Biomedical subjects

Y Shibata

Publications and source records attributed to Y Shibata.

At least 253 records · Page 14Linked to original sources

PubMed1997

Neonatal alloimmune thrombocytopenia associated with anti-human platelet antigen-3a antibody.

A sister and brother with neonatal alloimmune thrombocytopenic purpura (NAITP) caused by maternal anti-human platelet antigen (HPA)-3a are reported. The children had transient severe thrombocytopenia in the newborn period, and were treated with intravenous gamma-globulin and platelet concentrates from random donors. Although the sister had intracranial hemorrhage on day 2 postnatally, the development of the child has been normal and no neurological sequelae have been observed. The brother only had bloody stool when the platelet count was low, and did not have severe hemorrhagic manifestations. The diagnosis of NAITP was made by the sera from the mother, which contained anti-HPA-3a antibody directed against platelets of the children. The rate of recurrence might be high in this family, because the father of the patients was found to be homozygous for the HPA-3a gene.

Antigens, Human Platelet↗

PubMed1997

Is the dog a useful model for accelerated calcification study of cardiovascular bioprostheses?

Chitosan posttreatment has been shown to be effective in prevention of calcification of the glutaraldehyde treated bovine pericardium when implanted subdermally in rats for 12 weeks. The efficacy of chitosan posttreatment in complete calcium mitigation of the glutaraldehyde treated porcine aortic valves implanted in the right side of the heart in dogs was well-documented in our previous study. In this study, an attempt has been made to evaluate the merit of the chitosan posttreatment in prevention of calcification of the glutaraldehyde (GA) treated porcine aortic valved conduits in the systemic circulation in dogs for a period of 5 months. Eleven mongrel dogs underwent left thoracotomy. Porcine aortic valved conduits treated with 0.625% GA (n = 5) and GA-chitosan (n = 6) were implanted in the descending thoracic aortas of the dogs for 5 months. Gross histological observations showed no calcification in either the 0.625% GA treated or in the GA-chitosan treated valved conduits at 5 months. This was confirmed by results of quantitative analyses for calcium in each explant. There was no significant difference in calcium content between the GA only (Ca, 0.43 +/- 0.26 mg/g) and GA-chitosan treated (Ca, 0.51 +/- 0.19 mg/g; p = 0.5959) valved conduits. This study suggests that the dog is not a suitable model for evaluating the efficacy of a calcium mitigating agent in bioprostheses implanted in systemic circulation.

Animals↗

PubMed1997

Presence of HLA-G-expressing cells modulates the ability of peripheral blood mononuclear cells to release cytokines.

PROBLEM: Human leukocyte antigen-G (HLA-G) is thought to be at play in maternal-fetal immune interplay during pregnancy. Whether the expression of HLA-G protein on the target cells altered the release of cytokines from effector mononuclear cells was questioned. METHOD OF STUDY: The amounts of cytokines released from peripheral blood mononuclear cells (PBMC) cocultured with or without HLA-G-expressing target cells were compared. RESULTS: When cocultured with HLA-G-expressing target cell lines, the amounts of interleukin-3 (IL-3) and interleukin-1 beta (IL-1 beta) released from PBMC were increased, whereas the amounts of tumor necrosis factor-alpha (TNF-alpha) were decreased. CONCLUSIONS: Mononuclear cells, if cultured with HLA-G-expressing cells, modulate their ability to release cytokines, suggesting a role of HLA-G in triggering maternal-fetal immune interplay and thereby maintaining pregnancy.

Cell Line↗

PubMed1997

Using acoustic radiation force as a concentration method for erythrocytes.

We investigated the potential damage inflicted on erythrocytes by acoustic radiation force when the cells are concentrated by a 500-kHz ultrasonic standing wave at the pressure node. The extent of the damage was estimated from the concentrations of potassium ions, iron complexes, and lactate dehydrogenase released from the cells. After 2 min of ultrasound irradiation at 12.8 mJ/m3, the cells concentrated on the pressure node, with a cell distribution half-width of 138 microns; no significant release of intracellular components was detected, even after 15 min of irradiation. The results indicate that even small ions like potassium are not released as a result of ultrasound irradiation on cell membranes without cavitation, and they demonstrate the potential use of acoustic radiation force for concentrating living cells in biomedical applications.

Acoustics↗

PubMed1997

Alveolar macrophage priming by intravenous administration of chitin particles, polymers of N-acetyl-D-glucosamine, in mice.

Intravenous (i.v.) administration of phagocytosable chitin particles (1 to 10 microm) in C57BL/6 mice and SCID mice primed alveolar macrophages (Mphi) within 3 days to yield up to a 50-fold increase in their oxidative burst when elicited in vitro with phorbol myristate acetate (PMA). C57BL/6 mice pretreated with monoclonal antibodies (MAbs) against mouse gamma interferon (IFN-gamma) or NK1.1 showed a markedly decreased level of alveolar Mphi priming following injection of chitin particles. To confirm IFN-gamma production in vitro, spleen cells isolated from normal C57BL/6 mice and SCID mice were cultured with chitin particles. Significant IFN-gamma production was observed following stimulation with chitin but not with chitosan or latex beads. When spleen cells were treated with anti-NK1.1 MAb, IFN-gamma production was significantly inhibited. Another set of experiments showed that when C57BL/6 mice were pretreated i.v. with a small dose IFN-gamma, a higher level of priming was induced with not only phagocytosable chitin particles but also phagocytosable chitosan and even latex beads. Likewise, the spleen cell cultures preconditioned with IFN-gamma provided an up-regulation of IFN-gamma production by these phagocytosable particles. Taken together, the in vivo and in vitro results suggest that (i) the alveolar Mphi priming mechanism is due, at least in part, to direct activation of Mphi by IFN-gamma, which is produced by NK1.1+ CD4- cells; (ii) IFN-gamma would have an autocrine-like effect on Mphi and make them more responsive to particle priming; and (iii) phagocytosis of particulates, probably by a postmembrane event such as interiorization, appears to be important for the up-regulation of alveolar Mphi priming and IFN-gamma production.

Animals↗

PubMed1997

Small GTP-binding protein, Rab6, is associated with secretory granules in atrial myocytes.

Rab proteins, a subfamily of small GTP-binding proteins, have been shown to play key roles in regulation of vesicular traffic in eukaryotic cells. In this study, we have intended to identify, the atrial granule-associated Rab proteins that seem to be required for formation or intracellular transport of the granules. Atrial granules contained at least four small GTP-binding proteins, and we have demonstrated by biochemical analysis that one of the small GTP-binding proteins associated with the atrial granules is a Rab6 protein (Rab6p). Rab6p was also detected in highly purified zymogen granules of pancreatic exocrine gland. Immunogold electron microscopy performed on ultrathin cryosections of rat auricle revealed that Rab6p was associated with the atrial granule membranes. Association of Rab6p with the atrial granule membranes was also confirmed by immunodiffusion electron microscopy in agarose-embedded atrial granules. These data indicate that Rab6p is associated with the atrial granules and that it might function in the intracellular traffic of the secretory granules in the atrial myocytes.

Animals↗

PubMed1997

Selective breeding for high serum IgA levels from noninbred ddY mice: isolation of a strain with an early onset of glomerular IgA deposition.

An outbred mouse strain known as ddY has been reported to spontaneously develop, late in life, mesangioproliferative glomerulonephritis with a severe glomerular immunoglobulin A (IgA) deposition that mimics human IgA nephropathy. However, the incidence of the disease in this strain is not very high, probably due to its heterogeneous genetic background. Therefore, we attempted to isolate a strain with a high incidence and an early onset of the disease through selection for high serum IgA from the outbred ddY mice. The selection procedure was successful in increasing the serum IgA level of the selected line and proved effective both in increasing the incidence and in accelerating the onset of the disease. We propose to designate this line of mice 'HIGA', denoting a line with high serum IgA levels. More than half of the mice from the HIGA strain showed a moderate to severe glomerular IgA deposition as early as 25 weeks of age. The severe deposition observed was comparable to that occasionally seen in the original nonselected ddY strain after 40 weeks of age. Thus, we have succeeded in generating a mouse model of IgA nephropathy with a high incidence and an early onset of glomerular IgA deposition. Using light microscopy, progressive and marked mesangial matrix accumulation was shown to develop in HIGA mice. However, they showed only mild proteinuria (100-300 mg/dl) and did not show hematuria.

Aging↗

PubMed1997

Inhibition of neutrophil elastase-induced interleukin-8 gene expression by urinary trypsin inhibitor in human bronchial epithelial cells.

BACKGROUND: Urinary trypsin inhibitor (UTI), a potential inhibitor for proteinases including neutrophil elastase (NE), trypsin, plasmin, cathepsin B and H has been used for the treatment of lung diseases with the absence of side effects in Japan. METHODS: In this study, we investigated the inhibitory effects of UTI on both purified NE and NE activities present in bronchoalveolar fluids from patients with chronic bronchitis. We also investigated the inhibitory capacity of UTI with regard to NE-induced interleukin-8 gene expression in human bronchial epithelial cells by Northern analyses. RESULTS: UTI inhibited NE activities in bronchoalveolar lavage fluid from patients with chronic bronchitis and of the purified enzyme. In addition, UTI inhibited NE-induced interleukin-8 gene expression and protein secretion in a human bronchial epithelial cell line. CONCLUSIONS: Our results suggest that UTI is applicable to patients with a variety inflammatory lung diseases in which NE plays a pivotal role.

Bronchi↗

PubMed1997

Elevated levels of cytokeratin 19 in the bronchoalveolar lavage fluid of patients with chronic airway inflammatory diseases--a specific marker for bronchial epithelial injury.

Cytokeratin 19 (CK19) is a specific cytoskeletal structure of simple epithelia, including bronchial epithelial cells (BEC). Since CK19 is released from injured bronchial epithelium, we investigated the levels of CK19 fragments in the bronchoalveolar lavage fluid (BALF) of eight patients with chronic airway inflammatory diseases (CAID) using an enzyme-linked immunosorbent assay (ELISA). Included in our test group were four cases of chronic bronchitis, three cases of bronchiectasis, and one case of diffuse panbronchiolitis. There were also 15 control subjects (five asymptomatic smokers and 10 nonsmokers). BALF from the nonsmokers as well as from the asymptomatic smokers contained few CK19 fragments (0.2 +/- 0.2 and 1.9 +/- 0.8 pg/ml, respectively). In contrast, significantly high levels of CK19 were present in the BALF of patients with CAID (21.7 +/- 5.7 pg/ml; p < 0.01 versus nonsmoking controls). In addition, CK19 fragment concentrations in BALF correlated significantly with the number of neutrophils (r = 0.722, p < 0.01) but not with the numbers of macrophages or lymphocytes in BALF. BALF from patients with CAID contained high levels of neutrophil elastase (NE) activity, suggesting that NE might be an important stimulus for the release of CK19 from BEC. To prove this, we incubated BET-1A cells, a human immortalized bronchial epithelial cell line, both in the absence and the presence of inflammatory mediators (including NE, tumor necrosis factor-alpha [TNF-alpha], and hydrogen peroxide). We then measured the concentration of CK19 fragments in the culture supernatants with ELISA. BET-1A cells released CK19 fragments into their culture supernatants after treatment with NE but not after treatment with TNF or hydrogen peroxide. Further, we demonstrated that CK19 cleaved by NE could not be detected by ELISA. Our results suggest that CK19 measurement in BALF is useful for assessing the presence of bronchial epithelial injuries.

Adult↗

PubMed1997

Prevalence of goiter and urinary iodine excretion levels in children around Chernobyl.

The prevalence of goiter among children living in areas affected by the Chernobyl accident was investigated by analysis of data on approximately 120,000 children examined at five medical diagnostic centers in Belarus, Russia, and the Ukraine. Examinations of thyroid gland were conducted with an arch-automatic ultrasonographic instrument at the five centers under the same protocol. The diagnosis of goiter was established when the thyroid volume exceeded a limit calculated from age, height, and body weight of a child. A considerable variation by region was noted in the prevalence of goiter. Highest in the Kiev region, the prevalence in the five regions was 54% in Kiev, 38% in the Zhitomir regions of the Ukraine, 18% in Gomel, 22% in the Mogilev regions of Belarus, and 41% in the Bryansk region of Russia. Urinary iodine content was measured in approximately 5700 children, and an endemic iodine deficient zone was confirmed in the Bryansk, Kiev, and Zhitomir regions. A significant negative correlation was observed between the prevalence of goiter and the median level of urinary iodine content (Spearman's rank correlation coefficient was -0.35, P = 0.025).

Adolescent↗

PubMed1997

Targeted disruption of the mouse homologue of the Drosophila polyhomeotic gene leads to altered anteroposterior patterning and neural crest defects.

The rae28 gene is a mouse homologue of the Drosophila polyhomeotic gene (Nomura, M., Takihara, Y. and Shimada, K. (1994) Differentiation 57, 39-50), which is a member of the Polycomb group (Pc-G) of genes (DeCamillis, M., Cheng, N., Pierre, D. and Brock, H.W. (1992) Genes Dev. 6, 223-232). The Pc-G genes are required for the correct expression of the Homeotic complex genes and segment specification during Drosophila embryogenesis and larval development. To study the role of the rae28 gene in mouse development, we generated rae28-deficient mice by gene targeting in embryonic stem cells. The rae28-/- homozygous mice exhibited perinatal lethality, posterior skeletal transformations and defects in neural crest-related tissues, including ocular abnormalities, cleft palate, parathyroid and thymic hypoplasia and cardiac anomalies. The anterior boundaries of Hoxa-3, a-4, a-5, b-3, b-4 and d-4 expression were shifted rostrally in the paraxial mesoderm of the rae28-/- homozygous embryos, and those of Hoxb-3 and b-4 expression were also similarly altered in the rhombomeres and/or pharyngeal arches. These altered Hox codes were presumed to be correlated with the posterior skeletal transformations and neural crest defects observed in the rae28-/- homozygous mice. These results indicate that the rae28 gene is involved in the regulation of Hox gene expression and segment specification during paraxial mesoderm and neural crest development.

Animals↗

PubMed1997

Dynamics of connexins, E-cadherin and alpha-catenin on cell membranes during gap junction formation.

We examined the dynamics of connexins, E-cadherin and alpha-catenin during gap-junction disassembly and assembly in regeneration hepatocytes by immunofluorescence microscopy, and immunogold-electron microscopy using SDS-digested freeze-replicas. The present findings suggest that during the disappearance of gap junctions most of the gap junction plaques are broken up into smaller aggregates, and then the gap junction proteins may be removed from the cell membrane, but some of the connexons or connexins remain dispersed in the plane of membrane as pure morphologically indistinguishable intramembrane proteins. Double-immunogold electron microscopy using a polyclonal antibody for connexins and a monoclonal antibody for E-cadherin or alpha-catenin revealed co-localization of these molecules at cell-to-cell contact sites during the reappearance of gap junction plaques. This implies that, at least in regenerating hepatocytes, the cadherin-catenin complex-mediated cell-to-cell contact sites act as foci for gap junction formation. In addition, connexin-immunoreactivity was also observed along tight junctional strands, suggesting that the gap junction may also form along the tight junctions.

Animals↗

PubMed1997

Inhibitory effect of oversulfated fucoidan on tube formation by human vascular endothelial cells.

Fucoidan is a sulfated poly(L-fucopyranose) present in brown marine algae. In this study, we examined the effect of native and chemically oversulfated fucoidans (NF and OSF) on the tube structure formation by human umbilical vein endothelial cells (HUVEC) on the basement membrane preparation, Matrigel. Unlike NF, OSF significantly decreased the tube formation: maximal inhibition (50% of control) was obtained with 25 micrograms/ml. The OSF effect was mediated, at least in part, through the inhibition of HUVEC migration, as determined by the ability to block chemotaxis in a Transwell chamber assay. Quantitative immunoreactive assays for tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) in the culture media indicated that OSF (25 micrograms/ml) increased the accumulation of PAI-1 antigen, but not of t-PA antigen, 2.7-fold compared with control. The release of both antigens by HUVEC was slightly affected by the addition of NF. Determination of the media levels of type IV collagenase activity and tissue inhibitor of metalloproteinase-1 (TIMP-1) antigen showed that OSF (25 micrograms/ml) decreased the collagenolytic activity by 50% compared to the control, without alteration of the TIMP antigen level. However, the collagenase inhibition by OSF was not observed in an assay system using purified enzyme. NF had no effect on collagenase activity or TIMP-1 antigen levels. These results indicate that the introduction of sulfate groups into NF enables it to effectively inhibit the formation of capillary-like structures by HUVEC on Matrigel by reducing the basement membrane destruction and cell migration. It is involved as at least one of the mechanisms by which the OSF-induced increase in HUVEC PAI-1 decreases plasmin formation and suppresses the following pro-collagenase activation.

Cell Adhesion↗

PubMed1997

Changes of lipoxygenase and fatty acid hydroperoxide lyase activities in bell pepper fruits during maturation.

Developmental changes in fatty acid hydroperoxide lyase (HPO lyase) and lipoxygenase (LOX) during the maturation of bell pepper fruits (Capsicum annuum L. cv. Kyonami) were examined by means of activity measurements, immunological detection of both the enzymes, and analysis of the volatile compounds formed upon homogenization of the fruits. Both the enzyme activities decreased with maturation, and immunological studies showed that the amounts of the enzymes concomitantly decreased. The amounts of six-carbon aldehydes and alcohols formed from bell pepper fruits upon homogenization also decreased during maturation, and with the fully ripened red fruits, these volatile compounds were hardly detectable. These results suggest that the major factor contributing to the changes in the composition of volatile compounds during the maturation of bell pepper fruits was changes in the amounts of HPO lyase and LOX.

Alcohols↗

PubMed1997

Sarcocystis mihoensis n. sp. from sheep in Japan.

Sarcocystis mihoensis n. sp., a heteroxenous coccidium was detected from sheep in Japan and dogs were experimentally determined as the definitive host. The cysts were 1,300-2,100 x 200-300 microns in size and had the thick cyst wall which was 10 to 12 microns thick and provided with radial striated and finger-like villar protrusions. Two 6-month old dogs fed with the cysts passed sporocysts, 15-16 x 8-9 microns in size, in the feces from day 11 to days 57-60 after ingestion. No domestic cats fed with same cysts shed sporocysts throughout the experimental period.

Animals↗

PubMed1997

Immunohistochemical localization of connexin43 in the enamel organ of the rat upper incisor during ameloblast development.

We examined the localization of connexin (Cx)43 in the enamel organ during ameloblast development. The specificity of monoclonal anti-Cx43 antibody was elucidated by immunoblot analysis and immunoelectron microscopy. Gold particles for Cx43 were detected by immunoelectron microscopy on gap junctions but not on other structures such as desmosomes. Punctate and intense immunofluorescence for Cx43 was detected in all cell types of the enamel organ. Cx43 expression in ameloblasts showed a transient decrease and then increase during ameloblast development. Double staining of Cx43 and amelogenin, one of the enamel proteins, revealed that immunofluorescence for Cx43 markedly decreased in some late presecretory ameloblasts just prior to enamel formation. Moreover, the localization of Cx43 changed during enamel formation. Cx43 was distributed randomly on the lateral plasma membranes of presecretory ameloblasts, but tended to gather on those corresponding to the supranuclear regions of secretory ameloblasts. Immunofluorescence for Cx43 in maturation ameloblasts appeared linear rather than punctate. These results suggest that Cx43 in the late presecretory ameloblasts is degraded just before enamel formation and then newly synthesized Cx43 is redistributed during the secretory stage. These changes in Cx43 expression may be related to the cellular differentiation of ameloblasts.

Ameloblasts↗

PubMed1997

A pilot study of centrifugal leukocyte apheresis for corticosteroid-resistant active ulcerative colitis.

Corticosteroids are effective in bringing about a clinical remission in patients with ulcerative colitis. However, in severely relapsed cases, corticosteroids are not always effective even when a high dosage is administered. In addition, the long-term use of corticosteroids often causes serious side effects. Therefore, an alternative treatment for active ulcerative colitis is necessary in order to avoid these clinical problems. In the present pilot study, the efficacy of leukocytapheresis using a centrifugal procedure was evaluated for corticosteroid-resistant, active ulcerative colitis. Fourteen patients with corticosteroid-resistant severely active ulcerative colitis were treated by leukocytapheresis. Thirteen patients (92.9%) achieved clinical remission within 4 weeks after the apheresis, and remained in remission for 8 months on average without any additional corticosteroid therapy. In the remaining patient, in whom remission was not induced, a total colectomy was performed immediately after the fourth course of leukocytapheresis. No significant side effects were noticed throughout the therapy. Both colonoscopic and histological examinations confirmed the beneficial effect of this procedure in terms of the reduction of severe inflammation of the affected colon. We found that the expression of two adhesion molecules, L-selectin and VLA4a, on the surface of peripheral leukocytes was decreased after this new therapy.

Adrenal Cortex Hormones↗

PubMed1997

Mn-metalloporphyrin conjugated with Gd-DTPA (Gd-ATN10): tumor enhancement agent for magnetic resonance imaging.

A conjugate of manganese-metalloporphyrin and gadolinium (Gd)-diethylenetriaminepenta-acetic acid (Gd-ATN10) was developed as a tumor-specific enhancement agent for magnetic resonance (MR) imaging. Gd-ATN10 was evaluated in an experimental 9L gliosarcoma rat tumor model. T1-weighted MR imaging showed enhancement of the tumor which persisted for up to 24 hours. Gd concentration measurement by inductively coupled plasma atomic emission spectroscopy revealed the peak Gd concentration was reached after 30 minutes and Gd was retained in the blood and tumor up to 24 hours. There was no uptake of Gd in the normal brain and little in the skin. Gd-porphyrin derivatives are potentially useful agents for tumor diagnosis on MR imaging and for neutron capture therapy.

Animals↗