Search PubMed⌕ Search

Biomedical subjects

W Stewart

Publications and source records attributed to W Stewart.

108 records · Page 6Linked to original sources
PubMed1975

Non-obstructive megacystis and refuluxing megaureter in pre-teen enuretic boys with minimal symptoms.

We herein describe 4 older boys with non-obstructive, non-neurogenic refluxing megacystis-megaureter syndrome. These patients require immediate investigation and aggressive surgical intervention, the goal being total reconstruction of the bladder and upper tracts in continuity. This goal was achieved in 3 patients with followup in excess of 4 years. Failure to recognize the syndrome, as with our fourth patient, may result in improper classification and treatment. A plea is made for urological investigation of pernicious nocturnal enuresis in older boys and in all children with a history of urinary tract infection.

Child↗
PubMed1975

Naturally occurring histoplasmosis in the chinchilla (Chinchilla laniger).

Histoplasmosis was diagnosed histopathologically in a female chinchilla. This animal had originated from a commercial chinchilla ranch in central Missouri. Seventeen of 130 animals in the colony had died within a month's period with a respiratory illness. This animal had a history of fur chewing, but this was not true of all the other animals that had died. Histoplasma capsulatum was cultured from timothy hay used for food.

Animal Feed↗
PubMedDate not supplied

The prevalence of the neuropathological lesions of Alzheimer's disease is independent of race and gender.

Senile plaques (SP) and neurofibrillary tangles (NFT) are the lesions characteristic of Alzheimer's disease (AD). In this study, we examined variation in the proportion of individuals who had these lesions by race, age, and gender in a series of 138 autopsies conducted at the Office of the Chief Medical Examiner of the State of Maryland between 1990 and 1998. Cases were selected on the bases of age between 40 to 79 years and non-natural manner of death, and included 73% males, 61% subjects < 65 years of age, and 42% African Americans. Observations were conducted on histologic sections of the hippocampus, entorhinal cortex, and inferior temporal cortex stained with silver (Hirano method) and immunostained for Abeta-amyloid. We found that SP and NFT are strongly associated with age. These lesions begin to appear in the early to late 40s, depending on the anatomic location, and become common in the 6th decade, preceding by one to two decades the age at which AD becomes clinically prevalent. No difference in the prevalence of SP or NFT was found by gender or between whites and African Americans. The latter is in contrast to epidemiologic studies that suggest AD is more prevalent in African Americans than in whites.

Adult↗
PubMedDate not supplied

Associations of subtypes of hemoglobin with delta-aminolevulinic acid dehydratase genotype and dimercaptosuccinic acid-chelatable lead levels.

Hemoglobin in erythrocytes may be an important intravascular site of lead binding. We examined associations of hemoglobin subtypes A1 and A2 with delta-aminolevulinic acid dehydratase (ALAD) genotype, a protein that is another important site of erythrocyte lead binding. After oral administration of dimercaptosuccinic acid (DMSA-chelatable lead), we also examined 4-h lead excretion, which provides an estimate of bioavailable lead stores. We randomly selected 57 South Korean current lead battery manufacturing workers from two plants (N = 290 employees) and from two ALAD genotype strata (ALAD1-1 and ALAD1-2). These workers voluntarily administered 5 mg/kg oral DMSA. We frequency-matched subjects with ALAD1-1 (n = 38) to subjects with ALAD1-2 (n = 19) with respect to duration of employment in the lead industry. Blood lead levels ranged from 11 to 53 microg/dl (mean +/- standard deviation, 25.4 +/- 10.2 microg/dl). After administration of oral DMSA, workers excreted a mean lead level of 85.4 (standard deviation, 45.0 microg; range, 16.5-184.1 microg). Hemoglobin A1 and A2 ranged from 3.7% to 9.9% and 1.6% to 5.9%, respectively (mean +/- standard deviation, 6.2 +/- 1.0% and 2.7 +/- 0.8%, respectively). Subjects with ALAD1-1 had elevated mean hemoglobin A1 levels (adjusted p = .05). In addition, higher hemoglobin A1 levels were associated with higher DMSA-chelatable lead levels (adjusted p = .03). This, as well as the results of prior research, suggest that both ALAD and hemoglobin A1 may be important lead-binding sites that influence urinary lead excretion after administration of DMSA.

Administration, Oral↗
PubMedDate not supplied

Simple visual reaction time in organolead manufacturing workers: influence of the interstimulus interval.

The authors conducted this investigation to study the effects of interstimulus interval duration for a given simple visual reaction time trial on the relationship between lead exposure and reaction time. Organolead manufacturing workers (n=222) and nonexposed referents (n=62) were administered a neurobehavioral test battery that included simple visual reaction time. Simple visual reaction time was measured over 44 trials; interstimulus intervals ranged from 1 to 10 s in a randomly generated sequence that was identical for all study subjects. Mean reaction times for both lead-exposed and nonexposed subjects were longest for interstimulus intervals of 1 and 2 s. Mean reaction times in response to moderate (4-6 s) and long (7-10 s) interstimulus intervals were mainly associated with lead exposure; this association led the authors to suggest that interstimulus interval duration modifies the relationship between lead exposure and simple visual reaction time performance. In simple visual reaction time protocols, stronger associations between reaction time and lead exposure may be found if the analysis trials are separated with interstimulus intervals of less than 3 s duration.

Age Factors↗
PubMedDate not supplied

Thyroid hormones and duration of ovulatory activity in the etiology of breast cancer.

We conducted the present study with the hypothesis that conflicting reports on the association between mild hypothyroidism and breast cancer may be due to failure to consider the potential interaction between thyroid and ovarian hormones. Seventy-three cases of breast cancer and 75 hospital controls were studied. The overall matched multivariate odds ratio of breast cancer for the lowest tertile of free T4 (< or = 1.10 ng/dl) versus the two other tertiles was 1.7 (95% confidence limits, 0.6-5.0). However, there was a statistically significant linear trend (P = 0.04) in the odds ratios for breast cancer related to subnormal free T4 levels across tertiles of duration of ovulatory activity. These results suggest that women combining low levels of circulating free T4 with long duration of ovulatory activity may be at increased risk for this disease.

Adult↗