981 research outputs found
Melatonin ameliorates calcium homeostasis in myocardial and ischemia-reperfusion injury in chronically hypoxic rats
Chronic hypoxia (CH) leads to the deterioration of myocardial functions with impaired calcium handling in the sarcoplasmic reticulum (SR), which may be mediated by oxidative stress. We hypothesized that administration of antioxidant melatonin would protect against cardiac and ischemia-reperfusion (I/R) injury by ameliorating SR calcium handling. Adult Sprague-Dawley rats that had received a daily injection of melatonin or vehicle were exposed to 10% oxygen for 4 wk. The heart of each rat was then dissected and perfused using a Langendorff apparatus. The ratio of heart-to-body weight, ventricular hypertrophy and hematocrit were increased in the hypoxic rats compared with the normoxic controls. Malondialdehyde levels were also increased in the heart of hypoxic rats and were lowered by the treatment of melatonin. The hearts were subjected to left coronary artery ischemia (30 min) followed by 120-min reperfusion. Lactate dehydrogenase leakage before ischemia, during I/R and infarct size of the isolated perfused hearts were significantly elevated in the vehicle-treated hypoxic rats but not in the melatonin-treated rats. Spectroflurometric studies showed that resting calcium levels and I/R-induced calcium overload in the cardiomyocytes were more significantly altered in the hypoxic rats than the normoxic controls. Also, the hypoxic group had decreased levels of the SR calcium content and reduced amplitude and decay time of electrically induced calcium transients, indicating impaired contractility and SR calcium re-uptake. Moreover, there were reductions in protein expression of calcium handling proteins, markedly shown at the level of SR-Ca2+ ATPase (SERCA) in the heart of hypoxic rats. Melatonin treatment significantly mitigated the calcium handling in the hypoxic rats by preserving SERCA expression. The results suggest that melatonin is cardioprotective against CH-induced myocardial injury by improving calcium handling in the SR of cardiomyocytes via an antioxidant mechanism. © 2008 The Authors.postprin
Melatonin attenuates pulmonary hypertension in chronically hypoxic rats
published_or_final_versio
The first genome sequences of human bocaviruses from Vietnam.
As part of an ongoing effort to generate complete genome sequences of hand, foot and mouth disease-causing enteroviruses directly from clinical specimens, two complete coding sequences and two partial genomic sequences of human bocavirus 1 (n=3) and 2 (n=1) were co-amplified and sequenced, representing the first genome sequences of human bocaviruses from Vietnam. The sequences may aid future study aiming at understanding the evolution of the pathogen
Differential Effects of Concomitant Use of Vitamins C and E on Trophoblast Apoptosis and Autophagy between Normoxia and Hypoxia-Reoxygenation
Concomitant supplementation of vitamins C and E during pregnancy has been reportedly associated with low birth weight, the premature rupture of membranes and fetal loss or perinatal death in women at risk for preeclampsia; however, the cause is unknown. We surmise that hypoxia-reoxygenation (HR) within the intervillous space due to abnormal placentation is the mechanism and hypothesize that concomitant administration of aforementioned vitamin antioxidants detrimentally affects trophoblast cells during HR.Using villous explants, concomitant administration of 50 microM of vitamins C and E was observed to reduce apoptotic and autophagic changes in the trophoblast layer at normoxia (8% oxygen) but to cause more prominent apoptosis and autophagy during HR. Furthermore, increased levels of Bcl-2 and Bcl-xL in association with a decrease in the autophagy-related protein LC3-II were noted in cytotrophoblastic cells treated with vitamins C and E under standard culture conditions. In contrast, vitamin treatment decreased Bcl-2 and Bcl-xL as well as increased mitochondrial Bak and cytosolic LC3-II in cytotrophoblasts subjected to HR.Our results indicate that concomitant administration of vitamins C and E has differential effects on the changes of apoptosis, autophagy and the expression of Bcl-2 family of proteins in the trophoblasts between normoxia and HR. These changes may probably lead to the impairment of placental function and suboptimal growth of the fetus
Inhibition of the Nicotinic Acetylcholine Receptors by Cobra Venom α-Neurotoxins: Is There a Perspective in Lung Cancer Treatment?
Nicotine exerts its oncogenic effects through the binding to nicotinic acetylcholine receptors (nAChRs) and the activation of downstream pathways that block apoptosis and promote neo-angiogenesis. The nAChRs of the α7 subtype are present on a wide variety of cancer cells and their inhibition by cobra venom neurotoxins has been proposed in several articles and reviews as a potential innovative lung cancer therapy. However, since part of the published results was recently retracted, we believe that the antitumoral activity of cobra venom neurotoxins needs to be independently re-evaluated
Serum estradiol/progesterone ratio on day of embryo transfer may predict reproductive outcome following controlled ovarian hyperstimulation and in vitro fertilization
BACKGROUND: To determine whether estradiol-to-progesterone (E(2)/P) ratios at the time of embryo transfer (ET) have an effect on implantation and pregnancy in IVF cycles. METHODS: 239 women consecutively treated by IVF or ICSI were retrospectively analyzed and early luteal serum E(2 )and P were measured on the day of ET. Transfer occurred after a variable in vitro culture period ranging from 4–7 days after ovulation induction (OI). Following ET, serum E(2)/P ratios were calculated for clinical pregnancies, preclinical abortions and non-coneption cycles. RESULTS: Receiver-operator curve analysis demonstrated that the E(2)/P ratio could differentiate between clinical pregnancies and non-pregnant cycles (area under the curve on OI +4 days = 0.70; 95% CI = 0.60–0.80; p = 0.003, on OI +5 days = 0.76; 95% CI = 0.64–0.88; p = 0.001, OI +7 days = 0.85; 95% CI = 0.75–0.96; p < 0.0001). CONCLUSION: These retrospective data may hold prognostic value regarding endometrial receptivity as reflected by E(2)/P measurements and may help improve IVF treatment outcome. Further prospective studies should be undertaken to confirm these obersveration
Particular solutions of a certain class of associated Cauchy-Euler fractional partial differential equations via fractional calculus
- …