Biomedical subjects

M Karplus

Publications and source records attributed to M Karplus.

309 records · Page 18Linked to original sources

PubMedDate not supplied

Construction of a model for the three-dimensional structure of human renal renin.

The aspartyl proteases that have had their complete three-dimensional structures determined by x-ray diffraction techniques exhibit a high degree of structural homology and a correspondingly high degree of sequence homology. Using this homology, we constructed a model for the three-dimensional structure of human renal renin. We then refined and evaluated the model with the energy refinement program called CHARMM. We found that the model for human renin differs from that of mouse submaxillary gland renin in certain features, which may account for the differences in substrate specificity and antibody binding. Amino acid differences between human and mouse renin in the regions that bind the P1' side chain of the substrate appear to change only the shape of the S1' subsite of the enzyme, so that either valine or leucine side chains of the substrate can be accommodated by human renin. Amino acids in the solvent-accessible surface of the 75-85 flap appear to be distinctly different between the two structures and could account for the differences observed in antibody binding to human and mouse renin.

Amino Acid Sequence↗

PubMedDate not supplied

Retinopathy of prematurity in multiple-gestation, very low birth weight infants.

Ninety-nine infants from multiple gestation births and weighing < or = 1500 g at birth were matched with infants from single births to clarify the relationship of multiple gestation to retinopathy of prematurity (ROP). There was no significant difference in the incidence of ROP between the twins and the singletons (relative risk [RR] = 0.84, 95% confidence intervals [CI] = 0.61, 1.16). Logistic regression analysis confirmed that very low birth weight (VLBW), not single or multiple gestation, was the most significant predictor of ROP occurrence in either group. In 27 pairs of twin siblings from the original twin group, where both weighed < or = 1500 g at birth, we found that the second-born twin seemed at higher risk for developing ROP, but logistic regression showed that the lower birth weight of the second twin, not birth order, was the more significant predictor of ROP. These results indicate that ROP screening in VLBW twins may be conducted according to the same standard protocols as for singletons.

Birth Order↗

PubMedDate not supplied

Clitoral and penile sizes of full term newborns in two different ethnic groups.

Standards of penile and clitoral sizes are useful for diagnosis of genital abnormalities. In order to verify whether ethnicity has an effect on the size of external genitalia in newborns, 570 full term infants, Jews (221) and Bedouins (349), at the neonatal department of the Soroka Medical Center were examined. Clitoral length, the distance between the center of the anus to the fourchette (AF) and the distance between the center of the anus and the base of the clitoris (AC) were measured, and the AF/AC ratio was calculated for the females. Penile length was measured in the males. Significant differences in clitoral length (12.6%) between the Jewish group (5.87 +/- 1.48 mm) and the Bedouin group (6.61 +/- 1.72 mm) (p < 0.01) and in the ratio of AF to AC between the two ethnic groups (p < 0.01) were found. To the best of our knowledge, our study is the first to report ethnic differences in genital sizes of newborns.

Arabs↗