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Biomedical subjects

M Kojo

Publications and source records attributed to M Kojo.

16 recordsLinked to original sources
PubMed2001

Reduction of carotid artery blood flow in pediatric patients with syncope: evaluation with head-up tilt test.

We investigated the effect of postural changes on cerebral circulation by measuring carotid artery blood flow (CABF) in the supine position and during head-up tilt (HUT) test using a Doppler flow meter. Subjects included 10 patients with neurally mediated syncope, 10 patients with orthostatic intolerance, 8 with epilepsy, aged between 8 to 24 years (mean +/- SD, 13.9 +/- 4.1 years). The test caused pallor and dizziness in 16 patients (symptomatic), while no symptoms were recognized in the other 12 patients (asymptomatic). Significant reductions in the mean CABF (Fm), maximum CABF (Fs) and minimum CABF (Fd), components of the CABF waveform, were noticed during HUT compared to before HUT (supine), and these reductions in symptomatic patients were more severe than those in asymptomatic patients (Fm: - 2.8 +/- 2.0 SD vs - 0.7 +/- 1.4 SD; Fs: - 2.7 +/- 1.5 SD vs - 0.9 +/- 1.3 SD; Fd: - 4.5 +/- 2.8 SD vs - 2.2 +/- 2.1 SD). Reductions in Fm, Fs and Fd in the symptomatic patients during HUT lasted longer than those of the asymptomatic patients, being statistically significant for Fm and Fs (Fm: p < 0.01; Fs: p < 0.05). The criteria during HUT for distinguishing neurally mediated syncope (NMS) from others was Fs: < - 4 SD and Fd: < - 5 SD. Our data suggest that reduction of CABF should be carefully evaluated for the diagnosis of neurally mediated syncope in pediatric patients. Such a reduction might be an essential mechanism of syncopal attacks.

Adolescent↗
PubMed2000

Reduction of carotid arterial blood flow in ventricular septal defect associated with severe congestive heart failure.

After diagnosing abnormality of cardiac and carotid-cerebral circulation in an infant with isolated ventricular septal defect (VSD) associated with severe congestive heart failure, the authors measured the carotid arterial blood flow volume (CABF). At 3 months, the patient was not thriving and had dyspnea because of severe congestive heart failure. The authors measured the VSD size/body surface area (BSA) ratio relative to the predicted value of the left ventricular end-diastolic dimension (%LVEDd), left-to-right shunt ratio (Qp/Qs), and the small stroke volume (SV)/BSA using echocardiography and cardiac catheterization. The mean, maximum, and minimum CABF (mean CABF, maxCABF, and minCABF) among R-R intervals on electrocardiogram were measured by Doppler flowmetry in this patient and 5 healthy age-matched control children. The patient had a large VSD size/BSA ratio (37.9 mm/m2), %LVEDd (164%), and Qp/Qs (3.8), and a small SV/BSA ratio (18 mL/m2). The mean CABF, maxCABF, and minCABF were significantly lower than those of control children (VSD patient vs. controls; 2.7 +/- 0.4 vs. 4.5 +/- 0.6, 6.1 +/- 0.9 vs. 12.0 +/- 2.1, 1.2 +/- 0.2 vs. 1.7 +/- 0.4 mL/sec (mean +/- S.D.)), respectively (p < 0.01). The authors' results showed abnormal cardiac and carotid-cerebral circulation in an infant with large VSD associated with severe congestive heart failure.

Blood Volume↗
PubMed1999

Two-dimensional autoregressive analysis of carotid artery blood flow waveform in children with isolated atrial septal defect.

BACKGROUND: The aim of the present study was to analyze the carotid artery blood flow waveform, using a two-dimensional autoregressive modeling approach and component analysis, and to determine the relation between cardiac contractility, peripheral and cerebral circulation and characteristic values of component activities of carotid artery blood flow waveform in patients with atrial septal defect (ASD), with or without congestive heart failure. METHODS AND RESULTS: We analyzed the carotid artery blood flow waveform of nine patients with ASD and 35 normal controls using a two-dimensional autoregressive modeling approach. The component of impulse response was divided into six groups according to the damping frequency: (i) group I, 0 Hz; (ii) group II, 1-5 Hz; (iii) group III, 5-8 Hz; (iv) group IV, 8-13 Hz; (v) group V, 13-17 Hz and (vi) group VI, > 17 Hz. The decrease of impulse response power-density in patients of groups I, II, III and IV and the prolongation of damping time for patients in groups I and II were particularly noticeable in two ASD patients, whose pulmonary to systemic blood flow ratio was more than 2.7 and whose left ventricular stroke volume was less than 33.1 mL/m2. The power-density of groups I and II varied with cardiac contractility and the power-density of groups III and IV varied with cerebral circulation. In contrast, the damping time of groups I and II changed with the reflection velocity from the position of arterial reflection against blood flow from left ventricle. CONCLUSIONS: These results may be influenced by the decrease in left ventricular stroke volume and velocity in arterial reflection.

Blood Circulation↗
PubMed1998

Normal developmental changes in carotid artery diameter measured by echo-tracking.

We examined the developmental changes in carotid arterial diameter and its change with pulsatile pressure in infants and children using the phase-locked echo-tracking method. The mean, maximum systolic, and minimum diastolic carotid arterial diameter and pulsating diameter changes were measured in 95 healthy children aged 1 month to 13 years. The mean, maximum, and minimum carotid arterial diameter increase significantly and exponentially with age, body weight, height, and body surface area, and the correlation coefficient was highest with body surface area. The change in carotid arterial diameter with pulse pressure increased gradually until 2 to 3 years of age. Our results suggest that the maturational changes in carotid diameter and the dynamic changes in the diameter reflect changes in the carotid-cerebral circulatory system. The noninvasive measurement of the carotid diameter and pulsating diameter changes by a phase-locked echo-tracking method is useful for examining carotid-cerebral circulatory disorders.

Adolescent↗
PubMed1997

Mutations induced in Drosophila during space flight.

To examine the possible effects of space radiation on living organisms, fruit flies Drosophila melanogaster were loaded on the US Space Shuttle Endeavour, and after the flight we have analyzed two types of mutations, sex-linked recessive lethal mutations induced in male reproductive cells and somatic mutations which give rise to morphological changes in hairs growing on the surface of wing epidermal cells. Wild type strains and a radiation-sensitive strain mei-41 were used. The frequencies of sex-linked recessive lethal mutations in flight groups were 2 and 3 times higher for wild type Canton-S and mei-41 strains, respectively, than those in ground control groups. By contrast, the frequencies of wing-hair somatic mutations differed little between flight and control groups. The possibility that the space environment causes mutations in certain types of cells such as male reproductive cells, is discussed.

Animals↗
PubMed1996

Normal developmental changes in carotid arterial blood flow measured by Doppler flowmetry in children.

We examined the developmental changes in carotid arterial blood flow in a group of neonates, infants, and children using a Doppler flowmeter. The mean, maximum and minimum carotid arterial blood flow (CABF) were measured serially in 35 healthy newborns during the first 5 days of life (total 175 records), and in 62 healthy children aged 1 month to 13 years. In newborns, the mean CABF increased significantly on the second day of life, while the maximum and minimum CABFs increased significantly every day during the first 3 days of life. The mean, maximum, and minimum CABFs increased steadily and significantly in those older than 1 month but reached a plateau after 2 to 4 years of age. Our results indicate that CABF changes with age in early life, reflecting a change in cardiac contraction and carotid-cerebral circulatory system. The measurement of CABF by Doppler flowmetry may be useful for examining cardiac and carotid-cerebral circulatory disorder.

Adolescent↗
PubMed1996

[Estimation of SIDS with measurement of cardio-respiratory contribution ratio through multivariate autoregressive modelling approach].

We obtained the cardio-respiratory impulse response and noise contribution ratio to study the central respiratory control system in one case of Ondine's curse, one case of sleep apnea syndrome and 34 cases of preterm infants, using multivariate autoregressive analysis. In Ondine's curse, the noise contribution ratio decreased during sleep. In the sleep apnea syndrome, the noise contribution ratio before apnea and after apnea decreased. In the preterm infants, the noise contribution ratio increased with the conceptional age. From these results, we concluded that the central cardio-respiratory control system was disturbed in Ondine's curse, sleep apnea syndrome and preterm infants. The cardio-respiratory impulse response using a multiple autoregressive analysis was useful for prediction of sudden infant death syndrome.

Heart Rate↗
PubMed1995

Multivariate autoregressive analysis of carotid artery blood flow waveform in an infant of a diabetic mother with cardiomyopathy.

We analyzed the carotid artery blood flow waveform (CABFW) of an infant of a non-insulin dependent diabetic mother with hypertrophic cardiomyopathy (IDM cardiomyopathy) through multivariate autoregressive analysis and compared the developmental change of his CABFW with that of normal newborns. The total power was lower than normal newborns on the second and third day of life when his heart dysfunction was severe, and elevated on the fifth day of life when normal-heart function was recovered. The power of component 3 (C3), of which the damping frequency was 7-11 Hz, was slightly high on the second and third day of life and it decreased to the normal range on the fifth day of life by component analysis. In contrast, the power of C3 increased with decreasing resistance index of anterior cerebral artery (RI of ACA) which shows the cerebral vascular resistance of normal newborns. These results suggest that the carotid artery blood flow volume decreased by low cardiac output and the cerebral vascular resistance decreased to maintain the cerebral circulation, when the heart dysfunction was severe.

Adult↗
PubMed1995

Developmental change in carotid artery blood flow waveform by component analysis in children.

The carotid artery blood flow waveform (CABFW) is regarded as a summation of cardiac impulse responses. These impulse responses are divided into several components through a two-dimensional autoregressive modelling approach. Using this approach, we determined the developmental change in CABFW in 94 normal subjects from the neonatal period to adolescence. Our analysis demonstrated that: (i) the total power of impulse response increased significantly with increasing age. The component of impulse response was divided into six groups according to the damping frequency: group I (0 Hz), group II (1-5 Hz), group III (5-8 Hz), group IV (8-13 Hz), group V (13-17 Hz) and group VI (> 17 Hz); (ii) the power-density and the damping time of group I and II impulse response increased significantly with increasing age; (iii) the power-density and percent power of group III impulse response and power-density of group IV impulse response increased significantly with increasing age. Our results indicated that CABFW contained some regular impulses and that group I, II, III and IV, which were influenced by several factors, including cardiac contraction and the compliance and frictional forces of the carotid artery, appeared to be important to the developmental change of CABFW in children.

Adolescent↗
PubMed1995

[Multivariate autoregressive analysis of carotid artery blood flow waveform in a newborn with multicystic encephalomalacia].

We analyzed the carotid artery blood flow waveform (CABFW) through multivariate autoregressive analysis in a case with multicystic encephalomalacia (MCE) after neonatal asphyxia and compared the result with those of 35 healthy newborns. The total power of CABFW was at the -2 SD level of the value for 35 healthy newborns, and the power, % power, bio-informing amounts and damping time of component 3 (damping frequency 11.15 Hz) were less than -2 SD of the values in 35 healthy newborns. The Pulsatility Index (PI) of anterior cerebral artery (ACA) was high (0.76). These results suggest that cerebral blood flow decreases because of cerebral vasoconstriction in MCE after neonatal asphyxia.

Brain Diseases↗
PubMed1993

Cardio-respiratory control in an infant with Ondine's curse: a multivariate autoregressive modelling approach.

We applied spectral analysis through multivariant autoregressive model fitting [1] to RR interval (RRI) and respiratory (RES) oscillation obtained during quiet sleep in an infant with congenital central hypoventilation syndrome (Ondine's curse), a child with obstructive sleep apnea, and two healthy children. Power spectra, impulse response and noise contribution ratio between RRI and RES oscillation were calculated by using a minicomputer PFU-1200 (FACOM) to determine the structure of the feedback system between RRI and RES within the central nervous system. We found that the respiratory noise contribution ratio to RRI was significantly smaller in Ondine's curse (37 +/- 7.7%, at 0.23 Hz) than in obstructive sleep apnea (90 +/- 6.7%, at 0.39 Hz) and healthy subjects. We postulate that the result shows disturbance of the central autonomic control of breathing and heart rate in Ondine's curse.

Autonomic Nervous System↗
PubMed1993

[An experience with surgical treatment for mucoepidermoid carcinoma of the lungs].

Mucoepidermoid carcinoma (MEC) of the lungs is thought to arise in the bronchial glands. It is a tumor that rarely develops and it has a low grade of malignancy. In this paper, we describe one case of infiltrative MEC, which we were able to diagnose preoperatively. Surgery revealed a high grade malignancy which is reported here with a discussion based on the related literature. The patient was a 63-year-old male who was referred to our hospital by another physician due to a cough and left chest pain. A simple chest X-ray revealed a tumor shadow and a fascicular shadow on its periphery in the upper left lobe. Bronchoscopy disclosed complete circumferential stenosis at B1+2,3 and reddening from this region to the main bronchus, but it was impossible to directly confirm the tumor. Pulmonary arterography did not depict the left upper pulmonary vein, but obstruction due to a tumor of that vein was observed. Given the above findings, under a diagnosis of infiltrative MEC, a left total lobectomy accompanied by a combined left atriectomy was performed. Although most cases of MEC have a low grade malignancy, there have been some reported cases with a very high grade of malignancy. Therefore, evaluation of the progress of this type of carcinoma by preoperative diagnosis as well as radical excision appropriate to lung cancer are considered to be important.

Carcinoma, Mucoepidermoid↗
PubMed1989

The inhibitory effects of cimetidine on elimination and distribution of propranolol in rats.

We studied the effects of cimetidine on the pharmacokinetics, blood and tissue distribution and plasma protein binding of propranolol in rats. The plasma disappearance of propranolol after a 10 mg/kg intravenous injection and oral administration were fitted to a two compartment open model. In the cimetidine treated rats, the area under concentration curve after an intravenous injection (AUCiv) was increased by 64% and the plasma total body clearance (Cltot) and the rate constant at the terminal phase (beta) were decreased by 38% and 33% of those of the non-treated rats, respectively. The area under the concentration curve after oral administration (AUCpo) was increased by 62% and the plasma oral clearance (Clpo) was decreased by 39% by cimetidine treatment, whereas the bioavailability (F) was not changed. The hepatic blood flow rate (Qh) and the product of the plasma unbound fraction and the hepatic intrinsic clearance (fp x Clint,h) calculated from Cltot and Clpo were decreased by 30% and 39%, respectively. The blood-to-plasma concentration ratio (Rb) and the tissue-to-plasma concentration ratio (Kp) of propranolol were not affected by cimetidine treatment, while the binding constant (Kb) in plasma was decreased by 45%. The plasma unbound fractions (fp) of propranolol were increased by 25-70% in the in vivo plasma concentration range (0.1-1.0 microgram/ml) resulting in the decrease of tissue-to-plasma unbound concentration ratio (Kp,u) in lung, heart, spleen, brain and muscle. Cimetidine was shown to have the inhibitory effects on elimination and distribution of propranolol in rats.

Administration, Oral↗