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Biomedical subjects

W F Stewart

Publications and source records attributed to W F Stewart.

At least 37 records · Page 2Linked to original sources
PubMed2001

Associations of tibia lead, DMSA-chelatable lead, and blood lead with measures of peripheral nervous system function in former organolead manufacturing workers.

BACKGROUND: The goals of the present study were to compare and contrast associations of blood lead, DMSA-chelatable lead, current tibia lead, and back-extrapolated "peak" tibia lead with four peripheral nervous system (PNS) sensory and motor function measures in older males with past exposure to organic and inorganic lead. METHODS: Data were collected from former organolead manufacturing workers with an average of 16 years since last occupational lead exposure. Current tibia lead levels were measured by (109)Cd x-ray fluorescence. Sensory pressure thresholds (index and pinky fingers) and pinch and grip strength were measured with the Pressure-Specified Sensory Device (PSSD). RESULTS: In adjusted analyses, none of the four lead biomarkers was associated with sensory pressure threshold of the index finger or pinch or grip strength. In contrast, all four biomarkers were associated (P < or = 0.10) with pressure threshold of the pinky finger. The final linear regression models accounted for a small proportion of the variance in the sensory (1-3%) and motor measures (10-21%). CONCLUSIONS: This study found no strong association between lead biomarkers and selected PNS sensory or motor function measures among former organolead manufacturing workers with no recent occupational exposure to lead. Previously reported CNS findings in this cohort suggest that the PNS may be less sensitive to the chronic toxic effects of lead in this dose range among adults. It is also possible that the PNS has a greater capacity for repair than does the CNS, or that the PNS measures were less sensitive for detection of lead-related health outcomes than were the CNS measures.

Adult↗
PubMed2001

Epidemiology of migraine.

Migraine is a highly prevalent headache disorder that has a substantial impact on the individual and society. Over the past decade, substantial advances in research have increased understanding of the pathophysiology, diagnosis, epidemiology, and treatment of the disorder. This article reviews data on the epidemiology and impact of migraine. It also highlights the increased awareness of migraine, citing examples from the popular media and the Internet.

Humans↗
PubMed2001

Health-related quality of life among adults with symptoms of overactive bladder: results from a U.S. community-based survey.

OBJECTIVES: To assess, by means of a survey, the impact of the symptoms of overactive bladder (urinary frequency, urgency, and urge incontinence) on the quality of life in a community-based sample of the U.S. population. METHODS: A telephone survey was conducted in the United States among an age and sex-stratified sample of 4896 noninstitutionalized adults 18 years of age and older. From the responses to the telephone survey, a total of 483 individuals with symptoms of overactive bladder and 191 controls completed a mailed follow-up questionnaire to assess their quality of life using the Medical Outcomes Study Short-Form 20. RESULTS: After adjustment for age, sex, and the use of medical care, the greatest differences in the quality-of-life scores between the patients with incontinent overactive bladders and the controls were in the health perception (17.6 points; P <0.001) and role functioning (13.0 points; P <0.001) scales. Those with an overactive bladder with the symptoms of frequency or urgency, or both, but without incontinence, also had significantly lower scores than did the controls in mental health (P = 0.026), health perception (P = 0.01), and bodily pain (P = 0.016). CONCLUSIONS: These data indicate that individuals with an overactive bladder experience decrements in their quality of life relative to community controls. An important new finding from this study is that individuals with an overactive bladder, even without demonstrable urine loss, also have a poorer quality of life than that of controls.

Adult↗
PubMed2001

Coping strategies and health care-seeking behavior in a US national sample of adults with symptoms suggestive of overactive bladder.

BACKGROUND: Although millions of individuals have symptoms suggestive of overactive bladder (OAB), few ever seek or receive medical treatment for their condition. OBJECTIVE: The purpose of this study was to describe coping strategies and health care-seeking behavior in a community-based sample of adults with symptoms suggestive of OAB. METHODS: A cross-sectional household telephone survey of an age- and sex-stratified sample of adults was conducted. The survey consisted of general health-related questions as well as questions related to OAB symptoms. A total of 4896 adults completed the interview Respondents were considered to have OAB if they reported > or = 1 symptom of urinary urgency, frequency, or urge incontinence. A follow-up questionnaire was then mailed to a subsample of the telephone interview respondents. The mailed questionnaire contained questions related to type and severity of OAB symptoms, coping strategies, medical care/treatment, feelings/beliefs about OAB, and quality of life. Half of the phone respondents with urinary incontinence (n = 638) and a random sample of all other phone respondents received the mailed questionnaire (n = 873); 1,034 questionnaires were returned. RESULTS: Of the respondents with OAB, 69.6% tried > or = 1 nonmedical coping strategy. Respondents with incontinent OAB were significantly more likely than those with continent OAB or those with no OAB (controls) to use nonmedical coping strategies (incontinent OAB, 76.1%; continent OAB, 59.0%; controls, 31.9%; P < 0.001). Fewer than half of the respondents with OAB (43.5%) had spoken with a provider about OAB in the previous 12 months. Medical consultation was associated with sex, type and severity of OAB, number of nonmedical coping strategies tried, number of OAB information sources consulted, inclination to try new OAB medications, and feelings/beliefs about OAB. In 90% of patient-provider discussions about OAB, the patient initiated the topic. CONCLUSIONS: Individuals manage symptoms suggestive of OAB primarily by using nonmedical coping strategies rather than consulting health care providers. Results of this study support the need for improved clinical recognition of OAB and increased patient-provider communication about this condition.

Adaptation, Psychological↗
PubMed2001

Epidemiology and economic impact of migraine.

Migraine is a very common disorder, affecting about 11% of adult populations in Western countries. Prevalence is highest during the peak productive years--between the ages of 25 and 55. The prevalence is higher in females than males at all post-pubertal ages, but the sex ratio varies with age. In the United States, migraine prevalence is higher in those with low income or education, perhaps because migraine interferes with work and school. Most migraineurs mane their headaches without conventional medical advice and generally treat their attacks with over-the-counter medication. The indirect costs of migraine greatly outweigh the cost of treatment, creating opportunities for cost-effective intervention. The public health burden of migraine is substantial due to its high prevalence and prominent temporary disability. The widespread disability produced by migraine is an important target for treatment.

Age Factors↗
PubMed2001

Development and testing of the Migraine Disability Assessment (MIDAS) Questionnaire to assess headache-related disability.

The MIDAS Questionnaire was developed to assess headache-related disability with the aim of improving migraine care. Headache sufferers answer five questions, scoring the number of days, in the past 3 months, of activity limitations due to migraine. The internal consistency, test-retest reliability, and validity (accuracy) of the questionnaire were assessed in separate population-based studies of migraine sufferers. In addition, the face validity, ease of use, and clinical utility of the questionnaire were evaluated in a group of 49 physicians who independently rated disease severity and need for care in a diverse sample of migraine case histories. The test-retest Pearson correlation coefficient for the total MIDAS score was approximately 0.8. The MIDAS score was valid when compared with a reference diary-based measure of disability; the overall correlation between MIDAS and the diary-based measure was 0.63. The MIDAS score was also correlated with physicians' assessments of need for medical care (r = 0.69). From studies completed to date, the MIDAS Questionnaire has been shown to be internally consistent, highly reliable, valid, and correlates with physicians' clinical judgment. These features support its suitability for use in clinical practice. Use of the MIDAS Questionnaire may improve physician-patient communication about headache-related disability and may favorably influence health-care delivery for migraine patients.

Disability Evaluation↗
PubMed2001

Characterization of toxicokinetics and toxicodynamics with linear systems theory: application to lead-associated cognitive decline.

We present a theoretical approach to analysis of toxicokinetics and toxicodynamics using linear systems theory. In our approach, we define two impulse response functions that characterize the kinetic behavior of an environmental agent in the body and the dynamic time-course behavior of its effect on the body. This approach provides a formalism for understanding the relation among exposure, dose, and cumulative biologically effective dose and for understanding the implications of an effect time-course on cross-sectional and longitudinal data analyses. We use lead-associated cognitive decline as a specific example where the approach may be applied.

Cognition Disorders↗
PubMed2001

Associations of blood pressure and hypertension with lead dose measures and polymorphisms in the vitamin D receptor and delta-aminolevulinic acid dehydratase genes.

Evidence suggests that lead and selected genes known to modify the toxicokinetics of lead--namely, those for the vitamin D receptor (VDR) and delta-aminolevulinic acid dehydratase (ALAD)--may independently influence blood pressure and hypertension risk. We report the relations among ALAD and VDR genotypes, three lead dose measures, and blood pressure and hypertension status in 798 Korean lead workers and 135 controls without occupational exposure to lead. Lead dose was assessed by blood lead, tibia lead measured by X-ray fluorescence, and dimercaptosuccinic acid (DMSA)-chelatable lead. Among lead workers, 9.9% (n = 79) were heterozygous for the ALAD(2) allele, and there were no ALAD(2) homozygotes; 11.2% (n = 89) had at least one copy of the VDR B allele, and 0.5% (n = 4) had the BB genotype. In linear regression models to control for covariates, VDR genotype (BB and Bb vs. bb), blood lead, tibia lead, and DMSA-chelatable lead were all positive predictors of systolic blood pressure. On average, lead workers with the VDR B allele, mainly heterozygotes, had systolic blood pressures that were 2.7-3.7 mm Hg higher than did workers with the bb genotype. VDR genotype was also associated with diastolic blood pressure; on average, lead workers with the VDR B allele had diastolic blood pressures that were 1.9-2.5 mm Hg higher than did lead workers with the VDR bb genotype (p = 0.04). VDR genotype modified the relation of age with systolic blood pressure; compared to lead workers with the VDR bb genotype, workers with the VDR B allele had larger elevations in blood pressure with increasing age. Lead workers with the VDR B allele also had a higher prevalence of hypertension compared to lead workers with the bb genotype [adjusted odds ratio (95% confidence interval) = 2.1 (1.0, 4.4), p = 0.05]. None of the lead biomarkers was associated with diastolic blood pressure, and tibia lead was the only lead dose measure that was a significant predictor of hypertension status. In contrast to VDR, ALAD genotype was not associated with the blood pressure measures and did not modify associations of the lead dose measures with any of the blood pressure measures. To our knowledge, these are the first data to suggest that the common genetic polymorphism in the VDR is associated with blood pressure and hypertension risk. We speculate that the BsmI polymorphism may be in linkage disequilibrium with another functional variant at the VDR locus or with a nearby gene.

Adolescent↗
PubMed2001

Migraine's impact today. Burden of illness, patterns of care.

Migraine is a common disorder that causes severe headaches and associated nausea, photophobia, phonophobia, and temporary disability. Though the pain and other symptoms of migraine can be effectively managed, the condition remains underdiagnosed and undertreated. In this article, Drs Lipton, Stewart, Reed, and Diamond consider the scope and distribution of the migraine problem and the current patterns of care in the United States.

Activities of Daily Living↗
PubMed2001

Associations of lead biomarkers and delta-aminolevulinic acid dehydratase and vitamin D receptor genotypes with hematopoietic outcomes in Korean lead workers.

OBJECTIVES: This study compares and contrasts associations of dimercaptosuccinic acid (DMSA)-chelatable lead, tibia lead, and blood lead with five hematopoietic outcomes and evaluates the effect modification of these relations by polymorphisms in the delta-aminolevulinic acid dehydratase (ALAD) and vitamin D receptor (VDR) genes. METHODS: A cross-sectional study of 798 lead workers and 135 unexposed referents was performed. RESULTS: The DMSA-chelatable lead, tibia lead, and blood lead levels ranged in the lead (Pb) workers from 4.8 to 2103 g, -7 to 338 g Pb/g bone mineral, and 4 to 86 g/dl, respectively. The mean of the hemoglobin, hematocrit, zinc protoporphyrin (ZPP), and urinary (ALAU) and plasma (ALAP) delta-aminolevulinic acid levels of the lead workers were 14.2 (SD 1.4) g/dl, 42.4 (SD 4.4)%, 80.2 (SD 63.5) g/dl, 2.1 (SD 3.7) mg/l, and 17.7 (20.6) g/ml, respectively. After adjustment for the covariates, tibia lead was associated with all five hematopoietic outcomes, while blood lead and DMSA-chelatable lead were associated only with ZPP, ALAP, and ALAU. A comparison of the regression coefficients, total model adjusted R2 values, and delta R2 values revealed that blood lead was the best predictor of ZPP, ALAP, and ALAU. Only tibia lead was significantly associated with hemoglobin and hematocrit levels, but the additional variance explained by tibia lead was (<1%). No clear effect modification of the relations between the lead biomarkers and hematopoietic outcomes studied was caused by ALAD or VDR genotype. CONCLUSIONS: Lead must have a chronic, cumulative effect on hemoglobin and hematocrit levels, and any speculated mechanism cannot merely involve short-term plasma or target organ lead levels.

Adolescent↗
PubMed2001

Intraneuronal abeta-amyloid precedes development of amyloid plaques in Down syndrome.

CONTEXT: Down syndrome patients who live to middle age invariably develop the neuropathologic features of Alzheimer disease, providing a unique situation in which to study the early and sequential development of these changes. OBJECTIVE: To study the development of amyloid deposits, senile plaques, astrocytic and microglial reactions, and neurofibrillary tangles in the brains of young individuals (<30 years of age) with Down syndrome. METHODS: Histologic and immunocytochemical study of a series of autopsy brains (n = 14, from subjects aged 11 months to 56 years, with 9 subjects <30 years) examined at the Office of the Chief Medical Examiner of the State of Maryland and The Johns Hopkins Hospital. RESULTS: The principal observations included the presence of intraneuronal Abeta immunostaining in the hippocampus and cerebral cortex of very young Down syndrome patients (preceding the extracellular deposition of Abeta) and the formation of senile plaques and neurofibrillary tangles. CONCLUSIONS: We propose the following sequence of events in the development of neuropathologic changes of Alzheimer disease in Down syndrome: (1) intracellular accumulation of Abeta in neurons and astrocytes, (2) deposition of extracellular Abeta and formation of diffuse plaques, and (3) development of neuritic plaques and neurofibrillary tangles with activation of microglial cells.

Adolescent↗
PubMed2001

Clinical utility of an instrument assessing migraine disability: the Migraine Disability Assessment (MIDAS) questionnaire.

OBJECTIVE: We evaluated the agreement between Migraine Disability Assessment (MIDAS) scores and independent physician judgments about pain, disability, and treatment needs based on patient medical histories. BACKGROUND: The MIDAS questionnaire measures headache-related disability as lost time due to headache from paid work or school, household work, and nonwork activities. METHODS: Twelve histories from patients with migraine were presented to 49 primary and specialty care physicians unaware of the MIDAS scores. Physicians graded each patient for pain level (mild, moderate, or severe), level of disability (none, mild, moderate, or severe), and need for medical care (from 0 [lowest] to 100 [highest]). Physicians also identified MIDAS scores they associated with different degrees of disability and with the urgency to prescribe an effective treatment during the first consultation. RESULTS: The physicians' perceptions of the need for medical care based on medical histories correlated with the MIDAS score (r =.69). Estimates of pain and disability by physicians were directly correlated with increasing MIDAS scores. Using the physicians' clinical judgments, the overall MIDAS score was categorized into four grades of increasing severity. CONCLUSIONS: Scores on the MIDAS are highly correlated with physician judgments regarding patients' pain, disability, and need for medical care. These findings support the potential utility of the MIDAS questionnaire in clinical practice.

Disability Evaluation↗
PubMed2000

Menstrual cycle and headache in a population sample of migraineurs.

BACKGROUND: Migraine is three times more common in women than men. There is a clinical impression that migraines are more common and severe around the time of menses. OBJECTIVES: To determine 1) the distribution of headache attacks by day of the menstrual cycle in women with migraine, 2) if the excess occurrence varies by headache type, and 3) if headache features differ by time in the menstrual cycle. METHODS: In a population-based sample, 81 menstruating women with clinically diagnosed migraine were enrolled in a 98-day diary study and completed a total of 7219 diary days. The daily diary was used to record the occurrence of menses, headache days, and, on days with headache, associated headache features (i.e., symptoms, quality-of-pain, attack duration, pain intensity, and disability at work, household work, and nonwork activities). RESULTS: An excess risk of headache occurred perimenstrually and was highest on days 0 and 1 of the cycle (day 0 being the first day of menses). A significantly elevated risk of headache on days 0 and 1 was observed for migraine without aura (OR 2.04; 95% CI 1.49, 2.81) and for tension-type headache (OR 1.67; 95% CI 1.24, 2.25). Elevated risks were also observed in the 2 days before onset of menses for migraine without aura (OR 1.80; 95% CI 1.40, 2.30). A significantly lower risk was observed around the time of ovulation for all headaches (OR 0.44; 95% CI 0.27, 0.72). Few significant differences were observed in headache features (i.e., pain intensity, disability score, symptom score, headache duration) by day of the cycle overall or by headache type. Pain intensity was slightly greater for migraine headaches during the first 2 days of menses. CONCLUSIONS: Attacks of migraine without aura, but not migraine with aura, were more likely to occur 2 days before onset of menses and on the first 2 days of menses. This study does not support the clinical notion that headaches, regardless of type, are more severe during the perimenstrual period compared to other times in the cycle. Although migraine headaches are significantly more painful during the first 2 days of menses, differences are small.

Adolescent↗
PubMed2000

Past adult lead exposure is associated with longitudinal decline in cognitive function.

OBJECTIVE: To determine whether adults with past exposure to neurotoxicants have progressive declines in cognitive function years after exposure has ceased, and whether tibia lead is a predictor of the magnitude of change. METHODS: A total of 535 former organolead manufacturing workers with a mean age of 55.6 years, a mean duration of 16 years since last occupational lead exposure, and low blood lead levels at the first study visit and 118 controls were evaluated with neurobehavioral tests two to four times over 4 years. "Peak" tibia lead levels, estimated from current levels measured by X-ray fluorescence, were used to predict changes in cognitive function over time. RESULTS: In former lead workers, peak tibia lead ranged from -2.2 to 98.7 microg Pb/g bone mineral. Compared to controls, former lead workers performed worse over time for three tests of visuo-constructive ability and verbal memory and learning (p < 0.05). In former lead workers, peak tibia lead predicted declines for six tests of verbal memory and learning, visual memory, executive ability, and manual dexterity (p < 0.05 for four tests and < 0.10 for two additional tests). On average, for these six tests, an increase of 15.7 microg/g of peak tibia lead was equivalent in its effects on annual test decline to 5 more years of age at baseline. CONCLUSIONS: These are the first data to suggest that cognitive function can progressively decline due to past occupational exposures to a neurotoxicant.

Adult↗
PubMed2000

Migraine, quality of life, and depression: a population-based case-control study.

OBJECTIVE: This study reports on the influence of migraine and comorbid depression on health-related quality of life (HRQoL) in a population-based sample of subjects with migraine and nonmigraine controls. METHODS: Two population-based studies of similar design were conducted in the United States and United Kingdom. A clinically validated, computer-assisted telephone interview was used to identify individuals with migraine, as defined by the International Headache Society, and a nonmigraine control group. During follow-up interviews, 389 migraine cases (246 US, 143 UK) and 379 nonmigraine controls (242 US, 137 UK) completed the Short Form (SF)-12, a generic HRQoL measure, and the Primary Care Evaluation of Mental Disorders, a mental health screening tool. The SF-12 measures HRQoL in two domains: a mental health component score (MCS-12) and a physical health component score (PCS-12). RESULTS: In the United States and United Kingdom, subjects with migraine had lower scores (p < 0.001) on both the MCS-12 and PCS-12 than their nonmigraine counterparts. Significant differences were maintained after controlling for gender, age, and education. Migraine and depression were highly comorbid (adjusted prevalence ratio 2.7, 95% CI 2.1 to 3. 5). After adjusting for gender, age, and education, both depression and migraine remained significantly and independently associated with decreased MCS-12 and PCS-12 scores. HRQoL was significantly associated with attack frequency (for MCS-12 and PCS-12) and disability (MCS-12). CONCLUSIONS: Subjects with migraine selected from the general population have lower HRQoL as measured by the SF-12 compared with nonmigraine controls. Further, migraine and depression are highly comorbid and each exerts a significant and independent influence on HRQoL.

Adult↗
PubMed2000

Headache and major depression: is the association specific to migraine?

OBJECTIVE: To examine the relationship between migraine and major depression, by estimating the risk for first-onset major depression associated with prior migraine and the risk for first migraine associated with prior major depression. We also examined the extent to which comorbidity with major depression is specific to migraine or is observed in other severe headaches. METHODS: Representative samples of persons 25 to 55 years of age with migraine or other severe headaches (i.e., disabling headaches without migraine features) and controls with no history of severe headaches were identified by a telephone survey and later interviewed in person to ascertain history of common psychiatric disorders. RESULTS: Lifetime prevalence of major depression was approximately three times higher in persons with migraine and in persons with severe headaches compared with controls. Significant bidirectional relationships were observed between major depression and migraine, with migraine predicting first-onset depression and depression predicting first-onset migraine. In contrast, persons with severe headaches had a higher incidence of first-onset major depression (hazard ratio = 3.6), but major depression did not predict a significantly increased incidence of other severe headaches (hazard ratio = 1.6). CONCLUSIONS: The contrasting results regarding the relationship of major depression with migraine versus other severe headaches suggest that different causes may underlie the co-occurrence of major depression in persons with migraine compared with persons with other severe headaches.

Adult↗
PubMed2000

Abdominal pain, bloating, and diarrhea in the United States: prevalence and impact.

The prevalence and impact of abdominal pain, bloating, and diarrhea in the adult US population are largely unknown. We conducted a national, cross-sectional, telephone survey of US households to provide estimates of the frequency, duration, severity, and impact of specific digestive symptoms during the previous month. A total of 2510 subjects completed interviews (70.7% response rate). Among the respondents, 1017 (40.5%) reported one or more digestive symptoms within the month before the interview, including abdominal pain or discomfort 21.8%, bloating or distension 15.9%, and diarrhea or loose stools 26.9%. Women were more likely than men to report abdominal pain or discomfort (24.4% vs 17.5%) and bloating or distension (19.2% vs 10.5%), but not diarrhea or loose stools (27.1% vs 26.7%). Symptoms were less common among those > or =60 years of age. More than 65% of respondents rated symptoms as moderate or severe in intensity, and the majority reported limitations in daily activities. We conclude that digestive symptoms are more common than previously recognized and have a significant impact.

Abdominal Pain↗