Successful Percutaneous Retrieval of an Embolized Left Atrial Appendage Occluder

A 75-year-old man with a previous mitral valve repair experienced embolization of a left atrial appendage occlusion device in the left atrium. The device was successfully retrieved using a double snaring technique, without the need for open surgery. This is an unusual report of left atrial appendage occluder retrieval, confirming the feasibility of the technique and the high flexibility of the device. (Level of Difficulty: Advanced.

A highly selective electrochemical assay based on the Sakaguchi reaction for the detection of protein arginine methylation state

Protein arginine methylation is a common form of post-translational modification that plays an important role in many bioprocesses. However, research advances in this field have been severely hampered by the lack of a quick and sensitive method for detecting the arginine methylation state of a protein. In this work we propose a direct and sensitive electrochemical method for identifying the arginine methylation state. This novel assay combines an electrochemical technique with the Sakaguchi reaction, which is highly selective towards the arginine methylation state. We show that the presence of a methyl group on the arginine residue of a protein prevents the Sakaguchi reaction, while the unmethylated arginine residue selectively reacts with 8-hydroxyquinoline; the electrical signal of the reaction product is used for electrochemical detection. From this, a highly selective and simple electrochemical sensor has been developed based on (1) the high selectivity of the Sakaguchi reaction towards the arginine methylation state, and (2) the sensitive electrochemical signal generated by the linked 8-hydroxyquinoline. The assay described in this work thus provides a convenient tool for detection of protein arginine methylation, which may facilitate studies of the biological functions of protein arginine methylases and demethylases

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Structural investigations on orotate phosphoribosyltransferase from Mycobacterium tuberculosis, a key enzyme of the de novo pyrimidine biosynthesis

AbstractThe Mycobacterium tuberculosis orotate phosphoribosyltransferase (MtOPRT) catalyses the conversion of α-D-5-phosphoribosyl-1-pyrophosphate (PRPP) and orotate (OA) in pyrophosphate and orotidine 5′-monophosphate (OMP), in presence of Mg2+. This enzyme is the only responsible for the synthesis of orotidine 5′-monophosphate, a key precursor in the de novo pyrimidine biosynthesis pathway, making MtOPRT an attractive drug target for the development of antitubercular agents. We report the crystal structures of MtOPRT in complex with PRPP (2.25 Å resolution), inorganic phosphate (1.90 Å resolution) and the exogenous compound Fe(III) dicitrate (2.40 Å resolution). The overall structure of the mycobacterial enzyme is highly similar to those described for other OPRTases, with the “flexible loop” assuming a well define conformation and making specific contacts with the Fe(III)-dicitrate complex. The structures here reported add to the knowledge of a potential drug target for tuberculosis, and will provide a useful tool for the structure-based drug design of potent enzyme inhibitors.</jats:p

The First Italian Telemedicine Program for Non-Critical COVID-19 Patients: Experience from Lodi (Italy)

Italy was the first Western country to face a massive SARS-CoV-2 outbreak. The limited information initially available on the natural course of the disease required caution in the discharge of patients accessing health facilities. This resulted in overcrowded health facilities and emergency services. In this context, improvements of other forms of hospital care assistance were needed. This study shows the results of the first Italian remote monitoring program for COVID-19 patients. The program was implemented by the Azienda Socio Sanitaria (ASST) Lodi (Italy) by using the innovative Zcare software®. Data generated during patient recruitment, monitoring, and discharge were extracted from the Zcare software and statistically analysed. Data refer to a sample of 1196 patients enrolled in the remote monitoring program in 2020. Patients reported symptoms mainly during the first week. The most frequently reported symptoms were general fatigue, cough, and loss of taste and smell (dysosmia). More than 80% of patients reported a saturation level below 96% at least once, and more than 70% had a temperature above 37 °C. Active monitoring of reported symptoms provided valuable insights into the disease’s natural history during its less severe acute phase. Only 109 individuals visited the emergency department at least once in the first 100 days of monitoring. Of these, 101 had COVID-19 infection, 69 of whom were hospitalized following a first clinical assessment at the emergency department. The ASST Lodi’s telemedicine strategy for COVID patients appears to be a viable alternative to hospitalization. This strategy enables the provision of proper care while making resources available for more critically ill patients, and enhances the availability of resources available for more critically ill patients

Crystal structure of a thermophilic O6-alkylguanine-DNA alkyltransferase-derived self-labeling protein-tag in covalent complex with a fluorescent probe

The self-labeling protein tags are robust and versatile tools for studying different molecular aspects of cell biology. In order to be suitable for a wide spectrum of experimental conditions, it is mandatory that these systems are stable after the fluorescent labeling reaction and do not alter the properties of the fusion partner. SsOGT-H5 is an engineered variant alkylguanine-DNA-alkyl-transferase (OGT) of the hyperthermophilic archaeon Sulfolobus solfataricus, and it represents an alternative solution to the SNAP-tag\uae technology under harsh reaction conditions. Here we present the crystal structure of SsOGT-H5 in complex with the fluorescent probe SNAP-Vista Green\uae (SsOGT-H5-SVG) that reveals the conformation adopted by the protein upon the trans-alkylation reaction with the substrate, which is observed covalently bound to the catalytic cysteine residue. Moreover, we identify the amino acids that contribute to both the overall protein stability in the post-reaction state and the coordination of the fluorescent moiety stretching-out from the protein active site. We gained new insights in the conformational changes possibly occurring to the OGT proteins upon reaction with modified guanine base bearing bulky adducts; indeed, our structural analysis reveals an unprecedented conformation of the active site loop that is likely to trigger protein destabilization and consequent degradation. Interestingly, the SVG moiety plays a key role in restoring the interaction between the N- and C-terminal domains of the protein that is lost following the new conformation adopted by the active site loop in the SsOGT-H5-SVG structure. Molecular dynamics simulations provide further information into the dynamics of SsOGT-H5-SVG structure, highlighting the role of the fluorescent ligand in keeping the protein stable after the trans-alkylation reaction