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Biomedical subjects

S Yamagata

Publications and source records attributed to S Yamagata.

At least 145 records · Page 8Linked to original sources
PubMed1987

Partial purification and some properties of homoserine O-acetyltransferase of a methionine auxotroph of Saccharomyces cerevisiae.

A wild-type strain and six methionine auxotrophs of Saccharomyces cerevisiae were cultured in a synthetic medium supplemented with 0.1 mM L-cysteine or L-methionine and analyzed for the synthesis of homoserine O-acetyltransferase (EC 2.3.1.31). Among them, four mutant strains exhibited enzyme activity in cell extracts. Methionine added to the synthetic medium at concentrations higher than 0.1 mM repressed enzyme synthesis in two of these strains. The enzyme was partially purified (3,500-fold) from an extract of a mutant strain through ammonium sulfate fractionation and chromatography on columns of DEAE-cellulose, Phenyl-Sepharose C1-4B, and Sephadex G-150. The enzyme exhibited optimal pH at 7.5 for activity and at 7.8 for stability. The reaction product was ascertained to be O-acetyl-L-homoserine by confirming that it produced L-homocysteine in an O-acetyl-L-homoserine sulfhydrylase reaction. The Km for L-homoserine was 1.0 mM, and for acetyl coenzyme A it was 0.027 mM. The molecular weight of the enzyme was estimated to be approximately 104,000 by Sephadex G-150 column chromatography and 101,000 by sucrose density gradient centrifugation. The isoelectric point was at pH 4.0. Of the hydroxy amino acids examined, the enzyme showed reactivity only to L-homoserine. Succinyl coenzyme A was not an acyl donor. In the absence of L-homoserine, acetyl coenzyme A was deacylated by the enzyme, with a Km of 0.012 mM. S-Adenosylmethionine and S-adenosylhomocysteine slightly inhibited the enzyme, but methionine had no effect.

Acetyltransferases↗
PubMed1987

[An autopsy case of AFP-producing gastric carcinoma resembling hepatocellular carcinoma on light microscopy].

We experienced an autopsy case of alpha-fetoprotein(AFP)-producing advanced gastric carcinoma with liver metastasis. Microscopically, the tumor was compose by medullary nests of poorly differentiated adenocarcinoma cells. The cells had an exclusively hepatoid pattern characterized by discrete masses, nests, and broad bands, consisting of large eosinophilic epithelial cells and separated by fibrous stroma. Immunohistochemical studies of hepatoid cells yielded a positive reaction for AFP, but negative for CEA. Electron microscopically, tumor cells possess a ductal lumina with abundant microvilli having a central core filaments, and secretory granules in cytoplasma. These findings suggest that the tumor cells differentiated into intestinal direction, irrespective of the appearance of their hepatoid features characterized by light microscopy.

Adenocarcinoma↗
PubMed1987

[Evaluation of regional cortical blood flow by thermal diffusion using a Peltier stack].

The possibility of quantitative evaluation of cerebral blood flow (CBF) by thermal diffusion has been reported, when the thermal gradient was created by a Peltier stack. We already described the linear relationship between the CBF and the inverse of thermal gradient elsewhere when the CBF measured by hydrogen clearance (Hydrogen CBF) was compared to the values estimated by thermal diffusion. In this paper, the correlation of linear relationship between the thermal CBF and hydrogen CBF in each animal was first investigated. Secondary, the possibility of in vitro calibration for quantitative evaluation was discussed. Two kinds of probes were manufactured. One was treated not to leak the heat from the Peltier stack except the sensors for the experimental or intraoperative use, and the other was not treated to minimize the size of probe for the long-term use by implantation into the subdural space. When the thermal CBF was compared to hydrogen CBF in each of 3 cats, a linear relationship was obtained in each and the values showing gradient and constant of the regression line were similar in each cat. Moreover, a good linear relationship was also observed when all measurements in 3 cats were included. These results suggested that there is no difference between each animal in the relationship of thermal and hydrogen CBF when the same probe is employed. In addition, the probe can be characterized with two values, and these are gradient and constant of the linear relationship. The fact that the blood flow is proportional to the heat conductivity indicates that the heat conductivity of some material is equivalent to some CBF value in the brain tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Convexity meningioma associated with Werner's syndrome--histopathological findings with electron microscopical and immunohistochemical findings].

Werner's syndrome is rare and autosomal recessive condition with multiple progeroid features. There is an increased incidence of neoplasm such as meningioma or sarcoma in association with this syndrome. However, the pathogenesis of this subject is still controversial. To date, only two cases have been reported, dealing with surgical operation. Our present case of a 39-year-old woman who had a meningioma associated with Werner's syndrome is the third of such cases. In this rare case we did histopathological examinations including electron microscopic and immunohistochemical studies, which showed intense proliferation of the connective tissue in the tumor tissue. The present morphological study may imply a close relationship between proliferation of collagen fibers in the meningioma and the aberration of connective tissue metabolism in context of theory of the pathogenesis of Werner's syndrome.

Adult↗
PubMed1987

[Cerebral blood flow in subarachnoid hemorrhage: analysis in patients with poor outcomes].

Cerebral blood flow (CBF) of 6 patients with poor outcome after subarachnoid hemorrhage is analyzed. Neurological grades of these patients were grade III in 2 and grade IV in 4 patients, and subarachnoid hemorrhage on CT was diffuse and thick in all patients. Cerebral blood flow was continuously measured for 7 to 19 days by the thermal diffusion flow probe with a peltier stack which was left on the cerebral cortex at the surgery for ruptured aneurysm. Moreover, CBF studies by cold xenon CT and 133Xe inhalation methods were also performed in discussing cases. At the same time intracranial pressure was monitored. Cerebral angiography was carried out in all except for 2 patients who died due to severe cerebral vasospasm. The initial CBF value of all patients was 20 to 40 ml/100 g/min (mean value: 27 ml/100 g/min), and these were significantly low compared to normal value (50 ml/100 g/min). Moreover, these CBF was substantially decreased several days after surgery in all patients, and it was marked in 3 patients who died. From these results it was clear that the degree of vasospasm is important to determine the prognosis. One of 3 patients who died had ruptured left posterior cerebral artery aneurysm with occlusion of bilateral internal carotid arteries. In this case further decrease of CBF due to vasospasm was observed in addition to low initial CBF resulting diffuse low flow in both hemispheres although extracranial to intracranial bypass was performed. On the other hand, it was also shown that the intracranial pressure was an important factor to influence the outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

[Regional cerebral blood flow images of single photon emission computed tomography by N-isopropyl-p-[I-123] iodoamphetamine in patients with brain tumor].

Regional cerebral blood flow (r-CBF) was studied by single photon emission computed tomography (SPECT) using N-isopropyl-p-[I-123] iodoamphetamine (IMP) in order to evaluate CBF in patients with brain tumor. Total 27 studies were carried out in 20 patient, including 8 patients with meningioma, 3 with glioblastoma multiforme, 2 with oligoastrocytoma, and 7 with other intracranial tumors. All CBF images by IMP-SPECT were obtained by using a rotating gamma camera with dual heads. In the serial scans, each scan was started at 20 minutes, 2 hours and 6 hours after intravenous injection of I-123 IMP (3 mCi). The all IMP-SPECT images were compared with cerebral angiogram, X-ray CT (plain and/or enhancement), and images of Kr-81 m SPECT and Tc-99 m SPECT. In 5 patients (4 patients with meningioma and 1 with glioblastoma multiforme) this comparative study was performed before and after surgery to evaluate the r-CBF changes surrounding tumor. The abnormal lesion on X-ray-CT was identified as hot area on CBF image by IMP-SPECT in two cases with meningioma, and in 14 cases the lesion showed cold area. Totally 80% of cases showed abnormal findings on CBF images by IMP-SPECT. The cases which showed no abnormal findings on IMP-SPECT images included 1 case with meningioma which located in frontal base, 2 with small intracranial brain tumor which was smaller than 2 cm in diameter, and 1 with pituitary adenoma. On the IMP-SPECT images scanned 2 hours after injection, hot area, which was identified in two cases with meningioma on the images 20 minutes after injection, was changed into cold area.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphetamines↗
PubMed1987

[Measurement of cerebral blood flow by thermal diffusion using a flow probe with a Peltier stack].

In order to evaluate the blood flow by means of thermal diffusion, relationship between blood flow and parameters induced by thermal diffusion was investigated. Flow probe employed for measurement by thermal diffusion incorporated a Peltier stack which contained a small semiconductor and two L-shaped gold plates. These two plates were attached to both sides of the semiconductor by one side of each gold plate and the other side was surfaced with a tissue to be measured. Temperature gradient is created with current applied to the Peltier stack between two plates, one cooled and the other heated, and it is affected only by tissue blood flow. Two kinds of parameters of thermal diffusion were subjected to compare to blood flow. One was temperature gradient when the constant current was applied to the Peltier stack. The other was a current required to maintain a definite temperature gradient which was determined before hand. From the theoretical principle in thermodynamics, the correlations between blood flow and each of thermal diffusion parameters were defined by the following equations: (Formula: see text) where F is blood flow, delta V is voltage converted from temperature gradient, and Ci and Cv are constants. Each of phi v and phi i indicates the characteristics of each probe. Experimental study was carried out to confirm the above relationship using cortex of experimental animals. Under the general anesthesia, a cat was placed in prone position. After the craniotomy, dura mater was opened and a small flow probe, 10 mm in diameter, 5 mm in height and 5 g in weight, was placed on the cortex and blood flow was continuously evaluated by two parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Intraoperative liquid embolization of an arteriovenous malformation in the basal ganglia and thalamic region].

Total three patients with arteriovenous malformation (AVM) in basal ganglia or thalamic region were treated by intraoperative liquid embolizations. These procedures were decided because of repeated hemorrhagic episodes. In the case with AVM in the head of the caudate nucleus which was fed by several anterior perforating arteries originated from anterior cerebral artery (A1 portion) and middle cerebral artery (M1 portion), frontotemporal craniotomy was performed. After the microsurgical dissection of these feeders, one of the feeders lenticulostriate artery, was cannulated with a small-caliber polyethylene catheter, 0.6 mm in outer diameter and 0.3 mm in inner diameter. A small amount of isobutyl 2-cyanoacrylate (IBCA) was injected through the catheter. Same procedure was carried out one month later. Postoperative angiograms revealed about 90% loss of AVM. In two cases with AVM which involved almost entire thalamus, subtemporal craniotomy was done. Feeding vessels which originated from posterior communicating artery and posterior cerebral artery (PCA) were carefully dissected under the operative microscope and one of them was prepared for cannulation with small catheter. When the small amount of IBCA was injected, proximal PCA and internal carotid artery were temporarily occluded. In both cases intraoperative embolization was carried out twice. Postoperative angiograms revealed that the size of AVM was decreased to 20% in one and 40% in the other. Although temporary postoperative deterioration of neurological deficits such as hemiparesis and visual disturbance was slightly noted in all cases, no hemorrhagic episode was experienced for 6 months, 1.5 and 2 years in each after embolization.

Adult↗
PubMed1986

The staining of type V collagen obtained from FBJ virus-induced osteosarcoma with concanavalin A.

Type V collagen from FBJ virus-induced osteosarcoma of mice has a high content of saccharide as has been noted for type V collagens from different sources. In the present study, this collagen was found to contain significant amounts of mannose and hexosamine. Three alpha chains of this collagen were electrophoretically separated and cleaved by cyanogen bromide. The cyanogen bromide peptides, following their separation by SDS-polyacrylamide gel electrophoresis, were transferred onto nitrocellulose paper and stained with concanavalin A. Several bands derived only from alpha 3(V) stained positively, but this was inhibited by the presence of alpha-methylmannoside. Thus, at least one of these three chains appears to have an asparagine-linked oligosaccharide.

Animals↗
PubMed1986

Study of the posterior circulation in moyamoya disease. Part 2: Visual disturbances and surgical treatment.

The involvement of the posterior circulation in moyamoya disease was studied in 178 patients. Forty-three had several types of disturbance such as visual field defect, decreased visual acuity, episodes of blindness, and scintillating scotomata. Most of these symptoms were attributed to occlusive lesions in the posterior circulation. Visual disturbances were seen more often in patients with a juvenile onset than in cases of adult onset. Superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis and encephalomyosynangiosis (EMS) improved the cerebral perfusion both in the anterior and posterior circulation by redistribution of blood. In most cases, the visual symptoms subsided or were stabilized after STA-MCA anastomosis and EMS. These surgical procedures did not, however, lead to direct revascularization in cases of ischemia in the visual cortex. In five patients with impending blindness, transplantation of the omentum to the occipital lobe led to improved vision.

Adolescent↗
PubMed1986

[Differing progress patterns in cancer of the uterine cervix and variant effects of adjuvant chemotherapy based on histological type].

Clinical features of 644 surgically treated cases of cancer of the uterine cervix were analyzed according to their histological type. Large cell non-keratinizing carcinomas (L) showed node metastasis proportional to the grade of invasion in the cervix, and the lowest recurrence rate. Small cell non-keratinizing carcinomas (S) tended to have widely spread metastasis from an early stage of the primary lesion. Lateral recurrence from metastatic foci was common in this type. Keratinizing carcinomas (K) were localized in the cervix until the primary tumor became enlarged to a certain size. Central recurrence from invasive foci in the surrounding tissue or organ occurred more often than lateral recurrence in this type. Metastasis pattern of pure adenocarcinomas (A) was similar to that of S, but recurrence was delayed. Adenosquamous carcinomas (AS) showed a similar metastasis pattern to that of K, but recurrence was rapid and the ratio high. Prophylactic maintenance chemotherapy with Tegafur (800 mg/day) or Carboquone (0.5 mg/day) was performed in 187 cases for a period of 2 years after surgery. The effect of maintenance chemotherapy depended on the histological type. A marked effect was obtained in the groups of S and A, in which no recurrence has appeared so far. The recurrence rate of L dropped to 1/5 that of the control. However, unsatisfactory results were shown in the groups of K and AS including the keratinizing cell component. It is of significance that maintenance chemotherapy showed the highest effectiveness in S and A on which conventional adjuvant therapy, i.e. postoperative radiotherapy, has had the least effect. This has led us to consider that a proper selection of adjuvant therapies would contribute toward improving the postoperative prognosis of patients with cancer of the uterine cervix.

Adenocarcinoma↗
PubMed1986

Controlled double-blind study of the therapeutic effect of pirenzepine dihydrochloride in duodenal ulcer. Phase III study.

A controlled double-blind study was performed in 17 institutes using gefarnate as a control drug in order to investigate the therapeutic effect and safety of pirenzepine dihydrochloride (LS 519) in duodenal ulcer. A total of 233 subjects were studied, 110 in the pirenzepine group (LS group) and 123 in the gefarnate group (GF group). Final improvement rate of ulcer lesions (8 weeks) of LS group showed the highly significant superiority over the GF group. Cumulative healing rates based on endoscopic findings of 17.9, 49.4, 67.0, 84.2 and 91.2% were found for the LS group at the 2nd, 4th, 6th, 8th, 10th and 12th weeks, respectively; the respective values for the GF group being 14.7, 33.0, 51.5, 66.7, 70.5 and 72.4%. Thus, the LS group showed a significantly superior acceleration of healing to that of the GF group on all occasions but the 2nd week. The improvement rate of subjective symptoms for moderately and markedly improved cases together totalled 98.9% for the LS group and 81.2% for the GF group, indicating the significant superiority of the former. These results proved the excellent therapeutic effect of pirenzepine. No significant difference in safety was found between the two drug groups. Gastric analysis was carried out before the start of drug administration and of its termination. In the healed subjects treated with pirenzepine there were a significant decrease in the secretion volume and acid output, and also a tendency to decrease in the acidity in basal secretion; and further a tendency to decrease in the acidity in maximally stimulated secretion.

Benzodiazepinones↗