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Sexual and Reproductive Health Care after Gonadotoxic Treatment in Females at a Tertiary Pediatric Hospital. J Pediatr Adolesc Gynecol 2024:S1083-3188(24)00019-6. [PMID: 38253233 DOI: 10.1016/j.jpag.2024.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 01/05/2024] [Accepted: 01/15/2024] [Indexed: 01/24/2024]
Abstract
STUDY OBJECTIVES Recommendations from the Children's Oncology Group Long-Term Follow-Up (COG-LTFU) Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancer emphasize the importance of reproductive health care, yet little is known regarding adherence to these recommendations and non-fertility-related sexual and reproductive health (SRH) outcomes. METHODS Follow-up of outcomes on the basis of the COG-LTFU guidelines was assessed in female patients who underwent fertility preservation consultation before gonadotoxic therapy between 2016 and 2022 at a single institution and were at least 6 months from treatment completion. RESULTS We included 140 patients, with a mean time of 2.7 years from treatment completion. Eighty-six patients were 12 years old or older, of whom sexual activity was recorded in 59 (68.7%), and 12 of 31 (38.7%) sexually active patients underwent sexual function assessment. The 57 (66.3%) patients at high risk of premature ovarian insufficiency (POI) at diagnosis were more likely than minimal-risk counterparts (29, 33.7%) to have abnormal uterine bleeding (42.1% vs 17.2%, P = .03), to be diagnosed with POI (29.8% vs 0%, P = .01), and to have sexual activity recorded (77.2% vs 51.7%, P = .03). Of 17 patients with POI, 82.4% were on hormone replacement therapy, and 58.8% had undergone bone mineral density testing. CONCLUSION This study adds to the limited literature regarding non-fertility-related SRH outcomes after gonadotoxic therapy and illustrates opportunities to improve adherence to the COG-LTFU guidelines. Increased attention to SRH guidelines may increase detection and treatment of SRH conditions, improving the health and quality of life of female cancer survivors.
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Association between Individual versus Community-level Social Vulnerability and Neonatal Opioid Withdrawal Syndrome among Pregnant Individuals Receiving Buprenorphine for Opioid Use Disorder. Am J Perinatol 2023. [PMID: 37890511 DOI: 10.1055/a-2200-3187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
OBJECTIVE Individual patient-level measures of adverse social determinants of health are associated with neonatal opioid withdrawal syndrome (NOWS), but the relative impact of community-level adverse social determinants of health remains to be defined. We examined the association between community-level social vulnerability and NOWS among pregnant individuals receiving buprenorphine for opioid use disorder. STUDY DESIGN We conducted a secondary analysis of an established cohort of pregnant individuals and their infants participating in a multidisciplinary prenatal/addiction care program from 2013 to 2021. Addresses were geocoded using ArcGIS and linked at the census tract to the Centers for Disease Control and Prevention 2018 Social Vulnerability Index (SVI), incorporating 15 census variables. The primary exposure was the SVI as a composite measure of community-level social vulnerability, and secondarily, individual scores for four thematic domains (socioeconomic status, household composition and disability, minority status and language, and housing type and transportation). The primary outcome was a clinical diagnosis of NOWS defined as withdrawal requiring pharmacological treatment following buprenorphine exposure. RESULTS Among 703 pregnant individuals receiving buprenorphine, 39.8% (280/703) of infants were diagnosed with NOWS. Among our patinets, those who were nulliparous, had post-traumatic stress disorder, a term birth (≥ 37 weeks) and had a male infant were more likely to have an infant diagnosed with NOWS. Individuals with and without an infant diagnosed with NOWS had similarly high community-level social vulnerability per composite SVI scores (mean [standard deviation]: 0.6 [0.4-0.7] vs. 0.6 [0.4-0.7], p = 0.2]. In adjusted analyses, SVI, as a composite measure as well as the four domains, was not associated with NOWS diagnosis. CONCLUSION Among pregnant persons receiving buprenorphine enrolled in a multidisciplinary prenatal and addition care program, while individual risk factors that measure adverse social determinants of health were associated with an NOWS diagnosis in the infant, community-level social vulnerability as measured by the SVI was not associated with the outcome. KEY POINTS · Community-level SVI was not associated with neonatal opioid use disorder.. · Certain individual risk factors were identified as being associated with NOWS.. · Homogeneity of composite SVI scores may have led to lack of significant findings..
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3
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Associations between social vulnerability and hepatitis C virus in pregnant individuals with opioid use disorder. Am J Obstet Gynecol 2023. [DOI: 10.1016/j.ajog.2022.11.1017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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4
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Association between individual versus community-level social vulnerability and neonatal opiate withdrawal syndrome. Am J Obstet Gynecol 2023. [DOI: 10.1016/j.ajog.2022.11.1102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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5
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Hepatitis C virus in pregnant individuals with opioid use disorder and association with preterm birth. Am J Obstet Gynecol 2023. [DOI: 10.1016/j.ajog.2022.11.1027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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6
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Caloric intake in normal weight, overweight, and obese adolescents: circadian and homeostatic influences measured from 28-hour forced desynchrony (FD). Sleep Med 2019. [DOI: 10.1016/j.sleep.2019.11.153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
In this article we consider some of the implications of the UK Human Rights Act 1998 for nurses in practice. The Act has implications for all aspects of social life in Britain, particularly for health care. We provide an introduction to the discourse of rights in health care and discuss some aspects of four articles from the Act. The reciprocal relationship between rights and obligations prompted us to consider also the relationship between guidelines in the United Kingdom Central Council’s Code of professional conduct and the requirements of the Human Rights Act 1998. We conclude with the recommendation that the new legislation should be welcomed for its potential to support good practice and to urge critical and reflective practice rather than as yet another burdensome bureaucratic imposition.
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9
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Subdermal contraceptive implant: “typical use” in a California managed care setting. Contraception 2012. [DOI: 10.1016/j.contraception.2011.11.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
BACKGROUND Sufficient, appropriately trained health personnel need to be retained in the workforce, and their performance maintained, to achieve quality care. Mid-level ophthalmic personnel in Western Pacific Island Countries and Territories (WPICT) are no exception. AIM The study aims to assess influences on the quality of care provided by specialist mid-level ophthalmic personnel in WPICT and devise strategies to train, retain and maintain performance of these personnel. METHODS A situational assessment employed a checklist and semi-structured interviews with specialist mid-level ophthalmic personnel, nursing bodies and Ministry of Health representatives from seven WPICT. A selective literature review guided strategies to address the issues identified. RESULTS Appropriate training allows nurses to fulfill a mid-level role in WPICT as specialist ophthalmic nurses. Resources generally do not restrict practice. Nursing structures have generally failed to support professionalism: scope and conditions of service, clinical supervision, career structures, professional recognition and opportunities for continuing professional development are rudimentary. Ophthalmic nurses were dissatisfied with the lack of specialty recognition, career progression and salary increase. Regional and local strategies tailored to each country have been devised to establish sustainable processes for support. CONCLUSION Salary was a major cause of dissatisfaction. It should be addressed along with professional recognition and related processes. Without professional support, specialist and advanced cadres within nursing may cease to exist, nurses' performance may be affected or they may leave. Specialist ophthalmic nursing, recognized, situated within and properly supported by nursing structures can provide a model for specialist clinical care for other specialties and in other countries.
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Effects of ethane dimethane sulfonate on the functional structure of the adult rat testis. ARCHIVES OF ANDROLOGY 2003; 49:313-26. [PMID: 12851034 DOI: 10.1080/01485010390204922] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In ethane dimethane sulfonate (EDS)-treated adult Sprague Dawley rats, Leydig cells (LC) were not present up to 14 days but seen at 21 days. They increased in number thereafter and reached the values of age-matching controls (i.e., 150-day-old untreated) at day 60. Mesenchymal cell number per testis also increased and reached a peak at day 21, and remained at a higher (p<.05) value than the controls at days 28-60. LC were smaller at day 21, but were larger at days 28-60 (compared to untreated 90- and 150-day-old rats) and secreted more testosterone at day 60 compared to both control groups. Testes of treated rats had greater numbers of macrophages (except at day 28) and they were smaller than those in untreated rats and 60-day EDS rats. Immunolabeling studies on 3beta-HSD, 11beta-HSD1, and LH receptor activity and androgen data agreed with morphological findings. The relationship between mesenchymal and LC numbers during LC differentiation following EDS treatment is reminiscent of this process in prepubertal testis. The presence of increased numbers of macrophages in treated testes agreed with the role of macrophages on LC differentiation. The absence of aging signs in LC of 60-day treated rats who were 150 days of age can be attributed at least in part to their newly differentiated status in older rats (i.e., equivalent to pubertal LC and not to aged LC). Larger LC observed in EDS rats at days 28-60 and their increased testosterone secretory capacity at day 60 (compared to controls) are attributed to elevated plasma LH levels and locally produced factors in EDS rats.
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EDITORIAL. Vet Dermatol 2001. [DOI: 10.1046/j.1365-3164.2001.00245.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
The cells of the mesencephalic trigeminal nucleus (MTN) are the proprioceptive sensory neurons that innervate the jaw muscles. Interestingly, their evolution is generally thought to have been concomitant with that of the jaws. They are also the first born neurons of the mesencephalon, and their axons pioneer some of the major tracts within the brain. The cells of the MTN are also paradoxical in being the only group of intramedullary primary sensory neurons in amniotes. However, we know little about the early development of these important neurons, and we have analysed this here. To study the earliest stages of MTN development, we have used a battery of neural crest markers to try and pinpoint the progenitors of the MTN. We find that, contrary to current perceptions, the progenitors of the MTN are not highlighted by these markers, suggesting that they are not neural crest derived. However, the cells of the MTN are marked by means of their expression of Brn-3a. This gene labels cells that arise either side of the dorsal midline, extending rostrally from the isthmus across the roof of the mesencephalon. We have further demonstrated that the MTN develops under the influence of the Fgf-8 secreted by the isthmus. Ectopic Fgf-8 application promotes MTN development, whereas inhibiting Fgf-8 function in vivo drastically affects MTN development.
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Developmental expression of fibroblast growth factor (FGF) receptors in neural stem cell progeny. Modulation of neuronal and glial lineages by basic FGF treatment. Neurol Res 2001; 23:612-21. [PMID: 11547930 DOI: 10.1179/016164101101199090] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Neural stem cells (NSCs) are self-renewable, multipotential cells capable of differentiating into the three major neural cell types, but the mechanisms which regulate their development are not fully understood. Both basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) promote the proliferation of NSCs. However, studies on the role of FGFs in the differentiation of EGF-expanded NSCs are still incomplete. We have studied the expression of distinct FGF receptors (FGFRs) in the progeny of EGF-expanded NSCs isolated from E15 rat striatum. In situ hybridization analysis and immunocytochemistry showed a developmentally related expression pattern and a cell lineage-specific distribution of these receptors. FGFR1 and FGFR2 were identified in many early precursors and in the oligodendrocyte lineage. The latter receptor was also present in a subpopulation of astrocytes. FGFR3 was detected in a restricted population of early precursors, in oligodendroglial progenitors, and in neurons and protoplasmic astrocytes of late-term cultures. Basic FGF treatment of the progeny of NSCs increased the proliferative rate of precursors and the number of oligodendrocytes generated, whereas the number of differentiating neurons was significantly reduced. Together these data provide evidence that FGFs modulate the development of EGF-expanded NSCs, and that this is at least partly determined by a cell lineage-specific expression of multiple FGFRs.
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MESH Headings
- Animals
- Astrocytes/cytology
- Astrocytes/metabolism
- Bromodeoxyuridine
- Cell Compartmentation/physiology
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cell Division/drug effects
- Cell Division/physiology
- Cell Lineage/drug effects
- Cell Lineage/physiology
- Cells, Cultured
- Central Nervous System/cytology
- Central Nervous System/embryology
- Central Nervous System/growth & development
- Fibroblast Growth Factor 2/pharmacology
- Gene Expression Regulation, Developmental/physiology
- Immunohistochemistry
- Intermediate Filament Proteins/metabolism
- Nerve Tissue Proteins
- Nestin
- Neuroglia/cytology
- Neuroglia/drug effects
- Neuroglia/metabolism
- Neurons/cytology
- Neurons/drug effects
- Neurons/metabolism
- Oligodendroglia/cytology
- Oligodendroglia/metabolism
- Protein-Tyrosine Kinases
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor Protein-Tyrosine Kinases/drug effects
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptor, Fibroblast Growth Factor, Type 1
- Receptor, Fibroblast Growth Factor, Type 2
- Receptor, Fibroblast Growth Factor, Type 3
- Receptors, Fibroblast Growth Factor/drug effects
- Receptors, Fibroblast Growth Factor/genetics
- Receptors, Fibroblast Growth Factor/metabolism
- Stem Cells/cytology
- Stem Cells/drug effects
- Stem Cells/metabolism
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[Aromatase and breast cancer]. VOPROSY ONKOLOGII 2001; 47:182-6. [PMID: 11383454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Aromatase activity may be detected using in vitro and in vivo techniques in most breast cancers and mammary adipose tissue. This activity makes a variable contribution to endogenous estrogens within the breast and in many cases represents the major source of these hormones. Such local biosynthesis may maintain the growth of some hormone-dependent tumors. The factors which regulate aromatase activity within the breast are not defined but are likely to include growth factors and cytokines which may be produced by breast tissues so that autocrine and paracrine loops may exist. Estrogen biosynthesis within the breast, like other peripheral systems, appears sensitive to classical aromatase inhibitors and the new generation of drugs are capable of profoundly blocking the activity and markedly reducing endogenous estrogen levels; in turn these endocrine effects are translated in dramatic anti-tumor influences in hormone-dependent breast cancer.
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Spread of foot-and-mouth disease from the burning of animal carcases on open pyres. Vet Rec 2001; 148:585-6. [PMID: 11386443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Preliminary results indicate that no evidence has been found to support the spread of FMD virus from the burning of animal carcases on open pyres. This finding is subject to a number of assumptions, and is based on a limited number of case studies.
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Regulation and function of FGF8 in patterning of midbrain and anterior hindbrain. Biochem Cell Biol 2001; 78:577-84. [PMID: 11103948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
In this article, an adjunct to a platform presentation at the Winternational 2000 Symposium, we summarize the recent findings of this group concerning the regulation and functions of FGF8 expressed at the isthmus of the developing brain. We show that several different FGF8 isoforms, ectopically expressed in midbrain or posterior forebrain, are able to mimic the proliferative and patterning functions previously attributed to the isthmus in tissue grafting studies. Moreover, we also show that FGF8 protein is sufficient to induce an ectopic isthmic organiser (Fgf-8+, Gbx2+) in anterior midbrain. We also provide evidence that isthmic FGF8 patterns anterior hindbrain, repressing Hox-a2 expression and setting aside a territory of the brain that includes the cerebellar anlage. We show that these effects of FGF8 are likely to be mediated via FGFR1 and be modulated by the putative FGF antagonist, Sprouty2, identified using a differential display screen. Finally, we provide evidence that the onset of Fgf8 expression is regulated by En1 and that its expression at the isthmus is subsequently maintained by a specific and direct interaction between rhombomere 1 and midbrain.
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Inflammatory bowel disease. NURSING TIMES 2001; 97:33-5. [PMID: 11954328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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Gastric dysrhythmias occur in gastro-oesophageal reflux disease complicated by food regurgitation but not in uncomplicated reflux. Gut 2001; 48:212-5. [PMID: 11156642 PMCID: PMC1728202 DOI: 10.1136/gut.48.2.212] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AIM To investigate gastric pacemaker activity in gastro-oesophageal reflux disease using the electrogastrogram. PATIENTS Forty patients with gastro-oesophageal reflux disease (20 with acid reflux, 20 with the additional symptom of food regurgitation) and 30 asymptomatic controls. METHODS Patients were studied using an electrogastrogram, oesophageal manometry, and 24 hour ambulatory oesophageal pH analysis. RESULTS An abnormal electrogastrogram was recorded in two (7%) controls, two (10%) patients with acid reflux, and 10 (50%) patients with food regurgitation. Food regurgitators had significantly more gastric dysrhythmias (tachygastrias) both before (p<0.02) and after (p<0.01) a test meal. Gastric pacemaker activity was also significantly less stable following the test meal in food regurgitators (p<0.003). Patients with food regurgitation and an abnormal electrogastrogram had higher oesophageal acid exposure than those with a normal electrogastrogram (p<0.05). CONCLUSIONS The electrogastrogram is usually normal in gastro-oesophageal reflux disease but an abnormal rhythm occurred in half of our patients with the additional symptom of food regurgitation. Furthermore, an abnormal electrogastrogram is associated with increased oesophageal acid exposure.
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Abstract
Studies in Drosophila suggest that receptor-tyrosine phosphatases are key regulators of neural development, however little is known about their expression or function in the nervous system of vertebrate embryos. In this report, we describe the expression pattern of RPTPgamma during early chick embryogenesis. Transcripts are largely restricted to the developing nervous system including oculomotor, trochlear and branchiomotor populations but are absent from spinal motor neurones. RPTPgamma is also detected in cells in the positions of hindbrain reticulospinal neurones, spinal commisural neurones and in cells with neuronal morphology in the ventral diencephalon. Within the peripheral nervous system transcripts are found in neuroblasts delaminating from epibranchial placodes and subsequently in placode-derived cranial ganglia. Outside the nervous system expression is detected in somites and transiently in the second branchial arch and the cranial mesenchyme.
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Fibroblast growth factor (FGF) receptor 1-IIIb is a naturally occurring functional receptor for FGFs that is preferentially expressed in the skin and the brain. J Biol Chem 2000; 275:16091-7. [PMID: 10821861 DOI: 10.1074/jbc.275.21.16091] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fibroblast growth factors (FGFs) transmit their signals through four transmembrane receptors that are designated FGFR1-4. Alternative splicing in the extracellular region of FGFR1-3 generates receptor variants with different ligand binding affinities. Thus two types of transmembrane receptors (IIIb and IIIc isoforms) have been identified for FGFR2 and FGFR3, and the existence of analogous variants has been postulated for FGFR1 based on its genomic structure. However, only a single full-length transmembrane FGFR1 variant (FGFR1-IIIc) has been identified so far. Here we describe the cloning of a full-length cDNA encoding FGFR1-IIIb from a mouse skin wound cDNA library. This receptor isoform was expressed at the highest levels in a subset of sebaceous glands of the skin and in neurons of the hippocampus and the cerebellum. FGFR1-IIIb was expressed in L6 rat skeletal muscle myoblasts and used in cross-linking and receptor binding studies. FGF-1 was found to bind the receptor with high affinity, whereas FGF-2, -10, and -7 bound with significantly lower affinities. Despite their apparently similar but low affinities, FGF-10 but not FGF-7 induced the activation of p44/42 mitogen-activated protein kinase in FGFR1-IIIb-expressing L6 myoblasts and stimulated mitogenesis in these cells, demonstrating that this new receptor variant is a functional transmembrane receptor for FGF-10.
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The expression of dopamine beta-hydroxylase, tyrosine hydroxylase, and Phox2 transcription factors in sympathetic neurons: evidence for common regulation during noradrenergic induction and diverging regulation later in development. Mech Dev 2000; 92:169-77. [PMID: 10727856 DOI: 10.1016/s0925-4773(99)00336-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
During differentiation of sympathetic neurons in chick embryos, tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) mRNAs become detectable during the same developmental period and are both induced by BMP 4. Later during sympathetic ganglion development, DBH is detectable in TH-positive and -negative cells. Moreover, BMPs reduce DBH mRNA in cultures of sympathetic neurons while leaving TH unaffected. The data provide evidence for a common regulation of TH and DBH early during sympathetic neuron differentiation and indicate that BMPs promote their initial expression but not the maintenance during later development. The time course of Phox2a and 2b expression suggests an evolutionary conserved role in noradrenergic induction. In addition, Phox2a, Phox2b, and c-ret may be involved in the differentiation of cholinergic sympathetic neurons.
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The RET receptor tyrosine kinase: activation, signalling and significance in neural development and disease. PHARMACEUTICA ACTA HELVETIAE 2000; 74:261-4. [PMID: 10812967 DOI: 10.1016/s0031-6865(99)00048-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The RET receptor tyrosine kinase was first identified in a screen for human oncogenes and has subsequently been linked to several human syndromes: Hirschprung's disease, multiple endocrine neoplasia types 2A and 2B and familial thyroid carcinoma. Interestingly, all of the tissues affected by mutations in RET are derived from the neural crest during development. RET transduces a signal following activation by ligands of the glial cell line-derived neurotrophic factor (GDNF) family of neurotrophins which currently comprises GDNF, neuturin (NTN), artemin (ART) and persephin (PSP). To activate RET they form a tripartite complex with RET and a member of a family of four extracellular, GPI-linked alpha receptors (GFR alpha 1-4). Specificity is achieved by each GFR alpha binding only one member of the GDNF family with high affinity. Current evidence indicates that signal transduction by RET activates several second messenger systems including the PLC gamma, Ras, JNK and inositol phosphate pathways. Targeted mutagenesis in transgenic mice has shown that Ret, GFR alpha 1 and GDNF are required for multiple developmental events including development of the enteric nervous system (ENS) affected in Hirschsprung's disease. We describe experiments in chick neural crest cells which provide evidence for the normal function of RET and the basis of the defect in Hirschsprung's disease.
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Expression of sprouty2 during early development of the chick embryo is coincident with known sites of FGF signalling. Mech Dev 2000; 91:361-4. [PMID: 10704865 DOI: 10.1016/s0925-4773(99)00288-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The Drosophila sprouty protein is a recently-identified intracellular modulator of FGF and EGF receptor tyrosine kinase activity which antagonises ras/MAP kinase signalling. In a differential display analysis to identify genes involved in patterning the mid/hindbrain region of the chick neural tube, we have identified a sprouty orthologue, sprouty2. Here we report expression of sprouty2 transcripts in the developing chick embryo. We find a close correlation with known sites of FGF activity but little correlation with expression patterns of members of the EGF family. Initially, transcripts are associated with the primitive streak. During the period of neural tube patterning expression is detected in the anterior neuropore, in the isthmic region and in neural plate and posterior spinal cord. Transcripts are also detected in the otic placode, tail bud, mesoderm of the branchial arches, somitic myotome, retina, limb buds and gut mesenchyme; all known sites of FGF action.
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Signalling by FGF8 from the isthmus patterns anterior hindbrain and establishes the anterior limit of Hox gene expression. Development 2000; 127:177-86. [PMID: 10654611 DOI: 10.1242/dev.127.1.177] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Current evidence suggests that the anterior segment of the vertebrate hindbrain, rhombomere 1, gives rise to the entire cerebellum. It is situated where two distinct developmental patterning mechanisms converge: graded signalling from an organising centre (the isthmus) located at the midbrain/hindbrain boundary confronts segmentation of the hindbrain. The unique developmental fate of rhombomere 1 is reflected by it being the only hindbrain segment in which no Hox genes are expressed. In this study we show that ectopic FGF8 protein, a candidate for the isthmic organising activity, is able to induce and repress gene expression within the hindbrain in a manner appropriate to rhombomere 1. Using a heterotopic, heterospecific grafting strategy we demonstrate that rhombomere 1 is able to express Hox genes but that both isthmic tissue and FGF8 inhibit their expression. Inhibition of FGF8 function in vivo shows that it is responsible for defining the anterior limit of Hox gene expression within the developing brain and thereby specifies the extent of the rl territory. Previous studies have suggested that a retinoid morphogen gradient determines the axial limit of expression of individual Hox genes within the hindbrain. We propose a model whereby activation by retinoids is antagonised by inhibition by FGF8 in the anterior hindbrain to set aside the territory from which the cerebellum will develop.
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Differential display of genes expressed at the midbrain - hindbrain junction identifies sprouty2: an FGF8-inducible member of a family of intracellular FGF antagonists. Mol Cell Neurosci 2000; 15:22-35. [PMID: 10662503 DOI: 10.1006/mcne.1999.0801] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Specification and polarization of the midbrain and anterior hindbrain involve planar signals originating from the isthmus. Current evidence suggests that FGF8, expressed at the isthmus, provides this patterning influence. In this study, we have sought to identify novel genes which are involved in the process by which regional identity is imparted to midbrain and anterior hindbrain (rhombomere 1). An enhanced differential display reverse transcription method was used to clone cDNAs derived from transcripts expressed specifically in either rhombomere 1 or midbrain during the period of isthmic patterning activity. This gene expression screen identified 28 differentially expressed cDNAs. A clone upregulated in cDNA derived from rhombomere 1 tissue showed a 91% identity at the nucleotide level to the putative human receptor tyrosine kinase antagonist: sprouty2. In situ hybridization on whole chick embryos showed chick sprouty2 to be expressed initially within the isthmus and rhombomere 1, spatially and temporally coincident with Fgf8 expression. However, at later stages this domain was more extensive than that of Fgf8. Introduction of ligand-coated beads into either midbrain or hindbrain region revealed that sprouty2 could be rapidly induced by FGF8. These data suggest that sprouty2 participates in a negative feedback regulatory loop to modulate the patterning activity of FGF8 at the isthmus.
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28
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Abstract
Studies involving chick embryos have implicated FGFs in neural induction and patterning as well as in other developmental events. Detailed analyses of FGF receptor expression at early stages of neural development have not been reported for the chick embryo and are incomplete for other vertebrate classes. Here we show the expression patterns of three FGF receptors, (FGFR1, FGFR2 and FGFR3) in embryonic stages between gastrulation and limb bud formation, focussing particularly on neural tissues. Between neural induction and neurulation, all three receptors are expressed in the neural plate albeit with distinct and overlapping distributions. During early neuromere formation FGFR1 transcripts are present throughout the neural tube, while transcripts for FGFR2 and FGFR3 become restricted to regions of the diencephalon and spinal cord. A little later, FGFR2 and FGFR3 are additionally expressed in the anterior midbrain and within the hindbrain. During later neuromere development, FGFR1 transcripts become localised to the telencephalon, anterior dorsal diencephalon and throughout the midbrain and hindbrain, whereas FGFR2 mRNA is restricted to dorsal telencephalon, dorsoanterior midbrain and hindbrain. FGFR3 is also expressed in anterior midbrain and hindbrain during this developmental period, and is additionally expressed in the posterior telencephalon, in the pretectum, and at the zona limitans intrathalamica. The observed expression patterns of all three receptors within the hindbrain, including rhombomere boundaries, are complex and dynamic. Expression patterns within the somites, eye, head mesenchyme, branchial arches, limb buds, nephric kidney and pharynx are also described.
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MESH Headings
- Animals
- Chick Embryo
- Embryo, Nonmammalian/embryology
- Embryo, Nonmammalian/physiology
- Gene Expression Regulation, Developmental
- Nervous System/embryology
- Protein-Tyrosine Kinases
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptor Protein-Tyrosine Kinases/biosynthesis
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor, Fibroblast Growth Factor, Type 1
- Receptor, Fibroblast Growth Factor, Type 2
- Receptor, Fibroblast Growth Factor, Type 3
- Receptors, Fibroblast Growth Factor/biosynthesis
- Receptors, Fibroblast Growth Factor/genetics
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Regeneration of isthmic tissue is the result of a specific and direct interaction between rhombomere 1 and midbrain. Development 1999; 126:3981-9. [PMID: 10457008 DOI: 10.1242/dev.126.18.3981] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The midbrain-hindbrain boundary, or isthmus, is the source of signals that are responsible for regional specification of both the midbrain and anterior hindbrain. Fibroblast growth factor 8 (Fgf8) is expressed specifically at the isthmus and there is now good evidence that it forms at least part of the patterning signal. In this study, we use Fgf8 as a marker for isthmic cells to examine how interactions between midbrain and hindbrain can regenerate isthmic tissue and, thereby, gain insight into the normal formation and/or maintenance of the isthmus. We show that Fgf8-expressing tissue with properties of the isthmic organiser is generated when midbrain and rhombomere 1 tissue are juxtaposed but not when midbrain contacts any other rhombomere. The use of chick/quail chimeras shows that the isthmic tissue is largely derived from rhombomere 1. In a few cases a small proportion of the Fgf8-positive cells were of midbrain origin but this appears to be the result of a local respecification to a hindbrain phenotype, a process mimicked by ectopic FGF8. Studies in vitro show that the induction of Fgf8 is the result of a direct planar interaction between the two tissues and involves a diffusible signal.
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Abstract
Fibroblast growth factor 4 (Fgf4) has been implicated as a regulator of mesoderm formation, posteriorisation, neural induction and neural patterning. Much of the evidence for this derives from studies in which exogenous FGF4 is applied to avian embryos. We have therefore examined expression of endogenous Fgf4 mRNA in the developing chick embryo at stages when these processes are occurring. Expression was detected in the primitive streak from the onset of gastrulation. Notably, transient expression of transcripts was found in head process cells at the onset of neural plate formation and regionalisation. Later, mRNA was detected in the presumptive posterior hindbrain and within the ventral midbrain. Fgf4 mRNA was also found in paraxial mesoderm underlying the posterior hindbrain, somites, branchial arches, limb buds and the tail bud.
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Abstract
OBJECTIVE Cutaneous electrogastrography records gastric electrical activity and detects gastric arrhythmias. Abnormalities of the electrogastrogram have been described in a variety of disorders, but their specificity and their prevalence in patients with functional gastrointestinal disorders has not been reported. The aim of this study was to assess the specificity of electrogastrography as well as the prevalence and pattern of abnormalities in functional dyspepsia and irritable bowel syndrome. METHODS Electrogastrography was performed in 170 patients with functional dyspepsia, 70 patients with irritable bowel syndrome, 20 patients with gastroesophageal reflux disease, and 30 asymptomatic controls. The abnormal electrogastrogram was defined as <70% normal electrical activity either before or after a test meal. RESULTS The electrogastrogram was abnormal in 36% of patients with functional dyspepsia and in 25% with irritable bowel syndrome who complained of concurrent dyspepsia. The electrogastrogram was normal in 93% of asymptomatic controls, 90% of patients with gastroesophageal reflux, and 92% of patients with irritable bowel syndrome who did not complain of dyspepsia. As a group, functional dyspepsia patients had a greater degree of tachygastrias both before (p < 0.02) and after (p < 0.01) a test meal. The electrical frequency after the test meal was also more unstable (p < 0.003). CONCLUSIONS The electrogastrogram is abnormal in approximately 36% of functional dyspepsia patients and has a specificity of approximately 93%. Electrogastrography defines a subgroup of patients with functional dyspepsia and electrical rhythm disturbance. In irritable bowel syndrome, the electrogastrogram is usually abnormal only if concurrent dyspepsia is present.
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Abstract
Receptor tyrosine kinases and receptor protein tyrosine phosphatases (RPTPs) appear to coordinate many aspects of neural development, including axon growth and guidance. Here, we focus on the possible roles of RPTPs in the developing avian retinotectal system. Using both in situ hybridization analysis and immunohistochemistry, we show for the first time that five RPTP genes--CRYPalpha, CRYP-2, PTPmu, PTPgamma, and PTPalpha--have different but overlapping expression patterns throughout the retina and the tectum. PTPalpha is restricted to Muller glia cells and radial glia of the tectum, indicating a possible function in controlling neuronal migration. PTPgamma expression is restricted to amacrine neurons. CRYPalpha and CRYP-2 mRNAs in contrast are expressed throughout the retinal ganglion cell layer from where axons grow out to their tectal targets. PTPmu is expressed in a subset of these ganglion cells. CRYPalpha, CRYP-2, and PTPmu proteins are also localized in growth cones of retinal ganglion cell axons and are present in defined laminae of the tectum. Thus, the spatial and temporal expression of three distinct RPTP subtypes--CRYPalpha, CRYP-2, and PTPmu--are consistent with the possibility of their involvement in axon growth and guidance of the retinotectal projection.
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Abstract
Experiments involving tissue recombinations have implicated both early vertical and later planar signals in the specification and polarisation of the midbrain. Here we investigate the role of fibroblast growth factors in regulating these processes in the avian embryo. We show that Fgf4 is expressed in the notochord anterior to Hensen's node before transcripts for the earliest molecular marker of midbrain tissue in the avian embryo, En1, are detected. The presence of notochord is required for the expression of En1 in neural plate explants in vitro and FGF4 mimics this effect of notochord tissue. Subsequently, a second member of the fibroblast growth factor family, Fgf8, is expressed in the isthmus in a manner consistent with it providing a polarising signal for the developing midbrain. Using a retroviral vector to express En1 ectopically, we show that En1 can induce Fgf8 expression in midbrain and posterior diencephalon. Results of the introduction of FGF8 protein into the anterior midbrain or posterior diencephalon are consistent with it being at least part of the isthmic activity which can repolarise the former tissue and respecify the latter to a midbrain fate. However, the ability of FGF8 to induce expression of genes which have earlier onsets of expression than Fgf8 itself, namely En1 and Pax2, strongly suggests that the normal function of FGF8 is in maintaining patterns of gene expression in posterior midbrain. Finally, we provide evidence that FGF8 also provides mitogenic stimulation during avian midbrain development.
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Computerised biofeedback games: a new method for teaching stress management and its use in irritable bowel syndrome. JOURNAL OF THE ROYAL COLLEGE OF PHYSICIANS OF LONDON 1998; 32:552-6. [PMID: 9881312 PMCID: PMC9662981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
OBJECTIVES To develop and test a computer biofeedback game designed to teach deep relaxation to patients with a stress related disorder and to assess whether relaxation can improve symptomatic episodes. STUDY DESIGN AND SETTING An open, prospective, single centre study. Department of Gastroenterology, Royal Free Hospital, London. SUBJECTS Forty patients with irritable bowel syndrome refractory to conventional medical treatment. MAIN OUTCOME MEASURES Development of a computer aided biofeedback apparatus directed at the gut for teaching relaxation to patients with irritable bowel syndrome. The patients' ability to complete a computer game involving biofeedback modulated by a physiological loop that related changes in stress (monitored by electrodermal activity) to animated computer graphics. The degree to which deep relaxation was achieved was measured numerically by a progressive reduction in the sensitivity level of the biofeedback loop. The success of relaxation in ameliorating physical symptoms of irritable bowel syndrome was assessed by daily diaries in which global and weighted bowel symptom scores were entered. RESULTS A computer biofeedback game based on animated gut imagery was successfully developed. Most patients learned to achieve progressively deeper levels of relaxation after four 30 minute biofeedback sessions (mean difference in sensitivity level 2.0 (95% confidence interval 0.96 to 2.93), p < 0.001). Use of 'dosed' relaxation when bowel symptoms were troublesome was helpful in 50% of patients. It reduced the global symptom score (mean difference 0.5 (0.02 to 0.32), p < 0.04) and the bowel symptom score (mean difference 0.8 (0.04 to 1.58), p < 0.04). At long term follow up, 64% of patients who had been helped by dosed relaxation continued to use the technique, although they had had no further contact with the hospital. CONCLUSIONS This computer biofeedback game taught deep relaxation rapidly and effectively. Half the patients with refractory irritable bowel syndrome found the technique helpful on most occasions on which it was used. Computer biofeedback games may offer a simple, inexpensive strategy for managing other stress related medical disorders.
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Abstract
Gbx-2 is required for the normal development of the anterior hindbrain. Since much of our understanding of the normal development of this region derives from studies of avian embryos, we have determined the expression of Gbx-2 in chick embryos at stages relevant to the regionalization of the hindbrain. As the neural plate forms transcripts already have a clear anterior limit of expression and, subsequently, occupy a domain extending from the extreme posterior midbrain to the rhombomere 3/4 boundary. Subsequently, expression is restricted to the isthmus, a dorsal stripe of expression extending throughout the hindbrain in the ventricular region and the cells adjacent to rhombomere boundaries. Transcripts were also detected in pharyngeal endoderm, the otic placode and vesicle, pharyngeal arches and somites.
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Abstract
BACKGROUND The electrogastrogram (EGG), which records gastric myoelectrical activity, is abnormal in one-third of adult patients with non-ulcer dyspepsia (NUD). AIM To observe the effects of cisapride on EGG in adults with NUD. METHODS Twenty-seven NUD patients who had undergone a pre- and post-prandial EGG were entered into an open study. All patients completed a dyspepsia symptom questionnaire and were then treated with cisapride 10 mg t.d.s. The dyspepsia questionnaire was repeated in all those completing 4 weeks of treatment. Those with an initial abnormal EGG (< 70% of slow wave activity at 2-4 cycles per minute) had a repeat EGG at the end of the study. RESULTS Treatment with cisapride was associated with a significant improvement in the post-prandial EGG (P = 0.007). After 4 weeks of treatment, 7 of 13 abnormal EGGs normalized. Symptom scores improved significantly in the 13 patients with an abnormal EGG who completed treatment (P < 0.0003), but not in NUD patients with a normal EGG (P = 0.48). CONCLUSION In this open study, treatment of NUD with cisapride was associated with significant symptom improvement in patients with an abnormal pre-treatment EGG, but not those with a normal EGG, with a significant improvement of the post-prandial EGG.
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The management of acid-related dyspepsia in general practice: a comparison of an omeprazole versus an antacid-alginate/ranitidine management strategy. Compete Research Group [corrected]. Aliment Pharmacol Ther 1998; 12:263-71. [PMID: 9570261 DOI: 10.1046/j.1365-2036.1998.00282.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND There is need for an evidence-based comparison of clinical management strategies to provide the rationale for selection of a particular therapeutic approach to treatment. Ideal dyspepsia treatment should quickly and conveniently alleviate patient symptoms whilst also minimizing the use of healthcare resources. AIM To examine dyspepsia symptom relief over 16 weeks and compare an omeprazole clinical management strategy with a commonly used combination of antacid-alginate followed by H2-antagonist. METHODS Seven hundred and twenty-five patients participated in this randomized, open, parallel group comparison over 16 weeks. Patients were randomized to receive either an omeprazole treatment strategy (363) consisting of omeprazole 10 mg stepping up to 20 mg and 40 mg as required, or an antacid-alginate/ranitidine treatment strategy (362) consisting of antacid-alginate 10 mL q.d.s. stepping up to ranitidine 150 mg b.d. and 150 mg q.d.s. as required. RESULTS A greater proportion of patients receiving the omeprazole clinical management strategy had achieved the stringent health target of complete symptom relief (61 vs. 40%, P < 0.0001) at 16 weeks. Forty-six per cent of omeprazole-treated patients were symptom free after the first 10 mg step compared to only 17% in the antacid-alginate treated group (P = 0.0001). Total relief of heartburn, the most common symptom at entry, was achieved by more patients in the omeprazole treatment group than the antacid-alginate/ranitidine treatment group, 62 vs. 36%, respectively, at 4 weeks, and 81 vs. 60% at 16 weeks (P = 0.0001). CONCLUSION Treatment with the omeprazole clinical management strategy was superior to the antacid-alginate/ranitidine management strategy in providing relief of acid-related dyspepsia symptoms after 16 weeks. In addition, the omeprazole treatment strategy involved fewer GP consultations and thus minimized the use of other healthcare resources.
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Abstract
Hirschsprung's disease is a neuronal dysplasia of the hindgut, characterised by a loss of neurones, which affects about 1 in 5000 live births. Genetic factors have been implicated in the aetiology of this disease in about 20% of cases and a dominant pattern of inheritance has been revealed in several families. The pathogenesis of the aganglionosis is often attributed to a failure of migration of neural crest cells, although this has not been proven. Recently, mutations in a developmentally regulated receptor tyrosine kinase gene, ret, and mutations in the endothelin receptor-B gene (ENDR-B) have both been linked to familial Hirschsprung's disease in humans. Moreover, certain mutant mouse strains--namely piebald lethal and lethal spotted--exhibit striking similarities to the human condition. The mutation which gives rise to piebald lethal has now been found to be in the ENDR-B gene, and the mutation associated with lethal spotted occurs in the gene for endothelin-3 (ET-3), a ligand for ENDR-B. Two transgenic mouse lines have been developed which also reflect the human disease: ret-k-, which has a loss of function mutation of the ret gene, and ENDR-B null. In addition, the introduction of a Lac-Z reporter gene into neural crest cells of aganglionic mice has made it possible to study directly the fate of enteric neuroblasts which are affected by "Hirschsprung's-like" mutations. Here, we review the possible roles of RET and endothelin in the normal development of the enteric nervous system, and the significance of their mutated forms in the pathogenesis of familial aganglionosis. This review focuses on recent advances in our understanding of the genetic basis of the lesions which have been implicated in congenital forms of Hirschsprung's disease. Disruption of these genes in the mouse, either by transgenic "knockout" approaches or in mutant mouse lines, offers the prospect of greater understanding of both the cellular and developmental bases of the human disease.
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Two omeprazole-based Helicobacter pylori eradication regimens for the treatment of duodenal ulcer disease in general practice. Aliment Pharmacol Ther 1997; 11:919-27. [PMID: 9354201 DOI: 10.1046/j.1365-2036.1997.00234.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Helicobacter pylori is the main acquired factor in the pathogenesis of duodenal ulcer disease. METHODS This multicentre study conducted in 32 general practice centres in the UK and Ireland was a double-blind, placebo-controlled, randomized, parallel-group comparison of triple therapy (n = 98: omeprazole 40 mg once daily and amoxycillin 1 g b.d. for 2 weeks, and metronidazole 400 mg t.d.s. for the first week) and dual therapy (n = 85: omeprazole 40 mg once daily and amoxycillin 1 g b.d. for 2 weeks, with placebo during the first week) for the eradication of H. pylori in patients with symptomatic duodenal ulcer disease. Patients who were successfully treated entered a follow-up phase for 12 months to assess symptomatic relapse and use of health-care resources. RESULTS Eradication of H. pylori based on a second 13C-urea breath test was successful in 95% (95% confidence interval (CI) = 90-100%) of patients receiving omeprazole triple therapy and 53% (95% CI = 41-65%) of those receiving omeprazole dual therapy (P < 0.0001 between groups, all data available analysis). The all-patients-treated analysis gave eradication rates of 80 and 44% for omeprazole triple therapy and omeprazole dual therapy, respectively. Symptomatic relapse occurred in 16% (18/116) of the H. pylori-negative patients who entered the 12-month follow-up period, and there were significant reductions in the number of consultations, investigations and prescriptions relating to upper gastrointestinal symptoms compared with the 12 months prior to the eradication therapies (all P < 0.0001). The two treatment strategies were comparable in terms of the number of adverse events reported. CONCLUSIONS Omeprazole triple therapy provides a highly effective treatment for the eradication of H. pylori infection in patients in general practice, with an adverse event profile similar to that seen with omeprazole dual therapy. The successful eradication of H. pylori with these omeprazole regimens results in a significant decrease in the use of health-care resources in the 12 months following treatment.
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Abstract
Fibroblast growth factors (FGFs) and receptors (FGFRs) are expressed in the developing lung and appear to be major regulators of lung growth and differentiation. By using mesenchyme-free lung epithelial cultures we show that FGF-1 (aFGF) and FGF-7 (KGF) produce different effects in the developing lung. FGF-1 stimulates epithelial proliferation that results in bud formation (branching), while FGF-7 promotes epithelial proliferation that leads to formation of cyst-like structures. In addition, FGF-7 stimulates epithelial differentiation, stimulating expression of SP-A and SP-B mRNA throughout the explant, and inducing formation of focal areas of highly differentiated cells. The FGF-1 effects on differentiation are limited to induction of surfactant protein SP-B mRNA at the tips of the explant. The FGF-induced patterns of growth appear to correlate with the distribution of epithelial FGFRs mRNAs; FGFR-2 IIIb (KGFR) is diffusely expressed in the day 11 lung epithelium, while FGFR-4 appears in distal but not in proximal sites. We propose that cyst-like structures may result from FGF-7 binding to the uniformly distributed FGFR-2-IIIb. Lung bud formation may be regulated by FGF-1 and/or other ligands binding to FGFR-2 and a distally located FGFR, such as FGFR-4, leading to an increasing binding and activation of FGFRs at the tips of the explant. Thus, in the embryonic lung epithelium, growth effects of FGFs appear to be dependent on location of FGFRs, while effects on differentiation are ligand-dependent.
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Abstract
Recent studies suggest that fibroblast growth factors (FGFs), or FGF receptor-mediated signalling, function in specifying posterior identity in the developing neural tube, and possibly also in neural induction.
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Secretion and mitogenic activity of zebrafish FGF3 reveal intermediate properties relative to mouse and Xenopus homologues. Oncogene 1996; 12:1503-11. [PMID: 8622866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Zebrafish (Brachyodanio rerio) Fgf-3 cDNAs expressed in COS-1 cells give rise to the heterogeneous set of secreted proteins with relative molecular masses in the range of 29-30.5 kDa. These proteins associate strongly with the extracellular matrix but are quantitatively released into the culture medium in the presence of heparin (5 micrograms/ml). Extracellular zebrafish FGF3 (ZFGF3) also contains a smaller sized component that appears to result from an amino-terminal proteolytic cleavage. These properties are similar to those described for Xenopus FGF3 (XFGF3). Receptor binding experiments indicate that ZFGF3 has a higher affinity for the IIIb rather than the IIIc isoform of FGFR2; properties that are more reminiscent of the mouse than the Xenopus homologue. Consistent with the FGF receptor binding properties, ZFGF3 shows a restricted mitogenic potential and a reduced transforming activity on NIH3T3 cells compared to XFGF3. Hybrid proteins made between Xenopus and zebrafish FGF3 implicate the C-terminal region in determining the differences in receptor potential affinities, mitogenic potency and transforming activity. Thus, ZFGF3 shows the structural and secretory properties of XFGF3, but has biological properties more akin to those of the mouse homologue.
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