Search bioRxiv⌕ Search

Biology subjects

Simpson, S. M.

Publications and source records attributed to Simpson, S. M..

2 recordsLinked to original sources

Assembly Arena: Benchmarking RNA isoform reconstruction algorithms for nanopore sequencing

Resolving the transcriptomes of higher eukaryotes is more tangible with the advent of long read sequencing, which greatly facilitates the identification of new transcripts and their splicing isoforms. However, the computational analysis of long read RNA sequencing data remains challenging as it is difficult to disentangle technical artifacts from bona fide biological information. To address this, we evaluated the performance of multiple leading transcriptome assembly algorithms on their ability to accurately reconstruct RNA transcript isoforms. We specifically focused on deep nanopore sequencing of synthetic RNA spike-in controls (Sequins and SIRVs) across different chemistries, including cDNA and direct RNA protocols. Our systematic comparative benchmarking exposes the strengths and limitations of the different surveyed strategies. We also highlight conceptual and technical challenges with the annotation of transcriptomes and the formalization of assembly quality metrics. Our results complement similar recent endeavors, helping forge a path towards a gold standard analytical pipeline for long read transcriptome assembly.

bioinformatics↗

A Subcutaneous Implant of Tenofovir Alafenamide Fumarate Causes Local Inflammation and Tissue Necrosis in Rabbits and Macaques

We describe the in vitro and in vivo evaluation of a subcutaneous reservoir implant delivering tenofovir alafenamide hemifumarate (TAF) for the prevention of HIV infection. These long-acting reservoir implants were able to deliver antiretroviral drug for over 90 days in vitro and in vivo. We evaluated the implants for implantation site histopathology and pharmacokinetics in plasma and tissues for up to 12 weeks in New Zealand White rabbits and rhesus macaque models. A dose-ranging study in rabbits demonstrated dose-dependent pharmacokinetics and local inflammation up to severe necrosis around the active implants. The matched placebos showed normal wound healing and fibrous tissue encapsulation of the implant. We designed a second implant with a lower release rate and flux of TAF and achieved a median cellular level of tenofovir diphosphate of 42 fmol per 106 rhesus macaque peripheral blood mononuclear cells at a dose of 10 {micro}g/kg/day. This dose and flux of TAF also resulted in adverse local inflammation and necrosis near the implant in rhesus macaques. Inflammation in the primates was markedly lower in the placebo group than the active implant. The histological inflammatory response to the TAF implant at 4 and 12 weeks in primates was graded as a severe reaction. Thus, while we were able to achieve sustained target dose we observed unacceptable inflammatory response locally at the implant tissue interface.

pharmacology and toxicology↗