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Biomedical subjects

T Horikoshi

Publications and source records attributed to T Horikoshi.

At least 109 records · Page 6Linked to original sources
PubMed1989

Regional distribution of metabotropic glutamate response in the rat brain using Xenopus oocytes.

The regional distribution of metabotropic L-glutamate responses was investigated in Xenopus oocytes injected with poly(A)+-RNA from a rat brain which was separated into 3 parts: cerebrum, cerebellum and brainstem. Under voltage-clamp, oscillatory current responses were induced more in cerebellum or brainstem poly (A)+-RNA-injected oocytes, and less in cerebrum poly(A)+-RNA-injected oocytes. These results suggest that the metabotropic glutamate receptor is distributed mostly in cerebellum and brainstem.

Animals↗
PubMed1989

Merkel cell carcinoma. A successful treatment with tumor necrosis factor.

A Merkel cell carcinoma of the mandibular area in a 78-year-old woman was treated successfully by direct intratumoral administration of recombinant human tumor necrosis factor. The patient received 2.5 x 10(5) U/d of recombinant human tumor necrosis factor every other day. A total of six injections (total dose, 1.5 x 10(6) U, 0.52 mg of protein) were administered over a period of 12 days. Soon after the therapy ended, the lesion softened and decreased in size. After 1 month, only erythema was visible. The lesion had completely disappeared clinically and histologically 5 months after the local injection of recombinant human tumor necrosis factor. Neither recurrence nor metastasis has been observed for at least 12 months following the treatment. Recombinant human tumor necrosis factor is suggested to be effective for the treatment of Merkel cell carcinoma.

Aged↗
PubMed1989

Purification and characterization of cell-associated glucosyltransferase synthesizing water-insoluble glucan from serotype c Streptococcus mutans.

Strains of Streptococcus mutans (serotypes c, e and f) were found to possess high levels of glucosyltransferase (GTase) activity, both cell-associated and in the culture medium, when grown in either sucrose-free or sucrose-containing broth media. The cell-associated GTase of S. mutans MT8148 (serotype c) was effectively extracted by treatment with 8 M-urea at 25 degrees C for 1 h. Approximately 95% of the GTase activity was solubilized by this treatment. The crude extract was purified by DEAE-Sephacel and hydroxylapatite column chromatography. For comparison, extracellular GTase was also purified from the culture supernatant of the same strain by ammonium sulphate precipitation, chromatofocusing and hydroxylapatite chromatography. The molecular masses of the cell-associated and extracellular GTase proteins were similar (156 kDa) as determined by SDS-PAGE. However, the pH optima for maximum GTase activity were different: pH 6.7 to 7.0 for the cell-associated enzyme and pH 5.5 to 6.5 for the extracellular enzyme. The product of cell-associated GTase from sucrose was almost exclusively water-insoluble glucan. On the other hand, extracellular GTase produced mainly water-soluble glucan from sucrose. This indicates that GTase synthesizing water-insoluble glucan is present primarily in a cell-associated form in serotype c S. mutans. Insoluble glucan synthesis by the cell-associated GTase from sucrose was not enhanced by addition of primer dextran T10 to the reaction mixture. The extracellular and cell-associated GTases were immunologically unrelated as determined by ELISA using monoclonal antibodies.

Chromatography↗
PubMed1989

Fine structural and immunohistochemical properties of dysplastic melanocytic nevi: comparison with malignant melanoma.

This study will review the clinical features of dysplastic melanocytic nevi (DMN) in Japanese cases, and then show the fine structure of melanosomes/melanogenesis in the dysplastic melanocytes and the immunohistochemical property of DMN as identified by monoclonal antibodies against human melanosome specific antigen (HMSA). The incidence of DMN is quite low in the Japanese. It is indicated that this fact may partly explain the low incidence of malignant melanoma in Japanese; in particular, low incidence in sun-exposed areas. The patients with DMN were largely males. They were different from ordinary Japanese in that they usually burn and tan poorly after sun exposure. In addition, the synthesis of melanosomes in the dysplastic melanocytes was found to be abnormal and characterized by a significant alteration in the fine structure of the melanosomal matrix and the pattern of melanization. These abnormal melanosomes reacted positively with MoAb HMSA-1 and HMSA-2, which identify the structural matrix protein of melanosomes unique to neoplastic melanocytes. Importantly, HMSA was present in both dysplastic melanocytes and melanoma cells, but not in epidermal melanocytes (nevus cells) of common melanocytic nevi.

Antigens, Neoplasm↗
PubMed1988

Production and characterization of monoclonal antibodies that bind to phosphatidylinositol 4,5-bisphosphate.

We established a series of monoclonal antibodies (MAbs) that bound to phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] which is confidently believed to play an important role in cellular signal transduction. We used complement dependent liposome lysis assay for screening MAbs and antibodies that bind to PI(4,5)P2 but not to phosphatidylinositol 4-monophosphate [PI(4)P] were selected. The reactivity of the MAbs was analyzed by complement dependent liposome lysis assay, enzyme-linked immunosorbent assay (ELISA) and inhibition of liposome lysis by soluble haptens. The MAbs exhibited three distinct reactivity profiles measured by three different assay systems and the results obtained from three typical MAbs designated AM-2, AM-7 and AM-212 are described. On liposome lysis assay, all three MAbs were highly specific with PI(4,5)P2 and no cross-reaction with other acidic phospholipids such as PI(4)P, phosphatidylinositol (PI), phosphatidic acid (PA), phosphatidylserine (PS), phosphatidylethanolamine (PE) and cardiolipin (CL) was observed. All three MAbs were able to react with as low as 0.1 mol% of PI(4,5)P2 embedded in the liposomal membrane. On ELISA, AM-2 and AM-212 bound only to PI(4,5)P2 and did not cross-react with other acidic phospholipids including PI(4)P. In contrast, AM-7 showed considerable binding to other phospholipids such as PI(4)P, PA and PE on ELISA. The reactivities of the MAbs with water soluble haptens such as inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] were examined by inhibition of liposome lysis. Among three clones examined, only AM-212 showed considerable reactivity with Ins(1,4,5)P3 while also showing weak cross-reactivity with fructose 1,6-diphosphate and inositol 1,4-bisphosphate. No cross-reaction with other structural analogs such as inositol 1-monophosphate and inositol 2-monophosphate was observed.

Animals↗
PubMed1988

Taurine and beta-alanine act on both GABA and glycine receptors in Xenopus oocyte injected with mouse brain messenger RNA.

The responding pathway (process from agonist binding to channel opening) of taurine and beta-alanine was investigated in Xenopus oocytes injected with mouse brain poly(A)+ RNA. Responses to gamma-aminobutyric acid (GABA), glycine, taurine and beta-alanine were induced in oocytes injected with poly(A)+ RNA extracted from 3 regions, cerebrum, cerebellum and brainstem of the mouse brain. From comparison, responses to these 4 inhibitory amino acids in each regional poly(A)+ RNA-injected oocytes were categorized into at least 3 groups: (1) GABA, (2) glycine, and (3) taurine and beta-alanine. No cross-desensitization was observed between GABA response and glycine response, but taurine and beta-alanine responses cross-desensitized both the GABA and glycine responses. Taurine and beta-alanine responses were partially inhibited by the GABA antagonist, bicuculline, and also by the glycine antagonist, strychnine. The results suggest that the taurine or the beta-alanine response in the brain is caused through both the GABA receptor and the glycine receptor.

Alanine↗
PubMed1988

Taurine modulates glycine response in Xenopus oocytes injected with messenger RNA from mouse brain.

The modulatory action of taurine on the glycine response was investigated in Xenopus oocytes injected with messenger RNA from mouse brainstem under voltage-clamped condition. Taurine competitively inhibited the glycine response in a dose-dependent manner. This inhibition was insensitive to bicuculline and intracellularly injected EGTA. The results suggest that taurine could directly modulate glycinergic neurotransmission in the central nervous system.

Animals↗
PubMed1988

Effects of panose on glucan synthesis and cellular adherence by Streptococcus mutans.

The effects of panose on glucan synthesis and sucrose-dependent cellular adherence by Streptococcus mutans were investigated. Panose effectively inhibited glucan synthesis from sucrose by glucosyltransferases from S. mutans strain 6715, but increasing amounts of panose increased the release of fructose from sucrose by the enzymes. On the other hand, production of a series of oligosaccharides of increasing size by the enzymes was markedly enhanced in the presence of panose. These results indicate that panose activates the enzymes and that the inhibition of glucan synthesis by panose is due to the transfer of the glucosyl group of sucrose to panose. Sucrose-dependent adherence of cells of various S. mutans strains to a glass surface was also inhibited by panose.

Bacterial Adhesion↗
PubMed1987

The distribution of GABA and glycine response in the mouse brain using Xenopus oocytes.

Injection of mRNA from different regions of the central nervous system (CNS) of the mouse into the Xenopus oocyte caused a difference in the relative glycine to gamma-aminobutyric acid (GABA) response of the oocyte. Glycine caused the response in oocytes injected with brainstem mRNA but hardly in oocytes injected with cerebrum mRNA and in oocytes injected with cerebellum mRNA. In contrast, GABA caused the response in oocytes injected with mRNA from each of the 3 parts of the CNS. These obvious regional differences may reflect the distribution of the receptors to each plausible neurotransmitter in the CNS.

Animals↗
PubMed1987

Symmetrical bilateral low-density lesions in the areas of supply by Heubner's arteries after aneurysm surgery.

Three patients with symmetrical bilateral low-density areas which were the perfusion territories of Heubner's arteries are reported. The infarctions were demonstrated on computed tomography after aneurysm surgery. Two of them had an anterior communicating artery aneurysm and the other one had multiple aneurysms of both sides. They were operated upon in the acute stage after subarachnoid haemorrhage. As common factors, a thick and diffuse subarachnoid haemorrhage, an acute-stage operation, temporary clips to bilateral A1 segments or the internal carotid artery and a relatively low systemic blood pressure during operation were found. From these findings we conclude that the pathogenesis of the infarctions was due to occlusive changes affecting Heubner's arteries bilaterally.

Caudate Nucleus↗