Detection of methaemoglobinaemia in a COVID-19 patient on dapsone.

Methaemoglobinaemia occurs when iron in haemoglobin is oxidised into a form that cannot transport oxygen. At low levels, it is asymptomatic, though at rising levels symptoms arise from impaired oxygenation, and it can ultimately be fatal. While uncommon, it is important to consider in hypoxaemic COVID-19 patients, especially if they are not clinically improving on standard treatments and workup for other causes does not explain the ongoing hypoxaemia. It is often diagnosed through a mismatch in peripheral and arterial oxygen, with the former typically less than the latter. We present the case of a COVID-19 patient who was found to have methaemoglobinaemia due to dapsone use for Pneumocystic jirovecii pneumonia (PJP) prophylaxis while on chemotherapy. Dapsone was stopped and supplemental high-flow nasal cannula was provided, and methaemoglobin levels improved over a 5-day period. She was discharged to follow-up with her haematologist in the clinic.

Epithelioid Hemangioendothelioma Presenting as Necrotizing Pneumonia.

Epithelioid hemangioendothelioma (EHE) is a very rare vascular neoplasm that is often asymptomatic. A 40-year-old woman presented to the emergency department for evaluation of a nonproductive cough, chest pain, and dyspnea. A chest computed tomography angiography (CTA) demonstrated necrotizing pneumonia, a loculated left-sided pleural effusion, and an acute pulmonary embolus. She was started on broad-spectrum intravenous antibiotics and heparin infusions, and a chest tube was placed. After minimal improvement in her pleural effusion following instillation of fibrinolytics, she underwent video-assisted thoracoscopic surgery with decortication, and a pleural biopsy was performed. Her presenting symptoms resolved shortly thereafter. Following discharge, surgical pathology resulted in a diagnosis of EHE. She was not a candidate for surgical resection and remained under surveillance. A year later, she was found to have metastatic disease, and radiotherapy was initiated. Our case, which presented as necrotizing pneumonia associated with pulmonary EHE, highlights the challenges in diagnosing this disease given its extreme rarity and discusses its management.

Rupture of a de novo dural AV fistula following adult cerebral AVM resection.

Acquired unruptured dural arteriovenous fistulas (DAVFs) have been described; however, ruptured de novo DAVFs remain exceedingly rare. We describe the case of a man in his 40s who presented with a recurrent intraparenchymal haemorrhage several years after angiographic cure of an intracranial arteriovenous malformation (AVM). Repeat angiography identified a new Cognard type IV DAVF anterior to the prior craniotomy. He underwent preoperative embolisation followed by craniotomy to completely obliterate the fistulous point. This case illustrates the need for close monitoring of AVM patients, even after complete obliteration, as local recrudescence of arteriovenous shunting can occur even in adulthood.

Direct Synthetic Control over the Size, Composition, and Photocatalytic Activity of Octahedral Copper Oxide Materials: Correlation Between Surface Structure and Catalytic Functionality.

We report a synthetic approach to form octahedral Cu2O microcrystals with a tunable edge length and demonstrate their use as catalysts for the photodegradation of aromatic organic compounds. In this particular study, the effects of the Cu(2+) and reductant concentrations and stoichiometric ratios were carefully examined to identify their roles in controlling the final material composition and size under sustainable reaction conditions. Varying the ratio and concentrations of Cu(2+) and reductant added during the synthesis determined the final morphology and composition of the structures. Octahedral particles were prepared at selected Cu(2+):glucose ratios that demonstrated a range of photocatalytic reactivity. The results indicate that material composition, surface area, and substrate charge effects play important roles in controlling the overall reaction rate. In addition, analysis of the post-reacted materials revealed photocorrosion was inhibited and that surface etching had preferentially occurred at the particle edges during the reaction, suggesting that the reaction predominately occurred at these interfaces. Such results advance the understanding of how size and composition affect the surface interface and catalytic functionality of materials.