Biosynthesis of bacterial glycogen. IV. Activation and inhibition of the adenosine diphosphate glucose pyrophosphorylase of Escherichia coli B.
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Adenine Nucleotides↗
Biomedical subjects
L Shen
Publications and source records attributed to L Shen.
Estimation of the bioavailability of zinc and calcium from human, cow's, goat, and sheep milk by an in vitro method.
The availability of zinc and calcium from human, cow's, goat, and sheep milk is evaluated by an in vitro method that involves a simulated human gastrointestinal digestion followed by measurement of dialyzability of zinc and calcium. Zinc availability of milk showed the highest value for human milk (15.0%) and the lowest for sheep milk (1.0%), in both whole and skim milk. Calcium availability of the different types of milk did not differ significantly and ranged between 18 and 23%. No significant differences in availability between whole and skim milk were found for both elements, except for zinc in cow's milk.
Animals↗
Diffusibility of selenate, selenite, seleno-methionine, and seleno-cystine during simulated gastrointestinal digestion.
The present study was undertaken to evaluate the in vitro availability of chemically varying forms of selenium (Se), supplemented in cow's milk. Two inorganic (selenite and selenate) and two organic (seleno-methionine [Se-Met] and seleno-cystine [Se-Cys]) Se sources were evaluated. The in vitro availability was estimated by the diffusibility of Se during simulated gastrointestinal digestion. First, the diffusibility was compared after adding a constant amount of Se as either selenate, selenite, seleno-methionine, or Se-Cys in milk samples. Se-Met and selenate were found to be significantly more diffusible than seleno-cystine and selenite under the simulated gastrointestinal conditions. The tendency for superior in vitro availability of selenate and Se-Met compared to selenite and Se-Cys was confirmed for a supplementation range of 5-40 ng/g of Se. This study suggests that the high diffusibility of selenate and Se-Met in a simulated gastrointestinal environment may contribute to their high absorption in vivo.
Animals↗
The disruption of macaque CD4+ T-cell repertoires during the early simian immunodeficiency virus infection.
T-cell receptor (TCR) complementarily determining region 3 (CDR3) spetratyping analysis was employed to assess the ability of an AIDS virus to disrupt CD4 + T-cell repertoires during the primary infection. Rhesus and pig-tailed macaques infected with simian immunodeficiency virus (SIV)mac 251 and SIVsmmFGb, respectively, were evaluated. Following SIV infection, the macaques exhibited an apparent decline of CD4 + peripheral blood lymphocyte (PBL) counts, which was associated with a change in CDR3 profiles from multiple-length distribution to one- or two-length dominance in the selected TCR Vbeta-expressing CD4 + PBL subpopulations. Molecular analysis of the perturbed cell subpopulations suggested that the CD4 + T cells bearing the dominant CDR3 length were clonally expanded. These results indicate that SIV infection can induce a disruption of macaque CD4 + T-cell repertoires during the primary infection. The finding in this study, therefore, suggests that the virus-induced clonal dominance can contribute to the disruption of CD4 + T-cell repertoires.
Animals↗
As2O3 induces apoptosis of the human B lymphoma cell line MBC-1.
OBJECTIVE: To see how arsenic trioxide (As2O3) affects proliferation of the human B lymphoma cell line MBC-1. METHODS: We studied the effect of As2O3 on MBC-1 cells and its mechanism by morphological observation, flow cytometry assay and DNA gel electrophoresis. RESULTS: As2O3 could upregulate p53 gene expression at protein level, inducing cell apoptosis and inhibiting the proliferation of MBC-1 cells. Upregulation of p53 expression appears to be important in the apoptosis of MBC-1 cells. CONCLUSIONS: As2O3 can inhibit the proliferation of MBC-1 cells by upregulating p53 gene expression, thus inducing apoptosis.
Antineoplastic Agents↗
Correlation between DNA methylation and pathological changes in human hepatocellular carcinoma.
BACKGROUND/AIMS: This study was undertaken to obtain information at the molecular level on the possible mechanism of human hepatocarcinogenesis and also to provide a clue for further study. METHODOLOGY: We examined the methylation patterns of c-myc and c-N-ras oncogenes, which are most closely related to HCC, by using the Southern blot technique and HpaII/MspI restriction enzymes. In addition, we measured the level of global DNA methylation in cancerous and paracancerous tissues of HCC by incubating DNA with 3H-S-adenosylmethionine (3H-SAM) in the presence of methylase. The measured global level of DNA methylation was compared with pathological changes of the liver. The methylation patterns of oncogenes as well as the levels of global DNA methylation were compared with pathological changes. RESULTS: The results showed that the hypomethylation rates of c-myc and c-N-ras oncogenes were 30% and 61% respectively in human hepatocellular carcinoma, coinciding with a decreased level of global DNA methylation. DNA hypomethylation was highly significant in cases with a tendency of tumor infiltration or metastasis. CONCLUSIONS: It is concluded that abnormal DNA methylation plays an important role in the process of hepatocellular carcinogenesis. DNA methylation level is closely correlated with the biological characteristic of liver cancer, the lower the level of DNA methylation, the stronger the infiltration and metastatic capacity.
Adult↗