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Biomedical subjects

S Nakashima

Publications and source records attributed to S Nakashima.

At least 217 records · Page 12Linked to original sources
PubMed1991

Antigen-induced biphasic diacylglycerol formation in RBL-2H3 cells: the late sustained phase due to phosphatidylcholine hydrolysis is dependent on protein kinase C.

Exposure to antigen (Ag) caused a biphasic 1,2-diacylglycerol (DG) production in [3H]myristic acid-labeled RBL-2H3 cells; the early, small transient phase and the second large sustained phase. The accumulation of phosphatidic acid (PA) or phosphatidylethanol (PEt) in the presence of ethanol was paralleled by the second-phase DG generation. Ag-induced formation of phosphocholine and choline in [3H]choline-labeled cells suggested the hydrolysis of phosphatidylcholine (PC) by phospholipases C and D. Treatment with phorbol myristate (PMA) or A23187 caused increases in [3H]DG and water-soluble [3H]choline metabolites. In protein kinase C (PKC) down-regulated cells, PEt formation was markedly reduced. In these cells DG production induced by Ag and A23187 was largely suppressed, thus indicating that PKC would play an important regulatory role for PC hydrolysis. However, because the A23187 treatment showed significant accumulation of water-soluble choline metabolites in PKC down-regulated cells, an increase in intracellular Ca2+ is another factor regulating PC hydrolysis. Taken together, these results may indicate that PC hydrolysis in response to Ag is dependent on PKC and Ca2+.

Animals↗
PubMed1991

Thrombin induces a biphasic 1,2-diacylglycerol production in human platelets.

The 1,2-diacylglycerol (DAG) mass content was measured in thrombin-stimulated human platelets. Thrombin stimulates a biphasic accumulation of DAG, with an early phase reaching a peak at 10 s and a later phase reaching a peak at 2-3 min. The time course of first-phase DAG production corresponded well to that of Ins(1,4,5)P3 formation, which was rapid and transient. The second phase of DAG accumulation occurred after the level of Ins(1,4,5)P3 returned to nearly basal. Thrombin stimulated the decrease in PtdIns and phosphatidylcholine contents. The source of second-phase DAG was examined in platelets prelabelled with three radioactive fatty acids, i.e. arachidonic, palmitic and myristic. Thrombin stimulated the increase in radioactivity of DAG with decline of PtdIns in platelets labelled with [3H]arachidonic acid or [3H]palmitic acid, in which PtdIns was considerably labelled. In contrast, significant accumulation of [3H]DAG was not observed in [3H]myristic acid-labelled platelets, in which PtdIns was poorly labelled. In platelets prelabelled with [3H]inositol, an increase in InsP in response to thrombin was seen for more than 5 min. In contrast, upon stimulation, significant increases in [3H]phosphocholine and [3H]choline were not observed in [methyl-3H]choline-labelled platelets. Thrombin induced a small production of phosphatidylethanol, when ethanol was present during stimulation. However, the formation of DAG and phosphatidic acid was not significantly affected by ethanol. These results suggest that thrombin stimulates a biphasic accumulation of DAG, initially from PtdInsP2 and later from PtdIns in human platelets.

Arachidonic Acid↗
PubMed1991

Effect of a novel antiallergic drug, pemirolast, on activation of rat peritoneal mast cells: inhibition of exocytotic response and membrane phospholipid turnover.

The effects of a potent antiallergic drug, pemirolast (TBX), on activation of signal-transducing phospholipase C and A2, were examined in rat peritoneal mast cells. TBX at concentrations between 10(-7) and 10(-5) g/ml effectively inhibited degranulation in response to both antigen and compound 48/80. At the same concentrations the drug markedly suppressed the formation of 1,2-diacylglycerol and phosphatidic acid, and the decrease in phosphatidylinositol, suggesting the prevention of phospholipase C activation. The blockade of phospholipase A2 was suggested by the decrease in agonists-induced arachidonic acid liberation. These results indicate that TBX may exert its inhibitory effects on mast cells, at least in part, by preventing the activation of signal-transducing phospholipases.

Animals↗
PubMed1991

Thrombin-induced breakdown of phosphoinositides in platelets from patients with NIDDM.

We have examined thrombin-induced metabolism of phosphoinositides in the platelets from fifteen NIDDM (non-insulin-dependent diabetes mellitus) patients and fifteen healthy subjects (control). The diabetic patients were divided into two groups. One group (group I) had diabetic retinopathy (microangiopathy) and the other group (group II) had atherosclerosis of great vessels (macroangiopathy). In platelets incubated with [32P] orthophosphate for 80 min, the incorporation of 32P radioactivity into phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2) was significantly lower in the group II than in the control. The addition of thrombin induced a marked decrease in PIP2 radioactivity at 10 sec in platelets from group I compared with that from the control. These results suggest that the breakdown of polyphosphoinositides is increased in platelets from diabetic subjects with retinopathy, and also that the formation of polyphosphoinositides is decreased in the platelets from diabetic subjects with macroangiopathy.

Adult↗
PubMed1991

[The cytotoxic mechanism of tumor necrosis factor (TNF) in human osteosarcoma cell line TE85--(1). Implication of phospholipase A2 activity in cytotoxicity].

The cytotoxic mechanism of recombinant human tumor necrosis factor (TNF) in human osteosarcoma cells (TE85) was studied from the point of view of phospholipid metabolism. The TNF-induced cytotoxicity, determined by using the dye uptake method, was dose-dependent in the range of 100-10,000 U/ml. Phospholipid metabolism was analyzed in the cells labelled with [3H] arachidonic acid or [3H] glycerol. TNF stimulated the release of arachidonic acid and its metabolites from the cells in a dose-dependent manner. After TNF stimulation, the level of phosphatidylcholine (PC) decreased. Concomitantly, phospholipase A2 (PLA2) hydrolyzed PC producing a transiently increased level of lysophosphatidylcholine. ONO-RS-082, a potent PLA2 inhibitor, reduced the TNF-induced cytotoxicity and the release of arachidonic acid. These observations suggest that PLA2 may play a role in the cytotoxic effect of TNF on human osteosarcoma cells.

Cell Survival↗
PubMed1991

[Growth of the aortic anastomosis in puppies--comparison of monofilament suture materials, whether absorbable or nonabsorbable, and of suture techniques, whether continuous or interrupted].

This study compared the growth of vascular anastomoses performed with either polypropylene or polydioxanone sutures and with either continuous running suture or interrupted suture technique. Primary end-to-end anastomoses of the infrarenal aorta were performed in 38 puppies. Nineteen were performed with 5-0 polypropylene sutures; in ten all sutures were placed in continuous fashion, and in nine in interrupted fashion. The other nineteen were performed with 5-0 polydioxanone sutures; in ten the sutures were placed in continuous fashion, and in nine in interrupted fashion. The animals were subjected to the repeated aortograms at 2, 4, 8 weeks, 6 months and 1 year following operation. Each abdominal aorta was subjected to burst test, and pathological examination. All anastomoses were patent and tolerated burst-test (300 mmHg). Neither aneurysm nor dilatation of anastomotic site was observed. Anastomotic area was significantly smaller and more stenotic in the continuous polypropylene suture group than in other three groups at 8 weeks, 6 months and 1 year following operation. There was no significant difference among these three groups. No suture materials were observed in the polydioxanone suture groups after 6 months following operation. This study suggests that polydioxanone suture will be useful for the repair of cardiovascular anomalies where growth of the suture line is required.

Absorption↗
PubMed1991

Genistein, a protein tyrosine kinase inhibitor, inhibits thromboxane A2-mediated human platelet responses.

An isoflavone compound, genistein, which is known as a protein tyrosine kinase inhibitor, concentration-dependently (0.1-30 micrograms/ml) suppressed human platelet aggregation, serotonin secretion, and protein tyrosine phosphorylation induced by collagen or stable thromboxane A2 analogs [U46619 and 9,11-epithio-11,12-methano-thromboxane A2 (STA2)]. However, genistein did not inhibit these thrombin (0.1 unit/ml)-induced platelet responses. Although thrombin induced an increase in the platelet phosphotyrosine content, genistein at 100 micrograms/ml only slightly attenuated thrombin-induced protein tyrosine phosphorylation. Genistein competitively inhibited [3H]U46619 binding to washed platelets, in a concentration-dependent fashion. Daidzein (another isoflavone compound), which does not have a hydroxyl group at the 5-position of genistein and lacks inhibitory activity for protein tyrosine kinase, was found to suppress [3H]U46619 binding, leading to the inhibition of collagen- or STA2-induced platelet responses. These results indicate that the blockage by genistein of platelet responses induced by collagen or thromboxane A2 is due to its preventive action on thromboxane A2 binding to the receptor, rather than via inhibition of protein tyrosine phosphorylation, and that the drug does not appear to be a particularly good inhibitor of tyrosine phosphorylation in intact platelets.

Anti-Bacterial Agents↗
PubMed1990

A case of bulbospinal muscular atrophy with chief complaint of sensory disorder in the lower extremities.

A 56-year-old man was admitted to our department with a chief complaint of lower extremity dysesthesia. He described a dull numbness below the ankle and a dull pain in the nates for the past two years. Although the numbness extended to the thigh, he did not notice any muscular weakness or atrophy. Neurological examination revealed weakness and atrophy in the face, tongue and the proximal portions of all four extremities. Deep tendon reflexes were decreased. A moderate loss of vibratory sensation was noted below the knees. Electromyography showed neurogenic changes. Muscle biopsy revealed both myogenic and neurogenic changes. Sural nerve biopsy revealed a mild reduction of myelinated fibers, particularly the large-diameter fibers. Based on these findings, a diagnosis of bulbospinal muscular atrophy (BSMA) was made. In recent years, there have been some case reports of BSMA with sensory disturbances, or merely with subclinical manifestations of a sensory disturbance. This case is included in the same category as those reports, but it is interesting to note that the sensory disturbance in the lower extremities occurred as the chief complaint of the disease.

Humans↗
PubMed1990

[Serological evaluation of human T lymphotropic virus type-I infection in routine hospital samples, especially using serodia.HTLV-I].

Particle agglutination (PA; Serodia-ATLA) and ELISA (Ei-test ATL) assays have been used as routine anti-HTLV-I antibody detection in Japan. However, inconsistent results were obtained by the above methods. We wished to develop criteria for serological confirmation of HTLV-I infection in Hospital samples. Sera obtained in our Hospital from October, 1988 to September, 1989 were tested by five methods of PA (Serodia-ATLA), new PA (improved on the PA; Serodia.HTLV-I), ELISA-I (coated by HTLV-I infected cell lysates as antigens; Ei-test ATL), ELISA-II (coated by recombinant gag-env hybrid proteins as antigens) and IF. The HTLV-I seropositive rates using five methods were not different, ranged from 29.7 to 32.3% in 155 sera. However, PA assays appeared more false positive and rare false negative in some high titer sera. 13 sera as demonstrated negative for ELISA-I and positive for PA (ELISA-I(-)/PA(+] were reevaluated. As results, the antibody were confirmed in only 3 by new PA, 1 by ELISA-II and 2 cases by IF, respectively. On the other hand, 2 by new PA, 4 by ELISA-II and 2 by IF in 18 sera with ELISA-I(+)/PA(-) were interpreted as positive. Therefore, new PA is a remarkable improvement on the PA current model.

Agglutination Tests↗
PubMed1990

[An experimental study of reconstruction--differences of the healing process by materials].

The healing processes of carinal reconstruction by suture materials; absorbable suture (Vicryl) and nonabsorbable suture (Prolene) were compared. 67 adult mongrel dogs underwent resection of two rings of the trachea and bilateral main bronchi. This was followed by end-to-end anastomosis of the reconstructed carina and the remaining trachea. 3-0 Vicryl or 3-0 Prolene were used respectively. At some intervals, each anastomosis was removed and was analyzed by bronchoscopy, microangiography, scanning electron microscopy (SEM) and light microscopy. Suture insufficiency occurred in two of 32 anastomosis sutured by Vicryl and four of 35 anastomosis sutured by Prolene sutures. Stenosis developed in one of the Vicryl group and two of the Prolene group. Vicryl showed more inflammation than Prolene for 3 weeks after surgery. In four weeks, the inflammation subsided. Anastomoses were of the same degree in both groups. In microangiography, vascular regeneration was abundant by 3 weeks, which normalized in 4 weeks showing a normal network in both groups. Normalization of the vascular network appeared the earliest at the membranous portion. Scanning electron microscopy showed no difference in the reconstruction of the cilia over the anastomosis area in the both groups. This term was 2 months. The order of reconstruction revealed by SEM was the same as observed by microangiography. But in the Prolene group, it took more than 3 months for the suture material to be completely covered with the epithelium. In light microscopy, inflammation was stronger in the group than by in the Prolene groups, and it continued for 4 weeks suture material could not be found in the anastomosis area with bronchoscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Inhibitory action of cyclic AMP on inositol 1,4,5-trisphosphate-induced Ca2+ release in saponin-permeabilized platelets.

Ca2+ release triggered by inositol 1,4,5-trisphosphate (IP3) has been measured in saponin-permeabilized human platelets with quin2 or 45Ca2+. Ca2+ was sequestered by intracellular organelles in the presence of ATP, and IP3 released half of the sequestered Ca2+. The addition of cyclic AMP (cAMP) to permeabilized platelets transiently accelerated Ca2+ sequestration, but did not alter the steady-state level. In contrast, IP3-induced Ca2+ release was greatly inhibited by cAMP. Phorbol myristate acetate, an activator of protein kinase C did not affect IP3-induced Ca2+ release. These results indicate that cAMP may be involved in the regulation of IP3-induced Ca2+ release in human platelets.

Blood Platelets↗
PubMed1989

Mechanism of arachidonic acid liberation in platelet-activating factor-stimulated human polymorphonuclear neutrophils.

Upon stimulation of human polymorphonuclear neutrophils with platelet-activating factor (PAF), arachidonic acid (AA) is released from membrane phospholipids. The mechanism for AA liberation, a key step in the synthesis of biologically active eicosanoids, was investigated. PAF was found to elicit an increase in the cytoplasmic level of free Ca2+ as monitored by fluorescent indicator fura 2. When [3H] AA-labeled neutrophils were exposed to PAF, the enhanced release of AA was observed with a concomitant decrease of radioactivity in phosphatidylinositol and phosphatidylcholine fractions. The inhibitors of phospholipase A2, mepacrine and 2-(p-amylcinnamoyl)-amino-4-chlorobenzoic acid, effectively suppressed the liberation of [3H]AA from phospholipids, indicating that liberation of AA is mainly catalyzed by the action of phospholipase A2. The extracellular Ca2+ is not required for AA release. However, intracellular Ca2+ antagonists, TMB-8 and high dose of quin 2/AM drastically reduced the liberation of AA induced by PAF, indicating that Ca2+ is an essential factor for phospholipase A2 activation. PAF raised the fluorescence of fura 2 at concentrations as low as 8 pM which reached a maximal level about 8 nM, whereas more than nM order concentrations of PAF was required for the detectable release of [3H]AA. Pretreatment of neutrophils with pertussis toxin resulted in complete abolition of AA liberation in response to PAF. However, the fura 2 response to PAF was not effectively inhibited by toxin treatment. In human neutrophil homogenate and membrane preparations, guanosine 5'-O-(thiotriphosphate) stimulated AA release and potentiated the action of PAF. Guanosine 5'-O-(thiodiphosphate) inhibited the effects of guanosine 5'-O-(thiotriphosphate). These results suggest several points: 1) PAF stimulates human polymorphonuclear neutrophils to liberate AA mainly by the action of phospholipase A2; 2) Ca2+ mobilization alone is not sufficient to stimulate AA release, although Ca2+ is the important factor for phospholipase A2 activation; and 3) a pertussis toxin-sensitive GTP-binding protein may be implicated in activation of phospholipase A2.

Arachidonic Acid↗