Search PubMed⌕ Search

Biomedical subjects

T Okuda

Publications and source records attributed to T Okuda.

At least 199 records · Page 11Linked to original sources
PubMed1994

Purification and characterization of a juvenile hormone binding protein from hemolymph of the silkworm, Bombyx mori.

A juvenile hormone binding protein (JHBP) has been isolated from Bombyx mori hemolymph by gel filtration, ion-exchange chromatography, chromatofocusing and hydroxyapatite column chromatography. Gel electrophoresis indicates that the isolated protein is homogeneous in the presence or absence of a denaturing agent. The JHBP in question has a relative molecular mass of 32 kDa, determined by denaturing gel electrophoresis. Chromatofocusing analysis indicated that the JHBP is an acidic protein with pI 4.9. The protein exhibits a dissociation constant of 9.0 x 10(-8) M for JH I, 1.14 x 10(-7) M for JH II and 3.9 x 10(-7) M for JH III, and thus its affinity for JH analogues is in the order of JH I > JH II > JH III. Its amino acid composition indicates that the protein consists of 297 residues of 18 kinds of amino acids. The sequence of the N-terminus of the polypeptide chain was determined for 34 of the first 36 residues: Asp-Gln-Asp-Ala-Leu-Leu- Lys-Pro-?-Lys-Leu-Gly-Asp-Met-Gln-Ser-Leu-Ser-Ser-Ala-Thr-Gln-Gln-Phe-Le u-Glu- Lys-Thr-Ser-Lys-Gly-Ile-Pro-?-Tyr-His-.

Amino Acid Sequence↗
PubMed1994

Insulin attenuates intracellular calcium responses and cell contraction caused by vasoactive agents.

In the present study, we examined the effects of insulin and insulin-like growth factor I (IGF-I) on cultured rat mesangial cell responses to vasoactive agents. Intracellular calcium concentration ([Ca2+]i) was measured with the Fura-2 method in suspended mesangial cells. Pretreatment of mesangial cells with insulin (from 0.05 to 5 micrograms/ml) attenuated Ca2+ transients by platelet activating factor (PAF) in a dose dependent and a time dependent manner. Insulin also attenuated sustained elevation of [Ca2+]i elicited by PAF. Basal [Ca2+]i was not affected by insulin pretreatment. Since the effective dose of insulin (0.5 microgram/ml or higher) is much higher than the physiological concentration, the effects of insulin may be via IGF-I receptor. Indeed, IGF-I (50 ng/ml) similarly attenuated [Ca2+]i responses to PAF. Moreover, insulin pretreatment attenuated [Ca2+]i responses evoked by angiotensin II (Ang II) and endothelin-1. In addition, the pretreatment with insulin or IGF-I inhibited mesangial cell contraction in response to Ang II. The suppression of [Ca2+]i responses to vasoactive agents by insulin was abolished when extracellular Ca2+ was removed. These data suggest that insulin, probably via IGF-I receptor, attenuates [Ca2+]i responses and cell contraction of mesangial cells induced by vasoactive agents. It is likely that the change in Ca2+ influx from outside to inside the cell underlie the effect of insulin. The modification of mesangial cell function through IGF-I receptor may play a role in the regulation of glomerular hemodynamics.

Angiotensin II↗
PubMed1994

Mesangial cell ion transport and tubuloglomerular feedback.

Mesangial cells possess Ca(2+)-activated Cl- channels, Ca(2+)-activated K+ channels, voltage-gated Ca2+ channels, ATP-sensitive K+ channels, and two types of nonselective cation channels. Angiotensin II and arginine vasopressin depolarize the membrane. This membrane depolarization is caused by the activation of Ca(2+)-activated Cl- and Ca(2+)-activated nonselective cation channels through an elevation of intracellular Ca2+ concentration. The Ca(2+)-independent nonselective cation channel is activated by platelet-derived growth factor and is a candidate for the receptor-activated Ca2+ influx system. It has been suggested that macula densa Cl- reabsorption determines the Cl- concentration of juxtaglomerular apparatus interstitial fluid and thereby affects the resistance of afferent arterioles. In addition, angiotensin II-mediated and arginine vasopressin-mediated mesangial cell Ca2+ signals and contraction are attenuated via prostaglandin production by the mesangial cells themselves when the ambient Cl- concentration is reduced. Thus, Cl- plays an essential role in the tubuloglomerular feedback mechanism. The intracellular Ca2+ concentration appears to be important for the signal transduction mechanism of tubuloglomerular feedback. The ionic channels on the mesangial cell membrane may participate in controlling the intracellular Ca2+ concentration. The association of disturbed tubuloglomerular feedback and the development of hypertension has recently been reported.

Animals↗
PubMed1994

Response of pial vessel diameter and regional cerebral blood flow to CO2 during midazolam administration in cats.

Midazolam has been demonstrated to preserve the response of cerebral blood flow to CO2. However, the responsiveness of cerebral vessels or microcirculation during midazolam administration related to alteration of cerebral blood flow has not been explored. The purpose of this study was to examine the effects of midazolam on cerebral microcirculation. Nine cats were paralyzed and mechanically ventilated under nitrous oxide/oxygen anaesthesia. Using the closed cranial window technique and laser Doppler flowmetry, diameter of pial vessels and regional cerebral blood flow (rCBF) were examined on the surface of the cerebral cortex which was perfused by the middle cerebral artery. Before midazolam administration, haemodynamic variables, blood gases, rCBF, and diameter of pial vessels were determined as a control under normocapnia, hypocapnia, and hypercapnia conditions. After midazolam administration, given initially at 0.8 mg.kg-1.min-1 for 10 min and subsequently at 0.04 mg.kg-1.min-1 (total dose 10 mg.kg-1), the same variables were again analyzed. With regard to CO2 responsiveness, an 8.85% increase in rCBF was demonstrated for a Paco2 elevation of 1 kPa before midazolam administration, compared with a 7.47% increase after midazolam administration. With regard to the correlation between CO2 response and vessel diameter, arterioles less than 50 microns in diameter were more sensitive than those more than 50 microns in diameter, although there were no significant differences before or after midazolam administration. We conclude that CO2 responsiveness is preserved in terms of rCBF and vessel diameter after high doses of midazolam (10 mg.kg-1) in cats.

Animals↗
PubMed1994

Modification of mesangial cell function by chloride is attenuated in spontaneously hypertensive rats.

The effects of extracellular Cl- concentration ([Cl-]o) on cultured mesangial cells from spontaneously hypertensive rats (SHR) were examined. Angiotensin II (ANG II)- and vasopressin (VP)-induced cell contraction and Ca2+ transients of SHR mesangial cells were unaffected when the cells were preincubated with 10 mM [Cl-]o, while obvious suppression of the responses to these agents was observed in Wistar-Kyoto (WKY) mesangial cells. Enhanced prostaglandin E2 (PGE2) production was elicited by a decrease in [Cl-]o in WKY mesangial cells. In contrast, PGE2 synthesis by SHR mesangial cells was not enhanced by low [Cl-]o. However, ANG II-stimulated PGE2 production and the attenuation of ANG II-induced cell contraction and Ca2+ transients by the addition of exogenous PGE2 were present equally in both WKY and SHR mesangial cells. Based on these findings, we conclude that the absence of modification of mesangial cell function by [Cl-]o in SHR is due to the inability of low [Cl-]o to enhance PGE2 production. Insensitivity of SHR mesangial cells to changes in [Cl-]o might underlie the dysregulation of renal function in SHR.

Angiotensin II↗
PubMed1994

Tannins of theaceous plants. V. Camelliatannins F, G and H, three new tannins from Camellia japonica L.

Two new complex tannins, camelliatannins F (3) and G (4), were isolated from the leaves of Camellia japonica L. (Theaceae), and their structures, each consisting of an epicatechin unit and a C-glucosidic ellagitannin moiety, were elucidated. A new dimeric hydrolyzable tannin, named camelliatannin H (5), was isolated from the fruits of this plant. Camelliins A (6) and B (7), and camelliatannin A (1) and 3 were also isolated from the fruits.

Carbohydrate Sequence↗
PubMed1994

Tannins and related polyphenols of euphorbiaceous plants. XI. Three new hydrolyzable tannins and a polyphenol glucoside from Euphorbia humifusa.

Three new hydrolyzable tannins, euphormisins M1, M2, and M3, were isolated from Euphorbia humifusa WILLD., and respectively characterized as 1,3,6-tri-O-galloyl-4-O- brevifolincarboxyl-beta-D-glucose (19), an oxidative metabolite (23) of geraniin, and 1,3,6-tri-O-galloyl-alpha-D-glucose (18), by spectroscopic and chemical methods. A new ellagic acid glucoside (16) and fifteen known tannins, including geraniin (8) and four dimers [euphorbins A (13), B (14), excoecarianin (15) and eumaculin A (12)], were also isolated.

Flavonoids↗
PubMed1994

[Protein metabolism in vegans].

To elucidate the mechanisms of adaptation to a low-energy and low-protein vegan diet, we carried out dietary surveys and nitrogen balance studies five times during one year on two women and a man who ate raw brown rice, raw green vegetables, three kinds of raw roots, fruit and salt daily. Individual subjects modified this vegan diet slightly. The mean daily energy intake of the subjects was 18, 14, and 32 kcal/kg, of body weight. The loss of body weight was about 10% of the initial level. The daily nitrogen balance was -32, -33, and -11 mg N/kg of body weight. In spite of the negative nitrogen balance, the results of routine clinical tests, initially normal, did not change with the vegan diet. Ten months after the start of the vegan diet, the subjects were given 15N urea orally. The incorporation of 15N into serum proteins suggested that these subjects could utilize urea nitrogen for body protein synthesis. The level of 15N in serum proteins was close to the level in other normal adult men on a low-protein diet with adequate energy for 2 weeks.

Aged↗
PubMed1994

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↗
PubMed1994

Application of the random amplified polymorphic DNA using the polymerase chain reaction for efficient elimination of duplicate strains in microbial screening. I. Fungi.

For efficient fungal strain selection in microbial screening, we applied the random amplified polymorphic DNA (RAPD) method using the polymerase chain reaction (PCR). In order to evaluate this system, the genus Trichoderma was employed, because its species are difficult to distinguish from each other. We selected an appropriate oligonucleotide decamer, R28 (5'-ATGGATCCGC), determined the optimal cycles of PCR as 30 cycles, simplified the template preparation method, and determined optimal concentrations of the template and Taq DNA polymerase. We then examined 74 closely related strains of Trichoderma. The electrophoretic band patterns of the PCR products were compared. According to the statistical analysis with the phylogenetic analysis using parsimony (PAUP), the results were consistent with the morphological, physiological and ecological data on these strains. Therefore, we conclude that RAPD is a simple, efficient and reliable method for the selection of fungal strains employed in screening.

Base Sequence↗
PubMed1994

Application of the random amplified polymorphic DNA using the polymerase chain reaction for efficient elimination of duplicate strains in microbial screening. II. Actinomycetes.

We evaluated the random amplified polymorphic DNA (RAPD) method using Streptomyces lavendulae and Streptomyces virginiae strains to eliminate duplicate actinomycete strains in our microbial screening program. The RAPD data were compared with phenotypic characteristics, DNA relatedness, HPLC analysis of metabolites and low-frequency restriction fragment analysis by pulsed-field gel electrophoresis. These results were consistent with each other. Therefore, we conclude that RAPD is a simple, efficient, and reliable method for the selection of actinomycete strains.

Base Sequence↗
PubMed1994

Application of the random amplified polymorphic DNA using the polymerase chain reaction for efficient elimination of duplicate strains in microbial screening. III. Bacteria.

Random amplified polymorphic DNA (RAPD) analysis was evaluated for the selection and elimination of bacterial strains used in microbial screening. For this pilot study we used eight bacterial strains producing fragin and two Pseudomonas fragi strains, which are often isolated during the screening. A dendrogram constructed by the statistical analysis using parsimony, PAUP, based on the band patterns of RAPD with primer R28 was in good correlation with the results of DNA-DNA hybridization, HPLC analysis of metabolites, and conventional morphological and physiological characterization. RAPD was also applicable to a wide range of bacteria. This rapid selection system by RAPD was a very useful tool for excluding similar bacterial isolates encountered during screening.

Bacteria↗
PubMed1994

Adrenalectomy suppresses insulin secretion from pancreatic islets of ob/ob mice.

The aim of this work was to examine effects of adrenalectomy and intracerebroventricular injection of dexamethasone on insulin secretion from pancreatic islets of ob/ob mice. Female ob/ob and lean mice fed a stock diet were adrenalectomized at 5 wk of age and studied at 8-9 wks of age. Removal of the adrenal glands from ob/ob mice fed a stock diet normalized their plasma insulin concentration, islet size, and essentially normalized insulin secretion from islets incubated in 10 mM glucose. Insulin secretion from islets was, however, not fully normalized when the incubation buffer contained higher concentrations of glucose (20 mM), or acetylcholine, a potentiator of glucose-induced insulin secretion. Within 90 min after intracerebroventricular administration of dexamethasone plasma insulin concentrations were elevated and glucose-induced (10 mM) insulin secretion from isolated islets of adrenalectomized ob/ob mice increased, but dexamethasone was ineffective in lean mice. Regulation of insulin secretion from pancreatic islets of adrenalectomized ob/ob mice remains abnormal even though adrenalectomy normalized plasma insulin concentrations in these mice. Alterations in glucocorticoid-mediated, central nervous system regulation of insulin secretion likely contribute to hyperinsulinemia in ob/ob mice.

Adrenal Glands↗
PubMed1994

[The effect of priming dose of vecuronium on the diaphragm and the hypothenar muscle].

We studied the relaxation property of priming or precurarization vecuronium dose (0.015 mg.kg-1) on the diaphragm and the abductor digiti minimi muscle in 8 healthy patients undergoing elective surgery. Patients had control ventilation (PETCO2: 35 - 40 mmHg) by the laryngeal mask under "thiopental-fentanyl-oxygen" anesthesia. Supra-maximal single twitch stimulation with 1 Hz frequency was applied to right phrenic and ulnar nerves. Electromyographic response was recorded using NEC Synax ER1100 (NEC, Sanei, Tokyo, Japan) by surface electrodes in the 8 th intercostal space and the hypothenar. Time to maximum blockade at the diaphragm was 189 +/- 37 sec, compared with 314 +/- 39 at the abductor digiti minimi muscle (P < 0.01). This result suggests that we should be careful about the respiratory state of primed or precurarized patients with small dose of vecuronium such as 0.015 mg.kg-1 administration.

Adult↗
PubMed1994

Therapeutic strategy of nephrotic syndrome in patients over eighty.

In the present paper, we report four very elderly patients (80 years of age or older) with primary nephrotic syndrome. In all patients, oral prednisolone (PSL) alternative day therapy was attempted and three patients responded very well (complete remission 2, partial remission 1). However, one patient exhibited no effect of PSL and died from acute oliguric renal failure in spite of aggressive measures including hemodialysis. Fracture of the femoral neck occurred in one patient during PSL therapy, although the relationship between the fracture and PSL therapy was uncertain. In addition to our reported cases, 5 cases of nephrotic syndrome in similar patients reported elsewhere are analyzed together with our cohort. PSL was commonly effective in inducing remission in very elderly patients (7 of 9 patients; 78%). Very elderly patients with nephrotic syndrome frequently suffer from oliguric renal failure, which has a potentially high mortality. Based on these data, we conclude that PSL therapy can ameliorate primary nephrotic syndrome in patients over the age of eighty years. However, the complications both of the disease and its treatment, (e.g., acute oliguric renal failure, hip fracture) must be carefully monitored.

Acute Kidney Injury↗
PubMed1994

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

We investigated the utility of intraoperative peritoneal lavage smears and gastric wall brushing smears for diagnosis of peritoneal dissemination and serosal involvement during gastric cancer surgery. One hundred fifty-three patients with gastric cancer were examined; 138 who underwent gastric resection and 15 who did not. The incidence of cancer cell positivity determined by these methods was 8.0% in resected cases, and 80.0% in unresected cases. According to macroscopic serosal invasion, the incidence of positive cytology was 0% for S0, 15.4% for S1, 13.0% for S2, and 38.7% for S3. According to microscopic wall invasion, the incidence of positivity was 0% for m and sm, 6.3% for mp, 0% for ss, and 22.2% for se and si. In terms of macroscopic peritoneal dissemination, the incidence of positivity was 2.6% for P0, 28.6% for P1, 42.9% for P2, and 90.0% for P3. These results suggest that peritoneal lavage smears and gastric wall brushing smears are useful for predicting the spread of peritoneal dissemination. Thus, further study of intraoperative fast-smear cytology seems warranted.

Gastrectomy↗