Bram Ramjiawan

Potent Antihypertensive Action of Dietary Flaxseed in Hypertensive Patients

Flaxseed contains &ohgr;-3 fatty acids, lignans, and fiber that together may provide benefits to patients with cardiovascular disease. Animal work identified that patients with peripheral artery disease may particularly benefit from dietary supplementation with flaxseed. Hypertension is commonly associated with peripheral artery disease. The purpose of the study was to examine the effects of daily ingestion of flaxseed on systolic (SBP) and diastolic blood pressure (DBP) in peripheral artery disease patients. In this prospective, double-blinded, placebo-controlled, randomized trial, patients (110 in total) ingested a variety of foods that contained 30 g of milled flaxseed or placebo each day over 6 months. Plasma levels of the &ohgr;-3 fatty acid &agr;-linolenic acid and enterolignans increased 2- to 50-fold in the flaxseed-fed group but did not increase significantly in the placebo group. Patient body weights were not significantly different between the 2 groups at any time. SBP was ≈10 mm Hg lower, and DBP was ≈7 mm Hg lower in the flaxseed group compared with placebo after 6 months. Patients who entered the trial with a SBP ≥140 mm Hg at baseline obtained a significant reduction of 15 mm Hg in SBP and 7 mm Hg in DBP from flaxseed ingestion. The antihypertensive effect was achieved selectively in hypertensive patients. Circulating &agr;-linolenic acid levels correlated with SBP and DBP, and lignan levels correlated with changes in DBP. In summary, flaxseed induced one of the most potent antihypertensive effects achieved by a dietary intervention.

Oxidation of membrane cholesterol alters active and passive transsarcolemmal calcium movement.

Oxygen free radicals have the ability to oxidize cholesterol. However, nothing is known about the effects of cholesterol oxidation on ion transport in isolated myocardial membranes. The purpose of the present study was to investigate the effects of in situ oxidative modification of sarcolemmal cholesterol on Ca2+ flux. Cholesterol oxidase was used to oxidatively modify membrane cholesterol. After incubation of cardiac sarcolemmal vesicles with cholesterol oxidase, cholest-4-en-3-one (cholestenone) was the predominant species of oxidated cholesterol produced. Cholesterol oxidase inhibited sarcolemmal Na(+)-Ca2+ exchange in a concentration-dependent manner. Both the Vmax and Km of the reaction were altered after cholesterol oxidase treatment. Extensive treatment of the sarcolemmal membranes with cholesterol oxidase increased the passive permeability characteristics of the membrane. Passive Ca2+ efflux from the sarcolemmal vesicles was stimulated by increasing the concentration of cholesterol oxidase. ATP-dependent Ca2+ uptake was also inhibited after cholesterol oxidase treatment, but it was not as sensitive as the Na(+)-Ca2+ exchange. Conversely, passive Ca2+ binding to sarcolemmal vesicles was strikingly stimulated by cholesterol oxidase treatment. The results demonstrate that oxidative modification of sarcolemmal membrane cholesterol can directly affect ionic interactions with the sarcolemmal vesicle and provide potentially important mechanistic information for the molecular basis of the effects of free radicals on ion flux and function in the heart.

Effects of oxidative modification of cholesterol in isolated low density lipoproteins on cultured smooth muscle cells

SummaryIt has been proposed that low density lipoprotein (LDL) must undergo oxidative modification before it can participate in atherosclerosis. The present paper studied the effect of cholesterol oxidation in LDL on cultured vascular smooth muscle cells. LDL was oxidized by cholesterol oxidase (3-β-hydroxy-steroid oxidase) which catalyzes the oxidation of cholesterol to 4-cholesten-3 one and other oxidized cholesterol derivatives. Cholesterol oxidase treatment of LDL did not result in lipid peroxidation. Cultured rabbit aortic smooth muscle cells were morphologically changed following exposure to cholesterol oxidized LDL. Nile red, a hydrophobic probe which can selectively stain intracellular lipid droplets, was applied to detect the cellular lipid content after treatment with oxidized or non-oxidized LDL cholesterol. LDL which did not undergo oxidation of its cholesterol had no effect on the cells. However, cellular nile red fluorescence intensity was increased as the pre-incubation time of cholesterol oxidase with LDL increased. This was supported by HPLC analysis which revealed that the oxidized cholesterol content of treated cells increased. These findings suggest that cholesterol oxidation of LDL can alter lipid deposition in the cells and change cell morphology. The oxidation of cholesterol in vivo may play an important role in the modification of LDL which could contribute to the generation of the lipid-laden foam cells.

Oxidation of Nuclear Membrane Cholesterol Inhibits Nucleoside Triphosphatase Activity

Oxygen derived free radicals can oxidize membrane cholesterol. We have previously shown that cholesterol in the nuclear membrane can modulate nuclear nucleoside triphosphatase (NTPase) activity. Nucleocytoplasmic transport of peptides and mRNA via the nuclear pore complex may be regulated by the NTPase. The purpose of the present study was to determine if oxidation of nuclear cholesterol could alter NTPase activity. Nuclear membrane cholesterol was oxidized in situ with cholesterol oxidase (to selectively oxidize cholesterol) and NTPase activity measured. HPLC analysis confirmed the formation of cholesterol oxides. The activity of the NTPase was strikingly inhibited by cholesterol oxidase treatment. The Vmax of the NTPase was significantly decreased after cholesterol oxidase treatment but the Km value was unchanged. The sensitivity of NTPase activity to varying cholesterol oxidase concentrations also suggested that cholesterol located in the inner leaflet of the nuclear membrane appeared to be more important in the modulation of NTPase activity than that in the cytoplasmic leaflet. Our results indicate that oxidation of nuclear membrane cholesterol inhibits NTPase activity. These results have implications for peptide and mRNA flux across the nuclear membrane during conditions where lipid oxidation may be expected.

An international basic science and clinical research summer program for medical students

An important part of training the next generation of physicians is ensuring that they are exposed to the integral role that research plays in improving medical treatment. However, medical students often do not have sufficient time to be trained to carry out any projects in biomedical and clinical research. Many medical students also fail to understand and grasp translational research as an important concept today. In addition, since medical training is often an international affair whereby a medical student/resident/fellow will likely train in many different countries during his/her early training years, it is important to provide a learning environment whereby a young medical student experiences the unique challenges and value of an international educational experience. This article describes a program that bridges the gap between the basic and clinical research concepts in a unique international educational experience. After completing two semester curricula at Alfaisal University in Riyadh, Kingdom of Saudi Arabia, six medical students undertook a summer program at St. Boniface Hospital Research Centre, in Winnipeg, MB, Canada. The program lasted for 2 mo and addressed advanced training in basic science research topics in medicine such as cell isolation, functional assessment, and molecular techniques of analysis and manipulation as well as sessions on the conduct of clinical research trials, ethics, and intellectual property management. Programs such as these are essential to provide a base from which medical students can decide if research is an attractive career choice for them during their clinical practice in subsequent years. An innovative international summer research course for medical students is necessary to cater to the needs of the medical students in the 21st century.

The nuclear membrane integrity assay

A novel technique is described for the evaluation of membrane integrity in isolated nuclei. Membrane integrity is assessed by measuring nuclear fragility in response to high salt conditions. Salt-induced disruption of the nuclear membrane is followed by spectrophotometric monitoring of released nucleotides. The assay is based on determining the amount of salt necessary to induce release of 50% of the total pool of releasable nucleotides. This allows semiquantitative comparison of relative nuclear membrane strength or integrity of different samples in response to high salt conditions. In this manner, the effects of altered nuclear membrane composition or metabolism on membrane integrity may be monitored.

Effects of cholesterol oxidase on cultured vascular smooth muscle cells

SummaryCholesterol oxidase (3β-hydroxy-steroid oxidase) catalyzes the oxidation of cholesterol to 4-cholesten-3 one and other oxidized cholesterol derivatives. The purpose of the present study was to investigate its effects on cultured vascular smooth muscle cells. Cultured rabbit aortic smooth muscle cells were morphologically altered after exposure to cholesterol oxidase in the presence of culture medium containing 10% fetal calf serum. If fetal calf serum was absent, cells were unaffected by the treatment. The extent of morphological change of the smooth muscle cells was dependent upon the time of exposure to the enzyme and the concentration of cholesterol oxidase employed. After moderate treatment with cholesterol oxidase, cells excluded trypan blue. Further, a specific mitochondrial marker DASPMI (dimethyl aminostyryl-methyl-pyridiniumiodine) which was used as a fluorescent index of cell viability, revealed that cell viability was unchanged after moderate cholesterol oxidase treatment. Nile red, a hydrophobic probe which selectively stains intracellular lipid droplets, was applied to detect the cellular lipid content after treatment with cholesterol oxidase. Cellular nile red fluorescence intensity increased linearly with the time and concentration of cholesterol oxidase treatment. These results demonstrate that cholesterol oxidase alters lipid deposition in the cell and changes cell morphology. The primary site of action of cholesterol oxidase appears to be independent of the cell membrane itself and instead is dependent upon the lipid content in the surrounding culture media. These changes occur prior to the cytotoxic effects of extensive oxidation. Because oxidized cholesterol may play an important role in the pathogenesis of atherosclerosis, our results have implications for intracellular accumulation of lipids in smooth muscle cells during the atherosclerotic lesion.

Evaluation of the clinical utility, efficacy and safety of a novel medical device for the treatment of foot ulcers: Rationale and design of the carbothera trial

BACKGROUND: Foot ulceration usually precedes more serious foot complications such as infection, gangrene or amputation. The risk of developing foot ulcers has been estimated to be higher in individuals with peripheral arterial disease, diabetes and kidney disease. OBJECTIVE: To evaluate the healing potential of CO2-enriched water in patients with foot ulceration. METHODS: This is a multi-centered; placebo controlled and randomized clinical trial. Patients will have at least 1 distal extremity ulcer and will be randomized to receive a treatment with bath therapy at 37oC containing either 1,000-1200 ppm CO2-enriched tap water (the intervention), or non- carbonated tap water (the control group). The treatment will be carried out 3 times/week for 15 minutes per session for 4 months for a total of 48 treatments. At baseline and at the end of every treatment month, wound assessment, measurement of limb oxygenation, ankle brachial pressures as well as McGill pain questionnaire will be carried out. Blood will also be collected at baseline and at the end of every month of the treatment period (for a total of 5 collections) for the measurement of different biomarkers. BASELINE DATA: At baseline all 14 participants have at least one distal extremity ulcer and 93% (13/14) are diabetic. Although 6 of the participan`ts have peripheral arterial disease (left and/or right limb) as evidenced by an ankle brachial index (ABI) <0.9, another 5 exhibited non-compressible ankle arteries and 3 participants with left and right ABI of ≥ 0.9. Mean age of participants is 60.2 ± 1.7 and 64% (9/14) of the participants are undergoing hemodialysis for ESRD and 29% (4/14) are below knee amputees. CONCLUSIONS: The proposed clinical study will evaluatve the therapeutic potential, safety and efficacy of CO2 enriched water (produced by the Carbothera device) on treating foot ulcers.

Plasmid lipid and lipoprotein pattern in the Inuit of the Keewatin district of the Northwest territories

It has long been recognized that certain indigenous populations, such as the traditional living Inuit, have been relatively spared from ischemic heart disease despite their high fat diet. There is evidence to suggest that elevated serum levels of oxidated cholesterol may be a strong risk factor for atherogenesis. This study was performed to examine the plasma levels of lipid, triglyceride, lipoprotein cholesterol and oxidated cholesterol derivatives in the Inuit of the Keewatin district of Canada. Lipoprotein isolation from plasma was performed by serial centrifugation and apolipoprotein concentrations and native and esterified cholesterol content of the lipoprotein isolated were determined. Analysis of cholesterol and its oxidation products was performed using high pressure liquid chromatography. The Inuit showed a decreased concentration of both VLDL apolipoprotein and LDL apolipoprotein. The incidence of oxidatived cholesterol in Inuit VLDL and LDL was higher than control except for the 25 α-hydroxy derivative in VLDL. These data provide insight into the relative contributions of genetic and environmental influences on the development of ischemic heart disease.

Cardiac Sarcolemmal Na+/H+ Exchange after a Myocardial Infarction in the Rat

A growing number of studies have implicated the Na+/H+ exchanger in ischemic/reperfusion damage to the heart [1–7]. Other studies have now demonstrated accelerated ion flow through this exchanger in hypoxic/ reoxygenation insult to the heart as well [8–10]. While these are important pathological events, they are largely immediate reactions of Na+/H+ exchange activity in response to changes in the intracellular ionic environment in the heart. These reactions occur so quickly that they likely do not involve structural changes in the protein or alterations in protein synthesis. However, during low-flow ischemia of a relatively long duration, there are indications that these pathways are beginning to be activated. Changes in the Na+/H+ exchange mRNA message have been detected in hearts after three hours of low-flow ischemia [11]. These changes do not occur in global ischemia experiments, which employ considerably shorter ischemic periods (≤1 hour) [11,12]. Chronic alterations in the exchanger would be more likely to occur during conditions where an adaptive stimulus is placed upon the heart for a much longer period of time and/or where the tissue is allowed sufficient time to induce its adaptive mechanisms. A stimulus that frequently induces an adaptive response in the heart is myocardial disease.