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Biomedical subjects

J Yoshikawa

Publications and source records attributed to J Yoshikawa.

At least 235 records · Page 13Linked to original sources
PubMed1996

Nitric oxide mediates the cardiovascular instability of haemodialysis patients.

Acute hypotension is a major cardiovascular complication of haemodialysis. The cardiac output falls but the total peripheral resistance remains unchanged at the time when hypotension develops. Nitric oxide affects myocardial contraction and noradrenergic response, and regulates vascular tone. This review discusses the mechanisms of acute hypotension occurring during haemodialysis, focusing on the role of nitric oxide in the associated cardiovascular instability.

Animals↗
PubMed1996

Role of pulmonary vascular disorder in determining exercise capacity in patients with severe chronic obstructive pulmonary disease.

In patients with chronic obstructive pulmonary disease (COPD), the primary cardiovascular complication is the development of pulmonary hypertension, especially during exercise. The purpose of this study was to determine whether pulmonary vascular disorder plays an important role in determining exercise capacity in patients with severe COPD. Twenty-one male patients with severe COPD (mean FEV1 = 0.91 +/- 0.26 1) performed a progressive incremental exercise test, until symptom-limited maximum, to determine maximal exercise capacity, and then a constant-load exercise test for 5 min at a workload (20-60 W) corresponding to 60% of maximal workload during right heart catheterization to characterize the haemodynamic behavior of pulmonary circulation during exercise. The severity of the pulmonary vascular disorder was assessed using the slope of the mean pulmonary arterial pressure (PAP) - cardiac index (CI) relationship during constant-load exercise (P-Q slope). A significant inverse correlation was found between the maximal oxygen consumption (VO2max) and P-Q slope (r = -0.669), but not between VO2max and indices of expiratory airflow obstruction. In addition, the P-Q slope was inversely correlated with mixed venous oxygen tension (PvO2) at the end of constant-load exercise (r = -0.679) and with the change in oxygen delivery relative to oxygen consumption (delta DO2/delta VO2) during constant-load exercise (r = -0.671). These findings suggest that in patients with COPD, the functional impairment of the pulmonary vasculature is associated with disturbance in oxygen transport to the peripheral muscle during exercise, resulting in reduction of exercise capacity. We conclude that pulmonary vascular disorder may be an important factor in determining the exercise capacity of patients with severe COPD.

Aged↗
PubMed1996

Use of intravascular ultrasound for in vivo assessment of changes in intimal thickness of angiographically normal saphenous vein grafts one year after aortocoronary bypass surgery.

OBJECTIVE: To use intravascular ultrasound in vivo to evaluate changes in the intimal thickness of angiographically normal saphenous vein grafts one year after implantation. DESIGN: Fifteen saphenous vein grafts in 12 patients were examined one month and 12 months after aortocoronary bypass graft surgery with intravascular ultrasound using a 30 MHz transducer. None of the grafts examined showed any angiographic abnormalities. The intimal thickness and intimal area of the graft in the proximal portion were measured on intravascular ultrasound images obtained one month and 12 months after operation. SETTING: General hospital. PATIENTS: Twelve patients who underwent aortocoronary bypass graft surgery. RESULTS: The ultrasound images showed a thin-walled graft with a thin intima one month after operation (mean (SD)) (0.31 (0.09) mm). The intimal thickness of the graft increased significantly to 0.65 (0.08) mm (P < 0.001) 12 months after operation. The intimal area of the graft was 0.90 (0.80) mm2 one month after operation. 12 months after operation the intimal area had increased significantly to 5.26 (1.38) mm2 (P < 0.001). CONCLUSION: Intravascular ultrasound in vivo showed that one year after implantation angiographically normal saphenous vein grafts had a thicker intima than one month after implantation.

Coronary Artery Bypass↗
PubMed1996

Potentiation of the bronchoprotective effects of vasoactive intestinal peptide, isoprenaline, and theophylline against histamine challenge in anaesthetised guinea pigs by adrenomedullin.

BACKGROUND: Adrenomedullin is a hypotensive peptide recently discovered in human phaeochromocytoma which has been found to inhibit bronchoconstriction induced by histamine and acetylcholine. This study was designed to determine the manner in which adrenomedullin and other bronchodilators interact in modulating airway function. METHODS: A study was undertaken to determine whether adrenomedullin potentiated the bronchoprotective effects of isoprenaline, vasoactive intestinal peptide (VIP), and theophylline against histamine-induced bronchoconstriction in anaesthetised guinea pigs in vivo. RESULTS: Adrenomedullin in a concentration of 10(-9) M significantly inhibited histamine-induced bronchoconstriction but in a concentration of 10(-10) M it did not exhibit the bronchoprotective effect against histamine. VIP (10(-9) M) did not affect histamine-induced bronchoconstriction but it markedly inhibited the bronchoprotective effect against histamine in the presence of adrenomedullin (10(-10) M). VIP (10(-6) M) significantly inhibited histamine-induced bronchoconstriction but this effect was short lived. Adrenomedullin in a concentration of 10(-10) M potentiated bronchoprotection induced by VIP (10(-6) M) and prolonged it. Isoprenaline (10(-8) M) also significantly inhibited histamine-induced bronchoconstriction and this effect was enhanced in the presence of adrenomedullin (10(-10) M). Similarly, adrenomedullin (10(-10) M) significantly potentiated theophylline-induced bronchoprotection, and a sub-bronchoprotective dose of theophylline (20 mg/kg i.p.) was effective in preventing histamine-induced bronchoconstriction in the presence of adrenomedullin (10(-10) M). CONCLUSIONS: This study shows that adrenomedullin potentiates the bronchoprotective effects of different classes of bronchodilators against histamine challenge in anaesthetised guinea pigs.

Adrenomedullin↗
PubMed1996

Effect of loratadine, an H1 antihistamine, on induced cough in non-asthmatic patients with chronic cough.

BACKGROUND: H1 antihistamines have been shown to have an antitussive effect in patients with asthma, postnasal drip, and allergic rhinitis. No study has been performed to determine whether orally administered H1 antihistamines can reduce the number of coughs induced by stimulation of cough receptors in non-asthmatic patients with chronic dry cough. METHODS: The effect of loratadine (10 mg) on the number of coughs induced by ultrasonically nebulised distilled water (UNDW) was examined in 10 patients with nasal disease and in seven patients with unexplained chronic cough using a randomised, double blind crossover method. Eleven normal volunteers were also studied. Each subject inhaled UNDW for one minute, and the numbers of coughs during the one minute inhalation and the 30 seconds following it were counted. RESULTS: There was no difference in the results of pulmonary function tests performed before and one minute after UNDW inhalation for either patients or normal subjects. There was also no significant difference between the results of pulmonary function tests before or after oral administration of loratadine. Loratadine significantly reduced the number of coughs in patients with nasal disease and in those with unexplained chronic cough, but not in normal subjects. CONCLUSIONS: The H1 antihistamine loratadine reduces cough induced by UNDW. The release of histamine may contribute to the chronic cough in patients with unexplained chronic cough or nasal disease.

Adult↗
PubMed1996

Plasma adrenomedullin concentrations in essential hypertension.

We designed the present study to assess any changes in plasma concentrations of the novel vasorelaxant peptide adrenomedullin in patients with essential hypertension. Plasma adrenomedullin concentrations were measured in 45 patients with untreated essential hypertension, 15 patients with borderline hypertension, and 30 normotensive control subjects. After 4 weeks of effective calcium channel blocker-based antihypertensive therapy, adrenomedullin concentrations were measured again. The concentrations were higher in hypertensive patients with increased serum creatinine levels or decreased glomerular filtration rates compared with borderline hypertensive patients and normotensive subjects, although values in normotensive and hypertensive individuals overlapped. Plasma adrenomedullin concentrations were positively correlated with serum creatinine levels and inversely correlated with glomerular filtration rates in the hypertensive patients, whereas adrenomedullin values were not correlated with blood pressure level, left ventricular mass index, or left ventricular ejection fraction. Despite blood pressure control with antihypertensive therapy, plasma adrenomedullin concentrations were not changed. Reversed-phase high-performance liquid chromatographic analysis showed that a major component of immunoreactive adrenomedullin in the plasma of normotensive subjects and hypertensive patients is human adrenomedullin-(1-52). These results indicate that plasma adrenomedullin concentrations are elevated in many hypertensive patients with renal dysfunction and its major component is human adrenomedullin-(1-52).

Adrenomedullin↗
PubMed1996

Possible involvement of phospholipase D and protein kinase C in vascular growth induced by elevated glucose concentration.

Hyperglycemia is believed to be a major cause of diabetic vascular complications. To elucidate the effect of hyperglycemia on vascular response, we studied hyperproliferation, hypertrophy, and the natriuretic peptide response of vascular smooth muscle cells under high-glucose conditions. We observed that cells cultured in high glucose (22.2 mmol/L) showed hyper-proliferation and hypertrophy and that natriuretic peptide receptor responses were suppressed compared with cells cultured in normal glucose (5.6 mmol/L). We also examined phospholipase D and protein kinase C activities and found that in high-glucose conditions such activities are higher than in cells cultured in normal glucose. The activation of phospholipase D was not prevented by coincubation with 1 mumol/L protein kinase C(19-36), a specific protein kinase C inhibitor, but the activation of protein kinase C was. Protein kinase C(19-36) also markedly attenuated vascular hyperproliferation and hypertrophy as well as glucose-induced suppression of natriuretic peptide receptor response. These results show that hyperglycemia may be linked to vascular hyperproliferation, hypertrophy, and a suppressed natriuretic peptide receptor response, which are caused by increased phospholipase D and protein kinase C activities.

Animals↗
PubMed1996

Role of endogenous nitric oxide in airflow obstruction in smokers.

OBJECTIVE: The aim of this study was to examine the relationship between endogenous nitric oxide (NO) level and airflow obstruction in smokers using single-breath measurement of exhaled NO with the sequential breath-holding method. SETTING: A university hospital. PATIENTS: Nine nonsmoking and ten smoking healthy volunteers. MEASUREMENTS: NO in exhaled air was measured using a chemiluminescence analyzer. Pulmonary function tests were performed using an autospirometer. RESULTS: The level of exhaled NO was higher in nonsmokers than in smokers, and the difference became larger as the breath-holding time increased. To evaluate the correlation between endogenous NO level and the degree of airflow obstruction in smokers, we used a new parameter, the NO concentration difference (delta NO). Our findings indicate that reduced level of NO in exhaled air is an indicator of decreased NO synthesis within the respiratory system and is associated with the development of airflow obstruction in smokers (r = 0.678; p < 0.01). CONCLUSIONS: delta NO is a good indicator of the synthesis of endogenous NO within the respiratory system, and it appears likely that the reduced synthesis of NO may be a contributing factor to airflow obstruction in smokers.

Adult↗
PubMed1996

[Evaluation of left ventricular volume and ejection fraction using three-dimensional transesophageal echocardiography].

Left ventricular (LV) volume and ejection fraction (EF) derived from three-dimensional echocardiography using a multiplane transesophageal probe (3D-TEE) were compared with LV volume and EF obtained from left ventriculography (LVG) in 14 patients (mean age: 61 years). Left ventricular volumes were calculated using a summation of disks algorithm based on multiple reconstructed short-axis cross-sections from 3D data. Left ventricular volume (end-diastole and end-systole) and EF from 3D-TEE were compared with those from LVG using linear regression analysis. Three-dimensional TEE demonstrated excellent correlations with LVG for measuring LV volume (r = 0.97, SEE = 11 ml) and EF (r = 0.95, SEE-4%), respectively. Three-dimensional TEE is useful for the measurement of LV volume and EF in the clinical setting.

Echocardiography, Transesophageal↗
PubMed1996

[Phasic flow velocity characteristics of the right coronary artery in patients with aortic stenosis: a Doppler guide wire study].

This study investigated the characteristics of the phasic flow velocity pattern of the right coronary artery and the relationship to hemodynamic parameters in patients with aortic stenosis. Coronary flow velocities were recorded at the proximal (segment 1) and the distal (segment 4PD) portion of the right coronary artery using a Doppler guide wire (0.014-in, 15 MHz) in 10 patients with aortic stenosis and 8 control subjects with normal coronary arteries. The diastolic to systolic peak velocity ratio at both the proximal and distal portion were significantly greater in patients with aortic stenosis than in control subjects. Systolic flow reversal was not seen in the right coronary artery in control subjects, but it was observed in 5 patients (50%) at the proximal portion and in 10 patients (100%) at the distal portion. Peak velocity of flow reversal at the distal portion showed a significant correlation with mean pressure gradient across the aortic valve (y = -1.3x + 37.3, r = 0.71, p = 0.02). Systolic flow reversal is characteristic in the right coronary artery, especially at the distal portion, in patients with aortic stenosis. This may be related to the pressure difference across the aortic valve through the posterior descending artery.

Aged↗
PubMed1996

[Value and limitations of valve resistance in assessing prosthetic aortic valve function: clinical study using dobutamine stress doppler echocardiography].

Hemodynamic resistance may be a useful index for the severity of valvular aortic stenosis, but little is known about the utility of valve resistance in assessing the prosthetic aortic valve function. This study investigated whether valve resistance is useful in assessing prosthetic valve function in 13 patients with normally functioning CarboMedics prosthetic aortic valves. Transvalvular pressure gradient, effective orifice area and valve resistance derived from two-dimensional and Doppler echocardiography were calculated before and after dobutamine infusion. Dobutamine was infused incrementally (3-12 micrograms/kg/min) under echocardiographic imaging. Transvalvular pressure gradient (24 +/- 7-->53 +/- 18 mmHg, p < 0.01) and valve resistance (102 +/- 32-->140 +/- 57 dynes.sec.cm-5, p < 0.01) significantly increased after dobutamine infusion. However, effective orifice area did not increase significantly (1.1 +/- 0.5-->1.2 +/- 0.5 cm2). These findings indicate that transvalvular pressure gradient and valve resistance are flow-dependent and should be treated with caution when assessing prosthetic valve function.

Adult↗
PubMed1996

[Small-cell lung cancer and subacute sensory neuropathy in a patient positive for the anti-Hu antigen].

We encountered a case of small-cell lung cancer in a patient with subacute sensory neuropathy that began 5 months before the cancer was diagnosed. A 60-year-old man complained of abnormalities in the functioning of his peripheral sensory systems (senses of pain, touch, position, and vibration). A chest X-ray film obtained on admission showed an anterior mediastinal tumor. The anti-Hu antibody was found in his serum. The diagnosis was small-cell lung cancer. Combination chemotherapy (cisplatin and irinotecan, CPT-11) was begun and the response was a complete remission. The symptoms of neuropathy continued. The anti-Hu antibody was useful in the diagnosis in the case of small-cell lung cancer combined with subacute sensory neuropathy.

Acute Disease↗
PubMed1996

[Intraoperative assessment of mitral valve plasty by transesophageal echocardiography].

Mitral valve repair offers many advantages over prosthetic valve replacement, especially in minimizing the risk of thromboembolism. Intraoperative evaluation of residual mitral regurgitation (MR) is important in this procedure. The present study assessed the usefulness of transesophageal echocardiography (TEE) for the intraoperative assessment of residual MR in patients undergoing mitral valve repair. Intraoperative TEE was performed in 102 consecutive patients before and after mitral valve repair in the operating room. The grade of MR was evaluated according to the maximum MR jet area detected by biplane color Doppler TEE (mild: <4 cm2; moderate: 4 < or = < 7 cm2; severe : 7 cm2 < or =). After the first repair, the manual regurgitant test was performed. Excellent results with no or mild MR assessed by the manual regurgitant test were obtained in 101 patients. However, moderate or severe MR was identified in eight of these 101 (7.9%) patients by TEE after weaning from the cardiopulmonary bypass. Consequently, six of these eight patients underwent repeat mitral valve repair and two patients received prosthetic valve replacement. Satisfactory final operative results were obtained in all 101 patients. The eight patients who needed additional operative procedures followed good clinical courses in hospital. TEE 1 month after operation demonstrated no or mild MR in these eight patients. Intraoperative TEE is useful in the evaluation of residual MR after mitral valve repair. This technique provides indications for immediate additional operative procedures, and can reduce the occurrences of congestive heart failure and reoperation in the early stage after mitral valve repair.

Adult↗
PubMed1996

[Transverse myelitis in a patient with primary antiphospholipid syndrome--a case report].

A case of acute transverse myelitis following primary antiphospholipid syndrome was presented. The patient was 32-year-old Japanese female who was admitted to our hospital with paresthesia and weakness of the right upper extremity in September 1995. Neurological examinations revealed slight weakness and hypesthesia of the right arm and leg, impairment of vibration sense below the right knee, and hyperreflexia on the right side. There was no apparent history of systemic lupus erythematosus or multiple sclerosis. Laboratory investigations disclosed raised anticardiolipine antibody level of the IgG class. A magnetic resonance (MR) imaging of the cervical spine revealed changes in the spinal cord at C3-5. A gradual enlargement of the cord at C3-5 level was revealed on T1-weighted sagittal images; increased signal intensity at these same levels was visualized on T2-weighted images. Following administration of contrast material, an area of increased signal intensity was visualized within the cord extending from the C3/4 level to the C4/5 level in sagittal views and was located in the right lateral and posterior funiculus of the cord in axial views. After the admission, the patient's neurological symptoms worsened, and then we treated her by steroid pulse therapy. After that, the patient's symptoms gradually disappeared and the abnormal signal intensity of the spinal cord on an MR imaging disappeared. No evidence of recurrence was yielded by neurological examinations or neuroimaging studies. Antiphospholipid antibodies should be studied in all patients with transverse myelitis whether known to systemic lupus erythematosus, multiple sclerosis or not.

Adult↗
PubMed1996

Serial change of mitral regurgitation after mitral valve repair: comparison of anterior with posterior leaflet lesions.

Mitral valve repair is an important operative procedure for correcting mitral regurgitation (MR). However, serial change of residual MR after operation has not been reported. Serial change of MR after mitral valve repair was evaluated by transesophageal color Doppler echocardiography (TEE). Twenty-six patients undergoing mitral valve repair for MR during 1987 to 1991 were examined by TEE just after operation, 6 months after operation, and late follow-up period (mean 3.7 years). Thirteen patients had a lesion of the anterior mitral leaflet before operation (group A). Thirteen patients had a lesion of the posterior mitral leaflet before operation (group P). The MR area was measured by TEE at each stage after operation. In group A, the MR area at late follow-up increased significantly compared with just after operation (1.1 vs 4.3 cm2, p < 0.001). In group P, the MR area at late follow-up did not increase significantly compared with just after operation (0.6 vs 1.3 cm2, p = NS). In conclusion, MR does not increase after mitral valve repair in patients with posterior mitral valve repair, but MR may increase at late follow-up after operation for anterior mitral valve prolapse.

Echocardiography↗
PubMed1996

Pseudoaneurysm and ventricular septal rupture complicated with inferior myocardial infarction diagnosed by two-dimensional and Doppler echocardiography: case report.

A 72-year-old woman with inferior myocardial infarction presented with both a pseudoaneurysm and a ventricular septal rupture detected by two-dimensional and Doppler echocardiography. The pseudoaneurysm originated from the junctional area between the inferior portion of the ventricular septum and posterior left ventricular wall. The short-axis view of two-dimensional echocardiography revealed an abrupt discontinuity of the junctional area and an echo-free space behind the left ventricular cavity. The communication orifice was 5 mm wide. Color Doppler echocardiography showed a left-to-right shunt flow from the pseudoaneurysm to the right ventricle was visualized. Combined use of two-dimensional and color Doppler echocardiography was useful for detecting a pseudoaneurysm resulting in rupture of the ventricular septum.

Aged↗
PubMed1996

[Automatic assessment of left ventricular cavity area by the automated contour tracking method].

Measurements of left ventricular cavity area by the manual tracing method from apical four-chamber views were compared with those using the automated contour tracking (ACT) method. Nine consecutive patients in whom clear images were obtained by two-dimensional echocardiography were studied, and left ventricular end-diastolic, end-systolic areas an fractional area changes were calculated using the ACT method. The ACT method slightly underestimated left ventricular cavity areas, but excellent correlations were obtained with left ventricular end-diastolic and end-systolic areas between the ACT and manual methods (r = 0.99, SEE = 1.5 cm2; r = 0.99, SEE = 1.2 cm2; respectively). Manual tracing fractional area change correlated well with that by the ACT method (r = 0.95, SEE = 3.4%). The ACT method provides accurate estimates of the area of the left ventricular cavity.

Cardiac Volume↗