Search PubMed⌕ Search

Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 1,117 records · Page 62Linked to original sources
PubMed1992

A comparison of endocrine and exocrine function after pancreatic fragment autotransplantation into splenic pulp, portal vein, and hepatic parenchyma.

Three sites were evaluated for potential pancreatic fragment autotransplantation. Both endocrine and exocrine functions were evaluated following autotransplantation into splenic pulp, portal vein, or hepatic parenchyma in 44 pancreatectomized dogs. Cholecystic bile amylase concentrations in the hepatic parenchyma group surviving more than 2 months were elevated significantly, and choledochal bile amylase concentrations increased markedly following pancreozymin-secretin injection. In contrast, bile amylase concentrations in dogs with intrasplenic or intraportal implants were low and did not respond to PS injection. Histologically pancreatic autografts in hepatic parenchyma revealed marked proliferation of exocrine tissue with abundant zymogen granules and reconstruction of the acinar lobules with a few islets. These acinar cells in the hepatic parenchyma were ultrastructurally normal. Transplant endocrine function, estimated by K values, was significantly better after splenic pulp and portal vein than after a hepatic parenchyma implantation, but no group improved during 1-year follow-up. Glucose-stimulated initial insulin responses were abnormally low in all recipients. Islet B cells lacked mature insulin granules, such as seen in normal resting B cells. This ultrastructural finding implies a persistent demand on the B cells and may explain the spontaneous recurrence of hyperglycemia and the diminished initial insulin response to a glucose load. This study indicates that euglycemic recipients of pancreatic fragment autotransplantation remain unstable and prediabetic.

Amylases↗
PubMed1992

Activation of the mouse proliferating cell nuclear antigen gene promoter by adenovirus type 12 E1A proteins.

A plasmid carrying the 5'-flanking region (-1584 to +47 with respect to the transcription initiation site) of the mouse proliferating cell nuclear antigen (PCNA) gene was fused with the chloramphenicol acetyltransferase (CAT) gene, and then cotransfected into mouse N18TG2 cells with expression plasmids for the adenovirus type 12 E1 genes. Expression of E1A gene products elevated the CAT expression by 5- to 9-fold, but expression of the E1B gene product did not. RNase protection analysis revealed that the activation of the PCNA gene promoter by E1A was at the transcription step. Both the 13S E1A and the 12S E1A activated the PCNA gene promoter, indicating that the activation domain of E1A resides in a common region(s) of 13S and 12S E1A products. The major target region of E1A was mapped within the 68 base-pair region (-21 to +47) of the PCNA gene, which includes consensus sequences for transcription factors PEA3 and E2F, although the upstream region (-83 to -21) including ATF(CREB)-binding consensus had an additional effect in the transactivation.

Adenovirus Early Proteins↗
PubMed1992

Haemopoietic growth factors induce human basophil migration in vitro.

Accumulation of basophils in inflammatory sites is an important aspect of the late-phase allergic reaction involving skin and upper and lower airways, suggesting the existence of mechanisms for basophil migration. Because haemopoietic growth factors have been shown to stimulate various functions of human basophils, we tested the ability of haemopoietic growth factors to migrate basophils in vitro. Both IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) induced migration of purified normal basophils (purity c. 80%) in a dose-dependent fashion at picomolar concentrations, while granulocyte (G)-CSF, macrophage (M)-CSF, and IL-4 had no effect at all. Chequerboard analyses indicate that migratory activity of both factors are chemokinetic. These results suggest that local production of both factors during allergic reactions might potentially play an initial role in the recruitment of basophils from the circulation to sites of inflammatory reactions.

Antibodies↗
PubMed1992

Incidence of headache and severity of head injury.

The relationship between the incidence of post-traumatic headache and the severity of head injury has been a controversial issue. The milder the head injury, the more frequently severe headache is noted as a symptom. To investigate this relationship, 121 civilians were investigated using simplified classifications of the grade of headache, type of injury (mild or severe), cervical X-ray and head CT findings, and clinical history. All the subjects were claiming compensation for work-related injuries. In the mildly injured group, 46/64 patients complained of severe headache, while only 19/57 had severe headache in the severely injured group (p < 0.001). Abnormal findings on the cervical X-ray films including degenerative changes were more frequent in the severe headache group (p < 0.02). CT abnormalities correlated positively with the severity of head injury (p < 0.001), but showed an inverse relationship with the incidence of headache (p < 0.01). Mentally impaired patients also complained of headache less frequently (p < 0.01). On the basis of these results, possible organic mechanisms related to the pathogenesis of post-traumatic headache are discussed.

Craniocerebral Trauma↗
PubMed1992

Partial inhibition of skeletal muscle contraction by dantrolene sodium and its modification with perchlorate and Bay K 8644.

The effects of dantrolene sodium (DAN) on the dihydropyridine receptor (DHPR) of the transverse (T) tubule voltage sensor (Ca2+ channel) was studied with single fibers from bullfrog toe muscle. Perchlorate (ClO4-), which acts selectively on the DHPR, overcame DAN-induced inhibition of twitch tension. Bay K 8644, a DHPR agonist, slowed the rate of twitch inhibition by DAN. DAN inhibited twitch tension to a greater extent in Ca(2+)-free solution than in Ringer solution or solution containing Zn2+, whereas twitch inhibition by DAN was less in caffeine-containing solution than in the control. The effects of DAN on Zn(2+)- and caffeine-treated fibers and on fibers in Ca(2+)-free solution suggest that DAN must act near the voltage sensor of the T tubule. However, differences in net twitch inhibition by DAN between control fibers and fibers potentiated by ClO4- or Bay K 8644 suggest that DAN does not bind to the same site as these potentiating agents do. The role of myoplasmic Ca2+ in DAN-induced inhibition of twitch and the effects of DAN on the mechanical threshold and membrane potential in skeletal muscle are discussed.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Binding sites for interleukin-6 in the anterior pituitary gland.

Interleukin-6 (IL-6) binding site in the rat anterior pituitary gland was characterized using radioiodinated human recombinant (hr) IL-6. Results showed that the anterior pituitary gland contained 170 binding sites per cell of a single class with a dissociation constant of 2.7 x 10(-9) M. The binding of 125I-hrIL-6 to the rat anterior pituitary gland was competitively inhibited by unlabeled hrIL-6, but not by hrIL-1 alpha, hrIL-1 beta, hrIL-2 or hr-interferon-gamma, indicating these binding sites are specific for IL-6. We also demonstrated mouse IL-6 receptor gene expression in the rat anterior pituitary gland by Northern blot analysis. Furthermore, the IL-6 receptor was detected on human gonadotrophs by the double immunofluorescence method. Our findings demonstrate the presence and expression of IL-6 binding site in the rat anterior pituitary gland and the presence of IL-6 binding site on human gonadotrophs, suggesting the important role of IL-6 binding site in pituitary hormone release in both species.

Animals↗
PubMed1992

Inhibitory effect of beta-alanyl-L-histidinato zinc on bone resorption in tissue culture.

The inhibitory effect of beta-alanyl-L-histidinato zinc (AHZ) on bone resorption in tissue culture was investigated. Calvaria were removed from weanling rats (3-week-old male) and cultured for periods up to 48 h in Dulbecco's modified Eagle medium (high glucose, 4.5%) supplemented with antibiotics and bovine serum albumin. The experimental cultures contained 10(-7) to 10(-4) mol/l AHZ. The bone-resorbing factors, parathyroid hormone (1-34) (PTH; 10(-7) mol/l), prostaglandin E2 (10(-5) mol/l), interleukin-1 alpha (IL1 alpha; 50 U/ml), and lipopolysaccharide (10 micrograms/ml), caused a significant decrease in bone calcium content. The decreases in bone calcium content induced by bone-resorbing factors were completely inhibited by the coexistence of AHZ (10(-6) to 10(-4) mol/l). Also, AHZ (10(-5) mol/l) completely inhibited the PTH (10(-7) mol/l) or IL1 alpha (50 U/ml)-induced increase in medium glucose consumption and lactic acid production by bone tissue. Furthermore, AHZ (10(-5) mol/l) fairly blocked both PTH (10(-7) mol/l)-increased acid phosphatase and decreased alkaline phosphatase activities of bone tissue. The inhibitory effect of AHZ (10(-5) mol/l) on PTH (10(-7) mol/l)-stimulated bone resorption was clearly prevented by the presence of 10(-4) mol/l dipicolinate, a chelator of zinc. However, zinc sulfate (10(-7) to 10(-4) mol/l) did not inhibit the PTH (10(-7) mol/l)-stimulated bone resorption in tissue culture. These findings indicate that AHZ had a direct inhibitory effect on bone resorption in vitro, and the AHZ effect was found in the chemical form of zinc-chelated dipeptide.

Acid Phosphatase↗
PubMed1992

Cytoplasmic filaments in the endothelial cells of the sheathed capillary: an ultrastructural and immunocytochemical study in the pig spleen.

Cytoplasmic filaments of the endothelial cells of sheathed capillaries in the pig spleen were identified and their ultrastructure was studied. Two types of cytoplasmic filaments were found: intermediate filaments (diameter: 10 nm) which filled most of the interior of the cells, and thin filaments (diameter: 5 nm) which were located just beneath the cell membrane and filled the lateral cytoplasmic processes. In immunocytochemical preparations, the intermediate filaments were positive for vimentin and desmin, and were negative for keratin. Staining of the thin filaments with heavy meromyosin resulted in arrowhead formations. These observations suggest that the intermediate filaments maintain the cytoarchitecture, possibly protecting the cell from structural alterations induced by blood pressure changes. Concurrently, thin filaments may facilitate the passage of red blood cells and blood platelets through the interendothelial fenestrae of the sheathed endothelial cell to the reticular meshwork in the capillary sheath.

Animals↗
PubMed1992

Hemopoietic growth factors regulate the survival of human basophils in vitro.

Human basophils were purified from normal peripheral blood, using density gradient followed by negative panning selection. We tested the effects of hemopoietic growth factors on the survival of these basophils in vitro. In the absence of exogenous factors, basophils (purity greater than 90%) decreased in number rapidly. At day 7 only 11% of the cells remained alive in cultures; less than 1% of cells survived at day 14. Interleukin (IL)-3 maintained numbers of viable cells; cell viability was 67% at day 7 and 45% at day 14. Granulocyte-macrophage (GM)-colony-stimulating factor (CSF) exhibited slight effect on the survival; 33% of cells remained at day 7. Other growth factors including granulocyte (G)-CSF, macrophage (M)-CSF, and IL-4 had no significant effect on the survival of basophils at all. Morphological and functional characterization of cells maintained by IL-3 revealed that they belonged to the basophil lineage. These observations indicate that normal basophils possess functional receptors for IL-3 and GM-CSF and that both factors modulate immediate- and delayed-type hypersensitivity reactions by prolonging the life span of basophils.

Basophils↗
PubMed1992

Mouse IL-3 induces histamine release from mouse peritoneal mast cells.

In this study, we have attempted to determine whether mouse peritoneal mast cells released histamine in response to IL-3. Recombinant mouse (m)IL-3 induced histamine release from mouse peritoneal mast cells in a dose-dependent fashion. Histamine release did not occur in the absence of phosphatidyl serine (PS), and was dependent on PS concentrations. The release was 14.3 +/- 3.8 and 43.5 +/- 11.5% (mean +/- SEM, n = 5) at 1 nM IL-3 in the presence of 10 and 20 micrograms/ml of PS. Calcium was required for the response, and in the absence of calcium, significant histamine release was not observed. The kinetics were slower than those of anti-IgE-induced response. IL-3-induced histamine release reached a peak within 15 min, while that by anti-IgE reached 80% of the maximum in 3 min. Lower concentrations of IL-3, which failed to directly induce histamine release, did not enhance anti-IgE-induced histamine release. Other cytokines, including mIL-4, mIL-5, m-granulocyte-macrophage colony-stimulating factor, human (h)IL-1 alpha, hIL-1 beta and hIL-8, neither induced histamine release nor enhanced anti-IgE induced histamine release. IL-4 had no capacity to enhance IL-3-induced histamine release. These results suggest that locally produced IL-3 might modulate mast cell-related inflammation through histamine release from mast cells.

Animals↗
PubMed1992

Idiopathic pulmonary fibrosis and high prevalence of serum antibodies to hepatitis C virus.

The prevalence of serum antibodies to hepatitis C virus (HCV) was assessed by an enzyme-linked immunosorbent assay (ELISA) in 66 patients (46 male and 20 female; mean age +/- SEM, 61.5 +/- 10.1 yr) with idiopathic pulmonary fibrosis (IPF). Nineteen (28.8%) were positive for this test. The frequency of HCV positiveness was significantly higher in the patients with IPF than in the 9,464 control subjects, whose ages were comparable with those of the patients (3.66%, p less than 0.05). Importantly, 12 of the 19 patients with IPF and positive ELISA results (63.2%) had positive results on the Chiron recombinant immunoblotting assay (RIBA), which is known to be more specific for HCV. We judged the 12 perceptible reactions as eight reactive and four indeterminate. When we examined liver function retrospectively, only two of eight patients who tested positive for the HCV had liver dysfunction, suggesting that anti-HCV positivity in IPF was not observed as a result of liver disease. These results lead us to speculate that HCV infection may play an important role in the pathogenesis of IPF, or that the sera of patients with IPF may contain some antibody against an unknown epitope and cross-react with the anti-HCV assay.

Aged↗
PubMed1992

Hypersensitivity pneumonitis in athymic nude mice. Additional evidence of T cell dependency.

We previously demonstrated that C57 Black/6 mice develop lung lesions similar to human hypersensitivity pneumonitis (HP) by repeated transnasal administration of Thermoactinomyces vulgaris (Tv) antigen. To elucidate the role of T cells in the development of this disease, Tv antigen (90 micrograms/day) was transnasally administered to athymic nude C57 Black/nu/nu (nu) mice and their littermates (+/nu) three times a week for 3 wk. The nude mice developed minimal lung lesions, whereas their thymus-intact littermates (+/nu) showed changes equivalent to those in C57 Black/6. Changes in local inflammatory cell responses were evaluated by bronchoalveolar lavage, and increases in the numbers of lymphocytes and macrophages were significantly less severe in the nude mice than in the +/nu mice. Interestingly, the increase in polymorphonuclear leukocytes 6 h after the last antigen inoculation was equivalently seen in both groups. When spleen-derived T cells (more than 95% Thy-1.2+) from the sensitized +/nu mice were adoptively transferred to nude mice, the HP-like lesions in the recipients were found after Tv antigen challenge. These results suggest that Thy-1.2+ T cell-mediated immunity was necessary for the development of HP in this murine model.

Alveolitis, Extrinsic Allergic↗