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Biomedical subjects

Y Hada

Publications and source records attributed to Y Hada.

At least 19 recordsLinked to original sources
PubMed2006

Latency differences of N20, P40/N60, P100/N140 SEP components after stimulation of proximal and distal sites of the median nerve.

The latencies of SEP N20, P40, N60, P100, and N140 components were measured after stimulation of two different sites, and the differences in relation to conduction velocity and their central functions are discussed. Subjects were 8 healthy right-handed males (age 22-31 years, height 164-184 cm). An electrical pulse of 200micro sec duration with an intensity of 2 times the motor threshold was delivered to the wrist and to the elbow alternately at a random rate of 0.1 to 0.3 Hz. Recording electrodes were Cz', C3', and C4' referenced to linked ears. Analysis time was 50 msec before and 450 msec after the stimulus. The band pass was 0.5 Hz to 2 kHz. Subjects were asked to mentally count the number of stimuli. The averaging was interrupted after every 16 to 24 stimuli and checked to determine whether the subject was attentive to the stimuli by verifying the number of stimuli counted. A total of 100 responses each from elbow and wrist stimuli were averaged. Differences in peak latency between elbow and wrist stimuli for N20, P40, N60, P100, and N140 were 3.7 +/- 0.7 msec, 5.0 +/- 1.8, 4.3 +/- 1.2, 8.1 +/- 6.3, and 7.4 +/- 2.6 msec, respectively. According to the latency differences, SEP components can be divided into 3 groups: the shortest difference for N20, medium difference for P40 and N60 and longest difference for P100 and N140. Similar latency differences and similar potential distribution for P40 and N60, and for P100 and N140, and their differences from N20 confirmed that each of N20, P40/N60, and P100/N140 has a different function centrally. In addition, central processing time was longer with the more distal site stimulation.

Adult↗
PubMed2001

Measurement of plasma brain natriuretic peptide level as a guide for cardiac overload.

OBJECTIVES: We examined whether measurement of the plasma BNP concentrations might be useful for the early diagnosis of the existence and severity of disease in patients with heart disease in daily clinical practice. METHODS AND RESULTS: The plasma BNP and ANP concentrations in 415 patients with heart disease and hypertension and 65 control subjects were measured. Patients with heart disease had higher plasma BNP and ANP concentrations than did those with hypertension or control subjects. Among the etiology of cardiac diseases, specifically dilated cardiomyopathy and hypertrophic cardiomyopathy, was associated with the highest plasma BNP concentrations, whereas dilated cardiomyopathy was associated with the highest plasma ANP concentrations. Plasma BNP concentrations showed an increase as the severity of the heart disease, as graded according to the NYHA classification of cardiac function, increased. In both patients with heart disease and hypertension, the plasma BNP values were higher in those who had abnormalities in their echocardiogram and electrocardiogram as compared to those without any abnormalities. The plasma BNP levels also showed a significant correlation with left ventricular wall thickness and left ventricular mass. On the other hand, the plasma ANP levels showed significant correlations with left ventricular dimension. Receiver operative characteristic analysis revealed that plasma BNP levels showed substantially high sensitivity and specificity to detect the existence of heart diseases. CONCLUSION: Measurements of the plasma BNP concentrations is useful to detect the existence of the diseases, and abnormalities of left ventricular function and hypertrophy in patients with heart disease in daily clinical practice.

Atrial Natriuretic Factor↗
PubMed2001

Genomic analysis of a mouse model of immunoglobulin A nephropathy reveals an enhanced PDGF-EDG5 cascade.

The molecular mechanism of immunoglobulin A nephropathy (IgAN), the most common primary renal glomerular disease worldwide, is unknown. HIGA (high serum IgA) mouse is a valid model of IgAN showing almost all of the pathological features, including mesangial cell proliferation. Here we elucidate a pattern of gene expression associated with IgAN by analyzing the diseased kidneys on cDNA microarrays. In particular, we showed an enhanced expression of several genes regulating the cell cycle and proliferation, including growth factors and their receptors, as well as endothelial differentiation gene-5 (EDG5), a receptor for sphingosine 1-phosphate (SPP). One of the growth factors, platelet-derived growth factor (PDGF) induces a marked upregulation of EDG5 in proliferative mesangial cells, and promotes cell proliferation synergistically with SPP. The genomic approach allows us to identify families of genes involved in a process, and can indicate that enhanced PDGF-EDG5 signaling plays an important role in the progression of IgAN.

Animals↗
PubMed2001

Effects of stimulus intensity on latency and conduction time of short-latency somatosensory evoked potentials.

We studied the effect of stimulus intensity on latencies of short-latency somatosensory evoked potentials (SSEP) by measuring both onset and peak latencies individually. The latencies of N9, N13, N20 and N9-N13 peripheral conduction time (PCT) of median nerve (MN) SSEP, and N8, N23, P37 and N8-N23 PCT of tibial nerve (TN) and sural nerve (SN) SSEP significantly shortened with increasing stimulus intensity by onset latency measurement. However, those latencies by peak latency measurement were less significantly shortened or had only a trend of latency shortening without statistical significance. In contrast to PCT, N13-N20 central conduction time (CCT) of MN-SSEP and N23-P37 CCT of TN- or SN-SSEP showed no latency changes with the increased stimulus intensity by both onset and peak latencies measurement. As peak latencies had greater interindividual variability than onset latencies shown by larger standard deviation, shortening of onset latencies were more consistent than that of peak latencies. We think shortening of onset latencies indicates the recruitment of faster conduction fiber along with increased stimulus intensity. As the degree of latency shortening was less if stimulus intensity was above 2.5 times sensory threshold, the stimulus intensity greater than 2.5 times the sensory threshold should be used for clinical application.

Adult↗
PubMed1999

Are Metallic Markers Necessary for Coronary Artery Bypass Grafts? A Study Using X-ray Computed Tomography and Selective Graft Angiography.

Using X-ray computed tomography (CT) and selective graft angiography, the authors studied the necessity of metallic markers in coronary artery bypass grafts on 45 patients (mean age 57.2 years) with 87 saphenous vein grafts. Eight patients had 17 markers. X-ray CT was performed after surgery using an apparatus with a 1-second scanning time. Noncontrast X-ray CT was performed on horizontal sections, at 5-mm intervals, from the lower margin of the aortic arch to the lower left ventricle. A contrast medium was then injected into the antecubital vein (3 ml/second, total 30 ml) in one cross-section at the level of bifurcation of the pulmonary artery. Aortography (60 degrees in the left anterior and oblique positions, 20 ml/second, total 40 ml) was performed concurrently. Selective graft angiography was taken in the same direction, using 4 cm right of the Judkins with reference to the aortographic image and position of five clips on the sternum. Aortography revealed 79 patent and 8 occluded grafts. Selective graft angiography was easily performed even in grafts without markers. A cross-section of the occluded graft could not be seen with X-ray CT. Grafts with markers were often masked by artifacts produced by markers on X-ray CT. The number of observed graft slices (marker-positive grafts) was only 1.2 +/- 1.1 slices, significantly (p < 0.01) lower than marker-negative grafts (4.1 +/- 3.1 slices). In particular, the number of marker-positive right coronary artery grafts was 0.4 +/- 0.9 slices. Four of five right coronary artery grafts were unobservable due to artifacts. In grafts without markers, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of X-ray CT to graft patency were 100%, 85.7%, 98.4%, 100%, and 98.6%, respectively. This study suggests that metallic markers may not be necessary for coronary artery bypass grafts.

Journal Article↗
PubMed1999

Differential expression of immediate-early genes, c-fos and zif268, in the visual cortex of young rats: effects of a noradrenergic neurotoxin on their expression.

We investigated the expression pattern of two immediate-early genes, zif268 and c-fos, under various visual conditions using immunohistochemical and northern blot analysis in the visual cortex of young rats. The basal expression of c-fos was low and was further reduced by dark rearing that lasted for one week. A marked and transient increase was induced upon visual stimulation applied immediately after dark rearing. Zif268 showed a relatively high basal level. Its expression was reduced by dark rearing of the animals, but returned rapidly to the basal expression level following the introduction of light. Administration of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, a selective noradrenergic neurotoxin, suppressed the basal expression of c-fos messenger RNA. The response of c-fos to photo-stimulation was also significantly lower in the visual cortex of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine-treated young rats. In contrast, no significant change in zif268 expression was detected between normal and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine-treated animals. These findings suggest that differential expression of these immediate-early genes is involved in the activity-dependent regulation of cortical function. One possibility is that the noradrenergic system controls cortical function, including plasticity, by modifying the expression of c-fos.

Age Factors↗
PubMed1999

[Radiotherapy alone for elderly patients with stage III non-small cell lung cancer].

We undertook a retrospective study of elderly patients with stage III non-small cell lung cancer who had been treated solely with radiotherapy during the period 1986 to 1995. Our study was designed to assess the influence of age on survival and malnutrition in patients aged 75 years or older (elderly group) and patients aged 74 years or younger (younger group). Radiotherapy alone resulted in a median survival period of 11.5 months in the younger group and 6.3 months in the elderly group (p = 0.0043). With the Cox multivariate model, good performance status, age less than 75 years, and good response were significant favorable independent predictors. Furthermore, the elderly group patients more frequently died of respiratory infections and had lower prognostic nutritional indexes than the younger group patients before and after radiotherapy. These findings suggested elderly patients with stage III non-small cell lung cancer who had been treated with radiotherapy alone had a poor prognosis and that malnutrition caused by radiotherapy was a factor contributing to the risk of death from respiratory infection in such patients.

Age Factors↗
PubMed1999

Effects of monocular enucleation on parvalbumin in rat visual system during postnatal development.

PURPOSE: To evaluate the hypothesis that the expression of the calcium-binding protein parvalbumin (PV) in a subpopulation of gamma-aminobutyric acid (GABA)ergic neurons is an appropriate molecular marker for the effect on ocular dominance plasticity of monocular deprivation during the postnatal sensitive period. METHODS: Long-Evans rats underwent monocular enucleation immediately before eye opening (postnatal day [P] 14). Immunohistochemical analysis using anti-PV antibody was performed on the superior colliculus (SC) and lateral geniculate nucleus (LGN) at P45. In the visual cortex (VC) developmental changes in immunoreactivity were also examined at the ages of P17, P20, P27, and P45. Northern blot analysis for PV mRNA was also performed at P45. Changes in PV expression in the visual system of these rats were evaluated by use of a computer-based quantitative technique. RESULTS: PV-immunoreactive neurons were present in the SC and VC, whereas only a few were found in the LGN. The monocular enucleation at the onset of the sensitive period markedly reduced PV immunoreactivity in the neuropil of the SC, contralateral to the enucleated eye when examined one month later. No consistent and significant change in PV immunoreactivity was found in either the LGN or the VC. The number of PV-immunoreactive neurons in the VC rapidly decreased to the adult level during the middle of the sensitive period. The expression of PV mRNA in these central visual structures was not affected by early monocular enucleation. CONCLUSIONS: Expression of PV is developmentally regulated, and marked changes in its protein expression in the SC can be induced by monocular enucleation. Contrary to the original hypothesis, monocular enucleation did not consistently affect the expression of PV in the rat VC. The expression of PV is probably regulated by multiple factors, not merely by binocular competition.

Animals↗
PubMed1998

Effects of Postoperative Pericardial Effusion on Coronary Artery Bypass Grafts: A Study with X-ray Computed Tomography.

The aim of this study was to evaluate the effects of pericardial effusion on coronary artery bypass grafts and their patency using X-ray computed tomography (CT). Uncontrasted CT of horizontal sections from the lower margin of the aortic arch to the left ventricle was done at 5-mm intervals. In one cross-section of the pulmonary bifurcation level, 30 ml of a contrast media (lohexol 350) was injected at a rate of 3 ml/second into the antecubital vein. All slices of uncontrasted CT were analyzed for the presence or absence of effusion. The severity was expressed as the maximum value of the thickness of effusion. CT was repeated about every 6 months postoperatively under the same conditions. Selective angiography was also performed 7.1 +/- 3.9 months postoperatively. A total of 46 patients (mean age 57 years) underwent CT and angiography. A total of 95 grafts were implanted: 90 saphenous veins and 5 internal thoracic arteries. Selective angiography revealed that 79 grafts were patent and 16 were occluded. The first postoperative CT (at 2.6 +/- 2.1 months) showed the retention of effusion in all patients. The mean maximum value was 1.0 +/- 0.5 cm; there were no significant differences between patent grafts (1.0 +/- 0.5 cm) and occluded grafts (1.0 +/- 0.5 cm). Occlusion was found in 10 grafts by the first CT (2.9 +/- 2.7 months postoperatively) and another 6 grafts by the second CT (11.3 +/- 4.2 months). Thereafter, all grafts were patent. Previously occluded grafts showed no cross-section images on uncontrasted or contrasted CT. Except for two grafts, all patent grafts could be observed even without contrast enhancement. The remaining two grafts were masked with effusion, but patency was confirmed by a contrast media. In conclusion, retention of effusion does not affect the patency of grafts. Occlusion occurs early after surgery, and grafts cannot be imaged on CT. Patent grafts can be observed by uncontrasted CT, as well as contrasted CT, except where a large amount of effusion is present.

Journal Article↗
PubMed1998

[Left ventricular wall motion dynamics of asymmetric septal hypertrophy: assessment by intramyocardial pulsed Doppler echocardiography].

Apical pulsed Doppler tissue imaging can be used to assess the function of regional myocardium. We hypothesized that septal dysfunction might be clarified in the hypertrophic cardiomyopathy (asymmetric septal hypertrophy) by this method. Twenty-one patients with asymmetric septal hypertrophy (mean age 54.8 +/- 11 years) and age-matched 24 normal subjects (52.4 +/- 8 years) were studied. The E/A ratio measured by mitral inflow Doppler was not different between the groups (1.1 vs 1.2). E wave velocities of the septum were significantly decreased in the hypertrophy group compared to the control group (4.0 +/- 1.5 vs 8.1 +/- 2.2 cm/sec), and A wave velocities were increased in the hypertrophic septum, resulting in a significantly lower E/A ratio (0.5 +/- 0.3) compared to the E/A ratio (0.9 +/- 0.3) of the normal septum. Deceleration time of the E wave and isovolumic relaxation time were significantly prolonged in the thick septum compared to the normal septum (136 +/- 51 vs 107 +/- 28 msec, 91 +/- 36 vs 63 +/- 19 msec, respectively). In conclusion, asymmetric septal hypertrophy was characterized by diastolic dysfunction of the thickened septum. Intramyocardial pulsed Doppler echocardiography can detect regional myocardial dysfunction earlier than the mitral inflow Doppler method.

Cardiomyopathy, Hypertrophic↗
PubMed1998

[Ebstein's anomaly associated with left ventricular dysfunction: a case report].

A 66-year-old man presented with Ebstein's anomaly associated with left ventricular dysfunction. He had been followed since 40 years of age for cardiomegaly and arrhythmia, and experienced episodes of orthopnea at the age of 64. He was referred to our hospital in April 1997 because of lower extremity edema. Physical examination revealed dilated external jugular vein, tenderness of the right hypocondorium, and lower extremity edema. Electrocardiography confirmed atrial fibrillation. Transthoracic echocardiography revealed bilateral atrial and ventricular dilation, and paradoxical septal movement. The apical four-chamber view demonstrated 15 mm apical displacement of the septal leaflet. Color Doppler echocardiography revealed moderate tricuspid regurgitation. Transesophageal echocardiography revealed low echoic and hypoplastic tricuspid valve. Left ventriculography showed diffuse hypokinesis, and the ejection fraction was 49%. The coronary artery was normal. Atrial septal defect was not detected. Diffuse fibrosis, which may be found in the hearts of patients with Ebstein's anomaly at autopsy may have been responsible for the left ventricular depressed systolic function in this patient.

Aged↗
PubMed1996

[Concurrent high-dose thoracic irradiation plus daily low-dose cisplatin and vindesine in locally advanced unresectable stage III non-small cell lung cancer].

Patients with unresectable non small-cell lung cancer were treated to evaluate the toxicity and efficacy of high-dose thoracic irradiation (RT) combined with concurrent daily cisplatin plus vindesine. Fourteen evaluable patients with unresectable stage III non small-cell lung cancer treated with continuous-course RT (70 Gy in 35 fractions of 2 Gy once daily) and concurrent daily intravenous cisplatin (6 mg/m2) plus vindesine (3 mg/m2 on day 1 and day 8). The objective response rate was 86%, and two patients achieved a radiographic complete response. Leukocytopenia was the severe toxicity, but there were no episodes of discontinuation of treatment. Only one patient had grade 3 acute radiation esophagitis. Ten patients experienced late radiation pneumonitis and nine of those had grade 1 or grade 2. There was only one life-threatening case of toxicity (grade 5 pneumonitis). We concluded that the regimen of high-dose thoracic RT combined with concurrent daily cisplatin plus vindesine obtained a high response rate. Further testing on late toxicities and survival time is required.

Aged↗
PubMed1996

Intramyocardial pulsed Doppler echocardiography as a new modality for evaluation of left ventricular wall motion: assessment in normal subjects.

Doppler tissue imaging-guided pulsed Doppler echocardiography can record velocities of the regional ventricular wall, but the potential clinical applications have not yet been investigated. To propose a new modality for assessment of left ventricular wall dynamics, we investigated the longitudinal and latitudinal motions of the normal left ventricular wall with intramyocardial pulsed Doppler echocardiography under tissue imaging guidance, and characterized the velocity patterns in 31 normal subjects or normal volunteers (mean age 38 +/- 18 years old). Velocity patterns of the septal and posterior walls were recorded and compared using the parasternal and apical approaches. The apical approach showed that the entire left ventricle moved, coded in red, toward the transducer during systole, and moved away, coded in blue, during diastole. Pulsed Doppler echocardiography recorded the systolic S, early diastolic E and presystolic A waves from both windows. All three waves had higher velocities in the apical compared to the parasternal approach, and the velocities of S and E waves were increased more in the posterior wall than in the septum. Thus, the A/E ratio was significantly lower in the posterior compared to the septal wall (0.63 +/- 0.3 and 0.77 +/- 0.3, respectively, in the apical approach) and the A/E ratio of transmitral inflow was between those of the walls. Apical intramyocardial pulsed Doppler echocardiography can accurately evaluate septal and posterior wall dynamics. The present study provides important basic data for assessing regional myocardial function.

Adult↗