Kevin D. Roberts

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Theta-defensins (θ-defensins) are macrocyclic antimicrobial peptides expressed in leukocytes of Old World monkeys. The peptides are broad spectrum microbicides in vitro and numerous θ-defensin isoforms have been identified in granulocytes of rhesus macaques and Olive baboons. Several mammalian α- and β-defensins, genetically related to θ-defensins, have(More)
Estrone sulfate levels were measured in the plasma of 63 postmenopausal women. The assay method involved prior extraction of the free estrogens, enzyme hydrolysis of the estrone sulfate with sulfatase and radioimmunoassay of the estrone liberated. The plasma levels ranged from 37 to 320 pg/ml (expressed as free estrone) with a mean value of 178 +/- 79(More)
Spermatozoa obtained from the cauda epididymidis possess twice the ability to take up sterol sulfates in vitro when compared to sermatozoa obtained from the caput. This would suggest that a modification of the membrane composition of the spermatozoa occurs during passage through the epididymis. Free sterols are taken up in a similar pattern.(More)
When cultured in monolayers, non-secretory epithelial cells from canine prostates actively synthesize DNA, RNA and proteins; subsequently, mitotic figures and an increase in cell number are observed. During this culture period, cell size and acid phosphatase activity remain constant. As the culture proceeds, these cells mature into secretory cells as(More)
To extend our observations that single or repeated application of a gel containing the NNRTI MIV-150 (M) and zinc acetate dihydrate (ZA) in carrageenan (CG) (MZC) inhibits vaginal transmission of simian/human immunodeficiency virus (SHIV)-RT in macaques, we evaluated safety and anti-SHIV-RT activity of MZC and related gel formulations ex vivo in macaque(More)
Steroid sulfatase of human placenta has been solubilized by treatment of the microsomal fraction with an amphoteric surface active agent, Miranol H2M and ultrasound. Criteria of solubility include non-sedimentation of the activity following centrifugation at 160,000 x g, its retention on Sepharose 6B and a single peak of activity after polyacrylamide gel(More)
Marked variations in the 3beta-hydroxysterol content of hamster spermatozoa were observed as they progress through the epididymis. Cholesterol is the major sterol of caputal spermatozoa while the concentration of precursors of cholesterol was higher than that of cholesterol in caudal spermatozoa. One of these precursors has been identified as desmosterol. A(More)
The interconversion and extraction of estrone and estradiol-17beta across and within different tissues or areas have been studied in the dog by the constant infusion technique. The results were calculated estradiol obtained from afferent and efferent blood and tissues at equilibrium. From these results it is concluded that: (1) there is no significant(More)
Cholesteryl sulfate is a component of human seminal plasma (avg. 445 mug%) and spermatozoa (15 mug/10 (9) cells) and represents more than 85% of the sterol sulfate fraction. This conjugate is avidly bound by spermatozoa when compared to other steroids or steroid sulfates. Autoradiographic localization of CS associated with the spermatozoa revealed a(More)