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Biomedical subjects

Y Ohta

Publications and source records attributed to Y Ohta.

At least 541 records · Page 30Linked to original sources
PubMed1993

Dorsal root and dorsal column mediated synaptic inputs to reticulospinal neurons in lampreys: involvement of glutamatergic, glycinergic, and GABAergic transmission.

This study was aimed at characterizing the inputs from dorsal roots and dorsal columns to reticulospinal neurons within the posterior rhombencephalic reticular nucleus in the lamprey. The in vitro isolated brainstem and spinal cord preparation was used. Microstimulation of dorsal roots and columns on both sides induced, in identified reticulospinal neurons, synaptic responses which consisted of large IPSPs mixed with excitation, particularly from stimulation on the ipsilateral side. When the spinal cord was selectively exposed to kynurenic acid or to Ca2+ free Ringer's containing 2mM Mn2+, synaptic responses to stimulation of dorsal roots and columns were not modified, whereas the same responses were abolished when the brainstem was exposed selectively to kynurenic acid, thus suggesting that the responses were carried by long fibres ascending directly to the brainstem. The excitatory and inhibitory synaptic responses are relayed by interneurons located in the brainstem. The ascending excitatory inputs to inhibitory interneurons and, most likely, also to excitatory interneurons, use excitatory amino acid transmission. Inhibitory responses were abolished by adding the glycinergic antagonist strychnine (5 microM) to the physiological solution, thus suggesting that inhibitory interneurons use glycine transmission. The synaptic transmission was depressed by (-)-baclofen, a GABAB agonist, probably acting at a presynaptic site. Taken together, the present results suggest that dorsal root and dorsal column stimulations give rise to disynaptic inhibition and excitation of reticulospinal neurons mediated by excitatory and inhibitory amino acid transmission via brainstem interneurons.

Animals↗
PubMed1993

Anatomical and physiological study of brainstem nuclei relaying dorsal column inputs in lampreys.

The course and sites of termination of dorsal column fibres in the lamprey brainstem are described along with their brainstem relays projecting to reticulospinal neurons. Dorsal column fibres ascend to the brainstem level where they intermingle with cells located in the alar plate close to the obex, a location that is analogous to that of the dorsal column nucleus in other vertebrates. Some dorsal column fibres continue further rostrally where they reach the octavolateralis and octavomotorii nuclei. Finally, a small contingent of fibres reach the cerebellum. Injections of cobalt-lysine into the posterior rhombencephalic reticular nucleus retrogradely label neurons within the dorsal column nucleus and within the octavolateralis and octavomotorii nuclei. Microstimulation of the dorsal column nucleus on either side elicits monosynaptic inhibitory responses in reticulospinal neurons while stimulation of octavolateralis and octavomotorius nuclei elicits excitation. By using intracellular recordings, it was shown that neurons within these alar plate nuclei receive monosynaptic inputs from the dorsal columns. It is thus proposed that disynaptic inputs from dorsal columns to reticulospinal neurons are relayed by these alar plate neurons: inhibition is relayed mainly by neurons in dorsal column nuclei and excitation by neurons in the octavolateralis and octavomotorii nuclei.

Afferent Pathways↗
PubMed1993

Hepatitis C virus plus- and minus- strand RNA in hepatocellular carcinoma and adjoining nontumorous liver.

The presence of hepatitis C virus (HCV) RNA in serum and liver tissue was examined in seven patients with hepatocellular carcinoma (HCC), using the reverse transcriptase-polymerase chain reaction method with primers for the 5'-noncoding region. Plus-strand HCV-RNA was detected in the serum and liver tissue (both cancerous and noncancerous tissue) of all five patients who were positive for anti-HCV antibodies (C100-3 and P22) and was not detected in both of two patients who were negative for anti-HCV antibodies. Minus-strand HCV-RNA was only detected in the liver tissue (cancerous and noncancerous portion) of the five anti-HCV antibody-positive patients. The relative liver tissue content of minus-strand HCV-RNA ranged from 1 to 100 time less than that of plus strand HCV-RNA in cancerous and noncancerous tissue in each patient, respectively. There was no similar tendency in the HCV-RNA content between the cancerous and noncancerous portions of the liver in each patient. These results suggest that HCV exists and replicates in HCC tissue and may have some role in the development of HCC.

Alcoholism↗
PubMed1993

Antigenicities of Group I and II hepatitis C virus polypeptides--molecular basis of diagnosis.

Comparative nucleotide sequence studies on the putative NS3 and NS4 regions of the genomes of hepatitis C viruses (HCV) have revealed that there are at least two groups of HCV, group I and group II. The cDNA clone E, corresponding to a boundary between the NS3 and NS4 (NS3-4) region of the group II HCV genome, encodes antigens that react to antibodies specific to group II HCV (Tsukiyama-Kohara et al. (1991) Virus Genes 5, 243-254). To understand the molecular basis of the group-specific antigenicity of HCV peptides, the predicted amino acid sequences around the NS3-4 region of our group II HCV cDNAs were compared with those of other HCV isolates. The analysis revealed the presence of group-specific amino acids in this peptide region. Evolutionary analysis of nucleotide sequences within this region of these HCV isolates also led to the same classification. A similar result was obtained by sequence analysis of cloned cDNAs corresponding to the core region. A cDNA of the group II HCV core region was prepared by polymerase chain reaction from the cDNA synthesized with group II-specific primer complementary to the NS3-4 region. The products directed by the cDNA of the core region did not have group-specific antigenicity. The NS3 peptide region also appeared not to carry group-specific antigens. Our results indicate that most HCV isolates can be classified into either group I or II, and that the existence of two groups of HCV does not disturb HCV diagnosis as long as core and/or NS3 peptides are used to detect HCV antibodies.

Amino Acid Sequence↗
PubMed1993

Longer transplanted heart allograft survival in rats without immunosuppressants after intrathymic myocardial cell inoculation in the neonatal period.

In order to induce immunological tolerance, intrathymic inoculation of incompatible donor myocardial cells in rats was performed in the neonatal period. Isolated myocardial cells harvested from donor rat hearts were inoculated into the thymus of incompatible neonatal recipient rats without administration of immunosuppressive agents. Ten weeks later, the hearts from the donors were transplanted heterotopically to these pretreated rats. The animals were sacrificed on the 7th day of heterotopic transplantation and were examined histopathologically. The results showed no early rejection in the group in which intrathymic myocardial cell inoculation had been performed in the neonatal period. Immunohistochemical staining for myoglobin of the thymus from the inoculated recipient revealed that the donor myocardial cells continued to survive. The longest proven graft survival in this series, thus far, was 60 days, while it was only 7 days in the control group.

Animals↗
PubMed1993

Present status of autoimmune hepatitis in Japan.

The clinical and biochemical features of patients with autoimmune hepatitis (AIH) in Japan during the 15-year period, 1975 to 1990, were evaluated by a nationwide survey using a questionnaire prepared by the Intractable Diseases Study Group organized by the Ministry of Health and Welfare. Data on a total of 866 cases with AIH were collected and analyzed, and of these, 632 cases underwent follow-up study. AIH was predominant in females, with a male:female ratio of approximately 2:19. Biochemical investigation on the occasion of the first examination showed abnormalities of liver function tests, including increased serum total bilirubin, transaminase activity and gamma-globulin levels. The main complications of autoimmune diseases were rheumatoid arthritis, Sjögren's syndrome and chronic thyroiditis. All patients with complications were female. Of 253 AIH patients, 50 were positive for anti-C100-3 antibody. ICG clearance and platelet count, which are stigmata of liver cirrhosis, were the main factors of prognostic importance in AIH. Therefore, early diagnosis prior to the development of liver cirrhosis is important to improve the prognosis of AIH.

Autoimmune Diseases↗
PubMed1993

Anti-HCV immunoglobulin M antibody in patients with acute and fulminant hepatitis C.

To determine whether detection of IgM type antibody (Ab) to hepatitis C virus (HCV) antigens would be useful in the early diagnosis of type C acute hepatitis (AH) or fulminant hepatitis (FH), we assayed serum IgM and IgG type Abs to nonstructural (C100-3) and core (AR 142) antigens of HCV in patients with type C hepatitis. Of 8 patients with AH, anti-C100-3 IgM and anti-AR 142 IgM were positive in 1 and 6 patients, respectively. Early appearance of Anti-AR 142 IgM was observed in all of these 6 patients, and in 4 anti-AR 142 IgM was the sole serological marker of HCV infection during the acute-phase. However, the anti-AR 142 IgM response was rather persistent, not transient in AH. Only 1 patient with AH was positive for anti-C100-3 IgM, and this patient became positive for anti-AR 142 IgM 3 months before the appearance of anti-C100-3 IgM. The titre of anti-AR 142 IgM in AH was not dependent on the activity of hepatitis or on the duration. Anti-AR 142 IgM was also positive in 30-75% cases with chronic HCV carriers. Thus it is suggested that the detection of anti-AR 142 IgM may contribute to the early diagnosis of type C AH, although the appearance of this marker in chronic HCV carriers limits its usefulness as the sole serological marker of acute HCV infection.

Acute Disease↗
PubMed1993

Antimutagenicity of cell fractions of microorganisms on potent mutagenic pyrolysates.

The inactivation of 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 2-amino-6-methyldipyrido[1,2-a: 3',2'-d]imidazole (Glu-P-1) by binding of mutagenic pyrolysate to fractions of microorganisms (their desmutagenic and bio-antimutagenic activity) was investigated. All strains bound Trp-P-1 effectively, but Glu-P-1 to a lesser extent. The Gram-negative bacteria (GNB) could bind about 10-20 micrograms/mg of Trp-P-1 more than the Gram-positive bacteria (GPB), and about 50-60 micrograms/mg more than the yeasts. The cell wall skeletons of all strains tested had great binding ability, but in the cytoplasm of all strains tested it was lower. The peptidoglycan, outer membrane, and glucan isolate from the cell wall skeletons showed the highest binding ability to Trp-P-1. The cell wall skeletons of the tested strains greatly inhibited the mutagenicity induced by Trp-P-1, and to a lower extent that of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). Although the cultured broth and solution of cells extracted by phosphate buffer (pH 7.0) showed antimutagenicity against Trp-P-1, this activity was lower than the binding of Trp-P-1 to the cells. The cultured broth and freeze-dried cytoplasms of yeast cells showed bio-antimutagenicity towards Trp-P-1, but those of all bacteria tested did not.

Amines↗
PubMed1993

Anticlastogenic and bio-antimutagenic activity of cultured broth of Saccharomyces cerevisiae 28 on mutagens.

The possible anticlastogenic activity and bio-antimutagenic mechanism of the cultured broth of Saccharomyces cerevisiae 28 were examined using in in vivo and in vitro test systems. In the Ames test with Salmonella typhimurium TA100 (SD-) and in the umu-test with S. typhimurium TA1535/psk1002, the cultured broth of S. cerevisiae 28 showed bio-antimutagenic activity against mutagenicity induced by 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). The cultured broth also showed bio-antimutagenic activity towards reverse mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Escherichia coli B/r WP2 trp-, but not by UV radiation. It is clear that the cultured broth could inhibit base substitution mutations induced by mutagens. Using mitomycin C (MMC) as a mutagen, the micronucleus test (with bone marrow cells of mice) showed anticlastogenic action when the cultured broth was given orally to mice. Micronucleated polychromatic erythrocytes induced by the mutagen were reduced by about 47% by the cultured broth.

Antimutagenic Agents↗
PubMed1993

Water transport model during CAPD: determination of parameters.

To minimize the total amount of glucose required for removing the same volume of water as a bolus, a continuous infusion of glucose during CAPD was proposed and studied. Both a computer simulation of water transport through the peritoneal membrane and in vivo assessment with rats were carried out to evaluate the feasibility of the newly proposed mathematical model in which lymphatic drainage of dialysate from the peritoneal cavity to lymphatic system was considered in addition to conventional water transport. Mass transport area coefficients (KA) of 0.041 to 0.063 ml/min/100 g body wt and 0.045 to 0.066 ml/min/100 g body wt were measured for glucose and urea during CAPD with male Wistar rats. Hydraulic conductivity of peritoneal membrane (Lc) was 7.9 x 10(-5) to 1.5 x 10(-4) ml/min/mm Hg/100 g body wt, which was calculated by a linear relationship between volume and osmotic pressure. Simulated water transport model using determined parameters indicated that the ratio of lymphatic transport to convective transport would be changeable in CAPD with glucose infusion at varying infusion rates, while up to 16% of the glucose uptake could be reduced compared with that of the common CAPD at the same dwell time.

Animals↗
PubMed1993

Effect of chronic alcohol intake on rat liver microcirculation assessed by the multiple indicator dilution technique.

To study the hepatic microcirculatory disturbance in alcoholic liver injury, rats were chronically (8-12 weeks) fed with alcohol via a gastric fistula according to the method of Tsukamoto and French (1986). The hepatic microcirculation was studied by measuring the sinusoidal volume (SV) and the apparent space of Disse (DS) volume using a multiple-indicator dilution technique. Both the SV and the DS volume were significantly decreased in the alcohol-fed rats at 8-12 weeks despite the absence of microscopically detectable hepatic fibrosis. Similar changes were noted in the alcohol-fed and control rats regarding expansion of the SV and the DS volume with alterations in portal pressure. However, since the volumes in the alcohol-fed group increased with the increase of portal pressure, they maintained a steady difference from the control values. These results suggested that the decrease of the SV and the DS volume may have been secondary to compression caused by steatosis and/or hepatocyte enlargement, although a possible role for microscopically undetectable hepatic fibrosis could not be ruled out.

Alcoholism↗
PubMed1993

Assay of serum interleukin 8 levels in patients with alcoholic hepatitis.

Studies were performed to evaluate the role of interleukin 8 (IL-8) in the pathogenesis of alcoholic hepatitis. Using a recently developed sensitive and specific enzyme-linked immunosorbent assay, we measured serum IL-8 levels in patients with alcoholic hepatitis. The mean serum IL-8 level was increased significantly in patients with alcoholic hepatitis compared with normal controls (P < 0.05). It was of interest to note that serum IL-8 levels were increased transiently after abstinence from alcohol in patients with alcoholic hepatitis. These findings suggest that there may be a correlation between IL-8 and alcoholic hepatitis.

Adult↗
PubMed1993

Prevalence of risk factors for sleep apnea in Japan: a preliminary report.

A final goal of the present study is to estimate the prevalence of sleep apnea in the general population of Japan. As the first step, the detailed questionnaires were sent out to the presumably healthy subjects who underwent regular medical checkups at four hospitals in different cities of Japan. The questionnaires included queries about difficulties in initiating and maintaining sleep, habitual snoring, parasomniac symptoms, excess daytime sleepiness, any present illness, consumptions of cigarettes and alcohol and so on. A total of 3,243 replies were obtained so far (2,029 male and 1,214 female; mean age = 50 years). The results were consistent among the four hospitals, and the prevalences of risk factors were as follows: habitual snoring was reported by 12.8-16.0%, excess daytime sleepiness by 8.1-9.4% and frequent awakenings by 7.3-12.6%, respectively. The prevalence of systemic hypertension ranged from 5.3% to 12.9%. Polysomnographic studies are being performed on the possible cases of sleep apnea who were sorted out by the questionnaires.

Adult↗
PubMed1993

Developmental changes in mouse placental cells from several stages of pregnancy in vivo and in vitro.

Developmental changes in mouse placentae from the 6th to the 18th day of pregnancy were studied in vivo and in vitro. Placental volume increased from the 6th to the 18th day of pregnancy; however, the total number of cells per placenta reached a plateau on the 14th day. Decidual cells were predominant in the placenta on the 6th day. Placentae obtained from the 10th to the 18th day contained decidual cells, trophoblastic (labyrinth and spongiotrophoblast) cells, and trophoblast giant cells. Decidual cells increased in number from the 6th to the 10th but decreased on the 14th day, whereas trophoblastic cells increased linearly until the 14th day. Two types of placental cells were distinguished in vitro: small fibroblast-like cells and large flattened cells containing 2-3 nuclei. The large cells reacted to anti-desmin antibody, indicating their decidual character. The small cells reacting to anti-keratin antibody appeared to be trophoblastic cells. Decidual cells from all days of gestation were nonproliferative, regressing with time in culture. 17 beta-Estradiol (E, 10(-9) and 10(-8) M), progesterone (P, 10(-10), 10(-9), and 10(-8) M), and a combination of E and P (10(-9) M each) stimulated proliferation of the trophoblastic cells only from the 6th and the 10th days. Keoxifene (2 x 10(-7) M), but not tamoxifen, significantly inhibited the E-induced proliferation of the trophoblastic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗