Retrospective evaluation of a dose-dependent effect of angiotensin-converting enzyme inhibitors on long-term outcome in dogs with cardiac disease.

BACKGROUND: Angiotensin-converting enzyme inhibitors (ACEIs) are commonly prescribed in dogs, but the ideal dosage is unknown. HYPOTHESIS/OBJECTIVES: In dogs with cardiac disease, a dose-response relationship exists for ACEIs with respect to long-term outcome. ANIMALS: One hundred forty-four dogs with cardiac disease, 63 with current or prior congestive heart failure. METHODS: Retrospective medical record review. Cox proportional hazards models were used to determine variables associated with 2-year survival or survival from first-onset congestive heart failure (CHF). RESULTS: Median initial ACEI dosage was 0.84 (interquartile range [IQR], 0.56-0.98) mg/kg/day, and 108/144 (75%) of dogs received q12h dosing. No clinically relevant changes in renal function test results, serum electrolyte concentrations, or blood pressure occurred between initial prescription of ACEI and first reevaluation (median, 14 days later). In univariable analysis, higher ACEI dose was associated with increased survival from first-onset CHF (P = .005), and within the subgroup of dogs in CHF at the time of ACEI prescription, higher ACEI dose was associated with improved survival at 2 years (P = .04). In multivariable analysis, q12h dose frequency of ACEI (hazard ratio [HR], 0.30; 95% CI, 0.10-0.88; P = .03) and higher serum potassium concentration at visit 1 (HR, 0.39; 95% CI, 0.16-0.97; P = .04) were predictive of 2-year survival. The ACEIs were well-tolerated, with only 8/144 (5.6%) dogs having ACEI dose decreased or discontinued because of adverse effects. CONCLUSIONS AND CLINICAL IMPORTANCE: Twice daily dose frequency might optimize the cardioprotective benefit of ACEIs.

Focused ultrasound of the caudal vena cava in dogs with cavitary effusions or congestive heart failure: A prospective, observational study.

INTRODUCTION: Ultrasonographic indices of the inferior vena cava are useful for predicting right heart filling pressures in people. OBJECTIVES: To determine whether ultrasonographic indices of caudal vena cava (CVC) differ between dogs with right-sided CHF (R-CHF), left-sided CHF (L-CHF), and noncardiac causes of cavitary effusion (NC). MATERIALS AND METHODS: 113 dogs diagnosed with R-CHF (n = 51), L-CHF (30), or NC effusion (32) were enrolled. Seventeen of the R-CHF dogs had pericardial effusion and tamponade. Focused ultrasound was performed prospectively to obtain 2-dimensional and M-mode subxiphoid measures of CVC maximal and minimal size (CVCmax and CVCmin), CVCmax indexed to aortic dimension (CVC:Ao), and CVC collapsibility index (CVC-CI). Variables were compared between study groups using Kruskal-Wallis and Dunn's-Bonferroni testing, and receiver operating characteristics curves were used to assess sensitivity and specificity. RESULTS: All sonographic CVC indices were significantly different between R-CHF and NC dogs (P < 0.001). Variables demonstrating the highest diagnostic accuracy for discriminating R-CHF versus NC were CVC-CI <33% in 2D (91% sensitive and 96% specific) and presence of hepatic venous distension (84% sensitive and 90% specific). L-CHF dogs had higher CVC:Ao and lower CVC-CI compared to NC dogs (P = 0.016 and P = 0.043 in 2D, respectively) but increased CVC-CI compared to the R-CHF group (P < 0.001). CONCLUSIONS: Ultrasonographic indices of CVC size and collapsibility differed between dogs with R-CHF compared to NC causes of cavitary effusions. Dogs with L-CHF have CVC measurements intermediate between R-CHF and NC dogs.

Experimental and simulation studies of anti-reflection sub-micron conical structures on a GaAs substrate.

In order to reduce surface reflection, anti-reflective (AR) coatings are widely used on the surfaces of solar cells to improve the efficiency of photoelectric conversion. This study employed colloidal lithography with a dry etching process to fabricate sub-micron anti-reflection structures on a GaAs substrate. Etching parameters, such as RF power and etching gas were investigated to determine their influence on surface morphology. We fabricated an array of conical structures 550 nm in diameter and 450 nm in height. The average reflectance of a bare GaAs wafer was reduced from 35.0% to 2.3% across a spectral range of 300 nm - 1200 nm. The anti-reflective performance of SWSs was also calculated using Rigorous Coupled Wave Analysis (RCWA) method. Both simulation and experiment results demonstrate a high degree of similarity.

Fabrication of high-refractive-index microstructures and their applications to the efficiency improvement of GaN-based LEDs.

This study employed a UV-assisted roller imprinting technique using PDMS soft molds to imprint periodically inverted-pyramid structures on the surface of GaN-based LEDs. The refractive indices of the structures were 1.5, 1.7, and 1.9, which enhanced light output power by 26%, 43%, and 50%, respectively, compared to conventional LEDs. Materials with a greater refractive index indicate a larger critical angle of total internal reflection from the semi-conductor to the imprinted material. Once photons are extracted into the imprinted structure, they are prone to be extracted into the air through the structured surface. The numerical simulation performed using the ray tracing method proved useful for identifying the microstructure with optimal light extraction efficiency. Simulation results showed that LEDs with imprinted structures of varying refractive indices enhance optical efficiency in a manner similar to that demonstrated in these experiments.