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Biomedical subjects

R L Tyndall

Publications and source records attributed to R L Tyndall.

At least 37 records · Page 2Linked to original sources
PubMed1976

Gallium-67 distribution in pregnant mammals.

Studies on the distribution of 67Ga in pregnant rabbits showed a marked concentration of the isotope in uterine tissue and flushings of 5-day pregnant rabbits 24 hours after isotope injection. The isotope no longer localized throughout the uterine tissues and flushings on injection of 7- to 8-day pregnant rabbits but was specifically associated with the blastocysts and sites of implantation. As the gestation time progressed 67Ga increasingly concentrated in placental and mammary tissue while the concentration in serum and thymus tissue decreased. The marked concentration in placental tissue was readily discernible on total-body scans of pregnant rabbits. Column chromatography of uterine washings and placental extracts from pregnant rabbits and thymus extracts from estrous rabbits showed most of the isotope associated with moieties greater than or equal to 200,000 MW whereas the isotope in "milk" and extracts of mammary tissue was bound to components of 25,000-35,000 MW. Extracts of thymus from pregnant rats showed a marked, selective loss of 67Ga binding in two peaks of approximately 50,000 and 120,000 MW compared to the chromatographic profile of extracts from normal rat thymus.

Animals↗
PubMed1975

Early alterations in plasma esterases with associated pathology following oral administration of diethylnitrosamine and butylated hydroxytoluene singly or in combination.

Plasma esterase changes are apparent in BALB/c mice within 3 weeks after feeding them laboratory chow with 0.75% of the antioxidant BHT added. Other esterase changes, different from those in BHT-treated animals, are also apparent in plasma of mice during exposure to the carcinogen DENA. Interference with these DENA esterase alterations is apparent in plasma of mice treated concomitantly with both DENA and BHT. Esterase changes resulting from either the carcinogen or antioxidant exposure precede the overt histologically detected changes induced by these compounds. The early esterase changes and subsequent tumorigenesis resulting from DENA exposure are more severe in female mice. Some of the esterases altered by DENA or BHT exposure are testosterone-related.

Administration, Oral↗
PubMed1975

Alterations in uterine and serum esterases in pregnant mammals.

Uterine flushings, endometrial extracts, and serum from estrous and pregnant rabbits were analyzed by acrylamide gel electrophoresis for esterase activity. Two bands of enzyme activity in uterine findings were detectable on days 4 through 7 after coitus. No activity was detectable in washings from nonpregnant animals or on days 1 to 3 of pregnancy. Esterase activity was detectable in endometrial extracts of all rabbits. The intensity and complexity of the esterase activity markedly increased on day 3 and persisted through day 7 after coitus, during which time nine to ten electrophoretic bands were apparent, compared with four bands in extracts from estrous animals. Serum from pregnant rabbits showed two basic patterns. High esterase activity, concentrated in four major bands, was seen in some sera, while other serum samples showed little esterase activity. No consistent correlation was apparent, however, between the stage of gestation and the serum esterase pattern. In contrast, analysis of mouse serum prior to and after mating showed consistent, reproducible changes in esterase profiles, noticeable about 7 days after coitus and becoming increasingly pronounced until parturition. Changes in mouse serum included both marked enhancement of some esterase activities and concomitant diminution in others with increasing gestation time.

Animals↗
PubMed1975

Pigment production by Cryptococcus neoformans from para- and ortho-Diphenols: effect of the nitrogen source.

Cryptococcus neoformans produced pigments when p-diphenols were substrates in a glucose-amino acid-salts medium. The best substrates were 2.5-dihydroxybenzoic acid and 2,5-dihydroxybenzenesulfonic acid. In contrast to the cellular pigment production from o-diphenols (hydroxyl groups in the 2,3- or 3,4-position of phenyl ring), the p-diphenols (1,4- or 2,5-positions for the hydroxyl groups) produced large amounts of soluble pigments that diffused into the medium. When an optimal source of nitrogen (glutamine, glycine, and asparagine) was used, 89% of the C. neoformans strains produced pigments from p-diphenols. In contrast, 0 to 67% of the strains produced pigments when a suboptimal nitrogen source (proline, ammonium sulfate, ornithine, and methionine) was used. When glutamine-glycine-asparagine was the nitrogen source, 100% of the C. neoformans strains produced pigments from o0diphenols, whereas 77 to 100% of the strains produced pigment when proline-ammonium sulfate-ornithine-methionine was the nitrogen source. Cryptococcus species other than C. neoformans and all tested Candida species failed to produce pigments from any of the substrates except when hydroquinone was used. A combination of glutamine-glycine-asparagine and 3,4-dihydroxyphenylalanine allowed differentiation of colonies of C. neoformans from C. albicans in 3 to 6 days. These data showed that pigment production from o- and p-diphenols served as an excellent biochemical test for the identification of C. neoformans.

Asparagine↗