Microsatellite variation between an African and five European taurine breeds results in a geographical phylogenetic tree with a bison outgroup

Genetic variation is being used extensively for individual identification and linkage analysis, and may be useful for interpopulation studies. Previously, blood groups and biochemical variants in blood cell and serum proteins have been used to study (evolutionary) relationships in mammals. But genetic divergence and gene flow among closely related populations are difficult to measure with these classical markers because their mutation rate is so low that new mutations have not had sufficient time to appear and become fixed. So they have a small number of alleles and a relatively low level of heterozygosity. These markers are now replaced by DNA markers, mostly microsatellites. These microsatellite loci are useful genetic markers at which alleles differ in length due to differences in the number of short sequence motifs arranged adjacent to one another. They are abundantly distributed throughout the mammalian genome. They have a large number of alleles, a high level of heterozygosity and are inherited in true Mendelian fashion. These characteristics make them valuable for parentage control, linkage analysis, genome mapping and phylogenetic studies. In terrestrial vertebrates with limited mobility, genetic differentiation often increases with the distance between populations or corresponds to the extent of geographic and habitat barriers (R oy et al. 1994). Investigations of short tandem repeats yield a considerable volume of genetic data regarding the similarities and divergence times of different cattle populations. Microsatellite markers are suitable for the estimation of these parameters as they are not generally subject to direct selection and environmental influences. Computation of genetic distances based on data from several loci can be used to evaluate the taxonomic relationship between populations. The aim of this study was to estimate the relative genetic variability between Belgian cattle breeds and to reconstruct the evolutionary relationship among them, also using two small genetically isolated cattle-like populations.     

Investigating the Link between Particulate Exposure and Airway Inflammation in the Horse

Inhalant exposure to airborne irritants commonly encountered in horse stables is implicated in the pathogenesis of inflammatory airway disease (IAD) and recurrent airway obstruction (RAO), non‐infectious, inflammatory pulmonary disorders that impact the health and performance of horses across all equine disciplines. IAD and RAO have overlapping clinical, cytological, and functional manifestations of the pulmonary response to organic dust and noxious gases encountered in the barn environment. Study of these diseases has provided important but incomplete understanding of the effect of air quality upon the respiratory health of horses. In this review, the principles of particulate exposure assessment, including health‐related aerosol size fractions and size‐selective sampling, the factors influencing air quality in equine environments, and the effect of air quality on the equine respiratory tract are discussed. The objective of this review is to provide the reader with a summary of the most common chronic inflammatory airway diseases in the horse and the principles of air sampling that are essential to the planning, interpretation, and assessment of equine respiratory health‐related exposure studies.     

The pharmacokinetics and metabolism of ivermectin in domestic animal species

The pharmacokinetic properties of drugs are closely related to their pharmacological efficacy. The kinetics of ivermectin are characterised, in general terms, by a slow absorption process, a broad distribution in the organism, low metabolism, and slow excretion. The kinetics vary according to the route of administration, formulation, animal species, body condition, age, and physiological status, all of which contribute to differences in drug efficacy. Characterisation of ivermectin kinetics can be used to predict and optimise the value of the parasiticide effects and to design programmes for parasite control. This article reviews the pharmacokinetics of ivermectin in several domestic animal species.     

Metallic foreign bodies in the tongues of 16 horses

The history, clinical signs, results of diagnostic imaging, treatment methods and outcome of 16 adult horses with a metallic foreign body in the tongue are reviewed. All the horses had a swollen tongue, they salivated excessively and were partially to completely anorexic. Less common clinical signs were fever, an enlarged and painful intermandibular space, dysphagia, unilateral tongue paralysis and halitosis. Most of the horses had shown clinical signs for less than 24 hours. The foreign bodies were diagnosed by oral examination, radiography and ultrasonography; they were removed from the tongue of four of the horses during the initial oral examination, and were removed surgically from nine others; the other three horses were treated medically without attempts being made to extract the foreign bodies. Twelve of the bodies were small pieces of wire and one was a hypodermic needle. All the horses received a combination of antimicrobial and non-steroidal anti-inflammatory drugs and they all made an uneventful recovery. Feeding hay and the use of cable-framed tractor tyres as feeders were commonly associated with the cases.     

Beacon-like immunoreactivity in the hypothalamus of domestic chick

Beacon-immunoreactive (B-ir) fibres and neurons in the hypothalamus of the domestic chick (Gallus domesticus) were studied using an immunohistochemical technique in order to verify the presence and elucidate the pattern of distribution of this novel peptide in an avian brain. B-ir neurons were seen in the n. supraopticus, pars ventralis and pars externus; n. magnocellularis preopticus, pars dorsalis, medialis and ventralis; n. preopticus periventricularis; n. suprachiasmaticus, pars medialis; n. ventrolateralis thalami. Only few B-ir cells were scattered in the most anterior part of the lateral hypothalamic area. B-ir fibres, appearing as thin punctuate structures, were seen mainly along the walls of the third ventricle and in the ventromedial hypothalamus. Labelled fibres and terminals were located in the external and internal zones of the anterior and posterior median eminence. In particular, fibre terminals were seen close to the capillary loops of the hypothalamo-hypophysial portal system. The anatomical data of the present study regarding the distribution of B-ir in the chick hypothalamus suggest that beacon may play a key role in the regulation of the neuroendocrine system by acting as a neuromodulator and/or neurotransmitter.     

Effect of Angiotensin II Type 1 receptor blocker on cardiac angiotensin-converting enzyme and chymase-like activities, and cardiac fibrosis in cardiomyopathic hamsters

It has been reported that cardiac chymase has an effect on cardiac fibrosis through the Angiotensin (Ang) II formation and an Ang II-independent mechanism. In the present study, Ang II type 1 (AT1) receptor blocker (candesartan cilexetil) was administered to dilated cardiomyopathic (DCM; Bio TO2) hamsters for 4 weeks to study the effect of AT1 receptor blocker on cardiac chymase-like activity and cardiac fibrosis. Echocardiography, histological examination, and assessment of cardiac angiotensin-converting enzyme (ACE)/chymase-like activities were conducted. Hamsters showed cardiac dysfunction due to increased left ventricular dimensions and decreased ventricular wall thickness, significant increase in cardiac chymase-like activity, and fibrosis. This result indicates that the cardiac chymase-like activity is responsible for cardiac fibrosis. When candesartan cilexetil was administered to Bio TO2 hamsters, cardiac chymase-like activity increased significantly, whereas cardiac fibrosis decreased significantly. Cardiac ACE and chymase-like activities were unchanged in non-DCM hamsters with candesartan cilexetil. This suggests that the cardiac Ang II formation mechanism was stimulated by suppressing the effect of cardiac Ang II, and cardiac chymase-like activity could be increased. Moreover, this mechanism may be more highly activated if cardiac Ang II is activated in the heart. In conclusion, we demonstrated that AT1 receptor blocker reduced cardiac fibrosis, although cardiac chymase-like activity increased. Because the Ang II-forming pathway and the effect of chymase in hamsters is similar to that in dogs, the results of the present study may supplement the available information for dogs.     

Optimization of conditions for in vitro production of radical oxygen species and expression of tissue factor by canine mononuclear cells and granulocytes for use in high-throughput assays

The purpose of this study was to optimize conditions for high throughput measurement of radical oxygen species (ROS) production and expression of tissue factor, also termed procoagulant activity, by canine leukocytes. Granulocytes and mononuclear cells were separated by density gradient centrifugation from peripheral blood collected on several occasions from three healthy large breed dogs. To determine optimal conditions for ROS production, granulocytes were incubated for 1 or 3h in PBG (PBS containing 0.5% BSA and 5mM glucose) or RPMI containing 10% fetal bovine serum (FBS); lipopolysaccharide (LPS), zymosan, peptidoglycan (PGN) and phorbol myristate acetate (PMA) were used as stimuli. ROS was assessed by conversion of the nonfluorescent dye dihydrorhodamine 123 to fluorescent rhodamine 123 by radical species released into the media. To identify optimal conditions for expression of tissue factor, mononuclear cells were incubated for 5h in RPMI containing different concentrations of heat-inactivated FBS (HI-FBS), and LPS, zymosan, PGN or PMA as stimuli. Expression of tissue factor was determined using a one-stage recalcification assay performed in an automated nephelometric coagulation analyzer. Neither LPS nor zymosan increased ROS production by granulocytes incubated in PBG media. In contrast, granulocytes incubated in RPMI had dose-dependent increases in ROS production in response to zymosan and PGN. ROS production was significantly increased by incubation with concentrations of LPS of 0.01microg/ml or greater, and by zymosan concentrations of 0.1microg/ml or greater. ROS production in response to incubation with PMA was significantly increased starting at 10(-7)M, and was significantly greater for cells incubated in RPMI than cells incubated in PBG. LPS-, zymosan- and PGN-stimulated procoagulant activity increased in a dose-dependent manner, whereas PMA-stimulated procoagulant activity peaked at 10(-7)M. Increasing concentrations of HI-FBS significantly increased LPS-, zymosan- and PGN-induced procoagulant activity of mononuclear cells. Results obtained in this study indicate production of ROS by canine granulocytes is optimal when these cells are incubated for 3h in RPMI with LPS (0.1microg/ml), zymosan (10 microg/ml), PGN (10 microg/ml), and PMA (10(-7)M). Furthermore, canine mononuclear cells express procoagulant activity in response to LPS, zymosan, PGN, and PMA, and responses to LPS, zymosan and PGN are enhanced by the addition of HI-FBS. These findings suggest that HI-FBS retains important serum proteins that facilitate interactions between each of these bacterial or yeast derived products and the mononuclear cells. Consequently, future studies regarding the regulation of procoagulant activity by canine mononuclear cells should be performed in the presence of HI-FBS. Both assays utilized in this study allow high throughput of samples, and therefore are appropriate choices for rapid screening of conditions and/or therapeutic interventions affecting the canine inflammatory system.     

In vitro activity of Peltophorum africanum Sond. (Fabaceae) extracts on the egg hatching and larval development of the parasitic nematode Trichostrongylus colubriformis

Trichostrongylus colubriformis is an important cause of parasitic gastroenteritis in ruminants, where it causes protracted diarrhoea, rapid loss of weight, loss of production and death. The in vitro efficacy of extracts of Peltophorum africanum was determined against this parasitic nematode. Eggs and larvae of T. colubriformis were incubated at 23 degrees C in the extracts of the leaf, bark and root of P. africanum at concentrations of 0.008-25 mg ml-1 for 2 and 5 days, respectively. Thiabendazole and water were used as positive and negative controls, respectively. Inhibition of egg hatching and larval development increased significantly (P<0.05) with increasing concentrations of the extracts. Concentrations of 0.2-1.0 mg ml-1 of the extracts of leaf, stem bark, and root bark of P. africanum completely inhibited the hatching of eggs and development of larvae. No eggs and larvae of T. colubriformis could be observed in wells incubated with all the three extracts at concentrations of 5 and 25 mg ml-1. The in vitro model results support the traditional use of P. africanum against nematode parasites. Further research is required to isolate and structurally identify the active anthelmintic compounds, and to improve methods of plant extraction of the effective anthelmintic components that will be readily adaptable for use by rural communities against helminthosis.