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Topic:Laboratory Methods
Laboratory methods in equine research encompass a variety of techniques and procedures used to analyze biological samples from horses to study health, disease, genetics, and physiology. These methods include hematological analyses, biochemical assays, molecular biology techniques, and microbiological cultures. Commonly utilized laboratory techniques involve blood tests for complete blood count (CBC) and serum chemistry, polymerase chain reaction (PCR) for genetic and infectious disease studies, and enzyme-linked immunosorbent assays (ELISA) for detecting specific proteins or antibodies. These methods provide valuable data that contribute to understanding equine health and disease mechanisms. This page compiles peer-reviewed research studies and scholarly articles that explore the application, development, and outcomes of laboratory methods in the context of equine research.
Determination of triamcinolone acetonide in equine serum and urine by liquid chromatography-atmospheric pressure ionization mass spectrometry. Urine and serum samples collected from four standard-bred mares after 30-mg intraarticular administrations of triamcinolone acetonide were analyzed using combined high-performance liquid chromatography-atmospheric pressure ionization mass spectrometry. Maximum triamcinolone acetonide concentrations of 32.3, 14.8, 24.3, and 29.4 ng/mL in the urine and 2.7, 1.9, 2.3, and 2.5 ng/mL in the serum samples were observed. The peak concentrations of the drug were detected approximately 22 h (urine) and 12 h (serum) after administration. The drug elimination profiles for both urine and serum are present...
Detection of clenbuterol (Ventipulmin) in the horse. An enzyme linked immunosorbent assay (ELISA) was developed to detect the beta 2-agonist clenbuterol in equine blood and urine. The antiserum was raised in rabbits, employing clenbuterol-diazo-BSA as antigen. Clenbuterol-diazo-horseradish peroxidase served as enzyme conjugate. The concentration of clenbuterol to decrease tracer binding by 50% (IC50 value) was found to be 27.50 +/- 4.20 pg/well (1.37 ng/ml). The antibody cross-reacted with salbutamol (30%), terbutaline (14%) and cimaterol (1%). Horse serum was used directly to screen for clenbuterol, while urine was employed diluted. Positive sc...
Tropane alkaloids and toxicity of Convolvulus arvensis. Horses in a few, localized northern Colorado pastures exhibited weight loss and colic. At post mortem, intestinal fibrosis and vascular sclerosis of the small intestine was identified. The pastures where the affected horses grazed were overrun by field bindweed (Convolvulus arvensis). Bindweed from the pasture was found to contain the tropane alkaloids tropine, pseudotropine, and tropinone and the pyrrolidine alkaloids cuscohygrine and hygrine. Laboratory mice readily ate C. arvensis and exhibited a variety of abnormal clinical signs depending on the amount eaten. Similar alkaloids have been f...
Application of the polymerase chain reaction to the detection of African horse sickness viruses. The development of a coupled reverse transcriptase-polymerase chain reaction assay (RT-PCR) is described for the detection of African horse sickness virus (AHSV) double-stranded RNA. Genome segments 7 and 10 were chosen as target templates for primers selected for use in the RT-PCR. Using these AHSV-specific primers all 9 serotypes were detectable. The sensitivity and specificity of the RT-PCR results were compared to those obtained by competition ELISA.
Regulatory function of the equine herpesvirus 1 ICP27 gene product. The UL3 protein of equine herpesvirus 1 (EHV-1) KyA strain is a homolog of the ICP27 alpha regulatory protein of herpes simplex virus type 1 (HSV-1) and the ORF 4 protein of varicella-zoster virus. To characterize the regulatory function of the UL3 gene product, a UL3 gene expression vector (pSVUL3) and a vector expressing a truncated version of the UL3 gene (pSVUL3P) were generated. These effector plasmids, in combination with an EHV-1 immediate-early (IE) gene expression vector (pSVIE) and chimeric EHV-1 promoter-chloramphenicol acetyltransferase (CAT) reporter constructs, were used in trans...
Development of an ELISA using a universal method of enzyme-labelling drug-specific antibodies. Part I: Detection of dexamethasone in equine urine. The development, validation, and application of an ELISA for dexamethasone in equine urine is described. The drug-protein conjugate was immobilised in microtitre plate wells and antiserum raised against the same drug-protein conjugate was allowed to compete with sample or standard drug and the immobilised drug-protein conjugate. The proportion of antiserum binding to the immobilised drug-protein conjugate was detected using a biotinylated protein G/extravidin-alkaline phosphatase complex in situ and measurement of the substrate product. The method was used to detect the presence of drug-derive...
A novel Ca(2+)-dependent step in exocytosis subsequent to vesicle fusion. Exocytosis begins with formation of a small fusion pore which then expands allowing rapid release of granular contents. We studied the influence of cytoplasmic free Ca2+ ([Ca2+]i) on the conductance of the initial pore and on the dynamics of subsequent expansion in horse eosinophils using the patch clamp technique. The mean initial conductance is approximately 200 pS independent of [Ca2+]i. This value is close to that previously found in beige mouse mast cells. The pore subsequently expands by 18 nS/s at [Ca2+]i < 10 nM, by 40 nS/s at [Ca2+]i = 1.5 microM and by 90 nS/s at [Ca2+]i = 10 micr...
Substitutions of isoleucine residues at the adenine binding site activate horse liver alcohol dehydrogenase. The contributions of isoleucine residues 224 and 269 of horse liver alcohol dehydrogenase to binding of the adenine moiety of NAD and to catalysis were studied by replacing Ile-224 with glycine (I224G) and Ile-269 with serine (I269S). The kinetic mechanisms of wild-type and both mutated liver enzymes were ordered. Affinities for several adenosine derivatives were decreased 5-50-fold by both substitutions. The I269S mutation differentially destabilized binding of the complete coenzyme, as affinities for NAD+ and NADH were decreased about 60-fold with the I224G enzyme and 350-fold for the I269S ...
The disposition of gentamicin in equine plasma, synovial fluid and lymph. Plasma (P), synovial fluid (SF) and lymph (L) concentrations of gentamicin were studied in two trials. A lymph vessel in the hindlimb was cannulated. The day after surgery (trial A), P and L samples were collected for 12 h after intravenous injection of gentamicin sulphate at 2.2 mg/kg dose rate. Approximately 48 h after surgery (trial B), the fetlock joint of the cannulated hindlimb was catheterized and P, SF and L samples collected for 12 h after a similar intravenous injection. The kinetic parameters were similar to those in other reports and did not differ between trials (P < 0.05). The P,...
Responsiveness of equine basilar artery to transmural nerve stimulation differs from that of porcine and bovine basilar arteries in vitro. Transmural nerve stimulation (TNS) induced relaxations in porcine and bovine basilar arteries which were abolished by tetrodotoxin (TTX) and by L-nitro-arginine (LNAG). However, TNS induced contractions in equine basilar artery which were abolished by TTX and by guanethidine, but not by LNAG. These results suggest that the TNS-induced contractions of equine basilar arteries may be mediated by norepinephrine release.
Permeation of small molecules into the cavity of ferritin as revealed by proton nuclear magnetic resonance relaxation. The NMR relaxation technique was used to investigate the permeation of molecules into the cavity of ferritin. Spin-lattice relaxation times in the rotating frame of various probe molecules were measured for solutions of recombinant horse L-apoferritin without iron and horse spleen apoferritin with very small amounts of ferric ions. The results show that molecules larger than the size of the ferritin channels can pass through the channels into the ferritin interior, and that the maximum size of molecules for the permeation is smaller than maltotriose.
Proteoglycan metabolism of equine articular cartilage and its modulation by insulin-like growth factors. The effect of human recombinant insulin-like growth factor 1 (rhIGF-1) on proteoglycan (PG) metabolism of full thickness equine articular cartilage explants was investigated. PG synthesis was stimulated at all ages, but higher concentrations of rhIGF-1 were required for maximal stimulation of adult cartilage. There were no changes in the hydrodynamic size, electrophoretic heterogeneity or composition of proteoglycans isolated from rhIGF-1-stimulated cartilage. rhIGF-1 reduced the rate of turnover of both newly synthesized and endogenous proteoglycans in all ages of cartilage investigated. The ...
Detection of Salmonella enteritidis in equine feces using the polymerase chain reaction and genus-specific oligonucleotide primers. Salmonella was identified in feces from horses, using the polymerase chain reaction (PCR) and genus-specific oligonucleotide primers. Feces from healthy horses were determined to be culture negative and PCR negative for Salmonella. Fecal samples were inoculated with known numbers of colony-forming units (CFU) of S. enteritidis. The fecal samples were enriched overnight in tetrathionate broth, and then DNA was extracted and amplified by PCR using genus-specific primers. Sensitivity of the assay extended to 10 degrees CFU Salmonella enteritidis/g feces; sensitivity of microbiologic culture with ...
Taxon-specific probes for the cellulolytic genus Fibrobacter reveal abundant and novel equine-associated populations. A total of six 16S rRNA targeted oligonucleotide probes were used to quantify Fibrobacter abundance and diversity in the gastrointestinal contents of a pony. Approximately 12% of the total 16S rRNA extracted from cecal contents hybridized with a Fibrobacter genus-specific probe and a Fibrobacter succinogenes species-specific probe. However, no significant hybridization was observed with a probe for the species. Fibrobacter intestinalis or with three probes for F. succinogenes subspecies. This suggested the presence of a previously undescribed population of F. succinogenes-like organisms. Novel...
Delineating minimal protein domains and promoter elements for transcriptional activation by lentivirus Tat proteins. Lentivirus Tat proteins comprise a novel class of RNA-binding transcriptional activators that are essential for viral replication. In this study, we performed a series of protein fusion experiments to delineate the minimal protein domains and promoter elements required for Tat action. We show that a 15-amino-acid region of equine infectious anemia virus (EIAV) Tat protein, when fused to the GAL4 or LexA DNA binding domain, can activate transcription in appropriate promoter contexts. In the natural human immunodeficiency virus type 1 long terminal repeat, activation by Tat is dependent on multi...
Differences in a ribosomal DNA sequence of Strongylus species allows identification of single eggs. In the current study, molecular techniques were evaluated for the species identification of individual strongyle eggs. Adult worms of Strongylus edentatus, S. equinus and S. vulgaris were collected at necropsy from horses from Australia and the U.S.A. Genomic DNA was isolated and a ribosomal transcribed spacer (ITS-2) amplified and sequenced using polymerase chain reaction (PCR) techniques. The length of the ITS-2 sequence of S. edentatus, S. equinus and S. vulgaris ranged between 217 and 235 nucleotides. Extensive sequence analysis demonstrated a low degree (0-0.9%) of intraspecific variation...
Development of PCR assays to detect genetic variation amongst equine herpesvirus-1 isolates as an aid to epidemiological investigation. A search for variable restriction sites has been carried out for equine herpesvirus-1 (EHV-1) in an attempt to develop markers which can be used to group epidemiologically related viruses into groups, and to learn more about the dynamics of EHV-1 disease. Crude viral DNA extracts of EHV-1, prepared by Hirt extraction, were digested with AluI, HaeIII, or RsaI, and Southern blotted following electrophoresis. DNA fingerprints, produced by probing the Southern blots with the EHV-1 EcoR1-I fragment, separated 56 isolates into 16 groups. The variable sites within the EcoR1-I fragment were mapped app...
Catecholamine affects acetylcholine release in trachea: alpha 2-mediated inhibition and beta 2-mediated augmentation. We investigated the effects of catecholamines on acetylcholine (ACh) release from equine airway parasympathetic nerves. Trachealis strips were suspended in 2-ml tissue baths with Krebs-Henseleit solution containing atropine (10(-7) M), neostigmine (10(-6) M), and guanethidine (10(-5) M). Electrical field stimulation (20 V, 0.5 ms, 0.5 Hz, for 15 min) was applied, and ACh was measured by high-performance liquid chromatography with electrochemical detection. Epinephrine (Epi) and norepinephrine (NE) inhibited ACh release in a concentration-dependent manner. Inhibition was attenuated by the alpha...
Enhanced sensitivity to neutralizing antibodies in a variant of equine infectious anemia virus is linked to amino acid substitutions in the surface unit envelope glycoprotein. Serial passage of the prototype (PR) cell-adapted Wyoming strain of equine infectious anemia virus (EIAV) in fetal donkey dermal (FDD) rather than fetal horse (designated fetal equine kidney [FEK]) cell cultures resulted in the generation of a variant virus strain which produced accelerated cytopathic effects in FDD cells and was 100- to 1,000-fold more sensitive to neutralizing antibodies than its parent. This neutralization-sensitive variant was designated the FDD strain. Although there were differences in glycosylation between the PR and FDD strains, passage of the FDD virus in FEK cells di...
Regulation of granule size in human and horse eosinophils by number of fusion events among unit granules. 1. We have investigated the granule size distributions in human and horse eosinophils by time-resolved patch-clamp capacitance measurements. 2. During exocytosis of single granules the electrical capacitance of the plasma membrane increases in discrete steps. The steps in horse cells are about six times larger than those in human cells in accordance with the difference in granule size. 3. In both species a multimodal capacitance step size distribution is observed with a first peak at 6-7 fF corresponding to granules with a diameter of about 450-500 nm and a surface area of about 0.7 microns2, ...
The proximal ligand variant His93Tyr of horse heart myoglobin. The spectroscopic and structural properties of the His93Tyr variant of horse heart myoglobin have been studied to assess the effects of replacing the proximal His residue of this protein with a tyrosyl residue as occurs in catalases from various sources. The variant in the ferric form exhibits electronic spectra that are independent of pH between pH 7 and 10, and it exhibits changes in absorption maxima and intensity that are consistent with a five-coordinate heme iron center at the active site. The EPR spectrum of the variant is that of a high-spin, rhombic system similar to that reported for...
Characterisation of a membrane receptor on ruminants and equine platelets and peripheral blood leukocytes similar to the human integrin receptor glycoprotein IIb/IIIa (CD41/61). This paper describes two anti-glycoprotein IIb/IIIa or CD41/61 murine monoclonal antibodies (Co.35E4 and Co.2oA1). The cellular distribution and apparent molecular weight of the antigen detected by these antibodies is consistent with their reaction with ruminant and equine glycoprotein IIb/IIIa. Biochemical analysis of the equine molecule using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed bands of 24, 100 and 110 kDa under reducing conditions and 115 and 80 kDa under nonreducing conditions. Biochemical analysis of ruminant antigen revealed that the 24 kDa band...
Electrostatics of hemoglobins from measurements of the electric dichroism and computer simulations. Hemoglobins from normal human cells, from sickle cells, and from horse were investigated by electrooptical methods in their oxy and deoxy forms. The reduced linear dichroism measured as a function of the electric field strength demonstrates the existence of permanent dipole moments in the range of 250-400 Debye units. The reduced limiting dichroism is relatively small (< or = 0.1); it is negative for hemoglobin from sickle cells and positive for the hemoglobins from normal human cells and from horse. The dichroism decay time constants are in the range from about 55 to 90 ns. Calculations of th...
Production of monoclonal antibodies in horses. Monoclonal antibodies (MAbs) have been successfully used to evaluate immune responses in horses, and to target important antigens of equine infectious agents to which protective immune responses may be directed (1–5). Most of these studies are performed with murine MAb produced by fusing spleen cells from immunized mice with an appropriate myeloma cell line, as described in Chapter 3. However, there are experimental questions for which murine MAb are not adequate. These include:
1.Definition of microbial epitopes recognized by the infected host;
2.Identification of immunodominant epito...
Molecular analysis of an XY mare with gonadal dysgenesis. In this study, cytogenetic analysis of an infertile mare revealed a 64, XY karyotype. The XY sex-reversed animal had a female phenotype with gonadal dysgenesis. Using Southern blot analysis, we tested for the presence of two Y-specific genes SRY and ZFY by using DNA isolated from peripheral blood leukocytes. The results showed that at least the DNA-binding domain of the SRY gene was deleted from the Y chromosome of the XY mare but that the ZFY gene was present on this chromosome.
Isolation and identification of two potent neurotoxins, aspartic acid and glutamic acid, from yellow star thistle (Centaurea solstitialis). Horses grazing for prolonged periods on yellow star thistle (YST), a plant which grows wild in western parts of the United States, develop an extrapyramidal disorder known as nigropallidal encephalomalacia (NPE). Attempts have been made to identify, isolate, and characterize the toxins responsible for the disease in animals. Using the organotypic tissue culture system on mouse cortical explants as a specific assay method for neurotoxicological evaluation, it has been possible to isolate and characterize two potent neuroexcitotoxic compounds, aspartic and glutamic acids, the former being the ma...
