Nanoparticle Retinoic Acid-Inducible Gene I Agonist for Cancer Immunotherapy.

Pharmacological activation of the retinoic acid-inducible gene I (RIG-I) pathway holds promise for increasing tumor immunogenicity and improving the response to immune checkpoint inhibitors (ICIs). However, the potency and clinical efficacy of 5'-triphosphate RNA (3pRNA) agonists of RIG-I are hindered by multiple pharmacological barriers, including poor pharmacokinetics, nuclease degradation, and inefficient delivery to the cytosol where RIG-I is localized. Here, we address these challenges through the design and evaluation of ionizable lipid nanoparticles (LNPs) for the delivery of 3p-modified stem-loop RNAs (SLRs). Packaging of SLRs into LNPs (SLR-LNPs) yielded surface charge-neutral nanoparticles with a size of ∼100 nm that activated RIG-I signaling in vitro and in vivo. SLR-LNPs were safely administered to mice via both intratumoral and intravenous routes, resulting in RIG-I activation in the tumor microenvironment (TME) and the inhibition of tumor growth in mouse models of poorly immunogenic melanoma and breast cancer. Significantly, we found that systemic administration of SLR-LNPs reprogrammed the breast TME to enhance the infiltration of CD8+ and CD4+ T cells with antitumor function, resulting in enhanced response to αPD-1 ICI in an orthotopic EO771 model of triple-negative breast cancer. Therapeutic efficacy was further demonstrated in a metastatic B16.F10 melanoma model, with systemically administered SLR-LNPs significantly reducing lung metastatic burden compared to combined αPD-1 + αCTLA-4 ICI. Collectively, these studies have established SLR-LNPs as a translationally promising immunotherapeutic nanomedicine for potent and selective activation of RIG-I with the potential to enhance response to ICIs and other immunotherapeutic modalities.

A Cancer Nanovaccine for Co-Delivery of Peptide Neoantigens and Optimized Combinations of STING and TLR4 Agonists.

Immune checkpoint blockade (ICB) has revolutionized cancer treatment and led to complete and durable responses, but only for a minority of patients. Resistance to ICB can largely be attributed to insufficient number and/or function of antitumor CD8+ T cells in the tumor microenvironment. Neoantigen targeted cancer vaccines can activate and expand the antitumor T cell repertoire, but historically, clinical responses have been poor because immunity against peptide antigens is typically weak, resulting in insufficient activation of CD8+ cytotoxic T cells. Herein, we describe a nanoparticle vaccine platform that can overcome these barriers in several ways. First, the vaccine can be reproducibly formulated using a scalable confined impingement jet mixing method to coload a variety of physicochemically diverse peptide antigens and multiple vaccine adjuvants into pH-responsive, vesicular nanoparticles that are monodisperse and less than 100 nm in diameter. Using this approach, we encapsulated synergistically acting adjuvants, cGAMP and monophosphoryl lipid A (MPLA), into the nanocarrier to induce a robust and tailored innate immune response that increased peptide antigen immunogenicity. We found that incorporating both adjuvants into the nanovaccine synergistically enhanced expression of dendritic cell costimulatory markers, pro-inflammatory cytokine secretion, and peptide antigen cross-presentation. Additionally, the nanoparticle delivery increased lymph node accumulation and uptake of peptide antigen by dendritic cells in the draining lymph node. Consequently, nanoparticle codelivery of peptide antigen, cGAMP, and MPLA enhanced the antigen-specific CD8+ T cell response and delayed tumor growth in several mouse models. Finally, the nanoparticle platform improved the efficacy of ICB immunotherapy in a murine colon carcinoma model. This work establishes a versatile nanoparticle vaccine platform for codelivery of peptide neoantigens and synergistic adjuvants to enhance responses to cancer vaccines.

Engineering endosomolytic nanocarriers of diverse morphologies using confined impingement jet mixing.

The clinical translation of many biomolecular therapeutics has been hindered by undesirable pharmacokinetic (PK) properties, inadequate membrane permeability, poor endosomal escape and cytosolic delivery, and/or susceptibility to degradation. Overcoming these challenges merits the development of nanoscale drug carriers (nanocarriers) to improve the delivery of therapeutic cargo. Herein, we implement a flash nanoprecipitation (FNP) approach to produce nanocarriers of diverse vesicular morphologies by using various molecular weight PEG-bl-DEAEMA-co-BMA (PEG-DB) polymers. We demonstrated that FNP can produce uniform (PDI < 0.1) particles after 5 impingements, and that by varying the copolymer hydrophilic mass fraction, FNP enables access to a diverse variety of nanoarchitectures including micelles, unilamellar vesicles (polymersomes), and multi-compartment vesicles (MCVs). We synthesized a library of 2 kDa PEG block copolymers, with DEAEMA-co-BMA second block molecular weights of 3, 6, 12, 15, 20, and 30 kDa. All formulations were both pH responsive, endosomolytic, and capable of loading and cytosolically delivering small negatively charged molecules - albeit to different degrees. Using a B16.F10 melanoma model, we showcased the therapeutic potential of a lead FNP formulated PEG-DB nanocarrier, encapsulating the cyclic dinucleotide (CDN) cGAMP to activate the stimulator of interferon genes (STING) pathway in a therapeutically relevant context. Collectively, these data demonstrate that an FNP process can be used to formulate pH-responsive nanocarriers of diverse morphologies using a PEG-DB polymer system. As FNP is an industrially scalable process, these data address the critical translational challenge of producing PEG-DB nanoparticles at scale. Furthermore, the diverse morphologies produced may specialize in the delivery of distinct biomolecular cargos for other therapeutic applications, implicating the therapeutic potential of this platform in an array of disease applications.

Chromatin reprogramming and bone regeneration in vitro and in vivo via the microtopography-induced constriction of cell nuclei.

Topographical cues on cells can, through contact guidance, alter cellular plasticity and accelerate the regeneration of cultured tissue. Here we show how changes in the nuclear and cellular morphologies of human mesenchymal stromal cells induced by micropillar patterns via contact guidance influence the conformation of the cells' chromatin and their osteogenic differentiation in vitro and in vivo. The micropillars impacted nuclear architecture, lamin A/C multimerization and 3D chromatin conformation, and the ensuing transcriptional reprogramming enhanced the cells' responsiveness to osteogenic differentiation factors and decreased their plasticity and off-target differentiation. In mice with critical-size cranial defects, implants with micropillar patterns inducing nuclear constriction altered the cells' chromatin conformation and enhanced bone regeneration without the need for exogenous signalling molecules. Our findings suggest that medical device topographies could be designed to facilitate bone regeneration via chromatin reprogramming.

Trends and risk factors for readmissions following press-fit total knee arthroplasty for the treatment of end-stage osteoarthritis of the knee: a five-year analysis.

INTRODUCTION: The development of new prostheses with improved osseointegration, bone preservation, and reduced cost has renewed interest in uncemented total knee arthroplasty (UCTKA). In the current study, we aimed to: (1) assess demographic data of patients who were and were not readmitted and (2) identify patient-specific risk factors associated with readmission. METHODS: A retrospective query from the PearlDiver database was performed from January 1, 2015, to October 31, 2020. International Classification of Disease, Ninth Revision (ICD-9), ICD-10, or Current Procedural Terminology (CPT) coding was used to distinguish cohorts of patients who had osteoarthritis of the knee and underwent UCTKA. Patients readmitted within 90 days were classified as the study population, while those who were not readmitted were classified as control. A linear regression model was utilized to analyze readmission risk factors. RESULTS: The query yielded 14,575 patients, with 986 (6.8%) being readmitted. Patient demographics such as age (P < 0.0001), sex (P < 0.009), and comorbidity (P < 0.0001) were associated with annual 90-day readmission. Patient-specific risk factors associated with 90-day readmission following press-fit total knee arthroplasty were: arrhythmia (OR: 1.29, 95% CI: 1.11-1.49, P < 0.0005), coagulopathy (OR: 1.36, 95% CI: 1.13-1.63, P < 0.0007), fluid and electrolyte abnormalities (OR: 1.59, 95% CI: 1.38-1.84, P < 0.0001), iron deficiency anemia (OR: 1.49, 95% CI: 1.27-1.73, P < 0.0001), and obesity (OR: 1.37, 95% CI: 1.18-1.60, P < 0.0001). DISCUSSION: This study demonstrates that patients with comorbidities, such as fluid and electrolyte problems, iron deficiency anemia, and obesity, were at an increased risk of readmission after having an uncemented total knee replacement. The risks of readmission following an uncemented total knee arthroplasty can be discussed with patients who have certain comorbidities by arthroplasty surgeons.

The association of QTc prolongation with cardiovascular events in cancer patients taking tyrosine kinase inhibitors (TKIs).

OBJECTIVE: To investigate the association between stages of QTc prolongation and the risk of cardiac events among patients on TKIs. METHODS: This was a retrospective cohort study performed at an academic tertiary care center of cancer patients who were taking TKIs or not taking TKIs. Patients with two recorded ECGs between January 1, 2009, and December 31, 2019, were selected from an electronic database. The QTc duration > 450ms was determined as prolonged. The association between QTc prolongation progression and events of cardiovascular disease were compared. RESULTS: This study included a total of 451 patients with 41.2% of patients taking TKIs. During a median follow up period of 3.1 years, 49.5% subjects developed CVD and 5.4% subjects suffered cardiac death in patient using TKIs (n = 186); the corresponding rates are 64.2% and 1.2% for patients not on TKIs (n = 265), respectively. Among patient on TKIs, 4.8% of subjects developed stroke, 20.4% of subjects suffered from heart failure (HF) and 24.2% of subjects had myocardial infarction (MI); corresponding incidence are 6.8%, 26.8% and 30.6% in non-TKIs. When patients were regrouped to TKIs versus non-TKIs with and without diabetes, there was no significant difference in the incidence of cardiac events among all groups. Adjusted Cox proportional hazards models were applied to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). There is a significant increased risk of HF events (HR, 95% CI: 2.12, 1.36-3.32) and MI events (HR, 95% CI: 1.78, 1.16-2.73) during the 1st visit. There are also trends for an increased incidence of cardiac adverse events associated with QTc prolongation among patient with QTc > 450ms, however the difference is not statistically significant. Increased cardiac adverse events in patients with QTc prolongation were reproduced during the 2nd visit and the incidence of heart failure was significantly associated with QTc prolongation(HR, 95% CI: 2.94, 1.73-5.0). CONCLUSION: There is a significant increased QTc prolongation in patients taking TKIs. QTc prolongation caused by TKIs is associated with an increased risk of cardiac events.

Magnetically Powered Chitosan Milliwheels for Rapid Translation, Barrier Function Rescue, and Delivery of Therapeutic Proteins to the Inflamed Gut Epithelium.

Inflammatory bowel disease (IBD) is mediated by an overexpression of tumor necrosis factor-α (TNF) by mononuclear cells in the intestinal mucosa. Intravenous delivery of neutralizing anti-TNF antibodies can cause systemic immunosuppression, and up to one-third of people are non-responsive to treatment. Oral delivery of anti-TNF could reduce adverse effects; however, it is hampered by antibody degradation in the harsh gut environment during transit and poor bioavailability. To overcome these shortcomings, we demonstrate magnetically powered hydrogel particles that roll along mucosal surfaces, provide protection from degradation, and sustain the local release of anti-TNF. Iron oxide particles are embedded into a cross-linked chitosan hydrogel and sieved to produce 100-200 µm particles called milliwheels (m-wheels). Once loaded with anti-TNF, these m-wheels release 10 to 80% of their payload over 1 week at a rate that depends on the cross-linking density and pH. A rotating magnetic field induces a torque on the m-wheels that results in rolling velocities greater than 500 µm/s on glass and mucus-secreting cells. The permeability of the TNF-challenged gut epithelial cell monolayers was rescued in the presence of anti-TNF carrying m-wheels, which both neutralized the TNF and created an impermeable patch over leaky cell junctions. With the ability to translate over mucosal surfaces at high speed, provide sustained release directly to the inflamed epithelium, and provide barrier rescue, m-wheels demonstrate a potential strategy to deliver therapeutic proteins for the treatment of IBD.

The influence of prior dental pathology on medical complications and peri-prosthetic joint infections following primary shoulder arthroplasty.

PURPOSE: Antibiotic prophylaxis before invasive dental procedures is a common practice in the USA. Consensus regarding the influence of prior dental pathology (DP) on postoperative complications is lacking. The objectives are to determine the association of DP prior to shoulder arthroplasty (SA) on: (1) lengths of stay (LOS), (2) medical complications, (3) readmissions, (4) implant-related complications including peri-prosthetic joint infections (PJIs) and (5) healthcare expenditures. METHODS: The PearlDiver database was queried for primary shoulder arthroplasty from 2010 to 2020. Patients with history of dental caries or dental implant placement before SA represented the study group (n = 1419). Patients without prior DP represented controls (n = 7062). Study group patients were 1:5 ratio matched to controls by age, sex, and comorbidities. Outcomes included LOS, 90-day complications, readmissions, 2-year implant-related complications, and healthcare reimbursements. Logistic regression was used to calculate odds ratios (OR) of complications and readmissions. T tests compared LOS and costs. P values < 0.003 were significant. RESULTS: LOS (2.17 vs. 2.07 days; p = 0.071) were similar between groups. Patients with DP had higher 90-day medical complications compared to controls (OR: 1.74, p < 0.0001), including myocardial infarctions (2.2% vs. 0.8%; OR: 2.79, p < 0.0001), acute kidney injuries (8.3% vs. 4.6%; OR: 1.92, p < 0.0001), and pneumonias (8.7% vs. 5.3%; OR: 1.72, p < 0.0001). Readmission rates (1.97% vs. 1.54%; p = 0.248) were similar. Two-year implant complications were higher in patients with DP compared to controls (16.1% vs. 11.5%; OR: 1.38, p = 0.0003), including dislocations (6.4% vs. 4.5%; OR: 1.45, p = 0.002) and mechanical loosenings (4.0% vs. 2.4%; OR: 1.67, p = 0.001); however, PJIs were similar (2.2% vs. 1.9%; OR: 1.12, p = 0.583). Healthcare expenditures between groups were similar ($12,611 vs. $12,059; p = 0.075). CONCLUSION: Patients with prior DP have higher 90-day medical complications and 2-year implant-related complications. Two-year incidence of PJIs were similar between groups. These findings can help shoulder surgeons counsel patients with a pertinent dental history. LEVEL OF EVIDENCE III: Retrospective comparative study.

ROS-Responsive Glycopolymeric Nanoparticles for Enhanced Drug Delivery to Macrophages.

Macrophages play a diverse, key role in many pathologies, including inflammatory diseases, cardiovascular diseases, and cancer. However, many therapeutic strategies targeting macrophages suffer from systemic off-target toxicity resulting in notoriously narrow therapeutic windows. To address this shortcoming, the development of poly(propylene sulfide)-b-poly(methacrylamidoglucopyranose) [PPS-b-PMAG] diblock copolymer-based nanoparticles (PMAG NPs) capable of targeting macrophages and releasing drug in the presence of reactive oxygen species (ROS) is reported. PMAG NPs have desirable physicochemical properties for systemic drug delivery, including slightly negative surface charge, ≈100 nm diameter, and hemo-compatibility. Additionally, due to the presence of PPS in the NP core, PMAG NPs release drug cargo preferentially in the presence of ROS. Importantly, PMAG NPs display high cytocompatibility and are taken up by macrophages in cell culture at a rate ≈18-fold higher than PEGMA NPs-NPs composed of PPS-b-poly(oligoethylene glycol methacrylate). Computational studies indicate that PMAG NPs likely bind with glucose transporters such as GLUT 1/3 on the macrophage cell surface to facilitate high levels of internalization. Collectively, this study introduces glycopolymeric NPs that are uniquely capable of both receptor-ligand targeting to macrophages and ROS-dependent drug release and that can be useful in many immunotherapeutic settings.

Lipid Phase Separation in Vesicles Enhances TRAIL-Mediated Cytotoxicity.

Ligand spatial presentation and density play important roles in signaling pathways mediated by cell receptors and are critical parameters when designing protein-conjugated therapeutic nanoparticles. Here, we harness lipid phase separation to spatially control the protein presentation on lipid vesicles. We use this system to improve the cytotoxicity of TNF-related apoptosis inducing ligand (TRAIL), a therapeutic anticancer protein. Vesicles with phase-separated TRAIL presentation induce more cell death in Jurkat cancer cells than vesicles with uniformly presented TRAIL, and cytotoxicity is dependent on TRAIL density. We assess this relationship in other cancer cell lines and demonstrate that phase-separated vesicles with TRAIL only enhance cytotoxicity through one TRAIL receptor, DR5, while another TRAIL receptor, DR4, is less sensitive to TRAIL density. This work demonstrates a rapid and accessible method to control protein conjugation and density on vesicles that can be adopted to other nanoparticle systems to improve receptor signaling by nanoparticles.

Longitudinal uptake of the human papillomavirus vaccine among gay, bisexual and other men who have sex with men in British Columbia, Canada 2012-2019.

OBJECTIVES: In 2015, a publicly funded human papillomavirus (HPV) vaccination programme was implemented for gay, bisexual and other men who have sex with men (gbMSM) up to age 26 years in British Columbia, Canada. We assessed trends and correlates of HPV vaccine uptake from 2012 to 2019 in a cohort of gbMSM in Vancouver. METHODS: We recruited sexually active gbMSM aged ≥16 years using respondent-driven sampling from February 2012 to February 2015 and followed them until July 2019. We evaluated self-reported HPV vaccine trends using mixed-effects logistic regression and identified factors associated with uptake using multivariable mixed-effects Poisson regression. RESULTS: A total of 719 participants were recruited and completed the baseline visit, of whom 549 were unvaccinated with at least one follow-up visit. The median age was 33 years and 23% were living with HIV. HPV vaccination increased from 4% in 2012 to 28% in 2019 (p<0.001) among gbMSM >26 years, and from 9% in 2012 to 20% in 2017 (p<0.001) among gbMSM ≤26 years. Vaccination uptake increased after September 2015, following vaccination policy expansion (adjusted rate ratio (aRR)=1.82, 95% CI 1.06 to 3.12). In multivariable models, increased vaccination was associated with age ≤26 years vs ≥45 years (aRR=3.90; 95% CI 1.75 to 8.70), age 27-44 vs ≥45 years (aRR=2.86; 95% CI 1.46 to 5.62), involvement in gay community sports teams (aRR=2.31; 95% CI 1.15 to 4.64) and other groups (aRR=1.71; 95% CI 1.04 to 2.79), awareness of HIV-postexposure prophylaxis (aRR=5.50; 95% CI 1.31 to 23.09), recent sexually transmitted infection testing (aRR=2.72; 95% CI 1.60 to 4.60) and recent sex-work (aRR=2.59; 95% CI 1.08 to 6.19). CONCLUSIONS: Although we observed increases in HPV vaccination uptake from 2012, by 2019 HPV vaccination still remained below 30% among gbMSM in Vancouver, BC. Additional interventions are needed to increase vaccine uptake.

How Does Iron Deficiency Anemia Impact Outcomes following Revision Total Hip Arthroplasty?

PURPOSE: Studies have shown the prevalence of iron deficiency anemia (IDA) increasing worldwide, and currently the literature is limited on the impact of IDA on outcomes following revision total hip arthroplasty (RTHA). Therefore, the purpose of this study was to determine whether IDA patients undergoing RTHA have longer: 1) in-hospital lengths of stay (LOS); 2) medical complications; and 3) costs of care. MATERIALS AND METHODS: A retrospective query of a nationwide administrative claims database was performed. Using Boolean command operations, the study group consisted of all patients in the database undergoing RTHA with IDA; whereas, patients without IDA served as controls. To reduce the effects of confounding, study group patients were matched to controls in a 1:5 ratio by age, sex, and medical comorbidities yielding 92,948 patients with (n=15,508) and without (n=77,440) IDA undergoing revision THA. A P-value less than 0.001 was considered statistically significant. RESULTS: IDA patients were found to have significantly longer in-hospital LOS (5 days vs. 4 days, P<0.0001). Additionally, the study showed IDA patients were found to higher incidence and odds of (73.84% vs. 11.77%, OR 5.04, P<0.0001) 90-day medical complications. IDA patients also incurred high 90-day episode of care costs ($25,597.51 vs. $20,085.70, P<0.0001). CONCLUSION: After adjusting for age, sex, and medical comorbidities this study of over 92,000 patients demonstrated IDA is associated with longer in-hospital LOS, complications, and costs of care. Future studies should compare the duration and severity of IDA on outcomes.

An Elevated Metrorail as a Source of Orthopedic Injuries and Death at a Level-I Trauma Center.

Background: Elevated Metrorail systems differ from conventional trains by their slower speeds and collisions with pedestrians predominantly occurring at accessible stations or platforms. Here, the orthopedic implications of pedestrians struck by a Metrorail are evaluated, as were the correlations of substance abuse and psychiatric history on injury and death. Methods: Retrospective cohort study at a single Level-1 trauma center of patients requiring admission with orthopedic injuries following Metrorail impact from 1/2004-2/2017. Demographics, substance abuse, psychiatric history, intentionality, LOS, follow-up, fracture characteristics, and management were studied. Results: 33 patients sustained 104 total orthopedic injuries requiring admission; nine sustained 15 traumatic amputations. There were at least 37 open fractures, with some incomplete data in deceased (5) and amputation (9) patients. Suicide attempts were completed at 35.7% and were associated with a documented psychiatric illness and prior psychiatric evaluation. Spine injuries were associated with increased traumatic brain injuries, rib fractures, and open pelvic ring injuries, yet fewer humerus fractures. Open fractures were significantly predictive of death. 14 patients (42.4%) required ICU admission, and 26 (78.8%) patients required orthopaedic surgery (mean 1.3 ± 1.4 operations). Conclusions: Metrorail systems are unique sources of orthopaedic injuries requiring high rates of critical care and surgical intervention. Patients sustain multiple injuries, many with amputations. With this mechanism, there is a high rate of open fractures and suicide. Trauma centers should emphasize an extensive evaluation of orthopaedic injuries in this patient setting.Level of Evidence: II.

CEMIP upregulates BiP to promote breast cancer cell survival in hypoxia.

Cell migration-inducing protein (CEMIP) and binding immunoglobulin protein (BiP) are upregulated in human cancers, where they drive cancer progression and metastasis. It has been shown that CEMIP resides in the endoplasmic reticulum (ER) where it interacts with BiP to induce cell migration, but the relationship between the two proteins was previously unknown. Here we show that CEMIP mediates activation of the BiP promoter and upregulates BiP transcript and protein levels in breast cancer cell lines. Moreover, CEMIP overexpression confers protective adaptations to cancer cells under hypoxic conditions, by decreasing apoptosis, activating autophagy, and increasing glucose uptake, to facilitate tumor growth. We demonstrate that BiP signals downstream of CEMIP, modulating cellular resistance to hypoxia. Reducing BiP in CEMIP-expressing cells sensitized cells to hypoxia treatment, decreased glucose uptake, and resulted in tumor regression in vivo. Our study provides insights into the link between CEMIP and BiP expression and the pro-survival role they play in hypoxia. Better understanding of the mechanisms behind cancer cell adaptations to harsh tumor environments could lead to development of improved cancer treatments.

HIV Testing Among a Representative Community Sample of Gay, Bisexual, and Other Men Who Have Sex with Men in Vancouver, Canada.

Earlier HIV diagnosis allows for improved treatment outcomes and secondary prevention. It is recommended that all individuals know their HIV status and that those at higher risk test more frequently. Using a representative community sample of gay, bisexual, and other men who have sex with men (GBMSM), we aimed to: (1) determine the proportion of GBMSM who have tested in the past 2 years, (2) determine reasons for testing and never having tested, and (3) explore correlates of testing. Of 535 eligible participants, 80.0% reported having had an HIV test in the past 2 years, most commonly as part of a regular testing schedule. The most common reason for not testing was low perceived HIV risk. Bisexual and older GBMSM, as well as those who lived outside of Vancouver, were less likely to have tested in the past 2 years. Rapid point-of-care testing may help improve testing rates and was shown to effectively engage some hard-to-reach GBMSM (e.g., those who had not tested for other STIs) in this sample.

Spectroscopic and Microscopic Evidence of Biomediated HgS Species Formation from Hg(II)-Cysteine Complexes: Implications for Hg(II) Bioavailability.

We investigated the chemistry of Hg(II) during exposure of exponentially growing bacteria ( Escherichia coli, Bacillus subtilis, and Geobacter sulfurreducens) to 50 nM, 500 nM, and 5 µM total Hg(II) with and without added cysteine. With X-ray absorption spectroscopy, we provide direct evidence of the formation of cell-associated HgS for all tested bacteria. The addition of cysteine (100-1000 µM) promotes HgS formation (>70% of total cell-associated Hg(II)) as a result of the biodegradation of added cysteine to sulfide. Cell-associated HgS species are also detected when cysteine is not added as a sulfide source. Two phases of HgS, cinnabar (α-HgS) and metacinnabar (ß-HgS), form depending on the total concentration of Hg(II) and sulfide in the exposure medium. However, α-HgS exclusively forms in assays that contain an excess of cysteine. Scanning transmission electron microscopy images reveal that nanoparticulate HgS(s) is primarily located at the cell surface/extracellular matrix of Gram-negative E. coli and G. sulfurreducens and in the cytoplasm/cell membrane of Gram-positive B. subtilis. Intracellular Hg(II) was detected even when the predominant cell-associated species was HgS. This study shows that HgS species can form from exogenous thiol-containing ligands and endogenous sulfide in Hg(II) biouptake assays under nondissimilatory sulfate reducing conditions, providing new considerations for the interpretation of Hg(II) biouptake results.

Assessing the longitudinal stability of latent classes of substance use among gay, bisexual, and other men who have sex with men.

BACKGROUND: Association between substance use and HIV-risk among gay and bisexual men (GBM) is well documented. However, their substance use patterns are diverse, and it is unknown whether self-reported use patterns are stable over time. METHODS: Sexually-active GBM, aged >16 years, were recruited in Metro Vancouver using respondent-driven sampling and followed across 5 study visits at six-month intervals (n = 449). To identify distinct patterns of substance use and their longitudinal stability, Latent Transition Analysis (LTA) was conducted for drugs reported by at least 30 participants. Intraclass correlation coefficients (ICC) quantified the stability of class assignments. RESULTS: Six classes characterizing 'limited drug use' (i.e., low use of all drugs, except alcohol), 'conventional drug use' (i.e., use of alcohol, marijuana, and tobacco), 'club drug use' (i.e., use of alcohol, cocaine, and psychedelics), 'sex drug use' (i.e., use of alcohol, crystal meth, GHB, poppers, and erectile dysfunction drugs), 'street drug use' (i.e., use of alcohol and street opioids) and 'assorted drug use' (i.e., use of most drugs) were identified. Across five visits (2.5 years), 26.3% (n = 118/449) of GBM transitioned between classes. The prevalence of limited use trended upwards (Baseline:24.5%, Visit 5:28.3%, p < 0.0001) and assorted use trended downwards (13.4%-9.6%, p = 0.001). All classes had strong longitudinal stability (ICC > 0.97). CONCLUSION: The stability of latent substance use patterns highlight the utility of these measures in identifying patterns of substance use among people who use drugs - potentially allowing for better assessment of these groups and interventions related to their health.

How social media, training, and demographics influence online reviews across three leading review websites for spine surgeons.

BACKGROUND CONTEXT: The future of health care is consumer driven with a focus on outcome metrics and patient feedback. Physician review websites have grown in popularity and are guiding patients to certain health-care providers, for better or worse. No prior study has specifically evaluated Internet reviews of spine surgeons, determined if social media (SM) correlates with patient reviews, or evaluated Google as a physician review website. PURPOSE: This study aimed to evaluate patient satisfaction scores for spine surgeons in Florida using leading physician ratings websites. STUDY DESIGN: A retrospective study was carried out. SAMPLE POPULATION: The sample comprised spine surgeons with a review on Healthgrades.com (HG), Vitals.com (V), or Google.com (G) online rating websites as of August 17, 2017. OUTCOME MEASURES: Number of ratings, number of comments, overall rating, patient-reported wait times, physician website presence, and physician SM presence were the outcome measures. METHODS: Using the directory of registered North American Spine Society physicians, we identified all spine surgeons practicing in Florida (137 orthopedic trained; 78 neurosurgery trained). Surgeon demographics and ratings data were collected from three physician rating websites (HG, V, G) from July 19, 2017 to August 17, 2017. Using only the first 10 search results from Google.com we then identified if the surgeon had accounts on Facebook (FB), Twitter (TW), or Instagram (IG). RESULTS: Nearly every surgeon in this cohort had either an institutional or personal website (98.1%), and 38.6% had at least one SM outlet of our three reviewed. Both personal and institutional website presence significantly correlated with higher G scores. Spine surgeons with a searchable account on FB, TW, or IG made up 35.4%, 10.2%, and 0.5% of the cohort, respectively. Surgeons with an SM presence had a significantly higher number of ratings and comments on HG, V, and G, but not overall scores. In multivariable analysis, only V showed a significant inverse correlation between overall score and age, private institution, and orthopedic surgery training. Wait times >30 minutes were significantly associated with worse overall scores across all three review sites. Overall ratings between HG, V, and G all had significantly positive correlations on Pearson correlation analysis. CONCLUSION: Social media presence correlates with patient communication in the form of number of ratings and comments, yet does not impact overall scores, suggesting social media may influence patient feedback. Longer wait times are indicative of lower scores across all three platforms. Overall ratings from all three websites correlate significantly with each other, indicating agreement between physician ratings across different platforms. Understanding the factors that optimize a patient's overall experience with a physician is an important and emerging outcome measure for the future of patient-centered health care.

A latent class analysis of substance use and culture among gay, bisexual and other men who have sex with men.

Assessments of gay and bisexual men's substance use often obscures salient sociocultural and identity-related experiences related to how they use drugs. Latent class analysis was used to examine how patterns of substance use represent the social, economic and identity-related experiences of this population. Participants were sexually active gay and bisexual men (including other men who have sex with men), aged ≥ 16 years, living in Metro Vancouver (n = 774). LCA indicators included all substances used in the past six months self-reported by more than 30 men. Model selection was made with consideration to model parsimony, interpretability and optimisation of statistical criteria. Multinomial regression identified factors associated with class membership. A six-class solution was identified representing: 'assorted drug use' (4.5%); 'club drug use' (9.5%); 'street drug use' (12.1%); 'sex drug use' (11.4%); 'conventional drug use' (i.e. tobacco, alcohol, marijuana; 25.9%); and 'limited drug use' (36.7%). Factors associated with class membership included age, sexual orientation, annual income, occupation, income from drug sales, housing stability, group sex event participation, gay bars/clubs attendance, sensation seeking and escape motivation. These results highlight the need for programmes and policies that seek to lessen social disparities and account for social distinctions among this population.

Spine Trauma From Personal Watercraft Usage.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To identify patient characteristics and associated injuries in those sustaining a spine fracture from personal watercraft (PWC) usage. SUMMARY OF BACKGROUND DATA: There are few studies regarding PWC use and injuries, and even more scarce are studies evaluating PWC usage and spine injuries. Identifying high-risk actions and individuals can help to effectively treat them, reduce mortality, and possibly avoid certain spine fractures. METHODS: Retrospective analysis of 142 patients admitted from the emergency department with PWC-related injuries at a single-level I trauma center from January 1, 2004 to May 1, 2017. Twenty-six (18.3%) sustained a spine fracture, totaling 71 fractures. Statistical analysis was used to investigate the patient characteristics, specific mechanisms of injury, injury severity score (ISS), and associated injuries. Patients expiring (12) had incomplete evaluations and were excluded from most reported results. RESULTS: Spine fractures were not associated with age, race, or sex, but were associated with a higher ISS, intensive care unit length, in-patient length of stay, cerebral injury, and abdominal/genitourinary (GU) injury. There were 8 cervical fractures, 22 thoracic fractures, 33 lumbar, and 8 sacral fractures. Axial load injuries were associated with vertebral body fractures and specifically burst fractures. Being a driver or passenger did not influence likelihood of a spine fracture, but did correlate with abdominal/GU injury. Five (19.2%) of patients with spine fractures required eight spine surgeries during admission. Mortality was associated with females, severe systemic injuries (ISS ≥ 15), direct collision mechanism of injury, and the spring season. CONCLUSION: PWC usage may result in spine fractures with a moderate percentage requiring orthopedic surgery. Additional studies should examine how hull or seat modifications can lessen the risk of axial loads leading to spine fractures. PWC patients with spine fractures should also be evaluated for abdominal/GU and cerebral injuries at presentation. LEVEL OF EVIDENCE: 4.