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S Ohta

Publications and source records attributed to S Ohta.

At least 523 records · Page 29Linked to original sources
PubMed1993

Protein-tyrosine kinase p72syk is activated by thrombin and is negatively regulated through Ca2+ mobilization in platelets.

Activation of platelets by thrombin results in a dramatic increase in tyrosine phosphorylation on multiple cellular proteins (Ferrell, J. E., and Martin, G. S. (1988) Mol. Cell. Biol. 8, 3603-3610; Golden, A., and Brugge, J. S. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 901-905; Nakamura, S., and Yamamura, H. (1989) J. Biol. Chem. 264, 7089-7091). However, none of the responsible protein-tyrosine kinase has been reported so far. We report here that p72syk, one of the non-receptor-type protein-tyrosine kinases, is activated following thrombin stimulation in blood platelets. Washed porcine platelets were stimulated by thrombin, and the activation of p72syk was assessed in an immunoprecipitation kinase assay. The activity of p72syk increased within 5 s, reached a maximum at 10 s, and decreased to a basal level within 60 s after 0.5 unit/ml thrombin stimulation. The amount of immunoprecipitated p72syk was not altered throughout the time course. This activation was greatly enhanced in a dose-dependent manner and was completely canceled by the pretreatment of platelet suspension with hirudin, a specific antagonist of thrombin. In the Ca(2+)-depleted condition both extra- and intracellularly, the activation of p72syk was still persistent; in contrast, the deactivation process was completely abrogated even at 120 s after thrombin stimulation. In addition, the replenishment of Ca2+ resulted in a similar deactivation pattern as seen in the Ca(2+)-rich condition. Furthermore, this deactivation was also canceled by the pretreatment of platelets with W7, a calmodulin antagonist, as well as ML9, a myosin-light-chain kinase inhibitor. These results indicate that p72syk can be a responsible enzyme to the protein-tyrosine phosphorylation events following the platelet activation by thrombin and may be negatively regulated by Ca2+ in a calmodulin-dependent manner, inter alia myosin light-chain kinase, in thrombin-stimulated platelets.

Animals↗
PubMed1993

Selective release of serotonin by endogenous alkaloids, 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines, (R)- and (S)salsolinol, in the rat striatum; in vivo microdialysis study.

Dopamine-derived 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines, (R)- and (S)salsolinol, released an enormous amount of serotonin in the rat striatum; the concentration of serotonin increased from undetectable level to 2.53 +/- 0.12 and 3.69 +/- 0.01 microM after perfusion of (R)- and (S)salsolinol, respectively. Salsolinols increased extracellular dopamine level, but to a much lesser degree than serotonin. Other naturally occurring isoquinolines with catechol structure released serotonin and dopamine, but salsolinols were the most potent and selective releaser of serotonin. Serotonin release by salsolinols may be involved in some psychiatric symptoms in L-DOPA therapy or alcoholism.

Alkaloids↗
PubMed1993

Inherited amyloid polyneuropathy type IV (gelsolin variant) in a Japanese family.

We describe a Japanese family with familial amyloid polyneuropathy type IV. The family originates from central Japan, Nagano prefecture, and is unrelated to Finnish or other Caucasian populations. Of 42 members in three generations, 14 individuals (5 men, 9 women) are affected by corneal lattice dystrophy, cranial neuropathy, mild peripheral neuropathy, and skin changes. Polarizing microscopy and immunohistochemistry studies of skin biopsy samples demonstrated abundant amyloid deposits, which bound an antigelsolin monoclonal antibody. Direct sequence analysis of a DNA fragment spanning codon 187 of plasma gelsolin complementary DNA and restriction analysis using a modified polymerase chain reaction demonstrated a single base substitution, guanine to adenine, at nucleotide position 654, which is identical to the mutation in Finnish familial amyloid polyneuropathy type IV. This strongly suggests that the mutation causes the familial amyloid polyneuropathy type IV phenotype regardless of ethnic background.

Adult↗
PubMed1993

Close phylogenetic relationship between Vestimentifera (tube worms) and Annelida revealed by the amino acid sequence of elongation factor-1 alpha.

To clarify the phylogenetic position of Vestimentifera (tube worms), 346-bp fragments of the elongation factor-1 alpha (EF-1 alpha) gene (939-1286 according to the numbering of the human gene) of a vestimentiferan, Lamellibrachia sp., a sternaspid polychaete, Sternaspis scutata, an earthworm, Pheretima sp., and a gastropod, Alviniconcha hessleri, were sequenced. From the amino acid sequences of these EF-1 alpha, and those of two other vertebrates and two arthropods, phylogenetic relationships were deduced by the maximum likelihood (ML) method, by which the phylogenetic tree can be inferred without assuming constancy of the molecular evolutionary rate. For the ML tree and all of seven alternative trees, whose log-likelihoods could not be discriminated from that of the ML tree by the criterion of the standard error, the vestimentiferan, the polychaete, and the oligochaete formed a clade, excluding the arthropods and the gastropod as outgroups. This result is convincing evidence that Vestimentifera are protostomes that are closely related to Annelida. The ML tree suggests that Vestimentifera are more closely related to Polychaeta than to Oligochaeta, though the data were not sufficient to discriminate these three groups at a significant level. From recent evidence such as morphological characteristics and molecular information, it may safely be said that vestimentiferans should be included in the Annelida provided this phylum contains polychaetes and oligochaetes.

Amino Acid Sequence↗
PubMed1993

Recovery of protein synthesis in tolerance-induced hippocampal CA1 neurons after transient forebrain ischemia.

Protein synthesis at various recirculation times after 5-min transient forebrain ischemia was evaluated in gerbil hippocampal CA1 pyramidal neurons that had acquired tolerance to delayed-type ischemic injury. Evaluation was performed by observing polyribosomes under electron microscopy, and by [14C]leucine autoradiography. Hippocampal CA1 pyramidal neurons in the gerbils acquired stable and reproducible tolerance to delayed-type ischemic injury subsequent to a 5-min ischemia by pretreatment that consisted of loading two 2-min ischemic periods at a 1-day interval, followed by 48 h of recirculation. During the early phase following the 5-min ischemia, polyribosomal disaggregation, loss of dendritic microtubules, and significant suppression of radiolabeled leucine incorporation were observed in the tolerance-induced CA1 neurons as well as in the non-tolerance-induced neurons. While these findings persisted in the non-tolerance-induced neurons throughout the duration of the experiment, most of the tolerance-induced neurons demonstrated reaggregation of cytosomal ribosomes, increase in the number of dendritic microtubules, and restoration of impaired amino acid incorporation 24 h after the ischemia. These findings suggest that recovery of protein synthesis during the early post ischemic phase is essential for CA1 neuron survival after ischemic injury.

Amino Acids↗
PubMed1993

Antitumor effects of a novel monoclonal antibody with high binding affinity to ganglioside GD3.

Ganglioside GD3, which is one of the major gangliosides expressed on the cell surface human tumors of neuroectodermal origin, has been studied as a target molecule for passive immunotherapy. We established ten kinds of anti-GD3 monoclonal antibodies (mAb) of the mouse IgG3 subclass by immunization with purified GD3 and melanoma cells. One of the established mAb, KM641, showed major reactivity with GD3 and minor reactivity with GQ1b out of 11 common gangliosides in an enzyme-linked immunosorbent assay. Immunostaining of gangliosides, separated on thin-layer chromatography plates, using KM641 revealed that most of the melanoma cell lines contained immunoreactive GD3 and GD3-lactone at a high level, but only the adrenal gland and the urinary bladder out of 21 human normal tissues had immunoreactive GD3. In immunofluorescence, KM641 bound to a variety of living tumor cell lines especially melanoma cells, including some cell lines to which another anti-GD3 mAb R24, established previously, failed to bind. High-affinity binding of KM641 to a tumor cell line was quantified by Scatchard analysis (Kd = 1.9 x 10(-8) M). KM641 exerted tumor-killing activity in the presence of effector cells or complement against melanoma cells expressing GD3 at a high level. Not only natural killer cells but also polymorphonuclear cells were effective as the effector cells in antibody-dependent cellular cytotoxicity. Intravenous injection of KM641 markedly suppressed the tumor growth of a slightly positive cell line, C24.22 (7.2 x 10(5) binding sites/cell), as well as a very GD3-positive cell line, G361 (1.9 x 10(7) binding sites/cell), inoculated intradermally in nude mice. KM641, characterized by a high binding affinity for GD3, has the potential to be a useful agent for passive immunotherapy of human cancer.

Animals↗
PubMed1993

A mouse/human chimeric anti-(ganglioside GD3) antibody with enhanced antitumor activities.

Ganglioside GD3, which is one of the major gangliosides expressed on the cell surface of human tumors of neuroectodermal origin has been focused on as a target molecule for passive immunotherapy. We have cloned the cDNA encoding the immunoglobulin light and heavy chains of an anti-GD3 monoclonal antibody KM641 (murine IgG3, kappa), and constructed the chimeric genes by linking the cDNA fragments of the murine light and heavy variable regions to cDNA fragments of the human kappa and gamma 1 constant regions, respectively. The transfer of these cDNA constructs into SP2/0 mouse myeloma cells resulted in the production of the chimeric antibody, designated KM871, that retained specific binding activity to GD3. Indirect immunofluorescence revealed the same staining pattern for chimeric KM871 and the mouse counterpart KM641 on GD3-expressing melanoma cells. When human serum and human peripheral blood mononuclear cells were used as effectors in complement-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity respectively, the chimeric KM871 was more effective in killing GD3-expressing tumor cells than was the mouse counterpart KM641. Intravenous injection of chimeric KM871 markedly suppressed tumor growth in nude mice. The chimeric KM871, having enhanced antitumor activities and less immunogenicity than the mouse counterpart, would be a useful agent for passive immunotherapy of human cancer.

Amino Acid Sequence↗
PubMed1993

Effect of 4-phenyl-1,2,3,4-tetrahydroisoquinoline on ambulation induced by injection of methamphetamine into the nucleus accumbens in rats.

4-Phenyl-1,2,3,4-tetrahydroisoquinoline (4-PTIQ) has previously been shown to have antagonistic properties to methamphetamine in the spinal cord. Administration of 4-PTIQ (5 mg/kg, s.c.) reduced the ambulation induced by methamphetamine (0.5 mg/kg, s.c.) in rats. Methamphetamine (3 micrograms), injected unilaterally into the nucleus accumbens, increased ambulation. Alone, 4-PTIQ (10 micrograms) failed to elicit ambulation; however, it inhibited the methamphetamine-induced increase in ambulation. The alpha 1-antagonist prazosin (0.5 micrograms) or the beta-antagonist propranolol (3 micrograms) showed no effect on ambulation induced by methamphetamine. Haloperidol (5 ng), which possesses strong dopamine-blocking activity, abolished the ambulation induced by methamphetamine. The drug 4-PTIQ had weak affinity for dopamine D1 and D2 receptors. These results support the possibility that the inhibitory effects of 4-PTIQ on the ambulation-stimulating effects of methamphetamine, are due to blocking of the dopamine-releasing effect of methamphetamine but not due to dopamine blocking effects.

Animals↗
PubMed1993

Inhibitory effect of 4-phenyltetrahydroisoquinoline on locomotion and dopamine release induced by micro-injection of methamphetamine into the nucleus accumbens of the rat.

The inhibitory effects of 4-phenyl-1,2,3,4-tetrahydroisoquinoline (4-PTIQ) on methamphetamine-induced increases in dopamine and locomotion were investigated. Methamphetamine hydrochloride (10 micrograms) microinjected into the nucleus accumbens increased both locomotor activity and extracellular dopamine levels, measured by the brain microdialysis method. 4-PTIQ hydrochloride (20 micrograms) co-injected with methamphetamine inhibited both the increase in dopamine and the locomotor activity. The uptake blocker cocaine hydrochloride (20 micrograms) co-injected with methamphetamine failed to inhibit the effect of methamphetamine. Thus 4-PTIQ but not cocaine inhibited the dopamine-releasing effect of methamphetamine, and 4-PTIQ is suggested to block methamphetamine-induced locomotion by inhibition of dopamine release.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Purification of hemagglutinin from Haemophilus paragallinarum using monoclonal antibody.

The purification of hemagglutinin from Haemophilus paragallinarum was attempted using affinity chromatography with monoclonal antibody. The antigen eluted from the affinity column using potassium thiocyanate buffer agglutinated chicken erythrocytes. In immunoblotting of the eluted antigen, a single band with monoclonal antibody was found as well as the crude antigen. When the chickens were immunized with the eluted antigen, they produced the hemagglutination inhibition (HI) antibody, and they showed protection against challenged exposure with H. paragallinarum strain 221. These results indicated that the HA antigen of H. paragallinarum was a protective antigen.

Animals↗
PubMed1993

Characterisation of a vindesine-resistant human small-cell lung cancer cell line.

We established a vindesine-resistant (x 11.6) human small-cell lung cancer cell line (H69/VDS) by stepwise exposure of parent line H69 to vindesine. H69/VDS showed cross-resistance to taxol (x 10.1), vincristine (x 6.9) and colchicine (x 3.4) but not to doxorubicin, cisplatin or etoposide. There was no significant difference in intracellular [3H]-vincristine and doxorubicin accumulation between H69 and H69/VDS cells. The human mdr1 mRNA was not detected in either of the cell lines. These results indicated that H69/VDS did not express a typical multidrug resistant phenotype. Addition of 20 microM verapamil enhanced the growth inhibitory effect of vindesine on both H69/VDS (x 12.0) and H69 cells (x 3.8). The amount of total tubulin in H69/VDS cells was lower than that in the H69 parental cells. No significant increase was observed in the amount of total and polymerised tubulins of H69 cells. In H69/VDS cells, however, verapamil increased the amount of total tubulin to the level of parental cells, but decreased the amount of polymerised tubulin. Modulation of tubulin may play a role in the resistance to vindesine.

Antineoplastic Agents↗
PubMed1993

Role of protein kinase C in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage.

This study investigated the role of protein kinase C (PKC) in the pathogenesis of vasospasm after experimental subarachnoid hemorrhage (SAH). PKC activation by intracisternal injection of a phorbol ester [12-O-tetradecanoylphorbol-13-acetate (TP)] induced dose-dependent, slowly developing, severe contraction of the basilar artery. A single intracisternal injection of TP (5 x 10(-9) M in the CSF) induced sustained contraction lasting over 3 days, which almost paralleled the changes of membrane-bound PKC activity in the basilar arterial wall. In a two-hemorrhage SAH model, membrane-bound PKC activity in the basilar artery increased up to day 4 and returned to the control level by day 14, whereas angiographic contraction reached a maximum on day 7 and still persisted at a moderate level on day 14. Thus, there was a discrepancy between arterial PKC activity and arterial contraction. Multiple intracisternal injections of TP produced 30-40% sustained contraction of the basilar artery lasting for more than 10 days along with sustained activation of PKC to levels compatible with that observed in the SAH model. However, TP injection caused considerably milder histological changes in the basilar artery than those noted in the SAH model. We concluded that cerebral vasospasm after SAH cannot be explained solely on the basis of activation of the PKC pathway.

Animals↗
PubMed1993

The gene for Machado-Joseph disease maps to human chromosome 14q.

Machado-Joseph disease (MJD) is an autosomal dominant, multisystem neurodegenerative disorder involving predominantly cerebellar, pyramidal, extrapyramidal, motor neuron and oculomotor systems. Although it was first reported in families of Portuguese-Azorean descent, MJD has also been described in non-Azorean families from various countries, being one of the most common hereditary spinocerebellar degenerations. With the use of highly polymorphic microsatellite DNA polymorphisms, we have assigned the gene for MJD to the long arm of chromosome 14 (14q24.3-q32) by genetic linkage to microsatellite loci D14S55 and D14S48 (multipoint lod score Zmax = 9.719).

Chromosome Mapping↗
PubMed1993

The gluteal perforator-based flap for repair of sacral pressure sores.

A gluteal perforator-based flap employing the gluteus maximus muscle perforators located around the sacrum is described. A cadaveric study disclosed the existence of several significant perforators all around the gluteal region. Among these, the parasacral perforators originating from the internal pudendal artery and lateral sacral artery have proven useful for the repair of sacral pressure sores. A total of eight decubitus in seven patients were treated with gluteal perforator-based flaps. There were no postoperative complications, such as flap necrosis and wound infection, with the exception of fistula formation in one case. This flap requires no transection or sacrifice of the gluteus maximus muscle, and elevation time for the flap is short. However, the perforators are located at various sites and thus require some careful dissection.

Adult↗
PubMed1993

The mechanism of the difference in cellular uptake of platinum derivatives in non-small cell lung cancer cell line (PC-14) and its cisplatin-resistant subline (PC-14/CDDP).

A cisplatin-resistant non-small cell lung cancer cell line, PC-14/CDDP, was established from PC-14 by stepwise escalation of CDDP concentrations in vitro. PC-14/CDDP cells were 11.4-fold more resistant to CDDP compared with PC-14 cells. This resistant cell line was cross-resistant to platinum analogues, such as carboplatin (CBDCA) (x 3.5), cis-diammine(glycolate-O,O')platinum(II) (254-S) (x 5.6) and cis-dichloro(ethylenediammine)platinum(II) (cis-DEP) (x 4.2). On the other hand, relative resistance value to ormaplatin was only 1.4-fold. To elucidate the mechanism(s) of CDDP resistance and of its circumvention by ormaplatin, we investigated the characteristics of this cell line. Total sulfhydryl content was slightly elevated in PC-14/CDDP cells compared with PC-14 cells. There was no significant difference in the DNA repair ability between the two cell lines. Cellular accumulations of CDDP, CBDCA, 254-S, and cis-DEP in PC-14/CDDP cells were markedly decreased to 23%, 27%, 29%, and 32% of those in PC-14 cells, respectively. However, the accumulation of ormaplatin in PC-14/CDDP was almost the same as that in PC-14. To elucidate the mechanisms of uptake of these platinum analogs in the cells, we studied the effects of ouabain, an Na+,K(+)-ATPase inhibitor, on cellular drug uptake in both cell lines. Preincubation with 300 nM ouabain for 1 h inhibited approximately 60% of CDDP accumulation in PC-14. However ouabain preincubation at any concentration up to 300 nM did not affect CDDP accumulation in PC-14/CDDP. The accumulation of ormaplatin was not inhibited by ouabain in either of the cell lines. These data suggest that the mechanism of the uptake of ormaplatin is different from that of CDDP, and that ormaplatin exerts a cytotoxic effect in CDDP-resistant cells which have defective cisplatin accumulation.

Antineoplastic Agents↗
PubMed1993

[Case report: suppurative arthritis due to group B Streptococcus in a patient with rheumatoid arthritis].

A 62-year-old woman, who had been diagnosed as having rheumatoid arthritis (RA) with systemic amyloidosis and diabetes mellitus, was admitted to our hospital because of polyarthralgia on October 1, 1987. She had some subcutaneous nodules and rheumatic pleural effusion. Therefore she was treated with 20 milligrams of prednisolone (PSL) daily. On the ninth day after the beginning of steroid therapy, she complained of severe pain and a new swelling in her right knee joint. The knee joint aspirate on arthrocentesis yielded a pure growth of group B Streptococcus (GBS). Blood culture was also positive for GBS. Her suppurative arthritis gradually improved by treatment with penicillin G. However, after the discontinuance of PSL, her pleural effusion deteriorated and she died on January 10, 1988. To our knowledge, there have been no prior reports of group B streptococcal suppurative arthritis complicating RA in Japan.

Arthritis, Infectious↗
PubMed1993

[A case of vivax malaria in which remission was achieved by primaquine at 1.5 times the standard dose after two earlier relapses].

A 22-year-old male student, who had been to Indonesia, was admitted to our hospital because of a high grade fever on October 12, 1990. On admission, vivax malaria parasites were detected in his blood smears and the antibody titers against Plasmodium vivax and P. falciparum antigen were respectively 1:1024 and 1:64 by the indirect fluorescent antibody test. Therefore, he was diagnosed as having vivax malaria and was treated with sulfadoxine/pyrimethamine (Fansidar), followed by primaquine at 15 mg/day for 14 days. However, relapse occurred twice after treatment with the above-mentioned standard dose of primaquine. After his second relapse, he was treated with primaquine at 22.5 mg/day for 14 days and remission was finally achieved without any adverse reactions. The antibody titer against P. vivax did not re-increase during the first and second relapses.

Adult↗