Biomedical subjects

K Harada

Publications and source records attributed to K Harada.

At least 1,423 records · Page 79Linked to original sources

PubMedDate not supplied

Wall motion velocities of abdominal aorta measured by tissue Doppler imaging in normal children.

Tissue Doppler imaging (TDI) offers a new technique for assessing aortic wall expansion/contraction velocities and may provide a noninvasive approach to aortic wall mechanics. The purpose of this study was to determine the normal values of abdominal aortic wall motion velocities and the effect of age on these velocities in normal children. We examined 103 normal children. Using TDI, maximum wall expansion velocity during systole (peak S) and maximum wall contraction velocity during diastole (peak D) were measured. M-mode diameter of the abdominal aorta and systolic, diastolic, and mean arterial pressures were measured. Aortic stiffness was measured as (I(n)[BP(syst)/BP(diast)])/(D(s)-D(d)/D(d), where I(n) is the natural log, D(s) is the maximal abdominal aortic diameter during systole, and D(d) is the abdominal aortic diameter at end-diastole. In all subjects, wall motion velocities of the abdominal aorta were recorded. The mean values for peak S and peak D were 4.23, 1.14 and 2.16, 0.45 cm/sec, respectively. Both peak S and peak D were low in infants and increased significantly with age (r = 0.63, p < 0.0001 and r = 0.36, p = 0.0002, respectively), systolic blood pressure (r = 0.42 and 0.47, respectively, p < 0.0001), and diastolic blood pressure (r = 0.24, p = 0.016 and r = 0.28, p = 0.0038, respectively). Aortic stiffness index of the abdominal aorta was constant with age and did not correlate with peak S or peak D. Abdominal aortic wall motion velocities can be easily assessed by TDI. Age-related changes in the aortic wall motion velocities are observed in normal children. This study provides baseline information for further quantitative assessment of arterial stiffness in children with congenital or acquired heart disease.

Adolescent↗

PubMedDate not supplied

Posterior descending coronary artery flow reserve assessment by Doppler echocardiography in children with and without congenital heart defect: comparison with invasive technique.

To evaluate whether transthoracic Doppler echocardiography can reliably measure coronary flow velocity and coronary flow velocity reserve (CFVR) in the posterior descending coronary artery (PD) in children, we examined 32 patients who had congenital heart disease (ventricular septal defect in 10, tetralogy of Fallot in 6, tricuspid atresia in 3, double-outlet right ventricle in 2, patent ductus arteriosus in 2, and aortic valve stenosis in 2) and 7 patients who had a history of Kawasaki disease without stenosis or aneurysm formation of the coronary artery. Average peak flow velocity (APV) in the PD was measured by transthoracic Doppler echocardiography at the time of intracoronary Doppler study. CFVR was defined as the ratio of hyperemic to basal APV. Clear envelopes of basal and hyperemic APV in the PD were obtained in 23 of 32 patients by transthoracic Doppler echocardiography. APV obtained from transthoracic Doppler echocardiography correlated highly with that from the Doppler guidewire method (r=0.91). The mean difference between transthoracic Doppler echocardiography and the Doppler guidewire method was 0.1+/-2.9. There was an excellent correlation between transthoracic Doppler echocardiography and the Doppler guidewire method for the measurements of CFVR (r=0.84). The mean difference between transthoracic Doppler echocardiography and Doppler guidewire was -0.016+/-0.198. Noninvasive measurement of coronary flow velocity and CFVR in the PD using transthoracic Doppler echocardiography accurately reflects invasive measurement of coronary flow velocity and CFVR by the Doppler guidewire method in pediatric patients with various heart diseases.

Adolescent↗

PubMedDate not supplied

Effects of acute preload reduction on myocardial velocity during isovolumic contraction and myocardial acceleration in pediatric patients.

We evaluated the effects of acute preload reduction with inferior vena cava (IVC) occlusion on myocardial velocities during systole (Sa), early (Ea) and late (Aa) diastole, isovolumic contraction (IVV), and myocardial acceleration (IVA) measured by tissue Doppler imaging (TDI) in pediatric patients. A total of 22 patients (5 +/- 3 years) were studied: 9 patients (4 +/- 3 years) with Kawasaki disease, 8 patients (6 +/- 3 years) with atrial septal defect and right ventricular (RV) volume overload, and 5 patients (5 +/- 4 years) with pulmonary stenosis and RV pressure overload. Using TDI, Sa, Ea, Aa, IVV were recorded at the base of the RV free wall from a four-chamber view. IVA was calculated by dividing IVV by the time interval from onset of IVV to the time at peak velocity of this wave. In each group, IVC occlusion caused significant decreases in peak Sa, peak Ea, and peak Aa (p < 0.05). However, IVV and IVA did not change during acute preload reduction. This study demonstrated the effects of acute preload reduction on TDI velocities. In contrast to peak Sa, peak Ea, and peak Aa, IVV and IVA were unaffected by preload within a physiological range.

Blood Pressure↗

PubMedDate not supplied

Coronary blood flow assessed by transthoracic echocardiography in neonates.

Coronary flow measurement has provided useful clinical and physiologic information. However, there is little information about values for coronary flow in normal neonates, much less neonates with congenital heart disease. The aim of this study was to assess coronary blood flow in normal neonates and to compare the results with those in infants with ventricular septal defect. The study groups consisted of 12 normal neonates and 9 infants with simple ventricular septal defect associated with pulmonary hypertension. Left ventricular dimension, left ventricular mass, and the diameter of the coronary vessel were measured by standard M-mode and two-dimensional echocardiography. Peak flow velocities, flow velocity integrals, and flow volumes in the left anterior descending and circumflex coronary arteries were measured. The flow signals from the left anterior descending and circumflex coronary arteries were recorded in 84% (10/12) and 17% (2/12), respectively, in the normal neonates and 78% (7/9) and 11% (1/9), respectively, in the patients. The left ventricular end diastolic diameter and mass were significantly lower in normal infants than in the infants with ventricular septal defect (1.56 +/- 0.11 vs 1.84 +/- 0.09 cm and 5.4 +/- 1.6 vs 8.8 +/- 0.8 g, respectively, p < 0.01). The mean peak diastolic velocity and the flow velocity time integral in the left anterior descending coronary artery were significantly lower in the normal neonates than in the patients (15 +/- 4 vs 28 +/- 6 cm/sec and 2.3 +/- 0.6 vs 5.9 +/- 1.5 cm, respectively, p < 0.01). The coronary flow volume was significantly lower in the normal neonates than in the patients (3.1 +/- 1.4 vs 7.9 +/- 4.7 ml/min, p < 0.05). However, the flow volume of the left anterior descending coronary artery/left ventricular mass did not show any significant difference between the two groups. Our study demonstrated in neonates that it is feasible to detect noninvasively and to evaluate the flow of the left anterior descending coronary artery under physiologic conditions and abnormal hemodynamic situations. Increased flow volume in the left anterior descending coronary artery in patients with ventricular septal defect may be a compensated mechanism for the increase in oxygen demand of hypertrophic myocardium of the left ventricle.

Blood Flow Velocity↗

PubMedDate not supplied

Body mass index can predict left ventricular diastolic filling in asymptomatic obese children.

To examine the effects of body mass index on left ventricular diastolic function, flow velocity patterns of the pulmonary vein and mitral valve were measured by pulse Doppler echocardiography in 21 asymptomatic obese children and were compared with those of an age-matched control population. The degree of obesity was calculated as (actual body mass index/ideal body mass index -1) x 100. The pulmonary venous flow indexes were peak systolic (S) and diastolic (D) velocities and peak D/S. The mitral inflow indexes were peak velocities of early diastole (E) and atrial contraction (A) and peak E/A. The pulmonary venous flow velocity pattern in obese patients was characterized by unchanged peak S, decreases in peak D (43 +/- 7 vs 51 +/- 8, p < 0.01) and peak D/S (0.98 +/- 0.19 vs 1.29 +/- 0.20, p < 0.01), suggesting the reduction in the early diastolic filling. The peak D/S decreased significantly with an increase in the percentage body mass index (r = -0.84, p < 0.01). In contrast to the pulmonary venous flow pattern (peak D > peak S) as seen in normal controls, all of the obese patients with > 70% over body mass index had abnormal pulmonary venous flow velocity patterns (peak D < peak S). The mitral flow velocity pattern in obese patients was also characterized by a decrease in early diastolic filling. However, these indices did not correlate with an increase in the percentage over body mass index. This study suggests that body mass index predicts the abnormality of left ventricular diastolic filling assessed by pulmonary venous flow patterns.

Adolescent↗

PubMedDate not supplied

Postnatal changes in left ventricular volume and contractility in healthy term infants.

To evaluate how the size of the ductus arteriosus affects neonatal left ventricular (LV) volume and contractility, we serially obtained two-dimensional and Doppler echocardiograms at 2, 12, 24, and 120 hours after birth in 20 healthy infants. LV volume was calculated by the biplanar Simpson's rule, and ductus arteriosus size with left-to-right shunting was measured by two-dimensional and Doppler echocardiography. At 2 hours, the ductus arteriosus was at its maximal size, and the LV end-diastolic volume was 1.2-fold higher than at the subsequent hours after birth. Additionally, there was a significant linear correlation between the end-diastolic volume and the ductal diameter. In contrast, the peripheral vascular resistance, derived from blood pressure measurements and Doppler echocardiography, was lowest at 2 hours of age. The mean normalized systolic ejection rate, an index of contractility, remained constant throughout the study period. These results suggest that alterations in the LV end-diastolic volume soon after birth depend on changes in ductal flow, which in turn is affected by ductal diameter, and that the neonatal left ventricle operates at its maximal performance with limited contractility during ductal patency.

Age Factors↗

PubMedDate not supplied

Postnatal left ventricular contractility in very low birth weight infants.

The objective of the study was to evaluate postnatal changes in left ventricular (LV) contractility in very low birth weight (VLBW) infants. An echocardiographic study comparing 18 VLBW infants without significant complications and 16 normal term infants was carried out at the Neonatal Intensive Care Unit in Akita University Medical Hospital, Japan. The echocardiographic examinations were performed within 6 hours of birth and on day 5. We obtained the relations between rate-corrected mean velocity of circumferential fiber shortening (mVcfc) and end-systolic wall stress (ESS), which were calculated from two-dimensional LV short-axis views to compensate for the distorted LV shape, and we compared these relations statistically. In both VLBW and term infants there were inverse linear correlations between mVcfc and ESS for each study period (p < 0.05). The regression line of VLBW infants had a lower y-intercept and a steeper slope than that of term infants at 6 hours of age but almost corresponded on day 5. It is concluded that the left ventricle of VLBW infants adapts to postnatal hemodynamic alterations with low contractility but operates with a contractile state similar to that of term infants on day 5.

Adaptation, Physiological↗

PubMedDate not supplied

Increase in pulmonary arterial diameter under prostaglandin E1 therapy in infants with cyanotic congenital heart disease.

We studied the change in pulmonary arterial diameter under prostaglandin E1 (PGE1) therapy in infants with ductus-dependent cyanotic heart disease (pulmonary atresia). Ten infants undergoing administration of PGE1 for more than 2 weeks were selected for this study. A classic Blalock-Taussig (BT) shunt was performed in seven patients and a modified BT shunt in three. The shunt was successful in all patients. The internal diameters of the right and left pulmonary arteries were measured before and after the start of PGE1 therapy using two-dimensional echocardiography. The pulmonary arterial index (PA index) was calculated to correct the diameters for body surface area. Both pulmonary arteries enlarged during the first week of PGE1 therapy in all 10 patients. Further increases in the two diameters were observed even after the first week of treatment in nine patients. Both the mean diameters at 2 weeks after the start of PGE1 were about 50% larger than the initial diameters (right; increased from 3.1 to 4.7 mm; left; increased from 3.0 to 4. 4 mm). Of the eight patients given PGE1 for more than 3 weeks, four showed no changes in pulmonary arterial diameters after the first 2 weeks and the remaining four showed a slight increase. PA indexes also showed a rapid increase during the first 2 weeks and no significant change thereafter. We suggest that, in infants with pulmonary atresia and small pulmonary arteries, the optimal pulmonary artery size for BT shunt insertion is achieved after 2 weeks of PGE1 infusion, with no further significant increase in size being observed after this time.

Alprostadil↗

PubMedDate not supplied

MRI findings of primary biliary cirrhosis: correlation with Scheuer histologic staging.

Magnetic resonance imaging (MRI) findings of primary biliary cirrhosis (PBC; currently regarded as a vanishing bile duct syndrome) are not established. In this report, we describe our preliminary analysis of the relation between MRI findings and histopathologic staging of PBC and review clinical, morphologic, and MRI findings of PBC especially focusing on the staging of PBC.

Diagnosis, Differential↗

PubMedDate not supplied

Intraarterial chemotherapy or chemoembolization for locally advanced and/or recurrent hepatic tumors: evaluation of the feeding artery with an interventional CT system.

PURPOSE: To evaluate the utility of an interventional CT system for intraarterial chemotherapy or chemoembolization for locally advanced and/or recurrent hepatic tumors. METHODS: Thirty-eight patients with locally advanced or recurrent hepatic tumors underwent 73 intraarterial contrast-enhanced CT (IA-CECT) examinations immediately before chemotherapy or chemoembolization. The degree of tumor vascularity on angiography and enhancement on IA-CECT was classified into three grades: no, mild, or marked vascularity. The IA-CECT grades were compared with the angiographic grades. RESULTS: Twenty-nine (69%) of 42 examinations that were interpreted as having no or mild vascularity on angiography were classified as marked enhancement on IA-CECT. Based on IA-CECT findings, the position of the catheter was changed in 14 (19%) of 73 CT examinations. The reasons for the reposition were as follows: weak or no enhancement of the tumor (n = 11) or strong enhancement of the gallbladder wall (n = 3). The treatment strategy was changed in three patients (8%). No major complications relating to the interventional procedures were observed. CONCLUSIONS: IA-CECT is a reliable method when evaluating the perfusion of the tumor and adjacent normal tissues. The interventional CT system is useful for performing safe and effective intraarterial chemotherapy or chemoembolization in patients with locally advanced and/or recurrent hepatic tumors.

Adult↗

PubMedDate not supplied

Factors controlling the size of proteinoid microspheres.

Proteinoid microspheres were prepared from aqueous solutions containing various metal halides under different pH values and ionic strengths. The effects of pH and ionic strength on the diameter of the microspheres and also the solubility of the proteinoid in hot solution (100 degrees C) were investigated by means of different physiochemical measurements. It is found that, under high ionic strength, the diameter of the microsphere is mainly affected by the salt concentration, while the pH of the system is the main factor when the ionic strength is low. Moreover, the change in the solubility with ionic strength and pH is found to show a striking resemblance to that in the diameter with both factors. On the basis of these results, the external and internal factors controlling the size of proteinoid microspheres are clarified, and a plausible mechanism of the proteinoid microsphere formation under prebiotic conditions is also discussed.

Hydrogen-Ion Concentration↗

PubMedDate not supplied

Evaluation of myelination by means of the T2 value on magnetic resonance imaging.

The progress of myelination in the cerebrum was evaluated by visual inspection, and magnetic resonance (MR) imaging and the transverse relaxation time (T2) was calculated from double echo images. Twenty-three pediatric cases, who did not show intracranial organic changes on MR examination, were included. The T2 values in the corpus callosum (CC), frontal deep white matter (FWM), occipital deep white matter (OWM) and centrum semiovale (CS) were calculated, and the changes in these values with age were followed. During the first year of life, a rapid decrease in the T2 value was seen, followed by a more gradual decrease. The T2 value seemed to reach the adult level between 2 and 3 years of life in all areas examined. The T2 values between 2 and 16 years in CC, FWM, OWM and CS were 59.7 +/- 3.6, 64.5 +/- 5.2, 69.8 +/- 4.8 and 66.3 +/- 3.3 ms (mean +/- S.D.), respectively. The T2 values in patients with clinically diagnosed Pelizaeus-Merzbacher disease (PMD) and late onset Krabbe disease were also calculated. In PMD, non-progressive prolongation of the T2 value was observed in all areas. In late onset Krabbe disease, on the other hand, progressive prolongation of the T2 values was mainly demonstrated in OWM and the posterior part of CS. These results suggest that the T2 value in the cerebral white matter allows more objective judgement than visual inspection, and makes it possible to clarify the mechanism underlying abnormal myelination, i.e. progressive or not.

Adolescent↗

PubMedDate not supplied

MR diffusion imaging in Pelizaeus-Merzbacher disease.

A case of classical type Pelizaeus-Merzbacher disease was reported. This patient exhibited marked motor and mental developmental delay, and nystagmus, with a positive familial history. Electrophysiological studies, such as on brainstem auditory evoked potentials, blink reflex and somatosensory evoked potentials, suggested marked disturbance of nerve conduction in CNS. T2-weighted magnetic resonance (MR) images revealed non-progressive diffuse T2 prolongation of cerebral white matter after a 2-year interval, indicating congenital hypomyelination in CNS. A newly developed magnetic resonance diffusion imaging method demonstrated the existence of diffusional anisotropy in the corpus callosum, internal capsule, and white matter of the frontal lobe. Although the diffusional anisotropy was considered to depend on the well-developed multiple layers of myelin around the axons, the imaging data of this patient demonstrated that the diffusional anisotropy did not necessarily depend on those multiple layers. These results may indicate the potential usefulness of MR diffusion imaging, combined with electrophysiological studies and conventional MR imaging, for analyzing the lesions of the cerebral white matter.

Anisotropy↗

PubMedDate not supplied

Inclined coronal scans in thoracic MR imaging.

To determine the value of inclined coronal MR in diagnosing thoracic abnormalities, the multiscan coronal and inclined coronal spin echo MR images of 4 normal subjects and 10 patients with thoracic abnormalities were reviewed. The major airway such as trachea, main bronchi and lobar bronchi, left atrium and its junctions with pulmonary veins required less slices for visualization on inclined coronal images than on standard coronal images, and these normal structures and the lesions located in this region were easy to evaluate in several cases. The left pulmonary artery, especially the upper and lower lobe branches were better visualized on inclined coronal images. The pericardium and the other great vessels were equally visualized on inclined and on standard coronal images. There was no case in which normal structures or lesions were more difficult to demonstrate on inclined coronal images compared with standard coronal images. We conclude that an inclined coronal MR scan of the thorax is valuable to evaluate the mediastinal structures and lesions, especially in diagnosing the abnormalities of the airway, left atrium and its junctions with pulmonary veins.

Adult↗

PubMedDate not supplied

Arterial oxygen desaturation during non-sedated diagnostic upper gastrointestinal endoscopy.

We studied oxygen saturation (SaO2) using a pulse oximeter in 120 patients undergoing non-sedated diagnostic upper gastrointestinal endoscopy. The baseline SaO2 was 98.3 +/- 1.0%. During the procedure, absence of oxygen desaturation (SaO2 > or = 95%) was found in 56%, mild oxygen desaturation (95% > SaO2 > or = 90%) in 35%, and severe oxygen desaturation (SaO2 < 90%) in 9%. Age (p = 0.56), gender (p = 0.47), smoking (p = 0.35), hemoglobin level (p = 0.52), body mass index (p = 0.27), or total endoscopy time (p = 0.72) was not related to the degree of oxygen desaturation. These results suggest that oxygen desaturation is frequently observed during non-sedated diagnostic upper gastrointestinal endoscopy although severe oxygen desaturation, which may induce rare but serious cardiopulmonary events, is not common. Furthermore, we cannot predict in which patients desaturation will occur. We therefore recommend continuous monitoring of arterial oxygenation in all patients during the procedure.

Adult↗

PubMedDate not supplied

Arterial oxygen desaturation during non-sedated diagnostic upper gastrointestinal endoscopy in patients with cirrhosis.

Oxygen saturation was studied with a pulse oximeter in 80 patients with cirrhosis (44 Pugh-Child's class A, 25 class B, and 11 class C) and 80 controls undergoing diagnostic esophagogastroduodenoscopy (EGD). No narcotic agent was used during the procedure. Baseline SaO2 was significantly lower in cirrhotics than in controls (97.7 +/- 1.0% versus 98.4 +/- 0.9%, p < 0.01). However, nadir SaO2 during EGD was similar for controls and cirrhotics (94.7 +/- 3.0% versus 94.9 +/- 3.3%, NS). Significant hypoxia was found in 29 (36%) control patients: mild hypoxia (95% > nadir SaO2 > or = 90%) in 22 patients and severe hypoxia (nadir SaO2 < 90%) in 7. Similarly, significant hypoxia was noted in 28 (35%) cirrhotic patients: mild hypoxia in 21 and severe hypoxia in 7. The mean duration of significant hypoxia during total EGD time was also similar for controls and cirrhotics (7.4 +/- 6.3% versus 9.2 +/- 10.7%, NS). When the degree of hypoxia during EGD was correlated with the severity of liver disease, analysis of variance (ANOVA) failed to show a significant relationship between Pugh-Child's class and nadir SaO2 or duration of significant hypoxia during total EGD time. These results suggest that oxygen desaturation during EGD occurs both in cirrhotic patients and in controls. We therefore conclude that a population of patients with cirrhosis does not have an increased risk of oxygen desaturation during non-sedated EGD.

Body Mass Index↗

PubMedDate not supplied

Intratracheal administration of microcystin-LR, and its distribution.

Microcystin-LR (MCLR) was injected into mice intratracheally, absorption from the lungs was easy and it was confirmed that both the cause of death and lethality dose level were the same as by intraperitoneal injection treatment. An immunostaining method revealed that there was a time lag of about 60 min before accumulation of MCLR, and that it caused bleeding in the liver. Clearance from internal organs took about 2 weeks; during the initial stage (the first 2 days), the small intestine, kidney, cecum and large intestine were already involved. However, even after 2 weeks, small amounts of MCLR were still present in epithelial cells in the gastrointestinal mucosa.

Absorption↗

PubMedDate not supplied

Bis(hydroxamamide)-based bifunctional chelating agent for 99mTc labeling of polypeptides.

To develop chelating molecules that provide 99mTc-labeled polypeptides of high in vivo stability and high specific activities under mild reaction conditions, an asymmetrical bis(benzohydroxamamide) compound with an amine group, 4'-aminomethyl-N,N'-trimethylenedibenzohydroxamamide [NH2-C3(BHam)2], was designed and synthesized. The amine residue of NH2-C3(BHam)2 was converted to a maleimide group by reaction with N-succinimidyl-6-maleimidohexanoate, and the conjugation product was coupled to thiol groups of a monoclonal antibody against osteogenic sarcoma (OST7, IgG1) pretreated with 2-iminothiolane to prepare C3(BHam)2-OST7. 99mTc radiolabeling of C3(BHam)2-OST7 was performed by the exchange reaction with [99mTc]glucoheptonate. [99mTc]C3(BHam)2-OST7 was further characterized using directly radioiodinated OST7 ([125I]OST7) and [111In]labeled OST7 with 1-[4-[(5-maleimidopentyl)amidobenzyl]ethylenediamine-N,N, N'N'-tetraacetic acid (EMCS-Bz-EDTA) as references. [99mTc]C3(BHam)2-OST7 was obtained with radiochemical yields of over 94% at protein concentrations as low as 0.2 mg/mL at room temperature for 1 h. [99mTc]C3(BHam)2-OST7 remained stable after incubation in freshly prepared murine plasma and in the presence of cysteine. Similar binding affinities to tumor cells were observed between [99mTc]C3(BHam)2-OST7 and [125I]OST7. When injected into normal mice, [99mTc]C3(BHam)2-OST7 exhibited radioactivity levels in the blood similar to [111In]-EMCS-Bz-EDTA-OST7 up to 24 h postinjection with significantly faster elimination rate of the radioactivity from the liver. In nude mice bearing osteogenic sarcoma, no significant differences were observed in the radioactivity levels in the blood and the tumor between [99mTc]C3(BHam)2-OST7 and [125I]OST7 at 24 h postinjection. These findings indicated that C3(BHam)2 provided 99mTc chelate of high stability at low concentrations even when conjugated to an intact antibody. Such characteristics render bis(hydroxamamide) compounds useful as chelating molecules for preparation of 99mTc-labeled polypeptides.

Amides↗