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Biomedical subjects

K Ogata

Publications and source records attributed to K Ogata.

At least 289 records · Page 16Linked to original sources
PubMed1991

Location of the motoneurons supplying the rabbit pharyngeal constrictor muscles and the peripheral course of their axons: a study using the retrograde HRP or fluorescent labeling technique.

The location of the motoneurons supplying the rabbit pharyngeal constrictor muscles (the superior and the middle constrictors, and the thyropharyngeus and the cricopharyngeus; the last two collectively compose the inferior constrictor) was investigated with intramuscular injection of HRP or the fluorescent tracer nuclear yellow into the individual muscles. Moreover, the peripheral course of their axons was investigated by injection of HRP into all of the pharyngeal constrictors in conjunction with intracranial severing of either the vagus or the glossopharyngeal nerves. The pharyngeal constrictor motoneurons were ipsilaterally located within a subdivision of the nucleus ambiguus which is formed by a compact arrangement of the smallest neurons of the nucleus and situated in the rostral half of the nucleus. We named that subdivision the compact cell group (CoG). Axons of the pharyngeal constrictor motoneurons traversed the vagal rootlets. The rostrocaudal extent of the pharyngeal constrictor motoneurons covered almost the entire length of CoG at a level from about 500 to 2,900 microns rostral to the obex, with their number being most numerous in the middle one-third level of the CoG. Although the motoneurons of the superior constrictor, those of the middle constrictor, and those of the thyropharyngeous and the cricopharyngeus overlapped considerably in location, they tended to be arranged rostrocaudally in that order. At the middle one-third level of the CoG, where the CoG is subdivided into dorsomedial and ventrolateral subgroups of neurons, the superior and the middle constrictor motoneurons were confined to the medial portion of the dorsomedial subgroup, while the inferior constrictor motoneurons were distributed throughout its entirety.

Animals↗
PubMed1991

So-called embryonal hyperplasia of Bowman's capsular epithelium: an immunohistochemical and ultrastructural study.

The so-called embryonal hyperplasia of Bowman's capsular epithelium (EHBCE) is a rather specific lesion occurring in kidneys of patients maintained on chronic dialysis. It consists of poorly differentiated cells proliferating around sclerosed or obsolescent glomeruli. In this study, immunohistochemical and ultrastructural characterization of EHBCE was performed. The poorly differentiated cells in the lesion exhibited a positive reaction for vimentin and a negative one for cytokeratin (PKK 1) and epithelial membrane antigen. On ultrastructural examination, specialized junctions between adjoining cells, microvilli-like structures on their surfaces, and immature basal folds were observed. These observations suggest that the cells of EHBCE may be associated with the anlage of glomerular epithelium. The background in which neoplasms like renal cell carcinoma or atypical epithelium of cyst wall develop in end-stage kidneys of adult patients on long-term dialysis may cause such a proliferation of poorly differentiated cells in young or paediatric age group patients.

Child, Preschool↗
PubMed1991

Effects of compression and devascularisation on ulnar nerve function. A quantitative study of regional blood flow and nerve conduction in monkeys.

This study investigated the effects of compression, devascularisation and ischaemia with compression on blood flow and function of the ulnar nerve in monkeys. The hydrogen washout technique assessed blood flow; nerve conduction tests determined nerve function. 100 g of external compression produced a significant but incomplete reduction of intraneural blood flow, when conduction velocity decreased significantly and response amplitude deteriorated to zero 28 minutes after the onset of compression. Short-segment devascularisation stopped blood flow but did not influence response latency or velocity. Amplitude was diminished significantly 44 minutes after devascularisation. Tourniquet ischaemia followed by compression produced temporary variability in latency and velocity, while amplitude was diminished only during the compression phase following ischaemia. The overall results suggested that compression and ischaemia influence the nerve conduction response differently and that the effects of compression are potentiated by previous ischaemia, even if this was of short duration.

Animals↗
PubMed1991

Occurrence of 5SrRNA in high molecular weight complexes of aminoacyl-tRNA synthetases in a rat liver supernatant.

The 5SrRNA in the rat liver postmicrosomal supernatant was investigated. Acrylamide gel electrophoresis and Northern blot analysis showed that most of the 5SrRNA was present in the fractions obtained on high molecular weight regions separated by Sephadex G-200 column chromatography of the supernatant, which contained the bulk of the methionyl-tRNA synthetase (Fraction I) and tyrosyl-tRNA synthetase (Fraction II). A high molecular weight complex containing nine aminoacyl-tRNA synthetases [Mirande, M., LeCorre, D., & Waller, J.-P. (1985) Eur. J. Biochem. 147, 281-289] was purified by fractional precipitation with polyethylene glycol 6000, gel filtration on Bio-Gel A-1.5m, and finally tRNA-Sepharose column chromatography, which gave two fractions. Fraction B showed the activities of nine aminoacyl-tRNA synthetases and gave protein bands corresponding to eight previously identified enzymes on SDS-PAGE. Fraction A, eluted with a lower KCl concentration than Fraction B, showed lower activities than fraction B of eight of the aminoacyl-tRNA synthetases, the exception being prolyl-tRNA synthetase. The staining patterns with ethidium bromide of the RNAs after PAGE showed 5SrRNA bands for Fraction A but not for Fraction B. However, Northern blot analysis indicated that 5SrRNA was present in both Fractions A and B. The staining pattern after SDS-PAGE of Fraction A with Coomassie Brilliant Blue showed several protein bands in addition to those observed for Fraction B, one of which, with a staining intensity comparable with those of other bands, was located at the same position as ribosomal protein L5, which is the protein moiety of the 5SrRNA-L5 protein complex of ribosomal 60S subunits.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acyl-tRNA Synthetases↗
PubMed1991

Role of 5SrRNA as a positive effector of some aminoacyl-tRNA synthetases in macromolecular complexes, with specific reference to methionyl-tRNA synthetase.

1) Rat liver 5SrRNA enhanced the activity of methionyl-tRNA synthetase in the macromolecular aminoacyl-tRNA synthetase complex (Fraction B) purified from a rat liver supernatant. 5SrRNA-L5 protein complexes (5SrRNP) had similar effects, whereas other ribosomal RNAs and E. coli 5SrRNA had no effect. 2) 5SrRNA increased the activity of the complex for methionine-dependent ATP-PPi exchange. 3) 5SrRNA increased the activities of methionyl-, arginyl-, and isoleucyl-tRNA synthetases in the complex, but scarcely affected its leucyl-, lysyl-, and glutamyl-tRNA synthetase activities. 4) 5SrRNA increased the activities of the rat liver supernatant for the attachment of [35S]methionine, [3H]isoleucine, [3H]lysine, [3H]proline, [3H]threonine, [3H]tyrosine, and [3H]phenylalanine to endogenous tRNA markedly, and those for [3H]leucine, [3H]arginine, [3H]aspartic acid, and [3H]histidine slightly, but did not affect those for [3H]glutamic acid, [3H]glycine, [3H]valine, [3H]alanine, and [3H]tryptophan. 5) Preincubation of the rat liver supernatant with an antibody against Artemia salina ribosomal protein L5, that cross-reacted with the rat liver ribosomal protein L5, decreased the attachment of [35S]methionine and [3H]isoleucine to endogenous tRNA, and 5SrRNA and 5SRNP enhanced these activities of the supernatant preincubated with antibody. On the other hand, the antibody did not affect that for [3H]alanine. Immune dot blot analysis using the antibody against L5 showed the presence of immunologically the same protein as L5 in the liver supernatant. Northern blot analysis of RNA in the immunoprecipitate prepared from the liver supernatant incubated with the antibody against L5 indicated that 5SrRNA was complexed with L5.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1991

Longitudinal study on forces transmitted from denture base to retainers of lower free-end saddle dentures with Aker's clasps.

The aim of this study was to make a longitudinal analysis of the forces transmitted from denture base to retainers of lower free-end saddle dentures with Aker's clasps using a newly developed transducer. The experimental apparatus consisted of two components, a metal framework and a denture base embedded with a force-detecting unit. This device was the transducer, which could detect changes in lateral and vertical forces transmitted from denture base to retainers at the same time. Forces were measured on several separate occasions from the insertion of new dentures to about 4 months afterwards. The result are summarized as follows: (i) the maximal mean value of vertical forces transmitted from denture base to retainers was decreased after 1 week of insertion of new dentures, then increased and reached a constant level (about 10N) 4-6 weeks after the insertion of new dentures; (ii) there were large differences in the maximal mean value of lateral forces between subjects.

Aged↗
PubMed1991

A case of malignant lymphoma simulating acute myocardial infarction.

A patient with malignant lymphoma suddenly collapsed, and ST segment elevation with complete atrioventricular block was observed on his electrocardiogram during an episode resembling acute myocardial infarction. Cardiac cineangiography revealed posterobasal asynergy of the left ventricle with no significant obstruction in the coronary arterial tree. Autopsy revealed diffuse invasion of the myocardium by lymphoma cells. Left ventricular wall motion was preserved even in the area of massive invasion; there was no true necrosis. Myocardial biopsy may be indicated in patients in whom there is a discrepancy between coronary pathoanatomy and wall motion abnormalities.

Diagnosis, Differential↗
PubMed1991

Thrombosis-inducing activity in plasma of patients with acute respiratory tract infection disappears after treatment.

Thrombosis-inducing activity (TIA) was identified in plasma from 16 of 27 patients (59%) with acute respiratory tract infections. On the other hand, it was present in only 9 of 79 subjects (11%) with chronic lung diseases and 4 of 49 healthy volunteers (8%). In the patients with acute respiratory tract infections, there were significant elevations in plasma fibrinogen, C-reactive protein and erythrocyte sedimentation rate in the TIA-positive group compared with the negative group. Plasma TIA disappeared in all of the 8 patients who were retested for TIA 2-5 weeks after they became disease free. Pneumonia was induced in rabbits by transbronchial injection of viable Escherichia coli. TIA was not present in plasma from normal rabbits, but it appeared in plasma collected 3 days after injection. It then disappeared after 1-2 weeks of treatment with antibiotics. TIA may serve as a marker for inflammatory responses and be a factor responsible for elevated blood coagulation activity in patients with acute infectious diseases.

Acute Disease↗
PubMed1991

Plasma thrombosis-inducing activity in 120 patients with primary lung cancer.

One hundred and twenty patients with primary lung cancer were examined for the presence of thrombosis-inducing activity (TIA) in their plasma. TIA was identified in plasma from 16 of 38 patients with stage 3 (42%) and 31 of 65 patients with stage 4 (48%) disease. On the other hand, only 1 of 17 patients with stages 1 and 2 (6%) showed TIA in their plasma. Cell type did not seem to correlate with the presence of plasma TIA, since TIA was identified in plasma from patients with all cell types. Survival of 32 patients with inoperable non-small cell lung cancer, all stage 4, was studied. The mean survival time was 7.2 months in the TIA-positive group and 10.3 months in the TIA-negative group. This difference was statistically significant.

Adult↗
PubMed1991

Standing radiographs cannot determine the correction in high tibial osteotomy.

The use of standing radiographs to determine correction angles for high tibial osteotomy is not appropriate because the relative angle of the articular surfaces (condylar-plateau angle) in the weight-bearing knee changes after the osteotomy. This may give unpredictable results postoperatively. We found that the condylar-plateau angle in postoperative standing films is very similar to that seen in non-weight-bearing supine views, and suggest that these latter radiographs be used for pre-operative planning. We describe our early results, using a special osteotomy jig, in 140 knees.

Adult↗
PubMed1991

Posterior cruciate ligament reconstruction: a comparative study of two different methods.

The results of posterior cruciate ligament (PCL) reconstruction with the patellar bone-tendon-bone graft performed in 21 patients between 1984 and 1989 were compared with the results of PCL reconstruction using the iliotibial band performed in 12 patients between 1980 and 1984. Much better results were obtained from the procedure using the patellar tendon. Four factors are considered to be responsible for the improvement: precise preoperative assessment of the pathomechanics of the posterior instability and simultaneous correction of collateral laxities if present; isometric placement of the PCL graft; use of a biomechanically sound graft and its secure fixation in the knee; and the concept of full extension of the knee to protect the graft from undue posterior stress during the early postoperative period.

Adolescent↗
PubMed1990

The tryptophan cluster: a hypothetical structure of the DNA-binding domain of the myb protooncogene product.

In the DNA-binding domain of the c-myb protooncogene product (c-Myb) which consists of three repeats of 51-52 amino acids, there are 3 perfectly conserved tryptophans in each repeat. Site-directed mutagenesis of these tryptophans showed that any single or multiple mutations of tryptophan to hydrophilic residues or alanine abolished or greatly reduced the sequence-specific DNA-binding activity, but mutations to hydrophobic amino acids retained considerable activity. Raman spectroscopic study showed that these tryptophans were buried in the protein core. These 3 tryptophans are proposed to form a cluster in the hydrophobic core in each repeat. This hypothetical structure is referred to as the "tryptophan cluster," and it may represent a characteristic property of a group of DNA-binding proteins including the myb- and ets-related proteins.

Animals↗
PubMed1990

A sandwich type enzyme-linked immunosorbent assay for proliferating cell nuclear antigen (PCNA)/cyclin using monoclonal antibodies.

Three hybridomas producing monoclonal antibodies to proliferating cell nuclear antigen (PCNA)/cyclin were newly derived. The specificity of established monoclonal antibodies to PCNA, TOB7, TO17 and TO30, was compared with that of the previously reported PCNA-specific monoclonal antibodies, 19A2 and 19F4. TOB7, TO17 and TO30 reacted with purified PCNA in an enzyme-linked immunosorbent assay (ELISA). A 34 kDa PCNA polypeptide was noted by immunoblotting, the same polypeptide as recognized by 19A2 and 19F4. Epitopes recognized by all those monoclonal antibodies to PCNA were analyzed by competitive inhibition tests using ELISA. The results of those experiments suggested that the epitope recognized by TO17 and TO30 was almost identical to that of 19A2 and closely related to that of 19F4, but different from that of TOB7. Based on those results, a sandwich type ELISA for detection of PCNA was developed using TO17 and TOB7. This system was applied to measure the concentration of PCNA in normal peripheral blood lymphocytes (PBL) before and after stimulation by phytohemagglutinin (PHA), and in tissue extracts from rabbit kidney and thymus (RKE and RTE, respectively). Before mitogenic stimulation, the PCNA concentration in PBL extracts was less than 6 ng/ml (cell concentration 2.5 x 10(7)/ml), but at 48 h after PHA stimulation, when more than 70% of cells were in S phase, its concentration became 1280 ng/ml. RTE which contained many proliferative lymphocytes had much higher concentration of PCNA than RKE. Those results suggested that sandwich type ELISA using TO17 and TOB7 was useful as the quantitative assay to detect blast-transformation and proliferation of cells in vivo.

Antibodies, Monoclonal↗
PubMed1990

Two cases of disseminated Trichosporon beigelii infection treated with combination antifungal therapy.

Two patients with acute leukemia in whom disseminated Trichosporon beigelii infection developed are reported. The T. beigelii infection developed in the first patient while he was receiving 5-fluorocytosine. He was treated with amphotericin B in addition to 5-fluorocytosine. Despite the continued antifungal therapy, multiple organs were invaded by the organisms at autopsy. The second patient was treated with miconazole and norfloxacin. Although this combination antifungal therapy seemed to be effective, this patient required splenectomy for cure of the infection.

Adult↗
PubMed1990

Inhibition of platelet aggregation by S-(1,2-dicarboxyethyl)glutathione, intrinsic tripeptide in liver, heart, and lens.

S-(1,2-Dicarboxyethyl)glutathione (DCE-GS) found in animal tissues or baker's yeast showed strong inhibitory effects on blood coagulation and platelet aggregation. The inhibitory effect of blood coagulation was almost the same as those of EDTA, oxalate, and citrate. DCE-GS did not show chelating activity. As for ADP- or thrombin-induced platelet aggregations, DCE-GS exerted a potent effect on the secondary aggregation, while it was less active in the primary aggregation. DCE-GS gave a distinct lag period in the time course of the secondary aggregation induced by collagen and inhibited most strongly the aggregation induced by arachidonic acid compared with those elicited by ADP, thrombin, and collagen. The peptide, however, did not inhibit the platelet aggregation induced by 12-O-tetradecanoylphorbol-13-acetate. Although both DCE-GS and EDTA inhibited the platelet aggregation which was triggered by ADP, their inhibitory manners were entirely different.

Adenosine Diphosphate↗
PubMed1990

Mitochondrial rhodanese: membrane-bound and complexed activity.

We have proposed that phosphorylated and dephosphorylated forms of the mitochondrial sulfurtransferase, rhodanese, function as converter enzymes that interact with membrane-bound iron-sulfur centers of the electron transport chain to modulate the rate of mitochondrial respiration (Ogata, K., Dai, X., and Volini, M. (1989) J. Biol. Chem. 204, 2718-2725). In the present studies, we have explored some structural aspects of the mitochondrial rhodanese system. By sequential extraction of lysed mitochondria with phosphate buffer and phosphate buffer containing 20 mM cholate, we have shown that 30% of the rhodanese activity of bovine liver is membrane-bound. Resolution of cholate extracts on Sephadex G-100 indicates that part of the bound rhodanese is complexed with other mitochondrial proteins. Tests with the complex show that it forms iron-sulfur centers when incubated with the rhodanese sulfur-donor substrate thiosulfate, iron ions, and a reducing agent. Experiments on the rhodanese activity of rat liver mitochondria give similar results. Taken together, the findings indicate that liver rhodanese is in part bound to the mitochondrial membrane as a component of a multiprotein complex that forms iron-sulfur centers. The findings are consistent with the role we propose for rhodanese in the modulation of mitochondrial respiratory activity.

Animals↗
PubMed1990

An HRP study of location of the rabbit palatopharyngeal motoneurons and peripheral course of their axons.

The location of the rabbit palatopharyngeal motoneurons and the peripheral course of their axons were investigated with intramuscular injection of HRP either in the normal animal or in conjunction with intracranial severing of the vagal rootlets. Labeled palatopharyngeal motoneurons were ipsilaterally located within a subdivision of the nucleus ambiguus which is formed by a compact arrangement of the smallest neurons of the nucleus and situated in the rostral of the nucleus. We named that subdivision the compact cell group (CoG). The labeled motoneurons occupied the caudal half of the CoG at a level from about 500 to 1,900 microns rostral to the obex. Labeling was completely abolished by severing the vagal rootlets, indicating that the axons of the palatopharyngeal motoneurons traversed the vagal rootlets.

Animals↗