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• NMR spectroscopy is used to characterize reactivity in bromoacetyl-dPRP. • Reaction with 2-mercapto imidazole provides proton NMR assignments in BrAc-dPRP. • Bromine loss from BrAc-dPRP before conjugation can be monitored using NMR. PedvaxHIB® is a highly purified capsular polysaccharide (polyribosylribitol phosphate or PRP) of Haemophilus influenzae type b (Hib) that is covalently linked to an outer membrane protein complex (OMPC) of Neisseria meningitidis pediatric vaccine. This Hib protein conjugate vaccine is very effective in protecting infants from invasive gram-negative bacterium Hib. Before conjugation of PRP to OMPC, PRP is first derivatized with butadiamine and bromoacetyl group which reacts with thiolated OMPC. This report describes an NMR method to analyze the reactivity of bromoacetyl group in derivatized PRP (BrAc-derivatized PRP) toward small molecule thiol group, 2-mercapto imidazole (MI) which is used as a surrogate for thiolated OMPC. Reaction with MI helped identify observable amide protons in BrAc-derivatized PRP according to presence or absence of bromine. Furthermore, the new method can be used to monitor the percent of bromoacetylation during manufacturing and potentially a stability indicating assay for loss of bromine in BrAc-derivatized PRP. [ABSTRACT FROM AUTHOR]

Conjugation with polyethylene glycol (PEG) is a strategy for improving the pharmaceutical properties of therapeutic proteins. In nonclinical studies of PEGylated compounds, microscopic tissue vacuolation is often observed, characterized ultrastructurally in this report by lysosomal distension. Although PEGylation-associated vacuolation appears to be of limited toxicologic concern when alternative therapies are limited, the risk-benefit considerations may be impacted by uncertainty about reversibility, lack of methods for monitoring PEG accumulation in vivo without biopsy, and the variability in tissues affected depending on species studied. We demonstrate the use of magnetic resonance spectroscopy (MRS) to measure PEG concentrations at multiple time points in vivo in the kidney with comparison to PEG concentrations ex vivo in body fluids and tissue extracts using nuclear magnetic resonance (NMR) spectroscopy. Furthermore, we demonstrate the use of these techniques to study distribution and elimination of PEG in a dog model of PEGylation-associated vacuolation. This report suggests that MRS could be further investigated as a feasible imaging-based method for monitoring PEG accumulation in a clinical setting in conjunction with NMR quantitation of PEG in plasma and urine. [ABSTRACT FROM AUTHOR]

Indoleamine-2,3-dioxygenase 1 (IDO1) and tryptophan-2,3-dioxygenase 2 (TDO2) degrade tryptophan (Trp) to kynurenine (Kyn), and these enzymes have promise as therapeutic targets. A comprehensive characterization of potential safety liabilities of IDO1 and TDO2 inhibitors using knockout (KO) mice has not been assessed, nor has the dual Ido1/Tdo2 KO been reported. Here we characterized male and female mice with KOs for Ido1 , Tdo2 , and Ido1/Tdo2 and compared findings to the wild type (WT) mouse strain, evaluated for 14 days, using metabolomics, transcriptional profiling, behavioral analysis, spleen immunophenotyping, comprehensive histopathological analysis, and serum clinical chemistry. Multiple metabolomic changes were seen in KO mice. For catabolism of Trp to Kyn and anthranilic acid, both substrates were decreased in liver of Tdo2 and dual KO mice. Metabolism of Trp to serotonin and its metabolites resulted in an increase in 5-Hydroxyindole-3-acetic acid in the Tdo2 and dual KO mice. Ido1 and dual KO mice displayed a Kyn reduction in plasma but not in liver. Nicotinamide synthesis and conversion of glucose to lactic acid were not impacted. A slight decrease in serum alkaline phosphatase was seen in all KOs, and small changes in liver gene expression of genes unrelated to tryptophan metabolism were observed. Regarding other parameters, no genotype-specific changes were observed. In summary, this work shows metabolomic pathway changes for metabolites downstream of tryptophan in these KO mice, and suggests that inhibition of the IDO1 and TDO2 enzymes would be well tolerated whether inhibited individually or in combination since no safety liabilities were uncovered. • IDO1 & TDO2 degrade tryptophan to kynurenine, & these enzymes have promise as therapeutic targets. • To understand target liabilities, single & dual Ido1 & Tdo2 KO mice were thoroughly evaluated. • Tryptophan metabolite changes were seen, & other subtle findings had no toxicologic consequence. • This implies inhibition of these enzymes would be well tolerated. [ABSTRACT FROM AUTHOR]

Polar codes, as the coding scheme for the control channel in fifth-generation mobile communication technology (5G), have attracted widespread attention since their proposal. As a mainstream decoding algorithm for polar codes, the successive cancellation list (SCL) decoder usually improves the error correction performance by increasing the list size, but this method suffers from the problems of high decoding complexity. To address this problem, this paper proposes a layered-search bit-flipping (LS-SCLF) decoding algorithm based on SCL decoding. Firstly, a new flip-bit metric is proposed, which derives a formula to approximate the probability of an error occurring in an information bit. This formula introduces a perturbation parameter to improve the calculation accuracy. Secondly, a compromise scheme for determining the perturbation parameter is proposed. The scheme uses Monte Carlo simulation to determine an optimized parameter for the precise positioning of the first erroneous decoded bit under different decoding conditions. Finally, a layered search strategy is adopted to sequentially search the erroneous decoded bits from the low order to high order, which can correct up to multiple bits at the same time. Simulation results show that the proposed algorithm achieves improved error correction performance with a slight increase in decoding complexity compared to the generalized SCL-Flip (GSCLF) decoding algorithm. This algorithm also achieves a good balance between the error correction performance and decoding complexity. [ABSTRACT FROM AUTHOR]