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Biomedical subjects

K Sakata

Publications and source records attributed to K Sakata.

At least 343 records · Page 19Linked to original sources
PubMed1992

Receptor agonists induce myosin phosphorylation-dependent and phosphorylation-independent contractions in vascular smooth muscle.

In isolated rat aorta, 72.7 mM KCI, 10 microM prostaglandin F2 alpha, 30 nM endothelin-1 and 1 microM norepinephrine increased muscle tension, cytosolic Ca++ concentration ([Ca++]i) and 20 kDa myosin light chain (MLC) phosphorylation. The levels of contractile tension and MLC phosphorylation at a given [Ca++]i were greatest in the presence of endothelin-1 followed by prostaglandin F2 alpha greater than norepinephrine greater than high K+. Verapamil inhibited the high K(+)-induced increments to their respective resting levels. Verapamil also almost completely inhibited the receptor agonist-induced increments in [Ca++]i and MLC phosphorylation, although a part of the contraction was not inhibited. Ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid further decreased [Ca++]i and muscle tension, suggesting that a part of the contraction is regulated by [Ca++]i below a resting level. Receptor agonists induced sustained contraction in the absence of external Ca++ which was not followed by the increase in [Ca++]i or MLC phosphorylation. This contraction was followed by the increments in shortening velocity and stiffness. In the rabbit mesenteric artery permeabilized with Staphylococcus aureus, alpha-toxin, norepinephrine and endothelin-1 shifted the Ca(++)-tension curve to the left in the presence of GTP. From these results, it is suggested that high K(+)-induced sustained contraction of vascular smooth muscle is attributable to an increase in [Ca++]i followed by an increase in MLC phosphorylation. In addition to this fundamental mechanism, receptor agonists increase Ca+ sensitivity of MLC phosphorylation when [Ca++]i is higher than resting level resulting in a greater contraction than that induced by high K+ for a given increase in [Ca++]i.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Antihypertensive effects and pharmacokinetics of NZ-105 single administration in patients with hypertension].

The influence of renal function on the antihypertensive effect and pharmacokinetics of NZ-105 were studied in 7 patients with essential hypertension (EH) and 6 patients with hypertension having impaired renal function (RH). 1. As for the hypertensive effect, both in EH and RH, the maximum antihypertensive effect was attained 3 to 5 hr after drug administration and there was not significant difference between EH and RH. 2. There was not significant difference in transition of plasma concentration of NZ-105 between EH and RH. 3. Concerning pharmacokinetic parameters of NZ-105, there was significant difference between EH and RH in Tmax. at 20 mg of NZ-105 administration. However, in regard to Tmax. at 30 mg of NZ-105 administration and Cmax., AUC and t1/2 at 20 mg, 30 mg of NZ-105 administration, there were not significant differences between EH and RH. 4. There was no correlation between t1/2 and serum creatinine levels. 5. All cases showed good tolerance without any adverse effect.

Adult↗
PubMed1992

[Two cases of Marfan syndrome, surgically treated for complicating spontaneous pneumothorax].

Two cases of spontaneous pneumothorax in the patients of Marfan Syndrome were reported. Nine and 13-year-old girls were admitted to our hospital complaining of chest pain and dyspnea for the first time. Tension pneumothorax was confirmed by the chest radiograph. Both of them had the physical stigmata of Marfan Syndrome including cardiovascular abnormalities. The drainage tube was inserted into the thoracic cavity. As the drainage was ineffective, the surgical treatment was undertaken. The thoracic cavity was opened though axillary incision and bullae were resected. The patient of pneumothorax with the Marfan Syndrome should be examined preoperatively about cardiovascular abnormality using chest computed tomography and echocardiography. As far as the surgical intervention was concerned, the axillary approach is preferred to the median sternotomy, as such patient highly probably require cardiovascular operation in future.

Adolescent↗
PubMed1992

[A case report of true palmar aneurysm].

True palmar aneurysm is a rare disease of the hand. Only 12 cases of true palmar aneurysm have been reported in Japan. This occurs commonly in the hypothenar region. We experienced a 12-year-old boy who had a aneurysm of the left palmar hand successfully treated by surgery. The clinical diagnosis was established by ultra sound. Vascular reconstruction by end to end anastomosis was performed after excision of aneurysm. Pathology revealed this was true aneurysm.

Anastomosis, Surgical↗
PubMed1992

[Management of infective endocarditis].

Clinical manifestations and the results of management of infective endocarditis were reported. Of 46 patients, 17 cases received medical treatment alone (group A), and 29 cases underwent surgical interventions (group B). Affected valves were aortic in 29, and mitral in 24. In group B, however, infection occurred on the aortic valve in 22, and on the mitral valve in 11. Aortic valve was more often affected in group B than in group A (p less than 0.05). Embolic complications were observed in 5 of group A, 4 of whom had involvement of cerebral vessels, and in 4 of group B, all of whom had cerebral emboli. Of 8 cerebral embolic episodes, 6 emboli originated from mitral valvular lesions. In group A, 6 (35.3%) died of cerebral accidents or acute heart failure within 30 days after the onset of illness. In group B, 20 cases were operated on at chronic stage, and 9 cases underwent operation at active stage. Various procedures, alleged to be the most favorable, were selected to the individual patient. No mortality was found in the former group, but one patient (11.1%) in the latter group died of multiple organ failure 31 days after surgery. All patients, who were operated on at active stage, received intravenous administration of antibiotics for 6 to 8 weeks after the operation. Comparing the actuarial survival rate of group A and group B, group B was superior to group A for initial 4 years, but no significant difference was discernible thereafter.

Actuarial Analysis↗
PubMed1992

[A case of tricuspid valvular myxoma in a child].

A six-year old boy had hospitalization because of cardiac murmur and syncope attack. Laboratory data including immunoglobulin and erythrocyte sedimentation rate were normal, but echocardiography and cardioangiography indicated tricuspid valvular myxoma in the right atrium. The tumor was successfully removed with the septal tricuspid valve using the cardiopulmonary bypass. The tumor was 18 x 20 x 12 mm in size and pathological findings showed a myxoma originated from tricuspid valve. Now he shows normal cardiac function and no recurrent sign of tumor. There has been reported a few cases of valvular myxoma in Japan. However, this is the first case which was successfully resected by surgery.

Child↗
PubMed1991

Plasminogen activator inhibitor activity as a possible indicator of disease activity in rest angina with angiographically insignificant coronary artery stenosis.

To assess the role of fibrinolytic system, 19 patients with rest angina and insignificant coronary artery stenosis and 23 controls performed symptom-limited multistage exercise. Vasospasm was angiographically demonstrated in 12 patients. Pre- and peak exercise blood samples from each patient were assayed to determine the fibrinolytic components. The patients displayed significantly increased PAI activity both under the basal conditions (p less than 0.01) and at peak exercise (p less than 0.01) as compared with the controls. However, the values of other fibrinolytic components, such as t-PA antigen, t-PA/PAI-1 complex and free PAI-1 antigen, in the controls and patients were similar. Nineteen patients were divided into two groups according to PAI activity levels under basal conditions. Nine patients displayed high PAI activity (more than the mean + 1 SD of the control value) under the basal conditions. When compared to the remaining 10 patients, the high PAI activity group had both a significantly short time interval from the last attack to the time of getting the blood sample (p less than 0.05), and a worse short-term prognosis (p less than 0.05). Thus, the level of PAI activity under basal conditions reflected the extent of disease activity, suggesting that PAI activity may be a useful clinical indicator of the severity of rest angina in patients without significant coronary stenosis.

Adult↗
PubMed1991

Synergistic stimulatory effect of glucocorticoid, EGF and insulin on the synthesis of ribosomal RNA and phosphorylation of nucleolin in primary cultured rat hepatocytes.

Effects of dexamethasone, EGF and insulin on the synthesis of rRNA and phosphorylation of nucleolin in primary cultures of adult rat hepatocytes were studied. Hepatocytes were incubated for 8 h with EGF (20 ng/ml) plus insulin (0.1 microM) and/or for 20 h with dexamethasone (1 microM) before the end of incubation. The incorporation of [3H]uridine into acid-insoluble materials and the nuclear activity of RNA polymerase I were stimulated approx. 2-fold with EGF plus insulin and these were further enhanced 2-3-times by dexamethasone, although dexamethasone alone exerted no stimulation. When hepatocytes were incubated with [32P]orthophosphate, similar enhancement by these hormones was also observed in the phosphorylation of a nucleolar protein, nucleolin, which was detected by immunoprecipitation with anti-nucleolin antibodies. The amount of nucleolin was slightly increased by EGF plus insulin in the presence of dexamethasone, but scarcely changed by treatment with EGF plus insulin or dexamethasone alone. Cycloheximide inhibited RNA synthesis to a greater or lesser degree in the case of all hepatocytes which were cultured with or without these hormonal treatments. These results indicate that the in vivo effect of glucocorticoid on rRNA synthesis and nucleolin phosphorylation in liver is primarily a direct action on parenchymal cells and requires other growth factors such as EGF and insulin.

Animals↗
PubMed1991

Clinical application of indium-111 antimyosin antibody and thallium-201 dual nuclide single photon emission computed tomography in acute myocardial infarction.

The significance of indium-111 antimyosin antibody and thallium-201 dual nuclide single photon emission computed tomography (SPECT) was evaluated in 7 patients with acute myocardial infarction (AMI) who underwent emergency coronary angiography with successful revascularization by intracoronary thrombolysis. Indium-111 antimyosin antibody and thallium-201 dual nuclide SPECT was performed 11 to 36 days after the onset of AMI. Antimyosin SPECT images delineated areas of myocardial necrosis in all 7 patients (100%), but planar images detected necrotic areas in only 4 of 7 patients (57%). Peak CPK-MBs of the 3 patients in which no necrotic area was detected by indium-111 planar image showed a tendency to be smaller. Indium-111 antimyosin antibody/thallium-201 overlap was observed in all patients. The area of overlap was at the center of necrosis in 4 patients (2 anterior infarction, 1 inferior infarction, 1 inferolateral infarction) and at the peripheral portion in 3 patients (all 3 had inferior infarction). Indium-111 antimyosin antibody and thallium-201 dual nuclide SPECT is useful in identifying the localization of myocardial infarction and the overlap of these tracers might reflect the presence of salvaged myocardium adjacent to the necrotic myocardium.

Aged↗
PubMed1991

Hypoxia-induced drug resistance: comparison to P-glycoprotein-associated drug resistance.

In this report, we investigate several examples of hypoxia-induced drug resistance and compare them with P-glycoprotein associated multidrug resistance (MDR). EMT6/Ro cells exposed to drugs in air immediately after hypoxic treatment developed resistance to adriamycin, 5-fluorouracil, and actinomycin D. However, these cells did not develop resistance to colchicine, vincristine or cisplatin. When the cells were returned to a normal oxygen environment, they lost resistance. There was no correlation between the content of adriamycin and the development of adriamycin resistance induced by hypoxia. There was no difference between the efflux of adriamycin from aerobic cells and that from hypoxia-treated cells. The mRNA for P-glycoprotein was not detected in the hypoxia-treated cells. These results suggest that hypoxia-induced drug resistance is different from P-glycoprotein associated multidrug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Telecanthal approach for meningiomas in the ethmoid and sphenoid sinuses.

In three cases involving meningiomas in the ethmoid and sphenoid sinuses, transbasal spreading of the interocular distance (telecanthal approach) was used for tumor removal and reconstruction of the skull base. This telecanthal approach involves 1) bilateral en bloc removal of the superior lateral rim of the orbit, the nasal bone, and the posterior lateral wall of the orbit; 2) detachment of the medial canthal ligaments; and 3) spreading of the interocular distance. This approach provides a wide working space beneath the anterior half of the midline skull base, and needs neither a facial incision nor significant retraction of the brain. The surgical technique and its modification are described. The discussion focuses not only on comparisons with other techniques, but on the indications for this approach. Meningiomas originating in the paranasal sinuses are rare; a brief review of the literature concerning the clinicopathological features and pathogenesis is also given.

Adult↗
PubMed1991

Apneusis in a man with a supratentorial tumor.

A 67-year-old 163-cm tall man weighing 56 kg was scheduled for right fronto-temporal craniotomy following a diagnosis of right supratentorial brain tumor. Prior to surgery he was somnolent, but response to verbal questioning was accurate. Heart rate was 50 beats/min, respiratory rate 20 breaths/ min, and blood pressure 148/80 mm Hg. Neurological examinations revealed a space-occupying lesion in the right frontal deep white matter and basal ganglia, and a moderate increase in intracranial pressure. There were no signs of brain-stem dysfunction. Upon arrival in the operating room and before the induction of anesthesia, the impedance pneumograph showed an apneustic respiratory pattern, which, along with bradycardia, persisted until the 5th postoperative day. A diagnosis of anaplastic astrocytoma of Grade III was made postoperatively. Usually we record the respiratory pattern in patients with brain injury or with brain tumor prior to surgery. We noted the apneustic pattern in one of 49 patients with head injuries and brainstem dysfunction and in one of 98 with brain tumor, but none of 55 medical student volunteers. The rate of occurrence of apneusis in patients with brain disease is 2 of 147 (1.36%).

Journal Article↗
PubMed1991

Tissue distribution of mouse mammary tumor virus (MMTV) antigens and new endogenous MMTV loci in Japanese laboratory mouse strains.

The distribution of mouse mammary tumor virus (MMTV) antigens was studied by the immunoperoxidase method in the II-TES and I-TES mouse strains as well as their progenitors, CS and DBA/2 strains. In the II-TES, I-TES and CS strains, and BALB/c mice foster-nursed with these strains, MMTV antigens were found not only in epithelial cells of the mammary glands but also in those of other tissues including the seminal vesicle, vas deferens, epididymis, prostate, parotid, submandibular, lacrimal, sebaceous, and urethral glands. In DBA/2 and BALB/cfDBA/2 mice, however, the MMTV antigens were found only in the mammary glands. Electron microscopic examination showed MMTV particles in these organs. When we examined the presence of Mtv-1 and 2 proviruses, which are known to be responsible for MMTV expression, in the genomes of the II-TES, I-TES, CS and DBA/2 strains by Southern blotting, Mtv-2 was not found in any of the mice and Mtv-1 was found in the II-TES and DBA/2 mice but not in the I-TES and CS mice. Instead, four new endogenous MMTV loci, which have never previously been reported in laboratory mouse strains, were detected in the genomes of the II-TES, I-TES and CS strains. One (designated Mtv-42) was common in the three strains and the other three (designated Mtv-43, 44 and 45) were common in the II-TEX and I-TES strains or the II-TES and CS strains. These results thus suggest that new endogenous MMTV loci may be responsible for MMTV expression in a variety of tissues of these three strains.

Animals↗
PubMed1991

Effects of a novel smooth muscle relaxant, KT-362, on contraction and cytosolic Ca2+ level in the rat aorta.

1. Inhibitory effects of a novel smooth muscle relaxant, KT-362 (5-[3-([2-(3,4-dimethoxyphenyl)-ethyl]amino)-1-oxopropyl]-2,3,4,5- tetrahydro-1,5-benzothiazepine fumarate), on contraction and the cytosolic Ca2+ level ([Ca2+]cyt) in isolated vascular smooth muscle of rat aorta were examined. 2. KT-362 inhibited the contractions induced by high K+ and noradrenaline. The inhibitory effect was antagonized by an increase in external Ca2+ concentration. A Ca2+ channel activator, Bay K 8644, did not change the effect of KT-362 on high K+-induced contraction. 3. [Ca2+]cyt, measured with fura-2-Ca2+ fluorescence, increased during the contractions induced by high K+ or noradrenaline. KT-362 decreased [Ca2+]cyt and muscle tension stimulated by high K+ or noradrenaline. By contrast, a Ca2+ channel blocker, verapamil, inhibited the noradrenaline-induced increase in [Ca2+]cyt with only partial inhibition of the noradrenaline-induced contraction and KT-362 inhibited the verapamil-insensitive portion of the contraction without changing [Ca2+]cyt. 4. In a Ca2(+)-free solution, noradrenaline and caffeine induced a transient contraction following a transient increase in [Ca2+]cyt. KT-362 inhibited the increments due to noradrenaline but not those induced by caffeine. 5. These results suggest that KT-362 inhibits vascular smooth muscle contraction by inhibiting Ca2+ channels, receptor-mediated Ca2+ mobilization, and receptor-mediated Ca2+ sensitization of contractile elements.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Electrocardiographically and symptomatically silent myocardial ischemia during exercise testing.

Certain patients with coronary artery disease (CAD) may have neither ST depression nor chest pain during exercise despite the presence of myocardial ischemia. The frequency and characteristics of such electrocardiographically and symptomatically silent ischemia were studied in 171 patients with both angiographically documented CAD and scintigraphically documented ischemia. Fifty-six (33%) of 171 patients had neither ST depression nor chest pain (Group N), and 115 (67%) had ST depression and/or chest pain (Group P). The two groups were similar with respect to age, gender, the prevalence of prior infarction, and peak systolic blood pressure. Group N patients, however, had a higher mean peak heart rate and rate-pressure product, less severe scintigraphic ischemia, a lower lung thallium-201 uptake, and a smaller number of diseased vessels. Stepwise discriminant analysis showed a history of effort angina, lung thallium-201 uptake, and scintigraphic severity of ischemia to be significant discriminators between Groups N and P. In conclusion, electrocardiographically and symptomatically silent ischemia may be common during exercise in patients with CAD, and less severe ischemia may be one of important determinants.

Coronary Angiography↗
PubMed1991

[A study on health examination services under the Health Service Law for the Aged--multiple logistic regression analysis of service methods and the service-acceptance rate].

A survey on health services provided in accordance with the Health Service Law for the Aged was conducted in 3,278 cities, wards, towns, and villages throughout Japan in May 1985. Responses were returned from 2,645 districts and data on beneficiaries of these health services in 2,625 districts became available. Because the exact number of people constituting the subjects of health services could not be obtained, the service-acceptance rate was calculated by the number of people utilizing the services divided by the those in the population who were at least 40 years old. The service-acceptance rate was affected by both the size of the population of the local community and the methods of implementation of health services. Therefore, the mutual effects of population size and service methods were corrected by logistic regression analysis to find the relationship between methods of implementing health services and the response rate of the public in accepting the services. The service-acceptance rate was divided into two categories: one less than 30% and the other 30% and over. Odds ratios were calculated for an acceptance ratio of 30% and over. The results were summarized as follows: 1. In the jurisdictions where the local organizations cooperated in notifying citizens about the results of their general health examination, in comparison with the areas where there was no cooperation, the odds ratio was found to be 2.40. A similar comparison was made between the communities with local cooperation for notification of a general health examination and those communities without it. The odds ratio for the former was found to be 1.66.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗