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Biomedical subjects

H Katsuta

Publications and source records attributed to H Katsuta.

At least 19 recordsLinked to original sources
PubMed2005

In vivo evaluation of ocular inflammatory responses in experimental diabetes.

AIMS: Diabetic patients may have abnormal inflammatory reactions to foreign or endogenous stimuli. This study was designed to evaluate inflammatory reactions in the diabetic eye through retinal leucocyte dynamics in the inflamed eyes of diabetic rats. METHODS: Three weeks after diabetes induction in Long-Evans rats, endotoxin induced uveitis was produced by footpad injection of lipopolysaccharide (LPS). After LPS injection, leucocyte behaviour was evaluated in vivo by acridine orange digital fluorography. RESULTS: The number of rolling leucocytes increased in a biphasic manner at 12 hours and 48 hours. The number of leucocytes accumulating in the retina reached a peak at 72 hours. The maximal numbers of rolling and accumulating leucocytes in the diabetic retina decreased by 56.3% (p<0.01) and 46.7% (p<0.0001), respectively, compared with the non-diabetic retina. The levels of mRNA expression of adhesion molecules in the retina, which were upregulated after LPS injection, were also lower in diabetic rats than in non-diabetic rats. CONCLUSION: This study is the first to show that endotoxin induced inflammation is disturbed in the diabetic eye, based on evidence that the leucocyte-endothelial cell interactions stimulated by LPS were suppressed in the diabetic retina. These findings support the theory that ocular inflammatory reactions are impaired in diabetic patients.

Animals↗
PubMed2001

Mastoparan stimulates GABA release from MIN6 cells: relationship between SNARE proteins and mastoparan action.

We examined the action of mastoparan on beta cell exocytosis. Mastoparan stimulated GABA and insulin release from MIN6 beta cells. On the other hand, mastopraran-induced GABA release was decreased by expressing the tetanus toxin C1 light chain in MIN6 cells. We have then investigated the relationship between SNARE proteins and mastoparan action using adenovirus-mediated gene transfer system. Overexpression of t-SNAREs, syntaxin 1A, and SNAP-25 inhibited the mastoparan-induced insulin release by approximately half-fold of control levels, however, the mastoparan-induced GABA release was not affected by these t-SNAREs overexpression. The overexpression of mutant alpha-SNAP (1-285), which inhibits the wild-type alpha-SNAP function in a dominant negative manner, did not influence either mastoparan-induced GABA or insulin release in spite of its marked inhibition of glucose-stimulated insulin release. Our data indicate that mastoparan stimulates GABA exocytosis via vesicular transport; however, SNARE proteins are differently involved in the exocytosis of insulin and GABA.

Animals↗
PubMed2001

Transforming growth factor-beta 2 levels in aqueous humor of glaucomatous eyes.

PURPOSE: To determine whether clinical characteristics are correlated with increased levels of transforming growth factor-beta 2 (TGF-beta 2) in aqueous humor in glaucomatous eyes. METHODS: Aqueous humor samples were collected from 91 glaucomatous eyes. Included were samples from primary open-angle glaucoma (POAG) in 40 eyes, (pseudo)exfoliation syndrome (EXS) in 18 eyes, primary angle-closure glaucoma (PACG) in 26 eyes and uveitis-related secondary glaucoma (SG) in 7 eyes. TGF-beta 2 in aqueous humor was assessed with a specific-capture ELISA. RESULTS: The mean concentration (+/- standard error) of mature (biologically active) TGF-beta 2 in the aqueous humor of eyes with POAG was 293.6 +/- 33.6 pg/ml, significantly higher than that in eyes with PACG, EXS and SG: 147.5 +/- 28.1, 135.8 +/- 30.2 and 41.0 +/- 10.7 pg/ml, respectively (P = 0.0006, P = 0.0010 and P = 0.0003; analysis of variance). The mean concentration (+/- standard error) of total TGF-beta 2 in the aqueous humor of eyes with POAG was 1647.6 +/- 124.5 pg/ml, not significantly different from that in eyes with PACG, EXS and SG: 1482.9 +/- 148.2, 1442.7 +/- 187.8 and 1929.0 +/- 367.6 pg/ml, respectively. A multivariate analysis using logistic regression showed significant correlations between mature TGF-beta 2 concentration and history of cataract surgery (P = 0.0225) and the use of carbonic anhydrase inhibitors (P = 0.0143). CONCLUSIONS: Our results indicate that increased levels of TGF-beta 2 may play an important role in the pathogenesis of POAG.

Aged↗
PubMed2000

Suppression of insulitis and diabetes in B cell-deficient mice treated with streptozocin: B cells are essential for the TCR clonotype spreading of islet-infiltrating T cells.

In order to clarify the role of B cells in the development of insulitis and diabetes, B cell-deficient (B(-)) mice treated with streptozocin (STZ) were studied. The extent of insulitis and the cumulative incidence of diabetes were significantly suppressed in B(-) mice (P < 0.0001), indicating that B cells are crucial for the progression of insulitis and diabetes. Accumulation of both CD4(+) T cells and B cells was observed in islets of B(+) mice, while CD4(+) T cells but not B cells were found in B(-) mice. A few CD8(+) T cells and macrophages were detectable in both types of mice. The immunohistochemical study did not reveal any change in the subpopulations of infiltrating lymphocytes except for the absence of B cells in the B(-) mice. TCR V(beta) gene repertoire usage of islet-infiltrating T cells was restricted to some extent in the B(+) or B(-) mice, but there was no significant difference between the B(+) and B(-) mice, suggesting that the initial islet-reactive T cell response can occur in the absence of B cells. In contrast, TCR clonotype spreading of islet-infiltrating T cells was significantly suppressed in B(-) mice compared with B(+) mice (P < 0.0001). These data suggest that initial priming of T cells is not impaired and TCR V(beta) repertoire usage is not limited by the lack of B cells, while B cells are important essentially for the spreading of islet-infiltrating clonal T cells in autoimmune diabetic mice induced with STZ.

Animals↗
PubMed2000

Terson syndrome caused by ventricular hemorrhage associated with moyamoya disease--case report.

A 24-year-old female presented with Terson syndrome secondary to bilateral ventricular hemorrhage as a complication of moyamoya disease. Ophthalmoscopy and magnetic resonance imaging clearly demonstrated vitreous hemorrhage in the left eye globe. Various visual symptoms are associated with moyamoya disease, almost all of which result from ischemic lesions in the visual cortex and optic pathways. In this case, the visual disturbance was caused by Terson syndrome secondary to ventricular hemorrhage. Close ophthalmological and radiological evaluation is mandatory even in patients with moyamoya disease and hemorrhagic manifestation located in the intracerebral, subarachnoid, or intraventricular space.

Adult↗
PubMed1999

Establishment of an embryonic stem (ES) cell line derived from a non-obese diabetic (NOD) mouse: in vivo differentiation into lymphocytes and potential for germ line transmission.

A non-obese diabetic (NOD) mouse-derived embryonic stem (ES) cell line has been stably maintained in an undifferentiated state with a characteristic ES cell-like morphology, expressing the stem cell marker alkaline phosphatase, and displaying a normal diploid karyotype. After injecting the NOD-ES cells into blastocysts, chimeric mice were obtained. Small but significant numbers of lymphocytes expressed the NOD-derived MHC allele. When a chimeric mouse was mated with C57BL/6 mice, an agouti mouse was obtained, having the NOD-derived H-2 I-A(beta)g7 haplotype. Thus, an NOD-ES cell line which can differentiate into lymphocytes with potential for germ line transmission was successfully established.

Animals↗
PubMed1998

Lyn-mediated down-regulation of B cell antigen receptor signaling: inhibition of protein kinase C activation by Lyn in a kinase-independent fashion.

Stimulation of the B cell Ag receptor (BCR) induces activation of tyrosine kinases such as Lyn and Syk, phosphorylation and activation of multiple signaling components, and eventually, the expression of several genes including c-myc. Syk is required for activation of phospholipase C-gamma 2 and the subsequent phosphatidylinositol hydrolysis, leading to protein kinase C (PKC) activation and intracellular Ca2+ increase. In contrast, the function of Lyn remains obscure. Here, we report that BCR-mediated induction of c-myc promoter activity and of PKC activity, but not the expression level of functional PKC, was markedly augmented in Lyn-deficient chicken B cells. This enhancement was reversed to the level of wild-type cells by the expression of exogenous Lyn of kinase-inactive form. These results indicate that Lyn inhibits BCR-mediated activation of a large portion of PKC isozymes in a kinase-independent fashion. This finding reveals a novel role of Lyn in negative regulation of BCR signaling.

Animals↗
PubMed1998

Task-related coherence and task-related spectral power changes during sequential finger movements.

In order to investigate the activity of cortical regions in the control of complex movements, we studied task-related coherence (TRCoh) and task-related spectral power (TRPow) changes in 8 right-handed subjects during the execution of 4 different finger movement sequences of increasing complexity. All sequences were performed with the right hand and were paced by a metronome at 2 Hz. EEG power spectra and coherence values were computed within alpha (8-12 Hz) and beta (13-20 Hz) frequency bands for 29 scalp EEG positions during the execution of the sequences and were compared with values obtained during a rest (control) condition. Movement sequences were associated with TRPow decreases in the alpha and beta frequency bands over bilateral sensorimotor and parietal areas, with a preponderance over the contralateral hemisphere. Increases of TRCoh occurred over bilateral frontocentral regions. TRCoh decreases were present over the temporal and occipital areas. The spatial extent and the magnitude of TRPow decreases and TRCoh increases in both frequency bands were greater for sequential movements of higher complexity than for simpler ones. These results are consistent with previous findings of bilateral activation of sensorimotor areas during sequential finger movements. Moreover, the present results indicate an active intercommunication between bilateral and mesial central and prefrontal regions which becomes more intense with more complex sequential movements.

Adult↗
PubMed1980

Establishment of tissue culture cell strains from normal fetal human liver and kidney.

Three cells strains of tissue culture were established from normal fetal human liver and kidney tissues. The rate of cell proliferation decreased with time after the primary culture. The cells were rarely subcultured, but the medium was renewed routinely twice a week. After 9 months of cultivation, the cells were found in both tissues to have abruptly begun to proliferate rapidly, but only in the group culture in the medium containing galactose and sodium pyruvate in place of glucose. No special treatment were given to these cultures, e.g. treatment with viruses, chemical carcinogens and others. The chromosome number was kept around diploid in the beginning but was shifted to hypotriploid after the establishment. The cell strain from liver consists of epithelial cells. The cell strains from kidney consist of mixed population of various kinds of cells. Doubling time of cells is about 33.4 hours in all of them, as determined by cinemicrography. This might be the first establishment of cell strains from untreated, normal human tissues.

Cell Division↗
PubMed1980

Neutralization of cytotoxicity of spermine on the proliferation of rat liver cells in tissue culture.

Cytotoxicity of spermine in tissue culture was found previously. To neutralize this toxicity, the addition of various high molecular weight substances and others was attempted in this paper, e.g. lysozyme, N-acetyl-D-glucosamine, chondroitin sulfate, poly-L-glutamic acid, bovine serum fractions V and VI, fetal calf serum, methyl cellulose, carboxymethyl cellulose, polyvinylpyrrolidone and others. Into the culture of rat liver cells, strain RLC-10(2), simultaneous addition of other substances with spermine did not neutralize the toxicity. However, by the pretreatment of spermine with fetal calf serum or bovine serum albumin (fraction V) at 37 degrees C for 24 hr, the toxicity of spermine was markedly reduced. This was probably due to the denaturation of spermine caused by the pretreatment.

Animals↗
PubMed1980

An attempt in tissue culture at preventing and treating the collagen fiber formation of liver cells.

To prevent and to cure liver cirrhosis, we examined the effect of the ethanol extract of berries of Japanese ampelopsis on the collagen formation of rat liver cells in tissue culture. These cells had been transformed to produce collagen fibers very actively. When added at a time of subcultivation, the extract prevented the formation of collagen fibers. When it was added after the formation of collagen fibers, the fibers were fragmented into fine microfilaments.

Animals↗
PubMed1979

Tapping culture--an improved method for cell suspension culture.

A new culture vessel was designed for cell suspension culture. A silicone-covered magnet bar fixed by one end to the side wall of the bottle was held horizontally a short distance from the bottom. A standard type magnetic stirrer was used. In contrast to the conventional horizontal movement of "stirring" in cultures the bar moves vertically with a "tapping" motion. This improvement resulted in less cell injury, higher rate of cell proliferation and formation of fewer bubbles than in the conventional type. Nine cell types were simultaneously cultivated in tapping, stirring and stationary culture. All cell types proliferated more luxuriously in tapping cultures then in stirring cultures. Serial cultivation of cells in tapping cultures was also successful.

Animals↗
PubMed1979

Carcinogenesis in tissue culture 30: malignant transformation of normal rat liver cells treated with diethylnitrosamine in tissue culture with special reference to the differential effects of cytochalasin B on various cells with and without tumorigenicity.

Liver tissue of a suckling rat was cultured. After 3 weeks of cultivation, the cultures consisting of epithelial cells were treated with 50 micrograms/ml or 100 micrograms/ml DEN for 7 days. 5 months after the treatment, the mode of chromosome number was found decreased from 42 to 40 in the 100 micrograms/ml DEN-treated group and shifted to triploid range after 21 months. The mode in the 50 micrograms/ml DEN-treated group maintained the diploid number until the 5th month but was found reduced to 40 in 21 months. On subcutaneous backtransplantation into young rats at the 22nd month, the treated cells produced tumors at the site inoculated in all the rats. Metastatic foci were also detected in lungs. These tumors were histologically diagnosed as hepatomas. Untreated control cells did not produce tumors. The differential effects of cytochalasine B on the cells with and without tumorigenicity were examined by the use of these cells and other cells, and it revealed that the capacity of multinucleated cell-formation by cytochalasin B fairly corresponds with the backtransplantability of the cells. Binucleated cell formation, not more than 2 nuclei, in the culture of normal cells was found by time-lapse cinemicrography to be not due to the non-capacity of multinucleation but to the destruction of multinucleated cells.

Animals↗