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Biomedical subjects

R Weinberg

Publications and source records attributed to R Weinberg.

At least 91 records · Page 5Linked to original sources
PubMed1982

Hereditary and environmental influences on cardiovascular risk factors for children: the Bogalusa Heart Study.

This paper reports on a study of all school-age children from Bogalusa, Louisiana, examined during the 1973-1974 and 1976-1977 school years by personnel of the Specialized Center of Research-Arteriosclerosis. For these children, the authors estimated the proportion of total variability in risk factors for atherosclerosis resulting from the influences of heredity (h2) and of common environment (c2). The authors' method of classifying half siblings underestimated h2 but overestimated c2. The results showed statistically significant values of h2 for height (0.91), weight (0.90), systolic blood pressure (.137), triglycerides (0.88), beta-lipoprotein (1.16), and alpha-lipoprotein (0.63). In addition, c2 was statistically significant for height (0.20), weight (0.32), triceps skinfold (0.19), systolic blood pressure (0.30), beta-lipoprotein (0.21), and alpha-lipoprotein (0.13). Because of the definition of c2, all traits for which it is significant must increase in value for some Bogalusa environments, and decrease for others. Therefore, for such traits, future analyses may identify favorable common environments that intervention studies can use to decrease the risk of atherosclerosis in Bogalusa. The values found for h2 and c2 in Bogalusa were compared and contrasted with values found for other communities.

Adolescent↗
PubMed1982

Transfection of fibroblasts by cloned Abelson murine leukemia virus DNA and recovery of transmissible virus by recombination with helper virus.

A cloned, permuted DNA copy of the Abelson murine leukemia virus (A-MuLV) genome was capable of eliciting the morphological transformation of NIH/3T3 fibroblasts when applied to cells in a calcium phosphate precipitate. The efficiency of the process was extremely low, yielding approximately one transformant per microgram of DNA under conditions which give 10(4) transfectants per microgram of other DNAs (e.g., Moloney sarcoma virus proviral DNA). The DNA was able to induce foci, even though the 3' end of the genome was not present. The transforming gene was thus localized to the 5' portion of the genome. The transformed cells all produced viral RNA and the virus-specific P90 protein. Transmissible virus could be rescued from these cells at very low frequencies by superinfection with helper virus; the rescued A-MuLV virus had variable 3' ends apparently derived by recombination with the helper. Dimerization of the permuted A-MuLV cloned genome to reconstruct a complete provirus did not improve transformation efficiency. Virus could be rescued from these transformants, however, at a high efficiency. Cotransfection of the permuted A-MuLV DNA with proviral M-MuLV DNA yielded a significant increase in the efficiency of transformation and cotransfection of dimeric A-MuLV and proviral M-MuLV resulted in a high-efficiency transformation yielding several thousand more transformants per microgram than A-MuLV DNA alone. We propose that helper virus efficiently rescues A-MuLV from transiently transfected cells which would not otherwise have grown into foci. We hypothesize that multiple copies of A-MuLV DNA introduced into cells by transfection are toxic to cells. In support of this hypothesis, we have shown that A-MuLV DNA sequences can inhibit the stable transformation of cells by other selectable DNAs.

Abelson murine leukemia virus↗
PubMed1981

Evaluation of the quality of duplicated radiographs.

This experiment evaluated the image quality of duplicated radiographs made at different ultraviolet light exposures. Image quality was measured in terms of "residual" film fog, film density, mottle, image contrast, and resolution. The "residual" fog density of duplicates decreased with increases in ultraviolet exposures until it was less than the fog density of the original. The density of duplicates decreased with increases in ultraviolet exposures until it leveled off at a certain density, depending on the density of the original film. Mottle was less on lighter duplicates than on darker duplicates. Contrast of duplicates increased initially with increases in ultraviolet exposures and later decreased with further increases in ultraviolet exposures. Resolution of duplicates was nearly the same as the original as long as the duplicate had acceptable "residual" fog density.

Copying Processes↗
PubMed1981

The heart rate, perceived exertion, and pace of the 1.5 mile run.

The logical validity of a 1.5-mile run as a measure of aerobic capacity, and the validity of Borg's laboratory model of perceived exertion (RPE) were examined in a field setting on a 440-yd cinder track. Performance time, heart rate (HR), and RPE were described for college-age males (N=67) instructed to achieve the lowest time possible during an "all-out" effort. Alpha and canonical factor analyses revealed three robust factors for performance times: 1) lap 1, 2) laps 2.5, 3) lap 6; two robust factors for HR: 1) laps 3-6, 2) laps 1 and 2; and four factors for RPE: 1) lap 6, 2) laps 1-3, 3) laps 4 and 5, 4) first 220 yd of lap 1. Results indicated distinct pacing characteristics of an initial sprint, a stable speed reduction, and a finishing sprint. This pace was generally independent of Ss HR (r's, mean lap 1 = 0.09; mean laps 2-5 = 0.19, mean lap 6 = 0.21) and RPE (r's, mean lap 1 = -0.15; mean laps 2-5 = 0.12; mean lap 6 = 0.07), and in part these findings at least implicate confounding influences by anaerobic metabolism and Ss motivation on performance. This possibility was supported by the fact that 95% of performance variance could be accounted for by pace factors of the initial and finishing sprints. Both HR and RPE response followed a linear-like increase as a function of cumulative time and distance. However, only a small relationship between HR and RPE (r, mean = 0.16) was observed during the run, and the obtained correlations did not support a central RPE-control model based on cardiovascular stress.

Adult↗
PubMed1981

A comparison of attitudes and final grades among freshman dental students.

A study was conducted to determine if a change in dental students' attitudes toward three preselected concepts would occur as a result of a traditionally difficult gross anatomy course. In addition, an attempt was made to determine the predictive value of a student's attitudes in determining his or her final grade. The study employed Campbell and Stanley's one group pretest-posttest design. The results indicated that students' attitudes toward a difficult course and themselves did not change significantly, but that a significant negative change did occur in their attitude toward the entire dental educational experience. The results also indicated that students' attitudes toward specific concepts can be successfully employed to predict a portion of their final grade.

Anatomy↗
PubMed1980

Thrombosis of the spermatic vein in children.

We describe 3 children in whom thrombosis of the spermatic vein vessels caused swelling of the spermatic cord and epididymis with edema of the scrotum. Venography of the spermatic vein demonstrated the thrombosis and, therefore unnecessary exploration was avoided.

Child↗
PubMed1980

Comparison of films processed in automatic and manual processors.

This study compared the quality of Kodak RP X-Omat, Kodak Blue Brand, and Kodak periapical films processed in manual tank. Auveloper, P-10, All-Pro, Philips 810, and RP X-Omat processors. Film quality was evaluated in terms of film fog, image contrast, and resolution. For Kodak RP X-Omat and periapical films, automatic processors produced less film fog and were more consistent in fog production than manual tank processor. The difference in fog production between automatic and manual processors was not clinically significant; indeed, it was visuially undetectable. The difference disappeared when Kodak Blue Brand film was used. For Kodak RPX-Omat and Kodak Blue Brand films, at high film densities, the RP X-Omat processor produced films of the highest image contrast. For periapical films, the manual processor produced the highest image contrast. Image contrast at low densities was nearly the same for all processors. For each type of film, resolution was nearly the same for all processors.

Radiography, Dental↗
PubMed1980

Competition trait anxiety, state anxiety, and performance.

This study tested predictions about social facilitation using a competitive (evaluation) vs non-competitive setting. In addition, subjects who exhibited low, moderate, or high anxiety concerning competition were selected to determine the relation of anxiety to social facilitation. The design was 2 (competition/no competition) X 3 (competition trait anxiety), with state anxiety and performance as the major dependent variables. In a significant main effect of anxiety about competition subjects high in competitive anxiety displayed higher levels of state anxiety than subjects moderate or low in anxiety about competition. Performance differences were non-significant although means were as predicted.

Achievement↗
PubMed1979

Path analysis of environmental and genetic influences on blood pressure.

Familial aggregation of a trait (determined by the intraclass correlation coefficient) may result from genetic influence or from environment common to a household. The authors used path analysis to separate aggregation into the proportion of population variability due to genetic influence (h2 = heritability) and the proportion due to environment common to a household (c2). They used data from full siblings and maternal half siblings, aged two to 18 years, from Bogalusa, Louisiana, a biracial community. The statistically significant aggregation they found could be explained by either h2 or c2 except for two cases: systolic measurement in the pooled (black and white) sample requires h2; diastolic measurement in the white sample requires c2. The authors present a simplified explanation of the techniques they used.

Adolescent↗
PubMed1978

Poor predictability of lactose malabsorption from clinical symptoms for Chilean populations.

Clinical symptoms and lactose malabsorption may occur in persons intolerant to lactose. To predict malabsorption from symptoms and age, the authors used simple regression, multiple regression, and discrimant analysis on data from 436 Chileans. All individual r2 values from simple regression were less than 0.05. For the best stepwise multiple regression program, R2 was only 0.09, indicating that 91% of the variability in malabsorption was "unexplained" by the five best predictor variables. Because of so much unexplained variability, the authors could detect (using multiple regression) only 56 of 90 (62%) malabsorbers and only 14 of 38 (37%) absorbers. In conclusion, for their Chilean populations the authors poorly predicted malabsorption from symptoms.

Adolescent↗
PubMed1978

Childhood sibling aggregation of coronary artery disease risk factor variables in a biracial community.

To analyze aggregation of risk factors for coronary artery disease (CAD), the authors studied 4538 children from the biracial community of Bogalusa, Louisiana. Of these children ranging in age from two to 18 years, 2535 had at least one sibling, permitting the calculation of F-ratios and intraclass correlation coefficients. Those calculations revealed statistically signigicant F-ratios for all anthropometric, blood pressure and lipid variables studied. Of the lipoprotein variables studied only alpha-lipoprotein showed no statistically significant aggregation (for black children). The analysis failed to reveal any significant differences in intraclass correlations between black and white children.

Adolescent↗
PubMed1976

Estimates of the heritability of serum lipoprotein and lipid concentrations.

Heritability (h2) of a serum lipid or a serum lipoprotein concentration is the proportion of variability in that concentration, among individuals, which is associated with heredity. We derive a familiar formula for estimating heritability (h2) from a simple linear model for inheritance. The formula was implied by Fisher (1918) and by Wright (1921); it was derived from a consideration of variances by Jensen (1967), and from a consideration of path coefficients by Rao et al. (1974). The estimate of heritability (ĥ2) is ĥ2 = 2(rMZ - rDZ) for twin studies, where rMZ and rDZ are the sample intraclass correlation coefficients among monozygous and dizygous twins, respectively. We calculate ĥ2 for some published twin data (Heiberg 1974) on serum lipoprotein and serum lipid concentrations.

Analysis of Variance↗
PubMed1975

Mechanism of induction of RNA tumor viruses by halogenated pyrimidines.

Frome these studies on JLS V-9 cells, a number of conclusions can be drawn about the mechanism of MuLV induction by halogenated pyrimidines. The compounds can induce virus from otherwise healthy cells as long as deoxycytidine is present along with the inducing agent. The compounds must be present during the S phase of the cell cycle and must be incorporated into DNA in order to induce virus (Teich et al. 1973). Only one strand of DNA need be substituted by BrdU or IdU in order to induce virus, because a one-hour period of incorporation leads to induction. From these results it is possible to construct a model for how halogenated pyrimidines are able to induce viruses from otherwise uninfected cells. Because the critical period for the incorporation of the compound is a restricted segment of the S phase of the cell, there would appear to be a critical segment of the genetic information of the cell which, when substituted with BrdU or IdU, leads to a transcriptional derepression. Presumably the critical segment of DNA is either a controlling element of the integrated provirus or it is a separate gene which controls the expression of the integrated provirus. Whichever is true, these results strongly imply that the search for specific repressors of the segments of mammalian DNA is likely to be successful and that RNA tumor viruses may offer a system in which such repression systems can be identified and investigated.

Bromodeoxyuridine↗
PubMed1974

Translation of mRNA from simian virus 40-infected cells into simian virus 40 capsid protein by cell-free extracts.

Messenger RNA was isolated from simian virus 40 (SV40)-infected and mock-infected cells by chromatography on poly(U) sepharose. When added to cell-free extracts from Chinese hamster ovary cells or rabbit reticulocytes, RNA from the infected cells, but not from mock-infected cells, stimulated synthesis of the major SV40 capsid protein. Identification of this species was done by sodium dodecyl sulfate gel electrophoresis, peptide mapping, and immunoprecipitation. The in vitro synthesized capsid protein was slightly different from virion assembled capsid protein, as shown by separation upon chromatography on hydroxylapatite and by minor differences in the peptide map.

Animals↗