Lack of mutagenicity of fasciolicides

Six fasciolicides, bithionol, bromofenofos, DS-6, nitroxynil, oxyclozanide and tribromsalan, were tested for mutagenicity in the Salmonella reverse mutation test using S. typhimurium tester strains TA100, TA98, TA1535, TA1537 and TA1538 and the micronucleus test in mice. None of the fasciolicides increased the number of revertant colonies in any tester strain in the presence and absence of S9 mix, nor did they induce a significant increase of the micronuclei in erythrocytes. Taking the high correlation between mutagenicity and carcinogenicity into consideration, these results suggest that the fasciolicides tested in this investigation are devoid of carcinogenic action.     

橘皮素乙酰酯致突变性研究

橘皮素乙酰酯是搐皮素结构改造后获得的衍生物，是一种新型杀螨药物，通过Ames试验、小鼠骨髓细胞微核试验、精子畸形试验，考察了橘皮素乙酰酯的致突变性。结果：在活化与非活化条件下，诱发TA97、TA98、TAl00和TAl02的回变菌落数与自发回变菌落数相近，无剂量反应关系；各试验组微核率(2．20‰～2．40‰)与阴性(2．00‰)和溶剂对照组(1．88‰)相近；精子畸形率(2．48％～2．72％)与阴性(2．36％)和溶剂对照组(2．06％)比较也无显著差异。表明橘皮素乙酰酯无致突变性．     

亚硒酸钠突变试验研究

为评价亚硒酸钠的致突变性,进行了Ames试验,结果表明：在5～0.008 mg亚硒酸钠/皿剂量范围内,在加S9混合物和不加S9混合物时,受试物对鼠伤寒沙门氏菌TA97、TA98、TA1535、TA100、TA102五株试验菌株,在加与不加S-9时试验结果均为阴性.     

Mutagenicity of water samples from five cities in Korea

Four doses (equivalent to 4, 2, 1, and 0.5 liter water) of organic extracts from raw, treated and drinking waters sampled from seven different treatment plants in five cities in Korea were challenged to the Ames test using S. typhimurium strains TA98 and TA100 in the presence/absence of S9 mix. The mutagenicity was usually observed from chlorine-treated (28.6%) and drinking (42.9%) waters rather than raw (3.4%) waters. The strain TA98 (33.3%) was more sensitive to detect the mutagenicity of water samples than the strain TA100 (16.7%). However, the absence of S9 mix showed higher mutagenic activity of waters compared to the presence of S9 mix, corresponding to the detection of 42.9% and 7.1%, respectively. These results indicate that the bacterial mutagenicity of treated and drinking waters may be derived from chlorination in water treatment plants but that the mutagenicity in humans may be limited due to enzymatic metabolism.     

紫锥菊提取物的Ames试验

通过对紫锥菊提取物进行昆明种小鼠伤寒沙门氏菌回复突变试验,评价该材料的潜在致突变性。用紫锥菊提取物制备混悬液进行Ames（致突变）试验,采用平板掺入法,计数TA97、TA98、TA100、TA102标准测试菌株在4个不同浓度下,于37℃培养48h后的回复突变菌落数。结果显示无论在＋S9和-S9的情况下,各剂量组均未引起测试菌株回变菌落数的明显增加,Ames试验结果为阴性。说明紫锥菊提取物不引起鼠伤寒沙门氏菌的回复突变数增加,无致基因突变性。     

Studies ofStreptococcus suis type 2 infection in pigs

Investigations into the immunology, pathogenesis and epidemiology ofStreptococcus suis type 2 infections were carried out in experimental pigs and in naturally-occurring field outbreaks of disease.The capsular polysaccharide fromStr. suis type 2 was shown to induce opsonic antibodies in pigs when injected with Freund's incomplete adjuvant, but difficulties encountered in experimental production of the disease prevented a study of their protective effects.Problems with the bactericidal tests led to an investigation of other assays for antibodies againstStr. suis type 2, namely, a phagocytic test with pig neutrophils, a mixed reverse passive antiglobulin haemagglutination test and an indirect haemagglutination test. There was evidence that with modifications both the latter tests would be useful.Transmission studies in 39 conventionally-reared and 7 hysterectomy-derived, colostrum-deprived pigs yielded interesting results with regard to the distribution of the organism in relation to the disease process.Tonsil carriage in clinically-healthy pigs was demonstrated after experimental and natural infection. Detectable carrier rates varied between 0 and 59%. The organism was shown to persist in the presence of circulating opsonic antibodies and in pigs on penicillin-medicated feed. Attempts to isolate the organism from the genital tract were unsuccessful.Medicated early weaning and classical SPF techniques applied to infected herds appeared to be effective in producing pigs free fromStr. suis type 2 infection.     

Mutagenicity,Creatine and Nutrient Contents of Pan Fried Meat from Various Animal Species

The mutagenic activity in extracts of fried meat from 16 different animal species was studied in Salmonella typhimurium TA98. In each experiment, 1 meat sample together with a standard beef sample was fried, and the mutagenicity was expressed relative to the beef sample. All meat samples showed less mutagenic activity than beef. The contents of creatine, creatinine, water, protein, carbohydrate and fat in the meat samples were analyzed, but mutagenicity was not correlated with the concentration of any of these constituents. Beef meat treated with creatinase to remove creatine produced reduced mutagenic activity. Possibly a threshold concentration of creatine is necessary to give a high mutagenic response.     

Decontamination of Campylobacter jejuni on chicken drumsticks using chemicals and radiation

A trial was conducted to compare the efficacy of four disinfectants and radiation to reduce the level of C. jejuni contamination on poultry meat. Two levels of each treatment were applied to chicken drumsticks inoculated with a known concentration of a strain of Campylobacter jejuni, biotype 1, isolated from a human patient with diarrhea.Radiation using a cobalt-60 source at a level of 0.5 KGy effected a 99% surface reduction in C. jejuni. With a mean initial surface contamination level of 1.1 × 10³ Colony Forming Units/cm², 1 KGy completely eliminated C. jejuni. Glutaraldehyde at 0.5% concentration for 30 minutes had an efficacy similar to the lower dose of radiation. Chlorine showed a negligible effect on C. jejuni. Succinic acid and Poly (hexamethylenebiguanide hydrochloride) were statistically similar in their effectiveness, ranking between glutaraldehyde and chlorine.These results strongly indicate that, of the alternatives tested, low-dose radiation is the method of choice for reducing Campylobacter contamination of poultry products.     

Pharmacokinetic behaviour and anthelmintic efficacy of 1-n-butyl carbamoyl oxfendazole given by intramuscular injection

Oxfendazole (OFZ) was chemically modified to 1-n-butyl carbamoyl OFZ (C₄-OFZ) in an attempt to improve the solubility of OFZ and enable it to be administered by injection. After intramuscular injection to sheep and cattle, C₄-OFZ was metabolised to OFZ which resulted in higher plasma OFZ concentrations that persisted for a considerably longer period than those observed following administration of OFZ orally. The anthelmintic efficacy of injected C₄-OFZ was tested, in sheep, against strains ofTrichostrongylus colubriformis,Haemonchus contortus andOstertagia circumcincta, which were highly resistant to benzimidazoles. In all cases, the C₄-OFZ treatment showed a significant improvement in efficacy over the conventional oral OFZ drench.     

鼠伤寒沙门氏菌致突变试验的方法学研究

本文对鼠伤寒沙门氏菌致突变试验在国内实验条件下方法标准化进行了研究。国产试剂配制的营养肉汤可满足试验菌株的营养需求,烧瓶振荡培养10小时即可达1～2×10~9存活菌/ml,肉汤培养物稀释后测定OD650可监测细菌密度。国产五氯联苯和Aroclor 1254诱导的Sprague-Dawley及Wistar大鼠肝S9活化苯并(a)芘及2-乙酰氨基芴的能力相似(P>0.05)。本文还提出以点试验估计受试物毒性及以参比物减小或消除多次实验间的误差。     

Identification of antigenic epitopes of the SapA protein of Campylobacter fetus using a phage display peptide library

In this study, we immunized mice with prokaryotically expressed recombinant surface layer protein, SapA, of Campylobacter fetus, generated hybridomas secreting mouse monoclonal antibodies (mAb) targeting SapA, and purified the mAb A2D5 from mouse ascites using saturated ammonium sulfate solution. The mAb A2D5, coated onto ELISA plates, was used to screen the phage random 12-peptide library through three rounds of panning. Following panning, 15 phage clones were randomly chosen and tested for reactivity with mAb A2D5 by indirect ELISA. Single-stranded DNA from positive clones was sequenced and compared with the sequence of SapA to predict the key epitope. ELISA and/or Western blot analyses further validated that synthetic peptides and recombinant peptide mimotopes all interact with mAb A2D5. Nine of ten positive phage clones identified by screening were sequenced successfully. Seven clones shared the same sequence HYDRHNYHWWHT; one had the sequence LSKNLPLTALGN; and the final one had the sequence SGMKEPELRSYS. These three sequences shared high homology with SapA J05577 in the region GNEKDFVTKIYSIALGNTSDVDGINYW, in which the underlined amino acids may serve as key residues in the epitope. ELISA and/or Western blot analyses showed that mAb A2D5 not only interacted with the four synthetic peptide mimotopes, but also with 14 prokaryotically expressed recombinant peptide mimotopes. The mimotopes identified in this study will aid future studies into the pathological processes and immune mechanisms of the SapA protein of C. fetus.     

Efficacy of the avermectins against filarial parasites: A short review

The avermectins are macrocyclic lactones produced byStreptomyces avermitilis. One of them has been chemically modified and given the non-proprietary name invermectin. The compounds have shown efficacy against various stages of filarial parasites. With respect to pre-adult stages in the mammalian host, activity has been observed againstDirofilaria immitis in ferrets and dogs, andDipetalonema viteae andLitomosoides carinii in jirds (Meriones); but activity has not been observed against the developing stages ofBrugia spp. in jirds orOnchocerca spp. in cattle. The compounds have not shown activity against adult filarial worms, except in the case ofSetaria equina in horses and possiblyDipetalonema viteae in jirds. With respect to the first stage larva (microfilaria) in the mammalian host, efficacy has been observed againstDirofilaria immitis in dogs,Brugia malayi in multimammate rats (Mastomys),Dipetalonema viteae andLitomosoides carinii in jirds andOnchocerca spp. in horses and cattle; but activity has not been observed against microfilariae ofBrugia pahangi in jirds or cats. Efficacy against filarial parasites has been observed following oral or parenteral administration of drug, sometimes at extremely low dosage. For example, a single oral dosage of 0.05 mg/kg was highly active against the third and fourth larval stages and microfilariae ofD. immitis in dogs.     

Bovine homocytotropic antibody in the sera of cattle resistant to infestation withRhipicephalus appendiculatus

The homologous skin sensitizing activity of serum from tick-naive cattle (Bos taurus) and from cattle resistant to the tickRhipicephalus appendiculatus was tested by attempting to induce passive cutaneous anaphylaxis (PCA) in ticknaive calves. The serum from tick-resistant cattle induced PCA, whereas that from tick-naive cattle failed to do so. The PCA was more marked at 72 hours than at 24 hours after administration of the serum. Treatment of the serum by heat at 56°C for 2 hours or by adding 0.1 M 2-mercaptoethanol to it reduced its ability to sensitize.Serum from tick-resistant cattle did not sensitize the skin of heterologous species, namely rabbits, guinea-pigs and rats.     

Studies onEscherichia coli vaccines: Estimation of endotoxins in veterinary vaccines

Fifteen batches ofE. coli vaccines for pigs, from three different manufacturers, were subjected to a quantitative form of the in vitro Limulusamoebocyte-lysate (LAL) test for their free endotoxin content. A batch of vaccine associated with abortions in pregnant sows was found to contain a much higher level of free endotoxin than batches of vaccine not associated with abortion. The evidence of these assays suggests that they will be useful in the quality control ofE. coli vaccines.     

Intestinal helminths of cats in the Kainji Lake area Nigeria

Six parasitic helminths detected wereAncylostoma sp.,Opisthorchis felineus,Toxocara mystrax,Hepaticola hepatica,Taenia sp. andHydatigera taeniaeformis. The prevalence ofH.hepatica,T.mystrax andH.taeniaeformis is associated with rodents hunted by cats, and that ofO.felineus with fish fed to cats. The role of cats as primary host and reservoir for these helminths, which could be of zoonotic importance, is briefly mentioned.     

Microbiology of the genitalia of nulliparous and postpartum Savanna Brown goats

A study of the bacterial flora of the genitalia of nulliparous Savanna Brown does was carried out both before breeding and at different intervals postpartum to investigate the type of microbial organisms that could be present in the uterus, cervix and the vagina respectively.Of 29 pre-breeding vaginal swabs, Staphylococcus sp. was isolated from 20 goats, Streptococcus sp. from 15 goats and Micrococcus sp. from four goats. Mycoplasma agalactiae was isolated from five goats.The postpartum vagina did not show any appreciable change in the microbial flora, except that Escherichia coli was encountered in two cases. The uterus yielded E. coli from the goats slaughtered 2 days postpartum; Micrococcus sp. from goats slaughtered 12 days postpartum; Staph. aureus from goats slaughtered 16 days postpartum and Staph. aureus from goats slaughtered 24 days postpartum.Also in these two cases — a goat slaughtered at two days postpartum (dpp) and a goat slaughtered 16 dpp — E. coli was present in the uterus. Other isolates from the uteri of slaughtered goats were Micrococcus sp. (12 dpp), Staph. aureus and Micrococcus sp. (16 dpp) and Staph. aureus (24 dpp).     

Etiology and pathogenesis of necrotic enteritis

Sporulated oocysts ofEimeria acervulina were administered orally to cage-housed broilers at a dose of 3.5×10⁵ resulted in mild subclinical coccidiosis.Clostridium perfringens incorporated in feed at a level of 2.5×10⁸ organisms/g. produced lesions characteristic of necrotic enteritis. Mortality of 8% (7/80) occurred in birds fed a ration inoculated withCl. perfringens alone. Mortality of 35% (28/80) was observed in birds which received an oral dose ofE. acervulina and which were fed simultaneously with a ration containingCl. perfringens. Birds which were fed an inoculated ration two days after an oral dose ofE. acervulina showed 41% (33/80) mortality. Birds which received an inoculated ration for two days before administration of an oral dose ofE. acervulina demonstrated 18% mortality (15/80). Birds which were fed an inoculated ration four days after an oral dose ofE. acervulina showed 10% mortality. Infection withE. acervulina reduced the pH of intestinal contents with a simultaneous depression in serum protein. A 39% increase in intestinal passage time from 178 to 248 minutes occurred on the fifth day after infection withE. acervulina. These experiments suggest that necrotic enteritis, attributed to proliferation of a toxigenic strain ofCl. perfringens, followed intestinal stasis and minimal lesions induced by mild intestinal coccidiosis.     

Immunogenicity of a soluble antigen againstPasteurella haemolytica-associated pneumonia in calves

Three experiments were performed to evaluate the immunogenic potency of a soluble fraction ofPasteurella haemolytica against pneumonic pasteurellosis in calves. A soluble antigen was extracted by a 2.5% saline solution fromP.haemolytica. Weaned Holstein bull calves, seronegative for infectious bovine rhinotracheitis virus (IBRV) and the pasteurella antigen, were vaccinated either by repeated subcutaneous (SC) vaccination, or by exposure 3 times to the aerosol ofP.haemolytica antigen. Challenge exposure to aerosol ofP.haemolytica was preceded by infection with IBRV, or in experiments 2 and 3, the virus exposures were combined with a stress treatment. The lung lesions were examined at necropsy 3 to 8 days post infection. In the first experiment, all the vaccinated calves produced specific antibody response to the pasteurella antigen, and none of the calves including controls showed significant lesions in the lung. In the second experiment 2 aerogenically vaccinated calves had no lesions. One of the two SC-vaccinated calves had mild consolidated lesions. Two control calves, one of which died 3 days following the challenge, developed severe fibrinous pneumonia with consolidation of 50% or more of the lung surfaces.P.haemolytica was isolated only from the 2 control animals. In the third experiment, 2 of the 3 control calves developed moderate to severe consolidation, butP.haemolytica was isolated only from one of them. Two of the three aerosol-vaccinated calves also developed significant lesions and one of them yielded the bacteria from the lung. Three SC-vaccinated calves had slight lesions and the organism was not isolated from their lungs. The results did not consistently indicate an immunogenic potential of the soluble antigen againstP.haemolytica-related pneumonia. The effect of stress on the pathogenesis of bovine viral penumonia and correlation between pneumonic lesions and antibacterial resistancein situ are discussed.     

Kinetics of levamisole-induced potentiation of lymphocyte blastogenic responses inMycobacterium bovis sensitized lymphocyties

A study was conducted to determine the kinetics of levamisole-induced potentiation of lymphocyte blastogenesis inMycobacterium bovis sensitized and nonsensitized cattle lymphocytes. It was observed that levamisole significantly potentiated PPD-induced blastogenic responses when it (levamisole) was added toM. bovis sensitized lymphocyte cultures 24 hours prior to the addition of PPD. Levamisole-induced either minimal or suppressed the PPD-induced lymphocyte stimulation response inM. bovis nonexposed control lymphocytes. The implications of possible use of levamisole in cellularin vitro assays for studying anergy or general unresponsiveness are discussed.     

A review of studies on three mouse-infectiveT. vivax strains

The literature is reviewed of three strains ofT.vivax which retained their characteristics ofT.vivax after serial passage through mice. These mouse infective (m.i.) strains were used to study the surface coat ofT.vivax, antigenic variation and behaviour in rodents and ruminants.The m.i.T.vivax Y58 was mildly virulent for ruminants, causing a hemolytic anaemia, thrombi and in the more chronic stage a myocarditis with extravascular parasites. The relation between bradykinin levels, parasitaemia, fever, pulse rate and forestomach motility was not clear. The fall in serotonin levels was caused by thrombocyte aggregation, followed by release, degradation and/or reuptake of the serotonin. No systematic role could be attributed to the released serotonin. Some of the strains have been tested for their drug susceptibility, whereby dose rates higher than generally recommended had to be used in order to clear the animals completely from the parasites.

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Kurzfassung Es wird eine Literaturübersicht gegeben über dreiT. vivax-Stämme, die ihreT. vivax-Eigenschaften nach Serienpassagen in Mäusen beibehalten haben. Diese Mäuse-infektiösen (m.i.)-Stämme wurden für das Studium des Oberflächenmantels vonT. vivax, von Antigenvariationen und ihr Verhalten in Nagern und Wiederkäuern verwendet.Der m.i.T. vivax-Stamm Y58 war schwach virulent für Wiederkäuser, der zu einer hämolytischen Anämie, Thrombenbildung und während der mehr chronischen Stadien zu einer Myocorditis mit extravaskulären Parasiten führte. Die Beziehungen zwischen Bradykinin-Spiegel, Parasitämie, Fieber, Pulsrate und Vormagenmotilität waren nicht klar. Der Abfall des Serotoninspiegels wurde durch Thrombozytenaggregation verursacht mit nachfolgendem Freiwerden, Abbau und/oder Wiederaufnahme von Serotonin. Eine systemische Rolle konnte dem freigewordenen Serotonin nicht zugeschrieben werden. Einige der Stämme wurden auf ihre Arzneimittelempfindlichkeit getestet, wobei höhere Dosierungen als allgemein empfohlen angewendet werden mussten, um die Tiere vollständig parasitenfrei zu bekommen.

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Resume La littérature est recensée à propos de trois souches deT. vivax qui conservent leurs caractéristiques après plusieurs passages en série chez la souris. Ces souches pathogènes pour la souris ont été utilisées pour étudier l'enveloppe de surface deT. vivax, ses variations antigéniques et son comportement chez les ruminants et les rongeurs.La soucheT. vivax Y58 étant faiblement virulente pour les ruminants, provoquait une anémie hémolytique, des thrombi et au cours d'une phase plus tardive une myocardite avec présence de parasites extra cellulaires. La relation existant entre les taux de bradykinine, la parasitémie, la fièvre, la fréquence du pouls et la motricité des estomacs n'était pas claire. La chute du taux de sérotonine était causée par l'aggrégation plaquettaire, suivie de la production, de la dégradation et/ou de la réutilisation de la sérotonine. Aucun rôle particulier n'a pu être attribué à la réutilisation de la sérotonine. Aucum rôle particulier n'a pu être vis-à-vis de certains médicaments, des doses plus élevées que celles habituellement recommandées doivent être utilisées pour stériliser les animaux.

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Riassunto Tre ceppi diT. vivax hanno mantenuto le caratteristiche proprie diT. vivax dopo passaggio seriale su topini. Tali ceppi patogeni per il topo (p.t.) sono stati impiegati per studiare la cuticola superficiale del parassita, la variazione antigenica ed il comportamento nei roditori e nei ruminanti. T. vivax Y58 p. t. è risultato lievemente virulento per i ruminanti in quanto ha causato anemia emolitica, trombi e, nello stadio di tipo più cronico, una miocardite con presenza di parassiti in sede extravascolare. La relazione fra i livelli di bradichinina, la parassitemia, la febbre, la frequenza del polso e la motilità dei prestomaci non è risultata chiara. La caduta dei livelli di serotonina è state causata dall'aggregazione dei trombociti, seguìta da liberazione, degradazione e/o rialzo della serotonina. Non è stato possibile attribuire alcun ruolo sistematico alla serotonina liberata. Alcuni dei ceppi sono stati saggiati nei riguardi della sensibilità ai farmaci, stabilendo così che si dovevano usare dosaggi superiori a quelli generalmente raccomandati per liberare completamente gli animali dai parassiti.