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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.
Sarcoplasmic reticulum responses to repeated sprints are affected by conditioning of horses. Sarcoplasmic reticulum (SR) responses to repeated sprints and to physical conditioning were studied in 10 Quarter Horses. Exercise tests (four repeated sprints on a treadmill) were conducted before and after 12 wk of sprint conditioning. Muscle samples from the middle gluteal muscle were taken before and after each exercise test, and SR vesicles were isolated. Calcium uptake was determined spectrophotometrically using antipyrylazo III, and Ca2+-ATPase activity was determined using an enzyme-linked optical assay. Conditioning increased calcium uptake rate and Ca2+-ATPase activity by 14 and 38%,...
Variability of oxygen radical absorbance capacity (ORAC) in different animal species. The oxygen radical absorbance capacity (ORAC) was measured both in whole (ORAC-T) and deproteinized (ORAC-AS) plasma samples of human, pig, cow, rabbit, dog, cat, sheep, horse, dolphin, turkey, guinea-hen and chicken. In the 12 species, ORAC-T data, expressed as micromoles of peroxyl radicals trapped by 11 of sample, were found scattered between 8,600 and 23,000 micromol/l. The species with the highest ORAC-T values were cat among mammals and chicken among avies. ORAC-AS values ranged between 600 and 2000 micromol/l, with the highest values found in dolphin and sheep among mammals, while chick...
Studies on equine lipid metabolism. 1. A fluorometric method for the measurement of lipolytic activity in isolated adipocytes of rats and horses. A simple and sensitive method for direct and continuous monitoring of free fatty acid (FFA) release, by measuring the pH-sensitive change in relative fluorescence intensity of seminaphthofluorescein (SNAFL-1) is described. The method was designed to use a small number of adipocytes isolated from fat pads of rats and biopsy specimens of horses for the detection of decreasing pH in fat cell suspensions caused by released FFA into the incubation medium. Species specific differences of lipolysis were demonstrated when adipocytes of rats and horses are incubated with stimulators or inhibitors of li...
Purification of two equine pepsinogens by use of high-performance liquid chromatography. To purify and characterize pepsinogens in equine gastric mucosa. Methods: Stomachs collected from 2 healthy horses at necropsy. Methods: After collection, stomachs were placed immediately in ice before storage at -48 C. After slow thawing, the mucosa was scraped off while the tissue was immersed in 0.1M potassium phosphate (pH 7.4) at 4 C, then was homogenized. The filtered extract was subjected to anion-exchange chromatography. Fractions that were found to contain pepsin or pepsinogen were further chromatographed. Individual fractions were tested for pepsinogen or pepsin content by monitoring...
Metoclopramide ameliorates the effects of endotoxin on gastric emptying of acetaminophen in horses. The effect of metoclopramide on gastric emptying of a liquid marker in horses was evaluated by measuring serum concentrations of acetaminophen. Gastric emptying was determined in normal, fasted horses (n = 7), horses given endotoxin intravenously (n = 7), and horses given intravenous metoclopramide plus endotoxin (n = 6). The mean time to reach maximum serum acetaminophen concentration (Tmax), the maximum serum concentration (Cmax), and the area under the serum acetaminophen concentration vs time curve (AUC) were compared among treatment groups. Endotoxin caused a profound delay in gastric emp...
Metmyoglobin/azide: the effect of heme-linked ionizations on the rate of complex formation. The kinetics of formation and dissociation of the horse metmyoglobin/azide complex has been investigated between pH 3.5 and 11.5. The ionic strength dependence of the reaction has been determined at integral pH values between 5 and 10. Hydrazoic acid, HN3, binds to metmyoglobin with a rate constant of (3.8 +/- 1.0) x 10(5) M-1 s-1. Protonation of a group with an apparent pKa of 4.0 +/- 0.3 increases the rate of HN3 binding 6.5-fold to (2.5 +/- 0.8) x 10(6) M-1 s-1. The ionizable group is attributed to the distal histidine, His-64. The azide anion, N-3, binds to metmyoglobin with a rate constan...
Micromechanics of the equine hoof wall: optimizing crack control and material stiffness through modulation of the properties of keratin. Small-scale components of the equine hoof wall were tested to determine their mechanical roles in the morphological hierarchy. Macroscale tensile tests conducted on samples of the inner wall tubules and intertubular material showed a sixfold difference in mean initial stiffnesses (0.47 and 0.08 GPa, respectively), indicating that the inner wall tubules stiffen the wall along its longitudinal axis. The similarity in material properties of tubule and intertubular samples from the mid-wall suggests that tubules in this region offer only minor reinforcement along the longitudinal axis. Microscale ...
Biochemical markers of bone metabolism in draught and warmblood horses. Concentrations of the cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and osteocalcin (OC) have been determined in the serum of one hundred clinically healthy adult Draught or Warmblood horses. The correlation between these two markers has been evaluated and the influence of gender, age and type of horse described. No significant variations were observed between animals of different sex, but a significant inverse correlation (P < 0.0001) with age was observed for both measured parameters. After correction for age, serum levels of OC were found to be lower in Draught [adju...
Immunolocalization of cathepsin B in equine dyschondroplastic articular cartilage. A polyclonal antiserum raised in sheep against human cathepsin B was tested for specificity and cross-reactivity with the horse homologue by SDS-PAGE and Western blotting, prior to being used for immunolocalization of the enzyme in equine articular cartilage. In Western blots, the antiserum recognized the 30 kDa single chain and 25 kDa heavy chain of the mature enzyme in purified bovine cathepsin B, and corresponding bands at 32 and 27 kDa in equine chondrocyte and fibroblast lysates. This antiserum was then used to compare the expression and distribution of cathepsin B in normal and dyschondr...
Organisation of the equine immunoglobulin constant heavy chain genes. II. Equine cgamma genes. The number of immunoglobulin G constant heavy chain genes (cgamma genes) varies broadly among mammalian species, reflecting structural and functional differences between expressed immunoglobulin G (IgG) isotypes and allotypes. Up to now equine IgG isotypes have been defined only at the biochemical and serological level. It is still not clear how many IgG isotypes exist in horses and whether there are any allotypes. Here, we describe the isolation and characterisation of equine cgamma genes. An equine genomic lambda phage library was screened with a human cgamma4 probe. Cross-hybridising equine...
Conformationally restricted carbamate inhibitors of horse serum butyrylcholinesterase. Conformationally restricted carbamate inhibitors, exo-2-norbornyl-N-butylcarbamate (1), endo-2-norbornyl-N-butylcarbamate (2), l-adamantyl-N-butylcarbamate (3), and 2-adamantyl-N-butylcarbamate (4) as active site-directed irreversible inhibitors of horse serum butyrylcholinesterase are investigated for values of the dissociation constant (KI), the carbamylation constant (k2), and the bimolecular rate constant (ki). Compound 1 is the most potent inhibitor of the enzyme and the values of KI and ki are 20 nM and 1.1 x 10(5) M-1sec-1, respectively.
Effect of regular training on the myocardial and plasma concentrations of taurine and alpha-amino acids in thoroughbred horses. Exercise induces significant changes in the free intracellular amino acid pool in skeletal muscle but little is known of whether such changes also occur in cardiac muscle. In this study the effect of regular exercise on the size and the constituents of the free amino acid pool in the hearts and in the plasma of thoroughbred horses was investigated. The total free intracellular amino acid pool in the hearts of control horses was 30.9 +/- 1.2 mumol/g wet weight (n = 6). Glutamine but not taurine was present at the highest concentration (13.5 +/- 0.9 and 7.7 +/- 0.69 mumol/g wet weight for glutam...
Endometrial oxytocin receptor and uterine prostaglandin secretion in mares during the oestrous cycle and early pregnancy. Circulating concentrations of 13,14-dihydro-15-ketoprostaglandin F2 alpha (PGFM) were measured before and after administration of oxytocin and after endometrial biopsy, with or without uterine flushing performed per vaginam, on days 10, 14 and 18 after ovulation in nine pregnant and nine cyclic mares. Concentrations of oxytocin receptor were measured in endometrial biopsy samples. Neither pregnancy status nor time after ovulation affected basal PGFM concentrations. PGFM concentrations were increased after oxytocin administration on each of the days studied in cyclic mares; on day 14 the mean r...
Production of gelatinases and tissue inhibitors of matrix metalloproteinases by equine ovarian stromal cells In vitro. Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) play very important roles in extracellular matrix (ECM) remodeling in ovarian follicle growth and ovulation. Equine follicles are embedded in cortex that is at the center of the ovary, and they must expand/emigrate to the fossa, the only site in the ovary for ovulation. Therefore, equine ovarian stromal cells (EOSC) are probably involved in ECM remodeling during follicle growth. This study examined whether cultured EOSC synthesize gelatinases and TIMPs, molecules essential for ECM remodeling in other systems. Results showed...
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...
