It is well known that neuronal damage following a stroke has been attributed to the over stimulation of excitatory amino acids such as glutamate and aspartate through activation of NMDA receptors. The brain is exposed to most of the constituents of plasma including homocysteine as a result of the disruption of the blood–brain barrier after stroke, head trauma and stress. The question, therefore, arises as to whether or not homocysteine is able to selectively stimulate the release of excitatory amino acids in stroke. This review article will address the importance of homocysteine in nervous system specifically how these amino acids may trigger the release of catecholamines. Our data will thus strengthen the view that a mechanism for the association of hyperhomocysteinemia with increased brain lesion in stroke. As hypothalamus also controls the cardiac function via sympathetic system, the contractility of heart will be compromised. Homocysteine is also known to mediate cardiovascular problems by its adverse effects on cardiovascular endothelium and smooth muscle cells with resultant alterations in subclinical arterial structure and function. The present review will thus summarize both central and peripheral effects of homocysteine and will highlight some of the controversies associated with hyperhomocysteinemia-induced cardiovascular problems.
The effects of insulin and thyroid hormone treatments on cardiac sarcoplasmic reticular function were investigated in chronic streptozotocin-induced diabetes in rats. ATP-dependent Ca2+ transport and Ca2+-stimulated ATPase activities were depressed significantly in microsomal samples from diabetic rats in comparison with control (P less than 0.05). This defect was seen at various times of incubation (1-20 min) and different concentrations of free Ca2+ (10(-7) to 10(-5) M Ca2+) and was accompanied by changes in the protein composition and phospholipid contents of the microsomal fraction. The defect in calcium transport in microsomal vesicles was not evident until 28 days after streptozotocin (65 mg/kg iv) injection, whereas increases in plasma glucose levels due to insulin-deficiency occurred within 3 days. All changes in function and composition of the sarcoplasmic reticulum were reversed by insulin administration to the diabetic rats. Although the plasma level of thyroid hormone was decreased in the diabetic rat, thyroid hormone treatment did not restore microsomal calcium transport in the diabetic animals. The results of this study provide some evidence that the depression in cardiac sarcoplasmic reticular calcium accumulation during diabetes is a consequence of insulin deficiency and associated chronic metabolic changes but the hypothyroid condition that accompanies experimental diabetes does not appear to play any role in this defect.
Assessing teaching-learning outcomes in anatomical knowledge is a complex task that requires the evaluation of multiple domains: theoretical, practical, and clinical knowledge. In general, theoretical knowledge is tested by a written examination system constituted by multiple choice questions (MCQs) and/or short answer questions (SAQ). The assessment of practical knowledge (three-dimensional anatomical concepts) involves oral, spot, or objective structured practical examinations (OSPE). Finally, the application of anatomical knowledge to patients is tested mainly through objective structured clinical examinations (OSCE). The major focus of this study is the OSPE. Although many schools challenge students using this tool in practical examinations in the early phase of the curriculum, the true meaning of OSPE is frequently forgotten and it becomes, in reality, a spot examination. This article, for the first time, describes how the concept of the OSPE has evolved and is currently being used to assess the practical domain of anatomical knowledge in a problem-based curriculum at Alfaisal University College of Medicine. In addition, it describes the main differences from the spot examination, which is normally used in traditional medical curricula. The authors believe that the OSPE remains the most efficient tool to assess the practical aspects of anatomical knowledge in a system where basic knowledge is integrated with the clinical or functional part of anatomy. However, this contention only holds true if the OSPE process revolves around structured objectives.
Today we are beginning to understand how phytochemicals can influence metabolism, cellular signaling and gene expression. The hydroxybenzoic acids are related to salicylic acid and salicin, the first compounds isolated that have a pharmacological activity. In this review we examine how a number of hydroxyphenolics have the potential to ameliorate cardiovascular problems related to aging such as hypertension, atherosclerosis and dyslipidemia. The compounds focused upon include 2,3-dihydroxybenzoic acid (Pyrocatechuic acid), 2,5-dihydroxybenzoic acid (Gentisic acid), 3,4-dihydroxybenzoic acid (Protocatechuic acid), 3,5-dihydroxybenzoic acid (α-Resorcylic acid) and 3-monohydroxybenzoic acid. The latter two compounds activate the hydroxycarboxylic acid receptors with a consequence there is a reduction in adipocyte lipolysis with potential improvements of blood lipid profiles. Several of the other compounds can activate the Nrf2 signaling pathway that increases the expression of antioxidant enzymes, thereby decreasing oxidative stress and associated problems such as endothelial dysfunction that leads to hypertension as well as decreasing generalized inflammation that can lead to problems such as atherosclerosis. It has been known for many years that increased consumption of fruits and vegetables promotes health. We are beginning to understand how specific phytochemicals are responsible for such therapeutic effects. Hippocrates’ dictum of ‘Let food be your medicine and medicine your food’ can now be experimentally tested and the results of such experiments will enhance the ability of nutritionists to devise specific health-promoting diets.
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