Lysozyme adsorption on carbonaceous nanoparticles probed by second harmonic light scattering.

The first hyperpolarizability (ß) of two different sizes (15 and 35 nm) of carbonaceous nanoparticle (CNP) is reported for the first time using second harmonic light scattering (SHLS). The ß values of the CNPs were found to be larger than those of organic molecules like pNA but lower than those of plasmonic nanoparticles like gold and silver. SHLS was further used to investigate the adsorption of a model protein Lysozyme (Lyz) on these CNPs, which is crucial for the design of safe and effective CNP-based therapeutics. The change in SH intensity from the CNPs on the addition of Lyz was recorded and fitted to the modified Langmuir adsorption model (MLM). The binding constant, free energy changes and surface coverage values show that Lyz is physisorbed on the CNPs forming less than a monolayer. The temperature dependent SH intensity measurements enabled direct determination of enthalpy and entropy changes for Lyz adsorption. The enthalpy and entropy changes reveal that Lyz adsorption is endothermic and entropically driven.

Safety of opioid prescribing among older cancer survivors.

BACKGROUND: Cancer survivors receive more long-term opioid therapy (LTOT) than people without cancer, but the safety of LTOT prescribing is unknown. METHODS: Opioid-naive adults aged ≥66 years who had been diagnosed in 2008-2015 with breast, lung, head and neck, or colorectal cancer were identified with data from Surveillance, Epidemiology, and End Results cancer registries linked with Medicare claims. Survivors with 1 or more LTOT episodes (≥90 consecutive days) occurring ≥1 year after their cancer diagnosis and before censoring at hospice entry, another cancer diagnosis, 6 months before death, or December 2016 were included. The safety of prescribing during the first 90 days of the first LTOT episode was measured during follow-up. As a positive safety indicator, the proportion of survivors with concurrent nonopioid pain management was measured. Indicators of less safe prescribing were the proportion of survivors with a high average daily opioid dose (≥90 morphine milligram equivalents) and the proportion of survivors with concurrent benzodiazepine dispensing. Multivariable logistic regression analyses were conducted to identify clinical predictors of each safety outcome. RESULTS: In all, 3628 cancer survivors received LTOT during follow-up (median duration, 4.9 months; interquartile range, 3.5-8.0 months). Seventy-two percent of the survivors received multimodal pain management concurrently with LTOT. Eight percent of the survivors had high-dose opioid prescriptions; 25% of the survivors received benzodiazepines during LTOT. Multivariable analyses identified variations in safety measures by multiple clinical factors, although none were consistently significant across outcomes. CONCLUSIONS: To improve safe LTOT prescribing for survivors, efforts should focus on increasing multimodal pain management and reducing inappropriate benzodiazepine prescribing. Different clinical predictors of each outcome suggest different drivers of safe prescribing.

Thermodynamics of multilayer protein adsorption on a gold nanoparticle surface.

We report the thermodynamics of protein adsorption on negatively charged colloidal gold nanoparticles (GNPs) of 16 nm to 69 nm at pH 7.0. Three biologically important proteins of varying size, namely tetrameric alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae, bovine serum albumin (BSA), and insulin from the porcine pancreas were taken and their adsorption on the GNP surface was investigated by dynamic light scattering (DLS), absorption spectroscopy and zeta potential measurements. The hydrodynamic size of the GNPs was found to increase with protein addition. At very low protein concentrations, the adsorption of these proteins was earlier described by Langmuir-type adsorption isotherms. However, when the protein concentration is raised, the adsorption data are found to fit the BET (Brunauer, Emmett, and Teller) adsorption isotherm well, indicating multilayer formation on the GNP surface. The equilibrium binding constants: KS (monolayer) ∼108-109 M-1, KL (subsequent layers) ∼105-106 M-1, and monolayer thickness are obtained from our measurements. KS is found to increase with the size of the GNPs, while KL does not change significantly with either the size of the GNPs or that of the protein. KL, which originates from protein-protein interaction, compares very well with the protein dimerization constant in solution, indicating that the interaction beyond the first layer is not significantly influenced by the nanoparticles. The first layer forms the soft corona on the GNP surface since this layer, although stable, is removable by centrifugation. But the subsequent layers are weakly bound and we call it an ultra-soft corona in order to distinguish it qualitatively from the strongly bound first layer. The modest magnitudes of Gibbs free energy changes of 43-55 kJ mol-1 for the first layer and 31-35 kJ mol-1 for the subsequent layers indicate that ADH, BSA, and insulin are all physiosorbed on the GNP surface. The temperature dependent DLS data point out that the adsorption of these proteins on GNPs is endothermic but is accompanied by a large increase in entropy. The nature of the BET fits to the adsorption data shows that multilayer adsorption starts even before the monolayer formation is complete, and it does not occur in a layer-by-layer sequence.

Spillover Effects of Medicare's Voluntary Bundled Payments for Joint Replacement Surgery to Patients Insured by Commercial Health Plans.

BACKGROUND: Under the Bundled Payments for Care Improvement (BPCI) program, bundled paymtents for lower-extremity joint replacement (LEJR) are associated with 2% to 4% cost savings with stable quality among Medicare fee-for-service beneficiaries. However, BPCI may prompt practice changes that benefit all patients, not just fee-for-service beneficiaries. OBJECTIVE: To examine the association between hospital participation in BPCI and LEJR outcomes for patients with commercial insurance or Medicare Advantage (MA). DESIGN: Quasi-experimental study using Health Care Cost Institute claims from 2011 to 2016. SETTING: LEJR at 281 BPCI hospitals and 562 non-BPCI hospitals. PATIENTS: 184 922 patients with MA or commercial insurance. MEASUREMENTS: Differential changes in LEJR outcomes at BPCI hospitals versus at non-BPCI hospitals matched on propensity score were evaluated using a difference-in-differences (DID) method. Secondary analyses evaluated associations by patient MA status and hospital characteristics. Primary outcomes were changes in 90-day total spending on LEJR episodes and 90-day readmissions; secondary outcomes were postacute spending and discharge to postacute care providers. RESULTS: Average episode spending decreased more at BPCI versus non-BPCI hospitals (change, -2.2% [95% CI, -3.6% to -0.71%]; P = 0.004), but differences in changes in 90-day readmissions were not significant (adjusted DID, -0.47 percentage point [CI, -1.0 to 0.06 percentage point]; P = 0.084). Participation in BPCI was also associated with differences in decreases in postacute spending and discharge to institutional postacute care providers. Decreases in episode spending were larger for hospitals with high baseline spending but did not vary by MA status. LIMITATION: Nonrandomized studies are subject to residual confounding and selection. CONCLUSION: Participation in BPCI was associated with modest spillovers in episode savings. Bundled payments may prompt hospitals to implement broad care redesign that produces benefits regardless of insurance coverage. PRIMARY FUNDING SOURCE: Leonard Davis Institute of Health Economics at the University of Pennsylvania.

Personal Payments from Pharmaceutical Companies to Authors of Oncology Clinical Practice Guidelines.

BACKGROUND: Oncologists who author clinical practice guidelines frequently have financial relationships with the pharmaceutical industry. It is unknown whether participation on clinical practice guideline committees is associated with differences in the amounts of industry money received. MATERIALS AND METHODS: We conducted a nested case-control study from August 2013 to December 2018. We manually abstracted membership records of National Comprehensive Cancer Network (NCCN) Guidelines committees for the 20 most common cancers and linked to Open Payments. The study sample included medical oncologists selected to join an NCCN Guidelines committee ("joiners") during the study period. Joiners were matched 1:2 to medical oncologists who had no participation on NCCN committees (controls) by gender, NCCN institution, and medical school graduation year. We performed difference-in-differences (DiD) estimation to assess whether selection to an NCCN committee was associated with the dollar value of payments received from industry, using generalized estimating equations to address correlation between matched pairs and between repeated observations of the same pair. RESULTS: During the study period, 54 physicians joined an NCCN Guidelines committee. These physicians received more payments than matched controls in the year prior to joining ($11,259 vs. $3,427; p = .02); this difference did not increase in the year after joining (DiD = $731; p = .45). CONCLUSION: Medical oncologists selected to NCCN Guidelines committees had greater financial ties to industry than their peers. The potential influence of industry in oncology clinical practice guidelines may be reduced through the selection of committee members with fewer ties to industry. IMPLICATIONS FOR PRACTICE: Oncologists who author clinical practice guidelines frequently have financial conflicts of interest with the pharmaceutical industry. This creates concern about the potential for industry influence on guidelines. However, it is unknown whether oncologists who author guidelines have greater industry relationships than their peers. This study compared medical oncologists who were newly selected to join a National Comprehensive Cancer Network (NCCN) Guidelines panel with medical oncologists at the same institutions and at similar career stages. At the time they joined, oncologists joining NCCN Guidelines panels had received more than three times the dollar value of industry payments than their peers. The potential for industry influence may be reduced by the selection of less-conflicted panel members.

Thermodynamics of adsorption of alcohol dehydrogenase on the gold nanoparticle surface: a model based analysis versus direct measurement.

Characterization of the nanoparticle protein corona has gained tremendous importance lately. The parameters which quantitatively establish a specific nanoparticle-protein interaction need to be measured accurately since good quality data are necessary for the elucidation of the underlying mechanism and accurate molecular dynamics simulation. Here, we have employed surface sensitive second harmonic light scattering (SHLS) for investigating the adsorption of a tetrameric protein, alcohol dehydrogenase (ADH, Saccharomyces cerevisiae 147 kDa), on 16 nm, 27 nm, 41 nm, and 69 nm citrate capped gold nanoparticles (GNPs) in aqueous phosphate buffer at pH 7. We have extracted the binding constant, number of ADH bound per GNP, Gibbs free energy (ΔG°) from the decay of the second harmonic scattered signal as a function of protein concentration using a modified version of the Langmuir adsorption isotherm. The data obtained were checked with another technique, dynamic light scattering, using the same modified Langmuir model (MLM). While the binding constants measured by the two methods are in agreement, the number of ADH bound to each GNP obtained by the two methods varies a lot. In order to further probe this binding independent of a model fitting, we used an orthogonal fluorescence assay which measures the number of ADH bound to a GNP directly, and no model-fitting is necessary. We then used temperature dependent SHLS to measure the heat of adsorption (ΔH°) and entropy (ΔS°) for ADH-GNP corona formation. We found that the equilibrium binding constant (Kb) obtained from SHLS is of the order of 109 M-1 and the formation of the GNP-ADH corona is spontaneous with ΔG° ∼ -55 kJ mol-1. However, the adsorption is modestly endothermic, accompanied by a large increase in entropy. Stated differently, GNP-ADH corona formation is entropically driven. This is perhaps due to the tremendous disruption of the water structure at the negatively charged interface upon the arrival of the protein within the bonding distance to it. We believe that the SHLS technique is highly sensitive and reliable, at very low concentrations of both nanoparticles and proteins, for the quantitative estimation of the thermodynamic parameters of nanoparticle-protein corona formation, where many other techniques may fall short.

Functional interrogation of Lynch syndrome-associated MSH2 missense variants via CRISPR-Cas9 gene editing in human embryonic stem cells.

Lynch syndrome (LS) predisposes patients to cancer and is caused by germline mutations in the DNA mismatch repair (MMR) genes. Identifying the deleterious mutation, such as a frameshift or nonsense mutation, is important for confirming an LS diagnosis. However, discovery of a missense variant is often inconclusive. The effects of these variants of uncertain significance (VUS) on disease pathogenesis are unclear, though understanding their impact on protein function can help determine their significance. Laboratory functional studies performed to date have been limited by their artificial nature. We report here an in-cellulo functional assay in which we engineered site-specific MSH2 VUS using clustered regularly interspaced short palindromic repeats-Cas9 gene editing in human embryonic stem cells. This approach introduces the variant into the endogenous MSH2 loci, while simultaneously eliminating the wild-type gene. We characterized the impact of the variants on cellular MMR functions including DNA damage response signaling and the repair of DNA microsatellites. We classified the MMR functional capability of eight of 10 VUS providing valuable information for determining their likelihood of being bona fide pathogenic LS variants. This human cell-based assay system for functional testing of MMR gene VUS will facilitate the identification of high-risk LS patients.

Unravelling the Mechanism behind Charge Reversal at Silica Nanoparticle-Model Cell Membrane Interfaces.

Vibrational sum frequency generation spectroscopy is used to understand the interactions of silica nanoparticles (SNPs) with a model cationic membrane (1,2-dipalmitoyl-3-(trimethylammonium)propane, DPTAP) by monitoring changes in the interfacial water and lipid structure at pH ∼ 2 and pH ∼ 11. Our study reveals that, at pH ∼ 11, SNPs are attracted to DPTAP due to electrostatic forces, causing changes in the interfacial water structure and lipid membrane. At high concentrations of SNPs (≥70 pM), the interfacial charge reversed from positive to negative, inducing the formation of new hydrogen-bonded structures and reorganization of water molecules. Conversely, negligible changes are observed at pH ∼ 2 due to nearly neutral charge of the SNPs. Molecular dynamics simulations demonstrated that the interfacial potential due to model membrane and SNPs dictates the water structure at the interface. These results elucidate the fundamental mechanism governing interfacial interactions and could have implications in drug delivery, gene therapy, and biosensing.

Synthesis and Nonlinear Optical Behavior of Thermally Stable Chromophores Based on 9,9-Dimethyl-9H-fluoren-2-amine: Improving Intrinsic Hyperpolarizability through Modulation of "Push-Pull".

Improvement in the first hyperpolarizability (ßHRS) as well as intrinsic hyperpolarizability (ßint) of chromophores based on 9,9-dimethyl-9H-fluoren-2-amine through modulation of the conjugation pathway is described. A series of six novel chromophores with "linear" conjugation showed significant enhancement of ßHRS as well as ßint compared to the counterparts lacking a "linear" conjugation but having an identical combination of donor, acceptor, and the intervening π-conjugated linker. The hyperpolarizability (ßHRS as well as ßint) values of the new series measured using hyper-Rayleigh scattering exceeded the apparent limit set by the latter set of fluorene-based chromophores. The experimental results are analyzed and interpreted in the context of linear optical properties, single-crystal X-ray analysis, electrochemistry, etc. and corroborated by theoretical studies. We find that modulation of the "push-pull" of the conjugation pathway in these donor-acceptor chromophores compares favourably with the corresponding changes in the optical gaps, transition dipole moments, and dipole moment difference between the ground and excited states.

Mathematics anxiety in deaf, hard of hearing, and hearing college students.

While mathematics anxiety (MA) has been widely researched in recent decades, this study addresses significant gaps: namely, research that explores the relationship between MA and self-reported mathematics experiences; samples adults with a range of MA levels; and controls for general anxiety. Additionally, the study sampled deaf and hard of hearing (DHH) students, whose diverse life and educational experiences often differ from hearing students'. We investigated whether DHH students' experiences with mathematics (i.e., parental behaviors, school environment, and mathematics feelings) and demographic variables (i.e., hearing status, age, and gender) predict their MA, and whether these relationships differ from those in hearing students. Self-report questionnaires were completed by 296 DHH and hearing college students. Linear regression analyses controlling for general anxiety led to the following inference: DHH students who reported more positive attitudes toward mathematics and school environments demonstrated higher MA. Also, the relationships between mathematics feelings, parental behaviors, and MA differed between DHH and hearing students. Logistic regression analyses showed no contribution of MA to students' likelihood of pursuing STEM degrees in either DHH or between DHH and hearing groups. Overall, this work breaks new ground in the study of MA in DHH students and challenges standard views of the relationships between MA and individual experiences.

Trends in chronic opioid therapy among survivors of head and neck cancer.

BACKGROUND: Survivors of head and neck cancer (HNC) have increased risk of opioid misuse. METHODS: Using Surveillance, Epidemiology and End-Results-Medicare data, we matched adults ≥66 years diagnosed with HNC 2008-2015 with cancer-free controls. We computed odds ratios (OR) for receipt of chronic opioid therapy (COT, claims for ≥90 consecutive days) for HNC survivors compared to controls each year after matching through 2016. RESULTS: The cohort of HNC survivors declined from 5107 in the first year after diagnosis to 604 in the sixth year after diagnosis. For 5 years, rates of COT among HNC survivors exceeded that of controls. Differences between survivors and controls declined each year (ORs: year 1, 4.36; year 2, 2.60; year 3, 2.18; year 4, 1.85; and year 5, 1.35; all P-values <.05). CONCLUSIONS: Among older HNC survivors, cancer-associated opioid use in the first years after diagnosis suggests that the benefit of opioids must balance the risk of opioid misuse.

Spillover effects of mandatory hip and knee replacement surgery bundles in medicare.

BACKGROUND: Medicare used the Comprehensive Care for Joint Replacement (CJR) Model to mandate that hospitals in certain health care markets accept bundled payments for lower extremity joint replacement surgery. CJR has reduced spending with stable quality as intended among Medicare fee-for-service patients, but benefits could "spill over" to individuals insured through private health plans. Definitive evidence of spillovers remains lacking. OBJECTIVE: To evaluate the association between CJR participation and changes in outcomes among privately insured individuals. DESIGN, SETTING, PARTICIPANTS: We used 2013-2017 Health Care Cost Institute claims for 418,016 privately insured individuals undergoing joint replacement in 75 CJR and 121 Non-CJR markets. Multivariable generalized linear models with hospital and market random effects and time fixed effects were used to analyze the association between CJR participation and changes in outcomes. MAIN OUTCOMES AND MEASURES: Total episode spending, discharge to institutional post-acute care, and quality (e.g., surgical complications, readmissions). RESULTS: Patients in CJR and Non-CJR markets did not differ in total episode spending (difference of -$157, 95% CI -$1043 to $728, p = 0.73) or discharge to institutional post-acute care (difference of -1.1%, 95% CI -3.2%-1.0%, p = 0.31). Similarly, patients in the two groups did not differ in quality or other utilization outcomes. Findings were generally similar in stratified and sensitivity analyses. CONCLUSIONS: There was a lack of evidence of cost or utilization spillovers from CJR to privately insured individuals. There may be limits in the ability of certain value-based payment reforms to drive broad changes in care delivery and patient outcomes.