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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.
Cytokeratins of the matrices of the chestnut (torus carpeus) and periople in horses with acute laminitis. To determine whether there is a change in the expression of cytokeratins in the epidermal cells of the non-weight-bearing parts of the limb in horses with acute laminitis and thus determine whether the morphologic changes that develop in the periople and chestnut (torus carpeus) of horses early in acute laminitis are caused by inhibition of keratinocyte differentiation. Methods: 8 horses with acute laminitis. Methods: Tissue specimens were obtained from the chestnuts of all 8 horses and from the stratum externum of the hoof wall of 3 horses. Tissue specimens were obtained within 48 hours of th...
Estimation of the probability for exceeding a threshold concentration of furosemide at various intervals after intravenous administration in horses. To estimate the probability for exceeding a threshold concentration of furosemide commonly used for regulatory purposes after IV administration of furosemide in horses. Methods: 12 mature healthy horses (6 Thoroughbreds and 6 Quarter Horses). Methods: Venous blood was collected from each horse prior to and 0.25, 0.5, 0.75, 1, 2, 3, 4, 4.5, 5, and 6 hours after administration of 250 or 500 mg of furosemide. Concentrations of furosemide were determined, using an ELISA. Concentration of furosemide was modeled as a function of time, accounting for inter- and intrahorse variabilities. On the basis ...
Variations in cartilage catabolism in different equine joints in response to interleukin-1 in vitro. An explant system was used to investigate the hypothesis that cartilage from different equine joints might respond differently to challenge with interleukin-1alpha (IL-1alpha). Pairs of normal cartilage samples were taken from the metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints of six horses. One of each pair was stimulated with 10 ng/ml human recombinant IL-1alpha for three days, and the supernatants and remaining cartilage explants were analysed for their total content of glycosaminoglycans. A significantly higher percentage of glycosaminoglycans was released ...
Assessment of the rate of solid-phase gastric emptying in ponies by means of the 13C-octanoic acid breath test: a preliminary study. The aim of this study was to assess the feasibility of applying the 13C-octanoic acid breath test for assessment of gastric emptying in ponies by investigating the pattern of 13C enrichment in breath following the administration of a test meal +/- 13C-octanoic acid. After a 14 h fast, the ponies received either no meal (Test I) or a standardised test meal labelled with 0 mg (Test II), 125 mg (Test III), 250 mg (Test IV) or 500 mg (Test V) 13C-octanoic acid. For each test (I-V), exhaled breath samples were collected in duplicate at 1 h and immediately before ingestion of the test meal and at fr...
MMP-9 as a marker of inflammation in tracheal epithelial lining fluid (TELF) and in bronchoalveolar fluid (BALF) of COPD horses. Gelatinolytic activity was analysed to study whether elevated activity previously found at the tracheal level of the respiratory tract of horses with chronic obstructive pulmonary disease (COPD) could also be found at the lower part of the respiratory tract. Furthermore, presence and significance of the gelatinolytic matrix metalloproteinases (MMPs) MMP-2 and MMP-9 in respiratory secretions of healthy and COPD horses were determined. Elevated gelatinolytic matrix metalloproteinases were detected in bronchoalveolar and tracheobronchial secretions from COPD horses. The main pathologically elevat...
beta-Subunit 102-104 residues are crucial to confer FSH activity to equine LH/CG but are not sufficient to confer FSH activity to human CG. Horse LH/CG (eLH/CG) and donkey LH/CG (dkLH/CG) are strictly LH-specific in their respective homologous species. However, both bind to the FSH receptors from non-equid species, whereas the zebra hormone (zbLH/CG) does not. The FSH/LH ratio of eLH/CG and of the alphadkbetae hybrid is about tenfold higher than that of dkLH/CG and of the alphaebetadk hybrid, showing that the betae subunit contains the structural features responsible for the high FSH activity of eLH/CG. Only six amino acid positions (51, 94, 95, 102, 103 and 106) are unique to the betae subunit when compared with the betadk and be...
In situ zymography: topographical considerations. In situ gelatin zymography is a simple technique providing valuable information about the cellular and tissue localization of gelatinases. Until recently, the use of this technique has been confined to soft, relatively homogeneous tissue. In this report in situ zymography has been utilized to assess the sub-lamellar location of gelatinases in the hard, semi-keratinized epidermal layer and the adjacent soft connective tissue matrix of the dermis of the equine hoof. We show that alterations in the orientation at which the tissue is dipped and withdrawn from the emulsion cause profound alteration...
Glycerol hyperhydration in resting horses. To determine whether administration of glycerol-containing solutions induces a state of transient hyperhydration in resting euhydrated horses, changes in plasma and urine constituents were measured in four horses for 1 h before and 5 h after nasogastric administration of each of four treatments (Experiment 1). Treatments were applied in a randomized fashion and included: (1) 1.0 g.kg(-)(1)glycerol in 8 L of water (G); (2) 8 L of water (W); (3) 8 L of 0.9% NaCl solution (S); and (4) 1.0 g.kg(-)(1)glycerol in 8 L of 0.9% NaCl solution (GS). In a subsequent study, voluntary water intake was measu...
Expression of 3beta-hydroxysteroid dehydrogenase, cytochrome p450 17alpha-hydroxylase/17,20-lyase and cytochrome p450 aromatase enzymes in corpora lutea of diestrous and early pregnant mares. In the pregnant mare, luteal estrogen production increases at the onset of equine chorionic gonadotropin (eCG) secretion by endometrial cups. In previous studies, we have demonstrated that eCG stimulates luteal androgen and estrogen production in pregnant mares. To further elucidate the regulation of steroidogenesis within the equine corpus luteum (CL) of pregnancy, we examined the expression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), cytochrome P450 17alpha-hydroxylase/17,20 lyase (P450(17alpha)) and cytochrome P450 aromatase (P450(arom)) in luteal tissue samples collected during dies...
In vitro evidence for a bacterial pathogenesis of equine laminitis. Utilizing an in vitro laminitis explant model, we have investigated how bacterial broth cultures and purified bacterial proteases activate matrix metalloproteinases (MMPs) and alter structural integrity of cultured equine lamellar hoof explants. Four Gram-positive Streptococcus spp. and three Gram-negative bacteria all induced a dose-dependent activation of MMP-2 and MMP-9 and caused lamellar explants to separate. MMP activation was deemed to have occurred if a specific MMP inhibitor, batimastat, blocked MMP activity and prevented lamellar separation. Thermolysin and streptococcal pyrogenic ex...
Cytokeratins of the stratum medium and stratum internum of the equine hoof wall in acute laminitis. The cytoskeleton of living keratinocytes consists mainly of cytokeratins that have polymerised into intermediate filaments. The aim of this study was to describe the expression of cytokeratins in the living epidermal cells of the weight-bearing parts of the equine hoof wall during acute spontaneous laminitis. A total of 9 hooves from 3 horses subjected to euthanasia within 48 h of the first clinical signs of laminitis were sectioned and examined. The cytokeratins in the stratum medium and stratum internum of the hoof wall were characterized by 1- and 2-dimensional gel electrophoresis, and the ...
[ACTH stimulation test for the determination of salivary cortisol and of cortisol responses as markers of the training status/fitness of warm-blooded sports horses]. Previous work (Marc et al., 2000) suggested that plasma cortisol responses to treadmill exercise or ACTH injection are a reliable marker for performance evaluation in warmblood horses. For practical purposes blood sample collections and treadmill exercise tests are somewhat troublesome and time consuming. The goal of this study was thus to evaluate the use of saliva for cortisol determination (by direct EIA) as a marker for performance and to investigate the reliability and repeatability of plasma cortisol responses to a single i.v. injection of ACTH (50 micrograms or 250 micrograms). Furtherm...
[Receptor sialylsugar chains as determinants of host range of influenza viruses]. All types of the hemagglutinin(HA) of human, pig, horse and aq. bird influenza A viruses, recognize sialyl lacto-series type I and II sugar chains(Sialic acid(SA) alpha 2-3(6)Gal beta 1-3(4) GlcNAc beta 1-) in glycoproteins and glycolipids in the target cells as common receptor molecules. Avian and equine influenza viruses preferentially binds the terminal sialic acid alpha 2-3Gal(SA2-3Gal) linkage, while human influenza viruses preferentially bind the SA2-6Gal linkage. SA distribution in animal species influence influenza virus host range. Swine trachea has both receptors for avian influenza ...
In vitro quantitative analysis of (3)H-uracil incorporation by Sarcocytis neurona to determine efficacy of anti-protozoal agents. Parasite-specific incorporation of (3)H-uracil was used to assess the replication of Sarcocystis neurona, a protozoal parasite associated with equine protozoal myeloencephalitis (EPM). Anti-protozoal drugs, pyrimethamine (0.01, 0.1 and 1.0microg/ml PYR), sulfadiazine (5microg/ml; SDZ), sulfamethoxazole (5microg/ml; SMZ), diclazuril (100ng/ml; DCZ), atovaquone (0.04ng/ml; ATQ), tetracycline (5microg/ml; TET) and the herbicide glyphosate (1.5 and 4.5mM; GLY) were studied with varying S. neurona parasite densities (2x10(1)-1.2x10(6)merozoites/well). A microtiter plate format was used to test thes...
Effect of eltenac in horses with induced endotoxaemia. Ten horses were used in a crossover study to evaluate the effectiveness of eltenac against endotoxaemia. Eltenac (0.5 mg/kg bwt) or saline control was given i.v. then 15 min later, intravenous infusion of endotoxin was begun and continued for 120 min (total dose 100 ng/kg bwt). Horses were monitored for heart and respiratory rates, pulmonary and carotid arterial pressure and core body temperature. Blood was sampled at intervals for measurement of haematological variables and plasma concentrations of lactate, prostanoid metabolites, tumour necrosis factor (TNF) and stress hormones. In compariso...
Aggregation behavior and electrophoretic mobility of red blood cells in various mammalian species. Differences of red blood cell (RBC) aggregation among various mammalian species has been previously reported for whole blood, for RBC in autologous plasma, and for washed RBC re-suspended in polymer solutions. The latter observation implies the role of cellular factors, yet comparative studies of such factors are relatively limited. The present study thus investigated RBC aggregation and RBC electrophoretic mobility (EPM) for guinea pigs, rabbits, rats, humans and horses; RBC were re-suspended in isotonic 500 kDa dextran solutions for the EPM and aggregation measurements, with aggregation stud...
Effect of oral administration of excessive iron in adult ponies. To evaluate the potential of excess dietary iron to cause hepatic lesions similar to those described in horses with suspected iron toxicosis or hemochromatosis. Methods: Prospective study. Methods: 6 adult male ponies. Methods: 4 ponies received 50 mg of iron/kg (22.7 mg/lb) of body weight each day by oral administration of ferrous sulfate, which contained 20% elemental iron; 2 ponies received only the carrier (applesauce). Complete blood counts, serum biochemical analyses, and hepatic tissue biopsies were performed, and serum iron concentrations were measured. Blood and tissue samples were ob...
Assessment of stallion spermatozoa viability by flow cytometry and light microscope analysis. Viability of spermatozoa can be assessed by numerous methods, but many are slow and poorly repeatable, and subjectively assess only 100 to 200 spermatozoa per ejaculate. We collected two ejaculates from each of 4 stallions, and extended them to 50x10(6) sperm/mL in a nonfat dried milk solids glucose extender (EZ Mixin). Half the ejaculate was freeze-killed by immersing in liquid nitrogen for 10 min. Aliquots using appropriate volumes of live and freeze-killed spermatozoa provided the following ratios of live:dead spermatozoa: 100:0, 75:25, 50:50, 25:75, 0:100. We determined the viability of ea...
The interaction of ferrocytochrome c with long-chain fatty acids and their CoA and carnitine esters. Non-covalent modification of cytochrome c may have implications for electron transport and energy metabolism. We examined the interaction of various fatty acids (FAs), their coenzyme A and carnitine esters, and fatty alcohols with horse heart ferrocytochrome c. A comparison of FAs indicated a minimum chain length of 14 carbons was required for significant effect on the ferroheme chromophore and major changes in electronic spectra. Coenzyme A and carnitine esters interacted less strongly than FAs whereas long-chain alcohols did not interact with the protein. We found a single, saturable FA bind...
Early and long-term changes of equine skeletal muscle in response to endurance training and detraining. Twenty-four 4-year-old Andalusian (Spanish breed) stallions were used to examine the plasticity of myosin heavy chain (MHC) phenotype and the metabolic profile in horse skeletal muscle with long-term endurance-exercise training and detraining. Sixteen horses underwent a training programme based on aerobic exercises for 8 months. Afterwards, they were kept in paddocks for 3 months. The remaining eight horses were used as controls. Three gluteus medius muscle biopsy samples were removed at depths of 20, 40 and 60 mm from each horse before (month 0), during (month 3) and after (month 8) training,...
In vitro pharmacologic effect of two endothelin-1 antagonists on equine colonic arteries and veins. To evaluate the effectiveness of 2 potential endothelin (ET)-1 antagonists in blocking the contractile responses of equine colonic vessels to increasing concentrations of ET-1. Methods: Mesenteric vessels from 6 clinically healthy horses. Methods: Colonic vessels (arterial and venous rings) were placed in organ baths with oxygenated Tyrode solution at 37 C. Each was attached to a force transducer interfaced with a polygraph, and 2 g of tension was applied and equilibrated for 45 minutes. Then, B-1 (PD 142893) and B-2 (PD 145065) ET-1 antagonists were tested. One ring from each vessel type was ...
Cross-sectional comparison of synovial fluid biochemical markers in equine osteoarthritis and the correlation of these markers with articular cartilage damage. To investigate the relationship between biochemical markers in the synovial fluid of osteoarthritic and contralateral equine joints and gross articular cartilage pathology. Methods: Twenty-two horses underwent bilateral arthroscopy of their carpal or metacarpophalangeal joints following recent onset lameness. The degree of cartilage damage in each joint was scored and synovial fluid, from both the clinically affected and the contralateral joint, was collected. Bone specific alkaline phosphatase (BAP), 5D4 epitope of keratan sulphate (KS), total glycosaminoglycans (GAG) and hyaluronan (HA) were...
Rate of intrachain contact formation in an unfolded protein: temperature and denaturant effects. We have measured the effect of temperature and denaturant concentration on the rate of intrachain diffusion in an unfolded protein. After photodissociating a ligand from the heme iron of unfolded horse cytochrome c, we use transient optical absorption spectroscopy to measure the time scale of the diffusive motions that bring the heme, located at His18, into contact with its native ligand, Met80. Measuring the rate at which this 62 residue intrachain loop forms under both folding and unfolding conditions, we find a significant effect of denaturant on the chain dynamics. The diffusion of the cha...
Heterologous expression of lacticin 3147 in Enterococcus faecalis: comparison of biological activity with cytolysin. Lacticin 3147 is a broad-spectrum, two-component, lanthionine-containing bacteriocin produced by Lactococcus lactis DPC3147 which has widespread food and biomedical applications as a natural antimicrobial. Other two-component lantibiotics described to date include cytolysin and staphylococcin C55. Interestingly, cytolysin, produced by Enterococcus faecalis, has an associated haemolytic activity. The objective of this study was to compare the biological activity of lacticin 3147 with cytolysin. The lacticin 3147-encoding determinants were heterologously expressed in Ent. faecalis FA2-2, a plasm...
Expression of Babesia equi merozoite antigen 1 in insect cells by recombinant baculovirus and evaluation of its diagnostic potential in an enzyme-linked immunosorbent assay. The gene encoding the entire Babesia equi merozoite antigen 1 (EMA-1) was inserted into a baculovirus transfer vector, and a recombinant virus expressing EMA-1 was isolated. The expressed EMA-1 was transported to the surface of infected insect cells, as judged by an indirect fluorescent-antibody test (IFAT). The expressed EMA-1 was also secreted into the supernatant of a cell culture infected with recombinant baculovirus. Both intracellular and extracellular EMA-1 reacted with a specific antibody in Western blots. The expressed EMA-1 had an apparent molecular mass of 34 kDa that was identical ...
The equine herpesvirus 1 immediate-early protein interacts with EAP, a nucleolar-ribosomal protein. The equine herpesvirus 1 (EHV-1) immediate-early (IE) phosphoprotein is essential for the activation of transcription from viral early and late promoters and regulates transcription from its own promoter. The IE protein of 1487 amino acids contains a serine-rich tract (SRT) between residues 181 and 220. Deletion of the SRT decreased transactivation activity of the IE protein. Previous results from investigation of the ICP4 protein, the IE homolog of herpes simplex virus 1 (HSV-1), revealed that a domain containing a serine-rich tract interacts with EAP (Epstein-Barr virus-encoded small nuclear...
Non-invasive assessment of equine bone: an update. This paper summarizes traditional and current methods of non-invasive assessment of bone in the horse. The description and potential clinical utility of two non-invasive technologies with major development in the last decade are presented, namely, (1) serum biochemical markers for bone turnover and (2) quantitative ultrasound. Serum biochemical markers of bone formation valid in horses are osteocalcin, carboxy-terminal peptide of type I procollagen and bone-specific alkaline phosphatase. The cross-linked carboxy-terminal telopeptide of type 1 collagen c-telopeptides of type I collagen and tota...
Role of exercise and ascorbate on plasma antioxidant capacity in thoroughbred race horses. During exercise, the oxygen consumption and the production of free radicals increase and can lead to oxidative stress with a deleterious effect on cellular structures involved in physical activity. To evaluate the oxidative stress produced by exercise and the role of ascorbate as an antioxidant, venous blood samples were obtained from 44 thoroughbred racehorses, before and after a 1000+/-200-m race at maximum velocity. Fourteen of these horses were treated intravenously with 5 g of ascorbate before running. Antioxidant capacity (PAOC), endogenous and exogenous ascorbate concentration, total an...
Molecular cloning and sequencing of equine cDNA encoding serum amyloid A (SAA). The serum amyloid A (SAA) protein is a characteristic and sensitive acute phase reactant in all vertebrates investigated. We molecularly cloned the equine cDNA encoding SAA from the liver of a healthy horse by polymerase chain reaction (PCR). The cloned cDNA is 480 bases in length, and contains an open reading frame (ORF) of 387 nucleotides encoding a precursor SAA protein of 128 amino acids. The precursor of horse SAA seems to have an 18-residue signal peptide and differs from the reported amino acid sequences of the horse SAA by substitution of valine at residue 81. It shows high homology wi...
Expression and characterisation of equine interleukin 2 and interleukin 4. In the present study, we describe the expression of equine IL2 and IL4. The cDNA of equine IL2 or IL4 was cloned in a mammalian expression vector, containing c-terminal myc- and six histidines His(6)-epitopes for recognition and purification of equine cytokines. The vector constructs were used for transfection of chinese hamster ovary (CHO) cells. Purified equine cytokines were characterised by western blotting. Equine IL2 was secreted with a molecular weight of approximately 17.1kDa, whereas IL4 was expressed in three different sizes of 17.1, 19.6 and 22.1kDa, probably due to different glycos...
