Development and implementation of an ultralow-dose CT protocol for the assessment of cerebrospinal shunts in adult hydrocephalus

Background: Cerebrospinal fluid shunts in the treatment of hydrocephalus, although associated with clinical benefit, have a high failure rate with repeat computed tomography (CT) imaging resulting in a substantial cumulative radiation dose. Therefore, we sought to develop a whole-body ultralow-dose (ULD) CT protocol for the investigation of shunt malfunction and compare it with the reference standard, plain radiographic shunt series (PRSS). Methods: Following ethical approval, using an anthropomorphic phantom and a human cadaveric ventriculoperitoneal shunt model, a whole-body ULD-CT protocol incorporating two iterative reconstruction (IR) algorithms, pure IR and hybrid IR, including 60% filtered back projection and 40% IR was evaluated in 18 adult patients post new shunt implantation or where shunt malfunction was suspected. Effective dose (ED) and image quality were analysed. Results: ULD-CT permitted a 36% radiation dose reduction (median ED 0.16 mSv, range 0.07–0.17, versus 0.25 mSv (0.06–1.69 mSv) for PRSS (p = 0.002). Shunt visualisation in the thoracoabdominal cavities was improved with ULD-CT with pure IR (p = 0.004 and p = 0.031, respectively) and, in contrast to PRSS, permitted visualisation of the entire shunt course (p < 0.001), the distal shunt entry point and location of the shunt tip in all cases. For shunt complications, ULD-CT had a perfect specificity. False positives (3/22, 13.6%) were observed with PRSS. Conclusions: At a significantly reduced radiation dose, whole body ULD-CT with pure IR demonstrated diagnostic superiority over PRSS in the evaluation of cerebrospinal fluid shunt malfunction

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Microfluidic based magnetic separator for biological applications

Macro scale magnetic separation of pure biological particles from a complex biological sample is a key technique performed in clinical and research settings. This thesis focuses on the development of a microfluidic based magnetic separator for biological applications. The work presented covers design, simulation, fabrication and testing of the magnetic separator. The magnetic separator design consists of a micron-sized channel fabricated in a biocompatible polymer, containing one inlet and three outlets. Close to the channel wall are soft permalloy elements. The external magnetic flux is provided by the permanent magnets situated on either side of the channel. Theoretical aspects of the design are discussed and special attention is paid to investigating the effects of the magnetic and fluidic forces acting within the microdevice. Fabrication of the magnetic separator was carried out in the Microsystems Engineering Centre, Heriot Watt University and at Epigem Ltd., Redcar, U.K. The manufacturing processes investigated include methods for rapid prototyping and UV-photolithography. CO2 laser ablation and powder blasting of PMMA were investigated as rapid prototyping techniques. Using UV-photolithography magnetic separators were realised in PDMS and in SU-8. Soft permalloy elements were fabricated using UV-LIGA and the correct permalloy ratio (Ni80Fe20) evaluated. Ultimately three magnetic separation systems have been successfully fabricated based on the different fabrication approaches. Magnetic separation on chip was successfully demonstrated for all three devices fabricated. Flow cytometry a highly accurate method of particle counting and analysis was used to verify the separation efficiency. Experimental testing results have shown that magnetic and non-magnetic beads can be separated with high efficiency

Targeted disruption of nonribosomal peptide synthetase Pes3 augments the virulence of Aspergillus fumigatus

Nonribosomal peptide synthesis (NRPS) is a documented virulence factor for the opportunistic pathogen Aspergillus fumigatus and other fungi. Secreted or intracellularly located NRP products include the toxic molecule gliotoxin and the iron-chelating siderophores triacetylfusarinine C and ferricrocin. No structural or immunologically relevant NRP products have been identified in the organism. We investigated the function of the largest gene in A. fumigatus, which encodes the NRP synthetase Pes3 (AFUA_5G12730), by targeted gene deletion and extensive phenotypic analysis. It was observed that in contrast to other NRP synthetases, deletion of pes3 significantly increases the virulence of A. fumigatus, whereby the pes3 deletion strain (A. fumigatus pes3) exhibited heightened virulence (increased killing) in invertebrate (P < 0.001) and increased fungal burden (P 0.008) in a corticosteroid model of murine pulmonary aspergillosis. Complementation restored the wild-type phenotype in the invertebrate model. Deletion of pes3 also resulted in increased susceptibility to the antifungal, voriconazole (P < 0.01), shorter germlings, and significantly reduced surface -glucan (P 0.0325). Extensive metabolite profiling revealed that Pes3 does not produce a secreted or intracellularly stored NRP in A. fumigatus. Macrophage infections and histological analysis of infected murine tissue indicate that Pes3 heightened virulence appears to be mediated by aberrant innate immune recognition of the fungus. Proteome alterations in A. fumigatus Pes3 strongly suggest impaired germination capacity. Uniquely, our data strongly indicate a structural role for the Pes3-encoded NRP, a finding that appears to be novel for an NRP synthetase