Insights into the Structures of Superoxide Reductases from the Symbionts Ignicoccus hospitalis and Nanoarchaeum equitans.

Superoxide reductases (SORs) are enzymes that detoxify the superoxide anion through its reduction to hydrogen peroxide and exist in both prokaryotes and eukaryotes. The substrate is transformed at an iron catalytic center, pentacoordinated in the ferrous state by four histidines and one cysteine. SORs have a highly conserved motif, (E)(K)HxP-, in which the glutamate is associated with a redox-driven structural change, completing the octahedral coordination of the iron in the ferric state, whereas the lysine may be responsible for stabilization and donation of a proton to catalytic intermediates. We aimed to understand at the structural level the role of these two residues, by determining the X-ray structures of the SORs from the hyperthermophilic archaea Ignicoccus hospitalis and Nanoarchaeum equitans that lack the quasi-conserved lysine and glutamate, respectively, but have catalytic rate constants similar to those of the canonical enzymes, as we previously demonstrated. Furthermore, we have determined the crystal structure of the E23A mutant of I. hospitalis SOR, which mimics several enzymes that lack both residues. The structures revealed distinct structural arrangements of the catalytic center that simulate several catalytic cycle intermediates, namely, the reduced and the oxidized forms, and the glutamate-free and deprotonated ferric forms. Moreover, the structure of the I. hospitalis SOR provides evidence for the presence of an alternative lysine close to the iron center in the reduced state that may be a functional substitute for the "canonical" lysine.

Superoxide reductase from Giardia intestinalis: structural characterization of the first SOR from a eukaryotic organism shows an iron centre that is highly sensitive to photoreduction.

Superoxide reductase (SOR), which is commonly found in prokaryotic organisms, affords protection from oxidative stress by reducing the superoxide anion to hydrogen peroxide. The reaction is catalyzed at the iron centre, which is highly conserved among the prokaryotic SORs structurally characterized to date. Reported here is the first structure of an SOR from a eukaryotic organism, the protozoan parasite Giardia intestinalis (GiSOR), which was solved at 2.0 Å resolution. By collecting several diffraction data sets at 100 K from the same flash-cooled protein crystal using synchrotron X-ray radiation, photoreduction of the iron centre was observed. Reduction was monitored using an online UV-visible microspectrophotometer, following the decay of the 647 nm absorption band characteristic of the iron site in the glutamate-bound, oxidized state. Similarly to other 1Fe-SORs structurally characterized to date, the enzyme displays a tetrameric quaternary-structure arrangement. As a distinctive feature, the N-terminal loop of the protein, containing the characteristic EKHxP motif, revealed an unusually high flexibility regardless of the iron redox state. At variance with previous evidence collected by X-ray crystallography and Fourier transform infrared spectroscopy of prokaryotic SORs, iron reduction did not lead to dissociation of glutamate from the catalytic metal or other structural changes; however, the glutamate ligand underwent X-ray-induced chemical changes, revealing high sensitivity of the GiSOR active site to X-ray radiation damage.

Peritoneal Carcinomatosis: When Everything Is Not What It Seems.

Malignant peritoneal mesothelioma (MPM) is a rare neoplasm with a low incidence rate worldwide but high morbidity and mortality rates. Due to its rarity, the studies are scarce. We present a case of a 73-year-old woman admitted to the internal medicine unit with constitutional syndrome, abdominal pain, and ascites. Throughout the investigation, aspects suggestive of peritoneal carcinomatosis were identified. An extensive study was then carried out in an attempt to identify the primary tumor, which proved to be unsuccessful. During the two weeks of hospitalization, the patient's clinical condition worsened, with an increase in ascites and a deterioration in her general health. This case was then discussed with an oncology consultant, and it was decided to biopsy a peritoneal implant with the support of interventional radiology. MPM was then diagnosed through histopathology. With this case, the authors intend to highlight that, although rare, this diagnosis should be considered when appropriate and that even in the suspicion of secondary disease, the primary tumor should always be identified, as localized MPM may be curable.

Allopurinol-Induced Toxic Epidermal Necrolysis.

Toxic epidermal necrolysis (TEN) is a rare and life-threatening cutaneous disease, frequently triggered by drugs. Allopurinol is one of the most frequent drugs associated with TEN, which implies detachment of a significant amount of the body surface area (BSA) and has a high morbidity and mortality associated with it. We present the case of a 68-year-old female with a recent diagnosis of hyperuricemia who started treatment with allopurinol. A week later, she presented to the emergency department with an extensive maculopapular exanthema with blisters and skin detachment. After the exclusion of other etiologies, the diagnosis of allopurinol-induced TEN was made, with 35% of BSA involvement. Due to the severity of the clinical condition, she was admitted to intensive care and treated with corticoids that had no response. So, she was started on immunoglobulins and transferred to a burn unit. She developed sepsis with multiorgan failure and required supportive treatment. She was discharged after a month, and physical rehabilitation was needed. This clinical case highlights the severity of allopurinol hypersensitivity that may happen and the importance of an accurate diagnosis and treatment for this rare disease.

Marine-origin polysaccharides-based free-standing multilayered membranes as sustainable nanoreservoirs for controlled drug delivery.

The layer-by-layer (LbL) assembly technology has been widely used to functionalise surfaces and precisely engineer robust multilayered bioarchitectures with tunable structures, compositions, properties, and functions at the nanoscale by resorting to a myriad of building blocks exhibiting complementary interactions. Among them, marine-origin polysaccharides are a sustainable renewable resource for the fabrication of nanostructured biomaterials for biomedical applications owing to their wide bioavailability, biocompatibility, biodegradability, non-cytotoxicity, and non-immunogenic properties. Chitosan (CHT) and alginate (ALG) have been widely employed as LbL ingredients to shape a wide repertoire of size- and shape-tunable electrostatic-driven multilayered assemblies by exploring their opposite charge nature. However, the insolubility of CHT in physiological conditions intrinsically limits the range of bioapplications of the as-developed CHT-based LbL structures. Herein, we report the preparation of free-standing (FS) multilayered membranes made of water-soluble quaternised CHT and ALG biopolymers for controlled release of model drug molecules. The influence of the film structure in the drug release rate is studied by assembling two distinct set-ups of FS membranes, having the model hydrophilic drug fluorescein isothiocyanate-labelled bovine serum albumin (FITC-BSA) either as an intrinsic building block or added as an outer layer after the LbL assembly process. Both FS membranes are characterised for their thickness, morphology, in vitro cytocompatibility, and release profile, with those having FITC-BSA as an intrinsic LbL ingredient denoting a more sustained release rate. This work opens up new avenues for the design and development of a wide array of CHT-based devices for biomedical applications, overcoming the limitations associated with the insolubility of native CHT under physiological conditions.

Androgenic-Anabolic Steroids: From the Gym to Drug-Induced Liver Injury.

Drug-induced liver injury (DILI) is a frequent cause of liver toxicity. We describe the case of a 32-year-old male patient without any relevant past medical history or medication use. In the past two months, he was engaged in weightlifting exercises and consumed androgenic-anabolic steroids to enhance his exercise routine. The patient initially experienced choluria and acholia for two weeks, followed by itching for two days, which led him to present to the emergency room. His laboratory results revealed cytocholestasis. He was admitted for investigations and after excluding other causes of liver injury, the diagnosis of DILI related to the consumption of androgenic-anabolic steroids was made. This case report highlights the perils of using performance-enhancing substances such as androgenic-anabolic steroids, which may lead to severe side effects like DILI.

Bioinstructive Layer-by-Layer-Coated Customizable 3D Printed Perfusable Microchannels Embedded in Photocrosslinkable Hydrogels for Vascular Tissue Engineering.

The development of complex and large 3D vascularized tissue constructs remains the major goal of tissue engineering and regenerative medicine (TERM). To date, several strategies have been proposed to build functional and perfusable vascular networks in 3D tissue-engineered constructs to ensure the long-term cell survival and the functionality of the assembled tissues after implantation. However, none of them have been entirely successful in attaining a fully functional vascular network. Herein, we report an alternative approach to bioengineer 3D vascularized constructs by embedding bioinstructive 3D multilayered microchannels, developed by combining 3D printing with the layer-by-layer (LbL) assembly technology, in photopolymerizable hydrogels. Alginate (ALG) was chosen as the ink to produce customizable 3D sacrificial microstructures owing to its biocompatibility and structural similarity to the extracellular matrices of native tissues. ALG structures were further LbL coated with bioinstructive chitosan and arginine-glycine-aspartic acid-coupled ALG multilayers, embedded in shear-thinning photocrosslinkable xanthan gum hydrogels and exposed to a calcium-chelating solution to form perfusable multilayered microchannels, mimicking the biological barriers, such as the basement membrane, in which the endothelial cells were seeded, denoting an enhanced cell adhesion. The 3D constructs hold great promise for engineering a wide array of large-scale 3D vascularized tissue constructs for modular TERM strategies.

Intramyocardial dissecting haematoma: a rare complication of acute myocardial infarction.

Intramyocardial dissecting haematoma (IDH) is a rare complication of myocardial infarction, with very scarce reports in medical literature. Before the advent of non-invasive imaging techniques, the diagnosis of IDH was only made by necropsy. It can develop in the left ventricular free wall, the right ventricle, or the interventricular septum. We present a case of a patient with an IDH after acute anterolateral myocardial infarction, focusing on the utility of echocardiography in the diagnosis and follow-up of this unusual complication. By this imaging modality, it was possible to see the various acoustic densities of the progressive clotting of the intramyocardial haematoma, its extension through the haemorrhagic dissection, as well as its independency in relation to ventricular cavities and extracardiac space by confirming intact epicardial and endocardial layers. Based on this report, we believe that serial two-dimensional echocardiography, added, when necessary, by the use of contrast agents is the non-invasive method ideally suited to confirm the diagnosis and monitor its evolution at the patient's bedside.

Spontaneous pneumothorax: a 5-year experience.

BACKGROUND: Spontaneous pneumothorax (SP) is defined by the presence of air in the pleural space without history of trauma. It is classified as secondary if coexisting with underlying pulmonary disease. Its an entity with considerable incidence and treatment particularities which give reason for a reflection on the subject. We present a 5-year casuistry, characterizing the SP epidemiology, clinical presentation, investigation and therapeutic choices. METHODS: Sixty-six patients were included in the study, corresponding to 93 episodes of SP. RESULTS: We have found male predominance and the mean age was 34.5 years old. In 60.6% of cases there was history of tobacco use; 36.4% of cases were classified as secondary; 30.1% of patients with secondary SP and 21.7% with primary SP recurred; 89.2% had an acute presentation. The most frequent initial symptom was chest pain (90.3%) and 81.7% had diminished breath sounds. In 17.3% it was documented a physical strain associated. We did not identify statistically significant association between the SP occurrence and the variation of the atmospheric pressure, on the first day of symptoms. In 12.9% of episodes the initial treatment option was observation. In most of the episodes the lung totally expanded. However, in 29.1% of the episodes surgical treatment was needed. CONCLUSIONS: Our results are similar to the literature. Some clinical records are incomplete, demanding the implementation of rules to improve knowledge about this matter. KEYWORDS: Spontaneous pneumothorax; Primary spontaneous pneumothorax; Secondary spontaneous pneumothorax; Epidemiology.

Risk factors for readmission after hospital discharge in chronic obstructive pulmonary disease. The role of quality of life indicators.

AIMS: To identify demographic, clinical, functional and inherent quality of life (QOL) and depression factors with impact on use of the Emergency Services (ES) or readmission after hospital discharge for acute exacerbation of chronic obstructive pulmonary disease (COPD) over a period of 66 weeks. QOL was evaluated by the St. George's Respiratory Questionnaire (SGRQ). The Beck Depression Inventory assessed depression. We prospectively evaluated 45 patients (84.4% male, median age 73 years, stage IV 51%). The median total SGRQ score was 50.6, with a greater impact on symptoms, especially in younger patients (r=-0.425; p=0.043), and activity limitation than emotional impact of the disease. More than half were depressed. Worse QOL meant depression (R=0.699; p=0.02). Low FEV1 correlated with depression (r=-0.46; p =0.05) but not with QOL. Long-acting anti-cholinergic bronchodilator and inhaled steroids improved QOL. Almost 85% of patients used ES (25.8% for exacerbated COPD). Rate of hospital readmission for all reasons and exacerbated COPD was 64.9% and 33.3%. The number of readmissions (all reasons) was correlated with age (R=0.48; p=0003), cor pulmonale (R=-0.46; p=0.03) and QOL (R=0.67; p=0.004). Depressed patients (R=0.51; p=004), with low FEV1 (R=-0413; p=0.04) and with cor pulmonale (R=-046, p=0.005) had more inhospital days for exacerbation of COPD. QOL and depression are variables to consider in the evaluation and treatment of patients with COPD as part of a set of clinical and functional data that can predict the risk of readmission after hospital discharge for exacerbated COPD.