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Biomedical subjects

T Okuda

Publications and source records attributed to T Okuda.

At least 19 recordsLinked to original sources

Involvement of rho in GTP gamma S-induced enhancement of phosphorylation of 20 kDa myosin light chain in vascular smooth muscle cells: inhibition of phosphatase activity.

In beta-escin-permeabilized cultured pig aortic smooth muscle cells GTP gamma S dose-dependently enhances Ca(2+)-induced, wortmannin-sensitive phosphorylation of 20 kDa myosin light chain (MLC20). GTP gamma S does not potentiate thiophosphorylation of MLC20, but does inhibit its dephosphorylation. Pretreatment with C. botulinum exotoxin C3, which specifically ADP-ribosylates and inactivates the rho family of the small molecular weight G proteins, completely abolishes the effects of GTP gamma S. These results indicate that rho is involved in the GTP gamma S-induced enhancement of Ca(2+)-dependent MLC20 phosphorylation in aortic smooth muscle cells, and strongly suggest that this effect of rho is due to inhibition of protein phosphatase activity toward MLC20.

Animals

Frequent deletion of p16INK4a/MTS1 and p15INK4b/MTS2 in pediatric acute lymphoblastic leukemia.

The tandemly linked p16INK4aMTS1 and p15INK4b/MTS2 genes on chromosome 9, band p21 encode proteins that function as specific inhibitors of the cyclin D-dependent kinases CDK4 and CDK6. This locus undergoes frequent bi-allelic deletion in human cancer cell lines, suggesting that the encoded proteins may function as tumor suppressors. However, more recent analysis of primary tumor samples has shown a much lower frequency of abnormalities affecting this region, raising doubt over the importance of these proteins in human malignancies. Hemizygous deletions and rearrangements of chromosome 9, band p21, are among the most frequent cytogenetic abnormalities detected in pediatric acute lymphoblastic leukemia (ALL), occurring in approximately 10% of cases. To determine if the p16INK4a/p15INK4b locus might be the target of these chromosomal lesions, we analyzed both genes in primary clinical samples from 43 pediatric ALL patients using interphase fluorescence in situ hybridization, Southern blot analysis, and the polymerase chain reaction. Deletions of p16INK4a/p15INK4b were identified in 18 of 20 cases with cytogenetically observed abnormalities of 9p and 5 of 23 with apparently normal chromosomes 9p, with the majority containing bi-allelic deletions (16 homozygous/7 hemizygous). Although most homozygous deletions involved both genes, Southern blot analysis showed an interstitial deletion in a single case that was confined to p16INK4a, suggesting that p15INK4b was not the critical target gene in this case. Sequence analysis of both p16INK4a and p15INK4b in all seven cases with hemizygous deletions failed to show mutations within the coding regions of the retained alleles. In this select group of patients, deletion of p16INK4a/p15INK4b was associated with T-cell phenotype, nonhyperdiploid karyotype (< 50 chromosomes), and poor event-free survival. These findings indicate that deletion of the p16INK4a/p15INK4b locus is one of the most common genetic abnormalities so far detected in pediatric ALL, and that loss of one or more of these cell cycle kinase inhibitors is important in leukemogenesis.

Adolescent

Hyperventilation activation on EEG recording in children with epilepsy.

In 20 patients with epilepsy, electroencephalography (EEG) slowing was quantitatively characterized during standardized hyperventilation activation (respiratory rate: 30/min, threefold elevation of total expiratory volume, duration: 4 min) and changes in cerebral blood flow and velocity in the right common carotid artery were monitored with the Doppler ultrasonic method. Thirteen age-matched normal children served as controls. The results were as follows: (1) EEG slowing in the epilepsy group was greater compared with controls. (2) There was a significant decrease in mean frequency (decrease in alpha power and increase in delta power) during hyperventilation in the epilepsy group, but no significant change in the controls. (3) The decrease in cerebral blood flow (CBF) was greater in the epilepsy group at the beginning of hyperventilation, possibly related to the greater EEG slowing. (4) The percentage of CBF at the end of hyperventilation was similar in the epilepsy and control groups. The difference in EEG response to hyperventilation between the 2 groups may be due to differences in the decrease in CBF volume and the sensitivity of the change in CBF.

Blood Flow Velocity

Insulin nonattenuation of vasoactive agent-induced responses in mesangial cells from spontaneously hypertensive rats.

We recently found that insulin attenuates intracellular calcium transients and cell contraction caused by vasoactive agents in cultured rat mesangial cells. Because altered glomerular function may be causally related to the evolution of hypertension, we examined in the present study the effects of insulin on the functions of mesangial cells derived from spontaneously hypertensive rats (SHR) of 4- and 8-weeks of age. Age-matched Wistar Kyoto rats (WKY) were used as controls. Intracellular calcium concentration ([Ca2+]i) was measured with Fura-2 method in suspended mesangial cells. Pretreatment of mesangial cells with 5 micrograms/ml insulin for 120 minutes did not affect basal [Ca2+]i in either WKY or SHR mesangial cells. However, insulin pretreatment significantly attenuated [Ca2+]i transients to vasoactive agents in WKY mesangial cells. In contrast, [Ca2+]i transients to these agents were not attenuated by insulin in SHR mesangial cells. Additionally, SHR mesangial cell contraction in response to angiotensin II (Ang II) was not altered by insulin, while WKY mesangial cell contraction to Ang II was, as in normal Wistar rats, significantly reduced by insulin. Since we previously showed the possibility that the attenuation of calcium signal by insulin is via insulin-like growth factor I (IGF-I) receptor, we also examined the effect of IGF-I. In contrast to WKY mesangial cells, IGF-I-induced attenuation of [Ca2+]i responses to platelet activating factor was absent in SHR mesangial cells. [125I]-IGF-I binding in SHR mesangial cells was not significantly different from that in WKY mesangial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II

Effects of sevoflurane on the middle latency auditory evoked response and the electroencephalographic power spectrum.

We investigated the effects of sevoflurane on the middle latency auditory evoked response (MLR) and the power spectrum of the electroencephalogram (EEG) in 10 elective surgical patients. The MLR and the EEG power spectrum were recorded with a surface electrode placed at the central (Cz) scalp location. End-tidal sevoflurane concentrations of 0%, 0.25%, 0.5%, 0.75%, 1.0%, and 1.5% in 50% nitrous oxide and oxygen were studied. The Na, Pa, and Nb components of the MLR increased in latency and decreased in amplitude in a dose-dependent manner at increasing concentrations of sevoflurane. The latencies for Na, Pa, and Nb increased in a linear fashion (correlation coefficients: r = 0.81, r = 0.81, and r = 0.89, respectively). The EEG delta power was dominant with increasing sevoflurane concentration, and was significantly increased at sevoflurane concentrations of 1.0%-1.5%. The beta power, median power frequency (MPF), and 95% spectral edge frequency (SEF) decreased significantly according to the increases by 0.5% sevoflurane. Regarding the changes evoked by 0.25% sevoflurane, the Nb latency of the MLR responded significantly under 0.75% of sevoflurane. At these low concentrations of sevoflurane, the MLR seemed to be more sensitive to changes in anesthetic concentration than the various EEG variables.

Anesthetics

Physical linkage of the cdc2-related gene (PCTK1) and the ubiquitin-activating enzyme E1 gene (UBE1) on human Xp11.3.

PCTAIRE-1 is a cdc2-related protein kinase of unknown function. The gene (PCTK1) has been mapped to chromosome Xp. In this study we refine the locus position by chromosome analysis with cosmid and YAC probes. PCTK1 maps distal to the t(X;18) synovial sarcoma breakpoint in Xp11.23. A 420-kb YAC clone positive for PCTK1 also contains the gene coding for ubiquitin-activating enzyme UBE1, previously mapped in Xp11.3, indicating close physical linkage of these genes. PCTK1 is a new candidate for heritable disorders mapped to Xp11.3--p11.23 region.

Base Sequence

[Tannins, a new family of bio-active natural organic compounds (questions and answers)].

Twelve questions concerning tannin selected from questions raised by other workers on the author's research were picked up. The answers of each question are as follows. 1. What is tannin?--the differences between the old concept and the new definition of tannin. 2. Is tannic acid the same as tannin? 3. How could each tannin be analyzed as a pure compound? 4. Which tannin found in recent years is implicated with the change of the concept of tannin in medicinal plants? 5. Is it possible that one to several chemical structures represent tannins contained in each plant species? 6. Which tannin-containing plants met in the human life are rich in tannins? 7. Is tannin produced by all species of plants?--a correlation between the occurrence of hydrolyzable tannins and the plant evolution system. 8. When and where are the hydrolyzable tannin oligomers produced, in the plant or after extraction? 9. Are tannins bound to other substances in the plants? 10. Is it appropriate to call tannins "plant polyphenols"? 11. Is it true that tannins are inhibitors of enzymes? 12. What kind of biological activities have been found for tannins.

Animals

[Effect of the interaction of tannins with coexisting substances. VIII. Inhibitory effect of tannins on discoloration of natural pigments].

The discoloration of shikonin (1) and beta-carotene (2), occurring during storage of their ethanol solutions in the presence of oxygen in an illuminated room, was remarkably suppressed by hydrolyzable tannins, such as geraniin (4) and tannic acid JP (3) in the solution. The inhibitory effect of tannins was enhanced by the coexistence of metallic ion. The irradiation with ultraviolet lamp (254 and 365 nm) gave, at the first stage of the discoloration, two products, one of which was found to be 5,8-dihydroxy-2-(1-hydroxy-3-oxo-4-methyl-4-pentenyl)-1,4-naphthoquinone (7). The presence of hydrolyzable tannins induced higher accumulation of these two products in the solution, showing that the secondary structural transformations of these two products were strongly inhibited by these coexisting tannins. These results suggest that tannins could be efficient inhibitors of discoloration of natural pigments.

Carotenoids

[Prognostic evaluation of peritoneal lavage smears and gastric wall brushing smears in gastric cancer surgery].

We investigated the correlation of intraoperative peritoneal lavage smear and gastric wall brushing smear cytology with macroscopic and histologic findings and prognosis, in 216 patients with gastric cancer. Some 196 of these patients underwent gastric resection and 20 did not. The incidence of positive cancer cells determined by these methods was significantly correlated with gastric resection, tumor invasion, and peritoneal dissemination. Among patients without macroscopic peritoneal dissemination, four were found to have positive peritoneal lavage smears or gastric wall brushing smears, respectively. The prognosis of these patients did not differ from that of patients with metastases to the adjacent peritoneum but not the distant peritoneum. These results suggest that peritoneal lavage smears and gastric wall brushing smears are useful for predicting the peritoneal cancer dissemination. Therefore we intend to target patients with no peritoneal metastases (Po) showing positive peritoneal cytology for intensive treatment.

Female

[Effects of nitroglycerin, prostaglandin E1, trimetaphan and nicardipine on systemic vascular resistance, pulmonary vascular resistance and pulmonary-systemic vascular resistance ratio in dogs].

Effects of the experimentally induced hypotension with 4 vasodilators; nitroglycerin (TNG), prostaglandin E1 (PGE1), trimetaphan (TMP) and nicardipine (NCP) on systemic vascular resistance (SVR), pulmonary vascular resistance (PVR) and pulmonary-systemic vascular resistance ratio (PVR/SVR ratio) were studied in dogs. The SVR values were significantly reduced by TNG, PGE1 and NCP, and not affected by TMP. The PVR values were significantly reduced by TNG and PGE1, and not affected by TMP and NCP. The PVR/SVR ratio values were significantly reduced by TNG, and significantly increased by NCP, and not affected by PGE1 and TMP. We concluded that TNG reduced PVR and SVR but it affected PVR more; PGE1 reduced PVR and SVR equivalently; TMP did not affect PVR and SVR remarkably; NCP reduced SVR but did not affect PVR.

Alprostadil

A dimeric hydrolysable tannin from Camellia oleifera.

Camellioferin A, a new dimeric ellagitannin, was isolated, together with 13 known tannins, including camellins A and B, from Camellia oleifera. The structure of the new tannin elucidated by spectroscopic methods.

Circular Dichroism

Hispidospermidin, a novel phospholipase C inhibitor produced by Chaetosphaeronema hispidulum (Cda) Moesz NR 7127. I. Screening, taxonomy, and fermentation.

A novel phospholipase C inhibitor, hispidospermidin, was discovered from a fungal culture broth. The producing fungus, NR 7127, formed abundant pycnidia on banana leaf agar under near UV light. The ostiolate pycnidia were dark colored with a short beak possessing numerous protruding setae. The conidiogeneous cells were phialidic. The conidia were hyaline, 1 septate, smooth and spindle-shaped. From these distinctive characteristics, this strain was identified as Chaetosphaeronema hispidulum (Cda) Moesz of the Coelomycetes. Hispidospermidin was produced in a 50-liter jar fermentor containing 2% glucose, 2% potato starch, 2% Toast soya, 0.5% yeast extract, 0.25% NaCl, 0.0005% ZnSO4.7H2O, 0.0005% CuSO4.5H2O, 0.0005% MnSO4.4H2O, 0.32% CaCO3, and 0.3% Nissan disfoam CA-115. Fermentation was conducted at 27 degrees C at an aeration rate of 30 liters/minute and agitated at 500 rpm for 95 hours. Maximum production yield of hispidospermidin was observed after 72 hours. Hispidospermidin inhibited rat brain phospholipase C at 16 microM of IC50. This is the first recorded discovery of a secondary metabolite from the genus Chaetosphaeronema.

Animals

pokkuri, a Drosophila gene encoding an E-26-specific (Ets) domain protein, prevents overproduction of the R7 photoreceptor.

Studies on sevenless and bride of sevenless genes have revealed that the R8 cell plays a key role in the fate of the R7 photoreceptor cell, presenting on its surface an inductive cue to which R7 responds. sev-independent induction of R7 cells has been reported in the seven-up mutation, which appears to transform R1 and R6 cells to R7 cells. We have induced recessive mutations in a gene pokkuri (pok; pokkuri is a Japanese word that means "dropping dead") that lead to overproduction of R7 cells with rather minor effects on outer photoreceptors and R8 cells. Pok protein may function as a transcription factor, as the predicted amino acid sequence contains a region similar to the consensus established for the E-26-specific (Ets) domain.

Amino Acid Sequence

Mouse mammary tumor virus gene expression is suppressed by oligomeric ellagitannins, novel inhibitors of poly(ADP-ribose) glycohydrolase.

Oligomeric ellagitannins (nobotanins B, E, and K) were found to be potent inhibitors of poly(ADP-ribose) glycohydrolase purified from mouse mammary tumor 34I cells. Kinetic analysis revealed that the inhibition of nobotanin B (dimer) was competitive with respect to the substrate poly(ADP-ribose), whereas nobotanin E (trimer) and nobotanin K (tetramer) exhibited mixed-type inhibition. These results suggest that the dimeric structure of ellagitannin may have a functional domain that competes with poly(ADP-ribose) on the poly(ADP-ribose) glycohydrolase molecule. To determine the inhibitory effects of oligomeric ellagitannins on poly(ADP-ribose) glycohydrolase in vivo, we examined their effects on de-poly(ADP-ribosyl)ation of some chromosomal proteins in intact 34I cells that was induced by glucocorticoid treatment. Nobotanin B caused concentration-dependent inhibition of glucocorticoid-induced de-poly(ADP-ribosyl)ation of HMG 14 and 17 and histone H1 in intact 34I cells. Interestingly, this inhibition was associated with suppression of the glucocorticoid-sensitive mouse mammary tumor virus (MMTV) mRNA synthesis. In contrast, nobotanin E and K had little inhibitory effect on either de-poly(ADP-ribosyl)ation of these proteins or induction of MMTV transcription after glucocorticoid treatment. Nobotanin B but not E and K was taken into 34I cells. These results may suggest that the suppression of glucocorticoid-sensitive MMTV transcription results from in vivo inhibition of poly(ADP-ribose) glycohydrolase by nobotanin B. These results also indicate the importance of de-poly(ADP-ribosyl)ation of HMG 14 and 17 and histone H1 in regulation of transcription of the glucocorticoid-sensitive MMTV gene.

Animals

Pharmacologically active tannins isolated from medicinal plants.

Starting with the isolation of a crystalline tannin (geraniin) of mild property from a popular herb medicine (Geranii herba), various polyphenolic compounds including those belonging to new classes of tannins (oligomeric hydrolyzable tannins, complex tannins, and other metabolites and condensates) have been isolated from various medicinal plants. Noticeable biological and pharmacological activities (inhibition of carcinogenesis, host-mediated antitumor activity, antiviral activity, and inhibition of active oxygen, such as inhibition of lipid peroxidation and lipoxygenase, xanthine oxidase, and monoamine oxidase) have been found for several of these polyphenolic compounds.

Animals