Evolution of the ionisation energy with the stepwise growth of chiral clusters of [4]helicene.

Polycyclic aromatic hydrocarbons (PAHs) are widely established as ubiquitous in the interstellar medium (ISM), but considering their prevalence in harsh vacuum environments, the role of ionisation in the formation of PAH clusters is poorly understood, particularly if a chirality-dependent aggregation route is considered. Here we report on photoelectron spectroscopy experiments on [4]helicene clusters performed with a vacuum ultraviolet synchrotron beamline. Aggregates (up to the heptamer) of [4]helicene, the smallest PAH with helical chirality, were produced and investigated with a combined experimental and theoretical approach using several state-of-the-art quantum-chemical methodologies. The ionisation onsets are extracted for each cluster size from the mass-selected photoelectron spectra and compared with calculations of vertical ionisation energies. We explore the complex aggregation topologies emerging from the multitude of isomers formed through clustering of P and M, the two enantiomers of [4]helicene. The very satisfactory benchmarking between experimental ionisation onsets vs. predicted ionisation energies allows the identification of theoretically predicted potential aggregation motifs and corresponding energetic ordering of chiral clusters. Our structural models suggest that a homochiral aggregation route is energetically favoured over heterochiral arrangements with increasing cluster size, hinting at potential symmetry breaking in PAH cluster formation at the scale of small grains.

Risk factors for curable sexually transmitted infections among youth: findings from the STICH population survey in Zimbabwe.

OBJECTIVES: Youth are at high risk of sexually transmitted infections (STIs) in Africa. We aimed to determine the risk factors for curable STIs in youth in Zimbabwe. METHODS: A population-based survey was conducted among randomly selected 18-24 year-olds in 16 communities across two provinces in Zimbabwe to ascertain outcomes for a cluster randomised trial investigating the impact of community-based STI screening for youth on population prevalence of STIs. Participants underwent an interviewer-administered questionnaire, HIV testing and screening for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV). Risk factors for curable STIs were explored through multivariable logistic regression. RESULTS: Of the 5601 participants, 62.5% (n=3500) were female, and the median age was 20 (IQR 19-22) years. HIV prevalence was 6.3% (351/5556), and 55.4% (1939/3501) reported condomless sex at last intercourse. Only 7.2% (401/5599) reported STI symptoms, but CT/NG/TV prevalence was 19.8% (1107/5601). On multivariable analysis, factors associated with STI diagnosis included being aged 21-24 years (adjusted OR (aOR) 1.37, 95% CI 1.17 to 1.61); female sex (aOR 2.11, 95% CI 1.76 to 2.53); being unemployed/informally employed (compared with in education/formal employment) (aOR 1.35, 95% CI 1.13 to 1.61); increasing number of sexual partners in the preceding 12 months (one partner: aOR 2.23, 95% CI 1.73 to 2.88; two partners: aOR 2.39, 95% CI 1.69 to 3.39); living with HIV (aOR 1.44, 95% CI 1.07 to 1.94); and previous attempted suicide (aOR 1.58, 95% CI 1.08 to 2.32). CONCLUSIONS: The prevalence of STIs among youth in Zimbabwe is high, particularly among those with HIV. In addition to moving away from syndromic STI management and strengthening implementation of existing prevention tools, there is a need for a more holistic focus on broader risk factors such as mental health and employment opportunities, and of integration of HIV and STI programming. TRIAL REGISTRATION NUMBER: ISRCTN15013425, NCT03719521.

Helicene Appended Benzothiadiazoles as Chiral Emitters.

A homologous series of 4,7-bis(aryl) substituted benzothiadiazole (BTD) compounds, containing the helicenic derivatives bis([4]helicene), bis([5]helicene) and bis([6]helicene), have been prepared upon a double Suzuki coupling between 3,6-bis(pinacolyl-borane)-BTD and the corresponding bromo-aryl precursors. The single crystal X-ray structure of the bis([4]helicene) compound shows the existence of both helicities (M) and (P) on the same molecule. All the compounds of the series are highly emissive in solution, with quantum yields of the emission ranging from 50 to 91%. The enantiopure compounds (M,M) and (P,P) for the BTD-bis([6]helicene) have been prepared from the corresponding enantiopure 2-bromo-[6]helicene precursors. Their chiroptical properties have been investigated in correlation with density functional theory (DFT) calculations, which allowed to confidently assign the absolute configuration of the helicene arms and to characterize the different electronic transitions, including the low energy charge transfer excitation from helicenes to BTD. The enantiomerically pure fluorophores (M,M)- and (P,P)-BTD-bis([6]helicene), which exist in solution as two main conformers, according to the DFT calculations, show CPL activity in solution, with glum factors of ≈ 1.7×10-3 at lem = 525 nm, and also in the solid state, with glum factors of ≈ 1.2×10-3 in spite of the strong decrease of the quantum efficiency.

Chronic Achilles Tendon Avulsion Repair: Central Third Fascia Slide Technique with Flexor Hallucis Longus Transfer.

Background: Chronic Achilles tendon defects are commonly associated with substantial impairment in gait and push-off strength, leading to decreased function1. These injuries cause a unique surgical dilemma, with no consensus surgical reconstruction technique for >6-cm gaps3. There are a multitude of surgical reconstruction techniques that rely on gap size as a determinant for preoperative planning1,2. The present article describes a technique for chronic Achilles tendon defects of >6 cm. The central third fascia slide (CTFS) technique with flexor hallucis longus (FHL) transfer provides adequate excursion and strength while avoiding use of allograft.2.The CTFS technique is a reconstructive technique that is utilized to treat large chronically gapped Achilles tendon tears, usually larger than 5 to 6 cm; however, recent literature has shown that intermediate gaps can be fixed with use of a combination of tendon transfers. The technique described here is a variation of the V-Y tendinoplasty and fascia turndown method in which the gastrocnemius complex fascia is slid down rather than being "turned down." This reconstructive technique, like its predecessor, restores function in damaged Achilles tendons3. Chronic gapping from a chronic Achilles tendon rupture can lead to decreased function and weakness. Patients may also experience fatigue and gait imbalance, leading to the need for surgical reconstruction to help restore functionality. Description: The CTFS technique utilizes a posterior midline incision, maintaining full-thickness flaps. A complete debridement of the degenerative Achilles tendon is performed, and the gap is measured. If the gap is >6 cm, the central third of the remaining Achilles and gastrocnemius fascia are sharply harvested. The FHL is transferred to the proximal Achilles footprint and held with use of an interference screw. The ankle is held in 15° to 25° of plantar flexion while the FHL shuttling suture is pulled plantarly and secured with a bio-interference screw. The fascial graft is then anchored to the calcaneus with use of a double-row knotless technique, maximizing osseous contact potential healing. Soft-tissue clamps are placed on the graft and on the gastrocnemius complex harvest site. The ankle is tensioned in nearly 30° of plantar flexion to account for known postoperative elongation. FiberWire (Arthrex) is utilized to secure the tension, then the remaining suture tape from the proximal insertional row is run up each side of the fascial graft in a running locking stitch, continuing proximally to close the harvest site. The use of an anchor-stay stitch helps to prevent elongation and maximizes construct strength. Alternatives: For patients who are poor surgical candidates or those with acceptable function, alternatives include nonoperative treatment and/or the use of a molded ankle foot orthosis. Most chronic Achilles tendon ruptures require surgery. Generally, a gap of <2 cm can be treated through primary repair with use of longitudinal and distally applied traction. For an Achilles gap of >2 cm but <6 cm, a V-Y gastrocnemius-lengthening procedure can utilized. Other methods such as autologous and local tendon transfers, advancement procedures, or a combination of these have been described as ways to treat gaps within this range. For gaps of >6 cm, there is insufficient literature to establish a single gold-standard reconstructive technique. Some surgeons have opted to utilize the turndown flap procedure, the FHL tendon transfer technique, or a combination of both. Rationale: The Achilles turndown flap technique can lead to the formation of scar tissue at the focal point of the turndown, a region also known as the hinge joint, and thus can perpetuate scarring of the repair site. To avoid this scarring, the central third fascia slide technique with FHL transfer is presented as a suitable reconstructive technique for chronic tendon defects of >6 cm. Expected Outcomes: Postoperatively, patients are managed according to a standard protocol. The first 2 weeks are non-weight-bearing with the foot in equinus in an L & U splint. At 2 to 4 weeks postoperatively, a walking boot with a 1.5-cm heel lift is applied, and crutches are utilized as the primary weight-bearing aid. At 4 to 6 weeks, the patient is transitioned to a 1-cm heel lift and may discontinue the use of crutches if they are able to walk without a limp. At 8 weeks, the patient may discontinue the use of the walking boot. At week 6 to 12, no heel lift is required. By approximately 12 weeks postoperatively, the patient should have regained full range of motion and should be able to walk without a limp. The patient should be able to resume activities of daily living by 3 to 4 months, with a gradual return to all physical activities by 4 to 6 months This postoperative protocol has produced favorable results. Ahmad et al. have reported the use of a similar protocol, with patients showing increased Foot and Ankle Ability Measure scores and decreased visual analog scale pain scores compared with the preoperative measurement2. Important Tips: Debride the Achilles until viable tendon is reached, then measure the defect.Tension the FHL and the fascia slide with the foot in 15° to 25° of plantar flexion.Perform a meticulous layered closure, preserving the paratenon as much as possible.Incomplete debridement may result in incompetent tissue.Incomplete closure of the fascia harvest site may predispose to seroma or hematoma formation.Not splinting for 10 to 14 days potentially predisposes the patient to wound breakdown. Acronyms and Abbreviations: CTFS = central third fascia slideFHL = flexor hallucis longusATTF = Achilles tendon turndown flapHPI = history of present illnessNWB = non-weight-bearingCAM = controlled ankle motionDVT = deep vein thrombosisMRI = Magnetic resonance imagingPMHx = past medical historyHTN = hypertensionSHx = social historyPE = physical examinationDF = dorsiflexionNVI = neurovascularly intactROM = range of motion.

Stability of One-Step Spray-on Splint for Lower Extremity Fractures During Splinting, MEDEVAC, and Impact.

INTRODUCTION: Military transport can induce whole-body vibrations, and combat almost always involves high impact between lower extremities and the ground. Therefore, robust splinting technology is necessary for lower extremity fractures in these settings. Our team compared a novel one-step spray-on foam splint (FastCast) to the current military standard structured aluminum malleable (SAM) splint. MATERIALS AND METHODS: Ten cadaveric specimens were subjected to complete tibia/fibula osteotomy. Specimens were fitted with custom accelerometer and gyroscope sensors superior and inferior to the fracture line. Each specimen underwent fracture and splinting from a standard of care SAM splint and an experimental FastCast spray foam splint in a randomized order. Each specimen was manually transported to an ambulance and then released from a 1 meter height to simulate impact. The custom sensors recorded accelerations and rotations throughout each event. Repeated-measures Friedman tests were used to assess differences between splint method within each event and between sensors within each splint method. RESULTS: During splinting, overall summation of change and difference of change between sensors for accelerations and rotations were greater for SAM splints than FastCast across all axes (P ≤ 0.03). During transport, the range of acceleration along the linear superior/inferior axis was greater for SAM splint than FastCast (P = 0.02), as was the range of rotation along the transverse plane (P < 0.01). On impact, the summation of change observed was greater for SAM splint than FastCast with respect to acceleration and rotation on the posterior/anterior and superior/inferior axes (P ≤ 0.03), and the cumulative difference between superior and inferior sensors was greater for SAM than FastCast with respect to anterior-axis rotation (P < 0.05). CONCLUSION: FastCast maintains stabilization of fractured lower extremities during transport and impacts to a significantly greater extent than SAM splints. Therefore, FastCast can potentially reduce the risk of fracture complications following physical stressors associated with combat and extraction.

Managing cybersecurity risk in healthcare settings.

Cybersecurity attacks have been steadily increasing in the healthcare sector over the past decade. Health data is a valuable source of reliable and permanent personal information making it an attractive target. Institutions that have faced limited cybersecurity funding must now augment their approach to combat this threat. The Internet of Things (IoT) refers to the connection of physical operational devices to digital networks allowing for communication between devices. In the healthcare setting, this includes patient monitoring, diagnostics, and even robotic surgery devices. This increased connectivity increases the importance of agile and robust cybersecurity measures. A progressive approach must involve collaboration between information technology, clinical, and administrative leaders to be successful. Adequate protection of patient data and the integrity of digital infrastructure must be a priority mandate at the enterprise level.

The Triplanar Hallux Abducto Valgus Classification System: Is it Valid?

Historically, 2-dimensional radiographic study techniques have been used to classify deformity and guide treatment of hallux valgus deformities in the transverse plane. Recently, a triplanar hallux abducto valgus classification system was proposed. The key elements of this classification system are the pathologic alignments in 3 anatomic planes. The triplanar hallux abducto valgus classification system is intended to clarify the deformity and apply a triplanar anatomic algorithm for treatment. To our knowledge, this classification system has not been validated. Our objective was to assess reliability of the triplanar hallux valgus classification system. Patients with hallux abducto valgus were identified from a foot and ankle registry. Digital radiographs were assembled in a digital slide presentation. The eligibility criteria required complete radiographic studies and represented varying degrees of hallux abducto valgus. The reviewers included 3 board-certified, fellowship-trained orthopedic foot and ankle surgeons. Each reviewer independently classified the hallux abducto valgus deformity for a total of 75 observations. After an 8-week washout period, the order of the hallux abducto valgus cases was randomized in the digital slide presentation and redistributed to the reviewers. The average kappa value from 3 readers was 0.241 with 95% CI (0.093-0.374), indicating a fair agreement. The inter-reader agreement was 0.046 with 95% CI (-0.041 to 0.112), showing poor agreement between readers. Our results indicate the triplanar hallux abducto valgus is not a reliable classification system. While this is the first known triplanar hallux abducto valgus classification system, it lacks prognostic value and reliability.

Arthroscopic Assisted, Lateral Ligament Reconstruction with Suture Tape Augmentation and Knotless All Suture Anchors: A Technique Guide.

More than 30,000 ankle sprains occur each day in the United States, and the majority of ankle sprains involve the anterior talofibular ligament. Up to 30% of patients develop functional ankle instability and chronic pain after a severe ankle sprain. When nonoperative measures are unsuccessful, operative reconstruction of the lateral ankle ligaments is recommended. To further strengthen the repair, accelerate rehabilitation, and allow for a quicker return to sport, augmentation with suture tape has recently become an alternative among surgeons in the reconstruction of the lateral ankle ligaments. Moreover, the advent of knotless all-suture anchors decreases the number of knots required in the procedure and, in theory, reduces lateral soft tissue irritation and accentuates recovery after surgery. Here we present our technique for arthroscopic assisted, lateral ligament reconstruction with suture tape augmentation and knotless all suture anchors.

Modified Low-Flow Arthroscopic Sandwich Technique for Complex Osteochondral Lesions of the Talus.

Treatment of osteochondral lesions of the talus proves to be challenging given the unique anatomy of the intra-articular surface and associated complexity of larger lesions. Simple bone marrow-stimulating procedures for large complex lesions often lead to poor results with increased risk of lesion progression, refractory pain, and associated functional limitations. Other methods of osteochondral autografts or allografts often require osteotomies, bone windows, or fibrin glue, which are associated with donor pain and nonunion. Thus, for larger and cystic lesions, we report our experience using a modified low-flow arthroscopic sandwich technique consisting of autologous cancellous bone graft, followed by a viable cryopreserved cartilage fiber, cartilage allograft matrix putty.

Managing Phosphate Burden in Patients Receiving Dialysis: Beyond Phosphate Binders and Diet.

Most patients receiving dialysis rely on dietary restriction and phosphate binders to minimize the risk of hyperphosphatemia, which is associated with increased mortality. However, dietary restriction is difficult because of hidden phosphate additives in processed foods and medications. Restriction of dietary phosphate sources such as protein may increase the risk of malnutrition. Phosphate binders, the only pharmacologic option for phosphate management since aluminum salts were introduced several decades ago, are often insufficient for binding the 1400-2500 mg of phosphate potentially consumed daily. Over the last decade, serum phosphate levels in the United States have risen, and >69% of patients receiving dialysis exhibited a most recent phosphate level >4.5 mg/dl (above the normal range), indicating an urgent need for new, more effective therapies to manage phosphate burden. Novel, nonbinder therapies such as transcellular and paracellular phosphate absorption inhibitors may be used for phosphate management, and future studies should examine whether they allow fewer dietary restrictions for patients receiving dialysis, potentially improving patient quality of life and nutritional status. It is imperative that we collaborate to move beyond the restrictive approaches available today and provide patients and clinicians with an array of strategies so that they may choose the most appropriate patient-centered therapy.

Technique Variation in the Surgical Treatment of Lateral Ankle Instability.

INTRODUCTION: Lateral ankle sprains are the most common type of injury to the ankle and can lead to ankle instability. There are many described techniques for the surgical treatment of lateral ankle instability. The purpose of this study is to quantify the variation in surgeon technique for lateral ankle instability treatment. METHODS: Surveys were sent to 62 orthopaedic foot and ankle surgeons regarding surgical technique for the treatment of lateral ankle instability. Clinical agreement was defined as greater than 80% agreement to assess the cohesiveness of surgical methods as described by Marx et al. Results. Response rate was 49/62 (79%). There was clinical agreement for not using bone tunnels and not using metal anchors. All other factors lacked clinical agreement. A greater average number of throws and knots (4.2 for each, range 1-6 throws, range 2-12 knots) were used by surgeons that do not believe knots cause pain compared to an average of 3.9 (range, 1-6) throws and 4.0 (range, 2-15) knots by surgeons who do believe knots cause pain. The association that surgeon who believed knots do cause pain and thus used fewer knots and throws was not statistically significant (P > .05). The preferred material by surgeons in our study are as follows: nonabsorbable braided suture (26/49, 53%), suture tape (15/49, 31%), and fiber tape (4/49, 8%). Among surgeons who use absorbable suture (34/49, 69%), there was no significant difference (P > .05) between surgeons who believe knots cause pain (23/34, 68%) and those who do not (11/34, 32%). DISCUSSION AND CONCLUSION: Among this small sample of orthopaedic foot and ankle surgeons, there is wide variation in surgical technique for lateral ankle instability treatment and little agreement on the clinical standard of care. This disagreement highlights the need for comparative outcome studies in the treatment of ankle instability. LEVEL OF EVIDENCE: Level III: Retrospective cohort study.

Financial incentives to improve uptake of partner services for sexually transmitted infections in Zimbabwe antenatal care: protocol for a cluster randomised trial.

Introduction: Sexually transmitted infections (STIs) such as chlamydia, gonorrhoea, trichomoniasis, and syphilis, are associated with adverse birth outcomes. Treatment should be accompanied by partner services to prevent re-infection and break cycles of transmission. Partner services include the processes of partner notification (PN) as well as arranging for their attendance for testing and/or treatment. However, due to a complex mix of cultural, socio-economic, and health access factors, uptake of partner services is often very low, in many settings globally. Alternative strategies to facilitate partner services are therefore needed.The aim of this study is to assess the impact of a small financial incentive on uptake of partner services for STIs as part of antenatal care (ANC) services in Zimbabwe. Methods and analysis: This trial will be embedded within a prospective interventional study in Harare, aiming to evaluate integration of point-of-care diagnostics for STIs into ANC settings. One thousand pregnant women will be screened for chlamydia, gonorrhoea, trichomoniasis, and syphilis. All individuals with STIs will be offered treatment, risk reduction counselling, and client PN. Each clinic day will be randomised 1:1 to be an incentive or non-incentive day. On incentive days, participants diagnosed with a curable STI will be offered a PN slip, that when returned will entitle their partners to $3 (USD) in compensation. On non-incentive days, regular PN slips with no incentive are provided.The primary outcome measure is the proportion of individuals with at least one partner who returns for partner services based on administrative records. Secondary outcomes will include the number of days between index case diagnosis and the partner attending for partner services, uptake of PN slips by pregnant women, adverse birth outcomes in index cases, partners who receive treatment, and intervention cost. Registration: Pan African Clinical Trials Registry: PACTR202302702036850 (Approval date 18 th February 2022).

Applying the concept of niche breadth to understand urban tree mortality in the UK.

Accelerated climate change has raised concerns about heightened vulnerability of urban trees, spurring the need to reevaluate their suitability. The urgency has also driven the widespread application of climatic niche-based models. In particular, the concept of niche breadth (NB), the range of environmental conditions that species can tolerate, is commonly estimated based on species occurrence data over the selected geographic range to predict species response to changing conditions. However, in urban environments where many species are cultivated out of the NB of their natural distributions, additional empirical evidence beyond presence and absence is needed not only to test the true tolerance limits but also to evaluate species' adaptive capacity to future climate. In this research, mortality trends of Acer and Quercus species spanning a 21-year period (2000-2021) from tree inventories of three major UK botanic gardens - the Royal Botanic Gardens, Kew (KEW), Westonbirt, the National Arboretum (WESB), and the Royal Botanic Garden Edinburgh (RBGE) - were analyzed in relation to their NB under long-term drought stress. As a result, Acer species were more responsive to drought and heat stress. For Acer, positioning below the lower limits of the precipitation of warmest quarter led to an increase in the probability of annual mortality by 1.2 and 1.3 % at KEW and RBGE respectively. In addition, the mean cumulative mortality rate increased corresponding to an increase in the number of niche positions below the lower limits of the selected bioclimatic variables. On the other hand, Quercus species in general exhibited comparable resilience regardless of their niche positions. Moreover, Mediterranean oaks were most tolerant, with cumulative mortality rates that were lower than those of native oaks in the UK. These findings further highlight the importance of incorporating ecological performance and recognizing species-specific adaptive strategies in climatic niche modeling.

Electrical Impedance Tomography Identifies Evolution of Regional Perfusion in a Porcine Model of Acute Respiratory Distress Syndrome.

BACKGROUND: Bedside electrical impedance tomography could be useful to visualize evolving pulmonary perfusion distributions when acute respiratory distress syndrome worsens or in response to ventilatory and positional therapies. In experimental acute respiratory distress syndrome, this study evaluated the agreement of electrical impedance tomography and dynamic contrast-enhanced computed tomography perfusion distributions at two injury time points and in response to increased positive end-expiratory pressure (PEEP) and prone position. METHODS: Eleven mechanically ventilated (VT 8 ml · kg-1) Yorkshire pigs (five male, six female) received bronchial hydrochloric acid (3.5 ml · kg-1) to invoke lung injury. Electrical impedance tomography and computed tomography perfusion images were obtained at 2 h (early injury) and 24 h (late injury) after injury in supine position with PEEP 5 and 10 cm H2O. In eight animals, electrical impedance tomography and computed tomography perfusion imaging were also conducted in the prone position. Electrical impedance tomography perfusion (QEIT) and computed tomography perfusion (QCT) values (as percentages of image total) were compared in eight vertical regions across injury stages, levels of PEEP, and body positions using mixed-effects linear regression. The primary outcome was agreement between QEIT and QCT, defined using limits of agreement and Pearson correlation coefficient. RESULTS: Pao2/Fio2 decreased over the course of the experiment (healthy to early injury, -253 [95% CI, -317 to -189]; early to late injury, -88 [95% CI, -151 to -24]). The limits of agreement between QEIT and QCT were -4.66% and 4.73% for the middle 50% quantile of average regional perfusion, and the correlation coefficient was 0.88 (95% CI, 0.86 to 0.90]; P < 0.001). Electrical impedance tomography and computed tomography showed similar perfusion redistributions over injury stages and in response to increased PEEP. QEIT redistributions after positional therapy underestimated QCT in ventral regions and overestimated QCT in dorsal regions. CONCLUSIONS: Electrical impedance tomography closely approximated computed tomography perfusion measures in experimental acute respiratory distress syndrome, in the supine position, over injury progression and with increased PEEP. Further validation is needed to determine the accuracy of electrical impedance tomography in measuring perfusion redistributions after positional changes.

Regional lung perfusion using different indicators in electrical impedance tomography.

Management of acute respiratory distress syndrome (ARDS) is classically guided by protecting the injured lung and mitigating damage from mechanical ventilation. Yet the natural history of ARDS is also dictated by disruption in lung perfusion. Unfortunately, diagnosis and treatment are hampered by the lack of bedside perfusion monitoring. Electrical impedance tomography is a portable imaging technique that can estimate regional lung perfusion in experimental settings from the kinetic analysis of a bolus of an indicator with high conductivity. Hypertonic sodium chloride has been the standard indicator. However, hypertonic sodium chloride is often inaccessible in the hospital, limiting practical adoption. We investigated whether regional lung perfusion measured using electrical impedance tomography is comparable between indicators. Using a swine lung injury model, we determined regional lung perfusion (% of total perfusion) in five pigs, comparing 12% sodium chloride to 8.4% sodium bicarbonate across stages of lung injury and experimental conditions (body position, positive end-expiratory pressure). Regional lung perfusion for four lung regions was determined from maximum slope analysis of the indicator-based impedance signal. Estimates of regional lung perfusion between indicators were compared in the lung overall and within four lung regions. Regional lung perfusion estimated with a sodium bicarbonate indicator agreed with a hypertonic sodium chloride indicator overall (mean bias 0%, limits of agreement -8.43%, 8.43%) and within lung quadrants. The difference in regional lung perfusion between indicators did not change across experimental conditions. Sodium bicarbonate may be a comparable indicator to estimate regional lung perfusion using electrical impedance tomography.NEW & NOTEWORTHY Electrical impedance tomography is an emerging tool to measure regional lung perfusion using kinetic analysis of a conductive indicator. Hypertonic sodium chloride is the standard agent used. We measured regional lung perfusion using another indicator, comparing hypertonic sodium chloride to sodium bicarbonate in an experimental swine lung injury model. We found strong agreement between the two indicators. Sodium bicarbonate may be a comparable indicator to measure regional lung perfusion with electrical impedance tomography.

Dorsal Cheilectomy Using Great Toe Metatarsophalangeal Joint Arthroscopy for the Treatment of Hallux Rigidus.

Great toe metatarsophalangeal joint (MTPJ) arthroscopy has been described in the literature for more than 50 years for treatment of a multitude of first MTPJ pathologies, including hallux rigidus, hallux valgus, and osteochondritis dissecans, among others. Despite this, the use of great toe MTPJ arthroscopy has not become widely used for treatment of these conditions as the result of reported difficulties with adequate visualization of the joint surface and manipulation of surrounding soft-tissue structures with the instruments available. We propose a simple technique with illustrations of the operating room setup and procedural steps to perform a dorsal cheilectomy in those with early-stage hallux rigidus using great toe MTPJ arthroscopy and a minimally invasive surgical burr in a way that is reproducible by foot and ankle surgeons.

Improving pulmonary perfusion assessment by dynamic contrast-enhanced computed tomography in an experimental lung injury model.

Pulmonary perfusion has been poorly characterized in acute respiratory distress syndrome (ARDS). Optimizing protocols to measure pulmonary blood flow (PBF) via dynamic contrast-enhanced (DCE) computed tomography (CT) could improve understanding of how ARDS alters pulmonary perfusion. In this study, comparative evaluations of injection protocols and tracer-kinetic analysis models were performed based on DCE-CT data measured in ventilated pigs with and without lung injury. Ten Yorkshire pigs (five with lung injury, five healthy) were anesthetized, intubated, and mechanically ventilated; lung injury was induced by bronchial hydrochloric acid instillation. Each DCE-CT scan was obtained during a 30-s end-expiratory breath-hold. Reproducibility of PBF measurements was evaluated in three pigs. In eight pigs, undiluted and diluted Isovue-370 were separately injected to evaluate the effect of contrast viscosity on estimated PBF values. PBF was estimated with the peak-enhancement and the steepest-slope approach. Total-lung PBF was estimated in two healthy pigs to compare with cardiac output measured invasively by thermodilution in the pulmonary artery. Repeated measurements in the same animals yielded a good reproducibility of computed PBF maps. Injecting diluted isovue-370 resulted in smaller contrast-time curves in the pulmonary artery (P < 0.01) and vein (P < 0.01) without substantially diminishing peak signal intensity (P = 0.46 in the pulmonary artery) compared with the pure contrast agent since its viscosity is closer to that of blood. As compared with the peak-enhancement model, PBF values estimated by the steepest-slope model with diluted contrast were much closer to the cardiac output (R2 = 0.82) as compared with the peak-enhancement model. DCE-CT using the steepest-slope model and diluted contrast agent provided reliable quantitative estimates of PBF.NEW & NOTEWORTHY Dynamic contrast-enhanced CT using a lower-viscosity contrast agent in combination with tracer-kinetic analysis by the steepest-slope model improves pulmonary blood flow measurements and assessment of regional distributions of lung perfusion.

Investigating point-of-care diagnostics for sexually transmitted infections and antimicrobial resistance in antenatal care in Zimbabwe (IPSAZ): protocol for a mixed-methods study.

INTRODUCTION: Sexually transmitted infections (STIs) can cause serious morbidity, including pelvic inflammatory disease, and adverse pregnancy outcomes. In low/middle-income countries, limited laboratory infrastructure has resulted in a syndrome-based approach being used for management of STIs, which has poor sensitivity and specificity, leading to considerable underdiagnosis and overtreatment. The WHO has called for development and evaluation of strategies to inform replacement of syndromic management by diagnostic testing.The aim of this project is to evaluate a strategy of point-of-care testing for six STIs in antenatal care (ANC) in Zimbabwe. METHODS AND ANALYSIS: A prospective interventional study will be conducted in ANC clinics in Harare province, Zimbabwe. One thousand pregnant women will be recruited when registering for routine ANC. Alongside routine HIV and syphilis testing, participants will be offered an integrated screening package including testing for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Trichomonas vaginalis (TV) and hepatitis B. All individuals with STIs will receive treatment, partner notification services, risk reduction counselling and referral if needed according to national guidelines. Gonorrhoea samples will be cultured and tested for antimicrobial resistance as per WHO enhanced gonococcal antimicrobial surveillance programme guidelines.The primary outcome measure is the composite prevalence of CT, NG, TV, syphilis and hepatitis B. A mixed-methods process evaluation and economic evaluation will be conducted to understand the acceptability, feasibility and cost-effectiveness of integrated STI testing, compared with standard of care (syndromic management). ETHICS AND DISSEMINATION: The study protocol was approved by the Medical Research Council of Zimbabwe, the Biomedical Research and Training Institute Institutional Review Board, and the London School of Hygiene & Tropical Medicine Research Ethics Committee. Results will be submitted to open-access peer-reviewed journals, presented at academic meetings and shared with participating communities and with national and international policymaking bodies. TRIAL REGISTRATION NUMBER: NCT05541081.

Highly Stereospecific On-Surface Dimerization into Bishelicenes: Topochemical Ullmann Coupling of Bromohelicene on Au(111).

The on-surface dimerization into bis(hexahelicene) on a gold(111) surface has been studied by means of scanning tunneling microscopy and time-of-flight secondary mass spectrometry. C-C Ullmann coupling of (rac)-2-bromo-hexahelicene leads to formation of the (M,M)- and (P,P)-diastereomers of 2,2'-bis(hexahelicene), whilst formation of the (M,P)-diastereomer is not observed. Upon cooling, the bis(hexahelicene) aggregates into an ordered two-dimensional lattice with partly randomly distributed enantiomers. The highly specific diastereomeric coupling is explained by the surface alignment of educt in combination with the strong steric overcrowding in a possible surface-confined (M,P)-product.