Biomedical subjects

P Langenberg

Publications and source records attributed to P Langenberg.

71 records · Page 4Linked to original sources

PubMed1989

In vitro stimulation of rat liver retinyl ester hydrolase by ethanol.

Retinyl ester hydrolase (REH), the enzyme which converts retinyl esters to retinol, was partially characterized from whole liver homogenates of rats using an HPLC method with quantitation of retinol product. Optimal results were obtained by incubation of 1 mg of whole homogenate protein with 900 microM all-trans-retinyl palmitate and 275 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate in a 0.1 M Tris-maleate buffer, pH 7.0, for 1 h at 37 degrees C. The enzyme assay proved to be sensitive and reproducible, with an interanimal coefficient of variation of 13% (n = 7). Because ethanol has been shown to mobilize vitamin A from the liver, we tested its effect on REH activity at several concentrations. In concentrations ranging from 0.01 to 0.5 M, ethanol added in vitro caused a concentration related increase in REH activity (from 20 to 86% above baseline activity). This increase was specific to ethanol as acetaldehyde, 1-propanol, and t-butanol either did not change or significantly decreased REH activity over the range of concentrations tested. The range of concentrations of ethanol causing stimulation in our assays was within the range of concentrations seen in the blood of rats after acute ethanol ingestion. Stimulation of REH activity could explain, in part, the well-known effects of ethanol on mobilization of vitamin A from liver stores.

Acetaldehyde↗

PubMed1989

Cigarettes and alcohol as independent risk factors for colonic adenomas.

Healthy adults completed smoking and alcohol consumption questionnaires before colonoscopies, which were performed because of occult blood in the stool or prior barium enema suggesting polyps. Subjects with adenomas at colonoscopy (n = 102) were compared with colonoscopy-negative controls (n = 89). In univariate analyses, age (p less than 0.05), male sex (p less than 0.005), cumulative smoking (p less than 0.0001), and cumulative beer consumption (p less than 0.005) were associated with adenomas. The association of smoking with adenomas was stronger in younger subjects. The association of beer with adenomas was stronger in older subjects. Logistic regression confirmed statistically significant associations of smoking (odds ratio for greater than 40 pack-years = 3.31; confidence intervals 1.41, 7.81) and beer consumption (odds ratio for greater than 40 beer-years = 2.64; confidence intervals 1.10, 6.32) with adenomas. These results suggest that smoking and beer consumption are independent risk factors for colonic adenomas.

Adenoma↗

PubMed1989

Factors in smoking cessation among participants in a televised intervention.

This paper analyzes factors associated with smoking cessation during a 1-year period following a televised, self-help intervention among a sample of smokers who registered and participated in the program. Factors examined include readiness to quit smoking, extent of use of self-help materials, degree of exposure to the televised intervention, and environmental support for quitting from within the smoker's household. Behavioral response immediately following the intervention appeared to persist over the year of observation. Of those who reported stopping smoking immediately following the intervention, fewer than half (about 10% of the total sample that was followed) were continuously abstinent at 12 months. The results indicate that environmental support when the individual is attempting to quit smoking is very important in differentiating between those who successfully quit and those who attempt but fail to sustain their abstinence. The results also suggest that an approach combining television and self-help may reach large populations of smokers and induce a substantial number to quit and remain abstinent.

Chicago↗

PubMed1989

Normal serum response to oral beta-carotene in humans.

This study was performed to determine (1) the normal serum response to a single oral dose of beta-carotene (BC), (2) the effect of meal timing and serum response to meal lipids on serum BC, (3) the effect of administered BC on other serum carotenoids and retinoids, and (4) the relationship of body composition to serum BC response. Subjects consumed one BC dose with a liquid 500 kcal BC-free diet; fasting and hourly venous blood was collected for 8 hours and again at 24 hours. A second liquid BC-free meal was consumed 4 hours post-dosing; this midday meal was omitted in some subjects. Serum BC levels rose and peaked initially at 5 hours, but continued to be absorbed in most subjects, remaining significantly elevated at 24 hours as compared to baseline values (p less than 0.001), independent of BC dose. The area under the BC absorption curve (8-hr AUC) increased linearly with BC dose and correlated positively with peak serum triglycerides (TG) after a meal (n = 26 tests, r = 0.56, p less than 0.003). Omission of the midday meal significantly delayed the initial BC peak to 7 hours (p less than 0.0004). Serum levels of retinol, alpha-carotene, cryptoxanthin, lycopene, and lutein remained unchanged. Serum retinyl esters did not rise in all subjects following BC intake; when it did, retinyl esters rose and peaked concomitantly with BC, but declined within 8 hours. There was no correlation between the initial serum BC, peak BC, 24-hr BC, 8-hr AUC, or peak serum TG and the percentage of body fat. We conclude that: (1) the timing of the serum response to oral BC is independent of dose, (2) the serum BC response is greater in those with a greater serum triglyceride response to meal lipids, (3) BC at the doses given does not alter the levels of other serum carotenoids, and (4) there is no correlation between the serum BC parameters measured and adiposity.

Administration, Oral↗

PubMed1989

Weekly alcohol consumption, cigarette smoking, and the risk of ischemic stroke: results of a case-control study at three urban medical centers in Chicago, Illinois.

To assess the role of current weekly alcohol consumption as a risk factor for cerebral infarction, we administered a pretested questionnaire to 205 middle-aged and elderly acute ischemic stroke patients and 410 outpatient controls matched by age, sex, race, and method of hospital payment. The frequency of hypertension (p less than 0.001) and transient ischemic attacks (p = 0.051), and mean weekly alcohol consumption (p = 0.0286) and mean pack-years cigarette exposure (p = 0.0168) were higher among stroke index cases than controls. For weekly alcohol consumption and mean pack-years cigarette exposure, there was a highly significant dose-response effect. In analyses to assess the possibility of mutual confounding effects of independent variables, we found hypertension and smoking to be independent risk factors for ischemic stroke, while alcohol consumption was not. Separate analyses by sex yielded similar results. We conclude that current weekly alcohol consumption may not be an independent risk factor for cerebral infarction in middle-aged and elderly patients.

Alcohol Drinking↗

PubMed1988

Clinical and angiographic comparison of asymptomatic occlusive cerebrovascular disease.

We compared clinical and arteriographic features in 106 patients with symptomatic unilateral carotid territory occlusive disease to determine the frequency and distribution of occlusive arterial lesions in asymptomatic vessels. Among black patients who were predominantly from Chicago, young, and female, there were fewer transient ischemic attacks and myocardial infarcts, less claudication, and more asymptomatic lesions of the supraclinoid internal carotid artery, anterior cerebral artery stem, and the middle cerebral artery stem. Among white patients predominantly from New England, elderly, and male, there was more frequent and severe occlusive asymptomatic disease at extracranial carotid and vertebral artery sites. Knowledge of the distribution of asymptomatic lesions will help guide evaluation and treatment strategies for patients with occlusive cerebrovascular disease.

Adult↗

PubMed1986

Headache in acute cerebrovascular disease.

Headache features were compared in 51 patients with acute subarachnoid hemorrhage (SAH), 61 with intraparenchymal hemorrhage (IPH), and 160 with ischemic stroke (IS). SAH patients had more sentinel headaches, more onset headaches, and more bilateral and severe onset headaches than patients with IPH or IS. Vomiting with onset headache was more common in SAH and IPH. In stepwise logistic regression analysis, onset headache and vomiting were direct predictors of SAH, but were inversely related to IS. Sentinel headache was not a predictor of underlying stroke mechanism. The data suggest that some headache features are more frequently associated with particular stroke subtypes and that onset headache and vomiting may be important indicators of stroke mechanism.

Brain Ischemia↗

PubMed1981

On the Colton model for clinical trials with delayed observations -- normally-distributed responses.

The Colton model for the choice between two medical treatments is studied, with the additional assumption that there is a time lag between the administration of the treatments and the availability of the responses. Two simple procedures are suggested for dealing with patients who arrive during the waiting period, caused by the lag, between the trial and treatment stages of the model. The relative performance of the procedures in the Bayesian framework is discussed when the responses to the treatments are normally distributed with unknown means and a common known variance.

Bayes Theorem↗

PubMedDate not supplied

A preliminary study of potential human health effects in private residences following chlordane applications for termite control.

A cross-sectional epidemiological investigation of the health status of 261 people from 85 private households previously treated with chlordane for termite control was conducted to assess potential human health effects. When sinusitis, bronchitis, and migraine responses were compared to measured indoor air levels of chlordane in categories designated as low (less than 1 microgram/m3), medium (1-5 micrograms/m3), and high (greater than 5 micrograms/m3), a dose-response relationship was found after controlling individually and simultaneously for age, sex, and smoking. Homes studied in this investigation having a proper chlordane application were observed to have chlordane air levels exceeding acceptable exposure limits.

Adolescent↗

PubMedDate not supplied

Media coverage of women's health issues: is there a bias in the reporting of an association between hormone replacement therapy and breast cancer?

Media coverage of scientific research plays a major role in shaping public opinion and influencing medical practice. When an association is controversial, such as with hormone replacement therapy (HRT) and breast cancer, it is important that a balanced picture of the scientific literature be reported. The objective of this study was to assess whether scientific publications that do and do not support an HRT/breast cancer association were cited in the media in proportions similar to those with which they appear in the scientific literature. Scientific publications reporting on the HRT/breast cancer association published from January 1, 1995, to June 30, 2000, were identified through a systematic Medline search. Media reports from newspapers, magazines, television, and radio that reported on HRT and breast cancer were retrieved from an online database. Investigators independently recorded characteristics of the scientific publications and media reports. A total of 32 scientific publications were identified: 20 (62.5%) concluded there was an increased risk of breast cancer associated with HRT (positive publications), and 12 (37.5%) concluded there was no evidence for an association (null publications). Nearly half (47%) of the scientific publications were not cited by the media. There were 203 media citations of scientific publications: 82% were of positive publications and 18% were of null publications, representing a significant excess of citations of positive publications (p < 0.01). Media coverage of this controversial issue is based on a limited sample of the scientific publications. Moreover, the excess of media citations for positive scientific publications suggests a bias against null scientific publications.

Bias↗

PubMedDate not supplied

Ovarian volume and menopausal status.

OBJECTIVE: The purposes of this study were to (1) examine whether ovarian volume differs by age and menopausal status in healthy women; (2) evaluate whether ovarian volume could be a sensitive and specific predictor of menopausal status; and (3) assess whether ovarian volume is affected by cigarette smoke, oral contraceptives (OCs), and hormone replacement therapy (HRT). DESIGN: Each participant (527 women) completed an extensive in-home interview that assessed age, menopausal status, smoking history, OC use, and HRT use. Each participant also received a transvaginal ultrasound that measured ovarian volume. Geometric means for ovarian volume were compared between premenopausal and postmenopausal women using t tests. Tests for trends were conducted using linear regression analyses. RESULTS: Ovarian volume declined with age (p < or = 0.0001) and also differed by menopausal status; postmenopausal women had smaller ovarian volumes than premenopausal women of the same age (p < or = 0.0001). Ovarian volume was not associated with smoking history or HRT use. However, it was significantly smaller in current users of OCs compared with past users of or those who never used OCs (p < or = 0.0001). Ovarian volume was a sensitive and specific predictor of postmenopausal status. CONCLUSIONS: The data suggest that age, menopausal status, and OC use may be determinants of ovarian volume. They also suggest that ovarian volume may be useful for predicting menopausal status in women.

Adult↗

PubMedDate not supplied

Ovarian volume and antral follicle counts as indicators of menopausal status.

OBJECTIVE: Recent studies suggest that ovarian volume and antral follicle numbers may be sensitive, specific, and early indicators of menopausal status. The accuracy of these markers, however, has not been compared directly to more traditional markers [age and follicle-stimulating hormone (FSH) levels]. Thus, the purpose of this study was to test whether ovarian volume and antral follicle counts are more sensitive and specific markers of menopausal status than age or FSH levels. DESIGN: Premenopausal (n = 34) and postmenopausal (n = 25) women between 40 and 54 years old received a transvaginal ultrasound for determination of ovarian volume and antral follicle numbers, provided blood for measurement of FSH levels, and completed a questionnaire. FSH levels, age, ovarian volume, and antral follicle numbers were compared using t tests. Receiver operating characteristic curves were generated to evaluate the sensitivity and specificity of each marker. RESULTS: Postmenopausal women had significantly higher FSH levels (p < or = 0.0001), smaller ovarian volumes (p < or = 0.002), and fewer antral follicles (p < or = 0.002) than premenopausal women. Ovarian volume and antral follicle numbers had similar sensitivity (27.3-100%) and specificity (3.4-92.9%) in indicating postmenopausal status as FSH levels and age. CONCLUSION: These data suggest that ovarian volume and antral follicle numbers may be useful indicators of menopausal status.

Adult↗

PubMedDate not supplied

Racial differences in the distribution of posterior circulation occlusive disease.

We compared clinical and arteriographic features in 27 white and 24 black patients with symptomatic posterior circulation occlusive disease. The degree of arterial stenosis was measured independently by two examiners at 12 sites within the vertebrobasilar territory. Racial comparisons were made based upon the distribution of extra- and intracranial occlusive lesions and symptomatic sites of the lesions. White patients had significantly more angina pectoris, more lesions of the origin of the left vertebral artery and more high grade lesions of the extracranial vertebral arteries. Black patients had significantly higher mean diastolic blood pressure, more diabetes mellitus, more lesions of the distal basilar artery, more high grade lesions of intracranial branch vessels and more symptomatic intracranial branch disease. Race was found to be the only factor increasing the risk of intracranial posterior circulation occlusive disease. Knowledge of the contribution of race to the distribution of posterior circulation lesions will help guide evaluation and treatment strategies for patients with vertebrobasilar occlusive disease.

Adult↗

PubMedDate not supplied

Is acute alcohol ingestion a risk factor for ischemic stroke? Results of a controlled study in middle-aged and elderly stroke patients at three urban medical centers.

To assess the role of acute alcohol ingestion as a risk factor for cerebral infarction, we administered a pretested questionnaire to 205 middle-aged and elderly acute ischemic stroke patients and 410 outpatient controls matched by age, sex, race, and method of hospital payment. Paired Mantel-Haenszel analysis revealed that alcohol ingestion within 24 (p = 0.07) and 72 (p = 0.001) hours of stroke onset and medical histories of smoking (p less than 0.0001), hypertension (p less than 0.001), and transient ischemic attacks (p = 0.051) were more common among stroke index cases than controls. Matched multiple logistic analysis revealed that both hypertension (p less than 0.05) and smoking (p less than 0.05) were independently associated with stroke, while alcohol consumption was not. In analyses to assess the possibility of mutual confounding effects of independent variables, the effect of alcohol ingestion was lost when adjusting for smoking. We conclude that acute alcohol ingestion is not an independent risk factor for cerebral infarction in middle-aged and elderly patients. The apparent association between alcohol ingestion and ischemic stroke may be the result of the confounding effects of smoking.

Aged↗

PubMedDate not supplied

Impaired insight in Alzheimer's disease.

We studied insight into illness in 41 patients with probable Alzheimer's disease. An impaired insight score was developed by measuring discrepancies between patient report and caregiver report on standard instruments of activities of daily living. Insight was more impaired in subjects with greater dementia severity and subjects with paranoid delusions. In a multivariate analysis, the best neuropsychological predictors of impaired insight were the Continuous Performance Test and the Visual Reproduction Test. We speculate that the impaired insight of Alzheimer's disease has two components: confabulation reflecting prefrontal dysfunction and anosognosia reflecting right-hemisphere dysfunction.

Activities of Daily Living↗

PubMedDate not supplied

Factors associated with attendance in a voluntary nutrition education program.

PURPOSE: This paper examines factors associated with attendance in a National Cancer Institute-funded randomized trial of nutrition education to increase fruit and vegetable consumption among women served by the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). SETTING: The study took place at 16 WIC sites in Maryland. SUBJECTS: The participants were 1528 women who were enrolled in WIC or who had children enrolled in WIC, were > or = 18 years of age, and planned to continue enrollment at that WIC site for at least 6 months (68% of eligible women approached agreed to participate). INTERVENTION: Women received personal invitations, letters, and telephone reminders from peer educators encouraging their attendance at three bimonthly nutrition sessions. MEASURES: Demographic data were collected in a baseline survey. Attendance data and telephone and address changes were also collected. The postintervention survey included a question regarding reasons for nonattendance. Focus groups were also held to ascertain reasons for attendance or nonattendance. Chi-square tests of trend and multiple logistic regression, adjusted for within-site correlation, were used in statistical analyses. RESULTS: Fifty-four percent of enrollees attended at least one session. Multiple logistic regression analysis showed increased odds of attending with higher age, breast-feeding, and/or knowledge of the recommendation to eat five or more servings of fruits and vegetables daily. There were decreased odds of attending for pregnant women who already had children. There were nonsignificant trends toward decreased attendance among unmarried women compared with married women and among blacks compared with nonblacks. Reasons given for nonattendance included withdrawal from WIC, moving, conflicting activities, negative feelings about nutrition education, and lack of transportation or child care. CONCLUSIONS: The results suggest that numerous barriers hinder participation in nutrition programs aimed at low-income women. These barriers should be considered by health care professionals when planning intervention programs. Overcoming these barriers presents a major challenge.

Adolescent↗

PubMedDate not supplied

Prospective study of the effect of safety belts on morbidity and health care costs in motor-vehicle accidents.

To assess the impact of safety belt use on the extent of injuries sustained in motor-vehicle accidents and the incurred health care costs, 1364 patients were prospectively evaluated at four Chicago-area hospitals. Of these, 791 (58%) were wearing a safety belt whereas 573 (42%) were not. The mean injury severity score for safety belt wearers was 1.8 +/- 0.07 vs 4.51 +/- 0.31 in those not wearing a safety belt. Only 6.8% of safety belt wearers required admission vs 19.2% of those not wearing a safety belt. Restrained occupants incurred mean charges of $534 +/- $67 compared with $1583 +/- $201 in unrestrained occupants. Thus, safety belt wearers had a 60.1% reduction in severity of injury, a 64.6% decrease in hospital admissions, and a 66.3% decline in hospital charges. Our findings demonstrate the significant societal burden of nonuse of safety belts in terms of morbidity and the costs of medical care.

Accidents, Traffic↗