Exposure of the mouse perinatal testis to radiation leads to hypospermia at sexual maturity.

The first round of mouse spermatogenesis begins from 3 to 4 days after birth through differentiation of gonocytes into spermatogonial-stem cells and type A spermatogonia. Consequently, this step of differentiation may determine generation of the original population of stem cells and the fertility potential of the adult mouse. We aimed to determine the effect of perinatal exposure to ionizing radiation on the testis at the end of the first wave of spermatogenesis and at sexual maturity. Our results show that, radiation sensitivity of the testis substantially decreases from late foetal life to the end of the first week after birth. In addition, partial or full recovery from radiation induced testicular weight loss occurred between the first round of spermatogenesis and sexual maturity, and this was associated with the stimulation of spermatogonial proliferation. Exposure of mice at 17.5 days after conception or at 1 day after birth to gamma-rays decreased the sperm counts at sexual maturity, while exposure of 8 day-old mice had no effect. This suggests that irradiation of late foetal or early neonatal testes has a direct impact on the generation of the neonatal spermatogonial-stem cell pool.

Dynamics of CCR5 expression by CD4(+) T cells in lymphoid tissues during simian immunodeficiency virus infection.

Early viral replication and profound CD4(+) T-cell depletion occur preferentially in intestinal tissues of macaques infected with simian immunodeficiency virus (SIV). Here we show that a much higher percentage of CD4(+) T cells in the intestine express CCR5 compared with those found in the peripheral blood, spleen, or lymph nodes. In addition, the selectivity and extent of the CD4(+) T-cell loss in SIV infection may depend upon these cells coexpressing CCR5 and having a "memory" phenotype (CD45RA(-)). Following intravenous infection with SIVmac251, memory CD4(+) CCR5(+) T cells were selectively eliminated within 14 days in all major lymphoid tissues (intestine, spleen, and lymph nodes). However, the effect on CD4(+) T-cell numbers was most profound in the intestine, where cells of this phenotype predominate. The CD4(+) T cells that remain after 14 days of infection lacked CCR5 and/or were naive (CD45RA(+)). Furthermore, when animals in the terminal stages of SIV infection (with AIDS) were examined, virtually no CCR5-expressing CD4(+) T cells were found in lymphoid tissues, and all of the remaining CD4(+) T cells were naive and coexpressed CXCR4. These findings suggest that chemokine receptor usage determines which cells are targeted for SIV infection and elimination in vivo.

Identifying the target cell in primary simian immunodeficiency virus (SIV) infection: highly activated memory CD4(+) T cells are rapidly eliminated in early SIV infection in vivo.

It has recently been shown that rapid and profound CD4(+) T-cell depletion occurs almost exclusively within the intestinal tract of simian immunodeficiency virus (SIV)-infected macaques within days of infection. Here we demonstrate (by three- and four-color flow cytometry) that this depletion is specific to a definable subset of CD4(+) T cells, namely, those having both a highly and/or acutely activated (CD69(+) CD38(+) HLA-DR(+)) and memory (CD45RA(-) Leu8(-)) phenotype. Moreover, we demonstrate that this subset of helper T cells is found primarily within the intestinal lamina propria. Viral tropism for this particular cell type (which has been previously suggested by various studies in vitro) could explain why profound CD4(+) T-cell depletion occurs in the intestine and not in peripheral lymphoid tissues in early SIV infection. Furthermore, we demonstrate that an acute loss of this specific subset of activated memory CD4(+) T cells may also be detected in peripheral blood and lymph nodes in early SIV infection. However, since this particular cell type is present in such small numbers in circulation, its loss does not significantly affect total CD4(+) T cell counts. This finding suggests that SIV and, presumably, human immunodeficiency virus specifically infect, replicate in, and eliminate definable subsets of CD4(+) T cells in vivo.

An interim report on the development of the Psychological Trauma and Resources Scales.

The William S. Hall Psychiatric Institute Psychological Trauma and Psychological Resources Scales is a preliminary measure for the assessment of psychological trauma and psychological health from a developmental perspective. This three-part article (1) discusses the various rationales leading to the development of the scales, (2) provides a factor-analysis of responses of 336 college students, and (3) addresses current (N = 37) and planned efforts to establish reliability and validity of a more refined version.

Hormonal influences on psychomotor reminiscence.

Psychomotor reminiscence was measured in contraceptively medicated and non-medicated subjects on Days 2, 8, and 14 of their menstrual cycles. As previously reported, mean reminiscence in non-medicated subjects was relatively low on Days 2 and 8, but significantly higher on Day 14. By contrast, reminiscence means in medicated subjects were relatively low and essentially alike across all testing days. These results are discussed within the context of reactive inhibition theory, wherein the adrenergic properties of mid-cycle concentrations of estrogenic hormones are thought responsible for more vigorous responding, hence more reactive inhibition and higher reminiscence. Such concentrations were, of course, precluded by contraceptive medication.

PIP: Psychomotor reminiscence was measured in contraceptively medicated and nonmedicated subjects on days 2, 8, and 14 of their menstrual cycles. The experimental sample of 89 subjects included 48 who were not using contraceptive medication and 41 who had used it consistently for an average of approximately 17 months. All subjects were Caucasian and right-handed and ranged in age from 18 to 25 years. Subjects were required to use mirror vision to track a small silver target as it moved clockwise at 1 rpm through a narrow star-shaped pathway and to keep the tracking stylus on the moving target as long as possible and to avoid touching the sides of the pathway. Time on target to the nearest .01 second was recorded for each minute of practice. 3 successive menstrual cycles for each subject were monitored to provide estimates of average cycle length. The subjects within each medication strategy were then assigned without bias to testing on days 2, 8, or 14 their cycles, or, in the latter case, on proportionately equivalent days as determined from average cycle length. After instruction and demonstration, all subjects executed a sequence consisting of 3 minutes massed practice, 3 minutes rest, 3 minutes massed practice, 3 minutes rest, and 3 minuts massed practice. When endogenous concentrations of estrogenic hormones were kept low by contraceptive medication, mean reminiscence values remained low and essentially alike across testing days, and they were not significantly different from those of nonmedicated subjects who were tested at the nadirs of their cycles. When estrogen concentrations were allowed to reach their natural midcycle peak, as in nonmedicated subjects, mean reminiscence values peaked accordingly. These results are interpreted to mean that the adrenergic properties of high estrogen concentrations promoted correspondingly more vigorous responding and greater accumulations of reactive inhibition, which across rest was manifested as higher reminiscence.