PubMed Health⌕ Search

Biomedical subjects

Y Yamazaki

Publications and source records attributed to Y Yamazaki.

At least 19 recordsLinked to original sources
PubMed1992

Effect of local cyanide perfusion on rat striatal extracellular dopamine and its metabolites as studied by in vivo brain microdialysis.

To investigate in vivo effects of energy failure on functions of dopaminergic neurons, we administered 0 (control), 0.2, 1 or 2 mM sodium cyanide (NaCN) dissolved in Ringer's solution for 60 min into the rat striatum through a brain microdialysis membrane. During NaCN perfusion, a transient and concentration-dependent increase in dopamine (DA) levels in the dialysate was observed. The maximum DA level during 2 mM NaCN perfusion was found to be 63-fold higher than the control levels. Leves of 3,4-dihydroxyphenylacetic acid and homovanillic acid were continuously lowered during and after NaCN perfusion. These data suggest that suppression of ATP production by NaCN induces an abrupt and remarkable increase in dopamine release from the nerve terminal in the striatum.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Immediate effects of percutaneous transvenous mitral commissurotomy on pulmonary hemodynamics at rest and during exercise in mitral stenosis.

Hemodynamics were evaluated during exercise in 33 patients with mitral stenosis who underwent percutaneous transvenous mitral commissurotomy (PTMC). PTMC was performed using an Inoue balloon. Each patient underwent a supine ergometer exercise test before and on the day after PTMC. Ergometer work load was started at 20 W and increased in increments of 20 W at 3-minute intervals until terminated by the patient's fatigue or shortness of breath. Mitral valve area increased by 0.8 +/- 0.4 cm2 (1.1 +/- 0.3 to 1.9 +/- 0.4 cm2, p less than 0.001). Mean mitral pressure gradient decreased (12 +/- 5 to 6 +/- 2 mm Hg, p less than 0.001). Pulmonary arterial pressure significantly decreased and the cardiac index significantly increased both at rest and during exercise after PTMC. Before PTMC, the increases in pulmonary arterial pressure, total pulmonary resistance and pulmonary arteriolar resistance during exercise were greater in patients with a mitral valve area less than 1.0 cm2 than in patients with an area greater than or equal to 1.0 cm2. After PTMC, total pulmonary resistance still increased during exercise. However, pulmonary arteriolar resistance did not change during exercise in patients with a mitral valve area greater than or equal to 1.5 cm2, whereas it increased in patients with an area less than 1.5 cm2. An enlarged mitral valve area greater than or equal to 1.5 cm2, which may prevent pulmonary vasoconstriction and permits a greater increase in pulmonary blood flow during exercise, is considered a good result immediately after PTMC.

Cardiac Catheterization↗
PubMed1992

Diffuse nerve fiber layer loss in normal tension glaucoma.

14 eyes of 14 normal tension glaucoma (NTG) patients with the maximum intraocular pressure (IOP) > or = 19 mmHg and 16 eyes of 16 NTG patients with the maximum IOP < 19 mmHg were examined. All patients had a scotoma confined to the upper or lower hemifield. Eyes with the maximum IOP > or = 19 mmHg showed significantly diffuse retinal nerve fiber layer (RNFL) loss in the RNFL area corresponded to the spared visual hemifield as compared to those with the maximum IOP < 19 mmHg. The results suggests that, even in NTG, IOP may be an important factor causing optic nerve damage.

Female↗
PubMed1992

Evaluation of hepatic density change by dynamic CT in healthy humans and in patients with chronic liver diseases.

Dynamic computed tomography using 0.4 ml/kg of 65% meglumine diatrizoate was performed to estimate pharmacokinetics of contrast media in the liver in healthy controls (N = 11), in patients with chronic viral hepatitis (N = 17), posthepatic liver cirrhosis (N = 21), and alcoholic liver cirrhosis (N = 23). The time of peak enhancement (the time interval between peak aortic and liver enhancement) was significantly different between each group. Alcoholic liver cirrhosis was the most prolonged, followed by posthepatic liver cirrhosis, chronic viral hepatitis, and finally controls. A peak enhancement time of 28 sec had a diagnostic accuracy of 97% for chronic liver diseases. A time greater than 44 sec had a diagnostic accuracy for cirrhosis of 96%. The decay time (the time from peak enhancement of the liver to the curve's center of gravity) was also significantly different between each group. Again, alcoholic liver cirrhosis was the longest, followed by posthepatic liver cirrhosis, chronic viral hepatitis, and then the controls. Dynamic computed tomography has many potential applications in studying intrahepatic physiologic events and may contain diagnostic information for chronic liver diseases.

Adult↗
PubMed1992

Multiple cis-acting DNA elements that regulate transcription of the adenovirus 12 E1A gene.

To delineate cis-acting elements for adenovirus (Ad) 12 E1A gene transcription, we transfected HeLa and NIH3T3 cells with DNAs having various deletions in the 5'-upstream region linked to the chloramphenicol acetyltransferase gene. Deletions in the regions between nucleotide (nt) positions 54 and 166, and 167 and 200, with respect to the left end of the viral genome at nt position 1, caused a two- to three-fold reduction in transcription. Transcription decreased to an almost undetectable level with loss of the region between nt positions 201 and 282. The effect of these mutations was almost consistent between both cell lines. The region between nt positions 77 and 94 stimulated transcription when situated upstream of the simian virus 40 early promoter in either orientation. Transcription was stimulated about ninefold in the presence of the DNA that encodes the product of the 13S, but not the 12S mRNA of the Ad12 E1A gene. These results indicate that transcription of the Ad12 E1A gene is regulated by multiple cis-acting elements and is stimulated by its own gene product.

3T3 Cells↗
PubMed1992

Balloon catheter with check valves for experimental relief of acute aortic regurgitation.

To evaluate the ability of a newly designed balloon catheter with check valves to temporarily relieve hemodynamic deterioration in acute aortic regurgitation, we produced an experimental model of acute aortic regurgitation in closed-chest dogs using endomyocardial biopsy forceps. Aortic regurgitation was produced until an increase in aortic pulse pressure of over 50% was achieved. Left ventricular end-diastolic pressure rapidly increased after the production of aortic regurgitation. Immediately after the catheter began functioning, pulse pressure decreased from 133 +/- 1 to 78 +/- 5 mm Hg (mean +/- SEM) and left ventricular end-diastolic pressure also decreased from 26 +/- 1 to 13 +/- 1 mm Hg. These effects lasted as long as the catheter functioned. Although a mild (21 +/- 8 mm Hg) pressure gradient between the left ventricular peak systolic pressure and the aortic peak systolic pressure was observed when this catheter was used, forward stroke volume was no less than in the group in which the catheter had not been used. These findings suggest that the balloon catheter with check valves may effectively reduce aortic regurgitation.

Animals↗
PubMed1992

Effects of destructive periodontitis, induced by diet, on the mechanical properties of the periodontal ligament of the mandibular first molar in golden hamsters.

To examine progressive changes in the mechanical properties of the periodontal ligament in the hamster mandibular first molar with experimental periodontitis--induced by feeding a high-carbohydrate diet--load-deformation curves obtained by extracting the tooth from its socket in the dissected jaw were analyzed. The maximum shear load, elastic stiffness and failure energy in shear in the experimental groups decreased significantly during the experimental period. On the other hand, significant differences in the maximum deformation were not found between the experimental and the relevant control groups. Radiographic and histological observations showed that the alveolar bone loss and destruction of the periodontal tissues occurred at the cervical region of the tooth in the experimental animals at 8 and 12 weeks after the start of the experiment. It is suggested that the reduction of the mechanical strength of the periodontal ligament in the experimental animals may be due to the alveolar bone loss, destruction of the periodontal tissues at the cervical region--particularly on the lingual aspect--followed by a decrease in the surface area of the ligament. It is also suggested that degenerative changes in the remaining periodontal ligament occurred in hamsters with periodontal disease, causing a reduction in the mechanical strength of the ligament.

Alveolar Bone Loss↗
PubMed1992

A case of vasovagal syncope with convulsions--the effects of midodrine hydrochloride.

A 42-year-old female had suffered from repeated syncope. She had vasovagal syncope with convulsions from vasodilatation and cardiac standstill which lasted for 9.8 sec. The 60 degrees head-up tilt test, nitroglycerin injection and isoproterenol infusion provoked vasovagal reaction. Although a beta blocker was not effective in preventing tilt-induced hypotension and bradycardia, midodrine hydrochloride (alpha-1 stimulant) or atropine prevented it. In this patient, insufficient constriction of capacitance vessels might have played an important role in activation of an inhibitory reflex from cardiopulmonary mechanoreceptors which caused hypotension and bradycardia.

Adult↗
PubMed1992

Type and amount of environmental information in urban scene--basic study on the design of intelligence environment.

Signs have gained importance as an information mechanism that supports the urban activities in signage, and projects are being actively launched in cities. Urban spaces are already filled with multitudes of signs including directories and signboards, calling for organization of signage as a system and not merely as a collection of individual signs. As a first step for tackling with the objectives, the present study noted the type and amount of environmental information presented in the realm of pedestrians. Our study included (1) investigating the type and amount of information available in the streets including underpass; (2) classifying and organizing signs according to the content of information; and (3) analyzing the relation between different types of information, between situations and signs, and continuity of the signs of the same type. The study revealed that there was a (1) deviation in information offered at various spots on a pedestrian route; (2) multitudes of advertisements and installations other than signs were placed at the same spot using the same method as the public signs; and (3) there were qualitative lack of signs despite many signs in the investigated area. The study thus indicated a need for cross-sectional environmental design for information in place of sign designs and delineates several basic requirements for it.

Environment Design↗
PubMed1992

[Silent myocardial ischemia in myocardial infarction patients: its prognostic significance].

To evaluate the prognostic and clinical significance of silent myocardial ischemia (SMI), we examined cardiac events in 160 patients with old myocardial infarction who underwent ambulatory Holter monitoring, treadmill exercise testing and coronary angiography. Using the Cox's proportional hazard regression model and the survival curves with the Kaplan-Meier method, we identified the predictors of cardiac events. The incidence of cardiac events for all the patients during the 44-month follow-up period was 18%. The significant predictors of unfavorable outcomes were severe coronary lesions and SMI. The incidence of SMI was 38%. The cardiac event rate in patients with SMI was higher than in those without SMI (32 vs 9%, p < 0.05). The most frequent cardiac event in patients with SMI was reinfarction, and the significant predictors of cardiac events for these SMI patients were lower ejection fraction and maximum ST depression on Holter monitoring. In conclusion, SMI proved to be a significant predictor of unfavorable outcome in patients with old myocardial infarction. It was, therefore, suggested that revascularization (PTCA/CABG) should be used as early as possible in patients with SMI whether anginal symptoms are present or not.

Aged↗
PubMed1992

Effect of nipradilol on cardiovascular hemodynamics during exercise in angina pectoris with old myocardial infarction.

Nipradilol (3,4-dihydro-(2-hydroxy-3-isopropylamino)-propoxy-3-nitroxy-2H-1- benzopyran, K-351, CAS 81486-22-8) is a new type of beta-blocker with vasodilating action. The effect of nipradilol on hemodynamics at rest and during exercise with a multi-stage bicycle ergometer in supine position was studied in 8 male patients suffering from angina pectoris with old myocardial infarction. Nipradilol was orally given at the daily dose of 12 mg (b.i.d.) for one week, and various hemodynamic parameters were measured at rest and during exercise before and after the treatment with nipradilol. At rest, the blood pressure was almost unchanged, heart rate was significantly reduced, cardiac output tended to decrease, and the pulmonary blood pressure and left ventricular ejection fraction (EF) were almost unchanged. At peak exercise, the blood pressure tended to decline, heart rate was significantly reduced, cardiac output tended to decrease and the pulmonary blood pressure and EF increased significantly. Consequently, the antianginal effect of nipradilol is considered to be attributable to the reduction in myocardial oxygen consumption caused by a decrease in double product. It is thus suggested that nipradilol exerts its antianginal effect without adversely affecting the cardiac performance.

Adrenergic beta-Antagonists↗
PubMed1992

Importance of acidic mucin secretions by foveolar and mucous neck cells of rat fundic mucosa as the defence mechanisms against HCl as revealed by fasting.

The localization of neutral mucin and acidic mucins in both control and fasted rat gastric fundic mucosa were examined by microscopic and electron microscopic histochemical methods. By Carnoy's fixation, the surface mucous coat of the control rat gastric fundic mucosa was found to be composed of alternating layers of acidic mucins and neutral mucin, indicating the synchronous and cyclic secretions of them. In many gastric pits of the fundic glands, the acidic mucins were found to spring out from the deep foveolar regions like volcanoes. This phenomenon may suggest that the acidic mucins play a fundamental role in protecting the pit cells against HCl during its passage, and the layers of neutral mucin and acidic mucins in the surface coat is the safeguard against the HCl and digestive enzymes in the gastric lumen. In the fasting rat gastric fundic mucosa, the acidity and the amount of the gastric juice were markedly decreased, indicating the suppressed secretions of mucins and HCl. The decreased production of sulfomucin was directly demonstrated by 35SO4-autoradiography. Many mucous neck cells existing in close association with the parietal cells were ballooned due to accumulation of alcian blue (AB)-positive but high iron-diamine (HID)-negative sialomucin, which was not demonstrable in the control. The secretory granules of sialomucin contained in the ballooned mucous neck cells were positively stained ultrastructurally with cacodylate-ferric colloid to stain acid mucopolysaccharides.

Acid Phosphatase↗
PubMed1992

Data compression of electrocardiograms for long-time digital recording in IC memory.

To realize a digital recorder capable of long-time recording of electrocardiograms (ECGs) in IC memories, the methods of data compression were studied and the accuracy of reconstructed ECGs from the compressed ones was evaluated. Concretely, the variant of MSAPA was used as a data compression algorithm in order to store ECGs in IC memories for 12-24 h. The fabricated digital recorder used an 8 bit CPU with the function of data compression and was capable of operating in real time at a sampling rate of 200 Hz. With bit compression, 24 samples of American Heart Association ECGs were compressed to an average value of 16.8% under the condition of an error limit of 30 microV (120 microV in QRS); the average maximum recording time in 1 Mbyte IC memories was 8.5 h. In a comparison of the reproduction accuracy and errors produced by a small analog tape recorder with those produced by the digital method, the digital system was shown to be superior to the analog system.

Algorithms↗
PubMed1992

[Left atrial myxomas: clinical characteristics, evaluation and considerations in classifying tumors].

Eleven patients underwent surgical excision for left atrial myxomas. Clinical symptoms, coronary angiographic findings and operative procedures were evaluated. Myxomas were classified into two types based on macroscopical findings, and clinical characteristics of these two types were analyzed. Seven cases (64%) classified as "lobular-type myxomas" were seen as lobulated, gelatinous and fragile. Four cases (36%) were classified as "round-type myxomas" were round and elastic soft. Primary symptoms included dyspnea on exertion in five cases (45%) and neurological disturbances in six cases (55%). Brain emboli were found in four patients by CT scan, and were classified as lobular-type myxomas. These eleven myxomas successfully removed in all cases. Four of these myxomas, which were pedunculated with fine fibrous stalks, were shaved along the base at the atrial septum or free wall. Others were excised completely along with a portion of the adjacent septum. Microscopic examination of the operative specimens revealed that two lobular-type myxomas with broad-based attachment to left atrial septum had invaded the atrial septum. All patients are doing well and have had no signs of myxoma recurrence at postoperative periods ranging from 10 months to 12 years (mean follow-up 5.3 years). Seven patients underwent selective coronary angiography due to a diagnosis of a coronary artery disease. All coronary angiograms were normal in all cases. In five (71%) of these seven, abnormally dilated atrial branches were seen as supplying the tumor. In two cases with round-type myxomas, neovascularity was evident and was made up of clusters of tortuous vessels with tumor blush.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[A case of humidifier lung associated with BHL].

We encountered a rare case of hypersensitivity pneumonitis associated with bilateral hilar lymphadenopathy (BHL). The patient was a 53-year-old male, who developed dry cough and shortness of breath when using a humidifier since 1982. He was admitted to our hospital for further evaluation in 1987. Chest X-ray films showed BHL and ground glass appearance in the bilateral lung fields. Pulmonary function test indicated disturbance of diffusing capacity. Transbronchial lung biopsy revealed interstitial pneumonitis, and lymph node biopsy by mediastinoscopy showed lymphoid sinus histiocytosis without noncaseating granuloma. Provocation test using the humidifier was positive, and the diagnosis of humidifier lung with BHL was made.

Alveolitis, Extrinsic Allergic↗
PubMed1992

[A case of congenital cystic adenomatoid malformation of the lung in 18-year-old male].

A case of congenital cystic adenomatoid malformation (CCAM) of the lung is reported. The patient had recurrent pneumonia after the second day of delivery, and was admitted to our hospital, at the age of 18. He received right pneumonectomy under the diagnosis of CCAM. The resected lung was composed of multiple cysts with thin wall measuring 20-30 mm in diameter. Microscopic examination showed that the cyst wall was lined by ciliated columnar epithelium, and infiltration of chronic inflammatory cells was found in the submucosal layer. Bronchial cartilage was absent through the specimen. These microscopic findings are identical with those of CCAM, which is very rare in this age.

Adolescent↗
PubMed1992

[The neurological outcome in patients with acute cervical spinal cord injury].

UNLABELLED: Twenty-three patients (twenty males and three females) with acute cervical spinal cord injury were cared for within a defined protocol and followed for 14 to 589 days (mean. 133 days). We evaluated the relationship between neurological recovery and neurological examination, myelography (MLG), CT-myelography (CTM) on admission. All of them were admitted to Kitasato University Hospital within 24 hours after injury. Thirteen of the 23 patients had complete injury, and the others had incomplete injury. RESULT: Four factors were found to be related to neurological recovery. They included: 1) complete injury; 2) areflexia; 3) cord swelling on CTM; and 4) complete block on MLG. Fourteen of 15 patients who had at most two of the four factors improved. But, no patients with three or four factors improved. CONCLUSION: These four factors have been recognized as indicators of bad neurological outcome. However, our result indicates that by our result, improvement of neurological function can be expected in patients affected by only one or two of these four factors. In other words these four factors have prognostic value for predicting the neurological outcome after acute cervical spinal cord injury.

Acute Disease↗