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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.
Analysis of phenylbutazone residues in horse tissues with and without enzyme-hydrolysis by LC-MS/MS. Phenylbutazone (PBZ) is permitted to be used for the treatment of musculoskeletal pain and inflammation in race horses but it is not approved for use in horses destined for human consumption. In a recent study initiated in our laboratory to study the disposition of PBZ and its oxyphenbutazone (OXPBZ) metabolite in equine tissues, we compared the effect of an additional enzymatic hydrolysis step with ß-glucuronidase on the results of the analysis for PBZ without enzymatic hydrolysis. Incurred tissue samples obtained from a female horse dosed with PBZ at 8.8 mg/kg for 3 days and sacrificed ...
Response to Intravenous Allogeneic Equine Cord Blood-Derived Mesenchymal Stromal Cells Administered from Chilled or Frozen State in Serum and Protein-Free Media. Equine mesenchymal stromal cells (MSC) are commonly transported, chilled or frozen, to veterinary clinics. These MSC must remain viable and minimally affected by culture, transport, or injection processes. The safety of two carrier solutions developed for optimal viability and excipient use were evaluated in ponies, with and without allogeneic cord blood-derived (CB) MSC. We hypothesized that neither the carrier solutions nor CB-MSC would elicit measurable changes in clinical, hematological, or biochemical parameters. In nine ponies (study 1), a bolus of HypoThermosol(®) FRS (HTS-FRS), CryoSt...
Congenital nutritional myodegeneration in a neonatal foal. A 2-day-old Quarter Horse colt was presented to the Atlantic Veterinary College for recumbency and diarrhea. Dietary history of the dam, serum biochemistry findings, and whole blood selenium levels were consistent with nutritional myodegeneration. The patient was treated successfully with fluid therapy and broad-spectrum antimicrobials. Recovery was uneventful, and the patient was discharged with a favorable prognosis. Un poulain Quarter Horse âgé de deux jours a été présenté à l’Atlantic Veterinary College pour un décubitus et de la diarrhée. L’anamnèse nutritionnelle de la mè...
Controlled trial of whole body protein synthesis and plasma amino acid concentrations in yearling horses fed graded amounts of lysine. Lysine has been reported as the first limiting amino acid in typical equine diets. Indicator amino acid oxidation (IAAO) has become the standard method for determining amino acid requirements in other species, but prior to this study, it has not been used to determine equine requirements. The aim of this study was to evaluate whole body protein synthesis and plasma and muscle amino acid concentrations in response to graded levels of lysine intake in yearling horses. Six Thoroughbred colts (358 ± 5 kg) were fed each of six treatment lysine intakes ranging from 76 to 136 mg/kg body weig...
Caspase 3 Activity and Lipoperoxidative Status in Raw Semen Predict the Outcome of Cryopreservation of Stallion Spermatozoa. Stallion-to-stallion variability in the quality of cryopreserved ejaculates postthaw affects the commercial acceptability of frozen semen and thus is a major constraint for the equine industry. In recent years, the molecular mechanisms associated with sperm damage during cryopreservation have become better understood. Identification of the freezability of the ejaculates before the freezing process is initiated will have a major impact on the equine industry. We studied three markers of oxidative stress in sperm, including 8-iso-PGF2alpha, 8-OH guanosine, and 4-hydroxynonenal (4-HNE); the prese...
Relationship of skeletal muscle inflammation with obesity and obesity-associated hyperinsulinemia in horses. Local (skeletal muscle and adipose) and systemic inflammation are implicated in the development of obesity-associated insulin resistance in humans. In horses, obesity is neither strongly nor consistently associated with systemic inflammation. The role of skeletal muscle inflammation in the development of insulin dysregulation (insulin resistance or hyperinsulinemia) remains to be determined. We hypothesized that skeletal muscle inflammation is related to obesity-associated hyperinsulinemia in horses. Thirty-five light-breed horses with body condition scores (BCSs) of 3/9 to 9/9 were studied, i...
A new strategy for the decellularisation of large equine tendons as biocompatible tendon substitutes. Tendon ruptures and/or large losses remain to be a great clinical challenge and often require full replacement of the damaged tissue. The use of auto- and allografts or engineered scaffolds is an established approach to restore severe tendon injuries. However, these grafts are commonly related to scarce biocompatibility, site morbidity, chronic inflammation and poor biomechanical properties. Recently, the decellularisation techniques of allo- or xenografts using specific detergents have been studied and have been found to generate biocompatible substitutes that resemble the native tissue. This...
Drug Residues after Intravenous Anesthesia and Intrathecal Lidocaine Hydrochloride Euthanasia in Horses. Intrathecal lidocaine hydrochloride under general anesthesia has been used as an alternative method of euthanasia in equids. Carnivore, scavenger, and even human consumption of horse meat from carcasses have been anecdotally reported in rural areas after this method of euthanasia. The presence of drug residues in horse meat has not been investigated. Objective: To investigate if drug residues are found in horse tissues and determine their concentrations. Methods: Of 11 horses requiring euthanasia for medical reasons. Methods: Prospective descriptive study. Horses were anesthetized with total I...
Mitochondrial function is altered in horse atypical myopathy. Equine atypical myopathy in Europe is a fatal rhabdomyolysis syndrome that results from the ingestion of hypoglycin A contained in seeds and seedlings of Acer pseudoplatanus (sycamore maple). Acylcarnitine concentrations in serum and muscle OXPHOS capacity were determined in 15 atypical myopathy cases. All but one acylcarnitine were out of reference range and mitochondrial respiratory capacity was severely decreased up to 49% as compared to 10 healthy controls. The hallmark of atypical myopathy thus consists of a severe alteration in the energy metabolism including a severe impairment in muscl...
Effect of infusion of equine plasma or 6% hydroxyethyl starch (600/0.75) solution on plasma colloid osmotic pressure in healthy horses. OBJECTIVE To compare the effects of equivalent volumes of equine plasma and 6% hydroxyethyl starch (600/0.75) solution (hetastarch) administered IV on plasma colloid osmotic pressure (pCOP) and commonly monitored clinicopathologic variables in horses. ANIMALS 6 healthy mares. PROCEDURES In a randomized, crossover study, horses were administered hetastarch or plasma (both 10 mL/kg, IV) 18 months apart. The pCOP and variables of interest were measured before (baseline), immediately after, and at intervals up to 96 or 120 hours after infusion. Prothrombin and activated partial thromboplastin time...
Lactate and Pyruvate Are Major Sources of Energy for Stallion Sperm with Dose Effects on Mitochondrial Function, Motility, and ROS Production. Stallion sperm rely primarily on oxidative phosphorylation for production of ATP used in sperm motility and metabolism. The objective of the study was to identify which substrates included in Biggers, Whitten, and Whittingham (BWW) media are key to optimal mitochondrial function through measurements of sperm motility parameters, mitochondrial oxygen consumption, and cellular reactive oxygen species (ROS) production. It was expected that mitochondrial substrates, pyruvate and lactate, would support sperm motility and mitochondrial function better than the glycolytic substrate, glucose, due to d...
Oxidative stress markers in Thoroughbred horses after castration surgery under inhalation anesthesia. Oxidative stress has been reported to occur during surgery. It is important to reduce intraoperative oxidative stress to improve the postoperative prognosis. However, there are no reports regarding oxidative stress related to surgery in horses. In the present study, we measured pre and postsurgical diacron-reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP); the oxidative stress index (OSI) was then calculated (OSI=d-ROMs/BAP × 100). d-ROMs were not significantly different between the pre and postsurgical periods. However, BAP significantly decreased after surgery ...
Effects of aging on mitochondrial function in skeletal muscle of American American Quarter Horses. Skeletal muscle function, aerobic capacity, and mitochondrial (Mt) function have been found to decline with age in humans and rodents. However, not much is known about age-related changes in Mt function in equine skeletal muscle. Here, we compared fiber-type composition and Mt function in gluteus medius and triceps brachii muscle between young (age 1.8 ± 0.1 yr, n = 24) and aged (age 17-25 yr, n = 10) American Quarter Horses. The percentage of myosin heavy chain (MHC) IIX was lower in aged compared with young muscles (gluteus, P = 0.092; triceps, P = 0.012), while the percentages of MHC I (gl...
Room temperature fluorescence and phosphorescence study on the interactions of iodide ions with single tryptophan containing serum albumins. In this study, the influence of heavy-atom perturbation, induced by the addition of iodide ions, on the fluorescence and phosphorescence decay parameters of some single tryptophan containing serum albumins isolated from: human (HSA), equine (ESA) and leporine (LSA) has been studied. The obtained results indicated that, there exist two distinct conformations of the proteins with different exposure to the quencher. In addition, the Stern-Volmer plots indicated saturation of iodide ions in the binding region. Therefore, to determine quenching parameter, we proposed alternative quenching model and...
Chondroitin sulphate glycosaminoglycans contribute to widespread inferior biomechanics in tendon after focal injury. Both mechanical and structural properties of tendon change after injury however the causal relationship between these properties is presently unclear. This study aimed to determine the extent of biomechanical change in post-injury tendon pathology and whether the sulphated glycosaminoglycans (glycosaminoglycans) present are a causal factor in these changes. Equine superficial digital flexor tendons (SDF tendons) were surgically-injured in vivo (n=6 injured, n=6 control). Six weeks later they were harvested and regionally dissected into twelve regions around the lesion (equal medial/lateral, pr...
Effect of medium variations (zinc supplementation during oocyte maturation, perifertilization pH, and embryo culture protein source) on equine embryo development after intracytoplasmic sperm injection. Prospective studies were conducted to help define procedural factors affecting in vitro embryo production via intracytoplasmic sperm injection (ICSI) of equine oocytes. In experiment 1, use of 10% fetal bovine serum as a protein source in embryo culture medium resulted in a higher blastocyst rate than did use of a combination of 3% fetal bovine serum, 3% equine preovulatory follicular fluid, and 4% human serum substitute (37% vs. 15%, respectively, P < 0.05). In experiment 2, the effect of zinc supplementation (0, 0.5, 1, or 1.5 μg/mL) during IVM was examined. There were no significant di...
Effects of deoxynivalenol (DON), zearalenone (ZEN), and related metabolites on equine peripheral blood mononuclear cells (PBMC) in vitro and background occurrence of these toxins in horses. Both deoxynivalenol (DON), zearalenone (ZEN), and their metabolites are known to modulate immune cells in various species whereby viability and proliferation are influenced. Such effects were rarely examined in horses. Therefore, one aim of the present study was to titrate the inhibitory concentrations of DON, 3-acetyl-DON (3AcDON), de-epoxy-DON (DOM-1), ZEN, and α- and β-zearalenol (ZEL) at which viability and proliferation of equine PBMC were reduced by 50 % (IC50) and 10 % (IC10) in vitro. For evaluation of practical relevance of the in vitro findings, a further aim was to screen horses...
Simplified strong ion difference approach to acid-base balance in healthy foals. To determine the strong ion difference (SIDa ) and total nonvolatile weak buffers (ATOT ) in healthy foals during the first year of life and to compare reference biochemistry laboratory with analyzers available during emergency hours. Methods: Prospective study performed over 2 years. Methods: University teaching hospital. Methods: Two hundred thirty-six healthy foals distributed in 6 groups: A (21 days-2 months), B (2-3 months), C (3-6 months), D (6-9 months), E (9-12 months), and 33 neonatal foals (< 21 days old). Methods: Blood samples were obtained to determine L-lactate, sodium, potass...
Polyphenols from Silybum marianum inhibit in vitro the oxidant response of equine neutrophils and myeloperoxidase activity. A recent study showed that silymarin, a standardized extract of S. marianum might be used in the prevention of equine laminitis. We investigated the effects of quercetin and some compounds found in silymarin (silybin, taxifolin and dehydrosilybin) on reactive oxygen species (ROS) production and myeloperoxidase (MPO) release by stimulated equine neutrophils (PMNs) and on MPO activity. All compounds (tested between 100 nm and 100 μm) inhibited superoxide anion production by stimulated PMNs in a dose-dependent manner. Dehydrosilybin and quercetin inhibited superoxide production and MPO release...
Implication of the estrogen receptors GPER, ESR1, ESR2 in post-testicular maturations of equine spermatozoa. Estrogen receptors ESR1, ESR2 and GPER are present on mature ejaculated horse spermatozoa, suggesting these cells as putative targets for estrogens. Indeed, spermatozoa are exposed to high level of estrogens during the transit in the male and female genital tracts but their roles are not investigated. So, we evaluated in vitro the role of 17β-estradiol during post-testicular maturations: regulation of motility, capacitation and acrosome reaction. Moreover according to the pseudo-seasonal breeder status of the stallion, we analyzed the putative seasonal variations in the presence of ESRs in sp...
The study of natural and artificial radionuclides incorporation in teeth and head bones of animals lived nearby Caetité uranium mine, Brazil. This study aimed at assessing the incorporation of radionuclides in animals in the proximity of the uranium mine in Caetité, Brazil. In 2014, samples of bovine and equine teeth and skull bones were collected and their contents of natural and artificial isotopes were assessed using nuclear spectrometry techniques. Gamma ray emission from Ra and K isotopes was determined using high-purity germanium (HPGe) spectrometry, Sr radioactivity was measured with liquid scintillation, and U, Th, Po and Pu radioactivity was assessed with alpha-spectrometry. Prior to the measurements, sample dissolutions a...
Binding Analysis of Human Immunoglobulin G as a Zinc-Binding Protein. Human immunoglobulin G (IgG) binding with zinc ions was examined using zinc ions immobilized on chelating Sepharose beads (Zn-beads). Human IgG bound to Zn-beads but not to Sepharose beads (control beads). Mouse, rat, bovine and equine IgGs also bound to Zn-beads, similar to human IgG. The human IgG F(c) fragment showed zinc ion-binding activity whereas the Fab fragment did not. Ethylenediaminetetraacetic acid (EDTA)-treated Zn-beads no longer bound human IgG; however, washing the beads, followed by the addition of zinc ions, restored the binding activity towards human IgG. Zn-beads saturated ...
Histological and lectin histochemical studies of the vomeronasal organ of horses. The morphological characteristics and glycoconjugate composition of the vomeronasal organ (VNO) of the horse was investigated using histological, immunohistochemical, and lectin histochemical methods. The VNO is bilaterally located at the base of the nasal septum, has a tubular structure surrounded by cartilage, and consists of sensory and non-sensory epithelia. Immunohistochemical examination showed that the vomeronasal sensory epithelium (VSE) consisted of receptor cells positive for both olfactory marker protein (OMP) and protein gene product 9.5 (PGP 9.5), supporting cells, and basal cells...
Repeatability of the ACTH stimulation test as reflected by salivary cortisol response in healthy horses. The aim of this study was to further characterize the ACTH stimulation test as reflected by salivary cortisol response and to measure the short- and long-term repeatability of it in healthy horses as a tool to assess the capacity of the adrenal cortex to secrete cortisol. Nineteen healthy horses were subjected to 3 ACTH stimulation tests. Intervals were 2 wk and 5 mo between the first and second and the second and third tests, respectively. A dose of 1-μg/kg BW synthetic ACTH was injected intravenously. Saliva samples were collected at baseline and at 30, 60, 90, 120, 150, and 180 min afte...
Cytosine methylation of sperm DNA in horse semen after cryopreservation. Semen processing may contribute to epigenetic changes in spermatozoa. We have therefore addressed changes in sperm DNA cytosine methylation induced by cryopreservation of stallion semen. The relative amount of 5-methylcytosine relative to the genomic cytosine content of sperm DNA was analyzed by ELISA. In experiment 1, raw semen (n = 6 stallions, one ejaculate each) was shock-frozen. Postthaw semen motility and membrane integrity were completely absent, whereas DNA methylation was similar in raw (0.4 ± 0.2%) and shock-frozen (0.3 ± 0.1%) semen (not significant). In experiment 2, three ej...
Randomised clinical trial on the effect of a single oral administration of l-tryptophan, at three dose rates, on reaction speed, plasma concentration and haemolysis in horses. Tryptophan (TRP) is marketed as a calmative for horses despite reservations about its efficacy. The aim of this study was to measure the effect of oral TRP administration on the reaction speed of horses. Sixty mature horses were used in a two stage randomised, blind, cross-over study, receiving a placebo and an oral dose of TRP (30, 60 or 120 mg/kg body weight), before undergoing a reaction speed test. Blood samples were taken up to 96 h after TRP administration, to identify signs of acute haemolytic anaemia. Plasma TRP concentrations were increased (P <0.001) by the administration of...
Proteome of equine oviducal fluid: effects of ovulation and pregnancy. The equine oviduct plays a pivotal role in providing the optimal microenvironment for early embryonic development, but little is known about the protein composition of the oviducal fluid in the horse. The aim of the present study was to provide a large-scale identification of proteins in equine oviducal fluid and to determine the effects of ovulation and pregnancy. Four days after ovulation, the oviducts ipsilateral and contralateral to the ovulation side were collected from five pregnant and five non-pregnant mares. Identification and relative quantification of proteins in the oviducal fluid ...
Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids. Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. During a potentially aversive situation, corticotrophin releasing hormone (CRH) is released from the hypothalamus in the brain. This stimulates the release of adrenocorticotrophic hormone (ACTH) from the pituitary gland, which in turn stimulates release of glucocorticoids from the adrenal gland. In horses the glucocorticoid corticosterone is responsible for several adaptations needed to support equine flight behaviour and subsequent removal from the aversive situation. Corticosterone met...
Aldehyde Dehydrogenase Plays a Pivotal Role in the Maintenance of Stallion Sperm Motility. Although stallion spermatozoa produce significant quantities of reactive oxygen species, a lag between 4-hydroxynonenal (4HNE) adduction and the loss of motility in stallion spermatozoa suggests the presence of a robust aldehyde detoxification mechanism. Because there is a paucity of studies characterizing the role of aldehyde dehydrogenase (ALDH) in sperm functionality, the aim of this study was to ascertain the relationship between 4HNE production and motility and ALDH expression by stallion spermatozoa. PCR analysis revealed the presence of the ALDH1A3, ALDH1B1, and ALDH2 isoforms in these ...
