CYP11B2 inhibitor dexfadrostat phosphate suppresses the aldosterone-to-renin ratio, an indicator of sodium retention, in healthy volunteers.

AIMS: High aldosterone is a key driver of hypertension and long-term negative sequelae. We evaluated the safety and efficacy of dexfadrostat phosphate (DP13), a novel aldosterone synthase (CYP11B2) inhibitor, in healthy participants. METHODS: This randomized, double-blind, placebo-controlled study was conducted in two parts. In part A, a single-ascending dose escalation, 16 participants received oral DP13 1-16 mg. Part B was a multiple-ascending dose, sequential group study in which 32 participants received oral DP13 4, 8 or 16 mg once daily for 8 days. Safety and tolerability were monitored throughout. An adrenocorticotropic hormone (ACTH) stimulation test at maximal blood drug concentrations defined the dose range for multiple dosing. RESULTS: DP13 was well tolerated at all doses, with no serious adverse events. In part B, all DP13 doses (4, 8 and 16 mg) over 8 days effectively suppressed aldosterone production, increased the urinary sodium/potassium ratio, decreased plasma sodium and increased plasma potassium and renin levels compared with placebo, resulting in potent suppression of the aldosterone-to-renin ratio (ARR). Endocrine counter-regulation resulted in the 4 mg dose no longer sustaining 24-h aldosterone suppression after 8 days of treatment, unlike the 8- and 16 mg doses. There was no evidence of drug-induced adrenal insufficiency (ACTH stress challenge). CONCLUSIONS: In patients with excess aldosterone and ensuing sodium retention driving hypertension, managing sodium balance is critical. A CYP11B2 inhibitor like DP13, whose effectiveness can be monitored by a reduction in ARR, may prove valuable in managing aldosterone-dependent hypertension and primary aldosteronism.

Effectiveness of hospital transfer payments under a prospective payment system: An analysis of a policy change in New Zealand.

Prospective payment systems reimburse hospitals based on diagnosis-specific flat fees, which are generally based on average costs. While this encourages cost-consciousness on the part of hospitals, it introduces undesirable incentives for patient transfers. Hospitals might feel encouraged to transfer patients if the expected treatment costs exceed the diagnosis-related flat fee. A transfer fee would discourage such behavior and, therefore, could be welfare enhancing. In 2003, New Zealand introduced a fee to cover situations of patient transfers between hospitals. We investigate the effects of this fee by analyzing 4,020,796 healthcare events from 2000 to 2007 and find a significant reduction in overall transfers after the policy change. Looking at transfer types, we observe a relative reduction in transfers to non-specialist hospitals but a relative increase in transfers to specialist facilities. It suggests that the policy change created a focusing effect that encourages public health care providers to transfer patients only when necessary to specialized providers and retain those patients they can treat. We also find no evidence that the transfer fee harmed the quality of care, measured by mortality, readmission and length of stay. The broader policy recommendation of this research is the introduction or reassessment of transfer payments to improve funding efficiency.

Do Capitation-based Reimbursement Systems Underfund Tertiary Healthcare Providers? Evidence from New Zealand.

One of the main concerns about capitation-based reimbursement systems is that tertiary institutions may be underfunded due to insufficient reimbursements of more complicated cases. We test this hypothesis with a data set from New Zealand that, in 2003, introduced a capitation system where public healthcare provider funding is primarily based on the characteristics of the regional population. Investigating the funding for all cases from 2003 to 2011, we find evidence that tertiary providers are at a disadvantage compared with secondary providers. The reasons are that tertiary providers not only attract the most complicated, but also the highest number of cases. Our findings suggest that accurate risk adjustment is crucial to the success of a capitation-based reimbursement system. Copyright © 2017 John Wiley & Sons, Ltd.

A Soft Total Artificial Heart-First Concept Evaluation on a Hybrid Mock Circulation.

The technology of 3D-printing has allowed the production of entirely soft pumps with complex chamber geometries. We used this technique to develop a completely soft pneumatically driven total artificial heart from silicone elastomers and evaluated its performance on a hybrid mock circulation. The goal of this study is to present an innovative concept of a soft total artificial heart (sTAH). Using the form of a human heart, we designed a sTAH, which consists of only two ventricles and produced it using a 3D-printing, lost-wax casting technique. The diastolic properties of the sTAH were defined and the performance of the sTAH was evaluated on a hybrid mock circulation under various physiological conditions. The sTAH achieved a blood flow of 2.2 L/min against a systemic vascular resistance of 1.11 mm Hg s/mL (afterload), when operated at 80 bpm. At the same time, the mean pulmonary venous pressure (preload) was fixed at 10 mm Hg. Furthermore, an aortic pulse pressure of 35 mm Hg was measured, with a mean aortic pressure of 48 mm Hg. The sTAH generated physiologically shaped signals of blood flow and pressures by mimicking the movement of a real heart. The preliminary results of this study show a promising potential of the soft pumps in heart replacements. Further work, focused on increasing blood flow and in turn aortic pressure is required.

Serelaxin, recombinant human relaxin-2, for treatment of acute heart failure (RELAX-AHF): a randomised, placebo-controlled trial.

BACKGROUND: Serelaxin, recombinant human relaxin-2, is a vasoactive peptide hormone with many biological and haemodynamic effects. In a pilot study, serelaxin was safe and well tolerated with positive clinical outcome signals in patients with acute heart failure. The RELAX-AHF trial tested the hypothesis that serelaxin-treated patients would have greater dyspnoea relief compared with patients treated with standard care and placebo. METHODS: RELAX-AHF was an international, double-blind, placebo-controlled trial, enrolling patients admitted to hospital for acute heart failure who were randomly assigned (1:1) via a central randomisation scheme blocked by study centre to standard care plus 48-h intravenous infusions of placebo or serelaxin (30 µg/kg per day) within 16 h from presentation. All patients had dyspnoea, congestion on chest radiograph, increased brain natriuretic peptide (BNP) or N-terminal prohormone of BNP, mild-to-moderate renal insufficiency, and systolic blood pressure greater than 125 mm Hg. Patients, personnel administering study drug, and those undertaking study-related assessments were masked to treatment assignment. The primary endpoints evaluating dyspnoea improvement were change from baseline in the visual analogue scale area under the curve (VAS AUC) to day 5 and the proportion of patients with moderate or marked dyspnoea improvement measured by Likert scale during the first 24 h, both analysed by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00520806. FINDINGS: 1161 patients were randomly assigned to serelaxin (n=581) or placebo (n=580). Serelaxin improved the VAS AUC primary dyspnoea endpoint (448 mm × h, 95% CI 120-775; p=0·007) compared with placebo, but had no significant effect on the other primary endpoint (Likert scale; placebo, 150 patients [26%]; serelaxin, 156 [27%]; p=0·70). No significant effects were recorded for the secondary endpoints of cardiovascular death or readmission to hospital for heart failure or renal failure (placebo, 75 events [60-day Kaplan-Meier estimate, 13·0%]; serelaxin, 76 events [13·2%]; hazard ratio [HR] 1·02 [0·74-1·41], p=0·89] or days alive out of the hospital up to day 60 (placebo, 47·7 [SD 12·1] days; serelaxin, 48·3 [11·6]; p=0·37). Serelaxin treatment was associated with significant reductions of other prespecified additional endpoints, including fewer deaths at day 180 (placebo, 65 deaths; serelaxin, 42; HR 0·63, 95% CI 0·42-0·93; p=0·019). INTERPRETATION: Treatment of acute heart failure with serelaxin was associated with dyspnoea relief and improvement in other clinical outcomes, but had no effect on readmission to hospital. Serelaxin treatment was well tolerated and safe, supported by the reduced 180-day mortality. FUNDING: Corthera, a Novartis affiliate company.

Avosentan is protective in hypertensive nephropathy at doses not causing fluid retention.

Multiple studies indicate that endothelin antagonism may have a protective effect for chronic kidney disease. Despite that, clinical studies using avosentan have been halted due to adverse effects including fluid overload. Therefore, we aimed at investigating whether avosentan may have protective effects against hypertensive nephropathy at doses below those inducing fluid-retention. We used double transgenic rats (dTGR), overexpressing both the human renin and angiotensinogen gene, which develop malignant hypertension. Effects of avosentan alone or in combination with low-dose of valsartan (angiotensin AT1 receptor antagonist) on end-organ damage were studied. Avosentan induced a decrease of diuresis (18.3%) with a consequent decrease in hematocrit (8.3%) only at the highest dose investigated (100mg/kg). Treatment with the combination of avosentan and valsartan (10 and 0.1mg/kg, once daily by gavage, respectively) decreased albuminuria to a greater extent than each compound given alone (avosentan: 19.6mg/24h; valsartan: 12.9mg/24h; avosentan+valsartan: 1.7mg/24h, data are median values). Histological severity score also showed a drastic reduction of kidney damage. Furthermore, avosentan alone or in combination therapy dramatically decreased mortality compared to the 100% in untreated animals. These data support a therapeutic effect of avosentan at doses below those inducing fluid overload.

Safety and efficacy of once-daily dexfadrostat phosphate in patients with primary aldosteronism: a randomised, parallel group, multicentre, phase 2 trial.

Background: Primary aldosteronism (PA) is caused by autonomous aldosterone overproduction and characterised by uncontrolled hypertension. There are currently no treatments that target aldosterone synthesis. We evaluated the safety and efficacy of a novel aldosterone synthase inhibitor, dexfadrostat phosphate, in patients with PA. Methods: This multi-centre, randomised, phase 2 trial was conducted between November 2019 and May 2022 (NCT04007406; EudraCT code 2019-000919-85). Adults with PA and an office systolic blood pressure of 145-190 mmHg were included. After a 2-week single-blind placebo run-in period, participants were randomised 1:1:1 to receive oral dexfadrostat phosphate 4, 8, or 12 mg once daily for an 8-week double-blind treatment period, followed by a 2-week single-blind placebo withdrawal period. Randomisation was conducted centrally and stratified by centre and sex. At the beginning and end of the treatment period, 24 h ambulatory systolic blood pressure (aSBP) was recorded. Blood samples were taken every 2 weeks. Primary endpoints were the change in aldosterone-to-renin ratio (ARR) and mean 24 h aSBP from baseline to the end of the treatment period in the combined dose group of all participants receiving any dose of dexfadrostat phosphate. Safety endpoints were the occurrence of treatment-emergent adverse events (TEAEs) and serious adverse events over the entire study in all randomised participants who received at least one dose of dexfadrostat phosphate. Findings: In total, 35 participants received dexfadrostat phosphate and all participants completed the study. Twenty-six participants (74.3%) were male, the mean age was 51.9 years (SD 8.7), and most were White (n = 32, 91.4%). The median ARR and the mean 24 h aSBP significantly decreased from the beginning to the end of the treatment period in the combined dose group (ARR: 15.3 vs 0.6, least-squares mean [LSM] change in log-normal values -2.5, p < 0.0001; aSBP: 142.6 vs 131.9 mmHg, LSM change -10.7 mmHg, p < 0.0001). There were no safety concerns; all TEAEs were mild or moderate and there were no serious TEAEs. Interpretation: Dexfadrostat phosphate corrected the ARR and aSBP and was well tolerated in patients with PA, demonstrating the benefit of pharmacologically targeting the source of hyperaldosteronism. Funding: DAMIAN Pharma AG.

Rapid surface-biostructure interaction analysis using strong metal-based nanomagnets.

Nanomaterials are increasingly suggested for the selective adsorption and extraction of complex compounds in biomedicine. Binding of the latter requires specific surface modifications of the nanostructures. However, even complicated macromolecules such as proteins can afford affinities toward basic surface characteristics such as hydrophobicity, topology, and electrostatic charge. In this study, we address these more basic physical interactions. In a model system, the interaction of bovine serum albumin and amyloid ß 42 fibrillar aggregates with carbon-coated cobalt nanoparticles, functionalized with various polymers differing in character, was studied. The possibility of rapid magnetic separation upon binding to the surface represents a valuable tool for studying surface interactions and selectivities. We find that the surface interaction of Aß 42 fibrillar aggregates is mostly hydrophobic in nature. Because bovine serum albumin (BSA) is conformationally adaptive, it is known to bind surfaces with widely differing properties (charge, topology, and hydrophobicity). However, the rate of tight binding (no desorption upon washing) can vary largely depending on the extent of necessary conformational changes for a specific surface. We found that BSA can only bind slowly to polyethylenimine-coated nanomagnets. Under competitive conditions (high excess BSA compared to that for ß 42 fibrillar aggregates), this effect is beneficial for targeting the fibrillar species. These findings highlight the possibility of selective extractions from complex media when advantageous basic physical surface properties are chosen.

Structural and clinical characterization of CYP11B2 inhibition by dexfadrostat phosphate.

Aldosterone synthase (CYP11B2) represents a promising drug target because its genetic dysregulation is causally associated with cardiovascular disease, its autonomous activity leads to primary aldosteronism, and its deficiency leads to salt wasting syndromes. The serendipitous discovery that the dextro-rotatory stereoisomer of the racemic aromatase (CYP19A1) inhibitor CGS16949A mediates potent CYP11B2 inhibition led to the purification and clinical development of dexfadrostat phosphate. To characterize the pharmacophore of dexfadrostat phosphate, structure-based enzyme coordination with CYP11B2, CYP11B1 and CYP19A1 was combined with steroid turnover upon in vitro and clinical treatment. Dexfadrostat, but not its 5S-enantiomer (5S-fadrozole), precisely coordinates with the catalytic heme moiety in the space of the CYP11B2 substrate binding pocket forming a tight and stable complex. Conversely, neither rigid nor flexible docking led to a plausible coordination geometry for dexfadrostat in steroid 11ß-hydroxylase (CYP11B1 - orthologue to CYP11B2) or in CYP19A1. The inhibitory preference of dexfadrostat was confirmed in vitro using an adrenal cortex-derived cell line. Dexfadrostat phosphate treatment of healthy subjects in the context of a clinical phase 1 study led to a dose-dependent decrease in urinary aldosterone secretion, accompanied by an increase in urinary corticosterone and deoxycorticosterone metabolites. Increased urinary corticosterone metabolites are indicative of CYP11B2 (18-oxidase) inhibition with clinical features reminiscent of patients with inborn corticosterone methyloxidase type II deficiency. An off-target effect on CYP19A1 was not observed as indicated by no clinical changes in testosterone and estradiol levels. Therefore, dexfadrostat exhibits the ideal structural features for binding and catalytic inhibition of CYP11B2 but not CYP11B1. Clinically, treatment with dexfadrostat phosphate leads to suppression of aldosterone levels by inhibiting predominantly one or both final CYP11B2-mediated reactions.

Adenocarcinomas of the esophagogastric junction are more likely to respond to preoperative chemotherapy than distal gastric cancer.

BACKGROUND: Preoperative chemotherapy has been shown to improve outcome of patients with adenocarcinoma of the esophagogastric junction (AEG) and gastric cancer (GC), and histopathologic response has been identified as an independent prognostic parameter in these patients. A recent meta-analysis has identified patients with AEG as benefiting more from preoperative chemotherapy than patients with GC. The aim of this retrospective analysis was to prove these findings in an experienced single-center large patient cohort because there are currently no recruiting prospective clinical trials. METHODS: In a single center, 551 patients underwent preoperative platin-based chemotherapy followed by oncologic surgery for locally advanced AEG and GC. Pretherapeutic clinical parameters were correlated with histopathologic response to preoperative chemotherapy. RESULTS: Histopathologic response (<10% of residual tumor) was found in 130 patients (24%) and was significantly correlated with overall survival (P<0.0001). Tumor localization at the esophagogastric junction (GE junction), lower baseline cT stage, and baseline cN0 stage were significantly associated with histopathologic response (P=0.034, P=0.015, and P=0.002, respectively). In subgroup analyses, the latter two predictive parameters were confirmed only for AEG (n=378) but not for other GC (n=173). AEG patients who were pretherapeutically staged as having cT3/4, cN0 disease (n=73) were identified as the subgroup with the highest rate of histopathologic response (48%). CONCLUSIONS: AEG is more likely to respond to preoperative chemotherapy than GC, a finding that might help identify patients who would benefit from preoperative chemotherapy.

Physical defect formation in few layer graphene-like carbon on metals: influence of temperature, acidity, and chemical functionalization.

A systematical examination of the chemical stability of cobalt metal nanomagnets with a graphene-like carbon coating is used to study the otherwise rather elusive formation of nanometer-sized physical defects in few layer graphene as a result of acid treatments. We therefore first exposed the core-shell nanomaterial to well-controlled solutions of altering acidity and temperature. The release of cobalt into these solutions over time offered a simple tool to monitor the progress of particle degradation. The results suggested that the oxidative damage of the graphene-like coatings was the rate-limiting step during particle degradation since only fully intact or entirely emptied carbon shells were found after the experiments. If ionic noble metal species were additionally present in the acidic solutions, the noble metal was found to reduce on the surface of specific, defective particles. The altered electrochemical gradients across the carbon shells were however not found to lead to a faster release of cobalt from the particles. The suggested mechanistic insight was further confirmed by the covalent chemical functionalization of the particle surface with chemically inert aryl species, which leads to an additional thickening of the shells. This leads to reduced cobalt release rates as well as slower noble metal reduction rates depending on the augmentation of the shell thickness.

Effects of flame made zinc oxide particles in human lung cells - a comparison of aerosol and suspension exposures.

BACKGROUND: Predominantly, studies of nanoparticle (NPs) toxicology in vitro are based upon the exposure of submerged cell cultures to particle suspensions. Such an approach however, does not reflect particle inhalation. As a more realistic simulation of such a scenario, efforts were made towards direct delivery of aerosols to air-liquid-interface cultivated cell cultures by the use of aerosol exposure systems.This study aims to provide a direct comparison of the effects of zinc oxide (ZnO) NPs when delivered as either an aerosol, or in suspension to a triple cell co-culture model of the epithelial airway barrier. To ensure dose-equivalence, ZnO-deposition was determined in each exposure scenario by atomic absorption spectroscopy. Biological endpoints being investigated after 4 or 24h incubation include cytotoxicity, total reduced glutathione, induction of antioxidative genes such as heme-oxygenase 1 (HO-1) as well as the release of the (pro)-inflammatory cytokine TNFα. RESULTS: Off-gases released as by-product of flame ZnO synthesis caused a significant decrease of total reduced GSH and induced further the release of the cytokine TNFα, demonstrating the influence of the gas phase on aerosol toxicology. No direct effects could be attributed to ZnO particles. By performing suspension exposure to avoid the factor "flame-gases", particle specific effects become apparent. Other parameters such as LDH and HO-1 were not influenced by gaseous compounds: Following aerosol exposure, LDH levels appeared elevated at both timepoints and the HO-1 transcript correlated positively with deposited ZnO-dose. Under submerged conditions, the HO-1 induction scheme deviated for 4 and 24h and increased extracellular LDH was found following 24h exposure. CONCLUSION: In the current study, aerosol and suspension-exposure has been compared by exposing cell cultures to equivalent amounts of ZnO. Both exposure strategies differ fundamentally in their dose-response pattern. Additional differences can be found for the factor time: In the aerosol scenario, parameters tend to their maximum already after 4h of exposure, whereas under submerged conditions, effects appear most pronounced mainly after 24h. Aerosol exposure provides information about the synergistic interplay of gaseous and particulate phase of an aerosol in the context of inhalation toxicology. Exposure to suspensions represents a valuable complementary method and allows investigations on particle-associated toxicity by excluding all gas-derived effects.

Hopping on the methadone bus.

This paper investigates the impact of a 'free drug program' on the market equilibrium of drugs. We introduce a screening model of the hard drug market in which dealers use payment and punishment options to screen between high and low risk users. We show that, if a free drug program selects sufficiently many high-risk drug users, the pure-strategy separating market equilibrium ceases to exist and a symmetric mixed-strategy equilibrium results, in which drug users derive a higher expected utility. This encourages new drug users to enter the market. The novelty of the paper is the transmission mechanism for this effect, which is via the influence on market price.

In vivo risk evaluation of carbon-coated iron carbide nanoparticles based on short- and long-term exposure scenarios.

BACKGROUND: While carbon-encapsulated iron carbide nanoparticles exhibit strong magnetic properties appealing for biomedical applications, potential side effects of such materials remain comparatively poorly understood. Here, we assess the effects of iron-based nanoparticles in an in vivo long-term study in mice with observation windows between 1 week and 1 year. MATERIALS & METHODS: Functionalized (PEG or IgG) carbon-encapsulated platinum-spiked iron carbide nanoparticles were injected intravenously in mice (single or repeated dose administration). RESULTS: One week after administration, magnetic nanoparticles were predominantly localized in organs of the reticuloendothelial system, particularly the lung and liver. After 1 year, particles were still present in these organs, however, without any evident tissue alterations, such as inflammation, fibrosis, necrosis or carcinogenesis. Importantly, reticuloendothelial system organs presented with normal function. CONCLUSION: This long-term exposure study shows high in vivo compatibility of intravenously applied carbon-encapsulated iron nanoparticles suggesting continuing investigations on such materials for biomedical applications.

Adsorption and separation of amyloid beta aggregates using ferromagnetic nanoparticles coated with charged polymer brushes.

Amyloid beta (Aß) protein aggregates, which include fibrils and oligomers, are neurotoxic and are considered to cause Alzheimer's disease. Thus, separation of these Aß aggregates from biological samples is important. Herein, we report the use of strongly ferromagnetic few-layer graphene-coated magnetic nanoparticles (C/Co), which were functionalized with a cationic polymer, poly[3-(methacryloyl amino)propyl]trimethylammonium chloride (polyMAPTAC), C/Co@polyMAPTAC, for the adsorption and magnetic separation of Aß aggregates. Fast adsorption (∼1 min) of Aß fibrils and oligomers onto the particles was observed. Interestingly, the Aß monomer was not captured by the particles, suggesting that binding to Aß molecules is toxic species-selective. Selective adsorption was also observed in the presence of serum albumin protein. We also showed that C/Co@polyMAPTAC could reduce the cytotoxicity of the Aß aggregate solutions. This study should be useful for further elucidation of the application of nanoparticle adsorption in mediating Aß toxicity.

Template-particle stabilized bicontinuous emulsion yielding controlled assembly of hierarchical high-flux filtration membranes.

A novel solvent-evaporation-based process that exploits template-particle stabilized bicontinuous emulsions for the formation of previously unreached membrane morphologies is reported in this article. Porous membranes have a wide range of applications spanning from water filtration, pharmaceutical purification, and battery separators to scaffolds for tissue engineering. Different situations require different membrane morphologies including various pore sizes and pore gradients. However, most of the previously reported membrane preparation procedures are restricted to specific morphologies and morphology alterations require an extensive optimization process. The tertiary system presented in this article, which consists of a poly(ether sulfone)/dimethylacetamide (PES/DMAc) solution, glycerol, and ZnO-nanoparticles, allows simple and exact tuning of pore diameters ranging from sub-20 nm, up to 100 nm. At the same time, the pore size gradient is controlled from 0 up to 840%/µm yielding extreme asymmetry. In addition to structural analysis, water flux rates of over 5600 L m(-2) h(-1) are measured for membranes retaining 45 nm silica beads.

Uptake of ferromagnetic carbon-encapsulated metal nanoparticles in endothelial cells: influence of shear stress and endothelial activation.

AIM: Magnetic field guided drug targeting holds promise for more effective cancer treatment. Intravascular application of magnetic nanoparticles, however, bears the risk of potentially important, yet poorly understood side effects, such as off-target accumulation in endothelial cells. MATERIALS & METHODS: Here, we investigated the influence of shear stress (0-3.22 dyn/cm(2)), exposure time (5-30 min) and endothelial activation on the uptake of ferromagnetic carbon-encapsulated iron carbide nanomagnets into endothelial cells in an in vitro flow cell model. RESULTS: We found that even moderate shear stresses typically encountered in the venous system strongly reduce particle uptake compared with static conditions. Interestingly, a pronounced particle uptake was observed in inflamed endothelial cells. CONCLUSION: This study highlights the importance of relevant exposure scenarios accounting for physiological conditions when studying particle-cell interactions as, for example, shear stress and endothelial activation are major determinants of particle uptake. Such considerations are of particular importance with regard to successful translation of in vitro findings into (pre-)clinical end points.

Structural components of SCAN-domain dimerizations.

The SCAN or leucine-rich domain has been characterized as a highly conserved sequence in zinc finger transcription factors that mediates selective dimer formation between SCAN-domain-containing proteins. In order to accommodate various SCAN-domain sequence features, a minimal functional folding unit was defined on the premise of proper structural folding and biochemical binding. The 58-amino acid minimal functional units derived from each of four SCAN-domain protein families were subjected to a three-dimensional position-specific scoring matrix (3D-PSSM) and ungapped threading analysis. The resulting fold prediction represented the SCAN-domain's minimal functional unit as a bundle of three alpha helices folded to a core structure. In addition, the minimal functional folding unit biochemically retained the selective dimerization properties of the native proteins. In order to elucidate the structural components within the SCAN-domain that engage in binding interactions, we attempted to correlate the physicochemical helix properties, as represented by a hydropathy profile, with the experimental dimerization selectivities. The amino-terminal helix revealed the highest diversity measure among the three helices of the minimal functional unit and is therefore likely to offer critical surface-exposed binding residues. Indeed, by interchanging the amino-terminal helix between SCAN-domains without alteration of their structural frames consisting of conserved hydrophobic residues, a modulation of binding preferences was demonstrated. The minimal functional folding unit of SCAN-domains may therefore contain within the amino-terminal alpha helix structural components that determine selective dimerization patterns and combinatorial control of transcription factors.

Characterization of carbon-coated magnetic nanoparticles using clinical blood coagulation assays: effect of PEG-functionalization and comparison to silica nanoparticles.

Intravascular application of magnetic nanocarriers is a critical step in the development of new therapeutic strategies, including magnetic drug targeting or hyperthermia. However, injection of particulate matter bears the intrinsic risk of contact activation of the blood coagulation cascade. In this work, we use point-of-care assays to study coagulation dynamics and clotting parameters in blood samples exposed to relevant concentrations of surface-functionalized carbon-coated iron carbide nanomagnets using unmodified nanomagnets and poly(ethylene)glycol-functionalized nanomagnets with different end-groups, including -OCH3, -NH2, -COOH, -IgG, and -ProteinA-protected-IgG (-IgG-ProtA). Silica nanoparticles with a comparable surface area are used as a reference material. For magnetic nanoparticles, we observe a decrease in clotting time by 25% compared to native blood at concentrations of 1 mg mL-1, independent of the surface functionalization, and only minor differences in receptor expression on platelets (GP-IIb-IIIa, CD62, and CD63) relative to control samples were observed. Interestingly, the inter-subject variance of the clotting time is similar to the nanoparticle-induced effect in a single subject with average clotting time. Whilst the present study is based on in vitro assays and a small group of healthy blood donors, the comparison to broadly used silica nanoparticles, and the fact that experimental intergroup variability is comparable to the observed effects from the carbon-coated nanomagnets suggests continuing investigations on their potential clinical use.

Aldosterone synthase inhibition for the treatment of hypertension and the derived mechanistic requirements for a new therapeutic strategy.

CONTEXT: We describe the clinical investigation of the first generation aldosterone synthase inhibitor, LCI699, in patients with essential, uncontrolled, resistant, or secondary hypertension. LCI699 competitively reduced blood pressure at lower doses yet counterintuitive effects were observed at higher doses. OBJECTIVE AND METHOD: An extensive endocrine biomarker analysis was performed to better understand the pharmacological mechanism of the drug. RESULTS: The interference of LCI699 in the renin-angiotensin-aldosterone system occurred with limited target selectivity, as a dose-dependent compensatory stimulation of the hypothalamic-pituitary-adrenal feedback axis was discovered. Thus, LCI699 affected two endocrine feedback loops that converged at a single point, inhibiting the 11ß-hydroxylase reaction in the adrenal gland, leading to supraphysiological levels of 11-deoxycortiscosterone. The accumulation of this potent mineralocorticoid may explain the blunted blood pressure response to LCI699. CONCLUSION: Future aldosterone synthase inhibitors may improve their target selectivity by sparing the 11ß-hydroxylase reaction and preferentially inhibiting one of the two other enzymatic reactions mediated by aldosterone synthase.