Search PubMed⌕ Search

Biomedical subjects

J Okada

Publications and source records attributed to J Okada.

At least 163 records · Page 9Linked to original sources
PubMed1987

Study of possible transmitters in the solitary tract nucleus of the cat involved in the carotid sinus baro- and chemoreceptor reflex.

By using a multibarrelled microelectrode, the possibility that putative transmitters may influence on the field potential evoked in the solitary tract nucleus by electrical stimulation of the carotid sinus nerve (the NTS response) was examined electrophysiologically in the cat. After iontophoretic application of a selective antagonist to the putative transmitter, it was determined whether or not the NTS response was influenced. Both substance P antagonist and naloxone altered the NTS response recorded in the depressor and apneic (or hypopneic) response zone as well as in the pressor and apneustic (or inspiratory) response zone throughout the rostral, intermediate and commissure regions, suggesting that substance P and opioid peptide may play the role of excitatory transmitters. Under the polarizing cathodal current which may activate inhibitory inputs to the site of the NTS response, bicuculline and prazosin strongly enhanced the NTS response recorded in the pressor and apneustic zone, while naloxone weakly enhanced the NTS response recorded in the depressor and apneic zone. These results suggest that gamma-aminobutyric acid, alpha-adrenergic agonist and opioid peptide may have an inhibitory influence on the NTS response.

Animals↗
PubMed1987

Preservation of natural killer and interleukin-2 activated killer cell activity in ataxia-telangiectasia with T cell deficiency.

Peripheral blood mononuclear cells (PBMs) from 6 patients with ataxia-telangiectasia (AT) were studied by 5 kinds of cell-mediated cytotoxicity systems. Decrease in cell mediated lympholysis (CML) activity to allogeneic lymphocytes was observed in all 6 AT patients who had low numbers of OKT-3+ cells. These patients also showed decreased proliferative responses to phytohemagglutinin stimulation and allogeneic lymphocytes. In contrast, antibody-dependent cell-mediated cytotoxicity (ADCC) activity and natural killer (NK) activity were comparable with those in normal controls. In addition, PBMs from these AT patients activated by in vitro stimulation with allogeneic PBMs or interleukin-2 were able to acquire lytic activity against NK-insensitive target cells. The phenotypes of these effectors determined by complement-mediated lysis were OKT-3- and Leu-11+, suggesting that they were derived from NK cell lineage. Thus, AT patients with severe T cell defects were found to maintain a normal range of NK, ADCC, MLC-activated and lymphokine-activated killer activity.

Adolescent↗
PubMed1986

Evidence that the cultured multipolar neurons of the lower brainstem of SHR and WKY rats differ significantly in the mode of responses to catecholamines.

By using cultures of 6 types of dissociated neurons from the lower brainstem of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats, we analyzed differences in the mode of response of the cultured neurons to 9 kinds of peptides and 7 kinds of neurotransmitters, and obtained evidence that there is a significant difference in the mode of response of multipolar neurons to catecholamines; dominantly facilitation in SHR, but dominantly inhibition in WKY rats.

Acetylcholine↗
PubMed1986

The role of Ia positive T cells in patients with rheumatoid arthritis.

In peripheral blood and synovial fluid of patients with rheumatoid arthritis (RA), increased levels of Ia antigen-positive (Ia+) T cells have been demonstrated. Therefore, we examined these Ia+ T cells in vitro to identify their role in the production of rheumatoid factor (RF) and to study the immunologic abnormalities of RA. When Ia+ T cells from peripheral blood of RA patients were added to pokeweed mitogen (PWM)-non-stimulated autologous B cells, the amount of IgM-RF production was 25.8 +/- 6.4 (mean +/- SE) (p less than 0.001) as compared to 16.0 +/- 4.6 ng/ml (mean +/- SE) in the presence of Ia-T cells. When Ia-OKT4+ cell fractions, obtained by excluding Ia+ T cells from OKT4+ cells, were added to B cells, the increase in IgM-RF production was markedly lower than that obtained with the OKT4+ cell fraction. These results indicate that the helper T cells which induce the production of IgM-RF may derive from the Ia+ OKT4+ cell fraction. B cells from rheumatoid synovial fluid produced IgM-RF levels as high as 102.7 +/- 19.2 ng/ml (mean +/- SE) even without stimulation. When T cells from autologous synovial fluid were added, IgM-RF production was not increased. These data suggest that B cells from RA synovial fluid had already been activated. When synovial fluid T cells were added to B cells from autologous peripheral blood, larger amounts of IgM-RF were produced as compared to experiments in which T cells from peripheral blood were added, suggesting that T cells from synovial fluid induced an enhanced IgM-RF production by B cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis, Rheumatoid↗
PubMed1986

In vitro analysis of lymphocyte functions in common variable immunodeficiency: heterogeneity in B-cell defects.

Ten patients with common variable immunodeficiency were classified into three groups according to the number of circulating B-cells, i.e. B-cells being absent (three patients), very low (three patients) or within the normal range (four patients). The four patients in the last group showed significant proliferative responses to the T-independent B-cell mitogen, formalin-fixed Staphylococcus aureus, Cowan I. Further study of these patients by co-cultures with allogeneic T or B-cells in various combinations with pokeweed mitogen showed that two patients had an intrinsic B-cell defect without T-cell defect. The third patient had a T-cell dysfunction (i.e. his T-cells could only help the B-cells of some individuals) resulting in a defect in Ig production. The T-cells of the fourth patient showed poor helper function towards all controls. All six patients with absent or very low numbers of B-cells in group I and II had normal T-cell helper function. This study demonstrates that the immunological defect in common variable immunodeficiency is most often a B-cell defect at different stages of their differentiation with sometimes an additional T-cell dysfunction.

Adolescent↗
PubMed1985

Sites of action of brain-gut peptides in cultured neurons of rat brainstem.

Using cultures of dissociated neurons from the lower brainstem of 14- to 15-day-old rat embryos, we studied a site of action of a brain-gut peptide by determining whether neuronal responses to a test peptide are abolished or not after replacement of normal medium with low Ca2+- high Mg2+ medium. VIP, secretin and CCK-4 may act on the postsynaptic membrane, while motilin and neurotensin may act on the presynaptic terminal. Somatostatin and bombesin may work either presynaptically or postsynaptically.

Animals↗
PubMed1985

Hepatic schistosomiasis japonica identified by CT.

We reviewed the CT examinations of 17 patients who had hepatic schistosomiasis japonica and noted peculiar hepatic calcifications in 15 cases and a notch on the hepatic surface in six. A hepatocellular carcinoma was found in six patients. The calcifications and notch appeared to indicate the degree of hepatic fibrosis but did not correlate with cirrhotic deformation.

Aged↗