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Biomedical subjects

W de Backer

Publications and source records attributed to W de Backer.

7 recordsLinked to original sources
PubMed1991

Tumour necrosis factor stimulates human skin mast cells to release histamine and tryptase.

Besides its effects on tumour cells, tumour necrosis factor (TNF) also acts on a variety of other cells, thus enhancing inflammatory and immune processes. In view of the prominent role of the mast cell in such processes, the aim of the present study was to assess the effects of recombinant TNF-alpha on human mast cells. Mast cells from the infant foreskin obtained during circumcision were dispersed by an enzymatic technique using collagenase and hyaluronidase. Cells thus obtained were pooled, washed and separated by Percoll gradient centrifugation. Mast cells, with a purity of 70-90% were incubated for 60 min with 10(-11) to 10(-7) M rTNF-alpha. Histamine and tryptase levels were assessed in the cell supernatant by spectrofluorometry and radioimmunoassay (RIA) respectively. A concentration dependent release of histamine was observed, which reached a maximum of 11.5 +/- 2.2 nmol/10(6) cells at 10(-8) M rTNF. Release of tryptase was also concentration dependent and reached a maximum of 293 +/- 105 mU/10(6) cells (10(-8) rTNF). rTNF-alpha thus appears to be a direct stimulus for mast cells to degranulate and to release both histamine and tryptase.

Histamine Release↗
PubMed1991

Measurement of total respiratory impedance in infants by the forced oscillation technique.

The forced oscillation technique according to Làndsér et al. (J. Appl. Physiol. 41:101-106, 1976) was modified for use in infants. Adaptations, including a flexible tube to connect the infant to the measuring system and a bias flow to avoid rebreathing, did not influence impedance values. The linearity of the respiratory system was assessed and confirmed by 1) applying pseudo-random noise oscillations at three different amplitudes to 7 infants and 2) comparing in 12 infants impedance values obtained with pseudo-random noise and with sinusoidal oscillations at 12 and 32 Hz. Intersubject variability, averaged for all frequencies, was 6%. In 17 infants the relative error (+/- SD) between two series of five measurements within a time interval of 15 min was 0.5 +/- 5.7%. No statistically significant difference was found between impedance values before and after repositioning of the infant's head, whereas rotation resulted in a decrease in resistance and no effect on reactance. Our results indicate that the infant-adapted forced pseudo-random noise oscillation technique has the potential to give valuable information about ventilatory lung function in infants.

Airway Resistance↗
PubMed1983

Serum IgA, IgG, IgM and IgD in allergic (type I) and non-allergic respiratory diseases.

Serum immunoglobulin levels A, G, M, D have been studied in 902 patients suffering from allergic or non-allergic asthma, rhinitis and cough or various combinations of these disorders. In addition, a control group of asymptomatic persons was included. Serum IgA and IgD levels were significantly lower in both the allergic and non allergic groups of patients as compared to the control group, indicating that this decrease is a common feature for all patient groups studies. Serum IgA was significantly increased in amount in smokers. Serum IgA and IgG levels increased significantly with age. Females showed significantly higher serum IgM levels as compared to males. Atopic eczema did not seem to influence the serum level of immunoglobulin classes A, G, M or D.

Adolescent↗
PubMed1983

Effect of almitrine bismesylate on arterial blood gases and ventilatory drive in patients with severe chronic airflow obstruction and bilateral carotid body resection.

According to a double-blind cross over design 100 mg almitrine bismesylate or placebo was administered orally to eight patients with chronic airflow obstruction having undergone bilateral carotid body resection up to two years earlier to alleviate their extreme dyspnoea. Almitrine bismesylate failed to improve gas exchange in these patients, nor did it affect ventilation, breathing pattern, ventilatory or hypoxic drive. This study confirms that the drug only exerts its effects on carotid bodies and that the previously documented improvement in V/Q matching also results from its action on carotid bodies.

Aged↗