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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.
Partial purification and characterization of rhinoceros gonadotropins, growth hormone, and prolactin: comparison with the horse and sheep. The rhinoceros is an endangered species related to the horse family. Little is known of its reproductive endocrinology. The objectives of this study were to partially purify rhinoceros pituitary hormones, determine which assays could be used for their assessment, and to ascertain whether rhinoceros LH possesses the intrinsic FSH activity of equine LH. A single pituitary each from a White (1.3 g) and a Black (1.2 g) Rhinoceros was homogenized and extracted (pH 9.5), then subjected to pH and salt fractionation, and ion-exchange chromatography (DEAE and Sephadex SP-C50) to yield partially purifie...
In vitro responses of equine digital vessels to dopamine and fenoldopam. The in vitro responses of isolated vascular preparations of digital arteries and veins obtained from healthy anaesthetised horses were determined for dopamine and fenoldopam. The digital vessels were harvested, cut into 4 mm vascular segments, suspended in tissue baths and attached to force-displacement transducers. Dose-response studies between 10(-8) and 10(-4)M concentrations were performed for all drugs. The change in tension of each vascular ring was measured in grams of force. The reactivity between palmar and plantar digital vessels and baseline vascular responses were determined for do...
Changes in luteinizing hormone bioactivity associated with gonadotrophin pulses in the cycling mare. Equine plasma luteinizing hormone (LH) possesses both biological (in vitro bioassay, B) and immunological (radioimmunoassay, I) activities and the ratio of B:I varies with stage of the oestrous cycle. To estimate the contribution made by pituitary secretion and peripheral metabolism to changes in the B:I ratio, pituitary venous effluent and circulating plasma from 5 dioestrous and 2 oestrous mares were analyzed using both an in vitro bioassay and a radioimmunoassay. During dioestrus, LH was released in a pulsatile fashion with a frequency of 1.4 pulses/24 h and a pulse duration of 20-40 min (c...
[The estimation of platelet factor 3 activity in horses, cattle, sheep and pigs by the use of synthetic chromogenic tripeptide substrates]. The aim of this study was to investigate the platelet factor 3 activity in platelet-rich plasma of horse, cattle, sheep and pig, by the use of chromogenic tripeptide substrate H-D-Phenylalanyl-Pipecolyl-Arginyl-p-nitroanilide. Among species examined the highest activity of this factor was stated in pig, the lowest one in sheep. Chromogenic substrate test was 10 times more sensitive that Stypven clotting time test. Thus, the use of chromogenic tripeptide substrate is fully valuable in platelet factor 3 activity estimation in domestic animals.
Influence of pregnancy on diurnal and seasonal changes in glucose level and activity of FDPA, AlAT and AspAT in mares. 1. The diurnal changes in the glucose level and in activity of FDPA, A1AT and AspAT in four pregnant standard-bred mares were studied. 2. As a control four barren mares, were kept and examined in the same conditions. 3. Blood samples were taken every 4 hr for one day, each month, throughout pregnancy, or one year. 4. A diurnal rhythm in activity of A1AT and AspAT in barren mares was found. The pregnancy masked diurnal rhythm in activities of both transaminases. 5. No diurnal rhythm in glucose level and FDPA activity in both groups of mares was observed. 6. Seasonal cyclicity was found in all i...
Galactosyltransferase activity is restricted to the plasma membranes of equine and bovine sperm. beta 1, 4-Galactosyltransferase (GalTase) is localized to the plasma membrane of mouse sperm, in which it mediates the binding of sperm to glycoconjugate residues in the egg zona pellucida. In this study, the presence of subcellular distribution of sperm GalTase were determined in two other mammalian species that yield sufficient sperm for subcellular fractionation. Equine and bovine semen were collected, and the plasma membranes (PM), outer acrosomal membranes (OAM), and inner acrosomal membranes (IAM) were sequentially removed. The purities of the isolated membrane preparations were determin...
Characterization of hydrophobic cores in apomyoglobin: a proton NMR spectroscopy study. A proton nuclear magnetic resonance spectroscopic study of horse apomyoglobin was undertaken in order to define the regions of myoglobin that are and that are not structurally affected by the binding of the prosthetic group. It was found that, in spite of the poor spectral resolution, a number of spin systems could be identified by using standard correlated methods. Four clusters consisting mostly of hydrophobic residues were detected by nuclear Overhauser spectroscopy, two of which involved the tryptophan side chains. Extensive similarities to nuclear Overhauser spectroscopy data collected on...
Haem binding to horse spleen ferritin. Horse spleen ferritin, a spherical protein shell of 24 subunits, contains no haem when extracted. This contrasts with ferritins isolated from bacterial sources which have the capacity to bind up to 24 haem groups [(1990) FEBS Lett. 271, 141-143] via two methionine residues [(1990) Nature 341, 771]. Here it is shown that horse spleen ferritin can bind between 15 and 17 haems per 24 subunits with an apparent association constant of 2.2-3.2 x 10(4) M-1. The strength of haem binding appears to be unaffected either by the presence of the core or by the oxidation state of the haem. The demonstration...
[Reference values for cortisol, T4 and T-uptake in different horse groups using the fluorescence polarization immunoassay (FPIA)]. Reference values for Cortisol, T4 and T-Uptake, determined with the Fluorescence-Polarization-Immunoassays (FPIAs) in blood-plasma of different horse groups were established. The highest Cortisol values were measured in blood samples from thoroughbred racehorses and riding horses taken between 7 and 8 a.m. (181 +/- 37 and 268 +/- 43 nmol/l), the lowest gained between 5 and 6 p.m. (69 +/- 45 and 85 +/- 32 nmol/l respectively). Peak values for T4 in riding horses were found in blood samples collected between 1 and 2 p.m. (28.2 +/- 5.7 nmol/l) followed by the samples taken at 5-6 p.m. and 7-8 a.m...
Preliminary investigation of alterations in blood viscosity, cellular composition, and electrophoresis plasma protein fraction profile after competitive racing activity in Thoroughbred horses. In this preliminary investigation, various hematologic variables potentially influential in determining the degree of blood viscosity were evaluated in 10 Thoroughbred horses subjected to competitive acute running exercise. Following completion of sprints over a distance of 1.25 miles, mean percent (+/- SD) increases in PCV (38.3 +/- 12.9%), RBC (47.8 +/- 15.3%), and rouleaux index (232.7 +/- 176.8%) were recognized. Simultaneous increases in total plasma protein (28.3 +/- 5.31%), serum albumin (26.7 +/- 6.80%), alpha 1-globulin (60.0 +/- 49.0%), alpha 2-globulin (25.5 +/- 27.9%), beta 1-globu...
Maximum velocity of shortening of three fibre types from horse soleus muscle: implications for scaling with body size. 1. To explore how maximum velocity of shortening (Vmax) of fibres varies within one muscle and how Vmax varies with body size, we measured Vmax of muscle fibres from soleus muscle of a large animal, the horse. 2. Vmax was determined by the slack test on skinned single muscle fibres at 15 degrees C during maximal activation (pCa = 5.2). The fibre type was subsequently determined by a combination of single-cell histochemistry and gel electrophoresis of the myosin light chains. 3. Vmax values for the type I, IIA and IIB muscle fibres were 0.33 +/- 0.04 muscle lengths/s (ML/s) (+/- S.E.M., n = 6),...
Bioavailability of ascorbic acid in horses. The bioavailability of ascorbic acid administered to thoroughbreds by intramuscular injection was investigated. For intramuscular injection two preparations were studied, and the percentage bioavailability up to 24 h of 10 g of ascorbic acid was 95% +/- 22 in four horses and 60% in two horses with preparations A and B, respectively. Bioavailability at 24 h in three horses injected subcutaneously with 10 g of preparation B was 82%. Intramuscular injection of both preparations was apparently well tolerated while subcutaneous injection of preparation B (pH 6.0) was associated with marked irritanc...
Immunohistochemical localization of alpha 2-beta 1-glycoprotein in horses. Alpha 2-beta 1-glycoprotein may be found free in horse serum or complexed with alpha-1-proteinase inhibitor to form pre-alpha 2-elastase inhibitor. There has been little information published concerning alpha 2-beta 1-glycoprotein and its possible tissue sources in horses. A peroxidase-antiperoxidase technique was used to identify alpha 2-beta 1-glycoprotein in buffy coat and bone marrow neutrophils of healthy horses. Macrophages and neutrophils in bronchoalveolar lavage samples from clinically normal horses and from horses with chronic pulmonary disease also were positive for alpha 2-beta 1-g...
Biochemical analysis of normal articular cartilage in horses. Articular cartilage specimens from the distal articular surface of 32 radiocarpal bones from 24 2- to 5-year-old horses were analyzed. The total collagen content was determined on the basis of the 4-hydroxyproline content, using a colorimetric method. A method for estimating the proportions of types-I and -II collagen by measuring spectrophotometric densities of specific cyanogen bromide peptide bands from mixtures of types-I and -II collagen on sodium dodecyl sulfate-polyacrylamide gels was used. The cyanogen bromide peptides representative of each collagen types-I and -II were identified. Th...
Equine granulosa-theca cell tumors express inhibin alpha- and beta A-subunit messenger ribonucleic acids and proteins. The association of equine granulosa-theca cell tumors with atrophied contralateral ovaries and abnormal estrous cycles suggests that these tumors produce hormones that affect pituitary gonadotropin production. Because inhibin, a heterodimer protein secreted by granulosa cells, decreases FSH production, we examined the presence of inhibin alpha- and beta A-subunits and their mRNAs in ovarian tumors obtained from three mares. These tumors contained neoplastic cords and nodules, multiple fluid-filled cysts, and a predominance of neoplastic granulosa cells. Reduced proteins from tumor-conditioned ...
Mechanisms of sodium and chloride transport across equine tracheal epithelium. Equine tracheal epithelium, stripped of serosal muscle, mounted in Ussing chambers, and bathed in plasmalike Ringer solution generates a serosa-positive transepithelial potential of 10-22 mV and a short-circuit current (Isc) of 70-200 microA/cm2. Mucosal amiloride (10 microM) causes a 40-60% decrease in Isc and inhibits the net transepithelial Na flux by 95%. Substitution of Cl with gluconate resulted in a 30% decrease in basal Isc. Bicarbonate substitution with 20 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid decreased the Isc by 21%. The Cl-dependent Isc was inhibited by serosal add...
Characterisation of compounds isolated from the sera of horses with acute grass sickness. Isolates were prepared from the sera of 12 horses with acute grass sickness, using methods reported to yield serum fractions associated with neurotoxicity, and their components identified by liquid chromatography and spectroscopy. All isolates were found to contain cortisol and six isolates also contained a degradation product of an analgesic drug, dipyrone. However, no recognised neurotoxin was detected.
Effect of dietary alpha-linolenic acid on equine monocyte procoagulant activity and eicosanoid synthesis. To investigate the effects of an omega-3 fatty acid-enriched ration on the in vitro response of equine monocytes to endotoxin, an 8-week feeding trial was conducted in which linseed oil served as the source of the omega-3 fatty acid, alpha-linolenic acid. One group of horses was fed a control pelleted ration and the other group was fed an 8% linseed oil-enriched pelleted ration. After 8 weeks of feeding, monocytes were isolated and incubated in the presence of Escherichia coli O55:B5 endotoxin for 6 hr. After 8 weeks on the rations, the mean procoagulant activity and thromboxane B2 production ...
Cultivation of tissue from the matrix of the stratum medium of the equine and bovine hoof walls. Explants from the matrix of the stratum medium of the wall of the equine and bovine hoof each were cultured on a microporous membrane, using a standard culture medium. After incubation at 37 C, the outgrowth was a mixture of keratinocytes and fibroblasts, with predominance of the latter. After incubation at 34 C, the keratinocytes dominated, covering the lateral surfaces of the explant as well as the basal surface. Lateral outgrowth of keratinocytes was observed at the borderline of the original epidermis and at the borderline of the explant's contact with the membrane. Epithelial outgrowth fr...
Hordenine: pharmacology, pharmacokinetics and behavioural effects in the horse. Hordenine is an alkaloid occurring naturally in grains, sprouting barley, and certain grasses. It is occasionally found in post race urine samples, and therefore we investigated its pharmacological actions in the horse. Hordenine (2.0 mg/kg bodyweight [bwt]) was administered by rapid intravenous (iv) injection to 10 horses. Typically, dosed horses showed a flehmen response and defecated within 60 secs. All horses showed substantial respiratory distress. Respiratory rates increased about 250 per cent and heart rates were approximately double that of resting values. All animals broke out in a sw...
Hyperkalemic periodic paralysis in horses. Eleven horses (3 mares, 7 stallions, 1 gelding) with clinical and biochemical evidence of hyperkalemic periodic paralysis were studied. Each horse had history of episodic weakness, muscular tremors, or collapse, which lasted for periods of a few minutes to hours. Diagnosis was based on hyperkalemia in association with a spontaneous episode of paralysis or by precipitation of an episode by oral administration of potassium chloride. Clinical and biochemical events were documented during spontaneous and induced episodes of muscular weakness. During episodes, electrocardiographic findings were con...
Identification of a major iodolipid from the horse thyroid gland as 2-iodohexadecanal. The incorporation of iodide into proteins (PBI) and lipids (LBI) of horse thyroid slices was measured in various conditions. Their dependency on the concentration of extracellular iodide was strikingly different. For PBI the relationship was biphasic with a decrease above 10 microM, likely to correspond to the Wolff-Chaikoff effect. On the contrary, LBI increased as a function of iodide concentration up to 100 microM. Methimazole (MMI) inhibited the incorporation of iodide into both LBI and PBI, but higher concentrations of MMI were required to depress LBI as compared to PBI. The inhibition of...
Production of fumonisins by Fusarium moniliforme and Fusarium proliferatum isolates associated with equine leukoencephalomalacia and a pulmonary edema syndrome in swine. Fumonisin B1 (FB1) and FB2 were isolated from corn cultures of both Fusarium moniliforme and Fusarium proliferatum. Respective concentrations in culture materials of FB1 and FB2 ranged from 960 to 2,350 and 120 to 320 micrograms/g for F. moniliforme and from 1,670 to 2,790 and 150 to 320 micrograms/g for F. proliferatum. Thin-layer chromatography, gas chromatography-mass spectroscopy, high-performance liquid chromatography, and liquid secondary ion mass spectroscopy were used for detection. Fumonisins from F. proliferatum have not previously been reported.
Measurement of endotoxic activity in feces of normal horses. Two chromogenic Limulus amebocyte lysate systems were evaluated for the measurement of endotoxic activity in feces of normal horses. Fecal extracts had neither non-specific nor inhibitory effect on the test reaction, and the two systems with different specificity showed equivalent results. Endotoxic activities in feces of healthy horses averaged 5.7 +/- 2.8 microns/g wet weight. Correlation between the endotoxin levels and the fecal microbial flora could not be determined.
Acrosome reaction of stallion spermatozoa evaluated with monoclonal antibody and zona-free hamster eggs. The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 +/- 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up ...
Effect of inositol hexakisphosphate on the spectroscopic properties of the nitric oxide derivative of ferrous horse and bovine hemoglobin. The effect of inositol hexakisphosphate (IHP) on the spectroscopic (EPR and absorbance) properties of the nitric oxide derivative of ferrous horse and bovine hemoglobin (Hb) has been investigated. In the absence of IHP, the nitric oxide derivative of ferrous horse Hb shows spectroscopic properties similar to those of the corresponding derivative of ferrous human Hb that are generally taken as typical of the high affinity state of tetrametric hemoproteins. Similar to human Hb, the addition of IHP to the nitric oxide derivative of ferrous horse Hb induces a transition toward a species characteri...
The use of stable isotopes and gas chromatography/mass spectrometry in the identification of steroid metabolites in the equine. Stable isotope gas chromatography/mass spectrometry has been used successfully in the elucidation of structures of urinary steroid metabolites in the horse and in the identification of metabolites isolated from in vivo perfusion and in vitro incubation studies using equine tissue preparations. Deuterium-labeled steroids, testosterone, dehydroepiandrosterone, and 5-androstene-3 beta,17 beta-diol have been synthesized by base-catalyzed isotope exchange methods and the products characterized by gas chromatography/mass spectrometry. [16,16(-2)H2]Dehydroepiandrosterone (plus radiolabeled dehydroepi...
Quantitative microanalysis of equine synovial fluid glycosaminoglycan concentration. An alcian blue precipitation method for quantifying the hyaluronic acid (HA) and sulphated glycosaminoglycan concentration (SGAG) in solutions containing both compounds was assessed. The assay was found to be rapid and reliable in solutions containing 0 to 200 mg of HA/dl and 50 to 1,000 micrograms of SGAG/dl, and was not affected by the presence of protein, hemoglobin, or methemoglobin in concentrations normally found in synovial fluid. The HA and SGAG concentrations in intercarpal synovial fluid from 13 clinically normal and 11 arthritic horses were evaluated. A relationship was not found be...
Effects of the dam on equine chorionic gonadotropin concentrations during pregnancy. Breeding trials were designed to determine the influence of the mare on serum concentrations of equine chorionic gonadotropin (eCG) from Day 39 to Day 104 of gestation. Sires were ranked according to mean eCG concentrations found in the groups of randomly selected mares to which they were mated in 1983. Mares were ranked according to their mean eCG concentrations on Days 55, 71 and 85 of gestation (Day 0 = mating), in 1983 and 1985. In the 1986 breeding season, mares that had pregnancies characterized by high eCG levels were mated to sires previously associated with low eCG concentration pregn...
Inhibition and recognition studies on the glutathione-binding site of equine liver glutathione S-transferase. Equine liver glutathione S-transferase has been shown to consist of two identical subunits of apparent Mr 25,500 and a pl of 8.9. Kinetic data at pH 6.5 with 1-chloro-2,4-dinitrobenzene as a substrate suggests a random rapid-equilibrium mechanism, which is supported by inhibition studies using glutathione analogues. S-(p-Bromobenzyl)glutathione and the corresponding N alpha-, CGlu- and CGly-substituted derivatives have been found, at pH 6.5, to be linear competitive inhibitors, with respect to GSH, of glutathione transferase. N-Acetylation of S-(p-bromobenzyl)glutathione decreases binding by 1...
