Barriers to Eye Care for Adults in the United States and Solutions for It: A Literature Review.

Vision loss and blindness is a significant public health concern that has had a profound impact on various communities in the United States. Both anticipated and unforeseen barriers have been linked to the rising rates of vision loss and blindness in the country. Extensive research has identified numerous barriers that put many Americans at a disadvantage when trying to seek high-quality eye care services. Not only do the barriers to eye care services create problems for eye health, but also create a poor quality of life. Therefore, understanding and identifying barriers to eye healthcare services is incredibly important. In addition to understanding and identifying barriers, it is also important to identify solutions to the problems created by these barriers. A systematic review of articles characterizing the barriers to eye care was completed which resulted in the identification of the major barriers that affect Americans. The review of previous research was also used to identify available solutions for problems associated with the barriers to eye care services. The major barriers identified were cost, insurance, transport and accessibility, eye health care literacy, and communication. Because of the identification of the major barriers, solutions were also identified. Health education and increased vision screenings were found to be the most used forms of solutions by healthcare professionals promoting good eye health. Telemedicine has also been cited as a possible solution to the growing problem of visual impairment and blindness within the American population.

Plate fixation optimization for distal femoral fractures with segmental bone loss: Defining the preferred screw distribution using finite element analysis.

OBJECTIVES: Distal femur fractures can exhibit extensive comminution, and open fractures may result in bone loss. These injuries are under high mechanical demands when stabilized with a lateral locked plate (LLP), and are at risk of non-union or implant failure. This study investigates the optimal LLP screw configuration for distal femur fractures with a large metadiaphyseal gap of 5 cm. METHODS: A finite element (FE) model, validated against experimentally measured strains and displacement, evaluated pull-out forces and stress concentration on typical implants under clinical conditions corresponding with the 10 % point during the stance phase of the gait cycle. RESULTS: Maximum stress was up to 83 % less when the ratio (Cp) between the proximal screw-distribution-length and the distance of the first screw to the fracture was less than 0.2; maximum pull-out force was 99 % less when this ratio was higher than 0.4. CONCLUSIONS: Screw configuration based on either normal or osteopenic bone quality plays an important role in determining the risk of construct failure for a major (50 mm) distal femoral metadiaphyseal segmental defect. This study provides valuable information when planning definitive fixation for distal femur fractures with extensive comminution or segmental bone defects, to mitigate the risk of implant failure and subsequent nonunion.

Safety and usability of proning pillows in intensive care: A scoping review.

OBJECTIVES: Proning is an established technique for the care of intubated patients with severe respiratory failure. Positioning devices used to support the head and body of patients placed in the prone position are often associated with the formation of pressure injuries. Despite robust literature on the prevention and monitoring of pressure injuries, little is described about the role of proning pillows on pressure injuries. The objective of this review is to understand the extent of evidence pertaining to the safety and usability of different types of proning pillows in the intensive care setting. REVIEW METHOD: A scoping review of the literature was completed using predefined search terms in three databases and identified 296 articles. An additional 26 were included from reference lists. Twenty studies are included in the analysis; most were published in the past 3 years, with >50% in surgical settings. DATA SOURCES: Three databases were searched: PubMed, Scopus, and EMBASE. REVIEW METHODS: The review followed the PRISMA Extension for Scoping Reviews, and data were reviewed using Covidence. RESULTS: The most prevalent proning pillow is a standard, noncontoured foam head positioner. It is responsible for the majority of facial pressure injuries in all settings of care. Memory foam pillows and helmet-based systems offer improved surface pressure distribution, although their usability in the intensive care setting remains poorly studied. Inflatable air-cell-based devices present an alternative, but the lack of supporting research and the costs may explain their poor uptake. Several articles proposed the use of pressure sensor systems to evaluate devices. We propose a set of ergonomic parametres to consider when choosing or designing a positioning device for proned patients. CONCLUSION: The evidence pertaining to the safety and usability of proning pillows in the intensive care setting is scarce, which provides opportunities for future research to improve the efficacy in the prevention of pressure injuries and the user experience.

Restoration of glenoid joint line: a three-dimensional analysis of scapular landmarks.

Background: Restoration of the glenoid joint line in shoulder arthroplasty is important for implant positioning and function. Medialization of the glenohumeral joint line due to glenoid bone loss is commonly encountered in primary and revision of shoulder arthroplasty albeit the direction and location of bone loss varies with different pathology. Three-Dimensional (3D) planning software has assisted in preoperative planning of complex glenoid deformities. However, limited literature is available defining a reliable 3D method to evaluate the glenoid joint line preoperatively. Aims: The purpose of this study is to identify a set of reliable scapular landmarks to be used as reference points to measure the premorbid glenoid joint line using 3D segmented models of healthy scapulae. Methods: Bilateral computed tomography scans from 79 patients eligible for primary stabilization procedures were retrospectively selected from our institutional surgical database (mean age 35 ± 10 years, 58 males and 21 females). 3D models of the contralateral healthy scapulae were created via computed tomography scan segmentation using Mimics 24.0 software (Materialise, Leuven, Belgium). Anatomical landmarks were identified using 3-Matic 16.0 software (Materialise, Leuven, Belgium). The distance between identified landmarks and a sagittal plane created on the deepest point of the glenoid was recorded for each scapula and reliability of each landmark was assessed. Inter- and intra-observer reliabilities were also evaluated using intraclass correlation coefficients (ICCs). Results: Four landmarks showed statistically significant results: the scapular notch (SN), the centroid of the coracoid (CC), a point on the most medial border of the scapula in line with the scapular spine (TS), and the most lateral point of the acromion (AL). The mean (± standard deviation) joint line measured from the SN, CC, TS and AL were 28.36 ± 2.97 mm, 11.66 ± 2.07 mm, 107.52 ± 8.1 mm, and 29.72 ± 4.46 mm, respectively. Inter-observer reliability analysis for SN, TS, and AL showed excellent agreement with ICC values of 0.966, 0.997, and 0.944, respectively, and moderate agreement for CC with ICC of 0.728. Conclusion: The results from this study assist in estimating joint line medialization preoperatively and in planning its subsequent restoration. A set of reliable landmarks can be used as references to estimate the premorbid glenoid joint line preoperatively.

Prebiotic Synthesis of N-Formylaminonitriles and Derivatives in Formamide.

Amino acids and their derivatives were probably instrumental in the transition of prebiotic chemistry to early biology. Accordingly, amino acid formation under prebiotic conditions has been intensively investigated. Unsurprisingly, most of these studies have taken place with water as the solvent. Herein, we describe an investigation into the formation and subsequent reactions of aminonitriles and their formylated derivatives in formamide. We find that N-formylaminonitriles form readily from aldehydes and cyanide in formamide, even in the absence of added ammonia, suggesting a potentially prebiotic source of amino acid derivatives. Alkaline processing of N-formylaminonitriles proceeds with hydration at the nitrile group faster than deformylation, protecting aminonitrile derivatives from reversion of the Strecker condensation equilibrium during hydration/hydrolysis and furnishing mixtures of N-formylated and unformylated amino acid derivatives. Furthermore, the facile synthesis of N-formyldehydroalanine nitrile is observed in formamide from glycolaldehyde and cyanide without intervention. Dehydroalanine derivatives have been proposed as important compounds for prebiotic peptide synthesis, and we demonstrate both a synthesis suggesting that they are potentially plausible components of a prebiotic inventory, and reactions showing their utility as abiotic precursors to a range of compounds of prebiological interest.

A biomechanical analysis of double-screw, double-button, and screw-button fixation constructs in patient-specific instrument-guided Latarjet procedure.

BACKGROUND: The Latarjet coracoid transfer procedure reliably stabilizes the glenohumeral joint for shoulder instability. However, complications such as graft osteolysis, nonunion and fracture continue to affect patient clinical outcomes. The double-screw (SS) construct is regarded as the gold standard method of fixation. SS constructs are associated with graft osteolysis. More recently, a double-button technique (BB) has been suggested to minimize graft-related complications. However, BB constructs are associated with fibrous nonunion. To mitigate this risk, a single screw combined with a single button (SB) construct has been proposed. It is thought that this technique incorporates the strength of the SS construct and allows micromotion superiorly to mitigate stress shielding-related graft osteolysis. AIMS: The primary aim of this study was to compare the failure load of SS, BB, and SB constructs under a standardized biomechanical loading protocol. The secondary aim was to characterize the displacement of each construct throughout testing. METHODS: Computed tomography scans of 20 matched-pair cadaveric scapulae were performed. Specimens were harvested and dissected free of soft tissue. SS and BB techniques were randomly assigned to specimens for matched-pair comparison with SB trials. A patient-specific instrument (PSI)-guided Latarjet procedure was performed on each scapula. Specimens were tested using a uniaxial mechanical testing device under cyclic loading (100 cycles, 1 Hz, 200 N/s) followed by a load-to-failure protocol (0.5 mm/s). Construct failure was defined by graft fracture, screw avulsion, and/or graft displacement of more than 5 mm. RESULTS: Forty scapulae from 20 fresh frozen cadavers with a mean age of 69.3 years underwent testing. On average, SS constructs failed at 537.8 N (SD 296.8), whereas BB constructs failed at 135.1 N (SD 71.4). SB constructs required a significantly greater load to fail compared with BB constructs (283.5 N, SD 162.8, P = .039). Additionally, SS (1.9 mm, IQR 0.87) had a significantly lower maximum total graft displacement during the cyclic loading protocol compared with SB (3.8 mm, IQR 2.4, P = .007) and BB (7.4 mm, IQR 3.1, P < .001) constructs. CONCLUSION: These findings support the potential of the SB fixation technique as a viable alternative to SS and BB constructs. Clinically, the SB technique could reduce the incidence of loading-related graft complications seen in the first 3 months of BB Latarjet cases. The study is limited to time-specific results and does not account for bone union or osteolysis.

Cabin Pressure Altitude Effect on Acceleration Atelectasis After Agile Flight Breathing 60% Oxygen.

INTRODUCTION: A flight trial was conducted to determine whether breathing 60% oxygen during high performance flight maneuvers using contemporary pilot flight equipment induces atelectasis and to explore whether cabin altitude had any influence on the extent of atelectasis identified.METHODS: On 2 separate days, 14 male aircrew flew as passengers at High [14,500-18,000 ft (4420-5486 m)] and Low [4000-6000 ft (1219-1829 m)] cabin pressure altitude in a Hawk T Mk1 aircraft breathing 60% oxygen. Sorties comprised 16 maneuvers at +5 Gz, each sustained for 30 s. Lung volumes (spirometry), basal lung volume (electrical impedance tomography, EIT), and peripheral oxygen saturation during transition from hyperoxia to hypoxia (pulmonary shunt fraction) were measured in the cockpit immediately before (Pre) and after (Post) flight.RESULTS: Forced inspiratory vital capacity (FIVC) was significantly lower Postflight after High (-0.24 L) and Low (-0.38 L) sorties, but recovered to Preflight values by the fourth repeat (FIVC4). EIT-derived measures of FIVC decreased after High (-3.3%) and Low (-4.4%) sorties but did not recover to baseline by FIVC4. FIVC reductions were attributable to decreased inspiratory capacity. Spo2 was lower Postflight than Preflight in High and Low sorties.DISCUSSION: Breathing 60% oxygen during flight results in a 3.8-4.9% reduction in lung volume associated with a small decrease in blood oxygenation and an estimated pulmonary shunt of up to 5.7%. EIT measures suggest persisting airway closure despite repeated FIVC maneuvers. There was no meaningful influence of cabin pressure altitude. The operational consequence of the observed changes is likely to be small.Tank H, Kennedy G, Pollock R, Hodkinson P, Sheppard-Hickey R-A, Woolford J, Green NDC, Stevenson A. Cabin pressure altitude effect on acceleration atelectasis after agile flight breathing 60% oxygen. Aerosp Med Hum Perform. 2023; 94(1):3-10.

Initial Investigation of a Grating Stimulus as a Visual Endpoint for Human Centrifuge Research.

INTRODUCTION: G tolerance has been widely assessed using Peripheral Light Loss (PLL), but this approach has several limitations and may lack sensitivity. The aim of this study was to investigate the use of a foveal visual endpoint for centrifuge research (Grating Loss; GL) and assess its repeatability, reliability, and usability with PLL as a reference.METHODS: A total of 11 subjects undertook centrifuge assessment. Gradual onset sessions (GOR; 0.1 G · s-1) measured both endpoints simultaneously and were performed twice, consisting of six determinations with anti-G suits activated (GOR-On) and six without (GOR-Off). Four determinations of each endpoint were also taken during rapid onset runs (ROR; 3 G · s-1). Usability was scored subjectively.RESULTS: The GL endpoint was reached 0.3-0.5 Gz lower than PLL with each endpoint correlating strongly in GOR-Off (r = 0.93), GOR-On (r = 0.95), and ROR (r = 0.86). The GL had excellent test-retest repeatability (intraclass correlation coefficient: GOR-Off/On = 0.99, ROR = 0.92) and low within-subject variability. Between-subject variance equaled PLL in all conditions. Subjective usability endpoint ratings were equal for all conditions.DISCUSSION: For the 11 individuals tested, the GL was a reliable, repeatable, and usable endpoint, with similar performance to PLL. GL may prove useful as a supplementary endpoint for human centrifuge research as a secondary data point or to reduce fatigue in repeated measurements. The foveal GL stimulus was lost before PLL, contrary to popular models of visual changes under +Gz.Britton J, Connolly DM, Hawarden DE, Stevenson AT, Harridge SDR, Green NDC, Pollock RD. Initial investigation of a grating stimulus as a visual endpoint for human centrifuge research. Aerosp Med Hum Perform. 2023; 94(12):894-901.

Natural and anthropogenic factors and their interactions drive stream community integrity in a North American river basin at a large spatial scale.

Urbanization, agriculture, and other human activities can exert considerable influence on the health and integrity of stream ecosystems. These influences vary greatly over space, time, and scale. We investigated trends in stream biotic integrity over 19 years (1997-2016) in relation to natural and anthropogenic factors in their spatial context using data from a stream biomonitoring program in a region dominated by agricultural land use. Macroinvertebrate and fish diversity and abundance data were used to calculate four multimetric indices (MMIs) that described biotic integrity of streams from 1997 to 2016. Boosted regression trees (BRT), a machine learning technique, were used to model how stream integrity responded to catchment-level natural and anthropogenic drivers including land use, human population density, road density, runoff potential, and natural factors such as latitude and elevation. Neither natural nor anthropogenic factors were consistently more influential on the MMIs. Macroinvertebrate indices were most responsive to time, latitude, elevation, and road density. Fish indices were driven mostly by latitude and longitude, with agricultural land cover among the most influential anthropogenic factors. We concluded that 1) stream biotic integrity was mostly stable in the study region from 1997 to 2016, although macroinvertebrate MMIs had decreased approximately 10% since 2010; 2) stream biotic integrity was driven by a mix of factors including geography, human activity, and variability over yearly time intervals; 3) MMI responses to environmental drivers were nonlinear and often nonmonotonic; 4) MMI composition could influence causal inferences; and 5) although our findings were mostly consistent with the literature on drivers of stream integrity, some commonly seen patterns were not evident. Our findings highlight the utility of large-scale, publicly available spatial data for understanding drivers of stream biodiversity and illustrate some potential pitfalls of large scale, integrative analyses.

Unified total synthesis of the brevianamide alkaloids enabled by chemical investigations into their biosynthesis.

The bicyclo[2.2.2]diazaoctane alkaloids are a vast group of natural products which have been the focus of attention from the scientific community for several decades. This interest stems from their broad range of biological activities, their diverse biosynthetic origins, and their topologically complex structures, which combined make them enticing targets for chemical synthesis. In this article, full details of our synthetic studies into the chemical feasibility of a proposed network of biosynthetic pathways towards the brevianamide family of bicyclo[2.2.2]diazaoctane alkaloids are disclosed. Insights into issues of reactivity and selectivity in the biosynthesis of these structures have aided the development of a unified biomimetic synthetic strategy, which has resulted in the total synthesis of all known bicyclo[2.2.2]diazaoctane brevianamides and the anticipation of an as-yet-undiscovered congener.

The effects of a new seat suspension system on whole body vibration exposure and driver low back pain and disability: Results from a randomized controlled trial in truck drivers.

Through a randomized controlled trial, we evaluated the effects of an electro-magnetic active seat suspension that reduces exposure of a long-haul truck driver to whole body vibration (WBV) on low back pain (LBP) and disability. Among 276 drivers recruited from six trucking terminals of a major US trucking company, 135 eligible drivers were assigned to either having an Active Seat (Intervention: n = 70) - the BoseRide® electro-magnetic active seat - or Passive Seat (reference: n = 65) - a new version of their current seat (passive air suspension seat) - installed in their truck via block (terminal) randomization. Low back pain (LBP) severity, on a 0-10 scale and the Oswestry LBP Disability Index were collected before and 3-, 6-, 12-, 18-, and 24-months post seat installation. LBP severity and LBP disability scores were significantly lower post seat installation in both groups. At 3 months, LBP severity decreased -1.4 [95% CI: -2.1 to -0.7: n = 46] for drivers in the Active Seat arm, and -1.5 [95% CI: -2.3 to -0.8: n = 41] for drivers in the Passive Seat arm. In a subset of drivers, WBV exposures were collected before and after the seat installation. WBV exposures significantly decreased post seat installation for Active Seat (p < 0.01) but not for Passive Seat (p = 0.15). While the new seat-suspension technology reduced WBV exposures, LBP appeared to be improved by multiple factors. These results were limited by the secondary prevention approach and the longer-term loss to follow up due to large rates of driver turnover typical for the industry.

Physiological Effects of Centrifuge-Simulated Suborbital Spaceflight.

BACKGROUND: High-G acceleration experienced during launch and re-entry of suborbital spaceflights may present challenges for older or medically susceptible participants. A detailed understanding of the associated physiological responses would support the development of an evidence-based medical approach to commercial suborbital spaceflight.METHODS: There were 24 healthy subjects recruited into 'younger' (18-44 yr), 'intermediate' (45-64 yr) and 'older' (65-80 yr) age groups. Cardiovascular and respiratory variables were measured continuously during dynamic combinations of +Gx (chest-to-back) and +Gz (head-to-foot) acceleration that simulated suborbital G profiles for spaceplane and rocket/capsule platforms. Measurements were conducted breathing air and breathing 15% oxygen to simulate a cabin pressure altitude of 8000 ft.RESULTS: Suborbital G profiles generated highly dynamic changes in heart rate, blood pressure, and cardiac output. G-induced hypoxemia was observed, with minimum arterial oxygen saturation < 80% in a quarter of subjects. Increased age was associated with greater hypoxemia and reduced cardiac output responses but did not have detrimental cardiovascular effects. ECG changes included recurrent G-induced trigeminy in one individual. Respiratory and visual symptoms were common, with 88% of subjects reporting greyout and 29% reporting blackout. There was one episode of G-induced loss of consciousness (G-LOC).DISCUSSION: Suborbital acceleration profiles are generally well tolerated but are not physiologically inconsequential. Marked hemodynamic effects and transient respiratory compromise could interact with predisposing factors to precipitate adverse cardiopulmonary effects in a minority of participants. Medically susceptible individuals may benefit from expanded preflight centrifuge familiarization that includes targeted physiological evaluation in the form of a 'G challenge test'.Smith TG, Pollock RD, Britton JK, Green NDC, Hodkinson PD, Mitchell SJ, Stevenson AT. Physiological effects of centrifuge-simulated suborbital spaceflight. Aerosp Med Hum Perform. 2022; 93(12):830-839.

Prebiotic Photochemical Coproduction of Purine Ribo- and Deoxyribonucleosides.

The hypothesis that life on Earth may have started with a heterogeneous nucleic acid genetic system including both RNA and DNA has attracted broad interest. The recent finding that two RNA subunits (cytidine, C, and uridine, U) and two DNA subunits (deoxyadenosine, dA, and deoxyinosine, dI) can be coproduced in the same reaction network, compatible with a consistent geological scenario, supports this theory. However, a prebiotically plausible synthesis of the missing units (purine ribonucleosides and pyrimidine deoxyribonucleosides) in a unified reaction network remains elusive. Herein, we disclose a strictly stereoselective and furanosyl-selective synthesis of purine ribonucleosides (adenosine, A, and inosine, I) and purine deoxynucleosides (dA and dI), alongside one another, via a key photochemical reaction of thioanhydroadenosine with sulfite in alkaline solution (pH 8-10). Mechanistic studies suggest an unexpected recombination of sulfite and nucleoside alkyl radicals underpins the formation of the ribo C2'-O bond. The coproduction of A, I, dA, and dI from a common intermediate, and under conditions likely to have prevailed in at least some primordial locales, is suggestive of the potential coexistence of RNA and DNA building blocks at the dawn of life.

Timescales for Prebiotic Photochemistry Under Realistic Surface Ultraviolet Conditions.

Ultraviolet (UV) light has long been invoked as a source of energy for prebiotic chemical synthesis, but experimental support does not involve sources of UV light that look like the young Sun. Here we experimentally investigate whether the UV flux available on the surface of early Earth, given a favorable atmosphere, can facilitate a variety of prebiotic chemical syntheses. We construct a solar simulator for the UV light of the faint young Sun on the surface of early Earth, called StarLab. We then attempt a series of reactions testing different aspects of a prebiotic chemical scenario involving hydrogen cyanide (HCN), sulfites, and sulfides under the UV light of StarLab, including hypophosphite oxidation by UV light and hydrogen sulfide, photoreduction of HCN with bisulfite, the photoanomerization of α-thiocytidine, the production of a chemical precursor of a potentially prebiotic activating agent (nitroprusside), the photoreduction of thioanhydrouridine and thioanhydroadenosine, and the oxidation of ethanol (EtOH) by photochemically generated hydroxyl radicals. We compare the output of StarLab to the light of the faint young Sun to constrain the timescales over which these reactions would occur on the surface of early Earth. We predict that hypophosphite oxidation, HCN reduction, and photoproduction of nitroprusside would all operate on the surface of early Earth in a matter of days to weeks. The photoanomerization of α-thiocytidine would take months to complete, and the production of oxidation products from hydroxyl radicals would take years. The photoreduction of thioanhydrouridine with hydrogen sulfide did not succeed even after a long period of irradiation, providing a lower limit on the timescale of several years. The photoreduction of thioanhydroadenosine with bisulfite produced 2'-deoxyriboadenosine (dA) on the timescale of days. This suggests the plausibility of the photoproduction of purine deoxyribonucleotides, such as the photoproduction of simple sugars, proceeds more efficiently in the presence of bisulfite.

Three-Dimensional Quantification of Glenoid Bone Loss in Anterior Shoulder Instability: The Anatomic Concave Surface Area Method.

BACKGROUND: Recurrent shoulder instability may be associated with glenoid erosion and bone loss. Accurate quantification of bone loss significantly influences the contemplation of surgical procedure. In addition, assessment of bone loss is crucial for surgical planning and accurate graft placement during surgery. PURPOSE: To quantify the concave surface area of glenoid bone loss by using 3-dimensional (3D) segmented models of the scapula and to compare this method with the best-fit circle and glenoid height/width methods, which use the glenoid rim for bone loss estimations. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A total of 36 consecutive preoperative bilateral computed tomography scans of patients eligible for a primary Latarjet procedure were selected from our institutional surgical database (mean patient age, 29 ± 9 years; 31 men and 5 women). The 3D models of both scapulae were generated using medical segmentation software and were used to map the anatomic concave surface area (ACSA) of the inferior glenoid using the diameter of the best-fit circle of the healthy glenoid. Bone loss was calculated as a ratio of the difference between surface areas of both glenoids (healthy and pathological) against the anatomic circular surface area of the healthy glenoid (the ACSA method). These results were compared with bone loss calculations using the best-fit circle and glenoid height/width methods. Inter- and intraobserver reliability were also calculated. RESULTS: The mean (± SD) bone loss calculated using the ACSA, the best-fit circle, and glenoid height/width methods was 9.4% ± 6.7%, 14.3% ± 6.8%, and 17.6% ± 7.3%, respectively. The ACSA method showed excellent interobserver reliability, with an intraclass correlation coefficient (ICC) of 0.95 versus those for the best-fit circle (ICC, 0.71) and glenoid height/width (ICC, 0.79) methods. CONCLUSION: Quantification of instability-related glenoid bone loss is reliable using the 3D ACSA method.

2,6-diaminopurine promotes repair of DNA lesions under prebiotic conditions.

High-yielding and selective prebiotic syntheses of RNA and DNA nucleotides involve UV irradiation to promote the key reaction steps and eradicate biologically irrelevant isomers. While these syntheses were likely enabled by UV-rich prebiotic environment, UV-induced formation of photodamages in polymeric nucleic acids, such as cyclobutane pyrimidine dimers (CPDs), remains the key unresolved issue for the origins of RNA and DNA on Earth. Here, we demonstrate that substitution of adenine with 2,6-diaminopurine enables repair of CPDs with yields reaching 92%. This substantial self-repairing activity originates from excellent electron donating properties of 2,6-diaminopurine in nucleic acid strands. We also show that the deoxyribonucleosides of 2,6-diaminopurine and adenine can be formed under the same prebiotic conditions. Considering that 2,6-diaminopurine was previously shown to increase the rate of nonenzymatic RNA replication, this nucleobase could have played critical roles in the formation of functional and photostable RNA/DNA oligomers in UV-rich prebiotic environments.

Illuminating Life's Origins: UV Photochemistry in Abiotic Synthesis of Biomolecules.

Solar radiation is the principal source of energy available to Earth and has unmatched potential for the synthesis of organic material from primordial molecular building blocks. As well as providing the energy for photochemical synthesis of (proto)biomolecules of interest in origins of life-related research, light has also been found to often provide remarkable selectivity in these processes, for molecules that function in extant biology and against those that do not. As such, light is heavily implicated as an environmental input on the nascent Earth that was important for the emergence of complex yet selective chemical systems underpinning life. Reactivity and selectivity in photochemical prebiotic synthesis are discussed, as are their implications for origins of life scenarios and their plausibility, and the future directions of this research.

A Novel Biopsychosocial Approach to Neck Pain in Military Helicopter Aircrew.

INTRODUCTION: Flight-related neck pain (FRNP) is a frequently reported musculoskeletal complaint among military helicopter aircrew. However, despite its prevalence and suspected causes, little is known of the underpinning pain mechanisms or the impact of neck pain on aircrews in-flight task performance. The biopsychosocial (BPS) approach to health, combined with the contemporary conceptualization of musculoskeletal pain, in which injury and pain are not necessarily synonymous, provides a relatively new holistic framework within which to consider the problem of FRNP in military helicopter aircrew. Combining these concepts, a new conceptual model is proposed to illustrate how biopsychosocial factors may influence pain perception, potentially affecting aircrews capacity to process information and, therefore, threatening in-flight task performance. Recommendations are made for considering the underlying pain mechanisms of FRNP to aid prognoses and guide the development of holistic evidence-based countermeasures for FRNP in military helicopter aircrew. Development of instruments able to measure psychosocial factors, such as self-efficacy and functional ability, validated in the military helicopter aircrew population, would assist this task.Vail RE, Harridge SDR, Hodkinson PD, Green NDC, Pavlou M. A novel biopsychosocial approach to neck pain in military helicopter aircrew. Aerosp Med Hum Perform. 2021; 92(5):333341.

Hypoxia-Like Events in UK Typhoon Aircraft from 2008 to 2017.

INTRODUCTION: Recent reports of in-flight, hypoxia-like events have prompted concern that aircraft life support systems (LSS) may not always provide effective altitude protection. An analysis was undertaken of hypoxia-like incidents reported in a UK front-line combat aircraft.METHODS: A search of the UK Aviation Safety Information Management System database identified all Typhoon Defense Air Safety Occurrence Reports (DASORs) notifying in-flight symptoms over the decade 20082017. Qualitative analysis focused on the event narrative, altitude profile, timeline, symptom description, sortie characteristics, LSS function, postflight engineering investigation, and training implications. The plausibility and likelihood of hypobaric hypoxia were assessed, and the probable cause of symptoms ascribed.RESULTS: There were 18 DASORs with notified symptoms of suspected in-flight hypoxia, 13 in solo pilots and 5 reports of symptoms affecting 7 of 10 aircrew in 2-seat aircraft. Two cases of probable hypoxia comprised one oxygen bottle failure and one mask-off cabin depressurization. In one report, hypoxia was assessed as plausible but unlikely, following birdstrike with failure of cabin pressurization during climb. Symptoms were explained by hyperventilation in 13 cases (65%) and twice by minor constitutional upset. Suspected hypoxia was managed by immediate selection of emergency oxygen and expedited descent in 10 of 18 occurrences (56%).CONCLUSIONS: Only 2 cases of probable hypoxia have been reported in over 150,000 Typhoon flying hours. The Typhoon LSS has provided effective altitude protection including during cases of cabin depressurization. Symptom occurrences in Typhoon are idiosyncratic and unrelated; hyperventilation probably accounts for two-thirds of reports.Connolly DM, Lee VM, McGown AS, Green NDC. Hypoxia-like events in UK Typhoon aircraft from 2008 to 2017. Aerosp Med Hum Perform. 2021; 92(4):257264.