Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Enzymes
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.
Endocrine and reproductive consequences of certain endotoxin-mediated diseases in farm mammals: a review. After giving an overview of the general pathology of endotoxin-mediated diseases, the authors summarise the endotoxin-induced endocrine changes and their clinical consequences, with particular regard to reproduction. The consequences of temporary activation of the cyclooxygenase-2 and lipoxygenase enzyme systems resulting in elevated release of various prostanoids are discussed in cyclic and pregnant ruminants, sows and mares. The clinical failures attributable to increased glucocorticoid secretion as well as the endotoxin-induced changes in thyroid function and in peripheral level of some oth...
The potential of collagenase as a new therapy for separation of human retained placenta: hydrolytic potency on human, equine and bovine placentae. The purpose of this study was to determine to what degree bacterial collagenase may digest human placentae compared to equine and bovine placentae. Placenta samples from human, equine and bovine were incubated with bacterial collagenase solution at various concentrations. The degree of hydrolysis and collagen breakdown was measured by the release of total proteins and hydroxyproline into the incubation media. Also, whole placentae were injected via umbilical cord arteries with collagenase solution (200 U/ml, 200 ml total volume in human and 1000 ml in equine) and hydrolysis determined chemical...
Triiodothyronine (T3), insulin and characteristics of 5′-monodeiodinase (5′-MD) in mare’s milk from parturition to 21 days post-partum. It is generally accepted that hormones and tissue growth factors are supplied from mother to neonate via mammary secretion. Among the protein hormones, insulin and prolactin are considered as the most important milk components for neonates. The significance of the thyroid hormones, namely triiodothyronine (T3) generated locally by 5'-monodeiodinase (5'-MD) in the mammary tissues, for the mammary gland itself and for suckling neonates is still under consideration. In the present study the activity of the 5'-MD and the concentrations of T3 and insulin in mare's colostrum and milk during the firs...
Characterization of a O-fatty-acylated sulfatide from equine brain. A sulfatide, O-fatty-acylated 3-sulfogalactosylceramide at C6-O on galactoside, was isolated from equine brain and the chemical structure was characterized by proton NMR and MS. The O-acylation site of the acylated sulfatide was determined by the down-field shift of protons attached to a carbon having an O-acyl group in the NMR spectrum and by analysis of a partially methylated derivative before and after acetalization of the intact sulfatide using GC-MS. The O-acyl chain length was determined by GLC, revealing that it exclusively had palmitoyl and stearoyl residues as the major fatty acids. T...
Fusion pore expansion in horse eosinophils is modulated by Ca2+ and protein kinase C via distinct mechanisms. Using the patch-clamp technique, we studied the role of protein phosphorylation and dephosphorylation on the exocytotic fusion of secretory granules with the plasma membrane in horse eosinophils. Phorbol 12-myristate 13-acetate (PMA) had no effect on the amplitude and dynamics of degranulation, indicating that the formation of fusion pores is insensitive to activation of protein kinase C (PKC). Fusion pore expansion, however, was accelerated approximately 2-fold by PMA, and this effect was abolished by staurosporine. Elevating intracellular Ca2+ to 1.5 microM also resulted in a 2-fold accelera...
Inhibition of glutathione S-transferase activity by the quinoid metabolites of equine estrogens. The risk factors for women developing breast and endometrium cancers are all associated with a lifetime of estrogen exposure. Estrogen replacement therapy (ERT) in particular has been correlated with a slight increased cancer risk, although the numerous benefits of ERT may negate this harmful side effect. Equilenin and equilin are equine estrogens which make up between 30% and 45% of the most widely prescribed estrogen replacement formulation, Premarin (Wyeth-Ayerst). In this study we have synthesized the catechol metabolites of equilenin [4-hydroxyequilenin (4-OHEN)] and equilin [4-hydroxyequ...
The activity of mixed function oxidases, estimated by in vivo antipyrine clearance, is similar in horses and camels. The activity of hepatic mixed function oxidases was compared in horses and camels (Camelus dromedarius) by studying the pharmacokinetics of antipyrine in seven camels and five horses following intravenous administration of a single dose of antipyrine (25 mg/kg). The data obtained (mean +/- SEM and median in brackets) in camels and horses, respectively, were as follows: the elimination half-lives were 3.25 +/- 0.23 (3.19) and 3.09 +/- 0.25 (2.90) hr; the apparent volumes of distribution (area method) were 0.691 +/- 0.045 (0.648) and 0.642 +/- 0.034 (0.676) l/kg; the volumes of distribution at s...
Maturation-promoting factor (MPF) and mitogen activated protein kinase (MAPK) expression in relation to oocyte competence for in-vitro maturation in the mare. In the equine species, a large proportion of oocytes fail to complete meiosis during in-vitro culture. The biochemical and molecular basis of this failure is unknown. The meiotic cell cycle is controlled in part by the maturation-promoting factor (MPF) and the mitogen-activated protein kinase (MAPK). In this study, we evaluated the oocyte competence for in-vitro maturation and the expression of MPF components (p34cdc2 and cyclin B) and MAPK after in-vitro culture. The maturation rate was influenced by the culture medium and the physiological stage of the mare at the time of oocyte recovery. We...
Gelatinolytic activity in tracheal epithelial lining fluid and in blood from horses with chronic obstructive pulmonary disease. To determine whether gelatinolytic activity in tracheal epithelial lining fluid (TELF), blood neutrophils, and blood lymphocytes from horses was metalloprotease activity, and to compare, for healthy horses and horses with chronic obstructive pulmonary disease, gelatinolytic activity in neutrophils, lymphocytes, and serum with activity in TELF. Methods: 7 horses with chronic obstructive pulmonary disease (COPD) and 4 healthy control horses. Methods: Neutrophils and lymphocytes were obtained by means of Percoll separation. Zymography was used to detect gelatinolytic activity; EDTA inhibition and...
The interaction of Streptococcus dysgalactiae with plasmin and plasminogen. The activation of plasminogen and the binding of plasmin by bacteria may have many effects which promote infection. The occurrence of such activities in streptococci is well documented; however, these are yet to be demonstrated for S. dysgalactiae. Consequently, the ability of this bacterium to activate mammalian plasminogen and bind either plasmin or its zymogen was investigated. Activation of bovine plasminogen was dependent on both the strain and the growth medium used for cultivation. Eighteen strain were able to activate bovine and ovine plasminogen and some of these also activated plasmi...
Plasma aspartate aminotransferase and creatine kinase activities in thoroughbred racehorses in relation to age, sex, exercise and training. In order to investigate the effect of age, sex and month on the response of plasma aspartate aminotransferase (AST) and creatine kinase (CK) to exercise, blood samples were collected once a month between March and September from a group of 40 2- and 3-year-old (2yo and 3yo) thoroughbred racehorses (kept under the same managemental regimen) at rest before exercise (PRE) and at 2 (2H) and 24 h (24H) post-exercise. The absolute change in activities between the 2H and PRE samples (2H delta) and the 24H and PRE samples (24H delta) was also calculated. Age had a significant effect on all measured an...
Equinins in equine neutrophils: quantification in tracheobronchial secretions as an aid in the diagnosis of chronic pulmonary disease. Equinins are a closely related group of proteins found in equine neutrophil granules. They demonstrate proteinase inhibiting activity restricted to microbial proteinase K and subtilisin, and they also possess antibacterial and antiviral properties. Antiproteinase K activity was measured in tracheobronchial secretions (TBS) of horses with mild (n = 15), moderate (n = 30) and severe (n = 16) chronic pulmonary disease, to determine its usefulness as an indicator of severity of disease and to measure neutrophil content. Determination of proteinase K inhibiting activity was based on a colorimetric ...
Multiple kinetic intermediates accumulate during the unfolding of horse cytochrome c in the oxidized state. The unfolding kinetics of horse cytochrome c in the oxidized state has been studied at 10, 22, and 34 degreesC as a function of guanidine hydrochloride (GdnHCl) concentration. Rapid (millisecond) measurements of far-UV circular dichroism (CD) as well as fluorescence quenching due to tryptophan to heme excitation energy transfer have been used to monitor the unfolding process. At 10 degreesC, the decrease in far-UV CD signal that accompanies unfolding occurs in two phases. The unobservable burst phase is complete within 4 ms, while the slower phase occurs over tens to hundreds of milliseconds. ...
Skeletal muscle glycolytic capacity and phosphofructokinase regulation in horses with polysaccharide storage myopathy. To determine whether polysaccharide storage myopathy (PSSM) in Quarter Horses is attributable to a defect in glycolysis or in the allosteric regulation of phosphofructokinase (PFK) enzyme. Methods: Muscle biopsy specimens were obtained from 6 Quarter Horses with PSSM and 8 Quarter Horse or Thoroughbred control horses. Methods: Maximal activity of glycogenolytic and glycolytic enzymes was determined spectrophotometrically. Maximal activity of PFK was determined for each horse at pH 8.0, and at pH 7.0 when variable concentrations of the activators, fructose 6 phosphate, fructose 2,6 bisphosphate...
Morphologic changes and xanthine oxidase activity in the equine jejunum during low flow ischemia and reperfusion. To determine whether xanthine oxidase and dehydrogenase activities are altered during low flow ischemia and reperfusion of the small intestine of horses. Methods: 5 clinically normal horses without histories of abdominal problems. Methods: With the horse under general anesthesia, a laparotomy was performed and blood flow to a segment of the distal jejunum was reduced to 20% of baseline for 120 minutes and was then reperfused for 120 minutes. Biopsy specimens were obtained before, during, and after ischemia for determination of xanthine oxidase and dehydrogenase activities, and for histologic a...
[Lysozyme activity in the milk of sucking mares during lactation]. It was the aim of this project to investigate the changes of the lysozyme activity in the milk of mares during the lactation period. Further on the influence of race, date of conception and foaling, age and number of lactations on the lysozyme activities in milk was analysed. Milk samples were collected from 44 mares (trotters, warmblood, quarter horses) from eight farms between the 1st and 90th day p. p. The activity of the lysozyme was measured by a turbidometric method. Summarizing the following results are obtained: Lysozyme activities in mare milk of the 1st and 3rd day p. p. were higher ...
Contribution of K+ channels and ouabain-sensitive mechanisms to the endothelium-dependent relaxations of horse penile small arteries. 1. Penile small arteries (effective internal lumen diameter of 300 600 microm) were isolated from the horse corpus cavernosum and mounted in microvascular myographs in order to investigate the mechanisms underlying the endothelium-dependent relaxations to acetylcholine (ACh) and bradykinin (BK). 2. In arteries preconstricted with the thromboxane analogue U46619 (3-30 nM), ACh and BK elicited concentration-dependent relaxations, pD2 and maximal responses being 7.71+/-0.09 and 91+/-1 % (n=23), and 8.80+/-0.07 and 89+/-2% (n=24) for ACh and BK, respectively. These relaxations were abolished by me...
Activation of extracellular matrix metalloproteinases in equine laminitis. Samples of connective tissue obtained from the hoof of six laminitic and eight non-laminitic adult horses were analysed zymographically to investigate whether connective tissue matrix metalloproteinases are activated or induced during laminitis. The activity or matrix metalloproteinases was substantially greater in the tissues from the laminitic horses than in the tissues from the non-laminitic horses. A comparison of the collagenolytic activity in the laminitic and control tissues showed that collagenolytic activities corresponding to the 92 kDa (P < 0.001), 72 kDa (P < 0.01) and 66 kDa (P < ...
[Activities of the enzymes LDH, gamma-GT, GOT, GPT and lactoperoxidase in the milk of breeding mares during the course of lactation]. Milk samples were collected from 44 mares (trotters, warm blood horses, quarter horses) during lactation between the 1st and 90th day p.p. at 20 defined days. The activity of the enzymes LDH, gamma-GT, GOT, GPT and lactoperoxidase was investigated. The aim of this study was to find out the changes of these parameters during lactation and whether an influence of race, conception, date of foaling, age and number of lactations existed on the enzyme activities in mare's milk. The following results were obtained: In mare's milk the LDH-activity was highest (xg = 629 x 1.5 +/- 1 U/l) on the 1st day ...
Cytoplasmic extrusion and the switch from creatine kinase B to M isoform are completed by the commencement of epididymal transport in human and stallion spermatozoa. Although in several species there is a relationship between epididymal sperm transport and fertility, in human in vitro fertilization (IVF), spermatozoa recovered from the caput epididymidis or even the rete testis are fertile. We studied two objective markers of sperm maturity in the sperm of men and stallions: creatine kinase (CK) concentrations, which are a measure of cytoplasmic retention in immature spermatozoa, and the ratio of CK-M and CK-B isoforms (% CK-M/[CK-M + CK-B]), which is proportional to the incidence of mature sperm. The CK markers and the fertilizing function are closely rel...
Determination of butorphanol in horse race urine by immunoassay and gas chromatography-mass spectrometry. An analytical procedure to screen butorphanol in horse race urine using ELISA kits and its confirmation by GC-MS is described. Urine samples (5 ml) were subjected to enzymatic hydrolysis and extracted by solid-phase extraction. The residues were then evaporated, derivatized and injected into the GC-MS system. The ELISA test (20 microl of sample) was able to detect butorphanol up to 104 h after the intramuscular administration of 8 mg of Torbugesic, and the GC-MS method detected the drug up to 24 h in FULL SCAN or 31 h in the SIM mode. Validation of the GC-MS method in the SIM mode using nalbup...
A microtiter plate assay for the determination of uronic acids. The amount of uronic acid residues in samples containing glycosaminoglycans or pectin is an important parameter in the quantitative and structural analysis of these complex carbohydrates. This paper describes a method to determine the content of uronic acids in biological samples, using conventional polystyrene microtiter plates and microtiter plate-reading equipment with standard interference filters (i.e., 540 or 492 nm). This assay is a modification of a commonly used procedure, viz. hydrolysis of uronic acid containing carbohydrate polymers in 80% sulfuric acid containing tetraborate ions ...
Inhibition and inactivation of equine aromatase by steroidal and non-steroidal compounds. A comparison with human aromatase inhibition. In order to approach the detailed structure-function relationships of aromatase, we studied the inhibitory and inactivatory potencies of several steroidal androstenedione analogues (1: 4-hydroxyandrostenedione, 2: 4-acetoxyandrostenedione and 3: 7 alpha-(4'-amino)phenylthio-4-androstene-3, 17-dione) and non-steroidal imidazole derivatives (4: ketoconazole, 5: miconazole and 6: fadrozole) on equine aromatase in placental microsomes, a well established mammalian model. Human placental microsomes and the purified enzyme from equine testis were also used to compare inhibition by 1 and 2. In equine...
Purification and characterization of equine testicular cytochrome P-450 aromatase: comparison with the human enzyme. Cytochrome P-450 aromatase was purified by five chromatographic steps from adult stallion testis. It was first separated from NADPH-cytochrome P-450 reductase (reductase) on omega-aminohexyl-Sepharose 4B then purified to homogeneity on concanavalin A-Sepharose 4B, hydroxyapatite-Sepharose 4B, DEAE-Sepharose CL-6B and on a second hydroxyapatite-Sepharose 4B. On the other hand, purifications of the equine testicular and rat liver reductases, which allowed the reconstitution of aromatase activity in vitro, were achieved for each species in one chromatographic step on an adenosine 2',5'-diphosphat...
Immunolocalization of 3 beta-hydroxysteroid dehydrogenase, cytochrome P450 17 alpha-hydroxylase/17,20-lyase and cytochrome P450 aromatase in the equine corpus luteum of dioestrus and early pregnancy. The onset of equine chorionic gonadotrophin (eCG) secretion in pregnant mares is associated with an increase in luteal androgen and oestrogen production. The luteal cell type(s) responsible for the increased production of androgens and oestrogens has not been identified in the equine corpus luteum. In this study, we examined the pattern of expression of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), cytochrome P450 17 alpha-hydroxylase/17,20-lyase (P450(17 alpha)) and cytochrome P450 aromatase (P450arom) by immunohistochemistry in equine luteal tissue collected during dioestrus (days 7-10; ...
Matrix metalloproteinases 2 and 9 in equine synovial fluids. Matrix metalloproteinases (MMPs) may be important in the destruction of cartilage seen in equine osteoarthritis and may be detectable in synovial fluid. Synovial fluids were obtained from normal equine joints and from joints of horses with aseptic and septic joint diseases. The total MMP gelatinase enzyme activities were measured by gelatin zymography and image analysis of the gels. The bioactivity of gelatinase in synovial fluid was determined by a gelatin degradation ELISA. Potential MMP-2 & MMP-9 monomer enzyme activities were significantly elevated in both septic and aseptic joint dise...
Characterisation of equine matrix metalloproteinase 2 and 9; and identification of the cellular sources of these enzymes in joints. The cellular production by resident articular cells and infiltrating inflammatory cells of the gelatinase matrix metalloproteinases (MMP) was investigated by tissue culture methods and analysis of cell supernatants by gelatin zymography. Peripheral blood neutrophils in short term culture produced MMP-9, as did peripheral blood monocytes in culture. Isolated articular chondrocytes in monolayer culture produced both MMP-2 and MMP-9, although articular cartilage maintained as explant culture produced MMP-2 alone. Synovial fibroblasts grown in monolayer culture produced MMP-2 alone, although synov...
Extraction and quantification of acrosin, beta-N-acetylglucosaminidase, and arylsulfatase-A from equine ejaculated spermatozoa. Acrosin, Arysulfatase A, and beta-N-acetylglucosaminidase are three key enzymes localized within the mammalian acrosome that play a pivotal role in the penetration of the oocyte. The objectives of this study were to compare two methods of enzyme extraction based on the activities of these enzymes from equine spermatozoa. Method A utilized a 0.5 M Tris-maleate buffer containing 0.1% Triton X-100 and Hyamine 2389. Method B used 0.05 M Tris-HCl, 0.05 M MgCl2 in 0.05 M Tris-maleate, followed by 0.05 M Tris-maleate containing 0.1% Triton X-100. Results indicated that acrosin was initially bound in ...
Mechanisms of echinocytosis induced by Crotalus atrox venom. Transient echinocytosis has been reported in association with snake envenomation in humans and dogs. An in vitro model of echinocytosis induced by venom of crotalus atrox (western diamondback rattlesnake) was established to characterize erythrocyte morphologic changes and to investigate potential mechanisms of echinocytic transformation. Erythrocyte morphologic changes produced after the addition of venom to canine, feline, equine, and human blood were characterized by dose-dependent echinocytosis. Type III echinocytosis were consistently induced in vitro at a dose comparable to in vivo enveno...
