Bait and Cleave: Exosite-Binding Peptides on Quantum Dots Selectively Accelerate Protease Activity for Sensing with Enhanced Sensitivity.

The advantageous optical properties of quantum dots (QDs) motivate their use in a wide variety of applications related to imaging and bioanalysis, including the detection of proteases and their activity. Recent studies have shown that surface chemistry on QDs is able to modulate protease activity, but only nonspecifically. Here, we present a strategy to selectively accelerate the activity of a particular target protease by as much as two orders of magnitude. Exosite-binding "bait" peptides were derived from proteins that span a range of biological roles─substrate, receptor, and inhibitor─and were used to increase the affinity of the QD-peptide conjugates for either thrombin or factor Xa, resulting in increased rates of proteolysis for coconjugated substrates. Unlike effects from QD surface chemistry, the acceleration was specific to the target protease with negligible acceleration of other proteases. Benefits of this "bait and cleave" sensing approach included detection limits that improved by more than an order of magnitude, reenabled detection of target protease against an overwhelming background of nontarget proteolysis, and mitigation of the action of inhibitors. The cumulative results point to a generalizable strategy, where the mechanism of acceleration, considerations for the design of bait peptides and conjugates, and routes to expanding the scope of this approach are discussed. Overall, this research represents a major step forward in the rational design of nanoparticle-based enzyme sensors that enhance sensitivity and selectivity.

Assessing the Steric Impact of Surface Ligands on the Proteolytic Turnover of Quantum Dot-Peptide Conjugates.

Proteases are important biomarkers and targets for the diagnosis and treatment of disease. The advantageous properties of semiconductor quantum dots (QDs) have made these nanoparticles useful as probes for protease activity; however, the effects of QD surface chemistry on protease activity are not yet fully understood. Here, we present a systematic study of the impact of sterics on the proteolysis of QD-peptide conjugates. The study utilized eight proteases (chymotrypsin, trypsin, endoproteinase Lys C, papain, endoproteinase Arg C, thrombin, factor Xa, and plasmin) and 41 distinct surface chemistries. The latter included three molecular weights of each of three macromolecular ligands derived from dextran and polyethylene glycol, as well as anionic and zwitterionic small-molecule ligands, and an array of mixed coatings of macromolecular and small-molecule ligands. These surface chemistries spanned a diversity of thicknesses, densities, and packing organization, as characterized by gel electrophoresis, capillary electrophoresis, dynamic light scattering, and infrared spectroscopy. The macromolecular ligands decreased the adsorption of proteases on the QDs and decelerated proteolysis of the QD-peptide conjugates via steric hindrance. The properties of the QD surface chemistry, rather than the protease properties, were the main factor in determining the magnitude of deceleration. The broad scope of this study provides insights into the many ways in which QD surface chemistry affects protease activity, and will inform the development of optimized nanoparticle-peptide conjugates for sensing of protease activity and resistance to unwanted proteolysis.

Are Bradycardic Donors More Likely to Have Adverse Outcomes During Blood Donation?

INTRODUCTION: In order to decrease adverse donor reactions during blood donation, volunteers are screened to safely donate according to the U.S. Food and Drug Administration standards. Volunteers must be normocardic, with a pulse between 50 and 100 beats per minute. Bradycardic volunteers with a pulse lower than 50 beats per minute who otherwise meet requirements may donate with physician approval. Blood donors in military settings tend to be younger and more physically fit than the average donor population, resulting in a higher percentage of bradycardic donors. The relationship between bradycardia and adverse donor reactions has not been well studied. Herein, we aim to compare post-donation adverse reactions and the ability to complete donation between normocardic and bradycardic donors. MATERIALS AND METHODS: Institutional review board approval was obtained. Records from a single blood donor center located on a large military installation in 2019 were retrospectively reviewed for vital signs, demographics, hemoglobin, and donor reactions. Donors were categorized as normocardic or bradycardic. The two groups were statistically compared using a χ2 test. RESULTS: Of the 1,601 donors in the study period, 1,514 qualified for donation. Mean age was 26.6 years (range, 17-72 years), with a male to female ratio of 2.1:1. Of these, 1,478 were normocardic and 26 were bradycardic. There was no significant difference in adverse reactions between the two groups (5.6% in bradycardic donors versus 3.6% in normocardic donors, n = 1,514, χ21 = 0.39, P = .53) or percentage of incomplete donations (5.9% in bradycardic and 5.65% in normocardic, n = 1,514, χ21 = 0.003, P = .96). CONCLUSIONS: Donors with bradycardia are as safe to donate as normocardic donors. In the absence of comorbidities, blood donor centers should ensure their policies consider donation for volunteers with bradycardia.

Home-delivered meals for people with dementia: Which model delays nursing home placement? - Protocol for a feasibility pilot.

BACKGROUND: Home-delivered meals promote food security, socialization, and independence among homebound older adults. However, it is unclear which of the two predominant modes of meal delivery, daily-delivered vs. drop-shipped, frozen meals, promotes community living for homebound older adults with dementia. Our objective is to present the protocol for a pilot multisite, two-arm, pragmatic feasibility trial comparing the effect of two modes of meal delivery on nursing home placement among people with dementia. We include justifications for individual randomization with different consent processes and waivers for specific elements of the trial. METHODS: 236 individuals with dementia on waiting lists at three Meals on Wheels programs' in Florida and Texas will be randomized to receive either: 1) meals delivered multiple times per week by a Meals on Wheels volunteer or paid driver who may socialize with and provide an informal wellness check or 2) frozen meals that are mailed to participants' homes every two weeks. We will evaluate and refine processes for recruitment and randomization; assess adherence to the intervention; identify common themes in participant experience; and test processes for linking participant data with Medicare records and nursing home assessment data. We will conduct exploratory analyses examining time to nursing home placement, the primary outcome for the larger trial. CONCLUSION: This pilot will inform the follow-on large-scale, definitive pragmatic trial. In addition, the justifications for individual randomization with differing consent procedures for elements of a pragmatic trial provide a model for future trialists looking to develop ethical and feasible pragmatic studies enrolling people with dementia.

A systematic review and qualitative analysis of geriatric models of care for rural and remote populations.

INTRODUCTION: Much is known about the healthcare needs of rural and remote communities; however, understanding how to best deliver geriatric models of care in these settings has received less attention. The purpose of this systematic review was to identify necessary key components of existing models of geriatric care serving rural or remote populations. METHODS: A systematic literature review was conducted using MEDLINE, CINAHL and EMBASE databases to identify articles that described models of geriatric care serving rural or remote populations. A qualitative case study and key component analysis approach was used to identify necessary model components. RESULTS: Eight articles were included. We identified eight distinct components that may improve the successful delivery of models of geriatric care serving rural or remote populations. Environmental assessments were done in six of eight models. Model integration with the local healthcare system, local provider leadership, and local provider education in geriatrics were present in five of eight models. Three of eight models used high-risk screening principles and included geriatrician consultation. One model described active community engagement, and one used telemedicine. CONCLUSION: Future geriatric care delivery models designed to serve rural or remote populations are encouraged to use an evidence-based framework based on eight distinct model characteristics found in the literature that aim to support the ideal provision of effective and accessible geriatric medical care.

Developing FRET Networks for Sensing.

Förster resonance energy transfer (FRET) is a widely used fluorescence-based sensing mechanism. To date, most implementations of FRET sensors have relied on a discrete donor-acceptor pair for detection of each analytical target. FRET networks are an emerging concept in which target recognition perturbs a set of interconnected FRET pathways between multiple emitters. Here, we review the energy transfer topologies and scaffold materials for FRET networks, propose a general nomenclature, and qualitatively summarize the dynamics of the competitive, sequential, homoFRET, and heteroFRET pathways that constitute FRET networks. Implementations of FRET networks for sensing are also described, including concentric FRET probes, other single-vector multiplexing, and logic gates and switches. Unresolved questions and future research directions for current systems are discussed, as are potential but currently unexplored applications of FRET networks in sensing.

Therapeutic Hypothermia in Transport Permits Earlier Treatment Regardless of Transfer Distance.

OBJECTIVE: Therapeutic hypothermia (TH) is currently the only effective therapy available to improve outcomes in neonates with hypoxic-ischemic encephalopathy (HIE) and has maximal effect when initiated within 6 hours of birth. Neonates affected by HIE are commonly born outside of cooling centers and transport is a barrier to timely initiation. In this study, we sought to determine if the initiation of servo-controlled TH in transport allowed neonates to reach target temperature earlier, without a significant delay in the transfer process, for both local and long-distance transport. STUDY DESIGN: In this single-center cohort study of neonates referred to a level IV neonatal intensive care unit for TH, we determined the chronologic age at which target temperature was reached for those cooled in transport. Short-term outcome measures were assessed, including survival, incidence of electrographic seizures, discharge feeding method, and length of hospitalization. RESULTS: In a study population of 85 neonates, those receiving TH during transport (n = 23), achieved target temperature (33-34°C) 77 minutes sooner (230 ± 71 vs. 307 ± 79 minutes of life (MOL); p < 0.001). Locally transported neonates (<15 miles) achieved target temperature 69 minutes earlier (215 ± 48 vs. 284 ± 74 MOL; p < 0.01). TH during long-distance transports allowed neonates to reach target temperature 81 minutes sooner (213 ± 85 vs. 294 ± 79 MOL; p < 0.01). Infants who were cooled in transport discharged 4 days earlier (13.7 ± 8 vs. 17.8 ± 13 days; p = 0.18) and showed a significantly higher rate of oral feeding at discharge (95 vs. 71%; p = 0.03). CONCLUSION: For those starting TH in transport, time to target temperature was decreased. In our cohort, cooling in transport was associated with improved short-term outcomes, although additional studies are needed to correlate these findings with long-term outcomes. KEY POINTS: · Therapeutic hypothermia started during transport allows shorter time to target temperature.. · Transfer was minimally delayed by starting cooling in transport.. · Cooling in transport was associated with increased rate of oral feeding at hospital discharge..

Preparation and Characterization of Quantum Dot-Peptide Conjugates Based on Polyhistidine Tags.

Quantum dots (QDs) offer bright and robust photoluminescence among several other advantages in comparison to fluorescent dyes. In order to leverage the advantageous properties of QDs for applications in bioanalysis and imaging, simple and reliable methods for bioconjugation are required. One such method for conjugating peptides to QDs is the use of polyhistidine tags, which spontaneously bind to the surface of QDs. We describe protocols for assembling polyhistidine-tagged peptides to QDs and for characterizing the resultant QD-peptide conjugates. The latter include both electrophoretic and FRET-based protocols for confirming successful peptide assembly, estimating the maximum peptide loading capacity, and measuring the assembly kinetics. Sensors for protease activity and intracellular delivery are briefly noted as prospective applications of QD-peptide conjugates.

Photoluminescent Nanoparticles for Chemical and Biological Analysis and Imaging.

Research related to the development and application of luminescent nanoparticles (LNPs) for chemical and biological analysis and imaging is flourishing. Novel materials and new applications continue to be reported after two decades of research. This review provides a comprehensive and heuristic overview of this field. It is targeted to both newcomers and experts who are interested in a critical assessment of LNP materials, their properties, strengths and weaknesses, and prospective applications. Numerous LNP materials are cataloged by fundamental descriptions of their chemical identities and physical morphology, quantitative photoluminescence (PL) properties, PL mechanisms, and surface chemistry. These materials include various semiconductor quantum dots, carbon nanotubes, graphene derivatives, carbon dots, nanodiamonds, luminescent metal nanoclusters, lanthanide-doped upconversion nanoparticles and downshifting nanoparticles, triplet-triplet annihilation nanoparticles, persistent-luminescence nanoparticles, conjugated polymer nanoparticles and semiconducting polymer dots, multi-nanoparticle assemblies, and doped and labeled nanoparticles, including but not limited to those based on polymers and silica. As an exercise in the critical assessment of LNP properties, these materials are ranked by several application-related functional criteria. Additional sections highlight recent examples of advances in chemical and biological analysis, point-of-care diagnostics, and cellular, tissue, and in vivo imaging and theranostics. These examples are drawn from the recent literature and organized by both LNP material and the particular properties that are leveraged to an advantage. Finally, a perspective on what comes next for the field is offered.

Sigmoid cancer mimicking ovarian echotexture on transvaginal ultrasound: Case report with literature review.

Ultrasound is a first line imaging modality for the evaluation of female pelvic pain. Pelvic pain constitutes one of the most common reasons for presentation to the emergency department with increasing use of point of care ultrasound. Infrequently, point of care or formal ultrasound evaluation may lead to misdiagnosis of extraovarian disease. This can have serious consequences, especially if an extraovarian malignancy is mistaken for a normal ovary or an ovary with a benign process. We present a case of a 41-year-old female who presented to the emergency department for a chief complaint of pelvic pain and vaginal bleeding. Transvaginal ultrasound demonstrated a left adnexal mass, later characterized as a sigmoid colon cancer on MRI and pathology, simulating ovarian echotexture with peripheral hypoechoic components resembling follicles. This article will review the literature of various cases of extraovarian pathology misidentified as ovarian processes and highlight the importance of considering these extraovarian mimickers to prevent potential morbidity and mortality of a missed diagnosis.

Dextran-Functionalized Semiconductor Quantum Dot Bioconjugates for Bioanalysis and Imaging.

The prerequisites for maximizing the advantageous optical properties of colloidal semiconductor quantum dots (QDs) in biological applications are effective surface functionalization and bioconjugation strategies. Functionalization with dextran has been highly successful with some nanoparticle materials, but has had very limited application with QDs. Here, we report the preparation, characterization, and proof-of-concept applications of dextran-functionalized QDs. Multiple approaches to dextran ligands were evaluated, including performance with respect to colloidal stability across a range of pH, nonspecific binding with proteins and cells, and microinjection into cells and viability assays. Multiple bioconjugation strategies were demonstrated and applied, including covalent coupling to develop a simple pH sensor, binding of polyhistidine-tagged peptides to the QD for energy transfer-based proteolytic activity assays, and binding with tetrameric antibody complexes (TACs) to enable a sandwich immunoassay and cell immunolabeling and imaging. Our results show that dextran ligands are highly promising for the functionalization of QDs, and that the design of the ligands is tailorable to help optimally meet the requirements of applications.

Accelerated Structural Prediction of Flexible Protein-Ligand Complexes: The SLICE Method.

Using existing and academically available software, we present a new method for the structural prediction of binding events containing flexible protein targets. SLICE (Selective Ligand-Induced Conformational Ensemble) combines opportunistic stochastic jumps of ligand position with standard molecular dynamics to model the induced-fit binding of ligands starting with unbound host coordinates. To induce the structural adaptations of the complex at the binding site, conformational jumps in ligand position are selected in SLICE from structures generated by a docking software. Multiple binding trajectories from the docking set are followed using molecular dynamics for a set time to relax the host structure and generate new host poses. A new configurational jump is made on the set of newly generated host poses. The process is then repeated. The method was implemented with AutoDock Vina as the docking method, Vina scores as the selection criterion, and Amber code for molecular dynamics and applied to several test systems. A system consisting of Chromobox protein homologue 8 (CBX8) and its small peptide ligand, H3K9Me3, for which the final (bound) configuration is known, is used for verifying SLICE in the present setup. The setup was also applied to several nonpeptide molecules on known difficult flexible targets exhibiting a large disparity between apo and holo host states. The SLICE simulations provide a promising approach to generate induced-fit configurations compared to existing long (microsecond) classical and accelerated dynamics approaches in all the test systems considered here. However, further optimization of SLICE parameters is required for replicating crystal structure coordinates for some systems. We discuss in the following pages the various SLICE parameters and how they can be optimized for the system at hand.

Concentric FRET: a review of the emerging concept, theory, and applications.

Concentric Förster resonance energy transfer (cFRET) is an emerging concept for single-vector multiplexed bioanalysis and imaging. It features a network of competitive and sequential energy transfer pathways, which, to date, has been assembled with a central semiconductor quantum dot (QD) and biomolecular linkers to multiple copies of multiple types of concentrically-arranged fluorescent dyes. In this review, we provide a first-hand account of the concept and development of cFRET, starting from its place in the broader context of FRET probes and assemblies. Topics of discussion include materials for cFRET, with a focus on the enabling properties of QDs and the ideal properties of nominal acceptor dyes; characterization and analysis of cFRET configurations via photoluminescence intensity, emission ratio, lifetime, and photobleaching measurements; semi-empirical modeling to determine the rates and efficiencies of competitive and sequential FRET pathways from overall quenching efficiencies; and archetypical examples of cFRET configurations and their application in bioanalysis and imaging. Most of the latter examples demonstrate multiplexed detection of protease activity or nucleic acid targets. Examples of atypical and cFRET-like configurations are also discussed, including those that utilize time-gated FRET relays and charge-transfer quenching. We conclude with a perspective on challenges and directions for future research with cFRET. Although still emerging as a method, many exciting opportunities in bioanalysis, imaging, and beyond are envisioned for cFRET.

Cationic 2,2'-bipyridine complexes of germanium(ii) and tin(ii).

We present the first systematic study of 2,2'-bipyridine complexes of E(ii) cationic acceptors (E = Ge, Sn). The complexes were comprehensively characterized by spectroscopic and crystallographic methods to yield complexes of ECl1+ and E2+. Computational DFT methods were also employed to survey the bonding in the cations, along with an examination of their molecular orbitals (MOs).

Interplay between adsorbed peptide structure, trapped water, and surface hydrophobicity.

Atomistic molecular dynamics simulations were used to study the influence of interfacial water on the orientation and conformation of a facewise amphipathic α-helical peptide adsorbed to hydrophilic and hydrophobic substrates. Water behavior beneath the peptide adsorbed to a hydrophilic surface was observed to vary with the height of the peptide above the surface. In general, the orientation of water close to the peptide (with the oxygen atom pointing up toward the peptide) was complementary to that observed near the hydrophilic surface in the absence of peptide. That is, no change in orientation of water trapped between the peptide and a hydrophilic surface is required as the peptide approaches the surface. The adsorption of the peptide to the hydrophilic surface was observed to be mediated by a layer of ordered water. Water was found to be largely excluded on adsorption to the hydrophobic surface. However, the small amount of water present was observed to be highly ordered. At the closest point of contact to the hydrophobic surface, the peptide was observed to make direct contact. These findings shed light on the fundamental driving forces of peptide adsorption to hydrophobic and hydrophilic surfaces in aqueous environments.

Effects of Making Art and Listening to Music on Symptoms Related to Blood and Marrow Transplantation.

PURPOSE/OBJECTIVES: To understand the benefits of making art and listening to music and whether those activities may be beneficial for reducing symptoms associated with blood and marrow transplantation. 
. DESIGN: A randomized, three-group, pre-/post-pilot design.
. SETTING: Outpatient Blood and Marrow Transplant Clinic at the University of Kansas Cancer Center in Kansas City.
. SAMPLE: 39 adults aged from 22-74 years receiving blood and marrow transplantations.
. METHODS: Participants were randomly assigned to one of three groups. MAIN RESEARCH VARIABLES: Therapy-related symptoms, state anxiety, and physiologic distress.
. FINDINGS: Of the 39 participants, 14 were randomized to the control group, 14 to the art group, and 11 to the diversional music group. No significant differences in age, gender, ethnicity, or diagnosis existed between groups. No statistical differences were found between groups on all measures following the intervention. 
. CONCLUSIONS: Although the results of the current study did not indicate significant differences, healthcare professionals may still consider creative therapies as a viable option for patients within hospital or outpatient clinics because they do not require specialty training or costly resources, and they may be an enjoyable activity to occupy time for patients and caregivers.
. IMPLICATIONS FOR NURSING: Art making and music listening are safe and desirable for patients undergoing blood and marrow transplantation in an outpatient clinic. Nurses might consider partnering with therapists to offer these creative therapies as diversion during treatment.

The first survey of attitudes of medical students in Ireland towards termination of pregnancy.

BACKGROUND: Since the UK Abortion Act (1967), women have travelled from Ireland to the UK for legal abortion. In 2011 >4000 women did so. Knowledge and attitudes of medical students towards abortion have been published, however, this is the first such report from Ireland. OBJECTIVE: To investigate medical students' attitudes towards abortion in Ireland. METHODS: All medical students at the University of Limerick, and physicians who graduated from the university within the previous 12 months, were invited via email to complete an anonymous online survey. The questionnaire comprised 17 questions. Quantitative and qualitative analyses were performed. RESULTS: Response rate was 45% (n=169; 55% women; 88.2% <30 years of age; 66.7% Irish; 29.2% North American). Outcomes were: abortion should not be legally available (7.1%), abortion should be allowed in limited circumstances only (35.5%), abortion should be legally available upon request (55%). 72.8% of respondents were moderately/strongly prochoice (74% of women/71% of men/72% and 76% of Irish and North American respondents, respectively). Students aged >30 years were less likely to be prochoice (55%). While 95.2% believed that education on abortion should be offered within medical school curricula, 28.8% stated that they would decline to terminate pregnancies even if legally permitted. While 58.8% indicated that they might perform legal abortions once qualified, 25.7% would do so under limited circumstances only. CONCLUSIONS: The majority of participants wanted education regarding abortion. Despite being predominantly prochoice, considerably fewer students, irrespective of nationality, indicated that they would perform abortions.