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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.
Effect of conditioning horses with short intervals at high speed on biochemical variables in blood. There is limited published work on the effect of training using intensive and short intervals of exercise to condition horses for racing. Objective: To examine the effect of conditioning horses 1, 2 or 3 x a week using 2 short fast exercise intervals on blood lactate (LA), plasma ammonia (NH3) and urea (urea) as well as creatine kinase (CK) activity. Methods: Thoroughbreds (age 4-5 years) were conditioned at near maximal speed (12-14 m/sec) over 100 m, on 2 occasions separated by a 10 min period at walk, on dirt track (conditioning exercise; CE) during a 6 week conditioning period (CP). The CE...
Effects of short-term training on insulin sensitivity and skeletal muscle glucose metabolism in standardbred horses. Increased insulin sensitivity occurs after a period of exercise training, but the mechanisms underlying this training-associated increase in insulin action have not been investigated. Objective: To examine the effects of short-term endurance training (7 consecutive days) and a subsequent period of inactivity (5 days) on whole body insulin sensitivity and GLUT-4 protein and the activities of glycogen synthase (GS) and hexokinase (HK) in skeletal muscle. It was hypothesised that training would increase insulin sensitivity in association with increased GLUT-4 protein and activities of GS and HK, ...
Is the distribution of selenium and zinc in the sublocations of spermatozoa regulated? In the sperm nuclei, of mammalian species selenium has been found only in the form of sperm nuclei glutathione peroxidase (snGPx) where it is most likely bound to the chromatin of spermatozoa. Over 80% of selenium in sperm is bound to the selenoprotein phospholipid hydroperoxide glutathione peroxidase (PHGPx) in the midpiece of rat sperm. Zinc in sperm is mainly contained in the outer dense fiber (ODF) proteins of the flagella of mammalian spermatozoa. In the sperm nuclei, zinc is predominately located in the chromatin to the protamine proteins. In order to investigate if the insertion of zinc...
Effects of prior exercise on components of insulin signalling in equine skeletal muscle. Exercise is an important stimulus for the regulation of numerous metabolic functions in muscle, but there has been little investigation of the mechanism of exercise-enhanced glucose utilisation. Objective: To examine the effects of exercise on the signalling components Akt and glycogen synthase kinase-3 (GSK3) involved in insulin regulation of glycogen synthase (GS) activity. It was hypothesised that hyperinsulinaemia and prior exercise would alter the extent of Akt phosphorylation and GSK3beta deactivation and increase insulin stimulation of GS activity in skeletal muscle. Methods: Eight Stan...
Assessment of cartilage degradation effects of matrix metalloproteinase-13 in equine cartilage cocultured with synoviocytes. To determine the effects of matrix metalloproteinase (MMP)-13, compared with interleukin (IL)-1alpha, on cartilage matrix molecule gene expression in a coculture system of equine cartilage explants and synoviocytes. Methods: Articular cartilage and synovium specimens harvested from femoropatellar joints of 4 horses, aged 3 to 5 years. Methods: Synoviocytes were isolated and cocultured with cartilage explants. Cultures were treated with human recombinant MMP-13 (1, 25, or 100 ng/mL) or IL-1alpha (0.01, 0.1, 1.0, or 10 ng/mL) for 96 hours, with medium exchange at 48 hours. Cartilage extracts and...
The contribution of heme propionate groups to the conformational dynamics associated with CO photodissociation from horse heart myoglobin. Photoacoustic calorimetry and transient absorption spectroscopy were used to study conformational dynamics associated with CO photodissociation from horse heart myoglobin (Mb) reconstituted with either Fe protoporphyrin IX dimethylester (FePPDME), Fe octaethylporphyrin (FeOEP), or with native Fe protoporphyrin IX (FePPIX). The volume and enthalpy changes associated with the Fe-CO bond dissociation and formation of a transient deoxyMb intermediate for the reconstituted Mbs were found to be similar to those determined for native Mb (DeltaV1 = -2.5+/-0.6 ml mol(-1) and DeltaH1 = 8.1+/-3.0 kcal mo...
The quantification of lipid and protein oxidation in stallion spermatozoa and seminal plasma: seasonal distinctions and correlations with DNA strand breaks, classical seminal parameters and stallion fertility. The goal of this work was to correlate oxidative stress caused by reactive oxygen species (ROS) and DNA damage with classic semen parameters in spermatozoa and seminal plasma of fertile and subfertile stallions. Oxidation was measured in both lipids and proteins, using the thiobarbituric acid reactive species (TBARS) assay and the DNPH carbonyl groups assay, respectively. Sperm DNA damage was monitored using the TUNEL assay. These parameters were monitored in samples obtained during the breeding and the non-breeding seasons. In general, fertile stallions showed better classical semen parameter...
Hypothermic storage of equine isolated hepatocytes. The aim of the study was to establish the optimal methods for hypothermic storage of equine isolated hepatocytes. Viability of equine isolated hepatocytes after hypothermic storage was dependent on the type of storage medium as well as on the cell density in the storage suspension and the preservation period. Hepatocytes stored at 4 degrees C in Hanks' Balanced Salt Solution (HBSS) and Williams' Medium E (WE) for 24 h showed very low viability, numerous cell membrane blebs, very low attachment rate (11.9 +/- 6.5% and 34.8 +/- 19.1%, respectively) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylte...
Classes and crossreactivity of proteinases in the excretory-secretory products of Caenorhabditis elegans. Proteinases released during the in vitro maintenance of asynchronous cultures of the free-living nematode Caenorhabditis elegans were characterized on the basis of subunit composition, fluorogenic substrate specificity, inhibitor sensitivity and pH optima. Cysteine proteinases are present in the excretory-secretory products (ESP) as indicated by the hydrolysis of cathepsin fluorogenic substrates and confirmed by immunoblotting. Serine proteinases were predominant as indicated by substrate gel analysis and inhibitor studies. The presence of metallo-proteinases was also indicated by inhibitor st...
Expression of connexin 43 protein in testes, epididymides and prostates of stallions. Connexin 43 (Cx43) is a ubiquitously distributed gap junction protein in testes and other reproductive tissues. Adjacent cells share ions and small metabolites through intercellular channels, which are present in gap junctions. Previously, Cx43 has not been reported in testes, epididymides and prostates either in healthy stallions or cryptorchid horses. Objective: To demonstrate the expression pattern of Cx43 in the reproductive tissues of stallions and examine whether naturally occurring bilateral cryptorchidism has any influence on distribution and expression of Cx43. Methods: The expression...
Composition, physiochemical properties, nitrogen fraction distribution, and amino acid profile of donkey milk. This study investigated the changes in chemical composition, nitrogen fraction distribution, and AA profile of milk samples obtained during lactation from the Jiangyue breed of donkey in Northwest China. Results showed that donkey milk contained 9.53% total solids, 1.57% protein, 1.16% fat, 6.33% lactose, and 0.4% ash on average, which is more similar to mare and human milk than to the milk of other mammals. Throughout the lactation investigated, pH and density were constant, protein and ash content showed an apparent negative trend (an increase in lactose content during 120 d postpartum, foll...
The primary structure of a low-Mr multiphosphorylated variant of beta-casein in equine milk. Highly phosphorylated casein with a low molecular mass was isolated from Haflinger mare's milk by RP-HPLC. It accounts for 4.0% of the casein content. Its mass was determined by LC-ESI-MS before and after treatment by alkaline phosphatase. The molecular mass found for the apo-form (10,591 +/- 2 Da) is in agreement with its primary structure, which was established by ESI-MS/MS from tryptic peptides. It appeared that this short protein (94 amino acid residues) is an internally truncated form of the full-length equine beta-casein (226 residues). This low-Mr variant of equine beta-casein displays ...
Pharmacokinetics of boldenone and stanozolol and the results of quantification of anabolic and androgenic steroids in race horses and nonrace horses. Anabolic steroids (ABS) boldenone (BL; 1.1 mg/kg) and stanozolol (ST; 0.55 mg/kg) were administered i.m. to horses and the plasma samples collected up to 64 days. Anabolic steroids and androgenic steroids (ANS) in plasma were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The limit of detection of all analytes was 25 pg/mL. The median absorption (t1/2 partial differential) and elimination (t1/2e) half-lives for BL were 8.5 h and 123.0 h, respectively, and the area under the plasma concentration-time curve (AUCho) was 274.8 ng.h/mL. The median t1/2e for ST was 82.1 ...
Detection of testosterone propionate administration in horse hair samples. A sensitive and specific method has been developed to detect semi-quantitatively testosterone in horse hair samples. The method involved a washing step with sodium dodecylsulfate aqueous solution. The mane and tail hair samples (100mg) were dissolved in 1 mL of sodium hydroxide for 15 min at 95 degrees C in the presence of d3-boldenone used as internal standard. The next three steps involved diethyl ether extraction and a solid phase extraction on Isolute C18 (EC) cartridges eluted with methanol. The residue was derivatized by adding 100 microL of acetonitrile and 30 microL of PFPA then incuba...
Oxygen consumption of equine articular chondrocytes: Influence of applied oxygen tension and glucose concentration during culture. We investigated the oxygen (O(2)) uptake of equine articular chondrocytes to assess their reactions to anoxia/re-oxygenation. They were cultured under 5% or 21% gas phase O(2) and at glucose concentrations of 0, 1.0 or 4.5g/L in the culture medium (n=3). Afterwards, the O(2) consumption rate of the chondrocytes was monitored (oxymetry) before and after an anoxia period of 25min. The glucose consumption and lactate release were measured at the end of the re-oxygenation period. The chondrocytes showed a minimal O(2) consumption rate, which was hardly changed by anoxia. Independently from the O(2...
Reorganization of immobilized horse and yeast cytochrome c induced by pH changes or nitric oxide binding. The redox properties of horse and yeast cytochrome c electrostatically immobilized on carboxylic acid-terminated self-assembled monolayers (SAMs) have been determined over a broad pH range (pH 3.5-8) in the absence and presence of nitric oxide. Below pH 6, both proteins exhibit comparable midpoint potentials, coverages, and electron-transfer rate constants, which suggests that they are adsorbed on the SAM in a similar fashion. Above pH 6, a sharp decrease in electron-transfer rate constants is observed for immobilized yeast cytochrome c, which is indicative of a change in the electron tunnelin...
The effect of colic on oxygen extraction in horses. Blood oxygen transport and oxygen extraction were assessed in horses with colic. A gravity score (GS) ranging from 1 to 3 was attributed to each colic case with healthy horses used as controls. Jugular venous and carotid arterial blood samples were collected and concentrations of 2,3-diphosphoglycerate, adenosine triphosphate, inorganic phosphate and chloride were determined. pH and partial pressures of carbon dioxide (PCO(2)), and oxygen (PO(2)) were also measured. Oxygen equilibrium curves (OEC) were constructed under standard conditions and oxygen extraction ratios calculated. Haemoglobin o...
The haemolytic effect of verapamil on erythrocytes exposed to varying osmolarity. The haemolytic effect of verapamil on red blood cells (RBCs) exposed to varying osmolarity was investigated. The experimental approach used a modified red cell haemolysis assay with concentrations of verapamil ranging from 50-1500 microM compared to drug free controls. The time-course of haemolytic effects was also investigated. We also briefly determined the haemolytic effects of verapamil in Ca2+-free conditions (with added EGTA). In conditions representing decreasing osmolarity (dilution from 140-0 mM NaCl) there was a significant increase in erythrocyte haemolysis that was also dependent o...
Desialylation of core type 1 O-glycan in the equine embryonic capsule coincides with immobilization of the conceptus in the uterus. During the second and third weeks of pregnancy, the equine conceptus expands rapidly while it is enclosed within a glycan capsule. Around day 16 of gestation, the conceptus loses its mobility in the uterus by a process termed 'fixation', coinciding with various changes in the capsule. Here, we compared the structure of the carbohydrate moieties expressed by the capsule during pre- and post-fixation periods. The glycan structures were studied by chemical analyses in combination with mass spectrometry. Capsule material from conceptuses collected before fixation (days 13-16) was observed to carry...
The role of mitochondrial reactive oxygen species in pH regulation in articular chondrocytes. To examine the effect of O(2) and the role, and source, of reactive oxygen species (ROS) on pH regulation in articular chondrocytes. Methods: Cartilage from equine metacarpo/tarsophalangeal joints was digested (collagenase) to isolate chondrocytes and loaded with 2',7'-bis-2-(carboxyethyl)-5(6)-carboxylfluorescein, a pH-sensitive fluorophore. O(2) tension was maintained using Eschweiler tonometers and a Wosthoff gas mixer. Cells were exposed to agents which alter ROS levels, mitochondrial inhibitors and/or inhibitors of protein phosphorylation. ROS levels were determined by dichlorofluorescein...
Muc5b and Muc5ac are the major oligomeric mucins in equine airway mucus. Horses frequently suffer from respiratory diseases, which, irrespective of etiology, are often associated with airway mucus accumulation. Studies on human airways have shown that the key structural components of the mucus layer are oligomeric mucins, which can undergo changes of expression and properties in disease. However, there is little information on these gel-forming glycoproteins in horse airways mucus. Therefore, the aims of this study were to isolate equine airways oligomeric mucins, characterize their macromolecular properties, and identify their gene products. To this end, pooled tr...
Helicobacter equorum sp. nov., a urease-negative Helicobacter species isolated from horse faeces. Gram-negative, curved, motile bacteria (strains EqF1T and EqF2) were isolated from faecal samples from two clinically healthy horses. Both strains possessed a single, monopolar, sheathed flagellum and were urease-negative. The novel strains grew at 37 degrees C under microaerobic conditions and were positive for oxidase, catalase and alkaline phosphatase activities. The isolates reduced nitrate to nitrite, but gamma-glutamyl transpeptidase activity was not detected. The novel isolates did not grow at 42 degrees C or on media containing 1 % glycine. They were resistant to cephalotin and nalidix...
Theoretical MRI contrast model for exogenous T2 agents. The rational development of new generations of MRI contrast agents (CAs) requires a scheme for predicting contrast enhancement. Previous contrast predictions have been based largely on empirical results in specific systems. Here we present a general theoretical model for evaluating the minimum concentration of T2 CA required for satisfactory image contrast. This analytic contrast model is applicable to a wide range of T2-type agents and delivery scenarios, and requires only a few readily evaluated parameters. We demonstrated the model by predicting contrast produced by superparamagnetic ferumo...
Protective effect of magnesium and potassium ions on the permeability of the external mitochondrial membrane. The data reported are fully consistent with the well-known observation that exogenous cytochrome c (cyto-c) molecules do not permeate through the outer membrane of mitochondria (MOM) incubated in isotonic medium (250 mM sucrose). Cyto-c is unable to accept electrons from the sulfite/cyto-c oxido-reductase (Sox) present in the intermembrane space, unless mitochondria are solubilized. Mitochondria incubated in a very high hypotonic medium (25 mM sucrose), in contrast to any expectation, continue to be not permeable to added cyto-c even if Sox and adenylate kinase are released into the medium. Th...
Relationships between serum serotonin and serum lipid levels, and aggression in horses. Levels of serum serotonin and serum lipids--triglyceride, total cholesterol, low-density lipoprotein, high-density lipoprotein and very low-density lipoprotein, were determined in normal horses and horses diagnosed with aggression on the basis of a questionnaire survey. Blood serotonin levels in aggressive horses were found to be significantly lower than in non-aggressive horses (P < 0.01), but no association was found with respect to blood lipids.
Equine zona protein synthesis and ZP structure during folliculogenesis, oocyte maturation, and embryogenesis. In the equine, the zona pellucida (ZP) is the major barrier to successful in vitro fertilization. Therefore the aim of our studies was to analyze species-specific features of the equine ZP in regard to structure and glycoprotein ZPB and ZPC expression sites during oocyte development and embryogenesis. The equine ZP revealed high immunological cross-reactivity to porcine ZPB and ZPC. In the ovary, the distribution of ZPB and ZPC was co-localized and correlated with the developmental stage of the follicle. ZPB and ZPC expression started in the oocyte of the late primordial and primary follicle. ...
Interactions responsible for secondary structure formation during folding of equine beta-lactoglobulin. Equine beta-lactoglobulin forms a compact intermediate at an acidic pH (A state). It also forms an expanded and helical conformation at low temperatures (C state). The structure of a single disulfide mutant C66A/C160A is similar to the A state in the presence of salts, while it is similar to the C state at low anion concentrations. We have investigated the temperature-dependent change in the secondary structure using circular dichroism and proline scanning mutagenesis. At low anion concentrations, the helical content increased linearly as temperature decreased. In the presence of salts, the A ...
Proliferative processes within the equine corpus luteum may depend on paracrine progesterone actions. Soon after ovulation, the corpus luteum (CL) starts secreting progesterone (P(4)), a hormone necessary for implantation. The aim of the study was to evaluate whether P(4) exerts an autocrine/paracrine action on luteal angiogenic activity and P(4), prostaglandin E(2) (PGE(2)) and NO production in the mare. Corpora hemorrhagica (CH) and mid-luteal phase CL (MCL) were cultured with (i) no hormone (Control); (ii) P(4); (iii) a P(4) precursor - pregnenolone; or (iv) a P(4) antagonist - onapristone [10(-4) M;10(-5) M; all steroids]. NO production decreased in MCL, with respect to CH, when treated wi...
