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Biomedical subjects

K L Jackson

Publications and source records attributed to K L Jackson.

At least 55 records · Page 3Linked to original sources
PubMed1990

A longitudinal study of depressive symptomatology in young adolescents.

As part of a longitudinal study of depression in adolescents, the Center for Epidemiologic Studies Depression Scale (CES-D) was administered to 550 students 3 times, at the beginning of the seventh, eighth, and ninth grades. Blacks and females had higher scores than did whites and males. Scores of blacks and males declined more over the 3 year period than did those of females and whites. The stability of individual students' depression scores was less consistent than the overall distributions with 1 and 2 year correlations reaching only 0.53 and 0.36, respectively. The best predictor of subsequent year CES-D scores was the previous year's score. Undesirable life events and family adaptability were significant but less important predictors.

Adolescent↗
PubMed1990

Kidney and lung injury in irradiated rats protected from acute death by partial-body shielding.

Ninety-six CD-1 male rats were exposed to gamma-ray doses (0-25 Gy) in increments of 5 Gy. One femur, the surgically exteriorized GI tract, and the oral cavity were shielded during irradiation to protect against acute mortality from injury to the hematopoietic system, small intestine, and oral cavity. In addition, the thoraxes of half of the animals from each dose group were shielded. At approximately monthly intervals from 2 to 10 months after irradiation the hematocrit, plasma urea nitrogen (PUN), and 51Cr-EDTA clearance were measured. During the study 20 thorax-shielded and 19 thorax-irradiated animals died. All rats whose thoraxes received 25 Gy irradiation and three out of seven rats whose thoraxes received 20 Gy died 1 to 3 months postirradiation with massive pleural fluid accumulation. Shielding the thoraxes prevented this mode of death at these doses. Kidney injury was judged to be the primary cause of death of all thorax-shielded animals and 15- and 20-Gy thorax-irradiated animals. Animals with kidney damage had elevated PUN and reduced 51Cr-EDTA clearance and hematocrits. The relative merits of each of these end points in assessing radiation-induced kidney injury after total-body exposure are discussed.

Animals↗
PubMed1990

Distribution of major dementias by race and sex in South Carolina.

Preliminary data from the newly implemented Registry for dementing illnesses was used to examine the distribution of four types of dementia in black and white residents of South Carolina. The data for 1464 subjects were abstracted by field research nurses in state mental health facilities. Overall, 649 patients (44.3%) were black and 765 (52.3%) were white. Women comprised 53.8% of all cases of dementia in this study. The overall distribution included 66% Alzheimer's disease (AD), 12% multi-infarct dementia (MID), 10% alcoholic dementia (ALC), nine percent other-medical and three percent other-unspecified. Though the proportion of blacks does not exceed one-third of the total population of S.C., blacks comprised 44.3% of all cases of dementia. AD accounted for 79% of all cases of dementia in women, but only 51% of such cases in demented men, who showed an apparent preoponderance of MID and alcoholic dementia. The frequency distribution of MID was equal in blacks and whites. Educational level had no discernible effects. Though not directly comparable, these preliminary findings are similar to those of the Copiah County Study, including a higher frequency of AD with advancing age.

Aged↗
PubMed1989

Age, physical activity, physical fitness, body composition, and incidence of orthopedic problems.

The incidence of orthopedic problems was examined in 5,582 men and women who attended the Cooper Clinic in Dallas, Texas between 1974 and 1982. The effects of age, physical activity, physical fitness, and body mass index (BMI) on the occurrence of these problems were examined using a proportional hazards approach. The expected risk of orthopedic problems per person-year was 0.045 for men and 0.046 for women. For men, physical fitness, BMI, and physical activity were associated with orthopedic problems, while for women, physical activity was the main predictor. Age was not a factor for either gender. The effect of change in physical fitness, physical activity, and BMI was examined in a subset of 2,325 persons with more than one visit to the clinic. For women, physical activity and a decrease in BMI were associated with orthopedic problems, while for men none of those factors were significant. Again, age was not a factor in either group. The absence of any age effect on the occurrence of problems suggests that with regard to orthopedic problems, moderate amounts of physical activity in generally healthy persons may be recommended without special consideration as to age.

Adolescent↗
PubMed1989

Knowledge, perceived risk, and beliefs about AIDS among high school and college students in South Carolina.

Our study reveals that high school and college students in South Carolina have a fairly high level of knowledge about AIDS. High school students have lower level of knowledge about AIDS than college students. High school students also have higher perception of risk of acquiring HIV infection and do not consider the AIDS epidemic as a very serious health threat. School-based AIDS education is critically needed to increase students' knowledge about AIDS and to develop skills which will help them adopt and maintain risk prevention behaviors. Physicians play a very important role in developing effective school-based AIDS education and prevention programs.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Predicting lower-extremity injuries among habitual runners.

This prospective study of 583 habitual runners used baseline information to examine the relationship of several suspected risk factors to the occurrence of running-related injuries of the lower extremities that were severe enough to affect running habits, cause a visit to a health professional, or require use of medication. During the 12-month follow-up period, 252 men (52%) and 48 women (49%) reported at least one such injury. The multiple logistic regression results identified that running 64.0 km (40 miles) or more per week was the most important predictor of injury for men during the follow-up period (odds ratio = 2.9). Risk also was associated with having had a previous injury in the past year (odds ratio = 2.7) and with having been a runner for less than 3 years (odds ratio = 2.2). These results suggest that the incidence of lower-extremity injuries is high for habitual runners, and that for those new to running or those who have been previously injured, reducing weekly distance is a reasonable preventive behavior.

Adolescent↗
PubMed1988

Changing health practices: the experience from a worksite health promotion project.

This paper uses data from an employee health promotion project for government employees to examine initial health practices and their relationship to social and demographic variables. It then uses data collected one year later to examine changes in health behaviors and to try to explain what types of people are most likely to undertake health behavior changes in a year, within the context of a worksite health promotion project. Most people in this sample of employees do make positive changes in health habits in at least one of the following areas: smoking, seatbelt usage, diet, exercise, alcohol usage. While a variety of different social and demographic variables are important in explaining initial differences in health practices, these same variables along with measures of personal efficacy and job stress are poor predictors of whether people change their health behavior over a year. Future research might usefully focus on more detailed collection of qualitative data to help understand what factors motivate people to change health behavior. Future survey approaches may then incorporate broader and more diverse categories of explanatory variables into regression models.

Adolescent↗
PubMed1988

The use of proportional hazards regression in investigating dropout rates in a longitudinal study.

One difficulty with the interpretation of data from longitudinal studies is the bias associated with those who do not complete the study. In a 12-month study on the occurrence of musculoskeletal problems in 966 runners (583 of whom completed the study), a proportional hazards model with time-dependent covariates was used to assess factors associated with dropout at the various stages of the study. This approach allowed examination of baseline factors as well as the effect of change in mileage, the occurrence of a musculoskeletal problem, or the occurrence of another health problem on the rate of dropout. Those most likely to drop out of the study were younger and heavier at baseline and, prior to drop out, were less likely to experience general health problems and more likely to show a 40% decline in weekly running mileage in the month before dropout. Examination of factors associated with dropout is important since factors influencing dropout may also affect the study outcome for the risk factor analysis (a musculoskeletal problem severe enough to be seen by a physician). The results of the dropout analysis can be used to guide in the choice of analytic methods and to aid in the interpretation of the risk factor analyses.

Adult↗
PubMed1987

Determinants of participation in worksite health promotion activities.

A model of risk factors and psychosocial variables that should enhance the prediction of participation in worksite health promotion programs was evaluated in a sample of 357 States employees in South Carolina. Degree of satisfaction with one's current health status, intent to change it, and participation in a relevant program were assessed in four health areas: weight, exercise, alcohol consumption, and the handling of stress and tension. In each area, a known risk factor was used to predict intent to change and participation during a one-year interval. Variables from the psychosocial model were added in a step-wise regression procedure. The key variables in the psychosocial model were personal efficacy, job stress, and trait anxiety. Neither intent to change a health relevant behavior nor degree of satisfaction with the health area were consistently associated with subsequent participation in a relevant health promotion program. The regression model was a statistically significant predictor of actual participation in two cases: exercise and weight control. For exercise, participators tended to be persons whose job stress was high (r = 0.15) and whose anxiety was high (r = 0.16). In the case of weight control, those who were high in the body mass index (r = 0.22) and in job stress (r = 0.15) were more likely to participate. Participants in stress management also had higher levels of job stress.

Adolescent↗
PubMed1987

Fluid and sodium loss in whole-body-irradiated rats.

Whole-body and organ fluid compartment sizes and plasma sodium concentrations were measured in conventional, GI decontaminated, bile duct ligated, and choledochostomized rats at different times after various doses of gamma radiation. In addition, sodium excretion was measured in rats receiving lethal intestinal radiation injury. After doses which were sublethal for 3-5 day intestinal death, transient decreases occurred in all the fluid compartments measured (i.e., total body water, extracellular fluid space, plasma volume). No recovery of these fluid compartments was observed in rats destined to die from intestinal radiation injury. The magnitude of the decreases in fluid compartment sizes was dose dependent and correlated temporally with the breakdown and recovery of the intestinal mucosa but was independent of the presence or absence of enteric bacteria or bile acids. Associated with the loss of fluid was an excess excretion of 0.83 meq of sodium between 48 and 84 h postirradiation. This represents approximately 60% of the sodium lost from the extracellular fluid space in these animals during this time. The remaining extracellular sodium loss was due to redistribution of sodium to other spaces. It is concluded that radiation-induced breakdown of the intestinal mucosa results in lethal losses of fluid and sodium as evidenced by significant decreases in total body water, extracellular fluid space, plasma volume, and plasma sodium concentration, with hemoconcentration. These changes are sufficient to reduce tissue perfusion leading to irreversible hypovolemic shock and death.

Amine Oxidase (Copper-Containing)↗
PubMed1987

Bile loss in the acute intestinal radiation syndrome in rats.

The effects of bile duct ligation (BDL), choledochostomy, bile acid sequestering within the intestinal lumen by cholestyramine, and fluid and electrolyte replacement on survival time and development of diarrhea after whole-body exposure to doses of ionizing radiation that result in death from acute intestinal injury were studied. BDL significantly prolonged survival and delayed the onset of diarrhea after exposure to 137Cs gamma rays, fission neutrons, or cyclotron-produced neutrons in the range of doses that produce intestinal death or death from a combination of intestinal and hematopoietic injuries. Cannulation of the bile duct with exteriorized bile flow (choledochostomy) to protect the irradiated intestine from the mucolytic action of bile salts did not duplicate the effect of BDL in increasing survival time. Choledochostomy without fluid replacement eliminated the occurrence of diarrhea in 15.4 Gy irradiated rats. Diarrhea did occur in irradiated animals with choledochostomy if they received duodenal injections of fluid and electrolytes to replace the fluid lost as a result of bile drainage. Duodenal injection of fluid and electrolytes, however, had no significant effect on survival time in irradiated rats. In contrast, injection of fluid and electrolytes into the peritoneal cavity of irradiated rats resulted in an increase in survival time that was comparable to that observed after BDL. Addition of antibiotics to the peritoneally injected fluid and electrolytes further increased survival time (up to 9 days). This survival time approached that seen in animals receiving the same radiation dose but which had the intestine exteriorized and shielded to minimize radiation injury to the intestine. Postmortem histological examinations of the irradiated small intestine showed mucosal regeneration in these long-term survivors receiving fluid and antibiotic therapy. In contrast, duodenal injection of cholestyramine post irradiation to bind bile acids had no effect on survival time or diarrhea incidence. The conclusions from these experiments are that BDL prolongs survival and postpones the onset of diarrhea in irradiated rats dying from acute intestinal injury primarily by slowing down the loss of fluid and electrolytes and that bile acids play no significant role.

Animals↗
PubMed1986

Logistic analysis of risk factors in acute retinopathy of prematurity.

In a prospective study of 328 high-risk neonates, we used computer-assisted logistic regression of 47 potential risk factors to study acute retinopathy of prematurity. Only four factors were significant in the logistic regression equation: ventilator hours, xanthine administration, birthweight, and maternal bleeding. Xanthine administration was identified as a new independent and significant (P less than .0001) predictor of acute retinopathy of prematurity.

Female↗
PubMed1986

(-)[125I]iodopindolol binding to beta-adrenergic receptors in tissues of the rat with particular reference to the characterization in liver.

The high affinity beta-adrenergic antagonist (-)[125I]iodopindolol was used to characterize and quantitate beta-adrenergic binding in liver and other tissues of the rat. Saturable, stereospecific binding with typical characteristics of beta-adrenergic receptors was demonstrated in all tissues examined (liver, lung, heart, kidney, fat and brain). Unlike the case with other radioactive ligands that have been used to measure beta-adrenergic receptors, assays were possible in crude homogenates as well as in purified membranes. Specific binding was defined as [125I]iodopindolol displaced by 0.1 mM isoproterenol. The percentage of [125I]iodopindolol specifically bound was greater than with other labelled antagonist ligands and it ranged from 95-60% of total binding over [125I]iodopindolol concentrations of 15-1000 pM. beta-Adrenergic binding could be quantitated in liver of animals of all ages whereas previously quantitation in liver was possible only using rats less than 2 months of age. Binding capacities ranged from a low of approximately 6 fmol/mg in liver particles precipitated at 4500 g to approximately 550 fmol/mg in 4500 g lung particles. The Kd of binding obtained by kinetic analysis was similar in all tissues. [125I]Iodopindolol is a nearly ideal ligand for the quantitation of beta-adrenergic receptors in various tissues of the rat. Because of its high affinity, stability and availability at high specific activity, this ligand should be especially useful in physiological studies requiring the accurate quantitation of receptor capacities.

Adrenergic beta-Agonists↗
PubMed1985

The risk of low birth weight. Alternative models of neonatal mortality.

The authors examine the use of the infant's weight at birth to estimate its risk of mortality by the 28th day of life. The performance of several commonly employed statistical models is compared for the population of single births to resident South Carolina mothers in 1975-1980. A log-linear function, fitting the natural logarithm of the probability of neonatal mortality to birth weight, performs far better in this analysis than a quadratic or a logistic model or a model using the logarithm of the probability of survival. The parsimonious log-linear model also appears preferable to more complex models with additional parameters. The authors use the model in an analysis of data in two-year periods to demonstrate its value as an indicator of underlying changes in neonatal prospects and its easily interpreted parameters. The results highlight the importance of changes in neonatal mortality affecting low birth weight infants, which produce a noticeable shift in the range in which low birth weight is associated with the risk of mortality. These have proven more important in accounting for the decline in mortality rates than have changes affecting only neonates with more typical birth weights in South Carolina in 1975-1980.

Birth Certificates↗