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Biomedical subjects

R Levinson

Publications and source records attributed to R Levinson.

At least 19 recordsLinked to original sources
PubMed1997

Centers for Disease Control and Prevention partnerships with external behavioral and social scientists. Roles, extramural funding, and employment.

The Centers for Disease Control and Prevention (CDC) must have strong external partnerships with behavioral and social scientists to refine and carry out its research and programmatic mission. This article examines funding, employment, and other mechanisms used to develop and foster such partnerships. The authors describe in detail funding mechanisms (especially the often-used cooperative agreement and contracting mechanisms) and identify specific sources of information about funding opportunities. Furthermore, they describe several different long- and short-term employment mechanisms that can be used to link CDC staff and external behavioral scientists. Finally, external behavioral and social scientists can serve in important roles as members of CDC advisory committees, peer reviewers of funding applications, and consultants; examples of these opportunities are also provided.

Behavioral Sciences↗
PubMed1993

Physical activity of public housing residents in Birmingham, Alabama.

OBJECTIVES: Because few data are available concerning physical activity among minority and low-income persons, we characterized physical activity patterns among public housing residents. METHODS: Two separate cross-sectional surveys were conducted 1 year apart of randomly selected residents of eight rental communities administered by the housing authority of Birmingham, Ala. Indigenous interviewers completed 687 interviews in survey 1 and 599 in survey 2. RESULTS: In both surveys, respondents were most frequently young adult African-American women, reflecting the predominance of women in these communities. Participants were generally poorly educated and either unemployed or working in service occupations. Thirty percent of the respondents in both surveys reported no participation in any of 13 physical activities in the previous year; approximately half reported activity levels equivalent to or less than walking 4 hours per week for 8 months of the year. Respondents who were younger and male were significantly more likely to have higher activity levels. CONCLUSIONS: A sedentary life-style is common among this low-income minority group, and, thus, interventions to promote exercise in these communities are needed.

Adolescent↗
PubMed1993

Promoting physical activity in low-income African-American communities: the PARR project.

Data suggest that low-income and minority individuals are less physically active than the general population. We conducted a constituency-based physical activity promotion program, the Physical Activity for Risk Reduction (PARR) project, from 1988 to 1991, with residents of rental communities administered by the Housing Authority of the Birmingham District in Birmingham, Alabama. Data collected through focus groups and by survey of randomly selected residents' exercise practices, beliefs, barriers to and facilitators of physical activity were used to develop specific intervention programs that were implemented and evaluated in six intervention and two control communities through surveys and process evaluations. Trained community residents conducted data collection and interventions. Ninety-nine percent of respondents in the baseline survey were African Americans. Thirty-one percent reported no participation in any of 13 physical activities in the previous year. Significant differences (P < .05) in average attendance by community at group exercise sessions indicated substantial variability in effectiveness of the intervention, due at least in part to factors related to both the communities and the leaders. This variability appeared to explain patterns of change in preintervention and postintervention physical activity scores in intervention communities. Data and experiences from PARR will be applicable to the delivery of similar types of health-related programs in undeserved communities.

Adolescent↗
PubMed1992

Identification of the active site residues in the nsP2 proteinase of Sindbis virus.

The nonstructural polyproteins of Sindbis virus are processed by a virus-encoded proteinase which is located in the C-terminal domain of nsP2. Here we have performed a mutagenic analysis to identify the active site residues of this proteinase. Substitution of other amino acids for either Cys-481 or His-558 completely abolished proteolytic processing of Sindbis virus polyproteins in vitro. Substitutions within this domain for a second cysteine conserved among alphaviruses, for four other conserved histidines, or for a conserved serine did not affect the activity of the enzyme. These results suggest that nsP2 is a papain-like proteinase whose catalytic dyad is composed of Cys-481 and His-558. Since an asparagine residue has been implicated in the active site of papain, we changed the four conserved asparagine residues in the C-terminal half of nsP2 and found that all could be substituted without total loss of activity. Among papain-like proteinases, the residue following the catalytic histidine is alanine or glycine in the plant and animal enzymes, and the presence of Trp-559 in alphaviruses is unusual. A mutant enzyme containing Ala-559 was completely inactive, implying that Trp-559 is essential for a functional proteinase. All of these mutations were introduced into a full-length clone of Sindbis virus from which infectious RNA could be transcribed in vitro, and the effects of these changes on viability were tested. In all cases it was found that mutations which abolished proteolytic activity were lethal, whether or not these mutations were in the catalytic residues, indicating that proteolysis of the nonstructural polyprotein is essential for Sindbis replication.

Amino Acid Sequence↗
PubMed1992

Noise pollution in the operating room: a hazard to surgeons, personnel, and patients.

Noise levels up to 118 dB--a level that is potentially damaging to the hearing--were measured in the operating room, notably during the use of high-speed gas turbine bone-cutting drills. Suction tips, which had trapped tissue "whistles" inside, yielded noise levels of up to 96 dB. Surgeons, staff, and patients should be cautioned against such noises and shielded in prolonged cases. We offer a review of acoustical criteria for various practical noises and duration of safe exposure.

Adult↗
PubMed1990

Erythropoietin has a mitogenic and positive chemotactic effect on endothelial cells.

Erythropoietin is known to be a hematopoietic growth factor with a singularly specific action on the proliferation and differentiation of erythroid progenitor cells. We have observed a dose-dependent proliferative action of human recombinant erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial cells. Binding studies with radioiodinated recombinant human erythropoietin revealed a large number (approximately 27,000) of an apparent single class of receptors with an affinity in the 10(-9) M range. Linkage of the radiolabeled ligand to its receptor via a bifunctional crosslinking agent allowed us to identify an endothelial cell protein of 45 kDa as the principal receptor associated with this mitogenic effect of erythropoietin. Recombinant human erythropoietin also enhanced the migration of endothelial cells.

Cell Division↗
PubMed1989

Evaluation of a diffusion strategy for school-based hypertension education.

The purpose of this research was to evaluate the effectiveness of hypertension (HBP) education within a population of sixth grade students (n = 1204) and their parents (n = 1446). The "3Rs and HBP" curriculum attempts to diffuse the HBP information from teachers, to pupils and then to parents using the sixth grade son/daughter as a "health messenger." This curriculum was tested with and without a home blood pressure measurement component versus controls in 21 schools randomly assigned to the three conditions. Postintervention data were collected from students at school and from their parents at home interviews. Students were compared for knowledge, blood pressure measurement skill, and home diffusion activities. Parents were compared for knowledge, risk factor reduction, blood pressure, care-seeking, and compliance behaviors. Student self-esteem and family interactions were investigated as possible intervening variables in the diffusion process. Student knowledge, BP measurement skills, and diffusion to parents was increased by the 3Rs and HBP curriculum with the home component. Parental effects beyond the diffusion process were limited to knowledge improvement in certain groups. Family interaction (level and style) was found to be a significant intervening variable in the diffusion process.

Child↗
PubMed1988

Nonstructural proteins nsP3 and nsP4 of Ross River and O'Nyong-nyong viruses: sequence and comparison with those of other alphaviruses.

We have sequenced the nsP3 and nsP4 region of two alphaviruses, Ross River virus and O'Nyong-nyong virus, in order to examine these viruses for the presence or absence of an opal termination codon present between nsP3 and nsP4 in many alphaviruses. We found that Ross River virus possesses an in-phase opal termination codon between nsP3 and nsP4, whereas in O'Nyong-nyong virus this termination codon is replaced by an arginine codon. Previous studies have shown that two other alphaviruses, Sindbis virus and Middelburg virus, possess an opal termination codon separating nsP3 and nsP4 [E.G. Strauss, C.M. Rice, and J.H. Strauss (1983), Proc. Natl. Acad. Sci. USA 80, 5271-5275], whereas Semliki Forest virus possesses an arginine codon in lieu of the opal codon [K. Takkinen (1986), Nucleic Acids Res. 14, 5667-5682]. Thus, of the five alphaviruses examined to date, three possess the opal codon and two do not. Production of nsP4 requires readthrough of the opal codon in those alphaviruses that possess this termination codon and the function of the termination codon may be to regulate the amount of nsP4 produced. It is an open question then as to whether alphaviruses with no termination codon use other mechanisms to regulate the activity of this gene. The nsP4s of these five alphaviruses are highly conserved, sharing 71-76% amino acid sequence similarity, and all five contain the Gly-Asp-Asp motif found in many RNA virus replicases. The nsP3s are somewhat less conserved, sharing 52-73% amino acid sequence similarity throughout most of the protein, but each possesses a nonconserved C-terminal domain of 134 to 246 amino acids of unknown function.

Alphavirus↗
PubMed1988

Analysis of contraceptive behavior of sexually active female adolescents in the United States.

Drawing on a theoretical model of adolescent contraceptive behavior, we examined the relationships between various social and behavioral variables and contraceptive use by sexually active female adolescents. Hypotheses were tested with the use of a national random sample of sexually active female adolescents (n = 1426), aged 15 to 20 years, from Cycle III of the National Survey of Family Growth. The data were analyzed with Pearson correlation coefficients and multiple regression analysis. Noncompliance with the initial birth control method was the strongest predictor of the adolescents' contraceptive behavior at the time of the interview. Not acquiring birth control at the initial family planning visit and the frequency of family planning visits during the previous 12 months were the second and third best predictors of subjects' contraceptive use. Coital frequency and the length of time between first coitus and the initiation of birth control each explained a small amount of additional variation in the regression model. When combined, these five variables explained 40% of the variation in the contraceptive behavior of this representative sample of sexually active female adolescents. The findings could be useful for clinicians in providing more effective birth control counseling to adolescent patients.

Adolescent↗
PubMed1986

Megavoltage radiotherapy using water bolus in the treatment of Kaposi's sarcoma.

Between 1976 and 1983, 28 patients with Kaposi's sarcoma were treated in the Department of Radiation and Clinical Oncology of the Hadassah University Hospital in Jerusalem. Most of the patients (16, i.e. 57%) were Jews of European origin. Eighteen (64.2%) of the patients presented with severe leg edema in addition to multifocal, disseminated skin lesions. Only one patient was free of clinical disease in the lower extremities. Large, ulcerated masses were seen in three patients. The affected limbs were immersed in a water bath and irradiated with two-opposing portals to a total dose of 3000 rads. Total disappearance of the skin lesions was achieved in 89% of the patients, although the limb edema regressed completely in only 56% of the patients.

Adult↗
PubMed1986

Spectrum of deranged sodium homeostasis in essential hypertension.

Essential hypertension is thought to produce a uniform exaggerated natriuresis and diuresis. Because validation of this formulation in humans is incomplete, the natriuretic and diuretic responses to acute volume expansion were characterized by using water immersion to the neck. This method provides a volume stimulus identical to that induced by 2 L of saline without plasma compositional change. Twenty-seven subjects with essential hypertension were studied on three occasions in the seated posture while in balance on a 10 mEq Na, 100 mEq K diet: during the seated control study, during 4 hours of head-out immersion, and during saline infusion (2 L/2 hours). Four subjects had exaggerated urinary Na excretion in response to neck immersion (Group 3), and 16 had a normal response (Group 2) indistinguishable from that of 15 previously studied normal subjects. The remaining seven subjects (Group 1) had blunted or absent natriuretic responses compared with that in normal subjects (p less than 0.005). Similar results were obtained with saline administration; cumulative Na excretion in Group 1 was markedly less than that in Group 2 and the normal subjects. The heterogeneity in Na excretion indicates that an exaggerated natriuresis is not a uniform concomitant of essential hypertension. The significant inverse correlation between basal plasma aldosterone level and peak urinary as well as cumulative Na excretion suggests that plasma aldosterone constitutes a determinant of the differing natriuretic responses. In contrast to findings with urinary Na excretion, the diuretic responses of Groups 1 and 2 were identical. The striking dissociation between renal Na and water handling underscores the specificity of the derangement in renal Na handling.

Adult↗
PubMed1986

Chronological supplement to the Carcinogenic Potency Database: standardized results of animal bioassays published through December 1982.

This paper is a chronological supplement to our earlier publication, "A Carcinogenic Potency Database of the Standardized Results of Animal Bioassays." We report here results of carcinogenesis bioassays published in Technical Reports of the National Cancer Institute/National Toxicology Program between July 1980 and December 1982, and the general literature between July 1981 and December 1982. This supplement includes results of 280 long-term, chronic experiments of 114 test compounds, and reports the same information about each experiment in the same plot format as the earlier paper: e.g., the species and strain of test animal, the route and duration of compound administration, dose level and other aspects of experimental protocol, histopathology and tumor incidence, TD50 and its statistical significance, dose response, author's opinion about carcinogenicity, and literature reference. While a number of appendices are provided to facilitate use of this supplement, we have not duplicated here the material published earlier. Instead, we refer the reader to the earlier publications (Peto et al. and Gold et al.) for a thorough description of the numerical index of carcinogenic potency (TD50), a guide to the plot of the database, and a discussion of the sources of data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. For 44 of the 114 chemicals reported in this second plot, results of earlier experiments are also given in the first plot; since only 1981-1982 results are reported here, the first plot is required for these repeated compounds. In this paper we also give corrections for errors that appeared in the earlier publication.

Animals↗
PubMed1984

A carcinogenic potency database of the standardized results of animal bioassays.

The preceding paper described our numerical index of carcinogenic potency, the TD50 and the statistical procedures adopted for estimating it from experimental data. This paper presents the Carcinogenic Potency Database, which includes results of about 3000 long-term, chronic experiments of 770 test compounds. Part II is a discussion of the sources of our data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. Part III is a guide to the plot of results presented in Part IV. A number of appendices are provided to facilitate use of the database. The plot includes information about chronic cancer tests in mammals, such as dose and other aspects of experimental protocol, histopathology and tumor incidence, TD50 and its statistical significance, dose response, author's opinion and literature reference. The plot readily permits comparisons of carcinogenic potency and many other aspects of cancer tests; it also provides quantitative information about negative tests. The range of carcinogenic potency is over 10 million-fold.

Animals↗
PubMed1976

Effects of water immersion to the neck on pulmonary circulation and tissue volume in man.

Utilizing the rebreathing of a gas mixture containing C2H2, C180, He O2, and N2, we obtained serial measurements of the pulmonary capillary blood flow (Qc), diffusing capacity per unit of alveolar volume (DL/VA), functional residual capacity (FRC), pulmonary tissue plus capillary blood volume (VTPC), and O2 comsumption (VO2) in five normal subjects under the following conditions: 1) 6 h of sitting, 2) 4 h of sitting while immersed in thermoneutral water to the neck, and 3) 4 h of lying in thermoneutral water to the neck. Water immersion (NI) was preceded and followed by 1-h prestudy and 1-h recovery periods. The measurements were made at 30-min intervals. Seated NI produced a fourfold increase in sodium excretion (UNaV), a 25-36% increase in Qc, a 45-59% increase in DL/VA, and a 30-36% decrease in FRC. This occurred as early as the 1st h of NI and persisted throughout the 4-h period of study. Throughout the seated control and NI periods, VO2, heart rate, and VTPC remained constant. During supine NI, Qc, HR, DL/VA, FRC, and VO2 did not differ significantly from supine prestudy. These date demonstrate that seated NI causes a significant increase of Qc and DL/VA which persists throughout the immersion period. Furthermore, the lack of change of VTPC suggests that the central vascular engorgement induced by seated NI is not accompanied by extravasation of fluid into the pulmonary interstitial space.

Adolescent↗