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A Varki

Publications and source records attributed to A Varki.

149 records · Page 9Linked to original sources
PubMed1980

An autosomal dominant gene regulates the extent of 9-O-acetylation of murine erythrocyte sialic acids. A probable explanation for the variation in capacity to activate the human alternate complement pathway.

Nydegger et al. (4) have reported that the difference in susceptibility of erythrocytes from different inbred murine strains to lysis by the human alternate complement pathway is determined by an autosomal locus. We have found a good correlation between the degree of O-acetylation of the erythrocyte sialic acid residues and the susceptibility to complement lysis, whereas there was no correlation between total erythrocyte sialic acid content and complement sensitivity. The major O-acetylated species in all the murine strains is 9-O-acetyl-N-acetylneuraminic acid. We propose that the autosomal dominant locus, which determines complement sensitivity, acts by influencing the extent of 9-O-acetylation of the erythrocyte sialic acid residues. By using recombinant inbred strains, we determined that this genetic locus is probably located on chromosome 9. The nature of the gene product remains unknown.

Acetylation↗
PubMed1980

Detection of accessory spleens with indium 111-labeled autologous platelets.

In two patients with recurrent immune thrombocytopenia, accessory splenic tissue was demonstrated by radionuclide imaging following administration of indium 111-labeled autologous platelets. In one of these patients, no accessory splenic tissue was seen on images obtained with technetium 99m sulfur colloid. This new technique provides a simple means for demonstrating accessory spleens and simultaneously evaluating the life-span of autologous platelets.

Adult↗
PubMed1977

Surface tension of amniotic fluid lipid extracts: prediction of pulmonary maturity.

The surface tension (ST)-lowering properties of an amniotic fluid lipid extract can provide a rapid and reliable means of predicting pulmonary maturity. One hundred and eleven samples from 91 patients were analyzed. A surface tension of less than 56 dynes per centimeter at 120 microliter of extract and less than 46 dynes per centimeter at 220 microliter of extract denoted pulmonary maturity. Values greater than these indicated immaturity. Among fluid samples studied within 48 hours of delivery for the presence or absence of respiratory distress syndrome (RDS) in 71 patients, there were no false positive ST values, while 7 of 22 patients with immature values developed RDS. Surface tension correlates well with the lecithin/sphingomyelin (L/S) ratio but provides clearer definition than the L/S ratio when compared to outcome. Blood and meconium contamination make the surface tension of fluid from babies with pulmonary immaturity appear mature. Identical twins with dissimilar ST values and outcome, as well as serial samples from individual patients, are analyzed and discussed.

Amniotic Fluid↗
PubMed1977

Rapid prediction of pulmonary maturity by amniotic fluid lipid globule formation.

Utilizing the surface tension (ST) lowering properties of an amniotic fluid lipid extract, it was noted that the amniotic fluid lipid layer formed a subsurface globule when the ST reached 36.9 dynes/cm +/- 0.1877 (SEM). The amount of required extract to achieve globule formation varied with the degree of fetal pulmonary maturity and the volume required could be used to differentiate pulmonary maturity (less than or equal to 320 microliter), transitional status (340 to 440 microliter), and pulmonary immaturity (greater than 460 microliter), as related to fetal outcome (amniotic fluid obtained within 48 hours of delivery). Of the 70 patients studied, the 7 (100%) who developed respiratory distress syndrome (RDS) were predicted correctly. Nine of 70 (12.1%) gave false negative results (predicted pulmonary immaturity, no RDS developed); there were no false positives. Globule measurements of a separate series of 74 samples were compared with their L/S ratios. Twenty-two of 24 (91.7%) samples termed mature had an L/S greater than 2.0, while 32 of 42 with a value termed immature had an L/S less than or equal to 1.9. The physical events in the establishment of the monolayer and subsequent globule formation are discussed. This method now provides a rapid and reliable screening indicator of fetal pulmonary maturity.

Amniotic Fluid↗