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Biomedical subjects

M Iwase

Publications and source records attributed to M Iwase.

At least 199 records · Page 11Linked to original sources
PubMed1988

Residual B cell function in patients with long-standing NIDDM and its relation to metabolic control and diabetic complications.

We have evaluated the residual pancreatic B cell function by glucagon load test in 28 patients with non-insulin-dependent diabetes mellitus (NIDDM) of a duration of 20 years or more. The increase in serum C-peptide at 6 minutes after glucagon administration (delta C-peptide) was used as an index of residual B cell function. There was much less delta C-peptide in patients treated with insulin than in those treated with sulfonylurea (p less than 0.05), and it was significantly correlated with the body mass index (r = 0.40, p less than 0.05). Long term metabolic control assessed by the average annual mean fasting blood glucose for the observation period (mean, 21 years) was not correlated with delta C-peptide (r = -0.13). The prevalence of retinopathy which needed photocoagulation therapy and of neuropathy in patients with poor residual B cell function (delta C-peptide less than or equal to 0.3 ng/ml) was the same as that in those with good residual B cell function (delta C-peptide greater than or equal to 1.0 ng/ml). The present study shows that the residual B cell function is not correlated with long term glycemic control and the prevalence of diabetic complications in long-standing NIDDM patients.

Adult↗
PubMed1988

Effects of high-frequency inflation (HFI) on expiratory activity.

It has been reported that triangular-shaped positive pressure pulses applied to the airway (high-frequency inflation, HFI) stimulates pulmonary stretch receptors and prolongs expiratory duration. In the present experiment, changes in the integrated curve of expiratory activity induced by HFI were investigated. Duration until the onset of the expiratory activity (E1 stage) was unchanged. In the E2 stage, the initial ascending slope became steeper and higher peaks were reached during HFI stimulation. The period from the onset of the slope to the peak, previously designated the stage of active expiration (Ea stage), showed no consistent change in duration and remained unchanged on average. The period after the peak until the onset of the following inspiratory activity was consistently prolonged. This period was designated the declining stage of expiration (Ed stage).

Afferent Pathways↗
PubMed1988

[Echocardiographic findings in a case of Fabry's disease with aortic regurgitation and complete AV block, and in his family members].

A 46-year-old man with Fabry's disease having aortic regurgitation and complete atrioventricular (AV) block was presented. In spite of severe aortic regurgitation (Seller's grade 3/4), his two-dimensional (2-D) echocardiogram revealed increased thickness of the left ventricular wall with mild dilatation. The myocardial echo showed a fine granular sparkling texture suggesting phospholipid deposition in the myocardial tissue. The membranous portion of the interventricular septum was thickened, and the aortic valve was thickened and had imperfect coaptation. Endomyocardial biopsy of the right side of the interventricular septum revealed intramyocardial vacuolization by light microscopy. Electron microscopy confirmed the presence of myelinoid lamellar inclusion. Electrophysiologic examination revealed an intra-Hissian AV block. A DDD pacemaker was implanted and the patient's symptoms were improved. Valvular replacement was not attempted due to the danger of suture failure. The patient's brother (41-year-old) also had increased thickness of his left ventricular wall on echocardiography, and a complete AV block by ECG, but no valvular abnormalities. His sister (45-year-old) had increased thickness of the left ventricular wall on echocardiography, and negative T waves by ECG, but she had no cardiac symptoms. The possibility of cardiac involvement in this heterozygous woman with Fabry's disease should also be considered. The patient's 38-year-old sister and all the children of all family members had normal left ventricular wall thicknesses and normal ECG. These findings may correspond to the age-related disease severity. The possibility of cardiac abnormalities should be considered in heterozygous women with Fabry's disease.

Adult↗
PubMed1987

Cross-correlation between vagal afferent impulses from pulmonary mechanoreceptors and high-frequency inflation (HFI) and deflation (HFD) in rabbits.

The effects of high-frequency airway inflation (HFI) and high-frequency airway deflation (HFD) generated by a triangular pressure pulse generator on pulmonary mechanoreceptors were examined. The cross-correlograms between vagal afferent impulses from the slowly adapting (SAR) and the rapidly adapting receptors (RAR) and the HFI or the HFD pulses were analysed. HFI stimulated SAR and RAR and HFD stimulated RAR, but inhibited SAR. The time lag of the mode in the correlogram between SAR and HFI was shorter than that of the mode in the correlogram between RAR and HFI. The span of the mode and the trough of SAR was shorter than the span of the mode of RAR. This may indicate that the time to peak of the generator potential of RAR is longer than that of SAR.

Adaptation, Physiological↗
PubMed1987

Diabetes induced by neonatal streptozotocin treatment in spontaneously hypertensive and normotensive rats.

The development of non-insulin-dependent diabetes mellitus (NIDDM) induced by neonatal streptozotocin (STZ) treatment was compared between male spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). The animals were intraperitoneally given 37.5, 50.0, 62.5, or 75.0 mg/kg of STZ at two days of age. At two days after STZ injection, plasma glucose was elevated in both groups of rats according to the dose of STZ, but the level was higher in SHR than in corresponding WKY. At ten days of age, plasma glucose in WKY returned to the similar level to that in vehicle-treated control irrespective of the doses of STZ, while in SHR it remained above control and its level was significantly higher than that in WKY. At 12 weeks of age, plasma glucose was within the control range in WKY, while in SHR it was markedly and dose-dependently elevated. The present study indicates that SHR are susceptible to NIDDM induced by neonatal STZ treatment. The difference in response to STZ between SHR and WKY was discussed.

Aging↗
PubMed1987

Sex differences in diabetes induced by neonatal streptozotocin treatment in spontaneously hypertensive rats.

We examined the sex differences in the development of diabetes due to neonatal streptozotocin (STZ) treatment in spontaneously hypertensive rats (SHR) which are more prone to diabetes than normotensive rats. Male and female SHR were intraperitoneally injected with various doses of STZ at 2 days after birth. In those treated with vehicle or 25 mg/kg of STZ, there were no sex differences in plasma glucose levels, which changed little during the 12 weeks of observation. When treated with 50 mg/kg of STZ, however, male SHR developed overt hyperglycemia greater than 300 mg/dl plasma glucose after 8 weeks of age, while females showed a minimal change in plasma glucose levels. When given 75 mg/kg of STZ, female rats developed overt hyperglycemia at 4-6 weeks of age, during which time male SHR showed no apparent hyperglycemia. At 8 weeks or later, however, both males and females had similarly high levels of plasma glucose. Glycosylated hemoglobin at 12 weeks was compatible with plasma glucose levels in each group. The present results indicate that there are sex differences in susceptibility to neonatal STZ treatment and in development of hyperglycemia.

Aging↗
PubMed1987

Effects of diltiazem on left ventricular diastolic behavior in patients with hypertrophic cardiomyopathy: evaluation with exercise pulsed Doppler echocardiography.

To estimate the effects of diltiazem on the left ventricular diastolic abnormalities in patients with hypertrophic cardiomyopathy, transmitral flow velocity during diastole was studied before and immediately after dynamic leg exercise with the pulsed Doppler technique combined with two-dimensional echocardiography. Seventeen patients with hypertrophic cardiomyopathy and 24 apparently healthy men performed bicycle ergometer exercise in the supine position with the target heart rate set at 120 beats/min. The patients with cardiomyopathy were directed to perform the exercise at the same intensity after receiving 30 to 60 mg of diltiazem, three times daily, for 1 or 2 weeks. The pattern of transmitral flow velocity in diastole had two components, one corresponding to the rapid filling phase in early diastole and the other to the atrial contraction phase in late diastole. To assess left ventricular diastolic behavior, the following variables were analyzed: peak velocity in the rapid filling and atrial contraction phases, the ratio of peak velocity in the atrial contraction phase to that in the rapid filling phase, and pressure half-time. The changes in peak velocity in the atrial contraction phase, pressure half-time and the ratio of peak velocity in the atrial contraction phase to that in the rapid filling phase with exercise differed significantly between patients with hypertrophic cardiomyopathy with no medication and control subjects. After diltiazem, the response of these variables to exercise was almost identical in the two groups. These results suggest that diltiazem can lessen the left ventricular diastolic abnormality in patients with hypertrophic cardiomyopathy on dynamic exercise of mild intensity.

Adult↗
PubMed1987

Blood pressure changes in spontaneously hypertensive and normotensive rats with neonatal streptozotocin induced type 2 diabetes.

We examined the blood pressure changes in hypertensive and normotensive rats with Type 2 diabetes induced by neonatal streptozotocin (STZ) treatment. STZ was intraperitoneally injected at 2 days of age with the dose of 25, 50 and 75 mg/kg for male spontaneously hypertensive rats (SHR) and with 75, 100, 125 and 150 mg/kg for male normotensive Wistar Kyoto rats (WKY). Blood pressure was measured by indirect tail-cuff method until 12 weeks of age. STZ-treated SHR, of which plasma glucose and glycosylated hemoglobin increased and body weight decreased with the dose of STZ, developed and maintained hypertension, same as did the vehicle-treated control SHR. On the other hand, STZ-treated WKY which developed only mild hyperglycemia lost body weight with the dose of STZ but the blood pressures rose slightly, these changes being correlated with the glycemic levels. The explanation for these differences between SHR and WKY remained to be elucidated.

Animals↗
PubMed1987

Effects of a new vasodilator, nicorandil, on exercise-induced impairment of left ventricular function in patients with old myocardial infarction.

Hemodynamic effects of nicorandil on exercise-induced impairment of left ventricular function were studied in nine patients with old myocardial infarction but without angina pectoris. Hemodynamic data were obtained by symptom-limited supine multistage bicycle ergometer exercise testing before and 1 h after single oral administration of 15 mg of nicorandil. Systolic and diastolic blood pressure at rest decreased significantly after nicorandil administration (p less than 0.01). A most remarkable change in the hemodynamic response to supine dynamic exercise after nicorandil was a decrease in pulmonary artery wedge pressure (both at rest and at peak exercise, p less than 0.001). An index cardiac function, obtained from the relation between pulmonary artery wedge pressure and left ventricular stroke work index, improved significantly after nicorandil. The ration of pressure-rate product to coronary sinus flow, which is an index of the ratio of myocardial oxygen consumption to myocardial oxygen supply, decreased significantly (p less than 0.05) after nicorandil administration. Reproducibility of the testings was also studied in six patients with old myocardial infarction. Invasive hemodynamic variables between two successive symptom-limited supine leg exercise testings, except pulmonary artery wedge pressure, were reproducible in patients with old myocardial infarction but without angina pectoris. Only pulmonary artery wedge pressure at rest in the second exercise testing showed a significantly lower value (p less than 0.05). It is concluded that nicorandil is a useful drug for improvement of exercise-induced impairment of left ventricular function with an increase in myocardial oxygen supply.

Adult↗
PubMed1986

Evaluation by pulsed Doppler echocardiography of the atrial contribution to left ventricular filling in patients with DDD pacemakers.

To evaluate the significance of the left atrial (LA) contribution to left ventricular (LV) filling in cardiac pacing, LV inflow velocity was recorded with pulsed Doppler echocardiography in 20 patients with a DDD pacemaker. The pacemaker was programmed to atrioventricular (AV) sequential pacing with AV intervals of 50, 100, 150, 200 and 250 ms, and then to VVI pacing at a fixed rate of 70 beats/min. To evaluate the relative changes of LV filling volume in individual patients, the percent change in time-velocity integral of LV inflow velocity in each pacing mode was calculated as the ratio to that of AV sequential pacing with an AV interval of 150 ms. To estimate the degree of LA contribution to LV filling, the ratio of time-velocity integral during LA ejection phase to that during total LV filling phase was measured at the optimal AV interval. The percent LV inflow volume in AV sequential pacing was 74% for an AV interval of 50 ms, 87% for 100 ms, 98% for 200 ms and 90% for 250 ms. The percent LV inflow volume in VVI pacing was 72%. The percent LV inflow volume at AV intervals of 150 ms was significantly greater than that at an AV interval of 50, 100 and 250 ms, and in VVI pacing (p less than 0.05). The degree of LA contribution to LV filling showed a positive correlation with the percent increase of LV inflow volume with mode conversion from VVI to AV sequential pacing (p less than 0.005) and also with age (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

A new model of type 2 (non-insulin-dependent) diabetes mellitus in spontaneously hypertensive rats: diabetes induced by neonatal streptozotocin treatment.

This study was designed to develop an animal model of Type 2 (non-insulin-dependent) diabetes with persistent hypertension. Male spontaneously hypertensive rats were treated with 25.0, 37.5, 50.0, 62.5 or 75.0 mg/kg of streptozotocin given intraperitoneally at 2 days of age and maintained for 12 weeks. In the rats which received 50.0 mg/kg or more streptozotocin, overt hyperglycaemia gradually and consistently developed following incomplete recovery from an initial hyperglycaemia. Compared to vehicle-treated controls, body weight gain in these animals did not differ for the first 8 weeks; thereafter, it was slightly but significantly (p less than 0.05) reduced. The animals treated with 25.0 or 37.5 mg/kg streptozotocin developed mild to moderate hyperglycaemia, but their body weight gain was similar to controls. The relationships between streptozotocin dose and metabolic responses (plasma glucose, glycosylated haemoglobin, urinary glucose, food intake, etc.) were clearly demonstrated. Systolic blood pressure rose with progressing age in both controls and streptozotocin-treated rats, irrespective of dosage or metabolic response. This new rat model of Type 2 diabetes associated with persistent hypertension may be useful in studying these combined effects on small and large vessels.

Animals↗
PubMed1986

Exercise P-vector magnitude changes in angina pectoris: Frank-Vectorcardiographic and hemodynamic correlations.

Multistage bicycle ergometer exercise testings with Frank vectorcardiogram and M-mode echocardiogram were performed on 12 patients with effort angina pectoris. The left atrial and left ventricular end-diastolic volume (LAV and LVEDV) were calculated as a cube of the left atrial and left ventricular end-diastolic dimension. The mean pulmonary artery wedge pressure (mPAWP) was measured with a Swan-Ganz catheter during the testing. At peak exercise a statistically significant increase was observed in mPAWP (p less than 0.001), LAV (p less than 0.005), the maximal horizontal P-vector magnitude (Hmax) (p less than 0.05) and the percent change in Hmax (%Hmax). %Hmax showed a significant correlation with the increment of mPAWP (delta mPAWP) (r = 0.66, p less than 0.05), the increment of LVEDV (delta LVEDV) (r = 0.83, p less than 0.01) and the increment of LAV (delta LAV) (r = 0.81, p less than 0.001). Multiple regression analysis was performed on %Hmax as a dependent variable with delta LAV, delta mPAWP, and the increment of heart rate (delta HR) as independent variables (r = 0.84, p less than 0.05), but the partial correlation coefficients of delta mPAWP and delta HR were not significant. The present study demonstrated that the increase in Hmax had a close relationship with the increase in mPAWP and LVEDV and that the preload of the left ventricle during exercise-induced anginal attack could be predicted noninvasively by %Hmax. The increase in Hmax was thought to be due to the increase in LAV during anginal attack.

Adult↗
PubMed1986

[Pulsed Doppler echocardiographic evaluation of hemodynamics in premature ventricular contractions].

To investigate hemodynamic changes in ventricular premature contractions (VPCs), the blood flow velocities at the left ventricular (LV) outflow and inflow tracts were analyzed by pulsed Doppler echocardiography in 23 patients with VPCs and in two patients with ventricular parasystoles. Percent LV stroke volume of the ectopic and the postectopic sinus beats to the other sinus beats and %LV inflow volume of the sinus beats preceding ectopic beats to the other sinus beats were calculated from the time integral of the blood flow velocity. The following results were obtained. The %LV stroke volume of VPCs or %LV inflow volume of the preceding sinus beats correlated positively with the coupling interval of VPCs (r = 0.69, p less than 0.001 and r = 0.67, p less than 0.001, respectively). The %LV stroke volume of VPCs correlated positively with %LV inflow volume of the preceding sinus beats (r = 0.84, p less than 0.001). In some patients with VPCs of the RBBB pattern and in one patient with VPCs of the LBBB pattern associated with abnormal right axis deviation, the %LV stroke volume of VPC was much more reduced. In patients with depressed rapid filling and increased atrial filling, %LV stroke volume of the VPC or %LV inflow volume of the preceding sinus beat was smaller than in the other patients with the same coupling interval of VPCs. In VPCs of right ventricular (RV) origin, deterioration of RV hemodynamics was more prominent than in those of LV origin, and vice versa. Increased LV stroke volume was observed in postextrasystolic sinus beats, related to the coupling intervals of VPCs. However, the sum of %LV stroke volume of VPC and the postextrasystolic sinus beat decreased as the coupling intervals of VPC shortened. These results suggest that not only the coupling interval and the origin of VPCs but the LV diastolic behavior, as well, are important factors determining the hemodynamics in VPCs. They also suggest that the increment of stroke volume in postextrasystolic beats is more prominent in VPCs with shorter coupling intervals, but the LV performance as a whole is more depressed in VPCs with a shorter coupling intervals. In conclusion, pulsed Doppler echocardiography proved a useful noninvasive technique for evaluating the hemodynamics of VPCs.

Cardiac Complexes, Premature↗