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Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 649 records · Page 36Linked to original sources
PubMed1982

Analysis of osteoid-forming activity of human osteosarcoma implanted into nude mice.

Thirty cases of human osteosarcoma were transplanted subcutaneously in BALB/c nude mice. Twenty-four tumours survived in animals and showed the histopathology of the original tumours. Growth of transplantable tumours was closely related to the amount of osteoid tissue and tumours with predominant osteoid tissue showed slow growth. Tumours whose osteoid-forming activity tended to diminish or disappear were likely to fail early during serial transplantation. Two osteosarcoma (SU and ISHI) were established into permanent transplantable strains and were maintained in nude mice for more than three years. These two strains showed striking differences in their growth capacity; SU grew rapidly and frequently formed pulmonary tumours after tail vein injection of tumour cells. Histologically, ISHI osteosarcoma cells continue to form osteoid tissue, whereas SU cells showed anaplastic changes and lost osteoid-forming activity. Alkaline phosphatase and Lactate Dehydrogenase (LDH) activities of tumour tissue were lower in ISHI than SU, and significant elevation of the relative value of Fraction III of LDH isozyme has been demonstrated in SU, and Fraction IV in ISHI. On this basis, the authors discuss the relation between the amount of osteoid formation or LDH isozyme patterns and the malignant potential of human osteosarcoma.

Alkaline Phosphatase↗
PubMed1982

DNA repair ability of cultured cells derived from mouse embryos in comparison with human cells.

DNA repair in mouse cells derived from embryos of 3 inbred strains were investigated in comparison with that in human cells. The levels of unscheduled DNA synthesis after UV irradiation appeared to change at different passages, but capacities of host-cell reactivation of UV-irradiated herpes simplex virus were always reduced to the same levels as those in xeroderma pigmentosum cells. This implied that mouse cells are reduced in excision-repair capacities and that the apparently high levels of unscheduled DNA synthesis at certain passages are not quantitatively related to high levels of cell survival. Essentially no differences in DNA repair were noted among 3 strains--BALB/c, C3H/He and C57BL/10.

Animals↗
PubMed1982

Substrate binding affinity changes in mitochondrial energy-linked reactions.

The effects of uncouplers and valinomycin plus nigericin (in the presence of K+) were studied on the apparent Km for substrates and apparent Vmax of the following energy-linked reactions catalyzed by submitochondrial particles: oxidative phosphorylation, NTP-33Pi exchange, ATP-driven electron transfer from succinate to NAD, and respiration-driven transhydrogenation from NADH to 3-acetylpyridine adenine dinucleotide phosphate. In all cases, partially uncoupling (up to 90%) concentrations of uncouplers of valinomycin plus nigericin were found to decrease apparent Vmax and to increase apparent Km. Results plotted as ln (Vmax/Km) versus the concentration of uncouplers or ionophores showed a linear decrease of the former as a function of increasing perturbant concentration (i.e., decreasing free energy). Because Vmax/Km may be considered as a measure of the apparent first-order rate constant for enzyme-substrate interaction and reflects the affinity between enzyme and substrate to form a complex, the results are consistent with the interpretation that membrane energization leads to a change in enzyme conformation with the resultant increase in enzyme-substrate affinity and facilitation of the reaction rate under consideration. The significance of these findings with respect to the mechanism of action of the energy-transducing systems studied is discussed.

Adenosine Triphosphate↗
PubMed1982

Aspartate: 2-oxoglutarate aminotransferase from bakers' yeast: crystallization and characterization.

Aspartate: 2-oxoglutarate aminotransferase [EC 2.6.1.1] was purified and crystallized from bakers' yeast. The crystalline preparation gave a single band on polyacrylamide disc gel electrophoresis in the presence of sodium dodecyl sulfate. However, in the absence of sodium dodecyl sulfate, the preparation gave one major band with two faint bands, all of which showed the same specific activity, molecular weight and serological properties. These faint bands appeared to be modified forms produced from the major band during the purification. The enzyme showed a molecular weight of 90,000 +/- 8,000 and 92,000 +/- 8,000 by gel filtration and sedimentation equilibrium analysis, respectively. The molecular weight of a subunit was estimated to be 45,000 by sodium dodecyl sulfate slab gel electrophoresis. Each subunit bound approximately 1 mol of pyridoxal 5'-phosphate. The bound pyridoxal 5'-phosphate showed an absorption maximum at 360 nm (epsilon M: 11,500) and 430 nm (epsilon M: 8,200) in alkaline and acidic conditions, respectively. Its proteolytic pK was pH 6.3. The enzyme showed an optimum pH of 8.0-9.0, and fairly high amino donor and acceptor specificities; aromatic amino acids and their corresponding 2-oxoacids were catalyzed at rates of 0.2-0.8% of those for aspartate and oxalacetate, respectively. Michaelis constants for various substrate were: L-aspartate (0.11 mM), L-glutamate (20.0 mM), oxalacetate (0.006 mM), and 2-oxoglutarate (0.16 mM). The antiserum against yeast aspartate aminotransferase did not form precipitin bands with homogeneous aspartate aminotransferases from pig heart cytosol, pig heart mitochondria or Escherichia coli B.

Amino Acids↗
PubMed1982

Effects of acid-dissolution on thin ground sections of enamel caries studied by microradiography and x-ray microbeam diffraction.

In order to obtain information about the chemical reactivity of localized areas within natural enamel caries, thin ground sections prepared from white spot lesions were subjected to HCl solutions with 0.01, 0.05, and 0.1 N concentrations. Microradiographic examination combined by densitometric analysis demonstrated that the surface layer covering demineralized lesions remained relatively stable against acid attacks and that, despite the original lower degree of mineralization, its microradiographic density became higher than that of the underlying normal enamel during acid-dissolution. Another interesting finding was that in the experiment using the most diluted HCl solution, a radiopaque zone became noticeable at the advancing front of the lesions in the course of dissolution. X-ray microbeam diffraction analysis of these sections showed that no apparent alterations occurred in mineral structure of enamel with acid dissolution, except for the decrease in crystallinity of enamel apatite. Based on the results obtained here, one can expect that the surface layer and the interior part of natural carious lesions possess a high degree of resistance to acid attacks, relative to the underlying normal enamel.

Dental Caries↗
PubMed1982

Crystallographic and structural alterations in the mineral phase of human enamel with carious attacks.

The present study aims to obtain further information about the crystallographic and structural alterations in the mineral phase of enamel with the onset of caries. For this purpose, X-ray microbeam diffraction analysis was carried out on ground sections prepared from natural white spot lesions. Electron spin resonance (ESR) analysis was also performed on block samples cut from white spot lesions and from undamaged enamel of the same teeth. The results of crystallinity measurements showed that enamel apatite in demineralized lesions was lower in crystallinity than the apatite in the surface layer and surrounding sound enamel. This X-ray diffraction study also revealed the presence of two non-apatitic minerals in the demineralized lesions. One type of the mineral is whitlockite, giving spotty rings. The nature of the other mineral, giving a single ring-like reflection, remains to be elucidated. A comparison of ESR spectra taken from the caries-attacked and undamaged enamel provided evidence that the former samples have a lower degree of alignment of apatite microcrystals. The occurrence of non-apatitic mineral phases and the observed difference in microcrystalline alignment may be the results of a remineralization process.

Apatites↗
PubMed1982

Electron spin resonance study of sound and carious enamel.

The present electron spin resonance (ESR) study aimed to investigate chemical alterations in enamel apatite associated with carious attacks. Enamel blocks were cut from sound areas and natural white spot lesions of human molar teeth and then X-irradiated at room temperature in air. Q-band ESR analysis of these samples showed the presence of two stable signals in the spectra recorded at room temperature. One of them has been identified at CO3-(3) centers, which originate from the carbonate ion substituting in the apatite lattice. The other signal is tentatively identified as O- defects in the hexad axis of apatite lattice. A comparison of the spectra between sound and carious samples demonstrated that the intensity ratios between the O- and the g parallel component of CO3-(3), R = O-/CO3-(3) (g parallel), are significantly higher in the carious samples than in the sound ones. This suggests that enamel apatite in the white spot lesions may have less carbonate ions in the crystal lattice, or have a higher producibility of the O- defects in its hexad axis. The observed alterations in enamel apatite may well be accounted for by remineralization playing a major role in the formation of white spot lesions, because this acid-dissolution study using irradiated enamel blocks showed that the R values do not increase but decrease in a simple process of demineralization.

Dental Caries↗
PubMed1982

[Comparative study on cefmetazole and cefazolin in the treatment of suppurative otitis media].

Cefmetazole (CMZ) was compared to cefazolin (CEZ) for efficacy and safety in the treatment of suppurative otitis media (including acute otitis media and chronic otitis media in acute aggravating stage) under well controlled clinical trials. The therapeutic effects were analyzed statistically in 172 patients (82 administered CMZ, 90 administered CEZ). The adverse reactions were also analyzed statistically in 199 patients (CMZ 99, CEZ 100) in whom the judgement was possible. 1. The efficacy rate of CMZ (72.3% for good to excellent response) was assessed by physicians in charge to be similar to that of CEZ (59.3%). This was the same being assessed by the committee, too (CMZ 64.6%, CEZ 56.7%). 2. When patients were classified into 2 groups (acute otitis media, chronic otitis media in acute aggravating stage) with respect to diagnosis, statistically significant difference in clinical efficacy assessed by physicians in charge was observed in the cases with chronic otitis media (CMZ, CEZ). In addition, the improvements of flares on the drum membrane and the mucous membrane of eardrum were significantly better in the CMZ group than in the CEZ group. 3. Bacteriologically, 16 cases (19.8%) of S. aureus were resistant to CEZ, while only 1 case (1.2%) to CMZ. CMZ was judged to be effective in 5 of the 6 cases in which CEZ-resistant strains were detected. 4. Side effects were found in 2 cases (2.0%) treated with CMZ: one complained of retching and abdominal pain and the other developed skin eruption. On the other hand, only 1 case (1.0%) developed skin eruption in the CEZ group. These results suggest that CMZ is a new antibiotic agent which is highly valuable in the treatment of suppurative otitis media.

Adolescent↗
PubMed1982

[Basic and clinical evaluations of cefmetazole in postoperative wound infections].

The time course of the concentration of cefmetazole (CMZ) in the serum and in skin and intestinal tissues was determined after a single intravenous injection of 2 g of the drug. CMZ moved into them well. Furthermore, 41 patients with postoperative wound infection (superficial in 29 and deep in 12) were treated with CMZ 2-4 g daily. Bacteriological examination of the lesions with simultaneously carried out. As a result, 101 strains of bacteria were isolated and identified. Mixed infection was found in 27 cases (65.9%). Fifteen strains (14.9%) of E. coli, 15 (14.9%) of B. fragilis, 7 (6.9%) of Klebsiella sp. and 7 (6.9%) of Proteus sp., were the main bacteria isolated. Eight cases (19.5%) had mixed infection of E. coli and B. fragilis. The committee (3 members) evaluated CMZ to be effective in 75.6% (31 of 41 cases) and bacteria disappeared in 60.5% (23 of 38 cases). The side effects observed were pyrosis and feeling of gastric malaise in 1 case. The results suggest that CMZ is useful, which exerts an excellent effect on postoperative wound infections.

Adolescent↗
PubMed1982

[A study on the treatment of pulmonary metastatic osteosarcoma].

The primary site of metastasis of osteosarcoma is the lung. Even if a primary lesion was completely removed by radical surgery, more than 90% of the patients died of pulmonary metastasis in one to two years in the past. A control of osteosarcoma depends upon the prevention and treatment of its pulmonary metastasis. An introduction of chemotherapy consisting mainly of adriamycin and high-dose methotrexate dramatically improved the prognosis of osteosarcoma. We analyzed the clinical data, and gross as well as histopathologic post mortem findings, in 161 cases without chemotherapy and 42 cases with systemic adjuvant chemotherapy. Based on these analysis, we tried to clarify the nature of pulmonary metastasis of osteosarcoma and to evaluate its response to treatment from a standpoint of clinical pathology, hoping that this would yield a clue to future treatment of osteosarcoma.

Antineoplastic Agents↗
PubMed1982

Computerized axial tomography (CAT): the value in the diagnosis of bone and soft tissue tumours.

Computerized axial tomography (CAT) was used in the diagnosis of thirty-five cases of bone and soft tissue tumours. Using CAT and related computations for each tumour, the authors have constructed an atlas of tumour density distributions. CAT densities are useful in the pre-operative diagnosis of bone and soft tissue tumours. Also, CAT cross-sectional images can assess the anatomical location, in relation to the cortex, the medullary canal, and the neurovascular bundle. This is of crucial importance in planning the surgical treatment.

Absorptiometry, Photon↗