A biological method for the determination of mycotoxins--Tetrahymena pyriformis

The toxic action of selected mycotoxins on a biological subject was tested in the protozoan Tetrahymena pyriformis. The following toxins were tested: toxin T-2 at doses from 1.52 micrograms to 100.0 mg per litre of medium, ochratoxin A at doses from 12.21 micrograms to 800.0 mg per litre of medium, and rubratoxin B at doses from 12.21 micrograms to 800.0 mg per litre of medium. In toxin T-2 the LD100 was found to be about 390.63 micrograms and LD50 about 48.83 micrograms per litre of medium. In ochratoxin A the LD100 was about 25.0 mg and LD50 about 3.13 mg per litre of medium. In rubratoxin B the LD100 was about 200.0 mg and LD50 about 25.0 mg per litre of medium.     

The effect of dichlorvos and metathion on selected enzymes of the amoeba Tetrahymena pyriformis

The effect of dichlorvos and metathion was studied as exerted on acetylcholinesterase activity in the protozoan Tetrahymena pyriformis. In dichlorvos, the highest enzyme activity inhibition was obtained after 30 minutes. A 50% inhibition of the enzyme activity was recorded at the dose of 1.22 mg per litre. As to metathion, the highest enzyme activity inhibition was obtained after 60 minutes. A 50% inhibition of the enzyme activity was recorded at the dose of 879.2 ng per litre. One hour after exposure to this dose, almost 75% inhibition of the activity of the enzyme was recorded. The determination of acetylcholinesterase activity increases the sensitivity of the bioassay for organophosphates with the use of the Tetrahymena pyriformis protozoan. Dichlorvos was studied for its action at supratoxic doses (50.0, 100.0 and 150.0 mg per litre) and it was found that lactate dehydrogenase activity was almost completely suppressed; the inhibition of alanine aminotransferase was pronounced. A weaker activity inhibition was recorded in aspartate aminotransferase, alkaline and acid phosphatase; the activity of alpha-amylase increased. No dependence on dosage was demonstrated.     

Simple transport medium for the isolation of Chlamydia psittaci from clinical material

Infectious elementary bodies of Chlamydia psittaci in tissue samples from field cases of enzootic abortion were placed in five different transport media (A to E). In one medium, in the absence of refrigerative storage, the organism remained viable for 30 days and at 4 degrees C for 34 days. This was medium D; it consisted of sucrose (74.6 g/litre), K2HPO4 (1.237 g/litre), L-glutamic acid (0.721 g/litre), fetal calf serum (10 per cent v/v), vancomycin and streptomycin (100 micrograms/ml) and nystatin and gentamicin (50 micrograms/ml). Samples of this transport medium were supplied to veterinary investigation centres throughout the UK. Of 1862 samples submitted for diagnosis of enzootic abortion only 1.55 per cent were so contaminated that chlamydiae could not be detected. This transport medium permits the isolation of C psittaci from clinical material for up to about one month, even in the absence of conventional storage facilities.     

Ability of bentonite and natural zeolite to adsorb aflatoxin from liquid media

The adsorption of aflatoxin (AF) B1, contained in aqueous medium or in synthetic medium left after the cultivation of Aspergillus parasiticus NRRL 2999, was studied in two samples of bentonite, two samples of natural zeolite, and three kinds of adsorption coal added to water, to saline, to the blood serum of pigs, to the stomach fluid of pigs or rumen fluid of cows at concentrations of 5 to 50 mg per litre. Unlike retinol-propionate and beta-carotene, AF was readily adsorbable in vitro. The initial concentration of 3.6 mg or 18 mg AFB1 per litre was reduced to 0.3-27% after exposure to 50 g of adsorbent; this reduction was greater when the AFB1 was tested in the cultivation medium and the maximum reduction was recorded when adsorption coals was involved. The effectiveness of zeolite was lower in media containing nitrogen compounds and in those cases when its doses were low. The average AF retention in the adsorbents, calculated after the determination of desorption by chloroform extraction, was 72% of the original content in the medium in the case of adsorption coals, 66% in bentonite, and 60% in zeolite.     

Ultrasonographic examination of the adrenal gland and evaluation of the hypophyseal-adrenal axis in 20 cats

The adrenal glands of 20 healthy, non-sedated cats were examined ultrasonographically; visualisation and assessment was possible in all cases. In comparison with the surrounding tissue, the adrenal glands were hypoechoic and two distinct zones could be differentiated in six of the cats. The length and width of the adrenal glands varied from 0.45 to 1.37 cm and 0.29 to 0.53 cm, respectively, and both dimensions could be reliably reproduced. The adrenal glands did not differ between male and female cats, and, in comparison to dogs, those of cats are more easily visualised ultrasonographically. The basal cortisol value ranged from 2.0 to 79 micrograms/litre. Values 30 and 60 minutes after administration of ACTH (0.125 mg/cat intramuscularly) varied from 36 to 126 micrograms/litre. The basal value of aldosterone ranged from 4 to 618 pg/ml. Values 30 and 60 minutes after administration of ACTH varied from 100 to 832 pg/ml. In all cats, suppression of the cortisol value below the level of detection (< 2.0 micrograms/litre) occurred four and eight hours after the administration of dexamethasone (0.1 mg/kg intravenously).     

Therapy of domestic animals affected by alkylphosphates]

Sheep were studied for the possibility of treatment after parenteral (intramuscular) intoxication with EDMM (methylthiophosphorous acid O-ethyl-S-2-dimethylamino-ethylester) and with EDIM (methylthiophosphorous acid O-ethyl-S-2-diisopropyl-aminoethylester). In both cases of intoxication, the therapy was based on a system of an anticholinergic and cholinesterase reactivator administered singly at a time of the maximum development of the clinical signs of poisoning and maximum inhibition of both erythrocytic (AChE, E.C.3.1.1.7.) and plasma (BChE, E.C.3.1.1.8.) cholinesterase. The optimum therapeutic system requires the administration of 20.0 mg atropine s. c. pro toto and 10.0 mg trimedoxim per kg 1. w. i. v. In both cases of poisoning with doses = LD50 in i. m. administration, the mentioned system was actually positive. In a single administration irrespective of the doses of the used drugs, the system does not guarantee survival after ingestion of anticholinesterasic doses above LD50.     

硫酸二乙酯对家蚕毒性的半致死剂量测定

硫酸二乙酯(DES)是一种能诱导生物体产生随机点突变的烷化剂。为了完善利用DES诱导家蚕突变的实验技术,采用不同剂量DES分别处理家蚕蛹、蛾、卵,检测DES对不同发育时期家蚕毒性的半致死剂量(LD50),结果表明DES对不同发育时期家蚕的LD50值存在显著差异:化蛹第5天的雌雄蛹分别为2 333.90μg/头和2 369.50μg/头;刚羽化雄蛾为156.39μg/头;蚕卵为13.23 mg/mL。研究结果可作为DES对家蚕的最适诱变剂量和家蚕诱变最佳发育时期选择的参考依据。     

Toxicity of seeds of three Aesculus spp to chicks and hamsters

Seeds of horse chestnut (Aesculus hippocastanum), Ohio buckeye (A glabra), and yellow buckeye (A octandra) were tested for toxicity to 2-week-old Leghorn chicks and adult female Syrian hamsters. The LD50 of the water soluble portion of alcoholic extracts of horse-chestnut seeds (for hamsters and chicks) and of dried, powdered seeds (chicks only) was determined. The LD50 for a single dose of extract from horse-chestnut seeds was 10.6 mg/g of body weight for chicks and 10.7 mg/g of body weight for hamsters. The LD50 for chicks given 2 consecutive daily doses of horse-chestnut seed was 6.5 mg/g. Toxic signs included depression, muscular incoordination, paralysis, coma, and death. Extracts of seeds of Ohio buckeye were nontoxic to chicks and hamsters when fed at 80 mg/g. One of 5 hamsters died after dosing for 5 days with 80 mg/g of extract of seeds of yellow buckeye/g.     

Transfer of sulphamethazine from contaminated dairy feed to cows' milk.

Four groups of four healthy mid-lactation Friesian cows were fed a compound feeding stuff containing either 2, 10 or 250 mg sulphamethazine/kg, corresponding to 0, 2, 10 and 250 per cent of the therapeutic inclusion rate in rations for pigs, at a flat rate of 3 kg twice daily for 21 days, followed by a seven-day withdrawal period. The cows were machine-milked twice daily and pooled milk samples from each cow were analysed by a commercially available microbiological assay with a sensitivity of 100 micrograms/litre and by a high performance liquid chromatography (HPLC) procedure with a limit of detection of 10 micrograms/litre. No sulphamethazine was detected by HPLC in the milk samples taken from any of the cows fed the concentrate containing 2 or 10 mg/kg. The milk samples from all four cows fed the highest concentration of sulphamethazine contained from 21 to 120 micrograms/litre while they were being fed the contaminated concentrate. The cow with the highest concentrations of sulphamethazine was the only one which repeatedly tested positive by the microbiological assay. The concentration of sulphamethazine declined rapidly during the withdrawal period and the drug was not detectable by either method in samples taken from two days after the contaminated feed was withdrawn.     

Selective medium for isolation of Haemophilus somnus from cattle and sheep

Incorporation of vancomycin (5 micrograms/ml), neomycin (5 micrograms/ml), sodium azide (50 micrograms/ml), nystatin (100 iu/ml) and cyclohexamide (100 micrograms/ml) into 5 per cent horse blood agar results in a selective medium for the primary isolation of Haemophilus somnus from cattle and sheep. Addition of thiamine monophosphate (1 microgram/ml) to the medium enhanced growth of this bacterium. Gram-positive bacteria did not grow on the medium and colonies of many Gram-negative bacteria were eliminated or reduced in numbers and size. Colonies of H somnus were larger on the selective medium than on sheep blood agar but retained typical morphology. Recovery of 18 laboratory strains was 73 to 166 per cent (mean 112) on selective medium compared to sheep blood agar. H somnus was isolated from the vagina of a total of 136 (28.6 per cent) of 476 cows surveyed, 79 (16.6 per cent) on sheep blood agar and 129 (27.1 per cent) on selective medium. The selective agents and thiamine were stable indefinitely as a freeze dried mixture while prepared plates were stable for two weeks.     

Evaluation of selective media for bifidobacteria in poultry and rabbit caecal samples.

Five media were evaluated to determine their selectivity for Bifidobacterium sp. in hen and rabbit caecal samples. The colonies arising on the plates inoculated with the caecal samples were Gram stained and screened for the presence of fructose-6-phosphate phosphoketolase activity. Rogosa agar modified by the addition of cysteine-hydrochloride (0.05% w/v), Beeren's agar (with 5 ml/l of propionic acid as a selective agent), BS 2 agar (containing per one litre sodium propionate 15 g, lithium chloride 3 g, paromomycin sulphate 50 mg, neomycin sulphate 200 mg), and Wilkins-Chalgren agar (MW) modified by the addition of acetic acid (1 ml/l) and mupirocin (100 mg/l) were selective for Bifidobacterium sp. from rabbit caecal samples. In contrast, only MW medium was suitable for the isolation and enumeration of bifidobacteria in hen caecal samples. In conclusion, the results suggest that MW agar showed the greatest selectivity. A further advantage of this medium is its case of preparation. Therefore this agar could contribute to the study of the effects of the ingestion both probiotics and prebiotics. Finally, it could be noted that the bifidobacteria selective media should be chosen in respect of the animal species origin of the sample tested.     

Pharmacokinetics of cefotaxime in the dog

Each of five dogs was given cefotaxime at a dose rate of 50 mg/kg by intravenous, intramuscular and subcutaneous routes, in three separate treatments. Plasma concentration time profiles were characterised by a linear two-compartment model after the intravenous administration. After intravenous, intramuscular and subcutaneous injections the mean biological half-lives were 0.74, 0.83 and 1.71 hours, respectively. The apparent steady state volume of distribution was 0.48 litre/kg and body clearance after intravenous injection was approximately 0.63 litre/hour/kg. After intramuscular and subcutaneous injections peak plasma cefotaxime concentrations were 47 +/- 15 and 29.6 +/- 16 micrograms/ml at 0.5 and 0.8 hours, respectively. The average bioavailability of cefotaxime given by intramuscular injection was 86.5 per cent and for cefotaxime given subcutaneously it was approximately 100 per cent. After two hours, the cefotaxime plasma concentration remained higher after subcutaneous than after intramuscular administration.     

Evaluation of Selective Media for Bifidobacteria in Poultry and Rabbit Caecal Samples

Five media were evaluated to determine their selectivity for Bifidobacterium sp. in hen and rabbit caecal samples. The colonies arising on the plates inoculated with the caecal samples were Gram stained and screened for the presence of fructose-6-phosphate phosphoketolase activity. Rogosa agar modified by the addition of cysteine-hydrochloride (0.05 % w/v), Beeren’s agar (with 5 ml/l of propionic acid as a selective agent), BS 2 agar (containing per one litre sodium propionate 15 g, lithium chloride 3 g, paromomycin sulphate 50 mg, neomycin sulphate 200 mg), and Wilkins-Chalgren agar (MW) modified by the addition of acetic acid (1 ml/l) and mupirocin (100 mg/l) were selective for Bifidobacterium sp. from rabbit caecal samples. In contrast, only MW medium was suitable for the isolation and enumeration of bifidobacteria in hen caecal samples. In conclusion, the results suggest that MW agar showed the greatest selectivity. A further advantage of this medium is its ease of preparation. Therefore this agar could contribute to the study of the effects of the ingestion both probiotics and prebiotics. Finally, it could be noted that the bifidobacteria selective media should be chosen in respect of the animal species origin of the sample tested.     

Physiological stimuli of thirst and drinking patterns in ponies

The stimuli that elicit thirst were studied in four ponies. Nineteen hours of water deprivation produced an increase in plasma protein from 67 +/- 0.1 g/litre to 72 +/- 2 g/litre, a mean (+/- se) increase in plasma sodium from 139 +/- 3 to 145 +/- 2 mmol/litre and an increase in plasma osmolality from 297 +/- 1 to 306 +/- 2 mosmol/litre. Undeprived ponies drank 1.5 +/- 0.9 kg/30 mins; 19 h deprived ponies drank 10.2 +/- 2.5 kg/30 mins and corrected the deficits in plasma protein, plasma sodium and plasma osmolality as well as compensating for the water they would have drunk during the deprivation period. In order to determine if an increase in plasma osmolality would stimulate thirst, 250 ml of 15 per cent sodium chloride was infused intravenously. The ponies drank when osmolality increased 3 per cent and when plasma sodium rose from 136 +/- 3 mmol/litre to 143 +/- 3 mmol/litre. Ponies infused with 15 per cent sodium chloride drank 2.9 +/- 0.7 kg; those infused with 0.9 per cent sodium chloride drank 0.7 +/- 0.5 kg. In order to determine if a decrease in plasma volume would stimulate thirst, ponies were injected with 1 or 2 mg/kg bodyweight (bwt) frusemide. Plasma protein rose from 68 +/- 2 g/litre pre-injection to 75 +/- 2 g/litre 1 h after 1 mg/kg bwt frusemide and to 81 +/- 1 g/litre 1 h after 2 mg/kg bwt frusemide.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fonofos toxicosis in dairy cows: an accidental poisoning (1977)

An accidental poisoning (in 1977) of 28 Holstein cows occurred when approximately 0.9 kg of 25% active ingredient fonofos, O-ethyl S-phenyl ethylphosphonothiolothionate, was spilled onto bulk feed in a delivery truck. Eight cows died within 2 days; the remaining 20 were necropsied 29 days later. Of the 8 fatally poisoned, 7 were being fed a high-grain diet and 1 was fed a medium-grain diet. Fonofos concentrations in feed cart and storage bin samples were 100 micrograms/g and 61 micrograms/g, respectively. Tissues from 6 animals were analyzed extensively for fonofos concentrations: 2 had died immediately; the other 4 were in the recovery state when they were necropsied. Rumen contents and liver, kidney, brain, heart, and milk samples were analyzed. Fonofos concentrations in these samples were significantly higher in the cows fatally affected than in the cows necropsied 3 weeks later. The oral acute LD50 and LD1 of fonofos in Holstein cows were calculated by the Litchfield and Wilcoxon method to be 1.30 and 0.84 mg/kg, respectively, with a 95% confidence range of +/- 0.20 mg/kg.     

Stress responses during total intravenous anaesthesia in ponies with detomidine - guaiphenesin - ketamine

Six ponies were anaesthetised for two hours with intermittent injections of a combination of guaiphenesin (72 mg/kg/hr), ketamine (1.4 mg/kg/hr) and detomidine (0.015 mg/kg/hr) after premedication with detomidine 0.01 mg/kg and induction of anaesthesia with guaiphenesin 50 mg/kg and ketamine 2 mg/kg. Induction of anaesthesia was smooth, the ponies were easily intubated and after intubation breathed 100% oxygen spontaneously. During anaesthesia mean pulse rate ranged between 31–44 beats per minute and mean respiratory rate between 12–23 breaths per minute. Mean arterial blood pressure remained between 110–130 mm Hg, mean arterial carbon dioxide tension between 6.1–6.9 kPa and pH between 737–7.42. Arterial oxygen tension was over 23 kPa throughout anaesthesia. Plasma glucose increased to more than 25 mmol per litre during anaesthesia; there was no change in lactate or ACTH concentration and plasma cortisol concentration decreased. Recovery was rapid and smooth. A guaiphenesin, ketamine and detomidine combination appeared to offer potential as a total intravenous technique for maintenance of anaesthesia in horses.     

Effects of intravenous lidocaine, ketamine, and the combination on the minimum alveolar concentration of sevoflurane in dogs

ObjectiveTo evaluate the effects of intravenous lidocaine (L) and ketamine (K) alone and their combination (LK) on the minimum alveolar concentration (MAC) of sevoflurane (SEVO) in dogs.Study designProspective randomized, Latin-square experimental study.AnimalsSix, healthy, adult Beagles, 2 males, 4 females, weighing 7.8 – 12.8 kg.MethodsAnesthesia was induced with SEVO in oxygen delivered by face mask. The tracheas were intubated and the lungs ventilated to maintain normocapnia. Baseline minimum alveolar concentration of SEVO (MAC_B) was determined in duplicate for each dog using an electrical stimulus and then the treatment was initiated. Each dog received each of the following treatments, intravenously as a loading dose (LD) followed by a constant rate infusion (CRI): lidocaine (LD 2 mg kg⁻¹, CRI 50 μg kg⁻¹minute⁻¹), lidocaine (LD 2 mg kg⁻¹, CRI 100 μgkg⁻¹ minute⁻¹), lidocaine (LD 2 mg kg⁻¹, CRI 200 μg kg⁻¹ minute⁻¹), ketamine (LD 3 mg kg⁻¹, CRI 50 μg kg⁻¹ minute⁻¹), ketamine (LD 3 mgkg⁻¹, CRI 100 μg kg⁻¹ minute⁻¹), or lidocaine (LD 2 mg kg⁻¹, CRI 100 μg kg⁻¹ minute⁻¹) + ketamine (LD 3 mg kg⁻¹, CRI 100 μg kg⁻¹ minute⁻¹) in combination. Post-treatment MAC (MAC_T) determination started 30 minutes after initiation of treatment.ResultsLeast squares mean ± SEM MAC_B of all groups was 1.9 ± 0.2%. Lidocaine infusions of 50, 100, and 200 μg kg⁻¹ minute⁻¹ significantly reduced MAC_B by 22.6%, 29.0%, and 39.6%, respectively. Ketamine infusions of 50 and 100 μg kg⁻¹ minute⁻¹ significantly reduced MAC_B by 40.0% and 44.7%, respectively. The combination of K and L significantly reduced MAC_B by 62.8%.Conclusions and clinical relevanceLidocaine and K, alone and in combination, decrease SEVO MAC in dogs. Their use, at the doses studied, provides a clinically important reduction in the concentration of SEVO during anesthesia in dogs.     

Pharmacokinetic Disposition of Cefazolin in Serum and Tissue during Canine Total Hip Replacement

Intraoperative cefazolin concentrations were measured in serum, joint capsule, cancellous bone of the acetabulum, and proximal cancellous bone of the femur in 15 dogs undergoing total hip replacement. Cefazolin (22 mg/kg intravenously [IV]) was administered every hour for three doses. The mean peak serum concentrations (+/- SEM) were 387.79 +/- 27.56 micrograms/mL, 521.71 +/- 28.00 micrograms/mL, and 542.20 +/- 30.91 micrograms/mL, respectively. Mean serum concentrations just before administration of doses 2 and 3 were 51.77 +/- 2.39 micrograms/mL, and 64.84 +/- 3.46 micrograms/mL, respectively. The mean cefazolin concentrations in the joint capsule, cancellous bone of the acetabulum, and cancellous bone of the femur were 34.71 +/- 2.50 micrograms/g, 28.70 +/- 7.40 micrograms/g, and 36.20 +/- 3.80 micrograms/g, respectively. The minimum inhibitory concentration of cefazolin for 90% of the common contaminants (MIC90) in this clinic is less than or equal to 2 micrograms/mL or per gram of tissue. Serum concentrations never fell below 15 times the MIC90 (lowest trough, 35.93 micrograms/mL), and the lowest tissue concentration (6.57 micrograms/mL in cancellous bone from the acetabulum) was still more than 3 times the MIC90. The mean tissue concentration was 15 times the MIC90.     

Production of cyclopiazonic acid, its effect on the chick embryo and on 1-day-old cockerels

In 1979 to 1983, 148 strains of Penicillium cyclopium were isolated from wheat and from poultry feed mixtures; 11.5% of these strains produced cyclopiazonic acid at the rate of up to 500 mg per kg of wheat. Forty-seven percent of the 96 isolates of Aspergillus flavus and 56% of the nine isolates of Penicillium griseofulvum produced cyclopiazonic acid at the maximum rate of 80 and 10 mg per kg. The ED50 of cyclopiazonic acid for two, three and four days old chicken embryo was found to be 2.40, 4.70 and 2.70 micrograms, respectively. Teratogenic effects were observed only in the two days old embryos in which the caudal end of trunk was shortened at the frequency of 0.36 and microophthalmia occurred at the frequency of 0.33. The LD50 of cyclopiazonic acid in day-old cockerels was found to be 21.71 mg per kg of weight.     

The toxicity of phomopsin for sheep

Pure phomopsin was administered to young Merino x Border Leicester wethers by single subcutaneous (SC) and by single and multiple intraruminal (IR) injection. The toxicity after IR injection was influenced by the size of individual doses and the time over which the total dose was given. At high levels of ingestion the toxicity of phomopsin may be limited by absorption rates; with low daily doses the capacity to repair liver damage may be sufficient to prevent cumulative effects. By SC injection a single dose of 10 micrograms/kg approximated the LD50. By IR injection the overall clinical, biochemical and histological responses closest to these of this SC dose resulted from a single dose of 1,000 micrograms/kg. The same total dose administered at daily rates of 50 or 200 micrograms/kg was more toxic and killed all sheep. A single dose of 500 micrograms/kg caused significant liver damage, but no deaths. Single doses of 125 and 250 micrograms/kg and repeated daily doses of 12.5 micrograms/kg over 16 weeks caused no detectable tissue damage. Inappetence was the most sensitive indicator of phomopsin toxicity. About 10% of the sheep differed substantially from the rest of the flock in their susceptibility to phomopsin poisoning.