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Biomedical subjects

T Fujinami

Publications and source records attributed to T Fujinami.

At least 55 records · Page 3Linked to original sources
PubMed1994

Effects of respiratory interval on vagal modulation of heart rate.

To determine whether paced breathing (PB) and respiratory interval of PB modify the relationship between spectral components of heart rate variability (HRV) and cardiac vagal tone, we studied seven healthy young males under the condition of beta-adrenergic blockade by intravenous propranolol (0.2 mg/kg). Compared with spontaneous breathing, PB at the same respiratory interval as that of individual spontaneous breathing showed no significant effect on the amplitude of the high-frequency (HF) component or the mean R-R interval in either the supine or tilt position, whereas the PB decreased the amplitude of the low-frequency (LF; 0.04-0.15 Hz) component in both positions (P = 0.004 and 0.042, respectively). When the respiratory interval was increased from 3 to 6 s, the HF amplitude showed a progressive increase in both positions (P = 0.001 and 0.035, respectively), while the LF amplitude and mean R-R interval remained unchanged. These results indicate that the effects of PB and respiratory interval on the spectral components of HRV are not mediated by the changes in mean cardiac vagal tone and support the hypothesis that increased respiratory interval amplifies the respiratory-related vagal modulation of heart rate.

Adrenergic beta-Antagonists↗
PubMed1994

Assessment of frequency shifts in R-R interval variability and respiration with complex demodulation.

A complex demodulation (CDM) method for continuous assessment of frequency shifts and time-dependent changes in amplitude in the rhythmic components existing in predefined frequency bands was proposed and applied to the analysis of high-frequency (HF) and low-frequency (LF) components of the R-R interval and to the analysis of respiration via impedance spirogram. Simulation studies revealed that this CDM technique furnishes mathematical features well suited to the investigation of non-stationary R-R interval signals and can delineate time-dependent fluctuations in both amplitude and frequency, accurately differentiating between HF and LF components. Analysis of data during paced breathing at different respiratory frequencies revealed that the estimated frequency of the HF component and respiration faithfully reflected the frequency of paced breathing. Analysis of data during dynamic exercise with increasing workload (20 W/min) showed that the frequency of the HF component was elevated with exercise and that both HF and LF amplitudes were reduced progressively with advancing load. CDM-derived frequency and amplitude of respiration were highly correlated to direct breath-by-breath respiratory frequency and tidal volume measurements. We conclude that this method could provide a powerful means for continuously assessing time-dependent changes in both cardiovascular and respiratory variations.

Adult↗
PubMed1994

Percutaneous transluminal coronary angioplasty of "superdominant" left anterior descending artery. A case report.

A seventy-one-year-old woman suffering from angina pectoris had a superdominant left anterior descending artery with a 95% stenosis just after it extended the apex. This superdominant artery was demonstrated angiographically by the findings that it ran in the posterior interventricular sulcus and reached the crux of the heart. Percutaneous transluminal coronary angioplasty for the stenosis beyond the apex was successfully performed. After the procedure, she was relieved from chest pain.

Aged↗
PubMed1993

Excretion of urinary epidermal growth factor in non-insulin dependent diabetes mellitus.

Morning urine samples were assayed for human EGF (hEGF) in 137 non-insulin dependent diabetic patients with normal serum creatinine and beta 2-microglobulin levels. Serving as controls, 80 age- and sex-matched healthy subjects were also examined. A significant positive correlation between hEGF excretion and the level of hemoglobin A1C (HbA1c) was present in those patients with a HbA1c value exceeding 8% (r = 0.37; p = 0.003) but not in the overall patients. The urinary hEGF level did not correlate with the concentration of glucose in urine or plasma. The mean urinary hEGF level of diabetic patients was significantly lower than that of healthy subjects. The mean urinary hEGF level was significantly lower in the patients with a diabetic history that exceeded five years as compared with those with a history below five years. The mean urinary hEGF level was significantly lower in the patients with retinopathy vs. those without retinopathy. In the patients with HbA1c value below 8%, the mean urinary hEGF level was lower in the patients whose urinary albumin level exceeded 1.7 mg/mmol.creatinine as compared with those whose urinary albumin excretion was below 1.7 mg/mmol.creatinine. These findings suggest that urinary hEGF excretion may decrease with the progression of diabetic complications in the patients with well-controlled glycemia, and that inadequate glycemic control may lead to an increased excretion of urinary hEGF in the early disease stage.

Adult↗
PubMed1993

Effect of ascorbic acid on pituitary prolactin secretion in the non-ascorbate synthesizing Osteogenic Disorder Shionogi (ODS) rat.

We examined the secretion of prolactin (PRL) in the hereditary scurvy-prone Osteogenic Disorder Shionogi (ODS) rat to investigate the role of ascorbic acid (AsA) in pituitary lactotroph and hypothalamic function. Plasma PRL concentrations of conscious AsA-deficient or control ODS rats were measured before and after the administration of metoclopramide (MCP), 5-hydroxy-L-tryptophan (5-HTP) or saline. The basal plasma PRL levels did not differ between the two groups. However, the AsA-deficient rats exhibited significantly larger changes in plasma prolactin concentration in response to MCP or 5-HTP than the control ODS rats. Thus, AsA deficiency enhanced the stimulated, but not the basal, secretion of PRL in ODS rats. Our findings suggest that AsA may have an inhibitory effect on PRL secretion.

5-Hydroxytryptophan↗
PubMed1993

Continuous assessment of hemodynamic control by complex demodulation of cardiovascular variability.

Usefulness of complex demodulation (CDM) in assessing the frequency components of cardiovascular variability was assessed and, subsequently, this technique was utilized to determine the time-dependent responses of the low-frequency (LF) and high-frequency (HF) amplitudes of heart rate and blood pressure variabilities during postural tilt. CDM provides the time-dependent changes in amplitude of a particular frequency component on a continuous basis. Analysis of simulated data showed that CDM has sufficient frequency resolution to separately measure LF and HF amplitudes with a time resolution < 15 s and that CDM is robust to alterations in the frequency of the components. Analysis of actual data during postural tilt test in 23 young healthy subjects demonstrated that the HF amplitude of heart rate, an index of cardiac parasympathetic tone, rapidly decayed with head-up tilt (P < 0.01) and increased quickly showing an overshoot with tilt back to the supine position (P < 0.01). The LF amplitude of blood pressure, an index of vasomotor sympathetic activity, showed marked rhythmic fluctuation at an interval of 48-100 s during head-up tilt (P < 0.01), synchronizing with similar fluctuation in the LF amplitude of heart rate (P < 0.01). These results suggest that CDM can be used to provide a continuous assessment of cardiovascular variability components and that the dynamic responses of autonomic circulatory control to upright posture result in a phasic modulation of LF amplitude.

Adult↗
PubMed1993

Detection of coronary artery stenosis by dipyridamole radionuclide ventriculography.

We assessed the usefulness of dipyridamole radionuclide ventriculography for detecting significant coronary artery stenosis in 89 patients who were undergoing cardiac catheterization. Radionuclide ventriculography was performed before and after the infusion of dipyridamole (0.56 mg/kg). The end-diastolic regions of interest of the left ventricle were divided into 5 sectors for calculation of the regional ejection fractions. Results were considered to be positive when the regional ejection fraction decreased by more than 5% after the infusion of dipyridamole. The presence of significant coronary artery stenosis (> 75%) was demonstrated by arteriography in 49 patients and was absent in 40 patients. A decrease in the regional ejection fraction greater than 5% was observed in 41 (84%) of the 49 patients with significant coronary artery stenosis and in 2 of the 40 without significant coronary stenosis. The sensitivity and specificity of this method for detecting significant coronary artery stenosis were 84% and 95%, respectively. We conclude that a decrease in the radionuclide-determined regional ejection fraction after the infusion of dipyridamole reflects left ventricular dysfunction and is a sensitive and specific indicator of significant coronary artery stenosis.

Adult↗
PubMed1992

Noninvasive evaluation of left ventricular performance by the shortest distance between mitral leaflets coaptation and interventricular septum at end-systole.

We attempted to evaluate left ventricular performance from the shortest distance between the mitral leaflets coaptation and the interventricular septum at end-systole (MVC-IVS distance). The subjects were 37 patients with coronary artery disease (CAD) with prior myocardial infarction (MI), 8 with CAD without prior MI, 22 with atypical chest pain, and 4 with aortic regurgitation. The MVC-IVS distance was measured on a two-dimensional echocardiogram obtained from the parasternal or apical long-axis view and frozen at end-systole. Left ventricular end-systolic volume and end-diastolic volume were obtained by left ventriculography, and the left ventricular ejection fraction was calculated. A significant positive correlation was observed between the MVC-IVS distance and the end-systolic volume (r = 0.83, p less than 0.001); a close correlation was observed between the MVC-IVS distance end-systolic volume and ejection fraction by monoexponential fitting (r = -0.91, p less than 0.001). Thus, a significant negative correlation was observed between the MVC-IVS distance and the left ventricular ejection fraction (LVEF) (r = -0.83, p less than 0.001). An MVC-IVS distance of greater than or equal to 30 mm suggests diagnosis of left ventricular dysfunction (LVEF less than 50%) with high sensitivity (94.4%) and specificity (90.6%), while a value less than 30 mm suggests that the left ventricular performance is likely to be normal. Thus one can easily evaluate the left ventricular performance noninvasively using this new index.

Adult↗
PubMed1992

Effects of prostacyclin infusion on blood pressure and plasma renin activity in patients with essential hypertension.

The effects of prostacyclin infusion (6.7 +/- 2.7 ng/kg/min, 3 to 10 ng/kg/min) on blood pressure, plasma renin activity (PRA), and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were studied in 7 patients with essential hypertension (4 men and 3 women) with a mean age of fifty-eight +/- eleven years (forty-six to seventy-four years). The baseline value of 6-keto-PGF1 alpha for patients with essential hypertension was not lower than in healthy subjects. Blood pressure immediately dropped following prostacyclin infusion. Systolic blood pressure returned to the baseline value after prostacyclin infusion was discontinued. However, diastolic blood pressure and mean arterial blood pressure were still significantly decreased thirty minutes after termination of infusion. Heart rate did not change during prostacyclin infusion but decreased significantly when infusion was terminated. PRA was not significantly affected by prostacyclin infusion. The 6-keto-PGF1 alpha level was about 8 times higher than the baseline value thirty minutes after initiation of prostacyclin infusion and approximately twice as high as the baseline value thirty minutes after termination of infusion. The decrease in mean arterial blood pressure coincided with the increase in 6-keto-PGF1 alpha. There was no correlation between mean arterial blood pressure and PRA, nor between PRA and 6-keto-PGF1 alpha. These results demonstrate that production of prostacyclin is not reduced in patients with essential hypertension, and heart rate and PRA are not changed by prostacyclin infusion, although prostacyclin decreases blood pressure.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Evaluation of a new systolic time interval, the Q-V peak: effects of heart rate, contractile state, and loading conditions in dogs.

The authors investigated the effects of alterations in heart rate, contractility, and loading conditions on a newly defined systolic time interval, the Q-V peak, in 46 anesthetized dogs. The Q-V peak was measured as the time from the beginning of the electrocardiographic Q wave to the moment at which the blood flow rate reached its peak in the ascending aorta as determined with an electromagnetic flowmeter. The Q-V peak did not change significantly as the heart rate was varied by atrial pacing between 70 and 110 beats/minute. The Q-V peak shortened when the contractility was augmented with dobutamine (p = 0.0001) and was prolonged when it was depressed with propranolol (p = 0.0001). However, the Q-V peak did not change significantly when the left ventricular end-diastolic pressure or the mean aortic blood pressure was increased to 130% or decreased to 70% of the baseline values. These findings suggest that one may also evaluate left ventricular performance by measuring the time to systole, which the authors define as the Q-V peak.

Animals↗
PubMed1992

Thyroid storm associated with probable subclinical hypoadrenocorticism in an elderly woman.

A 73-year-old woman was admitted to the hospital for severe persistent vomiting with fever, drowsiness, and weight loss. Elevated serum levels of thyroid hormones and the presence of a consciousness disorder with fever and vomiting led to the diagnosis of thyroid storm. A low normal concentration of serum cortisol, urinary 17-hydroxycorticosteroids and an elevated plasma level of corticotropin suggest that an inadequate adrenal reserve have been involved in the pathogenesis of the thyroid storm in this patient. She responded to the administration of intravenous methimazole and oral supersaturated potassium iodide solution.

17-Hydroxycorticosteroids↗