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Biomedical subjects

T Horikoshi

Publications and source records attributed to T Horikoshi.

At least 91 records · Page 5Linked to original sources
PubMed1992

Alteration of melanoma melanogenesis by phenotypic modifiers.

Human melanoma cells (MM96E) were incubated with a phenotypic modifier (L-ethionine) to compare its effects on phenotypic expression with those induced by sodium butyrate and dimethyl sulfoxide. In contrast to the latter agents, L-ethionine (8mM) failed to arrest the cell cycle at the G1 phase or to inhibit colony formation ability after 48 hr incubation. Tyrosinase activity changed in parallel with 5-S-cysteinyldopa (5-S-CD) content during treatment with sodium butyrate or dimethyl sulfoxide. Tyrosinase was inhibited in L-ethionine-treated cells, probably because of metabolism of L-ethionine to sulfhydryl compounds; this remains to be clarified. Gamma-glutamyl transpeptidase activity changed inversely with tyrosinase activity after sodium butyrate or dimethyl sulfoxide incubation, whereas L-ethionine did not significantly alter the enzyme activity. In addition, only sodium butyrate induced alkaline phosphatase activity. L-ethionine was less effective than sodium butyrate or dimethyl sulfoxide in inhibiting expression of the B8G3 melanosomal antigen, as determined by Western blotting. These results suggest that phenotypic modifiers (differentiation inducers) affect melanoma cells in various ways and that melanogenesis therefore reflects only one aspect of differentiation in pigment cells.

Alkaline Phosphatase↗
PubMed1992

Inhibitory effect of human fibroblast interferon (HuIFN-beta) on the growth and invasive potential of cultured human melanoma cells in vitro.

The effect of HuIFN-beta on the invasive potential of melanoma cells was studied using an in-vitro model system with Transwell chambers equipped with matrigel-coated polycarbonate filters. When (10(2), 10(3) and 10(4) IU/ml) for 3 days and then grown in medium without HuIFN-beta for another 7 days. On day 7, the proliferation of melanoma cells was inhibited by 77 and 87%, respectively, when cells were treated with 10(2) and 10(4) IU/ml of HuIFN-beta. This antiproliferative effect was dose-dependent and more pronounced on day 11. The effect of HuIFN-beta on the invasive potential of melanoma cells was studied using an in-vitro model system with Transwell chambers equipped with Matrigel-coated polycarbonate filters. When cells were treated with HuIFN-beta (10(2), 10(3) and 10(4) IU/ml) for 24 h, the amount of tritiated thymidine incorporated into cells was increased, indicating that cell growth was not inhibited. However, the number of cells that invaded to the filter decreased significantly by 15-40%. HuIFN-beta did not have an inhibitory effect on the haptotactic migration of melanoma cells. These data indicate that the antiproliferative effect of HuIFN-beta occurs after 24 h and that the direct anti-invasive effect is independent of any effect on proliferation.

Cell Division↗
PubMed1992

Monoclonal antibody analysis of phosphatidylserine and protein kinase C localizations in developing rat cerebellum.

Understanding the topographical relationships between phosphatidylserine (PS) and protein kinase C (PKC) within neurons can provide clues about the mechanism of translocation and activation of PKC. For this purpose we applied monoclonal antibodies (Abs) of PS and PKC to sections of developing rat cerebellum. The anti-PKC Ab immunohistochemical pattern showed homogeneous staining of Purkinje cells over various postnatal ages, whereas the anti-PS Ab staining showed a heterogeneous localization over these ages. Purkinje cells did not stain well between postnatal day 14 (PND 14) and PND 21, suggesting that the PS was lost from the membrane during preparation of the sections during this period. These data imply that interactions between PS and PKC vary in Purkinje cells during postnatal development.

Aging↗
PubMed1992

Partial resection of the gyrus rectus in pterional approach to anterior communicating artery aneurysms.

The effect of partial resection of the gyrus rectus during the unilateral pterional approach on surgical outcome was evaluated in 194 consecutive patients with ruptured anterior communicating artery aneurysms. Resection was performed more frequently in cases with poor clinical grade, in the acute stage, with superiorly directed aneurysms, and with high-positioned aneurysms. The surgical results were graded into three stages, and the follow-up results into five stages using the Glasgow Outcome Scale. Outcomes for 52 patients receiving gyrus rectus resection were compared with those for 142 patients without resection. There were no apparent effects caused by gyrus rectus resection on outcome.

Adolescent↗
PubMed1992

Giant aneurysm of the azygos anterior cerebral artery associated with acute subdural hematoma--case report.

A ruptured giant aneurysm of the azygos anterior cerebral artery (ACA) associated with an acute subdural hematoma (SDH) occurred in a 67-year-old male with two episodes of sudden severe headache and transient loss of consciousness. Neurologically, he had mild weakness of the left lower extremity. Computed tomography showed an elliptical heterogeneous hyperdense mass in the interhemispheric fissure in front of the corpus callosum and an acute SDH on the right. Angiography disclosed a giant aneurysm (2.8 x 2.0 cm) at the distal end of the azygos ACA. Removal of the SDH and aneurysmal neck clipping achieved a good outcome. Successive small bleedings may allow the aneurysmal dome to develop adhesions to the arachnoid membrane, and the final rupture will occur into the subdural space, resulting in a SDH.

Acute Disease↗
PubMed1992

Oblique sagittal magnetic resonance imaging visualizing vascular compression of the trigeminal or facial nerve.

An oblique sagittal magnetic resonance (MR) imaging method was developed to provide better visualization of vascular compression of nerves. The MR images of 12 patients with trigeminal neuralgia and 24 with hemifacial spasm were analyzed. The oblique sagittal views were obtained along the nerve identified by the axial view at an angle of 105 degrees between the line along the dorsal brain stem and the line along the margin of the pontomedullary junction (in patients with hemifacial spasm) or by the midsagittal view through the midpons (in patients with trigeminal neuralgia). The T1- and T2-weighted, proton-density, and/or gradient-echo MR images were evaluated to optimize imaging conditions. The oblique sagittal gradient-echo MR image most clearly visualized vascular compression of the nerves as high-intensity lines in six patients with trigeminal neuralgia, which was confirmed intraoperatively in four. Fifteen (75%) of 20 oblique sagittal gradient-echo MR images demonstrated vascular compression of the facial nerves in patients with hemifacial spasm; 12 of these were confirmed intraoperatively. The control study used 15 oblique sagittal gradient-echo MR images of nonaffected contralateral and normal sites. Four false-positive findings were found. Oblique sagittal gradient-echo MR images are a useful planning aid, allowing differential diagnosis prior to microvascular decompression in trigeminal neuralgia and hemifacial spasm.

Adult↗
PubMed1992

p53 gene mutation in primary human renal cell carcinoma.

We searched for possible mutations in the entire coding region of tumor suppressor gene p53 in primary human renal cell carcinomas using polymerase chain reaction and single-strand conformational polymorphism analysis of RNA. We found p53 mutations in 2 of 21 cases (10%). DNA sequencing of the polymerase chain reaction products verified that the first case included a 17-base deletion at the beginning of exon 6. The second case showed a T to C transition at nucleotide 1328 in exon 7. No clinical or pathological similarity was found in the renal cell carcinomas containing the mutated p53 genes. Present results suggest that p53 mutation is involved at low frequency in human renal cell carcinomas.

Base Sequence↗
PubMed1992

[Clinical effect of proton pump inhibitors on reflux esophagitis].

The clinical efficacy of proton pump inhibitors (PPI, omeprazole 20 mg or lansoprazole 30 mg), once daily, after breakfast, was studied in patients with erosive/ulcerative reflux esophagitis. The following results were obtained. 1) Twenty-four hour esophageal pH monitoring was performed before treatment and on 7th day of PPI medications. Omeprazole reduced the percent time pH less than 4 from 29.1 to 1.2 and lansoprazole from 68.0 to 2.4. 2) The cumulative disappearance rate of overall symptom was 52% after 1 week and 62% after 2 weeks with omeprazole these were 66% and 91%, and with lansoprazole respectively 3) The endoscopic healing rate was 63% was after 2 weeks and 76% after 4 weeks with omeprazole medication, and 76% and 97% respectively with lansoprazole. These results indicate that PPI medication inhibits the acid reflux almost completely and is a more useful therapeutic agent for GERD than H2-antagonists.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1991

Inactivation of Tetrahymena rRNA self-splicing by cis-platin proceeds through dissociable complexes.

The anti-cancer drug cis-diamminedichloroplatinum (II) (cis-DDP) reacted with Tetrahymena self-splicing rRNA ribozyme, causing loss of self-splicing activity and formation of a number of platinated RNA species. The formation of one distinct platinated product, migrating at an apparent size of 2400 nt, was closely associated with ribozyme inactivation. This platinated RNA was resistant to T1 ribonuclease digestion, suggesting the presence of inter-strand Pt cross-links. The reaction rate of cis-DDP with the ribozyme followed first order kinetics and showed a saturation effect with increasing cis-DDP concentration, characteristic of an affinity-label type of interaction rather than bimolecular collision. The apparent KI for binding of cis-DDP to the ribozyme was 62 microM. Ribozyme treated with urea was not inactivated by cis-DDP, indicating that the native structure of the RNA is required for reaction with cis-DDP. Mg++, which binds to the ribozyme and causes conformational changes in the molecule, protected the ribozyme from inactivation by cis-DDP and also prevented the formation of platinated RNA. These results suggest that binding of cis-DDP to sites formed by certain secondary or tertiary structural elements of the RNA enhance the rate and the specificity of reaction of the reagent with the ribozyme.

Animals↗
PubMed1991

Comparative efficacy of acid reflux inhibition by drug therapy in reflux esophagitis.

The advent of histamine H2 receptor antagonists (H2-RA) has allowed the treatment of reflux esophagitis (RE) to be controlled over a relatively long term. The authors have experienced some cases resistant to H2-RA, but it was revealed that these cases can be successfully treated with proton pump inhibitors. It has been suggested that esophagogastric dysmotility can lead to RE. RE has been treated for many years by using GI-prokinetic agents, which theoretically inhibit acid reflux and improve esophageal acid clearance. In order to compare the effects on acid reflux of an H2-RA (famotidine), a proton pump inhibitor (omeprazole) and a GI-prokinetic agent (cisapride), we measured the 24-hour pH in the esophagus and stomach simultaneously, before and after treatment in 17 patients with RE. It was found that the proton pump inhibitor was the most effective drug for inhibiting esophageal acidification, followed by famotidine and then cisapride. Furthermore, we found that cisapride often actually exacerbated acid reflux. The differences in inhibitory effects on acidification allowed us to draw conclusions regarding the treatment of RE. It was concluded that the stronger the inhibitory effect of a drug on acid secretion, the more useful it was in the treatment of RE. The GI-prokinetic drug did not inhibit acid reflux as much as we had expected.

Adult↗
PubMed1991

Effects of famotidine on upper gastrointestinal motility in patients with progressive systemic sclerosis.

The effects of famotidine on human upper gastrointestinal motility were investigated, together with the relationship of gastric alkalinization and serum gastrin levels to changes produced by famotidine. Intravenous famotidine (20 mg), at a dose level in which an inhibitory effect on acetylcholinesterase activity is not recognized, was given to 13 patients with progressive systemic sclerosis but no other disorders. Gastric phasic motor activity was not changed significantly, but the lower esophageal sphincter pressure was elevated significantly in comparison with 15 controls given physiological saline, even when gastric phasic motor activity was taken into consideration. Gastric alkalinization with 7% sodium bicarbonate did not significantly increase the sphincter pressure in all 7 subjects so treated. No significant correlation was recognized between the serum gastrin level, the lower esophageal sphincter pressure, and the gastric motility index in any of the 3 groups. It was, therefore, concluded that intravenous administration of famotidine affected upper gastrointestinal motility, especially the lower esophageal sphincter pressure, through an as yet unknown mechanism other than inhibition of acetylcholinesterase activity, gastric alkalinization, or elevation of serum gastrin levels.

Adult↗
PubMed1991

Developmental assembly of calcium-mobilizing systems for excitatory amino acids in rat cerebellum.

The postnatal development of calcium-mobilizing systems was studied by both microfluorometric imaging analysis of Ca2+ on living rat cerebellar slices and immunohistochemical labeling of phosphatidylinositol 4,5-bisphosphate (PIP2) and inositol 1,4,5-trisphosphate binding protein (IP3BP) in fixed rat cerebellum. Stimulation with quisqualate (QA) or N-methyl-D-aspartate (NMDA) enhanced the Ca2+ level only diffusely on postnatal day (PND) 3, but more discretely on PNDs 7 and 15. On PND 21, QA-induced responses were localized in the molecular layer especially, but not in the granular layer. By contrast, NMDA mobilized Ca2+ prominently in the granular layer, but only weakly in the molecular layer. Localized expression of PIP2 in the molecular layer paralleled QA-induced Ca2+ mobilization, but IP3BP was expressed more diffusely. The present study offers the first direct evidence that PIP2, but not IP3BP, is essential for QA-induced Ca2+ mobilization in the cerebellar cortex.

Amino Acids↗
PubMed1991

Effects of oxygen tension on the growth and pigmentation of normal human melanocytes.

The effects of oxygen tension on human melanocyte growth, tyrosinase activity, and melanin production were assessed. Melanocytes, seeded at 10(4) cells/cm2, were grown in modified Eagle's medium (MEM) with 5% fetal bovine serum (FBS) and 10 ng/ml 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Flasks were equilibrated with gas mixtures containing 5% CO2 and various partial pressures of oxygen (PO2 7-620 mm Hg) and kept in incubators, which were electronically maintained at the desired oxygen tensions. Melanocytes grew best at PO2 from 6-34 mm Hg. Growth was reduced by 30% at PO2 142 mm Hg, and even more at O2 tensions greater than 230 mm Hg. A PO2 of 603 mm Hg was cytotoxic. Tyrosinase activity (assayed by the method of Pomerantz) was 300 microU/mg protein at PO2 7-34 mm Hg. At PO2 235 and 355 mm Hg tyrosinase activity decreased to about 100 microU/mg protein. The apparent Km for tyrosine was unchanged in melanocytes cultured at all experimental oxygen tensions. The Vmax, however, was decreased at the higher oxygen tensions (PO2 235 mm Hg). At PO2 6-135 mm Hg the melanin content was proportional to tyrosinase activity. At cytostatic oxygen tensions (PO2 235 and 355 mm Hg) the intracellular melanin content increased somewhat, although tyrosinase activity was decreased. Low oxygen tension is favorable for both melanocyte proliferation and tyrosinase activity.

Cell Division↗
PubMed1991

Oral passive immunization against dental caries in rats by use of hen egg yolk antibodies specific for cell-associated glucosyltransferase of Streptococcus mutans.

The effect of polyclonal egg yolk immunoglobulin G antibodies (yIgG) raised against whole cells, cell-free (CF) glucosyltransferase (GTase), or cell-associated (CA) GTase of serotype c Streptococcus mutans was examined in terms of in vitro inhibition of virulence-related factors of S. mutans and protection of S. mutans-infected rats against the development of dental caries. Hens (18 weeks old) were immunized with formalin-treated whole cells, purified CF-GTase, or CA-GTase together with Freund's complete adjuvant. In addition, yIgG to surface protein antigen was used in some in vitro experiments for comparison with other antibodies. yIgG was purified by ammonium sulfate precipitation followed by DEAE-Sephacel column chromatography or fractional precipitation with ethanol. Purified yIgG was found to be a 220-kDa protein, which was dissociated into heavy and light chains upon addition of 2-mercaptoethanol. yIgG to whole cells and surface protein antigen gave a heavy aggregation of S. mutans organisms, while yIgG to CF- and CA-GTase specifically inhibited the enzymatic activity of the respective GTase. yIgG to CA-GTase and whole cells was found to clearly suppress the adherence of S. mutans cells to a glass surface. Specific-pathogen-free Sprague-Dawley rats that had been infected heavily and repeatedly with S. mutans and fed diet no. 2000 developed severe dental caries, while rats fed diet 2000 containing greater than or equal to 0.1% yIgG to CA-GTase showed a statistically significant reduction in dental plaque accumulation and caries development. Administration of yIgG to CF-GTase and whole cells failed to protect against caries. These results clearly suggest that yIgG to S. mutants CA-GTase specifically inhibited a virulence factor of this organism, i.e., insoluble glucan-synthesizing CA-GTase, resulting in a significant reduction in the development of dental caries.

Administration, Oral↗
PubMed1991

[Interdigestive migrating complex (IMC) and effect of cisapride in patients with non-ulcer dyspepsia (NUD)].

The 24-hr gastric and duodenal pressure measurement was performed in 5 patients with non-ulcer dyspepsia (NUD). The reduction of incidence of IMC and prolongation of the first appearance of IMC after evening meal were observed in NUD patients. The gastroprokinetic agent, cisapride 5 mg, 3 times a day for 7 days significantly increased the incidence of IMC and shortened the time before the first appearance of IMC after evening meal. This result indicates that in NUD patients impaired gastrointestinal motility is present in fasting phases and cisapride may be useful for correcting motility disorders.

Aged↗
PubMed1990

The relationship between interdigestive gallbladder and gastroduodenal motility in man.

The relationship between interdigestive gallbladder and gastroduodenal motility simultaneously with the behavior of plasma motilin and CCK levels in 20 subjects was investigated. We used an infusion catheter method for the measurement of gastroduodenal motility, and real-time ultrasonography for the measurement of gallbladder size. In gastric phase II, the gallbladder contracted with extension of the major axis and shrinking of the minor axis, with its minimum volume being 84% of the volume in phase I. The gallbladder then filled rapidly assuming a sphere-like shape with extension of the minor axis and shrinking of the major axis in gastric phase I. This motility was recognized only during the gastrointestinal interdigestive migrating complex (GI-IMC) cycle, originating in the stomach, and was associated with an increase of motilin levels, it was not seen before or after the intestinal IMC (I-IMC), which originated in the duodenum without contraction of the stomach or an increase of motilin levels. Furthermore no apparent relationship was recognized between CCK and gastric or gallbladder motility. Our findings suggest that gallbladder motility in the interdigestive period has a close relationship with gastroduodenal motility and is related to the appearance of the GI-IMC.

Adult↗