RESUMO
In this study, we analyzed the effect of aerobic exercise training (AET) and of a single bout of exercise on plasma oxidative stress and on antioxidant defenses in type 2 diabetes mellitus (DM) and in healthy control subjects (C). DM and C did not differ regarding triglycerides, high-density lipoprotein cholesterol (HDL-c), insulin, and HOMA index at baseline and after AET. To measure the lag time for low-density lipoprotein (LDL) oxidation (LAG) and the maximal rate of conjugated diene formation (MCD), participants' plasma HDL(2) and HDL(3) were incubated with LDL from pooled healthy donors' plasma. In the presence of HDL(3), both LAG and MCD were similar in C and DM, but only in DM did AET improve LAG and reduce MCD. In the presence of HDL(2), the lower baseline LAG in DM equaled C after AET. MCD was unchanged in DM after AET, but was lower than C only after AET. Furthermore, after AET plasma thiobarbituric acid-reactive substances were reduced only in DM subjects. Despite not modifying the total plasma antioxidant status and serum paraoxonase-1 activity in both groups, AET lowered the plasma lipid peroxides, corrected the HDL(2), and improved the HDL(3) antioxidant efficiency in DM independent of the changes in blood glucose, insulin, and plasma HDL concentration and composition.
Assuntos
Antioxidantes/farmacologia , HDL-Colesterol/farmacologia , Diabetes Mellitus Tipo 2/fisiopatologia , Exercício Físico/fisiologia , Peroxidação de Lipídeos/fisiologia , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estresse OxidativoRESUMO
BACKGROUND: Previous studies showed divergent results concerning the influence of medium-chain triacylglycerol (MCT) on lipoprotein metabolism. OBJECTIVE: The objective of this study was to compare the effects of MCT and corn oil on plasma lipids in primary hypertriglyceridemic patients. DESIGN: Ten subjects ate different proportions of corn oil and MCT for 12 wk. The subjects first ate a low-fat diet for 2 wk and during the next 4 wk, corn oil was added as the sole source of fat. Thereafter, for 2-wk periods, the subjects were sequentially fed corn oil and MCT mixed in the following proportions: 3:1, 1:1, and 0:1. Fasting plasma total cholesterol, triacylglycerol, and HDL-cholesterol concentrations were measured at the end of each period. At the end of the 100%-corn oil and of the 100%-MCT periods, subjects were fed a test meal containing the respective oil (40 g fat/m(2) body surface area) and total cholesterol and triacylglycerols were measured at 2-h intervals over 8 h; fasting lipoprotein composition was also measured. RESULTS: Compared with corn oil, MCT was associated with a higher mean (+/-SD) fasting total cholesterol concentration (6.39 +/- 1.14 compared with 5.51 +/- 0.98 mmol/L, respectively; P < 0. 05); non-HDL-cholesterol concentrations were also higher with MCT (5. 36 +/- 1.11 mmol/L) than with corn oil (4.51 +/- 0.92 mmol/L; P < 0. 005). In response to the liquid test meal, plasma total cholesterol did not change with either diet but triacylglycerols increased with the 100%-corn oil diet. CONCLUSIONS: MCT prevents the risk of pancreatitis due to postprandial hypertriglyceridemia but has the inconvenience of raising total cholesterol concentrations in primary hypertriglyceridemic subjects.
Assuntos
Gorduras na Dieta/administração & dosagem , Hipercolesterolemia/etiologia , Hipertrigliceridemia/sangue , Triglicerídeos/administração & dosagem , Triglicerídeos/sangue , Adulto , HDL-Colesterol/sangue , Óleo de Milho/administração & dosagem , Ingestão de Energia , Jejum , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
In healthy subjects with a normal body mass index, total plasma cholesterol, low-density lipoprotein (LDL) cholesterol, and apoB lipoprotein levels are higher in older individuals (n = 34) than in younger subjects (n = 43). The two groups studied ranged in age from 60 to 93 years and from 17 to 30 years, respectively. The cholesterol synthesis rates of peripheral mononuclear blood cells from 14C-acetate, total and unesterified cholesterol concentrations in freshly isolated cells, and the rates of uptake of pooled donor LDL, labeled with 125I- or 14C-cholesteryl oleoyl ether, by cells derepressed in a lipoprotein-free medium were similar in both experimental groups. Thus, the rise of LDL cholesterol with age would seem to be likely secondary to the higher rate of very-low-density lipoprotein production, as shown by other investigators.