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Biomedical subjects

L D Longo

Publications and source records attributed to L D Longo.

At least 199 records · Page 11Linked to original sources
PubMed1975

Amino acid transport in placental slices. Mechanism of increased accumulation by prolonged incubation.

The accumulation of alpha-aminoisobutyric acid by placental slices is increased dramatically upon prior incubation of the slices in amino acid-free, buffered saline. This increase is inhibited by inhibitors of protein synthesis and is accompanied by an increased V for the transport process. While alternative explanations are discussed, these data suggest that the incubation effect may be mediated through an increase in the number of available transport sites which are synthesized during the incubation period. Incubation with an amino acid mixture diminishes the increase as well as general protein synthesis, suggesting that a reduced availability of amino acids may initiate compensatory changes in the synthesis of cellular transport proteins.

Amino Acids↗
PubMed1975

Fetal circulation times and their implications for tissue oxygenation.

In an effort to understand O2 delivery to fetal tissues, we measured circulatory transit times using dye dilution methods in near-term fetuses of 19 ewes. Times from dye injection to peak response (+/-1 sec) were: femoral vein to carotid artery 2.2, to femoral arter 2.6, to umbilical artery 3.7; jugular vein to carotid artery 1.7, to femoral artery 2.6; umbilical vein to carotid artery 1.9, to femoral artery 3.4, to umbilical artery 5.1, and umbilical artery to umbilical vein 5.4 sec. These rapid transits suggest that changes in placenta and peripheral tissues will quickly affect one another. The time for a complete circuit of blood through the fetus was 12.6 (+/-1.0 SEM) sec. Following dye dilunjections into an umbilical vein double peaks, separated by 4.9 sec, were recorded in peripheral arteries (44 observations), and the divergence localized to the ductus venosus. Based on relative areas under the two peaks, ductus flow averaged 0.425 +/- 0.052 SEM of total flow returning from the placenta with the remainder taking a slow course through liver parenchyma.

Animals↗