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Biomedical subjects

Y Okano

Publications and source records attributed to Y Okano.

At least 145 records · Page 8Linked to original sources
PubMed1994

Thrombin-mediated phosphoinositide hydrolysis in Chinese hamster ovary cells overexpressing phospholipase C-delta 1.

The regulatory mechanism(s) of a phosphoinositide-specific phospholipase C, PLC-delta 1, was investigated using a clone of stably overexpressed PLC-delta 1 (PLC delta 30 cells) in Chinese hamster ovary cells. Thrombin stimulation of PLC delta 30 cells exhibited 6.5-fold increase in total inositol phosphates (InsP), which was significantly higher than that in the vector-transfected (V1) cells (2.0-fold). AIF-4 increased InsP accumulation in both V1 and PLC delta 30 cells, and pertussis toxin partially blocked InsP accumulation in thrombin-stimulated PLC delta 30 cells. Guanosine thiotriphosphate (GTP gamma S) markedly potentiated thrombin-stimulated InsP generation in permeabilized PLC delta 30 cells compared with V1 cells, suggesting possible involvement of a G-protein (s) in the activation of PLC-delta 1. In PLC delta 30 cells, ionomycin-induced significant InsP generation and thrombin-stimulated InsP generation were completely inhibited by addition of EGTA. Furthermore, the stimulatory effects of thrombin plus GTP gamma S in PLC delta 30 cells were more sensitive to change in free calcium concentration than in V1 cells. Suppression by 12-O-tetradecanoylphorbol 13-acetate of thrombin-stimulated InsP accumulation was not affected by increasing Ca2+ concentration. These results indicate that thrombin-induced PLC-delta 1 activation is regulated via both G-protein(s) and calcium.

Animals↗
PubMed1994

Clinical and prognostic associations based on serum antinuclear antibodies in Japanese patients with systemic sclerosis.

OBJECTIVE: To clarify the clinical features and prognosis of systemic sclerosis (SSc) based on serum antinuclear antibodies (ANA). METHODS: We studied 275 consecutive Japanese patients newly diagnosed as having SSc, who were first evaluated during the period 1971-1990. Eight SSc-related ANA were identified using indirect immunofluorescence, double immunodiffusion, or immunoprecipitation assays. Clinical and prognostic features were retrospectively analyzed in patient groups, categorized by their serum ANA. RESULTS: Cumulative survival rates at 10 years after diagnosis of SSc were 93% in patients with anticentromere antibodies (ACA), 72% in those with anti-U1 RNP, 66% in those with anti-DNA topoisomerase I (anti-topo I), and 30% in those with anti-RNA polymerases I, II, and III (anti-RNAP). Major organ involvement linked to cause of death included biliary cirrhosis in patients with ACA, isolated pulmonary arterial hypertension and cerebral hemorrhage in those with anti-U1 RNP, pulmonary interstitial fibrosis in those with anti-topo I, and cardiac and renal involvement in those with anti-RNAP. CONCLUSION: Determinations of serum ANA in SSc patients are useful in predicting organ involvement and long-term outcome.

Adolescent↗
PubMed1994

Racial differences in the distribution of systemic sclerosis-related serum antinuclear antibodies.

OBJECTIVE: To determine racial differences in the frequencies of systemic sclerosis (SSc)-related serum antinuclear antibodies (ANA). METHODS: We tested serum samples from 275 Japanese, 416 North American Caucasian, and 24 North American black SSc patients for 8 SSc-related serum ANA, using indirect immunofluorescence, double immunodiffusion, and radioimmunoprecipitation assays. RESULTS: In comparing the 3 racial groups, we found that anti-U1 RNP, anti-RNA polymerase I, II, and III, and anti-U3 RNP antibodies were the most frequently detected antibodies in Japanese, Caucasian, and black patients, respectively. Anti-PM-Scl antibody was found exclusively in Caucasians. CONCLUSION: The production of SSc-related serum ANA is related to immunogenetic background.

Antibodies, Antinuclear↗
PubMed1994

Reduced expression of phospholipase C-delta, a signal-transducing enzyme, in rat colon neoplasms induced by methylazoxymethanol acetate.

Phospholipase C (PLC), which hydrolyzes phosphoinositides, has been implicated as a key enzyme in signal transduction. We examined the expression of an isozyme of PLC, PLC-delta, in rat colon neoplasms induced by methylazoxymethanol (MAM) acetate. Large-bowel neoplasms were observed in five of 10 rats given MAM acetate (25 mg/kg body weight, by interperitoneal injection at 6 and 7 wk of age) 40 wk after treatment. Expression of PLC-delta in the neoplasms was not detected by northern blot analysis, and a low level of expression was detected by immunoblot analysis, although PLC-delta expression was apparent in the non-neoplastic colon mucosae of MAM acetate-treated rats as well as in the colon mucosae of control rats. Furthermore, analysis by reverse transcriptase-polymerase chain reaction revealed that the ratio of the expression of PLC-delta to that of beta-actin in the neoplasms was significantly lower than the ratios in the non-neoplastic colon mucosae of carcinogen-treated and control rats (P < 0.01). However, the ornithine decarboxylase (ODC) activity in the neoplasms was significantly greater than that of the non-neoplastic and control mucosae (P < 0.001). The differences in the levels of PLC-delta expression in neoplastic and non-neoplastic tissues and the inverse correlation of PLC-delta expression with ODC activity may suggest that PLC-delta has little effect on the PLC-mediated mitogenic signaling system, at least in MAM acetate-induced colon neoplasms in rats.

Animals↗
PubMed1994

Preferential uptake of lactosylceramide-bearing dipalmitoylphosphatidylcholine-liposomes into liver: role of membrane fluidity.

The effect of the membrane fluidity of lactosylceramide (LacCer)-bearing liposomes on their liver uptake was investigated in rats. Liposomes consisting of phosphatidylcholine (PC): cholesterol:dicetylphosphate:LacCer (7:2:1:1, molar ratio) were prepared with various fluidities using dipalmitoylphosphatidylcholine (DPPC), dimyristoylphosphatidylcholine (DMPC) and egg PC. These liposomes were all equally stable in serum and were small enough to pass freely through the fenestrae and be taken up easily by liver cells. The LacCer modification of DPPC-liposomes markedly facilitated blood clearance, whereas no enhancing effect of LacCer was observed with egg PC- and DMPC-liposomes. Tissue distribution studies showed the preferential liver uptake of LacCer-bearing DPPC-liposomes, which was largely compatible with the rapid clearance induced by the LacCer modification. In addition, electron spin resonance (ESR) spectroscopic analysis revealed that the LacCer modification of DPPC-liposomes significantly enhanced the order parameter S, indicating that LacCer-bearing DPPC-liposomes were the most rigid of those used in this study. These observations suggest that the membrane fluidity of liposomes in vivo is a crucial factor for their preferential liver uptake.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1994

[Ocular histopathological studies in leprosy in the silent stage--I. Light microscopic feature].

Eyes from autopsy cases of leprosy patients (29 eyes from 16 cases) were examined histologically. In some cases immunohistochemical methods were used. In the lepromatous type, ocular complications such as keratitis and iridocyclitis were often found. In the tuberculoid type, such complications were seldom encountered. In the active stage, lepra cells and "foamy cells" showed positive reaction to acid-fast staining and anti-BCG antibody but in the silent stage they did not react. All foamy cells in both the active and the silent stage showed positive reaction to KP1, but they did not react to lysozyme or alpha 1-antitrypsin. These results suggest that the foamy cells originated from macrophages, but that their biological activity was low.

Aged↗
PubMed1994

Spontaneous Ca2+ release from a caffeine and ryanodine-sensitive intracellular Ca2+ store in freshly prepared hepatocytes.

A considerable fraction of freshly prepared hepatocytes loaded with the fluorescent [Ca2+]i indicator fura-2 exhibited spontaneous rhythmic fluctuations that tended to decrease with increasing length of incubation after isolation. These oscillations were dependent on the external Ca2+. They could no longer be observed when a Ca2+ chelator-(ethylenebis [oxyethylenenitrilo]) tetraacetic acid--was added to medium. Addition of thapsigargin, which is known to release Ca2+ from inositol 1,4,5-trisphosphate-sensitive and -insensitive Ca2+ stores, induced a large transient increase in [Ca2+]i and abolished the fluctuations. When the cells were treated with 2 mmol/L caffeine, frequency was increased, whereas 10 mmol/L caffeine induced a single large peak followed by a persistent plateau. Moreover, addition of dibutyryl cAMP led to decreased frequency of fluctuations. Ryanodine caused larger fluctuations; thereafter the [Ca2+]i level became much higher and the spikes ceased. These results suggest that spontaneous rhythmic fluctuations in freshly prepared hepatocytes are driven by Ca2+ release from a caffeine- and ryanodine-sensitive calcium-induced calcium release pool.

Animals↗
PubMed1993

Autoantibody reactive with RNA polymerase III in systemic sclerosis.

OBJECTIVE: To determine the clinical significance of anti-RNA polymerase III antibody in systemic sclerosis (SSc). DESIGN: A point prevalence study of autoantibody to RNA polymerase III and longitudinal examination of its clinical significance in patients with SSc and in controls. SETTING: University medical center rheumatology practice. PATIENTS: Two hundred fifty-two consecutive new patients with SSc and 170 controls (150 patients with other connective tissue diseases and 20 normal volunteers). MEASUREMENTS: The presence of anti-RNA polymerase III antibody was determined by immunoprecipitation, immunoblotting, and immunodepletion studies. MAIN RESULTS: Serum specimens from 57 of the 252 patients with SSc (23%; 95% CI, 18% to 28%) reacted with RNA polymerase III, compared with none of the specimens from 170 controls (0%; 95% CI, 0% to 2%). In 40 of these 57 specimens, immunoprecipitation studies also showed the presence of RNA polymerase I or II, or both. Anti-RNA polymerase III antibody was detected in sera from 50 of the 111 patients (45%) who had SSc with diffuse cutaneous involvement (dcSSc), 7 of 114 patients (6%) who had SSc with limited cutaneous involvement, and none of 27 patients with an SSc overlap syndrome (P < 0.001). Among patients with dcSSc, anti-RNA polymerase III antibody was more common than antitopoisomerase I antibody (45% compared with 27%; P = 0.008). Patients with anti-RNA polymerase III antibody had a statistically significant higher mean maximum skin thickness score but statistically significant lower frequencies of telangiectasias, inflammatory myopathy, restrictive lung disease, and serious cardiac abnormalities than did patients with antitopoisomerase I antibody. CONCLUSION: Anti-RNA polymerase III antibody is a new marker autoantibody for many patients who have SSc with diffuse or extensive cutaneous involvement.

Antibodies, Antinuclear↗
PubMed1993

Protein kinase C-dependent expression of type I transglutaminase mRNA in ganglioside GQ1b- and calcium-stimulated human keratinocytes.

Ganglioside GQ1b was found to induce terminal differentiation in normal epidermal keratinocytes (Yada et al. (1991) Biochem. J. 279, 665-670). In GQ1b-stimulated human keratinocytes, the increase in mRNA expression of Type I TGase preceded the increases in the TGase activity. The enhancement of its mRNA expression was inhibited when protein kinase C (PKC) was suppressed by pretreatment with an inhibitor, H-7, or down-regulation by long-term preincubation with phorbol dibutyrate. These results indicate that PKC is involved in the activation of TGase probably via gene expression of TGase mRNA in GQ1b-induced human keratinocyte differentiation. Similar results were also obtained in Ca(2+)-induced differentiation.

Calcium↗
PubMed1993

Tyrosine phosphorylation of phospholipase C gamma in c-met/HGF receptor-stimulated hepatocytes: comparison with HepG2 hepatocarcinoma cells.

Hepatocyte growth factor (HGF) stimulates inositol 1,4,5-trisphosphate (InsP3) formation in rat primary cultured hepatocytes, which is inhibited by the pretreatment with a tyrosine kinase inhibitor, genistein. This InsP3 production was coincident with tyrosine phosphorylation of phospholipase C gamma (PLC gamma), detected in immunoprecipitates with anti-PLC gamma, suggesting activation mechanism of PLC gamma by tyrosine phosphorylation. However, in human hepatocarcinoma HepG2 cells, HGF, which suppresses cell growth, causes neither phosphorylation of PLC gamma nor InsP3 formation. The results suggests that PLC gamma in normal hepatocytes was activated by HGF through tyrosine kinase of HGF receptor.

Animals↗
PubMed1993

Ganglioside-induced terminal differentiation of human keratinocytes: early biochemical events in signal transduction.

Previous studies have indicated that GQ1b, a tetrasialoganglioside containing two disialosyl residues, may be an important regulator of cellular differentiation in murine keratinocytes. In the present study, we examined the effect of gangliosides on the differentiation of human keratinocytes. Current evidence indicates that GQ1b induces cornified envelope formation and enhancement of transglutaminase (TGase) activity, which are characteristic parameters of terminal differentiation in human cultured keratinocytes, while the other gangliosides, GT1b and GM1, are much less effective. The mass contents of inositol 1,4,5-trisphosphate (1,4,5-IP3) and the intracellular calcium concentration ([Ca2+]i) were also measured in keratinocytes exposed to gangliosides. A rapid increase in 1,4,5-IP3 occurred at 30 s following stimulation, but no significant difference at the maximum level was observed among the three gangliosides in contrast to the finding in murine keratinocytes. In addition, [Ca2+] increases occurred concurrently with the 1,4,5-IP3 generation by the three gangliosides. On the other hand, [Ca2+] transients were unaffected by chelating extracellular Ca2+ with EGTA. It is thus considered that the mobilization by 1,4,5-IP3 from internal stores plays a crucial role. These [Ca2+]i profiles were also indistinguishable between the gangliosides. Taken together, in human keratinocytes, gangliosides differentially affect some other as yet unidentified site(s) in the post-calcium transmission pathway(s) which leads to TGase activation.

Calcium↗
PubMed1993

Phospholipase C activity in cerebrospinal fluid following subarachnoid hemorrhage related to brain damage.

Phosphoinositide-specific phospholipase C (PLC) activities were measured in CSF from patients after subarachnoid hemorrhage (SAH). Their PLC activities were significantly higher than those in control CSF. Moreover, there was an obvious correlation between the PLC activity in CSF collected on day 3 and the preoperative clinical grade. The PLC activity was also closely correlated with the level of neuron-specific enolase as a marker of brain damage. Furthermore, the PLC activities were partially purified from CSF of patients after SAH and were immunologically identified to be PLC beta, PLC gamma, and PLC delta. These results suggest that PLCs are released into the CSF from brain tissue in conjunction with the initial hemorrhage and that their activity may reflect the extent of brain damage.

Aneurysm, Ruptured↗
PubMed1993

Biological activity of the endothelin family in cultured basilar arterial smooth muscle cells.

The effects of three forms of endothelin (ET), ET-1, -2 and -3, on intracellular free Ca2+ concentration ([Ca2+]i), their receptor binding activities, and DNA synthesis were investigated in cultured porcine basilar arterial smooth muscle cells. Endothelin-1 and ET-2 induced cytosolic free calcium elevations that did not return to the basal level. The maximum levels of [Ca2+]i induced by the three points were ET-1 approximately equal to ET-2 > ET-3. The cells display specific binding of 125I-labelled endothelin-1 which was displaced by three endothelins; ET-1, -2, and -3, in a concentration-dependent manner. The order of potency in inhibiting 125I-labeled endothelin-1 binding was ET-1 approximately equal to ET-2 > ET-3. Endothelin-1, ET-2, and ET-3 stimulated [3H]thymidine incorporation in a dose-dependent manner, the maximum order of potency (100 nM) was again ET-1 approximately equal to ET-2 > ET-3. These results indicate that ET-1 and ET-2 are more potent in their biological activities than ET-3 in cultured cerebral arterial smooth muscle cells.

Animals↗