Dextromethorphan-bupropion (Auvelity) for the Treatment of Major Depressive Disorder.

Depression is a significant cause of morbidity and mortality globally. Although various pharmacologic options exist for depression, treatments are limited by delayed or incomplete therapeutic response, low rates of remission, and adverse effects necessitating effective, fast-acting, and better tolerated alternatives. The purpose of this review is to describe the safety and efficacy of dextromethorphan-bupropion (Auvelity), a Food and Drug Administration approved treatment for major depressive disorder in adults. Dextromethorphan modulates glutamate signaling through uncompetitive antagonism of N-methyl-D-aspartate receptors and sigma-1 agonism, while bupropion increases the bioavailability of dextromethorphan by CYP2D6 inhibition. In a phase 3 trial with dextromethorphan-bupropion 45-105 mg for patients with major depressive disorder saw significant reductions in their Montgomery-Åsberg Depression Rating Scale total scores compared to placebo. A phase 2 trial comparing dextromethorphan-bupropion 45-105 mg to bupropion monotherapy led to significant reduction in Montgomery-Åsberg Depression Rating Scale score. Changes in Montgomery-Åsberg Depression Rating Scale with dextromethorphan-bupropion were seen within two weeks in both clinical trials. Remission and response rates were significantly higher with dextromethorphan-bupropion in both studies. The medication was well-tolerated in both trials, with the most common adverse events being rated as mild-to-moderate. Two long-term, open-label studies with dextromethorphan-bupropion saw large reductions in Montgomery-Åsberg Depression Rating Scale scores that were maintained through 12 and 15 months of treatment. In both long-term studies, remission rates approached 70%, while response rates were greater than 80%. These data suggest that dextromethorphan-bupropion is an effective, fast-acting, and well tolerated option for depression treatment and produced remission in a large percentage of patients.

Molecular Catalysis of Energy Relevance in Metal-Organic Frameworks: From Higher Coordination Sphere to System Effects.

The modularity and synthetic flexibility of metal-organic frameworks (MOFs) have provoked analogies with enzymes, and even the term MOFzymes has been coined. In this review, we focus on molecular catalysis of energy relevance in MOFs, more specifically water oxidation, oxygen and carbon dioxide reduction, as well as hydrogen evolution in context of the MOF-enzyme analogy. Similar to enzymes, catalyst encapsulation in MOFs leads to structural stabilization under turnover conditions, while catalyst motifs that are synthetically out of reach in a homogeneous solution phase may be attainable as secondary building units in MOFs. Exploring the unique synthetic possibilities in MOFs, specific groups in the second and third coordination sphere around the catalytic active site have been incorporated to facilitate catalysis. A key difference between enzymes and MOFs is the fact that active site concentrations in the latter are often considerably higher, leading to charge and mass transport limitations in MOFs that are more severe than those in enzymes. High catalyst concentrations also put a limit on the distance between catalysts, and thus the available space for higher coordination sphere engineering. As transport is important for MOF-borne catalysis, a system perspective is chosen to highlight concepts that address the issue. A detailed section on transport and light-driven reactivity sets the stage for a concise review of the currently available literature on utilizing principles from Nature and system design for the preparation of catalytic MOF-based materials.

Fast charging of energy-dense lithium-ion batteries.

Lithium-ion batteries with nickel-rich layered oxide cathodes and graphite anodes have reached specific energies of 250-300 Wh kg-1 (refs. 1,2), and it is now possible to build a 90 kWh electric vehicle (EV) pack with a 300-mile cruise range. Unfortunately, using such massive batteries to alleviate range anxiety is ineffective for mainstream EV adoption owing to the limited raw resource supply and prohibitively high cost. Ten-minute fast charging enables downsizing of EV batteries for both affordability and sustainability, without causing range anxiety. However, fast charging of energy-dense batteries (more than 250 Wh kg-1 or higher than 4 mAh cm-2) remains a great challenge3,4. Here we combine a material-agnostic approach based on asymmetric temperature modulation with a thermally stable dual-salt electrolyte to achieve charging of a 265 Wh kg-1 battery to 75% (or 70%) state of charge in 12 (or 11) minutes for more than 900 (or 2,000) cycles. This is equivalent to a half million mile range in which every charge is a fast charge. Further, we build a digital twin of such a battery pack to assess its cooling and safety and demonstrate that thermally modulated 4C charging only requires air convection. This offers a compact and intrinsically safe route to cell-to-pack development. The rapid thermal modulation method to yield highly active electrochemical interfaces only during fast charging has important potential to realize both stability and fast charging of next-generation materials, including anodes like silicon and lithium metal.

Pharmacokinetic, pharmacodynamic, and transcriptomic analysis of chronic levetiracetam treatment in 5XFAD mice: A MODEL-AD preclinical testing core study.

Introduction: Hyperexcitability and epileptiform activity are commonplace in Alzheimer's disease (AD) patients and associated with impaired cognitive function. The anti-seizure drug levetiracetam (LEV) is currently being evaluated in clinical trials for ability to reduce epileptiform activity and improve cognitive function in AD. The purpose of our studies was to establish a pharmacokinetic/pharmacodynamic (PK/PD) relationship with LEV in an amyloidogenic mouse model of AD to enable predictive preclinical to clinical translation, using the rigorous preclinical testing pipeline of the Model Organism Development and Evaluation for Late-Onset Alzheimer's Disease Preclinical Testing Core. Methods: A multi-tier approach was applied that included quality assurance and quality control of the active pharmaceutical ingredient, PK/PD modeling, positron emission tomography/magnetic resonance imaging (PET/MRI), functional outcomes, and transcriptomics. 5XFAD mice were treated chronically with LEV for 3 months at doses in line with those allometrically scaled to the clinical dose range. Results: Pharmacokinetics of LEV demonstrated sex differences in Cmax, AUC0-∞, and CL/F, and a dose dependence in AUC0-∞. After chronic dosing at 10, 30, 56 mg/kg, PET/MRI tracer 18F-AV45, and 18F-fluorodeoxyglucose (18F-FDG) showed specific regional differences with treatment. LEV did not significantly improve cognitive outcomes. Transcriptomics performed by nanoString demonstrated drug- and dose-related changes in gene expression relevant to human brain regions and pathways congruent with changes in 18F-FDG uptake. Discussion: This study represents the first report of PK/PD assessment of LEV in 5XFAD mice. Overall, these results highlighted non-linear kinetics based on dose and sex. Plasma concentrations of the 10 mg/kg dose in 5XFAD overlapped with human plasma concentrations used for studies of mild cognitive impairment, while the 30 and 56 mg/kg doses were reflective of doses used to treat seizure activity. Post-treatment gene expression analysis demonstrated LEV dose-related changes in immune function and neuronal-signaling pathways relevant to human AD, and aligned with regional 18F-FDG uptake. Overall, this study highlights the importance of PK/PD relationships in preclinical studies to inform clinical study design. Highlights: Significant sex differences in pharmacokinetics of levetiracetam were observed in 5XFAD mice.Plasma concentrations of 10 mg/kg levetiracetam dose in 5XFAD overlapped with human plasma concentration used in the clinic.Drug- and dose-related differences in gene expression relevant to human brain regions and pathways were also similar to brain region-specific changes in 18F-fluorodeoxyglucose uptake.

Circulating tumor and invasive cell expression profiling predicts effective therapy in pancreatic cancer.

BACKGROUND: Pancreatic adenocarcinoma (PDAC) remains a refractory disease; however, modern cytotoxic chemotherapeutics can induce tumor regression and extend life. A blood-based, pharmacogenomic, chemosensitivity assay using gene expression profiling of circulating tumor and invasive cells (CTICs) to predict treatment response was previously developed. The combination regimen of 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) and gemcitabine/nab-paclitaxel (G/nab-P) are established frontline approaches for treating advanced PDAC; however, there are no validated biomarkers for treatment selection. A similar unmet need exists for choosing second-line therapy. METHODS: The chemosensitivity assay was evaluated in metastatic PDAC patients presenting for frontline treatment. A prospective study enrolled patients (n = 70) before receiving either FOLFIRINOX or G/nab-P at a 1:1 ratio. Six milliliters of peripheral blood was collected at baseline and at time of disease progression. CTICs were isolated, gene-expression profiling was performed, and the assay was used to predict effective and ineffective chemotherapeutic agents. Treating physicians were blinded to the assay prediction results. RESULTS: Patients receiving an effective regimen as predicted by the chemosensitivity assay experienced significantly longer median progression-free survival (mPFS; 7.8 months vs. 4.2 months; hazard ratio [HR], 0.35; p = .0002) and median overall survival (mOS; 21.0 months vs. 9.7 months; HR, 0.40; p = .005), compared with an ineffective regimen. Assay prediction for effective second-line therapy was explored. The entire study cohort experienced favorable outcomes compared with historical controls, 7.1-month mPFS and 12.3-month mOS. CONCLUSIONS: Chemosensitivity assay profiling is a promising tool for guiding therapy in advanced PDAC. Further prospective validation is under way (clinicaltrials.gov NCT03033927).

ChemoSensitivity Assay Guided Metronomic Chemotherapy Is Safe and Effective for Treating Advanced Pancreatic Cancer.

Cytotoxic chemotherapy remains the mainstay of treatment for advanced pancreatic adenocarcinoma (PDAC). Emerging studies support metronomic chemotherapy (MCT) as effective, challenging established paradigms of dosing and schedules. The blood-based ChemoSensitivity Assay has been shown to predict response and survival in advanced PDAC patients treated with standard chemotherapy. The current study combines these concepts for a highly personalized treatment approach. This was a retrospective analysis; a pilot (n = 50) and validation cohort (n = 45) were studied. The ChemoSensitivity Assay was performed at baseline and during therapy; results were correlated to drugs administered and patient outcomes. MCT was administered based on the assay results at the treating physician's discretion. Patients in the pilot cohort experienced favorable survival compared with historical controls (median overall survival (mOS) 16.8 mo). Patients whose treatment closely matched the ChemoSensitivity Assay predictions experienced longer median time on lines of therapy (5.3 vs. 3.3 mo, p = 0.02) and showed a trend for longer mOS (20.9 vs. 12.5 mo, p = 0.055) compared with those not closely matched. These findings were confirmed in the validation cohort. Overall, patients treated with MCT closely matching Assay results experienced a remarkable mOS of 27.7 mo. ChemoSensitivity profiling-guided MCT is a promising approach for personalized therapy in advanced PDAC.

Elemental Depth Profiling of Intact Metal-Organic Framework Single Crystals by Scanning Nuclear Microprobe.

The growing field of MOF-catalyst composites often relies on postsynthetic modifications for the installation of active sites. In the resulting MOFs, the spatial distribution of the inserted catalysts has far-reaching ramifications for the performance of the system and thus needs to be precisely determined. Herein, we report the application of a scanning nuclear microprobe for accurate and nondestructive depth profiling of individual UiO-66 and UiO-67 (UiO = Universitetet i Oslo) single crystals. Initial optimization work using native UiO-66 crystals yielded a microbeam method which avoided beam damage, while subsequent analysis of Zr/Hf mixed-metal UiO-66 crystals demonstrated the potential of the method to obtain high-resolution depth profiles. The microbeam method was further used to analyze the depth distribution of postsynthetically introduced organic moieties, revealing either core-shell or uniform incorporation can be obtained depending on the size of the introduced molecule, as well as the number of carboxylate binding groups. Finally, the spatial distribution of platinum centers that were postsynthetically installed in the bpy binding pockets of UiO-67-bpy (bpy = 5,5'-dicarboxyy-2,2'-bipyridine) was analyzed by microbeam and contextualized. We expect that the method presented herein will be applicable for characterizing a wide variety of MOFs subjected to postsynthetic modifications and provide information crucial for their optimization as functional materials.

Enhancing photovoltages at p-type semiconductors through a redox-active metal-organic framework surface coating.

Surface modification of semiconductors can improve photoelectrochemical performance by promoting efficient interfacial charge transfer. We show that metal-organic frameworks (MOFs) are viable surface coatings for enhancing cathodic photovoltages. Under 1-sun illumination, no photovoltage is observed for p-type Si(111) functionalized with a naphthalene diimide derivative until the monolayer is expanded in three dimensions in a MOF. The surface-grown MOF thin film at Si promotes reduction of the molecular linkers at formal potentials >300 mV positive of their thermodynamic potentials. The photocurrent is governed by charge diffusion through the film, and the MOF film is sufficiently conductive to power reductive transformations. When grown on GaP(100), the reductions of the MOF linkers are shifted anodically by >700 mV compared to those of the same MOF on conductive substrates. This photovoltage, among the highest reported for GaP in photoelectrochemical applications, illustrates the power of MOF films to enhance photocathodic operation.

Transport Phenomena: Challenges and Opportunities for Molecular Catalysis in Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are appealing heterogeneous support matrices that can stabilize molecular catalysts for the electrochemical conversion of small molecules. However, moving from a homogeneous environment to a porous film necessitates the transport of both charge and substrate to the catalytic sites in an efficient manner. This presents a significant challenge in the application of such materials at scale, since these two transport phenomena (charge and mass transport) would need to operate faster than the intrinsic catalytic rate in order for the system to function efficiently. Thus, understanding the fundamental kinetics of MOF-based molecular catalysis of electrochemical reactions is of crucial importance. In this Perspective, we quantitatively dissect the interplay between the two transport phenomena and the catalytic reaction rate by applying models from closely related fields to MOF-based catalysis. The identification of the limiting process provides opportunities for optimization that are uniquely suited to MOFs due to their tunable molecular structure. This will help guide the rational design of efficient and high-performing catalytic MOF films with incorporated molecular catalyst for electrochemical energy conversion.

Analysis of Electrocatalytic Metal-Organic Frameworks.

The electrochemical analysis of molecular catalysts for the conversion of bulk feedstocks into energy-rich clean fuels has seen dramatic advances in the last decade. More recently, increased attention has focused on the characterization of metal-organic frameworks (MOFs) containing well-defined redox and catalytically active sites, with the overall goal to develop structurally stable materials that are industrially relevant for large-scale solar fuel syntheses. Successful electrochemical analysis of such materials draws heavily on well-established homogeneous techniques, yet the nature of solid materials presents additional challenges. In this tutorial-style review, we cover the basics of electrochemical analysis of electroactive MOFs, including considerations of bulk stability, methods of attaching MOFs to electrodes, interpreting fundamental electrochemical data, and finally electrocatalytic kinetic characterization. We conclude with a perspective of some of the prospects and challenges in the field of electrocatalytic MOFs.

Computational fluid dynamic analysis of bioprinted self-supporting perfused tissue models.

Natural tissues are incorporated with vasculature, which is further integrated with a cardiovascular system responsible for driving perfusion of nutrient-rich oxygenated blood through the vasculature to support cell metabolism within most cell-dense tissues. Since scaffold-free biofabricated tissues being developed into clinical implants, research models, and pharmaceutical testing platforms should similarly exhibit perfused tissue-like structures, we generated a generalizable biofabrication method resulting in self-supporting perfused (SSuPer) tissue constructs incorporated with perfusible microchannels and integrated with the modular FABRICA perfusion bioreactor. As proof of concept, we perfused an MLO-A5 osteoblast-based SSuPer tissue in the FABRICA. Although our resulting SSuPer tissue replicated vascularization and perfusion observed in situ, supported its own weight, and stained positively for mineral using Von Kossa staining, our in vitro results indicated that computational fluid dynamics (CFD) should be used to drive future construct design and flow application before further tissue biofabrication and perfusion. We built a CFD model of the SSuPer tissue integrated in the FABRICA and analyzed flow characteristics (net force, pressure distribution, shear stress, and oxygen distribution) through five SSuPer tissue microchannel patterns in two flow directions and at increasing flow rates. Important flow parameters include flow direction, fully developed flow, and tissue microchannel diameters matched and aligned with bioreactor flow channels. We observed that the SSuPer tissue platform is capable of providing direct perfusion to tissue constructs and proper culture conditions (oxygenation, with controllable shear and flow rates), indicating that our approach can be used to biofabricate tissue representing primary tissues and that we can model the system in silico.

Facile Orientational Control of M2L2P SURMOFs on ⟨100⟩ Silicon Substrates and Growth Mechanism Insights for Defective MOFs.

Layer-by-layer growth of Cu2(bdc)2(dabco) surface-mounted metal-organic frameworks (SURMOFs) was investigated on silicon wafers treated with different surface anchoring molecules. Well-oriented growth along the [100] and [001] directions could be achieved with simple protocols: growth along the [100] direction was achieved by substrate pretreatment with 80 °C piranha, while growth along the [001] direction was enabled by only rinsing silicon with absolute ethanol. Growth along the [001] direction produced more homogeneous SURMOF films. Optimization to enhance [001]-preferred orientation growth revealed that small changes in the SURMOF growth sequence (the number of rinse steps and linker concentrations) have a noticeable impact on the final film quality and the number of misaligned crystals. This new straightforward protocol was used to successfully grow other layer pillar-type SURMOFs, including the growth of Cu2(bdc)2(bipy) with simultaneous suppression of framework interpenetration.

On decomposition, degradation, and voltammetric deviation: the electrochemist's field guide to identifying precatalyst transformation.

What is the identity of the true electrocatalytic species? This fundamental question has plagued the molecular electrocatalysis community during its decades-long search for selective and efficient transition-metal based electrocatalysts for fuel forming reactions. Identifying when the added species is a precatalyst that transforms into the active catalyst in situ is an extraordinarily complex endeavor. Thankfully, the last decade has witnessed a resurgence of interest in understanding and controlling these transformations, leading to an expansion of the experimental toolkit available to probe catalyst identity. In this Tutorial Review, researchers will learn how the nature of the active catalyst can be uncovered using state-of-the-art electrochemical and spectroscopic methods. Analysis of catalytic voltammograms can quickly furnish qualitative evidence of precatalyst transformation and a library of these tell-tale signs is discussed, along with the chemical phenomena underpinning each feature. Complementary electrochemical and spectroscopic methods for identifying in situ generation of heterogeneous catalysts are also presented, outlining the conditions required for correct application with special emphasis on potential pitfalls when studying weakly-adsorbed material. Case studies are presented to showcase how these different probes can be integrated to develop a comprehensive picture of precatalyst transformation.

Decoding Proton-Coupled Electron Transfer with Potential-p Ka Diagrams: Applications to Catalysis.

The applied potential at which [NiII(P2PhN2Bn)2]2+ (P2PhN2Bn = 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) catalyzes hydrogen production is reported to vary as a function of proton source p Ka in acetonitrile. By contrast, most molecular catalysts exhibit catalytic onsets at p Ka-independent potentials. Using experimentally determined thermochemical parameters associated with reduction and protonation, a coupled Pourbaix diagram is constructed for [NiII(P2PhN2Bn)2]2+. One layer describes proton-coupled electron transfer reactivity involving ligand-based protonation, and the second describes metal-based protonation. An overlay of this diagram with experimentally determined E cat/2 values spanning 15 p Ka units, along with complementary stopped-flow rapid mixing experiments to detect reaction intermediates, supports a mechanism in which the proton-coupled electron transfer processes underpinning the p Ka-dependent catalytic processes involve protonation of the ligand, not the metal center. For proton sources with p Ka values in the range 6-10.6, the initial species formed is the doubly reduced, doubly protonated species [Ni0(P2PhN2BnH)2]2+, despite a higher overpotential for this proton-coupled electron transfer reaction in comparison to forming the metal-protonated isomer. In this complex, each ligand is protonated in the exo position with the two amine moieties on each ligand binding a single proton and positioning it away from the metal center. This species undergoes very slow isomerization to form an endo-protonated hydride species [HNiII(P2PhN2Bn)(P2PhN2BnH)]2+ that can release hydrogen to close the catalytic cycle. Importantly, this slow isomerization does not perturb the initially established proton-coupled electron transfer equilibrium, placing catalysis under thermodynamic control. New details revealed about the reaction mechanism from the coupled Pourbaix diagram and the complementary stopped-flow studies lead to predictions as to how this p Ka-dependent activity might be engendered in other molecular catalysts for multi-electron, multi-proton transformations.

Addressing the Third Delay in Saving Mothers, Giving Life Districts in Uganda and Zambia: Ensuring Adequate and Appropriate Facility-Based Maternal and Perinatal Health Care.

BACKGROUND: Saving Mothers, Giving Life (SMGL) is a 5-year initiative implemented in participating districts in Uganda and Zambia that aimed to reduce deaths related to pregnancy and childbirth by targeting the 3 delays to receiving appropriate care: seeking, reaching, and receiving. Approaches to addressing the third delay included adequate health facility infrastructure, specifically sufficient equipment and medications; trained providers to provide quality evidence-based care; support for referrals to higher-level care; and effective maternal and perinatal death surveillance and response. METHODS: SMGL used a mixed-methods approach to describe intervention strategies, outcomes, and health impacts. Programmatic and monitoring and evaluation data-health facility assessments, facility and community surveillance, and population-based mortality studies-were used to document the effectiveness of intervention components. RESULTS: During the SMGL initiative, the proportion of facilities providing emergency obstetric and newborn care (EmONC) increased from 10% to 25% in Uganda and from 6% to 12% in Zambia. Correspondingly, the delivery rate occurring in EmONC facilities increased from 28.2% to 41.0% in Uganda and from 26.0% to 29.1% in Zambia. Nearly all facilities had at least one trained provider on staff by the endline evaluation. Staffing increases allowed a higher proportion of health centers to provide care 24 hours a day/7 days a week by endline-from 74.6% to 82.9% in Uganda and from 64.8% to 95.5% in Zambia. During this period, referral communication improved from 93.3% to 99.0% in Uganda and from 44.6% to 100% in Zambia, and data systems to identify and analyze causes of maternal and perinatal deaths were established and strengthened. CONCLUSION: SMGL's approach was associated with improvements in facility infrastructure, equipment, medication, access to skilled staff, and referral mechanisms and led to declines in facility maternal and perinatal mortality rates. Further work is needed to sustain these gains and to eliminate preventable maternal and perinatal deaths.

Hydrocephalus in a rat model of Meckel Gruber syndrome with a TMEM67 mutation.

Transmembrane protein 67 (TMEM67) is mutated in Meckel Gruber Syndrome type 3 (MKS3) resulting in a pleiotropic phenotype with hydrocephalus and renal cystic disease in both humans and rodent models. The precise pathogenic mechanisms remain undetermined. Herein it is reported for the first time that a point mutation of TMEM67 leads to a gene dose-dependent hydrocephalic phenotype in the Wistar polycystic kidney (Wpk) rat. Animals with TMEM67 heterozygous mutations manifest slowly progressing hydrocephalus, observed during the postnatal period and continuing into adulthood. These animals have no overt renal phenotype. The TMEM67 homozygous mutant rats have severe ventriculomegaly as well as severe polycystic kidney disease and die during the neonatal period. Protein localization in choroid plexus epithelial cells indicates that aquaporin 1 and claudin-1 both remain normally polarized in all genotypes. The choroid plexus epithelial cells may have selectively enhanced permeability as evidenced by increased Na+, K+ and Cl- in the cerebrospinal fluid of the severely hydrocephalic animals. Collectively, these results suggest that TMEM67 is required for the regulation of choroid plexus epithelial cell fluid and electrolyte homeostasis. The Wpk rat model, orthologous to human MKS3, provides a unique platform to study the development of both severe and mild hydrocephalus.

Post synthetic exchange enables orthogonal click chemistry in a metal organic framework.

Biphenyl-4,4'-dicarboxylic acid derivatives containing either azide or acetylene functional groups were inserted into UiO-67 metal organic frameworks (MOFs) via post synthetic linker exchange. Sequential and orthogonal click reactions could be performed on these modified MOFs by incubating the crystals with small molecule substrates bearing azide or acetylene groups in the presence of a copper catalyst. 1H NMR of digested MOF samples showed that up to 50% of the incorporated linkers could be converted to their "clicked" triazole products. Powder X-ray diffraction confirmed that the UiO-67 structure was maintained throughout all transformations. The click reaction efficiency is discussed in context of MOF crystallite size and pore size. As the incorporation of clicked linkers could be controlled by post synthetic exchange, this work introduces a powerful method of quickly introducing orthogonal modifications into known MOF architectures.

Circulating Tumor and Invasive Cell Gene Expression Profile Predicts Treatment Response and Survival in Pancreatic Adenocarcinoma.

Previous studies have shown that pharmacogenomic modeling of circulating tumor and invasive cells (CTICs) can predict response of pancreatic ductal adenocarcinoma (PDAC) to combination chemotherapy, predominantly 5-fluorouracil-based. We hypothesized that a similar approach could be developed to predict treatment response to standard frontline gemcitabine with nab-paclitaxel (G/nab-P) chemotherapy. Gene expression profiles for responsiveness to G/nab-P were determined in cell lines and a test set of patient samples. A prospective clinical trial was conducted, enrolling 37 patients with advanced PDAC who received G/nab-P. Peripheral blood was collected prior to treatment, after two months of treatment, and at progression. The CTICs were isolated based on a phenotype of collagen invasion. The RNA was isolated, cDNA synthesized, and qPCR gene expression analyzed. Patients were most closely matched to one of three chemotherapy response templates. Circulating tumor and invasive cells' SMAD4 expression was measured serially. The CTICs were reliably isolated and profiled from peripheral blood prior to and during chemotherapy treatment. Individual patients could be matched to distinct response templates predicting differential responses to G/nab-P treatment. Progression free survival was significantly correlated to response prediction and ΔSMAD4 was significantly associated with disease progression. These findings support phenotypic profiling and ΔSMAD4 of CTICs as promising clinical tools for choosing effective therapy in advanced PDAC, and for anticipating disease progression.

Excessive localized leukotriene B4 levels dictate poor skin host defense in diabetic mice.

Poorly controlled diabetes leads to comorbidities and enhanced susceptibility to infections. While the immune components involved in wound healing in diabetes have been studied, the components involved in susceptibility to skin infections remain unclear. Here, we examined the effects of the inflammatory lipid mediator leukotriene B4 (LTB4) signaling through its receptor B leukotriene receptor 1 (BLT1) in the progression of methicillin-resistant Staphylococcus aureus (MRSA) skin infection in 2 models of diabetes. Diabetic mice produced higher levels of LTB4 in the skin, which correlated with larger nonhealing lesion areas and increased bacterial loads compared with nondiabetic mice. High LTB4 levels were also associated with dysregulated cytokine and chemokine production, excessive neutrophil migration but impaired abscess formation, and uncontrolled collagen deposition. Both genetic deletion and topical pharmacological BLT1 antagonism restored inflammatory response and abscess formation, followed by a reduction in the bacterial load and lesion area in the diabetic mice. Macrophage depletion in diabetic mice limited LTB4 production and improved abscess architecture and skin host defense. These data demonstrate that exaggerated LTB4/BLT1 responses mediate a derailed inflammatory milieu that underlies poor host defense in diabetes. Prevention of LTB4 production/actions could provide a new therapeutic strategy to restore host defense in diabetes.

Macrophage-derived LTB4 promotes abscess formation and clearance of Staphylococcus aureus skin infection in mice.

The early events that shape the innate immune response to restrain pathogens during skin infections remain elusive. Methicillin-resistant Staphylococcus aureus (MRSA) infection engages phagocyte chemotaxis, abscess formation, and microbial clearance. Upon infection, neutrophils and monocytes find a gradient of chemoattractants that influence both phagocyte direction and microbial clearance. The bioactive lipid leukotriene B4 (LTB4) is quickly (seconds to minutes) produced by 5-lipoxygenase (5-LO) and signals through the G protein-coupled receptors LTB4R1 (BLT1) or BLT2 in phagocytes and structural cells. Although it is known that LTB4 enhances antimicrobial effector functions in vitro, whether prompt LTB4 production is required for bacterial clearance and development of an inflammatory milieu necessary for abscess formation to restrain pathogen dissemination is unknown. We found that LTB4 is produced in areas near the abscess and BLT1 deficient mice are unable to form an abscess, elicit neutrophil chemotaxis, generation of neutrophil and monocyte chemokines, as well as reactive oxygen species-dependent bacterial clearance. We also found that an ointment containing LTB4 synergizes with antibiotics to eliminate MRSA potently. Here, we uncovered a heretofore unknown role of macrophage-derived LTB4 in orchestrating the chemoattractant gradient required for abscess formation, while amplifying antimicrobial effector functions.