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Biomedical subjects

A Tamura

Publications and source records attributed to A Tamura.

At least 271 records · Page 15Linked to original sources
PubMed1995

[Sphingolipid changes in rat cerebral cortex during focal ischemia--how does ceramide accumulate in an ischemic condition?].

Levels of ceramide, sphingomyelin, cerebroside and gangliosides were determined in rat cerebral cortex during focal ischemia produced by middle cerebral artery occlusion. Ceramide began to increase at 6 hours of ischemia and increased to 4.5 folds at 96 hours. Amino-linked fatty acids in increased ceramide were composed solely of non-hydroxy fatty acids, and stearic acid was the most prominent. Sphingomyelin, whose amino-linked fatty acids were mostly stearic acid, decreased in a time-dependent manner and became about a half of controls at 96 hours. Hydroxy fatty acid linked cerebroside decreased at and after 6 hours of ischemia, whereas significant decrease of non-hydroxy fatty acid linked cerebroside occurred only at 96 hours of ischemia. There were no measurable changes in the levels of gangliosides. The results suggested that ceramide was produced in the cerebral cortex by the breakdown of sphingomyelin during ischemia.

Animals↗
PubMed1995

[A case of remission of recurrent carcinosarcoma of the uterus with massive ascites by carboplatin].

A case of remission of recurrent carcinosarcoma of the uterus with massive ascites by chemotherapy using carboplatin (CBDCA) is reported. A 75-year-old female was diagnosed with cancer of the uterine body. She underwent abdominal total hysterectomy with bilateral salpingo-oophorectomy, which revealed carcinosarcoma of the uterus penetrating the myometrium and reaching the serosa of the uterus. Eight weeks after, she developed abdominal distension, obstruction of bilateral ureters and bleeding tumor measuring 5 cm in diameter at the vaginal cuff ending. Acute retention of bloody ascites of more than 2500 ml was demonstrated. Abdominal centesis, aspiration of ascites and intraperitoneal administration of 600 mg of CBDCA were performed. Two weeks after single use of CBDCA, the ascites completely disappeared and there was recovery from anuria. The remission has lasted more than 4 months, which has suggested the efficacy of CBDCA for uterine carcinosarcoma.

Aged↗
PubMed1995

Primary pulmonary lymphoma: relationship between clinical features and pathologic findings in 24 cases. The Japan National Chest Hospital Study Group for Lung Cancer.

To elucidate the relationship between the clinical features and pathologic findings of primary pulmonary lymphoma, we reviewed 24 patients with this disease. The pulmonary lymphomas were divided into four groups: (1) B-cell lymphoma composed of small to medium-sized lymphoid cells (19 cases); (2) B-cell lymphoma composed of large lymphoid cells (three cases); (3) T-cell lymphoma (one case); (4) malignant lymphoma of lymphomatoid granulomatosis (LYG) type (one case). Radiographs of the first group revealed a predominance of infiltration associated with ill-defined tumor margins upon gross pathology, corresponding histologically to lymphangitic spread. Air bronchogram and pleural tail or abutment were additional radiographic features. Characteristics of the second group were a nodule or mass evident on radiographs and well-circumscribed tumor margins upon gross pathology. Lack of air bronchogram was an another radiographic feature in this group. Seventeen patients in these two groups underwent complete resection of the tumors and survived without recurrence, whereas four received chemotherapy after biopsy and survived with disease. These results indicate that primary pulmonary B-cell lymphoma is a low-grade malignancy and that complete resection is the only therapy which leads to cure. In a single patient with T-cell lymphoma, the radiographic and pathologic features of the tumor were indistinguishable from those in the first group, but the patient had an unfavorable prognosis. We consider that, from a prognostic viewpoint, it is important to determine the T- or B-immunophenotype of the tumor cells for diagnosis of primary pulmonary lymphoma. The only patient in this series with pulmonary lymphoma of LYG type showed distinctive clinicopathologic findings. We consider that this uncommon disease should be separated from other types of primary pulmonary lymphoma.

Adolescent↗
PubMed1995

[Japan coma scale in the prediction of outcome after early surgery for aneurysmal subarachnoid hemorrhage].

The value of the 10-grade Japan Coma Scale (JCS) as a means of evaluating patients undergoing early aneurysm surgery was assessed in terms of its relationship to surgical outcome. The 13-grade Glasgow Coma Scale (GCS) was also assessed, and comparisons were made between the two. A series of 765 patients who underwent aneurysm surgery within 7 days after hemorrhage were evaluated both by JCS and GCS immediately prior to surgery, and outcome was assessed by the Glasgow Outcome Scale (GOS) 6 months postoperatively. Both the JCS and GCS scores were significantly correlated with surgical outcome (JCS vs GOS: rs = 0.586, GCS vs GOS: rs = 0.615, p < 0.001). There was no significant difference between the correlation coefficients for outcome of the JCS and GCS. In general, the better the JCS or GCS score was, the better the surgical outcome was, however, outcome among those with a JCS score of 3 was poorer than among those with a score of 10, 20, or 30. The results of this study indicate that both JCS and GCS are useful in predicting surgical outcome, but the GCS may be better than the JCS because of the problem with the score of 3 in the latter.

Acute Disease↗
PubMed1995

Reperfusion hastens appearance and extent of distribution of type I collagen in infarct zone: immunohistochemical study in rat experimental infarction.

BACKGROUND: The effects of reperfusion on time-dependent alteration of type I collagen have not been examined. OBJECTIVES: We compared the sequential changes in the appearance and distribution of type I collagen in reperfused infarct rat hearts to those in non-reperfused hearts. METHODS: Using an experimental rat model of infarction, we performed immunohistochemical staining with a polyclonal antibody to type I collagen by the avidin-biotin-peroxidase method. Reperfusion was established after 2-h coronary ligation that produced complete necrosis of myocytes. RESULTS: In reperfused hearts, type I collagen appeared in the peripheral zone of the infarct at day 2, which was 1 day earlier than in non-reperfused hearts. The extent of distribution of type I collagen in reperfused hearts was comparable to that observed approximately 1 day later in non-reperfused hearts. CONCLUSION: Reperfusion can accelerate collagen matrix formation compared with that in non-reperfused hearts after acute myocardial infarction.

Animals↗
PubMed1994

Effect of an intersubunit disulfide bond on the stability of Streptomyces subtilisin inhibitor.

The effect of an engineered disulfide bond between two identical subunits of a dimeric protein, Streptomyces subtilisin inhibitor, on the stability of the protein was studied by differential scanning calorimetry. The introduction of the linkage caused a large stabilization without changing the cooperativity of unfolding, with the denaturation temperature of a 2 mg/mL solution being increased by 14.3 degrees C to 95.0 degrees C at pH 9.5 and by 16.4 degrees C to 63.0 degrees C at pH 3.0. The stabilization was caused by a loss of denaturational entropy, i.e., -40 and -98 cal K-1 mol-1 at pH 3.0 and 9.5, respectively, which more than compensated for the loss in the denaturational enthalpy.

Bacterial Proteins↗
PubMed1994

[Hyaline cartilage delineation of the knee joint using magnetization transfer contrast images].

Using a magnetization transfer contrast method (MTC), we evaluated its clinical feasibility for demonstration of hyaline cartilage of the human knee in five normal subjects. MTC images, obtained from a gradient echo sequence with an off resonance pulse, were compared with those without off resonance pulse. Signal to noise ratio (SNR) and magnetization transfer rate (MTR) were analyzed with respect to hyaline cartilage, muscle, fat, joint fluid and background noise. Also, contrast to noise ratios (CNRs) of cartilage and fluid were compared. MTRs were significantly different between cartilage-muscle group and fat-fluid group. The CNRs of cartilage and fluid were increased on MTC images, showing good contrast separation between hyaline cartilage and joint fluid.

Adolescent↗
PubMed1994

Effect of YM737, a new glutathione analogue, on ischemic brain edema.

We investigated the effect of YM737, a monoester of glutathione (GSH), on brain edema and GSH content after occlusion of a middle cerebral artery (MCA) in the rat. The drug possesses stronger radical scavenging activity than GSH itself, and is more effectively transported into cells. Hemispheric water, sodium, and potassium contents were determined at 2.5 and 24 hours after MCA occlusion. The animals received either YM737 or GSH immediately after occlusion. Cerebral GSH content was measured by HPLC after 2.5 hours of ischemia. The increases in water and sodium contents at 2.5 and 24 hours after MCA occlusion were significantly suppressed by YM737. GSH content decreased by 53% in the caudate, and by 22% in the cortex after ischemia. YM737 significantly ameliorated the GSH decrease in the caudate, while administration of GSH showed little effects on the ischemia-induced changes in water, sodium, and GSH contents. The result suggests the role of free radicals in the pathogenesis of ischemic brain edema.

Animals↗
PubMed1994

CT and MRI features of intracranial germ cell tumors.

The computed tomographic (CT) and magnetic resonance imaging (MRI) features of 73 histologically proven primary intracranial germ cell tumors were analysed. CT images were available for all 73 patients, and 22 of them were also examined by MRI. The tumors were classified as germinoma, mature teratoma, immature or malignant teratoma, yolk sac tumor, choriocarcinoma, embryonal carcinoma and mixed type. Germinoma was revealed as a high- or slightly high-density area on plain CT scan, and was enhanced homogeneously. MRI revealed iso- or slightly low signal intensity on T1-weighted images, and iso- or high intensity on T2-weighted images. Mature teratoma, which had a clear margin on neuroradiological images, was characterized by mixed density on CT scans, often showing large cysts and area of calcification. Immature or malignant teratoma had a similar pattern to that of mature teratoma, but the cystic components and area of calcification tended to be less and smaller respectively. The tumor margin was obscure in malignant teratoma, and perifocal edema was observed in some cases. The shape of yolk sac tumors was irregular. Plain CT scan revealed an iso- or low-density mass with good heterogeneous enhancement. Perifocal edema was observed in some cases. In mixed germ cell tumors, MRI imaging was useful for detecting teratomatous components, particularly fatty components. Although definite histological diagnosis cannot be achieved by CT and/or MRI alone, detailed analysis of neuroradiological images are useful for predicting the histological diagnosis.

Brain Neoplasms↗
PubMed1994

Key of induced tolerance to ischaemia in gerbil hippocampal CA1 is not at transcriptional level of hsp70 gene: in situ hybridization of hsp70 mRNA.

Hippocampal neurons, when pretreated with sublethal ischaemia, acquired tolerance to future treatments of normally lethal ischaemia. The level of transcription of the stress protein hsp70 was studied by in situ hybridization in control, ischaemic and tolerance-induced-ischaemic hippocampal neurons. Mongolian gerbils were subjected to single forebrain ischaemia for 2 min (2-min ischaemia group: sublethal) or 5 min (5-min ischaemia group: lethal). Other animals, were exposed to sublethal ischaemia for 2 min and were subjected subsequently to ischaemia for 5 min, 2 days later. Animals were sacrificed at 6, 12, 24 and 48 h following ischaemia and in situ hybridization was performed with thin cross sections including the hippocampus. Hybridization of the hsp70 probe in the control group (no ischaemia) was barely visible in the brain. In the 2-min ischaemia group, intense hybridization was seen in the CA1 sector from 6 through 24 h of recirculation but hybridization almost disappeared at 48 h of recirculation. In the 5-min and the double ischaemic groups, the intense induction in the CA1 sector occurred during the period from 6 through 48 h of recirculation. Our present study by in situ hybridization reveals high levels of transcription of hsp70 message following 5-min of ischaemia, however no protein was detectable based on our previous experiments employing immunocytochemistry. In tolerance-induced hippocampal neurons, both hsp70 message and protein are present. These results suggest that tolerance-induced neurons are modified such that the hsp70 gene is both transcribed and translated. These changes most likely give rise to the tolerance observed in the double ischaemia group.

Animals↗
PubMed1994

Subgaleal angiomyolipoma.

A case of angiomyolipoma found in the subgaleal lesion is reported. Lipoma appearing between the galea and periosteum of the frontal bone is called subgaleal or subfascial lipoma and usually consists histopathologically of mature fat cells. We experienced a case of so-called subgaleal lipoma; however, the distinctive histologic features of our case were the proliferation of non-striated muscle fibers and small vessels scattered throughout the mature fat cells, which were compatible with angiomyolipoma. Extrarenal angiomyolipoma, especially cutaneous angiomyolipoma, are very rarely mentioned in the literature. Our case is the second reported patient with angiomyolipoma in the subgaleal location.

Angiomyolipoma↗
PubMed1994

Disturbance of retention of memory after focal cerebral ischemia in rats.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the behavioral changes, in particular retention of memory, after focal cerebral ischemia in rats. METHODS: Ischemia was produced by permanent occlusion of the left middle cerebral artery (MCA). For quantitative behavioral analysis, one-trial passive avoidance response and active avoidance response with the discrete lever-press avoidance procedure were observed. One group of animals was trained once to learn the passive avoidance task 1 day before surgery. The response latency was examined 4 and 14 days after surgery. The second group was trained to learn the active avoidance task for 2 weeks before surgery. The avoidance rate was examined 3 and 14 days after surgery. RESULTS: The MCA-occluded group showed significant failure of memory retention in both of these tasks (P < .01). The nonoperated group and sham-operated group showed no definite memory failure. CONCLUSIONS: Retention of memory in the passive avoidance response and the active avoidance response was disturbed after left MCA occlusion in the rat. These results strongly suggest that this model can be used to assess memory disturbance after focal cerebral ischemia.

Animals↗
PubMed1994

Structure, function and brain localization of neurotransmitter transporters.

We studied four different cDNAs encoding GABA transporters and three different cDNAs encoding glycine transporters in mouse and rat brains. A genomic clone of two of the glycine transporters (GLYT1a and GLYT1b) revealed that they derive from differential splicing of a single gene. The third glycine transporter (GLYT2) is encoded by a separate gene. Antibodies were raised against seven of these neurotransmitter transporters and their cytochemical localization in the mouse brain was studied. In general, we observed a deviation from the classical separation of neuronal and glial transporters. It seems that each of the neurotransmitter transporters is present in specific places in the brain and is expressed in a different way in very specific areas. For example, the GABA transporter GAT4, which also transports beta-alanine, was localized to neurons. However, GAT1, which is specific for GABA, was localized not only to neurons but also to glial cells. The recently discovered glycine transporter GLYT2 was of particular interest because of its deviation from the general structure by a very extended N terminus containing multiple potential phosphorylation sites. Western analysis and immunocytochemistry in frozen sections of mouse brain demonstrated a clear caudal-rostral gradient of GLYT2 distribution, with massive accumulation in the spinal cord and brainstem and less in the cerebellum. Its distribution is typically neuronal and it is present in processes with varicosities. A correlation as observed between the pattern we obtained and that observed previously from strychnine binding studies. The results indicate that GLYT2 is involved in the termination of glycine neurotransmission at the classical inhibitory system in the hindbrain. The availability of four different GABA transporters made it possible to look for specific binding sites upon the neurotransmitter transporters. An extensive program of site-directed mutagenesis led us to identify a potential neurotransmitter binding site on the GABA transporters.

Amino Acid Sequence↗
PubMed1994

An ultrastructural study of vertical transmission of Rickettsia tsutsugamushi during oogenesis and spermatogenesis in Leptotrombidium pallidum.

Rickettsia tsutsugamushi in Leptotromibidium pallidum was observed by electron microscopy and rickettsiae were found in the various tissues and organs of both larvae and adults. Budding of rickettsiae, a manner of release from the host cells, was observed only in the rudiments of the reproductive organs in larvae. Oogonia and maturing oocytes in adult females and eggs after oviposition contained the microorganisms. In adult males, rickettsiae were also found in the spermatogonia, spermatocytes, and spermatids in the early stage of spermatogenesis, but were eliminated from these cells during maturation. Only the maturing spermatids, but not the eliminated rickettsiae, migrated to another rickettsia-free area of the testis, resulting in the separation of spermatids from rickettsiae and in the production of rickettsia-free spermatophores. Based on these observations, the mechanism of vertical transmission of the rickettsiae to the progeny occurs only in the female parents. Most rickettsiae in the somatic cells of larvae and adults were coccoid, but some rickettsiae in the ovary and the testis of adult mites showed bacillary forms and were enveloped by a membrane of unknown origin.

Animals↗
PubMed1994

A new approach for the detection of type III hyperlipoproteinemia by RLP-cholesterol assay.

Type III is a remnant hyperlipoproteinemia identified by the presence of beta-VLDL (remnant lipoprotein) as well as a genetic variant of apo E (apo E2/2). The RLP isolated from the serum of Type III patients by a new method we have developed, the RLPcholesterol assay, was identified as chylomicron and VLDL remnant. In addition, the RLP-C levels of the Type III patients were significantly higher than other hyperlipidemic patients with similar serum TG levels, while the ratio of TC/TG in RLP-C of both groups was not significantly different. The RLP-cholesterol assay appears to be useful for the screening and monitoring of Type III hyperlipoproteinemia when used in conjunction with the assays of serum TG level and genetic apo E isoform analysis.

Adult↗