Topical Reformulation of Valsartan for Treatment of Chronic Diabetic Wounds.

Chronic wounds are among the most devastating and difficult to treat consequences of diabetes. Dysregulation of the skin renin-angiotensin system is implicated in abnormal wound healing in diabetic and older adults. Given this, we sought to determine the effects of topical reformulations of the angiotensin type 1 receptor blockers losartan and valsartan and the angiotensin-converting enzyme inhibitor captopril on wound healing in diabetic and aged mice with further validation in older diabetic pigs. The application of 1% valsartan gel compared with other tested formulations and placebo facilitated and significantly accelerated closure time and increased tensile strength in mice, and was validated in the porcine model. One percent of valsartan gel-treated wounds also exhibited higher mitochondrial content, collagen deposition, phosphorylated mothers against decapentaplegic homologs 2 and 3 and common mothers against decapentaplegic homolog 4, alpha-smooth muscle actin, CD31, phospho-vascular endothelial growth factor receptor 2, and p42/44 mitogen-activated protein kinase. Knockout of the angiotensin subtype 2 receptors abolished the beneficial effects of angiotensin type 1 receptor blockers, suggesting a role for angiotensin subtype 2 receptors in chronic wound healing.

Obstructive Sleep Apnea Dynamically Increases Nocturnal Plasma Free Fatty Acids, Glucose, and Cortisol During Sleep.

Context: Obstructive sleep apnea (OSA) is associated with diabetes and cardiovascular disease. This association may be related to metabolic changes that transpire during sleep in OSA. Objective: To examine the impact of OSA, elicited by cessation of continuous positive airway pressure (CPAP), on frequently sampled nocturnal metabolic markers including plasma free fatty acids (FFAs), glucose, insulin, triglycerides (TGs), cortisol, and lactate, as well as glucose production, oral glucose tolerance, blood pressure (BP), endothelial function, cholesterol, and high-sensitivity C-reactive protein (hsCRP). Design and Setting: Randomized crossover trial of CPAP vs CPAP withdrawal. Patients: Thirty-one patients with moderate to severe OSA acclimated to CPAP. Intervention: Patients underwent attended polysomnography while sleeping with therapeutic CPAP, or after CPAP withdrawal, in random order. Venous blood was sampled at ∼20-minute intervals on both nights. In 11 patients, we assessed glucose kinetics with an infusion of 6,6-[2H2]glucose. Results: CPAP withdrawal caused recurrence of OSA associated with hypoxemia, sleep disruption, and heart rate (HR) elevation. CPAP withdrawal dynamically increased nocturnal FFA (P = 0.007), glucose (P = 0.028), and cortisol (P = 0.037), in proportion to respiratory event frequency, HR elevation, or sleep fragmentation. Diabetes predisposed to glucose elevation. CPAP withdrawal also increased systolic BP (P = 0.017) and augmentation index (P = 0.008), but did not affect insulin, TGs, glucose production, oral glucose tolerance, cholesterol, or hsCRP. Conclusion: OSA recurrence during CPAP withdrawal increases FFA and glucose during sleep, associated with sympathetic and adrenocortical activation. Recurring exposure to these metabolic changes may foster diabetes and cardiovascular disease.

The EFFORT trial: Preoperative enoxaparin versus postoperative fondaparinux for thromboprophylaxis in bariatric surgical patients: a randomized double-blind pilot trial.

BACKGROUND: Prophylaxis for venous thromboembolism is routinely performed for all patients undergoing bariatric surgery. However, there is disagreement regarding the optimal dosing and duration of anticoagulant therapy. Furthermore, there is little data regarding the incidence of asymptomatic deep venous thrombosis (DVT) in this population. Our objective was to conduct a pilot randomized double blind study to evaluate the pharmacodynamic parameters of 2 different anticoagulation medications (enoxaparin and fondaparinux) administered to patients undergoing bariatric surgery. METHODS: From July 2010 to August 2013, 198 consecutive bariatric surgery patients from an academic institution were randomized in a double blinded manner to receive either 40 mg enoxaparin twice daily or 5mg fondaparinux sodium once daily. Antifactor Xa activity was measured on all patients in both study arms, 3 hours after the first dose (on the day of the operation), immediately before the second dose (postoperative day one), and 3 hours after the second dose. At the routine 2 week postoperative visit, patients underwent magnetic resonance venography (MRV) to detect DVT. The primary outcome was attainment of therapeutic antifactor Xa levels. The secondary outcome was DVT, as detected by MRV. Safety outcomes were perioperative bleeding, perioperative complications, and death. RESULTS: Of 198 patients randomized, 177 underwent MRV and 137 had interpretable antifactor Xa levels. Nearly half of the patients (47.4%) did not attain target prophylactic antifactor Xa levels. Adequate antifactor Xa levels were more common with fondaparinux (74.2%) than with enoxaparin (32.4%). Antifactor Xa levels were also associated with preoperative D-dimer level. 4 of the 175 patients who underwent MRV developed DVT, 2 in each arm of the study. No major adverse events occurred in either arm. CONCLUSION: Fondaparinux was much more likely to produce target prophylactic antifactor Xa levels than enoxaparin. Both regimens appear to be equally effective at reducing the risk of DVT. Further prospective studies are needed to determine the optimal DVT prophylaxis regimen in the bariatric surgical population.

Unexpected relative aqueous solubilities of a phosphotyrosine analogue and two phosphonate derivatives.

Phosphotyrosine (pTyr) is an essential component of biological signaling, often being a determinant of protein-protein interactions. Accordingly, a number of drug discovery efforts targeting signal transduction pathways have included phosphotyrosine and analogues as essential components of the lead compounds. Toward the goal of improved biological efficacy, the phosphonate and difluoro phosphonate analogues of pTyr have been employed in inhibitor design because of their stability to hydrolysis and enhanced binding affinity in certain cases. To quantitate the contribution of aqueous solubility of pTyr, phosphonomethyl phenylalanine (Pmp), and difluorophosphonomethyl phenylalanine (F(2)Pmp) to their relative binding affinities, free energy perturbation calculations were undertaken on the mimetics phenol phosphate (PP), benzyl phosphonate (BP), and difluorobenzyl phosphonate (F(2)BP), including development of empirical force field parameters compatible with the CHARMM all-atom force fields. Notably, it is shown that the most favorably solvated compound of the series is BP, followed by PP, with F(2)BP the least favorably solvated for both the mono- and dianionic forms of the compounds. The molecular origin of this ordering is shown to be due to changes in charge distribution, in the comparatively larger size of the fluorine atoms, as well as in differences of local solvation between PP and BP. The implications of the differences in aqueous solubility toward the relative binding potencies of pTyr-, Pmp-, and F(2)Pmp-containing peptide ligands are discussed. Our results indicate that one general principle explaining the efficacy of selective fluorination to enhance binding affinities may lie in the ability of fluorine atoms to increase the hydrophobicity of a ligand while maintaining its capability to form hydrogen bonds.

Influence of conformation on the EPR spectrum of 5,5-dimethyl-1-hydroperoxy-1-pyrrolidinyloxyl: a spin trapped adduct of superoxide.

Spin trapping, a technique used to characterize short-lived free radicals, consists of using a nitrone or nitroso compound to "trap" an unstable free radical as a long-lived aminoxyl that can be characterized by EPR spectroscopy. The resultant aminoxyl exhibits hyperfine splitting constants that are dependent on the spin trap and the free radical. Such is the case with 2,2-dimethyl-5-hydroxy-1-pyrrolidinyloxyl (DMPO-OH) and 2,2-dimethyl-5-hydroperoxy-1-pyrrodinyloxyl (DMPO-OOH) whose hyperfine splitting constants, A(N) = A(H) = 14.9 G and A(N) = 14.3 G, A(H)(beta) = 11.7 G, and A(H)(gamma) = 1.25 G, respectively, have been used to demonstrate the generation of HO(*) and O(2)(*)(-). However, to date, the source of the apparent A(H)(gamma) hyperfine splitting in DMPO-OOH is not known. We consider three possible explanations to account for the unique EPR spectrum of DMPO-OOH. The first is that the gamma-splitting arises from one of the hydrogen atoms at either carbon 3 or carbon 4 of DMPO-OOH. The second is that the gamma-splitting originates from the hydrogen atom of DMPO-OOH. The third is that the conformational properties of DMPO-R change upon going from DMPO-OH to DMPO-OOH. Experimental and theoretical chemical approaches as well as EPR spectral modeling were used to investigate which of these hypotheses may explain the asymmetric EPR spectrum of DMPO-OOH. From these studies it is shown that the 12-line EPR spectrum of DMPO-OOH results not from any proximal hydrogen, but from additional conformers of DMPO-OOH. Thus, the 1.25 G hyperfine splitting, which has been assigned as a gamma-splitting, is actually from two individual EPR spectra associated with different conformers of DMPO-OOH.