44 research outputs found
Effects of ML-236B (compactin) on sterol synthesis and low density lipoprotein receptor activities in fibroblasts of patients with homozygous familial hypercholesterolemia
金沢大å¦å¤§å¦é™¢åŒ»å¦ç³»ç ”究科 We studied biochemical genetics of low density lipoprotein (LDL) receptor mutations in fibroblasts from six homozygous and five heterozygous patients with familial hypercholesterolemia (FH). Three of six homozygotes are receptor-negative type and the other three homozygotes are receptor-defective type. In the cells from three receptor-negative homozygotes, the receptor binding, internalization, and degradation of 125I-LDL were 0.5 ± 0.3 ng/mg protein (mean ± SEM), 14 ± 8 and 8 ± 6 ng/mg protein per 6 h (four normal cells; 44 ± 3, 386 ± 32, and 1,335 ± 214 ng/mg protein per 6 h), respectively. In the cells from three receptor-defective homozygotes, the receptor binding, internalization, and degradation of 12:5I-LDL were 6 ± 2, 29 ± 8, and 90 ± 32 ng/mg protein per 6 h, respectively. In these six homozygotes, two pairs of siblings are included. Two siblings in the same family were classified as receptor-negative and two siblings in another family were classified as receptor-defective. The receptor-negative phenotypes and the receptor-defective phenotypes bred true in individual families. The cells from five heterozygotes showed ~46% of the normal activities of receptor. ML-236B, competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), completely inhibited the incorporation of [14C]acetate into digitonin-precipitable sterols in fibroblasts from normal subjects and heterozygous and homozygous patients with FH with the concentration of 0.5 μg/ml. However, at 0.05 μg/ml of ML-236 B sterol synthesis in fibroblasts from homozygotes was not completely suppressed in contrast to normal and heterozygous cells. Moreover, after preincubation with 0.05 μg/ml of ML-236B for 24 h in medium containing lipoproteins, sterol synthesis in the cells from receptor-negative homozygote showed 75% of the initial activity compared with that of 25% without preincubation. In the cells from a normal subject and heterozygote, sterol synthesis was inhibited even after preincubation. These results suggest that (a) the inhibitory effect of ML-236B is overcome in homozygote cells by their high intracellular levels of HMG-CoA reductase and (b) that a higher dose of ML-236B may be required to lower serum cholesterol levels in FH homozygotes than in heterozygotes
Circadian rhythm of cortical and hippocampal acetylcholine release as measured by in vivo microdialysis in freely moving rats
Amino acid sequence of an amyloidogenic Bence Jones protein in myeloma-associated systemic amyloidosis
Effect of suspension potential on the oxidation rate of copper concentrate in a sulfuric acid solution
N-linked oligosaccharide processing enzyme glucosidase II produces 1,5-anhydrofructose as a side product
α-1,4-Glucan lyase cleaves α-1,4-linkages of nonreducing termini of α-1,4-glucans to produce 1,5-anhydrofructose (1,5-AnFru). The enzymes isolated from fungi and algae show high homology with glycoside hydrolase family 31. Purification of α-1,4-glucan lyase from rat liver using DEAE Cellulose chromatography resulted in separation of two enzymatic active fractions, one was bound to the column and the other was in the flow-through. Partial amino acid sequence determined from the lyase, retained on the anion exchange column, were identical with that of the N-linked oligosaccharide processing enzyme glucosidase II. The lyase showed similar enzymatic properties as the microsomal glucosidase such as inhibition by 1-deoxynojirimycin and castanospermine. On the other hand, glucosidase II purified from rat liver microsomes produced not only glucose but also a small amount of 1,5-AnFru using maltose as substrate. Furthermore, CHO cells overexpressing pig liver glucosidase II showed a 1.5- to 2-fold higher lyase activity compared to the nontransfected CHO cells. Conversely, no lyase activity was detectable either in PHAR2.7, the glucosidase II-deficientmutant from a mouse lymphoma cell line, or in Saccharomyces cerevisiae strain YG427 having the glucosidase II gene disrupted. These data demonstrate that glucosidase II possesses an additional enzymatic activity of releasing 1,5-AnFru from maltos
Epitope mapping of antibodies against TDP-43 and detection of protease-resistant fragments of pathological TDP-43 in amyotrophic lateral sclerosis and frontotemporal lobar degeneration
Correlation between dielectric properties and aqueous oxidation rate for pulverized sphalerites and zinc concentrates
Effects of ML-236b (compactin) on sterol synthesis and low density lipoprotein receptor activities in fibroblasts of patients with homozygous familial hypercholesterolemia. J Clin Invest
A B S T R A C T We studied biochemical genetics of low density lipoprotein (LDL) receptor mutations in fibroblasts from six homozygous and five heterozygous patients with familial hypercholesterolemia (FH 29 December 1980. 1532 tion of 0.5 Ag/ml. However, at 0.05 ,ug/ml of sterol synthesis in fibroblasts from homozygotes was not completely suppressed in contrast to normal and heterozygous cells. Moreover, after preincubation with 0.05 ,ug/ml of ML-236B for 24 h in medium containing lipoproteins, sterol synthesis in the cells from receptornegative homozygote showed 75% of the initial activity compared with that of 25% without preincubation. In the cells from a normal subject and a heterozygote, sterol synthesis was inhibited even after preincubation. These results suggest that (a) the inhibitory effect of ML-236B is overcome in homozygote cells by their high intracellular levels of HMG-CoA reductase and (b) that a higher dose of ML-236B may be required to lower serum cholesterol levels in FH homozygotes than in heterozygotes