Isotonitazene, a novel psychoactive substance opioid, detected in two cases following a local surge in opioid overdoses.

BACKGROUND: Isotonitazene is a novel opioid that was first reported in Europe in 2019. There have been no reports of the detection of isotonitazene in patients presenting to the emergency department with acute drug toxicity. AIM: There was an increase in presentations to our emergency department with acute opioid toxicity in August 2021. We aim to describe this outbreak and provide detail on two cases in which isotonitazene was quantified in serum samples. METHODS: Serum samples were available for comprehensive toxicological analysis for two presentations. Written consent was obtained and the samples were analysed through a Thermo XRS ultrahigh-performance liquid chromatography system, interfaced to a Thermo Q Exactive high-resolution accurate mass spectrometer, operating in heated positive ion electrospray mode. Acquired data were processed using Toxfinder software (Thermo) against a regularly updated in-house database. RESULTS: There was an increase in acute opioid presentations to our emergency department from a median of 10 per month to 36 in August 2021. Twenty were treated with naloxone, and 23 were admitted to the hospital for observation and treatment. Serum sample analysis from two patients with acute opioid toxicity responsive to naloxone detected the presence of isotonitazene (0.18 and 0.81 ng/ml). CONCLUSION: We report a cluster of acute opioid toxicity presentations to our Emergency Department with detection of isotonitazene in two cases. Analytical screening is important in determining the presence of novel psychoactive substances (NPS) and to help inform the public health of the implications of NPS use, particularly during clusters of acute recreational drug toxicity presentations.

High-affinity chromodomains engineered for improved detection of histone methylation and enhanced CRISPR-based gene repression.

Histone methylation is an important post-translational modification that plays a crucial role in regulating cellular functions, and its dysregulation is implicated in cancer and developmental defects. Therefore, systematic characterization of histone methylation is necessary to elucidate complex biological processes, identify biomarkers, and ultimately, enable drug discovery. Studying histone methylation relies on the use of antibodies, but these suffer from lot-to-lot variation, are costly, and cannot be used in live cells. Chromatin-modification reader domains are potential affinity reagents for methylated histones, but their application is limited by their modest affinities. We used phage display to identify key residues that greatly enhance the affinities of Cbx chromodomains for methylated histone marks and develop a general strategy for enhancing the affinity of chromodomains of the human Cbx protein family. Our strategy allows us to develop powerful probes for genome-wide binding analysis and live-cell imaging. Furthermore, we use optimized chromodomains to develop extremely potent CRISPR-based repressors for tailored gene silencing. Our results highlight the power of engineered chromodomains for analyzing protein interaction networks involving chromatin and represent a modular platform for efficient gene silencing.

Cross-strand histidine-aromatic interactions enhance acyl-transfer rates in beta-hairpin peptide catalysts.

A reactive tagging methodology was used to select the species most reactive to an acylation reagent from a solid phase library of beta hairpin peptides. Hits bearing an electron-rich aromatic residue across strand from a reactive histidine were found to competitively become N-acylated. In addition to displaying rapid N-acylation rates the hit peptide was additionally deacylated in the presence of a nucleophile, thus closing a putative catalytic cycle. Variants of the hit peptide were studied to elucidate both the magnitude (up to 18,000-fold over background, kcat/kuncat = 94,000,000, or 45-fold over Boc-histidine methyl ester) and mechanism of acyl transfer catalysis. A combination of CH-π, cation-π and HisH(+)-O interactions in the cationic imidazole transition state is implicated in the rate acceleration, in addition to the fidelity of the beta hairpin fold. Moreover, NMR structural data on key intermediates or models thereof suggest that a key feature of this catalyst is the ability to access several different stabilizing conformations along the catalysis reaction coordinate.

Case report: neutrophilic CSF pleocytosis in hypertensive encephalopathy.

A patient with hypertensive crisis developed encephalopathy with a lumbar puncture revealing neutrophilic pleocytosis. No explanation for her case could be found, eg, no evidence of infection or vasculitis. It is concluded that the most probable cause of her neutrophilic cerebrospinal fluid pleocytosis is hypertensive encephalopathy.