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Topic:Biochemistry
The study of biochemistry in horses encompasses the chemical processes and substances that occur within equine organisms. This field investigates the molecular interactions and pathways that are fundamental to horse physiology, including metabolism, enzyme activity, and genetic expression. Key areas of interest include the examination of metabolic disorders, nutrient absorption, and the biochemical basis of muscle function and energy production. Researchers utilize biochemical analysis to understand health and disease mechanisms in horses, contributing to the development of diagnostic tools and therapeutic strategies. This page gathers peer-reviewed studies and scholarly articles that explore various biochemical processes and their implications for equine health and performance.
Cholesterol-loaded-cyclodextrins and fertility potential of stallions spermatozoa. Irreversible damage occurs to spermatozoal membranes, during the phase transition, when spermatozoa are cooled from room temperature to 5 degrees C. Some of this damage can be ameliorated by adding cholesterol to the membrane, thereby altering membrane lipid composition. Adding cholesterol-loaded cyclodextrins (CLCs) to stallion spermatozoa prior to freezing, increases cell cryosurvival. However, the fertilizing potential of CLC-treated stallion spermatozoa is unknown. To address this, experiments were conducted which evaluated the ability of CLC-treated stallion spermatozoa to capacitate, acr...
Evidence for a novel vasospastic transmitter system, neuromedin U, in the equine digital circulation. The brain-gut peptide neuromedin U (NMU) is a ligand for the G-protein-coupled receptors, NMU1 and NMU2. In humans, an extended form of this peptide, NMU-25, and the structurally related peptide, neuromedin S (NMS), both produce potent vasoconstriction in isolated blood vessels. The aim of this study was to determine whether NMU fulfilled criteria for controlling vasoreactivity in the equine digital circulation. NMU receptors were characterised in the equine digital artery and vein based on the pharmacological criteria of specific, saturable and high affinity binding. Immunoreactive peptide wa...
Stability of equine IgG antivenoms obtained by caprylic acid precipitation: towards a liquid formulation stable at tropical room temperature. Liquid formulations of antivenom require a cold chain for their distribution and storage, especially in tropical countries characterized by high temperature and humidity (climatic zone IV). Since cold chain is often deficient in many regions, there is a need to develop novel formulations of liquid antivenoms of higher stability at room temperatures. The effect of addition of the polyols mannitol and sorbitol on the thermal stability of caprylic acid-fractionated equine whole IgG antivenoms was assessed in preparations having different concentrations of protein and phenol. Results evidenced tha...
Male gamblers have significantly greater salivary cortisol before and after betting on a horse race, than do female gamblers. Prevalence rates of gambling are influenced by gender. Among normative populations, hypothalamic-pituitary-adrenal (HPA) axis response to stress is affected by gender. However, pathological, compared to recreational, gamblers demonstrate perturbations in HPA activation in response to gambling stimuli. We examined whether there were gender differences in HPA response to gambling in a naturalistic setting among horse-race bettors and scratch-off lottery bettors. Salivary cortisol was collected from horse-race gamblers (n=32) and scratch-off lottery ticket players (n=39) before and after (0, 10, ...
Paraspecific neutralization of the venom of African species of cobra by an equine antiserum against Naja melanoleuca: a comparative study. Venoms of snakes belonging to the same Genera tend to share biochemical, toxinological and antigenic characteristics. Accordingly, paraspecific neutralization of venom lethality by experimental antisera and commercial antivenoms has been reported. We studied the spectrum of neutralization of lethality of an experimental monovalent equine antiserum against the strongly neurotoxic African forest cobra (Naja melanoleuca) when tested against venoms of most species of African Naja, both neuro and cytotoxic as described by some authors. We report a comparison of the median lethal doses (LD50) of the...
Equine herpesvirus type 1 (EHV-1) utilizes microtubules, dynein, and ROCK1 to productively infect cells. To initiate infection, equine herpesvirus type 1 (EHV-1) attaches to heparan sulfate on cell surfaces and then interacts with a putative glycoprotein D receptor(s). After attachment, virus entry occurs either by direct fusion of the virus envelope with the plasma membrane or via endocytosis followed by fusion between the virus envelope and an endosomal membrane. Upon fusion, de-enveloped virus particles are deposited into the cytoplasm and travel to the nucleus for viral replication. In this report, we examined the mechanism of EHV-1 intracellular trafficking and investigated the ability of EH...
CE provides evidence of the stereoselective hydroxylation of norketamine in equines. CE with multiple isomer sulfated-CD as selector was used for the simultaneous analysis of the stereoisomers of ketamine, norketamine, 5,6-dehydronorketamine and hydroxylated metabolites of norketamine in liquid/liquid extracts of (i) in vitro incubations with ketamine or norketamine and equine liver microsomes and (ii) plasma and urine of ponies receiving a target-controlled infusion of ketamine under isoflurane anesthesia. Hydroxynorketamine metabolites with the hydroxy group at the cyclohexanone ring could be shown to be formed stereoselectively both in vitro and in vivo. Due to the lack of ...
Characterization of bradykinin-induced endothelium-independent contraction in equine basilar artery. We investigated the effect of bradykinin (BK) on isolated equine basilar arterial rings with and without endothelium. BK induced concentration-dependent contraction of resting arterial rings and no relaxation when the rings were precontracted by prostaglandin F(2alpha). The maximal response and pD(2) value were 161.2 +/- 28.1% (to 60 mm KCl-induced contraction) and 8.24 +/- 0.25 respectively. The cumulative concentration-response curve for BK was not shifted to the right by des-Arg(9)-[Leu(8)]-BK (a B(1)-receptor antagonist), HOE140 (a B(2)-receptor antagonist) or NPC567 (another B(2)-receptor...
Serum homocysteine and oxidative stress evaluation during exercise in horse. The aim of the present work was to evaluate the influence of exercise on serum homocysteine and oxidative stress in Thoroughbreds during official races. For our study, ten Thoroughbred mares, 5 years old and clinically healthy, were used. The horses were trained to take part in an official 2100 meter race. Reactive oxygen species (dROMs), antioxidant barrier (Oxy-adsorbent), thiol antioxidant barrier (SHp) and homocysteine (sHcy) were investigated. Blood samples, collected from each horse at rest, immediately after the race, and 30 and 180 min after the end of the race, were collected by jugul...
Electrophysiological characterization of electrolyte and nutrient transport across the small intestine in horses. The aim of this study was to characterize the transport mechanisms of electrolytes and nutrients across the jejunum of nine healthy horses electrophysiologically. The stripped mucosa was mounted in Ussing chambers and tissue conductances (G(t)) and short circuit currents (I(sc)) were continuously monitored. After blocking the sodium and potassium channels with amiloride, tetraethylammonium chloride (TEA) and barium, chloride secretion was stimulated by carbachol and forskolin. Subsequently, chloride channels were inhibited by 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid, 5-nitro-2-(3-ph...
Influence of age on surfactant isolated from healthy horses maintained on pasture. Surfactant alterations are described in horses after exercise, anesthesia, and prolonged transport, in horses with recurrent airway obstruction, and in neonatal foals. The effect of horse age or bronchoalveolar lavage fluid (BALF) sample characteristics on surfactant is unknown. Objective: To evaluate surfactant phospholipid composition and function in healthy horses, and to investigate the influence of age and BALF sample characteristics on surfactant. Methods: Seventeen healthy horses 6-25 years of age maintained on pasture year-round. Methods: BALF was collected by standard procedures and w...
Effects of intravenous administration of pirfenidone on horses with experimentally induced endotoxemia. To characterize effects of IV administration of pirfenidone on clinical, biochemical, and hematologic variables and circulating tumor necrosis factor (TNF)-alpha concentrations in horses after infusion of a low dose of endotoxin. Methods: 18 healthy adult horses. Methods: Horses were randomly assigned to 3 groups (n = 6 horses/group) and administered an IV infusion of 30 ng of endotoxin/kg or saline (0.9% NaCl) solution during a 30-minute period. Lipopolysaccharide-pirfenidone horses received endotoxin followed by pirfenidone (loading dose of 11.6 mg/kg and then constant rate infusion [CRI] at...
Changes in intramuscular amino acid levels in submaximally exercised horses – a pilot study. The time-dependent changes in intramuscular amino acid (AA) levels caused by exercise and by feeding a protein/AA supplement were analysed in nine horses. Horses were submitted to a total of four standardized exercise tests (SETs). Amino acid concentrations were determined prior to, immediately after, 4 and 18 h after exercise. The experiment was subdivided into two consecutive periods of 3 weeks. In each period two SETs were performed. In the second period, horses were given a protein/AA supplement within 1 h after exercise. Significant changes in mean plasma AA levels similar to previous stu...
Expression and purification of active recombinant equine lysozyme in Escherichia coli. Equine lysozyme (EL) is a calcium (Ca)-binding lysozyme and is an intermediary link between non-Ca-binding C-type lysozyme and alpha-lactalbumin. The feature of lysozymes to assemble into the fibrils has recently gained considerable attention for the investigation of the functional properties of these proteins. To study the structural and functional properties of EL, a synthetic gene was cloned and EL was overexpressed in Escherichia coli as a fused protein. The His-tagged recombinant EL was accumulated as inclusion bodies. Up to 50 mg/l of the recombinant EL could be achieved after purificati...
Stability of common biochemistry analytes in equine blood stored at room temperature. Time delays between collection of blood samples and biochemical analysis of equine blood are unavoidably common in equine practice. The effect that delays may have on the accuracy of results of blood biochemical analyses is not well established. Objective: Delays in processing of blood of up to 72 h results in alterations in measured levels of common biochemical analytes that are of potential clinical relevance. Separation of serum prior to storage is protective against the effects of time delays. Methods: Samples of clotted blood, separated serum and oxalate fluoride plasma from 20 horses wer...
Lactobacillus equicursoris sp. nov., isolated from the faeces of a thoroughbred racehorse. We previously isolated five strains of putative lactobacilli from the faeces of a thoroughbred horse (a 4-year-old male). Of the five strains, four were identified as members of existing Lactobacillus species; however, sequence analysis of the 16S rRNA gene revealed that the fifth isolate, DI70(T), showed approximately 97 % identity (1325/1366 bp) with the type strain of Lactobacillus delbrueckii. Therefore, we considered the possibility that DI70(T) represents a novel species of the genus Lactobacillus. Cells of strain DI70(T) were Gram-stain-positive, catalase-negative, non-spore-forming, no...
Molecular characterization and expression pattern of the equine lactate dehydrogenase A and B genes. The species-specific properties of LDH isozymes are essentially determined by M (muscle) and H (heart) subunit proteins encoded by the LDHA and LDHB genes, respectively. In the present study, we molecularly characterized the full-length equine lactate dehydrogenase A (eLDHA) and B (eLDHB) cDNAs. The eLDHA cDNA consisted of a 999-bp open reading frame (ORF), while the eLDHB and newly acquired bat LDHB consisted of a 1002-bp ORF, which is 3 bp shorter than the LDHB ORF of other registered mammals. The alignment of amino acid sequences showed that eLDHA acquired positively charged His 88 and 226,...
Osmotic tolerance limits and membrane permeability characteristics of stallion spermatozoa treated with cholesterol. Stallion spermatozoa exhibit osmotic damage during the cryopreservation process. Recent studies have shown that the addition of cholesterol to spermatozoal membranes increases the cryosurvival of bull, ram and stallion spermatozoa, but the exact mechanism by which added cholesterol improves cryosurvival is not understood. The objectives of this study were to determine if adding cholesterol to stallion sperm membranes alters the osmotic tolerance limits and membrane permeability characteristics of the spermatozoa. In experiment one, stallion spermatozoa were treated with cholesterol-loaded cycl...
The fracture toughness of cancellous bone. The mechanical capacity and integrity of cancellous bone is crucial in osteoporosis, a condition which is set to become more prevalent with increasing lifespan and population sizes. The fracture toughness (FT) of cancellous bone has never been examined before and the conditions associated with the growth of a major crack through the lattice of cancellous bone, a cellular solid, may improve our understanding for structural integrity of this material. The aim of this study is to provide (i) basic data on cancellous bone FT and (ii) the experimental support for the hypothesis of Gibson, L.J., Ash...
Equine alpha S1-casein: characterization of alternative splicing isoforms and determination of phosphorylation levels. alpha(S1)-Casein was isolated from Haflinger mare's milk by hydrophobic interaction chromatography and displayed great micro-heterogeneity by 2-dimensional electrophoresis, probably because of a variable degree of phosphorylation and alternative splicing events. The aim of the present work was to investigate the complexity of the mare's alpha(S1)-casein. The different isoforms present in milk were submitted to a double treatment of dephosphorylation, first by using alkaline phosphatase and then acid phosphatase to achieve complete dephosphorylation. The apoforms were then analyzed by electrosp...
Effects of dermal dexamethasone application on ACTH and both basal and ACTH-stimulated cortisol concentration in normal horses. There are no data available regarding the systemic (adverse) effects which might be induced by topical/dermal glucocorticoids (GCs) application in the horse. Besides their widespread use for the treatment of a variety of peripheral inflammatory disorders such as atopic dermatitis, eczemas or arthritis in the horse, their surreptitious application has become a concern in doping cases in competition/performance horses. Assessing both basal and ACTH-stimulated plasma cortisol as well as basal ACTH concentrations following application of dexamethsone-containing dermal ointment is necessary to dete...
Effect of cryopreservation on nitric oxide production by stallion spermatozoa. The ability of stallion spermatozoa to produce nitric oxide (NO) before (fresh) and after freezing and thawing (FT) was evaluated by means of flow cytometry after loading the sperm suspension with the probe, 4,5-diaminofluorescenin diacetate. The presence of NO synthase (NOS) was investigated by Western blotting using anti-NOS1, anti-NOS3, or anti-universal NOS antibodies (Abs). While NO was detected both in fresh and FT sperm suspensions, its production increased after cryopreservation only when egg yolk was removed from the extender. Anti-NOS1 Ab intensively labeled a single band with an app...
Development of a metabonomic approach based on LC-ESI-HRMS measurements for profiling of metabolic changes induced by recombinant equine growth hormone in horse urine. Despite the worldwide existing regulation banning the use of the recombinant equine growth hormone (reGH) as growth promoter, it is suspected to be used in horseracing to improve performances. Various analytical methods previously developed to screen for its misuse have encountered some limitations in terms of detection timeframes, in particular during the first days following reGH administration. A novel strategy involving the characterization of global metabolomic fingerprints in urine samples of non-treated and reGH-treated horses by liquid chromatography-electrospray-high-resolution mass s...
Protein oligomerization induced by oleic acid at the solid-liquid interface–equine lysozyme cytotoxic complexes. Protein oligomeric complexes have emerged as a major target of current research because of their key role in aggregation processes in living systems and in vitro. Hydrophobic and charged surfaces may favour the self-assembly process by recruiting proteins and modifying their interactions. We found that equine lysozyme assembles into multimeric complexes with oleic acid (ELOA) at the solid-liquid interface within an ion-exchange chromatography column preconditioned with oleic acid. The properties of ELOA were characterized using NMR, spectroscopic methods and atomic force microscopy, and showed...
Freezing equine semen: the effect of combinations of semen extenders and glycerol on post-thaw motility. We evaluated combinations of two commercial semen extenders and three concentrations of glycerol to determine the combination that yielded the highest post-thaw sperm motility. Methods: A randomised 2 x 3 block design was used. Methods: Semen was collected from four stallions (6 collections per stallion). The sample was diluted with either a dried skim-milk glucose extender (EZ Mixin Original Formula) or a chemically defined, milk-free diluent (INRA 96), and each was used in combination with 2%, 3% or 4% glycerol in standard commercial freezing medium. Sperm motility was assessed by microscopy...
Stereoselective pharmacokinetics of ketamine and norketamine after constant rate infusion of a subanesthetic dose of racemic ketamine or S-ketamine in Shetland ponies. To evaluate pharmacokinetics of ketamine and norketamine enantiomers after constant rate infusion (CRI) of a subanesthetic dose of racemic ketamine or S-ketamine in ponies. Methods: Five 6-year-old Shetland pony geldings that weighed between 101 and 152 kg. Methods: In a crossover study, each pony received a CRI of racemic ketamine (loading dose, 0.6 mg/kg; CRI, 0.02 mg/kg/min) and S-ketamine (loading dose, 0.3 mg/kg; CRI, 0.01 mg/kg/min), with a 1-month interval between treatments. Arterial blood samples were collected before and at 5, 15, 30, 45, and 60 minutes during drug administration and...
Effects of acute exercise and long-term exercise on total Na+,K+ -ATPase content and Na+,K+ -ATPase isoform expression profile in equine muscle. To investigate the effects of acute exercise and long-term training on Na(+),K(+)-ATPase content, mRNA isoforms, and protein concentration in equine muscle. Methods: 6 Standardbreds. Methods: Horses performed a bout of exercise on a treadmill before and after 18 weeks of combined interval and endurance training. Muscle biopsy specimens were obtained from vastus lateralis muscle (VLM) and pectoralis descendens muscle (PDM) before and after exercise. The Na(+),K(+)-ATPase content, mRNA isoforms, and protein concentrations were determined by use of [(3)H]ouabain binding, real-time PCR assay, and ...
Evaluation of pain and inflammation associated with hot iron branding and microchip transponder injection in horses. To compare effects of hot iron branding and microchip transponder injection regarding aversive behavioral reactions indicative of pain and inflammation in horses. Methods: 7 adult horses. Methods: In a randomized controlled clinical crossover study, behavioral reactions to hot iron branding and microchip transponder injection were scored by 4 observers. Local and systemic inflammation including allodynia were assessed and compared by use of physiologic and biochemical responses obtained repeatedly for the 168-hour study period. Serum cortisol concentration was measured repeatedly throughout th...
The effect of focused extracorporeal shock wave therapy on collagen matrix and gene expression in normal tendons and ligaments. Extracorporeal shock wave therapy (ESWT) is frequently used in equine practice, but little is known about its biological action. Objective: To study the effects of ESWT on matrix structure and gene expression levels in normal, physiologically loaded tendinous structures in ponies. Methods: Six Shetland ponies, free of lameness and with ultrasonographically normal flexor and extensor tendons and suspensory ligaments (SL), were used. ESWT was applied at the origin of the suspensory ligament and the mid-metacarpal region of the superficial digital flexor tendon (SDFT) 6 weeks prior to sample taki...
Modern techniques for the determination of anabolic-androgenic steroid doping in the horse. Control of the use of performance-affecting substances in the horse is critical to the integrity of a wide range of equine sports, with major implications for both animal welfare and revenue streams. One class of medications enjoying particular public notoriety is the anabolic-androgenic steroid group, as highlighted by the recent 'Big Brown' affair and Congressional inquiries into the use of steroids in professional sports, including horse racing, in the USA. This review examines the latest developments pertaining to the analytical detection of these substances in equine biological samples an...
