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Biomedical subjects

M Kohmoto

Publications and source records attributed to M Kohmoto.

At least 55 records · Page 3Linked to original sources
PubMed1994

Effects of insertion of multiple AP-1 binding sites into the U3 region of the long terminal repeat of feline immunodeficiency virus.

An oligonucleotide containing multiple AP-1 binding sites was introduced into the regulatory sequence in the long terminal repeat (LTR) of feline immunodeficiency virus (FIV). Chloramphenicol acetyltransferase assay revealed that basal promoter activity of the mutated LTR was higher than that of the wild-type LTR in Crandell feline kidney (CRFK) cells. The mutated LTR was introduced into an infectious molecular clone of FIV and the clone was transfected into CRFK cells. The virus production of the mutant in the cells was as high as that of the wild-type when determined by the reverse transcriptase activity assay. The growth of the mutant virus obtained from the transfected CRFK cells was examined in feline T lymphoblastoid cell lines (MYA-1 and FeL-039 cells) and primary feline peripheral blood mononuclear cells (fPBMCs). The growth was delayed when compared with that of the wild-type virus in all the cells used. Upon examination by polymerase chain reaction, the length of the LTR of the mutant virus was shortened in both MYA-1 cells and fPBMCs. Sequence analysis revealed that the insertion was completely deleted 39 days after infection in the MYA-1 cells.

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PubMed1994

Comparison of biological properties of feline immunodeficiency virus isolates using recombinant chimeric viruses.

The biological properties of homogeneous populations of feline immunodeficiency viruses derived from infectious, molecular clones of the TM1, TM2 and Petaluma strains were compared. Differences in infectivity for Crandell feline kidney (CRFK) cells, and in syncytium formation and replication kinetics in a feline T lymphoblastoid cell line (MYA-1 cells) were observed. To investigate the basis of these differences between the TM2 and Petaluma strains, we first compared the basal promoter activity of the long terminal repeat which is a highly divergent region, but no significant difference in activities was found in CRFK cells. We then constructed two recombinant chimeric clones which carry gag, pol, vif, and ORF A from the heterologous virus. From analyses using the chimeric clones, it was revealed that efficient virus growth in CRFK cells and MYA-1 cells was regulated by the gag, pol, vif and ORF A regions, whereas viral determinants of infectivity for CRFK cells, and syncytium formation and cytopathogenicity in MYA-1 cells, were located in the env region.

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PubMed1994

Plasma membrane fluidity during regeneration and atrophy of the rat liver following portal branch ligation.

Dynamic changes in liver plasma membrane fluidity caused by regeneration and atrophy were assessed in rats following portal branch ligation (PBL). The portal branch, which perfuses 70% of the liver, was ligated with 5-0 prolene, and liver plasma membranes were isolated by ultracentrifugation. The membrane fluorescence polarization was measured as an index of membrane fluidity using 1,6-diphenyl-1,3,5-hexatriene (DPH) as the probe dye. In nonligated lobes, a significant decrease in fluorescence polarization was observed 12 and 24 h after PBL (0.171 +/- 0.004, p < 0.01 and 0.165 +/- 0.005, p < 0.001, respectively) as compared to the controls (0.181 +/- 0.002). The fluorescence polarization values then gradually returned to near control levels. In contrast, in the ligated lobes, the fluorescence polarization had increased by 12 hours after PBL (0.196 +/- 0.002, p < 0.01), and remained significantly elevated (p < 0.01) for up to 1 week after PBL, gradually returning to control levels within 3 weeks. The membrane composition was also evaluated by analyzing the cholesterol/phospholipid (C/P) ratio. A significant increase in the C/P ratio was detected in the ligated lobes 12 h and 3 days after PBL, but there was no significant difference in fluorescence polarization values between nonligated lobes and controls. These results suggest that alterations in membrane fluidity play an important role in the regenerative and atrophic processes of the liver following portal branch ligation.

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PubMed1994

Comparison of the Rev transactivation of feline immunodeficiency virus in feline and non-feline cell lines.

The Rev protein of feline immunodeficiency virus (FIV) differentially transactivates the expression of viral structural proteins by allowing the accumulation of unspliced and singly spliced viral mRNA in cytoplasm via the Rev response element (RRE) at the end of env. To investigate the role of rev gene of FIV for the virus life cycle and cell tropism, we constructed the Rev expression plasmids, and functional activity of the Rev was assayed by using chloramphenicol acetyltransferase (CAT) assay system in feline and non-feline cell lines. Although the FIV Rev protein showed high transactivity to result in enhanced CAT production in a feline cell line, the productions of the CAT in non-feline cell lines were significantly lower than that in the feline cell line. These results indicate that specific cellular factor(s) present in feline cell line is required for the FIV Rev full-action and also suggest that the Rev action plays one of the important roles in determining the FIV cell tropism.

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PubMed1994

Growth properties of a feline immunodeficiency virus mutant which lacks an AP-1 binding site in primary peripheral blood mononuclear cells.

Thirty-one base pairs (bp) containing putative AP-1 and AP-4 binding sequences in the U3 region of feline immunodeficiency virus (FIV) long terminal repeat (LTR) were deleted from an infectious molecular clone of FIV for construction of a mutant virus, and the replication rate and the cytopathogenic activity of the virus were compared with those of the wild type virus in concanavalin-A (Con-A) stimulated primary feline peripheral blood mononuclear cells (fPBMCs). It was found that the replication rate and cytopathogenic activity of the mutant were almost the same as those of the wild type. The deletion of the mutant virus was stable during the infection experiments. From these data, we concluded that the 31 bp fragment in the LTR is not required for the replication of FIV in Con-A stimulated primary fPBMC.

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PubMed1994

Comparative functional analysis of the various lentivirus long terminal repeats in human colon carcinoma cell line (SW480 cells) and feline renal cell line (CRFK cells).

Basal promoter activities of various lentiviral long terminal repeats (LTRs) in a human colon carcinoma cell line (SW480 cells) and a feline renal cell line (CRFK cells) were examined by the chloramphenicol acetyltransferase (CAT) assay using the LTR-CAT reporter plasmids. In SW480 cells, the basal promoter activities induced by LTRs of visna virus, caprine arthritis-encephalitis virus (CAEV), and simian immunodeficiency virus (SIVAGM) were moderate, and those induced by LTRs of human immunodeficiency virus (HIV) type 1 (HIV-1) and HIV type 2 (HIV-2) were low. However, the activity induced by the LTR of feline immunodeficiency virus (FIV) was extremely low. In CRFK cells, the basal promoter activities induced by LTRs of visna virus, CAEV and SIVAGM were relatively high, and those induced by LTRs of HIV-1, HIV-2 and FIV were moderate. From these data, although the structure of the LTR of FIV is reported to be similar to that of visna virus and CAEV, the function of the LTR of FIV is rather quite different from that of the LTR of these viruses.

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PubMed1993

Altered fluidity of liver plasma membranes following partial hepatectomy in rats.

The fluidity of liver plasma membranes was assessed during regeneration following partial hepatectomy in rats. Fluorescence polarization was measured using 1,6-diphenyl-1,3,5-hexatriene to evaluate the fluidity of liver plasma membranes. The fluorescence polarization value of liver plasma membranes of control rats was 0.189 +/- 0.005 (mean +/- SEM). The fluorescence polarization values decreased initially after a 70% hepatectomy [0.176 +/- 0.003 at 3 hr and 0.174 +/- 0.004 at 6 hr (P < 0.01)] at 3 and 6 hours, but then recovered to preoperative levels (0.181 +/- 0.004, 0.189 +/- 0.004, 0.189 +/- 0.003, 0.193 +/- 0.003, 0.200 +/- 0.002, 0.208 +/- 0.007, and 0.190 +/- 0.003 at 12, 24, 36, 48, 72, 96 hr, and 7 days, respectively). Flow cytometric analysis using anti-bromodeoxyuridine (BrdU) monoclonal antibody was used to investigate the cell kinetics of the regenerating liver after 70% hepatectomy. The proportion of S-phase incorporating BrdU was not increased at 6 or 12 hr, but it then increased to peak of 27.9 +/- 1.9% at 24 hr. Subsequently, at 48, 72, and 168 hr, the proportion decreased to 8.5 +/- 0.6, 5.9 +/- 0.3, and 1.0 +/- 0.1%, respectively. The ratio of phospholipid to cholesterol contents of liver plasma membranes following partial hepatectomy did not significantly change in spite of markedly altered membrane fluidity. Thus, the alteration of membrane function occurs in conjunction with the initiation of the regeneration process following partial hepatectomy. It is suggested that the alteration of membrane fluidity plays an important role in the homeostatic response for cell proliferation.

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PubMed1993

Feline CD4 molecules expressed on feline non-lymphoid cell lines are not enough for productive infection of highly lymphotropic feline immunodeficiency virus isolates.

To investigate whether the feline CD 4 (fCD4) molecules are involved in infections of highly lymphotropic feline immunodeficiency virus (FIV) isolates, we expressed fCD4 stably on Crandell feline kidney cells and Felis catus whole foetus 4 cells by transfection of a cDNA encoding the fCD4 glycoprotein, and then infected them with TM 1 and TM 2 strains of FIV, which are unable to infect these cells productively. In spite of fCD 4 being expressed on these cells, no virus production was observed. This result indicates that fCD 4 expression alone cannot induce a productive infection of the FIV TM 1 and TM 2 strains.

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