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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.
Differential transcription of steroidogenic enzymes in the equine primary corpus luteum during diestrus and early pregnancy. In pregnant mares, eCG stimulates luteal androgen and estrogen production, increasing plasma concentrations 2- to 3-fold. To study how these changes are regulated, we examined the expression of mRNA for the steroidogenic enzymes 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), cytochrome P450 17 alpha-hydroxylase/17,20-lyase (P450 17 alpha), and cytochrome P450 aromatase (P450arom) in equine primary corpora lutea using Northern blot analyses. Three equine specific cDNAs were generated by reverse transcriptase polymerase chain reaction. When compared to human, bovine, and rat sequences, the nu...
Localization of regulatory peptides in the male urogenital apparatus of domestic equidae: a comparative immunohistochemical study in Equus caballus and Equus asinus. An immunohistochemical study was carried out on specimens of testis, excurrent duct including the male accessory glands and urethra in its various tracts in the horse and the donkey, in order to localize nine regulatory peptides. Immunoreactivities were tested by means of Labelled Strept Avidin-Biotin (LSAB) method. The study has shown that Equine male genitalia are supplied by many peptide immunoreactive nerves containing NPY-, VIP-, leu- and met-Enkephalin-, Substance P-, CGRP- and Bombesin/GRP-like peptides, each of them having a characteristic distribution pattern. These neurotransmitters ...
Effect of maturation and aging on the histomorphometric and biochemical characteristics of equine superficial digital flexor tendon. To assess tendon morphology and non-reducible crosslink concentration, and associations of these findings with horse age and previously reported mechanical and ultrasonographic findings. Methods: Superficial digital flexor tendon samples were obtained from 23 horses aged 2 to 23 years. The tendons had undergone ultrasonography and were submitted to biomechanical testing in the physiologic range prior to sample acquisition. Methods: Samples were sectioned in a transverse plane; then dorsal, palmar, central, lateral, and medial regions were evaluated for fascicle cross-sectional area (CSA), sept...
Novel di-O-acetylated GM3s from equine erythrocytes, one containing 4,9-di-O-acetyl-N-glycolylneuraminic acid and another containing 4-O-acetyl-N-glycolylneuraminic acid and 6-O-acetyl-D-galactose. A novel GM3 O-acetylated at C-4 and at C-9 of N-glycolylneuraminic acid (4,9-di-O-Ac GM3), together with a second GM3 O-acetylated at O-4 of the neuraminic acid and O-6 of D-galactose (4,6'-di-O-Ac GM3) were isolated from equine erythrocytes as a mixture in approximate 1:1 ratio. These two major species were chromatographically inseparable. Their structures, especially the positions of the acetoxy group(s), were determined by means of 1D- and 2D-1H NMR and fast atom bombardment-MS as well as by gas chromatography-MS of partially O-methylated O-trimethylsilylated monosaccharides derived from th...
Biochemical changes in the equine capsule following prostaglandin-induced pregnancy failure. The equine embryonic capsule, an acellular covering that envelops the conceptus during the second and third weeks of pregnancy, is composed of mucin-like glycoproteins. Its structure is consistent with a dual role during early pregnancy: protection of the conceptus, and communication between the embryo and the mother. Loss of sialic acid from the capsular glycoproteins at day 16 correlates with the time of "fixation," or loss of conceptus mobility throughout the uterine horns. This study investigated how the structure of the capsule is linked to the maintenance of pregnancy. Six pregnancies, c...
The hemoglobin polymorphism of the Sardinian wild dwarf horse and the oxygen binding properties of the four different horse hemoglobins. A study was made of the Hb phenotype of the Sardinian dwarfhorse (Equus caballus jara), one of the last surviving wild horse species in Europe. Hb haplotypes and their frequencies were found to be similar to those described in the Arabian horse (BI = 0.551, BII = 0.389, A = 0.036, V = 0.015), which suggests possible introduction onto the island from North Africa. The oxygen binding properties of the whole hemolysates and of the four different horse Hbs, separated by ion-exchange chromatography, were considered with regard to the effect of chloride, 2,3-bisphosphoglycerate and lactate. Results ...
Oxidative energy metabolism in equine tendon cells. Hypoxia has been suggested as a possible cause of tissue degeneration and subsequent rupture in equine tendons. To determine whether low oxygen tension is likely to be detrimental to tendon cell function, experiments were designed to investigate oxidative energy metabolism in freshly isolated and cultured equine tendon cells. Freshly isolated tenocytes and cultured fibroblasts possessed activities of the mitochondrial enzyme citrate synthase similar to those of other mammalian cells, with well defined oxidative metabolism. D-[6(-14)C]-glucose oxidation was measurable in both freshly isolated a...
Methods for the isolation, culture and characterisation of equine pulmonary artery endothelial cells. Equine endothelial cells were isolated from the pulmonary artery by enzymatic digestion and grown to confluency. The cells were characterised by positive immunofluorescent staining for von Willebrand factor and NADPH-diaphorase staining for nitric oxide synthase. Measurements of endothelins indicated that there were significant release rates from the cells for up to six hours. Measurements of intracellular calcium concentration showed that the application of bradykinin caused a transient increase in calcium concentration with similar characteristics to those observed in other endothelial cell ...
Nitric oxide production by equine articular cells in vitro. Recent research in several species has suggested nitric oxide (NO) as a mediator of articular cartilage damage and an inhibitor of cartilage matrix neosynthesis. This study investigated NO production by cultured equine articular chondrocytes in response to 2 arthritogenic molecules, namely lipopolysaccharide (LPS) and interleukin-1 beta (IL-1 beta), and compared NO production by cultured equine synoviocytes stimulated with LPS. Synoviocytes exhibited a low basal level of NO synthesis (measured as nitrite, a NO metabolite) that was neither significantly increased nor decreased by exposure to LP...
Antibody directed against plasma membrane components of equine spermatozoa inhibits adhesion of spermatozoa to oviduct epithelial cells in vitro. Before fertilization, equine spermatozoa adhere to oviduct epithelial cells (OEC) of the mare. The biochemical basis for this adhesion has not been determined. Our objective was to produce an antiserum to block this interaction. Ejaculated spermatozoa were subjected to nitrogen cavitation and spermatozoal plasma membranes enriched by sucrose density gradient centrifugation; membrane enrichment was confirmed by comparative alkaline phosphatase analysis, electron microscopy, and one- and two-dimensional PAGE. Periacrosomal plasma membrane was used as an immunogen for the production of an antiser...
Fumonisins – Importance and occurence of a new group of mycotoxins. This paper describes the importance of fumonisins for human beings and animals and shows data for the occurence in food. Corn-based food samples (n = 299) purchased in the area of munich were analyzed for fumonisin content using an enzyme immunoassay.Fumonisins are mycotoxins produced byFusarium species, especially byFusarium moniliforme andFusarium proliferatum. Occurrence of fumonisins in corn and in cornbased foods and feeds has been reported from almost all over the world. In several animal species different diseases are traced back to fumonisin toxicosis. Fumonisin levels of 5-10 ppm inho...
Patterns of secretion of GnRH, LH and FSH during the postovulatory period in mares: mechanisms prolonging the LH surge. To study the mechanisms responsible for the unusually slow decline of the ovulatory LH surge in mares, secretion patterns of GnRH, LH and FSH were monitored in pituitary venous blood collected every 2 or 5 min for 10.5-18.0 h from five mares on the third (n = 4) or fifth day after ovulation (first sampling period). To determine the effectiveness of progesterone negative feedback, mares were then given a luteolytic dose of a prostaglandin analogue (PGF2 alpha) and pituitary venous sampling (every 2 or 5 min for 16 h) recommenced 20-22 h later (second sampling period). During the declining arm o...
Effect of feeding and feed deprivation on plasma concentrations of prolactin, insulin, growth hormone, and metabolites in horses. Two experiments were conducted to determine 1) the prolactin response to different kinds of feedstuffs in stallions and 2) the effects of total feed deprivation on prolactin secretion in mares and its interaction with the prolactin response to feeding. Experiment 1 was performed with stallions as a 6 x 6 Latin square: A) no feed; B) pelleted feed fed to meet 82.5% of the horses' CP requirements; C) pelleted feed at 25% of the amount in B; D) pelleted feed as in B plus water ad libitum; E) cracked corn at the weight in B; and F) chopped alfalfa at the weight in B. The positive prolactin respons...
A developmental switch in expression from blastocyst to endometrial/placental-type cytochrome P450 aromatase genes in the pig and horse. Pig blastocysts exhibit a transient period of estrogen production at periimplantation, with a second, more sustained period of estrogen synthesis occurring in endometrium and placenta at later pregnancy. Previously we reported the isolation of cDNA clones encoding a novel isoform of cytochrome P450 aromatase (the terminal enzyme in the estrogen biosynthetic pathway) from porcine periimplantation blastocysts. The present study investigated pregnancy-associated expression, in blastocysts and maternal reproductive tract tissues of this and an additional mRNA transcript encoding a distinct P450 ar...
Serum thyroid hormone concentrations in New Zealand horses. Total thyroxine and total tri-iodothyronine concentrations were measured in the sera from 125 horses of mixed age, breed and sex, and varied clinical histories. While low serum thyroxine concentrations were detected in 35 horses, the majority of those horses had serum thyroxine values within the reference range when retested. Only one horse had a mildly decreased serum tri-iodothyronine concentration. Those horses in which the serum thyroxine concentration was low when retested had a normal thyrotropin releasing hormone stimulation test. Hypothyroidism was not diagnosed in any horses in this s...
Erythrocyte glutathione-S-transferase activity in animal species. This study was conducted to determine and compare the activities of glutathione-S-transferase (GST) in red blood cells of cattle, horses, pigs, goats, dogs, rabbits, rats and mice. The highest GST activity was found in mouse red blood cells followed by that of rats, dogs, cattle, pigs, goats and horses with the lowest activity in rabbits. There were significant differences between the GST activities from these various species. The species differences in GST activities correlate with the reported variable responses of the different species to different toxicants since erythrocyte GST plays a si...
Consideration of the optimum pH for the analysis of serum p-phenylenediamine oxidase activity in thoroughbred horses. The optimum pH for the measurement of serum p-phenylenediamine oxidase (Ox) activity was given (pH 6.6), and the relationship between serum ceruloplasmin (Cp) concentration and its Ox activity was established in healthy adult horses. In adult horses, serum antigenic Cp concentrations were measured by the single radial immunodiffusion (SRID) method with the affinity-purified antibody to equine plasma Cp and compared with its Ox activity. Efficient co-relation between Cp concentration and Ox activity in the sera (r = 0.93) and its Ox/Cp ratio were given. These results might contribute to the cal...
A comparison of the lipolytic and anticoagulative properties of heparin and pentosan polysulphate in the thoroughbred horse. The aim of the study was to develop a model for the pre-exercise elevation of plasma free fatty acids in the horse, with a view to its future use in investigations of fat metabolism during exercise. A comparison of the lipase releasing and anticoagulative effects of heparin and a related substance pentosan polysulphate was investigated. Furthermore, the ability of heparin and pentosan polysulphate to affect an increase in plasma free fatty acid concentration, when co-administered with-a triglyceride emulsion, was quantified. Doses of 0.39 and 1.3 mg kg-1 body wt of heparin and pentosan polysul...
Pharmacokinetics of intravenous and oral prethcamide in horses. The respiratory stimulant prethcamide is a mixture of equal parts of crotethamide and cropropamide. A specific and sensitive gas chromatographic method for the determination of crotethamide and cropropamide in horse plasma and urine is described. Both components of prethcamide were extracted from plasma and urine into dichloromethane. The extracts were analyzed by capillary gas chromatography with thermionic detection in the nitrogen-specific detection mode. The lower limits of quantitation were 4.0 ng ml-1 of plasma and 10.0 ng ml-1 of urine. Calibration curves were linear from 2.0-100 ng ml-...
Skeletal muscle characteristics and metabolic response to exercise in young standardbreds. To determine whether performance capacity in a group of young trained Standardbreds is related to skeletal muscle characteristics and metabolic response to exercise. Methods: 13 clinically normal 2-year-old Standardbreds. Methods: Venous blood and middle gluteal muscle biopsy samples were obtained from each horse within 1 to 2 minutes after trotting at high speed for 1,600 m. Results: There was a positive correlation between plasma lactate and muscle glucose-6-phosphate (G-6-P) concentrations and trotting speed. There was a negative correlation between muscle adenosine triphosphate concentrati...
[Characterization of Rhodococcus equi isolates from horse and man]. In the present investigation 19 and 22 R. equi-cultures isolated from diseased horses and humans, respectively, could be correctly identified by their morphological, biochemical and serological properties. The rod-coccus life cycle appeared to be a common feature of almost all cultures investigated. The cultures were typeable with the typing system described by Prescott (1981). The predominant serotypes among the R. equi-isolates belonged to serotypes 1 and 2. Among the R. equi-isolates from horses haemagglutination-positive cultures were mainly found among isolates of serotype 1, those of ser...
Quantitative ionspray liquid chromatographic/tandem mass spectrometric determination of reserpine in equine plasma. A method based on ionspray liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed for the determination of reserpine in equine plasma. A comparison was made of the isolation of reserpine from plasma by liquid-liquid extraction and by solid-phase extraction. A structural analog, rescinnamine, was used as the internal standard. The reconstituted extracts were analyzed by ionspray LC/MS/MS in the selected reaction monitoring (SRM) mode. The calibration graph for reserpine extracted from equine plasma obtained using liquid-liquid extraction was linear from 10 to 5000 pg ml-1 and t...
Subjecting horse spermatozoa to hypoosmotic incubation: effects of ouabain. Although hypoosmotic tests are widely used to assess spermatozoal quality in different species, they have not been used extensively in the stallion. Moreover, the role of the Na (+)K (+), ouabain sensitive-ATP-ase in the response of equine sperm to hypoosmotic shock is not well understood. This study tests two hypotheses: 1) that equine spermatozoa will respond to a hypoosmotic medium by swelling of the tail, and 2) that addition of ouabain will increase the percentage of swollen sperm tails. Ejaculates from 3 stallions were collected with an artificial vagina and diluted in Kenney's medium (T...
The influence of progesterone-induced proteins on glucose metabolism in early equine embryos. The influence of different maternal plasma progesterone concentrations on embryonic glucose metabolism was studied. Uterine flushes were obtained after treating ovariectomized mares (n = 3) with 0 (control), 100 or 200 mg progesterone daily for 7 d. A group of progesterone-induced proteins (PIP) of Mr approximately 20,000 were identified in flushes from progesterone treatments by SDS-PAGE but were not observed in control flushes. Progesterone-induced proteins were removed from half the pooled flush in each treatment group by Sepharose blue CL-6B. In a 3 x 2 factorial (progesterone treatments, ...
Production of free estrogens and estrogen conjugates by the preimplantation equine embryo. In vitro production of free estrogens and estrogen conjugates by intact Day 12.5, 13.5 and 14.5 equine embryos was measured at 2-h intervals over a 24-h culture period. Production of free estrogens was higher for Day 14.5 than Day 12.5 embryos. Differences in production of conjugated estrogens were not significant, but a trend toward increased production with increased age of embryo was apparent. No trend toward increased free and conjugated estrogen production per cell was observed with age. Embryo diameter and number of cells increased with age but varied considerably within groups. The amou...
1H-NMR study of inter-segmental hydrogen bonds in sperm whale and horse apomyoglobins. NMR signals for HisB5 N(delta)H and HisEF5 N(epsilon)H protons of sperm whale and horse apomyoglobins were assigned and compared with the corresponding signals of the holoproteins in terms of pH and temperature dependence behaviors of their shifts and line widths in order to gain insight into structural difference between the apoproteins and the holoproteins. Since these protons are involved in internal hydrogen bonds at the interfaces between the B helix and the GH corner and between the EF corner and the H helix, local structures of the interfaces in these proteins have been inferred from th...
High-performance liquid chromatographic determination of N-alpha-acetyl-L-carnosine in equine plasma. N-alpha-Acetyl-L-carnosine (NAcCAR) in perchloric acid extracts of equine plasma was assayed by high-performance liquid chromatography on a 3 microns Hypersil ODS (150 x 4.6 mm I.D.) column eluted with 5 mM phosphoric acid-1 mM triethylamine, pH 2.58. NAcCAR was isolated by solid-phase extraction on Isolute PRS (propylsulphonyl) columns. The HPLC mean retention time for NAcCAR was 5.9 +/- 0.2 min. The recovery from plasma by solid-phase extraction was 93.9-99.7% and lower limit of detection in plasma was 0.18 microM. The normal NAcCAR concentration in equine plasma was 2.4 +/- 0.3 microM. The ...
High-performance liquid chromatographic determination of imidazole dipeptides, histidine, 1-methylhistidine and 3-methylhistidine in equine and camel muscle and individual muscle fibres. The combined solid-phase extraction (Isolute PRS columns) and reversed-phase gradient HPLC method presented provides a sensitive, reproducible and selective quantification of carnosine, balenine, homocarnosine, histidine, 1-methylhistidine and 3-methylhistidine in equine and camel muscle and individual muscle fibres. Recoveries were 91-115%. Lower limits of detection were 0.005-0.010 mmol kg-1 dry muscle. The compounds were isolated from other physiological amino acids and small peptides and resolved within a single chromatographic run of 55 min. Concentrations of these compounds in equine myo...
Dose-response of X-irradiated human and equine lymphocytes. We have investigated and compared DNA damage and cell killing induced in human and equine lymphocytes after in vitro X-irradiation. Our data show that the cytogenetic and the lethality effects are both greater in equine lymphocytes, but that the difference is wider for lethality. The ratios between doses inducing the same effect are 1.3, 1.7 and 9.4 for the number of binucleated cells with micronuclei, micronucleus frequency in binucleated cells and DNA synthesis inhibition, respectively. The very different radiosensitivity observed for the two mammalian species encourages us to use their lymp...
Total cholinesterase activity in discrete brain regions and retina of normal horses. The research evaluates cholinesterase activity across different brain regions in horses to better understand its role in neuromuscular function and how it can be affected by certain toxic exposures. Cholinesterase […]
