Biomedical subjects

J Lerner

Publications and source records attributed to J Lerner.

At least 37 records · Page 2Linked to original sources

PubMed1983

Developmental changes in amino acid transport in the chicken erythrocyte.

1. Influx of leucine, lysine and glycine was found to be highest in prehatch (day -1) chicken red blood cells and to diminish during posthatch development when tested at two and four weeks of age. 2. The greatest decline in transport rate during development was seen with leucine; lysine showed a substantial age-related decline only at substrate concentrations greater than Km, the apparent Michaelis constant of transport. 3. Vmax, the maximal transport influx, of each amino acid tested declined during development. 4. Km of glycine and leucine appeared to increase slightly over the test period. 5. In contrast, a 7-fold decrease in Km for lysine transport was seen over the same period. 6. These results are discussed in context of changes in kinetic parameters of amino acid transport during development reported for various animal organs or tissues.

Aging↗

PubMed1982

Amino acid transport and intracellular Na+ and K+ content of chicken erythrocytes genetically selected for high and low leucine transport activity.

1. Amino acid transport and intracellular Na+ and K+ content have been studied in two lines of chickens, one high and the other low uptake, selected for their ability to transport leucine into erythrocytes. 2. Low line birds were less effective in absorbing glycine into erythrocytes than were high line birds, the difference in transport being due to a difference in maximal flux (Vmax), but not in apparent affinity for transport sites (Kt). 3. In contrast to glycine uptake, the greater ability of the high line to absorb lysine was found to be due to a difference in both Vmax and Kt. 4. High line erythrocytes were also observed to contain slightly more K+ (about 5%) and about 20% less Na+ than low line erythrocytes. 5. These results are discussed in terms of the ion dependency of amino acid transport.

Amino Acids↗

PubMed1982

Uptake of leucine and lysine in chicken red blood cells of varying density.

1. Reproducible separations of chicken red blood cells into three density ranges have been achieved employing Ficoll density layer centrifugation techniques. 2. Carrier-mediated lysine uptake was observed to be much greater than that of leucine and was found to decrease with an increase in cell density due to a change in the maximal uptake rate (Vmax) but not in apparent uptake affinity (Kt). 3. Little difference was seen between cells of varying density in their ability to absorb leucine. 4. Since red blood cell density increases with cell age, these results suggest that the uptakes of leucine and lysine are affected differentially during cell aging.

Animals↗

PubMed1981

Selective breeding of chickens for erythrocytes with high and low leucine transport activity.

Two lines of chickens, one high and the other low uptake, have been selected for three generations for their ability to transport leucine into erythrocytes. Significant line differences were produced in one generation of selection with further separation resulting in later generations. Selection progress has been exclusively with the high-uptake line, the low line not differing significantly from the control. The maximal rate of leucine uptake, the stimulation of leucine transport by medium Na+, lysine uptake, and the Na+-K+-ATPase activity all were greater in the high line. Rates of glucose transport were not different between the lines nor were intracellular concentrations of Na+ or K+.

Animals↗

PubMed1981

Development of brush-border membrane hexose transport system in chick jejunum.

Hexose transport was characterized in jejunal slices and brush-border membrane (BBM) vesicles from chicks of several ages (range: 2 days before hatch to 21 days after hatch). With slices, initial rates of 0.1 mM 3-O-methyl-D-glucose transport were low in --2-, and 0-day chicks, increasing to maximal levels 2-7 days after hatching; rates declined to adult levels over the next 2 wk. Phlorizin did not inhibit uptakes in --2- or 0-day slices. In contrast, about 80% of the uptakes in tissue from 2-day or older chicks was phlorizin inhibitable. The apparent Kt for phlorizin-sensitive transport was the same in slices from 2- (maximal transport rates) and 21-day (minimal posthatch rates) chicks; the apparent Vmax was 2.5 times greater in 2-day slices. With BBM vesicles, initial rates of Na-dependent D-glucose transport and maximal overshoot levels were greater in 2-day vesicles than in 21-day vesicles. As in slice experiments, Kt values were the same in the two preparations, but Vmax values were 1.4 times higher in the 2-day preparation.

Aging↗

PubMed1981

Experimental prostatitis in female Mastomys natalensis--a preliminary report.

Female Mastomys natalensis were inoculated with a suspension of Klebsiella pneumoniae into the bladder. All animals developed prostatitis without urinary tract infection between the 9th and the 12th day after inoculation. 10(4) - 10(5) CFU of K. pneumoniae per gram prostatic tissue could be cultivated. Histologically acute purulent prostatitis was detected in most cases 6 days after infection. In the follow-up periacinar infiltration predominated.

Animals↗

PubMed1980

HgCl2 inhibition of D-glucose transport in jejunal tissue from 2 day and 21 day chicks.

Chick jejunal slices that were exposed to HgCl2 exhibited markedly reduced uptakes of D-glucose. The carrier-mediated (phloridzin inhibitable), but not diffusive, component of uptake was affected by Hg. Within each age group, I50 values (concentration of HgCl2 causing 50% inhibition of mediated transport) for slices (mucosal plus serosal exposure) and sacs (mucosal exposure only) were nearly identical; values for brush border membrane vesicles were slightly lower (increased sensitivity). For each preparation, I50 values for 2 day chicks were consistently lower than corresponding values for 21 day chicks. Taken together, these data indicate that the jejunal brush border membrane is a site of HgCl2 action and that membrane sites in tissue from 2 day chicks are more sensitive to Hg than similar sites in tissue from 21 day chicks.

Age Factors↗

PubMed1980