Search PubMed⌕ Search

Biomedical subjects

M Kohmoto

Publications and source records attributed to M Kohmoto.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of cholecystokinin and carbachol on membrane fluidity in pancreatic acini.

The effects of pancreatic secretagogues on the membrane fluidity of pancreatic acini were investigated using 1-[4-(trimethylammonium)phenyl]-6-phenyl-1,3,5-hexatriene iodide as a probe. Two kinds of pancreatic secretagogues, one category of which induces acute pancreatitis (cholecystokinin and carbachol) and another which does not induce acute pancreatitis (bombesin, CCK-JMV-180, and secretin), as well as lecithin were used to investigate the effect of changes in membrane fluidity of acini. Our study revealed that the membrane fluidity of the pancreatic acini was unaffected by a physiological dose (10(-11) M) of cholecystokinin. However, stimulation with a supramaximal dose of cholecystokinin (10(-8) M) increased membrane fluidity markedly within 20 min. Membrane fluidity increased dose-dependently with increasing CCK stimulation. A supramaximal dose of cholecystokinin also induced bleb formation and increased LDH release. These phenomena were blocked by simultaneous incubation with CR1505 (Loxiglumide), a potent antagonist of peripheral cholecystokinin receptors. A supramaximal dose of carbachol (10(-3) M) also induced increases in the membrane fluidity. Pancreatic secretagogues that do not induce acute pancreatitis did not induce alterations in membrane fluidity. Lecithin increased both membrane fluidity and LDH release. These observations suggest that this increase in membrane fluidity of the pancreatic acini may be related to membrane alteration and to functional damage of the acini. These observations [correction of observation] can serve as a window to detect the development of acute pancreatitis at an early stage.

Animals↗
PubMed1996

Regulatory properties of the integrated long terminal repeat of the feline immunodeficiency virus.

To examine the regulatory properties of feline immunodeficiency virus (FIV) long terminal repeat (LTR) integrated into host chromatin, Crandell feline kidney cells were stably transfected with the FIV LTR that directs the bacterial chloramphenicol acetyltransferase (CAT) gene. Using these cells, we examined the effects of treatment with several chemical agents, infection with feline viruses, or transfection with effector plasmids expressing FIV gene products on FIV LTR-directed gene expression. Among them, treatment with the phorbol ester (a strong activator of protein kinase C), forskolin (an inducer of cyclic-AMP), 5-azacytidine (a DNA methylation antagonist), or infection with feline herpesvirus type 1 (FHV-1), resulted in induction of CAT activity in the cells. These results suggest that the integrated FIV LTR is stimulated by cellular transcriptional factors induced by phorbol ester, forskolin and FHV-1, and is also inactivated by DNA methylation. Furthermore, this permanent cell line can be used as a screening system of activators of the FIV LTR.

Animals↗
PubMed1996

Feline immunodeficiency virus can infect a human cell line (MOLT-4) but establishes a state of latency in the cells.

Infectivity of feline immunodeficiency virus (FIV) in feline and human lymphoblastoid cell lines was examined using homogeneous populations of FIV derived from infectious molecular clones of strains TMZ and Petaluma, and two recombinant chimeric clones carrying gag, pol, vif and ORF-A from the heterologous virus. FIV from the clones with the env region of the Petaluma strain was shown to infect and establish provirus in a human lymphoid cell line (MOLT-4), although the FIV-infected cells did not produce any infectious viruses. By treatment of the infected MOLT-4 cells with a phorbol ester, infectious virus was rescued. To examine which stage of the life-cycle of FIV is blocked in these cells, we analysed transcription of FIV-14 in the cells by RT-PCR. FIV-specific RNA expression could not be detected. These results strongly suggest that latency of the virus in MOLT-4 cells is due to a failure in transcription.

Antigens, Viral↗
PubMed1996

Roles of the auxiliary genes and AP-1 binding site in the long terminal repeat of feline immunodeficiency virus in the early stage of infection in cats.

To examine the roles of auxiliary genes and the AP-1 binding site in the long terminal repeat of feline immunodeficiency virus (FIV) in vivo, three mutant viruses, which are defective in the vif gene ([delta]vif), ORF-A gene (deltaORF-A), and AP-1 binding site (deltaAP-1), and wild-type virus as a positive control were separately inoculated into three specific-pathogen-free cats. These cats were assessed by measuring the number of proviral DNA copies in peripheral blood mononuclear cells (PBMCs), the CD4/CD8 ratio and antibody responses to FIV for 16 weeks and then examining histological changes at necropsy. Although viral DNAs were detected in PBMCs from all 12 cats to various degrees until 16 weeks postinoculation, no virus was recovered from PBMCs of cats infected with (delta)vif virus during the observation period. However, a very weak antibody response was induced in one cat infected with the (delta)vif virus. In contrast, despite the successful recovery of virus from both groups of cats infected with deltaORF-A and deltaAP-1 virus, antibody responses and decrease in the CD4/CD8 ratio in the groups were milder than those in cats infected with wild-type virus. Furthermore, the numbers of proviral DNA copies in PBMCs from the two groups were not able to reach the level in cats infected with wild-type virus during the observation period. From these results, we conclude that these mutant viruses are still infectious for cats but failed in efficient viral replication and suggest that these auxiliary genes and enhancer element are important or essential to full viral replication kinetics and presumably to full pathogenicity during the early stage of infection in vivo.

Animals↗
PubMed1996

Persistence of high virus neutralizing antibody titers in cats experimentally infected with feline immunodeficiency virus.

The development of virus neutralizing (VN) antibody is one of the most effective host defense mechanisms against virus infection. In the present study, we developed a new VN assay against feline immunodeficiency virus (FIV) using a feline T-lymphoblastoid cell line, MYA-1 cells, based on inhibition of viral reverse transcriptase production. This assay is applicable to strains of FIV which can not infect CRFK cells. By using the assay, we examined long-term responses of VN antibody in cats experimentally infected with FIV. VN antibody titers increased progressively during first 30 weeks post inoculation and remained at high titers thereafter for 7 years of observation periods.

Animals↗
PubMed1995

The C/EBP site in the feline immunodeficiency virus (FIV) long terminal repeat (LTR) is necessary for its efficient replication and is also involved in the inhibition of FIV LTR-directed gene expression by pseudorabies virus ICP4.

We investigated effects of site-specific mutation of the putative C/EBP binding site in the feline immunodeficiency virus (FIV) long terminal repeat (LTR) on the basal promoter activity in Crandell feline kidney (CRFK) cells and on replication efficiency in CRFK cells and a T-lymphoblastoid cell line, MYA-1 cells. Mutation of the C/EBP site reduced the basal promoter activity in CRFK cells and prevented efficient FIV replication in both CRFK and MYA-1 cells. Gel-mobility-shift assay using nuclear extracts from CRFK and MYA-1 cells revealed that the nuclear factor(s) actually binds to the C/EBP site, but there was a clear difference in the binding patterns to the C/EBP site between CRFK and MYA-1 cell nuclear proteins. Furthermore, we demonstrated that the C/EBP site is necessary for inhibition of FIV LTR-directed gene expression by pseudorabies virus (PRV) ICP4. The C/EBP site is sufficient to confer inhibitory effect by PRV ICP4 on heterologous promoters. These data suggest that the C/EBP site in the FIV LTR is important for the positive regulation of FIV gene expression and replication and is also required for the negative regulation of FIV gene expression by PRV ICP4.

Animals↗
PubMed1995

Significance of altered fluidity of plasma membranes of the liver and kidney in rats with sepsis.

The present study was conducted to investigate changes in plasma membrane fluidity of the liver and kidney in sepsis, which is the main cause of multiple organ failure. Male Wistar rats weighing 200-250 g were used in all experiments. Sepsis was induced by cecal ligation and puncture. As a control, a sham operation was performed. The time course of plasma membrane fluidity of the liver and the renal cortex in septicemic rats or in controls was studied. To evaluate the fluidity, fluorescence polarization was measured using 1,6-diphenyl-1,3,5-hexatriene. The fluorescence polarization values of liver plasma membranes increased after cecal ligation and puncture: 0.183 +/- 0.004 (mean +/- SEM), 0.194 +/- 0.008, 0.206 +/- 0.003, and 0.210 +/- 0.002 at 0, 24, 48, and 72 hr, respectively. Corresponding values for membranes of the renal cortex increased in a similar fashion. To determine whether factors involved in cell membrane damage exist in blood, the direct effects of lipopolysaccharide (LPS), platelet-activating factor (PAF), and serum from normal rats or from septicemic rats on membrane fluidity were studied. The fluorescence polarization of plasma membranes of the liver or renal cortex to which septicemic rat serum was added was higher than that of plasma membranes to which normal rat serum was added. The fluorescence polarization of liver plasma membranes was increased by LPS, but that of plasma membranes of the renal cortex was slightly decreased. In addition, the fluorescence polarization of liver plasma membranes was increased by PAF, but that of plasma membranes of the renal cortex was decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The feline herpesvirus type 1 ICP4 down-regulates feline immunodeficiency virus long terminal repeat (LTR)-directed gene expression via the C/EBP site in the LTR.

We investigated effects of feline herpesvirus type 1 (FHV-1) ICP4 on feline immunodeficiency virus (FIV) long terminal repeat (LTR)-directed gene expression by transient transfection assay in Crandell feline kidney cells. We demonstrated that FHV-1 ICP4 significantly stimulates the FIV LTR after introduction of site-specific mutation of the C/EBP site in the LTR, and the C/EBP site is sufficient to confer inhibitory effects by FHV-1 ICP4 on a heterologous promoter. These results indicate that FHV-1 ICP4 possesses both ability to transactivate FIV LTR-directed gene expression and to down-regulate the FIV LTR via the C/EBP site.

Animals↗