Chronic N-acetyl cysteine treatment does not improve respiratory system performance in the mdx mouse model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is characterised by respiratory muscle injury, inflammation, fibrosis and weakness, ultimately culminating in respiratory failure. The dystrophin-deficient mouse model of DMD (mdx) shows evidence of respiratory muscle remodelling and dysfunction contributing to impaired respiratory system performance. The antioxidant N-acetylcysteine (NAC) has been shown to exert anti-inflammatory and anti-fibrotic effects leading to improved respiratory muscle performance in a range of animal models of muscle dysfunction, including mdx mice, following short-term administration (2 weeks). We sought to build on previous work by exploring the effects of chronic NAC administration (3 months) on respiratory system performance in mdx mice. One-month-old male mdx mice were randomised to receive normal drinking water (n = 30) or 1% NAC in the drinking water (n = 30) for 3 months. At 4 months of age, we assessed breathing in conscious mice by plethysmography followed by ex vivo assessment of diaphragm force-generating capacity. Additionally, diaphragm histology was performed. In separate studies, in anaesthetised mice, respiratory electromyogram (EMG) activity and inspiratory pressure across a range of behaviours were determined, including assessment of peak inspiratory pressure-generating capacity. NAC treatment did not affect force-generating capacity of the mdx diaphragm. Collagen content and immune cell infiltration were unchanged in mdx + NAC compared with mdx diaphragms. Additionally, there was no significant effect of NAC on breathing, ventilatory responsiveness, inspiratory EMG activity or inspiratory pressure across the range of behaviours from basal conditions to peak system performance. We conclude that chronic NAC treatment has no apparent beneficial effects on respiratory system performance in the mdx mouse model of DMD suggesting limited potential of NAC treatment alone for human DMD.

Readability of Online Information for Parents Concerning Paediatric In-Toeing: An Analysis of the Most Popular Online Public Sources.

Background Parents often access online resources to educate themselves on their child's condition. In-toeing, also referred to as pigeon toeing, is a common paediatric condition that has a variety of causes and is often a cause of concern for parents. With the increasing usage of the internet, parents of children with this condition may look to the web for answers. However, to be understood by the average adult, online health information must be written at an elementary school reading level. We hypothesised that currently available online resources regarding in-toeing would score poorly on objective measures of readability and understandability. Methods Patient education materials were identified via three commonly used online search engines (Google.com, Yahoo.com, and Bing.com). The terms "intoeing" and "pigeon toeing" were used for the search. From the top 50 search results, websites were included if directed at educating patients and their families regarding in-toeing. News articles, non-text material (video), industry websites, and articles not related to in-toeing were excluded. The readability was analysed using a specialised website www.readable.com to produce the following three scores: Gunning Fog Index (GFI), Flesch Reading Ease (FRE), and Flesch-Kincaid Grade (FKG). Understandability was calculated using the 19-point Patient Education Materials Assessment Tool (PEMAT). Results After removing duplicates, 84 unique websites were assessed for inclusion. A total of 48 websites and articles (57.14%) met the inclusion criteria. Of note, 23 articles out of 84 (27.38%) were excluded as they were intended for healthcare professionals. The means for the FRE, FKG, and GFI were 57.92 (±12.26), 7.92 (±1.91), and 9.35 (±2.36), respectively. Less than half of online resources had an FRE score at or higher than the recommended reading level for the general population. Mean understandability scores were 69.63% (±11.55%), with only 45.83% of articles being greater than the 70% requirement of adequate understandability. Conclusion Overall, online in-toeing educational materials scored poorly with respect to readability and understandability. Given the popularity of online resources in patient education, we should seek to improve this situation. Articles that are easier to read are thus more accessible to the general public and will aid in the shared decision-making process. Improved patient and parent satisfaction and overall standard of care can be expected.

Syndesmotic injury with ankle fracture: A systematic review of screw vs dynamic fixation.

Cortical screw fixation across the tibiofibular joint is the mainstay of treatment for syndesmotic injury. Dynamic fixation devices have been developed offering similar advantages to screw fixation in terms of reduction and stability of the syndesmosis. Dynamic fixation may also facilitate a more physiological movement between the tibiofibular joint and thus incur less morbidity. Patient's rehabilitation potential is enhanced and reduces the need for hardware removal. Our systematic review aims to analyse the relevant current literature and compare screw fixation to dynamic fixation in the treatment of syndesmotic injury associated with acute ankle fractures. A literature search was performed on Pubmed and Ovid Medline to find scientific papers relating to syndesmotic fixation in acute ankle fractures. Papers were screened and included dependent on predetermined criteria. Risk of bias was assessed after screening full papers by two independent reviewers. Tables and analysis were made using Microsoft excel. A total of 8 papers with 673 patients were included. We found no functional difference between screw fixation or dynamic fixation groups at final follow-up. Three papers showed statistically significant lower rates of reoperation in the dynamic fixation group. Dynamic fixation may offer lower post operative complications and reoperation rates. Therefore, dynamic fixation may be a beneficial alternative treatment compared to traditionally used syndesmotic screws.

Characterizing variations in ambient PM2.5 concentrations at the U.S. Embassy in Dhaka, Bangladesh using observations and the CMAQ modeling system.

We analyze hourly PM2.5 (particles with an aerodynamic diameter of ≤ 2.5 µm) concentrations measured at the U.S. Embassy in Dhaka over the 2016 - 2021 time period and find that concentrations are seasonally dependent with the highest occurring in winter and the lowest in monsoon seasons. Mean winter PM2.5 concentrations reached ~165-175 µg/m3 while monsoon concentrations remained ~30-35 µg/m3. Annual mean PM2.5 concentration reached ~5-6 times greater than the Bangladesh annual PM2.5 standard of 15 µg/m3. The number of days exceeding the daily PM2.5 standard of 65 µg/m3 in a year approached nearly 50%. Daily-mean PM2.5 concentrations remained elevated (>65 µg/m3) for more than 80 consecutive days. Night-time concentrations were greater than daytime concentrations. The comparison of results obtained from the Community Multiscale Air Quality (CMAQ) model simulations over the Northern Hemisphere using 108-km horizontal grids with observed data suggests that the model can reproduce the seasonal variation of observed data but underpredicts observed PM2.5 in winter months with a normalized mean bias of 13-32%. In the model, organic aerosol is the largest component of PM2.5, of which secondary organic aerosol plays a dominant role. Transboundary pollution has a large impact on the PM2.5 concentration in Dhaka, with an annual mean contribution of ~40 µg/m3.

Photochemical model assessment of single source NO2 and O3 plumes using field study data.

Single source contribution to ambient O3 and PM2.5 has been estimated with photochemical grid models to support policy demonstrations for National Ambient Air Quality Standards, regional haze, and permit related programs. Limited field data exists to evaluate model representation of the spatial extent and chemical composition of plumes emitted by specific facilities. New tropospheric column measurements of NO2 and in-plume chemical measurements downwind of specific facilities allows for photochemical model evaluation of downwind plume extent, grid resolution impacts on plume concentration gradients, and source attribution methods. Here, photochemical models were applied with source sensitivity and source apportionment approaches to differentiate single source impacts on NO2 and O3 and compare with field study measurements. Source sensitivity approaches (e.g., brute-force difference method and decoupled direct method (DDM)) captured the spatial extent of NO2 plumes downwind of three facilities and the transition of near-source O3 titration to downwind production. Source apportionment approaches showed variability in terms of attributing the spatial extent of NO2 plumes and downwind O3 production. Each of the Community Multiscale Air Quality (CMAQ) source apportionment options predicted large O3 contribution from a large industrial facility in the flight transects nearest the facility when measurements and source sensitivity approaches suggest titration was outpacing production. In general, CMAQ DDM tends to attribute more O3 to boundary inflow and less to within-domain NOX and VOC sources compared to CMAQ source apportionment. The photochemical modeling system was able to capture single source plumes using 1 to 12 km grid resolution with best representation of plume extent and magnitude at the finer resolutions. When modeled at 1 to 12 km grid resolution, primary and secondary PM2.5 impacts were highest at the source location and decrease as distance increases downwind. The use of coarser grid resolution for single source attribution resulted in predicted impacts highest near the source but lower peak source specific concentrations compared to finer grid resolution simulations because impacts were spread out over a larger area.

A single centre experience of prosthetic joint infection outcomes with outpatient parenteral antimicrobial therapy.

Objectives: Prosthetic joint infection (PJI) is a serious complication following arthroplasties. This study assessed the clinical outcomes, readmission rates and financial impact of PJIs treated with outpatient parenteral antimicrobial therapy (OPAT). Methods: The study used prospectively collected data from the OPAT patient database at a tertiary care Irish hospital for PJI cases managed between 2015 and 2020. Data was analyzed using IBM-SPSS. Results: Forty-one patients with PJIs were managed via OPAT over five years, with median age of 71.6 years. Median duration of OPAT was 32 days. Hospital readmission occurred in 34% of cases. Reasons for readmission included progression of infection in 64.3%, unplanned reoperation in 21.4% and planned admission for joint revision in 14.3%. Type 2 Diabetes Mellitus (T2DM) was found to have a statistically significant association with unplanned readmission (OR 8.5, CI 95% 1.1-67.6; p < 0.01). OPAT saved a mean of 27.49 hospital-bed days per patient. 1,127 bed days were saved in total, estimating a total savings of 963,585 euros and median savings of 26,505 euros. Conclusions: The readmission rate observed was comparable to international data. Most readmissions were related to primary infections rather than due to OPAT-specific complications. Our main findings were that patients with PJIs can be safely managed via OPAT, and the finding of association between T2DM and increased risk of readmission.

Strength-Based Rehabilitation on Clinical Outcomes in Patients Postpartial Meniscectomy: A Systematic Review and Meta-analysis.

OBJECTIVE: The aim of the study is to determine the effect of strength-based rehabilitation programs on patients who underwent partial meniscectomy procedures. DESIGN: Three databases MEDLINE, PubMed, and Embase were searched from inception to May 9, 2022. Data on functional outcomes such as quadriceps and hamstring strengths, as well as patient-reported outcomes such as Knee Osteoarthritis and Outcome Score and visual analog scale were recorded. RESULTS: A total of nine studies comprising 417 patients were included in this review. There were no significant differences in quadriceps or hamstring strength measures between preinterventation and postintervention for both groups. Knee Osteoarthritis and Outcome Scores significantly increased from preintervention and postintervention in both control and exercise groups. Visual analog scale scores changed from 5.0 to 1.4 cm in the exercise arm and 3.1 to 1.9 cm in the control arm. CONCLUSIONS: Strength-based exercise programs for patients postpartial meniscectomy did not result in significantly different improvements in quadriceps or hamstring strength compared with control programs. However, strength-based exercise programs resulted in significantly higher Knee Osteoarthritis and Outcome Scores and a greater decrease in visual analog scale scores. Further studies, specifically well-designed systematic randomized controlled trials, are necessary to elucidate the specifics behind what type of exercises to use in addition to load progression and frequency of training.

Does previous fragility fracture impact upon mortality in a hip fracture cohort? a retrospective study.

BACKGROUND: Fragility fractures are described as fractures resulting from low-energy trauma and are considered diagnostic of reduced bone mineral density or osteoporosis. They often present as hip fractures with hip fractures remaining a common but devastating injury among older patients. Many factors influence a patient's risk of hip fracture and their subsequent risk of death. AIM: In this study, we examined if previous fragility fracture impacts upon mortality after hip fracture. METHODS: This was a retrospective single-center cohort study of patients included in the Irish Hip Fracture registry over a 5-year time period. Epidemiological data including gender, age, type of fracture, type of surgery, bone protection medication, American Society of Anesthetics (ASA) grade, and post-fracture outcomes including death at 30 days and death at 1 year were recorded. The presence or absence of a previous fragility fracture was examined to explore if a previous fragility fracture was an independent predictor of mortality. RESULTS: There were 964 patients included, and 290 of whom had sustained a previous fragility fracture; 289 patients were males and 675 females, 33 patients had died in the 30 days following their surgery, and 180 patients had died within 1 year. We found statistically significant results for gender and age but not for previous fragility fracture influencing mortality (p value 0.230). CONCLUSION: We found that previous fragility fracture does not impact upon mortality in a hip fracture cohort. However, gender and age did impact upon mortality in this study.

Impact of cancer cachexia on respiratory muscle function and the therapeutic potential of exercise.

Cancer cachexia is defined as a multi-factorial syndrome characterised by an ongoing loss of skeletal muscle mass and progressive functional impairment, estimated to affect 50-80% of patients and responsible for 20% of cancer deaths. Elevations in the morbidity and mortality rates of cachectic cancer patients has been linked to respiratory failure due to atrophy and dysfunction of the ventilatory muscles. Despite this, there is a distinct scarcity of research investigating the structural and functional condition of the respiratory musculature in cancer, with the majority of studies exclusively focusing on limb muscle. Treatment strategies are largely ineffective in mitigating the cachectic state. It is now widely accepted that an efficacious intervention will likely combine elements of pharmacology, nutrition and exercise. However, of these approaches, exercise has received comparatively little attention. Therefore, it is unlikely to be implemented optimally, whether in isolation or combination. In consideration of these limitations, the current review describes the mechanistic basis of cancer cachexia and subsequently explores the available respiratory- and exercise-focused literature within this context. The molecular basis of cachexia is thoroughly reviewed. The pivotal role of inflammatory mediators is described. Unravelling the mechanisms of exercise-induced support of muscle via antioxidant and anti-inflammatory effects in addition to promoting efficient energy metabolism via increased mitochondrial biogenesis, mitochondrial function and muscle glucose uptake provide avenues for interventional studies. Currently available pre-clinical mouse models including novel transgenic animals provide a platform for the development of multi-modal therapeutic strategies to protect respiratory muscles in people with cancer.

Review of the Role of Intraoperative Neurophysiological Monitoring in Spinal Surgery With a Focus on the True and False Positives and a Clinical Correlation.

BACKGROUND: Spinal surgery is a technically challenging endeavor with potentially devastating complications. Intraoperative neurophysiological monitoring (IONM) is a method of preventing and identifying damage to the spinal cord. OBJECTIVE: The aim of our study was to examine the clinical utility of IONM in spinal surgeries performed at our institution and what effect, if any, subsequent interventions had on postoperative patient outcomes. METHODS: This is a retrospective cohort study of 169 patients who underwent spinal surgery with IONM at 2 institutions between 2013 and 2018. Signal changes detected were recorded as well as the surgeon's response to these changes. Neurological status was recorded using a standard neurological examination and characterized as per the McCormick Neurological Scale. Patients were followed up for 12 months after surgery. RESULTS: A total of 169 spinal surgery cases with concurrent use of spinal cord monitoring were carried out in our institution between 2013 and 2018. The youngest patient was 14 years old, and the oldest was 92 years old (mean, 51.9 ± 19.6 years). There were 100 female patients and 69 male patients. Most patients (n = 124) had no signal changes. Signal changes were observed in 26.6% of the cases (n = 45). Most of these signal changes were rectified through repositioning of the patient (n = 24). The other 21 patients saw no improvement in their signals before the end of their procedures; however, these 21 patients had no postoperative deficits (grade I). This brought the false positive rate to 38% (21/55); the false negative rate was 1.8% (3/169). CONCLUSION: This study showed similar outcomes in patients whether IONM signals were recovered or not. The false positive and false negative rates were high. Our study helps to raise awareness about IONM's strengths and weaknesses to inform future clinical practice. We recommend prioritizing clinical judgment in spinal surgery cases and using IONM with caution.

The Optimisation of Cooking Parameters for Spirt Whiskey Production from Native Irish Wheat: A Response Surface Method Approach.

Barley and maize have dominated the Irish whiskey sector, but in recent years, alternative grains have started to gain traction. Ireland has a high average wheat yield, producing grain that is high in starch but low in protein, offering the potential for use in distillation. To successfully utilise Irish-grown wheat in distillation, cultivars that are suitable to the Irish climate and give high yields of alcohol need to be identified. This necessitates the development of a rapid screening test for grain alcohol yield. This study examined the optimal temperature, time period, α-amylase dose rate, and calcium concentration to be used in the cooking of wheat grain to maximise alcohol yields. It was determined that lower cooking temperatures are more successful in achieving higher alcohol yields, and it was confirmed that temperature is a key variable in the cooking process. By optimising all parameters, alcohol yields of 458 LA/tonne were obtained, demonstrating that the optimum parameters can be successfully used for both hard and soft endoderm wheat produced in Ireland as well as for different varieties. This indicates potential for producing higher alcohol yields using Irish-grown wheat in Irish distilleries.

Response Surface Methods to Optimise Milling Parameters for Spirit Alcohol Production from Irish Wheat Grain.

To standardise research activity and determine alcohol yield from native Irish hard wheat grain, a benchmark approach that reflects Irish industry norms is required. The goal of this study was to optimise milling parameters, grain particle size, and grain to liquid ratio towards developing a standard process. Hard wheat (Triticum avestivum cv. Costello) was used in this study. Experiments utilised a response surface method approach. When both 30 and 35 g of flour were used at a particle size of 0.2 mm, alcohol yield was >350 L of alcohol per tonne of grain (LA/tonne), but with a particle size of 0.65 and 1.1 mm, alcohol yield decreased to between 250 and 300 LA/tonne. It was noted that, during response surface study, >300 LA/tonne was achieved when grain amounts were >25 g, at a particle size of 0.2 mm; therefore, a follow-up experiment was conducted to determine whether there was a significant difference in grain amounts ranging from 25 to 35 g. During this experiment, no significant difference in alcohol yield was observed between 30 and 35 g of grain. Because there were no significant differences, the ideal milling parameters for alcohol yield were determined to be 30 g of flour with a particle size of 0.2 mm, achieving 389.5 LA/tonne. This study concludes that hard wheat can successfully be used for alcohol production, achieving >380 LA/tonne, when a milling size of 0.2 mm and more than 30 g of grain are used, and as such presents an opportunity for its increased use in Irish distilleries.

The 50 most influential papers pertaining to the Ilizarov method: A bibliometric analysis.

The Ilizarov method has become a widely recognised surgical technique. A bibliometric analysis of the 50 most-cited publications relating to the Ilizarov method was carried out. Cumulative number of citations was 4,918. Mean number of citations was 98. h-index was 50. Impact factor of these journals ranged from 0.5-5.082. Our study suggests that a highly cited and influential paper likely originated from an American journal with a high impact factor and was published in the 1990s/2000s. Our compilation of the 50 most influential papers on the Ilizarov method will prove invaluable to those in training and those involved in further advancing the technique.

Alleged recurrent traumatic shoulder dislocation in a young male patient - Diagnostic and management considerations.

A young male presented to a nearby hospital with a left shoulder dislocation after an alleged kickboxing injury. The patient reported worrying clinical findings including excruciating pain and absent sensation distally. Reduction was successful but his shoulder re-dislocated shortly after. His reported symptoms worsened and he was transferred to our institution. Imaging findings were not immediately concerning and he went to theatre the next day for an examination under anaesthetic. His shoulder was re-located easily and an immobiliser applied. Less than an hour later, the patient managed to re-dislocate his shoulder in recovery. He was subjected to another general anaesthetic and successful reduction. He absconded the following day after being declined multiple and increasing doses of opioid analgesia. He re-presented three weeks later with similar clinical findings but a different mechanism of injury. Further exploration of his collateral history revealed that he had been using a false identity. He had presented to all hospitals in our city within the previous 6 months. Once confronted, he did not return to these hospitals. He was also capable of self-relocating his shoulder. This case bore a striking resemblance to a case described by Warren in 2000 of a young lady with an apparently dislocated shoulder presenting to multiple city hospitals looking for analgesia and general anaesthetics. We wished to highlight the diagnostic and ethical challenges associated with these patients. They are vulnerable and so a high index of clinical suspicion is needed on the part of the surgeon to avoid unnecessary interventions. Effective communication between orthopaedic departments is a key recommendation from this case to mitigate risk of harm to these patients.

Readability and quality of online information for patients pertaining to revision knee arthroplasty: An objective analysis.

BACKGROUND: Modern patients use the internet more frequently for their health information. Our aim was to assess the quality and readability of online patient education materials relating to revision knee arthroplasty. We hypothesised that this information would be too difficult to read for the average patient and of a lesser quality than desired. METHOD: A search of the top 50 results on 3 search engines (Google, Bing, Yahoo) was completed (MeSH "revision knee arthroplasty", "revision knee replacement"). Readability of these websites was calculated using a specialised website, www.readable.com to produce 3 scores (Gunning-Fog (GF), Flesch Reading Ease (FRE), Flesch-Kincaid Grade (FKG). Quality was assessed using the Journal of American Medical Association (JAMA) benchmark criteria and the Health On the Net (HON) code toolbar extension. RESULTS: 89 unique websites were identified. Mean FRE was 44.01 ± 11.05. The mean GF was 12.01 ± 2.94. The mean FKG level was 10.06 ± 1.95. As per the FRE score, no webpage was pitched at or below a sixth grade reading level. The GF index identified only 3 websites (3.4%) at 6th grade reading level. As per FKG score, most webpages (n = 58, 65.2%) found themselves in the 10th grade reading level and above. Four websites (4.5%) displayed a HONcode certificate. However, all had expired. Most websites (n = 34, 38.2%) didn't meet any of the JAMA criteria. CONCLUSION: The reading level of these materials is too high for the average patient and of a low quality. Given what we know about levels of health literacy and their relationship with patient outcomes, it is vital that we address these deficiencies promptly.

A multi-site review of second hip fractures across 6 Dublin teaching hospitals.

INTRODUCTION: Fragility hip fractures are common and costly. Secondary fracture prevention is a treatment goal following hip fracture; however, the number of those that proceed to fracture their contralateral hip in Ireland is unknown. There are plans to introduce a Fracture Liaison Service Database in Ireland which will aim to prevent secondary fractures. To establish a baseline figure for secondary hip fractures, the injury radiographs of 1284 patients from 6 teaching hospitals over a 1-year period were reviewed. METHODS: Irish Hip Fracture Datasheets and corresponding injury radiographs were reviewed locally for all hip fractures within each respective teaching hospital for a 1-year period (2019). RESULTS: A total of 8.7% of all fragility hip fractures across the 6 hospitals were secondary hip fractures (range 4.9-11.5%). 46% occurred within years 1 to 3 following index hip fracture. Forty-eight per cent of patients were started on bone protection medications following their second hip fracture. DISCUSSION/CONCLUSION: Approximately 1 in 11 hip fractures treated across the 6 teaching hospitals assessed in 2019 was a patient's second hip fracture. We advocate for the widespread availability of Fracture Liaison Services to patients throughout Ireland to assist secondary fracture prevention.

Quadriceps Tendon Anterior Cruciate Ligament Reconstruction: A Systematic Review of Postoperative Rehabilitation and Complication Profiles.

PURPOSE: The purposes of this study are to explore current elements for postoperative rehabilitation protocol after quadriceps tendon-anterior cruciate ligament reconstruction (QT-ACLR), outline general timelines for progression of those elements, and explore their associated complication rates and profiles. METHODS: In accordance with PRISMA guidelines, 5 online databases (EMBASE, MEDLINE, CINAHL, Cochrane, and PubMed) were searched and screened in duplicate using predetermined criteria for studies on the aforementioned patient population. Descriptive statistics are presented. RESULTS: A total of 56 studies were included, with 31 studies using quadriceps tendon with bone block (B-QT) and 26 studies using all-soft tissue quadriceps tendon (S-QT). The majority of studies permitted full weightbearing and range of motion (ROM) within the first 12 postoperative weeks, and motion-controlled braces within 6 weeks. Isometric exercises were initiated within 1 week after surgery, closed-chain exercises within 12 weeks, and open-chain and sports-specific exercises within 36 weeks. Complication profiles were similar between graft types and included graft failure (1.2%-1.6%), cyclops syndrome (0.4%-0.7%), and persistent stiffness (0.9%). CONCLUSIONS: Current postoperative rehabilitation strategies in ACLR with QT offer a complication profile comparable to those reported with other graft types. Based on the included rehabilitation regimen, these protocols should focus on early ROM, specifically on achieving full extension, alongside isometric quadriceps strengthening. Progression to closed- and open-chain exercises should follow in a progressive manner, similar to existing protocols in ACLR. Adjuncts such as motion-controlled bracing and continuous passive motion machines may be used if graft protection is prioritized. This review highlights the need for comparison of defined protocols against one another in the setting of QT-ACLR. LEVEL OF EVIDENCE: IV, systematic review of Level I-IV studies.

Secondary organic aerosol association with cardiorespiratory disease mortality in the United States.

Fine particle pollution, PM2.5, is associated with increased risk of death from cardiorespiratory diseases. A multidecadal shift in the United States (U.S.) PM2.5 composition towards organic aerosol as well as advances in predictive algorithms for secondary organic aerosol (SOA) allows for novel examinations of the role of PM2.5 components on mortality. Here we show SOA is strongly associated with county-level cardiorespiratory death rates in the U.S. independent of the total PM2.5 mass association with the largest associations located in the southeastern U.S. Compared to PM2.5, county-level variability in SOA across the U.S. is associated with 3.5× greater per capita county-level cardiorespiratory mortality. On a per mass basis, SOA is associated with a 6.5× higher rate of mortality than PM2.5, and biogenic and anthropogenic carbon sources both play a role in the overall SOA association with mortality. Our results suggest reducing the health impacts of PM2.5 requires consideration of SOA.

Great tits who remember more accurately have difficulty forgetting, but variation is not driven by environmental harshness.

The causes of individual variation in memory are poorly understood in wild animals. Harsh environments with sparse or rapidly changing food resources are hypothesized to favour more accurate spatial memory to allow animals to return to previously visited patches when current patches are depleted. A potential cost of more accurate spatial memory is proactive interference, where accurate memories block the formation of new memories. This relationship between spatial memory, proactive interference, and harsh environments has only been studied in scatter-hoarding animals. We compare spatial memory accuracy and proactive interference performance of non-scatter hoarding great tits (Parus major) from high and low elevations where harshness increases with elevation. In contrast to studies of scatter-hoarders, we did not find a significant difference between high and low elevation birds in their spatial memory accuracy or proactive interference performance. Using a variance partitioning approach, we report the first among-individual trade-off between spatial memory and proactive interference, uncovering variation in memory at the individual level where selection may act. Although we have no evidence of harsh habitats affecting spatial memory, our results suggest that if elevation produced differences in spatial memory between elevations, we could see concurrent changes in how quickly birds can forget.