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Biomedical subjects

D Johnson

Publications and source records attributed to D Johnson.

At least 595 records · Page 33Linked to original sources
PubMed1986

Effects of a corporate health promotion program.

The effects of a pilot health promotion program at AT&T Communications were evaluated. The study group was given an initial health risk appraisal and offered health education modules. A control group was given the health risk appraisal with no modules; a second control group was neither given the health risk appraisal nor offered modules. The health promotion program was found to lower health risks and improve health-related and job-related attitudes among the study group. Participants in specific intervention modules experienced gains in positive health behaviors.

Attitude to Health↗
PubMed1986

Three-channel color generator for vision research.

A simple, relatively inexpensive technique for adequate stimulation of the visual system is described. A combination of continuous interference filters and light fibers in one compact instrument allows individual stimulation of the color channels with narrow band light in mosaic or homogeneous compositions. Effectively all parameters of stimulation may be separately controlled and used for studies of Psycho- and Neurophysiology.

Color↗
PubMed1986

The effects of various substituted hydrocarbons on two heme synthesis regulatory enzymes.

Benzene and some of its derivatives have been shown to cause alterations in heme and globin synthesis. Structure/activity relationships of the effects of substituted aromatic hydrocarbons on delta-aminolevulinic acid synthetase (ALAS) and ferrochelatase (FC) activities were studied. These enzyme systems were studied because they were regulatory and represented the initial and final enzymes in the biosynthesis of heme. Normal values for rat liver ALAS were 250-350 microM ALA/g protein/30 min, mean 293 microM/g +/- 44 (SD). Normal values for FC were 12-40 microM heme/g protein/45 min, mean 18 microM/g +/- 0.7 (SD). Nitrosonaphtholics inhibited ALAS activity an average of 49%; nitrosobenzenes, 48%; chloronitrobenzoic acids, 39%; phenol, 37%; nitrophenols, 22%; aminophenols, 16% and chlorophenols, 5%. Certain compounds inhibited FC activity: nitrosonaphtholics, 99%; chlorophenols, 56% and nitrosobenzenes, 3%. Some compounds that significantly inhibited ALAS activity enhanced FC activity, e.g. phenolic compounds and chloronitrobenzoic acids. The inhibitory effect may reflect a blockage of the active site of the enzymes and/or binding of a required substrate. The enhancing effect may be due to making the binding site of the heme pocket of the porphyrin more accessible to iron. These techniques may prove useful for assessing toxicity of pollutants in animal species.

5-Aminolevulinate Synthetase↗
PubMed1986

[The effect of cardiac glycosides on the visual system of man measured with cortical evoked potentials].

The effect of beta-acetyldigoxin (Novodigal) on color vision in normal, healthy subjects was studied using cortical evoked potentials. Initial results indicate a significant latency increase of one component of the visual evoked potential (VEP) and a dose dependency following a change of color from blue to red. The Farnsworth-Munsell-100-Hue test, however, showed no significant changes in color vision. It is postulated that the VEP is an even more sensitive measurement of color vision than subjective tests are.

Acetyldigoxins↗
PubMed1985

Phenotypic and functional analysis of T cells cloned directly from the blood and cerebrospinal fluid of patients with multiple sclerosis.

A single-cell cloning technique was used to analyze both phenotype and function of individual T cells in patients with multiple sclerosis (MS). Blood and cerebrospinal fluid (CSF) lymphocytes were plated at 1 cell per well, stimulated with phytohemagglutinin followed by interleukin 2, and expanded to 3 X 10(6) cells per "clone." More than 90% of the T8 clones generated from patients with MS and controls in both blood and CSF were cytotoxic precursors. There was also a slight decrease in cytotoxic T4 clones in the blood of patients with MS. The cytotoxic precursor frequencies of T cells in the CSF generally reflected those in the blood. In separate experiments, antigen reactivity was examined in lines established from blood or CSF. No reactivity to myelin basic protein or white matter was found in patients with MS or controls. Myelin basic protein-reactive clones could, however, be generated after first stimulating lymphocytes with antigen before cloning. These results suggest that changes in the T8 population from the blood of patients with MS involve cytotoxic as well as suppressor cells. Sequestration of myelin basic protein- or white matter-reactive T cells was not seen in the CSF of patients with MS, unlike reports of viral meningoencephalitis, in which large numbers of antigen-specific cells were found in the CSF. Direct single-cell clonal analysis of the CSF should provide a more sophisticated approach to the study of T cell abnormalities in patients with MS.

Brain↗
PubMed1985

A derivative of myelin-associated glycoprotein in cerebrospinal fluid of normal subjects and patients with neurological disease.

A procedure for quantitating the myelin-associated glycoprotein (MAG) in cerebrospinal fluid (CSF) was developed. The procedure involved immunoprecipitation with rabbit polyclonal anti-MAG antiserum followed by immune staining of electroblots with the monoclonal antibody HNK-1. This method could detect as little as 2 ng of MAG per ml of CSF and could accurately measure levels of 5 ng/ml or greater. No intact MAG was detected in any of the CSF samples examined, but all samples contained the 90K dalton proteolytic derivative of MAG called dMAG. Samples from normal volunteers and patients with demyelinating diseases contained levels of dMAG ranging from 2 to 13 ng/ml. There was no correlation of dMAG levels with levels of myelin basic protein or with active demyelinating disease. The relatively high levels of dMAG, even in control CSF samples, probably resulted from normal physiological turnover of MAG and could possibly obscure any additional increments of MAG or dMAG release that might occur as a result of demyelination.

Demyelinating Diseases↗
PubMed1985

Use of discriminative models of Pseudomonas aeruginosa bacteremia in granulocytopenic rats for testing antimicrobial efficacy.

The efficacy of single agent and combination antibiotic therapy was evaluated in rats with severe granulocytopenia and Pseudomonas aeruginosa infection using animal survival, rates of bacteremia and the emergence of resistant organisms as criteria. In this model end points following single agent therapy with imipenem/cilastatin and the synergistic combination of moxalactam plus amikacin were comparable. At a high bacterial challenge dose, equivalent results were obtained using single agent therapy with either piperacillin or ticarcillin. Results were also similar following therapy with piperacillin or ticarcillin in synergistic combination with amikacin. At a lower bacterial challenge dose, aminoglycoside therapy was superior to therapy with the beta-lactams. Therapy with the in vitro synergistic double beta-lactam combination of ceftazidime plus piperacillin was no more effective than therapy with the individual compounds. Results from these studies in this discriminative animal model have in part been used to formulate prospective clinical antibiotic studies in granulocytopenic cancer patients.

Animals↗
PubMed1985

Increased IgG secretion by unstimulated mononuclear cells in active multiple sclerosis and functional assessment of the T8 subset.

Unseparated mononuclear cells (10(5) cells/well) were cultured both in the presence and absence of pokeweed mitogen (PWM), and IgG secretion was measured by radioimmunoassay. In unstimulated cultures, levels of IgG secretion were found to be higher in a group of patients with multiple sclerosis (MS) than in control groups of healthy individuals or patients with other neurologic diseases (OND). By contrast, PWM-induced IgG secretion was similar in MS patients and in controls. In MS patients, levels of IgG secretion greater than 2500 ng/ml in unstimulated cultures were present in 29 (58%) of 50 patients with active disease and in only 3 (14%) of 21 patients with inactive MS (P less than 0.01; MS active vs inactive). Furthermore, levels of IgG secretion in unstimulated cultures were higher in patients who had abnormalities of circulating T-cell subsets consisting of reduced numbers of suppressor/cytotoxic (T8) cells and elevated helper:suppressor (T4:T8) ratios. In additional experiments using isolated populations of T-cell subsets, T8 cells from MS patients who had low percentages of circulating T8 cells were found to suppress PWM-induced IgG secretion by autologous cells to a similar extent as controls, suggesting that in vitro, T8 cells function normally in these patients. In vitro IgG secretion by unstimulated mononuclear cells in MS appears to be a further reflection of abnormal immune regulation in this disease.

Antibody Formation↗
PubMed1985

Left ventricular diastolic function in a population of healthy elderly subjects. An echocardiographic study.

Diastolic left ventricular function was comparatively assessed in 19 healthy elderly individuals (mean age 71 years) and in 20 young normal subjects (mean age 26 years), using digitized echocardiograms. Peak and average filling rates were slower in the group of elderly subjects than in the younger population (128 +/- 26 and 75 +/- 11 v 182 +/- 37 and 92 +/- 17 mm per second, respectively, P less than .001). The duration of the rapid filling phase and the time to peak filling rate were significantly longer in the older than in the younger population (207 +/- 39 and 125 +/- 21 v 174 +/- 38 and 90 +/- 26 ms, respectively, P less than .01). The atrial contribution to total ventricular filling was 18 +/- 6% in the elderly and 10 +/- 3% in the young (P less than .001). The group differences of most of these measurements of diastolic function retained statistical significance after correction for heart rate. Measurements of left ventricular systolic function were similar in both age groups. The authors conclude that aging is associated with a decline of left ventricular compliance, unrelated to heart rate or systolic performance. The contribution of atrial contraction to ventricular filling is quantitatively larger in elderly individuals.

Adult↗
PubMed1985

Immunocytochemical and biochemical characterization of the connective tissue component of fibrous papular lesions of oral mucosa.

In an attempt to define the fibroblastic components of fibrous papular lesions of oral mucosa, 21 cases representing these lesions were selected for study. Paraffin or frozen sections of the lesions were stained, using the immunoperoxidase technique, with antibodies to: alpha-l-antitrypsin, alpha-l-antichymotrypsin, lysozyme, fibronectin, actin, myosin, and for Clq binding. Three of these cases were biochemically analyzed for collagen Types I, III, and V. This study demonstrated the presence of cytochemical markers in fibrous papules that were similar to those observed for the compartment of circumvascular fibroblasts in control normal mucosa. Analysis of the collagens present indicated that in addition to histologic similarities, the gene products of these extracellular matrices were similar to those reported for angiofibromas and Shagreen patches in tuberous sclerosis. The cells in these lesions appear to be distinct from myofibroblasts and the high affinity complement binding fibroblasts characterized by Bordin et al.(1).

Cell Division↗
PubMed1985

Electron microprobe analysis of human labial gland secretory granules in cystic fibrosis.

X-ray microanalysis of freeze-dried labial gland cryosections revealed that Na concentration was doubled and the Ca/S concentration ratio was decreased in secretory granules of labial glands from patients with cystic fibrosis (CF) when compared with glands from normal subjects. Other results suggested that the decrease in the Ca/S concentration ratio resulted from an increase in S concentration. These findings imply that mucous granules in labial saliva showed a CF-related increase in Na and S content, and such changes would be expected to affect the rheology of the mucus after exocytosis. In contrast with a previous study in human parotid glands, no evidence was found for CF-related changes in cytoplasmic or nuclear Na, K, and Ca concentrations. Significant elemental differences were found between secretory granules and nuclei and cytoplasm of control cells.

Adolescent↗
PubMed1985

Aggregation of insulin, containing surfactants, in contact with different materials.

The aggregation of insulin and of insulin protected with surfactants was studied by shaking at 37 degrees C in glass, in polypropylene and polystyrene vials, and in CPI and Auto-Syringe insulin syringes and infusion sets. Surfactants such as Pluronic 17R8 and 25R5 hastened the aggregation, whereas Pluronic F68 was effective in preventing it. Furthermore, there was no change in the immunoreactivity of insulin containing Pluronic F68 even after 8 days of shaking. Unprotected insulin aggregated in all the vials. There appears to be little problem with the commercial syringes tested, but the infusion sets could cause aggregation of insulin if used over an extended period of time. Although Pluronic F68 prevented insulin aggregation in situ, it extracted more impurities from the contacting plastics. Further development in materials and design of insulin sets and insulin containers appears necessary.

Chemical Phenomena↗