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Christoffersen T, Riis T, Sonne DP, Klarskov N. Single-dose Tadalafil Reduces Opening Urethral Pressure: A Randomized, Double-blind, Placebo-controlled, Crossover Trial in Healthy Women. Int Urogynecol J 2024; 35:723-729. [PMID: 38456894 PMCID: PMC11024010 DOI: 10.1007/s00192-024-05757-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 02/02/2024] [Indexed: 03/09/2024]
Abstract
INTRODUCTION AND HYPOTHESIS Phosphodiesterase enzymes are widely distributed in female urogenital tissues. Yet, the understanding of their physiological roles and the impact of phosphodiesterase inhibitors on lower urinary tract symptoms in women remains limited. Current hypotheses are conflicting: one suggests that vasodilation might expand the periurethral vascular plexus, leading to increased urethral pressure, whereas the other proposes a relaxation of urethral musculature, resulting in decreased pressure. To further clarify this, we investigated the effect of tadalafil on the opening urethral pressure and voiding function in healthy women. METHODS We conducted a randomized, double-blind, placebo-controlled crossover trial involving 24 healthy women. Participants were randomly assigned to receive a single dose of tadalafil (40 mg) or placebo during their initial visit and then switched to the alternative treatment during their second visit. Opening urethral pressure was measured with urethral pressure reflectometry during both resting and squeezing conditions of the pelvic floor. Subsequently, voiding parameters were recorded. RESULTS Compared with placebo, a single dose of tadalafil significantly reduced opening urethral pressure during both resting (-6.8 cmH20; 95% confidence interval [CI], -11.8 to -1.9; p = 0.009) and squeezing conditions (-8.8 cmH20; 95% CI, -14.6 to -3.1; p = 0.005). Voiding parameters did not show significant differences (average flow rate: -0.8 ml/s [95% CI, -2.0 to 0.4; p = 0.2]; maximum flow rate: -1.7 ml/s [95% CI, -4.8 to 1.5; p = 0.3]). CONCLUSIONS A single dose of 40 mg tadalafil moderately reduced urethral pressure in healthy women, without affecting voiding parameters. The clinical implications of this are yet to be determined.
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Affiliation(s)
- Thea Christoffersen
- Department of Clinical Pharmacology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, Denmark.
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
| | - Troels Riis
- Department of Clinical Pharmacology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, Denmark
| | - David P Sonne
- Department of Clinical Pharmacology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Bispebjerg Bakke 23, 2400, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Niels Klarskov
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
- Department of Gynecology and Obstetrics, Copenhagen University Hospital - Herlev and Gentofte, Herlev, Denmark
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Watt T, Christoffersen T, Brogaard MB, Bjorner JB, Bentzen J, Hahn CH, Nygaard B, Feldt-Rasmussen U. Quality of life in thyroid cancer. Best Pract Res Clin Endocrinol Metab 2023; 37:101732. [PMID: 36732089 DOI: 10.1016/j.beem.2023.101732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
To explore the impact of differentiated thyroid cancer (DTC) on quality of life (QoL) a clinical analytical framework was developed. Based on the clinical analytical framework, a systematic literature search was performed to identify studies applying patient-reported outcomes (PRO) instruments among patients with DTC. Subsequently, the scope was narrowed down to studies comparing scores on the Medical Outcomes Study (MOS) Short form 36 (SF-36) to a reference population (clinical interpretability criterion). Further, the currently available thyroid cancer (TC) specific QoL PROs were review in accordance with the standards of the International Society of Quality of Life Research. In the initial search, 213 studies were included. The additional 'clinical interpretability'-criteria, limited the final study sample to 16 studies, 13 cross-sectional and 3 longitudinal. QoL was impacted across all SF-36 scales. The impact was generally modest and the impact was impeded by time since diagnosis and treatment. Four TC specific instruments were identified. Generally, the documentation of their measurement properties, particularly content validity and clinical validity, including substantial quantitative validation, was scarce. As was the cross-cultural applicability of the currently available instruments. This restricted, focused, clinically founded review showed an impact on a broad range of QoL issues. There is a need for large-scale measurement of QoL outcome longitudinally, using well-validated PRO instruments in order to identify with certainty the impact on subgroups.
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Affiliation(s)
- Torquil Watt
- Department of Endocrinology and Metabolism, Copenhagen University Hospital - Herlev and Gentofte, Herlev, Denmark; Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
| | - Thea Christoffersen
- Department of Clinical Pharmacology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Mathilde Borring Brogaard
- Department of Endocrinology and Metabolism, Copenhagen University Hospital - Herlev and Gentofte, Herlev, Denmark
| | - Jakob Bue Bjorner
- QualityMetric Incorporated, LLC, Johnston, RI, USA; Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bentzen
- Department of Oncology, Copenhagen University Hospital - Herlev and Gentofte, Herlev, Denmark
| | - Christoffer Holst Hahn
- Department of Otorhinolaryngology and Neck Surgery, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark
| | - Birte Nygaard
- Department of Endocrinology and Metabolism, Copenhagen University Hospital - Herlev and Gentofte, Herlev, Denmark
| | - Ulla Feldt-Rasmussen
- Department of Endocrinology and Metabolism, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark; Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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Windfeld‐Mathiasen J, Christoffersen T, Strand NAW, Dalhoff K, Andersen JT, Horwitz H. Psychiatric morbidity among men using anabolic steroids. Depress Anxiety 2022; 39:805-812. [PMID: 36281632 PMCID: PMC10092709 DOI: 10.1002/da.23287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/21/2022] [Accepted: 10/02/2022] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE The purpose of this study was to investigate the psychiatric morbidity among men with abuse of anabolic steroids. METHODS The design is a retrospectively matched cohort study. Five hundred and fourty-five males, who tested positive for anabolic steroids in Danish fitness centers during the period January 3, 2006 to March 1, 2018, were matched with 5450 randomly chosen male controls. Data was cross-referenced with seven national registers pertaining to information about education, employment status, and psychiatric comorbidity. Main outcomes and measures were prescription of psychopharmacological treatment. RESULTS The incidence of treatment with anxiolytics (HR: 2.34, 95% CI: 1.62-3.38) and antipsychotics (HR: 2.69, 95% CI: 1.99-3.63) displayed a remarkable increase in the years following doping sanction, compared to the control group. The prevalence of antidepressant use was already markedly elevated several years before doping sanction, but also displayed a higher incidence in the years following sanction (HR: 1.65, 95% CI: 1.28-2.13). The associations remained highly significant after controlling for socioeconomic factors. CONCLUSION Anabolic steroids use is strongly associated with psychiatric morbidity.
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Affiliation(s)
| | - Thea Christoffersen
- Department of Clinical PharmacologyBispebjerg and Frederiksberg HospitalCopenhagenDenmark
| | | | - Kim Dalhoff
- Department of Clinical PharmacologyBispebjerg and Frederiksberg HospitalCopenhagenDenmark
- Department of Clinical MedicineUniversity of CopenhagenCopenhagenDenmark
| | - Jon Trærup Andersen
- Department of Clinical PharmacologyBispebjerg and Frederiksberg HospitalCopenhagenDenmark
- Department of Clinical MedicineUniversity of CopenhagenCopenhagenDenmark
| | - Henrik Horwitz
- Department of Clinical PharmacologyBispebjerg and Frederiksberg HospitalCopenhagenDenmark
- Department of Clinical MedicineUniversity of CopenhagenCopenhagenDenmark
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4
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Windfeld-Mathiasen J, Christoffersen T, Horwitz H. [Not Available]. Ugeskr Laeger 2022; 184:V06220373. [PMID: 36426813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Anabolic steroid abuse is a growing health concern due to its relatively prevalent use and adverse health effects. These drugs cause significant disturbances of the body's endocrine system, and the most common somatic adverse drug reactions are gynaecomastia, infertility, testicular dysfunction, and acne. Furthermore, the use of anabolic steroids is associated with a variety of psychiatric disorders and antisocial behaviour as summarised in this review.
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Affiliation(s)
| | - Thea Christoffersen
- Klinisk Farmakologisk Afdeling, Københavns Universitetshospital - Bispebjerg og Frederiksberg Hospital
| | - Henrik Horwitz
- Klinisk Farmakologisk Afdeling, Københavns Universitetshospital - Bispebjerg og Frederiksberg Hospital
- Afdeling for Klinisk Medicin, Københavns Universitet
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Christoffersen T, Kornholt J, Riis T, Sonne J, Sonne DP, Klarskov N. Effect of single doses of citalopram and reboxetine on urethral pressure: A randomized, double-blind, placebo- and active-controlled three-period crossover study in healthy women. Neurourol Urodyn 2022; 41:1482-1488. [PMID: 35771361 PMCID: PMC9542537 DOI: 10.1002/nau.24985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/16/2022] [Accepted: 05/24/2022] [Indexed: 11/10/2022]
Abstract
AIMS Urethral closure function is essential for urinary continence in women and decreased urethral pressure is associated with stress urinary incontinence (SUI). For decades, the effects of serotonergic drugs on central neural control of urethral closure have been investigated and discussed. Epidemiological studies suggest that the use of selective serotonin reuptake inhibitors (SSRIs), such as citalopram, is associated with SUI. However, the literature findings are conflicting. This study aimed to evaluate citalopram's effect on opening urethral pressure (OUP) in healthy women. METHODS We conducted a randomized, double-blind, placebo- and active-controlled crossover study in 24 healthy women. On three study days, which were separated by 8 days of washout, the subjects received single doses of either 40 mg citalopram (and placeboreboxetine ), 8 mg reboxetine (and placebocitalopram ), or two placebos. Study drugs were administered at a 1-h interval due to a difference in estimated time to peak plasma concentration (tmax ). We measured OUP with urethral pressure reflectometry under both resting and squeezing conditions of the pelvic floor at estimated tmax for both study drugs (one timepoint). RESULTS Compared to placebo, citalopram increased OUP by 6.6 cmH2 0 (95% confidence interval [CI] 0.04-13.1, p = 0.048) in resting condition. In squeezing condition, OUP increased by 7.1 cmH2 0 (95% CI: 1.3-12.9, p = 0.01). Reboxetine increased OUP by 30.0 cmH2 0 in resting condition compared to placebo (95% CI: 23.5-36.5, p < 0.001), and 27.0 cmH2 0 (95% CI: 21.2-32.8, p < 0.001) in squeezing condition. CONCLUSION Citalopram increased OUP slightly compared to placebo suggesting that SSRI treatment does not induce or aggravate SUI.
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Affiliation(s)
- Thea Christoffersen
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonatan Kornholt
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Troels Riis
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Sonne
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - David P Sonne
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels Klarskov
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Gynecology and Obstetrics, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark
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Boesen VB, Borresen SW, Christoffersen T, Klose M, Watt T, Feldt-Rasmussen U. The effect of dual-release versus conventional hydrocortisone on fatigue, measured by ecological momentary assessments. Endocrine 2021; 71:467-475. [PMID: 33063273 DOI: 10.1007/s12020-020-02507-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 09/23/2020] [Indexed: 11/26/2022]
Abstract
PURPOSE Replicating the physiological cortisol secretion is key in the treatment of glucocorticoid insufficient individuals and optimization may enhance quality of life. The study investigates fatigue measured by ecological momentary assessments in patients treated with conventional hydrocortisone compared with once-daily dual-release hydrocortisone (Plenadren). METHODS A 21-week open-label switch pilot trial included 30 patients with adrenal insufficiency due to hypopituitarism. Fatigue was assessed four times daily for 20 days using a momentary item version of the Multidimensional Fatigue Inventory on patients' usual hydrocortisone regimen. Participants switched treatment to an identical daily dose of Plenadren for 16 weeks where fatigue assessments were repeated. Change in fatigue and diurnal variation of fatigue was analyzed using mixed models for repeated measurements. RESULTS In four out of five fatigue subscales fatigue was significantly reduced 0.7-1.1 points (scales ranging from 4 to 20), when treated with Plenadren compared with conventional hydrocortisone, corresponding to small effect sizes below the scale-specific minimal important changes. However, 33% of the participants completing the study (9/27) experienced reductions in fatigue above the minimal important change. On Plenadren, we found larger between-person variances and smaller within-person variances. Finally, we identified diurnal fatigue curves for both treatments. CONCLUSIONS The Plenadren-related reduction in fatigue was significant but not necessarily of clinical importance when looking at a group level. However, there was a large interindividual variation in treatment effect, why patients with a large benefit in quality of life should be identified. Future RCTs should be powered to detect the effect magnitudes identified here.
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Affiliation(s)
- Victor Brun Boesen
- Department of Endocrinology and Metabolism, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Stina Willemoes Borresen
- Department of Endocrinology and Metabolism, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Thea Christoffersen
- Department of Endocrinology and Metabolism, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Marianne Klose
- Department of Endocrinology and Metabolism, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Torquil Watt
- Department of Endocrinology and Metabolism, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
- Department of Internal Medicine, Copenhagen University Hospital Herlev Gentofte, Gentofte, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulla Feldt-Rasmussen
- Department of Endocrinology and Metabolism, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Alarkawi D, Bliuc D, Tran T, Ahmed LA, Emaus N, Bjørnerem A, Jørgensen L, Christoffersen T, Eisman JA, Center JR. Impact of osteoporotic fracture type and subsequent fracture on mortality: the Tromsø Study. Osteoporos Int 2020; 31:119-130. [PMID: 31654084 DOI: 10.1007/s00198-019-05174-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 09/18/2019] [Indexed: 11/25/2022]
Abstract
UNLABELLED Less is known about the impact of non-hip non-vertebral fractures (NHNV) on early death. This study demonstrated increased risk of dying following hip and NHNV fractures which was further increased by a subsequent fracture. This highlights the importance of early intervention to prevent both initial and subsequent fractures and improve survival. INTRODUCTION Osteoporotic fractures are a major health concern. Limited evidence exists on their impact on mortality in ageing populations. This study examined the contribution of initial fracture type and subsequent fracture on mortality in a Norwegian population that has one of the highest rates of fractures. METHODS The Tromsø Study is a prospective population-based cohort in Norway. Women and men aged 50+ years were followed from 1994 to 2010. All incident hip and non-hip non-vertebral (NHNV) fractures were registered. NHNV fractures were classified as either proximal or distal. Information on self-reported co-morbidities, lifestyle factors, general health and education level was collected. Multivariable Cox models were used to quantify mortality risk with incident and subsequent fractures analysed as time-dependent variables. RESULTS Of 5214 women and 4620 men, 1549 (30%) and 504 (11%) sustained a fracture, followed by 589 (38%) and 254 (51%) deaths over 10,523 and 2821 person-years, respectively. There were 403 (26%) subsequent fractures in women and 68 (13%) in men. Hip fracture was associated with a two-fold increase in mortality risk (HR 2.05, 95% CI 1.73-2.42 in women and 2.49, 95% CI 2.00-3.11 in men). Proximal NHNV fractures were associated with 49% and 81% increased mortality risk in women and men (HR 1.49, 95% CI 1.21-1.84 and 1.81, 95% CI 1.37-2.41), respectively. Distal NHNV fractures were not associated with mortality. Subsequent fracture was associated with 89% and 77% increased mortality risk in women and men (HR 1.89, 95% CI 1.52-2.35 and 1.77, 95% CI 1.16-2.71), respectively. CONCLUSION Hip, proximal NHNV and subsequent fractures were significantly associated with increased mortality risk in the elderly, highlighting the importance of early intervention.
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Affiliation(s)
- D Alarkawi
- Bone Biology Division, Garvan Institute of Medical Research, Sydney, Australia.
| | - D Bliuc
- Bone Biology Division, Garvan Institute of Medical Research, Sydney, Australia
| | - T Tran
- Bone Biology Division, Garvan Institute of Medical Research, Sydney, Australia
| | - L A Ahmed
- Institute of Public Health, United Arab Emirates University, Al Ain, UAE
| | - N Emaus
- Department of Health and Care Sciences, UiT, The Arctic University of Norway, Tromsø, Norway
| | - A Bjørnerem
- Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
- Department of Obstetrics and Gynecology, University Hospital of North Norway, Tromsø, Norway
| | - L Jørgensen
- Department of Health and Care Sciences, UiT, The Arctic University of Norway, Tromsø, Norway
| | - T Christoffersen
- Department of Health and Care Sciences, UiT, The Arctic University of Norway, Tromsø, Norway
- Finnmark Hospital Trust, Hammerfest, Norway
| | - J A Eisman
- Bone Biology Division, Garvan Institute of Medical Research, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
- Clinical School, St Vincent's Hospital, Sydney, Australia
- School of Medicine Sydney, University of Notre Dame, Sydney, Australia
| | - J R Center
- Bone Biology Division, Garvan Institute of Medical Research, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
- Clinical School, St Vincent's Hospital, Sydney, Australia
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Christoffersen T, Andersen JT, Dalhoff KP, Horwitz H. Anabolic-androgenic steroids and the risk of imprisonment. Drug Alcohol Depend 2019; 203:92-97. [PMID: 31421475 DOI: 10.1016/j.drugalcdep.2019.04.041] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/15/2019] [Accepted: 04/26/2019] [Indexed: 01/02/2023]
Abstract
BACKGROUND The use of Anabolic-Androgenic Steroids (AAS) has been associated with increased aggressiveness and violent behavior. We therefore investigated the proposed correlation between the use of AAS and criminality while controlling for important socio-economics covariates and for psychiatric comorbidity. METHODS The primary endpoints were prison sentences, and time to first prison sentence. A retrospective matched cohort study design consisting of 545 males, who tested positive for AAS in Danish gyms during the period January 3, 2006 to January 31, 2017. They were matched with 5450 randomly chosen male controls. Data were cross-referenced with national register information on education, employment status, substance abuse and psychiatric comorbidity. In addition, 638 males sanctioned because they rejected to participate in the doping control and 6380 controls were used as a replication cohort. RESULTS Already at baseline, 20.6% of the AAS users had a previous prison sentence whereas the rate was 3.7% in the control cohort (p < 0.0001). During the follow-up period the cumulative prevalence increased to 29.5% and 4.9%, respectively (unadjusted HR 9.15, 95% CI 6.33-13.20). The associations remained highly significant after controlling for socio-economic factors, drug abuse and psychiatric comorbidity. The results could be replicated in a similar cohort. CONCLUSION Our study shows that AAS users have a 9-fold increased risk of being convicted of a crime compared to matched controls, randomly chosen from the general population. This association could not be explained by common socioeconomic factors or by psychiatric comorbidity.
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Affiliation(s)
- Thea Christoffersen
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark.
| | - Jon Trærup Andersen
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark; Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
| | - Kim Peder Dalhoff
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark; Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
| | - Henrik Horwitz
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark; Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
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Hamfjord J, Guren T, Dajani O, Glimelius B, Sorbye H, Pfeiffer P, Christoffersen T, Lingjærde O, Tveit K, Kure E, Pallisgaard N, Spindler K. Total circulating cell-free DNA (cfDNA) as a prognostic biomarker in metastatic colorectal cancer prior to first-line oxaliplatin-based chemotherapy. Ann Oncol 2018. [DOI: 10.1093/annonc/mdy149.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Christoffersen T, Emaus N, Dennison E, Furberg AS, Gracia-Marco L, Grimnes G, Nilsen OA, Vlachopoulos D, Winther A, Ahmed LA. The association between childhood fractures and adolescence bone outcomes: a population-based study, the Tromsø Study, Fit Futures. Osteoporos Int 2018; 29:441-450. [PMID: 29147750 PMCID: PMC6124640 DOI: 10.1007/s00198-017-4300-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 11/02/2017] [Indexed: 10/18/2022]
Abstract
UNLABELLED Childhood fracture may predict persistent skeletal fragility, but it may also reflect high physical activity which is beneficial to bone development. We observe a difference in the relationship between previous fracture and bone outcome across physical activity level and sex. Further elaboration on this variation is needed. PURPOSE Childhood fracture may be an early marker of skeletal fragility, or increased levels of physical activity (PA), which are beneficial for bone mineral accrual. This study investigated the association between a previous history of childhood fracture and adolescent bone mineral outcomes by various PA levels. METHODS We recruited 469 girls and 492 boys aged 15-18 years to this study. We assessed PA levels by questionnaire and measured areal bone mineral density (aBMD) and bone mineral content (BMC) using dual-energy X-ray absorptiometry (DXA) at arm, femoral neck (FN), total hip (TH), and total body (TB) and calculated bone mineral apparent density (BMAD, g/cm3). Fractures from birth to time of DXA measurements were retrospectively recorded. We analyzed differences among participants with and without fractures using independent sample t test. Multiple linear regression was used to examine the association between fractures and aBMD and BMC measurements according to adolescent PA. RESULTS Girls with and without a previous history of fracture had similar BMC, aBMD, and BMAD at all sites. In multiple regression analyses stratified by physical activity intensity (PAi), there was a significant negative association between fracture and aBMD-TH and BMC-FN yet only in girls reporting low PAi. There was a significant negative association between forearm fractures, BMAD-FN, and BMAD-arm among vigorously active boys. CONCLUSION Our findings indicate a negative association between childhood fractures and aBMD/BMC in adolescent girls reporting low PAi. In boys, such an association appears only in vigorously active participants with a history of forearm fractures.
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Affiliation(s)
- T Christoffersen
- Department of Health and Care Sciences, UiT The Arctic University of Norway, Forskningsparken, Sykehusveien 21, 9037, Tromsø, Norway.
- Finnmark Hospital Trust, Alta, Norway.
| | - N Emaus
- Department of Health and Care Sciences, UiT The Arctic University of Norway, Forskningsparken, Sykehusveien 21, 9037, Tromsø, Norway
| | - E Dennison
- MRC Lifecourse Epidemiology Unit, Southampton, UK
- Victoria University, Wellington, New Zealand
| | - A-S Furberg
- Department of Community Medicine, UiT The Arctic University of Norway, Tromsø, Norway
- Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway
| | - L Gracia-Marco
- PROFITH "PROmoting FITness and Health through physical activity" Research Group, Department of Physical Education and Sports, Faculty of Sport Sciences, University of Granada, Granada, Spain
- Growth, Exercise, Nutrition and Development Research Group, University of Zaragoza, Zaragoza, Spain
| | - G Grimnes
- Division of Internal Medicine, University Hospital of North Norway, Tromsø, Norway
- Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
| | - O A Nilsen
- Department of Health and Care Sciences, UiT The Arctic University of Norway, Forskningsparken, Sykehusveien 21, 9037, Tromsø, Norway
| | - D Vlachopoulos
- Children's Health and Exercise Research Centre, Sport and Health Sciences, University of Exeter, Exeter, UK
| | - A Winther
- Division of Neurosciences, Orthopedics and Rehabilitation Services, University Hospital of North Norway, Tromsø, Norway
| | - L A Ahmed
- Department of Health and Care Sciences, UiT The Arctic University of Norway, Forskningsparken, Sykehusveien 21, 9037, Tromsø, Norway
- Institute of Public Health, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, UAE
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Boesen VB, Christoffersen T, Watt T, Borresen SW, Klose M, Feldt-Rasmussen U. PlenadrEMA: effect of dual-release versus conventional hydrocortisone on fatigue, measured by ecological momentary assessments: a study protocol for an open-label switch pilot study. BMJ Open 2018; 8:e019487. [PMID: 29362269 PMCID: PMC5786125 DOI: 10.1136/bmjopen-2017-019487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
INTRODUCTION Patients with adrenal insufficiency have impaired health-related quality of life (QoL). The dual-release hydrocortisone preparation, Plenadren, has been developed to mimic the physiological cortisol release more closely than conventional hydrocortisone treatment. Plenadren has been shown to improve QoL, in particular fatigue, in patients with primary adrenal insufficiency. However, the effect has not been investigated in patients with secondary adrenal insufficiency; furthermore, no study has taken the diurnal variation of fatigue into account. To assess diurnal variations, it is necessary to use repeated daily measurements, such as ecological momentary assessments (EMAs). This study aims to evaluate EMAs of fatigue as outcome in future large-scale randomised clinical trials. METHODS AND ANALYSIS The PlenadrEMA trial is an investigator-initiated open-label switch pilot trial of the effect of Plenadren versus conventional hydrocortisone on fatigue in patients with secondary adrenal insufficiency. The trial will include 30 participants. After 5 weeks on their usual hydrocortisone treatment, patients will be shifted to Plenadren for 16 weeks. Fatigue will be assessed using momentary versions of the Multidimensional Fatigue Inventory (MFI-20). Items will be administered to participants via a smartphone application four times daily during 20 days. Assessments will be performed before treatment shift and repeated after 12.5 weeks on Plenadren. The study will identify the best suited outcome for future randomised clinical trials, and in addition, estimate the variability and difference in fatigue between the two treatments to perform power calculations. ETHICS AND DISSEMINATION The trial will be conducted in accordance with the Declaration of Helsinki and has been approved by the Regional Scientific Ethical Committee in Copenhagen (ID: H-1-2014-073). All patients will receive written and verbal information about the trial and will give informed consent before enrolment. Findings will be published in peer-reviewed journals and presented at international conferences. TRIAL REGISTRATION NUMBER EudraCT201400203932.
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Affiliation(s)
- Victor Brun Boesen
- Department of Endocrinology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Thea Christoffersen
- Department of Endocrinology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Torquil Watt
- Department of Endocrinology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
- Department of Internal Medicine, Copenhagen University Hospital Herlev Gentofte, Denmark
| | | | - Marianne Klose
- Department of Endocrinology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Ulla Feldt-Rasmussen
- Department of Endocrinology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
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Ødegård J, Sondresen JE, Aasrum M, Tveteraas IH, Guren TK, Christoffersen T, Thoresen GH. Differential effects of epidermal growth factor (EGF) receptor ligands on receptor binding, downstream signalling pathways and DNA synthesis in hepatocytes. Growth Factors 2017; 35:239-248. [PMID: 29582692 DOI: 10.1080/08977194.2018.1453506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Hepatocytes are responsive to mitogenic effects of several ligands acting via EGFR. Studying primary cultures of rat hepatocytes, we found that, as compared to EGF, HB-EGF had a markedly higher affinity of the EGFR, while AR and TGFα had lower affinity. HB-EGF was also more potent compared to the other growth factors regarding phosphorylation of EGFR, Shc, ERK1/2 and Akt. All ligands induced phosphorylation of ErbB2, indicating receptor heterodimerization. TGFα, despite having much lower receptor affinity, was about equally potent and efficacious as HB-EGF as a stimulator of DNA synthesis. In contrast, EGF had relatively high affinity but markedly lower efficacy in stimulation of DNA synthesis. The results suggest that amplifying and/or inhibitory mechanisms may modulate the mitogenic responses downstream of the initial signalling steps, and that this may affect the effects of the EGFR ligands differentially.
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Affiliation(s)
- J Ødegård
- a Department of Pharmacology , Institute of Clinical Medicine, University of Oslo , Oslo , Norway
| | - J E Sondresen
- a Department of Pharmacology , Institute of Clinical Medicine, University of Oslo , Oslo , Norway
| | - M Aasrum
- a Department of Pharmacology , Institute of Clinical Medicine, University of Oslo , Oslo , Norway
| | - I H Tveteraas
- a Department of Pharmacology , Institute of Clinical Medicine, University of Oslo , Oslo , Norway
- b Department of Pharmacology , Oslo University Hospital , Oslo , Norway
| | - T K Guren
- c Department of Oncology , Oslo University Hospital , Oslo , Norway
| | - T Christoffersen
- a Department of Pharmacology , Institute of Clinical Medicine, University of Oslo , Oslo , Norway
| | - G H Thoresen
- a Department of Pharmacology , Institute of Clinical Medicine, University of Oslo , Oslo , Norway
- d Department of Pharmaceutical Biosciences, School of Pharmacy , University of Oslo , Oslo , Norway
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Christoffersen T, Nilsen O, Winther A, Furberg AS, Jorde R, Emaus N. Does the amount and degree of physical activity have an impact on bone? The Tromsø study—fit futures. Physiotherapy 2015. [DOI: 10.1016/j.physio.2015.03.432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Brusevold I, Tveteraas I, Aasrum M, Odegård J, Sandnes D, Christoffersen T. 516: Role of LPAR3, PKC and EGFR in LPA-induced cell migration in oral squamous carcinoma cells. Eur J Cancer 2014. [DOI: 10.1016/s0959-8049(14)50459-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Christoffersen T, Bjerrum L, Nielsen ABS. General practitioners do not systematically adhere to regional recommendations on treatment of uncomplicated urinary tract infections. Dan Med J 2014; 61:A4814. [PMID: 24814591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
INTRODUCTION Uncomplicated urinary tract infection (uUTI) is a common reason for seeing a GP. In Denmark, it is debated if sulfamethizole or pivmecillinam should be recommended for empirical treatment of uUTIs. We evaluated sulfamethizole and pivmecillinam use in the five Danish regions from 2007 to 2011 and explored if the choice of antibiotic in primary care was in accordance with the regional recommendations for uUTI. MATERIAL AND METHODS Regional drug use data on pivmecillinam and sulfamethizole from 2007 to 2011 were retrieved from the Registry of Medicinal Product Statistics. Regional recommendations from the same period were identified. We calculated differences in consumption based on defined daily doses per 1,000 inhabitants per day (DID) of pivmecillinam and sulfamethizole between the five regions, and intraregional developments. RESULTS Four regions had recommendations on uUTI in 2011. From 2007 to 2009, sulfamethizole was the only antibiotic recommended. Pivmecillinam was recommended along with sulfametizole in one of four regions from 2010, which increased to two regions in 2011. During the five-year period, sulfamethizole consumption decreased in all regions. The absolute decrease ranged from 0.4 to 0.6 DID. Pivmecillinam consumption increased steadily; the absolute increase ranged from 1.5 to 2.5 DID. During the whole period, the total pivmecillinam consumption was higher than the total sulfamethizole consumption. CONCLUSION Pivmecillinam dominated the treatment of uUTIs, whereas sulfamethizole prevailed in the regional recommendations, which suggests a lack of adherence to regional recommendations. FUNDING not relevant. TRIAL REGISTRATION not relevant.
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Affiliation(s)
- Thea Christoffersen
- Section and Research Unit of General Practice, Department of Public Health, University of Copenhagen, 1014 Copenhagen K, Denmark.
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Brusevold I, Aasrum M, Tveteraas I, Bryne M, Christoffersen T. 1055 POSTER Signalling Mechanisms Mediating EGF- and HGF-induced Migration in Carcinoma Cells in Vitro. Eur J Cancer 2011. [DOI: 10.1016/s0959-8049(11)70698-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Tveit K, Guren T, Glimelius B, Pfeiffer P, Sorbye H, Pyrhonen S, Kure E, Ikdahl T, Skovlund E, Christoffersen T. Randomized phase III study of 5-fluorouracil/folinate/oxaliplatin given continuously or intermittently with or without cetuximab, as first-line treatment of metastatic colorectal cancer: The NORDIC VII study (NCT00145314), by the Nordic Colorectal Cancer Biomodulation Group. J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.4_suppl.365] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
365 Background: The role of anti-EGFR therapy in first-line treatment of metastatic colorectal cancer (mCRC) is not established. In the present study pts were randomized to FLOX or FLOX + cetuximab until progression or FLOX intermittently + cetuximab continuously. Methods: Treatment arm A: Nordic FLOX (q2w): oxaliplatin 85 mg/m2day 1, 5-FU bolus 500 mg/m2 and FA 60 mg/m2 day 1-2; B: FLOX + cetuximab, initial dose 400 mg/m2, then 250 mg/m2/week; C: FLOX for 16 weeks + cetuximab continuously, with FLOX added at progression. Primary endpoint was progression-free survival (PFS). Results: Between May 05-Oct 07, 571 pts were randomized, 566 pts evaluable in intention to treat (ITT) analyses. Median age was 61 (24-74). ECOG status: 0=67%, 1=29%, 2=4%. KRAS and BRAF mutation (mut) analyses were obtained in 498 (87%) and 457 pts (81%), respectively. 40% of tumors had KRAS mut, 12% had BRAF mut. Cetuximab combined with Nordic FLOX did not significantly improve RR, PFS or OS compared to FLOX. KRAS mutation was not predictive for cetuximab effect. OS was similar for patients treated with FLOX intermittently and cetuximab continuously as for patients treated until progression. BRAF mutation was a strong negative prognostic factor (median OS 7.6 vs. 20.4 mo). Conclusions: Cetuximab did not add significant benefit to the Nordic FLOX regimen in first-line treatment of mCRC, irrespective of KRAS-mut. [Table: see text] [Table: see text]
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Affiliation(s)
- K. Tveit
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - T. Guren
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - B. Glimelius
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - P. Pfeiffer
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - H. Sorbye
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - S. Pyrhonen
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - E. Kure
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - T. Ikdahl
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - E. Skovlund
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
| | - T. Christoffersen
- Oslo University Hospital, Oslo, Norway; Akademiska University Hospital, Uppsala, Sweden; Department of Oncology, Odense University Hospital, Odense, Denmark; Haukeland University Hospital, Bergen, Norway; Turku University Hospital, Turku, Finland; University of Oslo, Oslo, Norway
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Sandnes D, Muller K, Tveteraas I, Aasrum M, Dawood M, Dajani O, Christoffersen T. 657 Protein kinase C and epidermal growth factor receptor signalling mediate growth stimulation by neurotensin in the colon carcinoma cell line HCT116. EJC Suppl 2010. [DOI: 10.1016/s1359-6349(10)71456-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Tveteraas I, Müller K, Dajani O, Guren T, Aasrum M, Ødegård J, Sandnes D, Christoffersen T. 552 Mechanisms of prostaglandin E2-induced transactivation of the EGF receptor in MH1C1 hepatoma cells. EJC Suppl 2010. [DOI: 10.1016/s1359-6349(10)71353-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Thoresen GH, Johasen EJ, Christoffersen T. Effects of cAMP on ERK mitogen-activated protein kinase activity in hepatocytes do not parallel the bidirectional regulation of DNA synthesis. Cell Biol Int 2001; 23:13-20. [PMID: 10527544 DOI: 10.1006/cbir.1998.0314] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have indicated that cAMP has bidirectional effects on epidermal growth factor (EGF)-induced DNA synthesis in cultured hepatocytes, acting to stimulate soon after plating (early G(1)) and to inhibit at later stages (nearer the G(1)/S transition). In this study we examined the role of the extracellular signal-regulated kinase (ERK) subgroup (p42/p44) of the mitogen activated protein (MAP) kinases both at growth-stimulatory and growth-inhibitory conditions. When added at low concentrations early during culturing, glucagon and 8-chlorophenylthio-cAMP (8-CPT-cAMP) did not increase MAP kinase activity, but enhanced the subsequent DNA synthesis. However, when administered at 24 h, glucagon and 8-CPT-cAMP decreased basal and EGF-induced MAP kinase activity and also inhibited EGF-induced DNA synthesis. Thus, although MAP kinase might play a role in the growth-inhibitory effect, it does not seem to be involved in growth-promoting regulation by cAMP in hepatocytes.
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Affiliation(s)
- G H Thoresen
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Oslo, N-0316, Norway
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Melien O, Sandnes D, Johansen EJ, Christoffersen T. Effects of pertussis toxin on extracellular signal-regulated kinase activation in hepatocytes by hormones and receptor-independent agents: evidence suggesting a stimulatory role of G(i) proteins at a level distal to receptor coupling. J Cell Physiol 2000; 184:27-36. [PMID: 10825231 DOI: 10.1002/(sici)1097-4652(200007)184:1<27::aid-jcp3>3.0.co;2-q] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
It was previously found that pertussis toxin (PTX) pretreatment inhibits the activation of extracellular signal-regulated kinases ERK1 (p44(mapk)) and ERK2 (p42(mapk)) in hepatocytes in response to either agonists that bind to heptahelical receptors or epidermal growth factor (EGF), suggesting a role of G(i) proteins in stimulatory mechanisms for ERK1/2. The present work shows that ERK1/2 is activated in a PTX-sensitive way not only by vasopressin, angiotensin II, prostaglandin (PG) F(2alpha), alpha(1)-adrenergic stimulation, and EGF but also by agents whose actions bypass receptors and stimulate protein kinase C (PKC) and/or elevate intracellular Ca(2+), such as 12-O-tetradecanoyl phorbol-13-acetate (TPA), exogenous phosphatidylcholine-specific phospholipase C (PC-PLC, from Bacillus cereus), thapsigargin, and the Ca(2+) ionophore A23187. Under the same conditions, PTX did not affect agonist stimulation of phosphoinositide-specific phospholipase C (PI-PLC) (IP(3) generation), and did not reduce the activation by these agents of phospholipase D (PLD). The results suggest that in hepatocytes a PTX-sensitive mechanism, presumably involving G(i) proteins, exerts a stimulatory effect on ERK at a level distal to receptor coupling, acting either as an integral part of the signaling pathway(s) or by a permissive, synergistic regulation.
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Affiliation(s)
- O Melien
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Blindern, Oslo, Norway.
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22
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Skarpen E, Lindeman B, Thoresen GH, Guren TK, Oksvold MP, Christoffersen T, Huitfeldt HS. Impaired nuclear accumulation and shortened phosphorylation of ERK after growth factor stimulation in cultured hepatocytes from rats exposed to 2-acetylaminofluorene. Mol Carcinog 2000; 28:84-96. [PMID: 10900465 DOI: 10.1002/1098-2744(200006)28:2<84::aid-mc4>3.0.co;2-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The hepatic carcinogen 2-acetylaminofluorene (AAF) exerts its effect as a tumor promoter by mitoinhibition of normal hepatocytes. Initiated cells proliferate selectively and develop into preneoplastic foci and subsequently into carcinomas. To study whether some of the mitoinhibitory effects of AAF could be attributed to an influence on intracellular signal transduction, growth factor signaling was studied in cultured hepatocytes from rats fed AAF for 7 d. Activation through the epidermal growth factor receptor (EGFR) was used to probe possible changes in downstream mitogenic signaling mechanisms. The proliferative response to epidermal growth factor (EGF), measured as proliferating cell nuclear antigen expression and thymidine incorporation, was almost completely inhibited in hepatocytes exposed to AAF. Neither EGFR protein levels nor EGF binding was notably altered in AAF-exposed hepatocytes as opposed to normal hepatocytes. The initial tyrosine phosphorylation of EGFR and downstream activation of Sos, Raf-1, and extracellular signal-regulated protein kinase (ERK) were similar in AAF-treated and control hepatocytes. Even though ERK phosphorylation was unaffected, a remarkable (80%) reduction of ERK nuclear accumulation was observed in AAF-exposed hepatocytes immediately after mitogen stimulation. EGFR tyrosine phosphorylation and downstream signaling lasted 6 h in control cells versus 2 h in AAF-exposed hepatocytes. We previously demonstrated that AAF inhibits the growth factor-dependent induction of cyclin D1 and arrests hepatocyte cell-cycle progression before the p21/CIP1-controlled DNA-damage check point. The present data indicate that the DNA-damaging carcinogen AAF induces growth inhibition by a distinct inhibition of ERK nuclear accumulation after mitogen stimulation. Inhibition of intracellular signal transduction may represent a novel mechanism of growth arrest. Mol. Carcinog. 28:84-96, 2000.
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Affiliation(s)
- E Skarpen
- Laboratory for Toxicopathology, Institute of Pathology, The National Hospital, University of Oslo, Oslo, Norway
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Dajani OF, Sandnes D, Melien O, Rezvani F, Nilssen LS, Thoresen GH, Christoffersen T. Role of diacylglycerol (DAG) in hormonal induction of S phase in hepatocytes: the DAG-dependent protein kinase C pathway is not activated by epidermal growth factor (EGF), but is involved in mediating the enhancement of responsiveness to EGF by vasopressin, angiotensin II, and norepinephrine. J Cell Physiol 1999; 180:203-14. [PMID: 10395290 DOI: 10.1002/(sici)1097-4652(199908)180:2<203::aid-jcp8>3.0.co;2-t] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The role of diacylglycerol (DAG) in hormonal induction of S phase was investigated in primary cultures of rat hepatocytes. In this model, several agonists that bind to G protein-coupled receptors act as comitogens when added to the cells soon after plating (i.e., in Go/early Gl phase), while the cells are most responsive to the mitogenic effect of epidermal growth factor (EGF) at 24-48 h of culturing (i.e., mid/late Gl). It was found that the cellular concentration of DAG rose markedly and progressively during the first 24 h of culturing. Exposure of the hepatocytes at 3 h to alpha1-adrenergic stimulation (norepinephrine with timolol), vasopressin, or angiotensin II further increased this rise, producing a sustained increase in the DAG level. Norepinephrine, which was the most efficient comitogen, produced the most prolonged DAG elevation. In contrast, no significant increase of DAG was found in response to EGF, neither at 3 nor at 24 h, using concentrations that markedly stimulated the ERK subgroup of the mitogen-activated protein kinases (MAPK) and DNA synthesis. Addition of Bacillus cereus phosphatidylcholine-specific phospholipase C (PC-PLC) strongly elevated DAG, while Streptomyces phospholipase D (PLD) increased phosphatidic acid (PA) but not DAG. B. cereus PC-PLC and the protein kinase C (PKC) activator tetradecanoyl phorbol-acetate (TPA), like norepinephrine, vasopressin, and angiotensin II, stimulated MAPK and enhanced the stimulatory effect of EGF on DNA synthesis. The PKC inhibitor GF109203X did not diminish the effect of EGF on MAPK or DNA synthesis, but strongly inhibited the effects of norepinephrine, vasopressin, angiotensin II, TPA and B. cereus PC-PLC on MAPK and almost abolished the enhancement by these agents of EGF-stimulated DNA synthesis. These results suggest that although generation of DAG is not a direct downstream response mediating the effects of the EGF receptor in hepatocytes, a sustained elevation of DAG with activation of PKC markedly increases the responsiveness to EGF. Mechanisms involving DAG and PKC seem to play a role in the comitogenic effects of various agents that bind to G protein-coupled receptors and activate the cells early in Gl, such as norepinephrine, angiotensin II, and vasopressin.
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Affiliation(s)
- O F Dajani
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway.
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Desdouets C, Thoresen GH, Senamaud-Beaufort C, Christoffersen T, Brechot C, Sobczak-Thepot J. cAMP-dependent positive control of cyclin A2 expression during G1/S transition in primary hepatocytes. Biochem Biophys Res Commun 1999; 261:118-22. [PMID: 10405333 DOI: 10.1006/bbrc.1999.0575] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
cAMP positively and negatively regulates hepatocyte proliferation but its molecular targets are still unknown. Cyclin A2 is a major regulator of the cell cycle progression and its synthesis is required for progression to S phase. We have investigated whether cyclin A2 and cyclin A2-associated kinase might be one of the targets for the cAMP transduction pathway during progression of hepatocytes through G1 and G1/S. We show that stimulation of primary cultured hepatocytes by glucagon differentially modulated the expression of G1/S cyclins. Glucagon indeed upregulated cyclin A2 and cyclin A2-associated kinase while cyclin E-associated kinase was unmodified. In conclusion, our study identifies cyclin A2 as an important effector of the cAMP transduction network during hepatocyte proliferation.
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Affiliation(s)
- C Desdouets
- INSERM U370, Faculté Necker, 156 rue de Vaugirard, Paris Cédex 15, 75730, France
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Guren TK, Abrahamsen H, Thoresen GH, Babaie E, Berg T, Christoffersen T. EGF-induced activation of Stat1, Stat3, and Stat5b is unrelated to the stimulation of DNA synthesis in cultured hepatocytes. Biochem Biophys Res Commun 1999; 258:565-71. [PMID: 10329425 DOI: 10.1006/bbrc.1999.0684] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Transcription factors of the STAT family have been implicated in regulation of cell proliferation. EGF activates several STAT proteins in liver. We have studied the relationship between STAT activation and the growth-stimulatory effect of EGF in rat hepatocytes, assessing specific DNA-binding activity of STAT proteins in electrophoretic mobility-shift and supershift assays. In freshly isolated hepatocytes, EGF activated Stat1, Stat3, and, particularly, Stat5b. However, the ability of EGF to produce this activation was rapidly attenuated when the cells were cultured, while the activation by IFN-gamma (Stat1) and IL-6 (Stat3) was sustained. Hepatocytes cultured for 24-48 h are highly sensitive to the stimulatory effect of EGF on S phase entry. In these cells EGF did not detectably activate Stat1, Stat3, or Stat5b but markedly stimulated MAP kinase (Erk1/2). Thus, although EGF has the ability to activate several STAT proteins, this did not seem to be part of the mitogenic mechanisms used by the EGF receptor in hepatocytes.
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Affiliation(s)
- T K Guren
- Faculty of Medicine, University of Oslo, Oslo, Norway.
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Sandnes D, Dajani O, Bjørneby A, Christoffersen T. The relationship between activation of phosphoinositide-specific phospholipase C and growth stimulation by Ca2+-mobilizing hormones in hepatocytes. Pharmacol Toxicol 1999; 84:234-40. [PMID: 10361980 DOI: 10.1111/j.1600-0773.1999.tb01488.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies have shown that while vasopressin and angiotensin II are markedly more effective than norepinephrine and prostaglandin F2alpha in eliciting an acute elevation of inositol 1,4,5-trisphosphate (IP3), norepinephrine and prostaglandin F2alpha produce larger enhancement of DNA synthesis. This suggests that the initial activation of phosphoinositide-specific phospholipase C is not a common factor for the growth response to these agonists, but does not exclude a role of the integral of phospholipase C activity over a prolonged part of the prereplicative period, during which agonist-specific changes in responsiveness might occur. We show that vasopressin and angiotensin II also cause a prolonged elevation of cellular IP3 levels. which remain elevated for at least 60 min., while norepinephrine and prostaglandin F2alpha elevate IP3 levels slightly and transiently For vasopressin the dose-effect curves for IP3 accumulation and stimulation of DNA synthesis were closely parallel, while this was not the case for angiotensin II, norepinephrine, or prostaglandin F2alpha. After cultivation of the hepatocytes, hormone-stimulated IP3 accumulation rapidly declined, particularly in response to norepinephrine and prostaglandin F2alpha. When the IP3 response to norepinephrine and prostaglandin F2alpha was completely down-regulated, these agonists still enhanced the DNA synthesis. These results suggest that other mechanisms in addition to IP3 accumulation and Ca2+ release are likely to be involved in the growth stimulatory effects of the Ca2+-mobilizing agonists studied here, in particular for angiotensin II, norepinephrine, and prostaglandin F2alpha.
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Affiliation(s)
- D Sandnes
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway.
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Lindeman B, Skarpen E, Thoresen GH, Christoffersen T, Wierød L, Madshus IH, Huitfeldt HS. Alteration of G1 cell-cycle protein expression and induction of p53 but not p21/waf1 by the DNA-modifying carcinogen 2-acetylaminofluorene in growth-stimulated hepatocytes in vitro. Mol Carcinog 1999; 24:36-46. [PMID: 10029409 DOI: 10.1002/(sici)1098-2744(199901)24:1<36::aid-mc6>3.0.co;2-i] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
2-Acetylaminofluorene (AAF) is a potent tumor promoter in rat liver carcinogenesis models. In the resistant hepatocyte model, AAF is combined with a growth stimulus for efficient promotion of preneoplastic lesions. The promoting property of AAF in this model is closely associated with mito-inhibition of normal hepatocytes, an effect to which initiated cells are resistant. How AAF induces growth arrest is not known, but genotoxic as well as non-genotoxic effects have been implicated. To elucidate the mechanisms of AAF-induced mito-inhibition, we studied the expression of the tumor suppressor protein p53 and the cyclin-dependent kinase (cdk) complexes mediating G1 progression and S-phase entry. Hepatocytes were isolated from male Fisher 344 rats fed either a control diet or a diet supplemented with 0.02% AAF for 1 wk and cultured in a defined serum-free medium containing epidermal growth factor, insulin, and dexamethasone. Thymidine labeling revealed a profound inhibition of DNA synthesis in AAF-exposed cells compared with control cells. The retinoblastoma protein did not become hyperphosphorylated in AAF-exposed cells. Thus, inhibition of G1 cyclin-cdk activity was implied as a cause of growth arrest. Indeed, G1 cell-cycle arrest was accompanied by reduced induction and nuclear accumulation of the cyclin D1-cdk4 complex and inhibited nuclear translocation of cdk2. Furthermore, the growth arrest was not mediated through p21/waf1 upregulation, although nuclear levels of p53 were increased. Thus, carcinogen-induced mito-inhibition may be effected by altered levels and localization of G1 cyclin-cdk complexes, independent of the upregulation of cdk inhibitory proteins.
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Affiliation(s)
- B Lindeman
- Institute of Pathology, The National Hospital, University of Oslo, Norway
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Abstract
OBJECTIVE To study if the Tono-Pen, a hand held digital tonometer, can replace Schiøtz tonometry in general practice. DESIGN Tonometry with Tono-Pen and Schiøtz tonometer were compared. SETTING Group practice with two general practitioners (GPs). PATIENTS 48 consecutive patients over 40 years of age. MAIN OUTCOME MEASURES The mean difference between intra ocular pressure (IOP) measured with the two methods with 95% confidence intervals and 95% limits of agreement between them. RESULTS One observer found a mean difference between methods of 0.3 mmHg and 95% limits of agreement of +/- 4 mmHg. The other observer with a different Schiøtz tonometer, had a mean difference of approximately -2 mmHg and 95% limits of agreement from -8 to +4 mmHg. CONCLUSION We consider the Tono-Pen to be an alternative to Schiøtz tonometry. The maximum mean difference between the methods for one GP, 1.9 mmHg, was within clinically acceptable limits. Possible reasons for the different agreement for the two observers are discussed.
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Skarpen E, Johannessen LE, Bjerk K, Fasteng H, Guren TK, Lindeman B, Thoresen GH, Christoffersen T, Stang E, Huitfeldt HS, Madshus IH. Endocytosed epidermal growth factor (EGF) receptors contribute to the EGF-mediated growth arrest in A431 cells by inducing a sustained increase in p21/CIP1. Exp Cell Res 1998; 243:161-72. [PMID: 9716460 DOI: 10.1006/excr.1998.4127] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the ability of endocytosed activated epidermal growth factor receptors (EGFR) to induce expression of the cyclin-interacting protein p21/CIP1 in A431 cells. Transforming growth factor alpha (TGFalpha) and EGF both induced tyrosine phosphorylation, induction of p21/CIP1, and thereby inhibition of DNA synthesis. TGFalpha is released from the EGFR when the TGFalpha-EGFR complex encounters low pH upon endocytosis. Consistently, we found more rapid dephosphorylation of the EGFR and less induction of p21/CIP1 by TGFalpha than by EGF. This difference was abolished upon neutralizing endosomal pH by the carboxylic ionophore monensin or the proton ATPase inhibitor bafilomycin A1. When surface-bound TGFalpha was removed by acid stripping and endosomal pH was neutralized with bafilomycin A1, TGFalpha stimulated EGFR tyrosine phosphorylation, induced p21/CIP1, and inhibited DNA synthesis. This strongly suggests that p21/CIP1 can be induced by endocytosed, activated EGFR and that endocytosed EGFR can affect cell growth.
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Affiliation(s)
- E Skarpen
- The National Hospital, The University of Oslo, Oslo, 0027, Norway
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Melien O, Thoresen GH, Sandnes D, Ostby E, Christoffersen T. Activation of p42/p44 mitogen-activated protein kinase by angiotensin II, vasopressin, norepinephrine, and prostaglandin F2alpha in hepatocytes is sustained, and like the effect of epidermal growth factor, mediated through pertussis toxin-sensitive mechanisms. J Cell Physiol 1998; 175:348-58. [PMID: 9572480 DOI: 10.1002/(sici)1097-4652(199806)175:3<348::aid-jcp13>3.0.co;2-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Several agents that act through G-protein-coupled receptors and also stimulate phosphoinositide-specific phospholipase C (PI-PLC), including angiotensin II, vasopressin, norepinephrine, and prostaglandin (PG) F2alpha, activated the ERK1 (p44mapk) and ERK2 (p42mapk) members of the mitogen-activated protein (MAP) kinase family in primary cultures of rat hepatocytes, measured as phosphorylation of myelin basic protein (MBP) by a partially purified enzyme, immunoblotting, and in-gel assays. All these agonists induced a peak activation (two to threefold increase in MBP-phosphorylation) at 3-5 min, followed by a brief decrease, and then a sustained elevation or a second increase of the MAP kinase activity that lasted for several hours. Although all the above agents also stimulated PI-PLC, implicating a Gq-dependent pathway, the elevations of the concentration of inositol (1,4,5)-trisphosphate did not correlate well with the MAP kinase activity. Furthermore, pretreatment of the cells with pertussis toxin markedly reduced the MAP kinase activation by angiotensin II, vasopressin, norepinephrine, or PGF2alpha. In addition, hepatocytes pretreated with pertussis toxin showed a diminished MAP kinase response to epidermal growth factor (EGF). The results indicate that agonists acting via G-protein-coupled receptors have the ability to induce sustained activation of MAP kinase in hepatocytes, and suggest that Gi-dependent mechanisms are required for full activation of the MAP kinase signal transduction pathway by G-protein-coupled receptors as well as the EGF receptor.
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Affiliation(s)
- O Melien
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Blindern, Norway
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31
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Thoresen GH, Guren TK, Sandnes D, Peak M, Agius L, Christoffersen T. Response to transforming growth factor alpha (TGFalpha) and epidermal growth factor (EGF) in hepatocytes: lower EGF receptor affinity of TGFalpha is associated with more sustained activation of p42/p44 mitogen-activated protein kinase and greater efficacy in stimulation of DNA synthesis. J Cell Physiol 1998; 175:10-8. [PMID: 9491776 DOI: 10.1002/(sici)1097-4652(199804)175:1<10::aid-jcp2>3.0.co;2-f] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The epidermal growth factor (EGF) receptor mediates the effects of both EGF and transforming growth factor alpha (TGFalpha). Recent data suggested that EGF acts as a partial agonist/antagonist in hepatocytes, TGFalpha exerting a larger maximal stimulation of DNA synthesis than EGF. To further study the mechanisms involved in mediating the different effects of EGF and TGFalpha, we have examined receptor binding of the two growth factors and their action on the p42/p44 mitogen-activated protein (MAP) kinase activity in hepatocytes. Single-ligand concentration curves and competition experiments showed that the binding affinity to a common population of surface binding sites was about 20-fold lower for TGFalpha than for EGF. MAP kinase activity responded to EGF and TGFalpha with different kinetics. While the two agents produced almost identical acute (5 min) stimulation (peak about fivefold), TGFalpha produced a more sustained MAP kinase activity than EGF. The difference between EGF and TGFalpha was still detectable 24 h after growth factor addition. The results show that in hepatocytes a lower receptor affinity of TGFalpha, as compared to EGF, is associated with a more sustained activation of the MAP kinase and a greater efficacy in the stimulation of DNA synthesis. This suggests that differential interaction of these two agents with the EGF receptor results in differences in the downstream events elicited at a given level of receptor occupancy. The data also are compatible with a role of a prolonged MAP kinase activity in the mitogenic effects of EGF and TGFalpha.
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Affiliation(s)
- G H Thoresen
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway.
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Dajani OF, Røttingen JA, Sandnes D, Horn RS, Refsnes M, Thoresen GH, Iversen JG, Christoffersen T. Growth-promoting effects of Ca(2+)-mobilizing agents in hepatocytes: lack of correlation between the acute activation of phosphoinositide-specific phospholipase C and the stimulation of DNA synthesis by angiotensin II, vasopressin, norepinephrine, and prostaglandin F2 alpha. J Cell Physiol 1996; 168:608-17. [PMID: 8816915 DOI: 10.1002/(sici)1097-4652(199609)168:3<608::aid-jcp13>3.0.co;2-v] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Although several hormones that promote hepatocyte proliferation also activate phosphoinositide-specific phospholipase C (PI-PLC) and mobilize Ca2+, the role of PI-PLC in the growth-stimulating effect of these agents is not clear. We have investigated this issue further, by exposing freshly isolated adult rat hepatocytes to vasopressin, angiotensin II, norepinephrine (in the presence of the beta-adrenoceptor blocker timolol) or PGF2 alpha, and examined both acute responses and the subsequent DNA synthesis when the cells were grown in monolayer culture. All the agonists elevated the level of inositol 1,4,5-trisphosphate (InsP3) and enhanced the DNA synthesis, amplifying the response to epidermal growth factor (EGF), and this comitogenic effect could be exerted by a single exposure of the cells 24 h prior to the addition of EGF. The acute activation of PI-PLC, measured as the early rise (peak 15-60 s) in InsP3, was 8-10-fold with vasopressin or angiotensin II, 3-4-fold with norepinephrine, and approximately 2-fold with PGF2 alpha. For all the agonists, a rise in cytosolic free Ca2+ in 100% of the cells and a maximal increase in glycogen phosphorylase activity were evoked at concentrations that approximately doubled the level of InsP3. However, the growth-stimulatory effects of these agonists showed a different order of efficacy as compared to the activation of PI-PLC; in terms of the maximal stimulation of DNA synthesis, the effects were: norepinephrine approximately PGF2 alpha > angiotensin II > vasopressin. Also, norepinephrine, PGF2 alpha, and angiotensin II, but not vasopressin, further enhanced the DNA synthesis when their concentrations were increased above those yielding maximal elevation of InsP3. In experiments where vasopressin and angiotensin II were combined, their effects on the DNA synthesis were additive while the InsP3 responses were not. The results show that the extent of the initial activation of PI-PLC is not the determinant for the magnitude of the growth effects of Ca(2+)-mobilizing hormones in hepatocytes. This suggests either (a) that the proliferative response to these agents is determined by the activity of PI-PLC at a later time, or its integral over an extended part of the prereplicative period, rather than by the acute activation, or (b) that additional, PI-PLC-independent, mechanisms are required.
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Affiliation(s)
- O F Dajani
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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33
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Sandnes D, Jacobsen FW, Refsnes M, Christoffersen T. 8-bromo-cAMP and 8-CPT-cAMP increase the density of beta-adrenoceptors in hepatocytes by a mechanism not mimicking the effect of cAMP. Pharmacol Toxicol 1996; 79:15-22. [PMID: 8841091 DOI: 10.1111/j.1600-0773.1996.tb00235.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Addition of 8-bromo-adenosine 3',5'-cyclic monophosphate (8-bromo-cAMP) or 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (8-CPT-cAMP) to hepatocytes at the time of plating enhanced the acquisition of beta-adrenoceptors that occurs spontaneously upon culturing as primary monolayers. This effect was partially suppressed by the phosphodiesterase inhibitor isobutyl methylxanthine, and was mimicked by 8-bromo-AMP, 8-bromo-adenosine, and the adenosine kinase inhibitor 5'-amino-5'-deoxyadenosine. Agents that elevated the intracellular level of cAMP, such as glucagon and forskolin, and Sp-8-bromo-adenosine 3',5'-monophosphorothioate (Sp-8-bromo-cAMPS), a cAMP analogue that is resistant towards metabolic breakdown, did not significantly enhance beta-adrenoceptor expression when used alone, but glucagon enhanced the effect of 8-bromo-adenosine. 8-bromo-cAMP and 8-bromo-adenosine decreased cellular ATP-levels. These observations suggest that the enhanced beta-adrenoceptor acquisition was mediated mainly through the action of metabolites of 8-bromo-cAMP and 8-CPT-cAMP, although there may be a cAMP-mediated component in the effect. Several mechanisms, including depletion of ATP, are probably involved, and might affect beta-adrenoceptor degradation.
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Affiliation(s)
- D Sandnes
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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34
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Guren TK, Thoresen GH, Dajani OF, Taraldsrud E, Moberg ER, Christoffersen T. Epidermal growth factor behaves as a partial agonist in hepatocytes: effects on DNA synthesis in primary culture and competition with transforming growth factor alpha. Growth Factors 1996; 13:171-9. [PMID: 8919025 DOI: 10.3109/08977199609003219] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The structurally related mitogens epidermal growth factor (EGF) and transforming growth factor (alpha (TGFalpha) are believed to exert all their effects via the same receptor. We have compared the effects of EGF and TGFalpha, and examined their interaction, on DNA synthesis in cultured rat hepatocytes. The potency of the two agents was similar, or slightly higher for EGF, but TGFalpha stimulated the DNA synthesis more efficiently, producing at high levels a rate of S phase entry that clearly exceeded (two to threefold) that obtained with maximally effective concentrations of EGF. While the hepatocytes became more sensitive both to TGFalpha and EGF when addition of the agents was postponed until late in the prereplicative period, TGFalpha exhibited higher efficacy than EGF both at early and late exposure. When EGF and TGFalpha were added together at 24 h, TGFalpha further enhanced the DNA synthesis in the presence of a saturating concentration (5 nM) of EGF, while EGF dose-dependently reduced the DNA synthesis in the presence of a high concentration (10 nM) of TGFalpha. The results show a lower efficacy of EGF than of TGFalpha, and, therefore, EGF displays the characteristics of a partial agonist in its EGF receptor-mediated growth stimulation in hepatocytes.
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Affiliation(s)
- T K Guren
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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Skarpen E, Lindeman B, Thoresen GH, Låg M, Christoffersen T, Huitfeldt HS. CCAAT/enhancer-binding protein (C/EBP) immunoreactivity during rat liver carcinogenesis. Histochem Cell Biol 1995; 104:287-94. [PMID: 8548562 DOI: 10.1007/bf01464324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To elucidate cell differentiation in liver carcinogenesis, we have studied the CCAAT/enhancer-binding protein (C/EBP). C/EBP is a positive-acting transcription factor important for the maintenance of liver-specific functions. It is associated with differentiation and regarded as an anti-proliferative agent. We have studied the expression and localization of C/EBP during sequential rat liver carcinogenesis. Two-color immunohistochemistry and confocal laser scan microscopy demonstrated C/EBP in hepatocyte nuclei and preneoplastic liver lesions, but not in bile ducts, non-parenchymal cells or oval cells. Both western blotting and immunohistochemistry revealed down-regulation of C/EBP during normal regeneration and when regeneration was inhibited by the carcinogen, 2-acetylaminofluorene. A similar down-regulation was shown by western blotting in hepatocytes grown in culture. Our data suggest that the altered metabolic phenotype of preneoplastic liver lesions was not caused by a change in the expression of C/EBP. Furthermore, the data favor a hepatocyte derivation of preneoplastic liver lesions.
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Affiliation(s)
- E Skarpen
- Laboratory for Toxicopathology, National Hospital (Rikshospitalet), University of Oslo, Norway
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Refsnes M, Dajani OF, Sandnes D, Thoresen GH, Røttingen JA, Iversen JG, Christoffersen T. On the mechanisms of the growth-promoting effect of prostaglandins in hepatocytes: the relationship between stimulation of DNA synthesis and signaling mediated by adenylyl cyclase and phosphoinositide-specific phospholipase C. J Cell Physiol 1995; 164:465-73. [PMID: 7650056 DOI: 10.1002/jcp.1041640304] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
While many observations indicate that prostaglandins may act as positive regulators of hepatocyte proliferation, the underlying mechanisms are not known. We have examined some of the signal pathways in the growth response induced by prostaglandins in hepatocytes, with particular focus on adenylyl cyclase and phosphoinositide-specific phospholipase C. Adult rat hepatocytes were cultured as primary monolayers in serum-free medium in the presence of EGF and insulin. PGE2 or PGF2 alpha (added 0-3 h after plating) enhanced the incorporation of [3H]-thymidine into DNA (measured at 50 h); at 100 microM the stimulation was about threefold PGI2 and PGD2 also showed significant but smaller stimulatory effects. No significant increase in the level of cyclic AMP (cAMP) was detected in response to any of the prostaglandins. Low concentrations of glucagon (0.1-10 nM), a potent activator of hepatic adenylyl cyclase, or 8-bromo-cAMP (0.1-10 microM) enhanced the DNA synthesis. When 8-bromo-cAMP was used in maximally effective concentrations, no further stimulation was obtained by combining it with glucagon, whereas the effects of PGE2 and 8-bromo-cAMP were completely additive. All the prostaglandins also showed additivity with the effect of glucagon on the DNA synthesis. PGE2, PGF2 alpha, PGI2, and PGD2 increased intracellular inositol-1,4,5-trisphosphate (InsP3), with a relative order of efficacy roughly corresponding to their activity as stimulators of DNA synthesis. Increases in cytosolic free Ca2+, as measured in single cells, were elicited in a majority of the hepatocytes by all these prostaglandins at 1 microM. Supramaximal concentrations of vasopressin, a strong activator of phospholipase C in hepatocytes, acted additively with PGE2 on the DNA synthesis. Pretreatment of the hepatocytes with a concentration of pertussis toxin that prevented the inhibitory effect of PGE2 on glucagon-induced cAMP accumulation did not abolish the ability of PGE2 to stimulate the DNA synthesis. The results do not support a role for adenylyl cyclase activation in the stimulatory effect of prostaglandins on hepatocyte growth. While the data are compatible with an involvement of phosphoinositide-specific phospholipase C in the growth-promoting effect of prostaglandins in cultured rat hepatocytes, they suggest this may not be the sole mechanism.
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Affiliation(s)
- M Refsnes
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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Thoresen GH, Refsnes M, Dajani OF, Johansen EJ, Christoffersen T. Dexamethasone inversely regulates DNA synthesis and phosphoenolpyruvate carboxykinase mRNA levels in cultured rat hepatocytes: interactions with insulin, glucagon, and transforming growth factor beta 1. Pharmacol Toxicol 1995; 76:163-70. [PMID: 7617540 DOI: 10.1111/j.1600-0773.1995.tb00124.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In hepatocytes, glucocorticoids control the expression of several genes and exert significant, but complex, regulation of the proliferation. To shed more light on the growth responses to glucocorticoids in these cells, we treated adult rat hepatocytes in primary culture with dexamethasone, in various combinations with other hormones (insulin, glucagon, transforming growth factor beta 1 (TGF beta 1)), and examined the relationship between the effects on the DNA synthesis and the mRNA level of phosphoenolpyruvate carboxykinase, a gene typically expressed in differentiated hepatocytes. Insulin exhibited the previously observed suppressing effect on the glucocorticoid-induced phosphoenolpyruvate carboxykinase mRNA level, and also reversed growth-inhibitory effects of the glucocorticoid. Dexamethasone and glucagon (via cAMP) acted strongly synergistically both in enhancing the phosphoenolpyruvate carboxykinase expression and inhibiting the growth, the inhibitory effect of glucagon on DNA synthesis being totally dependent on dexamethasone. The effects of dexamethasone plus glucagon on both the phosphoenolpyruvate carboxykinase mRNA abundance and the DNA synthesis were partially counteracted by insulin. Dexamethasone is permissive for a promoting effect of TGF beta 1 on phosphoenolpyruvate carboxykinase expression, and was found to increase the maximal inhibitory effect of (but reduced the sensitivity to) TGF beta 1 on the DNA synthesis. The results indicate that there is an inverse glucocorticoid-induced regulation of the DNA synthesis and the expression of a liver-typical gene.
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Affiliation(s)
- G H Thoresen
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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Christoffersen T. [The 1994 Nobel Prize in physiology and medicine. Signal transduction and g-proteins]. Tidsskr Nor Laegeforen 1994; 114:3562-3. [PMID: 7825126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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Dajani OF, Refsnes M, Guren TK, Horn RS, Thoresen GH, Christoffersen T. Elevated glucose concentrations inhibit DNA synthesis and expression of c-myc in cultured hepatocytes. Biochem Biophys Res Commun 1994; 202:1476-82. [PMID: 8060330 DOI: 10.1006/bbrc.1994.2097] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Glucose depressed DNA synthesis in rat hepatocytes in primary culture. As compared to controls cultured with 5.6 mM glucose, maximal (> or = 75%) inhibition was obtained at 20-30 mM, and half-maximal effect at 10-15 mM. Comparison of D- and L-glucose showed that the effect was specific for the D-form. Maximal inhibition required the presence of glucose during the first 24 hours of culture. The expression of the c-myc gene was reduced when the hepatocytes were cultured in the presence of elevated glucose. The responses to epidermal growth factor, insulin and vasopressin, in terms of percentual stimulation of DNA synthesis, were qualitatively similar at 5.6 and 16.8 mM glucose, while glucagon stimulated more strongly when the glucose concentration was increased; glucagon at concentrations > or = 1 nM reversed the inhibition by glucose. 8-Br-cAMP mimicked the effect of glucagon. These results suggest that an increase in the level of glucose depresses hepatocyte DNA synthesis. The effect is associated with lowered expression of the c-myc gene and is counteracted by cAMP.
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Affiliation(s)
- O F Dajani
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Blindern, Norway
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Refsnes M, Thoresen GH, Dajani OF, Christoffersen T. Stimulation of hepatocyte DNA synthesis by prostaglandin E2 and prostaglandin F2 alpha: additivity with the effect of norepinephrine, and synergism with epidermal growth factor. J Cell Physiol 1994; 159:35-40. [PMID: 8138589 DOI: 10.1002/jcp.1041590106] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previous data obtained in vivo and in vitro suggest that both prostaglandins (PGs) and catecholamines may have a role in promoting hepatocyte proliferation, and PGE2 and PGF2 alpha have also been implicated as mediators of the mitogenic actions of epidermal growth factor (EGF) (and transforming growth factor alpha [TGF alpha]). We have studied the effects of PGs and norepinephrine on DNA synthesis in serum-free primary cultures of rat hepatocytes, and compared the PG effects with those of norepinephrine. PGE2, PGF2 alpha, PGD2, and the synthetic analog dimethyl-PGE2 markedly enhanced the DNA synthesis. A more quantitative analysis of the effects of PGE2 and PGF2 alpha on the DNA synthesis, in the presence and absence of EGF, indicated that these PGs interacted in an essentially multiplicative manner with the effect of EGF. The effects of PGE2 and PGF2 alpha showed almost complete additivity with the stimulation of DNA synthesis produced by maximally effective concentrations of norepinephrine. The data suggest a) that PGE2 and PGF2 alpha facilitate and synergize with, rather than mediate, the actions of EGF in hepatocytes, and b) that this effect of the PGs occurs by mechanisms that are at least partly distinct from those of norepinephrine.
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Affiliation(s)
- M Refsnes
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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Thoresen GH, Christoffersen T. Transforming growth factor beta 1 increases the phosphoenolpyruvate carboxykinase mRNA level in cultured rat hepatocytes. Cell Biol Int 1994; 18:171-5. [PMID: 8019491 DOI: 10.1006/cbir.1994.1058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Transforming growth factor beta 1 (TGF beta 1) elevated the phosphoenolpyruvate carboxykinase (PEPCK) mRNA abundance in primary cultures of rat hepatocytes. Although this increase was not as large as the rise in PEPCK gene expression induced by the cAMP-elevating agents glucagon or isoproterenol, the effect of TGF beta 1 was several-fold and concentration-dependent, with ED50 at about 2.5 pM, which is in the same concentration range as the previously found growth-inhibitory effect of TGF beta. The data show that the level of mRNA for PEPCK, an enzyme typically expressed in the liver, can be regulated in the same direction by TGF beta 1 and cAMP.
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Affiliation(s)
- G H Thoresen
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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42
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Holtedahl K, Christoffersen T, Fors T, Ringberg U. Comparison between methods of tonometry: time for a change of approach. Br J Ophthalmol 1993; 77:754-5. [PMID: 8280700 PMCID: PMC504646 DOI: 10.1136/bjo.77.11.754-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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43
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Abstract
A retrospective study of 207 patients with chemical eye injuries in northern Norway revealed that fish bile was the causal agent in 14%. Fish bile caused superficial corneal erosions in 28 of 29 cases. All but one of the patients were professional fishermen or fish industry workers. In one case delayed medical care led to serious corneal opacity. Provided that there was immediate and abundant rinsing of the affected eye and good medical care, the prognosis of fish bile injuries was fairly good. The mechanisms for corneal damage due to fish bile are not clear.
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Affiliation(s)
- T Christoffersen
- Department of Ophthalmology, University Hospital, Tromsł, Norway
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44
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Sandnes D, Jacobsen FW, Refsnes M, Christoffersen T. Long-term inhibitory effect of cAMP on beta-adrenoceptor acquisition and nonselective attenuation of adenylyl cyclase in hepatocytes. Eur J Pharmacol 1993; 246:163-9. [PMID: 8397096 DOI: 10.1016/0922-4106(93)90094-p] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Long-term effects of cAMP on the surface expression of beta-adrenoceptors and adenylyl cyclase activity were investigated in primary cultures of rat hepatocytes. beta-Adrenoceptor density and catecholamine-responsive adenylyl cyclase activity increased during culturing in a biphasic manner, with a plateau of 10-20 h duration occurring approximately 10 h after plating. Treatment of hepatocyte cultures with 8-bromo-cAMP during the plateau period did not affect the density of beta-adrenoceptors. In contrast, addition of 8-bromo-cAMP, 8-chlorophenylthio-cAMP, forskolin or glucagon during a period of active recruitment of surface beta-adrenoceptors resulted in a suppression of the acquisition of beta-adrenoceptors. In both experimental situations there was a partial decrease in hormone-stimulated and basal adenylyl cyclase activity. The results suggest that cAMP exerts at least two types of long-term regulation of adenylyl cyclase in hepatocytes: a suppressive effect on beta-adrenoceptor acquisition, and a partial, nonselective decrease in adenylyl cyclase activity not involving beta-adrenoceptor down-regulation.
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Affiliation(s)
- D Sandnes
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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45
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Hansen C, Kristiansen T, Christoffersen T. High prevalence of myopia among medical students? Acta Ophthalmol 1993; 71:429. [PMID: 8362650 DOI: 10.1111/j.1755-3768.1993.tb07164.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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46
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Abstract
Intraocular pressure was measured in 132 consecutive patients over the age of 20 in a general practice with two general practitioners (GP). Tono-Pen tonometry was compared to Goldmann applantation tonometry in a masked, randomized design. Also, agreement between Tono-Pen measurements by the GPs and the ophthalmologist was estimated. Both mean difference between Tono-Pen and Goldmann applantation measurements and mean differences between Tono-Pen readings made by GPs and ophthalmologist were less than 1 mmHg. Ninety-five percent limits of agreement between the two methods were approximately -4.5 mmHg and 5.5 mmHg, and between observers approximately -4 mmHg and 5 mmHg. The Tono-Pen was agreeable both to patients and physicians. The GPs made as accurate measurements as the ophthalmologist. The wide limits of agreement are clinically much more important than the small differences between means. Random variation was much greater than systematic variation. Wide limits of agreement will apply to all known methods of clinical tonometry.
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47
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Abstract
A tonometry study comparing Tono-Pen with Goldmann applanation tonometry in a general practice setting revealed four cases of ocular hypertension in 132 patients. Two of the 4 patients required further ophthalmological care after referral. None of these patients, but 4 patients with no ocular hypertension, would have been referred for follow-up if referral had been made on the basis of the single reading made by the general practitioner. Tonometry readings are subject to considerable random variation, and the implications for a cut-off policy in general practice is discussed. Associations between ocular hypertension and known risk factors are weak and offer limited help in selecting asymptomatic patients for measurement. Systematic screening should not be a routine. The cut-off point should be kept low to avoid false reassurance of glaucoma patients, possibly as low as 17 mmHg. Multiple measurements may limit the number of referrals if the readings remain low.
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48
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Thoresen GH, Refsnes M, Christoffersen T. Inhibition of hepatocyte DNA synthesis by transforming growth factor beta 1 and cyclic AMP: effect immediately before the G1/S border. Cancer Res 1992; 52:3598-603. [PMID: 1319826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Previous studies have shown that both transforming growth factor beta (TGF-beta) and cyclic AMP (cAMP) inhibit hepatocyte DNA synthesis. While cAMP (in addition to being stimulatory in G0/early G1) exerts its inhibition on hepatocytes late in G1, the point where TGF-beta inhibits has not been precisely defined. We have now examined further the inhibitory effects of cAMP and TGF-beta 1 on DNA synthesis in primary rat hepatocyte cultures and, in particular, tried to determine where in the prereplicative period the cells are sensitive to these agents. Although a transient exposure to TGF-beta 1 (but not glucagon) during the first hours of the cell culturing led to inhibition of DNA synthesis, the cells were more sensitive at a point late in G1, where they also were inhibited by cAMP. Thus, exposure to TGF-beta 1, glucagon, or the cAMP analogue 8-chlorophenylthio-cAMP at a time when there was a continuous recruitment of cells to S phase strongly decreased the rate of S-phase entry. For both TGF-beta 1 and cAMP the inhibition was established within 1-2 h, the lag time being indistinguishable for the two agents. No evidence was found for a synergism between TGF-beta 1 and cAMP. Treatment with TGF-beta 1 did not detectably alter basal or glucagon-stimulated cAMP concentrations. The results suggest that in hepatocytes there is a process immediately before the G1/S border which is sensitive to both TGF-beta 1 and cAMP and which appears to represent a major point of inhibition.
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Affiliation(s)
- G H Thoresen
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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49
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Refsnes M, Thoresen GH, Sandnes D, Dajani OF, Dajani L, Christoffersen T. Stimulatory and inhibitory effects of catecholamines on DNA synthesis in primary rat hepatocyte cultures: role of alpha 1- and beta-adrenergic mechanisms. J Cell Physiol 1992; 151:164-71. [PMID: 1313818 DOI: 10.1002/jcp.1041510121] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Previous studies suggest that catecholamines may be involved in the regulation of liver growth. Considerable evidence implicates alpha 1-adrenergic mechanisms in the initiation of hepatocyte proliferation, while the role of beta-adrenoceptors is less clear. We have examined further the adrenergic regulation of hepatocyte DNA synthesis, using primary monolayer cultures. In hepatocytes that were also treated with epidermal growth factor and insulin, epinephrine or norepinephrine added early after the seeding strongly accelerated the rate of S phase entry. The beta-adrenergic agonist isoproterenol and the alpha-adrenergic agonist phenylephrine also stimulated the DNA synthesis, but were less efficient than epinephrine and norepinephrine. Experiments with the alpha 1-receptor blocker prazosine and the beta-receptor blocker timolol showed that the stimulatory effect of norepinephrine consisted of both an alpha 1- and a beta-adrenergic component. The alpha 1-component was most prominent in terms of maximal response at high concentrations of the agonist, but the beta-component contributed significantly and predominated at low concentrations (less than 0.1 microM) of norepinephrine. At later stages (about 40 h) of culturing norepinephrine strongly but reversibly inhibited the cells, acting at a point late in the G1 phase. This inhibition was mimicked by isoproterenol and abolished by timolol but was unaffected by prazosine, suggesting a beta-adrenoceptor-mediated effect. The results confirm the alpha 1-adrenoceptor-mediated stimulatory effect, but also show that beta-adrenoceptors may contribute to the growth stimulation by catecholamines. Furthermore, catecholamines, via beta-adrenoceptors and cyclic AMP, inhibit the G1-S transition, and may thus play a role in the termination of hepatic proliferation.
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MESH Headings
- Animals
- Catecholamines/pharmacology
- Cell Division/drug effects
- Cells, Cultured
- Cyclic AMP/physiology
- DNA/biosynthesis
- Dose-Response Relationship, Drug
- Epidermal Growth Factor/pharmacology
- Epinephrine/pharmacology
- G1 Phase/physiology
- Insulin/pharmacology
- Isoproterenol/pharmacology
- Liver/cytology
- Liver/metabolism
- Liver/ultrastructure
- Male
- Norepinephrine/pharmacology
- Phenylephrine/pharmacology
- Prazosin/pharmacology
- Rats
- Rats, Inbred Strains
- Receptors, Adrenergic, alpha/drug effects
- Receptors, Adrenergic, alpha/physiology
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/physiology
- S Phase/physiology
- Time Factors
- Timolol/pharmacology
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Affiliation(s)
- M Refsnes
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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50
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Gladhaug IP, Refsnes M, Christoffersen T. Regulation of surface expression of high-affinity receptors for epidermal growth factor (EGF) in hepatocytes by hormones, differentiating agents, and phorbol ester. Dig Dis Sci 1992; 37:233-9. [PMID: 1735341 DOI: 10.1007/bf01308177] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Freshly isolated adult rat hepatocytes exhibit a nonhomogeneous population of epidermal growth factor (EGF) receptors with about 10,000 high-affinity binding sites (Kd 20 pM) and about 200,000 low-affinity sites (Kd 600 pM) per cell. With culturing as primary monolayers under conditions where the cells show a marked increase in the sensitivity to the growth-stimulatory effect of EGF, a gradual reduction in the number of EGF receptors and an almost complete loss of high-affinity EGF receptors is seen. Insulin, which promotes growth of hepatocytes in concert with EGF, enhances the down-regulation of these high-affinity receptors. The differentiating (and growth-inhibitory) agent n-butyrate counteracts this down-regulation and preserves the high-affinity receptors. This effect of butyrate is synergistic with the glucocorticoid agent dexamethasone. Another differentiating agent, dimethylsulfoxide (DMSO), also counteracts the down-regulation of high-affinity EGF receptors. Moreover, the tumor promoter, tetradecanoylphorbol acetate (TPA), down-regulates the EGF receptor. This effect is particularly evident when studying the high-affinity receptors up-regulated by prior treatment with butyrate plus dexamethasone. Taken together these results provide strong support for the notion that an inverse relationship exists between expression of high-affinity EGF binding and responsiveness to growth activation by EGF.
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Affiliation(s)
- I P Gladhaug
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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