Biomedical subjects
A Endo
Publications and source records attributed to A Endo.
Inhibition of oxidized low-density lipoprotein metabolism in macrophage J774 by helvolic acid.
The antibiotic helvolic acid inhibited cholesteryl ester accumulation in macrophage J774 treated with oxidized low-density lipoprotein (LDL) at a concentration of 50-350 microM. The agent reduced oxidized 125I-LDL degradation and [14C]oleate incorporation into cholesteryl ester. In a cell-free assay, ATP-dependent acidification of endosomes and lysosomes was significantly inhibited by 35 microM helvolic acid, suggesting that this activity accounts for the inhibition of oxidized LDL metabolism in the macrophages.
Stimulation of acyl-CoA:cholesterol acyltransferase activity by brefeldin A in macrophage J774 cells.
Brefeldin A (BFA), an inhibitor of secretory pathway, enhances incorporation of radiolabeled cholesterol and oleate into cholesteryl esters in cultured cells [12]. We studied the mechanism for this effect of BFA in the macrophage J774. When incubated with 2.7 microM BFA in the absence of lipoproteins, J774 cells synthesized and accumulated 1.5- to 4-fold more cholesteryl esters than did cells which received no BFA. BFA caused neither an elevation of cholesterol synthesis, inhibition of its secretion nor changes in cholesterol transport to plasma membrane, esterification of plasma membrane cholesterol and cholesteryl ester hydrolysis. Acyl-CoA:cholesterol acyltransferase (ACAT) activity in microsomes from BFA-treated cells was 1.5- to 1.8-fold higher than that from control cells. The effect of BFA was diminished by treatment with low temperature, which is known to abolish BFA effect on Golgi formation.
Inhibition of protein prenylation by patulin.
The antibiotic patulin was found to inhibit protein prenylation in mouse FM3A cells. Thus, the agent reduced incorporation of [3H]mevalonate into proteins by 50% at a concentration of 7 microM. In a cell-free assay, patulin inhibited rat brain farnesyl:protein transferase, one of the enzymes responsible for protein prenylation. The inhibition was 50% at a concentration of 290 microM.
Cloning of two isozymes of Trichoderma koningii glyceraldehyde-3-phosphate dehydrogenase with different sensitivity to koningic acid.
Koningic acid inhibits glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by binding to the SH group in the active center. The fungus Trichoderma koningii, the producer of koningic acid, contains two GAPDH isozymes (GAPDHs I and II). GAPDH I is inhibited 50% by 1.1.10(-3) M koningic acid, while GAPDH II is inhibited 50% at 6.8 x 10(-6) M. cDNAs of the two isozymes were cloned from T. koningii and their nucleotide sequences were determined. The sequence of coding region and codon usage in both clones were compared with each other and with those of the gene for Aspergillus nidulans GAPDH (enzyme activity is inhibited 50% by 2.7 x 10(-7) M koningic acid). Results indicated that GAPDH II is more closely related to A. nidulans GAPDH than GAPDH I. All essential amino acid residues, except 174 and 181, which are implicated in catalysis and binding of NAD and substrates, were conserved among A. nidulans GAPDH and GAPDHs I and II. Residues 174 and 181 are threonine in both A. nidulans GAPDH and GAPDH II, but alanine and serine, respectively, in GAPDH I. The side-chain of alanine-174 in GAPDH I can not replace threonine-174 functionally as threonine-174 side-chain forms a hydrogen bond with the catalytically essential histidine-176.
Ecological factors affecting body size of Japanese adolescents.
Prefectural data of 17-year-old Japanese adolescents' body size were excerpted from the annual series of Reports on School Health Statistics (Ministry of Education) for the last 35 years, and were correlated with the mean annual temperature of prefectural capitals. A negative correlation was found for both height and weight. Thus, it can be stated that children in colder climates conform to Bergmann's rule that they are larger in their height and weight than children growing up in warmer climates. Partial correlation coefficients indicate that body weight is primarily related to the temperature. Further, the results of a multiple regression analysis, using temperature, daily energy intake (National Nutrition Surveys), and annual per capita income (Annual Reports of Prefectural Accounts) as the independent variables among the 12 districts (groups of prefectures) for the last 25 years, suggest that the observed Bergmann's phenomenon is related to geographical differences in nutrition; people in colder regions consume more calories than those in warmer regions.
Immortalization of epithelial-like cells from human liver tissue with SV40 T-antigen gene.
The cells derived from the human embryo liver tissue were transfected with a plasmid pSV3neo containing both the large and small T-antigen gene of the early region of simian virus 40 (SV40), and two cell strains, OUMS-21 and -22, were obtained. OUMS-22 cells, to date, have reached over 100 population doublings through a culture crisis and are considered to have become an immortal cell line. However, OUMS-21 cells failed to become an immortal cell line. Both OUMS-21 and -22 cells were SV40 T-antigen-positive, epithelial-like, and immunoreactive against an anti-keratin 18 monoclonal antibody but against neither an anti-vimentin nor an anti-von Willebrandt factor VIII monoclonal antibody. The staining pattern of cytokeratin in these cells was similar to that in the differentiated human hepatoblastoma and hepatocellular carcinoma cell lines but not to that in the human cholangiocellular carcinoma cell lines. OUMS-21 and -22 cells expressed neither alpha-fetoprotein nor albumin mRNAs. These cells showed no tyrosine aminotransferase activity. However, both OUMS-21 and -22 cells were sensitive to cytotoxicity of aflatoxin B1, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole, and benzo[a]pyrene, whereas human embryo lung fibroblasts were insensitive to the cytotoxicity of these carcinogens. These findings suggest that OUMS-21 and -22 cells may arise from undifferentiated liver stem cells or from hepatocytes that lost their ability to express the liver-specific functions prior to immortalization. Both OUMS-21 and -22 cells expressed glutathione S-transferase pi (GST-pi) mRNA. The expression of GST-pi mRNA highly increased in OUMS-22 cells with their immortalization. Karyotypic analysis showed that numerical and structural aberrations of the chromosomes were profound, but neither specific events nor marker chromosomes were found in OUMS-21 and -22 cells. Both OUMS-21 and -22 cells could grow in soft agar, but they were not tumorigenic when transplanted into nude mice.
Alteration in the retinoblastoma gene associated with immortalization of human fibroblasts treated with 60Co gamma rays.
Genetic analysis was carried out in human fibroblasts (KMST-6) immortalized by treatment with 60Co gamma rays in order to determine if any genetic change was involved in the immortal transformation of human cells. Analysis by restriction fragment length polymorphism revealed an alteration in chromosome 13q12-14, in which the retinoblastoma (RB) gene locus (13q14) is located. Then the RB gene itself was examined. Structural abnormalities in the RB gene were detected by Southern blot analysis. Furthermore, abnormal RB protein (pRB) was expressed in immortalized KMST-6 cells, as shown by in vitro phosphorylation, whereas normal KMS-6 cells expressed the intact pRB. These findings indicated that inactivation of the RB gene is one of the key events of the immortalization of human cells.
Time response of cholesterol synthesis inhibition by compactin-related compounds. In vitro quantitation of the "escape phenomenon".
The time course of the inhibition of cholesterol synthesis by low and high doses of mevinolin and monacolin X were studied in normal human skin fibroblasts, fibroblasts without low density lipoprotein receptor and HepG2 hepatoma cells. Low doses of the inhibitors (0.2 ng/mL) caused a sharp decrease in the rate of cholesterol synthesis during the first 2-3 h, which gradually increased to about 40% during the next 6 h. Further incubation led to a decrease or stabilization of the cholesterol synthesis rate. High doses of the drugs (100 mg/mL) strongly inhibited cholesterol synthesis during the first 2-3 h, followed by a moderate increase during the next 20 h. No drug or tissue selectivity was observed.
Paw preference in mice: a reappraisal.
Paw preference in three strains (BALB/cA, C57BL/6J, Jcl:ICR) of mice was measured using the method of R. L. Collins (RPE score). We found that a) the patterns of paw preference were not so distinct as in previous studies, b) however, among these three strains, there were some differences in their patterns; namely, slight laterality was found in the C57BL/6J strain (RPE score distribution flattened), although no laterality was found in BALB/cA or Jcl:ICR strain (RPE score distributions bell shaped). These findings differ from those of previous studies. In this study we also propose a simplified method for determining paw preference in mice.
Detection and identification of equine herpesvirus-1 and -4 by polymerase chain reaction.
A rapid method for detection and identification of equine herpesvirus-1 and -4 (EHV-1 and EHV-4) was developed using polymerase chain reaction (PCR). Primers for PCR were designed from aligned nucleotide sequences of glycoprotein B genes of EHV-1 and EHV-4 to amplify specific regions for EHV-1 or EHV-4 or a common region of both viruses. By using type specific primer mixture, amplified fragments were identified as EHV-1 or EHV-4 in a one-step reaction. We have applied this technique on specimens from aborted fetuses. The samples contained only EHV-1 and there was complete accordance between the results of PCR and virus isolation. Our PCR system could differentiate the two virus types rapidly in a one-step reaction.
Assessment of the chemical form of gaseous 35S species produced during the production of H3(32)PO4.
The chemical form of gaseous 35S species produced during the production of H3(32)PO4 was characterized in order to reduce 35S discharge by understanding its production mechanism and chemical reactivity. An air sample was evacuated from the cell in which the H3(32)PO4 production was being carried out and collected in a sample gas reservoir. Gaseous sulfur species contained in the sample were condensed in a cold trap maintained at -180 degrees C and analyzed by means of gas chromatography using a flame photometric detector. Sulfur dioxide (SO2) was the only sulfur species detected. Equilibrium constant calculations showed that SO2 would be expected to be the predominant species produced by reactions of sulfur molecules (Sn:n = 2-8) with oxygen in air and that the quantity of SO2 produced would be reduced by heating the irradiated sulfur target under vacuum or in atmospheres of inert gases.
Growth and development of 39,X mouse embryos at mid-gestation.
We examined the growth and development of XO embryos at mid-gestation (day 10) by assessing crown-rump length, head length, somite number, and morphological score (Van Maele-Fabry et al., 1990), using an XO mouse colony established from the Jcl/ICR strain. Contrary to expectation, there were no differences between the XO and XX embryos in any parameter measured. Also, no particular region was specifically retarded in XO embryos during development. We therefore concluded that the growth and development of XO embryos were not retarded when compared with their XX littermates at day 10 of gestation.
Chrysosporin, a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase produced by Chrysosporium pannorum.
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Inhibition of acyl-CoA: cholesterol acyltransferase by helminthosporol and its related compounds.
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Lateritin, a new inhibitor of acyl-CoA:cholesterol acyltransferase produced by Gibberella lateritium IFO 7188.
A new inhibitor of acyl-CoA:cholesterol acyltransferase (ACAT), designated lateritin, was isolated from the mycelial cake of Gibberella lateritium IFO 7188 by successive purification procedure of solvent extraction, silica gel column chromatography and reverse phase HPLC. Spectroscopic analyses of the compound yielded 4-methyl-6-(1-methylethyl)-3-phenylmethyl-1,4-perhydrooxazine-2,5- dione as the proposed structure. Lateritin inhibited rat liver ACAT activity by 50% at a concentration of 5.7 microM. This inhibition was time-dependent and irreversible.
Competitive inhibition of squalene synthetase by squalestatin 1.
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