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Biomedical subjects

E Mallett

Publications and source records attributed to E Mallett.

7 recordsLinked to original sources
PubMed2000

Phenylsilsesquioxane fluid: developmental toxicity studies in rats and rabbits following oral administration.

Phenylsilsesquioxane fluid (PSF) is used widely in the personal care industry and is a common component of skin and oral care products. The potential developmental toxicity of PSF was evaluated in rats and rabbits. Groups of 25 sperm-positive Sprague-Dawley rats (Taconic Farms) and 15 sperm-positive New Zealand White rabbits (HRP) were administered dose levels of 50, 500, or 1000 mg/kg PSF in corn oil. Vehicle control groups of equal size were administered corn oil alone. Rats were dosed daily (5 ml/kg) on gestation d 6-15 and sacrificed on gestation d 20, while rabbits were dosed daily (1.5 ml/kg) on gestation d 6-18 and sacrificed on gestation d 29. The fetuses were removed by cesarean section and examined for gross external, visceral, cephalic, and skeletal anomalies. No treatment-related clinical signs of toxicity were observed. No marked effects upon maternal food consumption, body weight, body weight gain, or uterus or liver weight were detected. Fetal viability and body weight, as well as developmental endpoints, were unaffected by treatment. Accordingly, exposure of pregnant rats or rabbits to 50, 500, or 1000 mg/kg of PSF during the period of major organogenesis did not result in any biologically significant adverse or teratogenic effects in the dams or fetuses.

Administration, Oral↗
PubMed2000

Evaluation of the developmental toxicity of 60 Hz magnetic fields and harmonic frequencies in Sprague-Dawley rats.

Experimental data suggest that exposure to the 50 and 60 Hz sinusoidal components of power-frequency magnetic fields (MFs) does not have an adverse impact on fetal development. However, the possible developmental toxicity of MF harmonics has not been investigated. This study was designed to determine whether exposure to 180 Hz MFs (third harmonic), alone or in combination with 60 Hz MFs, induces birth defects in Sprague-Dawley rats. Groups of sperm-positive dams (> or =20/group) were exposed for 18.5 h per day from gestation days 6 through 19 to (1) ambient MFs only (<0.0001 mT; sham controls); (2) 60 Hz MFs at 0.2 mT; (3) 180 Hz MFs at 0.2 mT; or (4) 60 Hz + 180 Hz MFs (10% third harmonic; total field strength = 0.2 mT). Litter size, litter weight, percentage live births, sex ratio, and number of resorption sites were determined for each dam, and gross external, visceral, cephalic and skeletal examinations were performed on all fetuses. MF exposure had no significant effects on litter size, litter weight, or fetal development. With the exception of common rib variants, the incidence of fetal anomalies was comparable in all groups. A small increase in the incidence of rib variants was seen in the group exposed to 60 Hz + 180 Hz MFs; however, the incidence of rib variants in this group was similar to that in historical controls from our laboratory. These data extend the existing database on developmental toxicity of MFs by demonstrating that exposure to 180 Hz MFs, either alone or superimposed on an underlying 60 Hz signal, does not induce biologically significant developmental toxicity. These data do not support the hypothesis that exposure to power-frequency MFs is an important risk factor for fetal development.

Animals↗
PubMed1996

Developmental toxicity study of 60 Hz (power frequency) magnetic fields in rats.

Considerable public concern has developed regarding possible adverse reproductive outcomes resulting from exposure to power frequency magnetic fields (MF). To identify possible effects of MF exposure on fetal development, timed-pregnant female Sprague-Dawley rats (55/ group) received continuous exposure to linearly polarized, transient-free 60 Hz MF at field strengths of 0 Gauss (G; sham control), 0.02 G, 2 G, or 10 G, or intermittent (1 hr on/1 hr off) exposure to 10 G fields. Dams received MF or sham exposures for 18.5 hr/day on gestation days 6 through 19. A positive control group of 15 dams received daily oral doses of 85 mg ethylenethiourea (ETU)/kg body weight on gestation days 11, 12, and 13; positive control dams received no MF exposure. Ambient and experimentally generated MF were monitored continuously throughout the study. Experimentally generated MF were within 2% of the target field strengths at all times, and ambient MF to which sham controls were exposed did not exceed 0.7 mG at any point in the study. No evidence of maternal toxicity was identified in any MF-exposed dam; mean maternal body weight and organ weights in groups exposed to MF did not differ from those in sham controls. Comparisons of fetal viability and body weight demonstrated no biologically significant differences between MF-exposed groups and sham controls. Similarly, a battery of gross external, visceral, skeletal, and cephalic examinations demonstrated no significant differences in the incidence of fetal malformations or anomalies in MF-exposed groups vs. sham controls. By contrast, 100% of the fetuses in the positive control group treated with ETU demonstrated malformations and reduced body weight. Exposure of pregnant Sprague-Dawley rats to 60 Hz at field strengths up to 10 G during gestation days 6-19 did not produce biologically significant effects in either dams or fetuses. These results do not support the hypothesis that exposure to pure, linearly polarized 60 Hz MF is a significant risk factor for the developing fetus.

Abnormalities, Drug-Induced↗
PubMed1988

Access and quality of care for urology patients under diagnostic related group reimbursement.

The Diagnostic Related Group payment mechanism is rapidly changing economic incentives for hospitals. We studied resource consumption and age for a large group of urology patients under Diagnostic Related Group reimbursement. Total hospital costs (exclusive of Diagnostic Related Group reimbursement. Total hospital costs (exclusive of physician fees) for the 1,281 urology patients studied were $8,895,264. Older urological patients consumed a disproportionately larger share of hospital resources. Mean hospital cost per patient, mean number of procedures, hospital length of stay and mortality generally increased with age. Under Diagnostic Related Group reimbursement, financial risk increased with age; patients 75 years and older generated significant financial risk to the hospital. Older patients often had a more intense resource use as measured by emergency or surgical intensive care unit admission, and blood and plasma protein requirements. These findings suggest that the current Diagnostic Related Group payment scheme may provide significant financial disincentives to hospitals vis-à-vis older urology patients and, thus, it could limit the access and quality of care for the older urology patient in the future.

Adult↗
PubMed1986

Management of male infertility: roles of contact thermography, spermatic venography, and embolization.

The leading cause of male infertility is the presence of varicocele. Recently, selective spermatic vein embolization during spermatic venography has afforded a simple, nonoperative treatment. In this study, liquid crystal contact thermography was employed before spermatic venography and after embolization or surgery. Pretreatment thermographic results were in agreement with venography in 15 of 17 cases as 13 were considered positive and two negative by both methods. Thermography further served to document objectively the immediate physiologic effectiveness of either therapy in controlling spermatic vein reflux into the pampiniform plexus. It therefore provides a noninvasive means of evaluating treatment success or recurrence at an early stage. Preliminary thermographic evidence indicates that embolization is a highly effective treatment of reflux. Thermography can also function as a useful, noninvasive screening technique to aid in selecting patients for spermatic venography and embolization therapy.

Adolescent↗