assessed patient outcomes.Discussion In contrast to studies in non-transplant populations, neither traditional nor novel impedance-based GERD metrics improved diagnostic yield compared to measuring pH alone in patients post-lung transplant.Reflux episodes and distal MNBI are insensitive tests for GERD which, if missed, may result in poor long-term clinical outcomes.These findings suggest the additional cost and time required for MII-pH interpretation compared to pH-metry alone may not be warranted.Table 1: Association between reflux episodes and mean nocturnal baseline impedance by acid exposure timeFigure 1: Distal mean nocturnal baseline impedance (MNBI) is inversely correlated with the number of reflux episodes Sa1182

less severe or nonerosive disease (GERD alone).Further prospective studies are needed to assess the benefit of aggressive anti-reflux therapy on AF outcomes.Table 1.Multiple linear regression analysis revealed that reflux esophagitis is a positive independent predictor of LOS in a nationwide inpatient cohort.BMI=body mass index; CCI=Charlson Comorbidity Index; CVA=cerebrovascular accident; LOS=length of stay.

Anesthetic agents cause dose-related alterations in many aspects of cerebral physiology including impairment of cerebral blood flow (CBF) autoregulation. To address this concern we have developed a novel survival surgery to investigate mechanisms of CBF control and regulation in conscious, unrestrained rats. To assess the feasibility and efficacy of our technique, we determined the impact of hypercapnia on CBF autoregulation in response to a phenylephrine induced increase in blood pressure (BP). We have observed that CBF was greater when measured while rats were anesthetized compared to CBF measured in conscious rats. Spontaneously breathing a hypercapnic gas mixture (5% CO2, 21% O2, and 74% N2), increased arterial blood gas values for pCO2 and pO2 by 26% and 45%, respectively, compared to inspired room air. Despite the significant increase in pCO2, there was no change in absolute CBF in the conscious rat. As BP increased in response to phenylephrine, CBF did not significantly change in conscious rats breathing room air (Autoregulatory Index, AI: -0.1). In contrast, CBF autoregulatory capacity was impaired in both conscious rats exposed to a hypercapnic gas mixture (5% CO2) and in isoflurane anesthetized rats (Iso), resulting in an increase in CBF with increasing BP (AI: 5% CO2 = 0.5; Iso = 0.7). Our findings suggest that isoflurane could potentially uncouple the normal function of the neurovascular unit and underscore the importance of designing experiments without the use of anesthetic agents. Combining this survival surgery with a flow-through plethysmograph allows for chronic repeated-measures of CBF within the same animal while being able to investigate the impact of hypercapnic or hypoxic conditions on CBF regulation. Research supported by NIH.

Hydrophilic polymers are the most common group of polymers used in the preparation of modifiedreleasedrug delivery systems. This is due to their versatility, low cost, high production yield, as well as easy manufacturingand adequate in vitro/in vivo correlation. In normal physiological conditions, the matrix controls the release of the loaded drugover time through a process of diffusion and/or erosion of the matrix, depending on its physicochemical composition. This is particularlyrelevant when describing the pharmacokinetic profile of nanosized drug delivery systems (nanoparticles). The use of mathematical modelsbecame an important tool to characterize the pharmacokinetics of drugs loaded in nanoparticles to improve the drug bioavailabilityand to establish bioequivalence. Therefore, the drug release profile can be predicted by a minimum number of experimental studies, sincethe mathematical equations reveal the dissolution rate of the drug loaded in the hydrophilic matrix. The present paper discusses the use ofmathematical models when developing modified-release drug delivery systems of nanometer size composed of hydrophilic polymers.