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Biomedical subjects

P Tremblay

Publications and source records attributed to P Tremblay.

7 recordsLinked to original sources

Pax genes, mutants and molecular function.

The paired domain is a conserved DNA binding motif which was first found in Drosophila segmentation gene products. This paired domain is encoded by a well conserved, paired box DNA sequence, also detected in the genomes of other species. The mouse paired box-containing genes are referred to as Pax genes and are expressed in a distinct spatiotemporal pattern during embryogenesis. Pax proteins are able to bind to specific DNA sequences and modulate transcriptional activity. Interestingly, three different Pax genes have already been shown to correspond to some mouse and human mutants, emphasizing their role as developmental control genes.

Animals

Modulation of CD4 expression on lymphoma cells transplanted to mice fed (n - 3) polyunsaturated fatty acids.

Groups of adult AKR mice were fed well defined fats controlled diet regimens. These consisted of either saturated (beef tallow: 'BT') or (n - 3) polyunsaturated (fish oil: 'FO') fatty acids supplementation to basal mix mouse food. In other groups, the basal mix was given without any fat supplement ('NF'). Six weeks or more after the initiation of these diet regimens, mice received intraperitoneal injection of histocompatible RDM-4 lymphoma cells. Ascites RDM-4 tumors were harvested approximately two weeks later, and some of their physicochemical properties were studied. It was repeatedly found that: (1) the tumor grew considerably faster in the FO-fed donor than in the BT- or NF-fed donors; (2) cell membrane fluidity, content of C20(n - 3) and of C22(n - 3) fatty acids were significantly higher in the FO groups than in both BT and NF groups, while the content of C20(n - 6) and 22:4(n - 6) fatty acids was concomitantly decreased; (3) expression of the CD4 cell surface marker was always significantly diminished in the FO groups, whereas other markers such as CD8, H2K, Thy-1 and LFA-1 were not affected. Similar results were obtained, whether fats constituted from 1% to 16% by weight of the food intake. Use of a recently selected line of the RDM-4 lymphoma, exhibiting higher CD4 marker expression, resulted in similar observations. On the other hand, CD4 expression on cells from lymphoid organs of healthy adult AKR mice was not detectably modulated by the dietary fats.

Animals

Protein quality and quantity in preterm infants receiving the same energy intake.

Fifteen low-birth-weight appropriate for gestational age infants, weighing 1.3 to 1.6 kg, were assigned to three isocaloric formulas differing in the quantity and form of nitrogen delivered. A balance study was done between 21 and 30 days after birth. Nitrogen retention expressed as milligram per kilogram per 100 kcal of metabolizable energy was greater with the 60:40 whey/casein and with the casein hydrolysate preparations than with the 20:80 whey/casein formula, which provided the same amount of energy (150 kcal/kg/day) but smaller quantities of protein (3.5 g/kg/day) than the two others (4.3 g/kg/day and 4.4 g/kg/day). Weight gain until discharge from the hospital and increment of height and head circumference over a three-month period showed an advantage of the two formulas providing higher intakes of protein. This study suggests that with high-energy intakes, protein quality does not affect nitrogen retention and growth unless the quantity of protein ingested falls below a critical level.

Caseins

Concentration and purification of influenza virus from allantoic fluid.

A simple procedure which enables the concentration and purification of influenza virus, using an angular rotor, is described. Virus is concentrated over a sucrose step gradient. The same gradients are reused and volumes up to 4 liters are concentrated in 1 day. The concentrated virus is further purified by a simplified density-gradient technique. No host cell protein is detectable in the final product. The technique offers a broad application potential for concentrating and purifying other viruses.

Allantois