Comparison of Three Culture Media for Isolation of Mycobacterium tuberculosis: a 6-Year Study

Among 2,648 specimens positive on culture for Mycobacterium tuberculosis over a 6-year period, 82% grew on Lowenstein-Jensen medium (LJ), 79% on American Trudeau Society (ATS), and 56% on Middlebrook 7H10 (7H10). When these commercial culture media were compared in regard to the number of acid-fast bacilli seen on the original smears, LJ cultures were found to have the highest isolation rates for each smear category, and 7H10 had the lowest rates. Comparing the media from the aspect of number of mycobacterial colonies produced, LJ and ATS had the highest average colony counts, followed by 7H10. These findings were relatively constant over the 6-year period. One possible reason for the low positive rate of 7H10 was the lack of CO(2) enrichment.     

Development of enzymes in the cotyledons of watermelon seedlings

Changes in hypocotyl length, cotyledon weight, lipid content, chlorophyll content, and capacity for photosynthesis have been described in seedlings of Citrullus vulgaris, Schrad. (watermelon) growing at 30 C under various light treatments. Corresponding changes in the levels of 19 enzymes in the cotyledons are described, with particular emphasis on enzymes of microbodies, since during normal greening, enzymes of the glyoxysomes are lost and those of leaf peroxisomes appear. In complete darkness enzymes of the glyoxysomes reach a peak at 4 days and decline as the fat is depleted. Enzymes of mitochondria and of glycolytic pathways also peak at 4 to 5 days and either remain unchanged or decline to a lesser extent. Exposure to light at 4 days, when the cotyledons emerge, results in a selectively greater destruction of enzymes of the glyoxylate cycle; chlorophyll synthesis and capacity for photosynthesis increase in parallel, and there is a striking increase in the activities of chloroplast enzymes and in those of the leaf peroxisomes, hydroxypyruvate reductase and glycolate oxidase. The reciprocal changes in enzymes of the glyoxysomes and of leaf peroxisomes can be temporally dissociated, since even after 10 days in darkness, when malate synthetase and isocitrate lyase have reached very low levels, hydroxypyruvate reductase and glycolate oxidase increase strikingly on exposure to light and the cotyledons become photosynthetic. Furthermore, the parallel development of enzymes of leaf peroxisomes and functional chloroplasts is not immutable, since hydroxypyruvate reductase and glycolate oxidase activity can be elicited in darkness following a 5-minute exposure to light at day 4 while chlorophyll does not develop under these conditions.     

Regulatory peptide and serotonin content and brush-border enzyme activity in the rat gastrointestinal tract following neonatal treatment with capsaicin; lack of effect on epithelial markers.

The possible trophic influence of the capsaicin-sensitive extrinsic innervation of the gastrointestinal mucosa was investigated. Rats were treated neonatally with capsaicin. The gastrointestinal content of serotonin and glucagon-like immunoreactivity were used as a measure of the effect on the endocrine gut mucosa and gastrointestinal aminopeptidase and alkaline phosphatase activities were used as a measure of the effect on the gut brush-border. The gastrointestinal content of the neuropeptides substance P, VIP and CGRP were used to monitor effects on the innervation of the gut. The depletion of substance P-immunoreactivity(-IR) and calcitonin gene-related peptide(CGRP)-IR in extracts of urinary bladder and lung from the capsaicin-treated rats is evidence of the efficacy of capsaicin treatment in affecting a loss of C-fibre sensory nerves. The significant depletion of CGRP-IR measured in the stomach and duodenum of capsaicin-treated rats indicated the loss of the C-fibre sensory innervation to the gastrointestinal tract. The gastrointestinal content of VIP and substance P, which are predominantly within intrinsic gut neurones, were unaffected by capsaicin treatment. In all regions of the gastrointestinal tract of capsaicin-treated rats, the serotonin and glucagon-IR levels were not significantly different from those in controls. Similarly the levels of activity of the brush-border enzymes were not significantly effected by capsaicin treatment. This suggest the absence of any major trophic influence of capsaicin-sensitive sensory nerves on the gut endocrine mucosa and the brush border.     

Effect of substance P on cardiovascular and respiratory function in subjects

The effect of substance P (SP), administered both intravenously and by inhalation, has been studied in normal and asthmatic humans. Intravenous infusion of SP (0.2-3.3 pmol X kg-1 X min-1) achieving a plasma concentration of SP between 5 and 25 pM produced vasodilatation (mean +/- SD), maximal increase in skin temperature (0.9 +/- 0.3 degree C) (P less than 0.05), and fall in diastolic blood pressure (8.5 +/- 2.9 mmHg) (P less than 0.05) associated with an increase in heart rate (15 +/- 10 beats/min) (P less than 0.05). All subjects had a fall in Vp30 (airflow at 70% of forced vital capacity measured from total lung capacity after a forced partial expiratory flow maneuver) at low infusion rate (P less than 0.05) and a significant rise at the highest infusion rate (P less than 0.05). Ventilation at rest and when stimulated by transient hypoxia increased (mean increase in resting ventilation 0.73 +/- 0.4 l/min and mean percent increase in transient ventilatory hypoxic response 41 +/- 27%). There was a small nonsignificant increase in plasma norepinephrine but no change in epinephrine or histamine. Inhaled SP, up to 0.7 mumol, caused a small nonsignificant fall in airway function in asthmatic subjects. SP has demonstrable effects on vascular smooth muscle and control of ventilation but at the doses studied had little effect on airway function.