Detection of anabolic androgenic steroids in serum samples

When testing for anabolic androgenic steroids (AAS) outside sports communities, for example, in healthcare and forensic medicine, urine is the matrix of choice. However, there are drawbacks with urinary sampling, and serum might be useful as a complementary matrix. The aim was to develop an LC-MS/MS method for serum measuring AAS frequently used outside of sport, including testosterone (T), steroid esters, and eight other synthetic AAS. The sample pretreatment included sample precipitation and evaporation. Limit of quantification for the AAS was 0.05-0.5 ng/mL, and linearity was 0.05-20 ng/mL for most of the substances. Generally, the within- and between-day CV results, matrix effect, and process efficiency were <15%. The AAS were stable for at least 6 months at -20°C. Serum samples were obtained from previous studies. A novel finding from an administration study was that T enanthate was present in serum even after 5 years of storage at -20°C. Serum samples from self-reporting AAS individuals, where T esters were detected, were positive for testosterone using the urinary testosterone/epitestosterone criterion >10. Of those identified as positive in traditional urinary doping tests (n = 15), AAS in serum were found in 80% of the subjects. Our results show that serum may be a valid complementary matrix to urine samples for AAS testing.

Pharmacodynamic evaluation and safety assessment of treatment with antibodies to serum amyloid P component in patients with cardiac amyloidosis: an open-label Phase 2 study and an adjunctive immuno-PET imaging study

BACKGROUND

In a Phase I study treatment with the serum amyloid P component (SAP) depleter miridesap followed by monoclonal antibody to SAP (dezamizumab) showed removal of amyloid from liver, spleen and kidney in patients with systemic amyloidosis. We report results from a Phase 2 study and concurrent immuno-positron emission tomography (PET) study assessing efficacy, pharmacodynamics, pharmacokinetics, safety and cardiac uptake (of dezamizumab) following the same intervention in patients with cardiac amyloidosis.

METHODS

Both were uncontrolled open-label studies. After SAP depletion with miridesap, patients received ≤ 6 monthly doses of dezamizumab in the Phase 2 trial (n = 7), ≤ 2 doses of non-radiolabelled dezamizumab plus [89Zr]Zr-dezamizumab (total mass dose of 80 mg at session 1 and 500 mg at session 2) in the immuno-PET study (n = 2). Primary endpoints of the Phase 2 study were changed from baseline to follow-up (at 8 weeks) in left ventricular mass (LVM) by cardiac magnetic resonance imaging and safety. Primary endpoint of the immuno-PET study was [89Zr]Zr-dezamizumab cardiac uptake assessed via PET.

RESULTS

Dezamizumab produced no appreciable or consistent reduction in LVM nor improvement in cardiac function in the Phase 2 study. In the immuno-PET study, measurable cardiac uptake of [89Zr]Zr-dezamizumab, although seen in both patients, was moderate to low. Uptake was notably lower in the patient with higher LVM. Treatment-associated rash with cutaneous small-vessel vasculitis was observed in both studies. Abdominal large-vessel vasculitis after initial dezamizumab dosing (300 mg) occurred in the first patient with immunoglobulin light chain amyloidosis enrolled in the Phase 2 study. Symptom resolution was nearly complete within 24 h of intravenous methylprednisolone and dezamizumab discontinuation; abdominal computed tomography imaging showed vasculitis resolution by 8 weeks.

CONCLUSIONS

Unlike previous observations of visceral amyloid reduction, there was no appreciable evidence of amyloid removal in patients with cardiac amyloidosis in this Phase 2 trial, potentially related to limited cardiac uptake of dezamizumab as demonstrated in the immuno-PET study. The benefit-risk assessment for dezamizumab in cardiac amyloidosis was considered unfavourable after the incidence of large-vessel vasculitis and development for this indication was terminated. Trial registration NCT03044353 (2 February 2017) and NCT03417830 (25 January 2018).

The role of support from significant others in the association between disease-related factors and sickness absence in early rheumatoid arthritis: a longitudinal study

Objective: The aim of this study was to analyse how support from significant others affects the associations between disease-related variables and sickness absence during the first 2 years after rheumatoid arthritis (RA) diagnosis.Method: Data from 274 people with RA (73% women) of working age (18-63 years) were retrieved from the Swedish early RA cohort TIRA-2. These data concerned disease-related variables (disease activity, activity limitations, pain intensity, and grip force), sickness absence, and perceived support from significant others. Associations of disease-related variables with sickness absence and how these associations were moderated by support from significant others were analysed using zero-inflated negative binomial regression.Results: During the 2 years after diagnosis, higher disease activity was significantly associated with increased odds of sickness absence, a connection strengthened by perceived support from family during the first year. More perceived support was also directly and significantly associated with increased odds of sickness absence during the first year.Conclusions: Support from significant others is related to sickness absence in RA, specifically during the first year after diagnosis. Although patients report high levels of support from significant others, this does not necessarily lead to more positive work outcomes. Therefore, it is important to consider other aspects of support that might influence work outcomes, e.g. type and quality of support. Future research should investigate these forms of support, and when significant others should be encouraged to support in the rehabilitation process to increase the chances of people with RA having a well-functioning and sustainable work life.

Detection of Drugs in Oral Fluid Samples Using a Commercially Available Collection Device: Agreement with Urine Testing and Evaluation of A and B Samples Obtained from Employees at Different Workplace Settings with Uncontrolled Sampling Procedures

The use of oral fluid tests to detect drugs is of growing interest in various areas, including treatment centers, roadside and workplace testing. In this study, we investigated drug detection in oral fluid samples collected using a commercially available device, Oral Eze. Drug detection in oral fluid was compared to paired urine samples, which were simultaneously collected. We also evaluated the collection device by comparing A and B oral fluid samples. Finally, we studied the stability of various drugs in samples stored for at least 1 year. The drug profile was investigated by comparing the drugs detected in oral fluid samples with paired urine samples collected in a treatment center. A total of 113 paired oral fluid and urine samples were investigated for the presence of drugs in the following groups: amphetamines, benzodiazepines, opiates and opioids, cocaine and cannabis. A and B samples were collected from different workplaces through an uncontrolled sampling procedure (n = 76). The stability of drugs in A samples was assessed after storage at -20°C for 1 year. Generally, there was a good correlation between drugs detected in oral fluid samples and urine samples. The heroin metabolite, 6-MAM, was more frequently detected in oral fluid samples than in urine samples, while cannabis was better detected in urine samples. Drugs in oral fluid samples were stable when stored at -20°C for at least 1 year. However, in many positive A and B oral fluid samples, there was significant variation in the concentrations obtained. Hence, the collection device may need to be further standardized and improved.

Cross-species/cross-modality physiologically based pharmacokinetics for biologics: 89Zr-labelled albumin-binding domain antibody GSK3128349 in humans

Two-pore physiologically-based pharmacokinetics (PBPK) for biologics describes the tissue distribution and elimination kinetics of soluble proteins as a function of their hydrodynamic radius and the physiological properties of the organs. Whilst many studies have been performed in rodents to parameterize the PBPK framework in terms of organ-specific lymph flow rates, similar validation in humans has been limited. This is mainly due to the paucity of the tissue distribution time course data for biologics that is not distorted by target-related binding. Here, we demonstrate that a PBPK model based on rodent data provided good to satisfactory extrapolation to the tissue distribution time course of ⁸⁹Zr-labeled albumin-binding domain antibody (AlbudAb™) GSK3128349 in healthy human volunteers, including correct prediction of albumin-like plasma half-life, volume of distribution, and extravasation half-life. The AlbudAb™ used only binds albumin, and hence it also provides information about the tissue distribution kinetics and turnover of that ubiquitous and multifunctional plasma protein.

OP0330-HPR ‘THE BEST THING WE HAVE IS EACH OTHER’ – A QUALITATIVE DYADIC APPROACH TO EXPLORE SUPPORT IN EVERYDAY LIFE BETWEEN PERSONS WITH RA AND THEIR SIGNIFICANT OTHERS

Background:

Participation in everyday life and the relationships between persons with rheumatoid arthritis (RA) and their significant others are often affected by the disease. Usually, both parts need to adapt to new roles [1]. However, the dyadic interaction between them in everyday life is yet to be understood on a deeper level.

Objectives:

To exploreI) How dyads consisting of persons with RA and their significant others comprehend support and participation in everyday life, andII) how the dyadic interaction can influence their experience of participation in everyday life.

Methods:

In-depth individual interviews were conducted both with the persons with RA 12-13 years after diagnosis and inclusion in the Swedish multicenter project TIRA-2 [2], and with their significant others as defined by the persons with RA. Demographic data and the Valued Life Activity Scale (VLA-swe) [3] was reported by the persons with RA. To avoid bias, the persons with RA and their significant others were interviewed by different researches. Data from the interviews were transcribed verbatim and content analysis with a dyadic approach was undertaken [4]. The process of coding and categorizing was discussed between the researchers. The study was approved by the Regional Ethics Committee at Linköping University (Dnr. 2018/158-31), all participants gave their written consent.

Results:

Three women and two men with RA and five significant others, all represented by spouses, participated (N=10). The age of the persons with RA ranged from 34 to 67 years and a majority experienced difficulties in ≥ 12 valued life activities.

Three categories were revealed:1) A strong willpower affecting the dyadic relationship, meaning that the understanding within the dyads was that the persons with RA were not so keen to share status, which was mentioned in connection to tenacity and expectations.2) Being a support to each other, referring to the mutual understanding within the couples that there was a constant exchange of support, forming a basis for participation in everyday life. However, disagreement was expressed concerning an unequal amount of support.3) The dyads’ potential issues with awareness, addressing the difficulty in fully comprehending the impact of the diagnosis. The couples mentioned an unwillingness from the person with RA to share information, and the significant other viewing comments as complaining. This type of miscommunication was interpreted as a potential negative effect on participation in everyday life.

Conclusion:

A constant exchange of support within the dyads was evident. However, the dyadic relationships were often affected by the willpower of the persons with RA to be independent in everyday life. In addition, the dyads faced the concern of fully understanding the diagnosis. The results indicate further needs for interventions for both the persons with RA as well as the significant others, in order to boost the dyadic interaction, and thereby facilitate optimal participation in everyday life of persons with RA.

References:

[1]Brignon M, Vioulac C, Boujut E et al. (2019) Patients and relatives coping with inflammatory arthritis: care teamwork. Health Expect 2019;00:1-11

[2]Thyberg I, Dahlström Ö, Björk M, et al. (2017) Hand pains in women and men in early rheumatoid arthritis, a one year follow-up after diagnosis. The Swedish TIRA project. Disabil Rehabil 2017;39(3):291-300

[3]Björk M, Thyberg M, Valtersson, E et al. (2016) Validation and internal consistency of the Swedish version of the Valued Life Activities scale. Clin Rehabil 2016;30(12):1211-1219

[4]Eiskovits Z, Koren C (2010) Approaches to and outcomes of dyadic interview analysis. Qual Health Res 2010;20(12):1642-55

Disclosure of Interests:

None declared

Maximal-intensity exercise does not fully restore muscle pyruvate dehydrogenase complex activation after 3 days of high-fat dietary intake

BACKGROUND & AIMS

Exercise activates muscle pyruvate dehydrogenase complex (PDC), but moderate intensity exercise fails to fully activate muscle PDC after high-fat diet [1]. We investigated whether maximal intensity exercise overcomes this inhibition.

METHODS

Quadriceps femoris muscle biopsy samples were obtained from healthy males at rest, and after 46 and 92 electrically-evoked maximal intermittent isometric contractions, which were preceded by 3 days of either low- (18%) or high- (69%) isocaloric dietary fat intake (LFD and HFD, respectively).

RESULTS

The ratio of PDCa (active form) to total PDCt (fully activated) at rest was 50% less after HFD (0.32 ± 0.01 vs 0.15 ± 0.01; P < 0.05). This ratio increased to 0.77 ± 0.06 after 46 contractions (P < 0.001) and to 0.98 ± 0.07 after 92 contractions (P < 0.001) in LFD. The corresponding values after HFD were less (0.54 ± 0.06; P < 0.01 and 0.70 ± 0.07; P < 0.01, respectively). Resting muscle acetyl-CoA and acetylcarnitine content was greater after HFD than LFD (both P < 0.05), but their rate of accumulation in the former was reduced during contraction. Muscle lactate content after 92 contractions was 30% greater after HFD (P < 0.05). Muscle force generation during contraction was no different between interventions, but HFD lengthened muscle relaxation time (P < 0.05). Daily urinary total carnitine excretion after HFD was 2.5-fold greater than after LFD (P < 0.01).

CONCLUSIONS

A bout of maximal intense exercise did not overcome dietary fat-mediated inhibition of muscle pyruvate dehydrogenase complex activation, and was associated with greater muscle lactate accumulation, as a result of lower PDC flux, and increased muscle relaxation time.

Positron Emission Tomography with 11C-Methionine and Computed Tomography of Intracranial Tumours Compared with Histopathologic Examination of Multiple Biopsies

A selected group of 36 patients with suspected supratentorial gliomas were investigated with positron emission tomography (PET) using 11C-methionine and transmission computed tomography (CT) before and after intravenous injection of contrast medium. Every examination was performed with the head fixed in a plastic helmet and a baseplate to guarantee that the slice orientation was the same at examinations with the two modalities and over time. Guided by the examinations, multiple stereotactic biopsies were performed with the biopsy instrument mounted on the baseplate. Regional accumulation of methionine was compared with histology of the corresponding samples and with attenuation before and after injection of contrast medium as well as mass effect on CT. Typically, there was a low attenuating lesion with a slight mass effect on CT. There was an increased accumulation compared with normal brain tissue in 31 cases of tumours and ordinary or decreased accumulation in 3 cases of tumours. In 22 cases with increased accumulation of methionine the extension of the tumour judged by PET corresponded with that of histology. In 4 cases tumour cells were found outside the area with pathologic methionine uptake. In 5 patients there were areas with increased methionine accumulation where no tumour cells were found. In 22 cases PET using methionine was more accurate than CT in defining the tumour boundaries as determined from the histologic findings. Four groups of biopsy specimens with different amounts of methionine accumulation are described. The uptake in a single biopsy gives good but not exact information about the histology of the specimen.

Comparison of the Accumulation Kinetics of L-(Methyl-11C)-Methionine and D-(Methyl-11C)-Methionine in Brain Tumors Studied with Positron Emission Tomography

Five patients with glioma were examined with positron emission tomography after the administration of 11C-L-methionine and at a following day with 11C-D-methionine. The rates of accumulation of the tracers were determined in the tumor and in the normal brain tissue according to a graphical technique of Patlak et coll. (24). The accumulation rates for L-methionine were on the average 2.4 times higher than those of D-methionine in the tumors. The corresponding ratio for normal brain tissue was 2.3. It is concluded that in this group of tumors without obvious blood-tumor-barrier breakdown, a stereospecific process with similar properties as in the normal brain tissue, is responsible for the accumulation of the labelled methionine.

Positron Emission Tomography Compared with Magnetic Resonance Imaging and Computed Tomography in Supratentorial Gliomas Using Multiple Stereotactic Biopsies as Reference

Ten patients with findings at computed tomography (CT) suggesting intracranial supratentorial glioma were investigated to compare the diagnostic efficacy of this technique with that of positron emission tomography (PET) using 11C-methionine and exminations with magnetic resonance (MR). The findings were related to histopathologic examination of serial stereotactic biopsies, which were guided by the appearance of the lesions on PET examination. To obtain corresponding slice orientation with the different examination techniques, an individually shaped helmet fixation was used. However, in 3 cases this fixation device could not be used for MR. Histopathologic diagnosis, obtained in all cases from multiple target stereotactic biopsies, included glioma in 9 patients and reactive gliosis in one case. A detailed comparison of the three imaging techniques and the findings at stereotactic biopsies was possible in 7 patients, while in 3 patients comparison with MR was less exact due to the patient's refusal to wear the helmet during this examination. MR was the most accurate method for outlining the total extent of a lesion, i.e. the tumor and the edema surrounding it. Four lesions had homogeneous signal characteristics and in 6 lesions two (or more) compartments could be distinguished with MR. In 5 cases the MR findings were in complete agreement with the histopathologic findings. However, a thorough correlation between signal characteristics and histology was not possible. Using PET the occurrence and the extent of tumor tissue was correctly predicted in 7 patients. The PET was normal in one case. Findings at CT were in agreement with the histopathologic diagnosis in 5 patients. MR was the most sensitive method for the detection of lesions. PET using methionine appeared to have a somewhat higher capacity to outline correctly the true extent of a tumor. The combination of CT and PET was superior to MR for determining the type and grade of the tumors.

Delineation of Gliomas with Magnetic Resonance Imaging Using Gd-DTPA in Comparison with Computed Tomography and Positron Emission Tomography

Fourteen patients with cerebral gliomas were investigated by MR imaging using Gd-DTPA (Magnevist), CT with the contrast agent iohexol (Omnipaque) and, as a reference, positron emission tomography (PET) using 11C-L-methionine. Tumour areas with disruption of the blood-brain-barrier (BBB) as seen on MR and CT were compared with areas with increased accumulation of methionine in PET. There were 6 patients with high-grade astrocytoma (grade III-IV), 5 with low-grade astrocytoma (grade I–II) and 3 with oligodendroglioma. In 4 high-grade tumours, PET showed a larger tumour or tumour tissue in additional areas, compared with enhancement on MR and CT, while in 2 cases the tumour extension was similar in the three modalities. In the low grade tumour group, the findings on PET differed from those on post-contrast MR or CT in 7 cases. In 3 of these cases, no disruption of the BBB was seen either on MR or on CT. In 2 of our 14 patients CT showed larger enhancement extension than MR and in 2 cases MR was superior to CT in this respect. The enhancement intensity was higher on MR in 4 patients and on CT in 2 patients. No definite difference in the delineation of tumour tissue between the T1 weighted SE sequences used was found. The gradient echo sequences FLASH and FISP gave limited information that was less than that provided by the T1 weighted SE sequences. A greater increase in signal intensity in T1 weighted images was usually seen 5 min post-contrast in the high-grade tumours than in the low-grade ones.

Application of a Kinetic Model on the Methionine Accumulation in Intracranial Tumours Studied with Positron Emission Tomography

Eleven patients were studied with positron emission tomography (PET) using 11C-methionine. They all had low-grade astrocytomas (Kernohan grade II). The PET studies were analyzed with a metabolic model to obtain values for the influx, the accumulation rate and the partition coefficient of methionine in normal and tumourous tissue. Seven of the tumours showed an increased accumulation of methionine as compared with normal tissue on the static PET scans and also had higher values as to the kinetic parameters. Four tumours had a methionine accumulation equal to or lower than that of normal tissue and the kinetic parameters were also lower. Application of the kinetic model did not aid significantly in the delineation of the tumours. There was a correlation between the three parameters indicating an adaption of the transport of methionine to the regional metabolic demand. The accumulation rate for normal cortical tissue was 0.49 nmol/g/min, the influx 0.97 nmol/ml and the partition coefficient 0.45 ml/g. These values are considerably higher than those previously reported. The differences might be attributed to differences in the corrections introduced for i.a. the occurrence of labelled metabolites in serum. With the use of a kinetic model, more information about the tracer is utilized and gained compared with the previously used graphic approach.

Prenatal parental depression and preterm birth: a national cohort study

Objective

To investigate the effects of maternal and paternal depression on the risk for preterm birth.

Design

National cohort study.

Setting

Medical Birth Register of Sweden, 2007–2012.

Population

A total of 366 499 singleton births with linked information for parents’ filled drug prescriptions and hospital care.

Methods

Prenatal depression was defined as having filled a prescription for an antidepressant drug or having been in outpatient or inpatient hospital care with a diagnosis of depression from 12 months before conception until 24 weeks after conception. An indication of depression after 12 months with no depression was defined as ‘new depression’, whereas all other cases were defined as ‘recurrent depression’.

Main outcome measures

Odds ratios (ORs) for very preterm (22–31 weeks of gestation) and moderately preterm (32–36 weeks of gestation) births were estimated using multinomial logistic regression models.

Results

After adjustment for maternal depression and sociodemographic covariates, new paternal prenatal depression was associated with very preterm birth [adjusted OR (aOR) 1.38, 95% confidence interval (95% CI) 1.04–1.83], whereas recurrent paternal depression was not associated with an increased risk of preterm birth. Both new and recurrent maternal prenatal depression were associated with an increased risk of moderately preterm birth (aOR 1.34, 95% CI 1.22–1.46, and aOR 1.42, 95% CI 1.32–1.53, respectively).

Conclusions

New paternal and maternal prenatal depression are potential risk factors for preterm birth. Mental health problems in both parents should be addressed for the prevention of preterm birth.

Tweetable abstract

Depression in both mothers and fathers is associated with an increased risk of preterm birth.

Depression in both mothers and fathers is associated with an increased risk of preterm birth.

Immunological profiling of haemodialysis patients and young healthy individuals with implications for clinical regulatory T cell sorting

With the increasing interest in clinical trials with regulatory T cells (Tregs), immunological profiling of prospective target groups and standardized procedures for Treg isolation are needed. In this study, flow cytometry was used to assess peripheral blood lymphocyte profiles of young healthy individuals and patients undergoing haemodialysis treatment. Tregs obtained from the former may be used in haematopoietic stem cell transplantation and Tregs from the latter in the prevention of kidney transplant rejection. FOXP3 mRNA expression with accompanying isoform distribution was also assessed by the quantitative reverse transcriptase polymerase chain reaction. Flow-cytometric gating strategies were systematically analysed to optimize the isolation of Tregs. Our findings showed an overall similar immunological profile of both cohorts in spite of great differences in both age and health. Analysis of flow-cytometric gating techniques highlighted the importance of gating for both CD25high and CD127low expression in the isolation of FOXP3-positive cells. This study provides additional insight into the immunological profile of young healthy individuals and uraemic patients as well as in-depth analysis of flow-cytometric gating strategies for Treg isolation, supporting the development of Treg therapy using cells from healthy donors and uraemic patients.

Therapy response monitoring of the early effects of a new BRAF inhibitor on melanoma xenograft in mice: evaluation of (18) F-FDG-PET and (18) F-FLT-PET

Inhibition of the V600E mutated BRAF kinase gene (BRAF(V600E) ) is an important and effective approach to treating melanomas. A new specific small molecule inhibitor of BRAF(V600E) , PLX3603, showed potent melanoma growth-inhibiting characteristics in preclinical studies and is currently under clinical investigation. In this study we investigated the feasibility of (18) F-FDG and (18) F-FLT-PET to monitor the early effects of the BRAF(V600E) inhibitor in mice with melanoma xenografts. SCID/beige mice with subcutaneous (s.c.) A375 melanoma xenografts, expressing BRAF(V600E) , received the BRAF(V600E) inhibitor twice daily orally (0, 25, 50 and 75 mg/kg). At 1, 3 and 7 days after start of therapy, the uptake of (18) F-FDG and (18) F-FLT in the tumor and normal tissues was determined in ex vivo tissue samples. Serial (18) F-FDG and (18) F-FLT-PET scans were acquired of animals at 1 day before and 1, 3 and 7 days after start of treatment with 75 mg/kg BRAF(V600E) inhibitor. A dose-dependent decrease in (18) F-FDG uptake in the A375 tumors was observed by ex vivo biodistribution analysis. Administration of 75 mg/kg BRAF inhibitor for 1, 3 and 7 days resulted in a significantly decreased (18) F-FDG uptake in A375 tumors (41, 35 and 51%, respectively). (18) F-FLT uptake in the A375 tumors was low at baseline and no significant changes in (18) F-FLT uptake were observed at any of the doses administered. These effects were corroborated by serial in vivo (18) F-FDG and (18) F-FLT-PET imaging. These data demonstrate that (18) F-FDG-PET can be used as an imaging biomarker to noninvasively evaluate the early effects of PLX3603.

Tesofensine, a novel triple monoamine re-uptake inhibitor with anti-obesity effects: dopamine transporter occupancy as measured by PET

Tesofensine (TE) is a novel triple monoamine re-uptake inhibitor inducing a potent inhibition of the re-uptake process in the synaptic cleft of the neurotransmitters dopamine, norepinephrine, and serotonin. In recent preclinical and clinical evaluations TE showed a robust anti-obesity effect, but the specific mechanism of this triple monoamine re-uptake inhibitor still needs to be further elucidated. This positron emission tomography (PET) study, using [¹¹C]βCIT-FE, aimed to assess the degree of the dopamine transporter (DAT) occupancy, at constant TE plasma levels, following different oral, multiple doses of TE during totally 8-12 days. In addition, the relationships between DAT occupancy and TE plasma concentrations, or doses, were investigated to enable assessment of DAT occupancies in subsequent clinical trials. The results demonstrated that TE induced a dose-dependent blockade of DAT following multiple doses of 0.125-1 mg TE at anticipated steady-state conditions. The mean striatal DAT occupancy varied dose-dependently between 18% and 77%. A sigmoid E(max) model well described the relationship between striatal DAT occupancy and TE plasma concentrations or doses. It was estimated that the maximum achievable DAT occupancy was about 80% and that half of this effect was accomplished by approximately 0.25 mg TE and a plasma drug concentration of 4 ng/ml. The results indicated an important mechanism of action of TE on DAT. Further, these results suggest that the previously reported dose-dependent weight loss, in TE treated subjects, was in part mediated by an up-regulation of dopaminergic pathways due to enhanced amounts of synaptic dopamine after blockade of DAT.

Self-expandable metal stents as a new treatment option for perforated duodenal ulcer

Primary stenting and drainage has been shown to be an effective and safe way to treat esophageal perforations and anastomotic leaks after gastric bypass surgery. We present a case series of eight patients with perforated duodenal ulcers treated with covered self-expandable metal stents (SEMS). The first two patients received their stents because of postoperative leakage after initial traditional surgical closure. The following six patients had SEMS placed as primary treatment due to co-morbidities or technical surgical difficulties. Endoscopy and stent treatment in these six patients was performed at a median of 3 days (range, 0 - 7 days) after initial symptoms. Six patients had percutaneous abdominal drainage. Early oral intake, 0 - 7 days after stent placement, was possible. All patients except one recovered without complications and were discharged 9 - 36 days after stent placement. This series indicates that primary treatment with SEMS and drainage might be an alternative to surgery in patients with perforated ulcer disease.

Reporting and incidence trends of hydatidiform mole in Sweden 1973-2004

OBJECTIVE

To examine temporal trends in the incidence of hydatidiform mole (HM) in relation to maternal age, the occurrence of choriocarcinoma in women with a history of HM and the extent of underreporting of HM to the Swedish Cancer Register (SCR).

METHODS

Women registered with a diagnosis of HM were identified in the Swedish Cancer Register and the Swedish Inpatient Register (IPR). Record linkage to the Medical Birth Register provided information to assess the incidence of HM.

RESULTS

We identified 3 844 unique cases of HM in the SCR and in the IPR combined between 1973 and 2004, yielding an incidence of 1.2 per 1 000 deliveries. The incidence of HM increased during the period under study. The highest incidence was observed in women below 20 and above 39 years of age. Of all registered cases of choriocarcinoma, 37% occurred in women with a previous history of HM. The risk of choriocarcinoma following HM was 1.3%, compared to 0.005% in women without a previous molar diagnosis. The records of the Cancer Register included 83.2% of all identified cases of HM.

CONCLUSION

The incidence of HM in Sweden has increased over time, and is characterized by a bimodal pattern with distinctive peaks in the youngest and oldest women of reproductive age. More than one third of all women registered with choriocarcinoma had a previous diagnosis of HM. Despite mandatory reporting, there was evidence of underreporting of HM to the SCR that remained virtually unchanged over calendar time.

Endoscopic sutured closure of a gastric natural orifice transluminal endoscopic surgery access gastrotomy compared with open surgical closure in a porcine model. A randomized, multicenter controlled trial

BACKGROUND AND STUDY AIMS

In natural orifice transluminal endoscopic surgery (NOTES) procedures it is essential to be able to perform secure closure of the access perforation. The aim of this study was to compare endoscopically sutured closure of a gastric access gastrotomy using the tissue apposition system (TAS), with closure via laparotomy in a randomized multicenter study.

METHODS

A total of 32 pigs (18 - 42 kg) were used in this study. The gastric NOTES access was created using a needle knife and a 20-mm balloon. Following transgastric pelvic peritoneoscopy, the endoscope was withdrawn into the stomach. The animals were then randomized to endoscopic closure or laparotomy with surgical closure. Procedure time, recovery time, and weight gain were measured. At necropsy, adhesions, abscesses or peritonitis were recorded.

RESULTS

Of the 32 pigs, 29 survived 14 days without complications. All endoscopic and all open surgical closures were secure at postmortem. On average two suture pairs were used for endoscopic closure. Surgical closure was quicker (12.5 vs. 20.1 minutes). Recovery time and postoperative weight gain were similar for both groups. Two pigs in the endoscopic group died: one of gastric dilatation, without leakage from the gastrotomy; another was euthanized due to rectal prolapse. In the laparotomy group one pig was euthanized after 7 days due to abdominal wound dehiscence. At necropsy there were significantly more intra-abdominal adhesions in the laparotomized group.

CONCLUSION

This randomized controlled study of endoscopic and surgical closure of a gastrotomy made for transperitoneal access for NOTES procedures suggests that both techniques are comparable in technical closure rates, postoperative recovery, and prevention of peritonitis. There were fewer adhesions in the endoscopic group.

Radiolabelled oligonucleotides for imaging of gene expression with PET

Our understanding of altered patterns of gene expression being responsible for many diseases has been growing thanks to modern molecular biological methods. Today, these changes can only be identified when tissue samples are available. Therefore, a noninvasive method allowing us to monitor gene expression in vivo would be valuable, not only as a research tool, but also for patient stratification before treatment and for treatment follow-up. Antisense oligonucleotides (ODN) have been considered to be suitable molecules to trace active genes in vivo, as well as to treat diseases by hybridising to its complementary messenger RNA (mRNA) sequence in the cells thereby preventing the synthesis of the peptide. However, the use of ODNs in the organisms are endangered by many hurdles such as physical barriers to pass and enzyme attack to be avoided. Positron emission tomography (PET) provides a most advanced in vivo imaging technology that allows the exploration of the fate of radionuclide-labelled antisense ODNs in the body; thereby providing information about biodistribution and quantitative accumulation in tissues to assess pharmacokinetic properties of ODNs. This kind of evaluation is important as part of the characterisation of antisense therapeutics but also as part of the development of antisense imaging agents. This review provides a general summary about the antisense concept and displays the present status of the antisense imaging field with the major achievements and remaining challenges on the long journey towards accomplishing in vivo monitoring of gene expression using PET.

Transgastric peritoneoscopy and appendectomy: thoughts on our first experience in humans

We present a series of three patients operated on by means of natural-orifice transgastric peritoneoscopy, including one appendectomy. A standard double-lumen gastroscope was used together with standard endoscopic tools. In all patients abdominal access through the gastric wall was smooth using a needle-knife/guide-wire/balloon technique. The whole abdominal cavity could be visualized and the appendix was found in two patients. In one patient the procedure was converted to laparoscopic appendectomy and in one to open surgery. In the third patient transgastric appendectomy was performed. The gastric access site was closed with the T-tag technique. Patients were allowed to drink and eat as soon as they woke up. Postoperatively patients were followed clinically and with standard laboratory tests daily until discharged. One patient (converted to open surgery) had a serious complication (pneumothorax). The transgastric approach to the abdominal cavity was shown to be feasible, but significant technical problems remain to be resolved.

Non-hybridization saturable mechanisms play a role in the uptake of (68)Ga-Labeled LNA-DNA mixmer antisense oligonucleotides in rats

Oligonucleotides (ODN) are key molecules for the aim of preventing translation of a gene product or monitoring gene expression in tissues. However, multiple methodological and biological hurdles need to be solved before in vivo application in humans will be possible. For positron emission tomography (PET) investigations, a 20-mer DNA-locked nucleic acid (LNA) mixmer ODN specific for rat chromogranin-A mRNA was labeled with (68)Ga and its uptake was examined in vivo in rats with and without blocking of scavenger receptors by polyribonucleotides. In addition, uptake studies of (68)Ga-LNA were performed with respect to time and concentration in human and rat cell lines. The human cell lines did not express the target mRNA. Both polyinosinic acid (poly-I) and polyadenylic acid (poly-A) reduced the uptake in rat tissues and in human cell lines. Poly-I was found to be more effective in the liver whereas poly-A was more effective in the kidney. In addition, the blockade by poly-I was statistically significant in the pancreas, adrenal gland, bone marrow, intestine, testis, urinary bladder, muscle, parotid gland, and heart, whereas poly-A also caused significant reduction in pancreas, adrenal gland, and bone marrow but not as much as in kidney. Cell culture study showed a 2-phase dose-dependent uptake characteristic with a saturable and a passive diffusion-like phase; however, these 2 phases were not so well expressed in the rat cell line. The results suggest that scavenger receptors or other saturable processes unrelated to hybridization may be involved in the tissue uptake of (68)Ga-LNA and in the clearance of antisense ODN through the liver, kidney, spleen, and bone marrow. The fact that these processes may be sequence-dependent suggests that proof of in vivo hybridization through imaging may not be obtained by only comparing sense and antisense sequences and proving dose-dependency.

Evaluation of the Hsp90 inhibitor NVP-AUY922 in multicellular tumour spheroids with respect to effects on growth and PET tracer uptake

BACKGROUND

Molecular targeting has become a prominent concept in cancer treatment and heat shock protein 90 (Hsp90) inhibitors are suggested as promising anticancer drugs. The Hsp90 complex is one of the chaperones that facilitate the refolding of unfolded or misfolded proteins and plays a role for key oncogenic proteins such as Her2, Raf-1, Akt/PKB, and mutant p53. NVP-AUY922 is a novel low-molecular Hsp90 inhibitor, currently under clinical development as an anticancer drug. Disruption of the Hsp90-client protein complexes leads to proteasome-mediated degradation of client proteins and cell death. The aim of the current study was to use a combination of the multicellular tumour spheroid (MTS) model and positron emission tomography (PET) to investigate the effects of NVP-AUY922 on tumour growth and its relation to PET tracer uptake for the selection of appropriate PET tracer. A further aim was to evaluate the concentration and time dependence in the relation between growth inhibition and PET tracer uptake as part of translational imaging activities.

METHODS

MTS of two breast cancer cell lines (MCF-7 and BT474), one glioblastoma cell line (U87MG) and one colon carcinoma cell line (HCT116) were prepared. Initially, we investigated MTS growth pattern and (3)H-thymidine incorporation in MTS after continuous exposure to NVP-AUY922 in order to determine dose response. Then the short-term effect of the drug on the four PET tracers 2-[(18)F] fluoro-2-deoxyglucose (FDG), 3'-deoxy-3'-fluorothymidine (FLT), methionine and choline was correlated to the long-term effect (changes in growth pattern) to determine the adequate PET tracer with high predictability. Next, the growth inhibitory effect of different dose schedules was evaluated to determine the optimal dose and time. Finally, the effect of a 2-h exposure to the drug on growth pattern and FDG/FLT uptake was evaluated.

RESULTS

A dose-dependent inhibition of growth and decrease of (3)H-thymidine uptake was observed with 100% growth cessation in the dose range 7-52 nM and 50% (3)H-thymidine reduction in the range of 10-23 nM, with the most pronounced effect on BT474 cells. The effect of the drug was best detected by FLT. The results suggested that a complete cessation of growth of the viable cell volume was achieved with about 50% inhibition of FLT uptake 3 days after continuous treatment. Significant growth inhibition was observed at all doses and all exposure time spans. Two-hour exposure to NVP-AUY922 generated a growth inhibition which persisted dose dependently up to 10 days. The uptake of FDG per viable tumour volume was reduced by just 25% with 300 nM treatment of the drug, whereas the FLT uptake decreased up to 75% in correlation with the growth inhibition and recovery.

CONCLUSIONS

Our results indicate a prolonged action of NVP-AUY922 in this cell culture, FLT is a suitable tracer for the monitoring of the effect and a FLT PET study within 3 days after treatment can predict the treatment outcome in this model. If relevant in vivo, this information can be used for efficient planning of animal PET studies and later human PET trial.

Effects of natural childbirth preparation versus standard antenatal education on epidural rates, experience of childbirth and parental stress in mothers and fathers: a randomised controlled multicentre trial

Objective

To examine the effects of antenatal education focussing on natural childbirth preparation with psychoprophylactic training versus standard antenatal education on the use of epidural analgesia, experience of childbirth and parental stress in first-time mothers and fathers.

Design

Randomised controlled multicentre trial.

Setting

Fifteen antenatal clinics in Sweden between January 2006 and May 2007.

Sample

A total of 1087 nulliparous women and 1064 of their partners.

Methods

Natural group: Antenatal education focussing on natural childbirth preparation with training in breathing and relaxation techniques (psychoprophylaxis). Standard care group: Standard antenatal education focussing on both childbirth and parenthood, without psychoprophylactic training. Both groups: Four 2-hour sessions in groups of 12 participants during third trimester of pregnancy and one follow-up after delivery.

Main outcome measures

Epidural analgesia during labour, experience of childbirth as measured by the Wijma Delivery Experience Questionnaire (B), and parental stress measured by the Swedish Parenthood Stress Questionnaire.

Results

The epidural rate was 52% in both groups. There were no statistically significant differences in the experience of childbirth or parental stress between the randomised groups, either in women or men. Seventy percent of the women in the Natural group reported having used psychoprophylaxis during labour. A minority in the Standard care group (37%) had also used this method, but subgroup analysis where these women were excluded did not change the principal findings.

Conclusion

Natural childbirth preparation including training in breathing and relaxation did not decrease the use of epidural analgesia during labour, nor did it improve the birth experience or affect parental stress in early parenthood in nulliparous women and men, compared with a standard form of antenatal education.

Radiopharmaceuticals for oncology drug development: a pharmaceutical industry perspective

Oncology remains an increasingly important focus of therapeutic development yet there remain many scientific and operational bottlenecks to deliver optimum treatments efficiently. Radiopharmaceuticals constitute a group of methodologies able to support the many stages of drug development. Methods such as [(18)F]-FDG-PET continue to have a role, evaluating early metabolic response to treatment and supporting more conventional assessments of disease response. Improvements over such tracers (for example, use of [(18)F]-FLT) in certain settings can also widen the impact radiotracers have on clinical development. New categories of tracers able to provide molecular insight into therapeutic intervention are likely grow and aim to remove the ambiguity of how effective a new drug is. It is likely that newer tracers able to define processes such as angiogenesis and apoptosis will supplement other methods in supporting early development decision-making and de-risking expensive, late-stage programs. Labeled drugs themselves also offer the ability to study localised pharmacokinetics in vivo and study issues such as therapeutic combinations. Owing to the significant cost, resource and time investment in developing novel tracers, new opportunities need to be closely matched with emerging drug development needs.

PET-evaluated transport of [11C]hydroxyurea across the rat blood-brain barrier--lack of influence of cyclosporin and probenecid

The transport of hydroxyurea, a ribonucleoside reductase inhibitor, over biological membranes is slow and it has therefore been suggested that the substance could interact with an active efflux transporter. The transport of [(11)C]hydroxyurea into the rat brain was therefore studied after administration of the multidrug resistance protein inhibitor probenecid (50 and 150 mg/kg), the P-glycoprotein inhibitor cyclosporin A (25 mg/kg), hydroxyurea (50, 150 and 450 mg/kg) and mannitol (25%). None of the intervention drugs affected the brain uptake of [(11)C]hydroxyurea. The brain-to-plasma concentration ratios (K(p)), with or without intervention drug, were in the range 0.12-0.25 after 60 min of [(11)C]hydroxyurea infusion. [(11)C]Verapamil, a P-glycoprotein substrate with low brain penetration, was used to study the ability of hydroxyurea to inhibit P-glycoprotein. Administration of hydroxyurea (150 and 450 mg/kg) did not increase brain concentrations of [(11)C]verapamil. It is therefore unlikely that hydroxyurea is a substrate for or an inhibitor of P-glycoprotein or a substrate for a probenecid sensitive transport system. The low brain concentrations may instead be the result of slow uptake due to the hydrophilic nature of hydroxyurea.

Performance of principal component analysis and independent component analysis with respect to signal extraction from noisy positron emission tomography data - a study on computer simulated images

Multivariate image analysis tools are used for analyzing dynamic or multidimensional Positron Emission Tomography, PET data with the aim of noise reduction, dimension reduction and signal separation. Principal Component Analysis is one of the most commonly used multivariate image analysis tools, applied on dynamic PET data. Independent Component Analysis is another multivariate image analysis tool used to extract and separate signals. Because of the presence of high and variable noise levels and correlation in the different PET images which may confound the multivariate analysis, it is essential to explore and investigate different types of pre-normalization (transformation) methods that need to be applied, prior to application of these tools. In this study, we explored the performance of Principal Component Analysis (PCA) and Independent Component Analysis (ICA) to extract signals and reduce noise, thereby increasing the Signal to Noise Ratio (SNR) in a dynamic sequence of PET images, where the features of the noise are different compared with some other medical imaging techniques. Applications on computer simulated PET images were explored and compared. Application of PCA generated relatively similar results, with some minor differences, on the images with different noise characteristics. However, clear differences were seen with respect to the type of pre-normalization. ICA on images normalized using two types of normalization methods also seemed to perform relatively well but did not reach the improvement in SNR as PCA. Furthermore ICA seems to have a tendency under some conditions to shift over information from IC1 to other independent components and to be more sensitive to the level of noise. PCA is a more stable technique than ICA and creates better results both qualitatively and quantitatively in the simulated PET images. PCA can extract the signals from the noise rather well and is not sensitive to type of noise, magnitude and correlation, when the input data are correctly handled by a proper pre-normalization. It is important to note that PCA as inherently a method to separate signal information into different components could still generate PC1 images with improved SNR as compared to mean images.

Pharmacokinetics of P-glycoprotein inhibition in the rat blood-brain barrier

This article describes the experimental set-up and pharmacokinetic modeling of P-glycoprotein function in the rat blood-brain barrier using [(11)C]verapamil as the substrate and cyclosporin A as an inhibitor of P-gp. [(11)C]verapamil was administered to rats as an i.v. bolus dose followed by graded infusions to obtain steady-state concentrations in the brain during 70 min. CsA was administered as a bolus followed by a constant infusion 20 min after the start of the [(11)C]verapamil infusion. The brain uptake of [(11)C]verapamil over 2 h was portrayed in a sequence of PET scans in parallel with measurement of [(11)C]verapamil concentrations in blood and plasma and CsA concentrations in blood. Mixed effects modeling in NONMEM was used to build a pharmacokinetic model of CsA-induced P-gp inhibition. The brain pharmacokinetics of [(11)C]verapamil was well described by a two-compartment model. The effect of CsA on the uptake of [(11)C]verapamil in the brain was best described by an inhibitory indirect effect model with an effect on the transport of [(11)C]verapamil out of the brain. The CsA concentration required to obtain 50% of the maximal inhibition was 4.9 microg/mL (4.1 microM). The model parameters indicated that 93% of the outward transport of [(11)C]verapamil was P-gp mediated.

Biodistribution of 68Ga-labeled LNA-DNA mixmer antisense oligonucleotides for rat chromogranin-A

In vivo monitoring of gene expression may be accomplished using a most advanced imaging technology such as positron emission tomography (PET). However, a range of methodological and biological hurdles needs exploration. In the present study, 20-mer DNA-LNA (locked nucleic acid) mixmer oligonucleotides specific for rat Chromogranin-A (Chg-A) mRNA were labeled with 68Ga and their biodistribution were investigated in rats; namely, two Antisense (LNA1, LNA2--differing only in the positioning of LNA modification), Mismatched, and Sense sequences. In addition, in vivo and in vitro metabolite analysis of LNA1 and LNA2 was compared, and hybridization in solution was performed to verify the hybridization ability after labeling. Furthermore, semiquantitative polymerase chain reaction was carried out to find organs expressing Chg-A mRNA in the rat. The biodistribution patterns altered according to the sequence and the positioning of LNA modification. The pattern of Mismatched--differing only in two nucleotides from the two Antisenses--was similar to that of Sense, whereas the pattern of LNA1 and LNA2 showed differences. Uptake in the adrenal gland was twofold higher with LNA2 compared to the other three oligonucleotides. Intact LNA2 could be observed in the 60-minute sample in vivo, whereas in vitro, the intact compound of both Antisenses could also be detected after 2 hours. Hybridization in solution revealed that the two Antisenses retained their hybridization abilities after 68Ga-labeling. With decreasing magnitude, Chg-A mRNA was expressed in the adrenal gland, intestine, testis, and pancreas. This study further supported LNA-DNA mixmer to be a favorable modification for antisense targeting approach with respect to hybridization and longer plasma residence; however, the organ uptake was dominated by processes irrelevant to specific hybridization.

A computerized infusion pump for control of tissue tracer concentration during positron emission tomography in vivo pharmacokinetic/pharmacodynamic measurements

BACKGROUND

A computer controlled infusion pump (UIPump) for regulation of target tissue concentration of radioactive compounds was developed for use in biological research and tracer development for PET.

METHODS

Based on observed tissue or plasma kinetics after a bolus injection of the tracer an algorithm calculates the infusion needed to obtain a specified target kinetic curve. A computer feeds this infusion scheme into an infusion pump connected to an animal via a venous catheter. The concept was validated using [11C]Flumazenil administrated to Sprague-Dawley rats where the whole brain distribution and kinetic of the tracer was measured over time using a microPET-scanner. The accuracy and precision of the system was assessed by producing steady-state levels of the tracer and by mimicking kinetics after oral administration.

RESULTS

Various kinetic profiles could be generated, including rapid achievement of constant levels, or step-wise increased levels. The resulting tissue curves had low deviation from the target curves according to the specified criteria: AUC (%): 4.2 +/- 2.8, Maximal deviation (%): 13.6 +/- 5.0 and R2: 0.95 +/- 0.02.

CONCLUSION

The UIPump-system is suitable for use in PET-research for assessment of PK/PD properties by simulation of different tracer tissue kinetics in vivo.

Positron emission tomography and target-controlled infusion for precise modulation of brain drug concentration

INTRODUCTION

There are several instances when it is desirable to control brain concentration of pharmaceuticals, e.g., to modulate the concentration of anesthetic agents to different desired levels fitting to different needs during the course of surgery. This has so far only been possible using indirect estimates of drug concentration such as assuming constant relation between tissue and blood including extrapolations from animals.

METHODS

A system for controlling target tissue concentration (UIPump) was used to regulate whole-brain concentrations of a central benzodiazepine receptor antagonist at therapeutic levels with input from brain kinetics as determined with PET. The system was tested by using pharmacological doses of flumazenil mixed with tracer amounts of [11C]flumazenil. Flumazenil was used as a model compound for anesthesia. An infusion scheme to produce three different steady-state levels in sequence was designed based on kinetic curves obtained after bolus injection. The subjects (Sprague-Dawley rats, n=6) were monitored in a microPET scanner during the whole experiment to verify resulting brain kinetic curves.

RESULTS

A steady-state brain concentration was rapidly achieved corresponding to a whole-brain concentration of 118+/-6 ng/ml. As the infusion rate decreased to lower the exposure by a factor of 2, the brain concentration decreased to 56+/-4 ng/ml. A third increased steady-state level of anesthesia corresponding to a whole-brain concentration of 107+/-7 ng/ml was rapidly achieved.

CONCLUSION

The experimental setup with computerized pump infusion and PET supervision enables accurate setting of target tissue drug concentration.

Application of the multicellular tumour spheroid model to screen PET tracers for analysis of early response of chemotherapy in breast cancer

INTRODUCTION

Positron emission tomography (PET) is suggested for early monitoring of treatment response, assuming that effective anticancer treatment induces metabolic changes that precede morphology alterations and changes in growth. The aim of this study was to introduce multicellular tumour spheroids (MTS) to study the effect of anticancer drugs and suggest an appropriate PET tracer for further studies.

METHODS

MTS of the breast cancer cell line MCF7 were exposed to doxorubicin, paclitaxel, docetaxel, tamoxifen or imatinib for 7 days for growth pattern studies and for 3 or 5 days for PET tracer studies. The effect on growth was computed using the semi-automated size determination method (SASDM). The effect on the uptake of PET tracers [18F]3'-deoxy-3'-fluorothymidine (FLT), [1-11C]acetate (ACE), [11C]choline (CHO), [11C]methionine (MET), and 2-[18F]fluoro-2-deoxyglucose (FDG) was calculated in form of uptake/viable volume of the MTS at the end of the drug exposures, and finally the uptake was related to effects on growth rate.

RESULTS

The drugs paclitaxel, docetaxel and doxorubicin gave severe growth inhibition, which correlated well with inhibition of the FLT uptake. FLT had, compared with ACE, CHO, MET and FDG, higher sensitivity in monitoring the therapy effects.

CONCLUSION

SASDM provides an effective, user-friendly, time-saving and accurate method to record the growth pattern of the MTS, and also to calculate the effect of the drug on PET tracer uptake. This study demonstrate the use of MTS and SASDM in combination with PET tracers as a promising approach to probe and select PET tracer for treatment monitoring of anticancer drugs and that can hopefully be applied for optimisation in breast cancer treatment.

Symptom provocation in specific phobia affects the substance P neurokinin-1 receptor system

BACKGROUND

Animal studies demonstrate that stress and negative affect enhance the release of the neuropeptide substance P (SP), which binds to the neurokinin 1 (NK1) receptor. This positron emission tomography (PET) study evaluated how the activity in the SP-NK1 receptor system in the amygdala was affected by fear provocation in subjects with specific phobia.

METHODS

Sixteen adult women with DSM-IV-defined specific phobia for either snakes or spiders but not both viewed pictures of feared and non-feared animals while being PET-scanned for 60 min with the highly specific NK1 receptor antagonist [(11)C]GR205171 as the labeled PET tracer.

RESULTS

The uptake of the labeled NK1 receptor antagonist was significantly reduced in the right amygdala during phobic stimulation. In the left amygdala no significant differences were found between phobic and non-phobic conditions. There was a negative correlation in the right, but not left, amygdala between subjective anxiety ratings and NK1 tracer binding.

CONCLUSIONS

Fear provocation affects the SP-NK1 receptor system in the right amygdala. This reflects reduced NK1 receptor availability during fear and could mirror an increased release of endogenous substance P.

Increase in [11C]vorozole binding to aromatase in the hypothalamus in rats treated with anabolic androgenic steroids

In the present study, we investigated the alteration of aromatase expression in the brain by anabolic androgenic steroid treatment in male rats. The rats were given nandrolone decanoate (15 mg/kg/day) for 14 days, and the brains were used for autoradiography with [C]vorozole, which has been developed as a positron emission tomography tracer for aromatase by our group. The results indicated a significant increase of [C]vorozole binding by anabolic androgenic steroids in the bed nucleus of the stria terminalis and preoptic area. In contrast, no significant change of [C]vorozole binding was observed in the medial amygdala. Our results suggest that aromatase is significantly upregulated in the bed nucleus of the stria terminalis and preoptic area by anabolic androgenic steroids and also suggest that androgens regulate aromatase differently in these structures compared with the medial amygdala.

Granulosa cell aromatase enzyme activity: effects of follicular fluid from patients with polycystic ovary syndrome, using aromatase conversion and [11C]vorozole-binding assays

The local regulation of ovarian aromatase enzyme in polycystic ovary syndrome (PCOS) was studied with aromatase conversion and [11C]vorozole-binding assays to analyze aromatase activity, substrate-enzyme affinity and number of aromatase binding sites in non-cultured human granulosa cells (GC) incubated with different sources and preparations of follicular fluid (FF). Incubation with FF from women stimulated in in vitro fertilization cycles with follicle-stimulating hormone yielded higher conversion activity than with FF from healthy women and PCOS patients, paralleled with higher substrate affinity (lower Kd) than with FF from healthy women. In PCOS women, charcoal-pretreated FF yielded higher conversion, whereas the ether-pretreated FF yielded lower conversion activity, than with untreated PCOS FF. Both preparations of FF yielded higher affinity to substrate (lower Kd values) and the ether-pretreated FF a lower number of binding sites (Bmax). It seems that steroids with the presence of proteins in PCOS FF reduced aromatase conversion activity through decreased substrate affinity, whereas FF preparations devoid of proteins reduced the aromatase conversion activity mainly through blocking of aromatase active sites. Identification of specific agents responsible for this rapid regulation of aromatase function might help to understand normal regulation of the menstrual cycle and supposed imbalances of inhibitors/activators in PCOS.

A new application of pre-normalized principal component analysis for improvement of image quality and clinical diagnosis in human brain PET studies—Clinical brain studies using [11C]-GR205171, [11C]-l-deuterium-deprenyl, [11C]-5-Hydroxy-l-Tryptophan, [11C]-l-DOPA and Pittsburgh Compound-B

Principal component analysis (PCA) is one of the most applied multivariate image analysis tool on dynamic Positron Emission Tomography (PET). Independent of used reconstruction methodologies, PET images contain correlation in-between pixels, correlations in-between frame and errors caused by the reconstruction algorithm including different corrections, which can affect the performance of the PCA. In this study, we have investigated a new approach of application of PCA on pre-normalized, dynamic human PET images. A range of different tracers have been used for this purpose to explore the performance of the new method as a way to improve detection and visualization of significant changes in tracer kinetics and to enhance the discrimination between pathological and healthy regions in the brain. We compare the new results with the results obtained using other methods. Images generated using the new approach contain more detailed anatomical information with higher quality, precision and visualization, compared with images generated using other methods.

Predicting brain concentrations of drug using positron emission tomography and venous input: modeling of arterial-venous concentration differences

OBJECTIVE

In a positron emission tomography (PET) study, the concentrations of the labeled drug (radiotracer) are often different in arterial and venous plasma, especially immediately following administration. In a PET study, the transfer of the drug from plasma to brain is usually described using arterial plasma concentrations, whereas venous sampling is standard in clinical pharmacokinetic studies of new drug candidates. The purpose of the study was to demonstrate the modeling of brain drug kinetics based on PET data in combination with venous blood sampling and an arterio-venous transform (T(av)).

METHODS

Brain kinetics (C(br)) was described as the convolution of arterial plasma kinetics (C(ar)) with an arterial-to-brain impulse response function (T(br)). The arterial plasma kinetics was obtained as venous plasma kinetics (C(ve)) convolved with the inverse of the arterio-venous transform (T(av) (-1)). The brain kinetics was then given by C(br)=C(ve)*T(av) (-1)*T(br). This concept was applied on data from a clinical PET study in which both arterial and venous plasma sampling was done in parallel to PET measurement of brain drug kinetics. The predictions of the brain kinetics based on an arterial input were compared with predictions using a venous input with and without an arterio-venous transform.

RESULTS

The venous based models for brain distribution, including a biexponential arterio-venous transform, performed comparably to models based on arterial data and better than venous based models without the transform. It was also shown that three different brain regions with different shaped concentration curves could be modeled with a common arterio-venous transform together with an individual brain distribution model.

CONCLUSION

We demonstrated the feasibility of modeling brain drug kinetics based on PET data in combination with venous blood sampling and an arterio-venous transform. Such a model can in turn be used for the calculation of brain kinetics resulting from an arbitrary administration mode by applying this model on venous plasma pharmacokinetics. This would be an important advantage in the development of drugs acting in the brain, and in other circumstances when the effect is likely to be closer related to the brain than the plasma concentration.

Duration and degree of cyclosporin induced P-glycoprotein inhibition in the rat blood-brain barrier can be studied with PET

Active efflux transporters in the blood-brain barrier lower the brain concentrations of many drug molecules and endogenous substances and thus affect their central action. The objective of this investigation was to study the dynamics of the entire inhibition process of the efflux transporter P-glycoprotein (P-gp), using positron emission tomography (PET). The P-gp marker [(11)C]verapamil was administered to anesthetized rats as an i.v. bolus dose followed by graded infusions via a computerized pump system to obtain a steady-state concentration of [(11)C]verapamil in brain. The P-gp modulator cyclosporin A (CsA) (3, 10 and 25 mg/kg) was administered as a short bolus injection 30 min after the start of the [(11)C]verapamil infusion. The CsA pharmacokinetics was studied in whole blood in a parallel group of rats. The CsA blood concentrations were used as input to model P-gp inhibition. The inhibition of P-gp was observed as a rapid increase in brain concentrations of [(11)C]verapamil, with a maximum after 5, 7.5 and 17.5 min for the respective doses. The respective increases in maximal [(11)C]verapamil concentrations were 1.5, 2.5 and 4 times the baseline concentration. A model in which CsA inhibited P-gp by decreasing the transport of [(11)C]verapamil out from the brain resulted in the best fit. Our data suggest that it is not the CsA concentration in blood, but rather the CsA concentration in an effect compartment, probably the endothelial cells of the blood-brain barrier that is responsible for the inhibition of P-gp.