Assessment of the nano-mechanical properties of healthy and atherosclerotic coronary arteries by atomic force microscopy.

Nano-indentation techniques might be better equipped to assess the heterogeneous material properties of plaques than macroscopic methods but there are no bespoke protocols for this kind of material testing for coronary arteries. Therefore, we developed a measurement protocol to extract mechanical properties from healthy and atherosclerotic coronary artery tissue sections. Young's modulus was derived from force-indentation data. Metrics of collagen fibre density were extracted from the same tissue, and the local material properties were co-registered to the local collagen microstructure with a robust framework. The locations of the indentation were retrospectively classified by histological category (healthy, plaque, lipid-rich, fibrous cap) according to Picrosirius Red stain and adjacent Hematoxylin & Eosin and Oil-Red-O stains. Plaque tissue was softer (p < 0.001) than the healthy coronary wall. Areas rich in collagen within the plaque (fibrous cap) were significantly (p < 0.001) stiffer than areas poor in collagen/lipid-rich, but less than half as stiff as the healthy coronary media. Young's moduli correlated (Pearson's ρ = 0.53, p < 0.05) with collagen content. Atomic force microscopy (AFM) is capable of detecting tissue stiffness changes related to collagen density in healthy and diseased cardiovascular tissue. Mechanical characterization of atherosclerotic plaques with nano-indentation techniques could refine constitutive models for computational modelling.

Considering the Influence of Coronary Motion on Artery-Specific Biomechanics Using Fluid-Structure Interaction Simulation.

The endothelium in the coronary arteries is subject to wall shear stress and vessel wall strain, which influences the biology of the arterial wall. This study presents vessel-specific fluid-structure interaction (FSI) models of three coronary arteries, using directly measured experimental geometries and boundary conditions. FSI models are used to provide a more physiologically complete representation of vessel biomechanics, and have been extended to include coronary bending to investigate its effect on shear and strain. FSI both without- and with-bending resulted in significant changes in all computed shear stress metrics compared to CFD (p = 0.0001). Inclusion of bending within the FSI model produced highly significant changes in Time Averaged Wall Shear Stress (TAWSS) + 9.8% LAD, + 8.8% LCx, - 2.0% RCA; Oscillatory Shear Index (OSI) + 208% LAD, 0% LCx, + 2600% RCA; and transverse wall Shear Stress (tSS) + 180% LAD, + 150% LCx and + 200% RCA (all p < 0.0001). Vessel wall strain was homogenous in all directions without-bending but became highly anisotropic under bending. Changes in median cyclic strain magnitude were seen for all three vessels in every direction. Changes shown in the magnitude and distribution of shear stress and wall strain suggest that bending should be considered on a vessel-specific basis in analyses of coronary artery biomechanics.

Development and initial validation of the Kiswahili version of the Migraine Disability Assessment (MIDAS-K) questionnaire.

BACKGROUND: The Migraine Disability Assessment Scale (MIDAS) is one of the tools for measuring and understanding disability caused by migraine. The purpose of this study was to validate a Kiswahili translation of the MIDAS (MIDAS-K) among patients suffering from migraines in Dar es Salaam, Tanzania. METHODS: A psychometric validation study of MIDAS was conducted after translation to Kiswahili. A total of 70 people with migraine were recruited by systematic random sampling and they completed the MIDAS-K questionnaire twice, 10-14 days apart. Internal consistency, split-half reliability, and test-retest reliability, convergent and divergent validity were examined. RESULTS: 70 patients (F:M; 59:11) with median (25th, 75th) headache days of 4.0 (2.0, 7.0) were recruited. Twenty-eight out of 70 (40%) of the population had severe disability on MIDAS-K. The overall test-retest reliability of MIDAS-K was high (ICC = 0.86; 95% CI = 0.78-0.92 p < 0.001). Factor analysis showed a two-factor structure; the number of days missed and reduced efficiency. MIDAS-K had a good internal consistency of 0.78, good split-half reliability of 0.80 and acceptable test-retest reliability for all items as well as total MIDAS-K scores. CONCLUSION: The Kiswahili version of the MIDAS questionnaire (MIDAS-K) is a valid, responsive, and reliable tool to measure migraine-related disability among Tanzanians and other Swahili-speaking populations. Quantification of migraine disability in the region will guide policies directed at care allotment, improvement in the provision of interventions for migraine, as well as enhancement of health-related quality of life for patients with migraine in our region.

Breakthrough Hemolysis Associated With COVID-19 Vaccination and Active COVID-19 Infection in a Patient With Paroxysmal Nocturnal Hemoglobinuria Maintained on Pegcetacoplan: A Case Report.

Breakthrough hemolysis (BTH) is the return of hemolytic disease resulting in an overall increase in complement activation in a patient being treated for paroxysmal nocturnal hemoglobinuria (PNH) with complement inhibitors (CI). BTH after COVID-19 vaccination has only been reported in PNH patients treated with the traditional C5 CI eculizumab and ravulizumab. We report on a new association of BTH in a newly COVID-19 vaccinated, previously stable PNH patient treated with pegcetacoplan, a C3 CI. The patient is a 29-year-old female diagnosed with PNH in 2017 and was started on eculizumab but was switched to pegcetacoplan in 2021 after continuing to exhibit symptomatic hemolysis. Subsequently, the patient returned to PNH remission serologically and symptomatically until her first COVID-19 vaccination. Since then, her lactate dehydrogenase (LDH) and hemoglobin counts have not fully returned to previous baseline levels, with significant exacerbations after her second COVID-19 vaccine and de novo COVID-19 infection. As of May 2022, the patient requires packed red blood cell transfusions every two to three months and has undergone a bone marrow transplant evaluation. This case study suggests that the administration of the upstream C3 CI, pegcetacoplan, is associated with active extravascular hemolysis in the setting of COVID-19 vaccinations and active COVID-19 infection. The pathophysiology of this hemolysis is unclear as hemolysis could be related to the underlying complement factor deficiency or amplification of complement factors causing extravascular hemolysis. There are conflicting reports in the literature regarding the mechanism by which COVID-19 vaccination and infection cause BTH in PNH patients, regardless of the choice of CI treatment. Bringing awareness to this case of BTH secondary to COVID-19 in a PNH patient treated with pegcetacoplan can further warrant the investigation of the role of COVID-19 in complement disruption and its role in BTH.

Diagnostic accuracy of computed tomography in adults with suspected acute appendicitis at the emergency department in a private tertiary hospital in Tanzania.

INTRODUCTION: The increasing incidence of acute appendicitis in sub-Saharan Africa emphasizes the need for accurate and reliable diagnostic tools. However, the variability in the diagnostic performance of computed tomography for suspected acute appendicitis coupled with comparatively higher negative appendectomy rates in this setting highlight a possible concern regarding the diagnostic accuracy. This study evaluated the diagnostic accuracy of a computed tomography scan for suspected acute appendicitis at the emergency department in Tanzania. METHODS: A retrospective diagnostic accuracy study was conducted from July to October 2020. All patients above 14 years of age who presented at the emergency department with right iliac fossa abdominal pain of fewer than ten days and underwent computed tomography for suspected acute appendicitis were evaluated, and the Alvarado score was computed. Histological diagnosis and clinical follow-up of 14 days were considered the reference standard. Ethical clearance was sought from the Aga Khan University Ethical review committee. RESULTS: 176 patients were included in this study. The sensitivity, specificity, and diagnostic accuracy were 100% (95% CI 91.8-100), 96.9% (95% CI 92.2-99.1), and 96.9% (95% CI 93.1-98.3), respectively. The mean Alvarado score in those without acute appendicitis was 4 (95% CI 3.7-4.3) compared to a mean score of 6.6 (95% CI 6.0-7.2) amongst those with acute appendicitis. The area under the receiver operator characteristics curve of computed tomography was 98.4%, and that of the Alvarado score was 84.1%. CONCLUSIONS: The diagnostic performance of computed tomography in this study is similar to that established elsewhere. However, the Alvarado score is not routinely used for the initial screening of suspected acute appendicitis patients. A threshold of Alvarado score of 4 as a guide to conduct computed tomography for suspected acute appendicitis would have decreased computed tomography use by 50%, and missed 4 cases. Implementation studies that address Alvarado score use should be conducted.

Mechanosensitive pathways are regulated by mechanosensitive miRNA clusters in endothelial cells.

Shear stress is known to affect many processes in (patho-) physiology through a complex, multi-molecular mechanism, termed mechanotransduction. The sheer complexity of the process has raised questions how mechanotransduction is regulated. Here, we comprehensively evaluate the literature about the role of small non-coding miRNA in the regulation of mechanotransduction. Regulation of mRNA by miRNA is rather complex, depending not only on the concentration of mRNA to miRNA, but also on the amount of mRNA competing for a single mRNA. The only mechanism to counteract the latter factor is through overarching structures of miRNA. Indeed, two overarching structures are present miRNA families and miRNA clusters, and both will be discussed in details, regarding the latest literature and a previous conducted study focussed on mechanotransduction. Both the literature and our own data support a new hypothesis that miRNA-clusters predominantly regulate mechanotransduction, affecting 65% of signalling pathways. In conclusion, a new and important mode of regulation of mechanotransduction is proposed, based on miRNA clusters. This finding implicates new avenues for treatment of mechanotransduction and atherosclerosis.

Considerations for analysis of endothelial shear stress and strain in FSI models of atherosclerosis.

Atherosclerosis is a lipid driven chronic inflammatory disease that is characterized by the formation of plaques at predilection sites. These predilection sites (side branches, curved segments, and bifurcations) have often been associated with disturbed shear stress profiles. However, in addition to shear stress, endothelial cells also experience artery wall strain that could contribute to atherosclerosis progression. Herein, we describe a method to accurately obtain these shear stress and strain profiles. We developed a fluid-structure interaction (FSI) framework for modelling arteries within a commercially available package (Abaqus, version 6.14) that included known prestresses (circumferential, axial and pressure associated). In addition, we co-registered 3D histology to a micro-CT-derived 3D reconstruction of an atherosclerotic carotid artery from a cholesterol-fed ApoE-/- mouse to include the spatial distribution of lipids within a subject-specific model. The FSI model also incorporated a nonlinear hyperelastic material model with regionally-varying properties that distinguished between healthy vessel wall and plaque. FSI predicted a lower shear stress than CFD (~-12%), but further decreases in plaque regions with softer properties (~-24%) were dependent on the approach used to implement the prestresses in the artery wall. When implemented with our new hybrid approach (zero prestresses in regions of lipid deposition), there was significant heterogeneity in endothelial shear stress in the atherosclerotic artery due to variations in stiffness and, in turn, wall strain. In conclusion, when obtaining endothelial shear stress and strain in diseased arteries, a careful consideration of prestresses is necessary. This paper offers a way to implement them.

Nivolumab and Ipilimumab as Maintenance Therapy in Extensive-Disease Small-Cell Lung Cancer: CheckMate 451.

PURPOSE: In extensive-disease small-cell lung cancer (ED-SCLC), response rates to first-line platinum-based chemotherapy are robust, but responses lack durability. CheckMate 451, a double-blind phase III trial, evaluated nivolumab plus ipilimumab and nivolumab monotherapy as maintenance therapy following first-line chemotherapy for ED-SCLC. METHODS: Patients with ED-SCLC, Eastern Cooperative Oncology Group performance status 0-1, and no progression after ≤ 4 cycles of first-line chemotherapy were randomly assigned (1:1:1) to nivolumab 1 mg/kg plus ipilimumab 3 mg/kg once every 3 weeks for 12 weeks followed by nivolumab 240 mg once every 2 weeks, nivolumab 240 mg once every 2 weeks, or placebo for ≤ 2 years or until progression or unacceptable toxicity. Primary end point was overall survival (OS) with nivolumab plus ipilimumab versus placebo. Secondary end points were hierarchically tested. RESULTS: Overall, 834 patients were randomly assigned. The minimum follow-up was 8.9 months. OS was not significantly prolonged with nivolumab plus ipilimumab versus placebo (hazard ratio [HR], 0.92; 95% CI, 0.75 to 1.12; P = .37; median, 9.2 v 9.6 months). The HR for OS with nivolumab versus placebo was 0.84 (95% CI, 0.69 to 1.02); the median OS for nivolumab was 10.4 months. Progression-free survival HRs versus placebo were 0.72 for nivolumab plus ipilimumab (95% CI, 0.60 to 0.87) and 0.67 for nivolumab (95% CI, 0.56 to 0.81). A trend toward OS benefit with nivolumab plus ipilimumab was observed in patients with tumor mutational burden ≥ 13 mutations per megabase. Rates of grade 3-4 treatment-related adverse events were nivolumab plus ipilimumab (52.2%), nivolumab (11.5%), and placebo (8.4%). CONCLUSION: Maintenance therapy with nivolumab plus ipilimumab did not prolong OS for patients with ED-SCLC who did not progress on first-line chemotherapy. There were no new safety signals.

A missing piece: Fracture of peripheral intravenous cannula, a case report.

INTRODUCTION AND IMPORTANCE: Peripheral venous cannulation is the most common procedure, often performed by junior colleagues. Despite its benign nature, it is associated with extravascular infiltration, thrombophlebitis, hematoma, catheter-associated bloodstream infections, trauma to surrounding structures, including tendon and nerve injures, hematoma formation and air embolism. Fracture of a peripheral intravenous cannula in situ is a rare, potentially serious complication that is underreported. More importantly, the etiology and prevention of this complication are not widely known by those performing cannulation. This case report will increase awareness and knowledge on intravenous peripheral cannula fracture to improve peripheral intravenous cannulation safety. CASE PRESENTATION: In this case report, we describe a fracture of a size 18 G plastic peripheral intravenous cannula (Neovac-Neomedic) in situ in a 76-year-old hypertensive male managed at Aga Khan Hospital Dar es salaam, Tanzania. The cannula's fracture was noticed 24 h later during the cannula's removal, where a fragment of the cannula was noted, and a palpable cord-like structure was appreciated along the cubital fossa. Ultrasound was done to localize the distal segment, confirming a cannula fracture with the distal fragment's retention. Surgical exploration under local anesthetic was necessary, retrieving the fragment. There were no intra-operatively or post-operative complications encountered. Proximal migration of the segment risks the chances of developing sepsis, dysrhythmia, and myocardial infarction, but this did not occur in our case. CLINICAL DISCUSSION: Reinsertion of the guide needle into the plastic sheath in situ most probably caused the fracture. Additional healthcare costs are incurred for investigation, admission, and surgical procedures. The patient experience may be affected by this complication. CONCLUSION: Understanding the guide needle's reinsertion may result in cannula fracture, allows safer cannulation practices by the clinician and adequate counseling of the patient before the procedure.

Inadvertent Stone Migration During Pneumatic Lithotripsy: Still a Conundrum in the 21st Century.

Currently, an ideal gadget to stop retrograde stone migration remains a holy grail, and the hunt for such a device is still ongoing in the 21st century. The quest for an ideal instrument is driven by the need to reduce cost, minimize ancillary procedure rates, reduce the device's operative time, and improve the stone-free rate. The purpose of the present review is to provide an update on the use of preventive measures that are used to stop retrograde stone migration during pneumatic lithotripsy for ureteric stone management.

Disturbed Cyclical Stretch of Endothelial Cells Promotes Nuclear Expression of the Pro-Atherogenic Transcription Factor NF-κB.

Exposure of endothelial cells to low and multidirectional blood flow is known to promote a pro-atherogenic phenotype. The mechanics of the vessel wall is another important mechano-stimulus within the endothelial cell environment, but no study has examined whether changes in the magnitude and direction of cell stretch can be pro-atherogenic. Herein, we developed a custom cell stretching device to replicate the in vivo stretch environment of the endothelial cell and examined whether low and multidirectional stretch promote nuclear translocation of NF-κB. A fluid-structure interaction model of the device demonstrated a nearly uniform strain within the region of cell attachment and a negligible magnitude of shear stress due to cyclical stretching of the cells in media. Compared to normal cyclical stretch, a low magnitude of cyclical stretch or no stretch caused increased expression of nuclear NF-κB (p = 0.09 and p < 0.001, respectively). Multidirectional stretch also promoted significant nuclear NF-κB expression, comparable to the no stretch condition, which was statistically higher than the low (p < 0.001) and normal (p < 0.001) stretch conditions. This is the first study to show that stretch conditions analogous to atherogenic blood flow profiles can similarly promote a pro-atherogenic endothelial cell phenotype, which supports a role for disturbed vessel wall mechanics as a pathological cell stimulus in the development of advanced atherosclerotic plaques.

A CRISPR Dropout Screen Identifies Genetic Vulnerabilities and Therapeutic Targets in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is an aggressive cancer with a poor prognosis, for which mainstream treatments have not changed for decades. To identify additional therapeutic targets in AML, we optimize a genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screening platform and use it to identify genetic vulnerabilities in AML cells. We identify 492 AML-specific cell-essential genes, including several established therapeutic targets such as DOT1L, BCL2, and MEN1, and many other genes including clinically actionable candidates. We validate selected genes using genetic and pharmacological inhibition, and chose KAT2A as a candidate for downstream study. KAT2A inhibition demonstrated anti-AML activity by inducing myeloid differentiation and apoptosis, and suppressed the growth of primary human AMLs of diverse genotypes while sparing normal hemopoietic stem-progenitor cells. Our results propose that KAT2A inhibition should be investigated as a therapeutic strategy in AML and provide a large number of genetic vulnerabilities of this leukemia that can be pursued in downstream studies.

ALDH1A1 and ALDH3A1 expression in lung cancers: correlation with histologic type and potential precursors.

We hypothesize that aldehyde dehydrogenase (ALDH) isozymes may be upregulated in lung tissue as a result of exposure to carcinogenic aldehydes found in cigarette smoke. To investigate this hypothesis, we studied the expression of two ALDH isozymes in lung cancer from patient samples and its relationship to the history of cigarette smoking. Immunohistochemical staining for ALDH1A1 and ALDH3A1 was performed on archival specimens from control patients without lung cancer, and patients with one of the primary lung cancers: squamous cell cancer (SCCA), adenocarcinoma (AdenoCA), and small cell lung cancer (SCLC). An overall score was obtained for each sample based upon multiplying the staining intensity (0-3) and the extensiveness (0-100%). Mean+/-S.E.M. for each experimental group was calculated and compared. Our results indicate a significantly higher level of expression of ALDH1A1 and ALDH3A1 in SCCA (155+/-19 and 162+/-17, respectively) and AdenoCA (116+/-12 and 107+/-10) than SCLC (39+/-11 and 42+/-12) (P<0.01). Atypical pneumocytes demonstrated significantly higher levels of expression of ALDH1A1 and ALDH3A1 than normal pneumocytes (a normal counterpart of AdenoCA), which is suggestive of up regulation during malignant transformation to AdenoCA. A subset analysis of all samples studied revealed increased expression of ALDH1A1 (P=0.055) and ALDH3A1 (P=0.0093) in normal pneumocytes of smokers (n=32) in comparison to those of non-smokers (n=17). Non-small cell lung cancer (NSCLC) express very high levels of ALDH1A1 and ALDH3A1 in comparison with SCLC, elevated expression of both enzymes may be associated with malignant transformation to AdenoCA, and cigarette smoking seems to result in increased expression of these enzymes in normal pneumocytes.