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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.
Lack of acid-resistant trypsin inhibitor in mare’s colostrum: short communication. Mare's colostrum was collected and examined for the presence of trypsin inhibitors. It was found to contain a low level of trypsin inhibitor which could be denatured by 2.5% trichloroacetic acid and, therefore, it clearly differs from the acid-resistant colostral inhibitor of Artiodactyla and Carnivora. This finding is exceptional for a species that concentrates IgG in the colostrum and whose newborn absorbs colostral proteins non-selectively by the gut. It appears that the presence of colostral trypsin inhibitor is not essential for the transmission of maternal immunity via the colostrum and ...
Pyrrole detection and the pathologic progression of Cynoglossum officinale (houndstongue) poisoning in horses. Houndstongue (Cynoglossum officinale), a noxious weed that contains pyrrolizidine alkaloids (PAs), infests pastures and fields in the western United States and Europe. The purpose of this study was to develop techniques to better diagnose PA poisoning and describe the progression of gross and microscopic lesions caused by houndstongue intoxication. Six horses were gavaged daily with a suspension of houndstongue containing 5 or 15 mg/kg total PA for 14 days. Two horses were treated similarly with ground alfalfa as controls. Liver biopsy samples and serum biochemical and hematologic values were ...
Relationship of plasma lactate production to cortisol release following completion of different types of sporting events in horses. Fifty-eight healthy horses were studied during five sporting events of various intensities and durations, namely show-jumping (n = 6), cross-country in a three-day event (n = 30), trotting races (n = 7), galloping races (n = 7) and endurance rides (n = 8). Venous blood samples were collected at rest and immediately after exercise and analysed for plasma cortisol (CORT) and lactate (LA) levels. The experimental procedure was the same throughout the investigation so as to permit a reliable comparison between the five types of exercise. The type of event significantly affected both the resting (p...
Expression of major histocompatibility complex antigen and timing of invasion by equine chorionic girdle cells cultured on Matrigel. Chorionic girdle cells are a highly invasive subpopulation of trophoblastic cells of the horse conceptus that adhere to the uterine epithelium and begin to invade the endometrium on Days 34-36 (Day 0 = day of ovulation). Just prior to and during invasion (Days 32-36), chorionic girdle cells express high levels of major histocompatibility complex (MHC) I, but expression of this antigen decreases by Days 40-45 and is lost by Day 55. The mechanisms involved in the control of chorionic girdle cell invasion and altered MHCI expression over time are not known. The objective of this study, therefore,...
Identification of metabolites of azaperone in horse urine. Two metabolites of the tranquilizer azaperone were extracted from alkalinized horse urine after treatment with beta-glucuronidase/sulfatase from limpets (Patella vulgata). The metabolites were identified by a combination of independent chemical synthesis and GC/MS and 1H NMR analysis. The metabolites were identified as 1-(fluorophenyl)-4-[4-(5-hydroxy-2-pyridinyl)-1-piperazinyl]-1-butanol, designated as 5'-hydroxy-azaperol, and 1-(fluorophenyl)-4-[4-(5-hydroxy-2-pyridinyl)-1-piperazinyl]-1-butanone, designated as 5'-hydroxyazaperone. A TLC screening test was developed for detecting both metabo...
Factors affecting the ultrasonic properties of equine digital flexor tendons. The velocity, attenuation and apparent backscattering coefficient of 6-11-MHz ultrasound were measured in three orthogonal directions in equine deep digital flexor (DDF) and superficial digital flexor (SDF) tendons at 0 degree C. Ultrasonic measurements were examined for correlation with tendon water, collagen, DNA and glycosaminoglycans contents, determined by chemical analyses and with structure observed by scanning electron microscopy. The SDF tendon contained more water, more DNA (i.e., more cells), less collagen and less glycosaminoglycans and exhibited lower velocities and attenuations t...
High concentrations of immunoreactive inhibin in the plasma of mares and fetal gonads during the second half of pregnancy. Plasma concentrations of immunoreactive (ir)-inhibin were measured in seven pregnant mares from around Day 140 of gestation to Day 2 after parturition using a heterologous bovine-based radioimmunoassay (RIA). Concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), oestradiol-17 beta, progesterone and relaxin were also measured in the same samples. A marked increase in plasma concentrations of ir-inhibin, FSH and LH occurred between Day 220 and Day 300 of gestation but the concentrations of all three hormones returned to baseline by about Day 320 (three weeks before part...
The vasomotor effects of 5-hydroxytryptamine on equine basilar arteries in vitro. The vasomotor effects of 5-hydroxytryptamine (5-HT) on isolated equine basilar arteries were studied. 5-HT induced contractions of equine basilar arteries in a concentration-dependent manner, with a pEC50 value (with 95% confidence limits) of 7.35 (7.08-7.62). Similar results were obtained with endothelium-denuded basilar arteries. Contractions were not competitively inhibited by the 5-HT2 receptor antagonist ketanserin at low concentrations of 5-HT. Conversely, at high concentrations of 5-HT, contractions were inhibited by ketanserin in a concentration-dependent manner, with a pA2 value of 8....
Rapid and quantitative analysis of bilirubin in equines by high-performance liquid chromatography. Rapid and quantitative analytical methods for bilirubin using high-performance liquid chromatography (HPLC) with UV detection were developed for samples from equines at a meat inspection site. Sharp HPLC peaks for bilirubins, unconjugated bilirubin (UCBL) and conjugated bilirubin (CBL), were obtained using a simple mobile phase of methanol:0.5 M Tris-HCl buffer (65:35, v/v, pH 7.4). A variable wavelength detector set at 450 nm, 0.01 AUFS and a recorder set at 4 cm/min were used for detection. Peaks for UCBL and CBL occurred at 7.1 min and 4.9 min, the lower limits of detection ranged between 0...
The inhibition of adenylate cyclase in equine platelets by collagen and by platelet-activating factor. Equine platelet aggregation was stimulated by collagen fibres or platelet-activating factor. The action of both ligands was blocked by forskolin or prostaglandin E(1) agents which are known to activate adenylate cyclase. Equine platelet membranes were found to contain adenylate cyclase activity which was inhibited in dose-dependent fashion by both collagen and platelet-activating factor. Platelet-activating factor-induced inhibition was antagonised by WEB2086.
Toxicity of Palicourea marcgravii: combined effects of fluoroacetate, N-methyltyramine and 2-methyltetrahydro-beta-carboline. Feeding experiments carried out with cattle and horses could prove the toxic effects of P. marcgravii (Rubiaceae) in all cases. The typical symptoms of "sudden death", however, are observed in ruminants only. This difference could not be explained so far. Apart from fluoroacetate, two more substances also have influence the toxic effects and have been isolated from P. marcgravii for the first time: N-methyltyramine and 2-methyltetrahydro-beta-carboline (2-Me THBC). Structure elucidation of these compounds is mainly accomplished by 1H-NMR, 13C-NMR and MS techniques. Due to the small quantity of...
Biosynthesis and distribution of leucocyte elastase inhibitor. Production of recombinant inhibitor. The horse leucocyte elastase inhibitor (HLEI), present in neutrophils, monocytes and bone marrow cells, is apparently a cytoplasmic protein which is not released from cells even in response to stimulation with lipopolysaccharide, phorbol ester, tumour necrosis factor alpha, interleukin-1 or elastin degradation products. Although no expression of the inhibitor was detected in neutrophils, both monocytes and bone marrow cells were efficient in its synthesis. Using a new expression vector pREST5d, recombinant inhibitor was produced in a large quantity in a soluble form, with a yield of 88 mg per ...
Species differences in the concentration of acetylcholine, a neurotransmitter, in whole blood and plasma. Various concentrations of acetylcholine (ACh) were detected in samples of bovine, goat, horse, porcine, rat and sheep blood and plasma using a specific, sensitive radioimmunoassay. The ACh levels in whole blood in bovine and horse samples were about 40- and ten-fold higher, respectively, than in humans, but levels comparable to those in humans were measured in porcine samples. Goat, rat and sheep samples had lower whole blood ACh concentrations than those of humans. When plasma samples were assayed, the ACh contents of bovine and porcine plasma were found to be about two- to five-fold those of...
Interpretation of equine serum biochemical profile results. A serum biochemical profile is a group of chemical assays that are used to analyze biochemical constituents of serum. Interpretation of the results requires an understanding of what is actually measured by an assay and knowledge of the pathophysiologic conditions that occur in animals. Interpretative information is presented for the following serum analytes: urea, creatinine, glucose, total protein, albumin, globulins, calcium, phosphorus, magnesium, iron, bilirubin, cholesterol, triglyceride, sodium, potassium, chloride, total carbon dioxide content, aspartate transaminase, lactate dehydrogen...
The synthesis of 19-norandrostenedione from dehydroepiandrosterone in equine placenta is inhibited by aromatase inhibitors 4-hydroxyandrostenedione and fadrozole. 19-Norandrostenedione was synthesized in vitro from dehydroepiandrosterone by explants of equine full-term placenta. The synthesis of 19-norandrostenedione was inhibited by two specific aromatase inhibitors, 4-hydroxyandrostenedione and fadrozole.
Glucose and oxygen metabolism in the fetal foal during late gestation. With the use of [U-14C]glucose tracer methodology, the rates of umbilical uptake, utilization, oxidation, and production of glucose were determined in nine chronically catheterized fetal foals in the fed state between 268 and 325 days of gestation (term approximately 335 days). At the same time, the rates of umbilical O2 and lactate uptake were measured in all nine fetuses by Fick principle. The mean fetal rates of umbilical glucose uptake, glucose utilization, and CO2 production from glucose carbon were 36.9 +/- 2.5, 36.4 +/- 1.7, and 117.7 +/- 17.4 mumol.min-1.kg fetal body wt-1, respectivel...
Families of tandemly repeated DNA elements from horse: cloning, nucleotide sequence, and organization. DNA repeats, revealed initially by digestion of horse DNA with restriction enzymes, were cloned and characterized by cross-hybridization studies and nucleotide sequencing. The Sau-like family of tandem repeats contained two classes of repetitive elements with unit repeats of about 80 bp that shared no sequence similarity. Both unit repeats were present, frequently in tandem, in cloned segments of horse DNA of less than 600 bp. Evidence is presented, based on their ladderlike patterns of hybridization to horse DNA and their high level of similarity to published sequences of satellites from equi...
Site-specific proteoglycan characteristics of third carpal articular cartilage in exercised and nonexercised horses. The relevance of site and the influence of exercise on third carpal articular cartilage proteoglycan (PG) were assessed in 16 horses. Six horses were exercised (exercised group) for 30 minutes, 3 times/wk, for 6 weeks. The other 10 horses (nonexercised group) were housed in box stalls for the same 6-week period. At week 6, articular cartilage from the proximal surface of the right third carpal bone was harvested and cultured with radioactive sulfate to label newly synthesized PG. Endogenous PG was measured by use of a uronic acid assay. Newly synthesized and endogenous PG were characterized by...
Effect of coculture with stallion spermatozoa on de novo protein synthesis and secretion by equine oviduct epithelial cells. Adhesion of equine spermatozoa to homologous oviduct epithelial cells (OEC) in vitro results in specific changes in spermatozoa and OEC function. To test the hypothesis that adhesion of spermatozoa affects protein synthesis and secretion by OEC, the following treatment groups were established in culture: OEC with culture medium only; control spermatozoa in culture medium only; OEC in coculture with spermatozoa; and OEC and spermatozoa in coculture, but physically separated by a microporous membrane. The experiment was replicated within each of 4 ejaculates from 3 stallions. De novo protein sec...
Mutations in the equine plasma transferrin and esterase systems. Eleven apparent mutations of the equine plasma transferrin and esterase gene (10 in TF and one in ES) were found in an analysis of approximately 240,000 thoroughbred horses. Eight of the transferrin mutations produced variants not previously recognized in horses. In the two remaining transferrin mutations and the esterase mutation, reduced plasma concentrations of the proteins were demonstrated by immunological techniques and together with the family data indicated the existence of 'null' alleles.
Evidence for endothelium-derived relaxing factor/nitric oxide in equine digital arteries. To test the hypothesis that endothelium-derived nitric oxide modulates vasomotor reactivity in equine digital arteries. Methods: Digital arteries were isolated from adult horses, and their vasodilator properties were examined in an in vitro controlled environment. Methods: Five adult horses (1 gelding, 4 mares) without evidence of hoof or vascular disease were studied. Methods: Arterial rings with or without endothelium were exposed to endothelium-dependent vasodilator drugs in the presence or absence of a pharmacologic inhibitor of the enzyme nitric oxide synthase. Results: Vasodilator effect...
[Histochemical and morphometric study of the fibrillar population in the diaphragm muscle. I. Horse and dog]. By using m-ATPase techniques, under alkaline and acid pre-incubations, as well as metabolic techniques (alpha-MGPDH and NADH-TR), sections from the lumbar and costal portions of diaphragm muscle in horse and dog were analysed. Fibre samples were exposed to image-analysis observations in order to determine the lowest fibre diameter and obtain statistical data. The findings revealed that the lumbar portion of horse diaphragm consists of fibre types I, IIA and IIB; in the costal portion, the fibre type I and IIA were present. In the dog, the lumbar and costal portions consisted of fibre types I, ...
Serial measurement of peripheral oestrogen and progesterone concentrations in oestrous mares to determine optimum mating time and diagnose ovulation. Rapid enzyme-based immunoassays were used to measure concentrations of oestradiol-17 beta and progesterone in daily blood samples recovered throughout oestrus and for a few days after ovulation from 34 Thoroughbred and 8 pony-type maiden, barren and foaling mares. The first detectable fall in oestradiol-17 beta levels occurred in 88% of the mares within the interval -72 to 0 h with respect to ovulation and in 65% of mares within the interval of -48 to 0 h. The results indicated that serial daily hormone assays of this type could, in a high proportion of animals, predict a correct time for a si...
The effect of naloxone administration on the secretion of corticotropin-releasing hormone, arginine vasopressin, and adrenocorticotropin in unperturbed horses. We used our nonsurgical method for collecting equine pituitary venous blood to study the role of endogenous opioids in the basal regulation of the hypothalamo-pituitary-adrenal axis. We gave mares the opioid antagonist, naloxone (NAL), at either a high (0.5 mg/kg i.v. bolus, followed by infusion of 0.25 mg/kg.h; n = 4) or low (0.2 mg/kg i.v. bolus; n = 6) dose rate. Pituitary venous blood was collected continuously, divided into 0.5- or 1-min segments for 15-30 min before and 1 h after the NAL bolus, and assayed for CRH, arginine vasopressin (AVP), and ACTH. The mares tolerated NAL administrat...
Haematological and biochemical changes in horses competing in a 3 Star horse trial and 3-day-event. Haematological and biochemical changes in horses competing in the Endurance Test (Phase T and D) of an advanced Horse Trial (HT, n = 22) and the Endurance Test (Phases A-D) of an advanced (CCI) 3-day-event (TD, n = 11) over a similar course on the same day were studied. Environmental conditions during the event were cool (5.5-11.1 degrees C). Blood samples were collected from the horses in each group the evening prior to the Endurance Test, within 60 s after, and 10 min after, completion of Phase D (cross-country jumping). The following were determined in the blood samples and compared between...
Acid:base and serum biochemistry changes in horses competing at a modified 1 Star 3-day-event. We examined the effects of participation in each of 3 modifications of Day 2 of a 3-day-event on blood and serum variables indicative of hydration, acid:base status and electrolyte homeostasis of horses. Three groups of horses - 8 European (E) horses and 2 groups each of 9 North American horses performed identical Days 1 (dressage) and 3 (stadium jumping) of a 3-day-event. E horses and one group of the North American horses (TD) performed modifications of Day 2 of a 1 Star 3-day-event and the other group of North American horses (HT) performed a Horse Trial on Day 2. Jugular venous blood was c...
Effects of hydrogen peroxide on isolated trachealis muscle of horses. During acute bouts of recurrent airway obstruction (heaves) in horses, neutrophils that are capable of increased production of reactive oxygen species accumulate in the airways. In the study reported here, the effect of hydrogen peroxide (H2O2; 1 microM to 0.1M), one of these reactive oxygen species products, on the responses of isolated trachealis muscle of horses was determined. Before and after incubation with H2O2, contractile responses to acetylcholine, electrical field stimulation (EFS), 127 mM KCl, and relaxation responses to isoproterenol and activation of the nonadrenergic noncholiner...
Protein tyrosine phosphorylation in equine platelets: the effect of stimulation by thrombin and platelet-activating factor (PAF). Protein tyrosine phosphorylation (PTP) in thrombin- and platelet-activating factor (PAF)-stimulated equine platelet activation was investigated in the absence and presence of 2 protein tyrosine kinase inhibitors (PTKIs), methyl 2,5-dihydroxycinnamate (MDHC) and genistein. Washed equine platelets aggregated irreversibly in response to thrombin or PAF in an agonist concentration dependent fashion. MDHC produced an MDHC concentration and time dependent inhibitory effect on rate and extent of thrombin- and PAF-induced aggregations, whereas the effect of genistein on the same parameters was only ge...
Physiological, metabolic and biochemical responses of horses competing in the speed and endurance phase of a CCI*****3-day-event. The present study was undertaken to investigate physiological, metabolic, haematological and biochemical changes in horses competing in the Speed and Endurance test of a Concours Complet International (CCI)*****3-day-event held under FEI rules. A total of 28 horses competing in the Burghley Horse Trials Speed and Endurance test were selected to be monitored: 11 horses in 1993 and 17 horses in 1994. Of the 28 horses selected, 17 completed the Speed and Endurance test and went on to complete the showjumping test. Mean +/- s.d. shade temperature and relative humidity, black globe temperature and ...
