Publications by authors named "Peter Gee"

Gene editing in human induced pluripotent stem (iPS) cells with programmable nucleases facilitates reliable disease models, but methods using double-strand break repair often produce random on-target by-products. Prime editing (PE) combines Cas9 nickase with reverse transcriptase and PE guide RNA (pegRNA) encoding a repair template to reduce by-products. We implemented a GMP-compatible protocol for transfecting Cas9- or PE-2A-mCherry plasmids to track and fractionate human iPS cells based on PE expression level.

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Experimental studies on DNA transposable elements (TEs) have been limited in scale, leading to a lack of understanding of the factors influencing transposition activity, evolutionary dynamics, and application potential as genome engineering tools. We predicted 130 active DNA TEs from 102 metazoan genomes and evaluated their activity in human cells. We identified 40 active (integration-competent) TEs, surpassing the cumulative number (20) of TEs found previously.

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Blood vessels show various COVID-19-related conditions including thrombosis and cytokine propagation. Existing blood vessel models cannot represent the consequent changes in the vascular structure or determine the initial infection site, making it difficult to evaluate how epithelial and endothelial tissues are damaged. Here, we developed a microphysiological system (MPS) that co-culture the bronchial organoids and the vascular bed to analyze infection site and interactions.

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Objective: Little research has evaluated trends in psychotropic prescribing and polypharmacy in primary care patients, especially those with dementia. We sought to examine this in Australia from 2011 to 2020 using the primary care dataset, MedicineInsight.

Methods: Ten consecutive serial cross-sectional analyses were performed to evaluate the proportion of patients aged 65 years or more, with a recorded diagnosis of dementia, who were prescribed psychotropic medications within the first six months of each year from 2011 to 2020.

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SARS-CoV-2 induces severe organ damage not only in the lung but also in the liver, heart, kidney, and intestine. It is known that COVID-19 severity correlates with liver dysfunction, but few studies have investigated the liver pathophysiology in COVID-19 patients. Here, we elucidated liver pathophysiology in COVID-19 patients using organs-on-a-chip technology and clinical analyses.

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The CRISPR-Cas9 system has quickly become the standard tool for genome editing. To deliver this system to target cells, adeno-associated virus (AAV) vectors are commonly used. In fact, AAV vectors have been utilized to deliver the CRISPR-Cas9 system to induce genomic exon skipping and restore the dystrophin protein in various Duchenne muscular dystrophy model animals.

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Selection-free, scarless genome editing in human pluripotent stem cells (PSCs) by utilizing ribonucleoprotein (RNP) of CRISPR-Cas9 is a useful tool for a variety of applications. However, the process can be hampered by time-consuming subcloning steps and inefficient delivery of the RNP complex and ssDNA template. Here, we describe the optimized protocol to introduce a single nucleotide change or a loxP site insertion in feeder-free, xeno-free iPSCs by utilizing MaxCyte and 4D-Nucleofector electroporators.

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Combined with CRISPR-Cas9 technology and single-stranded oligodeoxynucleotides (ssODNs), specific single-nucleotide alterations can be introduced into a targeted genomic locus in induced pluripotent stem cells (iPSCs); however, ssODN knockin frequency is low compared with deletion induction. Although several Cas9 transduction methods have been reported, the biochemical behavior of CRISPR-Cas9 nuclease in mammalian cells is yet to be explored. Here, we investigated intrinsic cellular factors that affect Cas9 cleavage activity in vitro.

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Background: Numerous mobile health (mHealth) apps have been developed to support smokers attempting to quit smoking. Although these apps have been reported to be successful, only modest improvements in the quit rate have been measured. It has been proposed that efforts to improve user engagement and retention may improve the quit rate further.

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Prolonged expression of the CRISPR-Cas9 nuclease and gRNA from viral vectors may cause off-target mutagenesis and immunogenicity. Thus, a transient delivery system is needed for therapeutic genome editing applications. Here, we develop an extracellular nanovesicle-based ribonucleoprotein delivery system named NanoMEDIC by utilizing two distinct homing mechanisms.

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Although single-component Class 2 CRISPR systems, such as type II Cas9 or type V Cas12a (Cpf1), are widely used for genome editing in eukaryotic cells, the application of multi-component Class 1 CRISPR has been less developed. Here we demonstrate that type I-E CRISPR mediates distinct DNA cleavage activity in human cells. Notably, Cas3, which possesses helicase and nuclease activity, predominantly triggered several thousand base pair deletions upstream of the 5'-ARG protospacer adjacent motif (PAM), without prominent off-target activity.

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Induced pluripotent stem cells (iPSCs) have strong potential in regenerative medicine applications; however, immune rejection caused by HLA mismatching is a concern. B2M gene knockout and HLA-homozygous iPSC stocks can address this issue, but the former approach may induce NK cell activity and fail to present antigens, and it is challenging to recruit rare donors for the latter method. Here, we show two genome-editing strategies for making immunocompatible donor iPSCs.

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The delivery of mRNA is advantageous over DNA delivery as it is transient and does not carry the risk of genomic DNA integration. However, there are currently few efficient mRNA delivery options available, especially for hard-to-transfect cell types, and thus new delivery methods are needed. To this end, we have established a novel mRNA delivery system utilizing chimeric virus-like particles (VLPs).

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Objective: To assess the impact of a multi-strategic, interdisciplinary intervention on antipsychotic and benzodiazepine prescribing in residential aged care facilities (RACFs). Design, setting: Prospective, longitudinal intervention in Australian RACFs, April 2014 - March 2016.

Participants: 150 RACFs (with 12 157 residents) comprised the main participant group; two further groups were consultant pharmacists (staff education) and community pharmacies (prescribing data).

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Introduction: The previously reported Patients' Experience of LIving with CANcer-associated thrombosis (PELICAN) identified several areas of unmet clinical and support need for cancer patients diagnosed with venous thromboembolism (VTE) in the UK. It is not known whether such experiences are restricted to one particular country's healthcare system and culture. We therefore undertook an evaluation of patients' experience of cancer-associated thrombosis (CAT) within a Spanish setting.

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Objective: For at least two decades, concerns have been raised about inappropriate psychotropic prescribing in Australian residential aged care facilities, due to their modest therapeutic benefit and increased risk of falls and mortality. To date, the majority of prevalence data has been collected in Sydney exclusively and it is not known if recent initiatives to promote appropriate psychotropic prescribing have impacted utilisation. Thus, we aimed to comprehensively analyse psychotropic use in a large national sample of residential aged care facility residents.

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Randomized mutagenesis at an endogenous chromosomal locus is a promising approach for protein engineering, functional assessment of regulatory elements, and modeling genetic variations. In mammalian cells, however, it is challenging to perform site-specific single-nucleotide substitution with single-stranded oligodeoxynucleotide (ssODN) donor templates due to insufficient homologous recombination and the infeasibility of positive selection. Here, we developed a DNA transposon based CRISPR-Cas9 regulated transcription and nuclear shuttling (CRONUS) system that enables the stable transduction of CRISPR-Cas9/sgRNA in broad cell types, but avoids undesired genome cleavage in the absence two chemical inducing molecules.

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Background: Inappropriate use of sedating medication has been reported in nursing homes for several decades. The Reducing Use of Sedatives (RedUSe) project was designed to address this issue through a combination of audit, feedback, staff education, and medication review. The project significantly reduced sedative use in a controlled trial of 25 Tasmanian nursing homes.

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In the past decade, the development of two innovative technologies, namely, induced pluripotent stem cells (iPSCs) and the CRISPR Cas9 system, has enabled researchers to model diseases derived from patient cells and precisely edit DNA sequences of interest, respectively. In particular, Duchenne muscular dystrophy (DMD) has been an exemplary monogenic disease model for combining these technologies to demonstrate that genome editing can correct genetic mutations in DMD patient-derived iPSCs. DMD is an X-linked genetic disorder caused by mutations that disrupt the open reading frame of the gene, which plays a critical role in stabilizing muscle cells during contraction and relaxation.

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Background: Smoking is recognized as the largest, single, preventable cause of death and disease in the developed world. While the majority of smokers report wanting to quit, and many try each year, smokers find it difficult to maintain long-term abstinence. Behavioral support, such as education, advice, goal-setting, and encouragement, is known to be beneficial in improving the likelihood of succeeding in a quit attempt, but it remains difficult to effectively deliver this behavioral support and keep the patient engaged with the process for a sufficient duration.

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Developing appropriate strategies to sustain optimal medication adherence among the increasing number of HIV-positive patients taking antiretroviral therapy (ART) in sub-Saharan Africa is a major challenge. The objective of this study was to determine patient, regimen, disease, patient-provider, and healthcare-related factors associated with adherence with ART over a one-year period, and assess the impact of adherence on treatment outcomes. We performed a prospective, observational study among 246 patients who were initiated on ART in Ethiopia.

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Precise gene correction using the CRISPR-Cas9 system in human iPS cells holds great promise for various applications, such as the study of gene functions, disease modeling, and gene therapy. In this review article, we summarize methods for effective editing of genomic sequences of iPS cells based on our experiences correcting dystrophin gene mutations with the CRISPR-Cas9 system. Designing specific sgRNAs as well as having efficient transfection methods and proper detection assays to assess genomic cleavage activities are critical for successful genome editing in iPS cells.

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Programmable nucleases, such as zinc finger nucleases (ZFNs), transcription activator like effector nucleases (TALENs), and clustered regularly interspersed short palindromic repeats associated protein-9 (CRISPR-Cas9), hold tremendous potential for applications in the clinical setting to treat genetic diseases or prevent infectious diseases. However, because the accuracy of DNA recognition by these nucleases is not always perfect, off-target mutagenesis may result in undesirable adverse events in treated patients such as cellular toxicity or tumorigenesis. Therefore, designing nucleases and analyzing their activity must be carefully evaluated to minimize off-target mutagenesis.

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Background: Current HIV antiretroviral therapies potently suppress virus replication and prevent patients from progressing to AIDS but are unable to completely eliminate HIV due to the existence of dormant viral reservoirs which threaten to reemerge at anytime. Recently, genome-editing technologies that can recognize specific DNA sequences, including viral DNA, are being touted as promising tools for curing HIV, owing to their specificity, ease of use, and ability to be custom designed.

Conclusion: Here, we introduce several novel strategies aimed at eradicating HIV proviruses with state-of-the-art genome-editing technologies and discuss perspectives of these approaches for curing HIV.

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