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Biomedical subjects

K Oka

Publications and source records attributed to K Oka.

At least 433 records · Page 24Linked to original sources
PubMed1988

Tissue-type plasminogen activator in patients with intracranial meningiomas.

Three of 13 patients with intracranial meningiomas showed the pre- and postoperative elevation of tissue-type plasminogen activator (t-PA) related fibrinolytic activity in euglobulin fractions (EFA). During operation, two of these three patients showed a significant elevation of the level of fibrin(ogen) degradation products and oozing in the operating field. However, oozing was not observed in the third patient who had been given tranexamic acid preoperatively. Fibrin autography revealed that a broad lytic band of mol wt 50-60 kDa, probably free t-PA, appeared in the plasma obtained from two of the three patients after operation when EFA elevated significantly. In all patients studied, the t-PA antigen levels were normal preoperatively but increased both during and after operation, and correlated mainly with the intensities of a lytic band of mol wt 110 kDa, probably t-PA complexed with its major inhibitor (PAI-1). These results suggest that the excessive fibrinolysis can induce the local hemorrhagic diathesis during operation and may be related to t-PA function in plasma.

Adult↗
PubMed1988

Molecular cloning of cDNA and chromosomal assignment of the gene for human phenylethanolamine N-methyltransferase, the enzyme for epinephrine biosynthesis.

Phenylethanolamine N-methyltransferase (PNMT; EC 2.1.1.28) catalyzes the synthesis of epinephrine from norepinephrine, the last step of catecholamine biosynthesis. To isolate a cDNA clone for human PNMT, we first isolated a cDNA clone for bovine adrenal medulla PNMT using mixed oligodeoxyribonucleotide probes whose synthesis was based on the partial amino acid sequence of tryptic peptides from the bovine enzyme. By screening a bovine adrenal medulla cDNA library, a cDNA clone with an insert of about 200 base pairs (bp) was isolated. This clone consisted of 84 bp of carboxyl-terminal coding region, which contained amino acid sequences corresponding to two tryptic peptides, and about 100 bp of 3'-untranslated region. Using this cDNA fragment as the probe, we screened a human pheochromocytoma cDNA library and isolated a cDNA clone with an insert of about 1.0 kilobase pairs, which contained the complete coding region of the enzyme. Northern blot analysis of human pheochromocytoma poly(A)+ RNA using this cDNA insert as the probe showed a single RNA species of about 1,000 nucleotides, suggesting that this clone is a full-length cDNA. Determination of the nucleotide sequence revealed that human PNMT consists of 282-amino acid residues with a predicted molecular weight of 30,853, including initial methionine. The amino acid sequence of the human PNMT was highly homologous (88%) to that of the bovine enzyme. Chromosomal assignment of the gene for human PNMT was carried out using mouse-human somatic cell hybrids. The PNMT gene was assigned to chromosome 17.

Amino Acid Sequence↗
PubMed1988

Demonstration of intracytoplasmic immunoglobulin in non-T-acute lymphocytic leukemia cases of children with immunoelectron microscopic examination.

Leukemic cells from 25 cases of non-T-acute lymphocytic leukemia (ALL) in children were investigated for intracellular immunoglobulin by the use of immunoelectron microscopic study (immuno-EM). As a result, 12 cases were negative for both heavy and light chains of the immunoglobulin in the neoplastic cells. Of these, one case that was also negative for common ALL antigen (CALLA) was defined as null cell type. The remaining 11 cases were defined as common ALL type. Six cases were defined as pre-B-cell type because they were positive for cytoplasmic mu chain but negative for cytoplasmic light chains. Seven cases were defined as B-cell type, all of which possessed lambda light chains in the neoplastic cells. Immunohistologic studies using monoclonal antibodies showed that most non-T-ALL cases were positive for CALLA and B4, whereas about 50% of them were positive for B1. Our immuno-EM study suggests that it is one of the effective ways of subclassifying non-T-ALL in children.

Antibodies, Monoclonal↗
PubMed1988

Measurement of rat brain spectra.

A method of optically monitoring oxygen saturation of blood haemoglobin in the rat brain stem was developed. Optical fiber bundles were attached to the orifices of both ears of the rat to irradiate incident light from one ear and receive transmitted light from the other ear. Absorption spectra were measured using a white-light source and a photodiode array spectrophotometer. Stable measurements of optical time courses and absorption spectra were made using this "ear-to-ear" path. Oxygen saturation levels were calculated from spectra by using a suitable reference and an improved method of determining spectral peak heights.

Animals↗
PubMed1988

DRC antigen expression in B-cell lymphomas.

DRC (dendritic reticulum cell) antigen expression was studied in 38 cases of B-cell lymphomas including follicular lymphoma. The results of this study showed DRC-1 to be expressed in 1/3 of small lymphocytic; 3/3 of mantle zone lymphoma (MZL); 10/10 of follicular, small cleaved; 6/7 of follicular, mixed; 1/2 of follicular, large cell lymphomas. However, DRC-1 was not expressed in any of diffuse, small cleaved (0/6) and diffuse, large cell (0/6). Although S-100 protein was positive in the majority of these DRC-1-positive cases on the paraffin embedded specimens, positive nodules were less intense and smaller in number compared with those of DRC-1 on frozen tissue specimens. These results suggest that in case of small lymphocytic lymphoma found to be positive for DRC-1, the networks of the DRCs are expressed in the pseudofollicular proliferation centers. This study also suggests that the networks of the DRCs newly appear accompanying the neoplastic growth rather than originating from residual germinal centers, and that neoplastic small cleaved cells play a major role in inducing the DRCs in the positive cases of follicular lymphoma, MZL, and small lymphocytic lymphoma.

Antigens↗
PubMed1988

Immunohistochemical study of mantle zone lymphoma.

Lymph nodes from four cases of mantle zone lymphoma (MZL) were studied immunohistochemically. All the cases had serum M proteins. Immunostaining with paraffin-embedded specimens revealed that proliferating cells of neoplastic nodules possessed the same monoclonal immunoglobulins as those in the serum (IgM, kappa in three and IgM, gamma in one). The plasma cells around neoplastic nodules contained the same monoclonal immunoglobulins as those in the nodules in two cases. In the remainder, most plasma cells around the nodules possessed the same immunoglobulins as those in the nodules. The authors consider these plasma cells to be the cause of paraproteinemia. Immunostaining with paraffin and frozen tissue sections revealed that the neoplastic cells (or neoplastic nodules) were positive for sIgD, sIgM, dendritic reticulum cell antigen (DRC-1), and LN-2 and weakly positive for common acute lymphocytic leukemia antigen (CALLA), and LN-1. These results indicate that the neoplastic cells of MZL have both phenotypes of mantle zone lymphocytes (sIgD, sIgM, and LN-2 positive) and of germinal center cells (sIgM, DRC-1, CALLA, and LN-1 positive). MZL is thus considered to be a neoplasma of B-cells differentiating from mantle zone lymphocytes to germinal center cells.

Cell Division↗
PubMed1988

Leu-4 (CD3) antigen expression in the neoplastic cells from T-ALL and T-lymphoblastic lymphoma.

The authors studied Leu-4 (CD3) antigen localization in the neoplastic cells from six cases with T-ALL, eight with T-lymphoblastic lymphoma (T-LL), and eight with peripheral T-cell lymphomas using immunoelectron microscopy (immuno-EM). Other various monoclonal antibody studies were also performed to detect the stages of differentiation of the neoplastic cells light microscopically. The authors' study indicated that cytoplasmic Leu-4 (cLeu-4) antigen expression appeared at the early stage of thymic T-cells, together with Leu-9 (CD7) and T101 (CD5). Their immuno-EM study also disclosed that the neoplastic cells at the early stage of thymocyte differentiation all had positive results for cLeu-4 but negative results for surface Leu-4 (sLeu-4). The Leu-4 antigen expression in the neoplastic cells at the stage of common thymocyte differentiation with OKT6- (CD1) positive phenotype was variable, showing cLeu-4+sLeu-4-, cLeu-4-sLeu-4+, and cLeu-4+sLeu-4+, depending on the cases investigated. From these results, they suggest that cLeu-4 antigen appears at the stage of early thymocyte differentiation, followed by predominant sLeu-4 expression at the stage of common thymocyte differentiation, and finally simultaneous expression of cLeu-4 and sLeu-4 at the stage of peripheral T-cells.

Antibodies, Monoclonal↗
PubMed1988

Meningiomas and hemorrhagic diathesis.

The physical act of operating on 13 patients with meningiomas was studied for its effect on the fibrinolytic system. Fibrinolytic abnormalities, mainly due to an increase of plasma fibrinolytic activity, appeared in three patients prior to, during, or after surgery. These patients demonstrated hemorrhagic diathesis in the operative wounds which was associated with a consumptive coagulopathy, namely, an increase of fibrin/fibrinogen degradation product concentration and a decrease of fibrinogen concentration in plasma. Antiplasmin agents (gabexate and tranexamic acid) were effective in minimizing loss of blood during and after the operation. Abnormal hyperfibrinolysis seems to play a role in hemostatic difficulties in patients undergoing surgery for meningioma.

Adult↗
PubMed1988

Effects of cyclosporine on adrenocortical stress response of Wistar rats.

The effects of cyclosporine on the adrenocortical stress response in Wistar male rats were examined. The adrenocortical response to cold exposure as assessed by serum corticosterone levels was suppressed significantly (25.2%) following the oral administration of 10 mg/kg/day cyclosporine for 10 days compared to that of controls (p less than 0.05). Stress response to cold exposure was also suppressed significantly to a greater extent in rats coadministered with cyclosporine plus 1 or 4 mg/kg/day of prednisolone than in rats administered with each dose of prednisolone alone (16.8% greater for 1 mg/kg prednisolone group; p less than 0.01, or 22.3% greater for 1 mg/kg prednisolone group; p less than 0.005). Stress response of ACTH was also suppressed significantly to a greater extent in animals coadministered with cyclosporine plus 1 or 4 mg/kg/day of prednisolone than in rats administered with each dose of prednisolone alone (37.5% greater for 1 mg/kg prednisolone group; p less than 0.025, or 25.7% greater for 4 mg/kg prednisolone group; p less than 0.025). However, the decrement in ACTH levels by cyclosporine did not always result in corresponding decrement of serum corticosterone levels. These results suggest that cyclosporine decreases the adrenocortical response in part via suppression of the pituitary-adrenal axis. However, direct effects of cyclosporine on the adrenal gland should not be neglected.

Adrenal Cortex↗
PubMed1988

Anti-Leu-3a antibody reactivity with Reed-Sternberg cells of Hodgkin's disease.

Eleven cases of Hodgkin's disease were studied using ten monoclonal antibodies. Our findings indicated that Reed-Sternberg cells and Hodgkin's cells were distinctly stained for HLA-DR and LN-2 in all the cases, for Leu-3a in six cases, and for Leu-M1 in eight cases. They were not stained for Leu-1, Leu-2a, Leu-4, OKT3, OKT6, or LN-1 in any of the cases. Although these results remain insufficient to find any conclusions concerning the nature of Reed-Sternberg cells and Hodgkin's cells, Leu-3a reactivity may represent the aberrant form of T-cell phenotype. Alternatively, we suggest that Reed-Sternberg cells and Hodgkin's cells may be derived from monocyte-macrophage lineage because normal and neoplastic cells of monocyte/macrophage lineage express Pan-T antigen-/HLA-DR+/Leu-3a+/OKT6- phenotype.

Antibodies, Monoclonal↗
PubMed1988

Changes in the concentration of testosterone in serum during the menstrual cycle, as determined by liquid chromatography.

We used a newly developed high-performance liquid chromatographic (HPLC) method to determine the concentration of testosterone in serum from women and compared the results with those obtained by conventional radioimmunoassay. We used a conventional silica gel column and organic solvent mixture (ethanol plus n-hexane containing a small amount of water). The detection limit for testosterone was as low as 0.2 micrograms/L, sufficient to correctly determine the concentration of the hormone in serum from women. For the calibration curve, we plotted the peak-height ratio of testosterone to 19-nortestosterone. The menstrual-cycle-related rhythm of the concentration of testosterone in serum was related to follicular and luteal phase-shifting, the concentration being considerably greater in the luteal phase than in the follicular phase. In contrast, RIA showed only minor and irregular fluctuation in the concentrations of the hormone throughout the menstrual cycle. When we used the HPLC to measure the hormonal change in a woman with an irregular menstrual cycle, we found that her testosterone concentration increased abnormally early after menstruation.

Adult↗