Survival and Decision-Making in Patients Turned Down for Abdominal Aortic Aneurysm Repair: A Retrospective Study with Focus on COVID-19 Impact.

BACKGROUND: To investigate and analyze various aspects related to patients who have been placed on a "turndown list" for elective or emergency repair of abdominal aortic aneurysms. METHODS: This retrospective study analyzed data from the Black Country Vascular Network. Multidisciplinary team meetings assessed abdominal aortic aneurysm patients referred through National Abdominal Aortic Aneurysm Screening Program or directly to vascular surgery. Patients considered unfit for intervention were added to a prospectively kept turndown list. Survival and cause of death data were collected, along with cardiopulmonary exercise testing (CPET) results and British Aneurysm Repair scores for some patients. The study covered a period from January 2015 to May 2023. RESULTS: After exclusions, 247 (16%) patients were placed on the turndown list with a median age of 85 years (interquartile range 8 years). The mortality of turndown cases on medical grounds was 74.1%. Survival was significantly higher for patients who completed CPET before being turned down (P = 0.004). Gender analysis revealed a higher proportion of females being turned down compared to males (P = 0.044). COVID-19 led to a notable reduction in the number of discussed cases and interventions, while the turndown rates remained consistent. Survival at 1 year in turndown patients was 66%, at 3 years it was 29%, at 4 years it was 18%, and at 7 years it was 5%. Most patients whose cause of death was known died of respiratory complications (30%) or malignancy (19%). British Aneurysm Repair scores and aneurysm size were not significant predictors of mortality. CONCLUSIONS: Patients on the turndown list have a substantial mortality rate. A significant proportion of female patients were being turned down compared to men and the reasons for this are not clear. Patients who completed CPET before being turned down had a longer survival time. While COVID-19 impacted healthcare services reducing the number of interventions, it did not influence turndown decisions. The study showed that the cause of death for a significant number of patients was respiratory complications or malignancy.

Myoferlin: A Potential Marker of Response to Radiation Therapy and Survival in Locally Advanced Rectal Cancer.

PURPOSE: Patients with locally advanced rectal cancer often require neoadjuvant chemoradiation therapy to downstage the disease, but the response is variable with no predictive biomarkers. We have previously revealed through proteomic profiling that myoferlin is associated with response to radiation therapy. The aims of this study were to further validate this finding and explore the potential for myoferlin to act as a prognostic and/or therapeutic target. METHODS AND MATERIALS: Immunohistochemical analysis of a tissue microarray (TMA) for 111 patients was used to validate the initial proteomic findings. Manipulation of myoferlin was achieved using small interfering RNA, a small molecular inhibitor (wj460), and a CRISPR-Cas9 knockout cell line. Radiosensitization after treatment was assessed using 2-dimensional clonogenic assays, 3-dimensional spheroid models, and patient-derived organoids. Underlying mechanisms were investigated using electrophoresis, immunofluorescence, and immunoblotting. RESULTS: Analysis of both the diagnostic biopsy and tumor resection samples confirmed that low myoferlin expression correlated with a good response to neoadjuvant long-course chemoradiation therapy. High myoferlin expression was associated with spread to local lymph nodes and worse 5-year survival (P = .01; hazard ratio, 3.5; 95% CI, 1.27-10.04). This was externally validated using the Stratification in Colorectal Cancer database. Quantification of myoferlin using immunoblotting in immortalized colorectal cancer cell lines and organoids demonstrated that high myoferlin expression was associated with increased radioresistance. Biological and pharmacologic manipulation of myoferlin resulted in significantly increased radiosensitivity across all cell lines in 2-dimensional and 3-dimensional models. After irradiation, myoferlin knockdown cells had a significantly impaired ability to repair DNA double-strand breaks. This appeared to be mediated via nonhomologous end-joining. CONCLUSIONS: We have confirmed that high expression of myoferlin in rectal cancer is associated with poor response to neoadjuvant therapy and worse long-term survival. Furthermore, the manipulation of myoferlin led to increased radiosensitivity in vitro. This suggests that myoferlin could be targeted to enhance the sensitivity of patients with rectal cancer to radiation therapy, and further work is required.

Changes in an enzyme ensemble during catalysis observed by high-resolution XFEL crystallography.

Enzymes populate ensembles of structures necessary for catalysis that are difficult to experimentally characterize. We use time-resolved mix-and-inject serial crystallography at an x-ray free electron laser to observe catalysis in a designed mutant isocyanide hydratase (ICH) enzyme that enhances sampling of important minor conformations. The active site exists in a mixture of conformations, and formation of the thioimidate intermediate selects for catalytically competent substates. The influence of cysteine ionization on the ICH ensemble is validated by determining structures of the enzyme at multiple pH values. Large molecular dynamics simulations in crystallo and time-resolved electron density maps show that Asp17 ionizes during catalysis and causes conformational changes that propagate across the dimer, permitting water to enter the active site for intermediate hydrolysis. ICH exhibits a tight coupling between ionization of active site residues and catalysis-activated protein motions, exemplifying a mechanism of electrostatic control of enzyme dynamics.

Changes in an Enzyme Ensemble During Catalysis Observed by High Resolution XFEL Crystallography.

Enzymes populate ensembles of structures with intrinsically different catalytic proficiencies that are difficult to experimentally characterize. We use time-resolved mix-and-inject serial crystallography (MISC) at an X-ray free electron laser (XFEL) to observe catalysis in a designed mutant (G150T) isocyanide hydratase (ICH) enzyme that enhances sampling of important minor conformations. The active site exists in a mixture of conformations and formation of the thioimidate catalytic intermediate selects for catalytically competent substates. A prior proposal for active site cysteine charge-coupled conformational changes in ICH is validated by determining structures of the enzyme over a range of pH values. A combination of large molecular dynamics simulations of the enzyme in crystallo and time-resolved electron density maps shows that ionization of the general acid Asp17 during catalysis causes additional conformational changes that propagate across the dimer interface, connecting the two active sites. These ionization-linked changes in the ICH conformational ensemble permit water to enter the active site in a location that is poised for intermediate hydrolysis. ICH exhibits a tight coupling between ionization of active site residues and catalysis-activated protein motions, exemplifying a mechanism of electrostatic control of enzyme dynamics.

A vascular multi-arm multi-stage trial to prevent groin wound surgical site infection: A feasibility survey.

Surgical site infection (SSI) is common following arterial surgery involving a groin incision. There is a lack of evidence regarding interventions to prevent groin wound SSI, therefore, a survey of vascular clinicians was undertaken to assess current opinion and practice, equipoise and feasibility of a randomised controlled trial (RCT). Participants at the Vascular Society of Great Britain and Ireland 2021 Annual Scientific Meeting were surveyed regarding three separate interventions designed to prevent SSI in the groin; impregnated incise drapes, diakylcarbomoyl chloride dressings and antibiotic impregnated collagen sponges. Results were collated via an online survey using the Research Electronic Data Capture platform. Seventy-five participants completed the questionnaire, most were consultant vascular surgeons (50/75, 66.7%). The majority agree that groin wound SSI is a major problem (73/75, 97.3%), and would be content using either of the three interventions (51/61, 83.6%) and had clinical equipoise to randomise patients to any of the three interventions versus standard of care (70/75, 93.3%). There was some reluctance to not use impregnated incise drapes as may be considered "standard of care". Groin wound SSI is perceived as major problem in vascular surgery, and a multicentre RCT of three preventative interventions appears acceptable to vascular surgeons.

Visual Field Pointwise Analysis of the Idiopathic Intracranial Hypertension Weight Trial (IIH:WT).

Purpose: This study was designed to determine if point analysis of the Humphrey visual field (HVF) is an effective outcome measure for people with idiopathic intracranial hypertension (IIH) compared with mean deviation (MD). Methods: Using the IIH Weight Trial data, we performed a pointwise analysis of the numerical retinal sensitivity. We then defined a medically treated cohort as having MDs between -2 dB and -7 dB and calculated the number of points that would have the ability to change by 7 dB. Results: The HVF 24-2 mean ± SD MD in the worse eye was -3.5 ± 1.1 dB (range, -2.0 to -6.4 dB). Total deviation demonstrated a preference for the peripheral and blind spot locations to be affected. Points between 0 dB and -10 dB demonstrated negligible ability to improve, compared with those between -10 dB and -25 dB. For the evaluation of the feasibility for a potential medical intervention trial, only 346 points were available for analysis between -10 dB and -25 dB bilaterally, compared with 4123 points in baseline sensitivities of 0 to -10 dB. Conclusions: Patients with IIH have mildly affected baseline sensitivities in the visual field based on HVF analyzer findings, and the majority of points do not show substantial change over 24 months in the setting of a randomized clinical trial. Most patients with IIH who are eligible for a medical treatment trial generally have the mildest affected baseline sensitivities. In such patients, pointwise analysis offers no advantage over MD in detection of visual field change.

Molecular-dynamics simulation methods for macromolecular crystallography.

It is investigated whether molecular-dynamics (MD) simulations can be used to enhance macromolecular crystallography (MX) studies. Historically, protein crystal structures have been described using a single set of atomic coordinates. Because conformational variation is important for protein function, researchers now often build models that contain multiple structures. Methods for building such models can fail, however, in regions where the crystallographic density is difficult to interpret, for example at the protein-solvent interface. To address this limitation, a set of MD-MX methods that combine MD simulations of protein crystals with conventional modeling and refinement tools have been developed. In an application to a cyclic adenosine monophosphate-dependent protein kinase at room temperature, the procedure improved the interpretation of ambiguous density, yielding an alternative water model and a revised protein model including multiple conformations. The revised model provides mechanistic insights into the catalytic and regulatory interactions of the enzyme. The same methods may be used in other MX studies to seek mechanistic insights.

Unsupervised Machine Learning Shows Change in Visual Field Loss in the Idiopathic Intracranial Hypertension Treatment Trial.

PURPOSE: We previously reported that archetypal analysis (AA), a type of unsupervised machine learning, identified and quantified patterns of visual field (VF) loss in idiopathic intracranial hypertension (IIH), referred to as archetypes (ATs). We assessed whether AT weight changes over time are consistent with changes in conventional global indices, whether visual outcome or treatment effects are associated with select AT, and whether AA reveals residual VF defects in eyes deemed normal after treatment. DESIGN: Analysis of data collected from a randomized controlled trial. PARTICIPANTS: Two thousand eight hundred sixty-two VFs obtained from 165 participants during the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT). METHODS: We applied a 14-AT model derived from IIHTT VFs. We examined changes in individual AT weights over time for all study eyes and evaluated differences between treatment groups. We created an AT change score to assess overall VF change from baseline. We tested threshold baseline AT weights for association with VF outcome and treatment effect at 6 months. We determined the abnormal ATs with meaningful weight at outcome for VFs with a mean deviation (MD) of -2.00 dB or more. MAIN OUTCOME MEASURES: Individual AT weighting coefficients and MD. RESULTS: Archetype 1 (a normal VF pattern) showed the greatest weight change for all study eyes, increasing from 11.9% (interquartile range [IQR], 0.44%-24.1%) at baseline to 31.2% (IQR, 16.0%-45.5%) at outcome (P < 0.001). Archetype 1 weight change (r = 0.795; P < 0.001) and a global score of AT change (r = 0.988; P < 0.001) correlated strongly with MD change. Study eyes with baseline AT2 (a mild diffuse VF loss pattern) weight of 44% or more (≥ 1 standard deviation more than the mean) showed higher AT2 weights at outcome than those with AT2 weight of < 44% at baseline (P < 0.001). Only the latter group showed a significant acetazolamide treatment effect. Archetypal analysis revealed residual VF loss patterns, most frequently representing mild diffuse loss and an enlarged blind spot in 64 of 66 study eyes with MD of -2.00 dB or more at outcome. CONCLUSIONS: Archetypal analysis provides a quantitative approach to monitoring VF changes in IIH. Baseline AT features may be associated with treatment response and VF outcome. Archetypal analysis uncovers residual VF defects not otherwise revealed by MD.

Unsupervised Machine Learning Identifies Quantifiable Patterns of Visual Field Loss in Idiopathic Intracranial Hypertension.

Purpose: Archetypal analysis, a form of unsupervised machine learning, identifies archetypal patterns within a visual field (VF) dataset such that any VF is described as a weighted sum of its archetypes (ATs) and has been used to quantify VF defects in glaucoma. We applied archetypal analysis to VFs affected by nonglaucomatous optic neuropathy caused by idiopathic intracranial hypertension (IIH). Methods: We created an AT model from 2862 VFs prospectively collected from 330 eyes in the IIH Treatment Trial (IIHTT). We compared baseline IIH AT patterns with their descriptive VF classifications from the IIHTT. Results: The optimum IIH AT model yielded 14 ATs resembling VF patterns reported in the IIHTT. Baseline VFs contained four or fewer meaningful ATs in 147 (89%) of study eyes. AT2 (mild general VF depression pattern) demonstrated the greatest number of study eyes with meaningful AT weight at baseline (n = 114), followed by AT1 (n = 91). Other ATs captured patterns of blind spot enlargement, hemianopia, arcuate, nasal defects, and more nonspecific patterns of general VF depression. Of all ATs, AT1 (normal pattern) had the strongest correlation with mean deviation (r = 0.69, P < 0.001). For 65 of the 93 VFs with a dominant AT, this AT matched the expert classification. Conclusions: Archetypal analysis identifies quantifiable, archetypal VF defects that resemble those commonly seen in IIH. Translational Relevance: Archetypal analysis provides a quantitative, objective method of measuring and monitoring disease-specific regional VF defects in IIH.

Mix-and-inject XFEL crystallography reveals gated conformational dynamics during enzyme catalysis.

How changes in enzyme structure and dynamics facilitate passage along the reaction coordinate is a fundamental unanswered question. Here, we use time-resolved mix-and-inject serial crystallography (MISC) at an X-ray free electron laser (XFEL), ambient-temperature X-ray crystallography, computer simulations, and enzyme kinetics to characterize how covalent catalysis modulates isocyanide hydratase (ICH) conformational dynamics throughout its catalytic cycle. We visualize this previously hypothetical reaction mechanism, directly observing formation of a thioimidate covalent intermediate in ICH microcrystals during catalysis. ICH exhibits a concerted helical displacement upon active-site cysteine modification that is gated by changes in hydrogen bond strength between the cysteine thiolate and the backbone amide of the highly strained Ile152 residue. These catalysis-activated motions permit water entry into the ICH active site for intermediate hydrolysis. Mutations at a Gly residue (Gly150) that modulate helical mobility reduce ICH catalytic turnover and alter its pre-steady-state kinetic behavior, establishing that helical mobility is important for ICH catalytic efficiency. These results demonstrate that MISC can capture otherwise elusive aspects of enzyme mechanism and dynamics in microcrystalline samples, resolving long-standing questions about the connection between nonequilibrium protein motions and enzyme catalysis.

Threshold Static Automated Perimetry of the Full Visual Field in Idiopathic Intracranial Hypertension.

Purpose: To characterize visual loss across the full visual field in idiopathic intracranial hypertension (IIH) patients with mild central visual loss. Methods: We tested the full visual field (50° nasal, 80° temporal, 30° superior, 45° inferior) of 1 eye of 39 IIH patients by using static perimetry (size V) with the Open Perimetry Interface. Participants met the Dandy criteria for IIH and had at least Frisén grade 1 papilledema with better than -5 dB mean deviation (MD) centrally. Two observers (MW and AS) evaluated the visual field defects, adjudicated any differences, and reviewed optical coherence tomography data. Results: We found a greater MD loss peripherally than centrally (central 26°). The median MD (and corresponding median absolute deviations) was -1.37 dB (1.61 dB) for the periphery and -0.77 dB (0.87 dB) for the central 26°, P < 0.001. There were about 30% more abnormal test locations identified in the periphery (P = 0.12), and the mean defect depth increased with eccentricity (P < 0.001). The most frequent defect found was a temporal wedge (23% of cases) in the periphery with another 23% that included this sector with inferior temporal loss. Although the presence of papilledema limited correlation, 55% of the temporal wedge defects had optical coherence tomography retinal nerve fiber layer deficits in the corresponding superonasal location. Other common visual field defects were inferonasal loss, superonasal loss, and superior and inferior arcuate defects. Seven patients (18%) had visual field defects in the periphery with normal central visual field testing. Conclusion: In IIH patients, we found substantial visual loss both outside 30° of the visual field and inside 30° with the depth of the defect increasing linearly with eccentricity. Temporal wedge defects were the most common visual field defect in the periphery. Static threshold perimetry of the full visual field appears to be clinically useful in IIH patients.

Artery Ligation for Infected Femoral Pseudoaneurysms Does Carry a High Risk of Major Amputation.

BACKGROUND: Arterial ligation has been described in the literature as a safe and effective procedure with a relatively low number of patients requiring major amputations. METHODS: We performed a retrospective analysis of a prospectively held database of all patients who underwent arterial ligation for infected femoral pseudoaneurysms due to chronic intravenous drug abuse from January 2012 to March 2018. Information recorded for each patient included age, gender, blood investigations, microbiologic results, diagnostic modality, operative details, outcome of surgery, postoperative complications, and follow-up. RESULTS: There were 25 patients identified, with 2 of them undergoing bilateral ligations. It was more common in men (4:1), and the mean age at presentation was 39.7 years (standard deviation 8.2 y). Nine patients underwent major limb amputation for severe limb ischemia (7 transfemoral amputations and two 53 hip disarticulation). Average hospital stay was 24 days, and there was no mortality. We found a trend with a higher level of arterial ligation, leading to a higher rate of amputation. CONCLUSIONS: Our study is the first to show that there is a trend toward a higher risk of amputation with a higher level of ligation in this cohort of patients, and therefore, we suggest avoidance of external iliac artery ligation even at the most distal part just under the ligament, leaving the circumflex iliac vessel in circuit. Arterial ligation also carries a higher risk of major amputation than previously reported.

Influence of Perioperative Serum Magnesium for Cardiac and Noncardiac Morbidity and Mortality Following Emergency Peripheral Vascular Surgery.

OBJECTIVES: To examine the influence of serum magnesium on 30-day mortality and cardiac and noncardiac morbidity. DESIGN: Retrospective cross-sectional observational study of routinely collected prospective data. SETTING: Single-center tertiary vascular center in the United Kingdom. PARTICIPANTS: All patients undergoing arterial peripheral vascular surgery during an unplanned admission. INTERVENTIONS: Observational, no interventions implemented. MEASUREMENTS AND MAIN RESULTS: In the study, n = 197. One hundred thirty-eight were male (70.1%). Median age at procedure was 70.0 years (interquartile range 20.0). Of those with a documented history, 37.9% had diabetes, 81.7% had a smoking history, 63.7% had hypertension, and 26.5% had known ischemic heart disease or heart failure. There was a significant perioperative change in magnesium (p < 0.001), calcium (p < 0.001), and creatinine (p = 0.004), with no significant alteration in potassium (p = 0.096). Thirty-day mortality was 4.6%. Thirty-day cardiac morbidity was 4.1%. Thirty-day noncardiac morbidity was 32.3%. Postoperative magnesium was independently predictive for 30-day mortality (p = 0.02, odds ratio [OR] 0.96, 95% confidence interval [CI] 0.94-0.99) and cardiac morbidity (p = 0.03, OR 0.97, 95% CI 0.95-1.00). Only a previous smoking history was independently predictive of noncardiac morbidity (p = 0.03, OR 9.67, 95% CI 1.20-78.15). CONCLUSION: Perioperative changes in serum magnesium may have an influence on short-term mortality and cardiac complications. This should be considered in the management of patients undergoing unplanned peripheral vascular surgery; however, further research is needed to examine the benefit of supplementation perioperatively and to explore the exact mechanisms.

Development and characterization of a CNS-penetrant benzhydryl hydroxamic acid class IIa histone deacetylase inhibitor.

We have identified a potent, cell permeable and CNS penetrant class IIa histone deacetylase (HDAC) inhibitor 22, with >500-fold selectivity over class I HDACs (1,2,3) and ∼150-fold selectivity over HDAC8 and the class IIb HDAC6 isoform. Dose escalation pharmacokinetic analysis demonstrated that upon oral administration, compound 22 can reach exposure levels in mouse plasma, muscle and brain in excess of cellular class IIa HDAC IC50 levels for ∼8 h. Given the interest in aberrant class IIa HDAC function for a number of neurodegenerative, neuromuscular, cardiac and oncology indications, compound 22 (also known as CHDI-390576) provides a selective and potent compound to query the role of class IIa HDAC biology, and the impact of class IIa catalytic site occupancy in vitro and in vivo.

Short-term Mortality, Morbidity and Recovery Milestones after Major Lower Limb Amputation: a Prospective Evaluation of Outcomes in a Tertiary Center.

BACKGROUND: Major lower limb amputation (MLLA) is well recognized to carry a high rate of mortality; however, little evidence explores the reasons for this. Even fewer studies look at other outcomes after MLLA such as major morbidity and functional and social recovery. This study aims to provide a contemporary analysis of these outcomes to contextualize the current state of care for MLLA in the United Kingdom. METHODS: All index MLLAs conducted in a single tertiary vascular center over a 1-year period were entered into the study. Data including demographic details, preoperative biochemical markers, and functional and social status were collected by a multidisciplinary team . Postoperative functional recovery milestones, and mortality and major morbidity data were collected prospectively from the date of amputation. Descriptive, univariate and multivariate analysis was used to present the results. RESULTS: Seventy-nine amputations were performed. The median total length of stay was 28.0 days (interquartile range [IQR] 14.0-48.0), and postoperative length was 18.0 days (IQR 9.5-36.0). Thirty-day mortality was 5.1% (n = 4), and 90-day mortality was 8.9% (n = 7). Thirty-day major morbidity was 32.4% (n = 24). After controlling for age and gender, preoperative serum white cell count was an independent predictor of 30-day mortality (odds ratio [OR] 1.375 [95% confidence interval [CI] 1.080-1.751]), 90-day mortality (OR 1.258 [95% CI 1.078-1.469]), and 30-day major morbidity (OR 1.228 [95% CI 1.070-1.409]. The proportion of the population living independently reduced from 56.7% to 13.7%, with 23.3% requiring further rehabilitation. The number needing either social care at home or permanent care placement rose by 12.8%. CONCLUSIONS: MLLA carries clinically significant risk of short-term mortality and morbidity. The only factor found to be consistently influential was preoperative serum white cell count. MLLA requires a significant in-hospital stay, and there is a significant deterioration in functional and social status after discharge from hospital.

Is Management of Central Retinal Artery Occlusion the Next Frontier in Cerebrovascular Diseases?

Central retinal artery occlusion (CRAO) is a medical emergency that, if not treated, may result in irreversible loss of vision. It continues to be an important cause for acute painless loss of vision. Amaurosis fugax or "transient CRAO" has long been considered an equivalent of transient cerebral ischemic event. Animal models, in addition to data from retrospective and randomized clinical studies, provide valuable insights into the time interval for irreversible retinal ischemia. Subset analyses from 2 large studies of patients with CRAO show benefit from treatment with thrombolysis within 6 hours from symptoms onset. Significant workflow improvements after the intra-arterial therapy trials for acute ischemic stroke have occurred world over in last 5 years. Patients with CRAO are uniquely suited to receive maximum benefits from the changes in workflow for treatment of patient's acute ischemic stroke. Just as in clinical triage of acute ischemic stroke, correct and timely diagnosis of patients with CRAO may help in preventing visual loss. The approach to acute ocular ischemia should mimic that used for acute brain ischemia. Comprehensive stroke centers would be ideal triage centers for these patients in view of availability of multidisciplinary participation from vascular neurology, neuroendovascular surgery, and ophthalmology. Time is Retina!

The role of compression after endovenous ablation of varicose veins.

OBJECTIVE: The aim of this review was to identify the evidence regarding the optimal duration of compression therapy after endovenous ablation of varicose veins. METHODS: Electronic databases were searched for studies assessing the use of compression after endovenous ablation in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The primary outcomes for this study were pain score and complications. Secondary outcomes were time to full recovery, quality of life score, leg circumference, bruising score, and compliance rates. RESULTS: Following strict inclusion and exclusion criteria, five studies were included in our review, including a total of 734 patients. The short-duration compression therapy ranged from 4 hours to 2 days, whereas the longer duration ranged from 3 to 15 days. A single study showed a better outcome in terms of complications with a short compression therapy. A single study showed a benefit to pain and quality of life with extended compression therapy, whereas the others did not. There was no significant difference in terms of bruising, recovery time, and leg swelling. CONCLUSIONS: Our review showed that there is no evidence for the extended use of compression after endovenous ablation of varicose veins.