Search PubMed⌕ Search

Biomedical subjects

M C Townsend

Publications and source records attributed to M C Townsend.

47 records · Page 3Linked to original sources
PubMed1986

Effective renal blood flow and renal energy charge in murine peritonitis.

The temporal sequence of physiological derangements preceding acute renal failure (ARF) observed in overwhelming bacterial septicemia remains controversial. In order to examine the relationship of renal circulatory alterations and cellular dysfunction in murine sepsis, effective renal plasma flow (ERPF), renal tissue metabolites, and energy charge ratios were determined in Sprague-Dawley rats at 10 and 20 hours following induction of peritonitis by cecal ligation and perforation (CLP) or cecal manipulation alone (sham). Tissue levels of adenine nucleotides, lactate, and pyruvate were assayed after freeze-clamping kidneys unilaterally followed by enzymatic determinations. Cardiac outputs were determined by thermodilution and ERPF by p-aminohippuric acid (PAH) clearance. Results indicate in this model, despite an increase in cardiac output (P less than 0.05), ERPF was significantly decreased at both 10 hours (P less than; 0.05) and 20 hours (P less than 0.01) following induction of peritonitis. Further, although tissue pyruvate/lactate ratios showed significant decreases by 10 hours (P less than 0.05), diminished energy charge ratios were not observed until 20 hours following septic insult. These findings support the hypothesis of diminished renal perfusion as contributory and antecedent to cellular dysfunction in septicemic ARF.

Adenine Nucleotides↗
PubMed1985

Pulmonary function in relation to total dust exposure at a bauxite refinery and alumina-based chemical products plant.

A cross-sectional study of 1,142 male employees at the Arkansas Operations of a large aluminum production company examined the effect on pulmonary function of chronic exposure to total dust produced in the mining and refining of bauxite and the production of alumina chemicals. Never smokers, ex-smokers, and current smokers were analyzed separately. Among never smokers, a pattern of decreasing FEV1 was observed in relation to increasing duration and cumulative total dust exposure. Among never smokers with cumulative total dust exposures of greater than or equal to 100 mg/m3 yr and greater than or equal to 20 yr of exposure, there was a mean reduction from the predicted FEV1 of 0.29 to 0.39 L, in addition to a 3- to 4-fold excess of observed/expected numbers of subjects with FEV1 less than 80% of predicted. These results were observed relative to an external and an internal comparison group. Among current smokers, the deviations from predicted and the excess numbers of subjects with FEV1 less than 80% of predicted were larger in all exposure groups than for the never smokers. However, the quality of the smoking data was inadequate to allow separation of the effects of smoking and dust exposure.

Adolescent↗
PubMed1984

The effects of leaks in spirometers on measurements of pulmonary function. The implications for epidemiologic studies.

Although the effects of spirometric leaks on forced expiratory tracings have been noted in retrospect in epidemiologic studies, the present study was designed to examine the effects of leaks of known size on the tracings of subjects with varying degrees of airway obstruction. Such information is needed to assess the potential impact of spirometric leaks on epidemiologic studies using existing spirograms collected in the absence of spirometer leak tests. Spirometric leaks of 5 to 9, 22 to 30, 34 to 46, 69 to 97, and 150 to 190 ml/s were produced by drilling holes of five sizes into spirometer mouthpieces. Eight subjects were studied, of whom five had FEV1/FVC of 0.70 or greater ("normal"), and three had FEV1/FVC of less than 0.70 ("obstructed"). Although leaks of 34 to 46 ml/s or less were found to be invisible in the forced expiratory tracings, they caused statistically significant (p less than .05) FVC decrements in all eight subjects, with a mean decrement of -0.35 l in the normal subjects and -0.79 l in the obstructed subjects. In contrast, the 34 to 46 ml/s leaks caused no significant FEV1 decrements in seven of the eight subjects. Since marked FVC decrements occurred even with the smaller leaks, the FVC should not be analyzed in epidemiologic studies in the absence of frequent, documented leak tests. However, the present study indicates that the FEV1 may be robust enough for analysis if recorded in the presence of small spirometric leaks.

Adult↗
PubMed1984

Spirometric forced expiratory volumes measured in the standing versus the sitting posture.

To date, only one study has empirically examined the effects of sitting versus standing posture on the spirometric forced expiratory volumes. Because of design limitations, the small excess of sitting over standing values found in that study may have been due to a positive testing order effect. Using a crossover design, the present study of 90 middle-aged male subjects alternated the sitting-standing and standing-sitting testing sequence between subjects to avoid confounding by testing order effects. The major findings were that forced expiratory volumes in one and in six seconds and forced vital capacity were significantly larger (p less than 0.001) in the standing than in the sitting posture, with mean standing minus sitting differences ranging from +0.06 to +0.08 L for the 3 indexes. The larger expired volumes measured in the standing position in this study were probably due to the subjects taking slightly larger inspirations in this posture than in the sitting position.

Forced Expiratory Volume↗
PubMed1984

Development of a standardized pulmonary function evaluation program in industry.

In industries where there are occupational exposures to dusts, fumes, and gases, employers should monitor periodically their employees' respiratory health, using both spirometric pulmonary function tests and respiratory symptoms questionnaires. To incorporate the recent American Thoracic Society recommendations of standardization in these areas into an industrial pulmonary function evaluation program, a three-day standardized pulmonary function evaluation course was developed by a respiratory epidemiologist with extensive spirometry experience and was offered to many of Alcoa's domestic plant medical departments. The course included spirometric pulmonary function testing and use of the ATS-DLD-78A respiratory symptoms questionnaire. The major points covered in the course, the quality control follow-up of the course, and the need for such a standardized pulmonary function evaluation program in a large company are described in this report.

Calibration↗
PubMed1982

The effects of underrecorded forced expirations on spirometric lung function indexes.

A problem with short recorded lengths of expiration, encountered in a large heart attack intervention trial, illustrates the importance of standardization and training in spirometric lung function testing. At baseline, half of the trial's clinical centers had mean FVC values that were between 500 and 1,100 ml below those predicted for these centers. To quantify the effects of underrecorded forced expirations on the FVC, the FEV1/FVC%, the FEF70-80%, the FEF 25-75%, and the FEF45-55%, a study of 80 complete spirograms of good quality was undertaken. The findings were that short lengths of expiration cause underrecording of the FVC, inflating all of the examined FVC-dependent spirometric indexes. The inflation was fairly uniform across all obstructions for the forced expiratory flow rates, but it increased markedly with level of obstruction for the FEV1/FVC%. Virtually no subjects exhibited low values of these spirometric indexes after 3 s of expiration, and the number of subjects with low values was still substantially underestimated after 6 s of expiration. Whereas 18 (23%) of the subjects had FEV1/FVC% greater than or equal to 80% and 21 (26%) had ratios less than or equal to 69% based on complete expiration, 60 (75%) of the subjects had ratios greater than or equal to 80% and only 2 (3%) had ratios less than or equal to 69%, after 3 s of expiration. Even after 6 s, 26 subjects (33%) had ratios greater than or equal to 80%, and only 10 (13%) had ratios less than or equal to 69%. Therefore, completely recorded expirations are essential for accurate measurement of the FVC-dependent spirometric indexes.

Adult↗
PubMedDate not supplied

Contraceptive social marketing and community-based distribution systems in Colombia.

Three operations research experiments were carried out in three provinces of Colombia to improve the cost-effectiveness of Profamilia's nonclinic-based programs. The experiments tested: (a) whether a contraceptive social marketing (CSM) strategy can replace a community-based distribution (CBD) program in a high contraceptive use area; (b) if wage incentives for salaried CBD instructors will increase contraceptive sales; and (c) whether a specially equipped information, education, and communication (IEC) team can replace a cadre of rural promoters to expand family planning coverage. All three strategies proved to be effective, but only the CSM system yielded a profit. Despite this, Profamilia discontinued its CSM program soon after the experiment was completed. Unexpected government controls regulating the price and sale of contraceptives in Colombia made the program unprofitable. As a result, family planning agencies are cautioned against replacing CBD programs with CSM. Instead, CBD programs might adopt a more commercial approach to become more efficient.

Colombia↗