Cyclic Thiosulfinates as a Novel Class of Disulfide Cleavable Cross-Linkers for Rapid Hydrogel Synthesis.

We recently reported that cyclic thiosulfinates are cysteine selective cross-linkers that avoid the "dead-end" modifications that contribute to other cross-linkers' toxicity. In this study, we generalize the chemistry of cyclic thiosulfinates to that of thiol selective cross-linking and apply them to the synthesis of hydrogels. Thiol-functionalized four-arm poly(ethylene glycol) and hyaluronic acid monomers were cross-linked with 1,2-dithiane-1-oxide to form disulfide cross-linked hydrogels within seconds. The synthesized hydrogel could be reduced with physiological concentrations of glutathione, which modulated hydrogel mechanical properties and degradation kinetics. Bovine serum albumin protein was successfully encapsulated in hydrogel, and diffusion-mediated release was demonstrated in vitro. Hep G2 cells grew in the presence of preformed hydrogel and during hydrogel synthesis, demonstrating acceptable cytotoxicity. We encapsulated cells within a hydrogel and demonstrated cell growth and recovery up to 10 days, with and without cell adhesion peptides. In summary, we report cyclic thiosulfinates as a novel class of cross-linkers for the facile synthesis of biodegradable hydrogels.

The thermodynamics of guest complexation to octa-acid and tetra-endo-methyl octa-acid: reference data for the sixth statistical assessment of modeling of proteins and ligands (SAMPL6).

Although computer-aided drug design has greatly improved over time, its application in the pharmaceutical industry is still limited by the accuracy of association constant predictions. Towards improving this situation, the Statistical Assessment of the Modeling of Proteins and Ligands (SAMPL) is a series of community-wide blind challenges aimed to advance computational techniques as standard predictive tools in rational drug design (https://en.wikipedia.org/wiki/SAMPL_Challenge). As an empirical contribution to the sixth assessment (SAMPL6), we report here the association constant (Ka ) and thermodynamic parameters (∆G, ∆H, -T∆S) of eight guests (G0-G7) binding to two subtly different hosts (OA and TEMOA) using ITC. Both hosts contain a unique, well-defined binding pocket capable of storing guests with up to ten non-hydrogen atoms, whilst the selection of amphiphilic guests contain a range of saturated and unsaturated substituents from C6 to C10. The thermodynamic data from this study will allow the challenge participants of SAMPL6 to test the accuracy of their computational protocols for calculating host-guest affinities.

Binding of carboxylate and trimethylammonium salts to octa-acid and TEMOA deep-cavity cavitands.

In participation of the fifth statistical assessment of modeling of proteins and ligands (SAMPL5), the strength of association of six guests (3-8) to two hosts (1 and 2) were measured by 1H NMR and ITC. Each host possessed a unique and well-defined binding pocket, whilst the wide array of amphiphilic guests possessed binding moieties that included: a terminal alkyne, nitro-arene, alkyl halide and cyano-arene groups. Solubilizing head groups for the guests included both positively charged trimethylammonium and negatively charged carboxylate functionality. Measured association constants (K a ) covered five orders of magnitude, ranging from 56 M-1 for guest 6 binding with host 2 up to 7.43 × 106 M-1 for guest 6 binding to host 1.

Differentiation of small alkane and alkyl halide constitutional isomers via encapsulation.

Previously we have demonstrated that host 1 is capable of hydrocarbon gas separation by selective sequestration of butane from a mixture with propane in the headspace above a solution of the host (C. L. D. Gibb, B. C. Gibb, J. Am. Chem. Soc., 2006, 128, 16498-16499). Expanding on the idea of using this host as a means to affect guest discrimination, we report here on NMR studies of the binding of constitutional isomers of two classes of small molecules: hexanes and chloropentanes. Our results indicate that even with these relatively straightforward classes of molecules, guest binding is complicated. Overall, host 1 displays a preference to bind guests with a X-C(R2)-C(R2)-Me (X = Cl or Me) structure, and more generally, a preference for branched guests rather than highly flexible, unbranched derivatives. The complexity of binding of these isomers is magnified when considering molecular differentiation between pairs of guests. In such cases, different guests demonstrated different propensities to self-sort; some self-sort exclusively, while others show very little propensity to do so. However, whereas the pool of guests reveals some general correlations between binding strength and structure, no obvious relationship between structure and degree of self-sorting was observed.

Carfilzomib associated thrombotic microangiopathy initially treated with therapeutic plasma exchange.

Drug associated thrombotic microangiopathy (TMA) is a rare event causing thrombocytopenia, microangiopathic anemia, renal failure, and neurologic abnormalities. Here, we present a case of TMA that occurred during the first cycle of treatment with carfilzomib for relapsed multiple myeloma.

Defects in purine nucleotide metabolism lead to substantial incorporation of xanthine and hypoxanthine into DNA and RNA.

Deamination of nucleobases in DNA and RNA results in the formation of xanthine (X), hypoxanthine (I), oxanine, and uracil, all of which are miscoding and mutagenic in DNA and can interfere with RNA editing and function. Among many forms of nucleic acid damage, deamination arises from several unrelated mechanisms, including hydrolysis, nitrosative chemistry, and deaminase enzymes. Here we present a fourth mechanism contributing to the burden of nucleobase deamination: incorporation of hypoxanthine and xanthine into DNA and RNA caused by defects in purine nucleotide metabolism. Using Escherichia coli and Saccharomyces cerevisiae with defined mutations in purine metabolism in conjunction with analytical methods for quantifying deaminated nucleobases in DNA and RNA, we observed large increases (up to 600-fold) in hypoxanthine in both DNA and RNA in cells unable to convert IMP to XMP or AMP (IMP dehydrogenase, guaB; adenylosuccinate synthetase, purA, and ADE12), and unable to remove dITP/ITP and dXTP/XTP from the nucleotide pool (dITP/XTP pyrophosphohydrolase, rdgB and HAM1). Conversely, modest changes in xanthine levels were observed in RNA (but not DNA) from E. coli lacking purA and rdgB and the enzyme converting XMP to GMP (GMP synthetase, guaA). These observations suggest that disturbances in purine metabolism caused by known genetic polymorphisms could increase the burden of mutagenic deaminated nucleobases in DNA and interfere with gene expression and RNA function, a situation possibly exacerbated by the nitrosative stress of concurrent inflammation. The results also suggest a mechanistic basis for the pathophysiology of human inborn errors of purine nucleotide metabolism.

Characterizing influence of rCHOP treatment on diffuse large B-cell lymphoma microenvironment through in vitro microfluidic spheroid model.

For over two decades, Rituximab and CHOP combination treatment (rCHOP) has remained the standard treatment approach for diffuse large B-cell lymphoma (DLBCL). Despite numerous clinical trials exploring treatment alternatives, few options have shown any promise at further improving patient survival and recovery rates. A wave of new therapeutic approaches have recently been in development with the rise of immunotherapy for cancer, however, the cost of clinical trials is prohibitive of testing all promising approaches. Improved methods of early drug screening are essential for expediting the development of the therapeutic approaches most likely to help patients. Microfluidic devices provide a powerful tool for drug testing with enhanced biological relevance, along with multi-parameter data outputs. Here, we describe a hydrogel spheroid-based microfluidic model for screening lymphoma treatments. We utilized primary patient DLBCL cells in combination with NK cells and rCHOP treatment to determine the biological relevance of this approach. We observed cellular viability in response to treatment, rheological properties, and cell surface marker expression levels correlated well with expected in vivo characteristics. In addition, we explored secretory and transcriptomic changes in response to treatment. Our results showed complex changes in phenotype and transcriptomic response to treatment stimuli, including numerous metabolic and immunogenic changes. These findings support this model as an optimal platform for the comparative screening of novel treatments.

Increased levels of inosine in a mouse model of inflammation.

One possible mechanism linking inflammation with cancer involves the generation of reactive oxygen, nitrogen, and halogen species by activated macrophages and neutrophils infiltrating sites of infection or tissue damage, with these chemical mediators causing damage that ultimately leads to cell death and mutation. To determine the most biologically deleterious chemistries of inflammation, we previously assessed products across the spectrum of DNA damage arising in inflamed tissues in the SJL mouse model nitric oxide overproduction ( Pang et al. ( 2007 ) Carcinogenesis 28 , 1807 - 1813 ). Among the anticipated DNA damage chemistries, we observed significant changes only in lipid peroxidation-derived etheno adducts. We have now developed an isotope-dilution, liquid chromatography-coupled, tandem quadrupole mass spectrometric method to quantify representative species across the spectrum of RNA damage products predicted to arise at sites of inflammation, including nucleobase deamination (xanthosine and inosine), oxidation (8-oxoguanosine), and alkylation (1,N(6)-ethenoadenosine). Application of the method to the liver, spleen, and kidney from the SJL mouse model revealed generally higher levels of oxidative background RNA damage than was observed in DNA in control mice. However, compared to control mice, RcsX treatment to induce nitric oxide overproduction resulted in significant increases only in inosine and only in the spleen. Further, the nitric oxide synthase inhibitor, N-methylarginine, did not significantly affect the levels of inosine in control and RcsX-treated mice. The differences between DNA and RNA damage in the same animal model of inflammation point to possible influences from DNA repair, RcsX-induced alterations in adenosine deaminase activity, and differential accessibility of DNA and RNA to reactive oxygen and nitrogen species as determinants of nucleic acid damage during inflammation.

High-throughput microfluidic 3D biomimetic model enabling quantitative description of the human breast tumor microenvironment.

Cancer is driven by both genetic aberrations in the tumor cells and fundamental changes in the tumor microenvironment (TME). These changes offer potential targets for novel therapeutics, yet lack of in vitro 3D models recapitulating this complex microenvironment impedes such progress. Here, we generated several tumor-stroma scaffolds reflecting the dynamic in vivo breast TME, using a high throughput microfluidic system. Alginate (Alg) or alginate-alginate sulfate (Alg/Alg-S) hydrogels were used as ECM-mimics, enabling the encapsulation and culture of tumor cells, fibroblasts and immune cells (macrophages and T cells, of the innate and adaptive immune systems, respectively). Specifically, Alg/Alg-S was shown capable of capturing and presenting growth factors and cytokines with binding affinity that is comparable to heparin. Viability and cytotoxicity were shown to strongly correlate with the dynamics of cellular milieu, as well as hydrogel type. Using on-chip immunofluorescence, production of reactive oxygen species and apoptosis were imaged and quantitatively analyzed. We then show how macrophages in our microfluidic system were shifted from a proinflammatory to an immunosuppressive phenotype when encapsulated in Alg/Alg-S, reflecting in vivo TME dynamics. LC-MS proteomic profiling of tumor cells sorted from the TME scaffolds revealed upregulation of proteins involved in cell-cell interactions and immunomodulation in Alg/Alg-S scaffolds, correlating with in vivo findings and demonstrating the appropriateness of Alg/Alg-S as an ECM biomimetic. Finally, we show the formation of large tumor-derived vesicles, formed exclusively in Alg/Alg-S scaffolds. Altogether, our system offers a robust platform for quantitative description of the breast TME that successfully recapitulates in vivo patterns. STATEMENT OF SIGNIFICANCE: Cancer progression is driven by profound changes in both tumor cells and surrounding stroma. Here, we present a high throughput microfluidic system for the generation and analysis of dynamic tumor-stroma scaffolds, that mimic the complex in vivo TME cell proportions and compositions, constructing robust in vitro models for the study of the TME. Utilizing Alg/Alg-S as a bioinspired ECM, mimicking heparin's in vivo capabilities of capturing and presenting signaling molecules, we show how Alg/Alg-S induces complex in vivo-like responses in our models. Alg/Alg-S is shown here to promote dynamic protein expression patterns, that can serve as potential therapeutic targets for breast cancer treatment. Formation of large tumor-derived vesicles, observed exclusively in the Alg/Alg-S scaffolds suggests a mechanism for tumor survival.

Spontaneous drying of non-polar deep-cavity cavitand pockets in aqueous solution.

There are many open questions regarding the hydration of solvent-exposed non-polar tracts and pockets in proteins. Although water is predicted to de-wet purely repulsive surfaces and evacuate crevices, the extent of de-wetting is unclear when ubiquitous van der Waals interactions are in play. The structural simplicity of synthetic supramolecular hosts imbues them with considerable potential to address this issue. To this end, here we detail a combination of densimetry and molecular dynamics simulations of three cavitands, coupled with calorimetric studies of their complexes with short-chain carboxylates. Our results reveal the range of wettability possible within the ostensibly identical cavitand pockets-which differ only in the presence and/or position of the methyl groups that encircle the portal to their non-polar pockets. The results demonstrate the ability of macrocycles to template water cavitation within their binding sites and show how the orientation of methyl groups can trigger the drying of non-polar pockets in liquid water, which suggests new avenues to control guest complexation.

The Thermodynamics of Anion Complexation to Nonpolar Pockets.

The interactions between nonpolar surfaces and polarizable anions lie in a gray area between the hydrophobic and Hofmeister effects. To assess the affinity of these interactions, NMR and ITC were used to probe the thermodynamics of eight anions binding to four different hosts whose pockets each consist primarily of hydrocarbon. Two classes of host were examined: cavitands and cyclodextrins. For all hosts, anion affinity was found to follow the Hofmeister series, with associations ranging from 1.6-5.7 kcal mol-1. Despite the fact that cavitand hosts 1 and 2 possess intrinsic negative electrostatic fields, it was determined that these more enveloping hosts generally bound anions more strongly. The observation that the four hosts each possess specific anion affinities that cannot be readily explained by their structures, points to the importance of counter cations and the solvation of the "empty" hosts, free guests, and host-guest complexes, in defining the affinity.

Hospital readmission following transplantation: identifying risk factors and designing preventive measures.

BACKGROUND: About 1 in 7 of all hospitalized patients is readmitted within 30 days of discharge. The cost of readmissions is significant, with Medicare readmissions alone costing the health care system an estimated $28 billion a year. OBJECTIVE: To identify the rates of and causes for readmission within 100 days of patients receiving a hematopoietic stem cell transplant. METHODS: We performed a retrospective review of 235 consecutive transplant recipients (autologous, n = 144; allogeneic, n = 91) to determine rates and causes for readmission within 100 days of patients receiving a transplant. Medical records and hospital readmissions were reviewed for each patient. RESULTS: 36 allogeneic patients accounted for 56 readmissions. 23 autologous patients accounted for 26 readmissions. Autologous transplant recipients were most commonly readmitted for the development of a fever (n = 15 patients) or cardiopulmonary issues (n = 4). The most prevalent reasons for readmission in the allogeneic recipients included a fever (n = 21) or the development or exacerbation of graft-versus-host disease (n = 5). The readmission length of stay was 6 days (median range, 1-91 days) for allogeneic patients and 4 days (median range, 1-22 days) for autologous patients. There was no difference in survival between the readmitted and the non-readmitted cohorts (𝑃 = .55 for allogeneic patients; 𝑃 = .24 for autologous patients). Although allogeneic graft recipients demonstrated a higher readmission rate (39.6%) compared with autologous recipients (16%), none of the variables examined, including age, gender, performance status, diagnosis, remission status at the time of transplant, comorbidities, type of preparative chemotherapy regimen or donor type, identified patients at increased risk for readmission. LIMITATIONS: Variations in clinical care, physician practices, and patient characteristics need to be considered when examining readmission rates. Most of the allogeneic patient population included unrelated donor recipients (65%) who received nonmyeloablative conditioning regimens (81% of allogeneic recipients). These features may not be characteristic of other centers. CONCLUSIONS: In these high-risk patients, readmissions following a transplant are common. Enhanced predischarge education by nurses and pharmacists, along with ongoing outpatient education and rigorous outpatient follow-up through phone calls or social media may decrease readmission rates.

Potential for improved survival with intensification of daunorubicin based induction chemotherapy in acute myeloid leukemia patients who do not receive transplant: A multicenter retrospective study.

INTRODUCTION: During induction daunorubicin intensification from 45 mg/m(2)/day to 90 mg/m(2)/day has shown improved response and survival rates in AML patients. We retrospectively reviewed outcomes of daunorubicin 60 mg/m(2)/day (DNR60) versus daunorubicin 90 mg/m(2)/day (DNR90) in adult AML patients. MATERIAL AND METHODS: Newly diagnosed AML patients ≥18 years who received 7+3 with or without etoposide as frontline therapy from 1/1/2006 to 5/1/2013 were identified. Chi-square and Wilcoxon rank sum tests were used to compare characteristics. Kaplan-Meier curves were estimated for overall survival (OS). Univariate and multivariate Cox proportional hazard regression models were developed to determine independent predictors for survival. RESULTS: A total of 128 patients were included (DNR90=48 patients, DNR60=80 patients). The estimated 3-year OS rate in the DNR90 group was 56% (95% CI 38-70%), while in the DNR60 group was 34% (95% CI 23-44%). Multivariate analysis (MVA) in non-allotransplanted patients showed that unfavorable cytogenetics and worse performance status were associated with decreased OS while DNR intensification, etoposide use and site were associated with improved OS. In MVA of allotransplanted patients re-induction based on day-14 marrow was associated with worse OS. CONCLUSIONS: Based on our retrospective study, initial DNR based induction chemotherapy intensification improved OS in non-allotransplanted patients. Prospective studies are needed to confirm this preliminary finding.

Antagonism of FOG-1 and GATA factors in fate choice for the mast cell lineage.

The zinc finger transcription factor GATA-1 requires direct physical interaction with the cofactor friend of GATA-1 (FOG-1) for its essential role in erythroid and megakaryocytic development. We show that in the mast cell lineage, GATA-1 functions completely independent of FOG proteins. Moreover, we demonstrate that FOG-1 antagonizes the fate choice of multipotential progenitor cells for the mast cell lineage, and that its down-regulation is a prerequisite for mast cell development. Remarkably, ectopic expression of FOG-1 in committed mast cell progenitors redirects them into the erythroid, megakaryocytic, and granulocytic lineages. These lineage switches correlate with transcriptional down-regulation of GATA-2, an essential mast cell GATA factor, via switching of GATA-1 for GATA-2 at a key enhancer element upstream of the GATA-2 gene. These findings illustrate combinatorial control of cell fate identity by a transcription factor and its cofactor, and highlight the role of transcriptional networks in lineage determination. They also provide evidence for lineage instability during early stages of hematopoietic lineage commitment.

Identification of ZBP-89 as a novel GATA-1-associated transcription factor involved in megakaryocytic and erythroid development.

A complete understanding of the transcriptional regulation of developmental lineages requires that all relevant factors be identified. Here, we have taken a proteomic approach to identify novel proteins associated with GATA-1, a lineage-restricted zinc finger transcription factor required for terminal erythroid and megakaryocytic maturation. We identify the Krüppel-type zinc finger transcription factor ZBP-89 as being a component of multiprotein complexes involving GATA-1 and its essential cofactor Friend of GATA-1 (FOG-1). Using chromatin immunoprecipitation assays, we show that GATA-1 and ZBP-89 cooccupy cis-regulatory elements of certain erythroid and megakaryocyte-specific genes, including an enhancer of the GATA-1 gene itself. Loss-of-function studies in zebrafish and mice demonstrate an in vivo requirement for ZBP-89 in megakaryopoiesis and definitive erythropoiesis but not primitive erythropoiesis, phenocopying aspects of FOG-1- and GATA-1-deficient animals. These findings identify ZBP-89 as being a novel transcription factor involved in erythroid and megakaryocytic development and suggest that it serves a cooperative function with GATA-1 and/or FOG-1 in a developmental stage-specific manner.