Search PubMed⌕ Search

Biomedical subjects

M Rosenthal

Publications and source records attributed to M Rosenthal.

At least 181 records · Page 10Linked to original sources

How many days of bed rest for acute low back pain? A randomized clinical trial.

Bed rest is usually recommended for acute low back pain. Although the optimal duration of bed rest is uncertain, a given prescription may directly affect the number of days lost from work or other activities. In a randomized trial, we compared the consequences of recommending two days of bed rest (Group I) with those of recommending seven days (Group II). The subjects were 203 walk-in patients with mechanical low back pain; 78 percent had acute pain (less than or equal to 30 days), and none had marked neurologic deficits. Follow-up data were obtained at three weeks (93 percent) and three months (88 percent). Although compliance with the recommendation of bed rest was variable, patients randomly assigned to Group I missed 45 percent fewer days of work than those assigned to Group II (3.1 vs. 5.6 days, P = 0.01), and no differences were observed in other functional, physiologic, or perceived outcomes. For many patients without neuromotor deficits, clinicians may be able to recommend two days of bed rest rather than longer periods, without any perceptible difference in clinical outcome. If widely applied, this policy might substantially reduce absenteeism from work and the resulting indirect costs of low back pain for both patients and employers.

Absenteeism↗

Dexamethasone suppresses pituitary-adrenal but not behavioral effects of centrally administered CRF.

Intracerebral ventricular (icv) administration of corticotropin-releasing factor (CRF) significantly enhances the expression of stress-related behaviors in the rat and also activates the pituitary-adrenal system. The pituitary-adrenal response can be blocked by pretreatment of animals with dexamethasone. The behavioral effects (motor activation, increased grooming and decreased eating) on the other hand are resistant to suppression by dexamethasone. The independence of the behavioral effects from activation of the pituitary-adrenal axis suggests that stress-induced release of CRF could contribute to behavioral alterations even in the presence of high concentrations of endogenous steroids.

Adrenocorticotropic Hormone↗

Relationship of prevalence of non-insulin-dependent diabetes mellitus to Amerindian admixture in the Mexican Americans of San Antonio, Texas.

A genetic and epidemiological survey of non-insulin-dependent diabetes mellitus (NIDDM) was conducted among the Mexican Americans residing in three socioeconomically distinct areas of San Antonio, Texas: a low socioeconomic (SES) traditional area (barrio), a middle SES, ethnically balanced area (transitional), and a high SES, predominantly Anglo area (suburb). Seventeen polymorphic markers were used to relate the prevalences of NIDDM with the extent of Amerindian ancestry of 1,237 Mexican Americans of these three residential areas. While only the RH and haptoglobin loci showed evidence of association with NIDDM, an admixture analysis of the combined allele frequency data revealed a pattern of decreasing NIDDM prevalence with increasing socioeconomic status (as approximated by neighborhood of residence) and a parallel decrease in Amerindian ancestry. The rank-order correlation between NIDDM prevalence and Amerindian admixture is 0.943 (P less than .001) for the crude prevalence rate and 0.829 (P less than .02) for the age-adjusted rate. Nested gene diversity analysis revealed that the heterogeneity of allele frequencies is more pronounced when individuals were classified by their NIDDM disease status as compared to the classification by neighborhood. Estimation of Amerindian ancestry of each individual did not reveal any significant change in the shape of the distributions of individual admixture proportions in diabetics as compared to the controls. Nevertheless, the results suggest that genetic factors partially explain the differences in NIDDM prevalence observed between the Mexican American and Anglo populations in the southwestern United States.

Adult↗

The ontogeny of renal alpha 1- and alpha 2-adrenoceptors in the Dahl rat model of experimental hypertension.

[3H]prazosin (PRAZ) and [3H]rauwolscine (RAUW) were used to examine the ontogeny of renal alpha 1- and alpha 2-adrenoceptors in the inbred Dahl hypertension-sensitive (S/JR) and -resistant (R/JR) rat. PRAZ and RAUW each bound to a single population of non-interacting sites. The binding of each ligand was saturable and reversible. The greatest proliferation of each receptor subtype occurred between 5 and 25 days of age. During this period, a 4 to 5-fold increase in the density of each was observed. Adult levels of each were reached by 50 days of age. The alpha 2-adrenoceptor was the predominant subtype present in renal tissue. However, its ratio to the alpha 1 subtype was influenced by strain and age: the ratio was greatest in the S/JR strain and decreased with age in both strains. The profile of alpha 1-adrenoceptor development was similar in S/JR and R/JR rats. In contrast, the density of alpha 2-adrenoceptors was similar in S/JR and R/JR rats at 5 and 15 days of age but significantly greater in the S/JR rat between 25 and 150 days of age. The elevated density of alpha 2-adrenoceptors could not be explained by strain-related differences in blood pressure or alterations in the affinity of the receptor. The results suggest that a relationship may exist between elevated renal alpha 2-adrenoceptor density and the genetic predisposition to hypertension in the S/JR rat. However, because this relationship is not apparent during the neonatal period of development, the possibility that the elevated density of sites may be secondary to some other event should also be considered.

Age Factors↗

A comparison of three indicators for identifying Mexican Americans in epidemiologic research. Methodological findings from the San Antonio Heart Study.

Because the issue of how to empirically identify Mexican Americans in health-related research is still unresolved, the authors compared the performance of three indicators for identifying Mexican Americans across five distinct population subgroups: men and women in two age strata, and residents in low, middle, and high socioeconomic neighborhoods. Individual surname had the lowest sensitivity, specificity, and predictive values in the pooled population sample and varied the most widely on these parameters across population subgroups. Parental surnames, which are available on vital statistics and could easily be added to other health records used in secondary analyses, offered a significant improvement over individual surname in classifying persons as Mexican American. The San Antonio Heart Study (SAHS) algorithm, a nine-item indicator which uses parental surnames, birthplace of both parents, self-declared ethnic identity, and ethnic background of grandparents, had the highest sensitivity, specificity, and predictive values and varied the least on these parameters across different sex, age, and socioeconomic status population subgroups. The performance of all indicators was lower at the higher socioeconomic status levels. The findings suggest that it may be useful to use parental surnames as an indicator for Mexican-American ethnicity in research involving vital statistics and to add parental surnames to other health records frequently used in secondary analyses. Since the SAHS algorithm can be adapted for use with non-Mexican origin Hispanic subgroups, it may be a useful indicator for Mexican-American (or other Hispanic) ethnicity in survey research.

Adult↗

Employment status and women's protection against coronary heart disease. Findings from the San Antonio Heart Study.

This study examined whether currently employed women are at increased risk of coronary heart disease relative to full-time homemakers. Subjects were 1,041 Mexican-American and non-Hispanic white women aged 25-64 years, residing in households randomly selected from three socioculturally distinct neighborhoods in San Antonio, Texas. No statistically significant differences between employed women and homemakers were found for obesity, total serum cholesterol, low density lipoprotein cholesterol, systolic and diastolic blood pressures, or cigarette smoking. Highly significant differences favoring employed women over homemakers were found for both Mexican Americans and non-Hispanic whites in high density lipoprotein (HDL) cholesterol, ratio of HDL cholesterol to total cholesterol, and triglycerides. These differences were not explained by obesity, exercise, cigarette smoking, alcohol consumption, use of exogenous estrogens, and use of oral contraceptives, or by the healthy worker effect, and were observed at all occupational levels. Employed women ate a less atherogenic diet than full-time homemakers, but it is not clear that this nutritional factor could explain the differences in HDL cholesterol and triglycerides found in this study. The magnitude of the employment status difference in HDL cholesterol for both ethnic groups was in a range (3-4 mg/100 ml) associated with protection against coronary heart disease.

Adult↗

The role of behavioral variables and fat patterning in explaining ethnic differences in serum lipids and lipoproteins.

Mexican Americans have been previously reported to have greater adiposity, higher triglyceride levels, and lower high density lipoprotein (HDL) cholesterol levels than Anglos. This study investigated the relationship between behavioral variables (caloric balance, cigarette and alcohol consumption, exercise, postmenopausal estrogen or oral contraceptive use) and fat patterning (central vs. peripheral distribution of adiposity) in the San Antonio Heart Study (1979-1982) (n = 2,102) to explain the ethnic difference in lipids and lipoproteins. Adjustment for caloric balance (as reflected by body mass index) narrowed the ethnic difference in triglyceride and HDL levels for both sexes, while adjustment for smoking widened the ethnic difference. For females, the ethnic difference was also decreased by adjustment for alcohol and estrogen use. However, adjustment for these behavioral variables did not completely eliminate the ethnic difference in lipids and lipoproteins in either sex. Increased central adiposity, more characteristic of Mexican Americans than Anglos, was positively associated with triglycerides and negatively associated with HDL levels, especially in females. Fat patterning made a more important contribution to the prediction of triglyceride and HDL levels than did the other behavioral variables (except for caloric balance) and, in general, eliminated ethnic differences in lipids and lipoproteins. Epidemiologists should consider the use of a centrality index to distinguish different types of adiposity since it is easy and inexpensive to measure.

Adipose Tissue↗

Hemodynamic effects of pulmonary insufficiency.

Although far from complete, this discussion points to the more common relevant hemodynamic sequelae in patients with pulmonary insufficiency. Successful management of these patients requires careful attention to systemic interactions of both the primary pathophysiology and therapeutic interventions.

Adult↗

Association between NIDDM, RH blood group, and haptoglobin phenotype. Results from the San Antonio Heart Study.

We examined seven red cell antigen and 10 polymorphic protein phenotypes in 1237 Mexican Americans randomly selected from three San Antonio neighborhoods. Statistically significant associations were found between non-insulin-dependent diabetes mellitus (NIDDM) and RH blood type (X2 = 32.87, df = 10, P = 0.0003) and haptoglobin phenotype (X2 = 9.15, df = 2, P = 0.010). The haptoglobin association showed a dose effect with a single dose of the haptoglobin-1 allele associated with an approximately 50% increase and a double dose of the haptoglobin-1 allele associated with an approximately 100% increase in NIDDM prevalence. Multivariate analysis indicated statistically significant associations between NIDDM and age, sex, adiposity, and neighborhood of residence. However, even after taking these potential confounding variables into account, there was still a significant, independent association between NIDDM and haptoglobin phenotype. The results suggest that the haptoglobin gene may be in linkage disequilibrium with a major susceptibility gene for NIDDM.

Adult↗

Effect of a bacterial extract on cellular and humoral immune responses in humans.

A lyophilized extract from E. coli (OM-89) was studied for its immunomodulating properties and tolerance in humans. Its oral administration to healthy volunteers produced a selective increase in the active T-cell population without changes in other lymphocyte populations. A significant increase in the proliferative response to concanavalin A and phytohemagglutin was recorded, but not to pokeweed mitogen. No significant changes were observed in the serum levels of IgG, IgA and IgM. The clinical and biological tolerance of OM-89 was excellent, without any adverse side-effects or production of circulating immune complexes or of autoantibodies, while the in vitro investigation showed that it is not a mitogen. Thus in healthy subjects OM-89 seems to act mainly on the cell-mediated immune responses.

Adjuvants, Immunologic↗

Triathlete characterization and response to prolonged strenuous competition.

The purpose of this study was to characterize triathletes and to assess their responses to prolonged, strenuous competition. Nine triathletes (6 males, 3 females) participated. Mean V0(2)max and percentage of body fat were 72.0 ml X kg-1 X min-1 and 7.1%, respectively, in the four males who finished in the top 15. This compared to values of 58.4 ml X kg-1 X min-1/10.2% and 58.7 ml X kg-1 X min-1/12.6% in the other males and females, respectively. In the 5 wk preceding competition (Hawaii "Ironman Triathlon World Championship") the average daily training of the four top 15 male competitors consisted of swimming 2720 m, running 13.6 km, and biking 84.0 km. This was approximately 1.5 times greater than that of the other athletes. The average training diet was 59% carbohydrate, 21% fat, and 20% protein. Immediately following competition, SGOT, SGPT, and serum LDH were increased 700, 262, and 222% (P less than 0.004), respectively, and still remained marginally elevated 5-6 d later (P less than 0.02). Immediately following competition, serum triglycerides remained unchanged, while serum glucose, glycerol, and nonesterified fatty acids increased 52, 248, and 191% (P less than 0.005), respectively. By 5-6 d post-competition glucose had returned to normal, while triglycerides were elevated 94% (P less than 0.005) and nonsterified fatty acids were decreased 58% (P less than 0.01).

Alanine Transaminase↗

A rapid-scanning spectrophotometer designed for biological tissues in vitro or in vivo.

Rapid and sensitive detection of optical signals from biological materials has been very useful in studies of cell physiology and biochemistry. A rapid-scanning spectrophotometer is described here that has the following advantages: (i) it can be used in transmission or reflection modes, (ii) it can rapidly accumulate spectra and simultaneous kinetic data, (iii) it has high accuracy and sensitivity, and (iv) it can analyze and store large amounts of spectral information. Evaluations described here are aimed toward the measurement of reduction/oxidation shifts of mitochondrial cytochromes in tissues, but the flexibility of the optical components makes this spectrophotometer adaptable to the study of light absorption changes of intrinsic or extrinsic optically active molecules in a variety of light scattering preparations, tissues, and organs in vitro or in vivo.

Animals↗

A computer-assisted rapid-scanning spectrophotometer with applications to tissues in vitro and in vivo.

A flexible approach is described to acquire, store, retrieve, and manipulate the large volume of data provided by a rapid-scanning spectrophotometer designed for biological preparations. Data can be displayed in spectral and kinetic formats. This spectrophotometer provides a means to simultaneously measure the concentrations of components of light scattering preparations and to record chemical reactions as they occur. Although application of this instrument for the study of reduction/oxidation shifts of mitochondrial respiratory chain components is emphasized, the design is suitable for many spectrophotometric applications.

Animals↗

Evidence of bimodality of two hour plasma glucose concentrations in Mexican Americans: results from the San Antonio Heart study.

Evidence for bimodality in the distribution of two hour post oral glucose challenge plasma glucose concentrations has come previously primarily from native American and Pacific Island populations having high non-insulin dependent diabetes mellitus (NIDDM) prevalence. Because the National Diabetes Data Group (NDDG) criteria for diagnosing NIDDM rely in part upon the assumption of bimodality, it is important to determine the generality of this phenomenon. We looked for bimodality among Mexican Americans in San Antonio, a population having greater than 50% Caucasian admixture. By fitting both a single normal distribution model and a mixture model of two normal distributions, for each age decade, we found that the mixture model was preferred to the single normal model (p less than 0.001) and that this model fit the data well. The proportion in the upper component (hyperglycemics) increased with each successive age decade. The minimum misclassification cutpoints decreased with age, but all were higher than the 200 mg/dl cutpoint recommended by the NDDG. Use of the NDDG cutpoint, however, improved sensitivity with only a minimal deterioration of specificity. Our findings further generalize the bimodality phenomenon and support the NDDG criteria.

Adult↗

Socioeconomic status and the prevalence of clinical gallbladder disease.

The prevalence of clinical gallbladder disease was determined in a cross-sectional survey of Mexican Americans and non-Hispanic whites. The study population was randomly selected from three urban neighborhoods representing different socioeconomic strata. Gallbladder disease was defined as a history of cholecystectomy, or of stones on cholecystography. Mexican American women had an age-standardized prevalence of 16.9%, vs 8.7% for non-Hispanic whites (p less than 0.0001). Prevalences in men were 4.2 and 3.4%, respectively. The ethnic differences in women persisted after stratification by age, parity, and body mass index. Gallbladder disease prevalence was inversely related to four measures of socioeconomic status. After controlling for age, obesity, parity, and ethnicity, the prevalence in women was inversely related to levels of education, income, occupational status, and neighborhood. These socioeconomic differences, if not the result of detection bias, suggest that environmental factors may play a role in gallstone pathogenesis. Identification of such factors may lead to the development of preventive strategies.

Adult↗