Biomedical subjects

P Langenberg

Publications and source records attributed to P Langenberg.

At least 55 records · Page 3Linked to original sources

PubMed1993

Pulmonary hemorrhage and exogenous surfactant therapy: a metaanalysis.

A metaanalysis of surfactant clinical trials was carried out to assess whether or not an association exists between exogenous surfactant therapy and pulmonary hemorrhage. Trials that reported the pulmonary hemorrhage occurrence (group 1) and those that did not (group 2) were analyzed. Thirty-three treatment strategies were tested in 29 publications from 1980 through 1992. Eleven of these were group 1 trials, which reported a 3% overall incidence of pulmonary hemorrhage. The rates were significantly higher in both the treated and the control groups of natural surfactant trials than in synthetic surfactant trails (5.87% and 5.36% in the natural surfactant trials vs 2.51% and 1.04% in the synthetic surfactant trials, respectively). The pooled estimate of relative risk for pulmonary hemorrhage with any surfactant therapy was 1.47 (95% confidence interval 1.05, 2.07; p < 0.05). Logistic regression modeling revealed that the nature of surfactant, treatment strategy, and lower mean birth weight had a significant influence on the relative risk of pulmonary hemorrhage; a similar trend was seen with higher mortality rates. Variation in the rates of patent ductus arteriosus did not have an independent effect on the estimated pulmonary hemorrhage risk. Most group 2 trials were published before 1990, and the median total sample size was 73, compared with 402 for the group 1 trials (p < 0.05), most of which were published in the 1990s. In 10 (50%) of 20 group 2 trials, pulmonary hemorrhage data were collected methodically, in comparison with all group 1 trials, most of which collected data prospectively. We conclude that pulmonary hemorrhage is a rare complication of respiratory distress syndrome. An awareness of the possible association of pulmonary hemorrhage with surfactant use in later trials and the differences in definitions and reporting practices probably explain variations in the reported incidence among the trials. The risk of pulmonary hemorrhage increases slightly, on an average of 47%, with any surfactant therapy. This increased risk is small compared with the documented benefits of surfactant therapy in respiratory distress syndrome.

Hemorrhage↗

PubMed1993

The socioeconomic correlates of hysterectomies in the United States.

The purpose of this study was to examine the relationship between incidence of prior hysterectomy and education, income, and race. Data concerning previous hysterectomy and socioeconomic information were collected from 12,465 women 18 years or older as part of the Behavioral Risk Factor Surveillance System conducted in 16 states in 1988. The results indicate that women with less education and lower incomes were more likely to have had a hysterectomy. Race was not related to hysterectomy rate.

Adolescent↗

PubMed1992

Hormone levels in vegetarian and nonvegetarian teenage girls: potential implications for breast cancer risk.

Between September 1984 and June 1985, a total of 75 adolescent girls, 35 vegetarians residing in a Seventh-Day Adventist school and 40 nonvegetarians residing in a private non-Adventist boarding school, underwent measurement of their plasma hormone levels in the follicular and luteal phase of their menstrual cycles as well as dietary intake measured by 3-day food records, medical history, height, and weight. There were no significant differences between vegetarians and nonvegetarians in average age of the girls, weight, body mass index, age at menarche, years since the onset of menstruation, or percentage of girls with ovulatory cycles. Vegetarian girls had significantly higher levels of log follicular estradiol [2.00 +/- 0.27 (SD) versus 1.85 +/- 0.27 pg/ml, P less than or equal to 0.05] and luteal dehydroepiandrosterone sulfate (DHS) (1.88 +/- 0.71 versus 1.45 +/- 0.80 microgram/ml, P less than or equal to 0.05) than nonvegetarian girls. Follicular DHS was higher in vegetarians than in nonvegetarians (1.72 +/- 0.79 versus 1.45 +/- 0.95 microgram/ml), but the difference was not significant. The differences in follicular and luteal DHS, but not the difference in log estradiol, were significant (P less than or equal to 0.05) after controlling for ovulation, smoking, and alcohol intake with multivariable regression analysis. There were no significant differences in testosterone or in percentage free estradiol levels between vegetarians and nonvegetarians. Smoking was significantly associated with follicular and luteal DHS and with percentage free follicular estradiol, while alcohol use was significantly and inversely associated with percentage free follicular estradiol after controlling for other variables. The implications for breast cancer risk are discussed.

Adolescent↗

PubMed1992

How much 'better' is good enough? The magnitude of treatment effect in clinical trials.

OBJECTIVES: Among the various factors required to calculate sample size for clinical trials, the magnitude of treatment effect anticipated is an important component. The objective of this report is to present some of the complexities involved in selection of treatment effect size in clinical trials. As a framework for discussion, an analysis of published reports related to surfactant therapy was carried out. DESIGN: Twenty-one consecutive exogenous surfactant trials for neonatal respiratory distress syndrome were analyzed. The "Methods" sections were reviewed for evaluating various components of sample size calculation, including the anticipated treatment effect size. RESULTS: Sixteen (76%) of the 21 reports provided a description of sample size calculations, and 12 of these gave some reasons for the choice of the anticipated treatment effect size. Expressed as percent change, the median treatment effect from intervention anticipated by the investigators was 50% (range, 15% to 90%), with a positively skewed distribution. The actual median percent reduction in adverse events from treatment (as compared with baseline) was 36% (range, 75% reduction to 5% excess). When the treatment effect was expressed as difference in adverse event rate, in the 14 (of 16) trials that could be analyzed, the median observed reduction in adverse events (death, bronchopulmonary dysplasia, or occurrence of respiratory distress syndrome) was 14.5% (range, 52% reduction to 2% excess). All trials except one concluded, however, that the intervention was effective, mostly based on additional subgroup calculations. CONCLUSIONS: Researchers often select sample sizes capable of detecting only large treatment effects, thus risking type II error, although sometimes a much smaller effect could be clinically important. While pragmatic considerations must be considered during the design of randomized clinical trials, researchers ought to present a rationale for anticipating a given magnitude of treatment effect in their sample size calculations. It may be possible to consider innovative trial designs that help determine the most appropriate treatment choice with the least possible sample size.

Confidence Intervals↗

PubMed1992

Insulin-like growth factor I and low-density-lipoprotein cholesterol in women during high- and low-fat feeding.

In vitro studies suggest that insulin-like growth factor I (IGF-I) may modulate hepatic production and peripheral utilization of lipoproteins. We measured blood concentrations of IGF-I; total, high-density-lipoprotein, and low-density-lipoprotein (LDL) cholesterol; and apolipoproteins in 18 women with above average cholesterol after high- and low-fat diet periods. Total cholesterol fell 6% (P less than 0.02) during the low-fat diet because of reduced concentrations of LDL cholesterol (P less than 0.01). Serum concentrations of IGF-I were inversely correlated with total and LDL cholesterol and apolipoprotein B during both high-fat (r = -0.676, P less than 0.005; r = -0.745, P less than 0.001; and r = -0.504, P less than 0.04, respectively) and low-fat (r = -0.656, P less than 0.005; r = -0.757, P less than 0.001; and r = -0.695, P less than 0.001, respectively) diets. IGF-I increased with reduced fat intake in obese subjects only. Thus, IGF-I may contribute to the regulation of LDL cholesterol in mildly hypercholesterolemic women but may not mediate the beneficial response to reduced fat intake.

Adult↗

PubMed1992

Differential reduction of plasma cholesterol by the American Heart Association Phase 3 Diet in moderately hypercholesterolemic, premenopausal women with different body mass indexes.

The ability of a low-fat, low-cholesterol diet to improve the risk-factor profiles of moderately hypercholesterolemic, premenopausal women was evaluated. Nineteen women were fed a typical American diet for 1 mo, after which a low-fat diet consisting of 21% of total energy (en%) as fat, 59 en% carbohydrates, 19 en% protein, and 96 mg cholesterol/d (P:S 1.8) was given. After 5 months, total and low-density lipoprotein (LDL) cholesterol was decreased by 7% and 11%, respectively, and total triglycerides increased by approximately 30%. High-density-lipoprotein (HDL) cholesterol was decreased by 12% at month 2 and 5% at month 5 (P less than 0.05). Although HDL2 cholesterol decreased progressively throughout the diet period to -35% by month 5, HDL3 cholesterol, which decreased to -5% at month 1, increased to +7% by month 5. Of the plasma apolipoproteins only apo A-II was altered (+15%) by the diet. Body mass index correlated to baseline values and affected response to diet; only the leanest women had significant decreases in total, LDL, and HDL2 cholesterol in response to the low-fat diet.

Adult↗

PubMed1992

A treatment program for adolescents with phenylketonuria.

A treatment program for adolescents with phenylketonuria (PKU), incorporating education, goal-setting, self-monitoring, contracts, and rewards, was evaluated by measuring knowledge of PKU, blood phenylalanine concentrations, and health locus of control (LOC) before and after participation in the program. Of the 16 subjects, seven subjects successfully completed the program by achieving behavioral goals. These subjects increased their knowledge of PKU and decreased their blood phenylalanine concentrations, but the nine nonsuccessful subjects did not. There was no significant change in LOC scores for either group. There was a significant relationship between baseline blood phenylalanine levels and success with the program. Therefore, this pilot study demonstrates that adolescents who have already achieved some measure of metabolic control can be expected to be most successful with this program and realize the greatest benefits from it in the form of increased knowledge of PKU and even better metabolic control.

Adolescent↗

PubMed1992

Relationships between carboplatin exposure and tumor response and toxicity in patients with ovarian cancer.

PURPOSE: The study was undertaken to define the relationship between tumor response and carboplatin area under the curve (AUC) in patients with ovarian cancer; to study the relationship between carboplatin AUC and myelosuppression in the same population; to establish the true impact of carboplatin AUC, prior therapy, and pretreatment platelet and WBC counts on toxicity; and to define an optimal carboplatin exposure for treating patients with ovarian cancer. METHODS: With the equation AUC = dose/(glomerular filtration rate [GFR]+25), carboplatin AUC (course 1) was calculated for 1,028 patients (450 previously untreated) who received single-agent carboplatin (40 to 1,000 mg/m2) for advanced ovarian cancer. GFR was measured (chromium-51-edathamil [51Cr-EDTA] or creatinine clearance) in all patients. RESULTS: Regression analysis showed that carboplatin AUC, prior treatment, and Eastern Cooperative Oncology Group grade performance status (PS) are predictors of tumor response, thrombocytopenia, and leukopenia. Pretreatment platelet and WBC counts are additional predictors of thrombocytopenia and leukopenia, respectively. Although the likelihood of tumor response increased with increasing carboplatin AUC, this relationship was nonlinear. In all patient subsets, the likelihood of complete response (CR) or overall response did not increase significantly above a carboplatin AUC of 5 to 7 mg/mL x minutes. At any given carboplatin AUC, thrombocytopenia occurred more frequently than leukopenia, although both approached 100% as carboplatin AUC increased. Both thrombocytopenia and leukopenia were more frequent in pretreated than in untreated patients regardless of pretreatment count. At any carboplatin AUC, the influence of PS on likelihood of response and toxicity was profound. CONCLUSION: Carboplatin dosing by AUC will lead to more predictable toxicity, and increasing carboplatin AUC above 5 to 7 mg/mL x minutes does not improve the likelihood of response but does increase myelotoxicity. Therefore, careful evaluation of high-dose carboplatin therapy in a prospective, randomized trial is needed before such treatment becomes accepted practice.

Aged↗

PubMed1992

The second Chicago televised smoking cessation program: a 24-month follow-up.

OBJECTIVES: As smoking decreases in the population, the remaining smoking population will change, and cessation initiatives will have to incorporate strategies designed for these smokers. METHODS: To study patterns of response to a cessation intervention composed of 20 televised segments and the American Lung Association Freedom from Smoking in 20 Days manual, this study compared cessation rates over 24 months in a cohort of smokers who registered for a cessation program with those in a cohort selected from the smoking population at large. RESULTS: At post intervention, multiple point prevalence of cessation among participants, adjusted for baseline smoking, was 14% among registrants and 6% in the population; at 24 months the adjusted rates were 6% and 2%, respectively. Heavy smokers benefited more than light smokers, and there was a consistent dose-response relationship between extent of exposure to the intervention and cessation. CONCLUSION: The effects of the intervention were strongest for those who read the manual and watched the programs daily. Manual use was important, and those who did not read it did not appear to benefit. Compared to the population and given full participation, heavy smokers benefited more than lighter smokers.

Adult↗

PubMed1991

Characteristics of participants in a televised smoking cessation intervention.

Participants in various components of a televised self-help smoking cessation program, based on the American Lung Association's Freedom From Smoking in 20 Days, are compared with a sample of the population of smokers to whom the intervention was addressed. Over 325,000 smokers in the target population were exposed to the program at some level. Most watched televised segments. Approximately 75,000 manuals were distributed and about 55,000 were used. Comparisons between participants and the targeted smoking population indicate that the intervention attracted those in the smoking population who are expected to be the majority of smokers by the Year 2000-blacks, females, and those with incomes under $13,000 per year. Participants with these characteristics were most likely to view the televised segments. Heavy smokers, females, and those with the most education were most likely to refer to the manual at least twice a week during the intervention. Older, nonblack participants and those with incomes of $13,000 or more per year were most likely to attend group support sessions outside the home. Overall, the patterns of association indicate that although a televised smoking cessation program can attract individuals similar to those projected to be smokers in 2000, participation in various components of the intervention will vary by demographic characteristics.

Adolescent↗

PubMed1991

Serum time curve characteristics of a fixed dose of beta-carotene in young and old men.

The present study was designed to evaluate age-related differences in serum beta-carotene time curve response characteristics when a beta-carotene dose was given in conjunction with 1500 kcal over the course of a day. On two consecutive days, seven old (73 +/- 4 years) and six young (24 +/- 1 years) men were each fed three 500-kcal meals of an isotonic liquid formula diet containing only trace amounts of beta-carotene. On the first day of testing, no supplemental beta-carotene was given (baseline day). A 15 mg dose of beta-carotene was fed with the morning meal on the second day (test dose day). Fasting blood and hourly blood samples were obtained for 8 consecutive hours on both days. Additional blood was drawn 24 and 48 hours after the test beta-carotene dose. There were no statistical differences in baseline beta-carotene concentrations between the two age groups tested, but, because of high individual variability, serum time curve characteristics were adjusted for fasting beta-carotene levels. After adjustment, the postdose serum beta-carotene response was two to three times greater (p less than or equal to 0.04) in young subjects, as evaluated by peak concentration, area under the curve, or ascending slope of the serum response curve. Examination of factors besides age group that may have accounted for these results suggests that the serum response of the elderly may be more a function of body composition and/or serum lipid patterns than of age per se. However, in the present US population, it may not be valid to control for these factors, which are both closely related to aging.

Adult↗

PubMed1991

Changes in body weight, body composition, and energy intake in women fed high- and low-fat diets.

The effects of a 20%-fat diet (LF) on total body weight, lean body weight, and adiposity were studied in 18 premenopausal women with body mass index (BMI) of 18-44. Subjects were fed a 37%-fat (HF) control diet for 4 wk followed by the LF diet for 20 wk. Total body weight, lean body weight, and fat weight were measured at the end of the HF and LF dietary periods by hydrostatic weighing. Despite adjustments in energy intake to maintain weight throughout the study, subjects exhibited a 2.8% decrease in total body weight (P less than 0.0006), an 11.3% decrease in fat weight (P less than 0.0001), and a 2.2% increase in lean body weight (P less than 0.0149) by the end of the LF period. Similar changes were observed in obese (BMI greater than 30) and non-obese women (BMI less than 30). By the end of the LF period, energy intake had increased significantly in comparison with the HF diet (119% of the HF intake, P less than 0.0001). Results could not be explained by changes in daily activity levels and suggest that macronutrient composition plays a role in energy requirements for weight maintenance.

Adipose Tissue↗

PubMed1991

Age-related effects of chronic ethanol intake on vitamin A status in Fisher 344 rats.

The present study was designed to investigate the interaction of age and ethanol on vitamin A status in rats. Rats aged 2 and 19 mo were fed a liquid diet containing 36% of total energy as ethanol or pair-fed a diet containing isoenergetic carbohydrate in place of ethanol. After 3 wk older rats had lower serum retinol (P = 0.04) and higher vitamin A concentrations in liver (P = 0.0001), esophagus (P = 0.0001) and the proximal (P = 0.03) and distal (P = 0.0001) colon than younger animals. Hepatic microsomal cytochrome P-450, retinyl ester hydrolase (REH) and cellular retinol-binding protein (cRBP) were significantly reduced; acyl coenzyme A: retinol acyltransferase (ARAT) was increased; and alcohol (retinol) dehydrogenase (ADH) activity was unchanged with age. Ethanol ingestion increased serum retinol as well as esophageal and colonic vitamin A levels in both age groups. Hepatic cRBP decreased further in the older rats with ethanol feeding, but no change was noted in the percentage of hepatic vitamin A as retinol or retinyl esters. Ethanol ingestion decreased REH (P = 0.0001) and ARAT activities (P = 0.02) and increased cytochrome P-450 (P = 0.04) but had no effect on the activity of ADH in either age group. These data indicate that, regardless of age, chronic ethanol ingestion significantly alters the tissue distribution of vitamin A; however, ethanol reduced cRBP levels only in older rats.

Acyltransferases↗

PubMed1991

The effect of flunarizine on essential tremor.

We investigated the effect of flunarizine treatment (10 mg/d) in 17 subjects with essential tremor in a double-blind placebo-controlled design. Tremor was assessed by clinical scoring, tremographic recordings, and subjective rating by subjects. Of the 15 subjects who completed the study, 13 showed improvement. We conclude that flunarizine is effective treatment for essential tremor.

Adolescent↗

PubMed1990

Prospective study of the effect of safety belts in motor vehicle crashes.

Trauma resulting from motor vehicle crashes (MVCs) is the leading cause of death in persons 1 to 38 years old. The following prospective study was undertaken to assess the effect of safety belts on the types of injuries sustained in MVCs. A total of 1,364 patients from four Chicago-area hospitals were evaluated prospectively during a six-month period. Safety belts reduced the incidence of head, facial, thoracic, abdominal, and extremity injuries sustained in MVCs. Spinal injuries comprised the only group in which safety belt wearers sustained injuries more frequently than safety belt nonwearers. Further research on the different safety belt designs and effects of air bags is needed to reduce the incidence of cervical and lumbar strain in restrained patients.

Abbreviated Injury Scale↗

PubMed1990

Hypertension and sodium transport in 390 healthy adults in Chicago.

A total of 390 people undergoing routine examinations at the Portes Center, a screening center in Chicago, and at the Northwestern Memorial Hospital employee health service, underwent an in-depth battery of tests designed to explore the relationships of both intracellular erythrocyte sodium and sodium-lithium countertransport with age, race, gender, body mass index, pattern of alcohol intake, exogenous hormone use and the presence of hypertension. Erythrocyte sodium was significantly higher in blacks than in whites and in men than in women aged 20-39 years. Relationships of erythrocyte sodium with race and gender, as well as inverse associations with alcohol intake in men, and positive associations with age and the presence of hypertension in women were significant on multivariate analysis after control for other variables. Sodium-lithium countertransport was significantly higher in whites than in blacks and in men than in women aged 20-59 years. Associations of sodium-lithium countertransport with race and gender as well as positive associations of sodium-lithium countertransport with body mass index in men and women were significant on multivariate analysis after control for other variables. Age-related gender differences in both sodium-lithium countertransport and erythrocyte sodium, as well as the association of erythrocyte sodium with the presence of hypertension in women but not in men, suggest a hormonal interaction with sodium transport in the development of hypertension.

Adult↗

PubMed1990

Correlation between essential tremor and migraine headache.

The relationship between essential tremor (ET) and migraine was investigated in a prospective study. In a group of 74 ET patients 36.5% had migraine compared with 17.7% of 102 control subjects without tremor. In a group of 58 patients with migraine 17.2% had ET compared with 1.2% of 85 controls without migraine. The prevalence of ET in migraine controls was greater than controls without migraine (22% compared with 1%; p = 0.002). It is concluded that there is an association between essential tremor and migraine.

Adolescent↗

PubMed1990

Chinese-white differences in the distribution of occlusive cerebrovascular disease.

The distribution of cerebrovascular lesions is affected by race. Blacks and Japanese have more intracranial occlusive cerebrovascular disease, while whites have more extracranial disease. Despite a high incidence of stroke in China, there are few formal studies of the distribution of vascular occlusive disease in Chinese populations. We compared clinical and angiographic features of 24 white and 24 Chinese patients with symptomatic occlusive cerebrovascular disease. In symptomatic vascular territories, whites had more severe (greater than or equal to 50% stenosis) extracranial lesions, while Chinese had more severe intracranial lesions. When we counted mild and severe lesions in a symptomatic territory, whites had more extracranial lesions while Chinese had more intracranial lesions. When we combined symptomatic and asymptomatic territories, whites had more extracranial lesions, while Chinese had more intracranial lesions. White patients reported more transient ischemic attacks. The distribution of lesions, however, was not explained by differences in incidence of transient ischemia, hypertension, diabetes, hypercholesterolemia, or ischemic heart disease between the groups. The preponderance of intracranial vascular lesions in Chinese patients is similar to that seen in blacks and Japanese. Racial differences in the occurrence of extracranial and intracranial lesions raise the possibility of a different underlying pathophysiology for the 2 locations.

Aged↗