Biomedical subjects

T W Turner

Publications and source records attributed to T W Turner.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Male reproductive effects of lead, including species extrapolation for the rabbit model.

The effects of elevated blood lead on semen quality were evaluated in the rabbit model and compared to published effects in humans. Mature, male rabbits were given lead acetate by subcutaneous injection in the dose range of 0 to 3.85 mg/kg on a Monday-Wednesday-Friday basis. In each of eight treatment groups, a dosing regimen was developed to produce blood lead levels of 0, 20, 40, 50, 70, 80, 90, and 110 microg/dL. A 5-week pre-exposure period was followed by a 15-week exposure testing period allowing for response through six cycles of the seminiferous epithelium. Semen analyses revealed that increased blood lead levels were associated with adverse changes in the sperm count, ejaculate volume, percent motile sperm, swimming velocities, and morphology. Hormonal responses were minimal. Testicular pathology revealed a dose-dependent inhibition of spermiation. For six measures of semen quality, threshold estimates ranged from 16 to 24 microg/dL. Using the species extrapolation factor derived in this study, a rabbit dose would have to be divided by 1.56 to obtain the equivalent human dose for an equal percentage decrease in sperm concentration; however, rabbits are 3.75 more sensitive in terms of absolute decrease in sperm count for a given blood lead level.

Animals↗

PubMedDate not supplied

Reproductive function in relation to duty assignments among military personnel.

As a follow-up to the pilot study of semen quality of soldiers with various military assignments a larger, more complete study was conducted. Soldiers were recruited at Fort Hood, Texas. Thirty-three men were exposed to radar as part of their duty assignment in the Signal Corps, 57 men were involved with firing the 155 mm howitzer (potential lead exposure), and 103 soldiers had neither lead nor radar exposure and served as the comparison control group. Both serum and urinary follicle-stimulating hormone and luteinizing hormone and serum, salivary, and urine testosterone levels were determined in all men. A complete semen analysis was conducted on each soldier. For statistical analysis, the primary study variables were: sperm concentration, sperm/ejaculate, semen volume, percent normal morphology, percent motile, percent viable (both vital stain and hypoosmotic swelling), curvilinear velocity, straight-line velocity, linearity, sperm head length, width, area, and perimeter. Variables were adjusted for significant confounders (e.g., abstinence, sample age, race). No statistical differences (P < 0.05) were observed in any measurement. While these results are in agreement with two previous studies assessing soldiers firing the 155-mm howitzer, they contradict our previous report indicating that radar exposure caused a significant decrease in sperm numbers. A possible explanation is that the radar exposure in this study was that used in Signal Corps operations while the men in the previous study were using different radar as part of military intelligence operations. The data presented here in men firing the 155-mm howitzer combined with the results from the previous studies confirms that there are no deficits in semen quality in these men. The contradiction between the results of the radar exposure studies indicates that more data are needed to evaluate the relationship of military radar and male reproductive health.

Adult↗

PubMedDate not supplied

Longitudinal study of semen quality of unexposed workers. Sperm motility characteristics.

As part of a longitudinal study of human semen characteristics of unexposed workers, sperm motility measurements were made using computer-assisted sperm analysis. Motility analyses were conducted on monthly samples from 46 men for 9 months. Measurements of curvilinear velocity, straight-line velocity (VSL), linearity, amplitude of lateral head displacement (ALH), and beat-cross frequency were collected in eight microscope fields for each semen sample. The variability within a sample, between samples from the same individual (between monthly samples), and between individuals were calculated using a nested analysis of variance. For all sperm motility measurements, at least 90% of the variation was observed between cells within a semen sample. For all variables, the component of variation between subjects was the smallest percentage (ranging from 1.3% for ALH to 4.0% for VSL). When sample means were used in the nested analysis of variation, at least 75% of the variation was observed between samples from the same individual. These results will be useful in power calculations for future studies.

Adult↗

PubMedDate not supplied

Longitudinal study of semen quality of unexposed workers: sperm head morphometry.

As part of a longitudinal study of human semen characteristics of unexposed workers, sperm head measurements were made using image analysis (Image Technologies Corp., Deer Park, NY). Morphometry was conducted on monthly samples from 45 men for 9 months. Measurements of area, perimeter, length, width, the width-length ratio, and the oval factor (4 [pi] area/perimeter) of 100 sperm heads per sample were obtained. The variability within a sample, between monthly samples from the same individual, and between individuals were calculated for each parameter. Tolerance intervals for each parameter were calculated, and are expected to contain 75% of all individual measurements. Similar intervals were calculated for the means and coefficients of variation of a semen sample. The largest source of variability was attributed to individual cell variation within a semen sample.

Adult↗