Two weeks of repetitive gut-challenge reduce exercise-associated gastrointestinal symptoms and malabsorption.

Debilitating gastrointestinal symptoms is a common feature of endurance running and may be exacerbated by and/or limit the ability to tolerate carbohydrate intake during exercise. The study aimed to determine whether two weeks of repetitive gut-challenge during running can reduce exercise-associated gastrointestinal symptoms and carbohydrate malabsorption. Endurance runners (n=18) performed an initial gut-challenge trial (GC1) comprising 2-hour running exercise at 60% VO2max (steady state) while consuming a formulated gel-disk containing 30 g carbohydrates (2:1 glucose-fructose, 10% w/v) every 20 minutes, followed by a 1-hour running effort bout. Gastrointestinal symptoms, feeding tolerance, and breath hydrogen (H2 ) were determined along the gut-challenge trial. After GC1, participants were randomly assigned to a blinded carbohydrate (CHO, 90 gCHO hour-1 ) or placebo (PLA, 0 gCHO hour-1 ) gut-training group. This comprised of consuming the group-specific feeding intervention during 1-hour running exercise at 60% VO2max equivalent, daily over a period of two weeks. Participants then repeated the gut-challenge trial (GC2). In GC2, a reduced gut discomfort (P=.012), total (P=.009), upper- (P=.015), and lower-gastrointestinal (P=.008) symptoms, and nausea (P=.05) were observed on CHO, but not PLA. Feeding tolerance did not differ between GC1 and GC2 on CHO and PLA. H2 peak was attenuated in GC2 (6±3 ppm) compared to GC1 (13±6 ppm) on CHO (P=.004), but not on PLA (GC1 11±7 ppm, and GC2 10±10 ppm). The effort bout distance was greater in GC2 (12.3±1.3 km) compared with GC1 (11.7±1.5 km) on CHO (P=.035) only. Two weeks of repetitive gut-challenge improve gastrointestinal symptoms and reduce carbohydrate malabsorption during endurance running, which may have performance implications.

Endotoxin transiently inhibits protein synthesis through Akt and MAPK mediating pathways in C2C12 myotubes.

In this study, the effect of lipopolysaccharide (LPS) on protein synthesis (PS) and intracellular signaling factors that regulate it have been investigated in C2C12 murine-derived myotubes. In particular, the role of Akt/mammalian target of rapamycin (mTOR) and the mitogen-activated protein kinases (MAPKs) [p38 and extracelluar regulated protein kinase (ERK1/2)] have been examined. The direct effect of LPS on PS was measured at 3 and 18 h. LPS significantly decreased PS at 3 h but not at the 18-h time point. This effect was preceded by decreased Akt phosphorylation at 5 and 30 min after LPS administration. The mTOR phosphorylation exhibited a long time dose-dependent increase at all the time points. Similarly, the activity-related phosphorylation of p38 and ERK1/2 significantly increased in a time- and dose-dependent manner at all the time points. Polymyxin B abolished the LPS-induced decrease in PS rate. The phosphatidylinositol 3-kinase inhibitor LY-0294002 in combination with LPS significantly decreased the rate of PS by 81% and alone by 66%, respectively, for the 3- and 18-h time points, whereas p38 and ERK inhibitors in combination with LPS significantly decreased the rate PS rate at the 18-h time point by 41% and 59%, respectively, compared with control cells. In conclusion, LPS alone transiently decreased the rate of PS by 50% at 3 h; this effect is most likely mediated via the Toll-like receptor 4 (TLR4)-Akt/mTOR pathway, and both p38 and ERK when inhibited in the presence of LPS at 3 h have a similar effect in preventing the LPS-induced reduction in PS.

Tumoricidal activity of tumor necrosis factor-related apoptosis-inducing ligand in vivo.

To evaluate the utility of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a cancer therapeutic, we created leucine zipper (LZ) forms of human (hu) and murine (mu) TRAIL to promote and stabilize the formation of trimers. Both were biologically active, inducing apoptosis of both human and murine target cells in vitro with similar specific activities. In contrast to the fulminant hepatotoxicity of LZ-huCD95L in vivo, administration of either LZ-huTRAIL or LZ-muTRAIL did not seem toxic to normal tissues of mice. Finally, repeated treatments with LZ-huTRAIL actively suppressed growth of the TRAIL-sensitive human mammary adenocarcinoma cell line MDA-231 in CB.17 (SCID) mice, and histologic examination of tumors from SCID mice treated with LZ-huTRAIL demonstrated clear areas of apoptotic necrosis within 9-12 hours of injection.

Cloning of a T cell growth factor that interacts with the beta chain of the interleukin-2 receptor.

A cytokine was identified that stimulated the proliferation of T lymphocytes, and a complementary DNA clone encoding this new T cell growth factor was isolated. The cytokine, designated interleukin-15 (IL-15), is produced by a wide variety of cells and tissues and shares many biological properties with IL-2. Monoclonal antibodies to the beta chain of the IL-2 receptor inhibited the biological activity of IL-15, and IL-15 competed for binding with IL-2, indicating that IL-15 uses components of the IL-2 receptor.

An essential role for ectodomain shedding in mammalian development.

The ectodomains of numerous proteins are released from cells by proteolysis to yield soluble intercellular regulators. The responsible protease, tumor necrosis factor-alpha converting enzyme (TACE), has been identified only in the case when tumor necrosis factor-alpha (TNFalpha) is released. Analyses of cells lacking this metalloproteinase-disintegrin revealed an expanded role for TACE in the processing of other cell surface proteins, including a TNF receptor, the L-selectin adhesion molecule, and transforming growth factor-alpha (TGFalpha). The phenotype of mice lacking TACE suggests an essential role for soluble TGFalpha in normal development and emphasizes the importance of protein ectodomain shedding in vivo.

[Quality improvement of multiple choice examinations: in psychiatry, psychosomatic medicine, psychotherapy, and neurology]. / Qualitätsverbesserung von Multiple-Choice-Prüfungen: In Psychiatrie, Psychosomatik, Psychotherapie und Neurologie.

We describe a continuous improvement process in planning, performance, and evaluation of multiple choice examination questions in psychiatry, neurology, psychosomatic medicine, and psychotherapy. We analyzed 640 multiple choice questions of 1,419 students during a period of 4 years. Crucial changes concerned the abolishment of problematic question types, implementation of validated new question formats, extension of case-based questions, elongation of question stems, quantitative evaluation of item difficulty, discriminatory value, and the introduction of a peer review system. Consequences of these improvements were greater item difficulty (average 18%) and discriminatory value (average 67%) and reduced post hoc analysis times. Introduction of peer reviews resulted in longer preparation time, which was however appreciated by the peers due to a clear improvement in item quality.

Effects of peer-assisted training during the neurology clerkship: a randomized controlled study.

OBJECTIVE: To determine the efficacy of peer-assisted clinical skills training for students during their neurology clerkship. METHODS: Students (n = 122) were randomized to get clinical skills training from either student (peer) instructors (experimental group) or from experienced clinical staff (control group). The remaining schedule during the clerkship did not differ between both groups. Primary endpoint was students' practical skills and knowledge tested at the end of the course by a written test and objective structured clinical examination (OSCE). Secondary endpoints were evaluation of the practical training and self-estimated gain in theoretical and practical competence. RESULTS: In the written test, the peer-trained group (n = 66) scored 69.5 +/- 10.2 (95% CI 67-72) points of 100 and the postgraduates-trained group (n = 56) 66.7 +/- 11.4 (95% CI 63.6-69.8) (P = 0.15). In the OSCE the peer-trained group scored 93.7 +/- 6.3 (95% CI 92.1 to 95.2) points of 100 and the postgraduates-trained group 92 +/- 5.1 (95% CI 90.6 to 93.4) (P = 0.11). In the evaluation and self-assessment items, there was no significant difference between the two groups except for the postgraduates' higher competence (P = 0.004). CONCLUSION: Peer-trained students pass written exam and OSCE as efficient as postgraduates-trained students. Self-assessed learning success is equally rated in both groups.

Estrogen and progesterone receptor-binding sites on the chicken vitellogenin II gene: synergism of steroid hormone action.

The chicken vitellogenin II gene is transcriptionally activated by estrogens. In transient transfection experiments in human T47D cells that contain receptors for various steroids, we showed estradiol, progestin, and androgen responses of a chimeric chicken vitellogenin II construct. This construct consists of DNA sequences from -626 to -590 upstream of the start of transcription of the chicken vitellogenin gene linked to the herpes simplex virus thymidine kinase promoter driving the transcription of the bacterial chloramphenicol acetyltransferase gene. Treatment of the transfected T47D cells with a combination of estradiol and the progestin R5020 led to a superinduction of chloramphenicol acetyltransferase activity, showing a synergistic action of these two steroids. This synergism was not observed upon treatment of the transfected cells with estradiol and the androgen dihydrotestosterone. Using point mutations in the vitellogenin gene fragment, we showed in functional and in in vitro DNase I footprinting assays with a purified progesterone receptor that, for the synergistic action of estradiol and R5020 to occur, the progesterone receptor must be bound to the vitellogenin gene fragment. The progesterone receptor-binding site was localized at -610 to -590, close to the consensus sequence (-626 to -613) for estrogen receptor binding and function. We therefore demonstrate here that two different steroid hormones can be functionally synergistic through the interaction of their corresponding receptors with two different binding sites adjacent to one another.

Regulation of tumor necrosis factor-related apoptosis-inducing ligand sensitivity in primary and transformed human keratinocytes.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to exert potent cytotoxic activity against many tumor cell lines but not against normal cells. It has been hypothesized that this difference in TRAIL sensitivity between normal and transformed cells might be due to the expression of the non-death-inducing TRAIL receptors (TRAIL-R) TRAIL-R3 and TRAIL-R4, presumably by competition for limited amounts of TRAIL. To assess the regulation of resistance versus sensitivity to TRAIL in primary as well as transformed keratinocytes, we examined TRAIL sensitivity, TRAIL receptor expression, and intracellular signaling events induced by TRAIL. Although TRAIL induced apoptosis in primary as well as transformed keratinocytes, a marked difference in sensitivity could be observed with primary keratinocytes (PK) being 5-fold less sensitive to TRAIL than transformed keratinocytes (TK). Yet both cell types exhibited similar TRAIL receptor surface expression, suggesting that expression of TRAIL-R3 and TRAIL-R4 may not be the main regulator of sensitivity to TRAIL. Biochemical analysis of the signaling events induced by TRAIL revealed that PK could be sensitized for TRAIL and, similarly, for TRAIL-R1- and TRAIL-R2-specific apoptosis by pretreatment of the cells with cycloheximide (CHX). This sensitization concomitantly resulted in processing of caspase-8, which did not occur in TRAIL-resistant PK. These data indicate that an early block of TRAIL-induced apoptosis was present in PK compared with TK or PK treated with CHX. Interestingly, cellular FLICE inhibitory protein (cFLIP) levels, high in PK and low in TK and several other squamous cell carcinoma cell lines, decreased rapidly after treatment of PK with CHX, correlating with the increase in TRAIL sensitivity and caspase-8 processing. Furthermore, ectopic expression of cFLIP long (cFLIP(L)) in TK by transfection with a cFLIP(L) expression vector resulted in resistance to TRAIL-mediated apoptosis of these cells. Thus, our results demonstrate that TRAIL sensitivity in PK is primarily regulated at the intracellular level rather than at the receptor level.

Intermittent energy restriction and weight loss: a systematic review.

BACKGROUND/OBJECTIVES: Intermittent energy restriction (IER) is an eating pattern of regular daily periods of restricted energy intake followed by periods of unrestricted energy intake. This is gaining prominence as an alternative weight-loss strategy to daily energy restriction (DER). The aim of this systematic review was to determine the effectiveness of IER on weight loss in overweight and obese adults and compare this with DER. SUBJECTS/METHODS: A systematic literature search was conducted using the CINAHL, Embase, Medline, PsycINFO, Cochrane and Scopus databases. Eight studies that assigned overweight or obese adults to IER or to a DER 'control' were deemed eligible for inclusion. RESULTS: All studies reported significant weight loss for IER groups. Average weight loss was approximately 0.2-0.8 kg per week. IER resulted in comparable weight loss to DER when overall energy restriction remained similar between diets. The majority of studies that reported body composition outcomes have shown equal efficacy for fat mass, fat-free mass and waist circumference. CONCLUSIONS: Weight loss was achieved in overweight and obese adults following IER and this loss was comparable to a DER diet. IER may be an effective alternative strategy for health practitioners to promote weight loss for selected overweight and obese people.

Glutathione transferases P1/P2 regulate the timing of signaling pathway activations and cell cycle progression during mouse liver regeneration.

Glutathione transferases (GST) are phase II enzymes catalyzing the detoxification of endogenous noxious compounds and xenobiotics. They also regulate phosphorylation activities of MAPKinases in a catalytic-independent manner. Previous studies have demonstrated the regulation of JNK-dependent pathway by GSTP1/2. Considering the crucial role of JNK in the early steps of the hepatocyte cell cycle, we sought to determine whether GSTP1/2 were essential for hepatocyte proliferation following partial hepatectomy (PH). Using a conventional double knockout mouse model for the Gstp1 and Gstp2 genes, we found that the lack of GSTP1/P2 reduced the rate of DNA replication and mitotic index during the first wave of hepatocyte proliferation. The lowered proliferation was associated with the decrease in TNFalpha and IL-6 plasma concentrations, reduced hepatic HGF expression and delayed and/or altered activation of STAT3, JNK and ERK1/2 signaling pathways. In addition, the expression and/or activation of cell cycle regulators such as Cyclin D1, CDK4, E2F1 and MCM7 was postponed demonstrating that the absence of GSTP1/2 delayed the entry into and progression through the G1 phase of the cell cycle and impaired the synchrony of proliferation in hepatocytes following PH. Furthermore, while JNK and its downstream targets c-Jun and ATF2 were activated during the early steps of the liver regeneration in wild-type animals, the constitutively active JNK found in the quiescent liver of Gstp1/2 knockout mice underwent a decrease in its activity after PH. Transient induction of antioxidant enzymes and nitric oxide synthase were also delayed or repressed during the regenerative response. Altogether our results demonstrate that GSTP1/2 are a critical regulators of hepatocyte proliferation in the initial phases of liver regeneration.

Characterization and localization of an immunoreactive growth hormone-releasing hormone precursor form in normal and tumoral human anterior pituitaries.

Arguments favor an in situ synthesis of GH-releasing hormone (GHRH) in the normal and tumoral human anterior pituitary. These tissues may express human (h) GHRH messenger RNA, contain hGHRH-(1-44)-NH2, and secrete in vitro an immunoreactive form (ir-form) of the peptide. Here, we characterize and localize the precursor of hGHRH in human anterior pituitary tissues using RIAs specific for the C-terminus or the midportion of hGHRH-(1-44)-NH2, size-exclusion chromatography, HPLC, Western blotting, and immunocytochemistry. The anterior pituitary ir-forms were compared to those found in hypothalamus, posterior pituitary, and GHRH-secreting endocrine pancreatic tumors. Three ir-forms of hGHRH with mol wt of 30-45, and 5 kilodaltons (kDa) were detected. The 30- to 45-kDa ir-form was very likely to consist of hGHRH bound to proteins. The 5-kDa ir-form represented mature forms of hGHRH. It was the major form in tissues actively synthesizing and/or secreting hGHRH. Nontumoral anterior pituitaries contained significant amounts of mature hGHRH. The 10-kDa form was identified as a hGHRH precursor ir-form. In addition to its expected presence in the hypothalamus and GHRH-secreting tumors, normal and tumoral human anterior pituitaries contained an identical ir-form of the hGHRH precursor. Cells immunoreactive for the hGHRH precursor were observed in pituitary adenomas. Evidence for precursor and mature ir-forms of hGHRH in anterior pituitary tissues provides conclusive arguments for the endogenous synthesis of the neuropeptide.

Presence of somatostatin receptors negatively coupled to adenylate cyclase in ectopic growth hormone-releasing hormone- and alpha-subunit-secreting tumors from acromegalic patients responsive to octreotide.

The functional study of SRIH receptors was performed in ectopic GHRH-secreting tumors from two patients with acromegaly; patient 1 presented with multiple endocrine neoplasia type 1 with GHRH- and insulin-secreting pancreatic tumors, and patient 2 presented with a multihormone-secreting carcinoid tumor (including GHRH and alpha-subunit secretion, as demonstrated by clinical and immunohistochemical studies). In both cases, plasma GH levels were responsive to octreotide. In patient 2, plasma GHRH and alpha-subunit levels were responsive to octreotide. In vitro perifusion studies of a tumor fragment from patient 1 also showed inhibition of GHRH secretion by SRIH. A high density of specific SRIH-binding sites was visualized by autoradiography in GHRH tumors from both patients. SRIH specific binding was much higher in the GHRH tumors (6.6-8.4 fmol/surface unit) than in the insulinoma (1.9 fmol/surface unit). The binding inhibition constant (IC50) was in the nanomolar range (0.9-3 nmol/L) in the GHRH tumors. SRIH-14 inhibited forskolin-stimulated adenylate cyclase in the GHRH tumors from both patients, but not in the insulinoma. The functional SRIH receptors negatively coupled to adenylate cyclase present in ectopic GHRH-secreting tumors mediate the inhibitory effect of octreotide on GHRH secretion and on previously underrecognized ectopic alpha-subunit secretion from carcinoid tumors.

Effect of polymorphism in the human glutathione S-transferase A1 promoter on hepatic GSTA1 and GSTA2 expression.

The patterns of expression of glutathione S-transferases A1 and A2 in human liver (hGSTA1 and hGSTA2, respectively) are highly variable, notably in the ratio of hGSTA1/hGSTA2. We investigated if this variation had a genetic basis by sequencing the proximal promoters (-721 to -1 nucleotides) of hGSTA1 and hGSTA2, using 55 samples of human liver that exemplified the variability of hGSTA1 and hGSTA2 expression. Variants were found in the hGSTA1 gene: -631T or G, -567T, -69C, -52G, designated as hGSTA1*A; and -631G, -567G, -69T, -52A, designated as hGSTA1*B. Genotyping for the substitution -69C > T by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP), showed that the polymorphism was widespread in Caucasians, African-Americans and Hispanics, and that it appeared to conform to allelic variation. Constructs consisting of the proximal promoters of hGSTA1*A, hGSTA1*B or hGSTA2, with luciferase as a reporter gene, showed differential expression when transfected into HepG2 cells: hGSTA1*A approximately hGSTA2 > hGSTA1*B. Similarly, mean levels of hGSTA1 protein expression in liver cytosols decreased significantly according to genotype: hGSTA1*A > hGSTA1-heterozygous > hGSTA1*B. Conversely, mean hGSTA2 expression increased according to the same order of hGSTA1 genotype. Consequently, the ratio of GSTA1/GSTA2 was highly hGSTA1 allele-specific. Because the polymorphism in hGSTA1 correlates with hGSTA1 and hGSTA2 expression in liver, and hGSTA1-1 and hGSTA2-2 exhibit differential catalysis of the detoxification of carcinogen metabolites and chemotherapeutics, the polymorphism is expected to be of significance for individual risk of cancer or individual response to chemotherapeutic agents.

Further evidence for a common mechanism for shedding of cell surface proteins.

Pro-TNF alpha, Steel factor, type II IL-1R and IL-2R alpha were expressed in COS-7 cells and the generation of their soluble forms was examined. The release of all four proteins was strongly stimulated by the phorbol ester PMA and completely blocked by a hydroxamate-based inhibitor of metalloproteases. COS-7 cell membranes were found to cleave various synthetic pro-TNF alpha peptides with the same specificity as a partially purified TNF alpha converting enzyme purified from human monocytic cells, suggesting that the same enzyme may be responsible for at least some of the COS-7 cell shedding activity.

Evidence of thyrotropin-releasing hormone (TRH) gene expression in rat anterior pituitaries and modulation by estrogens of TRH-like immunoreactivity and TRH-elongated peptide contents.

TRH gene expression in the anterior pituitary has previously been reported in the human in vivo and in the rat in vitro. Until now, modulation of this synthesis with glucocorticoids and thyroid hormones has been observed in rats. The present study demonstrates for the first time that the TRH gene is also expressed, in vivo, in the rat anterior pituitary and that anterior pituitary TRH-like immunoreactivity (TRH-LI) and elongated forms of the immediate TRH progenitor sequence (TRH-elongated peptide) contents are also modulated by estrogens (E2). To investigate the presence of proTRH mRNA in the rat anterior pituitary, total RNA was reverse transcribed (RT) and the RT products were then amplified by PCR. Treatments with E2 were performed on intact and ovariectomized (OVX) rats for 2 months. TRH-LI was measured by RIA with an antibody which did not recognize the TRH-like peptide. pGlu-Glu-Pro-NH2 (< EEP-NH2) (cross-reactivity < 0.1%) and was characterized further as TRH-LI by HPLC. TRH-elongated peptides were measured by EIA and characterized by Sephadex G-50 chromatography and immunoblotting (molecular mass 25-35 kDa). The plasma prolactin levels and the pituitary sizes were increased by E2 treatment in both intact and OVX rats. Anterior pituitary TRH-LI increased in intact E2-treated rats compared with intact rats (82.7 +/- 19.0 versus 39.6 +/- 3.6 fmol/mg protein; means +/- S.E.M.; P < 0.001). This increase was greater when E2 was administered to OVX rats (599.0 +/- 98.4 after E2 treatment versus 58.6 +/- 3.6 fmol/mg protein: P < 0.001). In intact rats, anterior pituitary TRH-elongated peptide contents were not modified by E2 treatment while they were significantly decreased in OVX E2-treated rats (144.6 +/- 8.8 versus 223.7 +/- 9.5 fmol/mg protein; P < 0.001). These results demonstrate TRH gene expression in the rat anterior pituitary in vivo and suggest that E2 treatment is responsible for an increase in anterior pituitary TRH-LI, together with a decrease in TRH-elongated peptide contents.

In two genes, synergism of steroid hormone action is not mediated by cooperative binding of receptors to adjacent sites.

Synergistic action of multiple steroid hormone response elements (HREs) has been proposed to be due to cooperative binding of receptors. We have studied the cooperativity of steroid hormone receptor binding to synergistic HREs in two natural genes. In the mouse mammary tumor virus long terminal repeat that contains four progesterone receptor binding sites, no cooperativity in receptor binding was observed between the single distal and the three proximal sites whereas a low level of cooperativity in receptor binding (about 2-fold) was found between the three proximal sites. This contrasted with the very strong synergism of these four HREs in stimulation of transcription. In the chicken vitellogenin II gene upstream sequences, an estrogen and a progestin response elements act synergistically. In this case again, no cooperativity of binding of the estrogen and progesterone receptors to their respective binding sites was observed. We therefore conclude that cooperative receptor binding may not always be required for synergistic action of multiple HREs.

Sliding of STOP proteins on microtubules: a model system for diffusion-dependent microtubule motility.

STOP proteins, of 145 kD, act substoichiometrically to block end-wise disassembly of microtubules. STOPs bind to microtubules either during microtubule assembly or when added at steady state, and when binding to the polymers is apparently irreversible. They are not measurably lost from polymers under competition conditions, and there is no measurable exchange between polymers. Nonetheless, STOP proteins exhibit an extraordinary behavior: they "slide" laterally on the surface of the microtubule. Displacement is assayed by forming hybrid microtubules in which cold stable or cold labile region subunits are labeled. Displacement of STOPs on the polymer with time will cause labeled subunits of cold-stable regions to become increasingly cold labile in a manner reciprocal to cold stabilization of previously cold-labile subunits. Because equilibrium exchange of STOP proteins onto and off the polymers can be ruled out, the displacement of STOPs relative to subunits can only be explained by lateral diffusion or "sliding." Axonal transport and mitotic mechanisms were discussed as implications of such a lateral translocation mechanism for microtubule-dependent motility.

Effect of the slow-release formulation of somatuline (BIM 23014) on estrogen-induced hyperprolactinemia and lactotroph hyperplasia in the female rat.

Somatuline, in common with other SRIH analogues, exerts antiproliferative and antisecretory activities on various tumors. Our purpose was to test the effectiveness of a slow-release formulation of somatuline on lactotroph hyperplasia and PRL hypersecretion induced by estrogens (17 beta E2) in rats. Female rats were primed with 17 beta E2 for 6 weeks before receiving somatuline (2 mg/kg) intramuscular injections every 10 days for one month. The mean anterior pituitary weight was 11.22 +/- 0.32 mg (mean +/- SEM) in non-estrogenized rats, 29.62 +/- 1.63 mg in 17 beta E2-primed rats and 23.58 +/- 1.26 mg in 17 beta E2-primed somatuline-treated rats. Mean plasma PRL level was 5.63 +/- 0.97 ng/ml, 182.37 +/- 27.55 ng/ml and 113.89 +/- 15.07 ng/ml in the same groups respectively. Thus, the 17 beta E2-induced pituitary enlargement and hyperprolactinemia were 20% and 38% lower respectively when animals were treated with somatuline during the last month of estrogenization. The 17 beta E2-induced increase in PRL cell density was also reduced by somatuline treatment. We conclude that the slow-release formulation of somatuline impedes 17 beta E2-induced hyperprolactinemia and pituitary enlargement concomittantly, at least in part by acting on lactotroph proliferation.

Pharmacokinetics of new testosterone transdermal therapeutic systems in gonadotropin-releasing hormone antagonist-suppressed normal men.

In a phase I single-center, open, randomized pilot study with a three-way cross-over design the pharmacokinetics of three testosterone-containing transdermal therapeutic systems were evaluated in healthy male volunteers. Testosterone TTS HEXAL type 1 and 2 are nonscrotal membrane patches differing in the kind of adhesive used. 6 subjects were treated with low dose Testosterone TTS type 1, high dose Testosterone TTS type 1 and low dose Testosterone TTS type 2. To eliminate the influence of endogenous serum testosterone, the endogenous testosterone secretion was suppressed by the GnRH antagonist cetrorelix. In all subjects under GnRH antagonist treatment a marked suppression of LH, FSH, testosterone, DHT and estradiol was observed. Physiologic testosterone levels were achieved during the 24-hour-application period. Maximal serum levels were reached after 4 hours with both TTS systems. Both systems appear suited for further testing because both enable a physiological circadian profile to be achieved. GnRH-antagonist pretreatment is a useful model to evaluate the effect of exogenous testosterone in clinical studies, when, due to fluctuations in endogenous hormone levels, an estimation of the proportion of exogenous steroid is not possible.