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  • Author or Editor: Elizabeth G. Welles x
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SUMMARY

A functional assay for equine plasminogen was established, using urokinase as the activator, a synthetic chromogenic substrate, a computer-assisted centrifugal analyzer, and acidified/neutralized plasma. One documented effect of plasma acidification appears to be inactivation of alpha-2-antiplasmin. Intra- and interassay precision testing yielded coefficients of variation of 4.1% (n = 10) and 5.6% (n = 26), respectively. Plasminogen was stable in equine plasma stored up to 1 week at 4 C and up to 5 months at − 70 C. Plasminogen in nonacidified equine plasma was not activated by urokinase, streptokinase, tissue plasminogen activator, or tissue plasminogen activator plus soluble fibrin. Streptokinase also failed to activate plasminogen in acidified/neutralized equine plasma.

Free access
in American Journal of Veterinary Research

Summary

Cerebrospinal fluid and serum were obtained from 16 clinically normal adult cows (11 dairy, 5 beef). Sodium, potassium, magnesium, total protein, and albumin concentrations, osmolality, and lactate dehydrogenase and creatine kinase activities, were quantified in csf and serum. Total and differential cell counting, protein electrophoresis, and IgG quantification were performed on csf. Statistical analyses of these variables, including mean, sem, range, and 95% confidence intervals, were performed. Effects of blood contamination were evaluated, and were found to be negligible for all measured constituents. Correction factors for csf creatine kinase and lactate dehydrogenase activities accounting for cellular contamination were developed.

Total nucleated cell count was similar to counts in csf of other species, but higher than values in healthy people. Differential leukocyte count in csf was similar to that reported in csf of other domestic animals: mostly lymphocytes, fewer monocytoid cells, and scant neutrophils.

Cerebrospinal fluid protein concentration was higher than concentration reported for dogs, goats, and people, but was similar to values reported for horses. Beef cows had higher csf total protein concentration than did dairy cows; also, beef cows had higher csf γ-globulin concentration.

The concentration of sodium in csf was slightly higher than the value in serum, and potassium concentration was lower than the value in serum. In contrast to studies of human beings, csf osmolality was generally less than serum osmolality in the cows studied. Reference values for csf electrolyte concentrations and osmolality are useful for diagnosis of salt poisoning and for assessment of the effects of fluid therapy. Magnesium concentration was lower in csf, compared with serum. Reference values may be useful for diagnosis of grass tetany.

Glucose concentration in csf was variable, compared with serum concentration; sometimes, it was similar, lower, or even higher than serum glucose concentration. This variation reflects a more complete equilibration of glucose between csf and blood, owing to the lower and more stable blood glucose concentration in cows.

Creatine kinase activity in csf was markedly less than, and was not correlated with, serum creatine kinase activity. Cerebrospinal fluid lactate dehydrogenase activity was markedly lower than serum lactate dehydrogenase activity. Compared with lactate dehydrogenase, creatine kinase activity had a wider range in these healthy cows; therefore, the former enzyme has higher specificity and sensitivity for diagnosis of diseases affecting the cns.

Free access
in American Journal of Veterinary Research

Summary

Hemostasis was evaluated in cows with experimentally induced endotoxemia and mastitis, caused by intramammary infusion of endotoxin (1 mg) derived from Escherichia coli. Hemostatic tests included prothrombin time; activated partial thromboplastin time; thrombin time; fibrinogen, fibrin(ogen) degradation products, and platelet concentrations; and antithrombin-III and plasminogen activities. Significant alterations were observed in the mean values of most analytes (prothrombin time was increased; thrombin time was increased with subsequent decrease; activated partial thromboplastin time, fibrinogen concentration, plasminogen activity, and platelet concentration were decreased; and antithrombin-III activity and fibrin(ogen) degradation products concentration were unchanged) at 1 or more postchallenge sample collection times (3, 12, or 24 hours) after endotoxin administration, compared with mean values obtained from samples prior to endotoxin administration. These data indicated activation of hemostatic mechanisms, initiated either directly by endotoxin or by inflammatory mediators released or produced in response to endotoxin infusion.

Free access
in American Journal of Veterinary Research

Summary

Cats with cardiomyopathy, especially dilated cardiomyopathy associated with taurine deficiency, often develop systemic thrombi. To investigate the relation of taurine deficiency to formation and persistence of thrombi, cats were made taurine-deficient by consumption of a casein-based taurine-deficient diet, then were evaluated for anticoagulant and profibrinolytic activities and platelet function. The cats served as their own controls in the taurine-replete state; then, values were compared for the taurine-deficient state. Plasma (P < 0.01), blood (P < 0.05), and platelet (P < 0.05) taurine concentrations were decreased markedly after cats consumed the taurine-deficient diet for 6 weeks, compared with baseline concentrations before diet. Compared with the taurine-replete state, taurine deficiency induced significantly (P < 0.05) increased mean antithrombin III activity, no significant change in plasminogen and fibrinolytic activities, and similar clot retraction/lysis test results. Decreased (P < 0.01) adenosine diphosphate (adp)-induced platelet aggregation and [14C]serotonin release, and slightly increased (P < 0.05) collagen-induced platelet [14C]serotonin release, but unchanged collagen-induced platelet aggregation were observed in taurine-deficient cats, compared with taurine-replete cats.

Changes in antithrombin III activity most likely reflected hepatocellular acute-phase reaction, which indicates that taurine deficiency may induce a stress-responsive state. Results of platelet function testing indicate that taurine may modulate platelet responsiveness to physiologic agonists, but not in consistent manner. That platelets from the taurine-deficient cats had decreased responsiveness to adp, but increased responsiveness to collagen is surprising, because irreversible aggregation is mediated by release of granule-associated ADP after sufficient initial stimulus.

All cats had normal clot retraction in dilute blood, which indicated adequate platelet numbers and function; however, clots failed to lyse in vitro. To the authors knowledge, this observation, at present, lacks adequate explanation.

Development of marked taurine deficiency and altered in vitro results of anticoagulant activities and some platelet function tests did not result in clinical manifestations in our cats. Results of our study do not conclusively document a pathophysiologic role of taurine depletion in the formation or persistence of thrombi.

Free access
in American Journal of Veterinary Research

Summary

Platelet function, antithrombin and plasminogen activities, and fibrinolytic capabilities in 11 cats with acquired heart disease were compared with results in 4 healthy cats. Of 11 cats with heart disease, 9 had hyperthyroidism with secondary cardiac dysfunction. One cat with hyperthyroidism had renal disease and heart failure, and of 2 cats with idiopathic hypertrophic cardiomyopathy, 1 also had renal disease. At the time of testing, 3 cats had thromboembolic events associated with the disease. Compared with healthy cats, cats with acquired heart disease had increased activity of antithrombin III, a protein that behaves as an acute-phase reactant. Plasminogen activity was decreased, although not significantly, in cats with acquired heart disease, compared with results in healthy cats. In cats with left ventricular dysfunction, clot retraction was decreased (marginal significance, P = 0.058) and might be attributed, in some cases, to the medications received by the cats. Dilute whole blood clots from all cats failed to lyse in vitro. This observation, at present, lacks adequate explanation. Platelets from cats with acquired heart disease, compared with platelets from healthy cats, had decreased responsiveness (aggregation and [14C]serotonin release) to adenosine diphosphate and increased responsiveness to collagen. Hyperthyroid cats were receiving various drugs (propranolol, atenolol, or diltiazem) to empirically treat clinical signs of disease attributable to cardiac dysfunction. Although numbers of cats in each group were small, definite trends were observed in the results of tests. Platelets from cats receiving atenolol had decreased responsiveness to adenosine diphosphate and unaltered responsiveness to collagen, compared with platelets from healthy cats, and may have decreased risk of thrombus formation. Cats receiving propranolol and diltiazem had platelets with markedly increased responsiveness to collagen; however, these drugs appeared to provide sufficient cardioprotective benefits to counter the prothrombotic effects.

Free access
in American Journal of Veterinary Research

SUMMARY

Protein C content and plasminogen activity were measured in plasma from 100 horses with signs of colic. Data were analyzed by grouping horses 4 ways. Each horse was allotted to 1 of 2 outcome groups (survivors and nonsurvivors), 1 of 3 broad-category diagnosis groups (inflammatory disorders, strangulating obstructions, and all other gastrointestinal disorders), and 1 of 2 clinical management groups (medical and surgical). In a fourth grouping, all horses (although numbers of horses included in each subgroup were small) were assigned either to specific diagnostic groups that had high expectation for activated hemostasis (intestinal ischemia, endotoxemia, jugular thrombosis, peritoneal adhesions, and laminitis) or to a control group, in which active hemostasis was unlikely. Within 2 to 24 hours after admission, nonsurvivors developed lower protein C content than did survivors. Protein C content and plasminogen activity became low during hospitalization in horses with strangulating obstructions and in horses having surgery. The results from the grouping by specific diagnosis must be considered pilot data because the numbers of horses in each subgroup were small. Although not statistically significant, trends were noticed in protein C and plasminogen: (1) horses with intestinal ischemia and endotoxemia developed low protein C content and plasminogen activity, (2) protein C content became low in horses that developed peritoneal adhesions or laminitis, and (3) plasminogen activity became low in horses that developed jugular thrombosis. Low protein C content or low plasminogen activity, or both, may be useful as predictors for outcome and for these specific complications of equine colic. Protein C content and plasminogen activity were often normal at admission, but decreased by 2 to 24 hours; therefore, the hemostatic alterations appear to be an effect, rather than a cause of the gastrointestinal disorders. A return to normal values over several days may signify clinical improvement.

Free access
in American Journal of Veterinary Research

SUMMARY

An antigenic assay was developed for determination of protein C in horses. Protein C, a natural, vitamin K-dependent anticoagulant component in blood, was isolated from equine plasma, a specific antibody was produced in goats, and a rocket electroimmunophoresis assay was established. Tests were performed to verify the identity of the isolated protein C and to determine the purity of the antibody. Protein C antigen was measured in plasma from 34 clinically normal horses, and values were compared with amidolytic function values. The mean (± sd) values for the 2 test methods were similar (antigen content, 104.5 ± 13.8%; amidolytic activity, 104.6 ± 17.5%), but the correlation coefficient was 0.1. Four horses given Na coumarin had markedly decreased plasma protein C amidolytic activity and minimal decrease in protein C antigen content.

Free access
in American Journal of Veterinary Research

Summary

Cerebrospinal fluid and serum were obtained from 17 adult, healthy llamas (9 males, 1 castrated male, and 7 females). Osmolality; activities of lactate dehydrogenase and creatine kinase; and concentrations of glucose, sodium, chloride, potassium, total protein, and albumin were determined in serum and CSF. Total and differential cell counts were determined in CSF, and electrophoresis of CSF proteins was performed.

Total nucleated cell count was low, 0 to 3/μl, which is lower than that reported for other domestic species and is similar to values in healthy people. Differential leukocyte percentages were disparate depending on the degree of blood contamination. Blood contamination influenced the percentage of neutrophils and eosinophils in CSF. Samples with few erythrocytes had differential leukocyte distribution similar to that of other species: mostly lymphocytes, fewer monocytoid cells, and scant neutrophils. Older llamas had a few eosinophils in the CSF.

Total protein, albumin, and γ-globulin concentrations in llamas were similar to values in cattle and were higher than values in most domestic species. Glucose concentration in CSF was approximately 40% of the value in serum (nonruminant animals and peoply typically have CSF glucose concentration that is approximately 60 to 80% of the serum glucose concentration). Sodium and Cl concentrations in CSF were higher than those in serum, whereas K concentration was lower in CSF, compared with serum. Activities of creatine kinase and lactate dehydrogenase in CSF were markedly lower than those in serum, and the ranges of values in this group of healthy llamas were narrow.

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To assess the accuracy of automated readings of urine dipstick results for assessment of glucosuria in dogs and cats, compare visual versus automated readings of urine glucose concentration, and determine the utility of the urine glucose-to-creatinine ratio (UGCR) for quantification of glucosuria.

SAMPLE

310 canine and 279 feline urine samples.

PROCEDURES

Glucose concentration was estimated in 271 canine and 254 feline urine samples by visual assessment of urine dipstick results and with an automated dipstick reader. Absolute urine glucose and creatinine concentrations were measured in 39 canine and 25 feline urine samples by colorimetric assay with a clinical chemistry analyzer (reference standard for detection of glucosuria), and UGCRs were determined.

RESULTS

Automated assessment of the urine dipsticks yielded accurate results for 163 (60.1%) canine urine samples and 234 (92.1%) feline urine samples. Sensitivity of the automated dipstick reader for detection of glucosuria was 23% for canine samples and 68% for feline samples; specificity was 99% and 98%, respectively. Visual readings were more accurate than automated readings for both canine and feline urine. The UGCR was significantly correlated with absolute urine glucose concentration for both dogs and cats, yet there was incomplete distinction between dipstick categories for glucose concentration and UGCR.

CONCLUSIONS AND CLINICAL RELEVANCE

Urine dipstick readings for dogs and cats were useful for ruling glucosuria in when the result was positive but not for ruling it out when the result was negative. The evaluated dipsticks were more accurate for detection of glucosuria in cats than in dogs. Visual dipstick readings were more accurate than automated readings. The UGCR did not appear to provide additional useful information.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To establish the existence of platelet-derived proteins in equine plasma, with the future goal of developing an assay for the detection of in vivo platelet activation.

Animals

5 mature healthy horses.

Procedure

Platelet-rich plasma and platelet-poor plasma were prepared from anticoagulated blood. Platelets were separated from plasma proteins by gel filtration, then activated with 0.5 μM platelet-activating factor. Protease inhibitors were added, and the released platelet proteins were harvested. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was performed on the released platelet proteins and platelet-poor plasma, and the resultant silver-stained bands were compared. Immunoblot analysis was performed on released platelet proteins, using an antibody to human thrombospondin; human platelet-derived proteins served as the positive control for the antibody.

Results

Released platelet proteins in the presence of β-mercaptoethanol (reduced samples) contained several proteins that were not observed in plasma including (mean ± SEM) 194 ± 2, 159 ± 2, 151 ±2, 104 ± 2, and 95 ± 1 kd. Immunoblots of released platelet proteins had a prominent 180 ± 2-kd protein in reduced samples that was recognized by an antibody to human thrombospondin, and with prolonged color development, 2 additional less prominent proteins (166 ± 1 and 155 ± 1 kd) were observed.

Conclusions

Several proteins are released from activated equine platelets that are not detectable in normal equine plasma. Thrombospondin is one of the high molecular mass proteins released by activated equine platelets.

Clinical Relevance

An assay can be developed for detection of thrombospondin in equine plasma and may be useful for detection of in vivo platelet activation in horses. (Am J Vet Res 1997;58:954–960)

Free access
in American Journal of Veterinary Research