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Biomedical subjects

M Oka

Publications and source records attributed to M Oka.

At least 343 records · Page 19Linked to original sources
PubMed1995

Thermosensitivity of green fluorescent protein fluorescence utilized to reveal novel nuclear-like compartments in a mutant nucleoporin NSP1.

Tagging proteins with the green fluorescent protein (GFP) from Aequorea victoria is a good means of analyzing protein localization in living cells. Nevertheless, GFP and a chimeric protein, GFP-nucleoplasmin, expressed in Saccharomyces cerevisiae were less fluorescent at high culture temperatures. Proteins synthesized at a low temperature retained their fluorescence despite a shift to a higher temperature. Hence, when a temperature-sensitive nsp1 mutant expressing GFP-nucleoplasmin was cultured at 23 degrees C and then shifted to 35 degrees C, we were able to exclusively monitor the localization of the protein synthesized prior to the temperature shift. This protein accumulated in novel nuclear-like compartments devoid of DNA.

Amino Acid Sequence↗
PubMed1995

Lansoprazole for maintenance therapy of peptic ulcer disease: weekend full-dose or everyday half-dose administration?

Seventy-one patients with peptic ulcer (44 gastric ulcer and 27 duodenal ulcer patients) were enrolled in this study. After the ulcers had healed with 2 months of treatment with lansoprazole (LPZ) 30 mg/day, patients were divided into two groups: 43 in the half-dose q.d. group and 28 in the weekend full-dose group. Fourteen (23%) of the 43 patients in the half-dose q.d. group and 14 of the 28 (50%) in the weekend full-dose group failed to continue taking the drug for 6 months owing to poor compliance (p < 0.05). None of the 30 patients who continued to take the maintenance dose of LPZ experienced ulcer recurrence during the 6-month follow-up period, whereas 71% of the patients who stopped taking LPZ experienced recurrence (p < 0.01). In conclusion, maintenance therapy using the half-dose q.d. administration schedule was superior to weekend full-dose administration because of the better patient compliance and a lower ulcer recurrence rate.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Differential down-regulation of protein kinase C subspecies in normal human melanocytes: possible involvement of the zeta subspecies in growth regulation.

Normal human melanocytes are often grown in vitro in the continuous presence of 12-O-tetradecanoylphorbol-13-acetate (TPA) for growth in vitro. The expression of protein kinase C (PKC) subspecies, which are the major cellular receptors for phorbol esters, was examined in melanocytes after long-term treatment with TPA to investigate the role of PKC subspecies in TPA-dependent cell growth. The PKC enzyme activity detected in quiescent melanocytes was almost completely depleted in cells after incubation with 85 nM TPA for 48 h. Immunoblot analysis indicated that, among the PKC subspecies alpha, beta, delta, epsilon, and zeta expressed in quiescent cells, alpha-, beta-, delta-, and epsilon-PKC were significantly down-regulated, whereas zeta-PKC remained at detectable levels in TPA-treated cells. TPA did not significantly affect the expression or subcellular distribution of zeta-PKC in melanocytes. Immunoprecipitation assay revealed that the enzyme activity of zeta-PKC was increased in both the cytosol and particulate cell fractions, but the increase was much greater in the latter. The activation of zeta-PKC lasted for 24 to 48 h after the addition of TPA; thereafter, zeta-PKC activity returned to basal levels. DNA synthesis was shown to change concomitantly with the activation of zeta-PKC in TPA-treated cells. These results indicate that TPA induces not only the down-regulation of alpha-, beta-, delta-, and epsilon-PKC, but also long-term activation of zeta-PKC in melanocytes, and that activation of zeta-PKC parallels the growth of normal human melanocytes.

Cell Division↗
PubMed1995

Strain variation in susceptibility to the development of monoclonal antibody 5-1-6-induced proteinuria in rats.

Susceptibility to the development of MoAb 5-1-6-induced proteinuria was investigated in four different rat strains, i.e. Brown-Norway (BN), Lewis (LEW), Sprague-Dawley (SD) and Wistar. An intravenous injection of 5 mg of MoAb 5-1-6 to female 7-week-old rats of a given strain induced massive proteinuria in BN, LEW and Wistar rats. However, SD rats developed almost no proteinuria. A similar tendency was observed in the second experiment, in which the injected dose of MoAb was adjusted according to the body weight of each rat (3 mg/100 g body weight). Immunofluorescence (IF) and immunoelectron microscopy (IEM) revealed no differences between the binding patterns of the MoAbs to normal rat kidneys derived from each strain. Quantitative study using 125I-labelled MoAb showed that there was no significant difference in the amount of antibody bound to the kidney 1 h and 5 days after injection between two rat strains, LEW and SD. Localization of 5-1-6 in vivo and its kinetics were investigated. In IF a linear-like pattern along capillary walls was observed 2 h after injection in both LEW and SD strains. This linear-like pattern was shifted to a granular pattern in proteinuric LEW rats 6 days after injection, whereas it remained linear-like in non-proteinuric SD rats. IEM confirmed this difference in the localization of injected MoAb 6 days after injection to LEW and SD rats also at the ultrastructural level. We conclude that there is a clear-cut strain difference in the development of proteinuria induced by MoAb 5-1-6. SD rats were less susceptible to MoAb-induced glomerular injury than BN, LEW and Wistar rats. Although the exact reason for strain variation in susceptibility to MoAb-induced proteinuria remains to be clarified, the movement of bound MoAb, presumably together with corresponding antigenic molecule along the glomerular epithelial cell surface followed by endocytosis into the epithelial cell, seems to be closely related to the induction of proteinuria.

Animals↗
PubMed1995

Disseminated intravascular coagulopathy in infection compared with that in malignant neoplasia.

The organic symptoms and results of coagulation tests of disseminated intravascular coagulopathy (DIC) in 17 patients with infection were compared with those in 12 patients with malignancy. The infectious diseases were mainly sepsis and pneumonia, and the malignancy was mainly lung cancer. The mean antithrombin III (AT III) before treatment was 54% in infection and 68% in malignancy, and the AT III values improved after administration of 1500 U of AT III concentrates per day. The mean thrombin-antithrombin complex level decreased from 22 ng/ml to 9 ng/ml after the treatment in infection, but it increased in malignancy. There were no differences in DIC scores between infection and malignancy before treatment; however, the scores were significantly more improved in infection than in malignancy after treatment (p < 0.05). The fibrin/fibrinogen degradation product level, platelet count, and fibronectin level were also significantly more improved in infection than in malignancy. This better response to treatment in infection than in malignancy is probably due to eradication of the causative organisms by antibiotics in infection. These data suggest that therapy against both DIC and the underlying disease is crucial for successful treatment.

Aged↗
PubMed1995

Effects of separate and combined ETA and ETB blockade on ET-1-induced constriction in perfused rat lungs.

To evaluate the role of endothelin (ET) receptors in ET-1-induced pulmonary vasoreactivity, we studied the effects of ET-receptor agonists and antagonists in isolated perfused rat lungs. ET-1 (1-10 nM) caused concentration-dependent pulmonary vasoconstriction and gross pulmonary edema at a concentration of 10 nM. The combination of the selective ETA antagonist BQ-123 and the selective ETB antagonist BQ-788 inhibited ET-1-induced pulmonary vasoconstriction more effectively than BQ-123 alone, whereas BQ-788 alone enhanced the constriction. ET-1-induced hydrostatic pulmonary edema was prevented by the combination of BQ-123 and BQ-788 but not by either BQ-123 or BQ-788 alone. After the addition of 125 ng of exogenous ET-1, the perfusate levels of ET-1 were significantly higher in BQ-788-treated lungs than in either the vehicle control or BQ-123-treated lungs. The selective ETB agonist IRL-1620 also caused pulmonary vasoconstriction and edema, both of which were completely inhibited by BQ-788. ET-1-induced transient vasodilation was abolished by BQ-788 but was unaffected by BQ-123. These results suggest that in the isolated perfused rat lung, ET-1-induced vasoconstriction is mediated by both ETA and ETB receptors, whereas ET-1-induced transient vasodilation is mediated exclusively by the ETB receptor. Blockade of ETB receptors may result in enhanced ET-1 activity (via the ETA receptor) through inhibition of the ETB-mediated clearance of ET-1. Thus combined ETA and ETB blockade is required for the complete inhibition of ET-1-induced vasoconstriction in the rat pulmonary circulation.

Animals↗
PubMed1995

Immunohistochemical and biochemical detection of low density lipoprotein receptors in cultured rat mesangial cells.

The expression of low density lipoprotein (LDL) receptors by cultured rat mesangial cells was demonstrated using immunohistochemical and biochemical methods. Using a mouse monoclonal anti-human LDL receptor antibody, the immunofluorescence technique was applied to cultured mesangial cells and showed granular staining. Immunoblotting analysis of the membrane fraction of cultured mesangial cells showed a single band with a protein of approximately 130,000 molecular weight. In addition, [125I]LDL binding and the uptake of [125I]LDL by cultured mesangial cells were studied. Binding and uptake both reached an equilibrium after about 30 min of incubation. A 50% reduction in [125I]LDL (20 micrograms protein/ml) binding and uptake occurred when unlabelled LDL was added to cultures at 20-40 micrograms protein/ml. Addition of high density lipoprotein without apoE to the culture medium did not induce competitive inhibition of [125I]LDL binding and uptake by mesangial cells. These findings suggest that cultured mesangial cells have the capacity to express an LDL receptor that regulates the cellular uptake of LDL.

Animals↗
PubMed1995

Cloning of the creatinine amidohydrolase gene from Pseudomonas sp. PS-7.

The gene encoding creatinine amidohydrolase (EC 3.5.2.10) was isolated from Pseudomonas sp. PS-7. The primary structure of creatinine amidohydrolase deduced from the nucleotide sequence showed that the protein is composed of 259 amino acids and has a molecular weight of 28,437. The enzymatic property of creatinine amidohydrolase produced by recombinant E. coli was identical with those by Pseudomonas sp. PS-7.

Amidohydrolases↗
PubMed1995

Physiological significance of plasma sulfoconjugated dopamine: experimental and clinical studies.

Sulfoconjugated catecholamines have been regarded simply as metabolites of free catecholamines. However, a conjugated form of the catecholamine, dopamine has recently attracted much attention because it is present at high levels in the plasma of humans and experimental animals. We carried out experimental and clinical studies to determine the physiological significance of this large amount of dopamine conjugate in the plasma. Clinical studies showed that the plasma level of dopamine sulfate decreased significantly during the acute phase of heart failure, whereas that of free dopamine increased. Moreover, the plasma level of conjugated dopamine in patients with essential hypertension was higher than that in control subjects, and being highest in patients with renal hypertension. In experimental studies, we examined the activity for deconjugating DA sulfate in homogenates of organs from dogs. The kidney and liver exhibited the highest activities, and in the heart, the activity was higher in the atrium than the ventricle. We also examined the effect of dopamine sulfate on isolated perfused rat heart. Dopamine sulfate was found to be converted to free dopamine, which was responsible for the positive inotropic action, in atrial tissue. Moreover, deconjugation of DA sulfate to the free form was accelerated by a high work lord on the heart. From these results, we conclude that the formation of dopamine sulfate plays a role in regulating the level of plasma free dopamine and that plasma dopamine sulfate may be a storage or reserve form of dopamine. Free (or active) dopamine may be formed through a deconjugation reaction when necessary.

Adult↗
PubMed1995

Pituitary adenylate cyclase-activating polypeptide stimulates the synthesis of dopamine in cultured bovine adrenal chromaffin cells.

The effect of pituitary adenylate cyclase-activating polypeptide1-38 (PACAP1-38) on the synthesis of dopamine in cultured bovine adrenal chromaffin cells was examined. PACAP1-38 stimulated [14C]dopamine synthesis from [14C]tyrosine, in a concentration-dependent manner, causing maximal stimulation at 10(-7)M. This stimulatory action of PACAP1-38 was not significantly inhibited by staurosporine (an inhibitor of protein kinase C) or in the cells in which protein kinase C was down-regulated by prolonged exposure to TPA (an activator of protein kinase C), whereas it was partially attenuated in Ca(2+)-free medium. PACAP1-38 increased the formation of [3H] inositol phosphates, [Ca2+]i, 45Ca2+ uptake and cAMP level. The peptide also stimulated the phosphorylation of tyrosine hydroxylase, the enzyme catalyzing the rate-limiting step in dopamine synthesis. Dopamine synthesis and tyrosine hydroxylase phosphorylation stimulated by the maximal effective concentration of dibutyryl cAMP or high K+, which activates Ca2+ uptake, were further enhanced by PACAP1-38. These results indicated that PACAP1-38 may stimulate the activities of cAMP- and calcium-dependent protein kinases in cultured bovine adrenal chromaffin cells, resulting in increase in the synthesis of dopamine probably by stimulation of phosphorylation of tyrosine hydroxylase.

Animals↗
PubMed1995

Arteriovenous malformation of the bronchial artery showing endobronchial protrusion.

The bronchoscopic findings of arteriovenous malformation of the bronchial artery are compared with findings on angiography and pathology. A non-pulsatile protrusion with engorged vessels on its glossy and uneven surface was seen at the distal portion of the right anterior segmental bronchus. A bronchial angiogram demonstrated that the protrusion corresponded to the hypervascular area of convoluted vessels. Histologically, a glossy, uneven surface and engorged vessels represented normal mucosa overlaying an extramuscular tortuous artery and proliferation of submucosal tiny vessels, respectively. These bronchoscopic findings were important clues for diagnosis.

Arteriovenous Malformations↗
PubMed1995

The senescence of oat leaf segments is promoted under simulated microgravity condition on a three-dimensional clinostat.

Plants have evolved on the earth, indicating the morphology, growth and development, and life cycle of plants are highly influenced by gravity as well as other environmental stimuli. Indeed, simulated microgravity on a clinostat or hypergravity on a centrifuge has recently been reported to change the growth and development of plants (Hoson et al. 1992, 1993, 1995, Rasmussen et al. 1994, Kasahara et al. 1995). Senescence is a final drastic phenomenon in life cycle of plants, which is characterized by the loss of total chlorophyll and protein, and/or the formation of the abscission (Osborne 1973, Thimann 1977, Addicott 1982). Many environmental stimuli as well as the qualitative and quantitative changes of plant hormones have been reported to affect plant senescence. Among those stimuli, light is the most important factor to regulate plant senescence (Leopold 1964). Dark condition promotes leaf senescence due to the decrease in endogenous level of cytokinin and/or the increase in that of abscisic acid or ethylene (Tetley and Thimann 1974, Gepstein and Thimann 1980). However, there are few reports concerning the effect of gravity on leaf senescence. Strenuous effort to learn leaf senescence under microgravity condition has been done using a three-dimensional (3-D) clinostat. In this paper, we report that simulated microgravity condition on a 3-D clinostat promoted the senescence of oat leaf segments in the dark. A possible mechanism of microgravity condition on promoting the senescence is also discussed.

Abscisic Acid↗
PubMed1995

Effect of simulated microgravity on auxin polar transport in inflorescence axis of Arabidopsis thaliana.

The morphology, growth and development of higher plants are strongly influenced by environmental stimuli on the earth, which affect the changes in the dynamics of plant hormones in plants. Qualitative and quantitative changes in plant hormones are the most important internal factor to regulate plant growth and development. Among them, auxin (IAA) is of most significant. There are numerous reports concerning the physiological roles of auxin in plant growth and development (Matthysse and Scott 1984). One of the characteristics of auxin is to have the ability of polar transport along the vector of gravity on the earth (Schneider and Wightman 1978), suggesting that the activity of auxin polar transport is also important for the growth and development of plants. It has recently been reported that the normal activity of auxin polar transport in inflorescence axis of Arabidopsis thaliana was required for flower formation (Okada et al. 1991, Ueda et al. 1992). Considering the above evidence together with the fact that gravity affects the morphology, growth and development of higher plants, gravity might affect the qualitative and quantitative changes in plant hormones including the activity of auxin polar transport. In this paper, we report the effect of microgravity condition simulated by a three-dimensional (3-D) or a horizontal clinostat on the activity of auxin polar transport in inflorescence axis of Arabidopsis thaliana.

Arabidopsis↗
PubMed1995

Relationship between axonal regeneration and vascularity in tubulation--an experimental study in rats.

This study investigated the effect of vascularity in a nerve conduit on peripheral nerve regeneration. The effect of three different types of tube (empty, blood vessel-containing and ligated vessel-containing) was compared using a rat sciatic nerve preparation with a 10-mm gap. Nerve regeneration through the vessel-containing tube was more efficient than in the other tubes 6 and 12 weeks after tubulation surgery, but there were no statistically significant differences among the three types of tube after 24 weeks. Electrophysiological, histological and microangiographic studies showed that vessels which were preinserted in the nerve conduit accelerated axonal regeneration through rapid capillary formation in the tube.

Animals↗
PubMed1995

[Clinical effects and immunological analysis of intraabdominal and intrapleural injection of lentinan for malignant ascites and pleural effusion of gastric carcinoma].

Twenty-one patients with malignant peritoneal or pleural effusions of gastric carcinomas were treated with intracavitary injection of lentinan (LNT). LNT was injected at a dosage of 4 mg/week for 4 weeks. In total, fifteen (71%) of twenty-one patients demonstrated clinical responses. Toxicity caused a high fever in only one case. LAK and ATK activities induced from peritoneal exudate cells (PEC) after culture with autologous tumor and interleukin-2 were examined before and after LNT injection. ATK activity was augmented, but LAK activity was reduced after LNT injection. These results indicate that intracavitary injection of LNT is a useful treatment for malignant effusions, and that LNT augments the induction of cytotoxic T-lymphocytes.

Antineoplastic Agents, Phytogenic↗
PubMed1995

[A case of multiple liver metastasis from ileac carcinoid effectively treated with continuous intraarterial infusion of somatostatin analog].

We report a case of multiple liver metastasis from ileac carcinoid treated with continuous intraarterial infusion of somatostatin analog. A 65-year-old man who complained of chest pain was admitted to Yamaguchi University Hospital School of Medicine for further examination of cardiac angina. Liver tumors, which were detected during ECHO cardiogram examination, were diagnosed as metastasis from carcinoid by percutaneous transhepatic liver biopsy. Primary tumor was found at the ileum by colonofiberscopy. We performed ileo-cecal resection and catheterization from the gastroduodenal artery for intraarterial chemotherapy under laparotomy. After the operation, the patient was treated with continuous intraarterial infusion of somatostatin analog (100 micrograms/day, 5 days/week for 16 weeks). The tumor in segment 6 (S6) disappeared, but the tumor in S2 enlarged after the therapy. Hepatic angiography confirming the drug distribution demonstrated the occlusion of the left hepatic artery. This drug was thus distributed to the tumor in S6 but not in S2. These results suggest that somatostatin analog may have a direct anti-tumor effect. Furthermore, no side effect was observed. Thus, intraarterial infusion of somatostatin analog may be a useful therapy for liver metastasis from carcinoid.

Aged↗
PubMed1995

Biodegradable plate fixation of rabbit femoral shaft osteotomies. A comparative study.

Femoral shaft transverse osteotomies in 58 rabbits were fixed with ultrahigh strength poly-L-lactic acid plates made by a drawing technique. Similar osteotomies in another 35 rabbits were fixed using stainless steel plates. The union rate, the mechanical strength of the united bones, bone mineral content and density in the area beneath the plate using dual energy x-ray absorptiometry, and the cortical thickness beneath and opposite the plate using a digitizer was compared between the poly-L-lactic acid and stainless steel groups after postoperative periods of 8, 25, and 40 weeks. The poly-L-lactic acid and stainless steel groups showed union rates of 67% (39 of 58) and 80% (28 of 35) without displacement, respectively. In the poly-L-lactic acid group, plate failure occurred in 14% (8 of 58). The mechanical strength of the specimen was restored to a level equal to that on the untreated side by 25 weeks, and cortical thickness and bone mineral content and density were maintained almost normal for 40 weeks in the poly-L-lactic acid group. The stainless steel group showed significantly lower mechanical strength and led to osteopenia because of stress shielding after 25 weeks.

Animals↗