Jack M. Rary

The utilization of bromodeoxyuridine incorporation into DNA for the analysis of cellular kinetics.

Abstract Recently developed differential staining techniques based on the incorporation of bromodeoxyuridine (BUdR) into DNA permits the unequivocal identification of metaphase cells which have replicated once, twice, and three or more times. This technique has the potential of being utilized in the examination of kinetics of dividing cell populations. This potential is examined in a phytohemagglutinin-stimulated lymphocyte system. Determinations of the effect of increasing concentrations of BUdR on the distribution of metaphase cells between different generation cycles reveals no inhibition of cellular kinetics below 35 μM. The ability to distinguish third generation metaphase cells from subsequent generations is examined through the determination of “labelled” centromeric regions. The applicability of this system to current cellular kinetics is discussed.

AN INVESTIGATION OF DNA REPAIR POTENTIAL IN BLOOM'S SYNDROME

ABSTRACT Blooms syndrome is characterized cytogenetically by increased frequencies of chromosomal aberrations and sister chromatid exchanges. We have earlier suggested that these increases are due to the endogenous production of an agent(s) capable of damaging DNA, and not due to a DNA repair deficiency. In an examination of DNA repair potential, Blooms syndrome cells exhibited an increase in UV-induced unscheduled DNA synthesis and a decrease in chromosomal aberrations induced by a G 2 exposure to ionizing radiation. These findings suggest that instead of being DNA repair deficient, Blooms syndrome cells may have an increased capability of handling certain kinds of DNA damage.

Testicular morphology in the 47XXY fetus at 16 weeks gestation

The testis from two 47XXY fetuses (20 weeks) revealed histologic features not dissimilar from that observed in a normal 46XY fetus of similar gestational age. These findings support the observation that the loss of germ cells in patients with Klinefelters syndrome is an event which begins in infancy and not in utero and progresses through early childhood and the prepubertal period. At puberty germinal aplasia may be complete with clinical evidence of testicular atrophy.