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Biomedical subjects

P Sobti

Publications and source records attributed to P Sobti.

11 recordsLinked to original sources
PubMed2000

Radioenzymatic assay for reductive catalysis of N(5)N(10)-methylenetetrahydrofolate by methylenetetrahydrofolate reductase.

Methylenetetrahydrofolate reductase catalyzes the reduction of N(5), N(10)-methylenetetrahydrofolate to N(5)-methyltetrahydrofolate. Because this substrate is unstable and dissociates spontaneously into formaldehyde and tetrahydrofolate, the customary method to assay the catalytic activity of this enzyme has been to measure the oxidation of [14C]N(5)-methyltetrahydrofolate to N(5), N(10)-methylenetetrahydrofolate and quantify the [14C]formaldehyde that dissociates from this product. This report describes a very sensitive radioenzymatic assay that measures directly the reductive catalysis of N(5),N(10)-methylenetetrahydrofolate. The radio-labeled substrate, [14C]N(5),N(10)-methylenetetrahydrofolate, is prepared by condensation of [C(14)]formaldehyde with tetrahydrofolate and the stability of this substrate is maintained for several months by storage at -80 degrees C in a pH 9.5 buffer. Partially purified methylenetetrahydrofolate reductase from rat liver, incubated with the radio-labeled substrate and the cofactors, NADPH and FAD at pH 7. 5, generates [14C]N(5)-methyltetrahydrofolate, which is stable and partitions into the aqueous phase after the assay is terminated with dimedone and toluene. A K(m) value of 8.2 microM was obtained under conditions of increasing substrate concentration to ensure saturation kinetics. This method is simple, very sensitive and measures directly the reduction of N(5), N(10)-methylenetetrahydrofolate to N(5)-methyltetrahydrofolate, which is the physiologic catalytic pathway for methylenetetrahydrofolate reductase.

Animals↗
PubMed2000

Enlarging single CT lesions can also spontaneously resolve.

Computed tomography in two patients, aged 9 and 14 years, with history of focal seizures, revealed single, small, enhancing CT lesions. These patients were treated with albendazole and anticonvulsants. Follow-up CT scans revealed an increase in the size of the solitary lesions. They were managed conservatively and further follow-up CT scans revealed complete resolution of the lesions. The report suggests that some enlarging CT lesions may also spontaneously resolve. The most likely cause of the enlarging lesions was albendazole therapy.

Adolescent↗
PubMed1983

Late bone metastasis in breast carcinoma.

A 49-year-old woman was free of metastases for 14 years after a left radical mastectomy. Metastases were found only in the skull, also the bone marrow biopsy demonstrated metastases.

Bone Neoplasms↗
PubMed1966

Hydatid disease.

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Adult↗