Antagonist of growth hormone-releasing hormone induces apoptosis in LNCaP human prostate cancer cells through a Ca2+-dependent pathway

Antagonists of growth hormone-releasing hormone (GHRH) exert antiproliferative effects directly on cancer cells, which are mediated by the tumoral GHRH receptors. However, the signal transduction pathways involved in antiproliferative effect of GHRH antagonists have not yet been elucidated. We used flow cytometry to investigate whether GHRH antagonist JV-1-38 can induce changes in the cytosolic free Ca2+ concentration leading to apoptosis in LNCaP human prostate cancer cells. JV-1-38 evoked prompt Ca2+ signal in a dose-dependent way (1-10 microM) and induced early stage of apoptosis in LNCaP human prostate cancer cells at a concentration effective in suppression of cell proliferation (10 microM) peaking after 3 h. Unexpectedly, agonist GHRH(1-29)NH2, which elevates cytosolic free Ca2+ concentration in pituitary somatotrophs at nanomolar concentrations, failed to induce Ca2+ signal or apoptosis even at a 10-fold higher concentration (100 microM). However, agonist GHRH(1-29)NH2 inhibited JV-1-38-induced Ca2+ signals in a dose-dependent way without affecting the antagonist-induced apoptosis. Peptides unrelated to GHRH did not induce Ca2+ signals in LNCaP human prostate cancer cells. EDTA (10 mM) or nifedipine (10 microM) significantly reduced the Ca2+ signal and early stage of apoptosis induced by JV-1-38, supporting the view that the increase in intracellular Ca2+ in response to JV-1-38 occurs primarily through extracellular Ca2+ entry through voltage-operated Ca2+ channels. In conclusion, GHRH antagonists activate tumoral GHRH receptors and are able to induce apoptosis in LNCaP human prostate cancer cells through a Ca2+-dependent pathway. Treatment with GHRH antagonists may offer a new approach to the therapy of prostate and other hormone-sensitive cancers.     

Serum leptin, soluble leptin receptor, free leptin index and bone mineral density in patients with primary biliary cirrhosis

BACKGROUND/AIM: The pathophysiology of osteoporosis in chronic liver diseases is unknown. Recent data suggest that serum leptin is associated with bone mineral density (BMD). In animal studies leptin was found to be a potent inhibitor of bone formation. We investigated the relationship between serum leptin levels, soluble leptin receptor (sOB-R), free leptin index (FLI) and BMD in patients with primary biliary cirrhosis (PBC). PATIENTS AND METHODS: Ninety-four female patients with PBC were included in this study; 122 healthy women served as controls. Serum leptin levels were measured by radioimmunoassay, sOB-R by enzyme-linked immunosorbent assay. BMD was measured by dual energy X-ray absorptiometry in the lumbar spine and femoral neck. RESULTS: Serum leptin was significantly lower in patients with PBC compared with healthy controls. No difference was found between the body mass index (BMI) of patients and controls. There was a strong positive correlation between leptin and BMI. In PBC no association was found between leptin, sOB-R and liver function tests, histological stages or the presence of osteoporosis. Osteoporosis was present in 38 patients. A positive correlation was found between serum leptin and femoral neck z-score even after adjustment for BMI, whereas serum sOB-R correlated inversely with the serum leptin level. There was no difference in FLI between the subgroups of PBC patients according to the stages of the disease. CONCLUSIONS: We found a lower serum leptin level and a higher sOB-R in patients with PBC, which could not be explained by the difference in BMI. As leptin was associated with BMD, it may be hypothesized that leptin is involved in the complex regulation of bone metabolism in PBC.     

Ultrastructural features of the spermatozoon and its differentiation in Brandesia turgida (Brandes, 1888) (Digenea,Microphalloidea, Pleurogenidae)

Spermatological characters of the digenean Brandesia turgida (Brandes, 1888), an intestinal parasite of the frog Pelophylax ridibundus (Pallas, 1771), have been investigated by means of transmission electron microscopy for the first time. The process of the spermatozoon formation begins with the appearance of the differentiation zone bordered by cortical microtubules and containing two centrioles associated with striated rootlets and with an intercentriolar body. The intercentriolar body is made up of seven distinct electron-dense plates, two less electron-dense, and four electron-lucent zones. The orthogonal development of the two flagella is followed by a flagellar rotation and their proximodistal fusion with the median cytoplasmic process. This process is accompanied by an extension of both the mitochondrion and nucleus into the median cytoplasmic process. The mature spermatozoon of B. turgida contains two parallel axonemes of unequal lengths with the 9?+?“1” trepaxonematan pattern, mitochondrion, nucleus, parallel cortical microtubules, four electron-dense attachment zones, an external ornamentation of the plasma membrane, and electron-dense glycogen granules. The anterior extremity of the male gamete contains one complete centriole, a small component of the central element of the second centriole, and peripheral cortical microtubules (up to 45). The posterior extremity of the mature spematozoon exhibits tubular elements of the disorganized axoneme. The present study provides the first data on spermiogenesis within the family Pleurogenidae. Variations of the spermatozoa ultrastructural characters within Digenea, in particular, between different families of the superfamily Microphalloidea, are discussed.     

Effects of experimental diabetes on endothelin-induced ventricular arrhythmias in dogs

Endothelin-1 (ET-1) is known to have a direct arrhythmogenic effect in the mammalian heart. Diabetes mellitus is accompanied by a series of endothelial and cardiac disfunctions; however, little is known about ET-1-induced direct arrhythmias in diabetes mellitus. Therefore, we infused ET-1 (33 pmol/min) into the left anterior descending coronary artery of 28 mongrel dogs, and measured basic hemodynamic parameters, coronary flow and an electrocardiogram. Diabetes mellitus was induced by alloxan (Group 4) and experiments were carried out 8 weeks later. Metabolically healthy dogs served as controls (Group 2). In a further control group, local hyperglycemia was induced by intracoronary glucose infusion (Group 3). ET-1 infusion induced prolongation of the QT-time and frequency-adjusted QT-time in all groups. Other electrophysiological parameters were comparable between the groups. This was followed by the occurence of ventricular premature beats, coupled extra-beats and later sustained ventricular tachycardia. Most of the experiments were terminated by ventricular fibrillation. The onset of arrhythmias was shorter in diabetic dogs as compared with control and locally hyperglycemic animals (18 +/- 8 minutes versus 24 +/- 8 minutes and 30 +/- 28 minutes, P < 0.05). However, there was no difference in the number of ventricular fibrillations, and the total elapsed time until the termination of the experiments. Therefore, the diabetic heart seems to be more prone to ET-1-induced arrhythmias and this is probably not a result of locally high glucose concentrations.     

Developing attributes for discrete choice experiments in health: a systematic literature review and case study of alcohol misuse interventions

Discrete choice experiments (DCEs) become increasingly popular to value outcomes for health economic studies and gradually gain acceptance as an input into policy decisions. Developing attributes is a key aspect for the design of DCEs, as their results may misguide decision-makers if they are based on an inappropriate set of attributes. However, the area lacks guidance, and current health-related DCE studies vary considerably in their methods of attribute development, with the consequent danger of providing an unreliable input for policy decisions. The aim of this article is to inform the progress toward a more systematic approach to attribute development for DCE studies in health. A systematic review of the published health-related DCE literature was conducted to lay the foundations for a generic framework which was tested in a case study of alcohol misuse interventions. Four stages of a general attribute development process emerged: (i) raw data collection; (ii) data reduction; (iii) removing inappropriate attributes; and (iv) wording. The case study compared and contrasted a qualitative and mixed-methods approach for the development of attributes for DCEs in the area of alcohol misuse interventions. This article provides a reference point for the design of future DCE experiments in health.