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Biomedical subjects

M Machida

Publications and source records attributed to M Machida.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Case report of choriocarcinoma of testicular origin indicating marked efficacy of a combination chemotherapy of methotrexate, vincristine, actinomycin D, cyclophosphamide, adriamycin and melphalan].

The patient was a 26-year-old male. He was admitted to our hospital with a chief complaint of hemoptysis, cough and left scrotal mass on May 9,1984. Chest X-ray film, LAG and CT revealed multiple lung, lymph node and cerebral metastases. Based on a diagnosis of testicular neoplasm, orchiectomy was performed on May 14,1984. PVB chemotherapy (Cis-diamminedichloro-platinum, Vinblastine and Pepleomycin) was administered. Because he got worse, however, he was treated with another combination chemotherapy, consisting of Methotrexate (MTX, 100 mg/m2 intravenous push (i.v.), 200 mg/m2 12-h infusion, day 1. The dose of MTX was increased with each course. Maximum dose of MTX was 900 mg/m2/day), Vincristine (1.0 mg/m2 i.v. day 1.) Actinomycin D (10 micrograms/kg i.v. days 3.4.5), Cyclophosphamide (600 mg/m2 i.v. day 3.), Adriamycin (30 mg/m2 i.v. day 8.) and Melphalan (6 mg/m2 p.o. day 8.). After 6 courses of this regimen, distant metastases disappeared or were reduced to under one tenth, and complete remission was obtained without severe side effects. The patient was in good health on March 30, 1985.

Adult↗
PubMed1985

Allosteric effect of fructose 1,6-bisphosphate on the conformation of NAD+ as bound to L-lactate dehydrogenase from Thermus caldophilus GK24.

The allosteric effect of fructose 1,6-bisphosphate (Fru-1,6-P2) on L-lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) from Thermus caldophilus GK24 was studied by means of 1H NMR analyses. The conformation of NAD+ as bound to the T. caldophilus enzyme was elucidated by analyses of the transferred nuclear Overhauser effects (TRNOE), in the presence and the absence of the allosteric effector, Fru-1,6-P2. Upon binding of Fru-1,6-P2 to the enzyme, the ribose ring of the adenosine moiety of NAD+ is converted from the C2'-endo form to the C3'-endo form. This C3'-endo form of the adenosine moiety is similar to that of NAD+ as bound to nonallosteric vertebrate enzymes. However, the anti conformation of the adenine-ribose bond of NAD+ as bound to the T. caldophilus enzyme is not affected by the binding of Fru-1,6-P2. In contrast, the syn conformation of the nicotinamide-ribose bond is converted to the anti form on the binding of Fru-1,6-P2, while the ribose ring remains in the C3'-endo form as found in the case of a nonallosteric enzyme. Such a conformational change of enzyme-bound NAD+ as found on TRNOE analysis is essentially involved in the allosteric regulation of the T. caldophilus enzyme by Fru-1,6-P2.

Adenosine↗
PubMed1985

Stationary negative potentials near the source vs. positive far-field potentials at a distance.

We studied the field distribution of referentially recorded negative potentials after stimulation of the median nerve at the wrist in 15 normal subjects. When recorded from multiple sites along the lateral aspect of the arm with the reference electrode at the knee, 3 negative peaks, N3, N6 and N9, appeared at fixed latencies. Of these N3 and N6 were highest in amplitude at the distal insertion of the brachioradialis and the distal end of the deltoid, respectively, and N9, at the acromion. With stimulation of the finger, the negative peaks shifted in latency by about 3 msec, indicating an anatomically fixed generator source for each component. When compared to far-field potentials, N9 was of the same latency as scalp recorded P9, that extended to the arm contralateral to the side of stimulation and to the upper half of the trunk. In contrast, N6 extended to the scalp with P6 spreading to the lower half of the body. When two subjects were connected by the arm, stationary negative or positive peaks were transmissible from the stimulated to the non-stimulated subject. When the stimulated arm of the first subject was in contact with the second subject, N3, N6 and N9 were recorded in the latter. Only P9 was registered when the unstimulated arm was in contact with the second subject. We conclude that N3, N6 and N9 are stationary negative potentials generated at certain points along the nerve pathway, probably representing a negative counterfield for positive far-field peaks, P3, P6 and P9. These stationary potentials can spread widely in a volume conductor and can even be detected in a non-stimulated subject making a close contact to the generator source.

Adolescent↗
PubMed1985

Fructose 1,6-bisphosphate-dependent L-lactate dehydrogenase from Thermus aquaticus YT-1, an extreme thermophile: activation by citrate and modification reagents and comparison with Thermus caldophilus GK24 L-lactate dehydrogenase.

Heat-stable fructose 1,6-bisphosphate-dependent L-lactate dehydrogenase [EC 1.1.1.27] was purified from an extremely thermophilic bacterium, Thermus aquaticus YT-1. The amino acid composition and NH2-terminal 34 amino acid sequence of the enzyme were determined. Its NH2-terminal sequence shows high homology with those of Thermus caldophilus GK24 (82% identity) and some other bacterial L-lactate dehydrogenases (44-53% identity), indicating the close phylogenic relationship of the two Thermus species. At the same time, the two Thermus L-lactate dehydrogenases were found not to be identical not only chemically but also kinetically and immunologically. Citrate activated the T. aquaticus enzyme in the weak acidic pH region, while fructose 1,6-bisphosphate did in both acidic and neutral pH regions. The maximum activity obtained with citrate at pH 5.0 was about 2.5 times higher than that in the presence of fructose 1,6-bisphosphate at pH 6.7. The enzymes modified with 2,3-butanedione, acetic anhydride and diethyl pyrocarbonate in the presence of both NADH and oxamate were desensitized to fructose 1,6-bisphosphate, and the modified enzymes were active even in the absence of fructose 1,6-bisphosphate. All of the modified enzymes examined were still activated by citrate similarly to the native enzyme. These results suggest that the mechanism of activation by citrate is different from that by fructose 1,6-bisphosphate, and that the citrate-binding site is different from the fructose 1,6-bisphosphate-binding site.

Amino Acids↗
PubMed1985

Spinal cord monitoring. Electrophysiological measures of sensory and motor function during spinal surgery.

Various recording methods were tested in 60 patients who underwent scoliosis surgery to find the most suitable technique for the spinal cord monitoring and to elucidate the neuroanatomic relationship of the evoked potentials recorded by these methods. Responses were recorded from the scalp and spine after stimulation of the tibial nerve or the spinal cord. The potentials from electrodes placed over the muscles and the tibial nerve after stimulation of the spinal cord were also recorded. Epidurally recorded spinal evoked potentials after stimulation of the tibial nerve generally consisted of two major negative peaks, NI and NII, and subsequent multiple waves. NI may be mediated through the spinocerebellar tract, and NII is most likely mediated through the dorsal column. The polyphasic waves are probably conducted through the slower sensory ascending pathways. The potentials recorded from the muscle after spinal cord stimulation may be mediated through the motor tract. Various recording techniques described in this study were mutually complimentary in confirming the results of tests recorded in the technically difficult environment of the operating room. In general, spinal cord stimulation recorded from the scalp or the spine was superior to peripheral nerve stimulation in yielding better defined responses. If the potential recorded from the muscle after stimulation of the spinal cord is indeed mediated through the motor pathway, this would be useful to assess motor function during surgery.

Action Potentials↗