Maintenance of acquired immunity to Trichostrongylus colubriformis in Merino sheep that are losing weight     

MFJ VAN  HOUTERT  DL WATSON  IA BARGER 《Australian veterinary journal》1995,72(8):301-303

SUMMARY The effect of loss of weight on maintenance of acquired immunity to Trichostrongylus colubriformis in Merino sheep was assessed in 2 experiments. Adult Merino sheep with previously acquired immunity to T colubriformis were housed in individual pens. Sheep were infected 3 times weekly with 2000 T colubriformis larvae. A diet based on chopped oaten and lucerne hay (experiment 1) or a pelleted diet based on lucerne hay and grain products (experiment 2), was offered in amounts to sustain a moderate gain in body weight, or was reduced step-wise to cause a loss in body weight. Worm egg counts were determined weekly. The reduction in feed on offer resulted in a mean weight loss of 4.0 kg over 9 weeks (experiment 1) or 4.8 kg over 7 weeks (experiment 2). Based on worm egg counts, there was no indication of a change in immunity to T colubriformis in either of the experiments. These results suggest that acquired immunity to T colubriformis in adult sheep that are exposed to infection is maintained during periods of moderate loss of weight associated with inadequate nutrition.  相似文献   

Applications of Social Science     

VAN DEN Haag E 《Science (New York, N.Y.)》1959,129(3360):1444

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Evaluation of anthelmintics, antiprotozoal drugs and ectoparasiticides for racing pigeons (Columba livia var. domestica) available in The Netherlands     

R. J. G. ZWIJNENBERG  A. G. VULTO†  A. S. P. J. A. M. VAN  MIERT† J. T. LUMEIJ DVM  PhD 《Journal of veterinary pharmacology and therapeutics》1992,15(4):395-408

Anthelmintics, antiprotozoal drugs and ectoparasiticides specially marketed for use in racing pigeons (Columba livia var. domestica) were evaluated by comparing dosages and indications given by the producers with data obtained from efficacy studies or empirical data. Of a total of 63 products, 59% were in accordance with the literature. Fifty-nine percent of the dosages and indications of anthelmintics were in accordance with scientifically obtained data, while for trichomonacides, coccidiostats and ectoparasiticides the figures were 47%, 59% and 100% respectively. Public health aspects of the consumption of medicated pigeons are discussed.  相似文献   

Pharmacokinetics of sulfadimethoxine and sulfamethoxazole in combination with trimethoprim after intravenous administration to healthy and pneumonic pigs     

M.J.B. MENGELERS  E.R. VAN  GOGH  H.A. KUIPER  A. PIJPERS†  J.H.M. VERHEIJDEN†  A.S.J.P.A.M. VAN  MIERT‡ 《Journal of veterinary pharmacology and therapeutics》1995,18(4):243-253

The pharmacokinetics of two sulfonamide/trimethoprim combinations were investigated after intravenous administration to clinically healthy pigs and to the same pigs following a challenge with Actinobacillus pleuropneumoniae toxins. Endobronchial challenge with A.pleuropneumoniae toxins resulted in fever, increased white blood cell counts and decreased water and feed consumption. Healthy, as well as febrile, pigs were given sulfadimethoxine (SDM) or sulfamethoxazole (SMX) intravenously at a dose of 25 mg/kg b.w. in combination with 5 mg trimethoprim (TMP) per kg body weight. The pharmacokinetic parameters of the sulfonamides as well as their main metabolites (acetyl sulfonamides) were not significantly different in healthy and febrile pigs. In healthy and pneumonic pigs, the mean elimination half-lives of SDM were 12.9 h and 13.4 h, respectively, those of SMX 2.5 h and 2.7 h, respectively, and those of TMP 2.8 h and 2.6 h, respectively. Distribution volumes in healthy and febrile pigs of SDM and SMX varied between 0.2 and 0.4 L/kg, and those of TMP between 1.1 and 1.6 L/kg. The mean AUC of TMP was decreased and the volume of distribution and total body clearance of TMP were increased in febrile pigs. Protein binding of the drugs and metabolites studied were not significantly changed after toxin-induced fever. The extent of protein binding of SDM, SMX and TMP was in the range 94–99%, 45–56% and 40–50%, respectively. Based on knowledge of in vitro antimicrobial activity of the drug combinations against A.pleuropneumoniae it was concluded that after intravenous administration of the dose administered (30 mg/kg of the combination preparations) to healthy and pneumonic pigs, plasma concentrations of SMX and TMP were above the concentration required for growth inhibition of 50% of A., pleuropneumoniae strains for approximately 16 h, whereas bacteriostatic plasma concentrations of SDM were still present after TMP had been eliminated from plasma. Because of similar elimination half-lives of SMX and TMP in pigs this combination is preferred to the combination of SDM with TMP.  相似文献   

The use of thermal calendar models to improve the efficiency of herbicide applications in Sorghum halepense (L.) Pers     

C. M. GHERSA  E. H. SATORRE  M. L. VAN  ESSO  A. PATARO  R. ELIZAGARAY 《Weed Research》1990,30(3):153-160

The dynamics of sprout emergence and rhizome populations of Sorghum halepense (L.) Pers. were followed in two field experiments. In addition, the herbicide dalapon was applied at various stages during rhizome development and the degree of control was evaluated. Rhizome biomass oscillated during the growth cycle, whereas the number of rhizome sprouts increased asymptotically until mid-summer. Observed values were compared against those predicted from a thermal calendar model. The dynamics of the rhizome population was predicted accurately in both experiments, but only in one of them was the prediction of the sprout emergence satisfactory. The degree of control differed markedly between herbicide applications at various intervals during population development. Best results were obtained from applications when rhizome biomass was at a minimum. The time of minimum biomass was predicted by a thermal calendar model. The advantages of using the thermal calendar model to determine the time of herbicide application, and the possible influence of the distribution of the rhizome population in the soil profile on the predictions of the model, are discussed.  相似文献   

Occurrence of a viroid in chrysanthemum in Brazil     

A. N. DUSI  M. E. N. FONSECA  A. C. DE  ÁVILA 《Plant pathology》1990,39(4):636-637

A viroid was detected in Chrysanthemum plants showing symptotns of stunting in a commercial field in Brazil. Analysis by return polyacrylamide gel electrophoresis (R-PAGE) of the nucleic acid preparations of leaves and flowers revealed the presence of a nucleic acid of low molecular weight with mobility within the range of viroids. The viroid-like band was completely eliminated by ribonuclease treatment or alkaline hydrolysis. The Chrysanthemum viroid was readily transmissible to Chrysathemum , tomnato and Gynura , which suggests that it may be an isolate of chrysanthemum stunt viroid.  相似文献   

The requirement of Cichlasoma urophthalmus (Günther) fry for pantothenic acid and the pathological signs of deficiency     

M. C. CHAVEZ DE  MARTINEZ  B. L. ESCOBAR  M. A. OLVERA-NOVOA 《Aquaculture Research》1990,21(2):145-156

Abstract. Fry of Cichlasoma urophthalmus (Günther) weighing 160-175 mg were fed for 75 days on diets containing seven different levels of calcium pantothenate. Fish fed on the three lowest inclusion levels (up to 0,10 and 20 mg/kg) exhibited a variety of external signs and high mortalities. Fish fed on the higher inclusion levels (40, 60, 80, 120 and 320 mg/kg) did not show external pathologies. At the end of the experiment there was no significant difference in these diets (P<0.01) in final weight, individual weight gain, individual food intake, food conversion ratio, and specific growth rate. Marked interlamellar lesions were observed in gills of fish fed on the lowest inclusion level diets. The lesions ranged from oedema, hyperplasia covering all the secondary lamellae to the complete fusion of adjacent filaments. These fish also developed necrosis of the pancreas, whilst fish fed diets up to 80 mg/kg showed marked glycogen deposition in the hepatic cells. For the first time it is reported that fish deficient in pantothenic acid showed ceroid deposition in the hepatic cells and spleen. Fish fed on diets containing 80-320 mg/kg did not show external or histological changes. It is thus recommended that the diet of C. urophthalmus fry must be supplemented with at least 80 mg/kg diet to give maximum growth and to avoid gross and histologicai signs of deficiency.  相似文献   

Pharmacokinetics and anthelmintic efficacy of febantel in the racing pigeon (Columba livia)     

L. BAERT  S. VAN POUCKE  H. VERMEERSCH  J. P. REMON  J. VERCRUYSSE†  P. BASTIAENSEN†  P. DE BACKER† 《Journal of veterinary pharmacology and therapeutics》1993,16(2):223-231

This paper reports on the pharmacokinetics and the efficacy of febantel against Capillaria obsignata and Ascaridia columbae in the racing pigeon. Febantel was rapidly cleared from the circulation and highly metabolized. The efficacy of febantel against Capillaria and Ascaridia was studied on lightly and heavily infected pigeons. The efficacy against Ascaridia was 100% for the faecal egg count reduction (FECR) as well as for the worm reduction in all treated pigeons. After two treatments with febantel against Capillaria in heavily infected pigeons the FECR amounted to 96.7% and worm reduction was 95%. In order to effectively remove both parasites from the host, repeated treatments with febantel at a short interval could be the treatment of choice.  相似文献   

In vitro and in vivo binding of trimethoprim and sulphachlorpyridazine to equine food and digesta and their stability in caecal contents     

E. VAN DUIJKEREN  B.G.F. KESSELS  M. M. SLOET van  OLDRUITEN-BORGH-OOSTERBAANH. J. BREUKINK  A. G. VULTO†  A.S.J.P.A.M. van  MIERT‡ 《Journal of veterinary pharmacology and therapeutics》1996,19(4):281-287

Binding of antibiotics to food has received little attention in equine medicine, although such binding could potentially reduce the bioavailability and clinical efficacy. In the present study, binding of trimethoprim (TMP) and sulphachlorpyridazine (SCP) to hay, grass silage and concentrate was investigated in vitro in buffer at pH 6.8 at different concentrations. The binding of TMP and SCP to caecal contents was also studied. In addition, the degradation of TMP and SCP by the caecal microflora was investigated by incubating sterilized and non-sterilized caecal contents for 3 h at 37° under anaerobic conditions and comparing the TMP and SCP contents. Further, a TMP/SCP powder formulation was adminstered orally with concentrate at a dose rate of 5 mg/kg TMP and 25 mg/kg SCP to three ponies with a caecum fistula; the animals were deprived of food for 8 h before administration. Blood samples, caecal contents samples and faecal samples were collected and analysed for TMP and SCP concentrations by means of high performance liquid chromatography (HPLC). Three non-fistulated ponies, acting as control animals, were fed the same dose of TMP/SCP with concentrate after 8 h of food deprivation and blood samples were taken. The percentage of in vitro binding of TMP as well as SCP to hay, grass silage and concentrate at concentrations of 4 μg/mL to 10 μg/mL was high (60-90%). TMP and SCP were also extensively bound to caecal contents (50-70%). At spiking concentrations above 10 μg/mL the percentage of binding decreased. There was no evidence of biodegradation of TMP or SCP in caecal contents. In vivo, both drugs could be detected in the caecal contents and in the faeces of three fistulated ponies. However, the fistulated ponies differed from the control ponies in that their TMP and SCP plasma concentrations were higher, and two fistulated ponies did not show double peaks in their plasma concentration-time curves. Therefore, the fistulated ponies did not provide an optimal model for in vivo binding studies. Despite this limitation, it can be concluded that binding of TMP and SCP to food is a major cause of the limited bioavailability of these drugs in the horse. It is hypothesized that the binding is reversible, and that a second absorption phase occurs in the large intestine, but part of the administered dose remains bound as both drugs were found in the faeces.  相似文献   

Age-dependent pharmacokinetics of oxytetracycline in ruminants     

J. F. M. NOUWS  C. A. M. VAN  GINNEKEN† G. ZIV‡ 《Journal of veterinary pharmacology and therapeutics》1983,6(1):59-66

Oxytetracycline (OTC) was administered intravenously (i.v.) to 3-and 12-week-old calves and lactating cows, and both i.v. and intramuscularly (i.m) to 14-week-old calves and non-lactating cows. Concentrations of OTC were determined in plasma and were analysed kinetically. The pharmacokinetic parameters which were derived using the three-compartment open model were inadequate to describe plasma drug levels in six out of the 23 animals treated i.v., and, therefore, model-independent kinetic parameters were utilized for evaluating age-dependent pharmacokinetics of OTC. In the 3-week-old calves, the total body clearance (Cl b ) was 0.0022 ml/min/kg, the total distribution volume (V d area ) was 2.48 l/kg, and the distribution volume of the central compartment (V 1 ) was 0.56 l/kg. Mean values for Cl b , V d area , and V 1 in 3-week-old calves were two-, three- and four-fold greater, respectively, than the corresponding values in cows. Mean values of Cl b and V d area for the 12-and 14-week-old calves were intermediate between the corresponding values in 3-week-old calves and cows. Dose and state of lactation did not affect the model-independent parameters. The i.v. and i.m. data illustrated that the recommended dose levels of OTC in young calves should be twice those employed in cows for obtaining similar plasma OTC concentration-time profiles.  相似文献