Regulation of intraluteal production of prostaglandins

There is clear evidence for intraluteal production of prostaglandins (PGs) in numerous species and under a variety of experimental conditions. In general, secretion of PGs appears to be elevated in the early corpus luteum (CL) and during the period of luteolysis. Regulation of intraluteal PG production is regulated by a variety of factors. An autoamplification pathway in which PGF-2alpha stimulates intraluteal production of PGF-2alpha has been identified in a number of species. The mechanisms underlying this autoamplification pathway appear to differ by species with expression of Cyclooxygenase-2 (Cox-2) and activity of phospholipase A2 acting as important physiological control points. In addition, a number of other responses that are induced by PGF-2alpha (decreased luteal progesterone, increased endothelin-1, increased cytokines) also have been found to increase intraluteal PGF-2alpha production. Thus, regulation of intraluteal PG production may serve to initiate or amplify physiological signals to the CL and may be important in specific aspects of luteal physiology particularly during luteal regression

Uptake and depletion of plasma 17α-methyltestosterone during induction of masculinization in muskellunge, Esox masquinongy: Effect on plasma steroids and sex reversal

Oral administration of 17α-methyltestosterone (MT) was used to induce masculinization of sexually undifferentiated muskellunge, Esox masquinongy. Three groups of muskellunge (mean weight, 2.5 ± 0.6 g) were submitted to MT treatment (15 mg of MT/kg) for 60 days. An additional one group was used as a control (hormone-free diet). Food was distributed over a 10-h period by using automatic belt feeders. Blood was sampled in both control and treated fish at different intervals during and after feeding: before (0 h), at 3 h, 6 h, and cessation of feeding (10 h), and after a fast of 22 h (32 h). MT had no significant effect on growth and survival in muskellunge 6 months after the treatment. Concentrations of plasma MT increased during the feeding period and reached their maximum levels 6 or 10 h after starting feeding. This rapid increase of MT indicated a rapid absorption of this steroid. Plasma MT levels then declined and reached a radir by 22 h after cessation of feeding, suggesting that MT is rapidly metabolized and excreted. The profiles of plasma testosterone during the MT treatment did not differ significantly between control and MT-treated groups. During and after the MT treatment, the concentration of plasma testosterone did not differ significantly between control and MT-treated groups. Moreover, no sexual dimorphism of testosterone levels was observed. Six months after treatment, the sex ratio in MT-treated groups (33% males, 62% females, and 5% intersex) was opposite to control (70% and 30%, respectively) and differed significantly. This suggests that at 15 mg of MT/kg over 60 days, a paradoxical feminization took place.Salaries were partly provided by State and Federal Funds awarded to the Ohio Agriculture Research and Development Center, Wooster, OH, USA

Advanced glycation end product cross-link breaker attenuates diabetes-induced cardiac dysfunction by improving sarcoplasmic reticulum calcium handling

Diabetic heart disease is a distinct clinical entity that can progress to heart failure and sudden death. However, the mechanisms responsible for the alterations in excitation-contraction coupling leading to cardiac dysfunction during diabetes are not well known. Hyperglycemia, the landmark of diabetes, leads to the formation of advanced glycation end products (AGEs) on long-lived proteins, including sarcoplasmic reticulum (SR) Ca2+ regulatory proteins. However, their pathogenic role on SR Ca2+ handling in cardiac myocytes is unknown. Therefore, we investigated whether an AGE cross-link breaker could prevent the alterations in SR Ca2+ cycling that lead to in vivo cardiac dysfunction during diabetes. Streptozotocin-induced diabetic rats were treated with alagebrium chloride (ALT-711) for 8 weeks and compared to age-matched placebo-treated diabetic rats and healthy rats. Cardiac function was assessed by echocardiographic examination. Ventricular myocytes were isolated to assess SR Ca2+ cycling by confocal imaging and quantitative Western blots. Diabetes resulted in in vivo cardiac dysfunction and ALT-711 therapy partially alleviated diastolic dysfunction by decreasing isovolumetric relaxation time and myocardial performance index (MPI) (by 27 and 41% vs. untreated diabetic rats, respectively, P < 0.05). In cardiac myocytes, diabetes-induced prolongation of cytosolic Ca2+ transient clearance by 43% and decreased SR Ca2+ load by 25% (P < 0.05); these parameters were partially improved after ALT-711 therapy. SERCA2a and RyR2 protein expression was significantly decreased in the myocardium of untreated diabetic rats (by 64 and 36% vs. controls, respectively, P < 0.05), but preserved in the treated diabetic group compared to controls. Collectively, our results suggest that, in a model of type 1 diabetes, AGE accumulation primarily impairs SR Ca2+ reuptake in cardiac myocytes and that long-term treatment with an AGE cross-link breaker partially normalized SR Ca2+ handling and improved diabetic cardiomyopathy.Peer reviewedPhysiological Science

Primo Levi : testimone e scrittore di storia /

"Il volume raccoglie gli atti del convegno 'Giornate di studio in ricordo di Primo Levi,' svoltosi a Saint-Vincent (Aosta) il 15-16 ottobre 1997"--P. opp t.p.At head of title: Istituto storico della Resistenza in Valle d'Aosta; Fondazione centro studi storico-letterari Natalino Sapegno; Biblioteca comunale di Saint-Vincent; Regione autonoma Valle d'Aosta; Comune di Saint-Vincent.Includes bibliographical references