Investigations on the mechanism of hypercholesterolemia observed in copper deficiency in rats

The mechanism of hypercholesterolemia effect of Cu²⁺ deficiency was studied in rats. There was increased activity of hepatic hydroxymethylglutaryl-coenzyme A reductase and increased incorporation of labelled acetate into free cholesterol of liver in the Cu²⁺ deficient rats. Incorporation of label into ester cholesterol was however decreased in the liver. Concentration of bile acids in the liver was not significantly altered. Increase in the incorporation of labelled acetate into serum cholesterol and increase in the concentration of cholesterol and apo B in the low density lipoproteins + very low density lipoproteins fractions were observed. Activity of lipoprotein lipase of the extrahepatic tissues decreased in the Cu²⁺ deficient rats.     

Effect of auxin on the metabolism of mevalonic acid in suspension-cultured carrot cells

The rate of incorporation of [¹⁴C]mevalonate into carotenoid and steroid fractions in suspension-cultured carrot cells decreased markedly after 2,4-dichlorophenoxyacetic acid was removed from the medium. In parallel to this change, the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase in a microsomal fraction was reduced to ca 33% of the control value, while that of a particulate fraction showed no significant change. The activities of mevalonate activating enzymes remained unchanged after auxin deprivation.     

Increased autophagy accelerates colchicine-induced muscle toxicity

Colchicine treatment is associated with an autophagic vacuolar myopathy in human patients. The presumed mechanism of colchicine-induced myotoxicity is the destabilization of the microtubule system that leads to impaired autophagosome-lysosome fusion and the accumulation of autophagic vacuoles. Using the MTOR inhibitor rapamycin we augmented colchicine’s myotoxic effect by increasing the autophagic flux; this resulted in an acute myopathy with muscle necrosis. In contrast to myonecrosis induced by cardiotoxin, myonecrosis induced by a combination of rapamycin and colchicine was associated with accumulation of autophagic substrates such as LC3-II and SQSTM1; as a result, autophagic vacuoles accumulated in the center of myofibers, where LC3-positive autophagosomes failed to colocalize with the lysosomal protein marker LAMP2. A similar pattern of central LC3 accumulation and myonecrosis is seen in human patients with colchicine myopathy, many of whom have been treated with statins (HMGCR/HMG-CoA reductase inhibitors) in addition to colchicine. In mice, cotreatment with colchicine and simvastatin also led to muscle necrosis and LC3 accumulation, suggesting that, like rapamycin, simvastatin activates autophagy. Consistent with this, treatment of mice with four different statin medications enhanced autophagic flux in skeletal muscle in vivo. Polypharmacy is a known risk factor for toxic myopathies; our data suggest that some medication combinations may simultaneously activate upstream autophagy signaling pathways while inhibiting the degradation of these newly synthesized autophagosomes, resulting in myotoxicity.     

A combined LDL receptor/LDL receptor adaptor protein 1 mutation as the cause for severe familial hypercholesterolemia

Familial hypercholesterolemia (FH) results from impaired catabolism of plasma low density lipoproteins (LDL), thus leading to high cholesterol, atherosclerosis, and a high risk of premature myocardial infarction. FH is commonly caused by defects of the LDL receptor or its main ligand apoB, together mediating cellular uptake and clearance of plasma LDL. In some cases FH is inherited by mutations in the genes of PCSK9 and LDLRAP1 (ARH) in a dominant or recessive trait. The encoded proteins are required for LDL receptor stability and internalization within the LDLR pathway. To detect the underlying genetic defect in a family of Turkish descent showing unregular inheritance of severe FH, we screened the four candidate genes by denaturing gradient gel electrophoresis (DGGE) mutation analysis. We identified different combinatory mixtures of LDLR- and LDLRAP1-gene defects as the cause for severe familial hypercholesterolemia in this family. We also show for the first time that a heterozygous LDLR mutation combined with a homozygous LDLRAP1 mutation produces a more severe hypercholesterolemia phenotype in the same family than a homozygous LDLR mutation alone.     

Genomic organization and expression analysis of a farnesyl diphosphate synthase gene (FPPS2) in apples (Malus domestica Borkh.)

A farnesyl diphosphate synthase gene (FPPS2), which contains 11 introns and 12 exons, was isolated from the apple cultivar “White Winter Pearmain”. When it was compared to our previously reported FPPS1, its each intron size was different, its each exon size was the same as that of FPPS1 gene, 30 nucleotide differences were found in its coding sequence. Based on these nucleotide differences, specific primers were designed to perform expression analysis; the results showed that it expressed in both fruit and leaf, its expression level was obviously lower than that of FPPS1 gene in fruit which was stored at 4 °C for 5 weeks. This is the first report concerning two FPPS genes and their expression comparison in apples.     

Syntheses and Biological Activities of 1-O-Glucopyranosyl Fatty Acid Esters

1-O-Palmitoyl-d-glucopyranose was prepared by the selective 1-O-acylation of 4,6-O-benzylideneglucose followed by hydrogenolysis of the protecting group. 1-O-Oleoyl-d-glucopyranose was synthesized from the corresponding benzylidene derivative by selective hydrolysis in acetic acid. This procedure constitutes a useful method for the synthesis of 1-O-acyl-d-glucopyranoses containing unsaturated carboxylic acids. However, 4,6-O-benzylidene-l-O-linolenoyl-d-glucopyranose was converted to 3-O-linolenoyl-d-glucopyranose by the acidic hydrolysis due to acyl migration.

Synthesized glucosyl esters were inactive in the bean second-internode bioassay. However, it was found that 3-O-linolenoyl-d-glucopyranose had a promoting activity on germination of pollen and growth of pollen tube.     

Rapid Retting of Kôzo (Paper Mulberry) Bast with Erwinia carotovora

The degradation of nitrite and the inhibition towards formation of carcinogenic nitrosamines by melanoidins, produced from the glucose-glycine system were investigated at various conditions. The degradation of nitrite was highest at pH 1.2 (29%), when the ratio of melanoidins to nitrite was 1: 3. The inhibition towards formation of nitrosamines by melanoidins had the same tendency as the degradation of nitrite, the inhibition also being highest at pH 1.2 (99%). In addition, melanoidins after nitrite treatment exhibited a little higher mutagenicity and much stronger desmutagenicity than those of the original melanoidins. The change of the structure of melanoidins after treating with nitrite was also investigated by HPLC and CP-MAS NMR.     

Effects of Korean Red Ginseng extract on hepatic lipid accumulation in HepG2 cells

In this study, we investigated the effects of Korean red ginseng water extract (KRGE) on hepatic lipid accumulation in HepG2 cells. KRGE decreased hepatic triglyceride and cholesterol levels. Further, KRGE suppressed expression of fatty acid synthase (FAS) and 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase. These results suggest that KRGE may reduce hepatic lipid accumulation by inhibition of FAS and HMG-CoA reductase expression in HepG2 cells.