A comparative study on fatty acid profile in selected vessels of coronary artery bypass graft (CABG)

Atherosclerosis is one of the leading non-communicable diseases in Sri Lanka. Analysis of fatty acid composition in blood vessels is important in understanding the development of atherosclerosis. Here, analyses of fatty acid profiles in major arteries which are commonly used in Coronary Artery Bypass Graft surgery (CABG) were subjected to investigation. Patients (n = 27) undergoing elective CABG were enrolled in the study. A small biopsy segment of the saphenous vein (SV), radial artery (RA), and left internal mammary artery (LIMA) of patients was obtained during the surgery. The fatty acid (FA) profile of tissue samples was analyzed using Gas Chromatography-Mass Spectroscopy (GCMS). Among the different arteries tested, palmitic acid and stearic acid were the predominant fatty acids. As far as monounsaturated FA (MUFA) are concerned, oleic acid was found to be the most abundant MUFA in vessels. The FA profile of LIMA samples had a higher SFA percentage and lower unsaturated FA percentage compared to other vessels. Furthermore, the vessel samples of RA indicated the highest percentage of pro-inflammatory ω -6 polyunsaturated fatty acids (PUFA) as well as a higher percentage ratio between ω -6: ω -3 PUFA. The fatty acid composition and ω -6: ω -3 PUFA ratio suggests that LIMA graft is preferred for CABG over RA and SV.

Changes in erythrocyte glucose-6-phosphate dehydrogenase (G6PD) and reduced glutathione (GSH) activities in the development of senile and diabetic cataracts

Oxidative and osmotic stress have been implicated in the pathogenesis of cataracts. Reactive oxygen intermediates (ROI) mediate peroxidation of membrane lipids and cause irreversible damage to lens proteins. The purpose of this study was to assess the changes in erythrocyte glucose- 6-phosphate dehydrogenase enzyme (G6PD) and reduced glutathione (GSH) levels in the development of senile and diabetic cataracts. The activity of erythrocyte G6PD and the concentration of GSH were measured to assess changes in oxidation-reduction status. The oxidation-reduction status of 26 non-diabetic non-cataract (control) subjects were compared with 24 diabetic non-cataract, 30 diabetic cataract and 28 non-diabetic cataract subjects. The results revealed that the GSH and G6PD levels of the subjects with senile cataracts were significantly lower than the subjects without cataracts. The present study reveals the risk of developing senile cataracts is associated with decreased levels of erythrocyte G6PD and GSH. In the formation of diabetic cataracts an adequate supply of NADPH (G6PD activity) is essential to produce osmotically active sorbitol in the lens.

Red blood cell antioxidant levels in Wuchereria bancrofti infection

The elimination of microfilariae of Wuchereria bancrofti is probably mediated by free radicals. Red cell catalase (C), glutathione peroxidase (GPX), and superoxide dismutase (SOD) activity levels were measured as an indirect method of assessing blood oxidant status in 29 asymptomatic microfilaraemics, 29 "endemic normals", and 29 controls living in a non-endemic area. Changes in the activity of these enzymes were also compared over a one month period in 22 asymptomatic microfilaraemics randomised to receive either single dose or 14 day treatment with diethyl carbamazine citrate (DEC). Red cell GPX activity levels were significantly higher in "endemic normals" when compared to mf positive cases and non-endemic controls. An early and significant increase in GPX activity (on days 3, 7 and 14 compared to pretreatment levels, p<0.01) was observed after DEC in both treatment groups. Increases in the activity of catalase and SOD became significant only on days 14 and 30 respectively. The percentage reduction in microfilaraemia correlated significantly with the percentage increase in GPX activity levels (R(2)=0.58, p=0.6 x 10(-5)). Our results may suggest a role for GPX related oxidant species in the elimination of microfilariae.

Protection by garlic against adriamycin induced alterations in the oxido-reductive status of mouse red blood cells

The effects of oral garlic supplementation on the activities of (a) the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) and (b) lipid peroxidation, as assessed by malondialdehyde (MDA) production in red blood cells of normal mice and those subject to oxidative stress by chronic administration of the anti-tumour drug adriamycin has been investigated. As expected, adria-mycin administration resulted in a significant increase in MDA generation (by 105.4%) and a decrease in GPX activity (by 23.8%) in the red blood cells. Although garlic had no significant effects on the basal levels of the antioxidant enzymes or MDA generation in red blood cells of normal mice (untreated with adriamycin), at doses of 20 mg/kg or 100 mg/kg, garlic was able to decrease significantly the adriamycin induced changes in the oxido-reductive status of the red blood cells. Thus, on administration of adriamycin to mice fed diets containing 20 mg/kg or 100 mg/kg garlic, the drug-induced increase in MDA generation was 38.2% and 22.5% respectively, less than that produced by adriamycin in mice fed normal diets, containing no garlic (105.4%). Similarly, in mice fed diets providing 20 mg/kg and 100 mg/kg garlic, adriamycin was able to decrease GPX activity by only 15.1% and 7.6% respectively, less than that produced by adriamycin in rats fed normal diets, containing no garlic (23.9%).

Hepatitis B and C virus markers among new entrant medical students

AIM

To investigate the presence of hepatitis B and C virus markers in new entrant medical students at the Faculty of Medicine, University of Kelaniya.

METHOD

456 students (mean age 24 years, SD 3.5, 257 men) were investigated before they were exposed to clinical work, using a questionnaire to assess sociodemographic factors and possible risk factors for contracting hepatitis B or C. Blood samples were tested for HBs Ag and anti HBs (n = 456), and anti-HCV (n = 162 randomly selected samples) with a third generation sandwich radioimmunoassay technique.

RESULTS

The students were from 20 of the 25 districts in the country, although their distribution was not inform. A past history of hepatitis or jaundice was obtained from 24 (5.3%) and 6 (1.3%) students respectively. None of them had been vaccinated against hepatitis B. At least one risk factor for hepatitis B or C was present in 32 (7%) of them. None of the samples were positive for HBsAg or anti-HCV, and only two (0.44%) were positive for anti-HBs.

CONCLUSION

Our results support the view that exposure to hepatitis B and C seems to be uncommon in this country, at least up to young adulthood. As most new entrant medical students are not immune to these infections there is a strong case to vaccinate them against hepatitis B before they are exposed to clinical work.

Effect of oral supplementation with vitamin E on the oxido-reductive status of red blood cells in normal mice and mice subject to oxidative stress by chronic administration of adriamycin

The effect of oral vitamin E supplementation on the oxido-reductive status of red blood cells in normal mice and those subject to oxidative stress by chronic administration of the anti-tumour drug Adriamycin was investigated. Mice were randomly separated into three groups of 20 animals each and maintained on diets identical in all respects except for vitamin E content. Group 1 received a low vitamin E diet that provided 10 mg vitamin E/kg body weight/day, group 2 received a normal mice chow diet (45 mg vitamin E/kg body weight/day) while group 3 received a high vitamin E diet (200 mg vitamin E/kg body weight/day). In comparison with the normal mice in group 1, their counterparts in groups 2 and 3 exhibited significantly higher (P < 0.001) activities of superoxide dismutase (SOD) in red blood cells (79.4% higher in group 2 and 114.2% higher in group 3, respectively) and produced lower concentrations of malondialdehyde (MDA) (22.9% less in group 2 and 51.2% less in group 3, respectively), with little difference in the glutathione peroxidase (GPX) activity. In Adriamycin-treated animals on the low vitamin E diet (group 1) the red blood cell SOD activity and MDA production were 46.2% and 200.7% higher (P < 0.001), respectively, and the GPX activity was 39.1% lower than in the red blood cells of untreated (normal) animals in the same group. The Adriamycin-induced changes were significantly less in animals receiving higher doses of vitamin E (groups 2 and 3). Thus, in the group maintained on the high vitamin E diet (group 3), Adriamycin administration resulted in only a 38.9% increase in the MDA production above that generated by red blood cells of normal mice in the same group, with no significant change in the SOD or GPX activities. Thus, in normal conditions as well as in conditions of oxidative stress, high doses of vitamin E appear to be able to protect the oxido-reductive status of red blood cells by modulating the extent of lipid peroxidation as well as the activities of antioxidant enzymes.

Methylprednisolone and gentamicin effects on hepatosplanchnic blood flow and carbohydrate metabolism in endotoxemic Yucatan miniature pigs

Conjoint therapy of a glucocorticoid and aminoglycoside antibiotic have been recommended for septic shock. These studies examined the hemodynamic and metabolic effects of methylprednisolone sodium succinate (MPSS) with and without gentamicin sulfate in a nonanesthetized model of nonseptic endotoxemia in Yucatan miniature pigs. Methylprednisolone sodium succinate alone had no effect on endotoxin-induced systemic hypotension. Endotoxemic pigs treated with MPSS in combination with gentamicin sulfate had lower mean arterial pressures than did MPSS-treated and nontreated endotoxemic pigs. Methylprednisolone sodium succinate alone and with gentamicin sulfate improved portal and hepatic venous blood flows moderately. Net hepatic lactate extraction, glucose production, and whole body [6-3H]glucose-derived rates of glucose appearance were also improved, but [6-3H]glucose-derived rates of glucose disappearance and blood lactate concentrations were increased, leading to no improvement in plasma glucose concentration. Pancreatic insulin secretion was higher in treated groups, which may have contributed to greater glucose utilization rates. Hepatic oxygen extraction efficiency was not affected by treatment, but increased in all groups to maintain hepatic oxygenation at base-line values. Although a calcium-antagonistic activity of gentamicin has been reported to synergize with endotoxin, thereby adversely affecting cardiovascular function, such effects did not complicate the metabolic response to steroid in the present studies.

Naloxone therapy in awake endotoxemic Yucatan minipigs

Twelve Yucatan miniature pigs were fitted with jugular, portal, hepatic vein, and carotid artery catheters, and hepatic artery and portal vein flow cuffs to quantitate portosystemic and transhepatic kinetics. Seventy-two hours later they were placed in slings, and following a 3-hr control period were infused with Escherichia coli endotoxin at 15 micrograms/kg/hr for 6 hr. Eight were controls and 4 received a primed (2 mg/kg) continuous infusion (2 mg/kg/hr) of naloxone 1 hr after initiation of endotoxin. In the naloxone group, arterial hypotension developed by 60 min. Arterial pressure increased to 125 mm Hg by 80 min (20 min post naloxone) and maintained this level for 3 hr. [6-3H]Glucose-derived rate of disappearance (Rd) values were increased above their own control period at 60 and 80 min, but were approximately 55% lower than untreated controls. Rate of appearance (Ra) values remained unchanged in the naloxone group resulting in a net glucose deficit. After 1 hr of endotoxin, blood pyruvate increased from 1.0 to 1.8 mg%, reached 3.3 mg% at 80 min, and remained elevated. Blood lactate similarly increased from 11 to 35 mg% by 60 min, increasing further to 82 mg% 20 min after naloxone infusion, in concert with signs of severe distress. Portal and hepatic total O2 decreased by 60 min and 100 min, respectively, reflecting depressed hepatic O2, input. Lethality was 75% in naloxone-treated pigs by the end of the experiment, vs 0% in untreated animals. Naloxone improves some hemodynamic parameters. However, in these conscious postsurgical patients, naloxone blocked some beneficial effects of endogenous opiates resulting in severe metabolic derangements and increased mortality.

Endotoxin dose. I. Hemodynamic, metabolic, and lethal consequences in Yucatan minipigs

This study was performed in part to establish an endotoxin dosage in miniature swine that would yield reproducible cardiovascular and metabolic aberrations over a specific 6-h sampling period, minimizing lethality during that time. Five groups of three 6-mo-old Yucatan miniature pigs were surgically fitted with jugular vein and carotid artery catheters. One week later they were placed in slings and infused for 6 h with Difco 055:B5 endotoxin at dosages of 0, 2.5, 7.5, 15, and 25 micrograms X kg-1 X h-1. Significant (P less than or equal to 0.05) time-dose interactions were observed in mean arterial pressure, plasma glucose, serum potassium, blood lactate, pyruvate, bicarbonate, pH, PO2, PCO2, and urea nitrogen. Significant (P less than or equal to 0.05) differences were seen in lethality by 5 days postendotoxin: 0 = 0%, 2.5 = 0%, 7.5 = 33%, 15 = 67%, and 25 = 100% lethal. These animals exhibited a sensitive dose response to endotoxin, often at two- or threefold dose differences. The 15 and 25 micrograms X kg-1 X h-1 groups consistently demonstrated the most profound changes in the parameters measured.

Indices of stress in housed experimental sheep

Six trained sheep were used in isotope dilution studies to determine the relations between glucose and lactate metabolism. The animals were judged by their behaviour and by their arterialplasma glucose and cortisol concentrations to be unstressed before and during each experiment. In each animal, however, the concentration of lactate in an arterial plasma sample taken immediately before an experiment was greater than the mean arterial plasma lactate concentration found during the course of the experiment. This increase in the concentration of lactate may be a sensitive index of apprehension in sheep which are well accustomed to being handled and which by other criteria appear to be unstressed.

A comparative study of ketone body metabolism between the camel (Camelus dromedarius) and the sheep (Ovis aries)

1. Plasma levels of beta-hydroxybutyrate (BHB), and acetoacetate (AcAc) have been measured in camels (Camelus dromedarius) and sheep (Ovis aries). The activity of beta-hydroxybutyrate dehydrogenase (BHB-deH2) (E.C. 1.1.1.30) was studied in the rumen epithelium and the liver of these animals. 2. Concentrations of plasma BHB and AcAc in the camel were in respective order 33 and 4 times lower than that of the sheep. The ratios of BHB to AcAc were 0.61 and 4.8 for the camel and sheep, respectively. 3. The activity of BHB-deH2 in the rumen epithelium of the camel and sheep were 7.15 and 66 mumol/hr/g wet wt tissue, respectively. The activity in both species was higher in the rumen epithelium than in the liver.

Glucose lactate interrelations in sheep

The constant-infusion, isotope-dilution method was used to investigate the interrelationships between the glucose and lactate pools of six trained sheep deprived of food overnight. Arterial plasma lactate concentration was a linear function of the net lactate entry rate as was the net production of glucose from lactate, which suggests that the net rate of formation of glucose from lactate is dependent on the availability of lactate. Similarly the arterial plasma glucose concentration was correlated with the net entry rate of glucose as was the net production rate of lactate from glucose, suggesting that the net rate of lactate production from glucose is a function of arterial plasma glucose concentration. The demonstration of these two interrelations between glucose and lactate in normal sheep suggests that, in the absence of external factors producing hormonal or other changes that could cause perturbations of carbohydrate homeostasis, the net rates of conversion of glucose to lactate and of lactate to glucose may be largely determined by the arterial concentrations of glucose and lactate, respectively.

Sheep lactate entry-rate measurements: error due to sampling jugular blood

Carotid arterial and jugular venous blood samples were taken simultaneously during primed continuous infusions of L-[U-14C]lactate in four sheep. The mean rate (n = 4) of total net formation of lactate (0.394 +/- 0.047 mg C/min per kg) calculated from the results obtained by analyzing the jugular blood samples for lactate concentration and specific radioactivity was significantly higher (0.01 greater than P greater than 0.005) than the mean rate (n = 4) calculated from the results of analysis of the arterial samples (0.302 +/- 0.036 mg C/min per kg). The error in the estimation of the rate of total net formation of lactate due to jugular sampling resulted from the negative arteriovenous difference found for lactate across the tissues of the head. These results illustrate the general need for examination of the suitability of venous sampling in experiments that make use of the continuous infusion isotope-dilution method.