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Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 559 records · Page 31Linked to original sources
PubMed1987

Thiols in oxidative phosphorylation: thiols in the F0 of ATP synthase essential for ATPase activity.

It was shown previously that the ATP synthase complex of bovine heart mitochondria contains an essential set of thiols or dithiols in its membrane sector (F0), whose modification by various reagents results in uncoupling [Yagi, T., and Hatefi, Y. (1984) Biochemistry 23, 2449-2455]. The sensitivity to modifiers was increased by membrane energization, and the uncoupling was reversed by membrane-permeable thiol compounds when modifiers other than alkylating agents were used to uncouple. The present paper demonstrates that there exists in the F0 of bovine ATP synthase another set of essential thiols, whose modification results in reversible inhibition of ATPase activity. These thiols are most susceptible to modification by mercurials (p-chloromercuribenzoate greater than p-chloromercuribenzene sulfonate) and do not appear to be modified by N-ethylmaleimide. The reversible modification of these thiols by mercurials protects the ATP synthase against irreversible inhibition in F0 by N,N-dicyclohexylcarbodiimide. The possible location of these two sets of thiols in the F0 of bovine ATP synthase is discussed.

4-Chloromercuribenzenesulfonate↗
PubMed1987

Differential sensitivities of transformed and untransformed murine cell lines to DNA cross-linking agents relative to repair of O6-methylguanine.

Sensitivities of several murine cell strains to killing by the DNA cross-linking agents 1-(2-chloroethyl)-1-nitrosourea (CNU), cis-diamminedichloroplatinum (II) (Cis-Pt) and mitomycin C (MMC) were measured by post-treatment colony-formation. Virally-transformed murine cells were usually more sensitive to cell killing by these agents than were the parental 3T3 cell strains. The hypersensitivity to CNU of some virally-transformed murine cell strains correlated well with the reduced ability to repair O6-methylguanine (O6mGua), a phenomenon similar to that in human cells. The loss of ability to repair O6mGua, as well as the increased sensitivity of transformed strains to cell killing, may not be due to a mutation but rather due to a change of gene expression associated with transformation by viruses or activation of oncogenes.

Animals↗
PubMed1987

[Significance of surgical adjuvant chemotherapy in osteosarcoma].

The primary site of the metastasis of osteosarcoma is the lung. More than 90% of patients have died of pulmonary metastasis in one to two years. Control of osteosarcoma depend upon the prevention of its pulmonary metastasis. The introduction of chemotherapy consisting mainly of Adriamycin, high-dose methotrexate with Leucovorin rescue and Cisplatinum, dramatically improved the prognosis of osteosarcoma. In the past, when systemic chemotherapy was not available, the five-year survival rate was around 19%. In patients who receive chemotherapy with the current combination of chemotherapeutic agents (ADM, HD-MTX, VCR, CPM, CDDP), the incidence of pulmonary metastasis was low, and the five-year survival rate increased to 65%. In patients who receive chemotherapy, pulmonary metastasis may be either delayed, with a single metastasis appearing after termination of treatment (late isolated type), or early and multiple, emerging in reaction to treatment (early multiple type). It is generally accepted that post-operative chemotherapy can inhibit pulmonary micro metastasis and prove to be of great significance in improving the survival rate of patients with osteosarcoma of extremities and achieve limb salvage operation. On the other hand, effective control of the side effects of drug administration such as nausea, vomiting, alopecia, cardio (ADM) and renal (CDDP) toxicity and bone marrow suppression, is a problem that must be solved as soon as possible.

Adolescent↗
PubMed1986

Purification and characterization of NADH dehydrogenase complex from Paracoccus denitrificans.

An NADH dehydrogenase complex was isolated from the plasma membranes of aerobically grown Paracoccus denitrificans cells by extraction with NaBr and purification on an NAD-agarose column. The NADH-ubiquinone-1 reductase activity of the isolated NADH dehydrogenase complex was about 10 times higher than that of the NaBr extract. The preparation was composed of 10 (6 major and 4 minor) unlike polypeptides, and lacked identifiable components and activities characteristic of other enzyme complexes of the oxidative phosphorylation system. The purified enzyme contained noncovalently bound FMN, nonheme iron, and acid-labile sulfide. The ratio of FMN to nonheme iron to acid-labile sulfide was 1:13 approximately 14:11 approximately 12, suggestive of the presence of multiple iron-sulfur clusters. The isolated NADH dehydrogenase complex cross-reacted with antisera to beef heart mitochondrial complex I and protein fraction derived therefrom, indicating the presence in the Paracoccus enzyme of antigenic sites similar to those in the intact complex I and its iron-sulfur protein and possibly hydrophobic protein fractions.

Flavin Mononucleotide↗
PubMed1986

High tibial osteotomy combined with anterior displacement of the tibial tubercle for osteoarthritis of the knee.

Eighty-nine knees with medial tibio-femoral and patellofemoral osteoarthritis were treated by high tibial osteotomy between 1972 and 1978, and 71 were followed up for at least 5 years, the average being 6 years and 9 months. There was no significant loss of motion as recorded before and after operation. In most patients pain decreased or disappeared, and walking ability was regained. Evaluation using the Japanese rating system showed that there were Good and Fair results in 86% of the cases. The average tibio-femoral angle in the Good group was 169 +/- 5 degrees. The angles in the Poor group varied over a wide range. There were serious complications such as nonunion, malunion and infection in a few cases. In Group 1 (30 knees) high tibial osteotomy alone was performed. In Group 2 (41 knees) there were associated osteoarthritic changes in the patellofemoral joint and a high tibial osteotomy was combined with anterior displacement of the tibial tubercle (ventralization). In comparison, Group 2 had better results with regard to both clinical and radiological evaluation.

Aged↗
PubMed1986

An enzymatic method for the synthesis of [14C]pyridoxal 5'-phosphate from [14C]pyridoxine.

A new enzymatic method for the synthesis of [14C]pyridoxal 5'-phosphate is presented. [14C]Pyridoxal 5'-phosphate was synthesized from [14C]pyridoxine through the successive actions of pyridoxal kinase and pyridoxamine 5'-phosphate oxidase in a reaction mixture containing ATP, [14C]pyridoxine, and both enzymes. [14C]Pyridoxal 5'-phosphate was isolated by omega-aminohexyl-Sepharose 6B column chromatography. The overall yield of the product was more than 60%, starting from 550 nmol of [14C]pyridoxine. The radiochemical purity of the products, as determined by thin-layer and ion-exchange chromatography, was greater than 98%.

Aspartate Aminotransferases↗
PubMed1986

Malignant schwannoma of the mandible.

A case of malignant schwannoma occurring in the mandible of a 76-year-old Japanese woman is presented. Results of the gross examination are described as well as the surgical procedure. Details of the staining techniques for examination of the biopsy specimen are given. The histopathological findings are mentioned including those obtained from radiographic, microscopic, and electron microscopic examination. A discussion of the disease and of its difficulty of diagnosis follows.

Aged↗
PubMed1986

Spontaneous activity of first-order horizontal canal neurons in the guinea pig.

The spontaneous activity of the primary horizontal canal neurons was investigated in 12 alert albino guinea pigs. Seventy-one neurons were recorded for analyzing spontaneous activity. These neurons had an average resting rate of 46.6 +/- 20.9 spikes/sec and a range of 2.2 to 113.6 spikes/sec. This was significantly higher than previously reported data recorded from anesthetized guinea pigs. The neurons were classified into three groups from values of coefficient of variation; regular, intermediate, and irregular firing units. Of the 71 units measured, 42.3% were regular, 42.3% were intermediate, and 15.4% were irregular discharge units. The incidence of the irregular units was slightly lower than that in the anesthetized animals. The difference in resting activity of the primary neurons with or without general anesthesia is discussed.

Acceleration↗