Cytogenetic evaluation of human endothelial cell cultures.

Cytogenetic evaluation of serially subcultivated human endothelial cells revealed significant differences between cultures derived from fetal umbilical cords and cultures derived from various vessel sites in adults. A rapid increase in the prevalence of polyploid cells, to levels of 100% in many cases, was detected in human umbilical vein endothelial cell cultures but not in endothelial cell cultures from adult vessels. Because the development of polyploidy has been viewed as one signpost of in vitro senescence, it may be that these in vitro observations of high levels of polyploidy are a reflection of the fact that umbilical tissue is at the end of its in vivo developmental lifespan when studied.

Clinical evaluation in healthy adults of a hepatitis B vaccine made by recombinant DNA.

A vaccine formulated from hepatitis B surface antigen (HBsAg) produced by a recombinant strain of the yeast Saccharomyces cerevisiae was administered to two groups of human volunteers composed of 37 healthy, low-risk adults. Each subject received a 10-micrograms dose of HBsAg at 0, 1, and 6 months. By one month, 27% to 40% of the vaccinees had antibody to HBsAg, and by three months 80% to 100% were antibody positive.

Live attenuated varicella virus vaccine. Efficacy trial in healthy children.

We conducted a double-blind, placebo-controlled efficacy trial of the live attenuated Oka/Merck varicella vaccine among 956 children between the ages of 1 and 14 years, with a negative clinical history of varicella. Of the 914 children who were serologically confirmed to be susceptible to varicella, 468 received vaccine and 446 received placebo. The vaccine produced few clinical reactions and was well tolerated.