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Biomedical subjects

T Ohshima

Publications and source records attributed to T Ohshima.

At least 415 records · Page 23Linked to original sources
PubMed1978

Properties of crystalline leucine dehydrogenase from Bacillus sphaericus.

The distribution of bacterial leucine dehydrogenase (L-leucine:NAD+ oxidoreductase, deaminating, EC 1.4.1.9) was investigated, and Bacillus sphaericus (IFO 3525) was found to have the highest activity of the enzyme. Leucine dehydrogenase, which was purified to homogeneity and crystallized from B. sphaericus, has a molecular weight of about 245,000 and consists of six identical subunits (Mr = 41,000). The enzyme catalyzes the oxidative deamination of L-leucine, L-valine, L-isoleucine, L-norvaline, L-alpha-aminobutyrate, and L-norleucine, and the reductive amination of their keto analogues. The enzyme requires NAD+ as a cofactor, which cannot be replaced by NADP+. D-Enantiomers of the substrate amino acids inhibit competitively the oxidation of L-leucine. The enzyme activity is significantly reduced by both sulfhydryl reagents and pyridoxal 5'-phosphate. Purine and pyrimidine bases, nucleosides and nucleotides have no effect on the enzyme activity. Initial velocity and product inhibition studies show that the reductive amination proceeds through a sequential ordered ternary-binary mechanism. NADH binds first to the enzyme followed by alpha-ketoisocaproate and ammonia, and the products are released in the order of L-leucine and NAD+. The Michaelis constants are as follows: L-leucine (1 mM), NAD+ (0.39 mM), NADH (35 micrometer), alpha-ketoisocaproate (0.31 mM), and ammonia (0.2 M). The pro-S hydrogen at C-4 of the dihydronicotinamide ring of NADH is exclusively transferred to the substrate; the enzyme is B-stereospecific.

Amino Acid Oxidoreductases↗
PubMed1976

Serial quantitative observations of leukemic and normal hematopoietic cells in the bone marrow of acute leukemia under chemotherapy.

In 87 cases of acute leukemia, leukemic and normal hematopoietic cell count in the bone marrow was serially observed, and the findings were used for evaluating the effectiveness of antileukemic agents and also for determining the grade of decrease in the marrow leukemic cell count required to start the proliferation of normal hematopoietic cells and to obtain complete remission of acute leukemia in adults.

Bone Marrow↗
PubMedDate not supplied

Myeloblastoma formation in acute myeloid leukemia.

The cell surface markers on the leukemic cells of 76 patients with adult acute myeloid leukemia (AML) have been analyzed by indirect immunofluorescence, and the presence of CD56+ leukemic cells was detected in ten of these patients. Four of these 10 CD56+ AML patients developed extramedullary myeloblastomas and in two of them an intracranial myeloblastoma. In contrast, in the remaining 66 CD56- AML patients, only one patient developed a myeloblastoma formation of the subcutaneous. It may be that the CD56 antigen which is an isoform of the neural cell adhesion molecule (NCAM), expressed on neurons, satellite cells of skeletal muscle cells, and on stromal cells, binds these tissues by a homophilic mechanism. CD56+ leukemic cells are capable of invading and of surviving in extramedullary tissues, where they proliferate and develop into a myeloblastoma. Because of this possibility, CD56+ AML patients should be carefully monitored for signs of myeloblastoma formation.

Adolescent↗
PubMedDate not supplied

Fatal injuries of the brain stem and/or upper cervical spinal cord in traffic accidents: nine autopsy cases.

Nine forensic autopsy cases were studied. All had injuries of the brain stem and/or upper cervical spinal cord due to traffic accidents. Among the nine subjects, eight were pedestrians and one was a left, front seat occupant of a vehicle. Examination of these 9 cases revealed that three had ponto-medullary avulsion, two had medullary avulsion and the other four had laceration of the upper cervical spinal cord. Atlanto-occipital dislocation was observed in five cases, and a ring fracture around the foramen magnum in the other two cases. Intraventricular haemorrhage, probably due to tears of the choroid plexus caused by hyperextension or hyperflexion of the head, was found in seven cases. In just one of these seven cases, both of the lateral ventricles were filled with dark red haemocoagulum. Hyperextension is considered to occur more commonly in road trauma cases where the victim is alcoholically intoxicated.

Accidents, Traffic↗
PubMedDate not supplied

Age-dependent expression of 8-hydroxy-2'-deoxyguanosine in human pituitary gland.

A major oxidative product, 8-hydroxy-2'-deoxyguanosine (8-OHdG) is involved in ageing, carcinogenesis, and different diseases. The expression of 8-OHdG in the human pituitary gland was investigated immunohistochemically using specimens from individuals aged 19-88 years. 8-OHdG was localized at the nuclei of the anterior lobar parenchymal cells of the pituitary gland. The number of cells positive for 8-OHdG were counted, and the ratio of the positive cells to the total parenchymal cells was evaluated. The ratios increased in accordance with the ages of the individuals examined. Statistically, there was a significant correlation between the ages in years and the 8-OHdG positive ratios in the anterior lobar parenchymal cells (r = 0.757, p < 0.01). These findings indicate an age-dependent accumulation of 8-OHdG in the pituitary gland, which may also be related to the ageing of neuroendocrine systems as well.

8-Hydroxy-2'-Deoxyguanosine↗
PubMedDate not supplied

Determination of the volatile anesthetics halothane, enflurane, isoflurane, and sevoflurane in biological specimens by pulse-heating GC-MS.

Four kinds of volatile anesthetics (halothane, enflurane, isoflurane, and sevoflurane) that were dissolved in 3 microL of experimental plasma samples were examined by the pulse-heating gas chromatographic-mass spectrometric method, and this approach was found to be reliable for qualitative and quantitative analysis. The analytical results also showed good recovery and accuracy. This method was then applied to real blood specimens taken from patients during surgery. The same blood specimens were also analyzed simultaneously by the conventional headspace method for comparison. The data for the clinical blood specimens examined by these two methods showed reasonable correlation coefficients of 0.914 (enflurane) and 0.937 (sevoflurane). These results indicate that the pulse-heating method is applicable for toxicological and clinical analysis of several kinds of volatile anesthetics.

Adult↗
PubMedDate not supplied

Evaluation of materials for use in extracorporeal circulation. In vitro serum-material interaction.

Polymeric membranes used in extracorporeal circulation procedures of varying hydroxyl (-OH) percent were evaluated with normal human serum to detect differences between chemical composition and serum-material interactions. The materials were evaluated as hollow fibers built into modules, including polypropylene (PP; 0%), polyvinyl alcohol (PVA; 23.7%), ethylene vinyl alcohol (EVAL; 29.7%), Cuprophan (CP; 31.5%), and Hemophan (HP; 30.9%). Data from serum perfusions expressed as percent changes to sham (circuit minus module) showed that solute % decreases were from 0% to 10% in all materials except for PVA (10-22%). Complement activation product % increases were higher with PVA (606-4309%) and CP (48-567%), and mononuclear cell transformation functions (MNCTFs) were more suppressed with PVA (100 to 98%) and CP (10-18%). Despite EVAL and HP having an -OH %, complement activation products were relatively low with EVAL (less than 212%), HP (less than 13%), and PP (less than 131%). MNCTFs were stimulatory with the co-polymer of vinyl alcohol and ethylene (EVAL), and very suppressed by serums from PVA contact. Ethylene vinyl alcohol and modified cellulose (HP) had reduced complement activation despite higher or comparable bulk -OH. Bulk -OH content alone cannot explain the differences observed.

Biocompatible Materials↗
PubMedDate not supplied

Do humoral factors removed by plasmapheresis suppress the cellular immune system in cryoglobulinemia?

The efficacy of plasmapheresis (PP) is believed to be primarily related to the removal of plasma humoral factors. Little is known, however, about the effect of solute removal on cellular systems. The effect of the presence of cryoprecipitable proteins (CPPT) on mononuclear blastogenesis (MNB) and polymorphonuclear cell phagocytosis (PMN-P) was studied. MNB stimulated by concanavalin A (Con A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM) was significantly inhibited in cryoglobulinemic (CG) patients to 70, 75, and 60% that of normal controls, respectively. PMN-P were significantly suppressed to 30% that of normals. CPPT purified from cryoglobulinemic plasmas, type I and type III CG, exhibited higher suppressive effects (and in a concentration dependent manner) on normal MNB and PMN-P than albumin used as a control. The studies indicate that patients with CG have defective leukocyte function and that CPPT have suppressive effects on normal leukocyte function in vitro. Removal of plasma CPPT may improve the immunologic status of CG patients.

Cryoglobulinemia↗