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Biomedical subjects

I B Puddey

Publications and source records attributed to I B Puddey.

At least 55 records · Page 3Linked to original sources
PubMed1999

Docosahexaenoic acid but not eicosapentaenoic acid lowers ambulatory blood pressure and heart rate in humans.

Animal studies suggest that the 2 major omega3 fatty acids found in fish, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may have differential effects on blood pressure (BP) and heart rate (HR). The aim of this study was to determine whether there were significant differences in the effects of purified EPA or DHA on ambulatory BP and HR in humans. In a double-blind, placebo-controlled trial of parallel design, 59 overweight, mildly hyperlipidemic men were randomized to 4 g/d of purified EPA, DHA, or olive oil (placebo) capsules and continued their usual diets for 6 weeks. Fifty-six subjects completed the study. Only DHA reduced 24-hour and daytime (awake) ambulatory BP (P<0.05). Relative to the placebo group, 24-hour BP fell 5.8/3.3 (systolic/diastolic) mm Hg and daytime BP fell 3.5/2.0 mm Hg with DHA. DHA also significantly reduced 24-hour, daytime, and nighttime (asleep) ambulatory HRs (P=0. 001). Relative to the placebo group, DHA reduced 24-hour HR by 3. 5+/-0.8 bpm, daytime HR by 3.7+/-1.2 bpm, and nighttime HR by 2. 8+/-1.2. EPA had no significant effect on ambulatory BP or HR. Supplementation with EPA increased plasma phospholipid EPA from 1. 66+/-0.07% to 9.83+/-0.06% (P<0.0001) but did not change DHA levels. Purified DHA capsules increased plasma phospholipid DHA levels from 4.00+/-0.27% to 10.93+/-0.62% (P<0.0001) and led to a small, nonsignificant increase in EPA (1.52+/-0.12% to 2.26+/-0.16%). Purified DHA but not EPA reduced ambulatory BP and HR in mildly hyperlipidemic men. The results of this study suggest that DHA is the principal omega3 fatty acid in fish and fish oils that is responsible for their BP- and HR-lowering effects in humans. These results have important implications for human nutrition and the food industry.

Adult↗
PubMed1999

A randomised, controlled study of the effects of aerobic exercise and dietary fish on coagulation and fibrinolytic factors in type 2 diabetics.

Type 2 diabetes is associated with disturbances in coagulation and fibrinolysis. Prospective studies show that increased tissue plasminogen activator (tPA) antigen increases the risk of cardiovascular mortality. The present study examined the hypothesis that combining a regime of moderate aerobic exercise with one daily fish meal as part of a low-fat diet (30% total energy) would improve coagulation and fibrinolytic factors in dyslipidaemic type 2 diabetic patients. In a randomised. controlled, 8-week trial, 55 sedentary type 2 diabetic subjects with serum triglycerides >1.8 mmol/l and/or HDL-C <1.0 mmol/l were randomly assigned to a low-fat diet (30% daily energy intake) with or without one fish meal daily (3.6 g omega3 fatty acids/day) and further randomized to a moderate (55-65% VO2max) or light (heart rate <100 bpm) exercise program. Plasma levels of fibrinogen, coagulation factor VIIc, tPA and plasminogen activator inhibitor (PAI-1) antigen were measured before and after intervention. In the 49 subjects who completed the study, the fish diet alone, moderate exercise alone and the combination of fish and moderate exercise all led to significant reductions in tPA antigen concentrations (-2.1 ng/ml, p = 0.02. -1.9 ng/ml, p = 0.03, -2.0 ng/ml, p = 0.01, respectively) compared to controls. In multivariate regression, changes in fasting blood glucose (positively) and erythrocyte omega3 fatty acid composition (inversely) were independent predictors of the change in tPA antigen. The fish diet alone contributed to a significant rise in coagulation factor VIIc compared to controls (4.9%, p = 0.02), which was prevented by moderate exercise. No significant effects on PAI-1 antigen and fibrinogen were seen. In view of recent epidemiological findings, the reduction in tPA antigen with both fish and moderate exercise in these dyslipidaemic type 2 diabetic patients could reflect a reduced thrombotic potential and decreased cardiovascular risk. Furthermore, a small, albeit significant, increase in coagulation factor VIIc associated with fish can be prevented by a concomitant programme of moderate exercise.

Adult↗
PubMed1998

Alcohol, free radicals and antioxidants.

Antioxidants in alcoholic beverages, especially polyphenolic compounds in red wine, have been proposed as an important contributory factor to the protective effect of regular alcohol use against atherosclerotic cardiovascular disease. The postulated mechanism involves quenching of free radicals with decreased oxidative damage to low density lipoprotein (LDL) hence reducing its potential atherogenicity. There is definitive in vitro evidence that extracts of red wine, white wine, grape juice and beer can inhibit the oxidation of LDL, the degree of inhibition being directly proportional to beverage polyphenolic content and able to be abolished by prior stripping of the polyphenolics from the alcoholic beverage. These in vitro antioxidant effects have not been reliably reproduced in vivo after acute or short-term administration of alcoholic beverages. In fact, in some studies where white wine or beer have been given over 2-4 week periods, enhanced oxidizability of LDL cholesterol has been reported. Such findings are consistent with the possibility that, depending on the beverage, a predominant pro-oxidant effect of alcohol itself may outweigh any antioxidant effect of beverage polyphenolics. Increased oxidant stress and enhanced lipid peroxidation with alcohol have several biologically plausible explanations and have been reported as possible mechanisms for alcohol-related toxicity and injury in various tissues. Therefore, before the promotion of any particular benefits of ingestion of polyphenolics from alcoholic beverages (especially red wine) for prevention of atherosclerotic cardiovascular disease, the balance of redox effects in vivo will need careful further clinical and laboratory evaluation.

Alcohol Drinking↗
PubMed1998

A controlled trial of the effects of pattern of alcohol intake on serum lipid levels in regular drinkers.

To determine whether the effects of drinking pattern (predominantly weekend versus daily drinking) have differential effects on serum lipids, 55 healthy male drinkers were recruited on the basis of a regular alcohol intake, 210-500 ml absolute alcohol/week (approximately 3-6 standard drinks/day), with more than 60% consumed as beer. Fourteen subjects were categorised as predominantly weekend drinkers, while 41 subjects regularly drank on a daily basis. After maintenance of their drinking pattern during a 4-week familiarisation, subjects were randomised to either consume low alcohol beer (0.9%, v/v) only, or to maintain their usual drinking habit consuming full-strength beer (5%, v/v) for the next 4 weeks. They then switched to full-strength or low alcohol beer, respectively, for a further 4 weeks. Their drinking pattern remained constant during the study. In both weekend and daily drinkers, a reduction in alcohol intake (i.e. from 387 ml/week to 88 ml/week for weekend drinkers and from 418 ml/week to 95 ml/week for daily drinkers, respectively, P < 0.001) resulted in a similar 0.12 mmol/l fall in HDL-C (P < 0.01) with a concomitant significant fall in both apolipoproteins A-I and A-II. In daily drinkers total cholesterol fell by 0.28 mmol/l (P < 0.001) and triglyceride by 0.22 mmol/l (P < 0.01) with a reduction in alcohol intake, but no change in LDL-C was seen. In contrast, weekend drinkers total cholesterol was unchanged while triglyceride decreased by 0.26 mmol/l (P < 0.05) and LDL-C increased by 0.25 mmol/l (P < 0.01). Lp(a) increased with a reduction in alcohol intake in both daily (9.1 U/l, P < 0.05) and weekend drinkers (27.6 U/l, P = 0.07). Previous reports of a more atherogenic lipid profile with episodic versus regular daily drinking were not confirmed in this study and potentially favourable effects of alcohol to increase HDL-C and decrease Lp(a) were shown to be independent of drinking pattern in these moderate to heavy drinkers.

Adult↗
PubMed1998

Effects of a short-term circuit weight training program on glycaemic control in NIDDM.

This study assessed the effects of short-term circuit weight training (CWT) on glycaemic control in NIDDM. Twenty-seven untrained, sedentary subjects (mean age, 51) with NIDDM participated in an 8-week randomised, controlled study, involving either CWT 3 days/week (n = 15) or no formal exercise (control) (n = 12). All subjects performed regular self-blood glucose monitoring throughout. Fasting serum glucose and insulin were measured following a 12-h fast and during an oral glucose tolerance test (75 g) before and after 8 weeks. Twenty-one subjects completed the study (CWT, n = 11) (Control, n = 10). Strength for all exercises improved significantly after CWT. Pooled time-series analysis, using a random effects model, revealed an overall decrease in self-monitored glucose levels with CWT compared to controls. Significant reductions from baseline values were observed in both the glucose (-213 mmol l-1 per 120 min, P < 0.05) and insulin (-6130 pmol l-1 per 120 min, P < 0.05) area under the curve following CWT relative to controls. After adjustment for body mass changes, the change in self-monitored glucose levels and insulin area under the curve, but not glucose area under the curve, remained significant. Short-term CWT therefore may provide a practical exercise alternative in the lifestyle management of this condition.

Analysis of Variance↗
PubMed1998

Supplementation with isoflavonoid phytoestrogens does not alter serum lipid concentrations: a randomized controlled trial in humans.

Isoflavonoids are a class of flavonoids that are derived in the human diet mainly from soybean-based foods. The major dietary isoflavonoids, genistein and daidzein, have estrogen-like activity and are classed as phytoestrogens. Because estrogens can lower serum LDL cholesterol and raise HDL cholesterol, the objective of this study was to determine if isoflavonoids could improve serum lipids in healthy subjects. Forty-six men and 13 postmenopausal women not receiving hormone replacement therapy completed a randomized, double-blind, placebo-controlled trial of two-way parallel design and 8 wk duration. One tablet containing 55 mg of isoflavonoids (predominantly in the form of genistein) or one placebo tablet was taken daily with the evening meal. Subjects maintained their usual diet and physical activity, which were unchanged throughout the intervention. Measurement of isoflavonoids and their metabolites in 24-h urine samples provided an assessment of compliance and of isoflavonoid metabolism. Serum total, LDL, HDL and HDL subclass cholesterol, triglycerides and lipoprotein (a) were assessed at baseline and during the last week of intervention. After adjustment for baseline values, no significant differences in postintervention serum lipid and lipoprotein (a) concentrations between groups were identified. Further adjustment for age, gender and weight change did not alter the results. In addition, changes in urinary isoflavonoids were not significantly correlated with changes in serum lipids and lipoprotein (a). Therefore, this study does not support the hypothesis that isoflavonoid phytoestrogens can improve the serum lipids, at least in subjects with average serum cholesterol concentrations.

Adult↗
PubMed1998

The effects of alcohol on coagulation and fibrinolytic factors: a controlled trial.

Light-to-moderate alcohol intake is associated with a reduced incidence of ischaemic cardiovascular events, whilst heavy alcohol intake can predispose individuals to stroke. Alcohol-induced changes in coagulation and fibrinolysis may be relevant and are the subject of this controlled trial of varying alcohol intake in 55 predominantly beer-drinking men. Following 4 weeks stabilization maintaining usual drinking habits, participants were randomized to either continue usual alcohol intake or to restrict alcohol by changing to low alcohol beer for 4 weeks. In a final 4 week period, they crossed over to low or usual alcohol intake, respectively. Comparing combined low and usual alcohol periods, an increase in mean weekly alcohol intake from 92 to 410 ml (mean daily intake from 13 to 58 ml) was associated with a decrease in plasma fibrinogen (by 11%, P < 0.001) and platelet count (3%, P < 0.05), but increases in factor VII (7%, P = 0.001), tissue plasminogen activator (tPA; 16%, P = 0.01) and plasminogen activator inhibitor-1 (PAI-1; 21%, P < 0.001). The ratio, tPA/PAI-1, fell from 0.50 to 0.44 (P = 0.02) confirming the relatively greater increase in PAI-1 with alcohol consumption. Two lipid-associated natural anticoagulants, tissue factor pathway inhibitor and beta 2-glycoprotein-I, did not change. The substantial reduction in plasma fibrinogen with alcohol intake may well contribute to the apparent protection alcohol confers against ischaemic coronary and cerebral events. The increase in factor VII and relatively greater increase in PAI-1 than tPA with alcohol intake may attenuate this benefit and indeed may sufficiently predispose individuals to thrombosis to contribute to the increased incidence of ischaemic stroke seen in heavier drinkers. The balance of anticoagulant and procoagulant and fibrinolytic effects in any individual may vary depending on quantity and type of alcoholic beverage ingested, as well as on genetic and other variables, all of which merit further study.

Adult↗
PubMed1998

Influence of pattern of alcohol intake on blood pressure in regular drinkers: a controlled trial.

OBJECTIVE: To evaluate the effects of patterns of drinking (weekend versus daily drinking) on the pressor responses to alcohol in 55 male drinkers using clinic and 24 h ambulatory blood pressure monitoring. DESIGN: A randomized, controlled cross-over trial. METHODS: Recruitment required a regular alcohol intake of 210-500 ml absolute alcohol/week, with > 60% consumed as beer. Fourteen subjects were categorized as predominantly weekend drinkers, whereas the remaining 41 subjects regularly drank on a daily basis. After 4 weeks of familiarization, all subjects were randomly allocated to drinking low-alcohol beer (0.9% vol:vol) only or to maintain their usual drinking habits with provision of full-strength beer (5% vol:vol) for 4 weeks. They then switched back to their usual drinking habits or low-alcohol beer, respectively, for a further 4 weeks while maintaining their usual drinking pattern. RESULTS: Baseline ambulatory systolic blood pressure in weekend but not in daily drinkers was 2.4 mmHg higher on Monday than it was on Thursday (P = 0.02). This Monday-Thursday difference was lost during intervention. When subjects switched from the high-alcohol to the low-alcohol period the falls in ambulatory systolic blood pressure in weekend (3.1 mmHg, P < 0.001) and daily drinkers (2.2 mmHg, P < 0.001) were similar. Most of the fall was evident during week 1 of the low-alcohol period for weekend drinkers but not until week 4 for daily drinkers. CONCLUSION: The pressor response to alcohol consumption is similar in magnitude in weekend and daily drinkers, present throughout a 24 h period and has a rapid onset/offset in weekend drinkers but is more sustained in daily drinkers.

Adult↗
PubMed1998

Effects of dietary fish and weight reduction on ambulatory blood pressure in overweight hypertensives.

Obesity is a major factor contributing to hypertension and increased risk of cardiovascular disease. Regular consumption of dietary fish and omega3 fatty acids of marine origin can lower blood pressure (BP) levels and reduce cardiovascular risk. This study examined the potential effects of combining dietary fish rich in omega3 fatty acids with a weight loss regimen in overweight hypertensive subjects, with ambulatory BP levels as the primary end point. Using a factorial design, 69 overweight medication-treated hypertensives were randomized to a daily fish meal (3.65 g omega3 fatty acids), weight reduction, the 2 regimens combined, or a control regimen for 16 weeks. Sixty-three subjects with a mean+/-SEM body mass index of 31.6+/-0.5 kg/m2 completed the study. Weight fell by 5.6+/-0.8 kg with energy restriction. Dietary fish and weight loss had significant independent and additive effects on 24-hour ambulatory BP. Effects were greatest on awake systolic and diastolic BP (P<0.01); relative to control, awake pressures fell 6.0/3.0 mm Hg with dietary fish alone, 5.5/2.2 mm Hg with weight reduction alone, and 13.0/9.3 mm Hg with fish and weight loss combined. These results also remained significant after further adjustment for changes in urinary sodium, potassium, or the sodium/potassium ratio, as well as dietary macronutrients. Dietary fish also significantly reduced 24-hour (-3.1+/-1.4 bpm, P=0.036) and awake (-4.2+/-1.6 bpm, P=0. 013) ambulatory heart rates. Weight reduction had a significant effect on sleeping heart rate only (-3.2+/-1.7 bpm, P=0.037). Combining a daily fish meal with a weight-reducing regimen led to additive effects on ambulatory BP and decreased heart rate. The effects were large, suggesting that cardiovascular risk and antihypertensive drug requirements are likely to be reduced substantially by combining dietary fish meals rich in omega3 fatty acids with weight-loss regimens in overweight medication-treated hypertensives. The reduction in heart rate seen with dietary fish suggests a cardiac/autonomic component, as well as vascular effects, of increased consumption of omega3 fatty acid from fish.

Adult↗
PubMed1998

Carbohydrate-deficient transferrin as a marker of change in alcohol intake in men drinking 20 to 60 g of alcohol per day.

We evaluated carbohydrate-deficient transferrin (CDT) and gamma-glutamyltranspeptidase (gamma-GT) as markers of alcohol intake and change in alcohol intake in white Australian men aged 20 to 63 years who regularly drank 20 to 60 g of alcohol/day (2 to 6 standard drinks), either as weekend (n = 14) or daily drinkers (n = 41). After 4 weeks of familiarization on usual alcohol intake, men were provided with low alcohol beer (24 x 375 ml cans, 0.9%, v/v, two-weekly), and, for 4 weeks, consumed as much or as little as they wished with no additional alcohol permitted. In an alternate 4-week period, the same amount of full-strength beer (4.9%, v/v) was provided, whereas subjects continued their usual amount and pattern of alcohol consumption. The order of experimental conditions was randomized. Retrospective 7-day diaries documented weekly alcohol intake during 4 weeks of familiarization and 8 weeks of intervention. Mean alcohol intake was 345 g/week of alcohol (SD 97) during familiarization. During the last 4 weeks of intervention (study weeks 8 to 12), mean alcohol intake either increased by 360 g/week (SD 138) with the switch from low to high alcohol or decreased by 328 g/week (SD 120) with the reverse. During familiarization (study weeks 1 to 4), alcohol intake was significantly related independently (R2 = 0.21) to mean corpuscular volume (p = 0.008) and uric acid (p = 0.003), but not to gamma-GT (p = 0.22) nor CDT (p = 0.94). Change in alcohol intake was predicted independently (R2 = 0.60) by change in CDT (p < 0.0001) and gamma-GT (p = 0.0003), but not by change in uric acid or mean corpuscular volume. A 10% change in CDT gave 70% sensitivity and 80% specificity to detect a change of at least 2 standard drinks/day; respective values were 68% and 0 for 10% change in gamma-GT. Results were not related to drinking pattern, smoking, age, or weight. CDT, particularly when used as a continuous variable, may have a place in monitoring alcohol consumption, even in men whose alcohol intake is in the 20 to 60 g/day range.

Adult↗
PubMed1997

The role of copper reduction by alpha-tocopherol in low-density lipoprotein oxidation.

The oxidation of lipoproteins is thought to be an important early step in atherogenesis. The measurement of lipid peroxidation in low-density lipoprotein (LDL) challenged with Cu2+ has become a widespread test to determine the "susceptibility" of LDL to oxidation. The determination of lag time to oxidation is thought to be a measure of the total antioxidant capacity of the LDL. However, we and others have failed to observe any correlation between lag time and the LDL content of its major lipid antioxidant, alpha-tocopherol. In fact, several studies now suggest a pro-oxidant role for tocopherol under some conditions of LDL oxidation. In the present study we sought to determine if there was a relationship between Cu2+ reduction by LDL and kinetic parameters of LDL oxidation. LDL (0.3 mmol/l cholesterol, approximately 0.1 mg protein/ml) was incubated at 30 degrees C with 2 microM Cu2+ and the formation of conjugated dienes measured over a 4-h period. Using neocuproine, an indicator molecule that specifically complexes Cu+ but not Cu2+, the reduction of Cu2+ by LDL was monitored. The final Cu concentration in these assays was 100 microM and neocuproine 750 microM. Cu+ formation was measured by absorbance at 454 nm. A strong negative correlation was observed between copper reduction by LDL and lag time to oxidation (r = -0.66, p < .005, n = 16). Further experiments showed that (1) LDL was able to reduce Cu2+ to Cu+ in a time and concentration-dependent manner; (2) blocking of free -SH groups on LDL apoprotein B by preincubation with dithionitrobenzoic acid (DTNB) had no significant effect on the rate and extent of Cu2+ reduction; (3) consumption of tocopherol in LDL undergoing oxidation with Cu was very rapid (rate = 6 x 10(-10) M s(-1)). When Cu+ formed during incubation with LDL was complexed with neocuproine, there was significant inhibition of LDL oxidation, as indicated by lipid peroxide formation and mobility on agarose gel electrophoresis. Surprisingly, tocopherol consumption was even more rapid in the presence of neocuproine, consistent with a shift in Cu2+/Cu+ equilibrium and faster reduction of Cu2+ by alpha-tocopherol. These results indicate that under these conditions tocopherol is a major reducing agent in LDL, converting Cu2+ to Cu+, and therefore, may play an important role in promoting LDL oxidation. However, there was no correlation between LDL tocopherol content and reduction of Cu2+. Examination of the time course of Cu2+ reduction in tocopherol enriched and depleted LDL indicates that tocopherol may determine Cu reduction at early time points but that the eventual capacity of LDL to reduce Cu may depend on more complex interactions between tocopherol and other LDL components.

Cations, Divalent↗
PubMed1997

Unexpected dose response of copper concentration on lipoprotein oxidation in serum: discovery of a unique peroxidase-like activity of urate/albumin in the presence of high copper concentrations.

Oxidative modification of low-density lipoprotein (LDL) may be an important factor in atherogenesis. The susceptibility of LDL to oxidation is usually determined in isolation by exposing LDL to oxidative stress induced by Cu ions or a free radical initiator. In these cases oxidation is carried out in the absence of water-soluble vitamins or serum proteins that may be present at the site of oxidation in vivo. We have examined the Cu2+-induced oxidation of lipoproteins in diluted serum. When oxidizing isolated LDL, there is a decrease in lag time with increasing concentration of Cu2+ until a minimum "lag time" is reached at a Cu:LDL ratio of about 50:1. In serum, we have shown an initial decrease in "lag time" with increasing Cu concentration up to 12.5 microM. However, with higher Cu concentrations "lag time" to oxidation increases, contrary to expectation, until a maximum is reached at about 50 microM Cu. This dose response observed for Cu oxidation of diluted serum was highly reproducible in a number of individual subjects. When serum was gel-filtered to remove low molecular weight compounds, the resulting filtrate behaved the same as isolated LDL. Uric acid was found to be an important component of the low molecular weight fraction responsible for the paradoxical effect of Cu concentration on serum oxidation. The same paradoxical effect was found when isolated LDL was incubated with uric acid in the presence of human serum albumin (HSA) and Cu. The incubation of HSA with reducing agents such as uric acid or bilirubin in the presence of high Cu concentrations, produces a "peroxidase-like" activity, capable of breaking down hydrogen peroxide as well as lipid hydroperoxides. The decomposition of lipid peroxides is a likely explanation for the longer serum oxidation lag times seen at higher Cu concentrations. Our study highlights the possible importance of interactions between uric acid and serum proteins in the presence of high metal ion concentrations.

Copper Sulfate↗
PubMed1997

The independent and combined effects of aerobic exercise and dietary fish intake on serum lipids and glycemic control in NIDDM. A randomized controlled study.

OBJECTIVE: The triglyceride-lowering effects of omega-3 fats and HDL cholesterol-raising effects of exercise may be appropriate management for dyslipidemia in NIDDM. However, fish oil may impair glycemic control in NIDDM. The present study examined the effects of moderate aerobic exercise and the incorporation of fish into a low-fat (30% total energy) diet on serum lipids and glycemic control in dyslipidemic NIDDM patients. RESEARCH DESIGN AND METHODS: In a controlled, 8-week intervention, 55 sedentary NIDDM subjects with serum triglycerides > 1.8 mmol/l and/or HDL cholesterol < 1.0 mmol/l were randomly assigned to a low-fat diet (30% daily energy intake) with or without one fish meal daily (3.6 g omega-3/day) and further randomized to a moderate (55-65% VO2max) or light (heart rate < 100 bpm) exercise program. An oral glucose tolerance test (75 g), fasting serum glucose, insulin, lipids, and GHb were measured before and after intervention. Self-monitoring of blood glucose was performed throughout. RESULTS: In the 49 subjects who completed the study, moderate exercise improved aerobic fitness (VO2max) by 12% (from 1.87 to 2.07 l/min, P = 0.0001). Fish consumption reduced triglycerides (0.80 mmol/l, P = 0.03) and HDL3 cholesterol (0.05 mmol/l, P = 0.02) and increased HDL2 cholesterol (0.06 mmol/l, P = 0.01). After adjustment for age, sex, and changes in body weight, fish diets were associated with increases in GHb (0.50%, P = 0.05) and self-monitored glucose (0.57 mmol/l, P = 0.0002), which were prevented by moderate exercise. CONCLUSIONS: A reduced fat diet incorporating one daily fish meal reduces serum triglycerides and increases HDL2 cholesterol in dyslipidemic NIDDM patients. Associated deterioration in glycemic control can be prevented by a concomitant program of moderate exercise.

Adult↗
PubMed1996

Low serum cholesterol and the risk of cerebral haemorrhage.

In addressing the potential for any hazards associated with lowering serum cholesterol, a recent meta-analysis by Law and colleagues (Br Med J 1994;308:373) concluded that that there was no evidence that a low or reduced serum cholesterol concentration increases mortality from any cause other than haemorrhagic stroke. In this review, the evidence for this unexpected association will be addressed, and possible mechanisms discussed. Overall implications of the phenomenon, particularly for the hypertensive patient, will be addressed in the context of the anticipated consequences of lipid-lowering therapy for all stroke, haemorrhagic and non-haemorrhagic, as well as ischaemic heart disease (IHD).

Cerebral Hemorrhage↗
PubMed1996

Phenolic content of various beverages determines the extent of inhibition of human serum and low-density lipoprotein oxidation in vitro: identification and mechanism of action of some cinnamic acid derivatives from red wine.

1. An antioxidant effect of phenolic substances in red wine to reduce oxidizability of low-density lipoprotein has been proposed as the basis for a relatively lower incidence of coronary disease in populations with high red wine intake. We have now investigated the possible antioxidant effects of various beverages, including red wines, white wines, beers and red grape juices (diluted 1:500), on metal ion-dependent (copper) and -independent (aqueous peroxyl radicals) oxidation of isolated human low-density lipoprotein. We also tested the effects of these beverages on copper-initiated oxidation of lipoproteins in serum. 2. The higher the polyphenolic content of a beverage, the greater was its antioxidative effect measured as change in lag time in the different oxidation systems. Upon stripping the polyphenolics from the drinks, the lag times returned to control levels in isolated low-density lipoprotein; however, the low concentrations of phenolics remaining after stripping had a lesser but still significant effect on oxidation of lipoproteins in serum. The inhibitory effect of these phenolics appeared to be more pronounced for metal ion (copper)-induced oxidation than for those induced by aqueous peroxyl radicals, suggesting that both copper-binding and free radical-trapping activities may be involved. A mixture of the carboxylic acids representative of those present in red wine exhibited no significant effect on lag time of metal ion-dependent and -independent low-density lipoprotein oxidations. Ethanol, at concentrations of 0.1-0.5%, had no effect on either copper-induced or aqueous peroxyl radical oxidations. 3. Extracts of acid-hydrolysed red wine were separated by thin-layer chromatography and the most active antioxidant fractions identified. GC-MS and HPLC analysis of these fractions resulted in the identification of several cinnamic acid derivatives, such as coumaric acid, caffeic acid and protocatechuic acid. Dose-response studies using the pure compounds indicated that caffeic acid was the most active antioxidant with an IC50 < 1 mumol/l for copper-initiated low-density lipoprotein oxidation. Caffeic acid (1 mumol/l) significantly inhibited lipid hydroperoxide formation while sparing alpha-tocopherol consumption. Caffeic acid at the same concentration also inhibits aqueous peroxyl radical-induced oxidation of low-density lipoprotein, sparing alpha-tocopherol. There was no evidence of caffeic acid preventing the binding of copper to low-density lipoprotein. 4. We conclude that phenolics in both alcoholic and non-alcoholic beverages can give dose-dependent protection against oxidation of low-density lipoprotein. Caffeic acid and protocatechuic acid are two compounds likely to contribute to these effects. These findings may be relevant to the putative cardiovascular-protective effects of high phenolic content alcoholic beverages such as red wine; however, the widespread occurrence of antioxidants such as caffeic acid in fruits and vegetables suggests that these protective principles are not limited to red wine.

Adult↗
PubMed1996

Exercise and weight control in sedentary overweight men: effects on clinic and ambulatory blood pressure.

OBJECTIVE: To examine whether restriction of caloric intake and exercise of vigorous intensity can independently and additively influence clinic and ambulatory blood pressures in sedentary overweight men. DESIGN: Sixty subjects aged 20-50 years were randomly allocated either to continue their normal caloric intake or to restrict it by 4186-6279 kl/day, with 15% provided by protein, 30% by fat and 55% by carbohydrate, for 16 weeks. Within each of these groups subjects were further randomly allocated either to a control light intensity programme of exercise or to a vigorous intensity programme of exercise for 30 min three times a week. The light exercise group performed stationary cycling against no resistance, flexibility exercises and slow walking. The vigorous intensity group cycled on an ergometer at 60-70% of maximum their workload. RESULTS: Fifty-one subjects completed the study. Their maximal oxygen uptake was increased by approximately 24% with vigorous exercise but did not change with light exercise. Caloric intake restriction led to a significant loss of body mass of 9.5 kg (95% confidence interval 7.6-11.3), whereas vigorous exercise had no effect. Restriction of caloric intake reduced supine clinic systolic and diastolic blood pressures significantly by 5.6 (2.3-8.9) and 2.4 mmHg (0.4-4.2), respectively. Relative to the control light exercise group, exercise of vigorous intensity exercise had no significant effect on clinic blood pressure. In contrast, time series analysis revealed that both caloric intake restriction and vigorous exercise were associated with lower daytime ambulatory systolic blood pressure, the reduction in systolic blood pressure being sustained throughout the 24 h period when vigorous exercise and caloric intake restriction were combined. CONCLUSION: Compared with the effects of caloric intake restriction, the effects of a vigorous exercise programme on blood pressure are inconsistent, there being no influence on clinic blood pressure but a reduction in daytime ambulatory blood pressure. However, when combined with caloric intake restriction, regular vigorous exercise exhibits a synergistic effect in reducing ambulatory blood pressure throughout a 24 h period.

Adult↗
PubMed1996

Oxidative susceptibility of low-density lipoproteins--influence of regular alcohol use.

In population studies, a low-to-moderate intake of alcohol has been consistently linked to a lower risk of coronary artery disease. The recent suggestion that alcoholic beverages may be conferring this decrease in risk because they contain antioxidant phenolic compounds that reduce the oxidizability of low-density lipoprotein (LDL) has to be reconciled with the possible counteracting influence of a pro-oxidant effect of alcohol. In a controlled crossover study, we have now measured the oxidizability of LDL in 27 regular beer drinkers during consecutive 4-week periods, wherein they consumed a high versus low alcohol beer (4.9 vs. 0.9% alcohol v/v, respectively), with the two beers being similar in phenolic content. This resulted in a decrease in alcohol consumption by approximately 80% (408 +/- 25 ml/week vs. 75 +/- 11 ml/week). During the low alcohol period, there was no change in LDL vitamin E or its cholesterol or protein content. Analysis of LDL oxidation kinetics revealed an increase in oxidizability during the high alcohol phase. This was despite a decrease in arachidonic acid content of LDL and a corresponding increase in palmitic acid during high alcohol intake--a change in fatty acid composition that has the potential to favor a decrease in oxidizability. Our results suggest that alcohol ingestion increases LDL oxidation, despite reducing the polyunsaturated fatty acid composition. The overall effect of alcoholic beverages on LDL oxidation may be a balance between the pro-oxidant and antioxidant activity of its various constituents. The predominant pro-oxidant effect demonstrated in these beer drinkers, although not relevant to any potential decrease in coronary artery disease, may be important in the pathogenesis of alcohol-related disease in other organ systems.

Adult↗