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Biomedical subjects

C A Mitchell

Publications and source records attributed to C A Mitchell.

At least 217 records · Page 12Linked to original sources
PubMed1979

Cyanide-insensitive, Salicylhydroxamic Acid-sensitive Processes in Potentiation of Light-requiring Lettuce Seeds.

Phytochrome-mediated germination of Lactuca sativa L. cv. Waldmann's Green seeds was inhibited strongly by 10 millimolar salicylhydroxamic acid (SHAM), but only slightly delayed by the same level of KCN. SHAM was most effective if applied within the 8-hour potentiation period (release from dormancy) following red light treatment, but much less effective with completely potentiated seeds. SHAM at 3 millimolar actually hastened completion of potentiation, whereas concentrations of 6.6 millimolar or higher retarded the process. A temporary upsurge of O(2) consumption was particularly evident during the period of most rapid potentiation (3 hours after red light), especially in the seed sections containing the embryonic axis. The embryonic axis obtained from dormant seeds also contained most of the SHAM-sensitive O(2) uptake. However, 8 hours of potentiation caused loss of SHAM sensitivity from axes and a simultaneous gain of SHAM sensitivity by cotyledons. Concomitant with this increased sensitivity to SHAM, O(2) uptake by cotyledonary tissues lost some sensitivity to KCN. Red light-stimulated metabolic processes leading to germination were blocked more effectively by SHAM than by KCN, but O(2) consumption by both dormant and nondormant seeds was much less sensitive to 10 millimolar SHAM than to the same concentration of KCN. This apparent contradiction between effects of SHAM on potentiation and O(2) uptake may be a result of: (a) compensatory electron flow through the cytochrome pathway at the expense of the alternate pathway; (b) a functional site of action of SHAM that differs from the organized, energy-coupled respiratory system; or (c) a combination of these possibilities.

Journal Article↗
PubMed1976

Community studies of lung disease in Connecticut: organization and methods.

We have obtained data on respiratory symptoms, enviornmental exposures, and lung function in 3730 residents, aged seven years and over, of a rural and an urban community in Connecticut. We used newly developed computerized techniques of data acquisition. The respondents represent 66.3% of the total populations available for study in the defined geographic areas (75.2% in the rural and 54.7% in the urban community). Door-to-door surveys in defined areas within each community provided information on the nonrespondents. Data on 92% of all residents were obtained in the door-to-door survey areas. Comparisons of respiratory symptoms and smoking habits between respondents and nonrespondents in the door-to-door survey areas, and between respondents living in the door-to-door survey areas and elsewhere in the two towns, led to the conclusion that the data on the respondents are an accurate reflection of the lung disease experienced by the total populations of the two communities.

Adolescent↗
PubMed1976

Lung function among black and white children.

Racial differences in ventilatory lung function were evaluated in a community study of 393 children (158 blacks, 235 whites). Mean forced vital capacity was 18 per cent larger in nonsmoking white males than in nonsmoking black males, and 11 per cent larger in nonsmoking white females than in nonsmoking black females. Similar differences were observed for the 1-sec forced expiratory volume and for the maximal expiratory flow at 50 per cent of the vital capacity. However, when adjusted for lung size (on the basis of forced vital capacity), 1-sec forced expiratory volume and maximal expiratory flow at 50 per cent of the forced vital capacity were larger in the black children compared to the white children. Lung function prediction equations based on race, sex, age, height and weight are presented for healthy nonsmoking children; these allow for an evaluation of normal lung function in both black and white children.

Adolescent↗
PubMed1976

Exposure to pesticides in agriculture: a survey of spraymen using dimethoate in the Sudan.

There is a need for objective data on the exposure of spraymen to pesticides in agriculture in order to assess minimum requirements for practicable protection in tropical areas. To provide data, a survey was carried out in the Sudan on spraymen using dimethoate. No cholinesterase depressions were found and the calculated dose received by each man per day was within safe limits in the circumstances of this survey. Respiratory exposure was only a minor part of total exposure. The methodology of such surveys is discussed and the need for the use of a standard protocol is emphasized.

Adult↗
PubMed1975

Airway disease caused by phenolic (phenol-formaldehyde) resin exposure.

A standardized respiratory questionnaire and pulmonary function tests, including measurement of forced vital capacity (FVC), one-second forced expiratory volume (FEV1.0), and maximum expiratory flow rate at 50% FVC (MEF50%), were administered to five groups of employees in a filter-manufacturing plant to determine the acute and chronic effects of exposure to phenolic resin fumes. Employees exposed for more than five years had lower FEV1.0/FVC and MEF50%/FVC ratios than a group that had smoked more but that had never been consistently exposed to resin fumes. The existence of chronic airway obstruction was also evident by a slight excess of chronic cough and sputum production in the exposed groups. However, in spite of the high proportions of subjects reporting acute respiratory symptoms, we found only small decreased in pulmonary function during the workday and workweek.

Adult↗
PubMed1975

Kinetics and Energetics of Light-driven Chloroplast Glutamine Synthesis.

Chloroplasts contain the enzyme glutamine synthetase. Formation of glutamine by isolated chloroplasts is light-dependent and requires an intact outer envelope. Addition of exogenous glutamic acid, as well as nitrogen donors such as nitrite or ammonium, stimulate the synthesis of this amide. Photosynthetic generation of ATP satisfies the light requirement of glutamine synthesis. The process is supported by cyclic as well as noncyclic photophosphorylation.

Journal Article↗
PubMed1975

Antibody production in goat milk serum after virus instillation of goat mammary gland. VII. Biochemical studies on sham infection with rabies and other non-propagatingagents.

This report describes the development of a method for the production and isolation of neutralizing antibodies against rabies virus (ERA strain) and other agents in the goat mammary gland during active lactation. The rabies virus did not propagate in thegland, but neutralizing antibodies were produced by serial instillations of the antigen. This process was termed 'sham infection.' Antibodies first appeared in the mildabout the 20th day and the titer increased until the 28th day. The antibodies were found to be associated with the lactogammaglobulin. The milk globulins were fractionated by gel chromatography and the fraction containing the antibody was isolated. This fraction was further purified and characterized by immunodiffusion, immunoelectrophoresis, and an analytical ultracentrifugation technique. The neutralizing antibody activityafter the 29th day was associated with the milk serum IgG fraction. This acive fraction was found to have a sedimentation coefficient of 6.8 Svedberg units.

Animals↗
PubMed1975

Respiratory function during prostaglandin-induced labor.

In a group of patients receiving intraamniotic injection of prostaglandin F2alpha or intramuscular injection of a methyl analogue of prostaglandin E2 for the termination of pregnancy, significant ariway constriction was demonstrated. The greatest responses were seen in 2 patients who had personal or family histories of asthma. If such patients receive prostaglandins, they should be carefully monitored to detect clinically important airway obstruction.

Amnion↗
PubMed1975

Use of the productive cough test to confirm presence of respiratory symptoms in school-age children.

We assessed the prevalence of respiratory symptoms and loose cough in 622 school-age children from an urban town in Connecticut. A higher prevalence of chronic symptoms was reported by black children, but the prevalence of recent symptoms and of loose cough in black children was similar to that in white children. The relationship between prevalence of recent symptoms and loose cough suggests that the observed racial differences in prevalence of chronic symptoms were unlikely to be due to racial differences in responses to a respiratory symptom questionnaire.

Adolescent↗
PubMed1975

Lactoglobulins (goat) in the immunofluorescence staining of parainfluenza virus type 2 in L-132 cells.

Instillation of parainfluenza virus type 2 in the mammary gland of the goat resulted in the appearance of specific and high titered antibodies in the milk. The globulin fraction of the milk was separated and conjugated with fluorescein isothiocyanate. These conjugated antibodies could be successfully used in the specific staining of the homologous virus in infected L-132 cells. Therefore, milk from such immunized animals represents a rich and convenient source of specific antibodies for use in immunofluorescence and other serological tests.

Animals↗