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Biomedical subjects

Y Hara

Publications and source records attributed to Y Hara.

At least 343 records · Page 19Linked to original sources
PubMed1996

[Familial hypertrophic cardiomyopathy generating a marked left ventricular pressure gradient in an 82-year-old woman].

Familial nonobstructive hypertrophic cardiomyopathy in 78-year-old woman was diagnosed in 1988. Since then she has been treated with a beta-blocking drug and a calcium antagonist. Her clinical condition was NYHA I or II for several years. Echocardiography revealed asymmetric septal hypertrophy in 1988 (interventricular septal thickness = 21 mm, posterior wall thickness = 10 mm). Systolic anterior motion of the mitral valve was first observed at the end of 1992. The left ventricular pressure gradient also gradually increased; it was about 138 mmHg in 1993 (age 82 yrs). The left ventricular ejection time index increased from 376 msec in May, 1992 to 459 msec in May, 1994. In September, 1994, the patient's condition gradually deteriorated (NYHA IV), and she was admitted to our hospital. To attenuate the left ventricular pressure gradient, 150 mg of disopyramide was administered. Her condition markedly improved: the left ventricular pressure gradient decreased from 180 mmHg to 76 mmHg, and the left ventricular ejection time index decreased from 485 msec to 419 msec. These results indicate that a left ventricular pressure gradient can be generated rapidly even in a very old patient, and that disopyramide may be useful to attenuate the left ventricular pressure gradient.

Aged↗
PubMed1996

[A 66-year-old woman with a patent ductus arteriosus and no significant progression of pulmonary arterial pressure over 17 years].

We report the case of a 66-year-old woman with a patent ductus arteriosus and no significant progression of pulmonary arterial pressure over 17 years. She was admitted to our hospital in 1978 because of palpitations on exertion and chest discomfort. Cardiac catheterization was done, and she was given a diagnosis of patent ductus arteriosus. Because the left-to-right shunt was small (15%) and because there was no evidence of pulmonary hypertension (38/18 mmHg), she was treated medically. In 1995 she was admitted again, to determine the cause of a cerebral infarction. The cerebral infarction was believed to have been caused by an embolism due to atrial fibrillation. She underwent cardiac catheterization again. The left-to-right shunt had increased to 41%, but the pulmonary artery pressure had not changed (27/14 mmHg). Intravascular ultrasound imaging was used to evaluate the ductus arteriosus. The diameter of the ductus was 4.4 mm and calcification was not observed. During the 17 years of follow-up, heart size increased slightly, but pulmonary artery pressure did not change. In addition, intravascular ultrasound was very useful for evaluating the condition of the ductus arteriosus.

Aged↗
PubMed1996

[Tympanic electrocochleography with disposable electrode].

Extratympanic recording of electrocochleography (ECochG) has played an important role in the differential diagnosis of inner ear diseases. We used a special electrode, which was wrapped in a cotton ball at the tip and covered with a silicon sheath over the entire length, and recorded ECochG from the tympanic membrane (tympanic ECochG). Our method was found to be more convenient and less traumatic than recording with an ear canal electrode. Tympanic ECochG records from 10 normal volunteers showed no influence of iontophoretic anesthesia on the tympanic membrane. The effects on the conductive hearing mechanism were negligible. The input-output curve of the action potential (AP) by click stimuli was fairly stable and comparable to that obtained with transtympanic recording. We performed tympanic ECochG in patients with Meniere's disease or other sensory hearing loss, and compared the amplitude ratios of the summating potential (SP) and AP (SP/AP ratio) with those in normal hearing subjects. The SP/AP ratios in patients with Meniere's disease were significantly increased, an observation consistent with the results of other studies. The SP/AP ratio was also elevated in patients with autoimmune sensory hearing loss or perilymphatic fistula. Based on the results of the present study, we speculate that it is possible to diagnose an inner ear disorder by comparing the tympanic ECochG findings with not only records from normal subjects, but also the contralateral record of tympanic ECochG from the same subject. We conclude that tympanic ECochG using disposable electrodes can provide useful information on inner ear function, because of its convenience, non invasiveness and safety in clinical use. We found tympanic ECochG to be useful in the glycerol dehydration test and for monitoring inner ear function during acoustic neurinoma surgery.

Acoustic Stimulation↗
PubMed1996

[A report of surgical treatment for atherosclerotic aneurysm in the aortic arch associated with type III acute aortic dissection].

A 75-year-old man was admitted to our hospital because of severe chest pain. A chest CT scan demonstrated an atherosclerotic true aneurysm measuring 50 mm in diameter located just distal to the aortic arch as well as a DeBakey type III dissection. Although the patient received medical therapy, the size of the true aortic aneurysm increased to 71 mm and the false lumen of the descending aorta was also enlarged after three weeks. At 11 weeks after admission, the aortic arch and the proximal portion of the descending aorta were replaced with a 32 mm Hemashield graft using moderate hypothermic selective cerebral perfusion. The postoperative course was uneventful, and there were no neurological complications. Coexistence of atherosclerotic true aneurysm and acute aortic dissection appears to increase the risk of aortic rupture, early surgical treatment should be considered.

Acute Disease↗
PubMed1996

[Molecular analysis of the estrogen receptor (ER) gene in association with ER negativity in breast cancer].

DNA from ninety-eight primary breast cancer biopsies has been examined for loss of heterozygosity (LOH). Thirteen of seventy-two informative cases (18.1%) were positive for LOH, which correlated with age at operation but not with ER status. This result suggests that LOH of the ER gene does not have an important role in the lack of ER function in breast cancer tissues. Thirteen breast cancers with ER negative/progesterone receptor (PgR) positive were screened for mutation analysis of the ER gene using single strand conformational polymorphism (SSCP). We found 2 polymorphisms in codon 10 (C to G) codon 325 (C to T), although neither germline nor somatic mutation was detected. Since the sequence variant of codon 325 tends to be more frequently seen in ER negative/PgR negative breast cancer patients than non-cancer control patients, it is suggested that this polymorphism was related to negativity and function of ER in breast cancer tissues.

Breast Neoplasms↗
PubMed1996

[Evaluation of myocardial damage using 123I-BMIPP imaging in patients with vasospastic angina].

The purpose of this study is to determine whether left ventricular dysfunction following coronary artery spasm by 123I-BMIPP myocardial imaging. To reveal the clinical efficacy of 123I-BMIPP SPECT, 20 patients with vasospastic angina were studied using resting, 3-hour delayed image with 123I-BMIPP and exercise, 3-hour delayed image with 201Tl SPECT. 123I-BMIPP uptake was decreased compared to 201Tl (discordant) in 12 patients (60%) and in 49/100 myocardial segments (49%). The extent and severity score in resting image with 123I-BMIPP were significantly larger than that in delayed image with 201Tl (p < 0.01). In 123I-BMIPP SPECT, the severity score in the latest ischemia were significantly larger than that in others. The incidence of a complete agreement of decreased 123I-BMIPP uptake and coronary artery spasm was significantly higher (75%) than that in 201Tl (28%, p < 0.01). Furthermore, compared to 201Tl uptake, decreased 123I-BMIPP uptake much more corresponded to reduced wall motion in 9 of patients with mismatching. The severity of regional wall motion abnormality was significantly correlated with severity score of 123I-BMIPP. Late redistribution in delayed image with 123I-BMIPP was seen in 6 patients. The regional washout rate and the severity of regional wall motion abnormality in 6 patients was significantly lower than that in others (p < 0.05). Thus, metabolic abnormality assessed by 123I-BMIPP is well associated with left ventricular asynergy and spastic region in patients with vasospastic angina. In conclusion, 123I-BMIPP SPECT may sensitively delineate the impaired myocardium following coronary artery spasm, and it is very useful in diagnosing and estimating the severity of vasospastic angina.

Adult↗
PubMed1996

[A case report of surgical treatment for acute mitral insufficiency associated with acute gastric lesion].

A 76-year-old female was admitted to our hospital due to anterior chest pain and dyspnea. Mitral regurgitation due to prolapse of the posterior leaflet was detected by UCG. After admission, massive gastric hemorrhage was observed. Because hemostatic therapy using endoscopy was not effective, partial gastrectomy was performed. The origin of the hemorrhage, an acute gastric ulcer, was located on the side of the minor curvature of the corpus ventriculi. After gastrectomy, the patient underwent medical treatment using an IABP, but the left heart failure was not reduced, and the pulmonary edema worsened. At 18 hours after gastrectomy, MVR was performed. The cause of regurgitation is torn chordae of the posterior leaflet. The postoperative course was good, and the patient is doing well in NYHA class 1. This case is the first report of acute mitral insufficiency associated with acute gastric lesion in Japan.

Acute Disease↗
PubMed1996

[A case report of Stanford type A acute thrombosed aortic dissection complicating cardiac tamponade].

An 85-year-old man was admitted with shock due to cardiac tamponade. Plain computed tomography showed a dilated ascending aorta but did not clearly show an aortic dissection. We performed an emergency operation with median sternotomy without the benefit of findings from enhanced computed tomography and aortography. Soon after the bloody pericardial effusion was decompressed during the operation, bleeding from the ascending aorta occurred. An intimal tear was found in the distal ascending aorta, and the pseudolumen was filled with fresh thrombus. The ascending aorta was replaced. The patient had an uneventful postoperative recovery and was discharged 1 month after the operation. We conclude that patients with Stanford type A acute thrombosed aortic dissection complicating cardiac tamponade should undergo early graft replacement.

Acute Disease↗
PubMed1996

Inhibitory effect of amiodarone on the muscarinic acetylcholine receptor-operated potassium current in guinea pig atrial cells.

It is well known that amiodarone is effective for the treatment of atrial fibrillation. However, effects of amiodarone on the muscarinic acetylcholine receptor-operated K+ current (IK.ACh), which plays an important role in the repolarization of atrial action potential, have not been evaluated. This study was undertaken to determine whether amiodarone inhibits the acetyl-choline-sensitive muscarinic K+ (KACh) channel by use of the patch-clamp technique. In isolated guinea pig atrial cells, IK.ACh was activated by extracellular application of carbachol (1 microM) or adenosine (10 microM) or by the intracellular loading of GTP gamma S (100 microM). Amiodarone inhibited the IK.ACh activated in these three different ways with similar IC50 values around 2 microM, which indicated that amiodarone directly depresses the function of the KACh channel itself and/or GTP-binding proteins. Single KACh channel current was also recorded by use of a pipette solution containing carbachol (1 microM) or atropine (10 microM) plus theophylline (100 microM) in a cell-attached configuration. Amiodarone at a concentration of 3 microM significantly decreased the open probability of the KACh channel in both conditions. Amiodarone also reversed the carbachol- and adenosine-induced action potential shortening in a concentration-dependent manner. In isolated guinea pig hearts, perfusion of 1 microM carbachol shortened the effective refractory period of the atria and lowered the atrial fibrillation threshold. Addition of 10 microM amiodarone reversed these electrophysiological parameters to the control level. These results suggest that amiodarone inhibits IK.ACh by depressing the function of the KACh channel itself and/or associated GTP-binding proteins. This effect of amiodarone may at least in part be involved in the antiarrhythmic action against atrial fibrillation.

Action Potentials↗
PubMed1996

[A case of aortitis syndrome, in which carotid ultrasonography was a useful approach for the diagnosis].

We report a case of aortitis syndrome, in which carotid ultrasonography was a useful approach for the diagnosis. A 21-year-old woman was admitted to our hospital for persistent fever. No specific physical findings or laboratory abnormalities were observed except high fever and marked increase of erythrocyte sedimentation rate and c reactive protein. Since clinical trial of antibiotics and antituberculosis agents resulted in no effectiveness, prednisolone was started, but the effect was limited. After that, she complained of the neck pain, and vascular murmur became apparently audible at the pain site. Ultrasonography of the carotid artery revealed the smooth lumen and homogeneous, non-hyperechoic intimal thickening. Then aortography confirmed the diagnosis of aortitis syndrome. Cyclophosphamide combined with steroid therapy diminished the disease activity. In this case, carotid ultrasonography gave us the important information to enforce the aortography. If ultrasonography of the carotid artery has been popularized for aortitis syndrome, and its findings have been standardized, non-invasive diagnosis of this disease will be taken a step forward.

Adult↗
PubMed1995

Association of chronic lymphocytic thyroiditis and thyroid papillary carcinoma. A study of surgical cases among Japanese, and white and African Americans.

BACKGROUND: An association between lymphocytic thyroiditis and thyroid papillary carcinoma is still controversial. To determine a definite statistical relation, a histopathologic study was performed on tissues from in three races, because there is a racial and age-related difference in the susceptibility to thyroiditis. METHODS: The prevalence and severity of thyroiditis combined with adenomatous goiter, follicular adenoma, or papillary carcinoma was defined by examination of surgically resected materials from Japanese (626 patients), and white and African Americans (330 and 90 patients, respectively). RESULTS: The prevalence of lymphocytic infiltrates, which are indicative of autoimmune thyroiditis, was significantly higher in patients with papillary carcinoma than in patients with adenomatous goiter or follicular adenoma among Japanese females (63.0%) and males (50.0%), white females (76.0%), and African American females (46.2%). Lymphocyte infiltration into the follicular adenoma or papillary carcinoma correlated with the severity of combined thyroiditis. CONCLUSION: An association between chronic lymphocytic thyroiditis and papillary carcinoma was confirmed in the Japanese, and white and African American populations. The possibility of autoimmune thyroiditis as a predisposing factor for papillary thyroid carcinoma, is suggested.

Adenoma↗
PubMed1995

Insulin resistance associated with compensatory hyperinsulinemia as an independent risk factor for vasospastic angina.

BACKGROUND: It is generally believed that coronary artery spasm plays an important role in the progression of obstructive coronary artery disease. Since insulin resistance together with hyperinsulinemia plays an important role in the pathogenesis of coronary atherosclerosis, we investigated the association of hyperinsulinemia and insulin resistance with vasospastic angina (VAP). METHODS AND RESULTS: The study population consisted of 60 patients with VAP and 42 control subjects (62 subjects with normal glucose tolerance and 40 with impaired glucose tolerance). Insulin sensitivity was determined by the steady-state plasma glucose (SSPG) method for nondiabetic, normotensive, nonobese subjects (16 control subjects, 16 obstructive coronary artery disease patients, and 16 VAP patients). Compared with the control group, the 2-hour insulin area (area under the plasma insulin concentration-time curve) during a 75-g oral glucose tolerance test was significantly higher in both VAP groups with normal and impaired glucose tolerance. A high frequency of vasospastic angina was observed in subjects with clustered risk factors for insulin resistance syndrome, suggesting a close association of VAP with this syndrome. In stepwise discriminant analysis, the 2-hour insulin area was significantly associated with VAP independent of other risk factors. SSPG level in VAP was about twofold over control, indicating the presence of insulin resistance in patients with VAP. However, no differences were found between patients with VAP and obstructive coronary artery disease with respect to mean SSPG level. CONCLUSIONS: SSPG level was significantly elevated in patients with VAP and obstructive coronary artery disease compared with control subjects. This indicates that hyperinsulinemia is secondary to insulin resistance, both of which are thought to play important roles as risk factors for VAP in the early atheromatous lesion and in the future development of occlusive lesions when chronically present.

Angina Pectoris, Variant↗
PubMed1995

Antiplatelet functions of a stable prostacyclin analog, SM-10906 are exerted by its inhibitory effect on inositol 1,4,5-trisphosphate production and cytosolic Ca++ increase in rat platelets stimulated by thrombin.

The mechanism of the antiplatelet functions of SM-10906, the active form of the 3-oxa-methano-prostaglandin (PG) I1 analog SM-10902, was examined in rat platelets. SM-10906 activated adenylate cyclase in crude membrane fractions, and inhibited platelet aggregation and release of adenine nucleotides stimulated by thrombin. SM-10906 also inhibited malondialdehyde production induced by thrombin, but not that induced by arachidonic acid. This may account for its inhibitory effects on phospholipase A2. SM-10906 prevented thrombin-induced inositol 1,4,5-trisphosphate production, Ca++ mobilization from intracellular Ca storage and 45Ca++ influx into platelets, which were all reversed by pretreatment with the adenylate cyclase inhibitor 2',5'-dideoxyadenosine. PGI2 and PGE1 have the same antiplatelet profiles in the order of PGI2 > or = SM-10906 > PGE1. These results indicate that SM-10906 as well as PGI2 and PGE1 may exert antiplatelet activities by stimulating adenylate cyclase to prevent thrombin-induced phospholipase C and A2 activations and increase in cytosolic Ca++ level.

Adenylyl Cyclases↗
PubMed1995

Anticholinergic effects of class III antiarrhythmic drugs in guinea pig atrial cells. Different molecular mechanisms.

BACKGROUND: It is well known that vagal stimulation increases the vulnerability to atrial fibrillation via muscarinic receptor-mediated shortening of refractory period. Recently it has been reported that some class III antiarrhythmic drugs effectively terminate or prevent atrial flutter and fibrillation by prolonging atrial effective refractory period. However, effects of class III antiarrhythmic drugs on the muscarinic acetylcholine receptor-operated K+ current (IK.ACh), which is important for the repolarization phase of the action potential in atrial cells, have not been thoroughly examined. METHODS AND RESULTS: Effects of three class III antiarrhythmic drugs, d,l-sotalol, E-4031, and MS-551, on the carbachol (1 mumol/L)-induced action potential shortening and outward K+ current were examined in guinea pig atrial cells by conventional microelectrode and patch clamp techniques. In isolated left atria, d,l-sotalol (100 mumol/L), E-4031 (3 mumol/L), and MS-551 (30 mumol/L) partially reversed the carbachol-induced action potential shortening. In isolated single atrial cells, IK.ACh was activated by extracellular application of carbachol (1 mumol/L) or adenosine (10 mumol/L) or by intracellular loading of GTP gamma S (100 mumol/L). Sotalol (3 to 1000 mumol/L), E-4031 (1 to 100 mumol/L), and MS-551 (1 to 100 mumol/L) inhibited the carbachol-induced IK.ACh in a concentration-dependent manner, and their IC50 (half-maximal inhibition) values were 35.5, 7.8, and 11.4 mumol/L, respectively. However, the GTP gamma S-induced and adenosine-induced IK.ACh were inhibited by high concentrations of E-4031 and MS-551 but not by sotalol. CONCLUSIONS: Sotalol may inhibit IK.ACh by the blockade of the atrial muscarinic receptors, whereas E-4031 and MS-551 may inhibit the current not only by blocking the muscarinic receptors but also by depressing the function of the K+ channel itself and/or G proteins. These drugs may potentially be useful for the prevention and termination of atrial flutter and fibrillation through their inhibitory action on IK.ACh.

Acetylcholine↗
PubMed1995

Utilization of hemin and hemoglobin as iron sources by Vibrio parahaemolyticus and identification of an iron-repressible hemin-binding protein.

Several clinical isolates of Vibrio parahaemolyticus were examined for their ability to utilize either hemin or hemoglobin as a sole source of iron. Both compounds appeared to be equally good iron sources. Maximum growth was obtained at 5 microM hemin or 1.25 microM hemoglobin under the conditions tested. Using a hemin-agarose batch affinity method, the hemin-binding protein was isolated from crude total membranes of a hemin-utilizing strain, WP1, grown under iron-deficient but not under iron-sufficient conditions. This protein was identical to the 83 kDa outer membrane protein which was expressed in response to iron limitation. The protein was susceptible to proteinase K cleavage in whole cells, indicating its exposure at the cell surface. Hemin and hemoglobin, but not protoporphyrin IX, inhibited binding of the protein to hemin-agarose.

Carrier Proteins↗