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Biomedical subjects

C Hamada

Publications and source records attributed to C Hamada.

At least 55 records · Page 3Linked to original sources
PubMed1992

Comparative study on the behavioral and EEG changes induced by diazepam, buspirone and a novel anxioselective anxiolytic, DN-2327, in the cat.

Behavioral and EEG effects of 2-(7-chloro-1,8-naphthyridin-2-yl)-3-[(1,4)-dioxa-8-(azas piro-[4.5]dec-8- yl)carbonylmethyl]isoindolin-1-one (DN-2327; 1, 5 and 20 mg/kg p.o.) were compared to those of diazepam (0.2 and 1 mg/kg p.o.) and buspirone (1 and 5 mg/kg p.o.) in freely moving cats. DN-2327 did not affect motor coordination or the relative percentages of the three sleep-wakefulness stages. Diazepam (1 mg/kg) increased wakefulness and non-REM sleep, and buspirone (5 mg/kg) also increased wakefulness and decreased REM sleep. In addition, diazepam (1 mg/kg) caused severe motor disturbance, but buspirone did not. The cortical EEG power density spectra during wakefulness were changed almost dose-dependently by DN-2327 (decreased: 2-7.75 Hz; increased: 20-49.75 Hz), and dose-dependently by diazepam (decreased: 2-7.75 Hz; increased 13-49.75 Hz) and buspirone (decreased: 4-9.75 and 13-19.75 Hz). The effect of DN-2327 on the cortical EEG varied with the sleep-wakefulness stage. The power of the 4- to 7.75-Hz frequency (theta) band of the hippocampal EEG during wakefulness was decreased by diazepam and buspirone but not by DN-2327, while the peak frequency of its spectra was decreased only by diazepam. On the other hand, during non-REM sleep, DN-2327 decreased the power of the theta band as did diazepam. These results indicate that the behavioral and EEG effects of DN-2327 differ completely from those of buspirone and considerably from those of diazepam and that the EEG effect of DN-2327 varies with the sleep-wakefulness stage.

Animals↗
PubMed1990

Plasma atrial natriuretic peptide during hemodialysis with or without fluid removal.

Plasma immunoreactive human atrial natriuretic peptide (hANP) levels were measured in 9 patients with chronic renal failure treated with maintenance hemodialysis in order to evaluate the effects of fluid removal and osmotic pressure. Under hemodialysis without fluid removal plasma hANP levels remained unchanged, but the levels were significantly decreased during extra-corporeal ultrafiltration (p less than 0.01). The present study provided strong evidence that the fall in plasma hANP levels in hemodialysis patients is mainly due to the reduction in circulating plasma volume.

Adult↗
PubMed1989

Propagation of hepatitis A virus in hybrid cell lines derived from marmoset liver and Vero cells.

To establish monkey liver cell lines with a high susceptibility to hepatitis A virus (HAV), marmoset (Saguinus labiatus) liver cells were fused with Vero cells deficient in hypoxanthine-guanine phosphoribosyltransferase and the resulting hybrid cells were selected in HAT medium. Of four hybrid cell lines obtained (S. 1a/Ve-1 to -4), three (S. 1a/Ve-1, -3 and -4) were equally susceptible to HAV infection. When inoculated with a virus isolated from marmoset liver tissue (10% liver tissue extract) or a faecal virus (10% stool extract) from a human hepatitis A patient, all susceptible cell lines showed a significant elevation of viral antigen activity as seen in radioimmunoassay and/or immunofluorescent antibody assays, at 4 to 6 weeks post-infection (p.i.) with the liver-derived inoculum and at 6 to 8 weeks p.i. with the stool-derived inoculum. In S. 1a/Ve-1 cells, a representative of the susceptible hybrid cell lines, full adaptation of HAV (liver tissue virus concentrate) to cell culture was attained after four serial passages. Thereafter, the virus grew to a plateau titre of 10(8.5) TCID50/ml at 7 days p.i. in a growth experiment. The infected cells showed no cytopathic effects but eventually a persistent infection was established when a saturated level of virus growth was reached.

Animals↗
PubMed1989

A Creutzfeldt-Jakob disease agent (Echigo-1 strain) recovered from brain tissue showing the 'panencephalopathic type' disease.

We used histologic evidence of degenerative changes in both the gray and white matter of the brain to diagnose a patient as having the panencephalopathic type of Creutzfeldt-Jakob disease (CJD). This type of CJD is relatively common in Japan, but not in North America or Europe. We recovered a transmissible pathogen (Echigo-1 strain) from an autopsy specimen of the patient's brain and passed it serially in Hartley guinea pigs. After a long latent period, it caused degenerative changes, mainly in the thalamic area of the guinea pig brain. On the 4th passage, a substrain emerged with a short latent period. When cross-transmitted to Golden Syrian hamsters, this substrain induced severe degeneration in both the thalamus and cerebral cortex. We compare our results with those for other experimental CJDs produced by other types of this disease.

Adult↗
PubMed1987

Studies on transmission of human non-A, non-B hepatitis to marmosets.

Two sera obtained from four healthy blood donors, which caused non-A, non-B post-transfusion hepatitis in two recipients, were experimentally inoculated into nine marmosets. Three of seven marmosets developed acute hepatitis characterized by the elevation of serum concentrations of glutamic pyruvic transaminase (GPT) and/or isocitric dehydrogenase (ICD) 8-11 weeks after inoculation. Four of seven showed histopathological changes of acute hepatitis in liver biopsy specimens during the biochemically acute phase. In electron microscopic examination, attached membrane-like structures, which consisted of two-unit membranes of two neighboring endoplasmic reticula with electron-dense material between them, were noted in cytoplasm of hepatocytes during the acute phase of hepatitis. Furthermore, acute-phase sera obtained from two animals were inoculated into four additional marmosets, and non-A, non-B hepatitis was successfully passaged in two of them. The results of this study indicate that certain species of marmoset monkeys are susceptible to human non-A, non-B hepatitis agents and provide a useful animal model for non-A, non-B hepatitis.

Alanine Transaminase↗
PubMed1987

Studies on drug absorption from oral cavity. II. Influence of the unstirred water layer on absorption from hamster cheek pouch in vitro and in vivo.

The influence of the unstirred water layer (UWL) adjacent to the membrane surface of the hamster cheek pouch on absorption was studied in vitro and in vivo. The tissue uptake rate of 14C-laurylalcohol was determined in vitro and the value of the effective resistance of UWL (RW) was calculated. RW values were reduced by increasing the stirring rate of the mucosal solution. In vitro permeation of 14C-benzoic acid into the serosal compartment was also increased in the well-stirred condition. Thus, the existence of UWL as an effective diffusion barrier for drug absorption from the hamster cheek pouch was suggested. To clarify the influence of the existence of UWL on the absorption in vivo, the apparatus for luminal stirring was newly devised. When the luminal solution was well-stirred, the absorption of benzoic acid in the lower pH region significantly increased, resulting in the disappearance of the shift of pH-absorption curve for benzoic acid. Furthermore, the luminal stirring increased the absorption rate constant for salicylic acid. From these experimental results, it is suggested that UWL plays a part of barriers against drug permeation in the hamster cheek pouch.

Administration, Buccal↗
PubMed1986

Expression of major histocompatibility complex class I antigens as a strategy for the potentiation of immune recognition of tumor cells.

Like many primary tumors, human adenovirus type 12 (Ad12)-transformed mouse cells express greatly reduced levels of the major histocompatibility complex (MHC) class I antigens and are highly tumorigenic in immunocompetent hosts. Expression of a transfected class I gene by these cells can abrogate their tumorigenicity. Both the K and the L class I genes can suppress the malignant phenotype. Previous studies showed that interferon can induce class I gene expression in certain Ad12-transformed cells and can suppress their tumorigenic phenotype. We now demonstrate that preimmunization of mice with a nontumorigenic dose of interferon-treated Ad12-transformed tumor cells can afford protection against a subsequent challenge by a tumorigenic dose of untreated Ad12-transformed tumor cells. Similar immunity can also be induced by using cells transfected with the K gene, and the observed protection appears specific to Ad12-transformed cells. Significant protection can be achieved even if immunization is provided subsequent to the tumor challenge. Since increasing numbers of human tumors have been found to have reduced levels of MHC class I antigens, the prospect of therapy by immunization with the parental tumor cells that have been manipulated to induce class I gene expression offers an attractive experimental model.

Adenoviruses, Human↗
PubMed1986

Growth experiment of Hantaan virus in A549 cells: an attempt to improve the immunofluorescent antibody technique for hemorrhagic fever with renal syndrome.

An assay method for the infectivity of Hantaan virus, a causative agent of HFRS (hemorrhagic fever with renal syndrome), was developed by the use of IFA (immunofluorescent antibody technique). With the aid of this method, the growth characteristics of Hantaan virus, 76-118 strain, were followed in A549 cells. At a maximal MOI (multiplicity of infection) of 1.6 VAIU (viral antigen-inducing units) per cell, the conventionally available value, plateau level potencies of the viral antigen and virus infectivity were attained at eight and ten days postinfection, respectively, and most of the infective virus produced accumulated in the culture fluids of infected cells. When infections were defined with MOI values in terms of VAIU per cell, development of the viral antigen was highly consistent and followed a given pattern of kinetics. Based on these findings, a protocol for preparation of the viral antigen in IFA was presented, wherein spot culture and FBS treatment were emphasized as effective procedures to minimize non-specific staining.

Animals↗
PubMed1985

Seroepidemiology of human T-lymphotropic retrovirus type I (HTLV-I) in residents of Niigata Prefecture, Japan. Comparative studies by indirect immunofluorescence microscopy and enzyme-linked immunosorbent assay.

A large sample of carriers of human T-lymphotropic retrovirus type I (HTLV-I) in Niigata Prefecture was examined for the detection of natural antibodies to HTLV-I-related antigens in sera using both indirect immunofluorescence microscopy (IFM) and enzyme-linked immunosorbent assay (ELISA). The present findings are based on multiple surveys, using each assay technique at least twice. Although Niigata Prefecture has been considered a non-endemic region for HTLV-I, Sado Island has been proven by this study to be a relatively endemic pocket within this non-endemic area. Seropositivity was highest in residents of Sado Island; 97/1, 117 (8.7%) by IFM and 33/1,061 (3.1%) by ELISA; followed by Niigata City, 18/650 (2.8%) by IFM and 16/638 (2.5%) by ELISA; and lowest in the remaining areas, 57/2,631 (2.2%) by IFM and 20/2,551 (0.8%) by ELISA. Seropositivity was demonstrated in 172/4,398 (3.9%) by IFM and 69/4,250 (1.6%) by ELISA in Niigata Prefecture taken as a whole. In general, the incidence of seropositive residents increased gradually with age. The sex difference was not significant. The serum samples tested were categorized into 4 groups; (1) IFM and ELISA both positive, (2) IFM positive but ELISA negative, (3) IFM negative but ELISA positive, and (4) IFM and ELISA both negative. By absorption tests, IFM and ELISA seemed to recognize different specific antibodies in sera; IFM recognized antibodies to HTLV-I-related cellular antigens in addition to HTLV-I viral antigens, but ELISA recognized antibodies to HTLV-I viral antigens alone. Thus, IFM detected a broader spectrum of antigens, resulting in recognition of more positive sera than those detected by ELISA.

Adolescent↗
PubMed1985

Localization of hepatitis A virus in marmoset liver tissue during the acute phase of experimental infection.

Electron microscopic and virological studies of marmoset liver tissue with acute infection of hepatitis A virus (HAV), especially in the earlier stages of infection, were carried out to characterize the maturation process of HAV. Four marmosets were inoculated intravenously with HAV suspension and sacrificed 1 week, 2 weeks, 3 weeks and 4 weeks after inoculation respectively. Hepatitis A antigen (HAAg) in 10% liver homogenates of marmosets was examined by radioimmunoassay and a large amount of HAAg was detected in the liver homogenate of two marmosets sacrificed 2 weeks and 3 weeks after inoculation respectively. The histodiagnosis of the marmoset sacrificed 2 weeks after HAV inoculation was normal. However, many clusters of virus-like particles about 27 nm in diameter, in both "solid" and "empty" forms were found, mainly in vesicles of Kupffer cells by electron microscopy. In the animal that developed mild hepatitis 3 weeks after inoculation HAV-like particles were found in vesicles of hepatocytes by electron microscopy. By immune electron microscopy using peroxidase-conjugated anti-hepatitis A antibody, HAAg was detected on the particles present within the cytoplasmic vesicles of Kupffer cells or hepatocytes and on the surrounding membrane of the vesicles which contained HAV-like particles.

Alanine Transaminase↗
PubMed1984

Location of human T-cell leukemia virus (HTLV) p19 antigen on virus-producing cells.

Mouse monoclonal antibody to HTLV p19 was used to locate HTLV p19 on the surface of cells and virions by immunofluorescence microscopy (IFM) and immunoelectron microscopy (IEM). When HTLV-producing cells HUT 102 (B2 clone), MT-2 and strain A were used as target cells, HTLV p19 was detected on the surface of cells and virions as spots or small sectors by both IFM and IEM. Cells infected with animal type-C retroviruses, e.g., gibbon ape leukemia virus, simian sarcoma virus, feline leukemia virus, and Gross murine leukemia virus, were completely negative for HTLVp19 expression. Other human T cells not producing HTLV, including HUT78 and HSB2-0, immature or pre-T cells (Molt-3) derived from leukemia patients, and fresh peripheral blood T cells from healthy persons, were also negative. In addition, B cells including Rob-B, IM-9, Raji, and BT-1 did not react with the monoclonal antibody to HTLV p19. In the light of the presence of HTLV p19 in the periphery of acetone-fixed HTLV-producing cells as shown by IFM, it seems most likely that HTLV p19 is an internal antigen of HTLV with part of its structure protruding out of the viral and cell membrane. The monoclonal antibody to HTLV p19 did not lyse HTLV-producing cells in the presence of complement, as expected, because the antibody is an IgG1. Antibody-dependent cell-mediated cytotoxicity was also studied by the 51Cr-release assay. No cytotoxicity was observed. Although HTLV p19 does not contribute to the destruction of malignant T cells for treatment and/or virions for prophylaxis, this protein is an important marker for diagnosis of HTLV infection. The patterns of HTLV p19 expression described above were exactly the same for American HTLV-producing HUT 102 (B2 clone), for strain A cells and for Japanese HTLV-producing MT-2 cells. These results further substantiate the close relationship of the Japanese and American HTLV isolates.

Antibodies, Monoclonal↗
PubMed1982

Effector cells working for rejection of Ad12 tumors in mice.

Immune spleen cells (ISC) capable of inhibiting the growth of adenovirus type 12 (Ad12) tumors were raised in C57BL/6 mice by immunization with Ad12, fractionated according to their affinity for plastic and nylon-wool substrates or treated with various antisera plus complement, and subjected to the tumor-neutralization test (Winn) to define the effector cells for the cell species. Full antitumor activity of ISC was recovered in the cell fractions nonadherent to the two substrates; the antitumor activity of ISC was abrogated entirely by anti-Thy-1,2 serum and almost entirely by anti-Lyt-2.2 ascites fluid plus complement. These results clearly indicate that T-lymphocytes, particularly those bearing Lyt-2.2 antigen, are the principal effectors in ISC against Ad12 tumors in animals.

Adenoviridae Infections↗
PubMed1981

Propagation of human hepatitis A virus in conventional cell lines.

Fecal extracts of hepatitis A (HA) patients were selected for the presence of hepatitis A virus (HAV) by radioimmunoassay (RIA) and immune electron microscopy (IEM). When FL and Vero cells were inoculated with fecal extracts containing HAV, development of hepatitis A antigen (HAAg) was evident in the cytoplasm of the two cell lines by the indirect immunofluorescence (IF) test. The antigen was detectable in the cells 12 hr postinoculation (pi), and reached a plateau within two days pi. FL cell cultures inoculated with a specimen containing HAV were harvested and passaged four times. During the passages, efficient production of HAAg was confirmed in the infected cultures by three different serological tests: The indirect IF test, RIA using fixed cells, and RIA by the sandwich method. At the second and fourth passages, HAV particles were recovered in abundance from infected FL cell cultures by IEM. Throughout these experiments, no cytopathic effect (CPE) was discernible in the cultures.

Antigens, Viral↗