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Biomedical subjects

M Demedts

Publications and source records attributed to M Demedts.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

The effect of age on cell-mediated immunity to tuberculin: a study on in vivo and in vitro tuberculin reactivity.

We investigated reactivity to tuberculin in a group of 91 elderly subjects (65 years old and more) and in a control group of 53 younger subjects between 18 and 59 years old, by means of the tuberculin skin test (TST) and by an in vitro lymphocyte stimulation test (LST). The LST had been validated in preliminary tests to accurately reflect T cell reactivity towards tuberculin. We defined a LST with a stimulation index (SI) (ratio of the tuberculin stimulated cultures to the non-stimulated cultures) of 10 or more at a concentration of 0.4 microgram/ml as indicative for sensitisation to tuberculin. The correlation between TST and LST was r = 0.58 (p = 0.0001) in the elderly subjects and r = 0.64 (p = 0.0001) in the younger age group; age did not affect those correlations (p = 0.39). Of the subjects with initially negative TST, 44.4% (16 LST-positive and 16 LST-negative) reacted positive on TST as well as on LST after repeated testing. We conclude that (a) there is a statistically significant but rather weak correlation between in vivo and in vitro assays of cell-mediated immune response to tuberculin, (b) age did not influence this correlation, (c) the in vivo and in vitro tests give complementary information but cannot substitute for each other and (d) repeated TST can induce an immunological boosting phenomenon on TST as well as on LST.

Adolescent↗
PubMedDate not supplied

Pulmonary tuberculosis in the elderly: diagnostic difficulties.

Although numerous case reports and reviews have suggested that pulmonary tuberculosis presents atypically in the elderly, our findings argue for a basic similarity in the radiological pattern between younger and older patients, but a dissimilarity in the clinical presentation. Indeed elderly patients present with more non-specific complaints and have more negative tuberculin skin tests. The combination of these features and confounding (e.g. pseudo-tumoural) aspects of roentgenographic manifestations of pulmonary tuberculosis, even if the localization is apicoposterior, frequently result in more misdiagnosis in elderly patients. It may be suggested that non-specific complaints, even in the presence of normal chest X-ray or of minor lesions in the upper portion of the lung, should prompt careful examination. Tuberculosis should be considered more frequently in the differential diagnosis even when malignancy or other infections seem to be more likely.

Aged↗
PubMedDate not supplied

Vitamin A and acute respiratory infections.

By questionnaire we studied the occurrence of acute respiratory infections (ARI) in 1961 children between 0 and 5 years old from a total of 3225 families in Cikutra, Bandung. In 38.7% of them 200.000 IU vitamin A supplement had been given at least once during the preceding year. Mild or moderate ARI occurred in 54.7% of the children during the previous month and in 87.9% during the previous year; severe ARI occurred in 5.5% during the previous month and in 16.8% during the previous year. Surprisingly slightly more ARI occurred in children with vitamin A supplementation. However, vitamin A had been distributed more to low income than high income families, and in the latter group significantly less children suffered from ARI (p less than 0.05; 44% versus 54 a 56%).

Acute Disease↗
PubMedDate not supplied

Effects of thoracic or abdominal strapping on exercise performance.

In eleven young healthy subjects, vital capacity was reduced by 30% by thoracic or abdominal strapping and the effects of this on maximal work capacity, ventilation and circulation were examined. During exercise as well as at rest, tidal volume and stroke volume were reduced and respiratory frequency and heart rate were increased with both types of strapping. Cardiac output appeared to be decreased. Thoracic strapping was slightly but significantly more impeding than abdominal strapping: residual volume, tidal volume and maximal work capacity were smaller. In both instances, the decrease in maximal performance was apparently due to ventilatory as well as circulatory limitation.

Abdomen↗
PubMedDate not supplied

Isocapnic hyperventilation with cold air in healthy non-smokers, smokers and asthmatic subjects.

Isocapnic hyperventilation with subfreezing air was performed by 15 healthy non-smokers, 10 asymptomatic smokers and 9 asthmatics. All subjects had normal ventilatory function and airway resistance (Raw) before challenge. The hyperventilation was performed twice. In one session, total respiratory resistance (Rrs) and reactance (Xrs) were measured at various frequencies, using a forced oscillation technique; in another session, vital capacity (VC), forced expiratory volume in 1 s (FEV1), maximal expiratory flow rates (FEF) and Raw were determined. In non-smokers, no changes in FEV1, FEF nor Raw were observed, whereas Rrs increased significantly (+ 20% of the prechallenge value), without change in resonant frequency nor in the Rrs-frequency relationship. This suggests a constrictory effect on central airways (possibly a narrowing of the glottis) only. In smokers, Rrs showed a similar, though longer lasting, increase than in non-smokers. Besides, a significant change of the Rrs-frequency relationship and a reduction in FEF at 50% of VC was found, suggesting an involvement of peripheral airways also. In asthmatics, bronchial reactivity was more pronounced, resulting in significant changes in all parameters: Rrs increased by about 100% of the prechallenge value, and became highly frequency dependent; Xrs decreased markedly, resulting in an increase in resonant frequency of the respiratory system. Similarly, VC, FEV1 and FEF decreased. These alterations are compatible with a more generalized constriction of the peripheral as well as central airways.

Airway Obstruction↗