Bract extract

In Vitro Mediator Release. Although no pulmonary effects have been demonstrable in guinea pigs following inhalation of bract extract (104), contraction of isolated guinea pig ileum by extracts (105,106) has been reported. Aqueous extracts of cotton, jute, flax, and hemp cause contractions of isolated guinea pig ileirni or tracheal muscle preparations which are similar in time of onset and duration to those produced by... 

The platelet hist UIline release assay demonstrated that cotton mill dust extract, cotton bract extract, cotton leaf extract, dialyzed CMD extract, polyphenols, compound 48/80, rutin, trimethylamine HCl, quercetin, catechin, tannic acid, ellagic acid and sodium metasilicate all release histamine directly (48). Thus not only do tannin compounds induce histamine release, but they may also form higher molecular weight polymers and contain components that survive acid hydrolytic conditions (48). Tannins are widely distributed in the plant kingdom. 

Nicholls and Skidmore (65) demonstrated that dust collected from mills with a higher prevalence of byssinosis caused greater smooth muscle contractile activity than dust from mills with a lower prevalence. Recently, Russell e al. (66) used an isolated tissue bath to measure canine trachealis muscle contraction caused by cotton bract extracts (CBE). Morey et al. (67) showed that cotton bract represents 20-43% of the cotton dust total thus, the findings of Paton and Davenport using cotton dust agree in principle with Russell e al., who used cotton bract. Davenport and Paton (62) found a percentage of the activity of CDE represented by a 5HT-like component, but they also found at least one more active substance in the CDE than Russell et al. (66). 

Cotton dust and cotton bract extract contracted smooth muscle with forces equivalent to a 0.32jj0.05 jug/ml concentration of 5HT and 0.7+0.1 ug/ml concentration of 5-HT, respectively ( ). However, cotton bract extracts were blocked by methysergide, a 5-HT antagonist, while cotton dust extracts were not. Diphenhydramine, a histamine antagonist, failed to significantly affect either of the extracts ( ). 

Preparation of cotton bract extracts. Figure 1 is a flow chart showing our procedures for preparing the various bract extracts. Dried bracts (frost killed) were hand picked just prior to harvest from cotton fields in the Lubbock, Texas area. These were stored at room temperature. Extracts were freeze-dried and stored at -4°C. For inhalation challenge by our subjects each extract was reconstituted with water or saline, as indicated, at a concentration equivalent to the standard crude extract. This Insured that for challenge purposes components were not concentrated as purification progressed. 

Aerosols of less than Ipm diameter droplets were generated from bract extracts and saline by use of the Dautrebande D30 nebulizer. 

Figure 1. Procedures for preparing cotton bract extracts.

We use the MEF40%(P) value to compare the airway constrictor activities of various bract extracts because of its greater sensitivity and thus the lack of a need to Induce large decreases in airway caliber and corresponding discomfort in our subjects. 

Table I is an attempt to compare the responses in lung function we observe with our naive subjects on exposure to cotton bract extracts with the responses reported in literature of both naive subjects and workers exposed to cotton dust. The comparison suffers from the fact that neither the exposure time or concentration nor the post-exposure time of FEV. q readings are standardized for the different investigating laboratories. The various cotton dusts or extracts are not standardized either and the airway constrictor potency varies with the dusts. Bracts also vary in their potency. We have observed variations in potency with harvest year from the same location (Lubbock, Texas).

Figure 3. Time course of response to standard crude bract extract. Mean MEF40%(P) (0) and FEVi,o CAl response to the crude extract aerosol as a function of time after the start of aerosol inhalation (0-10 min ). The subjects...

The extent of the response of our naive subjects to bract extracts is nevertheless similar to the finding of others for naive subjects exposed to cotton dust. Compared to a mean decrease in FEV] q of 7.5% for our subjects Boehleche al. observed a mean 8.5% decrease for his subject population exposed to cotton dust, Rylander et observed decreases ranging from... 

Airway Constrictor Activity of DEAE Fractions of Bract Extracts... 

Preparation of Aqueous Extract of Cotton Bract. Field-dried cotton bract, 10 g, picked directly from plants in a field near Lake Providence, Louisiana, was ground with mortar and pestle, extracted twice with 100 ml of deionized water at pH 7 for 30 min each time at 250c with stirring. The extracts were combined and the solution was filtered the filtrate was freeze-dried. This bract extract (bAg) was also used to immunize rabbits. Additional bAg was further purified by treatment with 85% methanol in a similar manner as with cotton dust. 

Figure 2. Double diffusion of cotton dust fractions and cotton bract extract against rabbit antiserum to dust (AD) and normal rabbit serum (NS). Conditions described in Material and Methods.

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