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Biomedical subjects

S Kamiya

Publications and source records attributed to S Kamiya.

At least 163 records · Page 9Linked to original sources
PubMed1986

Latent infection of human ovarian teratocarcinoma cells with human cytomegalovirus. Brief report.

Persistent infection with human cytomegalovirus (HCMV) can be established in cultures of human ovarian teratocarcinoma (PA1) cells, and maintained for more than 200 days. Infected cultures maintained at 34 degrees C (PA1CMV34) and 37 degrees C (PA1CMV37) entered crisis and subsequently displayed massive cytopathic effects (CPE), whereas infected cultures maintained at 32 degrees C (PA1CMV32) and 39 degrees C (PA1CMV39) continued to release small amounts of infectious virus until 240 or 151 days post-infection (p.i.) respectively. PA1CMV32 cultures shifted to 37 degrees C at 258 days p.i. resumed synthesis of infectious virus which resulted in cell destruction, indicating that latent infection with HCMV was maintained in PA1 cells at 32 degrees C. In contrast, PA1CMV39 cells did not produce infectious virus even when cultured at 37 degrees C for more than 100 days after the temperature shift.

Bromodeoxyuridine↗
PubMed1986

Human cytomegalovirus persistent infection in a human central nervous system cell line: production of a variant virus with different growth characteristics.

The susceptibility of human central nervous system cell lines to human cytomegalovirus (HCMV) and the fate of infected cultures were studied. Significant amounts of infectious progeny virus were produced in 118MGC glioma and IMR-32 neuroblastoma, but not in KGC oligodendroglioma cells when the cultures were infected with wild-type virus (HCMVwt) at an m.o.i. of 10 p.f.u. per cell. Further passage of infected 118MGC cells resulted in the establishment of a long-term persistent infection. This infection, designated 118MGC/Towne, continuously produced infectious virus (HCMVpi) with titres ranging from 10(2) to 10(5) p.f.u./10(6) cells up to 360 days post-infection (corresponding to 50 subcultures). Since no temperature-sensitive mutants, defective interfering particles or interferon-like activity were found in the 118MGC/Towne cultures, maintenance of the persistent infection seemed to be due to a balance between the release of infectious virus and the growth of uninfected cells. The HCMVpi produced in long-term persistently infected cultures was shown to be different from the HCMVwt originally used to infect by the following characteristics: HCMVpi replicated slowly and yielded lower amounts of progeny virus than HCMVwt; HCMVpi induced a 73,000 mol. wt. immediate early protein that was not synthesized in HCMVwt-infected cells; HCMVpi had a different DNA structure from that of HCMVwt. These results suggest that HCMVpi is a slower growing variant of HCMVwt and probably plays an important role in the maintenance of the persistent infection.

Cell Division↗
PubMed1985

Effect of dimethyl sulfoxide on interaction of human cytomegalovirus with host cell: conversion of a nonproductive state of cell to a productive state for virus replication.

The effect of dimethyl sulfoxide (DMSO) on the interaction of human cytomegalovirus (HCMV) with host cell was studied. Confluent state of a human rhabdomyosarcoma cell line (A204) showed a much lower susceptibility to HCMV infection when compared to that in subconfluent actively growing cell cultures. Treatment of confluent cultures with DMSO, however, converted many nonproductive cells in these cultures to a productive state for virus replication. Infectious center assay revealed that approximately 100-fold more cells in the compound-treated cultures are able to produce infectious virus. The amount of infectious virus produced in DMSO-treated confluent cultures was enhanced by approximately 10,000-fold over production in untreated cultures and recovered to the level of that produced in subconfluent cultures productive state for virus replication. This cell physiology-dependent inhibition of HCMV replication and enhancement of virus growth by DMSO did not occur with herpes simplex virus type 2. Immunofluorescence staining, gel electrophoresis, and DNA analyses indicate that block of HCMV replication in confluent cultures probably occurs at the level of early transcription or translation of the viral genome. In contrast, in DMSO-treated confluent cultures appreciable amounts of HCMV DNA polymerase (an early virus function), viral DNA, and late antigens were synthesized. Pretreatment of confluent cultures with DMSO enabled the cells to support HCMV replication. In addition, the most effective enhancement by DMSO was found in cultures that had been treated with the compound up to 5 hr after infection. These results suggest that the enhancing effect by DMSO is primarily expressed through some host cellular function(s) and the early stages in virus growth cycle are most likely under control by DMSO action.

Antigens, Viral↗
PubMed1985

Abortive infection with human cytomegalovirus induces an alteration of growth pattern: morphological changes with cytocidal effect in rabbit kidney epithelial cells. Brief report.

Rabbit kidney epithelial cells (RK13) exhibited a cytopathic effect (CPE) characterized by cell rounding after infection with human cytomegalovirus (HCMV). Although HCMV-specific immediate early and early antigens were detected by indirect immunofluorescence techniques, neither late antigens nor infectious progeny virus could be observed in virus-infected RK13 cells. HCMV-infected RK13 cells showed a prolonged doubling time and a decreased saturation density in cell growth compared to uninfected control cells. Moreover, colony forming ability (CFA) of virus-infected cells decreased by approximately 70 per cent compared to that of uninfected cells during the first 24 hours after infection. These results indicate that an abortive infection of RK13 cells with HCMV induces an alteration of growth pattern including morphological changes with cytocidal effect.

Animals↗
PubMed1985

Heavy meromyosin and subfragment-1 from squid mantle myosin, and Ca-sensitivity of their Mg-ATPases.

Heavy meromyosin (HMM) and subfragment-1 (S1) were obtained from squid mantle myosin by tryptic digestion and chymotryptic digestion, respectively. Squid HMM(T) and S1(CT) preparations contained stoichiometric amounts of the two types of light chain subunit; regulatory light chain, LC-2, and essential light chain, LC-1. No difference was detected in the chymotryptic digestibilities of squid mantle myosin in Ca-medium and in EDTA-medium. This is in contrast to the digestibility of scallop adductor myosin. The Mg-ATPase activity of HMM(T) alone and that of acto-HMM(T) were both sensitive to calcium ions. In contrast, the activity of S1(CT) alone and that of acto-S1(CT) were both insensitive to calcium ions. The affinity of HMM(T) for actin was not affected by calcium ions, but the amount of HMM(T) bound to actin was increased by calcium ions from 20% to 60% of the total amount of HMM(T). On the other hand, the actin affinity of S1(CT) and the amount of S1(CT) bound to actin were both unaffected by calcium ions. The role of calcium ions in the regulation of contraction in molluscan muscles is discussed.

Actins↗
PubMed1985

[Shared antigens between BCG and tumor cells--immunotherapy with BCG for mouse tumor].

Cytotoxic activity of anti-BCG rabbit serum (A-BCG) and the antigenic relationship between BCG and tumor cells were studies. A-BCG showed high cytotoxic activity against line 10 tumor cells of guinea pig Strain 2 and Colon 26 tumor cells of BALB/c mouse but not to cells of human bladder cancer (HT 1197, HT 1376). Cell-killing activity of A-BCG against line 10 and Colon 26 was dependent on complement participation. It was also found that Colon 26 cells were heterogenous in their susceptibility to the killing activity of A-BCG. Antigenic studies between BCG and tumor cells were undertaken using on indirect immunofluorescence method and it was found that all tumor cells used in the experiment shared common antigens with BCG. In immunotherapy with BCG for Colon 26 tumors, BCG worked effectively for suppressing tumor growth. However, enhancement of tumor growth in some of the BCG-treated mice was observed.

Animals↗
PubMed1984

Dexamethasone enhances human cytomegalovirus replication in human epithelial cell cultures.

An epithelial human hepatoma cell line (PLC/PRF/5) and a primary epithelial human baby kidney (HBK) cell culture showed restricted growth of human cytomegalovirus (HCMV). Treatment of these two epithelial cell cultures with dexamethasone greatly enhanced their ability to support HCMV replication. Growth kinetic experiments and infectious center assay revealed that in both the hormone-treated cultures infectious progeny virus appeared earlier by 1 or 2 days and 5- or 10-fold more cells are able to produce infectious virus. There was an approximate 50- or 100-fold increase in virus yield compared to that in the untreated control cultures. Enhanced HCMV replication in the hormone-treated cultures was not due to differences in the cell growth or the virus adsorption and was supported by evidence of increased synthesis of HCMV-specific immediate early antigens and DNA.

Carcinoma, Hepatocellular↗
PubMed1984

Enhanced replication of human cytomegalovirus in human fibroblasts treated with dexamethasone.

The effect of glucocorticoid hormones on the replication of human cytomegalovirus (HCMV) was studied in human embryonic lung (HEL) cells. Treatment of cells with pharmacological concentrations of adrenal glucocorticoids such as dexamethasone enhanced HCMV replication; treatment with oestrogenic or androgenic hormones did not do so. In dexamethasone-treated HEL cells there was an approximately tenfold increase in virus yield, with the virus eclipse period shortened by 1 day compared to control cultures. Treatment of cells with the hormone also enhanced plaquing efficiency of the virus by approximately tenfold. As the synthesis of virus-specific immediate early proteins and antigens was notably enhanced together with an increase of HCMV DNA synthesis, it appeared that the early stages of the HCMV replication cycle might be under hormonal control. Moreover, the data presented suggest that the hormonal enhancement of HCMV replication involves specific receptor proteins and requires the synthesis of a specific cellular mRNA(s).

Adsorption↗
PubMed1984

Synthesis of M protein of HVJ (Sendai virus) in rat glial cells is selectively restricted at a non-permissive temperature.

Production of HVJ (Sendai virus) wild-type in rat glial cells was characteristically restricted at high temperature. The synthesis of the M protein was selectively decreased in infected cells at 39 degrees C. This temperature-sensitive (ts) character of HVJ was not observed in infection of LLCMK2 cells or chick embryo fibroblast cells. Newcastle disease virus, mumps virus and vesicular stomatitis virus did not show ts growth in glial cells.

Animals↗