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P D Wood

Publications and source records attributed to P D Wood.

At least 19 recordsLinked to original sources
PubMed1998

Effects of diet and exercise in men and postmenopausal women with low levels of HDL cholesterol and high levels of LDL cholesterol.

BACKGROUND: Guidelines established by the National Cholesterol Education Program (NCEP) promote exercise and weight loss for the treatment of abnormal lipoprotein levels. Little is known, however, about the effects of exercise or the NCEP diet, which is moderately low in fat and cholesterol, in persons with lipoprotein levels that place them at high risk for coronary heart disease. METHODS: We studied plasma lipoprotein levels in 180 postmenopausal women, 45 through 64 years of age, and 197 men, 30 through 64 years of age, who had low high-density lipoprotein (HDL) cholesterol levels (< or =59 mg per deciliter in women and < or =44 mg per deciliter in men) and moderately elevated levels of low-density lipoprotein (LDL) cholesterol (>125 mg per deciliter but <210 mg per deciliter in women and >125 mg per deciliter but <190 mg per deciliter in men). The subjects were randomly assigned to aerobic exercise, the NCEP Step 2 diet, or diet plus exercise, or to a control group, which received no intervention. RESULTS: Dietary intake of fat and cholesterol decreased during the one-year study (P<0.001), as did body weight, in women and men in either the diet group or the diet-plus-exercise group, as compared with the controls (P<0.001) and the exercise group (P<0.05), in which dietary intake and body weight were unchanged. Changes in HDL cholesterol and triglyceride levels and the ratio of total to HDL cholesterol did not differ significantly among the treatment groups, for subjects of either sex. The serum level of LDL cholesterol was significantly reduced among women (a decrease of 14.5+/-22.2 mg per deciliter) and men (a decrease of 20.0+/-17.3 mg per deciliter) in the diet-plus-exercise group, as compared with the control group (women had a decrease of 2.5+/-16.6 mg per deciliter, P<0.05; men had a decrease of 4.6+/-21.1 mg per deciliter, P<0.001). The reduction in LDL cholesterol in men in the diet-plus-exercise group was also significant as compared with that among the men in the exercise group (3.6+/-18.8 mg per deciliter, P<0.001). In contrast, changes in LDL cholesterol levels were not significant among the women (a decrease of 7.3+/-18.9 mg per deciliter) or the men (10.8+/-18.8 mg per deciliter) in the diet group, as compared with the controls. CONCLUSIONS: The NCEP Step 2 diet failed to lower LDL cholesterol levels in men or women with high-risk lipoprotein levels who did not engage in aerobic exercise. This finding highlights the importance of physical activity in the treatment of elevated LDL cholesterol levels.

Adult↗
PubMed1998

Effect of postmenopausal hormone therapy on lipoprotein(a) concentration. PEPI Investigators. Postmenopausal Estrogen/Progestin Interventions.

BACKGROUND: Postmenopausal hormone therapy has been reported to decrease levels of lipoprotein (Lp)(a) in cross-sectional studies and small or short-term longitudinal studies. We report findings from a large, prospective, placebo-controlled clinical trial that allows a broad characterization of these effects for four regimens of hormone therapy. METHODS AND RESULT: The Postmenopausal Estrogen/Progestin Interventions study was a 3-year, placebo-controlled, randomized clinical trial to assess the effect of hormone regimens on cardiovascular disease risk factors in postmenopausal women 45 to 65 years of age. The active regimens were conjugated equine estrogens therapy at 0.625 mg daily, alone or in combination with each of three regimens of progestational agents: medroxyprogesterone acetate (MPA) at 2.5 mg daily (ie, continuous MPA), MPA at 10 mg days 1 to 12 (ie, cyclical MPA), and micronized progesterone at 200 mg days 1 to 12. Plasma levels of Lp(a) were measured at baseline (n = 366), 12 months (n = 354), and 36 months (n = 342). Assignment to hormone therapy resulted in a 17% to 23% average drop in Lp(a) concentrations relative to placebo (P<.0001), which was maintained across 3 years of follow-up. No significant differences were observed among the four active arms. Changes in Lp(a) associated with hormone therapy were positively correlated with changes in LDL cholesterol, total cholesterol, apolipoprotein B, and fibrinogen levels and were similar across subgroups defined by age, weight, ethnicity, and prior hormone use. CONCLUSIONS: Postmenopausal estrogen therapy, with or without concomitant progestin regimens, produces consistent and sustained reductions in plasma Lp(a) concentrations.

Aged↗
PubMed1997

PCB concentrations of eggs and chorioallantoic membranes of loggerhead sea turtles (Caretta caretta) from the Cape Romain National Wildlife Refuge.

PCBs were found in eggs and chorioallantoic membranes (CAMs) of loggerhead sea turtles (Caretta caretta). Total PCB concentrations in CAMs were larger than concentrations in eggs. Total PCB concentrations in egg and CAM tissues were highly correlated (r2 = 0.782; p = 0.0001). Sums of PCB congeners within homologue groups were also correlated in the two tissues. Data from these turtle eggs indicate 1) PCB concentrations in CAMs represent PCB concentrations in whole eggs and 2) CAMs can be collected in a nonlethal manner to determine PCB concentrations in sea turtle hatchlings.

Allantoin↗
PubMed1996

Exercise and lipids.

We have learned a substantial amount about the influence of exercise on plasma lipoprotein status in women. However, studies on women still lag behind those on men, and much detail remains to be filled in. For instance, the fluctuating sex hormone levels in women during the month produce substantial variations in plasma lipoprotein levels, which needs further investigation and must be considered in studies on premenopausal women. Meanwhile, it seems clear that athletes engaging in aerobic sports at a high level are particularly favored with respect to their low overall risk of coronary heart disease and, in particular, to their highly favorable plasma lipoprotein pattern.

Exercise↗
PubMed1994

Effects of cessation of caffeinated-coffee consumption on ambulatory and resting blood pressure in men.

Coffee consumption has been weakly linked to high blood pressure (BP). The hypothesis that cessation of caffeinated-coffee consumption lowers ambulatory BP was tested in men in a randomized trial. One hundred eighty-six middle-aged, normotensive, male, habitual caffeinated-coffee consumers were recruited. Of these subjects, 150 had sufficiently complete, ambulatory BP measurements for analysis. After 2 months of standard caffeinated-coffee consumption, subjects were randomized to consume an equal amount of the same standard caffeinated coffee or a standard decaffeinated coffee, or to discontinue coffee consumption for 2 months. Diet composition, body weight and exercise did not change. Resting BP and heart rate were not different between the groups before and after intervention. In comparison with the continued caffeinated-coffee group (control), the decaffeinated-coffee group revealed significant reductions in mean ambulatory systolic BP during the morning (-4.0 +/- 11 mm Hg; p = 0.014), afternoon (-5.3 +/- 10 mm Hg; p = 0.001) and evening (-3.2 +/- 10 mm Hg; p = 0.003) hours, reductions in mean ambulatory diastolic BP during the afternoon (-1.8 +/- 10 mm Hg; p = 0.063) and evening (-1.8 +/- 10 mm Hg; p = 0.059) hours and no change in ambulatory heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effects of low-fat diet, calorie restriction, and running on lipoprotein subfraction concentrations in moderately overweight men.

We studied the effects of exercise (primarily running), calorie restriction (dieting), and a low-fat, high-carbohydrate diet on changes in lipoprotein subfractions in moderately overweight men in a randomized controlled clinical trial. After 1 year, complete data were obtained for 39 men assigned to lose weight through dieting without exercise, 37 men assigned to lose weight through dieting with exercise (primarily running), and 40 nondieting sedentary controls. We instructed both diet groups to consume no more than 30% total fat, 10% saturated fat, and 300 mg/d of cholesterol, and at least 55% carbohydrates, and the controls were instructed to maintain their usual food choices. Analytic ultracentrifugation was used to measure changes in plasma lipoprotein mass concentrations. In addition, the absorbance of protein-stained polyacrylamide gradient gels was used as an index of concentrations for five high-density lipoprotein (HDL) subclasses that have been identified by their particle sizes, ie, HDL3c (7.2 to 7.8 nm), HDL3b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12 nm). Relative to controls, weight decreased significantly in men who dieted with exercise (net difference +/- SE, -3.3 +/- 0.4 kg/m2) and in men who dieted without exercise (-2.0 +/- 0.4 kg/m2). Dieting with exercise significantly decreased very-low-density lipoprotein (VLDL)-mass concentrations and significantly increased plasma HDL2-mass, HDL3a, HDL2a, and HDL2b relative to both control and dieting without exercise. There were no significant changes in lipoprotein mass and HDL protein for dieters who did not run.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The effects of weight loss by exercise or by dieting on plasma high-density lipoprotein (HDL) levels in men with low, intermediate, and normal-to-high HDL at baseline.

To assess whether baseline plasma high-density lipoprotein (HDL) cholesterol levels affected the HDL response to weight loss, we examined lipoprotein changes in overweight men aged 30 to 59 years who were randomized to lose weight by exercise training (primarily running, n = 46) or by caloric restriction (ie, dieting, n = 42) or to remain sedentary, nondieting controls (n = 42) in a 1-year study. In exercisers, absolute increases in HDL (mg/dL) were greatest in men with normal-to-high baseline HDL and least in men with low baseline HDL. Specifically, when divided into groups of low (< or = 37 mg/dL), intermediate (38 to 47 mg/dL), and normal-to-high HDL cholesterol (> or = 48 mg/dL) at baseline, the exercisers increased HDL cholesterol by 2.3 +/- 1.9, 4.9 +/- 1.1, and 7.0 +/- 1.3 mg/dL, respectively; HDL2 cholesterol by 0.8 +/- 1.6, 2.3 +/- 1.2, and 5.1 +/- 1.3 mg/dL; and HDL2 mass by 2.8 +/- 5.1, 9.5 +/- 8.9, and 31.7 +/- 11.0 mg/dL. Relative increases in HDL cholesterol were more similar in the low (7.1% +/- 6.1%), intermediate (12.4% +/- 3.9%), and normal-to-high men (13.2% +/- 4.0%). Regression analyses were performed to assess whether baseline HDL cholesterol was related to the amount of absolute HDL change per unit of weight loss. In exercisers, the increase in HDL3 cholesterol concentrations was significantly greater in men with low HDL than in those with normal-to-high HDL at entry (2.0 +/- 0.8 v 0.2 +/- 0.8 mg/dL per kg/m2 lost).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Curcumin-derived transients: a pulsed laser and pulse radiolysis study.

In this paper we report a time-resolved investigation of transients derived from curcumin, which may be intimately involved in the processes leading to its biological activity. Fluorescence and triplet quantum yields are respectively 0.06 and 0.11. The high percentage of internal conversion is proposed to proceed via H-transfer within the thermodynamically favored enol structure of what is formally a 1,3-diketone. The triplet energy (191 +/- 2 kJ mol-1), natural lifetime (1.5 microseconds) and self-quenching rate constant (5.0 x 10(8) L mol-1 s-1) have been determined. Oxygen quenching of the triplet leads to the production of singlet oxygen with unit efficiency. Curcumin quenches the latter species very inefficiently (2.5 x 10(5) L mol-1 s-1). The curcumin radical has been produced via three mechanistically distinct methods. This species is unreactive toward oxygen but is repaired by vitamins C and E and anthralin.

Curcumin↗
PubMed1994

Physical activity, diet, and health: independent and interactive effects.

Much work on the relationship of exercise level to cardiovascular risk factors has been stimulated by the pioneering epidemiological studies of Dr. Ralph Paffenbarger. At Stanford we have conducted a series of studies since 1973, with the following major findings. Very active middle-aged men and women (compared with sedentary controls) have higher plasma lipoprotein concentrations of high-density lipoprotein (HDL) cholesterol, lower levels of very-low-density-lipoprotein (VLDL) cholesterol and triglyceride (TG), and often moderately lower levels of low-density lipoprotein (LDL) cholesterol. Lipoprotein subfractions are also different: higher levels of HDL2 and lower levels of "small" LDL in the active groups. Very active people are leaner and smoke less. All of these characteristics predict lower risk of coronary heart disease (CHD). A 1-yr trial of jogging in sedentary men suggested that 8-10 miles.wk-1 of running is required for significant HDL changes. Body fat loss correlated positively with distance run, with increase in HDL, and with increase in caloric intake. A 1-yr trial in overweight men showed that fat loss by dieting alone or by exercising alone results in similar elevation of HDL cholesterol. A 1-yr trial in sedentary, overweight men and women losing weight on a hypocaloric low-fat diet showed that addition of regular exercise increases weight loss, improves lipoprotein pattern, and further decreases 12-yr CHD risk.

Adult↗
PubMed1993

Impact of experimental manipulation of energy intake and expenditure on body composition.

There is persuasive evidence that much obesity is due to underexercising rather than overeating. In a series of randomized, controlled trials we found that sedentary men who take up jogging lose body fat in proportion to miles run, increase their energy intake, and improve their lipoprotein pattern. In a 1-year comparison of fat loss by dieting vs. fat loss by exercise without dieting, both methods were found to be effective in moderately overweight men, and both approaches raised plasma HDL cholesterol. We also demonstrated in overweight men and women losing weight on a prudent diet (low fat, low cholesterol) that adding exercise to energy restriction further increased loss of body fat and reduced waist-to-hip girth ratio, especially in men. Risk of coronary heart disease was also substantially further reduced by addition of exercise, in both sexes. These studies suggest that regular exercise is a valuable addition to dietary change for weight control and reduction of risk of chronic disease in people of all ages. In this article I shall describe studies done by our group in the past 10 years to investigate the effects of varying energy expenditures and varying caloric intakes on body composition, in particular body fat content. The intervention studies are of relatively long duration (1 or 2 years) and have been conducted in free-living men and women. Such long-term investigations are rare in children and adolescents. Although experience in adults cannot be translated directly to children, our findings may indicate profitable research directions for future obesity research in the young.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1992

Variations in oxidative susceptibility among six low density lipoprotein subfractions of differing density and particle size.

Oxidative modification of low density lipoproteins (LDL) has been implicated in the sequence of events leading to fatty streak formation in the arterial intima. Increased oxidative modifications of dense versus buoyant LDL particles could contribute to increased atherosclerosis associated with lipoprotein profiles enriched in small, dense LDL. In the present studies, we compared rates of copper-induced oxidative changes for six LDL subfractions ranging in density from 1.023 to 1.053 g/ml and mean particle diameter from 282 +/- 10 to 245 +/- 3. Rates of formation of thiobarbituric acid-reactive substances (TBARS), as indicated by the time required for half-maximal TBARS formation (T1/2max), decreased with increasing density and decreasing particle diameter to a minimum in fraction 5 (d = 1.046 g/ml, diameter = 250 +/- 5) (P = 0.007). In parallel studies using unfractionated LDL (d = 1.019-1.063 g/ml), T1/2max values were inversely correlated with the predominant LDL species diameter as determined by 2-16% gradient gel electrophoresis (P less than 0.05), consistent with the involvement of subclass composition in determining oxidative behavior. In separate experiments, subfraction differences in oxidation rates as assessed by TBARS formation were verified by the finding of similarly dispartate changes in fluorescence intensity and anionic electrophoretic mobility. T1/2max values were not related to LDL contents of alpha-tocopherol, beta-carotene, protein, triglycerides or phospholipids, but were significantly correlated with unesterified cholesterol content (r = 0.46; P less than 0.001) and were inversely associated with cholesteryl ester content (r = 0.28; P less than 0.05). The positive association of T1/2max with unesterified cholesterol suggests that this constituent may impart resistance to oxidative modification, possibly by altering properties of the surface monolayer where it resides.

Adult↗
PubMed1992

Effects of weight-loss by exercise and by diet on apolipoproteins A-I and A-II and the particle-size distribution of high-density lipoproteins in men.

We studied separately the effects of weight-loss by dieting or by running on apolipoprotein (apo) A-I, apo A-II, and high-density lipoprotein (HDL) subfractions in sedentary, moderately overweight men assigned at random into three groups: exercise without calorie restriction, calorie restriction without exercise, and control. The absorbance of protein-stained polyacrylamide gradient gels was used as an index of mass concentrations for five HDL subclasses that have been identified by their particle sizes: HDL3c (7.2 to 7.8 nm), HDL3b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12.9 nm). During the 1-year trial, the exercisers ran (mean +/- SD) 15.6 +/- 9.1 km/wk, and the dieters reported eating 340 +/- 71 fewer calories per day than at baseline. Total body weight and fat weight were both reduced significantly more in dieters (-7.2 +/- 4.1 and -6.2 +/- 4.1 kg, respectively) and in exercisers (-4.0 +/- 3.9 and -4.6 +/- 3.5 kg) than in controls (0.6 +/- 3.7 and -0.7 +/- 2.7 kg). As compared with mean changes in controls, exercisers and dieters each decreased HDL3b and increased HDL2b. Exercisers also significantly increased plasma apo A-I concentrations. Analysis of covariance was used to statistically adjust the mean lipoprotein changes for the effects of weight-loss. The adjustment eliminated the significant reductions in HDL3b and the significant increases in HDL2b in exercisers and dieters, and it eliminated the significant increase in apo A-I in exercisers. When adjusted, the dieters' mean changes in HDL2b had significantly decreased relative to those of both exercisers and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Associations of lipoproteins and apolipoproteins with gradient gel electrophoresis estimates of high density lipoprotein subfractions in men and women.

We examined the relations of gender and lipoproteins to subclasses of high density lipoproteins (HDLs) in a cross-sectional sample of moderately overweight men (n = 116) and women (n = 78). The absorbance of protein-stained polyacrylamide gradient gels was used as an index of mass concentrations of HDL at intervals of 0.01 nm across the entire HDL particle size range (7.2-12 nm). At least five HDL subclasses have been identified by their particle sizes: HDL3c (7.2-7.8 nm), HDL3b (7.8-8.2 nm), HDL3a (8.2-8.8 nm), HDL2a (8.8-9.7 nm), and HDL2b (9.7-12 nm). Men had significantly higher HDL3b and significantly lower HDL2a and HDL2b than did women. Correlations of HDL subclasses with concentrations of other lipoprotein variables were generally as strong for gradient gel electrophoresis as for analytical ultracentrifugation measurements of HDL particle distributions. In both sexes, high levels of HDL3b were associated with coronary heart disease risk factors, including high concentrations of triglycerides, apolipoprotein B, small low density lipoproteins, intermediate density lipoproteins, and very low density lipoproteins and low concentrations of HDL2 cholesterol and HDL2 mass. Plasma concentrations of HDL3 cholesterol were unrelated to protein-stained HDL3b levels. HDL3 cholesterol concentrations also did not exhibit the sex difference or the relations with lipoprotein concentrations that characterized HDL3b. Thus, low HDL3b levels may contribute in part to the low heart disease risk in men and women who have high HDL cholesterol. Measurements of HDL3 cholesterol may not identify clinically important relations involving HDL3b.

Adult↗
PubMed1991

The effects on plasma lipoproteins of a prudent weight-reducing diet, with or without exercise, in overweight men and women.

BACKGROUND: The National Cholesterol Education Program (NCEP) recommends a low-saturated-fat, low-cholesterol diet, with weight loss if indicated, to correct elevated plasma cholesterol levels. Weight loss accomplished by simple caloric restriction or increased exercise typically increases the level of high-density lipoprotein (HDL) cholesterol. Little is known about the effects on plasma lipoproteins of a hypocaloric NCEP diet with or without exercise in overweight people. METHODS: We tested the hypothesis that exercise (walking or jogging) will increase HDL cholesterol levels in moderately overweight, sedentary people who adopt a hypocaloric NCEP diet. We randomly assigned 132 men and 132 women 25 to 49 years old to one of three groups: control, hypocaloric NCEP diet, or hypocaloric NCEP diet with exercise. One hundred nineteen of the men and 112 of the women returned for testing after one year. RESULTS: After one year, the subjects in both intervention groups had reached or closely approached NCEP Step 1 dietary goals and reduced their mean body fat significantly (range of reduction in mean fat weight, 4.0 to 7.8 kg). Weight loss on the NCEP diet alone did not significantly change HDL cholesterol levels in either the men or the women as compared with the subjects in the control group. Plasma levels of HDL cholesterol increased significantly more in the men who exercised and dieted (mean [+/- SE] change, +13 +/- 3 percent) than in the men who only dieted (+2 +/- 3 percent, P less than 0.01) or the men who acted as controls (-4 +/- 2 percent, P less than 0.001). HDL cholesterol levels remained about the same in the women who exercised and dieted (+1 +/- 2 percent); they were higher than in the women who only dieted (-10 +/- 3 percent, P less than 0.01), but not higher than in the controls (-3 +/- 3 percent). CONCLUSIONS: Regular exercise in overweight men and women enhances the improvement in plasma lipoprotein levels that results from the adoption of a low-saturated-fat, low-cholesterol diet.

Adult↗