Enzymes are biological catalysts that facilitate biochemical reactions in horses by lowering the activation energy required for these processes. They are involved in various physiological functions, including digestion, metabolism, and cellular repair. Common enzymes in equine biology include amylase, lipase, and lactate dehydrogenase, each playing a specific role in the breakdown of nutrients and energy production. The activity and concentration of these enzymes can vary in response to different physiological and pathological conditions, serving as potential indicators in veterinary diagnostics. This page compiles peer-reviewed research studies and scholarly articles that explore the function, regulation, and clinical implications of enzymes in equine health.
Anderson MG, Aitken MM.Adrenaline was given intramuscularly to resting horses. It increased heart rate, sweating, blood levels of lactic dehydrogenase, aldolase, creatine kinase, glucose, lactate, free fatty acids and glycerol. Responses to isoprenaline, to noradenaline and to adrenaline after pretreatment with propranolol indicated that beta receptors were involved in stimulation of tachycardia, sweating, lipolysis and muscle glycogenolysis, and alpha receptors in stimulation of liver glycogenolysis and leakage of intracellular enzymes. The time course and relative magnitude of the effects on different enzymes was ...
Rico AG, Braun JP, Benard P, El Hassan AA, Cazieux A.In the horse, gamma-glutamyl transferase (GGT) was found to be mainly located in the kidneys, liver and pancreas. As renal lesions are followed by a urinary escape of enzyme, it can be assumed that if there are raised serum enzyme levels then the source will be chiefly from the liver and pancreas. In the blood, GGT can be measured either in plasma or serum. Its mean level in 58 horses was 12 U/L. This level was not affected by moderate dilution or slight haemolysis and its activity was only slightly decreased by storage at--30 degrees C. The relative hepatic specificity of this enzyme and its ...
Castles JJ, Gershwin ME, Saito W, Ardans A, Osburn B.Previous studies of human congenital immunodeficiency states and in vitro observations of lymphocyte response to mitogens have implicated two purine salvage pathway enzymes, andenosine deaminase (ADA) and nucleoside phosphorylase (NP), as critical in the normal maturation and/or function of the immune system. Based on this information, ADA and NP activities were examined in a variety of congenital and acquired animal models of dysimmunity. The animals studied herein included: congenitally athymic (nude) mice; congenitally asplenic mice; congenitally athymic-asplenic mice; motheaten mice; New Z...
Evenberg A, Meyer H, Verheij HM, de Haas GH.Two phospholipases A2 (EC 3.1.1.4) with different isoelectric points have been isolated from horse pancreas in high yield (880 mg/kg tissue). From pancreatic juice the more acidic species was isolated as the sole phospholipase A2. Upon tryptic activation the zymogens release a hepta- and pentapeptide, respectively from the N-terminal part of the protein giving rise to the formation of one single enzyme with a specific activity higher than that of pancreatic phospholipases A2 from other mammalian species. Horse phospholipase A2 differs from the porcine and bovine enzymes with respect to amino a...
Evenberg A, Meyer H, Gaastra W, Verheij HM, De Haas GH.The complete amino acid sequence of phosphlipase A2 (EC 3.1.1.4) from horse pancreas was determined. The protein controls of a single polypeptide chain of 125 amino acids and has a molecular weight of 13,927. The chain is crosslinked by seven disulfide bridges. The sequence was determined by automated Edman degradation of the intact protein and several of the large peptide fragments. Smaller peptides were analyzed by manual Edman degradation. Fragmentation of the peptide chain was accomplished by enzymatic digestion with trypsin, chymotrypsin, and thermolysin. The final overlap was found by di...
Kang CH, Ferguson-Miller S, Margoliash E.1. The steady state kinetics for the oxidation of ferrocytochrome c by yeast cytochrome c peroxidase are biphasic under most conditions. The same biphasic kinetics were observed for yeast iso-1, yeast iso-2, horse, tuna, and cicada cytochromes c. On changing ionic strength, buffer anions, and pH, the apparent Km values for the initial phase (Km1) varied relatively little while the corresponding apparent maximal velocities varied over a much larger range. 2. The highest apparent Vmax1 for horse cytochrome c is attained at relatively low pH (congruent to 6.0) and low ionic strength (congruent to...
Sakura JD, Rupley JA.Reaction of horse methemoglobin with O-methylisourea at pH 10.2 results in 95% conversion of lysine residues to homoarginine. Analysis of the chymotryptic peptides showed that no single ϵ-amino group was unreactive. Guanidination decreases the dependence of the sedimentation coefficient on hydrogen ion concentration in the range of pH 8 to 11 and did not affect the dependence on protein concentration at pH 7. These results support the conclusion that the lysine side chains involved in subunit contacts have sufficient freedom to accommodate the small changes in bulk and geometry associated wit...
Allen GP, O'Callaghan DJ, Randall CC.Infection of cells with equine herpesvirus type 1 (EHV-1) or type 3 (EHV-3) resulted in the induction of a DNA polymerase activity distinguishable from host cell DNA polymerases by its high salt requirement for maximal activity. By column chromatography on DEAE-cellulose, DNA-cellulose, phosphocellulose, and hydroxyapatite, the EHV-1-induced polymerase was purified 500-fold with 1–2% recovery of total activity from the nuclei of infected hamster livers. The final enzyme preparation was homogeneous as judged by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels. Calculations based ...
Goranov Kh.The alkaline phosphatase enzyme, isolated by Morton's method from leukocytes of sheep, goats, and pigs gave after agarose elctrophoresis two isoenzyme fractions moving to the positive pole at the sites of the alpha 1- and alpha 2-globulins of the blood serum. In bovine leukocytes, besides these two fractions there was a third one that moved more slowly in the zone of the beta-globulins. In horses the alkaline phosphatase of leukocytes produced a wide band within the zones of the beta-globulins and the albumins. It was established that the proportion between the individual isoenzyme fractions o...
Mennella MR, Jones MR.The activity of 5'-nucleotidase (EC 1.3.5), cyclic nucleotide phosphodiesterase (EC 2.1.4.17), non-specific phosphodiesterase (EC 3.1.4.1) and ribonuclease (EC 1.7.7.16)has been investigated in the seminal plasma of whole semen and in the secretions of the seminal vesicle, prostate and epididymis of the bull, boar, ram, stallion, jackass, rabbit and man. Bull seminal plasma showed the highest activity for 5'-nucleotidase, cyclic nucleotide phosphodiesterase and ribonuclease; in contrast, stallion and jackass semen were very poor in these enzymes. Ram, rabbit and boar seminal plasma showed inte...
Hubbard CD, Shoupe TS.A transient phase for the hydrolysis of indophenyl acetate by the commercial preparation of horse serum cholinesterase was observed on a stopped-flow spectrophotometer. It was found that the transient process is a reaction of the ester with a major component of the preparation and is not caused by the serum cholinesterase enzyme. This noncholinesterase component was isolated and the dependence of its concentration and that of the ester upon the transient liberation of the indophenolate ion were determined. Studies with the isolated component and subsequent analyses have led to the tentative id...
Ek N.The Pr protein, which is one of the major equine acidic prealbumins and which consists of a large number of phenotypes, has been studied with regard to its chemical identity. Serum samples of known Pr phenotype which had been treated with varying amounts of bovine trypsin were subjected to starch gel electrophoresis at pH 4.8. When a certain amount of trypsin was used, the Pr protein was markedly affected, whereas the other acidic prealbumins retained their normal electrophoreitic pattern. Extracts from three different regions of the acidic prealbumin field were tested by the casein precipitat...
Rifkind JM, Lauer LD, Chiang SC, Li NC.Oxidation studies of hemoglobin by Cu(II) indicate that for horse hemoglobin, up to a Cu(II)/heme molar ratio of 0.5, all of the Cu(II) added is used to rapidly oxidize the heme. On the other hand, most of the Cu(II) added to human hemoglobin at low Cu(II)/heme molar ratios is unable to oxidize the heme. Only at Cu(II)/heme molar ratios greater than 0.5 does the amount of oxidation per added Cu(II) approach that of horse hemoglobin. At the same time, binding studies indicate that human hemoglobin has an additional binding site involving one copper for every two hemes, which has a higher copper...
Tobin T, Blake JW, Sturma L, Arnett S.Procaine added to whole equine blood or diluted plasma was hydrolyzed with half times of approximately 9 and 12 minutes, respectively, at 37 C. This hydrolytic activity was sensitive to heating and physostigmine, but did not affect procainamide. At pharmacologic concentrations of procaine, the rate of the hydrolytic reaction depended directly on the concentrations of plasma or procaine in the system and was less in whole blood than in plasma. These properties are consistent with hydrolysis being due to plasma esterases operating at less than saturating procaine concentrations. These esterases ...
Kundriutskova LA, Kruglikova RI.Hydrolysis of ethers of saturated and unsaturated alcohols and ethers, e.g. phenol and choline, under the action of horse blood serum cholinesterase, was studied. The reactivity towards enzymatic hydrolysis is decreased due to a greater length of the chain in the alcohol residue of the benzoic acid aminoethers; at nCH2 = 4 the compound is a poor substrate. An increase in nydrophobicity of the acyl residue of the ether molecule also leads to a decrease in the Vmax and Km values. In case of cholinesterase substrates, an increase in the molecule hydrophobicity results in an increase of its non-pr...
Tobin T, Blake JW, Tai CY, Arnett S.Rapid intravenous injection of 1 g of procaine hydrochloride in Thoroughbred mares produced variable signs of central nervous system excitation for as long as 4 minutes. Plasma concentrations of procaine were similarly variable and transient, decreasing with a half-life of approximately 25 minutes. In vitro, plasma from freshly collected equine blood hydrolyzed procaine with a half-life of approximately 7.5 minutes. This hydrolysis was apparently due to plasma esterases. Penicillin, when added free or complexed as procaine-penicillin, did not protect procaine against hydrolysis by these plasma...
Sentsui H, Kono Y.Equine infectious anemia (EIA) virus which was propagated on an equine dermal cell line agglutinated guinea pig erythrocytes. Viral fluids containing about 10(7.5) mean tissue culture infective doses/ml showed hemagglutinating (HA) titers ranging from 16 to 32 units/0.05 ml. Results of cesium chloride equilibrium density gradient centrifugation revealed that the hemagglutinin was inseparable from the virus particles. The hemagglutination reaction persisted over a wide range of temperature and pH, and the absence of divalent cations did not decrease its activity. The HA activity was stable at 4...
Sampaio MU, Galembeck F, Paiva AC, Prado ES.The kinetic constants for horse urinary kallikrein and trypsin hydrolysis of BAEE, TAME, bradykinin methyl ester and bradykinyl-Ser-Val-Gin-Val-Ser were determined. The values of the ratio kcat/Km show that (1) kallikrein is catalytically less efficient than trypsin for all the substrates (2) the three esters are equally good substrates for trypsin while horse urinary kallikrein is 100-fold more effective on bradykinin methyl ester than on the other substrates (3) for both enzymes the ester of bradykinin is a better substrate than the tetradecapeptide.
Sampaio CA, Prado ES.Ala-Phe-Lys-CH2-Cl is a chloromethylketone derivative which is able to promote the inhibition of several proteolytic enzymes. In this paper the inhibition of horse urinary and plasmatic kallikreins is described and this inhibition is compared to that produced in human plasma kallikrein. This compound was designed based upon the structure of bradykinin. This enzyme substrate system can provide a model for the study of the interactions between bradykinin and its receptor. The inhibition of the enzymes was achieved both for its esterase and kinin-releasing activities.
Wilson TM, Morrison HA, Palmer NC, Finley GG, van Dreumel AA.The clinical, macroscopic, and microscopic features of 10 isolated cases of myodegeneration in foals were compared. Low values for selenium and vitamin E content were found in the hay and oats from one breeding stable. Serum selenium concentrations in mares at this stable were also low. Creatinine phosphokinase and serum glutamic oxaloacetic transaminase activities were increased in 2 young foals at this stable; in 1 of these foals, both enzymatic activities were markedly reduced after treatment with vitamin E and selenium. Nutritional myodegeneration was suggested as a diagnosis in this stabl...
Palomba E, Martone F, Meduri A, Vaccaro A, Damiani N.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...
Johnson PE, Maister SG, Knowles JR.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...
Gopinath G, Ford EJ.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.
Mia AS, Koger HD.A direct colorimetric method for the determination of serum arginase activity in various domestic animals is described. Serum arginase activity in healthy mature dogs, cats, horses, cattle, sheep, and pigs ranged from 0 to 14 IU/L. Serum arginase activity increased considerably in these animals during experimental hepatic damage induced by oral administration of carbon tetrachloride.
Delbeke FT, Debackere M.A gas chromatographic method to measure urinary levels of the central nervous system stimulant fencamfamine and some of its metabolites is described. When 100 mg fencamfamine was given orally to four horses the parent drug could not be detected in the urine. After enzymatic hydrolysis of the urine the major human metabolite, N-desethylated fencamfamine, only accounted for 1% of the dose in 12 h. The major equine metabolites were conjugated parahydroxylated compounds representing 18% of the dose. With regard to horse doping control and analysis, the injudicious use of human doping routine metho...
Malmheden Yman I, Sandberg K.Meat from the species horse, donkey and their hybrids, mule/hinny, can be reliably identified by determination of genetic variants of serum albumin by starch gel electrophoresis of meat extracts. Staining of the starch gel for carboxylesterase activity permits differentiation of most horses from donkeys while mules/hinnies cannot be distinguished from horses by their esterase activity alone.
Babel I, Stella RC, Prado ES.Previous experiments indicated that horse urinary kallikrein (UK) hydrolyzes salminei- e and polyarginine, a but not polylysine. This paper reports the action of UK on bradykinyl-serine, methionyllysyl-bradykinin and lysyllysyl-bradykinin.
Skok MV, Denisiuk PV, Komissarenko SV.Glutaraldehyde treatment does not change the absorption of cytochrome c either in the visible or in UV spectra. It brings about the formation of dimers, trimers and high-polymeric forms of cytochrome c and shifts the pI of all cytochrome c isoelectric fractions to more acid pH. Polymerization also results in changes of kinetic parameters of cytochrome c benzidine reaction increasing its affinity to 3,3-diaminobenzidine with a simultaneous decrease in the effectiveness of H2O2 binding. These biochemical changes can be related to immunochemical differences of native and glutaraldehyde-treated cy...
Pasolini MP, Pezzella R, Santoro P, Cocchia N, Greco M, Del Prete C, Della Valle G, Auletta L.Equine exertional rhabdomyolysis (ER) is a well-recognized clinical syndrome affecting racehorses. Prevalence analysis of ER showed that female sex was a significant risk factor. The aim of this research was to evaluate the differences and correlations in the serum activity of muscle enzymes and the stage of the estrous cycle in ER-susceptible and control (C) mares. Serum muscle enzyme activity before and after exercise and sex hormones were analyzed in the two groups of mares. Ten cyclic ER and 10 cyclic C mares were examined weekly for 4 weeks. During diestrus, ER horses had significantly hi...
Stachel CS, Weik HO.Incubation of equine very low density lipoproteins with lipoprotein lipase isolated from horse postheparin plasma resulted in the formation of lipoproteins of a higher density. Lipoproteins isolated after incubation and plasma lipoproteins had a different chemical composition and triacylglycerol fatty acid pattern. In vitro-obtained low density lipoproteins contained substantially more phospholipids and triacylglycerols but significantly less cholesteryl esters than native low density lipoproteins. Comparing the triacylglycerol fatty acid pattern of plasma very low density lipoproteins and in ...
Groman EV, Schultz RM, Engel LL, Orr JC.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...
Bell K.Transferrin, albumin, 6-phosphogluconate dehydrogenase and vitamin D-binding protein polymorphisms were detected in 242 feral and domesticated Australian donkeys by polyacrylamide gel electrophoresis, starch gel electrophoresis, autoradiography, immunoblotting with specific antisera and activity staining. All four TF and two ALB variants were donkey specific while only one of the PGD variants was donkey specific. The two GC variants were electrophoretically identical to the Equus caballus F and S proteins. Available evidence suggested that the TF, ALB, PGD and GC systems are controlled by co-d...
Sogin DC, Plapp BV.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...
Pellegrini A, Von Fellenberg R.A new and probably unique elastase inhibitor of horse serum was identified, purified to homogeneity and called pre-alpha 2-elastase inhibitor of the horse. Electrophoretically it migrated immediately in front of the alpha 2 position. Its molecular weight was 188 000 by pore limit polyacrylamide gel electrophoresis and 225 000 by Sephadex G-200 gel filtration. The inhibitor was composed of at least two non-identical polypeptide chains of Mr 68 400 and 87 600. A banding pattern of restricted heterogeneity focused between pH 4.9 and 5.2 was revealed by isoelectric focusing. Of 13 animal, microbia...
Thomson JR, McPherson EA, Lawson GH, Wooding P, Brown R.The chymotrypsin activity of seven batches of Micropolyspora faeni and of five batches of Aspergillus fumigatus culture extracts, prepared for inhalation challenge in horses, was assayed and was found to range between 0.29 and 1.45 units/mg protein and 0.02 and 0.20 units/mg protein respectively. Horses affected with chronic obstructive pulmonary disease (COPD) were challenged with two batches of each antigen which had different chymotrypsin activities and no significant correlations were found between the degree of response to challenge and the chymotrypsin activity of the antigens. Inhalatio...
McKinney AR, Ridley DD, Suann CJ.The phase I and phase II metabolism of the anabolic steroid methandrostenolone was investigated following oral administration to a standardbred gelding. In the phase I study, metabolites were isolated from the urine by solid-phase extraction, deconjugated by acid catalysed methanolysis and converted to their O-methyloxime trimethylsilyl derivatives. GC-MS analysis indicated the major metabolic processes to be sequential reduction of the A-ring and hydroxylation at C6 and C16. In the phase II study, unconjugated, beta-glucuronidated and sulfated metabolites were fractionated and deconjugated us...
May SA, Hooke RE, Lees P.Interleukin-1 and a casein-degrading enzyme have been identified in an experimental system for studying acute inflammation in the horse. The levels of both the cytokine and the proteinase increased over the first 24 hours following initiation of the inflammatory response, and remained at high levels through to the last sample collected at 48 hours. This is in marked contrast to prostaglandin E2 concentrations which were low initially, peaked at four to eight hours and had returned to low levels by 12 to 24 hours. It is likely that interleukin-1 and various proteinases are involved in the later...
Nishita T, Deutsch HF.Equine muscle carbonic anhydrase (CA-III) behaves like ubiquitin in undergoing extensive acylation of N epsilon-lysine residues upon reacting with p-nitrophenyl esters. The enzyme undergoes extensive carbamoylation of lysine residues when reacted with carbamoyl phosphate. The modification of from 6 to 7 lysine residues results in the production of a series of more anodic electrophoretic components. The derivatization of the lysine residues leads to a marked decrease in the enzyme's ability to hydrate CO2. The equine CA-III possesses both acid and alkaline phosphatase activities in contrast to ...
Ellison RS, Jacobs RM.The main purpose of this study was to ascertain whether isoelectric point determination of alkaline phosphatase (AP) using an isoelectric focusing technique on agarose gels could define the isoenzymes present in healthy equine serum. The isoelectric points of AP extracted from nine tissues ranged from pH 3.5 to 7.5 with all tissues having multiple bands. There was considerable similarity in band pattern among tissues, with only pancreatic and colostral AP having substantially different isoelectric points from the others. Sera contained thirteen bands with isoelectric points ranging from pH 3.5...
Tobin T, Blake JW, Sturma L, Arnett S.Procaine added to whole equine blood or diluted plasma was hydrolyzed with half times of approximately 9 and 12 minutes, respectively, at 37 C. This hydrolytic activity was sensitive to heating and physostigmine, but did not affect procainamide. At pharmacologic concentrations of procaine, the rate of the hydrolytic reaction depended directly on the concentrations of plasma or procaine in the system and was less in whole blood than in plasma. These properties are consistent with hydrolysis being due to plasma esterases operating at less than saturating procaine concentrations. These esterases ...
Nishita T, Anezaki R, Matsunaga K, Orito K, Kasuya T, Sakanoue H, Matsunaga A, Arishima K.Although endoscopy is the definitive diagnostic method for the detection of colonic ulcers, the equipment required for performing the test is costly and difficult to use. Therefore, a simple cost-effective and reliable screening test for intestinal tract bleeding is needed. To this end, we measured carbonic anhydrase isozymes (CA-I and CA-II) originating from erythrocytes by ELISA in order to determine if they could be used as markers of occult blood in feces. For fecal extract preparation, 2 g of feces were mixed with 4 ml of 0.01 M Tris-HCl (pH 8.0) containing 0.01% thimerosal. The concentra...
Lavoie-Lamoureux A, Martin JG, Lavoie JP.Neutrophils are the predominant cells recruited in the airways of horses suffering from heaves. These cells have been shown to express arginase in some species. The metabolism of l-arginine is thought to be involved in chronic inflammation, and airway obstruction and remodeling. The aim of this study was to assess the expression, regulation, activity, and functional role of arginase isoforms in equine neutrophils. Arginase I, arginase II, ornithine decarboxylase (ODC) and ornithine aminotransferase (OAT) expression were assessed in resting and stimulated (IL-4, LPS/fMLP, PMA; 5 and 18 h) blood...
Kaminski M, Metenier L, Sykiotis M, Ryder OA, Demontoy MC.1. Among several species of Equidae only E. przewalskii possesses a serum esterase identical with that of E. caballus. 2. The esterases of Hemionidae differ slightly from that of domestic horse by electrophoretic migration and by antigenic structure. 3. Zebras (grevyi, burchelli) appear devoid of this component but Z. hartmannae possesses an esterase of high enzymatic activity, differing notably from that of horse by electrophoretic and antigenic properties.
Corbin CJ, Legacki EL, Ball BA, Scoggin KE, Stanley SD, Conley AJ.The 5α-reductase enzymes play an important role during male sexual differentiation, and in pregnant females, especially equine species where maintenance relies on 5α-reduced progesterone, 5α-dihydroprogesterone (DHP). Epididymis expresses 5α-reductases but was not studied elaborately in horses. Epididymis from younger and older postpubertal stallions was divided into caput, corpus and cauda and examined for 5α-reductase activity and expression of type 1 and 2 isoforms by quantitative real-time polymerase chain reaction (qPCR). Metabolism of progesterone and testosterone to DHP and dihydro...
Dacre KJ, McAleese SM, Knight P, McGorum BC, Pemberton AD.Mast cell mediators are believed to play a central role in inflammatory lung disorders such as human allergic and occupational asthma. Equine heaves is characterized by reversible neutrophilic airway inflammation and airway obstruction, primarily due to bronchospasm and mucus hypersecretion, following exposure of susceptible horses to organic stable dusts. As such, heaves shares many similarities with human occupational dust-induced asthma and therefore it is proposed that mast cells may also be implicated in the pathogenesis of heaves. Tryptase, a mast cell-specific proteinase, can be used as...
Zervos IA, Lavrentiadou SN, Tsantarliotou MP, Georgiadis MP, Kokolis NA, Taitzoglou IA.Plasminogen activators (PA) are proteolytic enzymes present in the spermatozoa and seminal plasma of various species. They play a role in the binding of the spermatozoon and its penetration through the layers surrounding the oocyte. Plasminogen activator activity (PAA) is modulated by hormones that have a seasonal variation, such as testosterone and melatonin. The present study investigates the seasonal variation of PA activity in sperm extracts and seminal plasma of four farm animal species: boar, buck, bull and stallion. Semen samples were collected every second week during a 12-month period...
Bosken JM, Lehner AF, Hunsucker A, Harkins JD, Woods WE, Karpiesiuk W, Carter WG, Boyles J, Fisher M, Tobin T.Isoxsuprine is routinely recovered from enzymatically-hydrolyzed, post-administration urine samples as parent isoxsuprine in equine forensic science. However, the specific identity of the material in horse urine from which isoxsuprine is recovered has never been established, although it has long been assumed to be a glucuronide conjugate (or conjugates) of isoxsuprine. Using ESI/MS/MS positive mode as an analytical tool, urine samples collected 4-8 h after isoxsuprine administration yielded a major peak at m/z 554 that was absent from control samples and resisted fragmentation to daughter ions...
Mayberry C, Mawson P, Maloney SK.Plasma cholinesterase activity levels of various species may be of interest to toxicologists or pathologists working with chemicals that interfere with the activity of plasma cholinesterase. Methods: We used a pH titration method to measure the plasma cholinesterase activity of six mammalian species. Results: Plasma cholinesterase activity varied up to 50-fold between species: sheep (88 ± 45 nM acetylcholine degraded per ml of test plasma per minute), cattle (94 ± 35), western grey kangaroos (126 ± 92), alpaca (364 ± 70), rats (390 ± 118) and horses (4539 ± 721). Conclusions: We present ...
Albrecht BA, MacLeod JN, Daels PF.At the onset of equine chorionic gonadotrophin (eCG) secretion, eCG stimulates luteal androgen and oestrogen production. Although eCG concentrations increase exponentially from day 37 to day 60 of gestation and eCG is detectable in maternal serum until about day 120-150 of gestation, luteal androgen and oestrogen production peaks between 5 and 10 days after initial exposure to eCG and then decreases gradually. It is not clear how eCG regulates luteal androgen and oestrogen production. In the present study, the steady-state mRNA expression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), cyto...
Watson TD, Burns L, Packard CJ, Shepherd J.Affinity chromatography on heparin sepharose was used to identify 2 lipolytic enzymes in heparinized plasma from horses. One enzyme was typical of hepatic triglyceride lipase (HTGL), because it was resistant to inactivation by high concentrations of NaCl, and it did not require the addition of serum for activity. The other enzyme was identified as lipoprotein lipase (LPL), because of its inactivation at NaCl concentrations in excess of 0.2M, and its dependency on addition of serum as a source of apolipoprotein C-II activator. The enzymes were purified by 347-(HTGL) and 442- (LPL) fold, with yi...
Larsdotter S, Holm L, Dahlborn K, Jansson A, Josefsson M, Ridderstråle Y.Sweat gland morphology and carbonic anhydrase (CA) distribution was studied after exercise in trained and untrained horses using a histochemical technique and light microscopic image analysis. Three trained and 3 untrained Standardbred trotters performed an exercise test (20 min trot at 6 m/s with 5 min walk at 1.8 m/s in the beginning and end) on a high-speed treadmill at 35 degrees C. Skin biopsies were taken before exercise and after trot. The fluid loss after exercise was 10, 12 and 12 g/kg bwt in the untrained horses and 4, 6 and 11 g/kg in the trained. Trained horses had a larger cell ar...
