Richard M. Carroll

Association among serum lipid and lipoprotein concentrations and physical activity, physical fitness, and body composition in young children

OBJECTIVE To examine the relationships among indicators of physical activity, physical fitness, and body composition with serum lipid and lipoprotein levels in young children. DESIGN Cross-sectional and 1-year prospective cohort. SETTING Studies of Child Activity and Nutrition (SCAN) program, Galveston, Tex. SUBJECTS One hundred twenty-three 4- or 5-year-old black, Hispanic (of Mexican origin), and white children. MEASUREMENTS Body composition, resting heart rate, and cardiovascular fitness variables and serum lipid and lipoprotein levels were measured at age 3 or 4 years (study year 1) and at age 4 or 5 years (study year 2), and day-long heart rate was measured and the Childrens Activity Rating Scale was administered between study years 1 and 2. RESULTS Year-1 waist/hip ratios were inversely correlated with total serum cholesterol (TSC) and low-density lipoprotein (LDL) levels. Mean activity level was inversely correlated with waist/hip ratios. On the basis of multiple regression analysis, the sum of seven skin-fold measurements, height, and gender explained 15.4% of the variation in triglyceride levels. The sum of seven skin-fold measurements was inversely correlated with the high-density lipoprotein (HDL) level. Resting heart rate, waist/hip ratio, and the slope of the exercise heart rate during fitness testing explained 19.5% of the variation in the concentration of an HDL subclass, HDL2. These childrens levels of physical activity were associated with higher fitness levels. Year-1 waist/hip ratios and year-2 sum of seven skin-fold measurements were positively correlated with the LDL/HDL and TSC/HDL ratios. CONCLUSION Higher levels of cardiovascular fitness and lower levels of fatness were associated with more favorable serum lipid and lipoprotein levels in these young children. Physical activity appeared to have an indirect association with serum lipid and lipoprotein values through its relationship with higher fitness levels and lower levels of fatness.

Eicosanoid synthesis in 7,12-dimethylbenz(a)anthracene-induced mammary carcinomas in Sprague-Dawley rats fed primrose oil, menhaden oil or corn oil diet

The comparative effects of high-fat diets (20%, w/w) on eicosanoid synthesis during mammary tumor promotion in 7,12-dimethylbenz(a)anthracene (DMBA)-induced rats were studied using diets containing 20% primrose oil (PO), 20% menhaden oil (MO) or 20% corn oil (CO). Sprague-Dawley rats fed the PO or MO diet had 21% or 24% fewer adenocarcinomas, respectively, than rats fed the CO diet. Histologically (i.e., mitotic figures, inflammatory cell infiltration and necrosis), the CO-fed rats exhibited the highest frequency of changes within tumors. Plasma fatty acid composition was significantly altered by diet, reflecting the composition of the oils which were being fed. Only the plasma of PO-fed rats contained detectable levels of gamma-linolenic acid (GLA). Arachidonic acid (AA) levels were significantly higher (p<0.05) in PO-fed than in CO- or MO-fed rats. MO-fed rats had significantly higher levels of plasma palmitic acid, while palmitoleic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were detected only in MO-fed rats. As expected, linoleic acid (LA) and AA levels were lower (p<0.05) in the MO-fed rats than in PO- or CO-fed groups. The plasma of the CO-fed rats contained significantly higher levels of oleic acid. Eicosanoid synthesis in mammary carcinomas of rats fed the 20%-fat diets was 2–10 times higher than in mammary fat pads of control rats. The synthesis of PGE1 and LTB4 was significantly (p<0.05) higher in PO-fed rats than in CO-fed or MO-fed rats, although PGE values were significantly (p<0.05) higher in CO-fed rats than in Mo or PO groups. The synthesis of eicosanoids in both mammary fat pads and mammary carcinomas of MO-fed rats was lower (p<0.05) than in tissues of rats fed either CO or PO diets due to less AA precursor being fed and/or to competition between n−6 and n−3 fatty acids for cyclooxygenase and lipoxygenase. The ratios of monoenoic to dienoic eicosanoids in both mammary fat pads and mammary carcinomas were higher in the PO group than in the MO or CO groups. These results suggest that inclusion of GLA (PO feeding) or EPA and DHA (MO feeding) in the diet may decrease malignancy by altering eicosanoid profiles.

Plasma lipoproteins in cortical versus lacunar infarction.

We investigated the relation of plasma lipids to the risk for ischemic stroke by comparing clinical and biochemical characteristics of survivors of cortical (n = 48) and lacunar (n = 36) brain infarction. By analysis of variance, no differences were observed in the concentrations of total cholesterol, triglycerides, low density lipoprotein cholesterol, very low density lipoprotein cholesterol, or apoproteins A1 and B. Patients with lacunar infarction, however, had higher concentrations of high density lipoprotein (HDL)-cholesterol than patients with cortical stroke. This HDL-cholesterol difference was due primarily to a strikingly low HDL-cholesterol content in white patients with cortical stroke. These data suggest that previously demonstrated differences in HDL-cholesterol concentrations between patients with ischemic stroke and control subjects without stroke may apply to patients with cortical but not lacunar infarction. Separation of cerebral infarction into subtypes based on mechanism may help clarify lipid-related risk factors in cerebrovascular disease.

Effects of dietary primrose oil on mammary tumorigenesis induced by 7,12-dimethylbenz(a) anthracene

The mammary tumor-promoting effect of a high-fat diet containing 20% evening primrose oil (PO) was compared to that of a 20% corn oil (CO) diet. Mammary tumors were induced in female Sprague-Dawley rats using 10 mg (Study 1) and 5 mg (Study 2) 7,12-dimethylbenz(a)anthracene (DMBA). The 10 mg dose of DMBA gave a total mammary tumor incidence of 47% in rats fed the PO diet and 80% for those fed the CO diet. When only adenocarcinomas were counted, the malignant mammary tumor incidences were 41% in rats fed the PO diet and 73% in rats fed the CO diet. In a second study using 5 mg DMBA to induce mammary tumors, total tumor incidences were 50% for PO-fed rats and 63% for those receiving a CO diet. Again, when only adenocarcinomas were counted, tumor incidences were 27% for PO- and 63% for CO-dieted rats. Analysis of plasma fatty acid profiles indicated that animals fed a 20% PO diet showed significant increases in 18∶3 and 20∶4 fatty acids and significant decreases in 16∶0 and 18∶1 compared to animals fed a 20% CO diet. These results indicate that the mammary tumor promoting effect of a diet containing 20% fat can be diminished by substituting PO for CO. Moreover, the promoting effect on mammary cancer by a high-fat diet could be depressed by feeding a source of γ-linolenic acid (GLA).

A lipogenic effect in intact male hamsters infected with plerocercoids of the tapeworm, Spirometra mansonoides.

Plerocercoids of the tapeworm, Spirometra mansonoides, produce a potent growth stimulating substance which is active in several species of mammals. While most of the actions of the plerocercoid growth factor (PGF) are similar to those of growth hormone (GH), lipid metabolism is one area where their actions are not alike. This report demonstrates that plerocercoid infection not only stimulates growth of intact male hamsters but is lipogenic as well. The lipogenic effects of plerocercoid infection were demonstrated by increases in epididymal fat pad weights, serum triglycerides, cholesterol, and total lipid. The livers of the plerocercoid-infected hamsters also had more cholesterol and more lipid phosphorus than controls. Incorporation studies using [2-14C]acetate showed that infected hamsters incorporated significantly higher levels of the radionuclide in their livers and serum after 1 hr than the controls. The lipogenic effect of plerocercoid infection is distinctly unlike the reported lipolytic action of GH and the lack of any stimulation of [2-14C]acetate incorporation into the epididymal fat pads is unlike the reported acute actions of insulin as well.

Isolation of a New, Pink, Obligately Thermophilic, Gram- Negative Bacterium (K-2 Isolate)

A pink, obligately themophilic (60 C), gram-negative, nonmotile, nonsporeforming, rod-shaped bacterium with a deoxyribonucleic acid base ratio of 64 to 65 mol% guanine plus cytosine has been repeatedly isolated from slightly alkaline, man-made and natural thermal aquatic environments. This bacterium (K-2 isolate) does not appear to have been described previously and it has been deposited with the American Type Culture Collection as an unidentified bacterium with the accession no. 27599.

Effect of Selenium Supplementation on Selenium Balance in the Dependent Elderly

Although trace minerals are necessary constituents of enzymes, dietary requirements of these nutrients for the elderly are unknown. This study measured selenium balance in six dependent elderly men before and after five weeks daily administration of 200 μg organically-bound selenium; dietary selenium intake averaged 62.1 ± 7 μg/day during both study periods. Selenium status was assessed not only chemically but also biologically as red cell and platelet glutathione peroxidase activities. Plasma selenium averaged 8.8 ± 0.8 μg% (normal: 10 ± 2 μg%) when intake derived from dietary sources alone and increased during medicinal supplementation to an average of 12.8 ± 1.9 μg%. The rise in plasma selenium was not associated with an increase in red cell or platelet glutathione peroxidase activity. The effect of selenium supplementation on in vivo platelet aggreg-ability was studied by measuring plasma levels of β-thrombo-globulin and platelet factor 4, two proteins secreted concomitant with aggregation, β-thromboglobulin diminished 7,5 ± 11.0 ng/ml and platelet factor 7.6 ± 11.0 ng/ml during selenium supplementation despite no change in platelet glutathione peroxidase activity. These data support the concept that selenium nutritional status should be assessed not only by blood selenium content but also by selenium-dependent enzyme activity or selenium-dependent biologic effect.

Comparison of the effects of the growth factor produced by Spirometra mansonoides and growth hormone in diabetic-hypophysectomized rats: lipid composition.

The effects of bovine growth hormone and the growth factor produced by plerocercoid larvae of the tapeworm, Spirometra mansonoides, on body growth and lipid composition in diabetic-hypophysectomized rats were compared. The diabetic-hypophysectomized control rats gradually lost weight throughout the experiment but both growth hormone and plerocercoids stimulated marked weight gains. Growth hormone treatment resulted in a loss of depot fat from the epididymal fat pads and caused a reduction of liver and serum cholesterol concentrations but had no effect on triglyceride concentrations of either liver or serum. However, plerocercoid infection resulted in increased weights of the epididymal fat pads and increased liver and serum triglyceride concentrations. Serum cholesterol was slightly increased but liver cholesterol was decreased in the plerocercoid-infected rats. Therefore, in the absence of pituitary hormones and insulin, these growth factors had similar effects on body growth but distinctly different effects on lipid metabolism.

Lipids and Lipoproteins in a Triethnic Sample of 5- or 6-Year-Old Type A or Type B Children

The Type A behavior pattern (TABP) has been proposed as a risk factor for coronary heart disease (CHD). Several studies have indicated an association between Type A behavior and serum cholesterol levels. If the effects of TABP are mediated by conventional CHD risk factors, evidence for a causal relationship between TABP and CHD would be strengthened if associations were detected among the young. This paper addresses the following: (1) Do levels of serum lipids and lipoproteins among young children vary by ethnicity, gender, or TABP? (2) Can obtained differences be accounted for by possible confounding factors, such as SES or body composition? ANCOVA revealed no significant ethnic, gender, or TABP effects for total serum cholesterol or HDLc. Analyses of LDLc and triglycerides disclosed significant main effects for gender and for ethnicity. A Competition subscale by ethnicity interaction was the only effect to approach statistical significance for TABP. The strongest findings were a replication of differences in lipid and lipoprotein risk factors by ethnicity.

Insulin-like effects of fatty acid synthesis in liver of hamsters infected with plerocercoids of the tapeworm, Spirometra mansonoides.

Elevated serum lipids are associated with infections of laboratory rodents with plerocercoids of Spirometra mansonoides. The effect of infection with these larval tapeworms on triglyceride degradation and hepatic de novo fatty acid synthesis was investigated in Syrian hamsters. Serum lipoprotein electrophoresis revealed a consistent elevation in very low density lipoproteins in the infected animals. Lipoprotein lipase activity was enhanced in the infected animals. After seven days of plerocercoid infection the activity of acetyl-CoA carboxylase (E.C. 6.4.1.2) was significantly elevated after 6, 12 and 18 hours of fasting. Fatty acid synthetase was significantly increased after 0, 6, 12, 18 and 24 hours of fasting. Therefore, a chronic insulin-like activity on lipid metabolism of hamsters is associated with plerocercoid infection.