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- Author or Editor: David A. Williams x
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Abstract
Objective—To develop and validate a radioimmunoassay (RIA) for measuring canine pancreatic lipase immunoreactivity (cPLI) in serum obtained from dogs.
Sample Population—Serum samples from 47 healthy dogs.
Procedures—Canine pancreatic lipase (cPL) was purified from pancreatic specimens of dogs. Antibodies against cPL were raised in rabbits and purified by use of affinity chromatography. A tracer was produced by iodination of cPL with 125I. An RIA was established and validated by determination of sensitivity, working range, dilutional parallelism, spiking recovery, and intra- and interassay variability. A reference range for cPLI in serum was established by use of the central 95th percentile for samples obtained from 47 healthy dogs.
Results—Sensitivity and upper limit of the working range were 0.88 and 863 µg/L, respectively. Observed-to-expected ratios for serial dilutions ranged from 84.9 to 116.5% for 4 samples. Observedto- expected ratios for spiking recovery ranged from 82.8 to 128.6% for 4 samples. Coefficients of variation for intra-assay variability for 4 serum samples were 18.3, 4.2, 3.5, and 8.9%, whereas interassay coefficients of variation were 29.2, 6.2, 3.9, and 4.4%, respectively. The reference range was 4.4 to 276.1 µg/L.
Conclusions and Clinical Relevance—We conclude that the RIA described is sensitive, linear, accurate, precise, and reproducible, with limited accuracy in the high end of the working range and limited precision and reproducibility in the low end of the working range. Additional studies are needed to evaluate whether this degree of accuracy, precision, and reproducibility will negatively impact clinical use of this assay. (Am J Vet Res 2003;64:1237–1241)
Abstract
Objective—To develop and validate a gas chromatography–mass spectrometry (GC-MS) method for determination of Nτ-methylhistamine (NMH) concentration in canine urine and fecal extracts and to assess urinary NMH concentrations in dogs with mast cell neoplasia and fecal NMH concentrations in dogs with protein-losing enteropathy.
Sample Population—Urine specimens were collected from 6 healthy dogs and 7 dogs with mast cell neoplasia. Fecal extracts were obtained from fecal specimens of 28 dogs with various severities of protein-losing enteropathy, as indicated by fecal concentration of α1-proteinase inhibitor.
Procedures—NMH was extracted directly from urine, and fecal specimens were first extracted into 5 volumes of PBSS containing 1% newborn calf serum. Nτ-methylhistamine in specimens was quantified via stable isotope dilution GC-MS. The assay was validated via determination of percentage recovery of known amounts of NMH and interassay coefficients of variation. Urinary excretion of NMH was evaluated by means of NMH-to-creatinine concentration ratios.
Results—Recovery of NMH in urine and fecal extracts averaged 104.6% and 104.5%, respectively. Interassay coefficients of variation ranged from 5.4% to 11.7% in urine and 12.6% to 18.1% in fecal extracts. Urinary NMH excretion was significantly increased in dogs with mast cell neoplasia, compared with that in healthy dogs. No correlation was detected between severity of protein-losing enteropathy and fecal NMH concentration.
Conclusions and Clinical Relevance—This method provided a sensitive, reproducible means of measuring NMH in canine urine and fecal extracts. High urinary NMH-to-creatinine concentration ratios in dogs with mast cell neoplasia are consistent with increased histamine release in this disease.
Abstract
Objective—To determine serum lipase activities and pancreatic lipase immunoreactivity (PLI) concentrations in dogs with exocrine pancreatic insufficiency (EPI).
Animals—74 healthy dogs and 25 dogs with EPI.
Procedures—A diagnosis of EPI was made on the basis of clinical signs, low serum trypsin like immunoreactivity (TLI) concentration, and response to treatment with enzyme replacement. Median values for fasting serum lipase activity and serum PLI concentrations were compared between the 2 groups with a Mann-Whitney U test.
Results—Median fasting serum lipase activity was not significantly different between dogs with EPI (366.0 U/L) and healthy dogs (294.5 U/L), and only 1 dog with EPI had a serum lipase activity less than the lower limit of the reference range. Median serum PLI concentration was significantly lower in dogs with EPI (0.1 μg/L) than in healthy dogs (16.3 μg/L). All dogs with EPI had serum PLI concentrations less than the lower limit of the reference range.
Conclusion and Clinical Relevance—Serum lipase activity is not limited to the exocrine pancreas in origin, whereas serum PLI is derived only from the exocrine pancreas. Unlike in serum TLI concentrations, there was a small degree of overlap in serum PLI concentrations between healthy dogs and dogs with EPI. Serum TLI concentration remains the test of choice for diagnosis of EPI.
Abstract
Objective—To determine cellular immunolocalization of canine gastric lipase (cGL) and canine pancreatic lipase (cPL) in various tissues obtained from clinically healthy dogs.
Sample Population—Samples of 38 tissues collected from 2 climically healthy dogs.
Procedures—The cGL and cPL were purified from gastric and pancreatic tissue, respectively, obtained from dogs. Antisera against both proteins were developed, using rabbits, and polyclonal antibodies were purified by use of affinity chromatography. Various tissues were collected from 2 healthy dogs. Primary antibodies were used to evaluate histologic specificity. Replicate sections from the collected tissues were immunolabeled for cGL and cPL and examined by use of light microscopy.
Results—Mucous neck cells and mucous pit cells of gastric glands had positive labeling for cGL, whereas other tissues did not immunoreact with cGL. Pancreatic acinar cells had positive labeling for cPL, whereas other tissues did not immunoreact with cPL.
Conclusions and Clinical Relevance—We concluded that cGL and cPL are exclusively expressed in gastric glands and pancreatic acinar cells, respectively. Also, evidence for cross-immunoreactivity with other lipases or related proteins expressed by other tissues was not found for either protein. Analysis of these data suggests that gastric lipase is a specific marker for gastric glands and that pancreatic lipase is a specific marker for pancreatic acinar cells. These markers may have clinical use in the diagnosis of gastric and exocrine pancreatic disorders, respectively. (Am J Vet Res 2002;63:722–727).
Abstract
Objective—To investigate postprandial changes in serum concentrations of unconjugated bile acids in healthy Beagles.
Animals—7 healthy Beagles.
Procedure—Blood samples were obtained from dogs at regular intervals up to 8 hours after consumption of a meal. Serum concentrations of 5 unconjugated bile acids were determined at each time point, using gas chromatography-mass spectrometry with selected ion monitoring.
Results—Total serum unconjugated bile acid concentration was significantly increased, relative to baseline values, at 360, 420, and 480 minutes after feeding. Unconjugated cholic acid was significantly increased at 360, 420, and 480 minutes. The proportion of total unconjugated bile acids represented by cholic acid was significantly increased at 240 to 480 minutes. Deoxycholic acid was significantly increased at 360 and 420 minutes. Chenodeoxycholic acid was significantly increased at 360 to 480 minutes. Lithocholic acid was significantly increased at 180 minutes, whereas no significant changes in ursodeoxycholic acid were detected at any time point.
Conclusion and Clinical Relevance—Healthy Beagles had significant increases in serum concentrations and changes in the profile of unconjugated bile acids after a meal. These increases persisted > 8 hours, indicating that prolonged withholding of food is necessary when to avoid the risk of a false-positive diagnosis when assessing serum unconjugated bile acid concentrations in dogs. (Am J Vet Res 2002;63:789–793
Abstract
Objective—To describe the kinetics of urinary recovery (UR) of 5 sugars used for gastrointestinal permeability and mucosal function testing following orogastric administration of lactose, rhamnose, xylose, methylglucose, and sucrose.
Animals—7 healthy male Beagles.
Procedure—A sugar solution containing lactulose, rhamnose, xylose, methylglucose, and sucrose was administered by orogastric intubation to healthy dogs. Urine samples were collected immediately before sugar solution administration (baseline) and at 2-hour intervals thereafter. The UR of the 5 sugars was determined from urine concentrations measured by high pressure liquid chromatography and pulsed amperometric detection. Percent urinary recovery (%UR) of the total UR up to 12 hours after sugar solution administration was calculated for each sugar at 2-hour intervals.
Results—Mean %UR exceeded 85% for all 5 sugars at 6 hours after orogastric administration of the sugar solution and exceeded 90% after 8 hours.
Conclusion and Clinical Relevance—In healthy dogs, a urine collection period of 6 hours is sufficient for gastrointestinal permeability and mucosal function testing following orogastric administration of lactulose, rhamnose, xylose, methylglucose, and sucrose. (Am J Vet Res 2002;63:845–848)
Abstract
Objective—To validate an automated chemiluminescent immunoassay for measuring serum cobalamin concentration in cats, to establish and validate gas chromatography-mass spectrometry techniques for use in quantification of methylmalonic acid, homocysteine, cysteine, cystathionine, and methionine in sera from cats, and to investigate serum concentrations of methylmalonic acid, methionine, homocysteine, cystathionine, and cysteine as indicators of biochemical abnormalities accompanying severe cobalamin (vitamin B12) deficiency in cats.
Sample Population—Serum samples of 40 cats with severe cobalamin deficiency (serum cobalamin concentration < 100 ng/L) and 24 control cats with serum cobalamin concentration within the reference range.
Procedure—Serum concentrations of cobalamin were measured, using a commercial automated chemiluminescent immunoassay. Serum concentrations of methylmalonic acid, methionine, homocysteine, cystathionine, and cysteine were measured, using gas chromatography-mass spectrometry, selected ion monitoring, stable-isotope dilution assays.
Results—Cats with cobalamin deficiency had significant increases in mean serum concentrations of methylmalonic acid (9,607 nmol/L), compared with healthy cats (448 nmol/L). Affected cats also had substantial disturbances in amino acid metabolism, compared with healthy cats, with significantly increased serum concentrations of methionine (133.8 vs 101.1 µmol/L) and significantly decreased serum concentrations of cystathionine (449.6 vs 573.2 nmol/L) and cysteine (142.3 vs 163.9 µmol/L). There was not a significant difference in serum concentrations of homocysteine between the 2 groups.
Conclusions and Clinical Relevance—Cats with gastrointestinal tract disease may have abnormalities in amino acid metabolism consistent with cobalamin deficiency. Parenteral administration of cobalamin may be necessary to correct these biochemical abnormalities. (Am J Vet Res 2001;62:1852–1858)
Abstract
Objective—To identify changes in folate status of mares and foals during lactation and growth, respectively.
Animals—20 Thoroughbred mares and foals.
Procedures—Pregnant mares, and following foaling the same mares with their foals, were maintained on mixed grass-legume pasture and fed either a traditional dietary supplement rich in sugar and starch (SS) or a dietary supplement high in fat and fiber (FF). Blood samples were collected monthly from mares and foals up to 6 months after foaling. Total folate concentration in feed and forage was determined. Analyses of plasma folate, RBC folate, plasma homocysteine (HCY), and milk folate concentrations were performed.
Results—Mare plasma folate concentrations declined moderately during 6 months of lactation. Mare RBC folate concentrations initially increased after foaling up to 3 months but declined toward the end of the study. Plasma HCY concentration was higher for mares fed the SS supplement, compared with mares fed the FF supplement from foaling to 6 months of lactation. Milk folate concentrations decreased during the first 3 months and then increased. Foal plasma folate initially declined but then increased. Stable concentrations of RBC folate were observed in foals. Plasma HCY concentrations in foals were unaffected by growth during the last 5 months. References range values for plasma folate, RBC folate, milk folate, and plasma HCY concentrations in healthy lactational mares and young growing foals were determined.
Conclusions and Clinical Relevance—Folate status was not impaired in lactating mares and growing foals under the conditions in our study. It appears that folate supplementation is not necessary. (Am J Vet Res 2005;66:1214–1221)
