Biomedical subjects

J F Barrett

Publications and source records attributed to J F Barrett.

110 records · Page 7Linked to original sources

PubMedDate not supplied

The autolytic peptidoglycan hydrolases of Streptococcus faecium.

Streptococcus faecium ATCC 9790 possesses two peptidoglycan hydrolase activities. The first enzyme, an N-acetylmuramoylhydrolase, has been purified and has been shown to be a glucoenzyme. Studies of hydrolysis of soluble, linear uncross-linked peptidoglycan chains showed that the enzyme bound strongly to the non-reducing ends of the chains and then sequentially (processively) hydrolysed susceptible bonds in that chain. The second peptidoglycan hydrolase does not appear to be a glycoprotein and differs from the first enzyme in substrate specificity and mechanism of hydrolysis. The presence of two partially redundant activities which may play different roles in surface growth and division could, at least in part, explain previous difficulties in obtaining mutants which completely lack autolytic activity.

Amidohydrolases↗

PubMedDate not supplied

Fetal urine production rates following intrauterine transfusion.

This study investigates the hypothesis that following an intrauterine, intravascular transfusion (IVT), one of the physiologic adaptations might be an increase in the fetal urine production. The hourly fetal urine production rate (HFUPR) was measured for the first hour following 12 transfusions and for 24 h following 5 transfusions in anemic isoimmunized fetuses. The HFUPR was also measured in 5 control fetuses who underwent fetal blood sampling without transfusion. Fetal hemoglobin, hematocrit and blood viscosity were measured before and after each transfusion. The HFUPR fell significantly from a mean (SEM) of 19.2 (2.85) to 7.4 (2.2) ml/h, and remained low for at least 4 h posttransfusion returning to pretransfusion rates by 24 h. There was no change in the HFUPR in the control fetuses. The study suggests that in human fetuses the rapid excretion of excess fluid via the renal tract is not an acute adaptive response to an IVT.

Adaptation, Physiological↗