We studied the association of six common polymorphisms of four genes related to lipid metabolism with serum lipid levels. We selected single-nucleotide polymorphisms (SNPs) in the genes for cholesteryl ester transfer protein (CETP), lipoprotein lipase (LPL), hepatic lipase (LIPC), and apolipoprotein CIII (APOC3), and studied 2267 individuals randomly selected from the participants of Serum Lipid Survey 2000. There was a significant association of CETP polymorphism (D442G, Int14 +1 G --> A, and TaqIB), LPL polymorphism (S447X), and LIPC polymorphism (-514 --> CT) with HDL-cholesterol levels. We also found a significant association of LPL polymorphism (S447X) and APOC3 polymorphism (SstI) with triglyceride levels. This is the largest database showing the association of common genetic variants in lipid metabolism with serum lipid levels in the general Japanese population. Further study is necessary to elucidate the role of these gene polymorphisms in cardiovascular events.
HDL-associated paraoxonase type 1 (PON1) can protect LDL and HDL against oxidative modification in vitro and therefore may protect against cardiovascular disease. We investigated the effects of PON1 levels, activity, and genetic variation on high density lipoprotein-cholesterol (HDL-C) levels, circulating oxidized LDL (OxLDL), subclinical inflammation [high-sensitive C-reactive protein (Hs-CRP)], and carotid atherosclerosis. PON1 genotypes (L55M, Q192R, -107C/T, -162A/G, -824G/A, and -907G/C) were determined in 302 patients with familial hypercholesterolemia. PON1 activity was monitored by the hydrolysis rate of paraoxon, diazoxon, and phenyl acetate. PON1 levels, OxLDL, and Hs-CRP were determined using an immunoassay. The genetic variants of PON1 that were associated with high levels and activity of the enzyme were associated with higher HDL-C levels (P values for trend: 0.008, 0.020, 0.042, and 0.037 for L55M, Q192R, -107C/T, and -907G/C, respectively). In addition to the PON1 genotype, there was also a positive correlation between PON1 levels and activity and HDL-C (PON1 levels: r = 0.37, P < 0.001; paraoxonase activity: r = 0.23, P = 0.01; diazoxonase activity: r = 0.29, P < 0.001; arylesterase activity: r = 0.19, P = 0.03). Our observations support the hypothesis that both PON1 levels and activity preserve HDL-C in plasma.
Plasma lipoprotein-associated phospholipase A2 (Lp-PLA2), also known as platelet-activating factor (PAF) acetylhydrolase (PAF-AH), is a member of the serine-dependent class of A2 phospholipases that hydrolyze sn2-ester bonds of fragmented or oxidized phospholipids at sites where atherosclerotic plaques are forming. Most circulating Lp-PLA2 is bound to low-density lipoprotein (LDL) particles in plasma and the rest to high-density lipoprotein (HDL). Deficiency of Lp-PLA2 is a predisposing factor for cardiovascular diseases in the Japanese population. We describe here two novel mutations of the gene encoding Lp-PLA2, InsA191 and I317N in Japanese subjects. The first patient, with partial Lp-PLA2 deficiency, was heterozygous for the InsA191 mutation; macrophages from this patient secreted only half the normal amount of Lp-PLA2 in vitro. The other patient, who showed complete Lp-PLA2 deficiency, was a compound heterozygote for the novel I317N mutation and a common V279F mutation; macrophages from that patient failed to secrete any Lp-PLA2. Measurement of Lp-PLA2 mass, activity and Western blotting verified impaired production and secretion of the enzyme after transfection of mutant construct into COS-7 cells. These results indicated that both novel mutants, InsA191 and I317N, impair function of the Lp-PLA2 gene.
Reversal of vecuronium-induced neuromuscular blockade with neostigmine was compared in two groups of 16 subjects: patients with Type 2 diabetes mellitus and normal controls. When the first twitch of the train-of-four had returned to 25% of the control value, neostigmine 40 microg x kg(-1) and atropine 20 microg x kg(-1) were given to reverse the neuromuscular blockade. The train-of-four ratio was lower at 3 min, 6 min, 9 min, 12 min and 15 min after reversal in the diabetic group than in the control group but the differences did not reach statistical significance. Fifteen minutes after reversal, the number of patients in whom recovery from neuromuscular blockade was judged insufficient to guarantee good respiratory function (train-of-four ratio < 0.74) did not differ between the groups. However, 15 min after reversal, the number of patients with a train-of-four ratio < 0.9 was significantly higher in the Diabetic Group than in the Control Group (15 vs. 10, p = 0.033).
A form of CAT-like activity was found bound present in rat brain synaptosomal membranes which could be recovered in the Triton X-114 phase. The enzyme activity was slightly activated by NaCl, had a pH maximum around 8 and showed a temperature dependence with a Q10 of 2.28. It was inhibited 100% by 10(-6) M naphthyl vinyl pyridinium but not by 10(-5) M diisopropyl phosphofluoridate. The kinetics of this bound form of CAT were similar to the soluble form of the enzyme. The Km was 405 +/- 58 microM for choline and 62 +/- 8 microM for AcCoA. Five isoelectric forms were found with pH's of 4.55, 6.05, 7.05, 7.36, and 8.00 which is in contrast to the three isoelectric forms found of the soluble enzyme in rat brain. The presence of a CAT-like activity in the plasma membrane was confirmed with experiments performed using intact synaptosomes and intact cells in culture. Acetylcholine, synthesized from radioactive AcCoA by intact rat brain synaptosomes, was recovered in the incubation medium and only in the presence of exogenous choline or when the production of choline was stimulated by oleate via the activation of phospholipase D. This was also seen in experiments with intact pheochromocytoma cell cultures (PC 12) which synthesize acetylcholine that was recovered in the incubation medium. Acetylcholine formation in the presence of choline and AcCoA was stimulated in cells that had been grown in the presence of nerve growth factor (NGF).
Title: Choline acetyltransferase activity bound to synaptosomal plasma membranes as regulatory step in acetylcholine biosynthesis Sorrentino G, Ferret B, Hattori H, Kanfer JN, Massarelli R Ref: Acta Neurol (Napoli), 10:85, 1988 : PubMed
Title: Stimulation of phospholipase D activity and indication of acetylcholine synthesis by oleate in rat brain synaptosomal preparations Hattori H, Kanfer JN, Massarelli R Ref: Neurochem Res, 12:687, 1987 : PubMed
It had been previously demonstrated that the oleate activation of synaptosomal membrane phospholipase D liberated choline which was available for acetylcholine formation. The present investigations were undertaken to determine if oleate might have an effect on choline uptake by synaptosomes. It was observed that oleate interfered with choline uptake when incubations were carried out at 37 degrees C but uptake was stimulated at 3 degrees C. Oleate was the most effective fatty acid of several tested. Preliminary observations suggest the presence of a membranous form of choline acetyltransferase.
