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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.
Effects of exercise and EDTA administration on blood ionized calcium and parathyroid hormone in horses. To determine effects of exercise on blood ionized calcium (Ca2+) and plasma parathyroid hormone (PTH) concentrations in horses and to compare the effects of exercise-induced and EDTA-induced hypocalcemia on PTH secretion. Methods: 17 horses entered in a show jumping competition and 5 horses given EDTA. Methods: Blood Ca2+ and plasma PTH concentrations were measured before and after exercise in the 17 horses entered in the jumping competition. In the other 5 horses, concentrations were measured during infusion of EDTA IV. Results: Exercise resulted in a significant decrease in blood Ca2+ concen...
Effect of irradiation with a low-intensity diode laser on the metabolism of equine articular cartilage in vitro. To determine whether irradiation with a low-intensity diode laser, which produces radiation at a wavelength of 810 nm, will induce nonthermal enhancement of chondrocyte metabolism. Methods: 144 grossly normal articular cartilage explants aseptically harvested from the femoral condyles of 6 adult horses. Methods: Treated cartilage explants were irradiated with a diode laser at 1 of 7 fluence levels that ranged from 8 to 1,600 J/cm2. Explants were incubated for 24 or 72 hours, labeled for 24 hours with [35S]Na2SO4, and assayed for newly synthesized sulfated glycosaminoglycan (GAG; measured incor...
Molecular characteristics of equine stromelysin and the tissue inhibitor of metalloproteinase 1. To clone the entire coding sequence of equine matrix metalloproteinase-3 (MMP-3, stromelysin) and tissue inhibitor of metalloproteinase-1 (TIMP-1) and compare their nucleotide and amino acid sequences with those of MMP-3 and TIMP-1 from other species. Methods: Articular cartilage harvested from the joints of 4 foals, 2 yearlings, and 3 adult horses. Methods: A cDNA library was constructed from mRNA extracted from equine chondrocytes. The library was screened and clones selected that contained the cDNA for MMP-3 and TIMP-1. The cDNA was sequenced and the nucleotide and deduced amino acid sequen...
The 2.03 signal as an indicator of dinitrosyl-iron complexes with thiol-containing ligands. The parameters of EPR signal from dinitrosyl-iron complexes (DNIC) with bovine serum albumin (BSA), horse hemoglobin (Hb), and apometallothionein (apo-Mt) of horse kidney incorporating one (BSA, Hb) or two thiol-containing ligands (apo-Mt) were compared. The EPR signal from DNIC-BSA was characterized by the rhombic symmetry of g tensor at room temperature of signal recording (ambient temperature) or at 77K in the solution frozen in the presence of glycerol. In freezing of the solution in the absence of glycerin, under the exposure of DNIC-BSA to negatively charged sodium dodecyl sulfate (SDS) ...
Relative binding of therapeutic drugs by sera of seven mammalian species. The relative binding of acetaminophen, lidocaine, phenobarbital, procainamide, quinidine, and theophylline to sera of seven mammalian species was studied. Pooled commercial sera from cow, goat, horse, human, pig, rabbit, and sheep were supplemented with 5 and 10 mM concentrations of each drug. For each serum, each drug, and each drug concentration, equilibrium dialysis was performed in duplicate against phosphate buffer (pH 7.4, 0.1 M, 4 degrees C). Percent drug bound to serum was calculated. Phenobarbital demonstrated more than 20% binding to goat, horse, human, and sheep serum at both 5 and ...
Macroscopic ‘degeneration’ of equine superficial digital flexor tendon is accompanied by a change in extracellular matrix composition. Injuries to the superficial digital flexor tendon are common in horses required to gallop and jump at speed. Partial rupture of this tendon usually occurs in the central core of the midmetacarpal region and may be preceded by localised degenerative changes. Post mortem examination of apparently normal equine flexor tendons has revealed an abnormal macroscopic appearance in the central core, characterised by a reddish discolouration. We have previously shown that there is also physical damage to the collagen fibres. In the present study we tested the hypothesis that the abnormal appearance is a...
Measurement of parathyroid hormone in horses. Measurement of parathyroid hormone (PTH) in horses was performed on plasma samples using 2 immunoradiometric assays: a human intact PTH assay and a rat amino-terminal PTH assay. The assays were validated by assessment of their precision, sensitivity and specificity, and also by evaluating PTH changes in the horse in response to variation in blood ionised calcium. Intra- and inter-assay variance, precision and sensitivity were similar for both human and rat assays; however, the rat assay was slightly more precise and sensitive than the human assay. Both assays detected an increase in PTH levels...
In vitro generation of equine osteoclasts from bone marrow cells using a novel culture system. We report on preliminary results of a novel in vitro culture system designed to generate equine osteoclasts in large numbers. Osteoclast generation, as determined by the expression of tartrate resistant acid phosphatase (TRAP) and ability to resorb bone, was enhanced in equine bone marrow cultures supplemented with fibroblastic cell (L929) conditioned medium (L929-CM). Bone marrow was collected from a total of 12 horses and ponies and TRAP-positive cells with bone resorbing ability were generated in significant numbers in the last seven. TRAP-positive mononuclear cells appeared after three day...
Inhibin secretion in the mare: localization of inhibin alpha, betaA, and betaB subunits in the ovary. To determine the source of circulating inhibin and estradiol-17beta during the estrous cycle in mares, the cellular localization of the inhibin alpha, betaA, and betaB subunits and aromatase in the ovary was determined by immunohistochemistry. Concentrations of immunoreactive (ir-) inhibin, estradiol-17beta, progesterone, LH, and FSH in peripheral blood were also measured during the estrous cycle in mares. Immunohistochemically, inhibin alpha subunits were localized in the granulosa cells of small and large follicles and in the theca interna cells of large follicles, whereas inhibin betaA and ...
Localisation of gelatinase activity in epidermal hoof lamellae by in situ zymography. In situ gelatin zymography is a technique, which utilises a gelatin-based emulsion overlay to detect and, more importantly, localise the gelatinase activity in underlying tissue. Gelatinase A [matrix metalloproteinase-2 (MMP-2)] and gelatinase B [matrix metalloproteinase-9 (MMP-9)] are present in equine hoof homogenates and supernatants from cultured hoof explants by SDS-PAGE gelatin zymography, and it has been assumed that the enzymes are derived solely from matrix and epithelia and not from other sources such as leucocytes. Using in situ zymography, gelatinases are shown to be localised with...
[Phenotypic characterization of equine Dermatophilus congolensis field isolates]. In 1993 and 1994 a highly increased occurrence of equine dermatophilosis was observed, and a study was initiated to determine phenotypic heterogeneity among 120 clinical isolates using biochemistry, antibiotic resistance profiles, membrane protein profiles and Western blotting. The biochemical examinations contained 1% equine serum in medium. Moreover, the API ZYM-test from bioMérieux was used. The biochemical reactions were suited to identify Dermatophilus congolensis but did not allow a differentiation among the various isolates. Antibiotic resistance in one or more isolates was observed ag...
Flow cytometric determination of oxidative burst activity of equine peripheral blood and bronchoalveolar lavage-derived leucocytes. Flow cytometric techniques were developed for the evaluation of oxidative burst activity in equine peripheral blood neutrophils and lymphocytes, as well as bronchoalveolar lavage derived pulmonary alveolar macrophages and lymphocytes. The oxidation of dichlorofluorescin was measured by the increased fluorescence of cells stimulated with phorbol myristate acetate or a variety of other stimulants. Flow cytometry was a suitable method for the evaluation of the intracellular oxidation in all cell populations evaluated. Analysis was rapid and cell separation before analysis was not required. Hetero...
Iron loading into ferritin by an intracellular ferroxidase. An intracellular, membrane-bound enzyme exhibiting both p-phenylenediamine oxidase activity and ferrous iron oxidase activity was isolated with the plasma membrane fraction of horse heart and studied for its ability to load iron into ferritin. The ferroxidase activity of the tissue oxidase was stimulated approximately twofold by horse spleen apoferritin, and the iron was loaded into ferritin. The loading of iron into ferritin by the tissue oxidase was inhibited by anti-horse serum ceruloplasmin antibody. The stoichiometry of iron oxidation and oxygen consumption during iron loading into ferrit...
Experimental infection of four horses with Ehrlichia phagocytophila. Four clinically healthy horses which were negative for antibodies to Ehrlichia phagocytophila, the agent of bovine ehrlichiosis, were infected experimentally with E phagocytophila-containing bovine leucocytes, administered intravenously. The horses were examined daily for four weeks, and blood samples were collected daily for cytological, haematological and biochemical examination and for a nested polymerase chain reaction (PCR). An indirect immunofluorescence test was used to determine when the horses seroconverted and the duration of positive titres. There were no abnormal clinical, haematol...
Physical exercise, oxidative stress and muscle damage in racehorses. Since it has been suggested that lipid peroxidation following free radical overproduction may be one of the causes of physical exercise-induced myopathies and hemolysis in horses, we looked for the possible relationships between these phenomena and muscle fiber damage. We use a homogeneous group of Maremmana stallions which, after a 3-month training period, underwent a series of physical exercises of increasing intensity. We determined the contents of malondialdehyde (MDA), one of the main lipid peroxidation end-products, and glutathione the substrate of one of the most important free radical ...
Pressure and temperature dependence of enantioselective excited-state quenching of chiral Tb(III) and Eu(III) tris(pyridine-2,6-dicarboxylate) chelates by various C-type ferricytochromes. For mitochondrial ferricytochrome c from horse, cow and tuna and for bacterial cytochrome c-550 from Paracoccus versutus, the pressure and temperature dependence of their quenching of racemic Tb(DPA)3(3-) and Eu(DPA)3(3-) (DPA = pyridine-2,6-dicarboxylate) luminescence in aqueous solution is investigated. Of these energy transfer reactions the activation volumes (delta V#) and energies (Ea) are determined for the ranges P = 0-3 kbar and T = 15-40 degrees C. For the lambda enantiomers of Tb(DPA)3(3-) and Eu(DPA)3(3-), delta V# and Ea are almost the same for all proteins: 0.4 < or = delta V# < o...
Equine chorionic gonadotropin regulates luteal steroidogenesis in pregnant mares. The onset of eCG secretion in pregnant mares coincides with an increase in luteal steroid production and a relative shift toward androgen and estrogen synthesis. However, a cause-effect relationship between eCG and the shift in luteal steroidogenesis has not been demonstrated. In this study, we have investigated the effect of eCG on steroid production by the corpus luteum (CL) during equine pregnancy. All mares were supplemented with 44 mg altrenogest (a progestogen) per day on Days 18-50. Increasing doses of eCG were administered on Days 26-28, before the onset of endogenous eCG secretion, to...
Hematologic and serum biochemical variables and plasma corticotropin concentration in healthy aged horses. To compare hematologic and serum biochemical variables and plasma ACTH concentration between healthy horses 5 to 12 years old and those more than 20 years old. Methods: 30 healthy horses 5 to 12 years old and 30 healthy horses more than 20 years old. Methods: Venous blood was collected from all horses, and CBC and serum biochemical analysis were performed for each horse. Plasma ACTH concentration was determined by radioimmunoassay. Student's paired t-test or the Mann-Whitney rank sum test was used to compare values between control and aged horse groups. Results: Compared with values for contro...
Establishment of a monoclonal antibody (1/14/16H9) for detection of equine keratan sulfate. To establish a sensitive and specific monoclonal antibody (MAB) against equine keratan sulfate (KS) and to develop an enzyme immunoassay for measurement of the concentration of KS in serum and synovial fluid from horses. Methods: 18 synovial fluid and 48 serum samples were obtained from clinically normal horses and horses with arthritis. Methods: BALB/c mice were immunized with chondroitinase-ABC-digested proteoglycan monomer from equine joint cartilage, and MAB were raised, using Sp2/O cells as a fusion partner. A competitive ELISA was optimized, using one of the established MAB, and KS conce...
Structures of buffalo and mare lactoferrins. Similarities, differences, and flexibility. Lactoferrin (Lf), an iron binding glycoprotein found in the external secretions and neutrophilic leucocytes of mammals, is thought to be responsible for primary defence against microbial infection, mainly as a result of lactoferrin sequestration of iron required for microbial growth (Weinberg, 1978). Many other functions have been attributed to lactoferrin, including immunomodulation and cell growth regulation (Lbnnerdal & lyer, 1995). The lactoferrin has molecular mass of 80 kDa. The protein folds into two globular lobes, the N-lobe comprising the N-terminal half of the polypeptide chain ...
Breath hydrogen measurement in ponies: a preliminary study. The aim of this study was to establish the normal patterns of breath hydrogen excretion in adult ponies following either voluntary consumption or administration per stomach tube of a test meal/carbohydrate substrate. After an overnight fast, the ponies (n = 7) received either no test meal (ie fasted), glucose, xylose, lactose, lactulose, wheat flour or oats. Exhaled breath samples were collected in duplicate at 0 minutes and at 30-minute intervals thereafter for eight hours. Analysis of duplicate breath hydrogen measurements (n = 714) indicated that the breath hydrogen collection/storage metho...
Neopterin values in selected groups of normal animals. To establish baseline information on neopterin concentrations in livestock, companion and laboratory animals and identify the factors that may influence these concentrations, blood samples were taken from normal dairy cattle, horses, llamas, dogs, cats and rats of varying ages and sexes. In addition, neopterin concentrations in normal, adult equines were compared with those found in racing Thoroughbreds. There were no differences due to sex, sexual maturity, pregnancy, castration, or age. For all ages and sexes combined, mean neopterin concentrations were significantly lower in llamas (2.27+/-...
Quantification of penicillin-G and procaine in equine urine and plasma using high-performance liquid chromatography. A rapid and sensitive method for the extraction and quantification of penicillin-G and procaine in horse urine and plasma samples has been successfully developed. The method involves the use of solid-phase extraction (SPE) for penicillin-G, liquid-liquid extraction (LLE) for procaine, and high-performance liquid chromatography (HPLC) for the quantification of penicillin-G and procaine. The new method described here has been successfully applied in the pharmacokinetic studies of procaine, penicillin-G and procaine-penicillin-G administrations in the horse.
Expression of inhibin alpha-subunit in horse testis. Inhibin is believed to play roles in the pituitary secretion of FSH and in the paracrine regulation of testicular function. Although it has been generally accepted that inhibin is produced in Sertoli cells, there was a recent evidence for the localization of inhibin in Leydig cells of primates, rat and sheep. However, there is no report on the expression of inhibin in the adult horse testis. Therefore, using immunohistochemistry, western blotting and in situ hybridization techniques, the present study examined inhibin alpha-subunit (Ih-alpha) expression in the adult horse testis. For the detec...
Equilibrium and kinetics of the folding of equine lysozyme studied by circular dichroism spectroscopy. The equilibrium unfolding and the kinetics of unfolding and refolding of equine lysozyme, a Ca2+-binding protein, were studied by means of circular dichroism spectra in the far and near-ultraviolet regions. The transition curves of the guanidine hydrochloride-induced unfolding measured at 230 nm and 292.5 nm, and for the apo and holo forms of the protein have shown that the unfolding is well represented by a three-state mechanism in which the molten globule state is populated as a stable intermediate. The molten globule state of this protein is more stable and more native-like than that of alp...
Evidence for different 5-HT1B/1D receptors mediating vasoconstriction of equine digital arteries and veins. 5-hydroxytryptamine (5-HT) is a potent vasoconstrictor of equine digital arteries and veins which may play a role in the ischaemic disease, laminitis. The present investigation compared the properties of 5-HT1B/1D receptors in arteries with those in veins using isolated rings of equine digital blood vessels. The 5-HT1B/1D receptor-selective agonists, anpirtoline and sumatriptan were 17.9 and 10 times more potent and produced 4.1 and 5.6 times greater maximum contractions, respectively, in veins when compared to arteries. Other agonists tested were of equal potency and produced the same maximum...
Monitoring the conformational flexibility of cytochrome c at low ionic strength by 1H-NMR spectroscopy. Horse heart cytochrome c at pH 7 and low ionic strength is present as two conformers, as evidenced by 1H-NMR spectroscopy. The two structures have been calculated using NOE and pseudocontact shift constraints. They have the same folding patterns and are essentially equal, within the rmsd of the families. The two average structures have rmsd values of 0.049 nm and 0.093 nm for the backbone and the heavy atoms, respectively. Such a difference has been analyzed through a detailed analysis of the NOEs. It appears that the species at low ionic strength differs from the species present at high ionic...
Equine TIMP-1 and TIMP-2: identification, activity and cellular sources. Matrix metalloproteinases (MMPs) are the main enzymes involved in connective tissue turnover. Regulation of MMPs is achieved by controlling production, activation of the pro-enzymes together with the presence of inhibitors, such as, tissue inhibitors of metalloproteinases (TIMPS). The presence of TIMPs in equine synovial fluid was assessed by the ability of the fluid to inhibit equine MMP-9 activity using a gelatin degradation ELISA. The cellular source of the TIMPs was determined using culture supernatants of resident articular cells (chondrocytes and synovial fibroblasts) and invading inflam...
Dextran-70 inhibits equine platelet aggregation induced by PAF but not by other agonists. Dextrans of mean molecular weight 70 kDa (dextran-70) have had clinical use as anti-thrombotics in man. A major part of the anti-thrombotic action is mediated via inhibition of platelet function. Greatorex (1975, 1977) treated thromboembolic colic in horses with infusions of dextran-70 and reported a 90% recovery rate, but this treatment is nonetheless rarely used. We have used an in vitro method to examine the effect of dextran-70 on equine platelet suspensions, in the hope that understanding the mechanism of action of dextran-70 might lead to the development of alternative therapeutic agents...
[Differentiation of domestic horse and Przewalskis horse using various DNA sequences]. The electrophoretic mobility of seven erythrocyte enzymes and spectra of fragments amplified by RAPD-PCR with primers UBC-85 and UBC-126 were comparatively analyzed in domestic horse and Przewalski's horse. All tested genetic markers were classified into two groups differing in their involvement in differentiation of the two closely related horse species. Markers from different groups differed neither in their type (a polymorphic protein or an amplification product) nor in their biochemical role (for enzymes).
