Tissue-dependent preventive effect of metallothionein against DNA damage in dyslipidemic mice under repeated stresses of fasting or restraint

AimsTo investigate the effect of repeated stress on DNA damage in seven organs of dyslipidemic mice, and the preventive role of metallothionein (MT).Main methodsFemale adult 129/Sv wild-type and MT-null mice fed high-fat diet (HFD) were repeatedly subjected to mild stress of fasting or restraint in weeks 2 to 4 of 4-week study period. Serum cholesterol level, DNA damage in the liver, pancreas, spleen, bone marrow, kidney, lung and gastric mucosa, and other parameters were determined.Key findingsBody weights were increased in both types of mice fed HFD compared to those fed standard diet (STD), and further increased by 12 h-fasting, while they were markedly decreased by 1–3 h-restraint. Fasting accelerated accumulation of fat in the liver, and increase in serum cholesterol of both types of mice fed HFD. Feeding of HFD increased DNA damage in the pancreas, spleen and bone marrow of both types of mice, compared with those fed STD. In the wild-type mice fed HFD, 24 h-fasting increased DNA damage in the liver and spleen, while restraint increased the damage in the liver, pancreas, spleen and bone marrow. DNA damage in the cells of organs was markedly increased in the MT-null mice. Specifically, damage in the liver, pancreas, spleen and bone marrow was greatly increased with the intensity of stress increased, and the damage was much greater in the restraint mice than in the fasting mice.SignificanceMT plays a tissue-dependent preventive role against DNA damage in various murine organs induced by repeated stress.     

Induction by synthetic polyribonucleotide poly(I) of differentiation of cultured mouse myeloid leukemic cells.

The effects of some synthetic polyribonucleotides on induction of differentiation of mouse myeloid leukemic M1 cells were examined. Poly(I) was found to be a potent inducer; on treatment with 100--200 microgram/ml of poly(I) for 2--4 days, M1 cells differentiated into cells resembling macrophages and granulocytes and developed phagocytosis and locomotive activities, Fc receptors and lysozyme activity. Poly(C) was less effective than poly(I) for induction of phagocytic activity, while the other single-stranded RNAs, poly(U) and poly(A), had no effect. Double-stranded RNAs, such as poly(I) . poly(C) and poly(A) . poly(U), were cytotoxic to M1 cells, and differentiation of the cells could not be detected even at the highest tolerable concentrations of these double-stranded RNAs.     

Syntheses and Proton Magnetic Resonance Studies at 300 MHz of Two New Bromopentachlorocyclohexanes and Three New Bromotrichlorocyclohexenes

Two diastereomers of 6-bromo-1, 2, 3, 4, 5-pentachlorocyclohexane were synthesized from the dl (36/45)-diastereomer of 3, 4, 5, 6-tetrachlorocyclohexene (α-BTC) and the dl (346/5)-diastereomer (γ-BTC) by several stepwise routes. Both of these new products were shown to have the configuration of lindane by NMR studies at 300 MHz and by the synthetic routes. Three diastereomers of 6-bromo-3, 4, 5-trichlorocyclohexene were also prepared and the configurations determined partly by means of 300 MHz NMR.     

The Effect of Riboflavin on Hypertension induced by High Salt Diet in the Rat

The effect of riboflavin on development of hypertension in rats given a high salt diet was studied. Large doses of riboflavin prevented both elevation of blood pressure and rise of cholesterol levels in the serum. The increase in liver monoamine oxidase activity of the rats fed riboflavin was confirmed.     

Phenanthridin-6-one derivatives as the first class of non-steroidal pharmacological chaperones for Niemann-Pick disease type C1 protein

Niemann-Pick disease type C is a fatal, progressive neurodegenerative disease mostly caused by mutations in Nieamnn-Pick type C1 (NPC1), a late endosomal membrane protein that is essential for intracellular cholesterol transport. The most prevalent mutation, I1061T (Ile to Thr), interferes with the protein folding process. Consequently, mutated but intrinsically functional NPC1 proteins are prematurely degraded via proteasome, leading to loss of NPC1 function. Previously, we reported sterol derivatives as pharmacological chaperones for NPC1, and showed that these derivatives can normalize folding-defective phenotypes of I1061T NPC1 mutant by directly binding to, and stabilizing, the protein. Here, we report a series of compounds containing a phenanthridin-6-one scaffold as the first class of non-steroidal pharmacological chaperones for NPC1. We also examined their structure-activity relationships.     

Switching subtype-selectivity: Fragment replacement strategy affords novel class of peroxisome proliferator-activated receptor α/δ (PPARα/δ) dual agonists

Peroxisome proliferator-activated receptors (PPARs) are important drug targets for treatment of dyslipidemia, type 2 diabetes, cardiovascular disease, nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, and great efforts have been made to develop novel PPAR ligands. However, most existing PPAR ligands contain a carboxylic acid (CA) or thiazolidinedione (TZD) structure (acidic head group) that is essential for activity. We recently discovered non-CA/TZD class PPARα/δ partial agonists, which contain an acetamide moiety and adjacent methyl group, linked to a 1,2,4-oxadiazole ring (“fragment a”). We hypothesized that the acetamide structure might interact with the CA/TZD-binding pocket. To test this idea, we firstly replaced fragment a in one of our compounds with the α-alkoxy-CA structure often found in PPAR agonists. Secondly, we replaced the α-alkoxy-CA head group of several reported PPAR agonists with our acetamide-based fragment a. The agonistic activities of the synthesized hybrid compounds toward PPARs (PPARα, PPARγ and PPARδ) were evaluated by means of cell-based reporter gene assays. All the hybrid molecules showed PPAR-agonistic activities, but replacement of the α-alkoxy-CA head group altered the maximum efficacy and the subtype-specificity. The acetamide-based hybrid molecules showed partial agonism toward PPARα and PPARδ, whereas the α-alkoxy-CA-based molecules were generally selective for PPARα and PPARγ, with relatively high activation efficacies. Thus, the fragment replacement strategy appears promising for the development of novel acetamide-based PPARα/δ dual agonists.     

CMP substitutions preferentially inhibit polysialic acid synthesis

It is widely reported that derivatives of sugar moieties can be used to metabolically label cell surface carbohydrates or inhibit a particular glycosylation. However, few studies address the effect of substitution of the cytidylmonophosphate (CMP) portion on sialyltransferase activities. Here we first synthesized 2'-O-methyl CMP and 5-methyl CMP and then asked if these CMP derivatives are recognized by alpha2,3-sialyltransferases (ST3Gal-III and ST3Gal-IV), alpha2,6-sialyltransferase (ST6Gal-I), and alpha2,8-sialyltransferase (ST8Sia-II, ST8Sia-III, and ST8Sia-IV). We found that ST3Gal-III and ST3Gal-IV but not ST6Gal-I was inhibited by 2'-O-methyl CMP as potently as by CMP, while ST3Gal-III, ST3Gal-IV, and ST6Gal-I were moderately inhibited by 5-methyl CMP. Previously, it was reported that polysialyltransferase ST8Sia-II but not ST8Sia-IV was inhibited by CMP N-butylneuraminic acid. We found that ST8Sia-IV as well as ST8Sia-II and ST8Sia-III are inhibited by 2'-O-methyl CMP as robustly as by CMP and moderately by 5-methyl CMP. Moreover, the addition of CMP, 2'-O-methyl CMP, and 5-methyl CMP to the culture medium resulted in the decrease of polysialic acid expression on the cell surface and NCAM of Chinese hamster ovary cells. These results suggest that 2'-O-methyl CMP and 5-methyl CMP can be used to preferentially inhibit sialyltransferases, in particular, polysialyltransferases in vitro and in vivo. Such inhibition may be useful to determine the function of a carbohydrate synthesized by a specific sialyltransferase such as polysialyltransferase.     

Recovery of Bacillus thuringiensis from Marine Sediments of Japan

Marine sediments from a Japanese bay were examined for the occurrence of Bacillus thuringiensis. Of 1313 colonies belonging to the Bacillus cereus/B. thuringiensis group, 22 (1.7%) were allocated to B. thuringiensis. Marine isolates of B. thuringiensis consisted of heterogeneous multiple H serogroups; 10 isolates were assigned to the eight serovars (kurstaki, sumiyoshiensis, sotto, aizawai, darmstadiensis, thompsoni, neoleonensis, and higo); two motile isolates failed to react with the reference antisera; and the others were serologically untestable. Insecticidal activities were associated with two kurstaki isolates (toxic to both Lepidoptera and Diptera) and a higo isolate (Diptera-specific). None of the parasporal inclusion proteins of the 22 isolates exhibited in vitro cytotoxic activity against two vertebrate cells, sheep erythrocytes and HeLa cells. All B. thuringiensis isolates had no halophilism, although seawater-based medium supported their growth, sporulation, and formation of parasporal inclusions. Received: 29 November 1999 / Accepted: 10 January 2000