Adaptations to Chronic Hypoxia Combined with Erythropoietin Deficiency in Cerebral and Cardiac Tissues

Chronic anemia-induced hypoxia triggers regulatory pathways that mediate long-term adaptive cardiac and cerebral changes, particularly at the transcriptional level. These adaptative mechanisms include a regulated cerebral blood flow and cardiac output, angiogenesis and cytoprotection triggered by hypoxia-inducible factor 1 alpha (HIF-1α), vascular endothelial growth factor (VEGF), neuronal nitric oxide synthase (nNOS) and Epo pathways. All these compensatory mechanisms aim to optimize oxygen delivery and to protect the brain and heart from hypoxic injury. We reviewed the effects of chronic hypobaric hypoxia as well as chronic anemia in the heart and brain, and we compared for the first time the effects of chronic hypobaric hypoxia combined with a severe lack of Epo (chronic anemia) in these vital organs. Functional cardiac adaptations such as cardiac hypertrophy, increased cardiac output as well as angiogenesis occurred along with the activation of HIF1α/VEGF and Epo/EpoR pathways under chronic anemia or hypoxia. Similarly, cerebrovascular adaptations take place through the same molecular mechanisms under chronic hypoxia or anemia. However, when both arterial pressure and content of oxygen are decreased, the cerebral and cardiac adaptative mechanisms showed their limitations. In addition, cerebral and cardiac cell injuries may have occurred following the combined effect of chronic anemia and hypoxia. By emphasizing the anemia and hypoxia-induced cerebral and myocardial adaptations, this review highlighted the crucial role of Epo in its non-erythropoietic functions such as angiogenesis and neuroprotection. Indeed, a better understanding of these protective mechanisms is of great clinical importance to the development of new therapeutic strategies for the management of ischemic heart and brain

Expression of recombinant Streptokinase from local Egyptian Streptococcus sp. SalMarEg

Streptokinase (SK) is a therapeutically important thrombolytic agent. Cardiovascular disease is the first cause of adult death worldwide. In Egypt about 13% of the population die every year due to ischemic heart disease. In spite of this fact, there is no local production of cardiovascular therapeutics. We reported for the first time the expression of a recombinant SK from a local Streptococcus strain. When produced on industrial scale this r-SK may substantially contribute to reducing the costs of thrombolytic therapy in developing countries. In this study, a highly purified r-SK from Streptococcus sp. isolated from Egyptian pharyngitis patients was obtained. The isolated strain was partially identified using 16S rDNA sequencing and named Streptococcus sp. SalMarEg. It was found to be phylogenetically related to Streptococcus pyogenes. Analysis of the obtained sequence showed high similarity with other SK genes. The protein expression in a prokaryotic system obtained a 47-kDa SK protein that could be purified using a single-step his-tagged affinity purification chromatography, with nearly 80% recovery. The clot lytic activities of both recombinant and commercial SK were similar, thus giving the basis to scale up this SK product in order to evaluate the possibilities of its commercialization in local and/or regional markets.Key words: Streptokinase, Streptococcus SalMarEg, thrombolytic agent, heterologous expression

Epo Is Relevant Neither for Microvascular Formation Nor for the New Formation and Maintenance of Mice Skeletal Muscle Fibres in Both Normoxia and Hypoxia

Erythropoietin (Epo) and vascular growth factor (VEGF) are known to be involved in the regulation of cellular activity when oxygen transport is reduced as in anaemia or hypoxic conditions. Because it has been suggested that Epo could play a role in skeletal muscle development, regeneration, and angiogenesis, we aimed to assess Epo deficiency in both normoxia and hypoxia by using an Epo-deficient transgenic mouse model (Epo-TAgh). Histoimmunology, ELISA and real time RT-PCR did not show any muscle fiber atrophy or accumulation of active HIF-1α but an improvement of microvessel network and an upregulation of VEGFR2 mRNA in Epo-deficient gastrocnemius compared with Wild-Type one. In hypoxia, both models exhibit an upregulation of VEGF120 and VEGFR2 mRNA but no accumulation of Epo protein. EpoR mRNA is not up-regulated in both Epo-deficient and hypoxic gastrocnemius. These results suggest that muscle deconditioning observed in patients suffering from renal failure is not due to Epo deficiency

Partial Purification and Characterization of Two Endo-ȕ-1, 4-glucanase from Trichoderma sp. (Shmosa tri)

Abstract: Two endoglucanases (EC 3.2.1.4) from Trichoderma sp. (shmosaTri) FJ937359 were purified to homogeneity using ammonium sulfate precipitation and gel filtration. Purity was confirmed by SDS/PAGE. Enzymatic properties and molecular weights were determined. Molecular weights of CMCase I and II were 58 and 34 KDa, respectively. The effect of temperature on the 2 endoglucanase activity was studied and results showed that optimum activity obtained at 50°C for both CMCase I and II. The enzymes withstand 60 min at 50ºC without loss of enzymatic activity. CMCase I and II retained 14.0 and 26.5 % of their original activities at 70°C after 90 min. The optimum pH for CMCase I and II was 5.0. Results also show that CMCase I was active at room temperature after 24 hrs over a broad pH range (3.0-9.0) while CMCase II was relatively stable in pH range (4.0-6.0). Among different kinds of substrates, both enzymes showed a high preference for carboxymethyl cellulose while both CMCase I and II did not show any hydrolytic activity against chitin, starch and cellobiose. On the other hand both CMCase I and II have relatively low hydrolytic activity towards ȕ glucan and xylan. All metallic ions used as well as EDTA and SDS at a concentration of 20 ug/ml of reaction mixture have an inhibitory effect on both CMCase I and II

A simple method to assess the oxidative susceptibility of low density lipoproteins

BACKGROUND: Oxidative modification of low density lipoproteins (LDL) is recognized as one of the major processes involved in atherogenesis. The in vitro standardized measurement of LDL oxidative susceptibility could thus be of clinical significance. The aim of the present study was to establish a method which would allow the evaluation of oxidative susceptibility of LDL in the general clinical laboratory. RESULTS: LDL was isolated from human plasma by selective precipitation with amphipathic polymers. The ability of LDL to form peroxides was assessed by measuring thiobarbituric acid reactive substances (TBARS) after incubation with Cu(2+) and H(2)O(2). Reaction kinetics showed a three-phase pattern (latency, propagation and decomposition phases) which allowed us to select 150 min as the time point to stop the incubation by cooling and EDTA addition. The mixture Cu(2+)/H(2)O(2) yielded more lipoperoxides than each one on its own at the same time end-point. Induced peroxidation was measured in normal subjects and in type 2 diabetic patients. In the control group, results were 21.7 ± 1.5 nmol MDA/mg LDL protein, while in the diabetic group results were significantly increased (39.0 ± 3.0 nmol MDA/mg LDL protein; p < 0.001). CONCLUSION: a simple and useful method is presented for the routine determination of LDL susceptibility to peroxidation in a clinical laboratory

Field manual for the preparation of a participatory community development plan

Arabic version available in IDRC Digital Librar

What is known about Ventricular Septal Defect in University Female Students of Saudi Arabia?

This study was performed to estimate the knowledge and awareness of the university students about the presence of ventricular septal defects (VSDs) in Saudi Arabia. A cross-sectional study was performed in Princess Nourah bint Abdulrahman University (PNU) campus where a total of 350 female students in the age group of 17-25 years were surveyed using a clinically appropriate structurally designed questionnaire. Only a third of the population were familiar with the definition and anatomical location of VSDs. Although, majority of the population believed that VSDs are subject to cure, a negligible population of the students were aware that VSDs are associated with pulmonary hypertension in adults, although, about half of the population were associated with people who were suffering from VSDs. Even though promising, only half of the population were aware of rapid breathing in infants and association of endocarditis with VSDs. Regarding life-style factors, only 18% of the population knew that VSD patients are restrained from different physical activities. This population study is the first of its kind to determine the knowledge of the university students regarding the characteristics, symptoms, risk-factors, management and life-style factors associated with VSD. It identified the imperative need to organize campaigns to raise awareness about the disease process and management among female population who will be future mothers since Awareness about VSDs can help manage the physical, social, cognitive and emotional well-being of the patients with better outcomes to reduce the mortality rate.

Irritable Bowel Syndrome Among Female Students in Princess Nourah University in Kingdom of Saudi Arabia

In this study, our objective was to explore the knowledge of Irritable Bowel syndrome (IBS) among university female students in the Kingdom of Saudi Arabia (KSA). A cross-sectional study was conducted where 307 university students were surveyed using a self-administered questionnaire to assess their awareness. The questionnaire was based on the socio-demographic and life-style characteristics of the students to evaluate the prevalence of IBS in the community.  About 60% of the population in the age group of 18-20 years are at a high risk of suffering from IBS. However, no significant difference is demonstrated between lifestyle habits such as consumption of fast and spicy foods and physical activities and onset of IBS among the students. Nevertheless, frequent episodes of exercise in a week may reduce the probability of IBS onset. Interestingly, almost half of the student population mentioned that they were taking antibiotics and their sleep was interrupted as they woke up in the middle of the night.  Also, majority of the population indicated that their stool texture was different, either hard or loose associated with a pain and distended abdomen followed with gastritis. Abdominal discomfort, feeling of bloating, altered texture of stool and urgency to defecate could be due to the development of psychological stress associated with academics, which possibly intensifies the disease symptoms. Initial findings from our study justifies the need of future longitudinal surveys to validate the existence of psychological stressors and other risk factors in the development of IBS subtypes

Antioxidants inhibit low density lipoprotein oxidation less at lysosomal pH: a possible explanation as to why the clinical trials of antioxidants might have failed

Oxidised low density lipoprotein (LDL) was considered to be important in the pathogenesis of atherosclerosis, but the large clinical trials of antioxidants, including the first one using probucol (the PQRST Trial), failed to show benefit and have cast doubt on the importance of oxidised LDL. We have shown previously that LDL oxidation can be catalysed by iron in the lysosomes of macrophages. The aim of this study was therefore to investigate the effectiveness of antioxidants in preventing LDL oxidation at lysosomal pH and also establish the possible mechanism of oxidation. Probucol did not effectively inhibit the oxidation of LDL at lysosomal pH, as measured by conjugated dienes or oxidised cholesteryl esters or tryptophan residues in isolated LDL or by ceroid formation in the lysosomes of macrophage-like cells, in marked contrast to its highly effective inhibition of LDL oxidation at pH 7.4. LDL oxidation at lysosomal pH was inhibited very effectively for long periods by N,N'-diphenyl-1,4-phenylenediamine, which is more hydrophobic than probucol and has been shown by others to inhibit atherosclerosis in rabbits, and by cysteamine, which is a hydrophilic antioxidant that accumulates in lysosomes. Iron-induced LDL oxidation might be due to the formation of the superoxide radical, which protonates at lysosomal pH to form the much more reactive, hydrophobic hydroperoxyl radical, which can enter LDL and reach its core. Probucol resides mainly in the surface monolayer of LDL and would not effectively scavenge hydroperoxyl radicals in the core of LDL. This might explain why probucol failed to protect against atherosclerosis in various clinical trials. The oxidised LDL hypothesis of atherosclerosis now needs to be re-evaluated using different and more effective antioxidants that protect against the lysosomal oxidation of LDL