Air Pollution Inequality in the Denver Metroplex and its Relationship to Historical Redlining.

Prior studies have shown that people of color (POC) in the United States are exposed to higher levels of pollution than non-Hispanic White people. We show that the city of Denver, Colorado, displays similar race- and ethnicity-based air pollution disparities by using a combination of high-resolution satellite data, air pollution modeling, historical demographic information, and areal apportionment techniques. TROPOMI NO2 columns and modeled PM2.5 concentrations from 2019 are higher in communities subject to redlining. We calculated and compared Spearman coefficients for pollutants and race at the census tract level for every city that underwent redlining to contextualize the disparities in Denver. We find that the location of polluting infrastructure leads to higher populations of POC living near point sources, including 40% higher Hispanic and Latino populations. This influences pollution distribution, with annual average PM2.5 surface concentrations of 6.5 µg m-3 in census tracts with 0-5% Hispanic and Latino populations and 7.5 µg m-3 in census tracts with 60-65% Hispanic and Latino populations. Traffic analysis and emission inventory data show that POC are more likely to live near busy highways. Unequal spatial distribution of pollution sources and POC have allowed for pollution disparities to persist despite attempts by the city to rectify them. Finally, we identify the core causes of the pollution disparities to provide direction for remediation.

Clinical Outcomes and Survivorship of Lateral Unicompartmental Knee Arthroplasty: A Large Single Surgeon Cohort.

BACKGROUND: Lateral unicompartmental knee arthroplasty (UKA) is an effective treatment for isolated lateral compartment osteoarthritis. However, due to the rarity of the procedure, long-term outcomes and survivorship are poorly understood. We report the clinical and radiographic outcomes after lateral UKA. METHODS: We retrospectively reviewed a consecutive series of patients who underwent lateral UKA by a single fellowship-trained arthroplasty surgeon from 2001 to 2021 with a minimum 2 year follow up. There were 161 knees in 153 patients (average age 69 years) that met inclusion criteria, with a mean follow up of 10.0 years (range 0.05 to 22.2). All patients underwent the procedure via a minimally invasive lateral parapatellar approach with a fixed-bearing implant. Patient demographics, complications, radiographic findings, patient-reported outcomes, and the need for revision surgery were evaluated. Survivorship was defined with the end point as revision of components. RESULTS: There were 8 patients (5.0%) who underwent conversion to total knee arthroplasty for lateral UKA implant failure or progression of arthritis. There were 3 patients (1.9%) who underwent ipsilateral medial UKA due to medial compartment arthritis progression with preserved mechanical alignment and patellofemoral joint. There were 8 additional procedures that did not require implant changes, including 5 irrigation and debridements for acute periprosthetic joint infection (3.1%), 2 wound closures for dehiscence (1.3%), and one loose body removal (0.6%). CONCLUSIONS: Lateral UKA showed a survivorship rate of 98.0% at 5 years, 96.0% at 10 years, and 94.5% at 15 years. When including patients who underwent additional surgery for the progression of arthritis, survivorship was 97.4% at 5 years, 95.4% at 10 years, and 91.3% at 15 years. Lateral UKA should be seen as a durable treatment option for isolated lateral compartment osteoarthritis.

Phase II trial of CV301 vaccine combined with atezolizumab in advanced urothelial carcinoma.

CV301 comprises recombinant poxviruses, Modified Vaccinia Ankara (MVA) and Fowlpox (FPV), encoding CEA, MUC-1, and co-stimulatory Molecules (TRICOM) ICAM-1, LFA-3, and B7-1. MVA-BN-CV301 is used for priming and FPV-CV301 is used for boosting. A Phase 2, single-arm trial was designed to evaluate CV301 plus atezolizumab as first-line treatment for cisplatin-ineligible advanced urothelial carcinoma (aUC) (Cohort 1) or progressing after platinum chemotherapy (Cohort 2). MVA-CV301 was given subcutaneously (SC) on Days 1 and 22 and FPV-CV301 SC from day 43 every 21 days for 4 doses, then tapered gradually over up to 2 years. Atezolizumab 1200 mg IV was given every 21 days. The primary endpoint was objective response rate (ORR). Overall, 43 evaluable patients received therapy: 19 in Cohort 1; 24 in Cohort 2; nine experienced ≥ Grade 3 therapy-related adverse events. In Cohort 1, one had partial response (PR) (ORR 5.3%, 90% CI 0.3, 22.6). In Cohort 2, 1 complete response and 1 PR were noted (ORR 8.3%, 90% CI 1.5, 24.0). The trial was halted for futility. Patients exhibiting benefit demonstrated T-cell response to CEA and MUC-1. The trial illustrates the challenges in the development of vaccines, which should be guided by robust preclinical data.

Salvage of Chronic Syndesmosis Instability: A Retrospective Review With Mid-Term Follow-Up.

Malreduced syndesmotic injuries lead to poor outcomes. No consensus exists regarding preferred surgical treatment. This study aims to assess clinical and radiographic outcomes in patients undergoing distal tibiofibular arthrodesis or stabilization. Retrospective review identified patients undergoing distal tibiofibular arthrodesis or stabilization between 2003 and 2019. Surgical factors, revision surgeries, and American Orthopedic Foot and Ankle Score ankle-hindfoot scores were collected. Radiographs were independently evaluated by 4 surgeons. Seventy patients were included. Mean American Orthopedic Foot and Ankle Score scores (n = 33) improved from 48 ± 16 preoperatively to 85 ± 14 (p < .001) at a median follow-up of 31.1 months. Mean Kellgren scores (n = 47) increased from 2.1 ± 1 to 2.5 ± 1 (p < .001) and the mean medial clear space decreased from 3.2 mm ± 0.8 mm to 2.8 mm ± 0.8 mm (p <.001) with no differences between the arthrodesis and stabilization groups. Zero patients progressed to arthroplasty or fusion. Patients demonstrated significant functional improvement after distal tibiofibular arthrodesis and stabilization. Progression of arthritis, while statistically significant, was not clinically significant.

Reverse coronal deformity: use of robotic total knee arthroplasty for identification and correction.

BACKGROUND: Despite continued advances in techniques and implant designs, a population of patients who are dissatisfied after total knee arthroplasty (TKA) remains. During robotic-assisted arthroplasty, real-time intraoperative assessment of patient knee alignment is performed. Here, we assess the prevalence of an under-appreciated deformity, reverse coronal deformity (RCD), and the benefits of utilizing robotic-assisted knee arthroplasty to help correct this dynamic deformity. METHODS: A retrospective study evaluating patients undergoing robotic-assisted cruciate-retaining TKA was performed. Intraoperative measurements were obtained using tibial and femoral arrays to assess coronal plane deformity at full extension and at 90° flexion. RCD was defined as ≥ 2° varus in knee extension that reversed to ≥ 2° valgus in flexion, or vice-versa. Coronal plane deformity was then reassessed after robotic-assisted bony resection and implant placement. RESULTS: Of 204 patients that underwent TKA, 16 patients (7.8%) were found to have RCD, with 14 patients (87.5%) transitioning from varus in extension to valgus in flexion. The average coronal deformity was 7.75°, with a maximum of 12°. These improved to an average coronal change of 0.93° post-TKA. Final medial and lateral gaps were all balanced to within 1° in extension and flexion. Another 34 patients (16.7%) had ≥ 5° change in coronal plane deformity from extension to flexion (average 6.39°), however, did not experience a reversal of their coronal deformity. Outcomes were assessed with KOOS Jr. scores postoperatively. CONCLUSION: Computer and robotic assistance were utilized to demonstrate the prevalence of RCD. We also demonstrated accurate identification and successfully balancing of RCD utilizing robotic-assisted TKA. An increased awareness of these dynamic deformities could aid surgeons in proper gap balancing even in the absence of navigation and robotic-assisted surgery.

Personality traits and stress perception as predictors of students' online engagement during the COVID-19 pandemic.

The COVID-19 pandemic coupled with increasing student numbers means online learning will remain a prevalent feature of the university experience, therefore it is vital that we understand how personality can influence student online engagement. The current study examined whether students' personality traits and stress perception predicted their online engagement with their studies during the COVID-19 pandemic. A sample of 301 first year psychology students completed the Big Five Inventory, Challenge and Hindrance Stress Scales, and the Online Student Engagement Scale, which measured students': engagement skills, emotional engagement, participation and performance. Results revealed that conscientiousness positively predicted all types of online engagement. Extraversion predicted participation and performance. Neuroticism predicted engagement skills, emotional engagement and performance, whilst agreeableness and openness to experience respectively predicted participation and emotional engagement. Additionally, stress perceived as a hindrance negatively predicted performance. These results reveal that students' personality traits and stress perception influence their online engagement and might enable educators to identify those who may require support in engaging with their studies.

Teaching Instrumental Analysis during the Pandemic: Application of Handheld CO2 Monitors to Explore COVID-19 Transmission Risks.

The COVID-19 pandemic has posed a challenge for maintaining an engaging learning environment while using remote laboratory formats. In this work, we describe a Student Choice Project (SCP) in an undergraduate instrumental analysis course that was adapted for remote learning without sacrificing research-based learning goals. We discuss the implementation and assessment of this SCP, selected student results, and student feedback. Students were provided handheld carbon dioxide monitors and charged with designing and implementing an investigation centered on COVID-19 airborne transmission. The real-time monitors provided experience with a new analytical tool that demanded considerations and analysis not common to other methods discussed in the course. Students were motivated by the ability to design their own projects and by the real-world implications of their findings. They performed well for all assessments, reported a positive experience, and recommended these monitors be added to the typical repertoire of instrumentation for the course.

Delayed debridement of open tibia fractures beyond 24 and 48 h does not appear to increase infection and reoperation risk.

PURPOSE: Surgical debridement is critical to the treatment of open tibia fractures, although the effects of delayed debridement have not been well-established. Other factors such as Gustilo-Anderson type, prompt initiation of antibiotics, and time to definitive closure may be more predictive of infection than time to surgery. We sought to determine the effect of a prolonged delay to surgical debridement with respect to infection and reoperation rates for open tibia fractures. METHODS: All open diaphyseal tibia fractures with > 12-week follow-up were evaluated. Patient demographics, Gustilo-Anderson type, and rates of deep infection and all-cause reoperation were recorded. Patients were divided into 3 groups based on time to surgery: early (< 24 h), delayed (24-48 h), and late (> 48 h). Univariate and multivariate analyses were performed to evaluate the relationship between time to surgery, fracture type, infection, and reoperation. RESULTS: In total, 96 open tibia fractures with average follow-up of 59.3 weeks and infection rate of 13.5% were included. Infection rates for the early, delayed, and late groups were 13.3%, 17.2%, and 9.1%, respectively (p = 0.70). Reoperation rates for the early, delayed, and late groups were 29.8%, 31.0%, and 22.7%, respectively (p = 0.80). The groups did not vary in proportion of Gustilo-Anderson fracture types; infection rates between Gustilo-Anderson types were similar (p = 0.57). Type IIIA-C fractures required more reoperations than other fracture types (p = 0.01). CONCLUSION: Delayed surgical debridement of open tibia fractures did not result in greater rates of infection or reoperation. Gustilo-Anderson classification was more predictive of reoperation, with Type IIIA-C injuries having a significantly higher reoperation rate.

Results of a multicenter, phase 2 study of nivolumab and ipilimumab for patients with advanced rare genitourinary malignancies.

BACKGROUND: In this multicenter, single-arm, multicohort, phase 2 trial, the efficacy of nivolumab and ipilimumab was evaluated in patients with advanced rare genitourinary cancers, including bladder and upper tract carcinoma of variant histology (BUTCVH), adrenal tumors, platinum-refractory germ cell tumors, penile carcinoma, and prostate cancer of variant histology (NCT03333616). METHODS: Patients with rare genitourinary malignancies and no prior immune checkpoint inhibitor exposure were enrolled. Patients received nivolumab at 3 mg/kg and ipilimumab at 1 mg/kg intravenously every 3 weeks for 4 doses, and this was followed by 480 mg of nivolumab intravenously every 4 weeks. The primary endpoint was the objective response rate (ORR) by the Response Evaluation Criteria in Solid Tumors (version 1.1). RESULTS: Fifty-five patients were enrolled at 6 institutions between April 2018 and July 2019 in 3 cohorts: BUTCVH (n = 19), adrenal tumors (n = 18), and other tumors (n = 18). The median follow-up was 9.9 months (range, 1 to 21 months). Twenty-eight patients (51%) received 4 doses of nivolumab and ipilimumab; 25 patients received nivolumab maintenance for a median of 4 cycles (range, 1-18 cycles). The ORR for the entire study was 16% (80% confidence interval, 10%-25%); the ORR in the BUTCVH cohort, including 2 complete responses, was 37%, and it was 6% in the other 2 cohorts. Twenty-two patients (40%) developed treatment-related grade 3 or higher toxicities; 24% (n = 13) required high-dose steroids (≥40 mg of prednisone or the equivalent). Grade 5 events occurred in 3 patients; 1 death was treatment related. CONCLUSIONS: Nivolumab and ipilimumab resulted in objective responses in a subset of patients with rare genitourinary malignancies, especially those with BUTCVH. An additional cohort exploring their activity in genitourinary tumors with neuroendocrine differentiation is ongoing. LAY SUMMARY: Patients with rare cancers are often excluded from studies and have limited treatment options. Fifty-five patients with rare tumors of the genitourinary system were enrolled from multiple sites and were treated with nivolumab and ipilimumab, a regimen used for kidney cancer. The regimen showed activity in some patients, particularly those with bladder or upper tract cancers of unusual or variant histology; 37% of those patients responded to therapy. Additional studies are ongoing to better determine who benefits the most from this combination.

National Trends Show Declining Use of Arthroscopic Subacromial Decompression Without Rotator Cuff Repair.

PURPOSE: The goal of this study was to investigate trends in the United States for arthroscopic subacromial decompression (aSAD) and open SAD (oSAD) with and without rotator cuff repair (RCR) between 2010 and 2018. METHODS: The PearlDiver Mariner claims database was queried using CPT codes for open and arthroscopic subacromial decompression and rotator cuff repair. Patient cohorts were developed for those undergoing aSAD or oSAD between 2010 and 2018, then segmented by whether RCR was performed simultaneously. Annual incidence was analyzed, as were associated diagnosis codes, and concomitant shoulder-associated procedures performed on the same day. RESULTS: The PearlDiver Mariner dataset from 2010 to 2018 included 186,932 patients that underwent aSAD, while 9,263 patients underwent oSAD. The total incidence of aSAD declined from 118.0 to 71.3 per 100,000 (39.6% decrease) (P < .001). This change was due primarily to a decreasing incidence of aSAD performed without RCR, which declined from 66.3 to 25.5 per 100,000 (61.5% decrease) (P < .001). During the same period, the incidence of aSAD combined with RCR remained relatively stable, from 51.7 to 45.8 per 100,000 (11.5% decrease) (P = .27). The overall incidence of oSAD declined from 7.1 to 2.2 per 100,000 (68.1% decrease) (P < .001). CONCLUSIONS: The overall rate of aSAD has declined in recent years, primarily due to a large decrease in the incidence of aSAD without RCR as an isolated treatment for rotator cuff disorders. CLINICAL RELEVANCE: Prior studies have demonstrated a rising incidence of SAD; however, high-level clinical evidence and clinical practice guidelines have challenged its efficacy. It is important for orthopaedic surgeons to understand evolving national trends in management among their peers.

Are Comorbidities Affecting Rotator Cuff Repair Outcomes? A Retrospective Review of Postoperative Costs and complications.

Our study examines the effect of comorbidities on rotator cuff repair (RCR) postoperative costs and complication rates. A retrospective review of patients receiving RCRs from 2008-2016 using the PearlDiver database was performed. We evaluated the effect of major comorbidities on postoperative costs and complications within one year of surgery. In total, 8,747 patients underwent RCR. Patients with no comorbidities had a 6-month and 12-month postoperative cost of $3,534 and $3,853, respectively. Patients with one comorbidity had 6-month postoperative costs ranging from $2,623 to $3,466 and 1-year postoperative costs ranging from $2,992 to $5,906. Patients with 3+ comorbidities receiving arthroscopic RCR had the highest complication rates at 1-, 3- and 6-month intervals (11.8%, 19.7% and 26.8%, respectively) compared to those with no comorbidities (8.1% [p = 0.139], 12.7% [p = 0.022] and 15.9% [p = 0.001], respectively). Patients with isolated comorbidities likely require similar healthcare utilization to those without, but patients with 3+ comorbidities risk greater complications and higher post-operative costs. (Journal of Surgical Orthopaedic Advances 30(1):024-029, 2021).

Stratifying Venous Thromboembolism Risk in Arthroplasty: Do High-Risk Patients Exist?

BACKGROUND: While there are many possible complications associated with total joint arthroplasty (TJA), venous thromboembolism (VTE) is both frequent and potentially severe. Despite this importance, there are inconsistent recommendations for prophylaxis based on patient risk factors. METHODS: A predictive model was constructed to compare low-molecular-weight heparin(LMWH) and aspirin (ASA) for prevention of VTE-associated complications following TJA.The model used risks from prior prophylaxis studies to estimate the risk of developing a symptomatic deep vein thrombosis, pulmonary embolism, thrombocytopenia, and operative or nonoperative site bleeding. We also evaluated the progression to 4 possible final health states: postphlebitis syndrome, intracranial hemorrhage, death, or baseline health. Within published ranges, we selected assumptions that were favorable to LMWH such that these analyses represent a best case scenario for LMWH or an alternative more aggressive low-molecular-weight heparin alternative (LMWHA). Events and outcomes were assigned quality-adjusted life-year (QALY) losses according to prior studies to determine the effect on patients' outcomes for ASA and LMWHA prophylaxis. RESULTS: Assessing VTE risk populations from 0.2% to 2% with life expectancies ranging from 5 to 40 years postoperatively, patients with a risk ratio less than 3.7 showed increased expected QALY with ASA compared to LMWHA. For patients with a baseline VTE risk of 1% and a 15 year life expectancy, a risk ratio of 13.4 was needed to identify patients that would benefit from LMWHA. With life expectancy increased to 30 years, the risk ratio needed to idetify these patients was 7.4. CONCLUSION: Patients undergoing TJA should receive ASA chemoprophylaxis in nearly all situations, unless the patient has a significantly increased VTE risk compared to the baseline population and a long life expectancy.

Phospholamban deficiency does not alter skeletal muscle SERCA pumping efficiency or predispose mice to diet-induced obesity.

The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) pump is a major contributor to skeletal muscle Ca2+ homeostasis and metabolic rate. SERCA activity can become adaptively uncoupled by its regulator sarcolipin (SLN) to increase the energy demand of Ca2+ pumping, preventing excessive obesity and glucose intolerance in mice. Several other SERCA regulators bear structural and functional resemblance to SLN, including phospholamban (PLN). Here, we sought to examine whether endogenous levels of skeletal muscle PLN control SERCA Ca2+ pumping efficiency and whole body metabolism. Using PLN-null mice ( Pln-/-), we found that soleus (SOL) muscle's SERCA pumping efficiency (measured as an apparent coupling ratio: Ca2+ uptake/ATP hydrolysis) was unaffected by PLN. Expression of Ca2+-handling proteins within the SOL, including SLN, were comparable between Pln-/- and wild-type (WT) littermates, as were fiber-type characteristics. Not surprisingly then, Pln-/- mice developed a similar degree of diet-induced obesity and glucose intolerance as WT controls when given a "Western" high-fat diet. Lack of an excessively obesogenic phenotype of Pln-/- could not be explained by compensation from skeletal muscle SLN or brown adipose tissue uncoupling protein-1 content. In agreement with several other reports, our study lends support to the notion that PLN serves a functionally distinct role from that of SLN in skeletal muscle physiology.

Wettability-Independent Droplet Transport by Bendotaxis.

We demonstrate "bendotaxis," a novel mechanism for droplet self-transport at small scales. A combination of bending and capillarity in a thin channel causes a pressure gradient that, in turn, results in the spontaneous movement of a liquid droplet. Surprisingly, the direction of this motion is always the same, regardless of the wettability of the channel. We use a combination of experiments at a macroscopic scale and a simple mathematical model to study this motion, focusing in particular on the timescale associated with the motion. We suggest that bendotaxis may be a useful means of transporting droplets in technological applications, e.g., in developing self-cleaning surfaces, and discuss the implications of our results for such applications.

Sulfur isotope analysis of microcrystalline iron sulfides using secondary ion mass spectrometry imaging: Extracting local paleo-environmental information from modern and ancient sediments.

RATIONALE: Sulfur isotope ratio measurements of bulk sulfide from marine sediments have often been used to reconstruct environmental conditions associated with their formation. In situ microscale spot analyses by secondary ion mass spectrometry (SIMS) and laser ablation multiple-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) have been utilized for the same purpose. However, these techniques are often not suitable for studying small (≤10 µm) grains or for detecting intra-grain variability. METHODS: Here, we present a method for the physical extraction (using lithium polytungstate heavy liquid) and subsequent sulfur isotope analysis (using SIMS; CAMECA IMS 7f-GEO) of microcrystalline iron sulfides. SIMS sulfur isotope ratio measurements were made via Cs+ bombardment of raster squares with sides of 20-130 µm, using an electron multiplier (EM) detector to collect counts of 32 S- and 34 S- for each pixel (128 × 128 pixel grids) for between 20 and 960 cycles. RESULTS: The extraction procedure did not discernibly alter pyrite grain-size distributions. The apparent inter-grain variability in 34 S/32 S in 1-4 µm-sized pyrite and marcasite fragments from isotopically homogeneous hydrothermal crystals was ~ ±2‰ (1σ), comparable with the standard error of the mean for individual measurements (≤ ±2‰, 1σ). In contrast, grain-specific 34 S/32 S ratios in modern and ancient sedimentary pyrites and marcasites can have inter- and intra-grain variability >60‰. The distributions of intra-sample isotopic variability are consistent with bulk 34 S/32 S values. CONCLUSIONS: SIMS analyses of isolated iron sulfide grains yielded distributions that are isotopically representative of bulk 34 S/32 S values. Populations of iron sulfide grains from sedimentary samples record the evolution of the S-isotopic composition of pore water sulfide in their S-isotopic compositions. These data allow past local environmental conditions to be inferred.

Hopanoids as functional analogues of cholesterol in bacterial membranes.

The functionality of cellular membranes relies on the molecular order imparted by lipids. In eukaryotes, sterols such as cholesterol modulate membrane order, yet they are not typically found in prokaryotes. The structurally similar bacterial hopanoids exhibit similar ordering properties as sterols in vitro, but their exact physiological role in living bacteria is relatively uncharted. We present evidence that hopanoids interact with glycolipids in bacterial outer membranes to form a highly ordered bilayer in a manner analogous to the interaction of sterols with sphingolipids in eukaryotic plasma membranes. Furthermore, multidrug transport is impaired in a hopanoid-deficient mutant of the gram-negative Methylobacterium extorquens, which introduces a link between membrane order and an energy-dependent, membrane-associated function in prokaryotes. Thus, we reveal a convergence in the architecture of bacterial and eukaryotic membranes and implicate the biosynthetic pathways of hopanoids and other order-modulating lipids as potential targets to fight pathogenic multidrug resistance.

Preoperative Interventions and Charges in the 2-Year Period Before Unicompartmental Knee Arthroplasty: What Happens Before Surgery.

BACKGROUND: This study investigated preoperative interventions and their costs in the 2-year period before a patient undergoing a unicompartmental knee arthroplasty (UKA). METHODS: A retrospective cohort analysis of patients undergoing UKA between 2009 and 2011 was conducted using the PearlDiver Patient Record Database to track inpatient and outpatient billing records. RESULTS: One thousand eight hundred forty-one patients from Medicare and 4704 patients from United Healthcare underwent UKA between 2009 and 2011. In the 2 years before UKA, the per patient average charge was $3919.96 for Medicare patients and $5219.14 for United Healthcare patients, with 21.7% of Medicare-associated charges and 28.2% of United Healthcare-associated charges occurring within 3 months of surgery. In the 2-year period before surgery, 65.5% of Medicare patients and 53.6% of United Healthcare patients received an intra-articular injection, with 29.1% (Medicare) and 46.0% (United Healthcare) of these injections occurring within 3 months of surgery. In addition, 15.1% of Medicare patients and 20.7% of United Healthcare patients underwent an arthroscopy, with between 32.4% and 43.8% of these occurring in the final 6 months before UKA. CONCLUSION: Preoperative interventions (ie, imaging, procedures, physical therapy, and injections) occur at a high frequency in close proximity to UKA resulting in substantial costs. The development of algorithms to guide management of these patients is critical in reducing costs before UKA.

Thiosulfate oxidation by Thiomicrospira thermophila: metabolic flexibility in response to ambient geochemistry.

Previous studies of the stoichiometry of thiosulfate oxidation by colorless sulfur bacteria have failed to demonstrate mass balance of sulfur, indicating that unidentified oxidized products must be present. Here the reaction stoichiometry and kinetics under variable pH conditions during the growth of Thiomicrospira thermophila strain EPR85, isolated from diffuse hydrothermal fluids at the East Pacific Rise, is presented. At pH 8.0, thiosulfate was stoichiometrically converted to sulfate. At lower pH, the products of thiosulfate oxidation were extracellular elemental sulfur and sulfate. We were able to replicate previous experiments and identify the missing sulfur as tetrathionate, consistent with previous reports of the activity of thiosulfate dehydrogenase. Tetrathionate was formed under slightly acidic conditions. Genomic DNA from T. thermophila strain EPR85 contains genes homologous to those in the Sox pathway (soxAXYZBCDL), as well as rhodanese and thiosulfate dehydrogenase. No other sulfur oxidizing bacteria containing sox(CD)2 genes have been reported to produce extracellular elemental sulfur. If the apparent modified Sox pathway we observed in T. thermophila is present in marine Thiobacillus and Thiomicrospira species, production of extracellular elemental sulfur may be biogeochemically important in marine sulfur cycling.

Influence of sulfate reduction rates on the Phanerozoic sulfur isotope record.

Phanerozoic levels of atmospheric oxygen relate to the burial histories of organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading to concomitant uncertainties in O2 budgets. Here we present experiments linking the magnitude of fractionations of the multiple sulfur isotopes to the rate of microbial sulfate reduction. The data demonstrate that such fractionations are controlled by the availability of electron donor (organic matter), rather than by the concentration of electron acceptor (sulfate), an environmental constraint that varies among sedimentary burial environments. By coupling these results with a sediment biogeochemical model of pyrite burial, we find a strong relationship between observed sulfur isotope fractionations over the last 200 Ma and the areal extent of shallow seafloor environments. We interpret this as a global dependency of the rate of microbial sulfate reduction on the availability of organic-rich sea-floor settings. However, fractionation during the early/mid-Paleozoic fails to correlate with shelf area. We suggest that this decoupling reflects a shallower paleoredox boundary, primarily confined to the water column in the early Phanerozoic. The transition between these two states begins during the Carboniferous and concludes approximately around the Triassic-Jurassic boundary, indicating a prolonged response to a Carboniferous rise in O2. Together, these results lay the foundation for decoupling changes in sulfate reduction rates from the global average record of pyrite burial, highlighting how the local nature of sedimentary processes affects global records. This distinction greatly refines our understanding of the S cycle and its relationship to the history of atmospheric oxygen.

Preoperative Interventions and Charges Before Total Knee Arthroplasty.

BACKGROUND: The cost effectiveness of total knee arthroplasty (TKA) has been well established, but little data exist regarding preoperative interventions and their costs. The purpose of this study was to examine preoperative interventions and their associated charges within the 2-year period before TKA. METHODS: A retrospective cohort analysis of patients undergoing TKA between 2007 and 2011 was conducted using the PearlDiver Patient Record Database. Patients' inpatient and outpatient billing records were tracked over the 2-year period before receiving a TKA. RESULTS: A total of 35,596 patients from Medicare and 47,064 from United Healthcare underwent TKA from 2009 to 2011. In the 2-year period before TKA, the per patient average charge was $3545.82 for Medicare and $3281.57 for United Healthcare. In the 2-year period before TKA, 21.4% (Medicare) and 23.3% (United Healthcare) of all patients received a magnetic resonance imaging, with between 31.9% (Medicare) and 45.6% (United Healthcare) of these occurring within 3 months of surgery (P < .05). During this same period, 49.4% (Medicare) and 63.2% (United Healthcare) of all patients received an intra-articular injection, with between 29.4% (Medicare) and 44.8% (United Healthcare) of these occurring within 3 months of surgery (P < .05). CONCLUSION: Interventions and costs before TKA occur largely within 6 months preoperatively, with a substantial portion occurring within 3 months. These interventions may not be clinically or cost effective for certain patients, such as those with moderate-to-severe osteoarthritis. Foregoing these interventions and opting to perform TKA earlier may reduce costs and prevent unnecessary tests and procedures.