The need for systematic quality controls in implementing N95 reprocessing and sterilization

BACKGROUND

Due to increased requirement for personal protective equipment during the coronavirus disease 2019 pandemic, many medical centres utilized sterilization systems approved under Food and Drug Administration Emergency Use Authorization for single-use N95 mask re-use. However, few studies have examined the real-world clinical challenges and the role of ongoing quality control measures in successful implementation.

AIMS

To demonstrate successful implementation of quality control measures in mask reprocessing, and the importance of continued quality assurance.

METHODS

A prospective quality improvement study was conducted at a tertiary care medical centre. In total, 982 3M 1860 masks and Kimberly-Clark Tecnol PFR95 masks worn by healthcare workers underwent sterilization using a vaporized hydrogen peroxide gas plasma-based reprocessing system. Post-processing qualitative fit testing (QFT) was performed on 265 masks. Mannequin testing at the National Institute for Occupational Safety and Health (NIOSH) laboratory was used to evaluate the impact of repeated sterilization on mask filtration efficacy and fit. A locally designed platform evaluated the filtration efficiency of clinically used and reprocessed masks.

FINDINGS

In total, 255 N95 masks underwent QFT. Of these, 240 masks underwent post-processing analysis: 205 were 3M 1860 masks and 35 were PFR95 masks. Twenty-five (12.2%) of the 3M masks and 10 (28.5%) of the PFR95 masks failed post-processing QFT. Characteristics of the failed masks included mask deformation (N=3, all 3M masks), soiled masks (N=3), weakened elastic bands (N=5, three PFR95 masks), and concern about mask shrinkage (N=3, two 3M masks). NIOSH testing demonstrated that while filter efficiency remained >98% after two cycles, mask strap elasticity decreased by 5.6% after reprocessing.

CONCLUSIONS

This study demonstrated successful quality control implementation for N95 mask disinfection, and highlights the importance of real-world clinical testing beyond laboratory conditions.

Baseline Findings of PreventE4: A Double-Blind Placebo Controlled Clinical Trial Testing High Dose DHA in APOE4 Carriers before the Onset of Dementia

INTRODUCTION

Lower blood levels of the omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) are correlated with worse cognitive functions, particularly among APOE ε4 carriers. Whether DHA supplementation in APOE ε4 carriers with limited DHA consumption and dementia risk factors can delay or slow down disease progression when started before the onset of clinical dementia is not known.

METHODS

PreventE4 is a double-blind, single site, randomized, placebo-controlled trial in cognitively unimpaired individuals with limited omega-3 consumption and dementia risk factors (n=368). Its objectives are to determine (1) whether carrying the APOE ε4 allele is associated with lower delivery of DHA to the brain; and (2) whether high dose DHA supplementation affects brain imaging biomarkers of AD and cognitive function.

RESULTS

365 cognitively unimpaired individuals between 55 and 80 (mean age 66) were randomized to 2 grams of DHA per day or identically appearing placebo for a period of 2 years. Half the participants were asked to complete lumbar punctures at baseline and 6-month visits to obtain cerebrospinal fluid (CSF). The primary trial outcome measure is the change in CSF DHA to arachidonic acid ratio after 6 months of the intervention (n=181). Secondary trial outcomes include the change in functional and structural connectivity using resting state functional MRI at 24 months (n=365). Exploratory outcomes include the change in Repeatable Battery of the Assessment of Neuropsychological Status at 24 months (n=365).

CONCLUSIONS

Findings from PreventE4 will clarify the brain delivery of DHA in individuals carrying the APOE ε4 allele with implications for dementia prevention strategies. Trial was registered as NCT03613844.

Aquatic and terrestrial cyanobacteria produce methane

Evidence is accumulating to challenge the paradigm that biogenic methanogenesis, considered a strictly anaerobic process, is exclusive to archaea. We demonstrate that cyanobacteria living in marine, freshwater, and terrestrial environments produce methane at substantial rates under light, dark, oxic, and anoxic conditions, linking methane production with light-driven primary productivity in a globally relevant and ancient group of photoautotrophs. Methane production, attributed to cyanobacteria using stable isotope labeling techniques, was enhanced during oxygenic photosynthesis. We suggest that the formation of methane by cyanobacteria contributes to methane accumulation in oxygen-saturated marine and limnic surface waters. In these environments, frequent cyanobacterial blooms are predicted to further increase because of global warming potentially having a direct positive feedback on climate change. We conclude that this newly identified source contributes to the current natural methane budget and most likely has been producing methane since cyanobacteria first evolved on Earth.

Archaea predominate among ammonia-oxidizing prokaryotes in soils

Ammonia oxidation is the first step in nitrification, a key process in the global nitrogen cycle that results in the formation of nitrate through microbial activity. The increase in nitrate availability in soils is important for plant nutrition, but it also has considerable impact on groundwater pollution owing to leaching. Here we show that archaeal ammonia oxidizers are more abundant in soils than their well-known bacterial counterparts. We investigated the abundance of the gene encoding a subunit of the key enzyme ammonia monooxygenase (amoA) in 12 pristine and agricultural soils of three climatic zones. amoA gene copies of Crenarchaeota (Archaea) were up to 3,000-fold more abundant than bacterial amoA genes. High amounts of crenarchaeota-specific lipids, including crenarchaeol, correlated with the abundance of archaeal amoA gene copies. Furthermore, reverse transcription quantitative PCR studies and complementary DNA analysis using novel cloning-independent pyrosequencing technology demonstrated the activity of the archaea in situ and supported the numerical dominance of archaeal over bacterial ammonia oxidizers. Our results indicate that crenarchaeota may be the most abundant ammonia-oxidizing organisms in soil ecosystems on Earth.

Production of recombinant and tagged proteins in the hyperthermophilic archaeon Sulfolobus solfataricus

Many systems are available for the production of recombinant proteins in bacterial and eukaryotic model organisms, which allow us to study proteins in their native hosts and to identify protein-protein interaction partners. In contrast, only a few transformation systems have been developed for archaea, and no system for high-level gene expression existed for hyperthermophilic organisms. Recently, a virus-based shuttle vector with a reporter gene was developed for the crenarchaeote Sulfolobus solfataricus, a model organism of hyperthermophilic archaea that grows optimally at 80 degrees C (M. Jonuscheit, E. Martusewitsch, K. M. Stedman, and C. Schleper, Mol. Microbiol. 48:1241-1252, 2003). Here we have refined this system for high-level gene expression in S. solfataricus with the help of two different promoters, the heat-inducible promoter of the major chaperonin, thermophilic factor 55, and the arabinose-inducible promoter of the arabinose-binding protein AraS. Functional expression of heterologous and homologous genes was demonstrated, including production of the cytoplasmic sulfur oxygenase reductase from Acidianus ambivalens, an Fe-S protein of the ABC class from S. solfataricus, and two membrane-associated ATPases potentially involved in the secretion of proteins. Single-step purification of the proteins was obtained via fused His or Strep tags. To our knowledge, these are the first examples of the application of an expression vector system to produce large amounts of recombinant and also tagged proteins in a hyperthermophilic archaeon.

Molecular analysis of pDL10 from Acidianus ambivalens reveals a family of related plasmids from extremely thermophilic and acidophilic archaea

The 7598-bp plasmid pDL10 from the extremely thermophilic, acidophilic, and chemolithoautotrophic Archaeon Acidianus ambivalens was sequenced. It contains 10 open reading frames (ORFs) organized in five putative operons. The deduced amino acid sequence of the largest ORF (909 aa) showed similarity to bacterial Rep proteins known from phages and plasmids with rolling-circle (RC) replication. From the comparison of the amino acid sequences, a novel family of RC Rep proteins was defined. The pDL10 Rep protein shared 45-80% identical residues with homologous protein genes encoded by the Sulfolobus islandicus plasmids pRN1 and pRN2. Two DNA regions capable of forming extended stem-loop structures were also conserved in the three plasmids (48-69% sequence identity). In addition, a putative plasmid regulatory protein gene (plrA) was found, which was conserved among the three plasmids and the conjugative Sulfolobus plasmid pNOB8. A homolog of this gene was also found in the chromosome of S. solfataricus. Single-stranded DNA of both pDL10 strands was detected with a mung bean nuclease protection assay using PCR detection of protected fragments, giving additional evidence for an RC mechanism of replication.