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Biomedical subjects

M Nishida

Publications and source records attributed to M Nishida.

At least 433 records · Page 24Linked to original sources
PubMed1989

[Primary interhemispheric subdural abscess: report of a case].

We reported a rare case of primary interhemispheric subdural abscess. Twenty-three cases of this pathological condition have been reviewed. In those reports, however, findings of magnetic resonance imaging (MRI) were not referred to. In this report, MRI findings in this pathological condition, in addition to X-ray computed tomography (CT), is mentioned. A 22-year-old man, who had suffered from headache and vomiting for 2 weeks, suddenly became drowsy and left-hemiparetic. The X-ray CT scan on admission showed a well-circumscribed low density area in contact with the falx in the right parieto-occipital region. This lesion had so called "ring enhancement". MRI in the sagittal view revealed that, along the falx, the long T1 and T2 areas extended from the right cerebellar tentorium to the right frontal region. The operation demonstrated the capsular formation of the abscess. After pus aspiration, continuous drainage was performed from the cavity of the abscess. The patient fully recovered postoperatively. In the diagnosis of interhemispheric subdural abscess, it is said that conventional X-ray CT sufficiently reveals the quality of the lesion, the precise site, and the anatomical relation to the surrounding edema. In our case, MRI was able to confirm the diagnosis made by the X-ray CT. Furthermore, MRI was thought to be superior to the X-ray CT in the evaluation of the extension of the abscess and in the delineation of the surrounding edema. Combined use of X-ray CT and MRI in cases of interhemispheric abscess was considered to make the diagnosis more precise in both qualitative and quantitative aspects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Cockayne syndrome: siblings with different ultraviolet sensitivity and early onset of manifestations].

Siblings of Cockayne syndrome were reported. Both of them had characteristic manifestation of Cockayne syndrome. A 4-year-old boy had been noted to have irritability and nystagmus from the 6th day of his life, and his elder sister, 8 years old, had been diagnosed as cerebral palsy at the age of 6 months. The elder sister lacked photosensitivity clinically. The proband was more severely affected than his elder sister on both cerebral CT-scan and electrophysiological studies. Reduced colony forming ability after ultraviolet exposure is currently considered to be the primary abnormality in Cockayne syndrome. The cells originating from the boy had moderately reduced colony forming ability after ultraviolet irradiation, whereas the cells from his elder sister showed mildly reduced colony forming ability. There may be some relationship between the severity of the symptoms and the colony forming ability. There is a broad spectrum of clinical manifestations in Cockayne syndrome. Further investigations are necessary to clarify the relationship between the cytological abnormalities of Cockayne syndrome and its neurological manifestations.

Child↗
PubMed1989

[Comparison of two dimensional and three dimensional CBF measurements in stroke patients].

The purpose of this study is to compare the detectability of the reduction in cerebral blood flow (CBF) using the two versus the three dimensional technique of CBF measurement. Both techniques were simultaneously carried out 85 times on 52 stroke patients. In the two dimensional technique, CBF was measured by the Xe-133 inhalation method and the value was calculated by the initial slope index. In the three dimensional technique, CBF was measured by single photon emission CT with Xe-133 inhalation method. CBF reduction was studied in the middle cerebral artery (MCA) territory on a CBF map in both techniques. Additionally, mean CBF was also calculated for the same territory. On the CBF map, the CBF reduction was shown in 25 of 85 measurements with the two dimensional technique and in 41 of 85 with the three dimensional technique. In comparing the imagings of both techniques, the CBF reduction seen extensively along the cortical surface and in the entire MCA territory with the three dimensional technique was also detected with the two dimensional technique. However, focal CBF reduction observed at the cortical surface and in the deep cerebral tissue with the three dimensional technique was not detected with the two dimensional technique. In order to evaluate both techniques quantitatively, we calculated the ratio of the mean CBF difference between the MCA territories of both hemispheres to mean CBF in the non-affected MCA territory. This ratio represented the asymmetry index. Firstly, the relationship between asymmetry index and the imaging of CBF reduction on the CBF map was studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1989

[Intraoperative monitoring of cerebral function and carotid hemodynamics during carotid endarterectomy].

The authors investigated the hemodynamics and monitored the cerebral function to perform the carotid endarterectomy (CEA) safely. The hemodynamics were investigated by measurements of carotid arterial blood flow by an electromagnetic flow meter before and after CEA. And a doppler flow meter applied directly to the carotid arteries to analyze the flow parameters such as peak frequencies (PF), mean frequencies (MF), mode frequencies (Mo F) and % window. We used routinely our specially designed shunt system during surgery, by which stump pressure of the ICA could be measured easily. The cerebral function was evaluated by the amplitude of N20-P25 component of somatosensory evoked potential (SEP). Flow parameters of doppler sounds demonstrated significant changes such as inversion of MF and Mo F, decrease in % window at the poststenotic ICA in the severe stenosis group. By these doppler sounds the extension of stenotic lesion could be detected clearly. The ICA flow showed evidently low values in patients with more than 80% stenosis, which was improved by CEA. With our specially designed T-tube shunt system, stump pressure, side pressure and direct pressure of the ICA could be monitored easily. The mean stump pressure was 52 mmHg and systemic arterial blood pressure was 99 mmHg on the average. SEP revealed evident changes during temporary occlusion in 10 out of 41 patients, which improved following the reflow with the shunt system. Mean stump pressure in the 11 patients was 33 mmHg, and that in the remaining patients were 59 mmHg on the average.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Enhancement by streptozotocin of O2- radical generation by the xanthine oxidase system of pancreatic beta-cells.

Spin-trapping techniques and electron spin resonance (ESR) spectroscopy were used to study the relationship between the effect of streptozotocin (STZ) on pancreatic beta-cells and free radical formation by these cells. Results showed that STZ enhanced generation of the DMPO-OH radical adduct, which is a degradation product of the superoxide anion (O2-) in the presence of cellular components, in a hypoxanthine-xanthine oxidase (XOD) system with a homogenate of beta-cells. This enhancing effect was also observed in a system without cellular components; STZ increased the signal height due to the O2- radical in a concentration-dependent manner and caused a maximum of 150% enhancement at a concentration of 1.5 mM. Thus, STZ seemed to enhance the generation of the O2- radical in the XOD system, probably by some mechanism of its interaction with XOD. Pancreatic beta-cells exhibited a high XOD activity and a very low superoxide dismutase activity. Therefore, the present result supports the possibility that the cytotoxic effect of STZ is closely related to free radical generation in pancreatic beta-cells.

Animals↗
PubMed1988

A sigmoidal relationship between liver stearoyl CoA desaturase activity and serum hormone concentrations caused by streptozocin and its antagonists.

Stearoyl CoA desaturase activity in liver microsomes, and insulin, thyroxine, and triiodothyronine levels in serum were measured after administration of streptozocin (STZ) and its antagonists to rats. The effect of STZ, which caused hyperglycemia and inhibited the desaturase activity, was antagonized by 2-desoxyglucose and 3-O-methyl-glucose; 1-O-methyl-3-desoxyglucose and 1-O-methyl-3-O-methylglucose were without any effect. The enzyme activity plotted against insulin levels showed a broad sigmoidal curve, whereas the activities versus thyroid hormone levels showed steeper sigmoidal curves.

Animals↗
PubMed1988

Arachidonate metabolism in myocardial ischemia and reperfusion.

Circulatory blood corpuscles have enzymes catalyzing arachidonic acid. Platelets have cyclo-oxygenase system which produce highly vasoconstrictive and thrombogenic thromboxane A2 (TXA2). Neutrophils have another type of arachidonate metabolism system, lipoxygenase enzymes, which produce hydroxyeicosatetraenoic acids (HETE) and leukotrienes (LT), mediating inflammatory reactions. These arachidonate metabolites were found to play important roles in the evolution of myocardial ischemia. Thromboxane B2 (TXB2) a stable metabolite of TXA2, was elevated in peripheral blood of patients with angina pectoris. This elevation of TXB2 was supposed to be derived from platelet activation in coronary circulation due to altered production of TXA2 and prostacyclin (PGI2). Augmentation of TXA2 was also observed in patients with acute myocardial infarction. TXA2 synthetase inhibitors decreased plasma levels of TXB2 in these patients accompanied by attenuation of infarct size. Neutrophils were found to accumulate in ischemic myocardium and were augmented at reperfusion phase especially at interface between infarcted and risk zone. These infiltrated neutrophils may also provide deleterious effects on myocardial cells by producing lipoxygenase metabolites. In fact, a chemotactic and vasoconstrictive lipoxygenase product, 12-HETE, was produced selectively in ischemic myocardial tissue of an occlusion-reperfusion model. During evolution of myocardial cell damage, platelets and neutrophils, accumulated in ischemic tissue, may contribute to the exacerbation of microcirculatory disorders by producing vasoactive prostanoids, leading to expansion of myocardial necrosis. We should gain insights into these cellular interactions through arachidonate metabolism under normal and catastrophic conditions of coronary circulation.

Arachidonic Acids↗
PubMed1988

Chronic recurrent anterior luxation of the mandible. A review of 12 patients treated by the LeClerc procedure.

A follow-up study was performed on 12 patients surgically treated because of chronic recurrent anterior dislocation of the temporomandibular joint by the LeClerc procedure which was refined by Gosserez & Dautrey. In all of the 12 patients, there had been no recurrence of the dislocation since the operation (follow-up period: up to 5 years and 3 months). This procedure did not disturb normal functional movement of the joint, yet prevented excessive forward excursion of the condyle. The surgical technique is presented and the results of this operation are evaluated.

Adolescent↗
PubMed1988

Nature of monocyclic beta-lactam antibiotic Nocardicin A to beta-lactamases.

Nocardicin A is the antibiotic which was first found to possess a monocyclic beta-lactam ring. This antibiotic was inactivated by the cleavage of its beta-lactam ring. The direct spectrophotometric assay was applied to measure the rate of enzymatic hydrolysis of Nocardicin A. Nocardicin A was highly stable to both chromosomal and plasmid-mediated beta-lactamases. Of the nine beta-lactam antibiotics including cefoxitin and cefuroxime, Nocardicin A was the most stable to the beta-lactamases tested excluding those from Klebsiella oxytoca and Proteus vulgaris. The latter broad-spectrum beta-lactamases hydrolyzed Nocardicin A rather intensively. Extreme stability of Nocardicin A to beta-lactamases was suggested to be due to the combination of its low affinity to the enzymes and stabilization of its monocyclic beta-lactam ring. Nocardicin A was shown to have inducing ability toward beta-lactamases.

Anti-Bacterial Agents↗
PubMed1988

Degradation of host defenses against respiratory tract infection by Klebsiella pneumoniae in aged mice.

The host defense against respiratory tract infection with Klebsiella pneumoniae was much weaker in 60-week-old mice than in 4-week-old mice, but the resistance against systemic infection by intravenous and intraperitoneal challenge with K. pneumoniae in 60-week-old mice did not differ from that in 4-week-old mice. The number of alveolar macrophages at the resting stage in 60-week-old mice was the same as in 4-week-old mice, but the number of macrophages and polymorphonuclear leukocytes in the pulmonary cavity 4 h after challenge with formalinized K. pneumoniae in aerosol doubled in parallel with body weight. Phagocytosis and killing activities and superoxide anion production as measured by the Nitro Blue Tetrazolium reduction test of alveolar macrophages in 60-week-old mice were significantly weaker than in 4-week-old mice. The surfaces of the alveolar macrophages of the 60-week-old mice shrunk and a few adhered weekly to the glass plate, but the alveolar macrophages of the 4-week-old mice stretched to their full length and adhered firmly to the glass plate. These functions of alveolar macrophages clearly differed from those of peritoneal macrophages in 60-week-old mice, but those of the peritoneal phagocytes did not differ between 60-week-old and 4-week-old mice. The results suggest that the susceptibility to respiratory tract infection in 60-week-old mice is affected by a decline in the functions of alveolar macrophages rather than by the number of alveolar macrophages and exudated polymorphonuclear leukocytes in the lungs.

Aging↗
PubMed1988

An appropriate model for congenital hypothyroidism in the rat induced by neonatal treatment with propylthiouracil and surgical thyroidectomy: studies on learning ability and biochemical parameters.

Hypothyroidism was induced in rats by treatment with propylthiouracil through the mother's milk throughout the suckling period followed by surgical thyroidectomy without use of radioiodine. The growth of these animals was considerably retarded and their light-dark discriminative operant learning ability was also significantly decreased. Replacement therapy with thyroxine to maintain its normal serum concentration was effective for continuing normal growth and development of learning ability. Therefore, these hypothyroid rats are a useful model of congenital hypothyroidism. Biochemical studies showed that the inhibition of cerebral Na,K-ATPase and succinic dehydrogenase activities detected in early postnatal life in these hypothyroid rats was transient and that normal activities of these enzymes were later regained in adult rats. However, the activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase and the brain myelin remained low throughout life unless thyroxine was administered. Though a critical correlation between biochemical parameters and learning ability is still uncertain, these results suggest that the formation of myelin in the neonatal period is at least dependent on thyroid hormone and would play an important role in mental development.

Animals↗
PubMed1988

Role of the cephalosporinase gene in the resistance of the clinically isolated cephem-resistant Escherichia coli.

A small number of highly cephem-resistant strains was found in extensive susceptibility testing of clinical isolates of Escherichia coli to the new cephalosporin derivatives. The cephem-resistance of these clinical isolates appeared to be due to the increased cephalosporinase activities. To clarify the mechanism of the resistance, we cloned the cephalosporinase genes from two typical cephem-resistant clinical isolates as well as from an E. coli K-12 strain. The following two lines of evidence indicated that the cephem-resistance resulted from hyper production of the cephalosporinase due to the up-mutation of the regulatory sequence of the cephalosporinase gene. 1) Reciprocal exchange of the regulatory sequence including a short segment of N-terminal coding sequence and the rest of the coding sequence between the cephalosporinase genes from E. coli K-12 and the cephem-resistant clinical isolate showed that the higher cephalosporinase activity was accompanied by the regulatory sequence of the cephalosporinase gene from the clinical isolate. 2) The promoter activities of the cephalosporinase genes were determined by cloning the regulatory sequences into a promoter analysis vector. The promoter activities of the cephalosporinase genes from the clinical isolates were 23-33-fold higher than that of the cephalosporinase gene from E. coli K-12.

Cephalosporinase↗