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Biomedical subjects

Y Tahara

Publications and source records attributed to Y Tahara.

At least 73 records · Page 4Linked to original sources
PubMed1992

The response of glycated albumin to blood glucose change in the circulation in streptozotocin-diabetic rats--comparison of theoretical values with experimental data.

The contribution of the preceding blood glucose level to glycated protein was theoretically analyzed using a linear kinetic model and was compared with experiments using streptozotocin-diabetic rats. We assumed that the glycation process can be described by one irreversible step and that the fraction of glycated protein is small. A formula based on these two assumptions showed that the level of glycated protein was proportional to the weighted mean blood glucose concentration in the preceding period and that the weight function was determined by the metabolic characteristics of each protein. For assessing the usefulness of the present formula, the value calculated for the response of glycated albumin (GA) to acute blood glucose change in streptozotocin-diabetic rats was compared with the data obtained under three experimental conditions. The calculated responses of GA showed a little more retardation than the observed data, but showed enough agreement with them.

Animals↗
PubMed1992

A method for observing cross-sectional views of biomembranes.

Cross-sectional views of intact biomembranes and synthetic lipid bilayer membranes were observed by electron cryomicroscopy using spontaneous orientation of disk-shaped membranes; purple membrane, thylakoid membrane, synthetic phospholipid membrane and a microcrystalline sheet made of Er-binding polypeptide were observed. The membranes were observed fully hydrated, embedded in vitreous ice, and their self-orientation was most probably caused by repulsion between their hydrophobic edges and their hydrophilic environment which forced their edges to be exposed to the air-water interface. The cross-sectional profiles of the native biomembranes were asymmetric and characteristic, whilst those of the synthetic membranes were symmetric and predictable by a simple model. Simple Fourier analysis showed that the cross-sectional images retained structural information up to a medium resolution.

Amino Acid Sequence↗
PubMed1992

Analysis of early-phase insulin responses in nonobese subjects with mild glucose intolerance.

OBJECTIVE: To study the possible contribution of a B-cell defect in the development of glucose intolerance in nonobese subjects. RESEARCH DESIGN AND METHODS: There were 41 normal, nondiabetic subjects; 18 subjects with IGT; and 21 patients with NIDDM. All subjects were nonobese (BMI < 27 kg/m2). Insulin secretory responses to an OGTT, IVGTT, and GST were studied. RESULTS: Early-phase insulin responses to OGTT and IVGTT were decreased in subjects with IGT to levels comparable with those in NIDDM patients, whereas the response to GST was preserved in the subjects with IGT compared with NIDDM patients. The insulinogenic index of OGTT correlated well (r = 0.78) with early-phase insulin response to IVGTT, suggesting that the insulinogenic index in OGTT is related to the early-phase insulin response to IVGTT in nonobese subjects. CONCLUSIONS: Impaired early-phase insulin response to glucose was associated with mild glucose intolerance, suggesting the importance of impaired insulin secretion in the development of glucose intolerance in nonobese subjects.

Blood Glucose↗
PubMed1992

[Clinical characteristic of elderly patients with insulin-dependent diabetes mellitus].

The number of elderly patients with insulin-dependent diabetes mellitus (IDDM) is increasing because of the prolongation of life due to the improvement of diabetic control. For better management of elderly patients with IDDM, we investigated the clinical and genetic characteristic of older patients with IDDM in comparison with younger patients. The subjects studied consisted of 19 patients with IDDM treated at the Department of Geriatric Medicine, Osaka University Hospital. Among the 19 subjects, 7 patients (37%) were more than 50 years old, including 3 patients (16%) more than 65 years old. The clinical and genetic characteristics of these 7 patients (older patients group) were compared with those of 12 patients (younger patient group) whose age was less than 50 years old. The age at onset of IDDM was significantly higher in older patient group (46 +/- 13 years old; mean +/- SD) than in younger patient group (34 +/- 6 years old). There was no significant difference in the duration of IDDM between older and younger patients (13 +/- 6 and 12 +/- 8 years, respectively). There were no significant differences in daily insulin dose, glycemic control (fasting plasma glucose and HbA1c levels) and glycemic stability as measured by the standard deviation of 10 measured fasting plasma glucose levels between the two groups. The frequency of diabetic retinopathy and neuropathy in the older patients was slightly, but not significantly, higher than that in younger patients. The frequency of diabetic nephropathy was similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Inhibition of growth and pulmonary metastasis of B16-F10 murine melanoma by N-1554, a polyprenyl phosphate.

Antitumor effect of N-1554 (alpha-dihydrodecaprenyl phosphate containing eight trans internal isoprene residues) against B16-F10 melanoma in syngeneic C57BL/6 mice was examined. B16-F10 cells were inoculated into the footpad of mice and N-1554 was intraperitoneally administered after the inoculation. The drug significantly inhibited the tumor growth in the footpad and dramatically reduced the pulmonary metastasis from the tumor. The antitumor effect of N-1554 was almost abolished when the immunosuppressant carrageenan or anti-asialo GM1 antibody was administered to mice. In addition, pretreatment of host mice with N-1554 reduced the growth of subcutaneously inoculated B16-F10 melanoma. These results suggest that enhancement of host immune system may be involved in the antitumor effect of N-1554.

Animals↗
PubMed1991

Evaluation of the electrocardiographic transitional zone by cardiac computed tomography.

The relationship between shift of the transitional zone on the standard 12-lead electrocardiogram (ECG) and anatomical rotation of the heart in one plane was studied by cardiac computed tomography (CT). Based on the position of the transitional zone, 102 subjects were divided into 3 groups: the normal transitional zone (NT) group (31 subjects), clockwise rotation (CWR) group (30 subjects), and counterclockwise rotation (CCWR) group (41 subjects). The left-sided angle between the interventricular septum and horizontal axis of the body (the septal angle) was determined on the cardiac CT and compared among the three groups. The angle was 51.8 degrees +/- 6.8 degrees in the NT group, 38.2 degrees +/- 8.4 degrees in the CWR group, and 64.9 degrees +/- 10.4 degrees in the CCWR group. There were significant differences in the septal angle among the groups (p less than 0.05). The mechanism of CWR and CCWR could be attributed to the septal angle in about two-thirds of the cases (24/30 in CWR and 27/41 in CCWR). However, those not explained by the septal angle amounted to 6 (20%) of the CWR group and 14 (34%) of the CCWR group. Relatively higher positions of the precordial ECG leads, as observed in the vertical heart, appeared to be responsible for CWR in the 6 patients, and left septal fascicular block was suspected to be responsible for CCWR in the 14 patients. These data indicate that about two-thirds of CWR and CCWR can be explained by anatomical rotation of the heart in one plane around the long axis, but other factors appear to be responsible for such electrocardiographic findings in the remaining one-third of cases.

Adult↗
PubMed1991

Urinary C-peptide as an index of unstable glycemic control in insulin-dependent diabetes mellitus (IDDM)

In order to investigate whether urinary C-peptide (UCP) excretion can be a useful index of insulin-dependent diabetes mellitus (IDDM) with unstable glycemic control, UCP was measured in nine IDDM patients with unstable glycemic control, nine IDDM patients with stable glycemic control, and 12 non-insulin-dependent diabetic (NIDDM) patients treated with insulin. The UCPs in overnight urine (U1) and fasting single void urine (U2) in IDDM patients with unstable glycemic control were significantly lower than those in IDDM patients with stable glycemic control (U1: 0.03 +/- 0.03 vs 0.24 +/- 0.20 nmol/mmol-Creatinine, U2: 0.02 +/- 0.01 vs 0.20 +/- 0.20 nmol/mmol-Cr, mean +/- SD, both P less than 0.01). The UCPs in U1 and U2 in both groups of IDDM were significantly lower than those in NIDDM (U1: 0.97 +/- 0.52, U2: 0.73 +/- 0.41 nmol/mmol-Cr, both P less than 0.01). The UCPs in U1 and U2 significantly correlated with incremental C-peptide response to intravenous glucagon injection and with glycemic stability assessed by the standard deviation of 10 previous fasting plasma glucose levels. These results suggest that UCP reflects their residual insulin secretory capacity and that UCP can be a useful index which distinguishes patients with unstable IDDM from those with stable diabetes mellitus.

Adult↗
PubMed1991

Renal handling of glycated albumin in non-insulin-dependent diabetes mellitus with nephropathy.

Renal handling of glycated albumin in diabetic nephropathy was examined by studies on renal selectivity for glycated albumin in 23 normal controls and 52 patients with non-insulin-dependent diabetes mellitus (NIDDM) with various degrees of nephropathy. The serum and urinary levels of glycated albumin were measured by enzyme-immunoassay with monoclonal antibody to glucitol-lysine residues in human glycated albumin. The diabetic patients were divided into 3 groups according to the albumin index (AI): patients with normoalbuminuria [AI less than or equal to 30 mg/g creatinine(Cr)], with microalbuminuria (30 less than AI less than or equal to 270 mg/g Cr), and with macroalbuminuria (AI greater than 270 mg/g Cr). The renal selectivity for glycated albumin was calculated from the ratio of the urinary to serum level of glycated albumin. In the controls, the renal selectivity was as high as 4.40 +/- 0.48, and significantly higher than those in patients with normo- (2.87 +/- 0.29), micro- (1.72 +/- 0.20) and macroalbuminuria (1.26 +/- 0.23). The renal selectivity was inversely correlated with the AI in diabetic patients (r = -0.58, P less than 0.01). These data indicate that glycated albumin was selectively excreted in the urine and that the renal selectivity in diabetic patients gradually decreased to a value of 1 with increase in albuminuria. When the patients with normoalbuminuria were divided into two subgroups with high and low albumin excretion, the renal selectivities for glycated albumin in both subgroups were still significantly lower than that in controls. These results suggested that early diabetic nephropathy which cannot be detected clinically by albuminuria can be diagnosed by measurement of renal selectivity for glycated albumin.

Aged↗
PubMed1991

Phase image characterization of ventricular contraction in left anterior hemiblock.

We investigated whether or not left anterior hemiblock is present in patients with left axis deviation using first-harmonic Fourier analysis of gated blood-pool images. Gated blood-pool images were taken in 50 patients without contraction abnormality. They included 14 normal subjects, 8 patients with right bundle branch block (RBBB), 20 with left axis deviation (LAD) and 8 with both RBBB and LAD (RBBB + LAD). ECG gated blood-pool scans were acquired in the anterior and "best septal" left anterior oblique projections. First, the phase images were displayed cinematically as a continuous-loop movie. Next, for quantitative analysis of the phase image, the whole left ventricular and left ventricular high lateral regions of interest were drawn. The "regional phase shift" (RPS) was then defined as (RPS = A-a) where "A" is the mean value of the whole left ventricular phase angles and "a" is that of phase angles in the high lateral region. The left ventricular phase changes and the RPSs in the RBBB and LAD groups were similar to those in the normal group. In the RBBB + LAD group, the latest phase changes occurred in the high anterolateral region. The RPSs of this group were significantly lower than those in the other 3 groups (p less than 0.01). These data suggest that left anterior hemiblock might coexist with RBBB in patients with RBBB + LAD, whereas left anterior hemiblock might not exist in the majority of patients with LAD alone.

Bundle-Branch Block↗
PubMed1991

Evaluation with Fourier analysis on radionuclide angiography of viable but stunned myocardium in patients with right ventricular myocardial infarction.

Stunned myocardium of right ventricle was studied by radionuclide angiography (RNA) and Thallium myocardial scintigraphy (TL) in 39 patients with inferior myocardial infarction with and without right ventricular myocardial infarction (RVMI). RNA was performed within 1 week of the onset (acute phase) and after 1 month, when exercise cardiac scintigraphy (EX-TL) was also performed. The ejection fraction (EF) of each ventricle calculated from RNA and the phase and amplitude evaluated visually and quantitatively by Fourier analysis were compared between the acute phase and 1 month after the onset of myocardial infarction. The degree of visualization of right ventricle was examined in EX-TL 1 month after the onset. (1) In RNA obtained in the acute myocardial infarction, abnormalities in the right ventricle (delayed phase or low amplitude image) were observed in 18 (46%) but not in 21 (54%) of the 39 patients (N group). Of those 18 patients, the abnormalities in the right ventricle alleviated in 11 (RVMI-A group) but persisted in 7 (RVMI-B group) in RNA obtained 1 month after the onset. (2) In the acute phase, the right ventricular ejection fraction (RVEF) was 39.4 +/- 10.4% in N group, 30.8 +/- 5.3% in RVMI-A group, and 29.6 +/- 8.9% in RVMI-B group, with significant differences between N group and the other two groups (P less than 0.05) but no significant difference between RVMI-A and RVMI-B groups. (3) After 1 month, RVEF was 40.1 +/- 10.1% in N group, 42.2 +/- 8.4% in RVMI-A group, and 32.2 +/- 9.8% in RVMI-B group, being improved in RVMI-A group and showing a significant difference as compared with RVMI-B group (p less than 0.05). (4) In EX-TL of RVMI-A group, the right ventricle was visible although the uptake of TL was reduced in the entire right ventricle. In RVMI-B group, only part of the right ventricular free wall was visible with defects in the other areas of right ventricle. The sign of RVMI showed improvements in many of the patients after the acute phase, and their condition was considered to have been so-called stunned myocardium, which is a complex of symptoms of reversible myocardial ischemia, rather than RVMI.

Aged↗
PubMed1991

[Assessment of denervated but viable myocardium in patients with myocardial infarction--by myocardial imaging with 201Tl and 123I-MIBG].

The present study assessed sympathetic function in viable infarcted areas of the myocardium following the onset of myocardial infarction. The subjects were 19 patients with myocardial infarction. After exercise on a bicycle ergometer, simultaneous SPECT with Tl-201 and I-123 MIBG was performed. The behavior of MIBG following exercise remains to be clarified, but in the present study MIBG provided images different from those obtained with Tl. While the redistribution of Tl in the infarcted area was observed in 8 of 19 patients, MIBG was absent in the infarcted area in both the initial and delayed scans. In the patient undergoing CABG, the infarcted area showed no MIBG despite the normal perfusion of Tl. The previous proposal that the redistribution of Tl indicates myocardial viability to some extent suggests that the sympathetic function of the area of the myocardium showing the redistribution of Tl decreases even though the area is viable. These findings indicate that after the onset of myocardial infarction, there is a denervated but viable area in the myocardium, despite the viability demonstrated by Tl imaging. They also indicate that concurrent myocardial imaging with MIBG is useful for the detection of such a myocardium.

3-Iodobenzylguanidine↗
PubMed1990

Role of protein kinase C in the regulation of glucagon gene expression by arginine.

The cellular mechanism of glucagon gene expression in intact rat islets and their synthesis and release of glucagon were investigated. Arginine significantly increased the amounts of preproglucagon mRNA and glucagon in the islets and glucagon release. H-7, a specific inhibitor of protein kinase C (PKC), significantly inhibited these effects of arginine. However, H-8, a potent inhibitor of cyclic nucleotide-dependent protein kinases, did not affect the arginine-induced biosynthesis of glucagon or glucagon release. These results suggest that the regulation of glucagon gene expression by arginine is mediated by PKC, not by cyclic nucleotide-dependent protein kinases.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Suppression of synthesis and release of glucagon by glucagon-like peptide-1 (7-36 amide) without affect on mRNA level in isolated rat islets.

Glucagon-like peptide-1 (GLP-1) has been reported to inhibit glucagon release. To investigate the mechanism involved, we examined the effects of GLP-1 on the preproglucagon mRNA level and the content and release of glucagon in the isolated rat islets. Arginine significantly increased the content and release of glucagon after incubation for 1 h or 18 h. The preproglucagon mRNA level was not increased after incubation for 1 h but was increased after incubation for 18 h. GLP-1 (7-36 amide) significantly decreased the content and release of glucagon after incubation for 1 h or 18 h, but did not affect arginine-induced increase in the preproglucagon mRNA level after incubation for 18 h. These data suggest that GLP-1 suppresses post-transcriptional processes in the content and release of glucagon.

Animals↗
PubMed1990

Aspartic acid at position 57 of the HLA-DQ beta chain is not protective against insulin-dependent diabetes mellitus in Japanese people.

Insulin-dependent diabetes mellitus (IDDM) in Caucasians is closely associated with the HLA-DQ gene, especially the residue 57 of the DQ beta chain. Aspartic acid at this position provides protection against IDDM, and substitution of this residue by alanine, valine or serine increases susceptibility to IDDM. To determine whether this is a common feature of IDDM in different ethnic groups, we studied DQB1 DNA in Japanese patients with IDDM by polymerase chain reaction and non-radioactive restriction site analysis. In contrast to Caucasian patients with IDDM, most Japanese patients with IDDM possessed at least one aspartic acid at position 57 of DQ beta. This finding strongly suggests that aspartic acid at position 57 of DQ beta does not protect the Japanese from IDDM.

Amino Acids↗
PubMed1990

Metabolism of intravenously administered maltose in renal tubules in humans.

To investigate how urinary excretion rates (UERs) of maltose and glucose are determined after intravenous maltose infusion, maltose and glucose solutions were infused at various rates and the relationships between UERs of maltose and glucose and their plasma concentrations were examined. Results showed the existence of a threshold plasma maltose concentration for the urinary excretions of maltose and glucose and the existence of a maximum rate of urinary glucose excretion after maltose infusion. Elevation of plasma glucose concentration by simultaneous glucose infusion increased urinary glucose excretion but did not increase urinary maltose excretion; the relationship between plasma total sugar concentration and urinary total sugar excretion was unchanged. Results suggest that maltose administered intravenously is hydrolyzed to glucose by maltase in renal tubules and reabsorbed as glucose competitively with glucose derived from plasma and that the maximum utilization of intravenously infused maltose is determined by the tubular glucose reabsorption capacity.

Adult↗
PubMed1990

Autoimmune neutropenia with anti-neutrophil autoantibody associated with Sjögren's syndrome.

A 74-year-old man developed neutropenia in association with Sjögren's syndrome. The peripheral neutrophils in his blood decreased to 210/mm3 (total white blood cell count 2,100/mm3). Bone marrow examination showed an increase in the number of neutrophil precursors. The presence of anti-neutrophil autoantibody (ANAB) in his plasma was determined by an enzyme-linked immunosorbent assay. Prednisolone therapy resulted in an increase in the neutrophil count and a decrease in the ANAB titer. However, when the daily dose of prednisolone was decreased, the neutrophil count gradually decreased, and the ANAB titer increased again. These results suggest that neutropenia in this patient was caused by ANAB, and ANAB could be the result of autoimmune disorders associated with Sjögren's syndrome.

Aged↗
PubMed1990

[Usefulness of rest-redistribution on thallium myocardial scintigraphy in patients with acute myocardial infarction by SPECT: analysis by bull's eye and unfolded map images].

The purpose of this study was to clarify the clinical significance of rest-redistribution in myocardial scintigraphy (SPECT) in acute myocardial infarction (AMI). Thirty patients with AMI within one week after the onset of attack were studied. SPECT images were obtained 10 min and three hours after injection of 201Tl. Bull's eye images and unfolded map images were prepared. A 201Tl uptake was studied at the infarct and non-infarct sites. Exercise SPECT and radionuclide angiography (RNA) were performed in all patients one month after the onset of AMI, and the findings were compared with clinical and coronary angiographic (CAG) findings. 1. Redistribution of thallium at rest was observed at the infarct sites in nine of the 30 patients. 2. Redistribution at rest was observed at the non-infarct sites in eight patients. 3. Redistribution at rest was observed during exercise SPECT one month after the onset of AMI in patients with redistribution at rest in the acute phase. 4. In patients with redistribution at rest at the infarct site, left ventricular ejection fraction (EF) improved one month after the onset of AMI (delta EF greater than 5%), but it decreased slightly during exercise. 5. Wall motion at the infarct site was not much impaired in patients who showed redistribution at rest at the infarct site. 6. Angina pectoris and recurrence of myocardial infarction were observed more frequently in those with redistribution at rest on SPECT. 7. No characteristic findings were obtained on CAG in those with redistribution at rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗