Palmitoyl-carnitine increases RyR2 oxidation and sarcoplasmic reticulum Ca2+ leak in cardiomyocytes: Role of adenine nucleotide translocase.

Long chain fatty acids bind to carnitine and form long chain acyl carnitine (LCAC), to enter into the mitochondria. They are oxidized in the mitochondrial matrix. LCAC accumulates rapidly under metabolic disorders, such as acute cardiac ischemia, chronic heart failure or diabetic cardiomyopathy. LCAC accumulation is associated with severe cardiac arrhythmia including ventricular tachycardia or fibrillation. We thus hypothesized that palmitoyl-carnitine (PC), alters mitochondrial function leading to Ca(2+) dependent-arrhythmia. In isolated cardiac mitochondria from C57Bl/6 mice, application of 10µM PC decreased adenine nucleotide translocase (ANT) activity without affecting mitochondrial permeability transition pore (mPTP) opening. Mitochondrial reactive oxygen species (ROS) production, measured with MitoSOX Red dye in isolated ventricular cardiomyocytes, increased significantly under PC application. Inhibition of ANT by bongkrekic acid (20 µM) prevented PC-induced mitochondrial ROS production. In addition, PC increased type 2 ryanodine receptor (RyR2) oxidation, S-nitrosylation and dissociation of FKBP12.6 from RyR2, and therefore increased sarcoplasmic reticulum (SR) Ca(2+) leak. ANT inhibition or anti-oxidant strategy (N-acetylcysteine) prevented SR Ca(2+) leak, FKBP12.6 depletion and RyR2 oxidation/S-nitrosylation induced by PC. Finally, both bongkrekic acid and NAC significantly reduced spontaneous Ca(2+) wave occurrences under PC. Altogether, these results suggest that an elevation of PC disturbs ANT activity and alters Ca(2+) handling in a ROS-dependent pathway, demonstrating a new pathway whereby altered FA metabolism may contribute to the development of ventricular arrhythmia in pathophysiological conditions.

Adaptive divergence in embryonic thermal plasticity among Atlantic salmon populations.

In the context of global changes, the long-term viability of populations of endangered ectotherms may depend on their adaptive potential and ability to cope with temperature variations. We measured responses of Atlantic salmon embryos from four populations to temperature variations and used a QST -FST approach to study the adaptive divergence among these populations. Embryos were reared under two experimental conditions: a low temperature regime at 4 °C until eyed-stage and 10 °C until the end of embryonic development and a high temperature regime with a constant temperature of 10 °C throughout embryonic development. Significant variations among populations and population × temperature interactions were observed for embryo survival, incubation time and length. QST was higher than FST in all but one comparison suggesting an important effect of divergent selection. QST was also higher under the high-temperature treatment than at low temperature for length and survival due to a higher variance among populations under the stressful warmer treatment. Interestingly, heritability was lower for survival under high temperature in relation to a lower additive genetic variance under that treatment. Overall, these results reveal an adaptive divergence in thermal plasticity in embryonic life stages of Atlantic salmon suggesting that salmon populations may differentially respond to temperature variations induced by climate change. These results also suggest that changes in temperature may alter not only the adaptive potential of natural populations but also the selection regimes among them.

[Creation of software to help cardiac surgeons: CordaBase].

BACKGROUND: The writing of surgical and hospitalization reports is time-consuming and does not necessarily enable the increment of a statistical database, tool that is indispensable nowadays to evaluate unit activity or to carry out scientific studies. In order to prevent this double data capture, a computer tool, named CordaBase, has been developed by surgeons and set up in a cardiac surgery unit. MATERIALS AND METHODS: CordaBase is an interactive software that stores medical data. Thanks to its intuitive interface, CordaBase stores data which is classified chronologically in the following categories: past medical history, preoperative assessment, operating gesture, stay in intensive care unit, stay in wards and evolution/monitoring after discharge. This date, stored in an Access base, are then used in the creation of personalized surgical and hospitalization reports. All the data is permanently available and can be used for the carrying out of scientific works or for the evaluation of the unit activity. RESULTS: From March 2009 to December 2010, 2617 consecutive patients operated on in a Cardiac Surgery Unit were recorded prospectively in the software. All of this stored data assisted the surgeon in his or her administrative tasks, thanks to personalized surgical and hospitalization reports, immediately at the secretariat's disposal. The database, which is requisitely filled by administrative work, enables the carrying out of any statistical study on all unit activity. CONCLUSION: With a hindsight of almost 2 years, CordaBase has proven its usefulness in an active cardiac surgery unit, both on an administrative and scientific level. The computerized reports have lightened the medical secretariat's workload and statistical studies have now become possible without having to take the paper medical files out again. In the years to come, the accumulation of medical data prospectively or retrospectively stored will surely confirm the potential of the use of such a software.

Protective effects of transgenic human endothelial protein C receptor expression in murine models of transplantation.

Thrombosis and inflammation are major obstacles to successful pig-to-human solid organ xenotransplantation. A potential solution is genetic modification of the donor pig to overexpress molecules such as the endothelial protein C receptor (EPCR), which has anticoagulant, anti-inflammatory and cytoprotective signaling properties. Transgenic mice expressing human EPCR (hEPCR) were generated and characterized to test this approach. hEPCR was expressed widely and its compatibility with the mouse protein C pathway was evident from the anticoagulant phenotype of the transgenic mice, which exhibited a prolonged tail bleeding time and resistance to collagen-induced thrombosis. hEPCR mice were protected in a model of warm renal ischemia reperfusion injury compared to wild type (WT) littermates (mean serum creatinine 39.0 ± 2.3 µmol/L vs. 78.5 ± 10.0 µmol/L, p < 0.05; mean injury score 31 ± 7% vs. 56 ± 5%, p < 0.05). Heterotopic cardiac xenografts from hEPCR mice showed a small but significant prolongation of survival in C6-deficient PVG rat recipients compared to WT grafts (median graft survival 6 vs. 5 days, p < 0.05), with less hemorrhage and edema in rejected transgenic grafts. These data indicate that it is possible to overexpress EPCR at a sufficient level to provide protection against transplant-related thrombotic and inflammatory injury, without detrimental effects in the donor animal.

Population differences in response to hypoxic stress in Atlantic salmon.

Understanding whether populations can adapt to new environmental conditions is a major issue in conservation and evolutionary biology. Aquatic organisms are increasingly exposed to environmental changes linked with human activities in river catchments. For instance, the clogging of bottom substratum by fine sediments is observed in many rivers and usually leads to a decrease in dissolved oxygen concentrations in gravel beds. Such hypoxic stress can alter the development and even be lethal for Atlantic salmon (Salmo salar) embryos that spend their early life into gravel beds. In this study, we used a common garden experiment to compare the responses to hypoxic stress of four genetically differentiated and environmentally contrasted populations. We used factorial crossing designs to measure additive genetic variation of early life-history traits in each population. Embryos were reared under normoxic and hypoxic conditions, and we measured their survival, incubation time and length at the end of embryonic development. Under hypoxic conditions, embryos had a lower survival and hatched later than in normoxic conditions. We found different hypoxia reaction norms among populations, but almost no population effect in both treatments. We also detected significant sire × treatment interactions in most populations and a tendency for heritability values to be lower under stressful conditions. Overall, these results reveal a high degree of phenotypic plasticity in salmon populations that nevertheless differ in their adaptive potential to hypoxia given the distinct reaction norms observed between and within populations.

The role of body size versus growth on the decision to migrate: a case study with Salmo trutta.

In a population exhibiting partial migration (i.e. migration and residency tactics occur in the same population), the mechanisms underlying the tactical choice are still unclear. Empirical studies have highlighted a variety of factors that could influence the coexistence of resident and migratory individuals, with growth and body size considered to be key factors in the decision to migrate. Most studies suffer from at least one of the two following caveats: (1) survival and capture probabilities are not taken into account in the data analysis, and (2) body size is often used as a proxy for individual growth. We performed a capture-mark-recapture experiment to study partial migration among juvenile brown trout Salmo trutta at the end of their first year, when a portion of the population emigrate from the natal stream while others choose residency tactic. Bayesian multistate capture-recapture models accounting for survival and recaptures probabilities were used to investigate the relative role of body size and individual growth on survival and migration probabilities. Our results show that, despite an apparent effect of both size and growth on migration, growth is the better integrative parameter and acts directly on migration probability whereas body size acts more strongly on survival. Consequently, we recommend caution if size is used as a proxy for growth when studying the factors that drive partial migration in juvenile salmonid species.

The autism-associated Meis2 gene is necessary for cardiac baroreflex regulation in mice.

Recent understanding of Autism Spectrum Disorder (ASD) showed that peripheral primary mechanosensitive neurons involved in touch sensation and central neurons affected in ASD share transcriptional regulators. Mutant mice for ASD-associated transcription factors exhibit impaired primary tactile perception and restoring those genes specifically in primary sensory neurons rescues some of the anxiety-like behavior and social interaction defects. Interestingly, peripheral mechanosensitive sensory neurons also project to internal organs including the cardiovascular system, and an imbalance of the cardio-vascular sympathovagal regulation is evidenced in ASD and intellectual disability. ASD patients have decreased vagal tone, suggesting dysfunction of sensory neurons involved in cardio-vascular sensing. In light of our previous finding that the ASD-associated Meis2 gene is necessary for normal touch neuron development and function, we investigated here if its inactivation in mouse peripheral sensory neurons also affects cardio-vascular sympathovagal regulation and baroreflex. Combining echocardiography, pharmacological challenge, blood pressure monitoring, and heart rate variability analysis, we found that Meis2 mutant mice exhibited a blunted vagal response independently of any apparent cardiac malformation. These results suggest that defects in primary sensory neurons with mechanosensitive identity could participate in the imbalanced cardio-vascular sympathovagal tone found in ASD patients, reinforcing current hypotheses on the role of primary sensory neurons in the etiology of ASD.

Long-term endoscopic follow-up after sleeve gastrectomy.

BACKGROUND: Endoscopic follow-up after sleeve gastrectomy (SG) sometime reveals worrisome findings as the presence of major digestive lesions such as esophagitis, Barrett's esophagus (BE), and also esophageal cancer. OBJECTIVES: The aim of this study was to investigate the frequency and severity of esophageal and gastric lesions after SG. METHODS: Our team collected the results of esogastric endoscopies performed on patients who underwent SG up to five years before in our hospital, from April 2010 to August 2014. Summons were sent by mail to all patients operated on between those dates. The results were collected from January 2018 to June 2019. RESULTS: Of the 765 patients who underwent SG up to five years before, only 78 (10.2%) agreed to undergo an upper digestive endoscopy. The average age before surgery was 51 years (range: 25-70 years). The mean preoperative body mass index (BMI) was 44.2±4.6kg/m2. For 12 out of these 78 patients (15.4%) it was revisional surgery: 9 SG after gastric banding, and 3 revisional SG (Re-SG). With an average follow-up of 6.3±0.8 years, the endoscopic results of the 78 patients were found to be normal in 31 cases (39.7%): gastritis was found in 28 patients (35.9%), severe grade C or D esophagitis was found in 15 cases (19.2%), hiatal hernia in 18 cases (23.1%), a benign gastric polyp in 2 cases (2.6%). Of the 28 patients with gastritis, HelicobacterPylori was detected in 8 cases (28.6%). No cancer was diagnosed, and BE after SG was found in only one case (1.3%) (normal before surgery). Six of 15 patients with esophagitis (40%) had reflux symptoms. Fourteen of these patients (93.3%) developed de novo esophagitis. CONCLUSION: Only 10.2% of operated patients agreed to a long-term esogastric endoscopy. The frequency and severity of endoscopic anomalies observed with an average follow-up of more than 6 years pleads for a policy of systematic upper endoscopies of long-term control after SG.

Application of the Life Cycle Management of Analytical methods concept to a HPTLC-DPPH assay method for acteoside content in industrial extracts of Plantago lanceolata L.

Analytical methods used for quality control of plants and plant extracts are based on the identification and quantification of chemical markers to manage batch reproducibility and efficacy. The aim of this work was to assess the performance of a High Performance Thin Layer Chromatography (HPTLC) method developed for quality control of industrial dry extracts of ribwort plantain (P. lanceolata L.), using 2,2-diphenyl 1-picrylhydrazyle (DPPH) effect directed chemical reaction for antioxidant activity of acteoside, a phenylethanoid glycoside commonly used as a marker for P. lanceolata L., and to demonstrate the applicability of the Life Cycle Management of Analytical Methods concept to quantitative HPTLC-DPPH methods. The first step was the determination of the Analytical Target Profile (ATP) and Target Measurement Uncertainty (TMU), taking into account the quality control requirements for such extracts and the detection method applicable range. Once the desired range was established, an evaluation of the calibration function was conducted using several calibration models. Due to the lack of reference samples, spiked samples were used to evaluate the accuracy of the method by means of Total Analytical Error (TAE) determination, using prediction intervals calculation for the selected calibration functions. Measurement Uncertainty (MU) was also estimated, allowing the final choice of the calibration function to be used for quality control, giving the most fit for purpose performance level in accordance with the product specifications. As Life Cycle Management of the method also includes its routine use, the Measurement Uncertainty was checked on spiked and unspiked extract samples with different dilution levels, in order to verify the accordance of results between spiked and unspiked samples and to prepare a replication strategy to be applied during the routine use of the method.

Prospective, multicentric, comparative study between sleeve gastrectomy and Roux-en-Y gastric bypass, 277 patients, 3 years follow-up.

BACKGROUND: Laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en Y gastric bypass (LRYGB) are commonly performed, but few studies have shown superiority of one strategy over the other. OBJECTIVE: Simultaneously compare LSG and LRYGB in terms of weight loss and morbimortality over a 36-month follow-up period. SETTING: University hospital and bariatric surgery centers, France. METHODS: Prospective, comparative study between LSG and RYGBP. The primary endpoint of this study was a joint hypothesis during the 36-month follow-up: the first primary outcome pertained to the frequency of patients with an excess weight loss (EWL) greater than 50% (% EWL>50%) after LSG or RYGB; the second primary outcome was defined as a composite endpoint of at least one major complication. Secondary objectives were regression of comorbidities and improvement in quality of life. RESULTS: Two hundred and seventy-seven patients were included (91 RYGBP, 186 LSG). The mean age was 41.1±11.1 years, and average preoperative body mass index of 45.3±5.5kg/m2. After 36months, the %EWL>50% was not inferior in the case of LSG (82.2%) relative to LRYGB (82.1%); while major complications rates were significantly higher in LRYGB (15.4%) vs. LSG (5.4%, P=0.005). After 36months, all secondary objectives were comparable between groups while only gastroesophageal reflux disease (GERD) increased in LSG group and decreased in LRYGB group. CONCLUSIONS: LSG was found non-inferior to LRYGB with respect to weight loss and was associated with lower risk of major complications during a 3-year follow-up. But GERD increased in LSG group and decreased in LRYGB group.

Pig thrombomodulin binds human thrombin but is a poor cofactor for activation of human protein C and TAFI.

Incompatibility between pig thrombomodulin (TM) and primate thrombin is thought to be an important factor in the development of microvascular thrombosis in rejecting pig-to-primate xenografts. To examine this interaction at the molecular level, we cloned pig TM and measured its ability to bind human thrombin and act as a cofactor for the activation of human protein C and TAFI. The 579-residue pig TM protein showed approximately 69% sequence identity to human TM. Within the EGF domains necessary for binding of thrombin (EGF56), protein C (EGF4) and TAFI (EGF3), all of the amino acids previously identified as critical for the function of human TM, with the exception of Glu-408 in EGF5, were conserved in pig TM. Comparison of transfected cells expressing pig or human TM demonstrated that both proteins bound human thrombin and inhibited its procoagulant activity. However, pig TM was a poor cofactor for the activation of human protein C and TAFI, with domain swapping showing that EGF5 was the most important determinant of compatibility. Thus, while pig TM may be capable of binding thrombin generated in the vicinity of xenograft endothelium, its failure to promote the activation of human protein C remains a significant problem.

The epidemiology and virology of hepatitis C virus genotype 5 in central France.

BACKGROUND: We previously reported high prevalence of hepatitis C virus genotype 5a (HCV 5) (14%) in Central France. AIM: To identify the risk factors associated with HCV5 infection and to characterize local HCV5 lineages. METHOD: A case-control study and phylogenetic analysis were conducted. RESULTS: In all, 131 HCV5 and 343 HCV non 5 infected patients were enrolled. No HCV5 patient was born in sub-Saharan Africa and only two were injection drug user. HCV5 contamination was associated with living in a rural area called Vic le Comte (VLC) in non-transfused patients (OR = 17.7), with transfusion in patients living outside VLC (OR = 3.8) and with receiving injections in patients from VLC (OR = 3.1). More than 80% of the patients from outside VLC were contaminated by transfusion and those from VLC mainly by an iatrogenic factor - injections performed before 1972 by the local physician. Phylogenetic analysis of HCV5 isolates evidenced no distinct genetic cluster, but close relationships between the isolates of spouse pairs and between blood donors and recipients. CONCLUSIONS: Our results suggest that HCV5 spread in our district by iatrogenic route before 1972 and then via transfusion to the whole district. Collaborative studies are underway to study viral sequences from different parts of Africa and Europe to estimate the origin of our HCV 5a strains.

A new locus for autosomal dominant intracranial aneurysm, ANIB4, maps to chromosome 5p15.2-14.3.

BACKGROUND: Intracranial aneurysms (IA) are dilatations of intracranial arteries that occur most commonly at arterial bifurcations. Unruptured IA are present in approximately 1-2% of the population aged over 30 years of age. Aneurysms are only rarely symptomatic unless they rupture, which typically results in a subarachnoid haemorrhage associated with high morbidity and mortality. METHODS: A large French Canadian (FC) family (Aneu60) was identified which contained 12 affected individuals with intracranial aneurysms. Nine of the affected patients and three unaffected individuals were sent for an 8 cM genome-wide scan. Multipoint and two-point methods were used to analyse the scan data by using a dominant parametric model. RESULTS: We identified an IA susceptibility locus (ANIB4) located on chromosome 5p15.2-14.3. The locus was found by genome-wide linkage analysis and follow up analyses provided a maximum multipoint LOD score of 3.57 over the region. An identical haplotype segment of 7.2 Mb was found in a second FC pedigree and contributes to the refinement of the candidate gene interval. CONCLUSIONS: Our results indicate that there is a major gene locus on chromosome 5p.

Left ventricular assist device-related infections: a multicentric study.

OBJECTIVES: The implantable left ventricular assist device (LVAD) is a major therapeutic development for end-stage heart failure in selected patients. As their use is expanding, infectious complications are emerging, with limited data available to guide their management. We aimed to better characterize LVAD-related infections. METHODS: We enrolled all consecutive patients diagnosed with LVAD-related infections in three referral centres in France, using a standardized definition of infections in patients with LVAD. Data were collected from medical charts using a standardized questionnaire. RESULTS: Between 2007 and 2012, 159 patients received LVAD for end-stage heart failure. Among them, 36 (22.6%; 5 women, 31 men) presented at least one infectious complication, after a median time of 2.9 months from LVAD implantation (interquartile range, 1.8-7.5), with a median follow up of 12 months (interquartile range 8-17). Main co-morbidities were alcoholism (33%), diabetes (11%) and immunosuppression (11%). Mean age at implantation was 51 (±11) years. LVAD were implanted as bridge-to-transplantation (n=22), bridge-to-recovery (n=8), destination therapy (n=4), or unspecified (n=2). LVAD-related infections were restricted to the driveline exit site (n=17), had loco-regional extension (n=13), or reached the internal pump (n=3). The main bacteria isolated were Staphylococcus aureus (n=20), coagulase-negative staphylococci (n=7), Enterobacteriaceae (n=14), Pseudomonas aeruginosa (n=10) and Corynebacterium sp. (n=7), with polymicrobial infections in 19 cases. LVAD could be retained in all patients, with the use of prolonged antibacterial treatment in 34 (94%), and debridement in 17 (47%). One patient died due to LVAD-associated infection. CONCLUSIONS: LVAD-related infections are common after LVAD implantation, and may be controlled by prolonged antibiotic treatment.

Neuron-specific expression of mutant superoxide dismutase 1 in transgenic mice does not lead to motor impairment.

Mutations were identified in the Cu/Zn superoxide dismutase gene (SOD1) in approximately 15% of patients with familial amyotrophic lateral sclerosis. Transgenic animals expressing mutant SOD1 in all tissues develop an ALS-like phenotype. To determine whether neuron-specific expression of mutant SOD1 is sufficient to produce such a phenotype, we generated transgenic animals carrying the G37R mutation that is associated with the familial form of ALS (FALS), which is driven by the neurofilament light chain promoter. The transgenic animals express high levels of the human SOD1 protein in neuronal tissues, especially in the large motor neurons of the spinal cord, but they show no apparent motor deficit at up to 1.5 years of age. Our animal model suggests that neuron-specific expression of ALS-associated mutant human SOD1 may not be sufficient for the development of the disease in mice.

Fatty acid composition of the lipids of Pseudomonas mildenbergii. Presence of a fatty acid containing two conjugated double bonds.

The whole cell fatty acids of Pseudomonas mildenbergii were extracted and separated, as methyl esters, into non-hydroxylated (60.6%) and hydroxylated (39.4%) esters. The main component of the hydroxy-ester fraction was methyl 3D-hydroxydecanoate. The non-hydroxylated fraction mainly consisted of methyl 2-decenoate, the methyl ester of a C-12 acid having two conjugated double bonds, methyl palmitate, methyl methylene-hexadecanoate and methyl vaccenate.

Evidence for a dual effect of gamma-aminobutyric acid on thyrotropin (TSH)-releasing hormone-induced TSH release from perifused rat pituitaries.

The effects of gamma-aminobutyric acid (GABA) on the spontaneous and TRH-induced TSH release were investigated in vitro on perifused rat pituitaries. The dynamic pattern of TSH release was measured in response to a 6-min pulse of TRH (10 nM) with or without GABA addition. GABA had no effect on spontaneous TSH release but exhibited a dual effect on TSH-stimulated release according to the dose (as calculated by the induced-basal ratio): a potentiation of the TSH response to TRH at the lowest concentrations tested (less than or equal to 10 nM) and an inhibition for GABA concentrations equal or higher than 100 nM. The GABA potentiation was mimicked by muscimol (10 microM) and isoguvacine (10 nM) but not by baclofen (1 microM). Bicucullin (1 microM) or picrotoxin (1 microM) added 15 min before GABA was unable to reverse the GABA potentiation of the TSH response, although SR 95103 (1 and 10 microM), a specific GABA A antagonist, partially or totally antagonized this response. Diazepam (7 nM) was able to potentiate the TSH response by 216% when GABA was added to the system at a concentration (60 nM) which does not modify by itself the TSH response. The inhibitory effect of GABA (100 nM) was completely abolished by bicucullin (1 microM), by picrotoxin (1 microM), and by SR 95103 (1 microM). Picrotoxin not only blocked the inhibitory action of GABA but significantly (P less than 0.05) potentiated the TSH response to TRH. Our data suggest a dual GABA-ergic control of TRH-stimulated TSH release directly on the pituitary, probably mediated by two different kinds of GABA receptors: a GABA A receptor site mediating the inhibitory effect and a nonclassical GABA A receptor site of higher affinity for its stimulatory action.

Benzodiazepines inhibit thyrotropin (TSH)-releasing hormone-induced TSH and growth hormone release from perifused rat pituitaries.

The perifusion technique was used to investigate the action of diazepam (DZ), a benzodiazepine molecule known to compete for TRH receptor binding in rat pituitary, on TRH-induced TSH and GH release. The release kinetics for the two hormones from quartered pituitaries were measured in response to a 6-min pulse of TRH (10 nM), without or with DZ addition for a period of 30 min before and during the TRH pulse, plus an additional 15-min period. The dynamic patterns of TSH and GH release in response to TRH were characterized by a rapid increase in hormone release, declining slowly over the next 20 min. The rate of release represented 2.98 +/- 0.02 (+/- SE) and 1.75 +/- 0.06 times the corresponding basal level for TSH and GH, respectively, when evaluated over the first 15 min of the response to TRH. Addition of increasing doses of DZ suppressed the stimulatory effect of TRH in a dose-related manner, with an ID50 of 3 nM for both TSH and GH. The maximal effect of DZ was obtained with a concentration of 10 nM for both hormones. Ro 15-1788 (100 nM), a selective antagonist of the central type of benzodiazepine-binding sites (added to the perifusion system 30 min before DZ and then during the whole period of DZ perifusion), completely abolished (P less than 0.01) the inhibitory effect of DZ (10 nM) on the TRH-induced TSH and GH responses. When added alone before the TRH pulse, Ro 15-1788 had no effect on the TSH response to TRH. In contrast, PK 11,195 (100 nM), a selective antagonist of the nonneuronal benzodiazepine-binding sites, was unable to abolish the inhibitory action of DZ on TRH-stimulated TSH release. In addition, the effects of four other types of benzodiazepine (flurazepam, chlordiazepoxide, midazolam, and medazepam), all tested at a 10-nM concentration, corroborated these findings. Furthermore, DZ inhibition of the TSH response was nullified by picrotoxin (1 microM), but not by bicuculline (1 microM), two gamma-aminobutyric acid antagonists that had no effect, by themselves, on this response. For comparison, the effect of DZ (10 nM) was also tested on the release of GH in response to human GH-releasing factor-(1-44)-NH2 (10 nM) and was found to be ineffective.(ABSTRACT TRUNCATED AT 400 WORDS)

Somatostatin blocks the potentiation of TRH-induced TSH secretion from perifused pituitary fragments and the change in intracellular calcium concentrations from dispersed pituitary cells elicited by prepro-TRH (PS4) or by tri-iodothyronine.

TRH and somatostatin (SRIH) are well known to stimulate and to inhibit TSH secretion respectively. However, the mechanisms underlying the effect of SRIH on thyrotrophs are still not understood. We have previously shown in vitro that the TSH response to TRH is potentiated in a Ca(2+)-dependent fashion through the activation of dihydropyridine (DHP)-sensitive Ca2+ channels by the prepro-TRH (160-169) cryptic peptide (PS4) and tri-iodo-L-thyronine (T3), when the hormone was added shortly before a TRH pulse in order to avoid its genomic effect. Using perifused rat pituitary fragments, the present study has shown that SRIH inhibits, in a dose-dependent manner, the TSH response to physiological concentration of TRH (10 nM) and reverses the Ca(2+)-dependent potentiation of that response induced either by PS4 or by T3. We have also demonstrated that the inhibition by SRIH of the T3 potentiation of TRH-induced TSH secretion is pertussis toxin-sensitive. Our data suggest that SRIH inhibits the PS4 and T3 potentiation of TRH-induced TSH secretion through the inactivation of DHP-sensitive Ca2+ channels. Using primary cultures of rat anterior pituitary cells and videomicroscopy, we have already demonstrated that TRH, as well as PS4 and T3, are able to increase intracellular Ca2+ concentration ([Ca2+]i) rapidly, in 15 s. Our study has shown that SRIH is able to abolish the acute rise in [Ca2+]i induced either by PS4 or by T3. Since [Ca2+]i responses to PS4 and T3 are also abolished by the DHP nifedipine, our results suggest that [Ca2+]i changes in PS4- or T3-sensitive pituitary cells depend directly or indirectly on the activation of DHP-sensitive Ca2+ channels and that the inhibitory effect of SRIH may be mediated by inactivation of this type of channel.

[Chemotaxonomy of gram-positive bacteria metabolizing beta-caryophyllene]. / Chimiotaxonomie de bactéries à gram positif métabolisant le beta-caryophyllène.

Chemotaxonomic identification of coryneform bacteria metabolizing b-caryophyllene was attempted. The following phospholipids were identified as main components of the bacterial extracts: cardiolipids, phosphatidylethanolamine, phosphatidylinositol and mannosides of phosphatidylinositol. Saponification of the lipid extracts gave a mixture of hydroxylated and nonhydroxylated fatty acids. Among the latter, oleic and tuberculostearic acids were identified. The hydroxylated fatty acids were analysed by thin-layer chromatography and mass spectrometry (as methyl esters). From the results thus obtained, the strains appeared to be more closely related to the genus Rhodococcus than to the genus Nocardia.