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

Information of ocular origin impairs target discrimination during visual search

Session 9: Poster: Attention & Awareness, Visual search, Clinical population, Computer visionVisual features such as colour, orientation, luminance, eye-of-origin information are reported to modulate attentional deployment and thus visual search. Among them, the effect of ocular origin of information on visual search performance is less clear: Zhaoping (2008, 2012) found that an ocular singleton improves visual search performance when it was the target, while we (Yeung et al, 2014) found consistent search ...postprin

The development, fabrication, and material characterization of polypropylene composites reinforced with carbon nanofiber and hydroxyapatite nanorod hybrid fillers

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Polypropylene biocomposites with boron nitride and nanohydroxyapatite reinforcements

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A novel bio-degradable polymer membrane to control the degradation of Mg-based metallic biomaterial for orthopaedic implantation

Oral Paper Session - Research: Biomaterials VI: abstract no. 31794Biodegradable metallic materials such as magnesium-based alloys are the potential candidates of replacing the currently used non-degradable metallic implants. However, the fast degradation rate and hydrogen gas release may hinder its use. To remedy these complications, our group has developed a controllable biodegradable polymer coating, polycaprolactone (PCL), onto magnesium alloy surface. This study aims to investigate the surface mechanics, in-vitro and in-vivo properties of the modified magnesium …postprin

MicroRNA-21 promotes survival but not functional maturation of human embryonic stem cell-derived cardiomyocytes (hESC-CMs)

published_or_final_versionThe 16th Medical Resarch Conference (MRC), The University of Hong Kong, Hong Kong, China, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 35, abstract no. 5

MiR-29b negatively regulates cell cycle activity of human embryonic stem cell-derived cardiomyocytes

published_or_final_versionThe 16th Medical Resarch Conference (MRC), The University of Hong Kong, Hong Kong, China, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 50, abstract no. 7

Engineered magnesium-based resorbable porous scaffold for bone tissue engineering

INTRODUCTION: Bone tissue engineering offers an alternative solution to the traditional methods of bone replacement including allografts and autografts [1]. Although these biological materials possess good osteoinductive and osteoconductive properties, both of them have limitations in terms of the availability, donor site morbidity and the risk of disease transmission with the use of allografts [2]. Therefore, the use of synthetic scaffold is the most common technique and good approach to regenerate diseased or damaged bone tissue. An ideal bone substitute should possess certain properties including ...postprin

Melatonin attenuates pulmonary hypertension in chronically hypoxic rats

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Low modulus novel bone substitutes for osteoporotic vertebral fracture management

Oral presentationpublished_or_final_versioneCM XIII - Bone Fixation, Repair & Regeneration, Davos Platz, Switzerland, 24-26 June 2012. In European Cells & Materials, 2012, v. 24 n. Suppl. 1, p. 1