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T Tamura

Publications and source records attributed to T Tamura.

At least 541 records · Page 30Linked to original sources
PubMed1995

Effect of high-fat diet on the gene expression of pancreatic GLUT2 and glucokinase in rats.

To define the biochemical and molecular basis of high-fat diet to reduce insulin secretion, the present study examined the effect of high-fat diet on the gene expression of pancreatic GLUT2 and glucokinase. Rats were isoenergetically meal-fed a high-fat or a high-carbohydrate diet for 10 weeks. Plasma glucose concentration was higher, whereas insulin concentration was lower in the rats fed a high-fat diet than in the rats fed a high-carbohydrate diet. The level of GLUT2 and glucokinase mRNA in pancreas was significantly decreased in the rats fed a high-fat diet compared with a high-carbohydrate diet. The rates of reduction in plasma insulin level, pancreatic gene expression of GLUT2 and glucokinase by high-fat feeding were about 50%. These results suggest that high-fat feeding impairs signal transduction mechanism in pancreatic beta-cells to reduce insulin secretion in rats.

Animals↗
PubMed1995

Repeat embolization of the side branch of the internal mammary artery graft by gelatin sponge particles and micro coils.

The internal mammary artery (IMA) is increasingly used as a coronary bypass conduit because of better long-term patency and improved prognosis as compared with venous grafts. Previous investigators have suggested that the "steal" of blood flow of the IMA graft via the subclavian artery or a persistent large side branch of the graft may lead to its thinning. However, only a few reports have described the embolization of a large side branch using a transcatheter procedure. We present a case of repeated embolization of a large lateral costal side branch of the left internal mammary arterial graft applying gelatin sponge particles and micro coils, as well as angioplasty to the graft conduit, with resulting easing of chest pain.

Aged↗
PubMed1995

Intracoronary stenting of a coronary occlusion resulting from an aortic dissection.

Acute myocardial infarction secondary to aortic dissection may occur due to compression of the coronary arteries by a hematoma or extension of the dissection into the coronary arterial wall. We report a patient with this condition who was successfully treated by Palmaz-Schatz stenting, providing an alternative to thrombolysis or angioplasty.

Aortic Dissection↗
PubMed1995

Myocardial damage after successful thrombolysis is associated with the duration of ST re-elevation at reperfusion.

The purpose of this study was to investigate the significance of ST re-elevation at reperfusion using strict criteria for patient inclusion and exclusion. Twenty-nine patients who had a first anterior infarction with single-vessel disease, successful recanalization by intracoronary thrombolysis (ICT) with urokinase, and an angiographically confirmed patent infarct-related artery after 4 weeks, were divided into three groups according to the deviation of the ST segment at reperfusion: Group A, 10 patients with sustained ST re-elevation; Group B, 10 patients with transient ST re-elevation; and Group C, 9 patients with ST reduction. Left ventricular (LV) function was evaluated from cineventriculograms performed in the 30 degrees right anterior projection 4 weeks after ICT. LV ejection fraction and regional wall motion of the infarct area, evaluated by the centerline method (SD/chords), were significantly lower in Group A (44 +/- 10%, -3.2 +/- 0.4) than in Group B (61 +/- 9%, -1.9 +/- 0.7) and Group C (60 +/- 5%, -2.0 +/- 0.4) (p < 0.01). Peak creatine kinase (CK) activity was significantly higher in Group A (5848 +/- 2112 IU) than in Group B (2485 +/- 1254 IU) and Group C (1889 +/- 1525 IU) (p < 0.05). These data suggest that a sustained ST re-elevation at reperfusion was strongly associated with marked LV dysfunction and higher peak CK activity. It was concluded that sustained, not transient, ST re-elevation associated with successful reperfusion indicates extensive myocardial damage.

Aged↗
PubMed1995

Endogenous bone-resorbing factors in estrogen deficiency: cooperative effects of IL-1 and IL-6.

Estrogen deficiency causes a marked bone loss by stimulating osteoclastic bone resorption. To explore the endogenous bone-resorbing factors involved in estrogen deficiency, we examined the bone-resorbing activity present in the supernatant fraction of mouse bone marrow collected from ovariectomized (OVX) mice. Adding bone marrow supernatants at 20-80% to organ cultures of mouse long bones dose-dependently stimulated bone resorption. The endogenous bone-resorbing activity present in bone marrow supernatants from OVX mice was much higher than that from sham-operated mice 2-4 weeks after surgery, and it was significantly diminished by indomethacin in vitro. Anti-IL-1 alpha antibody completely neutralized the bone-resorbing activity present in bone marrow supernatants from OVX mice. Antibodies against IL-1 beta, IL-6, and IL-6 receptors also neutralized it, but partially. The concentration of IL-1 alpha measured by ELISA was much higher in bone marrow supernatants than in sera, but it was not appreciably changed before or after OVX. The concentration of IL-1 beta in bone marrow supernatants from OVX mice was less than the detection limit. OVX stimulated IL-1 activity in bone marrow supernatants measured by means of the proliferation of thymocytes. However, the level of IL-1 alpha present in bone marrow supernatants from OVX mice was insufficient to stimulate bone resorption. Compared with the serum concentration, bone marrow supernatants contained a much higher level of IL-6 as well, and it was further increased by OVX. However, IL-6 alone present in bone marrow supernatants from OVX mice again did not stimulate bone resorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Demonstration of endothelin (ET) receptors on cultured rabbit chondrocytes and stimulation of DNA synthesis and calcium influx by ET-1 via its receptors.

Endothelin (ET) receptors on chondrocytes were demonstrated using cultured rabbit costal chondrocytes. After crosslinking the receptors on the cells with 125I-ET-1, two major bands of 43 kDa and 46 kDa were separated by SDS-PAGE. Scatchard analysis demonstrated two classes of ET receptors with Kd values of 1 x 10(-10) M and 5 x 10(-9) M. The numbers of high- and low-affinity receptors were 1 x 10(4) and 2 x 10(5) per cell, respectively. The binding of ET-1 to chondrocytes was increased by treatment with PTH, DBcAMP, TGF-beta 1, IL-1 beta, RA and EGF. ET-1 stimulated DNA synthesis in cultured rabbit chondrocytes. ET-1 also stimulated calcium incorporation through the cell membrane of chondrocytes. These findings indicate that ET-1 has a physiological effect on chondrocytes via its receptors on the cells.

Animals↗
PubMed1995

Changes in localization of ovarian immunoreactive estrogen receptor during follicular development in hens.

The aim of this study was to examine the changes of ovarian estrogen receptor (ER) localization in hens to determine the significance of estrogen-ER interactions for the regulation of follicular functions during their development. The ER was localized by immunocytochemistry in the various developmental and regressing stages of follicles, namely cortical and white follicles, the largest (F1, matured follicle) and third largest preovulatory follicles (F3, rapid growth phase follicle), and post-ovulatory follicles (POF). No immunoreaction for ER was observed in the cortical follicles, whereas the interstitial cells in the outer theca externa were ER positive in white follicles. The islets of epithelial cells (identical to estrogen producing cells) in the outer theca externa and granulosa cells were ER positive in F3 follicles. These ER immunoreactions observed in F3 follicle were remarkably reduced in F1 and POF. These results suggest that estrogen-ER interactions may be responsible for the follicular growth, and the loss of ER may be involved in the mechanism of follicular maturation. The estrogen-ER interactions may be also involved in the local control of the steroid production in follicles.

Animals↗
PubMed1995

The influence of ageing on cisplatin pharmacokinetics in lung cancer patients with normal organ function.

This study was performed to identify any relationship between age and cisplatin (CDDP) pharmacokinetics in lung cancer patients. CDDP was given at a dose of 80 mg/m2 by 1-h intravenous infusion to 23 lung cancer patients. All patients had normal renal, hepatic, and bone marrow functions. We measured ultrafilterable platinum (U-Pt) and total plasma platinum (T-Pt) using atomic absorption spectrometry. There was significant correlation between the age of the patients and U-Pt pharmacokinetic parameters such as the area under the plasma concentration versus time curve (AUC), total clearance (Cl), and peak plasma concentration (Cmax) as well as the AUC of T-Pt (P < 0.05). We performed univariate regression analysis to examine the influence of factors aside from age on the AUC of U-Pt and T-Pt. Creatinine and GPT levels were significantly related to the AUC of U-Pt, and creatinine clearance and creatinine concentrations were significantly related to the AUC of T-Pt. Therefore, stepwise multiple-regression models for the AUC of U-Pt and T-Pt were developed to assess an age effect. Age was consistently an independent and significant predictor of the AUC of U-Pt and T-Pt.

Adult↗
PubMed1995

Influence of tyrosine residues Y705 and Y807 on the transforming potency of the v-fms oncogene product of feline sarcoma virus.

Cell transformation is characterized by overt changes in growth control and cell morphology. To study the role of tyrosine residues Y705 and Y807 of v-Fms of the McDonough strain of feline sarcoma virus in cell transformation we replaced them individually with phenylalanine residues. Cells expressing the mutant genes showed mitogenic properties similar to wild-type v-Fms transformed cells. However, the morphology of cells expressing the Y807F mutant remained the same as nontransformed cells. Four phosphoproteins of 190, 120, 55 and 50 kDa were detected in cells expressing the wild-type but were absent in cells expressing the mutant Y807F-v-fms gene.

Base Sequence↗
PubMed1995

HLA-DRB1*1502 allele, subtype of DR15, is associated with susceptibility to ulcerative colitis and its progression.

HLA-DRB1 allele typing was performed by the PCR-RFLP method on 59 ulcerative colitis (UC) patients and 136 healthy controls. Phenotypic frequencies of HLA-B52 and DR2 were significantly increased among the UC patients, serologically. DNA typing of HLA-DRB1 revealed that the genotypic frequency of DRB1*1502 was higher in UC than in the controls (49.2% vs 17.6%; P < 0.0001). In the analysis of clinical parameters, 82.8% of patients bearing DRB1*1502 were treated with corticosteroids. DRB1*1501 and DRB1*1502 differ in only one amino acid at residue 86 (valine vs glycine), and 66% of the UC patients carried two glycines at position 86 in the HLA-DR beta-chain (vs 51% of control; P < 0.05). These observations suggest that the presence of Gly-86 in the HLA beta-chain and surrounding amino acid sequence of HLA-DRB1*1502 is strongly associated with susceptibility to UC.

Adolescent↗
PubMed1995

A re-evaluation of the prolactin-releasing activity of growth hormone-releasing hormone in acromegaly in vivo.

In 1985, Losa et al reported that an i.v. bolus injection of GH-releasing hormone (GHRH) was able to paradoxically stimulate PRL secretion in more than half of their acromegalic patients. However, this observation was not generally accepted since several other investigators have concluded that such an anomalous PRL response to GHRH was an extremely rare phenomenon in acromegaly. Therefore, in this study we examined a large number (51 patients) of active acromegalics in order to obtain more reliable data on the incidence of the paradoxical PRL response to GHRH in this disorder. Each patient underwent i.v. bolus injections of GHRH (100 micrograms) and thyrotropin-releasing hormone (TRH, 500 micrograms) on separate days, and plasma levels of GH and PRL were measured. The plasma PRL response to GHRH was considered positive (a paradoxical increase) when an increase over baseline of at least 50% occurred. We found that only 6 patients (12%) showed a positive PRL response to GHRH. These PRL-responders to GHRH had higher GH responses to this peptide than PRL-non-responders to GHRH. Although PRL-responders and non-responders to GHRH had a similar PRL responsiveness to TRH, the GH response to TRH was lower in PRL-responders to GHRH than PRL-non-responders to this peptide. In addition, PRL-non-responders to GHRH had lower basal GH and higher basal PRL levels than PRL-responders to GHRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1995

Clinical significance of the growth hormone response to vasoactive intestinal peptide and gonadotropin-releasing hormone in acromegaly.

GH-secreting pituitary adenomas causing acromegaly can be classified into at least two types, i.e. the lactotroph-like adenoma and somatotroph-like adenoma. From a functional point of view, the lactotroph-like adenoma is characterized by positive GH responses to TRH and bromocriptine (Br) with a GH increase or decrease, respectively, whereas the somatotroph-like adenoma is characterized by a high GH response to GHRH and a low GH response to TRH and Br. In this study, we examined whether the loading of vasoactive intestinal peptide (VIP) and GnRH, another hypothalamic hormone capable of stimulating GH secretion in acromegaly, have a pathophysiological significance as TRH, GHRH, and Br tests. In 52 patients with active acromegaly, we performed iv bolus injections of TRH (500 micrograms), GHRH (100 micrograms), VIP (100 micrograms), and GnRH (100 micrograms), and a peroral administration of Br (2.5 mg), in order to compare the GH responses to these loads. There was a significant correlation that the higher was the GH response after TRH the greater was the GH decrease after Br. Although statistically insignificant, there was a trend (0.05 < p < 0.1) that the higher was the GH response after GHRH the smaller was the GH decrease after Br. In addition, as novel findings, we observed that the GH responses to GHRH, VIP, and GnRH were in significant positive correlations to each other, and that the higher were the GH responses after VIP and GnRH the smaller was the GH decrease after Br. In agreement with this, we also found that a simultaneous GH responsivity to VIP and/or GnRH in TRH-responsive acromegalics significantly enhanced the GH response to GHRH and lowered the Br responsiveness compared to the data of pure TRH-responders. From these results, we hypothesize that the positive GH responsiveness to VIP and GnRH, like that to GHRH, may be a feature of the somatotroph-like pituitary adenoma causing acromegaly. The present results appear to be of some help in understanding the basis of the great variabilities in the GH responses to various dynamic testings in acromegaly.

Acromegaly↗
PubMed1995

Early and late results of repair of tetralogy of Fallot with subarterial ventricular septal defect. A comparative evaluation of tetralogy with perimembranous ventricular septal defect.

Between November 1966 and December 1990, 511 pediatric patients with tetralogy of Fallot underwent corrective operation at Tenri Hospital. There were 78 patients with subarterial ventricular septal defect. Mean age at repair was 5.6 +/- 3.3 years. The method of right ventricular outflow tract reconstruction was simple infundibulectomy in 14 patients, right ventricular ventricular outflow patch in 36, and transannular patch in 28. There were 7 (9.0%) early deaths as a result of low cardiac output syndrome and acute renal failure. The pressure ratio of the right ventricle to the left ventricle was 0.62 +/- 0.18 during the early postoperative catheterization. Follow-up was achieved for 442.6 patient-years and ranged from 0.5 to 27 years, with an average of 8.5 +/- 6.7 years. There were three late deaths (2 cardiac and 1 noncardiac). Actuarial survival was 94.8% +/- 4.0% at 20 years. Catheterization during late follow-up (6.8 +/- 4.7 years after repair) was done in 53 patients and the pressure ratio of the right ventricle to the left ventricle was 0.48 +/- 0.21. Fifteen patients underwent subsequent operation because of residual lesions, including ventricular septal defect in four patients, pulmonary stenosis in nine, combined ventricular septal defect and pulmonary stenosis in one, and pulmonary regurgitation in one, with no mortality. Actuarial rate of freedom from reoperation was 71.1% +/- 8.0% at 10 years and 58.8% +/- 16.8% at 20 years. Patients with tetralogy and subarterial ventricular septal defect were more likely to have the development of residual obstruction at the level of the pulmonary valve anulus after repair than were those with tetralogy and perimembranous ventricular septal defect.

Abnormalities, Multiple↗
PubMed1995

Characterization of guanylate cyclase activity in single retinal rod outer segments.

cGMP mediates vertebrate phototransduction by directly gating cationic channels on the plasma membrane of the photoreceptor outer segment. This second messenger is produced by a guanylate cyclase and hydrolyzed by a light-activated cGMP-phosphodiesterase. Both of these enzyme activities are Ca2+ sensitive, the guanylate cyclase activity being inhibited and the light-activated phosphodiesterase being enhanced by Ca2+. Changes in these activities due to a light-induced decrease in intracellular Ca2+ are involved in the adaptation of photoreceptors to background light. We describe here experiments to characterize the guanylate cyclase activity and its modulation by Ca2+ using a truncated rod outer segment preparation, in order to evaluate the enzyme's role in light adaptation. The outer segment of a tiger salamander rod was drawn into a suction pipette to allow recording of membrane current, and the remainder of the cell was sheared off with a probe to allow internal dialysis. The cGMP-gated channels on the surface membrane were used to monitor conversion of GTP, supplied from the bath, into cGMP by the guanylate cyclase in the outer segment. At nominal 0 Ca2+, the cyclase activity had a Km of 250 microM MgGTP and a Vmax of 25 microM cGMP s-1 in the presence of 1.6 mM free Mg2+; in the presence of 0.5 mM free Mg2+, the Km was 310 microM MgGTP and the Vmax was 17 microM cGMP s-1. The stimulation by Mg2+ had an EC50 of 0.2 mM Mg2+ for MgGTP at 0.5 mM. Ca2+ inhibited the cyclase activity. In a K+ intracellular solution, with 0.5 mM free Mg2+ and 2.0 mM GTP, the cyclase activity was 13 microM cGMP s-1 at nominal 0 Ca2+; Ca2+ decreased this activity with a IC50 of approximately 90 nM and a Hill coefficient of approximately 2.0.

Animals↗
PubMed1995

Endometrial oestrogen and progesterone receptors and their relationship to sonographic endometrial appearance.

The present study was undertaken to evaluate a possible relationship between the endometrial concentrations of oestrogen receptor (ER) or progesterone receptor (PR), and the sonographic appearance of human endometrium. Sonographic assessments and aspirations of the endometrium at the time of or prior to ovulation were made in 48 cycles of 45 infertile women. Endometrial patterns were classified as A, triple line pattern, or B, not triple line, on the basis of echogenicity. We did not find a correlation between ER or PR and serum oestradiol or endometrial thickness. Furthermore, serum oestradiol concentrations were not correlated with endometrial pattern or thickness. The only significant correlations were found between the concentrations of ER and PR in the pattern A endometrium (r = 0.80, P < 0.01) and in the pattern B endometrium (r = 0.49, P < 0.05). There were no differences in the mean concentrations of ER and PR despite differences in endometrial pattern and thickness. However, PR was measured at > 800 fmol/mg protein in 12 out of 38 pattern A endometria, while PR was < 800 fmol/mg protein in all pattern B endometria. These data suggest that high PR expression in the pre-ovulatory period is related to an adequate endometrial growth and thereby increases the responsiveness of the endometrium to progesterone stimulation after ovulation.

Buserelin↗