A new protein modification strategy has been developed that is based on an oxidative coupling reaction that targets electron-rich amino acids. This strategy relies on cerium(IV) ammonium nitrate ...(CAN) as an oxidation reagent and results in the coupling of tyrosine and tryptophan residues to phenylene diamine and anisidine derivatives. The methodology was first identified and characterized on peptides and small molecules, and was subsequently adapted for protein modification by determining appropriate buffer conditions. Using the optimized procedure, native and introduced solvent-accessible residues on proteins were selectively modified with polyethylene glycol (PEG) and small peptides. This unprecedented bioconjugation strategy targets these under-utilized amino acids with excellent chemoselectivity and affords good-to-high yields using low concentrations of the oxidant and coupling partners, short reaction times, and mild conditions.
The human gut microbiota plays a key role in pharmacology, yet the mechanisms responsible remain unclear, impeding efforts toward personalized medicine. We recently identified a cytochrome-encoding ...operon in the common gut Actinobacterium Eggerthella lenta that is transcriptionally activated by the cardiac drug digoxin. These genes represent a predictive microbial biomarker for the inactivation of digoxin. Gnotobiotic mouse experiments revealed that increased protein intake can limit microbial drug inactivation. Here, we present a biochemical rationale for how the proteins encoded by this operon might inactivate digoxin through substrate promiscuity. We discuss digoxin signaling in eukaryotic systems, and consider the possibility that endogenous digoxin-like molecules may have selected for microbial digoxin inactivation. Finally, we highlight the diverse contributions of gut microbes to drug metabolism, present a generalized approach to studying microbe-drug interactions, and argue that mechanistic studies will pave the way for the clinical application of this work.
Homology Directed Repair (HDR) enables precise genome editing, but the implementation of HDR-based therapies is hindered by limited efficiency in comparison to methods that exploit alternative DNA ...repair routes, such as Non-Homologous End Joining (NHEJ). In this study, we develop a functional, pooled screening platform to identify protein-based reagents that improve HDR in human hematopoietic stem and progenitor cells (HSPCs). We leverage this screening platform to explore sequence diversity at the binding interface of the NHEJ inhibitor i53 and its target, 53BP1, identifying optimized variants that enable new intermolecular bonds and robustly increase HDR. We show that these variants specifically reduce insertion-deletion outcomes without increasing off-target editing, synergize with a DNAPK inhibitor molecule, and can be applied at manufacturing scale to increase the fraction of cells bearing repaired alleles. This screening platform can enable the discovery of future gene editing reagents that improve HDR outcomes.
In MRI, anatomical structures are most often differentiated by variations in their bulk magnetic properties. Alternatively, exogenous contrast agents can be attached to chemical moieties that confer ...affinity to molecular targets; the distribution of such contrast agents can be imaged by magnetic resonance. Xenon-based molecular sensors are molecular imaging agents that rely on the reversible exchange of hyperpolarized xenon between the bulk and a specifically targeted host−guest complex. We have incorporated ∼125 xenon sensor molecules in the interior of an MS2 viral capsid, conferring multivalency and other properties of the viral capsid to the sensor molecule. The resulting signal amplification facilitates the detection of sensor at 0.7 pM, the lowest to date for any molecular imaging agent used in magnetic resonance. This amplification promises the detection of chemical targets at much lower concentrations than would be possible without the capsid scaffold.
To determine the feasibility of training otolaryngologists to perform head and neck ultrasound in low- and middle-income countries over a short timeframe.
Prospective cohort evaluating an ultrasound ...training course for otolaryngologists in low- and middle-income countries.
Surgical training camp for otolaryngologists in semirural Kenya.
Participants were prospectively recruited to participate in an ultrasound training course during a 2-week surgical training camp. They performed baseline ultrasound exams (9-item test, 5-point scale) with no assistance, followed by didactic sessions teaching ultrasound techniques. Participating surgeons then performed head and neck ultrasound exams on patients in clinic or in the operating room with direct supervision. Postcourse ultrasounds were performed, and the results of these tests were compared to baseline exams.
Eight surgeons were enrolled out of a total of 13 (62%). Three were attending surgeons (37.5%), 1 enrollee was a head and neck surgery fellow, and 4 were senior residents (50%). Six of 8 surgeons were from Kenya. The mean precourse test score was 25 (range 21-30) compared to a mean postcourse test score of 40 (range 37-45, p < 0.005). All participants significantly improved their scores, with a mean improvement of 16 points (range 10-23).
Otolaryngologists are uniquely equipped to learn head and neck ultrasound given their familiarity with the anatomy and pathology in this region. Training physicians without prior experience can be done even over short timeframes. Early training should focus on ultrasound, with later stages of training focusing on pathology.
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