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- Author or Editor: Sue Yee Lim x
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Lipases are water-soluble enzymes that hydrolyze water-insoluble lipid molecules, such as triglycerides, phospholipids, and galactolipids. They are ubiquitous in nature and are present in humans, animals, insects, plants, fungi, and microorganisms. While we commonly consider pancreatic lipase, this review provides an overview of several lipases that are important for the digestion and metabolism of lipids in veterinary species. All of these enzymes have specific functions but share a common α/β-hydrolase fold and a catalytic triad where substrate hydrolysis occurs. The pancreatic lipase gene family is one of the best characterized lipase gene families and consists of 7 mammalian subfamilies: pancreatic lipase, pancreatic lipase related proteins 1 and 2, hepatic lipase, lipoprotein lipase, endothelial lipase, and phosphatidylserine phospholipase A1. Other mammalian lipases that play integral roles in lipid digestion include carboxyl ester lipase and gastric lipase. Although most enzymes have preferred substrate specificity, much overlap occurs across the plethora of lipases because of the similarities in their structures. This has major implications for the development and clinical utilization of diagnostic assays. These implications are further explored in our companion Currents in One Health article by Lim et al in the August 2022 issue of the Journal of American Veterinary Medical Association, which focuses on pancreatic lipase assays for the diagnosis of pancreatitis.
OBJECTIVE To evaluate the effects of dobutamine, esmolol, milrinone, and phenylephrine on left atrial phasic function of healthy dogs.
ANIMALS 9 healthy Beagles.
PROCEDURES Following sedation with propofol on each of 4 experimental days, dogs were administered a constant rate infusion of dobutamine (5 μg/kg/min), esmolol (500 μg/kg/min), milrinone (25 μg/kg, IV bolus, followed by 0.5 μg/kg/min), or phenylephrine (2 μg/kg/min). There was at least a 14-day interval between experimental days. Each drug was administered to 6 dogs. Conventional and 2-D speckle tracking echocardiography were performed before (baseline) and after administration of the cardiovascular drug, and time–left atrial area curves were derived to calculate indices for left atrial reservoir, conduit, and booster pump functions (left atrial phasic function) and left ventricular contractility and lusitropy.
RESULTS Compared with baseline values, indices for left atrial reservoir and booster pump functions and left ventricular contractility and lusitropy were significantly increased following dobutamine administration; indices for left atrial phasic function and left ventricular lusitropy were changed insignificantly, and indices for left ventricular contractility were significantly impaired following esmolol administration; indices for left atrial phasic function and left ventricular relaxation were changed insignificantly, and indices for left ventricular systolic function were significantly augmented following milrinone administration; and indices for left atrial phasic function and left ventricular lusitropy were changed insignificantly, and indices of ventricular contractility were significantly impaired following phenylephrine administration.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that, following administration of dobutamine, esmolol, milrinone, or phenylephrine to healthy dogs, left atrial phasic function indices were fairly stable and did not parallel changes in left ventricular function indices.
Pancreatitis commonly occurs in humans, dogs, and cats. For both veterinary and human health-care professionals, measurement of serum pancreatic lipase concentration or activity provides useful support for a diagnosis of pancreatitis. In this Currents in One Health manuscript, we will discuss commonly used lipase assays in veterinary medicine, namely catalytic colorimetric and immunological lipase assays. We highlight potential diagnostic pitfalls associated with analytical specificity, assay validation, and sample condition interferences. Catalytic lipase assays may detect extrapancreatic lipases. In addition, we propose a decision tree for interpretation of lipase assays in the context of a clinical patient.
Objective—To determine the expression of tight junction and adherens junction proteins in duodenal mucosa samples of dogs with inflammatory bowel disease (IBD).
Animals—12 dogs with IBD and 6 healthy control Beagles.
Procedures—Duodenal mucosa biopsy samples were endoscopically obtained from dogs with IBD and healthy control Beagles. The expression of claudin-1, -2, -3, -4, -5, -7, and -8; E-cadherin; and β-catenin in the duodenal mucosa samples was determined by means of immunoblotting. The subcellular localization of E-cadherin in the duodenal mucosa samples was determined with immunofluorescence microscopy.
Results—The expression of each claudin and β-catenin was not significantly different between control dogs and dogs with IBD. However, expression of E-cadherin was significantly lower in duodenal mucosa samples of dogs with IBD than it was in samples obtained from healthy control dogs. Results of immunofluorescence microscopy indicated decreased intensity of E-cadherin labeling in the tips of villi in duodenal mucosa samples obtained from 6 dogs with IBD, compared with staining intensity for other dogs.
Conclusions and Clinical Relevance—Results of this study indicated expression of claudin-1, -2, -3, -4, -5, -7, and -8 and β-catenin was not significantly different between duodenal mucosa samples obtained from control dogs and those obtained from dogs with IBD. However, E-cadherin expression was significantly lower in the villus epithelium in duodenal mucosa samples obtained from dogs with IBD versus samples obtained from control dogs, which suggested that decreased expression of that protein has a role in the pathogenesis of IBD in dogs.
OBJECTIVE To evaluate repeatability and reproducibility of right ventricular Tei index (RTX) values derived from dual pulsed-wave Doppler, conventional pulsed-wave Doppler, and tissue Doppler echocardiography and to investigate relationships and repeatability among the 3 methods in healthy dogs.
ANIMALS 6 healthy adult Beagles.
PROCEDURE Echocardiography was performed on each dog on different days for 2 weeks (3 times/d) by 2 echocardiographers. Intraobserver within- and between-day and interobserver coefficients of variation (CVs) and intraclass correlation coefficients (ICCs) for RTXs derived from dual pulse-waved Doppler (RTXDPD), conventional pulsed-wave Doppler (RTXPD), and tissue Doppler (RTXTD) methods were determined. Degrees of agreement among RTX values derived from the 3 methods were assessed by modified Bland-Altman analysis.
RESULTS Least squares mean (95% confidence interval) RTXtd was 0.50 (0.46 to 0.54), which was significantly higher than that for RTXDPD (0.27 [0.23 to 0.31]) and RTXPD (0.25 [0.21 to 0.29]). Agreement between RTXDPD and RTXPD was good (bias [mean difference], 0.04 [95% confidence interval, −0.03 to 0.10]). The RTXdpd had high within-day (CV, 6.1; ICC, 0.77) and interobserver (CV, 3.5; ICC, 0.83) repeatability, but between-day repeatability was not high. The RTXtd had high within-day repeatability (CV, 6.0; ICC, 0.80), but between-day and interobserver repeatability were not high. Within-day, between-day, and interobserver repeatability of RTXPD were not high.
CONCLUSIONS AND CLINICAL RELEVANCE RTXdpd measurement was a repeatable and reproducible method of cardiac evaluation in healthy dogs. The RTXTD values were significantly higher than the RTXDPD and RTXPD values; therefore, RTX values derived from different echocardiographic methods should be interpreted with caution.
Objective—To evaluate left atrial phasic function in healthy dogs by means of 2-D speckle tracking echocardiography with time-left atrial area curve analysis and to assess repeatability and reproducibility of obtained measurements.
Animals—6 healthy Beagles.
Procedures—Each dog underwent echocardiography twice on different days (3 nonconsecutive examinations/d). Images were analyzed with offline software; area of the left atrium was automatically calculated in each frame throughout the cardiac cycle to derive time-left atrial area curves. Variables used to assess left atrial phasic function (total, passive, and active emptying area and emptying fractions and mean active and total emptying rates) were calculated. Agreement between variables measured via speckle tracking echocardiography and a manual tracing method was assessed with modified Bland-Altman analysis. Within-day and between-day coefficients of variation were determined.
Results—Mean ± SD total, passive, and active emptying fractions of the left atrium were 49.8 ± 3.5%, 277 ± 4.0%, and 30.5 ± 4.3%, respectively. Mean ± SD total and active emptying rates were 16.0 ± 2.5 cm2/s and 25.1 ± 4.9 cm2/s, respectively. Within-day and between-day coefficients of variation were < 20% (range, 0.41% to 16.4%) for all variables except mean active emptying rate (between-day coefficient of variation, 29.2%). Agreement between variables measured via speckle tracking echocardiography and the manual tracing method was good, and differences between methods were nonsignificant.
Conclusions and Clinical Relevance—Evaluation of left atrial phasic function via speckle tracking echocardiography was feasible; repeatability and reproducibility of measurements were adequate in healthy dogs. Studies are needed to determine clinical applicability in canine patients.
OBJECTIVE To assess the use of contrast-enhanced ultrasonography (CEUS) of the hepatic vein for the detection of hemodynamic changes associated with experimentally induced portal hypertension in dogs.
ANIMALS 6 healthy Beagles.
PROCEDURES A prospective study was conducted. A catheter was surgically placed in the portal vein of each dog. Hypertension was induced by intraportal injection of microspheres (10 to 15 mg/kg) at 5-day intervals via the catheter. Microsphere injections were continued until multiple acquired portosystemic shunts were created. Portal vein pressure (PVP) was measured through the catheter. Contrast-enhanced ultrasonography was performed before and after establishment of hypertension. Time-intensity curves were generated from the region of interest in the hepatic vein. Perfusion variables measured for statistical analysis were hepatic vein arrival time, time to peak, time to peak phase (TTPP), and washout ratio. The correlation between CEUS variables and PVP was assessed by use of simple regression analysis.
RESULTS Time to peak and TTPP were significantly less after induction of portal hypertension. Simple regression analysis revealed a significant negative correlation between TTPP and PVP.
CONCLUSIONS AND CLINICAL RELEVANCE CEUS was useful for detecting hemodynamic changes associated with experimentally induced portal hypertension in dogs, which was characterized by a rapid increase in the intensity of the hepatic vein. Furthermore, TTPP, a time-dependent variable, provided useful complementary information for predicting portal hypertension.
IMPACT FOR HUMAN MEDICINE Because the method described here induced presinusoidal portal hypertension, these results can be applied to idiopathic portal hypertension in humans.