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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.
Comparative pharmacokinetics of two intravenous administration regimens of tiludronate in healthy adult horses and effects on the bone resorption marker CTX-1. Bioavailability and pharmacological effects of tiludronate were compared when administered as an intravenous (i.v.) bolus at a dosage of 0.1 mg/kg body weight (b.w.) once daily for 10 consecutive days (group 1, n = 6) and as a single constant rate infusion (CRI) at a total dose of 1 mg/kg b.w. (group 2, n = 6) in healthy adult horses. Tiludronate and carboxy-terminal cross-linking telopeptide of type I collagen (CTX-1) were measured in plasma and urine. There was no statistically significant difference in area under the curve (AUC) and clearance (Cl) between the two groups. Bioavailability of ...
Specific electrochemical iodination of horse heart myoglobin at tyrosine 103 as determined by Fourier transform ion cyclotron resonance mass spectrometry. The iodination of proteins remains a useful tool in biochemistry for radiolabelling. However, chemical or enzymatic iodination is difficult to control and can give deleterious polyiodination. Previously, we have shown that electrooxidation with nitrite is a rapid method for the selective nitration of tyrosine residues in proteins. In principle, it should be possible to substitute a number of electrooxidisable anions into the tyrosine phenol ring. Electrochemical iodination is more difficult to control than nitration because the rapid anodic oxidation of I(-) leads to persistent formation of th...
Application of primed in situ DNA synthesis (PRINS) with telomere human commercial kit in molecular cytogenetics of Equus caballus and Sus scrofa scrofa. Recently, molecular techniques have become an indispensable tools for cytogenetic research. Especially, development of in situ techniques made possible detection at the chromosomal level, genes as well as repetitive sequences like telomeres or the DNA component of telomeres. One of these methods is primed in situ DNA synthesis (PRINS) using an oligonucleotide primer complementary to the specific DNA sequence. In this report we described application of PRINS technique with telomere human commercial kit to telomere sequences identification. This commercial kit may be use to visualization of inte...
The presence of the mu-opioid receptor in the isthmus of mare oviduct. The presence of the mu-opioid receptor and the type of glycosylation in the third extra-cellular loop of this receptor was investigated in the isthmus of mare oviduct during oestrus by means of immunoblotting and immunohistochemistry combined with enzymatic (N-glycosidase F and O-glycosidase) and chemical (beta-elimination) treatments. Immunoblotting analysis showed that the mu-opioid receptor consists of two peptides with molecular weights of around 65 and 50 kDa. After N-deglycosylation with N-glycosidase F an additional immunoreactive peptide was observed at around 30 KDa. The cleavage of O...
Determination of IGF-I in horse plasma by LC electrospray ionisation mass spectrometry. The insulin-like-growth factor (IGF-I) peptide is considered to be the main indirect marker for growth hormone administration (GH) in a horse. Further to a previous investigation on measurement of IGF-I in plasma samples by mass spectrometry, this study focuses on quantitative and qualitative analysis of intact IGF-I in horse plasma. First, protein-transposing software has been developed for IGF-I to facilitate its quantification by HPLC-electrospray-ion-trap mass spectrometry. Second, product-ion scan experiments on IGF-I have been conducted on standard samples, non-fortified equine plasma sa...
Serum concentrations of lidocaine and its metabolites after prolonged infusion in healthy horses. Continuous-rate infusions (CRI) of lidocaine are often used for prolonged duration but, to date, only limited time/concentration relationships administered as a short term (24 h) CRI have been reported. Objective: To determine the time/concentration profile of lidocaine and its active metabolites glycinexylidide (GX) and monoethylglycinexylidide (MEGX) during a 96 h lidocaine infusion. Methods: Lidocaine was administered to 8 mature healthy horses as a continuous rate infusion (0.05 mg/kg bwt/min) for 96 h. Blood concentrations of lidocaine, GX and MEGX were determined using high performance l...
Helix-rich transient and equilibrium intermediates of equine beta-lactoglobulin in alkaline buffer. Acidic buffer conditions are known to stabilize helix-rich states of even those proteins with a predominantly beta-sheet native secondary structure. Here we investigated whether such states also exist under alkaline buffer conditions. The guanidine hydrochloride (GuHCl)-induced unfolding transition and kinetic refolding of equine beta-lactoglobulin (ELG) by GuHCl-jump were investigated at pH 8.7 by far-ultraviolet circular dichroism. We found that an equilibrium intermediate appeared in 45% ethylene glycol (EGOH) buffer with 1.5 M GuHCl. The intermediate is rich in non-native alpha-helix, whic...
Contractile effects of 5-hydroxytryptamine (5-HT) in the equine jejunum circular muscle: functional and immunohistochemical identification of a 5-HT1A-like receptor. Prokinetic drugs used to treat gastrointestinal ileus in man have equivocal results in horses. In man, prokinetic drugs have 5-hydroxytryptamine4(5-HT4) receptors as their target, but little is known about the 5-HT-receptor subtypes in the equine small intestine. Objective: Functional and immunohistochemical identification of the serotonin receptor subtype(s) responsible for the 5-HT induced contractile response in the equine circular jejunum. Methods: Isometric organ-bath recordings were carried out to assess spontaneous and drug-evoked contractile activity of equine circular jejunum. Histolo...
Free radicals and antioxidants in inflammatory processes and ischemia-reperfusion injury. This article discusses the current understanding of the role of free radicals and antioxidants in inflammatory processes and in ischemia reperfusion injury. It begins by describing the manifestations of acute inflammation and outlining the cellular events that occur during inflammation. It then describes the biochemical mediators of inflammation with special attention to nitric oxide. It details the process of hypoxia reperfusion injury, the enzymes involved, its treatment, and studies involving specific hypoxia reperfusion injuries in various animal species.
Unusual observations during steroid analysis. In September 2005, our laboratory detected the presence of 4-androstene-3,17-dione and androsterone in a standard steroid screen of a post-race gelding urine sample received from an overseas authority. All other urine samples from the same batch tested negative. Subsequent gas chromatography/mass spectrometry (GC/MS) confirmatory analyses, however, repeatedly failed to detect any amount of 4-androstene-3,17-dione and androsterone in the suspicious sample. On the other hand, identical results were obtained when the initial GC/MS screening method was repeated on the suspicious sample as well as ...
Characterization of equine arteritis virus particles and demonstration of their hemolytic activity. Equine arteritis virus (EAV), a member of the newly established family Arteriviridae, is a small, positive-stranded RNA virus. It carries two protein complexes in its envelope, gp5/M and the recently described gp2b/gp3/gp4 complex. We report here on several basic features of EAV replication in cell culture and on the protein composition of virus particles. We have also characterized gp2b, gp3, and gp4 expressed using a baculovirus system in insect cells. Finally, we provide evidence that EAV possess hemagglutinating and hemolytic activity. The hemolysis assay might be useful for determining wh...
Hypothalamic-pituitary-adrenal axis assessment in healthy term neonatal foals utilizing a paired low dose/high dose ACTH stimulation test. Hypothalamic-pituitary-adrenal (HPA) axis function is dynamic in the neonatal foal. The paired low dose/high dose cosyntropin (ACTH) stimulation test allows comprehensive HPA axis assessment, but has not been evaluated in neonatal foals. Objective: Foal age will significantly affect cortisol responses to a paired 10 and 100 microg dose cosyntropin stimulation test in healthy neonatal foals. Methods: Twenty healthy neonatal foals. Methods: HPA axis function was assessed in 12 foals at birth and at 12-24, 36-48 hours, and 5-7 days of age. At each age, basal cortisol and ACTH concentrations were ...
Study on membrane fluidity and erythrocyte aggregation in equine, bovine and human species. The aim of the present paper is to analyze whether membrane fluidity can be predicted from its lipid composition and to assay the possible relationship between such variable and the aggregating properties of erythrocytes from equine, bovine and human species due to the widely acknowledged differences in their tendency to form aggregates. The main difference between phospholipids from plasma membrane in these species lies in the concentration levels of sphyngomyelin (SM) and phosphatidilcoline (PC); more precisely, in the external hemilayer of the lipid bilayer. Membrane fluidity was estimated ...
Physicochemical properties of meat of Italian Heavy Draft horses slaughtered at the age of eleven months. To investigate rheological and chemical characteristics of the meat from Italian Heavy Draft horse, 24 foals (12 males and 12 females) were weaned at 6 mo, reared and fed in the same way, and slaughtered at 11 mo of age. The results obtained showed that there were no significant differences between the sexes but that the muscle type is a significant variation source. The rectus femoris muscle was lighter, and the biceps femoris had a lower a* index than longissimus dorsii, rectus femoris, and semimembranosus muscle. The most tender muscle was the semitendinosus, and the toughest even after coo...
A defined medium supports changes consistent with capacitation in stallion sperm, as evidenced by increases in protein tyrosine phosphorylation and high rates of acrosomal exocytosis. Efficient in vitro capacitation of stallion sperm has not yet been achieved, as suggested by low sperm penetration rates reported in in vitro fertilization (IVF) studies. Our objectives were to evaluate defined incubation conditions that would support changes consistent with capacitation in stallion sperm. Protein tyrosine phosphorylation events and the ability of sperm to undergo acrosomal exocytosis under various incubation conditions were used as end points for capacitation. Sperm incubated 4-6h in modified Whitten's (MW) with the addition of 25 mM NaHCO3 and 7 mg/mL BSA (capacitating mediu...
Expression and localization of the mu-opioid receptor (MOR) in the equine cumulus-oocyte complex and its involvement in the seasonal regulation of oocyte meiotic competence. The micro-opioid receptor (MOR) was identified in equine oocytes, cumulus and granulosa cells. By RT-PCR, a 441bp fragment was observed. By immunoblotting, a 65 kDa band was detected in samples of winter anestrous whereas in cells recovered in breeding season, two bands, 65 and 50 kDa, were found. The 65 kDa band was significantly more intense in winter anestrous specimens. In samples recovered in the breeding season, this band significantly decreased with the raise of follicle size and was heavier in compact oocytes and cumulus cells. The protein was localized on the oolemma and within the cy...
Circulating fatty acid profiles in response to three levels of dietary omega-3 fatty acid supplementation in horses. Fatty acids of the n-3 type confer health benefits to humans and other species. Their importance to equine physiology could include improved exercise tolerance, decreased inflammation, and improved reproductive function. The circulating fatty acid profile and the acquisition and washout of fatty acids in response to n-3 supplementation were determined for horses in the current study. A fatty acid supplement high in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid was fed to deliver EPA plus DHA at 0 (control), 10, 20, or 40 g/d to 16 mares (n = 4/group) for 28 d. Plasma was collected at -...
Probing the role of water in lamellar bone by dehydration in the environmental scanning electron microscope. Water, collagen and mineral are the three major components of bone. The structural organization of water and its functions within the bone were investigated using the environmental scanning electron microscope and by analyzing dimensional changes that occur when fresh equine osteonal bone is dehydrated and then rehydrated. These changes are attributed mainly to loss of bulk and weakly bound water. In longitudinal sections a contraction of 1.2% was observed perpendicular to the lamellae, whereas no contraction occurred parallel to the lamellae. In transverse sections a contraction of 1.4% was o...
Insulins in equine urine: qualitative analysis by immunoaffinity purification and liquid chromatography/tandem mass spectrometry for doping control purposes in horse-racing. Insulin is a peptide hormone consisting of two peptide chains (A- and B-chain) that are cross-linked by two disulfide bonds. To obtain improved pharmacokinetic onset of action profiles of insulin treatment in diabetic patients, recombinant long-, intermediate-, and rapid-acting insulin analogs are produced, in which the C-terminal end of the B-chain plays an especially important role.A review of the veterinary literature reveals the low prevalence of equine type I diabetes mellitus, which indicates that the therapeutic use of insulin in racing horses is unlikely. Although there is no unequivoc...
Role of intracellular kinases in the regulation of equine eosinophil migration and actin polymerization. Inappropriately activated eosinophils can contribute to disease pathogenesis and intracellular signalling pathways that regulate functional responses may represent a therapeutic target. Little is known about intracellular signalling in equine eosinophils and this study examined the role of phospholipase C (PLC) and a range of protein kinases on responses to histamine and CCL11. Histamine (10(-4) M) or CCL11 (5.6 x 10(-9) M)-induced actin polymerization, migration and superoxide production by eosinophils from healthy horses were compared in the presence and absence of selective kinase inhibitor...
Characterization of agonist-induced endothelium-dependent vasodilatory responses in the vascular bed of the equine digit. The role of endothelium-derived relaxing factors was studied in the regulation of vascular responses in the Krebs perfused equine isolated digit. Perfusion pressure was recorded in response to bolus doses of 5-hydroxytryptamine (6 nmol) alone or co-administered with carbachol (CCh; 0.2 micromol), bradykinin (BK; 0.2 nmol), substance P (SP; 0.2 nmol) or sodium nitroprusside (SNP; 0.2 micromol). N(omega)-Nitro-L-Arginine methyl ester hydrochloride (L-NAME; 300 microm) caused partial but significant inhibition of CCh-induced vasodilatory response, whereas BK and SP-induced responses were resistan...
Effects of dexamethasone administration on insulin resistance and components of insulin signaling and glucose metabolism in equine skeletal muscle. To determine the effects of dexamethasone treatment on selected components of insulin signaling and glucose metabolism in skeletal muscle obtained from horses before and after administration of a euglycemic-hyperinsulinemic clamp (EHC). Methods: 6 adult Standardbreds. Methods: In a balanced crossover study, horses received either dexamethasone (0.08 mg/kg, IV, q 48 h) or an equivalent volume of saline (0.9% NaCl) solution, IV, for 21 days. A 2-hour EHC was administered for measurement of insulin sensitivity 1 day after treatment. Muscle biopsy specimens obtained before and after the EHC were a...
Effects of long-term oral administration of levothyroxine sodium on glucose dynamics in healthy adult horses. To determine the effects of long-term oral administration of levothyroxine sodium (L-T(4)) on glucose dynamics in adult euthyroid horses. Methods: 6 healthy adult mares. Methods: Horses received L-T(4) (48 mg/d) orally for 48 weeks. Frequently sampled IV glucose tolerance test procedures were performed on 3 occasions (24-hour intervals) before and at 16, 32, and 48 weeks during the treatment period. Data were assessed via minimal model analysis. The repeatability of measurements was evaluated. Results: During treatment, body weight decreased significantly from the pretreatment value; mean +/- ...
In vitro cell compatibility and antibacterial activity of microencapsulated doxycycline designed for improved localized therapy of septic arthritis. For the treatment of septic arthritis in large animals, the local application of antibiotics as a slow release system may be an appropriate means to reach high local bioactivity and low systemic side effects and drug residues. In this study, doxycycline microspheres were developed and tested in vitro for their drug-release properties, suitability for intra-articular application and antimicrobial activity. Methods: The development of a slow release system was achieved by microencapsulation of the drug into poly(lactide-co-glycolide) microspheres by a novel ultrasonic atomization method. Drug el...
Early exercise advances the maturation of glycosaminoglycans and collagen in the extracellular matrix of articular cartilage in the horse. Training at a very young age may influence the characteristics of the collagen network of articular cartilage extracellular matrix (ECM) in horses. Objective: To investigate whether increasing workload of foals results in significant changes in the biochemical composition of articular cartilage ECM. Methods: Thoroughbred foals (n = 33) were divided into 2 different exercise groups from age 10 days-18 months. One group (PASTEX; n = 15) was reared at pasture; the other (CONDEX; n = 18) underwent a specific additional training programme that increased workload by 30%. At mean age 18 months, 6 ani...
Detection of secondary biomarker of met-eGH as a strategy to screen for somatotropin misuse in horseracing. Since the Australian commercialisation of the recombinant equine growth hormone (reGH) in 1998 (EquiGen-5), Bresagen), this reGH, which differs only from eGH by an additional methionine at the N-terminal end (met-eGH), is worldwide suspected to be administered to racehorses as a doping agent. Indeed, the use of this biological drug is considered as a threat to horseracing since it acts both on growth, development or reproductive functions, and on the improvement of performances. In this work, we describe two reliable techniques based on surface plasmon resonance biosensor immunoassay (SPR-BIA)...
The effect of oral sodium acetate administration on plasma acetate concentration and acid-base state in horses. Sodium acetate (NaAcetate) has received some attention as an alkalinizing agent and possible alternative energy source for the horse, however the effects of oral administration remain largely unknown. The present study used the physicochemical approach to characterize the changes in acid-base status occurring after oral NaAcetate/acetic acid (NAA) administration in horses. Methods: Jugular venous blood was sampled from 9 exercise-conditioned horses on 2 separate occasions, at rest and for 24 h following a competition exercise test (CET) designed to simulate the speed and endurance test of 3-da...
Effects of a commercial dose of L-tryptophan on plasma tryptophan concentrations and behaviour in horses. L-tryptophan is a common ingredient in equine calmative products, but its effectiveness has not been demonstrated in horses. Objective: To determine whether a commercial dose of L-tryptophan increases plasma tryptophan and alters behaviour in horses fed a roughage or concentrate meal. Methods: L-tryptophan (6.3 g) or placebo (water) was administered per os in a cross-over design, to 12 Thoroughbred horses (503 +/- 12.1 kg bwt), just before a meal of lucerne hay or oats. Plasma tryptophan was measured by gas chromatography. Horse behaviour was observed in an empty enclosure, then in the presenc...
Graded arrangement of collagen fibrils in the equine superficial digital flexor tendon. By using ultramorphological and biochemical methods, we analyzed the regional differences between the three parts of the equine superficial digital flexor tendon (SDFT), namely, the myotendinous junction (MTJ), middle metacarpal (mM), and osteotendinous junction (OTJ). Cross-sectional images showed unique distributions of collagen fibrils of varying diameters in each region. Small collagen fibrils (diameter 200 nm). In the mM region, the collagen fibrils were intermediately distributed between the MTJ and OTJ. The results indicate a graded arrangement of collagen fibrils in the tendon. Type V ...
Characterization of glycoconjugates in the secretory epithelium of the equine ampulla ductus deferentis. The present work was undertaken to determine the glycoconjugates secreted by the epithelium of the equine ampulla ductus deferentis, using conventional (PAS, AB pH 2.5, AB pH 1.0) and lectin histochemical procedures in conjunction with enzymatic digestion and chemical treatment. The presence of abundant apical cytoplasmic blebs suggests that the equine ampulla secretes its products mainly in an apocrine manner. Glandular cells secrete neutral and acidic sialylated glycoconjugates as revealed by conventional histochemical procedures. Lectin histochemistry helped us to discover the following his...
