Biomedical subjects

B Stea

Publications and source records attributed to B Stea.

39 records · Page 3Linked to original sources

PubMed1978

Folate and pterin metabolism by cancer cells in culture.

Malignant cells grown in culture excrete into their growth medium a folate catabolite that can be seen as a blue-fluorescent region on paper chromatograms of such media. This folate catabolite has now been identified by paper chromatography, thin-layer chromatography, and combined gas chromatography-mass spectrometry as 6- hydroxymethylpterin and not as pterin-6-carboxaldehyde as previously reported. Moreover, when pterin-6-carboxaldehyde was added to the growth medium of logarithmically growing malignant cells, it was primarily reduced to 6-hydroxymethylpterin. In contrast pterin-6-carboxylate was the principal product formed from added pterin-6-carboxaldehyde by normal established cell lines in culture. These results have been interpreted as indicative of a possible mechanism of folate catabolism in malignant cells. Folic acid or another folate derivative is oxidatively cleaved at the C-9-N-10 bond to yield pterin-6-carboxaldehyde as one of the products. This derivative is subsequently reduced to 6-hydroxymethylpterin, which is excreted into the growth medium.

Cells, Cultured↗

PubMed1977

Pterin-6-aldehyde, a cancer cell catabolite: identification and application in diagnosis and treatment of human cancer.

Active folic acid degradation with the formation pterin-6-aldehyde is a previously undescribed characteristic of cancer cells in tissue culture. Neither normal adult epithelial and fibroblastic cells nor human amniotic cells nor mouse embryonic fibroblasts degrade folic acid to a measurable degree. Twenty-nine patients whose diagnoses were not revealed until after the test of their first morning urine for pterin-6-aldehyde was completed were studied for the presence or absence of pterin-6-aldehyde by thin-layer chromatography. Pterin-6-aldehyde was found in the urine at about 300 nmol/ml or greater only in those 13 patients with a tissue diagnosis of cancer. When the cancer was totally resected, the pterin-6-aldehyde was no longer found in the urine postoperatively. Pterin-6-aldehyde is not found in the urine of healthy patients at this level of detection unless their diets are supplemented with folic acid.

Adolescent↗

PubMedDate not supplied

Temperature distributions during clinical scanned, focused ultrasound hyperthermia treatments.

In this study a scanned focused ultrasound (SFUS) system was used to heat 66 tumours at various anatomical locations in 52 patients. A total of 160 treatments were given. On average, temperatures were measured in 14 or 15 locations in the scanned volume. The time-averaged temperatures over the 30 min treatment period in the best treatment of each tumour were 44.0 +/- 2.4 degrees C (mean +/- SD) and 39.6 +/- 1.5 degrees C at the location of the highest and lowest sensor, respectively. On average, 39% of the sensors were above 42.5 degrees C. When only the cases that were judged to be good candidates for the hyperthermia device were analysed, 64% of the sensors reached a temperature over 42.5 degrees C with the highest temperature achieved being 45.9 +/- 2.3 degrees C and the lowest 40.7 +/- 1.4 degrees C. Although the system tested has many technical limitations (for example, fixed frequency, beam geometry and power during the scan cycle), the results demonstrate that therapeutic temperatures can be achieved in many tumours. Significantly better temperatures are expected when all of the theoretical potential of scanned focused ultrasound systems has been used.

Body Temperature↗