Photophysical Rate Constants and Oxygen Dependence for Si and Ge Rhodamine Zwitterions.

The family of group XIV rhodamine zwitterions are fluorescence probes with carbon, silicon, germanium, or tin substituted in the 10-position of the xanthene ring. Because of their inherent near-infrared fluorescence, photostability and high quantum yields in aqueous solutions, the Si and Ge containing fluorophores in this class have become increasingly important for fluorescent labeling of proteins and biological molecules. This study fully characterizes photophysical rates derived from a model consisting of a singlet ground state, the lowest singlet excited state, and the lowest triplet excited state for two exemplar group XIV rhodamine zwitterions, one containing Si and the other Ge. Within a simple Jablonski diagram, all radiative and non-radiative rates, including intersystem crossing and triplet depopulation rates, were measured as a function of oxygen concentration. It was shown that the triplet depopulation rates are intrinsically fast in comparison with traditional xanthene containing fluorophores, probably due to the increased spin-obit coupling from the Si and Ge substitution in the xanthene ring. Dissolved oxygen increases both the intersystem crossing and triplet depopulation rates. Stern-Volmer analysis was conducted to estimate rates of quenching by oxygen. The experimental data was used to estimate the initial rates for reactive oxygen production by Si and Ge containing fluorophores in aqueous solutions containing different concentrations of dissolved O2. These estimates showed a significantly slower initial rate of reactive oxygen production in comparison with rhodamine 6G. This goes a long way to explaining their inherent photostability. Spectroscopic experiments were also conducted in 77 K viscous aqueous glasses where it was observed that the fluorescence spectra remained unchanged, and the quantum yields increased from 0.53 to 0.84 and from 0.52 to 0.89 for the Si and Ge containing fluorophores respectively; no phosphorescence was observed. All intersystem crossing and triplet depopulation rates were measured using fluorescence correlation spectroscopy (FCS) and analyzed using a new method that extrapolated the power dependence of the FCS curves to optical saturation. This method was verified using published data.

High Resource Utilization in Emergent Versus Elective General Surgery.

BACKGROUND: In an era of pay for performance metrics, we sought to increase understanding of factors driving high resource utilization (HRU) in emergent (EGS) versus same-day elective (SDGS) general surgery patients. METHODS: General surgery procedures from the 2016 ACS-NSQIP public use file were grouped according to the first four digits of the primary procedure CPT code. Groups having at least 100 of both elective and emergent cases were included (22 groups; 83,872 cases). HRU patients were defined as those in-hospital >7D, returned to the OR, readmitted, and/or had morbidity likely requiring an intensive care unit (ICU)stay. Independent NSQIP predictors of HRU were identified through forward regression; P for entry < 0.05, for exit > 0.10. RESULTS: Of all patients, 33% were HRU. The three highest HRU procedures (total colectomy, enterolysis, and ileostomy) comprised a higher proportion of EGS than SDGS cases (10.3 versus 2.6%, P < 0.001). The duration of operation was 40 Min lower in EGS after adjustment. Thirty-nine of the remaining 40 HRU predictors were higher in EGS including preoperative SIRS/Sepsis (50 versus 2%), ASA classification IV-V (31 versus 5%), albumin <3.5 g/dL (40 versus 12%), transfers (26 versus 2%, P's < 0.001), septuagenarians (35 versus 25%) and disseminated cancer (6.3 versus 4.8%, P's < 0.001); while sex did not differ. After adjustment, EGS patients remained more likely to be HRU (odds ratio 2.5, 95% CI 2.4 - 2.6, P < 0.001). CONCLUSIONS: EGS patients utilize significantly more resources than SDGS patients above what can be adjusted for in the clinically robust ACS-NSQIP dataset. Distinctive payment and value-based performance models are necessary for EGS.

Dissociation Constants of Cytochrome P450 2C9/Cytochrome P450 Reductase Complexes in a Lipid Bilayer Membrane Depend on NADPH: A Single-Protein Tracking Study.

Cytochrome P450-reductase (CPR) is a versatile NADPH-dependent electron donor located in the cytoplasmic side of the endoplasmic reticulum. It is an electron transferase that is able to deliver electrons to a variety of membrane-bound oxidative partners, including the drug-metabolizing enzymes of the cytochrome P450s (P450). CPR is also stoichiometrically limited compared to its oxidative counterparts, and hypotheses have arisen about possible models that can overcome the stoichiometric imbalance, including quaternary organization of P450 and diffusion-limited models. Described here are results from a single-protein tracking study of fluorescently labeled CPR and cytochrome P450 2C9 (CYP2C9) molecules in which stochastic analysis was used to determine the dissociation constants of CPR/CYP2C9 complexes in a lipid bilayer membrane for the first time. Single-protein trajectories demonstrate the transient nature of these CPR-CYP2C9 interactions, and the measured Kd values are highly dependent on the redox state of CPR. It is shown that CPRox/CYP2C9 complexes have a much higher dissociation constant than CPR2-/CYP2C9 or CPR4-/CYP2C9 complexes, and a model is presented to account for these results. An Arrhenius analysis of diffusion constants was also carried out, demonstrating that the reduced forms of CPR and CYP2C9 interact differently with the biomimetic ER and may, in addition to protein conformational changes, contribute to the observed NADPH-dependent shift in Kd. Finally, it is also shown that the CPRox/CYP2C9 affinity depends on the nature of the ligand, being higher when a substrate is bound, compared to an inhibitor.

Single-Protein Tracking Reveals That NADPH Mediates the Insertion of Cytochrome P450 Reductase into a Biomimetic of the Endoplasmic Reticulum.

Cytochrome P450 reductase (CPR) is the redox partner for most human cytochrome P450 enzymes. It is also believed that CPR is an integral membrane protein exclusively. Herein, we report that, contrary to this belief, CPR can exist as a peripheral membrane protein in the absence of NADPH and will transition to an integral membrane protein in the presence of stoichiometric amounts of NADPH or greater. All experiments were performed in a solid-supported cushioned lipid bilayer that closely matched the chemical composition of the human endoplasmic reticulum and served as an ER biomimetic. The phase characteristics and fluidity of the ER biomimetic was characterized with fluorescence micrographs and temperature-dependent fluorescence recovery after photobleaching. The interactions of CPR with the ER biomimetic were directly observed by tracking single CPR molecules using time-lapse single-molecule fluorescence imaging and subsequent analysis of tracks. These studies revealed dramatic changes in diffusion coefficient and the degree of partitioning of CPR as a function of NADPH concentration.

The Impact of the Great Migration on Mortality of African Americans: Evidence from the Deep South.

The Great Migration-the massive migration of African Americans out of the rural South to largely urban locations in the North, Midwest, and West-was a landmark event in U.S. HISTORY: Our paper shows that this migration increased mortality of African Americans born in the early twentieth century South. This inference comes from an analysis that uses proximity of birthplace to railroad lines as an instrument for migration.

Establishing the Top 10 Research Priorities for Adolescent and Young Adult (AYA) Cancer in Canada: A Protocol for a James Lind Alliance Priority Setting Partnership.

Adolescents and young adults (AYAs; 15-39 years) diagnosed with cancer have unique medical and psychosocial needs. These needs could be better addressed through research that is focused on the topics that matter most to them. However, there is currently no patient-oriented research agenda for AYA cancer in Canada. This manuscript describes the early development and project protocol for a priority-setting partnership (PSP) for establishing the top 10 research priorities for AYA cancer in Canada. This project follows the PSP methodology outlined by the James Lind Alliance (JLA) to engage patients, caregivers, and clinicians in research prioritization. The steps of a JLA PSP include establishing a steering group and project partners, gathering uncertainties, data processing and verifying uncertainties, interim priority setting, and a final priority setting workshop. The AYA cancer PSP will result in a top 10 list of research priorities identified by Canadian AYA patients, caregivers, and clinicians that will be published and shared broadly with the research community. The first steering group meeting was held in April 2023, and the project is ongoing. The establishment of a patient-oriented research agenda for AYA cancer will catalyze a long-term and impactful research focus and ultimately improve outcomes for AYA patients with cancer in Canada.

Thermodynamic Driving Forces of Redox-Dependent CPR Insertion into Biomimetic Endoplasmic Reticulum Membranes.

Cytochrome P450 reductase (CPR) is a NADPH-dependent membrane-bound oxidoreductase found in the endoplasmic reticulum (ER) and is the main redox partner for most cytochrome P450 enzymes. Presented are the measured thermodynamic driving forces responsible for how strongly CPR partitions into a biomimetic ER with the same lipid composition of a natural ER. Using temperature-dependent fluorescence correlation spectroscopy and fluorescence single-protein tracking, the standard state free energies, enthalpies, and entropies of the CPR insertion process were all measured. The results of this study demonstrate that the thermodynamic driving forces are dependent on the redox states of CPR. In particular, the partitioning of CPRox into a biomimetic ER is an exothermic process with a small positive change in entropy, while CPRred partitioning is endothermic with a large positive change in entropy. Both resulted in negative free energies and strong association to the biomimetic ER, but the KP of CPRox insertion is measurably smaller than that of CPRred. Using this new information and known results from literature sources, we also present a phenomenological model that accounts for membrane-protein interactions, protein orientation relative to the membrane, and protein conformation as a function of the redox state.

The Effect of Social Connectedness on Crime: Evidence from the Great Migration.

This paper estimates the effect of social connectedness on crime across U.S. cities from 1970 to 2009. Migration networks among African Americans from the South generated variation across destinations in the concentration of migrants from the same birth town. Using this novel source of variation, we find that social connectedness considerably reduces murders, rapes, robberies, assaults, burglaries, and motor vehicle thefts, with a one standard deviation increase in social connectedness reducing murders by 21 percent and motor vehicle thefts by 20 percent. Social connectedness especially reduces murders of adolescents and young adults committed during gang and drug activity.

Overview of the bicaval dual lumen cannula.

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a form of extracorporeal life support that provides total gas exchange (CO2 and O2) within the central venous circulation. The bicaval dual lumen cannula (DLC) is an option for patients requiring respiratory support with VV-ECMO. The catheter is inserted via the internal jugular vein into the superior and inferior vena cava, drains blood into the ECMO circuit for gas exchange, and then returns arterialized blood to the right heart for circulation. The DLC facilitates physical therapy, ambulation, and early extubation. This chapter will review the uses, advantages, and unique complications of the DLC.

Measurement of free chlorine levels in water using potentiometric responses of biofilms and applications for monitoring and managing the quality of potable water.

Residual free chlorine is not monitored continuously at scale in drinking water distribution systems because existing real-time sensor technologies require frequent maintenance, cleaning, and calibration, which makes these products too costly to be used throughout a distribution system. As a result, current measurement approaches require manual sampling, which is not feasible for the consistent monitoring of free chlorine because chlorine concentrations vary significantly throughout pipeline distribution and over time and space. This research presents an alternative and cost-effective method of predicting free chlorine levels in drinking water using graphite electrodes coated with naturally grown microbial biofilms. This Microbial Potentiometric Sensor (MPS) array was installed in a Continuously Mixed Batch Reactor (CMBR), and drinking water containing variable free chlorine concentrations. The chlorine concentrations were introduced in a controlled manner, and the MPS signals were monitored over time. MPS signals were measured from the change in Open Circuit Potential (OCP) across the MPS array in real-time. An empirically derived relationship between the normalized change in OCP and free chlorine was established by fitting individual and average MPS data to a decaying exponential growth function in order to predict free chlorine levels. The results show that free chlorine can be predicted with reasonable accuracy, with model validation showing an average absolute error of ±0.09 ppm below 1.1 ppm and ±0.30 ppm between 1.1 and 2.7 ppm. However, the accuracy of predictions was reduced at higher free chlorine levels. The researchers conclude that MPS systems may benefit drinking water distribution systems by measuring free chlorine. These advantages of the MPS are especially pronounced in the developing world because this system is inexpensive and does not require routine maintenance or cleaning. The system relies on a naturally forming and regenerating biofilm and an inexpensive potentiometric meter to produce stable measurements.

Awkward Choreographies from Cancer's Margins: Incommensurabilities of Biographical and Biomedical Knowledge in Sexual and/or Gender Minority Cancer Patients' Treatment.

Canadian and American population-based research concerning sexual and/or gender minority populations provides evidence of persistent breast and gynecologic cancer-related health disparities and knowledge divides. The Cancer's Margins research investigates the complex intersections of sexual and/or gender marginality and incommensurabilities and improvisation in engagements with biographical and biomedical cancer knowledge. The study examines how sexuality and gender are intersectionally constitutive of complex biopolitical mappings of cancer health knowledge that shape knowledge access and its mobilization in health and treatment decision-making. Interviews were conducted with a diverse group (n=81) of sexual and/or gender minority breast or gynecologic cancer patients. The LGBQ//T2 cancer patient narratives we have analyzed document in fine grain detail how it is that sexual and/or gender minority cancer patients punctuate the otherwise lockstep assemblage of their cancer treatment decision-making with a persistent engagement in creative attempts to resist, thwart and otherwise manage the possibility of discrimination and likewise, the probability of institutional erasure in care settings. Our findings illustrate the demands that cancer places on LGBQ//T2 patients to choreograph access to, and mobilization of knowledge and care, across significantly distinct and sometimes incommensurable systems of knowledge.

Microbial potentiometric sensor: A new approach to longstanding challenges.

The underlying hypothesis of this study is that simple potentiometric measurements between sensing electrodes and a shared reference electrode - Microbial Potentiometric Sesnor (MPS) system - can be employed in a long-term, continuous mode of operation to resolve the spatial and temporal changes in environmental systems. To address the hypothesis, (1) a conceptual description of the MPS system and its postulated principle of operation are provided; (2) the MPS system performance is documented under controlled laboratory conditions; and (3) the capabilities of the MPS system are documented under quiescent and dynamic field condition. In a laboratory setting, the variability among different MPS signals was insignificant confirming the postulated high accuracy and reproducibility of the sensor performance. It also demonstrated statistically significant correlations with dissolved oxygen (DO) and oxidation-reduction potential (ORP) sensors, while showing capabilities of operating under anoxic and anaerobic conditions. Regardless of their locations in the model wetland system, three MPS sensors functioned without interruption and cleaning for a period >2 years, and thus demonstrating long-term durability of the MPS technology. In real batch-wastewater treatment facility, the deployed MPS system signals were able to describe the organic carbon trends and correlate with each treatment phase in a cycle. Data reproducibility and reliability exceeded the expectations better describing the carbon treatment levels than the DO and ORP sensors (p < 4.4 × 10-162 vs phase adjusted p < 3.0 × 10-58). While MPS signals correlate with specific parameters that describe the local process or environments, it is more prudent to employ both the magnitude and pattern of a composite signal like the MPS signal describe the change to reflect any shift in the local environment. When compared to a baseline pattern, this change in signal magnitude and pattern reveals important information that can be employed to tailor and optimize any condition or process which involves microorganisms.

A Guide to Tracking Single Membrane Proteins and Their Interactions in Supported Lipid Bilayers.

The purpose of this chapter is to serve as a guide for those who wish to carry out experiments tracking single proteins in planar supported biomimetic membranes. This chapter describes, in detail, the construction of a simple single molecule microscope, which includes: (1) a parts list, (2) temperature control, (3) an alignment procedure, (4) a calibration procedure, and (5) a procedure for measuring the mechanical stability of the instrument. It also gives procedures for making planar supported bilayers on hydrophilically treated borosilicate and quartz. These include (1) POPC bilayers, (2) POPC/PEG-PE cushioned bilayers, (3) POPC/PEG-PE cushioned bilayers on BSA passivated substrates, and (4) a cushioned biomimetic membrane of the endoplasmic reticulum (ER). A procedure for the detergent mediated incorporation of the transmembrane protein 5HT3A (a serotonin receptor) is also described and can be used as a starting point for other large non-self-inserting transmembrane proteins. A procedure for the detergent-free incorporation of cytochrome P450 reductase (CPR) and cytochrome P450 enzymes (P450) into an ER biomimetic is also described. The final experimental section of this chapter details different procedures for data analysis including (1) quantitative analysis of mean squared displacements from individually tracked proteins, (2) gamma distribution analysis of diffusion coefficients from a small ensemble of individually tracked proteins, (3) average mean squared displacement analysis, (4) Gaussian analysis of step-size distributions, (5) Arrhenius analysis of temperature dependent data, (6) the determination of equilibrium constants from a step-size distribution, and (7) a perspective associated with the interpretation of single particle tracking data.

Cancer's Margins: Trans* and Gender Nonconforming People's Access to Knowledge, Experiences of Cancer Health, and Decision-Making.

PURPOSE: Research in Canada and the United States indicates that minority gender and sexuality status are consistently associated with health disparities and poor health outcomes, including cancer health. This article investigates experiences of cancer health and care, and access to knowledge for trans* and gender nonconforming people diagnosed with and treated for breast and/or gynecologic cancer. Our study contributes new understandings about gender minority populations that will advance knowledge concerning the provision of culturally appropriate care. This is the first study we are aware of that focuses on trans* and gender nonconforming peoples' experiences of cancer care and treatment, support networks, and access to and mobilization of knowledge. METHODS: This article analyzes trans* and gender nonconforming patient interviews from the Cancer's Margins project ( www.lgbtcancer.ca ): Canada's first nationally-funded project that investigates the complex intersections of sexual and/or gender marginality, cancer knowledge, treatment experiences, and modes of the organization of support networks. RESULTS: Our analysis documents how different bodies of knowledge relative to cancer treatment and gendered embodiment are understood, accessed, and mobilized by trans* and gender nonconforming patients. Findings reported here suggest that one's knowledge of a felt sense of gender is closely interwoven with knowledge concerning cancer treatment practices; a dynamic which organizes knowledge mobilities in cancer treatment. CONCLUSIONS: The findings support the assertion that cisgender models concerning changes to the body that occur as a result of biomedical treatment for breast and/or gynecologic cancer are wholly inadequate in order to account for trans* and gender nonconforming peoples' experiences of cancer treatments, and access to and mobilization of related knowledge.