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Biomedical subjects

D Townsend

Publications and source records attributed to D Townsend.

79 records · Page 5Linked to original sources
PubMed1970

Lipid Composition of the Hemagglutinating Active Fraction Obtained from Chick Embryos Infected with Chlamydia psittaci 6BC.

The lipid composition of the concentrated hemagglutininating active fraction (HF) of allantoic fluid from infected eggs, but free from Chlamydia psittaci 6BC, was compared to concentrated normal allantoic fluid (NAF). Phosphatidyl-choline (PC) and phosphatidylethanolamine were the major lipid classes of the total phospholipid fraction. Some quantitative differences were found in the amount of PC and phosphatidylserine present in HF and NAF. Lysophosphatidylcholine was present in HF but absent in NAF. Triglycerides and sterols were the major lipid classes found in neutral lipids of HF and NAF. Quantitative data showed distinct differences in the amount of different neutral lipid classes present between HF and NAF. The fatty acids of various classes of lipids were examined, and differences were noted in a number of phospholipids, sterol esters, and the free fatty acids. Branched-chain saturated fatty acids were found in many lipid classes of the HF, particularly in the phosphatidylethanolamine fraction, but were absent in the NAF.

Journal Article↗
PubMed1970

Lipid composition of Chlamydia psittaci grown in monkey kidney cells in defined medium.

The lipid compositions of (i) monkey kidney (MK-2) cells cultivated in Eagle's minimal essential medium (MEM) with 5% calf serum, (ii) MK-2 cells cultivated in Waymouth medium supplemented with 20 mug of sodium oleate and 2 mg of bovine albumin per ml, (iii) Chlamydia psittaci strain 6BC grown in the latter host system, and (iv) calf serum were compared. Strain 6BC contains 31% phosphatidyl ethanolamine (PE) and 15% phosphatidyl glycerol (PG), whereas the host cell contains almost the same amount of PE (27%) and no PG. A high concentration of total lipid was observed in strain 6BC (29 to 34%), whereas MK-2 cells contain only 9 to 15% and calf serum contains 4.5% total lipid. The fatty acids of the total lipid from strain 6BC contain branched-chain acids. These fatty acids were found mostly in PE (33.0%) and PG (37.0%). No branched-chain fatty acid was found in the MK-2 cells. There was an increase in triglyceride content when MK-2 cells cultivated in MEM (19.2%) were compared with cells cultivated in Waymouth medium (28.0%). A high concentration (62.0%) of octadecenoic acid (C18:1) was found in the triglyceride of MK-2 cells cultivated in Waymouth medium. The level of polyunsaturated fatty acids observed in MK-2 cells cultivated in Waymouth medium (10.8%) and in the chlamydiae grown in these cells (13.3%) was low compared with the level in MK-2 cells (28.8%) cultivated in MEM with 5% calf serum and the level in calf serum itself (50.8%). A higher ratio of sterol ester to free sterol was found in calf serum than in MK-2 cells or in chlamydiae. Host contribution to lipid composition of strain 6BC is discussed.

Animals↗
PubMedDate not supplied

Decreased dopachrome oxidoreductase activity in yellow mice.

Dopachrome oxidoreductase (DCOR) is a newly characterized enzyme in the melanin synthetic pathway, active in the conversion of dopachrome to 5,6-dihydroxyindole. DCOR and tyrosinase activity were measured in skin anagen hairbulbs from lethal yellow (Ay/a), sienna yellow (Asy/a) and recessive yellow (e/e) mice with and without treatment with melanocyte-stimulating hormone (MSH). DCOR activity was low (Asy/a) or absent (Ay/a, e/e) in yellow mice without MSH treatment, and increased dramatically in the lethal and sienna yellow mice with MSH. There was no increase in DCOR activity in recessive yellow mice with MSH. Corresponding tyrosinase activity was reduced in lethal yellow and sienna yellow mice without MSH, and increased with MSH. Tyrosinase activity was normal in recessive yellow mice without MSH and did not change with MSH. We conclude that DCOR is an MSH-sensitive enzyme and that DCOR activity is absent in recessive yellow melanocytes. The latter finding suggests that the extension locus may be the DCOR locus.

Animals↗
PubMedDate not supplied

In vitro cell changes in laser-exposed tissue.

Tissue cultures of WI 38 human embryonic lung were exposed to CO2 laser irradiation while others were maintained unexposed as controls. In the test cultures the target area demonstrated cell dehydration and distortion, consisting of nuclear and cellular elongation and cytoplasmic fragmentation. Regeneration of the cultures was gradual and incomplete.

Carbon Dioxide↗