A Single-Institution Analysis of Targeted Colorectal Surgery Enhanced Recovery Pathway Strategies That Decrease Readmissions.

BACKGROUND: Decreasing readmissions is an important quality improvement strategy. Targeted interventions that effectively decrease readmissions have not been fully investigated and standardized. OBJECTIVE: The purpose of this study was to assess the effectiveness of interventions designed to decrease readmissions after colorectal surgery. DESIGN: This was a retrospective comparison of patients before and after the implementation of interventions. SETTING: This study was conducted at a single institution dedicated enhanced recovery pathway colorectal surgery service. PATIENTS: The study group received quality review interventions that were designed to decrease readmissions: preadmission class upgrades, a mobile phone app, a pharmacist-led pain management strategy, and an early postdischarge clinic. The control group was composed of enhanced recovery patients before the interventions. Propensity score weighting was used to adjust patient characteristics and predictors for imbalances. MAIN OUTCOME MEASURE: The primary outcome was 30-day readmissions. Secondary outcomes included emergency department visits. RESULTS: There were 1052 patients in the preintervention group and 668 patients in the postintervention group. After propensity score weighting, the postintervention cohort had a significantly lower readmission rate (9.98% vs 17.82%, p < 0.001) and emergency department visit rate (14.58% vs 23.15%, p < 0.001) than the preintervention group, and surgical site infection type I/II was significantly decreased as a readmission diagnosis (9.46% vs 2.43%, p = 0.043). Median time to readmission was 6 (interquartile 3-11) days in the preintervention group and 8 (3-17) days in the postintervention group (p = 0.21). Ileus, acute kidney injury, and surgical site infection type III were common reasons for readmissions and emergency department visits. LIMITATIONS: A single-institution study may not be generalizable. CONCLUSION: Readmission bundles composed of targeted interventions are associated with a decrease in readmissions and emergency department visits after enhanced recovery colorectal surgery. Bundle composition may be institution dependent. Further study and refinement of bundle components are required as next-step quality metric improvements. See Video Abstract at http://links.lww.com/DCR/B849. ANLISIS EN UNA SOLA INSTITUCIN DE LAS CIRUGAS COLORECTALES CON VAS DE RECUPERACIN DIRIGIDA AUMENTADA QUE REDUCEN LOS REINGRESOS: ANTECEDENTES:La reducción de los reingresos es una importante estrategia de mejora de la calidad. Las intervenciones dirigidas que reducen eficazmente los reingresos no se han investigado ni estandarizado por completo.OBJETIVO:El propósito de este estudio fue evaluar la efectividad de las intervenciones diseñadas para disminuir los reingresos después de la cirugía colorrectal.DISEÑO:Comparación retrospectiva de pacientes antes y después de la implementación de las intervenciones.ESCENARIO:Una sola institución dedicada al Servicio de cirugía colorrectal con vías de recuperación dirigida aumentadaPACIENTES:El grupo de estudio recibió intervenciones de revisión de calidad que fueron diseñadas para disminuir los reingresos: actualizaciones de clases previas a la admisión, una aplicación para teléfono móvil, una estrategia de manejo del dolor dirigida por farmacéuticos y alta temprana de la clínica. El grupo de control estaba compuesto por pacientes con recuperación mejorada antes de las intervenciones. Se utilizó la ponderación del puntaje de propensión para ajustar las características del paciente y los predictores de los desequilibrios.PARÁMETRO DE RESULTADO PRINCIPAL:El resultado primario fueron los reingresos a los 30 días. Los resultados secundarios incluyeron visitas al servicio de urgencias.RESULTADOS:Hubo 1052 pacientes en el grupo de preintervención y 668 pacientes en el grupo de posintervención. Después de la ponderación del puntaje de propensión, la cohorte posterior a la intervención tuvo una tasa de reingreso significativamente menor (9,98% frente a 17,82%, p <0,001) y una tasa de visitas al servicio de urgencias (14,58% frente a 23,15%, p <0,001) que el grupo de preintervención y la infección del sitio quirúrgico tipo I / II se redujo significativamente como diagnóstico de reingreso (9,46% frente a 2,43%, p = 0,043). La mediana de tiempo hasta la readmisión fue de 6 [IQR 3, 11] días en el grupo de preintervención y de 8 [3, 17] días en el grupo de posintervención (p = 0,21). El íleo, la lesión renal aguda y la infección del sitio quirúrgico tipo III fueron motivos frecuentes de reingresos y visitas al servicio de urgencias.LIMITACIONES:El estudio de una sola institución puede no ser generalizable.CONCLUSIÓNES:Los paquetes de readmisión compuestos por intervenciones dirigidas se asocian con una disminución en las readmisiones y las visitas al departamento de emergencias después de una cirugía colorrectal con vías de recuperación dirigida aumentada. La composición del paquete puede depender de la institución. Se requieren más estudios y refinamientos de los componentes del paquete como siguiente paso de mejora de la métrica de calidad. Consulte Video Resumen en http://links.lww.com/DCR/B849. (Traducción-Dr Yolanda Colorado).

Source and Chemistry of Hydroxymethanesulfonate (HMS) in Fairbanks, Alaska.

Fairbanks, Alaska, is a subarctic city with fine particle (PM2.5) concentrations that exceed air quality regulations in winter due to weak dispersion caused by strong atmospheric inversions, local emissions, and the unique chemistry occurring under the cold and dark conditions. Here, we report on observations from the winters of 2020 and 2021, motivated by our pilot study that showed exceptionally high concentrations of fine particle hydroxymethanesulfonate (HMS) or related sulfur(IV) species (e.g., sulfite and bisulfite). We deployed online particle-into-liquid sampler-ion chromatography (PILS-IC) in conjunction with a suite of instruments to determine HMS precursors (HCHO, SO2) and aerosol composition in general, with the goal to characterize the sources and sinks of HMS in wintertime Fairbanks. PM2.5 HMS comprised a significant fraction of PM2.5 sulfur (26-41%) and overall PM2.5 mass concentration of 2.8-6.8% during pollution episodes, substantially higher than what has been observed in other regions, likely due to the exceptionally low temperatures. HMS peaked in January, with lower concentrations in December and February, resulting from changes in precursors and meteorological conditions. Strong correlations with inorganic sulfate and organic mass during pollution events suggest that HMS is linked to processes responsible for poor air quality episodes. These findings demonstrate unique aspects of air pollution formation in cold and humid atmospheres.

The impact of obesity and morbid obesity on urgent/emergency colorectal resections: a regional database analysis.

BACKGROUND: The obesity rate is projected to reach 50% by 2030. Obesity may be modifiable prior to elective colorectal surgery, but there is no opportunity for weight loss when patients present for urgent/emergency operations. The impact of obesity focused on urgent/emergent colorectal operations has not been fully characterized. The study aim was to determine outcomes of obese patients who undergo urgent/emergency colorectal surgery and differences when compared with elective outcomes. METHODS: This is a retrospective cohort study of 30-day outcomes for normal (BMI 18.5-25), obese (BMI 30-39.9), and morbidly obese (BMI > 40) patients in the Michigan Surgical Quality Collaborative between 1/1/2009 and 12/31/2018. Propensity score weighting was used to derive adjusted rates for overall morbidity, mortality, and specific complications. Primary outcome was postoperative complications (any morbidity). RESULTS: The study included 5268 urgent/emergency and 10,414 elective colorectal surgery patients. Postoperative complications were significantly more common in morbidly obese and obese than the normal BMI group for both urgent/emergency (morbidly obese 42.76% vs 33.75%, p = 0.003; obese 36.46% vs 33.75%, p = 0.043) and elective (morbidly obese 18.17% vs 13.36%, p = 0.004; obese 15.45% vs 13.36%, p = 0.011) operations. Surgical site infections are were significantly more common in morbidly obese and obese BMI groups as compared to normal BMI for both urgent/emergency and elective cases. Mortality was significantly higher in the morbidly obese (14.93% vs 11.44%, p = 0.013) but not obese BMI groups as compared to the normal BMI group for urgent/emergency cases. Mortality for all groups undergoing elective operations was < 1% and with no significant differences. CONCLUSIONS: Morbid obesity and obesity are associated with complications that are largely driven by surgical site infections after both urgent/emergency and elective colorectal surgery. Obesity is a risk factor difficult to modify prior to urgent/emergency surgery. Managing complications related to obesity after colorectal surgery will be a continued challenge with projected increasing obesity rates.

Efficacy and utilization of intravascular ultrasound in office-based lower extremity endovascular interventions for peripheral arterial disease.

OBJECTIVES: Intravascular ultrasound (IVUS) is a uniquely objective but underutilized imaging modality in the interventional treatment of peripheral arterial disease treatment. IVUS has been shown to improve device size selection and diagnose occult pathology difficult to see with routine angiography. We hypothesize that the use of IVUS in lower extremity endovascular intervention improves accuracy in stent and balloon size selection and minimizes contrast use. METHODS: This is a retrospective case series performed at a single-institution outpatient center by two vascular surgeons from July 2016 through July 2017. We identified 94 total IVUS-assisted procedures. We collected data regarding demographics, balloon and stent size, IVUS-determined vessel diameter, pre-procedure and post-procedure ABI values, and contrast used during the procedure. An independent core laboratory was further utilized to characterize all IVUS and angiographic size vessel measurements. RESULTS: For the 94 lower extremity IVUS-assisted interventions, the average patient age was 70±9 years old, with an average contrast use of 37.1 mL of Omnipaque 300. There was substantial improvement in pre- and post-procedure ABI (0.7±0.23 to 0.94±0.21). On analysis of average intraluminal IVUS vessel diameter to balloon angioplasty used, we had a correlation in size of 0.96±0.16 in our series. Additionally, in eight instances IVUS allowed for identification of a flow-limiting dissection with subsequent stenting. CONCLUSIONS: Routine use of IVUS offers a powerful diagnostic paradigm that has the potential to significantly decrease contrast use and to improve objectivity in choosing appropriate vascular tools to maximize intra-procedural efficacy. The discovery of adverse findings not initially noticed on angiography further reinforces the value of IVUS utilization.

Fenestrated repair improves perioperative outcomes but lacks a hospital volume association for complex abdominal aortic aneurysms.

BACKGROUND: Complex abdominal aortic aneurysms (AAAs) have traditionally been treated with an open surgical repair (OSR). During the past decade, fenestrated endovascular aneurysm repair (FEVAR) has emerged as a viable option. Hospital procedural volume to outcome relationship for OSR of complex AAAs has been well established, but the impact of procedural volume on FEVAR outcomes remains undefined. This study investigated the outcomes of OSR and FEVAR for the treatment of complex AAAs and examined the hospital volume-outcome relationship for these procedures. METHODS: A retrospective review of a statewide vascular surgery registry was queried for all patients between 2012 and 2018 who underwent elective repair of a juxtarenal/pararenal AAA with FEVAR or OSR. The primary outcomes were 30-day mortality, myocardial infarction, and new dialysis. Secondary end points included postoperative pneumonia, renal dysfunction (creatine concentration increase of >2 mg/dL from preoperative baseline), major bleeding, early procedural complications, length of stay, and need for reintervention. To evaluate procedural volume-outcomes relationship, hospitals were stratified into low- and high-volume aortic centers based on a FEVAR annual procedural volume. To account for baseline differences, we calculated propensity scores and employed inverse probability of treatment weighting in comparing outcomes between treatment groups. RESULTS: A total of 589 patients underwent FEVAR (n = 186) or OSR (n = 403) for a complex AAA. After adjustment, OSR was associated with higher rates of 30-day mortality (10.7% vs 2.9%; P < .001) and need for dialysis (11.3% vs 1.8; P < .001). Postoperative pneumonia (6.8% vs 0.3%; P < .001) and need for transfusion (39.4% vs 10.4%; P < .001) were also significantly higher in the OSR cohort. The median length of stay for OSR and FEVAR was 9 days and 3 days, respectively. For those who underwent FEVAR, endoleaks were present in 12.1% of patients at 30 days and 6.1% of patients at 1 year, with the majority being type II. With a median follow-up period of 331 days (229-378 days), 1% of FEVAR patients required a secondary procedure, and there were no FEVAR conversions to an open aortic repair. Hospitals were divided into low- and high-volume aortic centers based on their annual FEVAR volume of complex AAAs. After adjustment, hospital FEVAR procedural volume was not associated with 30-day mortality or myocardial infarction. CONCLUSIONS: FEVAR was associated with lower perioperative morbidity and mortality compared with OSR for the management of complex AAAs. Procedural FEVAR volume outcome analysis suggests limited differences in 30-day morbidity, although long-term durability warrants further research.

Postoperative Pain After Enhanced Recovery Pathway Robotic Colon and Rectal Surgery: Does Specimen Extraction Site Matter?

BACKGROUND: The current opioid crisis has motivated surgeons to critically evaluate ways to balance postoperative pain while decreasing opioid use and thereby reducing opioids available for community diversion. The longest incision for robotic colorectal surgery is the specimen extraction site incision. Intracorporeal techniques allow specimen extraction to be at any location. OBJECTIVE: This study was designed to determine whether the Pfannenstiel location is associated with less pain and opioid use than other abdominal wall specimen extraction sites. DESIGN: This was a retrospective cohort study. SETTINGS: The study was conducted with a prospectively maintained colorectal surgery database (July 2018 through October 2019). PATIENTS: Patients with enhanced recovery robotic colorectal resections with specimen extraction were included. MAIN OUTCOME MEASURES: Propensity score weighting was used to derive adjusted rates for numeric pain scores, inpatient opioid use, opioids prescribed at discharge, opioid refills after discharge, and other related outcomes. For comparing outcomes between groups, p values were calculated using weighted χ2, Fisher exact, and t tests. RESULTS: There were 137 cases (70.9%) with Pfannenstiel extraction site incisions and 56 (29.0%) at other locations (7 midline, 49 off-midline). There was no significant difference in transversus abdominis plane blocks and epidural analgesia use between groups. Numeric pain scores, overall benefit of analgesia scores, inpatient postoperative opioid use, opioids prescribed at discharge and taken after discharge, and opioid refills were not significantly different between groups. Nonopioid pain analgesics (acetaminophen, nonsteroidal anti-inflammatory drugs, and gabapentin) prescribed at discharge were significantly less in the Pfannenstiel group (90.19% vs 98.45%; p = 0.006). Postoperative complications and readmissions were not different between groups. LIMITATIONS: This study was conducted at a single institution. CONCLUSIONS: The Pfannenstiel incision as the specimen extraction site choice in minimally invasive surgery is associated with similar postoperative pain and opioid use as extraction sites in other locations for patients having robotic colorectal resections. Specimen extraction sites may be chosen based on patient factors other than pain and opioid use. See Video Abstract at http://links.lww.com/DCR/B495. DOLOR POSTOPERATORIO DESPUS DE VAS DE RECUPERACIN MEJORADA EN CIRUGA ROBTICA DE COLON Y RECTO IMPORTA EL LUGAR DE EXTRACCIN DE LA MUESTRA: ANTECEDENTES:La actual crisis de opioides ha motivado a los cirujanos a evaluar críticamente, formas para equilibrar el dolor postoperatorio, disminuyendo el uso de opioides y por lo tanto, disminuyendo opioides disponibles para el desvío comunitario. La incisión más amplia en cirugía colorrectal robótica, es la incisión del sitio de extracción de la muestra. Las técnicas intracorpóreas permiten que la extracción de la muestra se realice en cualquier sitio.OBJETIVO:El estudio fue diseñado para determinar si la ubicación del Pfannenstiel está asociada con menos dolor y uso de opioides, a otros sitios de extracción de la muestra en la pared abdominal.DISEÑO:Estudio de cohorte retrospectivo.AJUSTES:Estudio de base de datos de cirugía colorrectal mantenida prospectivamente (7/2018 a 10/2019).PACIENTES:Se incluyeron resecciones robóticas colorrectales con recuperación mejorada y extracción de muestras.PRINCIPALES MEDIDAS DE RESULTADO:Se utilizó la ponderación del puntaje de propensión para derivar las tasas ajustadas para los puntajes numéricos de dolor, uso de opioides en pacientes hospitalizados, opioides recetados al alta, recarga de opioides después del alta y otros resultados relacionados. Para comparar los resultados entre los grupos, los valores p se calcularon utilizando chi-cuadrado ponderado, exacto de Fisher y pruebas t.RESULTADOS:Hubo 137 (70,9%) casos con incisiones en el sitio de extracción de Pfannenstiel y 56 (29,0%) en otras localizaciones (7 en la línea media, 49 fuera de la línea media). No hubo diferencias significativas en los bloqueos del plano transverso del abdomen y el uso de analgesia epidural entre los grupos. Las puntuaciones numéricas de dolor, puntuaciones de beneficio general de la analgesia, uso postoperatorio de opioides en pacientes hospitalizados, opioides recetados al alta y tomados después del alta, y las recargas de opioides, no fueron significativamente diferentes entre los grupos. Los analgésicos no opioides (acetaminofén, antiinflamatorios no esteroideos, gabapentina) prescritos al alta, fueron significativamente menores en el grupo de Pfannenstiel (90,19% frente a 98,45%, p = 0,006). Las complicaciones postoperatorias y los reingresos, no fueron diferentes entre los grupos.LIMITACIONES:Una sola institución.CONCLUSIÓN:La incisión de Pfannenstiel como sitio de extracción de la muestra en cirugía mínimamente invasiva, se asocia con dolor postoperatorio y uso de opioides similar, a otros sitios de extracción en pacientes sometidos a resecciones robóticas colorrectales. Sitios de extracción de la muestra, pueden elegirse en función de factores del paciente distintos al dolor y uso de opioides. Consulte Video Resumen en http://links.lww.com/DCR/B495.).

Forest density intensifies the importance of snowpack to growth in water-limited pine forests.

Warming climate and resulting declines in seasonal snowpack have been associated with drought stress and tree mortality in seasonally snow-covered watersheds worldwide. Meanwhile, increasing forest density has further exacerbated drought stress due to intensified tree-tree competition. Using a uniquely detailed data set of population-level forest growth (n = 2,495 sampled trees), we examined how inter-annual variability in growth relates to snow volume across a range of forest densities (e.g., competitive environments) in sites spanning a broad aridity gradient across the United States. Forest growth was positively related to snowpack in water-limited forests located at low latitude, and this relationship was intensified by forest density. However, forest growth was negatively related to snowpack in a higher latitude more energy-limited forest, and this relationship did not interact with forest density. Future reductions in snowpack may have contrasting consequences, as growth may respond positively in energy-limited forests and negatively in water-limited forests; however, these declines may be mitigated by reducing stand density through forest thinning.

Anomalous insertion of anterior and posterior horns of medial meniscus. Case report.

BACKGROUND: Anatomical variations of the attachment of medial meniscus are a common finding. However, anomalies of the posterior horn are extremely rare. Only two cases of posterior root anomaly have been described prior to the routine use of arthroscopy for evaluation and treatment of meniscal pathology. In this report, we present an anomaly of both the anterior and posterior roots of the medial meniscus that posed both a diagnostic and therapeutic dilemma. CASE PRESENTATION: The patient is young male soccer player who is currently 16 years of age and began having the atraumatic onset of pain and symptoms that limited performance starting at age 14 and was referred for failure of response to nonoperative treatment. Diagnostic arthroscopy revealed the presence of an anteromedial meniscofemoral ligament whereas the posterior root showed no bony attachment. The radiographic and arthroscopic findings are described. The clinical decision was made after to proceed with observation, reassurance, and gradual return to full activity with physiotherapy guidance. DISCUSSION AND CONCLUSION: The absence of injury, the mild complaints reported by the patient, his age, skeletal immaturity, and remaining growth led us to adopt a conservative approach to treating this anatomic variant and currently the patient is able to participate fully in sports without symptoms or restrictions.

Recurrence of Acute Right Colon Diverticulitis Following Nonoperative Management: A Systematic Review and Meta-analysis.

BACKGROUND: There are currently no guidelines on the management of right colon diverticulitis. Treatment options have been extrapolated from the management of left-sided diverticulitis. Gaining knowledge of the risk and morbidity of diverticulitis recurrence is integral to weighing the benefit of elective surgery for right-sided diverticulitis. OBJECTIVE: The purpose of this study was to summarize the recurrence rate and the morbidity of recurrence of Hinchey classification I/II, right-sided diverticulitis following nonoperative management. DATA SOURCES: PubMed, EMBASE, and Cochrane Database of Collected Reviews were searched up to June 2019. STUDY SELECTION: Observational cohort studies evaluating outcomes following nonoperative management were reviewed. No randomized controlled trials were available. INTERVENTIONS: Intravenous antibiotics with or without percutaneous drainage of associated abscess were administered. MAIN OUTCOME MEASURES: The primary outcomes measured were the recurrence rate and morbidity associated with recurrence. Two independent investigators extracted data. The rates of recurrence were pooled by using a random-effects model. RESULTS: There were 1584 adult participants from a total of 11 studies (9 retrospective cohort and 2 prospective cohort studies) included in the analysis. Over a median follow-up period of 34.2 months, the pooled recurrence rate was 12% (95% CI, 10%-15%). Twenty of 202 patients (9.9%) required urgent surgery at the time of first recurrence. There was no mortality. Subset analysis excluding 3 studies that included percutaneous drainage as a nonoperative treatment option did not change the recurrence rate (12% (95% CI, 9%-15%)) or heterogeneity. Funnel plot assessment revealed no publication bias. LIMITATIONS: There were no randomized controlled trials available. The statistical heterogeneity was moderate (I = 46%). CONCLUSIONS: Nonoperative management of Hinchey I/II right-sided diverticulitis is safe and feasible. The recurrence rate is relatively low, and complications that require urgent operation are uncommon. PROSPERO: CRD42019131673.

Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale.

The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses. We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common-garden datasets, respectively. The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin. We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.

Liposomal Bupivacaine Transversus Abdominis Plane Block Versus Epidural Analgesia in a Colon and Rectal Surgery Enhanced Recovery Pathway: A Randomized Clinical Trial.

BACKGROUND: Multimodal pain management is an integral part of enhanced recovery pathways. The most effective pain management strategies have not been determined. OBJECTIVE: The purpose of this study was to compare liposomal bupivacaine transversus abdominis plane block with epidural analgesia in patients undergoing colorectal surgery. DESIGN: This is a single-institution, open-label randomized (1:1) trial. SETTING: This study compared liposomal bupivacaine transversus abdominis plane block with epidural analgesia in patients undergoing elective open and minimally invasive colorectal surgery in an enhanced recovery pathway. PATIENTS: Two hundred were enrolled. Following randomization, allocation, and follow-up, there were 92 patients with transversus abdominis plane block and 87 patients with epidural analgesia available for analysis. INTERVENTIONS: The interventions comprised liposomal bupivacaine transversus abdominis plane block versus epidural analgesia. MAIN OUTCOME MEASURES: The primary outcomes measured were numeric pain scores and the overall benefit of analgesia scores. RESULTS: There were no significant differences in the Numeric Pain Scale and Overall Benefit of Analgesia Score between groups. Time trend analysis revealed that patients with transversus abdominis plane block had higher numeric pain scores on the day of surgery, but that the relationship was reversed later in the postoperative period. Opioid use was significantly less in the transversus abdominis plane block group (206.84 mg vs 98.29 mg, p < 0.001). There were no significant differences in time to GI recovery, hospital length of stay, and postoperative complications. Cost was considerably more for the epidural analgesia group. LIMITATIONS: This study was conducted at a single institution. CONCLUSIONS: This randomized trial shows that perioperative pain management with liposomal bupivacaine transversus abdominis plane block is as effective as epidural analgesia and is associated with less opioid use and less cost. These data and the more favorable risk profile suggest that liposomal bupivacaine transversus abdominis plane block is a viable multimodal perioperative pain management option for this patient population in an established enhanced recovery pathway. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov (NCT02591407). See Video Abstract at http://links.lww.com/DCR/A737.

Effect of the Urban Heat Island on Aerosol pH.

The urban heat island (UHI) is a widely observed phenomenon whereby urban environments have higher temperatures and different relative humidities than surrounding suburban and rural areas. Temperature (T) and relative humidity (RH) strongly affect the partitioning of semivolatile species found in the atmosphere, such as nitric acid, ammonia, and water. These species are inherently tied to aerosol pH, which is a key parameter driving some atmospheric chemical processes and environmental effects of aerosols. In this study, we characterized the effect of the UHI on aerosol pH in Baltimore, MD, and Chicago, IL. The T and RH differences that define the UHI lead to substantial differences in aerosol liquid water (ALW) content. The ALW differences produce urban aerosol pH that is systematically lower (more acidic) than rural aerosol pH for identical atmospheric composition. The UHI in Baltimore and Chicago are most intense during the summer and at night, with urban-rural aerosol pH differences in excess of 0.8 and 0.65 pH units, respectively. The UHI has been observed in cities of all sizes: the similarity of our results for cities with different climatologies and aerosol compositions suggests that these results have broad implications for chemistry occurring in and around urban atmospheres globally.

Testing the generality of above-ground biomass allometry across plant functional types at the continent scale.

Accurate ground-based estimation of the carbon stored in terrestrial ecosystems is critical to quantifying the global carbon budget. Allometric models provide cost-effective methods for biomass prediction. But do such models vary with ecoregion or plant functional type? We compiled 15 054 measurements of individual tree or shrub biomass from across Australia to examine the generality of allometric models for above-ground biomass prediction. This provided a robust case study because Australia includes ecoregions ranging from arid shrublands to tropical rainforests, and has a rich history of biomass research, particularly in planted forests. Regardless of ecoregion, for five broad categories of plant functional type (shrubs; multistemmed trees; trees of the genus Eucalyptus and closely related genera; other trees of high wood density; and other trees of low wood density), relationships between biomass and stem diameter were generic. Simple power-law models explained 84-95% of the variation in biomass, with little improvement in model performance when other plant variables (height, bole wood density), or site characteristics (climate, age, management) were included. Predictions of stand-based biomass from allometric models of varying levels of generalization (species-specific, plant functional type) were validated using whole-plot harvest data from 17 contrasting stands (range: 9-356 Mg ha(-1) ). Losses in efficiency of prediction were <1% if generalized models were used in place of species-specific models. Furthermore, application of generalized multispecies models did not introduce significant bias in biomass prediction in 92% of the 53 species tested. Further, overall efficiency of stand-level biomass prediction was 99%, with a mean absolute prediction error of only 13%. Hence, for cost-effective prediction of biomass across a wide range of stands, we recommend use of generic allometric models based on plant functional types. Development of new species-specific models is only warranted when gains in accuracy of stand-based predictions are relatively high (e.g. high-value monocultures).

Hydroxymethanesulfonate and Sulfur(IV) in Fairbanks Winter During the ALPACA Study.

Hydroxymethanesulfonate (HMS) in fine aerosol particles has been reported at significant concentrations along with sulfate under extreme cold conditions (-35 °C) in Fairbanks, Alaska, a high latitude city. HMS, a component of S(IV) and an adduct of formaldehyde and sulfur dioxide, forms in liquid water. Previous studies may have overestimated HMS concentrations by grouping it with other S(IV) species. In this work, we further investigate HMS and the speciation of S(IV) through the Alaskan Layered Pollution and Chemical Analysis (ALPACA) intensive study in Fairbanks. We developed a method utilizing hydrogen peroxide to isolate HMS and found that approximately 50% of S(IV) is HMS for total suspended particulates and 70% for PM2.5. The remaining unidentified S(IV) species are closely linked to HMS during cold polluted periods, showing strong increases in concentration relative to sulfate with decreasing temperature, a weak dependence on particle water, and similar particle size distributions, suggesting a common aqueous formation process. A portion of the unidentified S(IV) may originate from additional aldehyde-S(IV) adducts that are unstable in the water-based chemical analysis process, but further chemical characterization is needed. These results show the importance of organic S(IV) species in extreme cold environments that promote unique aqueous chemistry in supercooled liquid particles.

Assessing the Oxidative Potential of Outdoor PM2.5 in Wintertime Fairbanks, Alaska.

The oxidative potential (OP) of outdoor PM2.5 in wintertime Fairbanks, Alaska, is investigated and compared to those in wintertime Atlanta and Los Angeles. Approximately 40 filter samples collected in January-February 2022 at a Fairbanks residential site were analyzed for OP utilizing dithiothreitol-depletion (OPDTT) and hydroxyl-generation (OPOH) assays. The study-average PM2.5 mass concentration was 12.8 µg/m3, with a 1 h average maximum of 89.0 µg/m3. Regression analysis, correlations with source tracers, and contrast between cold and warmer events indicated that OPDTT was mainly sensitive to copper, elemental carbon, and organic aerosol from residential wood burning, and OPOH to iron and organic aerosol from vehicles. Despite low photochemically-driven oxidation rates, the water-soluble fraction of OPDTT was unusually high at 77%, mainly from wood burning emissions. In contrast to other locations, the Fairbanks average PM2.5 mass concentration was higher than Atlanta and Los Angeles, whereas OPDTT in Fairbanks and Atlanta were similar, and Los Angeles had the highest OPDTT and OPOH. Site differences were observed in OP when normalized by both the volume of air sampled and the particle mass concentration, corresponding to exposure and the intrinsic health-related properties of PM2.5, respectively. The sensitivity of OP assays to specific aerosol components and sources can provide insights beyond the PM2.5 mass concentration when assessing air quality.

Indoor-Outdoor Oxidative Potential of PM2.5 in Wintertime Fairbanks, Alaska: Impact of Air Infiltration and Indoor Activities.

The indoor air quality of a residential home during winter in Fairbanks, Alaska, was investigated and contrasted with outdoor levels. Twenty-four-hour average indoor and outdoor filter samples were collected from January 17 to February 25, 2022, in a residential area with high outdoor PM2.5 concentrations. The oxidative potential of PM2.5 was determined using the dithiothreitol-depletion assay (OPDTT). For the unoccupied house, the background indoor-to-outdoor (I/O) ratio of mass-normalized OP (OPmDTT), a measure of the intrinsic health-relevant properties of the aerosol, was less than 1 (0.53 ± 0.37), implying a loss of aerosol toxicity as air was transported indoors. This may result from transport and volatility losses driven by the large gradients in temperature (average outdoor temperature of -19°C/average indoor temperature of 21 °C) or relative humidity (average outdoor RH of 78%/average indoor RH of 11%), or both. Various indoor activities, including pellet stove use, simple cooking experiments, incense burning, and mixtures of these activities, were conducted. The experiments produced PM2.5 with a highly variable OPmDTT. PM2.5 from cooking emissions had the lowest OP values, while pellet stove PM2.5 had the highest. Correlations between volume-normalized OPDTT (OPvDTT), relevant to exposure, and indoor PM2.5 mass concentration during experiments were much lower compared to those in outdoor environments. This suggests that mass concentration alone can be a poor indicator of possible adverse effects of various indoor emissions. These findings highlight the importance of considering both the quantity of particles and sources (chemical composition), as health metrics for indoor air quality.

Overview of the Alaskan Layered Pollution and Chemical Analysis (ALPACA) Field Experiment.

The Alaskan Layered Pollution And Chemical Analysis (ALPACA) field experiment was a collaborative study designed to improve understanding of pollution sources and chemical processes during winter (cold climate and low-photochemical activity), to investigate indoor pollution, and to study dispersion of pollution as affected by frequent temperature inversions. A number of the research goals were motivated by questions raised by residents of Fairbanks, Alaska, where the study was held. This paper describes the measurement strategies and the conditions encountered during the January and February 2022 field experiment, and reports early examples of how the measurements addressed research goals, particularly those of interest to the residents. Outdoor air measurements showed high concentrations of particulate matter and pollutant gases including volatile organic carbon species. During pollution events, low winds and extremely stable atmospheric conditions trapped pollution below 73 m, an extremely shallow vertical scale. Tethered-balloon-based measurements intercepted plumes aloft, which were associated with power plant point sources through transport modeling. Because cold climate residents spend much of their time indoors, the study included an indoor air quality component, where measurements were made inside and outside a house to study infiltration and indoor sources. In the absence of indoor activities such as cooking and/or heating with a pellet stove, indoor particulate matter concentrations were lower than outdoors; however, cooking and pellet stove burns often caused higher indoor particulate matter concentrations than outdoors. The mass-normalized particulate matter oxidative potential, a health-relevant property measured here by the reactivity with dithiothreiol, of indoor particles varied by source, with cooking particles having less oxidative potential per mass than pellet stove particles.

Staphylococcus xylosus and Staphylococcus aureus as commensals and pathogens on murine skin.

Skin ulcers, skin dermatitis and skin infections are common phenomena in colonies of laboratory mice and are often found at increased prevalence in certain immunocompromised strains. While in many cases these skin conditions are mild, in other cases they can be severe and lead to animal morbidity. Furthermore, the presence of skin infections and ulcerations can complicate the interpretation of experimental protocols, including those examining immune cell activation. Bacterial species in the genus Staphylococcus are the most common pathogens recovered from skin lesions in mice. In particular, Staphylococcus aureus and Staphylococcus xylosus have both been implicated as pathogens on murine skin. Staphylococcus aureus is a well-known pathogen of human skin, but S. xylosus skin infections in humans have not been described, indicating that there is a species-specific difference in the ability of S. xylosus to serve as a skin pathogen. The aim of this review is to summarize studies that link S. aureus and S. xylosus to skin infections of mice and to describe factors involved in their adherence to tissue and their virulence. We discuss potential differences in mouse and human skin that might underlie the ability of S. xylosus to act as a pathogen on murine skin, but not human skin. Finally, we also describe mouse mutants that have shown increased susceptibility to skin infections with staphylococcal bacteria. These mutants point to pathways that are important in the control of commensal staphylococcal bacteria. The information here may be useful to researchers who are working with mouse strains that are prone to skin infections with staphylococcal bacteria.

Semimembranosus Tendon Findings in Acute Anterior Cruciate Ligament Tears: MRI Evaluation and Associated Lesions.

BACKGROUND: The semimembranosus (SM) tendon acts as a secondary dynamic stabilizer of the knee. It restrains external rotation and anterior translation of the medial compartment. Its role in the mechanism of injury during anterior cruciate ligament (ACL) rupture is unknown. HYPOTHESIS: The bone bruise (BB) often detected at the posteromedial tibia in association with acute ACL tear may be related to the traction force from the SM tendon insertion. Magnetic resonance imaging (MRI) alterations can be detectable at the direct arm of the SM tendon in association with acute ACL injury. STUDY DESIGN: Cross-sectional study: Level of evidence, 3. METHODS: In the first study phase, 36 noninjured patients underwent knee MRI. The anatomic appearance of the SM tendon was evaluated. An imaging score for evaluating the SM tendon was developed for the purpose of the study. The intensity (in the axial or sagittal plane), morphology, and thickness of the distal SM tendon was evaluated and scored (4 total points). In the second study phase, 52 patients undergoing acute ACL reconstruction were included. Preoperative MRI was examined and scored, with documentation of BB at the posteromedial tibial plateau. Finally, arthroscopic diagnosis of a ramp lesion was confirmed. Logistic regression analysis was carried out for correlation between an altered MRI scoring system and the presence of BB at the posteromedial tibial plateau, the presence of a ramp lesion, or both. RESULTS: Interrater agreement of 100% was obtained in the noninjured cohort (ie, no alteration found in any patient). The score validation in the cohort of patients with acute ACL injury showed a Cohen κ of 0.78 (interrater agreement, 82.7%). The direct arm of the SM tendon was altered in 35 of 52 patients (67.3%). A ramp lesion of the medial meniscus was arthroscopically detected in 21 patients (40.4%). The presence of BB at the posteromedial tibial plateau was detected in 33 patients (63.5%) and at the posterior medial femoral condyle in 1 (1.9%). Correlation analysis showed a significant association of a pathologic SM score with the presence of BB at the posteromedial tibial plateau (odds ratio = 2.7; P = .001). Conversely, no correlation was observed between the pathologic score and the presence of a ramp lesion (odds ratio = 0.88; P = .578). CONCLUSION: The prevalence of pathologic findings in the direct arm of the SM tendon insertion was high in the acutely injured cohort with ACL rupture and is correlated with the presence of BB at the posteromedial tibial plateau. The main hypothesis formulated for the study was confirmed.