Long-term stability of bronchial reactivity in guinea pigs.

Measurement of lung function and bronchial reactivity are widely used as outcome parameters to assess the efficacy of therapeutic interventions. In order to interpret the results correctly, it is necessary that the outcome parameters are themselves stable over time so that any significant changes measured may be attributed to the interventions. Specific airway conductance (SGaw) and airway reactivity to histamine are two commonly used parameters in animal models such as guinea pigs. Although short-term variability of these parameters has been investigated, there has been no study of long-term stability. In the present paper, SGaw and bronchial reactivity to histamine were measured in 111 conscious guinea pigs using a non-invasive, whole body plethysmograph. Baseline values of SGaw and ED35 histamine were measured and followed for eight weeks at weekly intervals. At baseline, mean SGaw in guinea pigs was 0.17 +/- 0.055 sec-1 cm H2O-1 and ED35 histamine ranged from 0.064 to more than 10 mg/ml. The distribution of ED35 histamine values was gaussian. We observed that the changes in SGaw and ED35 histamine recorded using this technique are highly reproducible over eight weeks. The reactivity varied by less than a doubling dose of histamine over any two consecutive weeks. Thus, the technique described in this paper is quick, easily learned, reproducible, independent of temperature-humidity artifact and highly suitable for studies of repeated measurements as in the study of dietary interventions and evaluation of effect of drugs.

A study of bronchial reactivity in relation to baseline pulmonary functions in patients with chronic obstructive lung disease.

Baseline bronchial reactivity was studied in 36 patients with chronic obstructive lung disease (COLD) and 20 normal healthy controls using the inhalational histamine challenge test. Using a cut off PD20 dose of 0.195 mg of histamine, 83.3% patients of COLD demonstrated bronchial hyper-reactivity. Presence of bronchial reactivity correlated significantly with the baseline FEV1, FEF25-75 and the ratio FEV1/FVC (p = 0.0019, 0.00001 and 0.008) respectively. Thus, bronchial reactivity in subjects with COLD correlates most significantly with the maximum mid-expiratory flow rate (FEF25-75).

Reproducibility of histamine inhalation bronchial challenge test.

Broncho-provocation tests with inhaled histamine were performed in 61 asthmatics twice at a gap of 4 weeks. Ten of them also underwent a third test after 16 weeks. More than 80% of the patients had a reproducibility of response within 1 to 2-fold concentration difference. It is concluded that under carefully controlled conditions broncho-provocation tests with histamine are reproducible.

Pruebas clínicas en el diagnóstico de lepra / Clinical proof in the diagnosis of leprosy

Se hace una revisión histórica de la histamina y pilocarpina, sustancias en el diagnóstico de la enfermedad de Hansen. Además se señala su uso práctico para el diagnóstico de esta patología