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Biomedical subjects

W Stewart

Publications and source records attributed to W Stewart.

At least 55 records · Page 3Linked to original sources
PubMed1993

Blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES) associated with interstitial deletion of band 3q22: review and gene assignment to the interface of band 3q22.3 and 3q23.

We report on a child with blepharophimosis, ptosis, and epicanthus inversus (BPES), developmental delay and an interstitial deletion of band q22 of chromosome 3. A review of chromosome 3q anomalies associated with eye abnormalities, specifically blepharophimosis and ptosis, strongly suggests that a locus for eyelid development is present at the interface of bands 3q22.3 and 3q23.

Blepharophimosis↗
PubMed1993

Decrements in neurobehavioral performance associated with mixed exposure to organic and inorganic lead.

In 1990, 222 current employees of a chemical facility in the eastern United States that manufactured tetraethyl lead were administered a neurobehavioral test battery, tests of olfactory function and peripheral vibration threshold, and questionnaires that assessed neuropsychiatric symptoms. A cumulative variable of exposure to inorganic and organic lead was derived from 12 years of personal industrial hygiene sampling data and an occupational history interview that assessed work in each of 29 exposure zones in the lead area. The range of assigned exposure intensities in these 29 zones was 4-119 micrograms/m3 for organic lead and 1-56 micrograms/m3 for inorganic lead. Cumulative lead exposure and exposure duration were defined as categorical variables (four groups) in multiple linear regression models. The adjusted mean differences in neurobehavioral test scores were estimated by comparing the average scores of the moderate, high, and highest exposure groups with the low exposure (reference) group. After adjustment for premorbid intellectual ability, age, race, and alcohol consumption, neurobehavioral test scores were poorer as measures of both cumulative lead exposure and exposure duration increased; many of the associations evidenced dose-response relations. Associations were observed in most cognitive and functional domains tested, but were most common in two domains: manual dexterity and verbal memory/learning. On the affected neuropsychologic measures, the groups with the highest exposure averaged scores 5-22% lower than those of the reference groups. Overall, the data revealed generally consistent and coherent associations between two measures of lead exposure and poorer neurobehavioral test performance.

Adult↗
PubMed1993

Work activities and the onset of first-time low back pain among New York City fire fighters.

In a prospective study of first-time low back pain among New York City fire fighters, a total of 115 cases and 109 randomly selected controls were interviewed by telephone between December 1988 and July 1989 to examine the role of recent work activities in the onset of first-time low back pain. After adjusting for known risk factors and off-duty activities, statistically significant high-risk work activities included operating a charged hose inside a building (odds ratio (OR) = 3.26), climbing ladders (OR = 3.18), breaking windows (OR = 4.45), cutting structures (OR = 6.47), looking for hidden fires (OR = 4.32), and lifting objects > or = 18 kg (OR = 3.07). Low-risk activities included connecting hydrants to pumpers (OR = 0.36), pulling booster hose (OR = 0.19), and participating in drills (OR = 0.09) or physical training (OR = 0.16). When further adjusted for exposure to smoke (OR = 13.59), a surrogate for severity of alarms, the ORs associated with high-risk activities were no longer significant. This, however, does not diminish the role of activities in the onset of low back pain. Instead, it suggests an inseparable role for activities and environmental hazards. To examine this, the risk of low back pain was measured within five work zones sequential in time relative to location and distance from a structural fire. The risk gradually increased as the fire fighter moved away from the firehouse (OR = 0.10) and closer to the site of fire (OR = 3.91).

Case-Control Studies↗
PubMed1993

Consistent lack of association between breast cancer and oral contraceptives using either hospital or neighborhood controls.

BACKGROUND: Case-control studies of oral contraceptive use and breast cancer have used neighborhood, population, or hospital controls. METHODS: To determine whether this association differs according to type of controls, interview data from 131 incident cases of breast cancer were compared with those of 189 hospital controls and 182 neighborhood controls Study subjects were white females recruited between 1973 and 1975 from among residents of Baltimore City and County ages 18 to 59 years. RESULTS: Adjusted relative odds of breast cancer related to ever versus never use of oral contraceptives were 1.0 and 0.8, using hospital and neighborhood controls, respectively. Relative odds did not increase proportionally to duration of oral contraceptive use or to progestogen potency. Although few subjects had used oral contraceptives for more than 2 years, almost all pill brands contained more than 49 micrograms of ethinyl estradiol or of mestranol. CONCLUSIONS: Results from the present study do not support the hypothesis that early preparations of oral contraceptives increased breast cancer risk among white women, regardless of whether controls are neighbors of the cases or hospital patients. However, its conclusions cannot be generalized to women who began taking the pill before their first full-term birth or took it for more than 2 years.

Adolescent↗
PubMed1993

Do patients with less than 'echo-perfect' results from mitral valve repair by intraoperative echocardiography have a different outcome?

BACKGROUND: Not all valve repairs for mitral regurgitation (MR) have a perfect result, with no MR on postpump intraoperative echocardiography. Although more than 2+ MR by postpump echocardiography has led to second pump runs for further surgery in 6% to 8% of our patients, those left with 1+ or 2+ MR, traditionally an acceptable result, have not previously been evaluated for clinical outcome. METHODS AND RESULTS: Among 530 patients undergoing mitral repair during 1987 to 1989, 76 patients with 1+ or 2+ MR by postpump intraoperative echocardiography were compared with 76 patients who had equivalent age, sex, left ventricular function, and concomitant surgery but who had no MR by postpump echo. In-hospital morbidity measured by the frequency of respiratory complications, strokes, time in intensive care unit, and duration of hospital stay was actually higher in the patients with no MR after repair. Hospital mortality was not significantly different. There were no significant differences in posthospital mortality (4-year survival estimate of 86% in both groups), thromboembolic events, hospitalizations for heart failure, or functional class, although more patients in the group with no MR after repair were using diuretics. There was a trend toward more reoperations in patients with 1+ or 2+ MR compared with those with no MR by intraoperative echocardiography after repair (4-year estimates of freedom from reoperation, 83% versus 94%; adjusted risk ratio, 3.30). CONCLUSIONS: The presence of 1+ or 2+ MR by postpump intraoperative echocardiography does not confer increased morbidity or mortality. However, the trend toward more reoperations suggests the need for close follow-up for possible recurrence of MR. These data support our low threshold for performing further surgery during second pump runs.

Female↗
PubMed1993

Collagen plug occlusion of Molteno tube shunts.

We report five patients in whom collagen lacrimal plugs were used to temporarily occlude the lumen of Molteno shunts to prevent early postoperative hypotony. Only one eye, with a double plate, developed hypotony and a flat anterior chamber that required reformation. However, in three patients, the collagen plugs did not dissolve and had to be removed surgically to lower the intraocular pressure. Although the semipermeability of collagen is desirable, its unpredictable degradation renders it unsuitable for temporary occlusion of tube shunts. Other biodegradable materials may be more appropriate for this purpose.

Aged↗
PubMed1992

Is there etiologic heterogeneity between upper and lower neural tube defects?

Neural tube defects are thought to arise from two different embryologic mechanisms depending on the level of the defect: neurulation defects associated with anencephaly and upper spina bifida and canalization defects associated with lower spina bifida. To investigate whether the risk profiles of neural tube defect cases differ according to the level of the defect, the authors examined data from the Atlanta Birth Defects Case-Control Study. Cases were infants live- or stillborn from 1968 to 1980 with these defects, and controls were infants without defects randomly selected and frequency matched to cases by race, birth year, and hospital of birth. By multivariate polychotomous logistic regression, 1,186 controls were compared with cases: 145 with anencephaly, 59 with upper spina bifida (cervical/thoracic lesions), and 100 with lower spina bifida (lumbar/sacral lesions). Infant's sex and sibling recurrence of neural tube defects were the only factors for which the case subgroups significantly differed in risk. The risks associated with selected maternal exposures during the first trimester of pregnancy did not differ among the case subgroups. Although these results do not support the concept that upper and lower neural tube defects differ in risks from exogenous factors, differences in sibling recurrence and in risks by sex between the two groups suggest an underlying heterogeneity in genetic susceptibility factors.

Anencephaly↗
PubMed1992

Genetic-epidemiologic study of omphalocele and gastroschisis: evidence for heterogeneity.

On the basis of clinical manifestations, epidemiologic characteristics, and the presence of additional malformations, omphalocele (OM) and gastroschisis (GA) are considered casually and pathogenetically distinct abdominal wall defects. More than 50% of infants with OM have additional defects, but only about 15% of those with GA do. To evaluate whether there is heterogeneity between isolated and multiply affected cases of OM and GA, we analyzed epidemiologic characteristics and familial risks of major defects for 82 OM and 81 GA cases drawn from a population-based study in the Maryland-Washington, DC-Northern Virginia area and born from 1980 through June 1987. We examined year of birth, sex, race, and maternal age distributions after stratifying the infants into isolated and multiple defect groups. We found significant differences in maternal age between cases with isolated OM and GA, but not between cases with GA or OM who had other defects. Using regressive logistic models, we analyzed familial aggregation of birth defects among relatives of infants with OM and GA. An autosomal recessive model of inheritance was found to be the most parsimonious explanation for the families of infants with isolated OM or GA. However, for families of infants with multiple defects, a sporadic or nongenetic model fit best. These findings are not only useful for estimating familial risk of major birth defects, but they also suggest further heterogeneity of infants with OM and GA according to the presence of other malformations.

Abdominal Muscles↗
PubMed1992

Characterization of platelet-derived growth factor and platelet-derived growth factor receptor expression in asbestos-induced rat mesothelioma.

Although altered expression of platelet-derived growth factor (PDGF) is a hallmark of human mesothelioma, expression of PDGF receptors has not been characterized in this cell type. In addition, the expression of this growth factor and its cognate receptor in rodent mesothelioma has not been investigated. In this study, examination of transformed mesothelial cells derived from asbestos-induced rat mesotheliomas revealed that these cells expressed high affinity PDGF receptors (Kd = 0.5 nM) and receptor number was 1.6 x 10(5)/cell. Western analysis using antibodies specific for either the alpha-type or beta-type PDGF receptor and Northern analysis using probes specific for alpha- and beta-type receptor RNA transcripts indicated that these cells expressed beta-type PDGF receptors but that alpha-type receptors could not be detected. However, when the mesothelioma-derived cells were examined for the expression of PDGF, no expression of this growth factor could be detected. The transformed cells expressed no detectable A- or B-chain PDGF RNA transcripts; and using a competitive enzyme immunoassay specific for isoforms containing the B chain of PDGF and a sandwich enzyme-linked immunosorbent assay specific for A-chain-containing isoforms, neither AA, nor AB, nor BB isoforms of this growth factor could be detected in medium conditioned by these cells. The absence of alterations in PDGF expression in rat mesothelioma, in contrast to the data for the human disease, suggests that the production of this growth factor by transformed mesothelial cells may be species specific.

Animals↗
PubMed1992

Biotic and abiotic parameters associated with an epizootic of Coelomomyces punctatus in a larval population of the mosquito Anopheles quadrimaculatus.

Biotic and abiotic parameters associated with an epizootic of the fungus Coelomomyces punctatus in larval populations of the mosquito Anopheles quadrimaculatus were investigated for three mosquito breeding seasons (1986-1988) in two adjacent farm ponds in North Carolina. In the first pond, the prevalence of infected larvae averaged 42% (range 0-85%) for collections made weekly from May 1 to November 20, 1986, but larvae did not occur in this pond in 1987. Infection rates in the adjacent pond, sampled during the mosquito breeding seasons of 1987 and 1988, declined from 10.9% (range 0-27.5%) in 1987 to 2.5% (range 0-14.2%) in 1988. Correlation analyses between the number of female copepods and fungal infection rates in sentinel mosquitoes were significant (P < 0.01) for Acanthocyclops robustus but insignificant for eight other species. Infections obtained in sentinel larvae placed in the ponds for 3 hr intervals indicated that C. punctatus infected larvae around sundown. Infection rates for field-collected larvae increased with the stage of larval development. However, experiments with sentinel larvae showed that early instars were more susceptible to infection than later instars, suggesting that the higher infection rates in late instars resulted from individual larvae being infected by two or more zygotes during larval development. Standard multiple regression analyses, used to determine the relationship between seasonal infection rates and water chemistry, weather variables, and the abundance of early and late instar larvae, showed that the abundance of late instars was the only independent variable common to linear models. The models only accounted for 20 and 9% of the variation in larval infection rates for 1987 and 1988, respectively. These results indicate that of the parameters examined, the seasonal abundance of the copepod, A. robustus, was the most important factor (or variable) correlated with the prevalence of mosquito infection.

Animals↗
PubMed1992

Evidence for the copepods Acanthocyclops robustus and Mesocyclops edax as competent intermediate hosts for Coelomomyces punctatus during an epizootic in a larval population of the mosquito Anopheles quadrimaculatus.

Field and laboratory experiments were conducted during an epizootic of Coelomomyces punctatus (Chytridiomycetes: Blastocladiales) in a population of the mosquito Anopheles quadrimaculatus in a North Carolina farm pond to examine the interactions of several potential copepod hosts with the mosquito and fungus. The diel vertical migratory behavior of the copepod species Acanthocyclops robustus, Eucyclops serrulatus, Macrocyclops albidus, and Mesocyclops edax were monitored in relation to infection rates in sentinel mosquito larvae. Mosquito infection occurred primarily around dusk, the same period during which A. robustus and E. serrulatus were most abundant near the surface of the pond. However, exposure of A. robustus, E. serrulatus, M. albidus, M. edax, Microcyclops varicans, and Paracyclops poppei to fungal meiospores in the laboratory showed that only A. robustus and M. edax were competent intermediate hosts for C. punctatus. Laboratory studies of the diel periodicity of gametangial dehiscence in A. robustus and M. edax infected with C. punctatus revealed that gamete release and zygote formation also occurred around dusk. The combined results of the laboratory and field studies on copepod abundance, susceptibility to infection, and periodicity of gametangial dehiscence suggest that A. robustus was the principal intermediate host for C. punctatus during the epizootic, though it is probable that M. edax also contributed importantly to the overall rate of larval infection.

Animals↗
PubMed1992

Measurement of pharyngeal transit time by electrical impedance tomography.

The feasibility of using electrical impedance tomography (EIT) for measuring pharyngeal transit time has been investigated. Imaging sequences were obtained on the neck in a group of eight healthy subjects when swallowing solutions of different electrical conductivities. The solutions used were aqueous Dioralyte (1.5 S m-1) and tap water (0.04 S m-1). The effects of movement upon the images were large compared with the changes due to the solutions, but these were cancelled by a subtraction technique. The mean value of the EIT pharyngeal transit time parameter was 370 +/- 120 ms. EIT has the advantage that repeated measurements could be performed without fear of hazard in contrast to the established technique of video fluoroscopy which involves ionising

Adult↗
PubMed1992

Ultraviolet radiation and its role in wound pattern documentation.

The history of ultraviolet illumination in photography is discussed. Particular attention is devoted to the forensic aspects of ultraviolet photography as it relates to patterned injury on human skin. The authors discuss the theory underlying ultraviolet illumination of wounds on skin as well as the equipment required for this type of imaging.

Documentation↗
PubMed1991

The effect of sodium deoxycholate and other surfactants on the mucosal surface pH in proximal jejunum or rat.

The mucosal surface pH (acid microclimate) and nucleotide levels of rat proximal jejunum were measured in vivo under various conditions which included exposure to pharmacological agents and to surfactants. Mucosal surface pH was unaffected by sodium nitroprusside, A23187 and amiloride, as was mucosal cGMP content, although amiloride and A23187 reduced cAMP content. In contrast, surfactants elevated the pH of the mucosal surface significantly (P less than 0.001): control value 6.23 +/- 0.02 (n = 12); Lubrol PX 0.8% (v/v) 6.98 +/- 0.02 (n = 5); sodium deoxycholate 2 mmol/l 6.67 +/- 0.04 (n = 5); Triton X-100 0.5% (v/v) 7.41 +/- 0.03 (n = 5). No significant changes in cGMP levels were noted after surfactant treatment, although DOC and Triton X-100 reduced cAMP levels. The ability of higher concentrations of surfactant to elevate the mucosal surface pH beyond neutrality to values similar to plasma pH contrasts with the action of Escherichia coli heat-stable (STa) enterotoxin which at high concentrations could not elevate the mucosal surface pH beyond neutrality. Consistent with the known effects on tight junction permeability, surfactants may act by allowing plasma-like subepithelial fluid to neutralise the microclimate.

Amiloride↗
PubMed1991

Job strain and ambulatory blood pressure profiles.

Occupational characteristics were used to study the role of job stress in the pathogenesis of hypertension. Ambulatory 24-h recordings of blood pressure were made for 161 men with borderline hypertension. From the occupational classification system scores for psychological demands, control, support, physical demands, and occupational hazards were obtained. The results indicated that the ratio between psychological demands and control (strain) was significantly associated with diastolic (but not systolic) blood pressure at night and during work. The association between job strain and diastolic blood pressure at night and during work was greatly strengthened when the subjects with occupations classified as physically demanding were excluded from the analysis. The conclusion was reached that a measure of job strain derived from the occupational classification is useful in predicting variations in diastolic blood pressure levels during sleep and work for men with borderline hypertension.

Adult↗
PubMed1990

Ifosfamide plus doxorubicin in previously untreated patients with advanced soft tissue sarcoma. The EORTC Soft Tissue and Bone Sarcoma Group.

The objective of this phase II trial was to assess the therapeutic activity and toxicity of doxorubicin plus ifosfamide in previously untreated patients with advanced soft tissue sarcoma. Treatment was doxorubicin 50 mg/m2 followed by a 24 h infusion of ifosfamide 5 g/m2 plus mesna 2.5 g/m2 repeated every 3 weeks until disease progression or unacceptable toxicity occurred. Of 203 patients entered, 175 were evaluable for response. The response rate was 35% (95% CI 28-42%), with 9% of the patients achieving a complete remission and 26% a partial remission. The median time to progression was 29 weeks for all evaluable patients, and 67, 40 and 28 weeks for complete and partial responders and patients with stable disease, respectively. The median duration of survival was 58 weeks. Myelosuppression was the dose-limiting toxicity, resulting in leukopenia (WHO grade 3 and 4) in 73% of evaluable treatment courses. Other side-effects were rare and usually well manageable.

Adolescent↗
PubMed1990

Personality and emotional disorder in a community sample of migraine headache sufferers.

To investigate whether individuals who suffer from chronic, severe headaches have more personality abnormalities or emotional disorders than their healthy counterparts, 162 young adults with classical migraine, ascertained by community survey, were compared to matched control subjects without migraine. On the General Health Questionnaire, the prevalence of psychological symptoms among the migraine subjects was 2.5 times the prevalence among the control subjects. The migraine sufferers also had significantly higher scores on the psychoticism (women only), neuroticism, and lie scales of the Eysenck Personality Questionnaire. Frequency of migraine attacks was not related to scores on any of the scales. These results suggest that classical migraine is associated with psychological abnormalities.

Adolescent↗