The chemotactic response of Vibrio anguillarum to fish intestinal mucus is mediated by a combination of multiple mucus components.

Chemotactic motility has previously been shown to be essential for the virulence of Vibrio anguillarum in waterborne infections of fish. To investigate the mechanisms by which chemotaxis may function during infection, mucus was isolated from the intestinal and skin epithelial surfaces of rainbow trout. Chemotaxis assays revealed that V. anguillarum swims towards both types of mucus, with a higher chemotactic response being observed for intestinal mucus. Work was performed to examine the basis, in terms of mucus composition, of this chemotactic response. Intestinal mucus was analyzed by using chromatographic and mass spectrometric techniques, and the compounds identified were tested in a chemotaxis assay to determine the attractants present. A number of mucus-associated components, in particular, amino acids and carbohydrates, acted as chemoattractants for V. anguillarum. Importantly, only upon combination of these attractants into a single mixture were levels of chemotactic activity similar to those of intestinal mucus generated. A comparative analysis of skin mucus revealed its free amino acid and carbohydrate content to be considerably lower than that of the more chemotactically active intestinal mucus. To study whether host specificity exists in relation to vibrio chemotaxis towards mucus, comparisons with a human Vibrio pathogen were made. A cheR mutant of a Vibrio cholerae El Tor strain was constructed, and it was found that V. cholerae and V. anguillarum exhibit a chemotactic response to mucus from several animal sources in addition to that from the human jejunum and fish epithelium, respectively.

Toxicokinetics of soman in cerebrospinal fluid and blood of anaesthetized pigs.

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman was analysed in cerebrospinal fluid (CSF) and blood in anaesthetized, spontaneously breathing pigs during a 90-min period after injection of soman. The pigs were challenged with different intravenous (i.v.) doses of C(+/-)P(+/-)-soman corresponding to 0.75-3.0 LD50 (4.5, 9.0 and 18 microg/kg in a bolus injection and 0.45 microg/kg per min as a slow infusion). Artificial ventilatory assistance was given if, after soman intoxication, the respiratory rate decreased below 19 breaths/min. Blood samples were taken from a femoral artery and CSF samples from an intrathecal catheter. The concentrations of the soman isomers were determined by gas chromatography coupled with high resolution mass spectrometry. All four isomers of soman were detected in both blood and CSF samples. The relatively non-toxic C(+/-)P(+) isomers disappeared from the blood stream and CSF within the first minute, whereas the levels of the highly toxic C(+/-)P(-) isomers could be followed for longer, depending on the dose. Concurrently with the soman analyses in blood and CSF, cholinesterase (ChE) activity and cardiopulmonary parameters were measured. C(+/-)P(-) isomers showed approx. 100% bioavailability in CSF when C(+/-)P(+/-)-soman was given i.v. as a bolus injection. In contrast, C(+/-)P(-) isomers displayed only 30% bioavailability in CSF after slow i.v. infusion of soman. The ChE activity in blood decreased below 20% of baseline in all groups of pigs irrespective of the soman dose. The effect of soman intoxication on the respiratory rate, however, seems to be dose-dependent and the reason for ventilatory failure and death. Artificial ventilation resulted in survival of the pigs for the time-period studied.

The effect of the calcium antagonist nimodipine on the detoxification of soman in anaesthetized rabbits.

The effect of nimodipine, a vasoactive calcium antagonist, on the disappearance of soman from blood was studied in anaesthetized rabbits intoxicated with soman (10.8 micrograms kg-1 i.v.). Blood samples from the left heart ventricle and femoral artery were used to investigate soman detoxification. The concentrations of the soman isomers C+P- and C-P- in blood samples were determined by gas chromatography coupled with high-resolution mass spectrometry. During the sampling, 15-300 s after soman injection, the soman concentration in control animals decreased from 50 to 0.029 ng mL-1; in animals pre-treated with nimodipine (10 mg kg-1) it decreased from 15 to 0.033 ng mL-1. In animals pre-treated with nimodipine the soman concentration was significantly reduced during the first minute of sampling. No differences were detected between soman concentrations in samples from the heart and femoral artery. Acetylcholinesterase inhibition was also used as an indicator of soman activity; there was no difference between the activity of this enzyme in different peripheral organs of control and nimodipine-treated animals. Nimodipine reduces the initial concentration of soman in the blood, which might be of significance in the treatment of soman intoxication.

The protective effect of nimodipine, a calcium antagonist, and its influence on soman clearance in the anaesthetized rabbit.

The effect of pretreatment with a vasoactive compound, nimodipine, on soman intoxication in peripheral organs of rabbits was studied by measuring changes in the cholinesterase and acetylcholinesterase activity and by measuring clearance of soman in blood using gas chromatography/high resolution mass spectrometry. In animals receiving soman only, initial blood concentrations were approximately 100 ng mL-1 and were still detectable after 5 min. The clearance rate of soman in blood markedly increased following nimodipine pretreatment such that soman was below the detection limit (0.002-0.003 ng mL-1) in all samples. Soman injection caused a significant inhibition of the acetylcholinesterase activity in serum, and in brain. In rabbits pretreated with nimodipine, no significant inhibition of acetylcholinesterase activity occurred after soman injection. In view of the effects of nimodipine on soman clearance and on the acetylcholinesterase and cholinesterase inhibition during soman intoxication, we suggest that nimodipine has profound circulatory effects, which during soman intoxication, increase the vascular perfusion through the body and thereby increase the detoxifying capacity.

Emission of hydrogen sulfide from sulfur dioxide-fumigated pine trees.

Pine (Pinus silvestris L.) trees subjected to relatively low concentration of SO(2) in the field emit H(2)S from the needles, as demonstrated by gas chromatographic analysis after preconcentration on a molecular sieve. H(2)S is the only reduced sulfurous compound emitted from SO(2) fumigated leaves. The emission is light and SO(2) concentration dependent. Pine trees in the field and in laboratory experiments continue to emit H(2)S several hours after the termination of prolonged SO(2) fumigation. The maximum emission rates observed from pine trees in the field and in laboratory experiments, 14 and 20 nanomoles per milligram chlorophyll per hour respectively, are about the activity expected for the sulfur assimilation pathway in the chloroplasts.

Trace analysis for chlorinated hydrocarbons in air by quantitative combustion and coulometric chloride determination: application to standardization of vinyl chloride permeation tubes.

Methods for high-temperature combustion of vinyl chloride in air were studied theoretically and two types of gas mixtures were found to give 100% conversion into HCl. The chloride was determined by coulometric titration with silver, in 70% acetic acid. Good agreement between theoretical and experimental results was obtained. Permeation rates of vinyl chloride from fluorinated ethylene propylene permeation tubes were determined gravimetrically and with the coulometric method developed. The standard deviations of the methods were 0.002 and 0.001 microg min respectively for permeation rates of 0.5 microg min when the temperature was controlled to +/- 0.02 degrees . The coulometric mean value was 99.9% of the gravimetric mean; 1 ppm of vinyl chloride in air could be determined coulometrically with a standard deviation of about 0.002 ppm.