Early patellar tendon rupture after total knee arthroplasty: A direct repair method

BACKGROUND Patellar tendon rupture after total knee arthroplasty(TKA)is a catastrophic complication.Although the occurrence of this injury is rare,it can lead to significant dysfunction for the patient and is very tricky to deal with.There has been no standard treatment for early patella tendon rupture after TKA,and long-term follow-up data are lacking.AIM To introduce a direct repair method for early patella tendon rupture following TKA and determine the clinical outcomes and complications of this method.METHODS During the period of 2008 to 2021,3265 consecutive TKAs were retrospectively reviewed.Twelve patients developed early patellar tendon rupture postoperatively and were treated by a direct repair method.Mean follow-up was 5.7 years.Demographic,operative,and clinical data were collected.The clinical outcomes were assessed using the Western Ontario and McMaster Universities(WOMAC)score,the Hospital for Special Surgery(HSS)score,knee range of motion,extensor lag,and surgical complications.Descriptive statistics and paired t test were employed to analyze the data.RESULTS For all 12 patients who underwent direct repair for early patellar tendon rupture,3 patients failed:One(8.3%)for infection and two(17.6%)for re-fracture.The two patients with re-fracture both underwent reoperation to reconstruct the extensor mechanism and the patient with infection underwent revision surgery.The range of motion was 109.2°±10.6°preoperatively to 87.9°±11°postoperatively,mean extensor lag was 21°at follow-up,and mean WOMAC and HSS scores were 65.8±30.9 and 60.3±21.7 points,respectively.CONCLUSION This direct repair method of early patellar tendon rupture is not an ideal therapy.It is actually ineffective for the recovery of knee joint function in patients,and is still associated with severe knee extension lag and high complication rates.Compared with the outcomes of other repair methods mentioned in the literature,this direct repair method shows poor clinical outcomes.

Water-facilitated targeted repair of degraded cathodes for sustainable lithium-ion batteries

Directly repairing end-of-life lithium-ion battery cathodes poses significant chal-lenges due to the diverse compositions of the wastes.Here,we propose a water-facilitated targeted repair strategy applicable to various end-of-life batches and cathodes.The process involves initiating structural repair and reconstruct-ing particle morphology in degraded LiMn_(2)O_(4)(LMO)through an additional thermal drive post-ambient water remanganization,achieving elemental repair.Compared to solid-phase repair,the resulting LMO material exhibits superior electrochemical and kinetic characteristics.The theoretical analysis highlights the impact of Mn defects on the structural stability and electron transfer rate of degraded materials.The propensity of Mn ions to diffuse within the Mn layer,specifically occupying the Mn 16d site instead of the Li 8a site,theoretically sup-ports the feasibility of ambient water remanganization.Moreover,this method proves effective in the relithiation of degraded layered cathode materials,yielding single crystals.By combining low energy consumption,environmental friendli-ness,and recyclability,our study proposes a sustainable approach to utilizing spent batteries.This strategy holds the potential to enable the industrial direct repair of deteriorated cathode materials.

DNA direct reversal repair and alkylating agent drug resistance

DNA direct reversal repair(DRR)is unique in that no DNA synthesis is required to correct the error and therefore repair via such mechanisms are error-free.In humans,DRR is carried out by two different pathways:the O6-methylguanine-DNA methyltransferase(MGMT)and the alkylated DNA repair protein B(AlkB)homologs.The use of alkylating agents is the standard of care for many cancers.However,the use of those drugs is usually halted when resistance develops.This review will examine repair of alkylating agent damage mediated by DRR,resistance mechanisms and potential ways to overcome such resistance.

A novel CRISPR/Cas9 system with high genomic editing efficiency and recyclable auxotrophic selective marker for multiple-step metabolic rewriting in Pichia pastoris

The methylotrophic budding yeast Pichia pastoris has been utilized to the production of a variety of heterologous recombinant proteins owing to the strong inducible alcohol oxidase promoter(pAOX1).However,it is difficult to use P.pastoris as the chassis cell factory for high-valuable metabolite biosynthesis due to the low homologous recombination(HR)efficiency and the limitation of handy selective markers,especially in the condition of multistep biosynthetic pathways.Hence,we developed a novel CRISPR/Cas9 system with highly editing efficiencies and recyclable auxotrophic selective marker(HiEE-ReSM)to facilitate cell factory in P.pastoris.Firstly,we improved the HR rates of P.pastoris through knocking out the non-homologous-end-joining gene(Δku70)and overexpressing HR-related proteins(RAD52 and RAD59),resulting in higher positive rate compared to the basal strain,achieved 97%.Then,we used the uracil biosynthetic genes PpURA3 as the reverse screening marker,which can improve the recycling efficiency of marker.Meanwhile,the HR rate is still 100%in uracil auxotrophic yeast.Specially,we improved the growth rate of uracil auxotrophic yeast strains by overexpressing the uracil transporter(scFUR4)to increase the uptake of exogenous uracil from medium.Meanwhile,we explored the optimal concentration of uracil(90 mg/L)for strain growth.In the end,the HiEE-ReSM system has been applied for the inositol production(250 mg/L)derived from methanol in P.pastoris.The systems will contribute to P.pastoris as an attractive cell factory for the complex compound biosynthesis through multistep metabolic pathway engineering and will be a useful tool to improve one carbon(C1)bio-utilization.

A CRISPR/Cas9-based visual toolkit enabling multiplex integration at specific genomic loci in Aspergillus niger

Aspergillus niger is a highly versatile fungal strain utilized in industrial production.The expression levels of recombinant genes in A.niger can be enhanced by increasing the copy number.Nevertheless,given the prolonged gene editing cycle of A.niger,a“one-step”strategy facilitating the simultaneous integration of recombinant genes into multiple genomic loci would provide a definitive advantage.In our previous study,a visual multigene editing system(VMS)was designed to knock out five genes,employing a tRNA-sgRNA array that includes the pigment gene albA and the target genes.Building upon this system,hybrid donor DNAs(dDNAs)were introduced to establish a clustered regularly interspaced short palindromic repeats(CRISPR)-based multiplex integration toolkit.Firstly,a CRISPR-Cas9 homology-directed repair(CRISPR-HDR)system was constructed in A.niger by co-transforming the CRISPR-Cas9 plasmid(with a highly efficient sgRNA)and the dDNA,resulting in precise integration of recombinant xylanase gene xynA into the target loci(theβ-glucosidase gene bgl,the amylase gene amyA,and the acid amylase gene ammA).Subsequently,the length of homology arms in the dDNA was optimized to achieve 100%editing efficiency at each of the three gene loci.To achieve efficient multiplex integration in A.niger,the CRISPR plasmid pLM2 carrying a sgRNA-tRNA array was employed for concurrent double-strand breaks at multiple loci(bgl,amyA,ammA,and albA).Hybrid dDNAs were then employed for repair,including dDNA1-3(containing xynA expression cassettes without selection markers)and dDNAalbA(for albA knockout).Among the obtained white colonies(RLM2′),23.5%exhibited concurrent replacement of the bgl,amyA,and ammA genes with xynA(three copies).Notably,the xynA activity obtained by simultaneous insertion into three loci was 48.6%higher compared to that obtained by insertion into only the bgl locus.Furthermore,this multiple integration toolkit successfully enhanced the expression of endogenous pectinase pelA and Candida antarctica lipase CALB.Hence,the combined application of VMS and the CRISPR-HDR system enabled the simultaneous application of multiple selection markers,facilitating the rapid generation in the A.niger cell factories.