PubMed Health⌕ Search

Biomedical subjects

M Iwase

Publications and source records attributed to M Iwase.

At least 163 records · Page 9Linked to original sources
PubMed1991

Dependency of the pulsed Doppler-derived transmitral filling profile on the sampling site.

In previous reports that evaluated pulsed Doppler transmitral filling, the sampling site has varied; we examined the effect of the sample volume location on Doppler measurements. Studied were 97 patients: 58 with normal echocardiograms, 20 with mitral regurgitation, and 19 with miscellaneous cardiac diseases. Transmitral filling was recorded at the mitral anulus and at the left atrial and left ventricular (LV) sides of the mitral tips. As the sample volume was moved from the mitral anulus to the LV side, the peak velocity and time-velocity integral of early diastole increased (40.6 +/- 13.8 versus 59.0 +/- 19.0 cm/sec, 5.26 +/- 1.65 versus 8.35 +/- 2.37 cm; p less than 0.001) as did those of late diastole (48.7 +/- 11.5 versus 57.5 +/- 17.0 cm/sec, 3.48 +/- 0.97 versus 4.59 +/- 1.39 cm; p less than 0.001). The late-to-early diastolic peak velocity and time-velocity integral ratios and the late-to-total diastolic time-velocity integral ratio decreased (1.33 +/- 0.51 versus 1.06 +/- 0.41, 0.71 +/- 0.24 versus 0.58 +/- 0.19, 0.40 +/- 0.09 versus 0.36 +/- 0.08; p less than 0.001). The dependency of these indices on the sampling site was in the same degree in all three groups. However, the peak filling rate normalized to mitral stroke volume (4.71 +/- 1.43 versus 4.63 +/- 1.32 l/sec; p = NS) was not influenced by the sample volume location; thus this parameter may be more reliable for assessing LV filling.

Adolescent↗
PubMed1991

Comparison of reliability of plasma fructosamine and glycosylated hemoglobin assays for assessing glycemic control in diabetic patients on hemodialysis.

To search for a reliable marker of medium-term integrated blood glucose level in diabetics on maintenance hemodialysis (HD), plasma fructosamine and glycosylated hemoglobin (Hb) levels were determined every week and blood glucose levels were determined four times every day over 3 weeks. The mean values of fructosamine (mol/L per 40 g of albumin) and of glycosylated Hb of other the study period correlated (r = .746, P less than .001) for combined materials of diabetic and nondiabetic subjects. However, plasma fructosamine values at the end of the study period did not correlate with the overall mean blood glucose values during the preceding 8 to 21 days (r = .372, NS). In contrast, glycosylated Hb values correlated closely with the same mean blood glucose values (r = .703, P less than .001). Fructosamine values significantly decreased during a HD, irrespective of the increases in albumin and total protein. In conclusion, glycosylated Hb was a reliable marker of long-term integrated blood glucose even in diabetics on HD. However, fructosamine was not a reliable marker of medium-term integrated blood glucose in these patients.

Blood Glucose↗
PubMed1991

Spontaneous recovery from non-insulin-dependent diabetes mellitus induced by neonatal streptozotocin treatment in spontaneously hypertensive rats.

We studied the long-term change in glycemic level in a model of non-insulin-dependent diabetes mellitus (NIDDM) induced by neonatal streptozotocin (STZ) treatment in spontaneously hypertensive rats (SHR). Two-day-old male SHR were intraperitoneally injected with 37.5 to 75.0 mg/kg of STZ or vehicle alone as control. According to nonfasting plasma glucose levels at 12 weeks of age, rats were divided into mild (less than 16.8 mmol/L) and severe (greater than or equal to 16.8 mmol/L) diabetes groups. In the mild diabetes group (n = 5), plasma glucose decreased significantly from 14.2 +/- 1.8 mmol/L (mean +/- SEM) at 20 weeks to 7.3 +/- 0.3 mmol/L at 52 weeks (P less than .05) with progressing age. At 52 weeks, overnight fasting plasma glucose levels were significantly lower and serum immunoreactive insulin (IRI) was higher than in controls, respectively (4.1 +/- 0.3 v 5.7 +/- 0.3 mmol/L, P less than 0.01; 625 +/- 50 v 409 +/- 50 pmol/L, P less than .05), and insulinoma was found in 60% of rats. Therefore, the recovery from hyperglycemia may be attributed to the development of insulinoma. In the severe diabetes group (n = 6), plasma glucose remained high until 28 weeks (27.2 +/- 1.5 mmol/L), but thereafter decreased with age, as it did in the mild diabetes group (13.7 +/- 3.5 mmol/L at 52 weeks, P less than .005). However, no insulinoma was found, and the mechanism for the recovery was unclear. The present study demonstrates that hyperglycemia spontaneously ameliorates in a neonatal STZ diabetes model of SHR, although this phenomenon may be strain-related.

Aging↗
PubMed1991

Immunocytochemistry of thyrotropin-releasing hormone in the rabbit medulla oblongata.

The distribution and ultrastructure of thyrotropin-releasing hormone-like immunoreactive (TRH-LI) neurons were examined in rabbit medulla oblongata. TRH-LI cell bodies were located in the ventral region of the medulla oblongata: in the paraolivary and parapyramidal regions, regions in and around the pyramidal tract, the dorsolateral region of the lateral reticular nucleus, and the raphe nuclei. The paraolivary and parapyramidal regions contained most of the TRH-LI cell bodies in the medulla oblongata. TRH-LI neurons processes were densely distributed in the dorsal vagal complex and the area postrema. Electron-microscopic immunocytochemical studies revealed TRH-LI neurons at the obex level in the paraolivary region of rabbits. TRH-like immunoreactivity was localized in larger granular vesicles. TRH-LI somata and dendrites received synaptic inputs from both TRH-LI and unlabeled axon terminals. More than half of the TRH-LI axon terminals made synapses with somata or processes of TRH-LI neurons. These observations, together with previous reports that TRH causes respiratory facilitation, suggest that TRH-LI neurons in the paraolivary region in rabbits may be involved in respiratory functions.

Animals↗
PubMed1991

A new animal model of non-insulin-dependent diabetes mellitus with hypertension: neonatal streptozotocin treatment in spontaneously hypertensive rats.

Streptozotocin (STZ) treatment on neonatal rats produces a non-insulin-dependent diabetes mellitus (NIDDM) model in adulthood. Applying this model to spontaneously hypertensive rats (SHR), we designed the present study to develop a new model of NIDDM with genetic hypertension. Two-day-old male and female SHR were intraperitoneally injected with 25.0-75.0mg/kg STZ, and two-day-old Wistar Kyoto rats (WKY) of both sexes, which are a normotensive control strain for SHR, were similarly injected with 75.0-150.0mg/kg STZ. Control rats received vehicle alone. The relationships between the doses of the STZ injected and the changes of the metabolic variable and blood pressure were examined for 12 weeks following the treatment. Plasma glucose levels in male SHR increased in a dose-dependent manner at 12 weeks, control 122 +/- 8 (SEM) mg/dl, 25.0mg/kg STZ 139 +/- 13mg/dl (ns), 37.5mg/kg STZ 240 +/- 51mg/dl (ns), 50.0mg/kg STZ 359 +/- 39mg/dl (p less than 0.01), 62.5mg/kg STZ 419 +/- 33mg/dl (p less than 0.001) and 75.0mg/kg STZ 513 +/- 10mg/dl (p less than 0.001), whereas in male WKY, only mild hyperglycemia developed in case of the higher doses of STZ given, control 112 +/- 4mg/dl, 75.0mg/kg STZ 136 +/- 18mg/dl (ns), 100.0mg/kg STZ 204 +/- 40mg/dl (ns), 125.0mg/kg STZ 219 +/- 37mg/dl (p less than 0.05), and 150.0mg/kg STZ 177 +/- 12mg/dl (p less than 0.01). The development of hypertension was not affected by the neonatal STZ treatment in male SHR at 11 weeks, systolic blood pressure being control 210 +/- 7mmHg, 25.0mg/kg STZ 217 +/- 5mmHg (ns), 37.5mg/kg STZ 202 +/- 3mmHg (ns), 50.0mg/kg STZ 216 +/- 6mmHg (ns), 62.5mg/kg STZ 210 +/- 6mmHg (ns), and 75.0mg/kg STZ 209 +/- 5mmHg (ns). For the long-term observation, STZ-treated male SHR were divided into mild diabetes group (plasma glucose at 12 weeks less than 300mg/dl, mean 195 +/- 21mg/dl) and severe diabetes group (greater than or equal to 300mg/dl, mean 445 +/- 18mg/dl). Hyperglycemia in both groups was maintained until 28 weeks, plasma glucose being control 112 +/- 4mg/dl, mild diabetes group 161 +/- 10mg/dl (p less than 0.01), and severe diabetes group 419 +/- 25mg/dl (p less than 0.001) but it later gradually ameliorated, plasma glucose at 52 weeks being control 120 +/- 3mg/dl, mild diabetes group 131 +/- 7mg/dl (ns), and severe diabetes group 220 +/- 43mg/dl (ns). However, hypertension persisted in both diabetes groups until 52 weeks, systolic blood pressure being control 209 +/- 6mmHg, mild diabetes group 199 +/- 9mmHg (ns), and severe diabetes group 221 +/- 6mmHg (ns).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

[Evaluation of maintenance of cardiac output during DDD and VVI pacing by exercise Doppler echocardiography].

To evaluate the efficacy of DDD pacing for cardiac reserve, we assessed increases in the stroke volume and cardiac output during randomized treadmill exercise in 16 patients by DDD and fixed-rate ventricular (VVI) pacing. The stroke volume index and cardiac index were determined using suprasternal Doppler measurements. Ten patients who showed sinus rhythm during exercise were excluded from this study. Compared with the findings during VVI pacing, those during DDD pacing showed: 1) a greater exercise-induced positive chronotropic response (mean maximum heart rate 122 +/- 22 beats/min vs 70 beats/min, p < 0.01), 2) a lesser increase in the stroke volume index (34 +/- 7 to 39 +/- 9 ml/m2 vs 31 +/- 7 to 49 +/- 11 ml/m2, p < 0.05), 3) a greater increase in the cardiac index (2.43 +/- 0.45 to 4.48 +/- 1.36 L/min/m2 vs 2.22 +/- 0.47 to 3.43 +/- 0.45 L/min/m2, p < 0.05), and 4) prolongation of exercise duration (6.35 +/- 2.00 min vs 5.97 +/- 1.81 min, NS). These findings indicated that VVI pacing promoted a greater stroke volume than DDD pacing, which provides a compensatory increase in contractility and the preload in cases without an increase in heart rate during exercise, however, the increase in cardiac output was insufficient due to the absence of a chronotropic response. In conclusion, a DDD pacemaker could effectively increase heart rate, causing a significant increase in cardiac output and extending exercise duration.

Adult↗
PubMed1990

Pre-inspiratory burst in the caudal medulla of rabbits.

The activity of 48 respiratory units in the paraolivary region from the middle to the rostral end of the hypoglossal cranial nerve root, and the effect of electrical stimulation and L-glutamate applied to the region on phrenic nerve activity was investigated in 14 rabbits. Electrical stimulation (50 Hz, 0.2 ms current pulses at intensities 5-20 microA) and L-glutamate (30-100 ng) shortened the expiratory time and increased the respiratory rhythm with no change in tidal phrenic nerve activity. Rhythmic activity preceding the phrenic nerve activity (pre-inspiratory burst) was recorded in the paraolivary region. The temporal relationship between the pre-inspiratory (pre-I) burst and the phrenic activity remained constant even when the respiratory frequency was altered by passive lung inflation. These results suggest that structures in the paraolivary region may influence the respiratory rhythm in rabbits and that pre-I burst neurons may play a role in triggering periodic phrenic activity.

Action Potentials↗
PubMed1990

Prediction of left ventricular function during supine bicycle ergometer exercise in angina-free patients with old myocardial infarction.

We investigated whether or not left ventricular function during dynamic exercise in angina-free patients with old myocardial infarction could be estimated using resting left ventricular function and noninvasive parameters determined during exercise. We studied 70 patients with old myocardial infarction by measuring hemodynamic parameters during supine multistage bicycle ergometer exercise. Coronary arteriography and left ventriculography were performed: then the left ventricular ejection fraction and left ventricular end-diastolic volume were measured. The parametric changes (delta) between rest and peak exercise were determined. Significant positive correlations were observed between cardiac index (CI) at rest and at peak exercise (r = 0.62, p less than 0.001), as well as between pulmonary artery wedge pressure (PAWP) at rest and at peak exercise (r = 0.72, p less than 0.001). Multiple regression analysis indicated that CI and PAWP at peak exercise as dependent variables were best described by the equations: CI at peak exercise = 1.074 [CIrest] +0.031 [delta HR] + 0.004 [ExD] + 0.018 [LVEF] - 1.560 (r = 0.79, p less than 0.001), PAWP at peak exercise = 0.994 [PAWPrest] - 0.181 [LVEF] + 0.203 [delta DBP] -0.076 [delta HR] -21.488 (r = 0.80, p less than 0.001). These data suggested that CI and PAWP during dynamic exercise in angina-free patients with old myocardial infarction could be predicted using noninvasive parameters, such as increments of blood pressure and heart rate as well as exercise duration, together with data on resting left ventricular function, such as resting CI, resting PAWP, and resting left ventricular ejection fraction (LVEF).

Adult↗
PubMed1990

Assessment of left ventricular function after sublingual administration of nifedipine in patients with moderate to severe hypertension.

To evaluate the left ventricular functional changes induced by acute decreases in blood pressure in 15 patients with systemic hypertension and left ventricular hypertrophy, this study used Doppler and M-mode echocardiographic derived left ventricular indices. After 30 minutes of administration of sublingual nifedipine, both systolic and diastolic blood pressure decreased and heart rates increased. The left ventricular end-systolic dimension decreased but not the end-diastolic dimension, which suggests that sublingual nifedipine may decrease only afterload, not preload. Total peripheral resistance decreased from 2770 to 1960 dyne.sec.cm-5. The M-mode-derived peak rate of dimension changes improved both the systolic and diastolic phase, and Doppler-derived indices of atrial contribution to ventricular filling decreased. Because both the systolic and diastolic phase indices of LV function are sensitive to variations in both preload and afterload, the improvement of myocardial contractility per se cannot necessarily be attributed to the direct effect of the drug to myocardium. Though favorable effects on the myocardial oxygen supply-demand ratio or increased adrenergic tone stimulated by the decline in systemic arterial pressures may contribute to the augmentation of LV systolic and diastolic function observed after nifedipine in the present study, the apparent augmentation of LV function appears to be attributable primarily to afterload reduction.

Administration, Sublingual↗
PubMed1990

Mechanism of abnormal postexercise systolic blood pressure response and its diagnostic value in patients with coronary artery disease.

To define the factors that affect an abnormal postexercise systolic blood pressure (SBP) response and to verify the diagnostic value of that response in patients with coronary artery disease (CAD), we studied 33 normal subjects, eight patients with hypertension who had no CAD, and 42 patients with documented CAD who underwent supine leg exercise testing. SBP recovery ratios were derived by dividing the values obtained 1 and 3 minutes after exercise by the peak value. The upper normal limit of the SBP ratio was defined by two standard deviations from the mean for 33 normal subjects. The specificity of this criterion for identifying patients with CAD was 97% and the sensitivity was 60%. None of the eight patients with hypertension showed an abnormal postexercise SBP response. At peak exercise the pulmonary artery wedge pressure was significantly greater in the patients with CAD having an abnormal response. In multiple regression analysis the exercise pulmonary artery wedge pressure, the exercise SBP, and the systemic vascular resistance after exercise were determining factors for an abnormal SBP response. Three-vessel disease was more common in patients with an abnormal response. Results of this study indicate that an abnormal postexercise SBP response appears to be determined by (1) the extent of exercise-induced impairment of left ventricular function and (2) peripheral vascular tone during recovery. This study also suggests that this criterion can increase the specificity of supine exercise testing in patients with CAD including those with hypertension and might provide a marker for the severity of impaired left ventricular function by exercise in CAD.

Adult↗
PubMed1990

Dynamic exercise-induced elevation in plasma levels of atrial natriuretic peptide in patients with effort angina pectoris.

We investigated the relationship between plasma atrial natriuretic polypeptide (ANP) levels and hemodynamic indices during dynamic exercise testing in 15 patients with effort angina pectoris. Patients exercised on an angina-limited, supine, multistage bicycle ergometer, and plasma ANP levels and hemodynamic indices were measured at rest, at peak exercise, and 6 minutes after exercise. Plasma ANP levels increased significantly at peak exercise. Pulmonary artery wedge pressure (PAWP) and coronary sinus blood flow (CSBF) were significantly correlated with plasma ANP levels before and at peak exercise (PAWP: r = 0.69, p less than 0.001; CSBF; r = 0.45, p less than 0.05). In six of eight patients whose PAWP exceeded 20 mm Hg at peak exercise, plasma ANP levels were increased at 6 minutes after exercise, whereas PAWP had decreased relative to the values obtained at peak exercise. Plasma ANP concentrations at 6 minutes after exercise were not correlated with PAWP at the same time. However, PAWP at peak exercise was correlated with the plasma ANP levels at 6 minutes after exercise (r = 0.80, p less than 0.001). These results suggest that in patients with effort angina pectoris left ventricular dysfunction resulting from exercise-induced myocardial ischemia may increase preload excessively and may contribute to the excess secretion of ANP after dynamic exercise.

Adult↗
PubMed1990

Lack of association between blood pressure and insulin in patients with insulinoma.

To investigate the hypothesis that insulin affects the regulation of blood pressure, blood pressure and fasting insulin and glucose levels were measured in seven patients with insulinoma both before and after resection of the insulinoma. The diagnosis of all insulinoma cases was confirmed during surgery. Before surgery, systolic and diastolic blood pressures were 127 +/- 15 and 74 +/- 9 mmHg, respectively, and did not correlate with the fasting insulin levels. At least 3 weeks after the surgery, significant decreases in fasting insulin levels (from 568 +/- 571 to 74 +/- 43 pmol/l, P less than 0.005) and body weight (-9.8 +/- 7.1%, P less than 0.05) were observed along with a significant increase in fasting glucose levels (98.2 +/- 43.2%, P less than 0.001). However, both systolic (-4.7 +/- 9.9%) and diastolic (-0.2 +/- 6.3%) blood pressures remained unchanged. The changes in fasting insulin levels were not linearly correlated with those in systolic and diastolic blood pressures. Even after the changes in both body weight and fasting glucose levels were taken into consideration using partial correlations, the changes in fasting insulin levels did not correlate with those in systolic and diastolic blood pressures. It was concluded that blood pressure, both systolic and diastolic, was not at hypertensive levels in the patients with insulinoma and showed no decrease after resection of the insulinoma. Therefore, insulin may not affect the regulation of blood pressure in patients with insulinoma.

Adenoma, Islet Cell↗
PubMed1990

Leukocidal activity of staphylococci isolated from human periodontal lesions.

Staphylococci isolated from subgingival samples of patients with advanced periodontitis were tested for leukocidal activity. Intact organisms, bacterial sonicates or bacterial culture supernatants were incubated with human neutrophils that had been prelabeled with 51chromium. The majority of Staphylococcus aureus periodontal isolates provoked dose-dependent extracellular release of the radiolabel. By contrast, other strains of staphylococci had marginal or no demonstrable leukocidal activity. Leukocidal activity was heat-sensitive and was neutralized by horse anti-leukocidin antibodies. The results indicate that S. aureus colonizing human periodontal lesions elaborate a leukocidin that may conceivably destroy neutrophils that emigrate into the gingival region. This could adversely affect the overall status of this antimicrobial defense system in the gingival area and contribute to the pathogenicity of S. aureus as well as other potential periodontopathic organisms.

Chromium Radioisotopes↗
PubMed1990

Effects of cations and osmotic protectants on cytolytic activity of Actinobacillus actinomycetemcomitans leukotoxin.

Actinobacillus actinomycetemcomitans leukotoxin permeabilized the plasma membrane of HL-60 promyelocytic leukemia cells, resulting in colloid osmotic lysis. These events were associated with efflux of 51chromium (from prelabeled cells), influx of propidium iodide, and ultrastructural evidence of cellular damage. Target cell lysis was inhibited by procedures which may interfere with the initial interaction of the toxin with the plasma membrane. For example, washing cultures (to dilute and remove toxin) or the addition of monoclonal antibodies (to neutralize toxin) or trypsin (to inactivate toxin) limited lysis when undertaken within the first 5 min of the reaction. The extent of injury was also diminished when radiolabeled HL-60 cells were exposed to toxin in the presence of unlabeled, toxin-sensitive cells (e.g., HL-60 cells or human neutrophils) or certain toxin-resistant target cells (e.g., human K562 erythroleukemia cells). This suggests that the association of the toxin with the cell membrane may not be sufficient to cause lysis without activation of additional effector mechanisms. The addition of specific trivalent (e.g., La3+) or divalent (e.g., Ca2+ and Zn2+) cations to toxin-treated cells appeared to enhance their capacity to repair or minimize the extent of toxin-mediated membrane damage. Depending on size, certain saccharides served as osmotic protectants: maltose almost completely inhibited radiolabel release, while smaller molecules provided correspondingly less protection. The results imply that the leukotoxin has membranolytic activity, producing pores in target cells with a functional diameter approximately the size of maltose (0.96 nm).

Actinobacillus↗