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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.
Influence of azaperone/metomidate anaesthesia on blood biochemistry in the horse. Ponies were anaesthetized by administration of the ataractic, azaperone (0 · 2–0 · 8 mg/kg), in combination with the hypnotic, metomidate (3 · 5 mg/kg). Changes in blood biochemistry were measured during and following the course of action of these drugs. In control experiments, azaperone (0 · 4 and 0 · 8 mg/kg) was administered alone to other ponies. There were no significant changes in blood glucose concentration in either circumstance. Blood lactate and pyruvate concentrations and lactate/pyruvate ratio were not altered significantly by azaperone. However, moderate increases in lactat...
[Preparative isolation of alpha 2-macroglobulin, transferrin, albumin and study of their nonspecific gamma-inhibitory activity]. Profiles of distribution of non-specific gamma-inhibitors of influenza A2/Victoria/35/72 in donkey and horse sera were established by gel chromatography in Sephadex G-200. High and low molecular inhibitors were found in 19S and 4S serum fractions. Highly purified preparations of a2-macroglobulin, transferrine and albumin were isolated by a combination of methods of salt precipitation, gel chromatography on Sephadex G-100, G-200 and ion exchange on DEAE-Sephadex A-50. Heating sera resulted in a considerable increase of the antiviral activity of a2-macroglobulin and transferrine and a reduction ...
Biochemical studies on equine infectious anaemia. A description is given of an outbreak of equine infectious anaemia (E.I.A.) in Campania [at Naples and Aversa (Caserta)]; it was diagnosed by clinical, pathological and serological examinations (Coggins test). Using the serum of 45 horses with E.I.A. and 11 healthy horses (controls), numerous investigations were carried out on: enzymes, intrinsic coagulation factors, lipids and other substances. The results obtained were very interesting and show that in this disease there are significant increases in many enzymes (LDH, LAP, gamma-GT, CPK, PK and ALD) and copper. Insignificant increases were f...
The problem of testing horse kidneys for the presence of antibiotics at meat inspection: how to avoid a false positive reaction. When 33 horse kidneys were tested for the presence of inhibitory substances by the Bacillus subtilis BGA method at pH 8 and the Micrococcus luteus ATCC 9341 method, 24 were positive and 9 negative. The pH of the seeded M. luteus test medium changed from pH 6.6 before incubation to 8.7 after 24 hours incubation at 30 degrees C. When the same 33 kidneys were tested by the B. subtilis BGA method, medium pH 6, and 15 of them also by the M. luteus method using a medium buffered to pH 6, all were negative. The cadmium concentration of the 33 horse kidneys was found to be 70.17 +/- 81.28 mg/kg wet we...
Crystalline 3-phospho-d-glycerate kinase from horse muscle. Phosphoglycerate kinase has been isolated in crystalline form from horse muscle. A convenient isolation procedure is described that yields homogeneous enzyme of specific activity 700 units/mg (30 degrees C). The enzyme is monomeric, and has a molecular weight 47 000. Of the eight cysteine residues in the protein, two react rapidly with Nbs21 with the concomitant loss of the catalytic activity. Since the isolation of phosphoglycerate kinase from yeast (Bücher, 1955) there have been several reports of purification methods yielding enzyme approaching molecular homogeneity, from rabbit muscle (Be...
Detection of immunologically active zones in equine growth hormone. Peptide fragments, obtained from equine growth hormone by cyanogen bromide cleavage and further chemical treatment, were isolated and identified. Their immunological reactivities were tested by hemagglutination and complement fixation methods using rabbit antisera against native hormone. Antigenic determinants were detected in the fragments comprising amino acid sequences 5-72 and 73-123, this last one being predominant. Fragment 124-178 had very low reactivity. Nitration of peptide 73-123 did not modify its immunological properties,but oxidation diminished them. Comparison of the antigenicity...
The influence of hepatic microsomal amidopyrine demethylase activity on halothane hepatotoxicity in the horse. The hepatotoxic effect of oral halothane in the horse is increased by pretreatment with phenobarbitone or DDT but not by chlorpromazine. Phenobarbitone and DDT increase the activity of hepatic amidopyrine N-demethylase but chlorpromazine does not. Carbon disulphide protects the liver of the horse against halothane.
Autoxidation in milk rich in linoleic acid. II. Modification of the initiation system and control of oxidation. Factors contributing to the initiation of lipid oxidation in cow's and mare's milk containing high levels of polyunsaturated fatty acids were studied. Addition of H2O2 just after milking, in slight excess of the stoichiometric amounts required to destroy ascorbic acid, delayed the development of oxidized flavours in cow's milk high in linoleic acid. Hydrogen peroxide treatment followed by the addition of alpha-or gamma-tocopherols prevented lipid oxidation in cow's milk even when 0.1 mg Cu/l milk was added. When used separately in the presence of Cu these treatments were ineffective as was but...
Steady-state enzyme kinetics of the pancreatic ribonucleases from five mannalian species. The kinetic parameters Km, k+2 and k+2/Km of the pancreatic ribonucleases (EC 3.1.4.22) from cow, giraffe, horse, rat and lesser rorqual have been determined, using 2',3'-cyclic cytidine monophosphate and 2',3'-cuclic uridine monophosphate as substrates. No large differences were found between the activities of the five enzymes. The relative differences between the activities of the five enzymes are mainly due to differences in the rates of hydrolysis and not to differences in the affinities for the substrates.
Isolation of kappa-casein-like proteins from milks of various species. Kappa-Casein-like proteins were isolated from the milks of cow, goat, reindeer, horse, rat, and rabbit. When treated with rennin, all of the isolated kappa-casein components yielded para-kappa-casein-like bands on gel electrophoresis. The rate of cleavage of these components with rennin was determined by measuring material soluble in trichloroacetic acid (macropeptide). The curves were characteristic of a limited, specific attack by rennin on these proteins. The goat and reindeer kappa-caseins were nearly as bovine kappa-casein, but the cleavage of horse, rat, and rabbit kappa-casein-like comp...
A comparison of techniques for the quantitative analysis of hyaluronic acid in equine synovial fluid. A comparison of methods of preparing the hyaluronic acid of equine synovial fluid for quantitative spectrophotographic analysis is presented. A new method is proposed which appears superior to the previous methods.
Horse-liver alcohol dehydrogenase and Pseudomonas testosteroni 3(17)beta-hydroxysteroid dehydrogenase transfer epimeric hydrogens from NADH to 17beta-hydroxy-5alpha-androstan-3-one. An exception to one of the Alworth-Bentley rules. In the reduction of 17beta-hydroxy-5alpha-androstan-3-one to the 3beta-alcohol, horse liver alcohol dehydrogenase utilizes the 4-pro-R hydrogen of NADH whereas the 3(17)beta-hydroxysteroid dehydrogenase of Pseudomonas testosteroni utulized the 4-pro-S hydrogen. These observations provide an exception to the rule proposed by Alworth and Bentley that with regard to the paired methylene hydrogens at C-4 of NADH and NADPH "the stereospecificity of a particular reaction is fixed and does not vary with the source of the enzyme preparation". It is also apparent that for these two enzymes, the selecti...
Mefanamic acid blood and urine levels in the horse determined by derivative gas-liquid chromatography-electron capture. Mefenamic acid is extracted from biological fluids and is acylated with pentafluoropropionic anhydride to form a derivative possessing high electron affinity. The derivative is analyzed by gas-liquid chromatography with an electron capture detector. The method is particularly valuable for determining drug levels in blood where small sample and/or drug concentrations are available.
Effects of ovariectomy and season on plasma luteinizing hormone in mares. Six pony mares were ovariectomized (OVX) on day 16 of diestrus during June and July, 1972, to study short term changes in plasma luteinizing hormone (LH) concentrations. Plasma LH was higher (P less than .05) 3 days after OVX (1.76 ng/ml) than the day after OVX (1.01 ng/ml), and a gradual increase occurred over the first 2 weeks. Elevated plasma LH concentrations similar to mid-estrus levels were present from the 2nd to 11th week post-OVX. In another experiment, the same 6 OVX mares were bled once a month from February, 1973, to January, 1974, to study long-term changes in plasma LH in relatio...
Characterization of protein phosphokinase activities in horse thyroid nuclei. The distribution of protein phosphokinase (EC 2.7.1.37) activities has been established in horse thyroid nuclei. The presence of several enzyme activities has been demonstrated, two of which are clearly distinct. The first one acts on histone as substrate and is activated by cyclic AMP. Physico-chemical properties of this nuclear cyclic AMP-dependent histone kinase and of the cytosol histone kinase are different, demonstrating the absence of a contamination from the cytosol. The second enzyme acts on casein as substrate and is not stimulated by cyclic AMP POR CYCLIC GMP. The findings are consi...
Inactivation of horse liver alcohol dehydrogenase by modification of cysteine residue 174 with diazonium-1H-tetrazole. Diazonium-1H-tetrazole was tested as a potential active-site-directed reagent for amino acid residues involved in catalysis by alcohol dehydrogenase. In a novel reaction with a protein, diazonium-1H-tetrazole inactivated the enzyme selectively, and almost stoichiometrically, but reacting with the sulfur of a cysteine residue, Cys-174. As a model compound, the tetrazole adduct of free cysteine was prepared. Elementary and spectral analyses of the adduct were consistent with the structure 5-tetrazoleazo-S-cysteine. The adduct absorbs light with a maximun at 316 nm, and is destroyed by irradiatio...
Effects of training on biochemical values in standardbred horses. Effects of training at a regular, fixed, standard exercise load on venous lactic acid, mixed venous and arterial blood gases and pH, and serum muscle enzymes were determined on previously unconditioned, healthy, adult, Standardbred horses. Arterial and mixed venous blood gases, pH, and serum muscle enzymes did not change in a consistent manner during training. Venous lactic acid concentrations did increase significantly with training and may be of value for the biochemical evaluation of fitness in horses.
Chemical mediators of anaphylaxis (histamine, 5-HT, and SRS-A) released from horse lung and leukocytes in vitro. Horses were sensitized to bovine plasma in Freund's complete adjuvant. Leukocytes, separated from venous blood, yielded histamine upon incubation with bovine plasma. Ioslated lung fragments incubated with bovine plasma liberated histamine and 5-HT, but not SRS-A. Pulmonary veins obtained from the same animals contracted to histamine, 5-HT and to antigen (Schultz-Dale reaction). Histamine and 5-HT probably contribute to immediate-type hypersensitivity in horses whereas the role of SRS-A is not proved.
Some assay restrictions on inferences made from determining hormones in horses, cows, and their fetuses. Often in developing hormone assays, hormones that may interfere with the assay by cross-reaction are not available for testing the validity of the assay. For example, horse TSH was unavailable to test for cross-reaction in an LH radioimmunoassay (RIA). The authors devised an indirect means of accomplishing the same goal, and the evidence from the indirect test of cross-reaction was at least as persuasive as a direct test might have been. Other examples are given of experiments where extensive effort was devoted to validation of steroid RIA, but there were substantial quantitative differences i...
