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Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 1,045 records · Page 58Linked to original sources
PubMed1990

Differentiation of lung cancer and radiation fibrosis using magnetic resonance images: a case study.

We used magnetic resonance imaging to differentiate residual and recurrent lung cancer from the surrounding radiation pulmonary fibrosis in a 62-year-old patient. The cancer's signal intensity was greater than the fibrotic lung tissue's intensity in an ECG-gated image with relatively short repetition and echo times and, also, in images with long repetition and echo times.

Diagnosis, Differential↗
PubMed1990

[Angle reproducibility and surface roughness of stone casts obtained from combined agar-alginate impressions].

Angle reproducibility and surface roughness were compared among stone casts obtained from two agar-alginate impression methods; 1) conventional method in which an alginate mix was applied before gelation of agar, and 2) improved method in which an alginate mix was applied to gelled agar. Impressions of the rectangular parallel piped metal mold with a high accurate point angle was taken according to the above methods, and stone casts were obtained. Enlarged images of the angles of the casts were projected with an optical projector, and the defects of the point angle were traced. The area, the length and the circular-degree coefficient of the defects were determined using an image analysis system. The surface roughness of the stone casts was also measured. The stone casts prepared by the improved agar-alginate method had better angle reproducibility and the same surface roughness as that prepared by the conventional method.

Agar↗
PubMed1990

[New low temperature initiator system for dental adhesive resins. Application of peroxyesters with carboxyl group].

Adhesion between dentin and MMA resin was investigated using chemically activated initiator system consisting of 1,3,5-trimethyl-2-thiobarbituric acid, cupric salt, chloride ion, and tert.-butyl peroxymaleic acid (MA) with carboxyl group which usually has affinity to tooth. The adhesive strength of the MMA/PMMA resin to bovine dentin increased significantly to 8-10 MPa by addition of MA, while the adhesive strength was 4 MPa without MA. When the bonding broke at higher than 7 MPa, the adhesive resin layer usually fractured cohesively and the interfacial fracture did not occur. The bond strength obtained in this experiment was comparable to that obtained with MMA resin using TBBO and ferric ion initiator system which is known as the best initiator system for dentin available.

Acrylic Resins↗
PubMed1990

Self-limited neonatal familial hyperparathyroidism associated with hypercalciuria and renal tubular acidosis in three siblings.

Three siblings with neonatal familial hyperparathyroidism diagnosed at age 4 months, 2 months, and 5 days, respectively, were treated. Hypercalciuria, nephrocalcinosis, and renal tubular acidosis were present in each child. In all three, there were higher responses of serum parathyroid hormone to serum calcium and higher elevation of serum calcium with oral calcium loading. The metabolism of vitamin D and calcitonin seemed to be intact. Hypercalcemia associated with the abnormal response of parathyroid hormone secretion disappeared when the children passed the age of approximately 2 years, although renal tubular acidosis and nephrocalcinosis remained. An autosomal recessive inheritance seems likely.

Acidosis, Renal Tubular↗
PubMed1990

[Effect of cepharanthin on radiotherapy induced leukopenia].

Cepharanthin, a kind of alkaloid, has been reported to show a protective effect for leukopenia induced by radiation therapy. In this study, one of three kinds of drugs, Cepharanthin, S-Adchnon (adrenochrome derivative) and Hythiol (L-cysteine), was randomly administered to 94 patients with cancer of the head and neck, the uterine cervix and the lung, during the course of radiotherapy. When Cepharanthin was given, 81.3% of the patients were protected from leukopenia, compared with 51.6% in S-Adchnon and 32.3% in Hythiol. It is suggested that prophylactic use of Cepharanthin may be useful for cancer radiotherapy.

Adrenochrome↗
PubMed1990

[Serological evaluation of human T lymphotropic virus type-I infection in routine hospital samples, especially using serodia.HTLV-I].

Particle agglutination (PA; Serodia-ATLA) and ELISA (Ei-test ATL) assays have been used as routine anti-HTLV-I antibody detection in Japan. However, inconsistent results were obtained by the above methods. We wished to develop criteria for serological confirmation of HTLV-I infection in Hospital samples. Sera obtained in our Hospital from October, 1988 to September, 1989 were tested by five methods of PA (Serodia-ATLA), new PA (improved on the PA; Serodia.HTLV-I), ELISA-I (coated by HTLV-I infected cell lysates as antigens; Ei-test ATL), ELISA-II (coated by recombinant gag-env hybrid proteins as antigens) and IF. The HTLV-I seropositive rates using five methods were not different, ranged from 29.7 to 32.3% in 155 sera. However, PA assays appeared more false positive and rare false negative in some high titer sera. 13 sera as demonstrated negative for ELISA-I and positive for PA (ELISA-I(-)/PA(+] were reevaluated. As results, the antibody were confirmed in only 3 by new PA, 1 by ELISA-II and 2 cases by IF, respectively. On the other hand, 2 by new PA, 4 by ELISA-II and 2 by IF in 18 sera with ELISA-I(+)/PA(-) were interpreted as positive. Therefore, new PA is a remarkable improvement on the PA current model.

Agglutination Tests↗
PubMed1990

[Heart rate changes in sleep apnea syndrome].

Sleep apnea syndrome (SAS) is often associated with arrhythmias. The study was performed to clarify the characteristics and mechanisms of the heart rate (HR) changes during and after sleep induced apneas. Thirty-one patients with SAS without definitive heart disease, aged 17-78 years (mean 54.2 years), were examined by electroencephalograms, electrocardiograms, electrooculograms, nasal and oral breathing, thoracic and abdominal respiratory movements and arterial oxygen saturation (SaO2). [Results and Discussion] At the onset of sleep apnea, some showed progressive reductions in HR, followed by abrupt tachycardia on the resumption of breathing. Thirty-one patients with SAS were classified into three Groups (A, B, C). Group A demonstrated that HR changes occurred associated with apnea both in stage REM and in stage non-REM. Group B demonstrated that HR changes occurred associated with apnea only in stage REM. Group C demonstrated that HR changes did not occur associated with apnea. In Group A, apnea frequency and apnea index were higher than those of Group C. In Group A, the lowest SaO2 was lower than that of Group C, total time under 90% of arterial oxygen saturation (SaO2) was longer than that of Group C. There was a good negative correlation between oxygen saturation and HR changes. Further, HR changes were augmented by arousal response. This might be related to the arousal response as well as to the cardiostimulatory effects of hypoxia associated with increased ventilation. The arousability in response to apneas might be important in HR changes. In SAS, the degree of HR changes was related to apnea frequency, apnea index, apnea length and sleep stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Preparation of monoclonal antibodies against human bone gamma-carboxyglutamic acid containing protein (BGP) and its immunohistochemical application to various human tissues].

Bone gamma-carboxyglutamic acid containing protein (BGP) has been considered to play an important role in mineralization of bone, because this protein is capable of binding to calcium ions. However, the function and localization of BGP in normal bones have not yet been fully understood. In this study, we prepared monoclonal antibodies against human BGP, by immunizing BALB/c mice with human BGP. All five monoclonal antibodies obtained were shown to bind specifically to human BGP, but not to the other bone-derived proteins. In immunohistochemical analysis, these antibodies were shown to react with osteoblasts and osteocytes in normal human bone tissues, but not with chondrocytes, osteoclasts and osteoid tissues. These antibodies are expected to be useful for the diagnosis of human osteoblastic tumors and also for the analysis of the role of BGP in the ossification process in bone.

1-Carboxyglutamic Acid↗
PubMed1989

Sequence and characteristics of the Bifidobacterium longum gene encoding L-lactate dehydrogenase and the primary structure of the enzyme: a new feature of the allosteric site.

The gene ldh, encoding L-lactate dehydrogenase (LDH; EC 1.1.1.27) of Bifidobacterium longum aM101-2, was cloned in Escherichia coli using an oligodeoxyribonucleotide hybridization probe. The amino acid (aa) sequence, deduced from the sequence of the cloned DNA, was consistent with the results of protein chemical analysis of B. longum LDH. The transcription start points (tsp) in B. longum were identified by S1 nuclease mapping. A sequence, GTAGCAA-(14 bp)-TTATAGA, which is located a few bp upstream from the tsp, was assigned as the promoter of this ldh gene. In the 3'-noncoding region, there were two structures that strongly resembled the Rho-independent transcriptional termination signal of E. coli. Therefore, the B. longum ldh gene might form a monocistronic unit. The deduced primary structure of B. longum LDH had 40% identity with LDHs from Thermus caldophilus, Bacillus stearothermophilus, Lactobacillus casei and dogfish muscle. Most bacterial LDHs are allosterically regulated by fructose 1,6-bisphosphate (FBP), while the vertebrate LDHs are not. The anion-binding site of vertebrate LDHs has been thought to correspond to the FBP-binding site of bacterial LDHs. Although the B. longum LDH was regulated by FBP, the charge properties of aa residues in the putative FBP-binding site of the LDH were closer to those of the vertebrate LDHs than to those of bacterial LDHs.

Allosteric Site↗
PubMed1989

Protective effect of lipoproteins containing apoprotein A-I on Cu2+-catalyzed oxidation of human low density lipoprotein.

Two apoprotein A-I (apoA-I)-containing lipoproteins, one containing apoA-I and apoA-II (LpA-I/A-II) and the other containing only apoA-I (LpA-I), were examined for their effect on Cu2+-mediated oxidation of low density lipoprotein (LDL). The presence of LpA-I or LpA-I/A-II prevented LDL oxidation when assessed by the electrophoretic mobility, apoprotein B fragmentation and amounts of thiobarbituric acid-reactive substances. The protection of LDL oxidation by these lipoproteins was effective for up to 6 h, with LpA-I being more active than LpA-I/A-II. Results from these in vitro model experiments raise a possibility that LpA-I may play a role in protecting LDL from Cu2+-mediated oxidation.

Apolipoprotein A-I↗
PubMed1989

Conformation of NAD+ bound to allosteric L-lactate dehydrogenase activated by chemical modification.

On modification of arginine residues with 2,3-butanedione, the Thermus caldophilus L-lactate dehydrogenase is converted to an activated form that is independent of an allosteric effector, fructose 1,6-bisphosphate (Fru-1,6-P2). The conformation of NAD+ bound to the modified enzyme in the absence of Fru-1,6-P2 was investigated by means of proton NMR, analyzing the time dependence of the transferred nuclear Overhauser effect (TRNOE) and TRNOE action spectra. The inter-proton distances determined on TRNOE analysis indicated that both the nicotinamide riboside moiety and the adenosine moiety of NAD+ were in the anti conformation, the ribose rings being in the C3'-endo form. This conformation was almost the same as that of NAD+ bound to the native enzyme-Fru-1,6-P2 complex, rather than that of NAD+ bound to the free native enzyme. These results suggest that the C3'-endo-anti form of the enzyme-bound NAD+ is essential for the activation of the T. caldophilus L-lactate dehydrogenase.

Allosteric Regulation↗
PubMed1989

Immunocytochemical localization of BGP in human bones in various developmental stages and pathological conditions.

Bone gamma-carboxyglutamic acid containing protein (BGP) was isolated from human bone and anti-BGP antibody was produced in rabbits. Localization of BGP was investigated immunocytochemically by light and electron microscopy in human bones in various developmental stages and pathological conditions. In the bones of a 12 week fetus, osteoblasts stained strongly in areas of bone formation. However in bones of late fetal stages and in newborns and adults, BGP was localized predominantly in the osteoid and bone matrix in the ossifying front. Osteoblasts and osteocytes also stained positive, but less dominantly than in the early fetus. Electron microscopy showed that BGP was localized in the ER and Golgi cisternae of osteoblasts and osteocytes, and the collagen fibers of the osteoid and bone matrix. The intensity and distribution of staining were not significantly different in osteoporosis and osteoarthritis. These observations indicate that BGP is synthesized by osteoblasts most actively in early fetal life and is then deposited on collagen fibers of the osteoid and bone matrix.

1-Carboxyglutamic Acid↗