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Biomedical subjects

C A Johnson

Publications and source records attributed to C A Johnson.

At least 289 records · Page 16Linked to original sources
PubMed1989

Regulation of the cytoplasmic accumulation of 5-methyltetrahydrofolate in MA104 cells is independent of folate receptor regulation.

To better understand how the folate receptor (also known as the membrane folate binder) is able to deliver 5-methyltetrahydrofolic acid to the cytoplasm of folate-depleted MA104 cells, we have examined the kinetics of movement from the cell surface into the cytoplasm. Bound 5-methyltetrahydrofolic acid was transferred into an acid-resistant membrane compartment at the rate of 0.9-1.0 pmol/10(6) cells per h. This folate appeared in the cytoplasm at the same rate. Furthermore, cytoplasmic 5-methyltetrahydrofolic acid became polyglutamated at the rate of 0.6-0.7 pmol/10(6) cells per h. As soon as intracellular 5-methyltetrahydrofolate reached 5-7 pmol/10(6) cells, however, cytoplasmic accumulation was markedly inhibited even though the folate receptor remained functional. Therefore, the acute regulation of 5-methyltetrahydrofolic acid accumulation appears to be achieved by controlling the movement of the vitamin from the receptor into the cytoplasm of the cell.

Animals↗
PubMed1989

Project SMART parent program: preliminary results of a chronic disease risk reduction trail.

Project SMART Parent Program is a school-based healthy lifestyle promotion program designed to reduce chronic disease risk in adults and to provide a health-conscious home environment for children through the adoption of healthy lifestyle by their parents. Parents in the high involvement condition received comprehensive health status appraisals, and a program designed to reduce dietary fat intake, and increase aerobic activity levels. Parents in the low involvement condition received only the comprehensive health status appraisals. ANCOVA, using treatment condition as the independent variable and change scores as the dependent variables, were used to assess program outcomes. At the first posttest measure, the intervention group compared to the control group had a significantly greater decrease in blood cholesterol, a greater gain in aerobic fitness, a greater weight loss, and a greater decrease in body fat. At the second posttest measure, the intervention group had significantly greater gain in aerobic fitness, a greater decrease in body fat, a greater decrease in systolic blood pressure, and a marginally significant decrease in weight. Preliminary results provide strong support for the effectiveness of the Parent Program in reducing chronic disease risks.

Adolescent↗
PubMed1989

Intraperitoneal Vancoled does not cause chemical peritonitis.

A prior report has suggested that loading doses of intraperitoneal Vancoled (vancomycin, Lederle) cause chemical peritonitis in patients with catheter infections. The present open-label study was conducted to determine the effects of a 30 mg/kg intraperitoneal loading dose of Vancoled given to five patients with a culture-positive, erythematous, draining exit-site infection. Prior to dosing, all dialysate was drained and sent for baseline cell count and culture. The loading dose was added to the dialysate and infused in the usual fashion. A sample of dialysate was drained at two hours and sent for cell count and culture. The entire exchange was drained at four hours and also sent for cell count and culture. Serum vancomycin concentrations wer measured at four hours. Baseline dialysate contained less than 9 white blood cells per microliter in all patients. Two and four hour samples contained less than 4 and less than 11 white blood cells per microliter, respectively. All fluid was sterile. WB C differential counts were unremarkable. No adverse effects occurred. The mean serum vancomycin concentration was 26.5 micrograms/ml. Intraperitoneal Vancoled did not cause chemical peritonitis and was well-tolerated by patients with exit-site infections.

Adult↗
PubMed1989

Bartholin's gland cancer.

Bartholin's gland cancer is a rare malignancy that must be considered in the differential diagnosis of a labial mass. The prognosis is generally poor due to the aggressive metastatic tendencies of this cancer. The etiology of Bartholin's gland cancer remains unknown, and no optimal plan of treatment has been established. Early detection followed by radical vulvectomy and bilateral inguinal-femoral node dissection may improve survival.

Adenocarcinoma↗
PubMed1989

Book prices and costs for a small-hospital library: a subject analysis.

An analysis of the Brandon/Hill lists has provided individual price figures to assist the librarian of a small hospital in calculating book costs associated with establishing and maintaining an up-to-date collection suited to institutional needs. For the fifty-three subject categories analyzed, the following were calculated over the past twenty-two years: average price per title, size and cost of the category, number of new titles or editions, percentages price increases, and cost of maintaining a basic collection. Used in conjunction with local purchasing data, these figures can be useful in budget preparation.

Book Prices↗
PubMed1989

Evidence for a neural basis of age-related visual field loss in normal observers.

Many studies have reported a decrease in visual field sensitivity as a function of increasing age in normal individuals. This age-related sensitivity loss has mainly been attributed to reductions in pupil size and transmission losses of the ocular media (particularly the lens), although neural losses in the retina, optic nerve and visual cortex have also been suggested. We evaluated the role of preretinal factors on normal visual field changes associated with aging. The central visual field of both eyes of 62 normal subjects (ages 20 to 72) were evaluated with Program 30-2 of a modified Humphrey Field Analyzer. Three test procedures were employed: (1) a standard visual field evaluation; (2) a yellow target on a yellow background condition (530 nm cutoff filter) to minimize the influence of lens transmission losses with age; and (3) a large target/high background luminance "yellow on yellow" test condition (530 nm cutoff filter, 635 asb background, Size V target) to minimize both pupil size and lens effects on central visual field sensitivity. In addition, relative lens absorption estimates were obtained for each subject. All three test conditions revealed a loss in visual field sensitivity with increasing age (approximately 0.8 dB per decade) but no meaningful differences were found among the three test procedures. Relative lens density increased with age but was not related to visual field sensitivity for any of the three test conditions. These data suggest that normal age-related visual field sensitivity changes are primarily due to neural losses rather than preretinal factors.

Adult↗
PubMed1989

Activity involvement, risk-taking, demographic variables, and other drug use: prediction of trying smokeless tobacco.

Four activity participation variables (clubs, sports, church, and parties); two indices of "risk-taking" (preference for risk-taking, getting into trouble at school); three demographic variables (sex, ethnic group, socioeconomic status); and two drug use variables (trial of cigarettes and alcohol) were examined as correlates and prospective predictors of trial of smokeless tobacco in two cohorts of seventh graders in urban Los Angeles. The data were analyzed separately for males and females. Cross-sectional logistic regression analyses indicated that correlates of trying smokeless tobacco among the seventh-grade cohorts or among these same cohorts in the eighth grade (considering those persons who had not tried smokeless tobacco in seventh grade) generally included being white, trying cigarettes, risk-taking, and attending parties. Prospective logistic regression analyses with data from subjects who had not tried smokeless tobacco in the seventh grade indicated that predictors of subsequent trial of it generally included only being white and having tried cigarettes. Sports participation predicted onset only in one cohort of female subjects but not in males. Some activities that have been proposed as being predictive of smokeless tobacco use (e.g., sports participation) are generally irrelevant for a large sample of young adolescents in urban Los Angeles. White male cigarette smokers, regardless of the activities they have engaged in, are most likely to try smokeless tobacco.

Adolescent↗
PubMed1989

Substance use among eighth-grade students who take care of themselves after school.

This investigation focused on substance use among children who regularly care for themselves after school (latchkey children). The data, collected from 4932 eighth-grade students, indicated that self-care is an important risk factor for alcohol, tobacco, and marijuana use. Data collected from 2185 parents validated these findings. Eighth-grade students, who took care of themselves for 11 or more hours a week, were at twice the risk of substance use as those who did not take care of themselves at all. This relationship held at all levels of sociodemographic status, extracurricular activities, sources of social influence, and stress. Of the 186 stratified tests of the relationship, 90% were significant; even those not found to be significant were in the direction expected. Path analyses suggest that risk-taking, having friends who smoke, and being offered cigarettes may partially explain the relationship between self-care and substance use. Those eighth-grade students who select friends who smoke and place themselves in situations in which they are offered cigarettes may be manifesting a desire to display their sense of maturity and independence. The fact that the increase in substance use occurred among almost all strata tested and the fact that mediation was not complete suggest that more than one mechanism may account for the associated increase in substance use. It is also possible that more time in self-care results in more unnoticed solitary trials of substances, as well as trials motivated by peer offers or peer pressure to use substances.

Adolescent↗
PubMed1988

Efficacy of clindamycin in the treatment of Staphylococcus aureus osteomyelitis in dogs.

The efficacy of clindamycin in the treatment of experimentally induced, posttraumatic Staphylococcus aureus osteomyelitis was studied in dogs. At the end of the experiment, bacteria could not be isolated from bone marrow of 15 of 16 (93.7%) dogs treated with clindamycin, whereas bacteria could not be isolated from similar specimens obtained from 6 of 13 (46.1%) untreated dogs. None of the 16 dogs treated with clindamycin had histopathologic evidence of osteomyelitis at the end of the experiment. Five of the 13 untreated control dogs had histopathologic evidence of osteomyelitis. The recovery rate was 31% in untreated dogs, whereas 94% of dogs treated with clindamycin recovered from osteomyelitis. Clindamycin, 11 mg/kg of body weight, given orally, q 12 h, for 28 days, was efficacious in the treatment of experimentally induced, posttraumatic S aureus osteomyelitis in dogs.

Animals↗
PubMed1988

Circulating megakaryocytes and platelet production in children with congenital cardiac defects undergoing cardiac catheterisation.

The literature has recently focused attention on the lung as a source of platelet production. Thirty-two children with normal lungs admitted to hospital for investigation of congenital heart disease were studied with the intention of showing a relationship between left atrial platelet counts and pulmonary blood flow. This was not demonstrated. Mean platelet counts were 296 X 10(9)/l (right atrium) and 304 X 10(9)/l (left atrium). There was no significant difference between the two results. It is suggested that previous studies were performed on subjects with significant acquired disease and that in young children with no pulmonary disease the lung is not a major source of platelet production.

Cardiac Catheterization↗
PubMed1988

The television school and family smoking prevention and cessation project. 1. Theoretical basis and program development.

Program development processes for the Television, School, and Family Project, a school-based smoking prevention and cessation project, are presented in this article. We first review applications of social-psychological and communications theory to school-based and mass media program development. These include the three broad areas of (a) mediators of mass media effects on behavior change, (b) the social influences approach to smoking prevention, and (c) a self-management and social support approach to smoking cessation. A program development model for school-based mass media efficacy trials, with a summary of formative research and pilot study processes, is then presented. The importance of reciprocal support among school district administrators, project research staff, and television station personnel is emphasized with recommendations for future research and demonstration efforts.

Adolescent↗
PubMed1988

Affective and social influences approaches to the prevention of multiple substance abuse among seventh grade students: results from project SMART.

Two drug abuse prevention curricula were tested to determine their efficacy in preventing the onset of tobacco, alcohol, and marijuana use among adolescents. The first program focused on prevention through social pressure resistance training. The second featured affective education approaches to prevention. Curricula were tested on seventh grade students. Subjects were pretested just prior to the program and were post-tested at 12 and 24 months. Post-test analyses indicated that the social program delivered to seventh grade subjects was effective in delaying the onset of tobacco, alcohol, and marijuana use. No preventive effect of the affective education program was observed. By the final post-test, classrooms that had received the affective program had significantly more drug use than controls.

Adaptation, Psychological↗
PubMed1988

Evaluation of the t test as a method of detecting visual field changes.

Automated perimetry is used to monitor changes associated with many ocular conditions such as glaucoma, neuro-ophthalmologic disorders, and retinal diseases. Comparisons among sequential visual fields are crucial to the determination of progression or regression of ocular anomalies, and to evaluate the efficacy of various therapeutic regimens. The Delta program for the Octopus perimeter uses a t test to provide an objective comparison of visual fields. To evaluate the utility of the t test for detecting visual field changes, the authors used computer simulation to generate pairs of visual fields with known alterations, and made comparisons with the t test procedure used by the Delta program. An initial visual field based on normal data was produced and stored. A second visual field, based on the same normal data but with a scotoma of known size and depth, was also produced and stored. A t test (as used by the Delta program) was then used to compare the two visual fields for statistically significant differences. Our results indicate that the t test was very sensitive to small changes of the entire visual field, such as those produced by both pathologic and nonpathologic (day-to-day sensitivity variations, changes in pupil size, etc.) factors. However, the t test was unable to reliably detect small to moderate scotomata (less than or equal to 18 degrees in diameter), even when the sensitivity loss was greater than 35 dB. These findings suggest that the t test has limited clinical utility for objective detection of pathologic visual field loss, and that additional procedures may be necessary to provide reliable detection of visual field changes.

Adult↗
PubMed1988

The effect of Goldmann applanation tonometry on automated static threshold perimetry.

Automated static threshold perimetry was performed in both eyes of 10 normal and 12 ocular hypertensive subjects treated with a topical beta-blocker, before and after Goldmann applanation tonometry of their right eyes. Both objective statistical comparison and subjective evaluation of the resultant visual fields showed no detrimental effect on visual field test results after applanation tonometry.

Adrenergic beta-Antagonists↗