[Lipoprotein(a): its concentrations in children with insulin-dependent diabetes mellitus]. / Lipoproteína(a): concentraciones en niños con diabetes mellitus dependiente de la insulina.

BACKGROUND: Insulin-dependent diabetes mellitus (IDDM) is characterized by an increased risk of having cardiovascular diseases which have been associated to, among other factors, an increase in lipoprotein (a) [Lp(a)] levels. METHODS: With the aim of analyzing the relationship between Lp(a) plasma levels and the degree of metabolic control in infantile diabetes mellitus their levels have been evaluated in children with IDDM and correlated with the degree of metabolic control and the length of disease evolution. The study was performed in a sample of 41 children diagnosed with IDDM and ages ranging from 2 to 9 years, and 82 normolipemic healthy children corresponding to the same ages and an equal proportion by sex. Cholesterol and total triglycerides, HDL, LDL and VLDL cholesterol, apolipoproteins AI and B were determined in all. Fasting glycemia, glycohemoglobin, serum fructosamine and creatinine clearance were used as markers of metabolic disease control. RESULTS: No significant differences were observed in the Lp(a) values among sexes or age in the control group. Upon comparison of the Lp(a) values of the diabetic patients with the control group, no significant differences were observed. In the diabetic children, no differences were found between the Lp(a) values according to the glycohemoglobin values (X +/- SD g/l) (< 8% 0.16 +/- 0.13); (> or = 8% 0.21 +/- 0.26). The Lp(a) values were only increased in diabetic children with more than 5 years of evolution (control: 0.12 +/- 0.14, IDDM < or = 5 years; 0.16 +/- 0.16 and IDDM > 5 years: 0.34 +/- 0.31 [p < 0.01]). CONCLUSIONS: The plasma levels of Lp(a) in diabetic children are significantly related to the length of disease evolution and are independent of the degree of metabolic control.

Triglyceride-rich lipoprotein abnormalities in CAPD-treated patients.

In the present study intermediate-density lipoproteins (IDL) and very-low-density lipoproteins (VLDL) composition, structure, and mass were analysed in fasting uraemic patients on continuous ambulatory peritoneal dialysis (CAPD) (n = 12) and on haemodialysis (HD) (n = 15), and in 15 healthy volunteers. All the groups were matched for sex, age, and time on dialysis. Both groups of patients had elevated very-low-density lipoprotein levels, CAPD patients four and HD group three times that of control. We found a fourfold and a twofold increase in the concentration of IDL cholesterol in the CAPD and HD group respectively when they were compared with the control group. Both groups of patients present an increased VLDL mass. The CAPD group showed a four-fold increase in IDL mass compared with the control group, which indicated a preponderance of large size and suggested that defective IDL clearance was involved. The IDL composition of the CAPD patients was significantly different from that of the HD patients: a twofold increase in IDL mass was observed in the CAPD patients if compared with HD patients. We report new data concerning the metabolism of triglyceride-rich lipoproteins in CAPD treated patients, which confirm the adverse effect of CAPD on serum lipids.

Platelet LDL receptor recognizes with the same apparent affinity both oxidized and native LDL. Evidence that the receptor-ligand complexes are not internalized.

We have recently demonstrated that the platelet low-density lipoprotein (LDL) receptor is immunologically different from the "classic" receptor of nucleated cells. We undertook the current studies to investigate the interaction of this receptor with oxidized LDL and to determine whether an endocytosis-mediated response is involved in the binding of LDL to platelets. The platelet LDL receptor recognized with the same affinity both native and oxidized LDL particles (IC50, 0.045 and 0.054 g/L; Kd, 45.8 and 65.9 nmol/L, respectively). The Hill coefficients of the displacement of 125I-LDL binding were -1.10 and -1.05 for unlabeled native and oxidized LDL, respectively, thereby suggesting a single set of binding sites. To ascertain whether human platelets bind oxidized LDL, we performed ligand binding assays with 125I-oxidized LDL. Saturation curves of 125I-oxidized LDL binding at 22 degrees C showed that human platelets bound these modified particles to a class of saturable binding sites, numbering approximately 3895 +/- 241 per platelet with a dissociation constant (Kd) of 96.2 +/- 10.3 nmol/L. Displacement experiments showed that 125I-oxidized LDL binding was inhibited with the same affinity by both oxidized and native LDL (IC50, 0.055 and 0.065 g/L; Kd, 88 and 64 nmol/L, respectively). The Hill coefficients of the displacement of the 125I-oxidized LDL binding were -1.02 and -1.07 for unlabeled oxidized and native LDL, respectively, suggesting that a single set of binding sites is implicated. Moreover, oxidized LDL- at a protein concentration of 0.5 g/L enhanced ADP- and collagen-induced platelet aggregation in a manner similar to native LDL.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparative study of two lipid emulsions in patients receiving total parenteral nutrition]. / Estudio comparativo de dos emulsiones lipídicas en enfermos que reciben nutrición parenteral total.

INTRODUCTION: the use of lipid emulsions together with glucose as a calorie source in parenteral nutrition has undisputed advantages. Their isotony and high calorie content mean they are essential for peripheric parenteral nutrition and in parenteral nutrition of long duration they are important in providing essential fatty acids. OBJECTIVE: to determine the constant of elimination of two commercial lipid emulsions with similar compositions, and evaluate whether significant differences exist between them. MATERIAL, METHODS AND PATIENTS: 20 candidates for total parenteral nutrition were studied over a period of at least ten days. These patients showed no severe stress, sepsis or IRA. The patients received total parenteral nutrition for at least 3 days prior to commencing the study; 12 hours after initiation, total parenteral nutrition was administered, without lipids. Afterwards, one of the emulsions studied was infused centrally (in Y with the parenteral nutrition) at a rate of 0.15 g/kg/hour for 3 hours, 24 hours later, the other emulsion was infused under the same conditions. Commencing with one or the other was done at random, and both at 10%. Blood samples were taken at the following times:--10.0 (end of the infusion of the emulsion), 10, 30, 60 and 90 minutes, and the following parameters studied: total cholesterol (col), triglycerides (tg) and phospholipids (pl); tg, col ad pl of the VLDL, HDL and LDL, free fatty acids and lipoprotein lipase. The analytical methods employed were: ultracentrifugation with compressed air and precipitation with PEG-6000. RESULTS: significant differences were observed in the constant of elimination of total tg (2.54 +/- 0.73 in emulsion A compared to 2.8 +/- 0.66 in B), in the Kd of the VLDL tg (1.65 +/- 0.86 in A compared to 1.99 +/- 0.77 in B) and in the Kd of the VLDL P1 (0.98 +/- 0.53 in the case of A compared to 1.1 +/- 0.43 in emulsion B), no significant differences were found in the other parameters studied. The Student T was applied, and no lipase lipoprotein activity was observed. DISCUSSION: the differences found may perhaps be explained by the action of the emulgent on the intravascular metabolism of the fats. Although in both cases this is egg lecithin, the composition of this has not been studied in depth. Emulsion A = Intralipid (n. reg). Emulsion B = Tutolipid (n. reg.).