Epigallocatechin gallate, the main component of tea polyphenol, binds to CD4 and interferes with gp120 binding

BACKGROUND: Epigallocatechin gallate (EGCG), the major component of tea polyphenol, has been reported to have various physiologic modulatory activities. Several reports also have shown that catechin has a protective effect against HIV infection, part of which is mediated by inhibiting virions to bind to the target cell surface. OBJECTIVE: We investigated the effect of EGCG on the expression of CD4 molecules and on its ability to bind gp120, an envelope protein of HIV-1. METHODS: Peripheral blood CD4+ T cells were incubated in the presence of EGCG, and the expression of CD4 was evaluated by means of flow cytometry. The effect of EGCG on the antibody binding to CD4 was investigated by using a sandwich ELISA, and the effect on the gp120 binding to CD4 was analyzed by means of flow cytometry. RESULTS: EGCG efficiently inhibited binding of anti-CD4 antibody to its corresponding antigen. This effect was mediated by the direct binding of EGCG to the CD4 molecule, with consequent inhibition of antibody binding, as well as gp120 binding. CONCLUSION: The present results suggest a potential preventive effect of EGCG on HIV-1 infection by modulating binding to CD4.     

DNA-Based Typing of Human Platelet Antigen Systems by Polymerase Chain Reaction-Single-Strand Conformation Polymorphism Method

Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method has been established to discriminate genotypes for the human platelet antigen (HPA) systems HPA-1, HPA-2, HPA-3, HPA-4, and HPA-5. Gene fragments which contain polymorphic sequences corresponding to the HPA-1, HPA-2, HPA-3, HPA-4, and HPA-5 systems were PCR-amplified with specific primers. The amplified DNA was denatured and subjected to non-denaturing polyacrylamide gel electrophoresis followed by silver staining. The results obtained by the PCR-SSCP method were in good agreement with those of the allotypes determined by serological typing. Furthermore, the results agreed with those obtained by other DNA-based typing methods such as PCR-allele-specific restriction enzyme analysis and PCR-sequence-specific primer. These results indicate that PCR-SSCP is a simple and sensitive method for determining HPA genotypes and identifying unknown polymorphisms.     

Basic study on human interferon-beta: Part III. The mechanisms of its antitumor effect

The mechanisms of the direct and indirect antitumor effects of human interferon-beta (IFN-beta, MR-21) were examined. IFN-beta suppressed DNA, RNA and protein synthesis in cells derived from human tumor. The expression of cellular oncogenes (c-Ha-ras and c-myc) in tumor-originated cells was also suppressed by IFN-beta. These results suggest that such suppression is one possible mechanism of the direct anticellular effect induced by IFN-beta. IFN-beta augmented NK cell activity and the ADCC activity of human peripheral blood lymphocytes. It is also suggested that these are two of the immune system-mediated mechanisms responsible for the indirect antitumor effect of IFN-beta in vivo.     

Magnetic resonance imaging of experimental cerebral ischemia: correlations between NMR parameters and water content

Recent studies on proton NMR imaging revealed its remarkable sensitivity for detecting cerebral ischemia. Since proton NMR reflects the distribution and state of water in the brain, an NMR imager becomes a sensitive in vivo detector of brain edema developing soon after the energy state is compromized by ischemia. To further clarify the usefulness of NMR imaging to characterize the ischemia-induced changes, correlations between T1 and T2 relaxation times and water content of the normal and ischemic rat and gerbil brain were studied by means of both spectroscopic and in vivo imaging methods. In the spectroscopic experiment on excised rat brain (cortex, white matter, hippocampus and thalamus for normal and ischemia-laden brain), T1 and T2 relaxation times and water content were determined. The ischemic insult was induced for 60 min by the method of Pulsinelli followed by 60 min of reperfusion. All of the T1, T2 and water content significantly increased in the ischemic tissue. Gray-white difference was evident in T1 and T1 was linearly correlated with the water content of the tissue. T2 was by far prolonged in the ischemic tissue compared with the increase in the water content, showing greater sensitivity of T2 for detection of ischemia. In the imaging experiment, coronal NMR imaging at 0.5 tesla was performed employing proton density-weighted saturation recovery (TR = 1.6 s, TE = 14 ms), T1-weighted inversion recovery (TR = 1.6 s, TI = 300 ms, TE = 14 ms) and T2-weighted spin echo (TR = 1.6 s, TE = 106 ms) pulse sequences.(ABSTRACT TRUNCATED AT 250 WORDS)     

Temperature-sensitive defect of influenza A/Ann Arbor/6/60 cold-adapted variant leads to a blockage of matrix polypeptide incorporation into the plasma membrane of the infected cells

A temperature-sensitive (ts) defect in growth of the A/Ann Arbor/6/60 (A/AA/60) cold-adapted (ca) and ts variant strain has been studied. At the restrictive temperature of 38.5 degrees C, the variant synthesized all the viral polypeptides in normal amounts within the infected cells, but the virions released into the culture fluid contained greatly reduced amounts of the matrix (M1) polypeptide and showed significantly low infectivity per unit hemagglutinin activity. Cell fractionation experiments revealed that incorporation of the M1 polypeptide into plasma membranes of the variant-infected cells was selectively reduced at 38.5 degrees C, whilst it occurred normally at 34 degrees C. The ts reassortants between the A/AA/60 variant and the A/AA/1/80 wild type (wt) strain (non-ts), which had the M gene derived from the wt parent, also showed similar patterns. These results suggest that the ts defect of the variant and its ts reassortants involves the process of incorporation of the M1 polypeptide into the plasma membranes of the infected cells and that this defect is not attributable to the M gene of the variant.     

Long-Term survivor of ruptured hepatocellular carcinoma after two hepatic resections

We report here a long-term survivor of ruptured hepatocellular carcinoma (HCC). A 37-year-old Japanese man complained of sudden abdominal pain after taking an alcoholic drink. Ultrasonographic examination showed a large amount of fluid in the abdominal cavity. Emergency laparotomy was performed. A solid mass showing extrahepatic growth was present in the right lobe of the liver. No active bleeding site was detected, but the tumor was covered with old blood coagula. The tumor was covered with the greater omentum to prevent further hemorrhage. Following assessment of the extent of the tumor and of liver function, delayed hepatectomy was performed. Histological examination indicated the tumor to be HCC. Twenty-six months after initial hepatic resection, partial resection of the liver was performed again for recurrent tumor. The patient has survived without recurrence for more than 5 years. The long survival was due, we believe to the liver being non-cirrhotic, the delayed hepatic resection, and the early detection of the recurrent tumor. Offprint requests to: K. Tanaka