Direct effect of melatonin on Syrian hamster testes: melatonin subtype 1a receptors, inhibition of androgen production, and interaction with the local corticotropin-releasing hormone system

Besides the hypothalamus and pituitary, melatonin action at the testicular level has been recently suggested. Therefore, we investigated in the Syrian hamster, a well-characterized seasonal breeder, melatonin action on Leydig cells, testicular expression of melatonergic receptors, and possible interactions between melatonin receptors and the previously identified testicular serotoninergic and CRH systems. In isolated Leydig cells from active testes of adult hamsters kept in a long-day (14 h light, 10 h dark) photoperiod and from regressed testes of adult animals exposed to a short-day photoperiod during 16 wk (6 h light, 18 h dark), melatonin significantly reduced human chorionic gonadotropin-stimulated production of cAMP and the main androgens: testosterone and androstane-3alpha,17beta-diol, respectively, and decreased the expression of steroidogenic acute regulatory protein, P450 side chain cleavage, 3beta-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase. In Leydig cells exposed to a short-day photoperiod during 16 wk, melatonin stimulated the conversion of testosterone into 5alpha-reduced androgens by inducing 5alpha-reductase isoform 1, and controlled androstane-3alpha,17beta-diol production by inhibiting 3alpha-hydroxysteroid dehydrogenase expression. Melatonin subtype (mel1a) receptors were detected in Leydig cells. Although the local serotonin system did not mediate melatonin action on androgen production, melatonergic effect on steroidogenesis involved the interaction between mel1a receptors and the inhibitory CRH system. Moreover, melatonin significantly increased CRH mRNA levels and production in hamster Leydig cells expressing CRH subtype 1 receptors. Our studies indicate that melatonin may act as a local inhibitor of human chorionic gonadotropin-stimulated cAMP and androgen production through mel1a receptors, down-regulation of steroidogenic acute regulatory protein, and key steroidogenic enzymes expression and its interaction with the local CRH system.     

Determinants of immediate and long-term results of subclavian and innominate artery angioplasty.

BACKGROUND: Percutaneous angioplasty (PTA) is widely used in the treatment of subclavian/innominate artery obstruction, but factors of long-term PTA outcome are poorly understood. Our aim was to evaluate the efficiency of PTA on symptom resolution and identify determinants of long-term outcome. METHODS AND RESULTS: Seventy-six lesions were treated in 75 patients (58.7% men) aged 60 +/- 8.5 years. PTA was successful in 70 (93.3%) patients, including 58/58 (100%) stenotic lesions and 13/18 (72.2%) occlusions. The mean stenosis grade (QCA) was reduced from 78.9% +/- 16.6% to 13.5% +/- 10.7% (P < 0.01). A great majority of lesions (87.1%) were stented. In 5 (7.1%) high-risk lesions a proximal or distal neuroprotection system was used. There were no strokes or embolic events. Minor complications occurred in 7 (9.3%) cases. Fifty-seven (89%) of 64 symptomatic patients had complete symptom resolution. The mean follow-up was 24.4 +/- 15.5 months (up to 66 months). Ten restenoses (15.6%), including 9 (13.8%) in-stent restenoses and 1 (16.7%) restenosis after balloon angioplasty, were diagnosed in 64 patients and followed up for at least 6 months. Nine symptomatic restenoses were successfully treated with repeated angioplasty. Cox multivariable analysis revealed the following independent predictors of restenosis: implantation of more than one stent (P = 0.005), low stent diameter (P = 0.088), and postprocedural systolic blood pressure difference between upper extremities (P = 0.044). CONCLUSIONS: PTA is a safe and effective method for the treatment of the subclavian/innominate artery obstruction and leads to symptom resolution in majority of patients. Restenosis is not frequent and it can be effectively treated with repeat angioplasty. Low stent diameter, implantation of two stents, and upper limb systolic blood pressure difference are independent predictors of restenosis.     

Prostaglandin production by human osteoclasts in culture

OBJECTIVE: Prostaglandins (PG) are important mediators of bone metabolism with direct and indirect effects on bone cells. They may have important effects on osteoclasts, but it is not known if these cells can synthesize PG. We used 2 experimental models in order (1) to determine the presence and functionality of cyclooxygenase (COX) and phospholipase A2 (PLA2) enzymes in human osteoclasts and (2) to study their role in cell metabolism. METHODS: Experiments were undertaken on authentic human osteoclasts extracted from human fetuses (fhOC) and on human osteoclast-like (hOCL) cells differentiated from peripheral blood mononuclear cells. The presence of COX proteins was determined by immunohistochemistry. COX and PLA2 enzymatic activity was evaluated at the single-cell level by fluorescence microscopy. An enriched population of hOCL cells was used to evaluate total PG production and the influence of COX activity on bone resorption. RESULTS: COX-1 was expressed in the cytoplasm and COX-2 was distributed mainly near the nuclear membrane of osteoclasts. These cells showed a high basal level of COX activity that could be inhibited by pretreatment with COX inhibitors. Cytosolic PLA2 was present in both models. Human osteoclasts actively produced PG, and the COX-1 pathway was implicated in the control of bone resorption. CONCLUSION: These results indicate that PG may be important autacoids for the control of osteoclast biology and that the COX-1 pathway is implicated in the inhibition of bone resorption.     

Prenatal diagnosis of trisomy 13: analysis of 28 cases.

OBJECTIVE: The purpose of this study was to investigate the role of second-trimester sonographic examination in the prenatal diagnosis of trisomy 13. METHODS: Of 22,150 fetal chromosome analyses, 28 fetuses with trisomy 13 were found between 1990 and 2004. Sonographic findings of this aneuploidy were analyzed in this study. RESULTS: The average maternal age was 32.4 years; the average gestational age was 19.5 weeks. There was an 89.3% (n = 25) total prevalence of sonographic abnormalities in fetuses with trisomy 13 in this series. Major (structural) malformations were seen in 23 cases (82.1%), whereas minor anomalies were detected on sonography in 16 cases (57.1%). Although in 2 fetuses 1 minor anomaly was the only sonographic sign of trisomy 13, other cases with minor anomalies (87.5% [n = 14]) were multiplex malformations, in which combinations of major and minor anomalies were detected on sonography. The most frequently seen structural abnormalities were central nervous system and facial anomalies (64.3% [n = 18]). Among central nervous system anomalies, ventriculomegaly and holoprosencephaly were seen most frequently. Cardiovascular anomalies were detected in 53.6% (n = 15) of the fetuses with trisomy 13. This high frequency underlines the importance of echocardiography in diagnosing this aneuploidy. Among minor anomalies, increased nuchal translucency (21.4%) and echogenic bowel (17.9%) were the most common findings. CONCLUSIONS: Second-trimester sonographic examination is capable of showing anomalies that are characteristic of trisomy 13; thus, the scan can indicate whether fetal karyotyping is advisable. Incorporation of careful assessment of the fetal cardiovascular system by sonography certainly increases the detection rate of trisomy 13.     

Added value of gastrin receptor scintigraphy in comparison to somatostatin receptor scintigraphy in patients with carcinoids and other neuroendocrine tumours

Gastrin receptor scintigraphy (GRS) is a new imaging method primarily developed for the detection of metastases of medullary thyroid carcinoma (MTC). As gastrin-binding CCK(2) receptors are also expressed on a variety of other neuroendocrine tumours (NET), we compared GRS to somatostatin receptor scintigraphy (SRS) in patients with NET. SRS and GRS were performed within 21 days in a series of 60 consecutive patients with NET. GRS was directly compared with SRS. If lesions were visible on GRS but not detectable by SRS, other imaging modalities (MRI, CT) and follow-up were used for verification. Of the 60 evaluable patients, 51 had carcinoid tumours, 3 gastrinomas, 2 glucagonomas, 1 insulinoma and 3 paragangliomas. The overall tumour-detection rate was 73.7% for GRS and 82.1% for SRS. In the 11 patients with negative SRS, GRS was positive in 6 (54.5%). Based on the number of tumour sites detected and the degree of uptake, GRS performed better than SRS in 13 patients (21.7%), equivalent images were obtained in 18 cases (30.0%) and SRS performed better in 24 (40.0%) cases. In six of the SRS positive patients, 18 additional sites of tumour involvement could be detected. Overall, GRS detected additional tumour sites in 20% of the patients. Localisation of the primary tumours or their functional status had no influence on the outcome of imaging. GRS should be performed in selected patients as it may provide additional information in patients with NET with equivocal or absent somatostatin uptake.     

Role of vasodilators in regurgitant valve disease

Opinion statement Vasodilator therapy is designed to reduce regurgitant volume and improve left ventricular function. Acute administration reduces vascular resistance and decreases regurgitant volume and left ventricular filling pressure. These effects may be clinically useful in acute regurgitations, but less consistent results have been reported in long-term therapy. In chronic mitral functional regurgitation, vasodilator therapy has proved to have clinical or prognostic benefit only when heart failure or poor ventricular function is present. The indication of vasodilator treatment in aortic regurgitation has raised significant controversy. Several studies with small series have shown beneficial effects on regurgitant volume, ejection fraction, and mass of the left ventricle. Nevertheless, in the only two randomized long-term follow-up studies, results differed completely. In our experience, both nifedipine and enalapril failed to reduce the need for valvular surgery or show benefits in echocardiographic parameters. Vasodilator therapy would be indicated only in patients with severe aortic regurgitation and systemic hypertension, or when surgery is contraindicated.     

Value of parathyroid hormone assay for preoperative sonographically guided parathyroid aspirates for minimally invasive parathyroidectomy

PURPOSE: The key to successful parathyroid surgery is accurate preoperative tumor localization. This study investigates the use of ultrasound (US)-guided parathyroid fine needle aspiration (FNA) as a confirmatory diagnostic method in patients with hyperparathyroidism undergoing minimally invasive parathyroidectomy. METHODS: Patients were selected for minimally invasive parathyroidectomy based on the finding of a single parathyroid adenoma identified with US and/or sestamibi scans and confirmation of the suspected parathyroid lesion via FNA and parathyroid hormone (PTH) assay. The value of aspirate obtained from the thyroid gland intraoperatively served as the negative control. RESULTS: A total of 56 tissue FNAs were performed in 27 patients. US detected masses suggestive of parathyroid lesion in all 27 patients, and 31 US-guided FNAs were performed. No complications related to the procedure were noted. Intraoperatively, FNA was performed in the thyroids of 25 patients undergoing minimally invasive parathyroidectomy. Aspirates from lesions subsequently confirmed as having developed from the parathyroid gland had a mean PTH level of 4,677 +/- 123 pg/ml (range, 3,600-5,000 pg/ml), which was significantly higher than thyroid aspirates, which yielded a mean PTH level of 48 +/- 7 pg/ml (range, 5-57 pg/ml). The sensitivity of US and sestamibi scans in the detection of abnormal parathyroid glands was 88% and 77%, respectively. The sensitivity of US-guided FNA in confirming the parathyroid origin of a lesion was 100%. CONCLUSION: US-guided FNA for PTH assay can be performed safely for the confirmation of lesions identified with preoperative US for the selection of patients eligible for minimally invasive parathyroidectomy.     

Neurotoxicity of Ecstasy metabolites in rat cortical neurons, and influence of hyperthermia

3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") is a widely abused, psychoactive recreational drug. There is growing evidence that the MDMA neurotoxic profile may be highly dependent on both its hepatic metabolism and body temperature. Metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine (MDA), which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA) and alpha-methyldopamine (alpha-MeDA), respectively, both of which are catechols that can undergo oxidation to the corresponding ortho-quinones. In the presence of glutathione (GSH), ortho-quinones may be conjugated with GSH to form glutathionyl adducts. In this study, we evaluated the neurotoxicity of MDMA and three of its metabolites obtained by synthesis, N-Me-alpha-MeDA, alpha-MeDA, and 5-(GSH)-alpha-MeDA [5-(glutathion-S-yl)-alpha-methyldopamine] in rat cortical neuronal serum-free cultures under normal (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Cell viability was assessed, and the mechanism of cell death was also evaluated. Our study shows that these metabolites are more neurotoxic [5-(GSH)-alpha-MeDA being the most toxic] than the parent compound MDMA. The neurotoxicity of MDMA metabolites was partially prevented by the antioxidants N-acetylcystein and also, in a minor extent, by alpha-phenyl-N-tert-butyl nitrone. All the tested compounds induced apoptotic cell death in cortical neurons, and their neurotoxic effect was potentiated under hyperthermic conditions. These data suggest that MDMA metabolites, especially under hyperthermic conditions, contribute to MDMA-induced neurotoxicity.     

Efficient sensing of avian influenza viruses by porcine plasmacytoid dendritic cells

H5N1 influenza A virus (IAV) infections in human remain rare events but have been associated with severe disease and a higher mortality rate compared to infections with seasonal strains. An excessive release of pro-inflammatory cytokine together with a greater virus dissemination potential have been proposed to explain the high virulence observed in human and other mammalian and avian species. Among the cells involved in the cytokine storm, plasmacytoid dendritic cells (pDC) could play an important role considering their unique capacity to secrete massive amounts of type I interferon (IFN). Considering the role of IFN as a major component of antiviral responses as well as in priming inflammatory responses, we aimed to characterize the induction of IFN-α release upon infection with IAV originating from various avian and mammalian species in a comparative way. In our porcine pDC model, we showed that the viral components triggering IFN responses related to the ability to hemagglutinate, although virosomes devoid of viral RNA were non-stimulatory. Heat-treatment at 65 °C but not chemical inactivation destroyed the ability of IAV to stimulate pDC. All IAV tested induced IFN-α but at different levels and showed different dose-dependencies. H5 and H7 subtypes, in particular H5N1, stimulated pDC at lower doses when compared to mammalian IAV. At high viral doses, IFN-α levels reached by some mammalian IAV surpassed those induced by avian isolates. Although sialic acid-dependent entry was demonstrated, the α-2,3 or α-2,6 binding specificity alone did not explain the differences observed. Furthermore, we were unable to identify a clear role of the hemagglutinin, as the IFN-α doses-response profiles did not clearly differ when viruses with all genes of identical avian origin but different HA were compared. This was found with IAV bearing an HA derived from either a low, a high pathogenic H5N1, or a human H3. Stimulation of pDC was associated with pDC depletion within the cultures. Taken together and considering the efficient sensing of H5N1 at low dose, pDC on one side may play a role in the cytokine storm observed during severe disease, on the other hand could participate in early antiviral responses limiting virus replication.