762 research outputs found

    Cone photoreceptor definition on adaptive optics retinal imaging

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    To quantitatively analyse cone photoreceptor matrices on images captured on an adaptive optics (AO) camera and assess their correlation to well-established parameters in the retinal histology literature

    Exfoliation of single layer BiTeI flakes

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    Spin orbit interaction is strongly enhanced in structures where a heavy element is embedded in an inversion asymmetric crystal field. A simple way for realizing such a setup is to take a single atomic layer of a heavy element and encapsulate it between two atomic layers of different elemental composition. BiTeI is a promising candidate for such a 2D crystal. In its bulk form BiTeI consists of loosely coupled three atom thick layers where a layer of high atomic number Bi are sandwiched between Te and I sheets. Despite considerable recent attention to bulk BiTeI due to its giant Rashba spin splitting, the isolation of a single layer remained elusive. In this work we report the first successful isolation and characterization of a single layer of BiTeI using a novel exfoliation technique on stripped gold. Our scanning probe studies and first principles calculations show that the fabricated 100 mu m sized BiTeI flakes are stable at ambient conditions. Giant Rashba splitting and spin-momentum locking of this new 2D crystal opens the way towards novel spintronic applications and synthetic topological heterostructures

    CASZ1b, the Short Isoform of CASZ1 Gene, Coexpresses with CASZ1a during Neurogenesis and Suppresses Neuroblastoma Cell Growth

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    In Drosophila, the CASZ1 (castor) gene encodes a zinc finger transcription factor and is a neural fate-determination gene. In mammals, the CASZ1 gene encodes two major isoforms, CASZ1a with 11 zinc fingers and CASZ1b with 5 zinc fingers. CASZ1b is more evolutionally conserved since it is the only homologue found in drosophila and Xenopus. Our previous study showed that full length CASZ1 (CASZ1a) functions to suppress growth in neuroblastoma tumor. However, the function of CASZ1b isoform in mammals is unknown. In this study, realtime PCR analyses indicate that mouse CASZ1b (mCASZ1b) is dynamically expressed during neurogenesis. CASZ1b and CASZ1a co-exist in all the neuronal tissues but exhibit distinct expression patterns spatially and temporally during brain development. CASZ1b and CASZ1a expression is coordinately upregulated by the differentiation agent Retinoic Acid, as well as agents that modify the epigenome in neural crest derived neuroblastoma cell lines. In contrast CASZ1b is down regulated while CASZ1a is upregulated by agents that raise intracellular cAMP levels. CASZ1b and CASZ1a have no synergistic or antagonistic activities on the regulation of their target NGFR gene transcription. Specific restoration of CASZ1b in NB cells suppresses tumor growth in vitro and in vivo. Consistent with its function role, we find that low CASZ1b expression is significantly associated with decreased survival probability of neuroblastoma patients (p<0.02). This study indicates that although their mechanisms of regulation may be distinct, both CASZ1b and CASZ1a have largely redundant but critical roles in suppressing tumor cell growth

    Evaluation of nanopore sequencing for Mycobacterium tuberculosis drug susceptibility testing and outbreak investigation: a genomic analysis

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    BACKGROUND: Mycobacterium tuberculosis whole-genome sequencing (WGS) has been widely used for genotypic drug susceptibility testing (DST) and outbreak investigation. For both applications, Illumina technology is used by most public health laboratories; however, Nanopore technology developed by Oxford Nanopore Technologies has not been thoroughly evaluated. The aim of this study was to determine whether Nanopore sequencing data can provide equivalent information to Illumina for transmission clustering and genotypic DST for M tuberculosis. METHODS: In this genomic analysis, we analysed 151 M tuberculosis isolates from Madagascar, South Africa, and England, which were collected between 2011 and 2018, using phenotypic DST and matched Illumina and Nanopore data. Illumina sequencing was done with the MiSeq, HiSeq 2500, or NextSeq500 platforms and Nanopore sequencing was done on the MinION or GridION platforms. Using highly reliable PacBio sequencing assemblies and pairwise distance correlation between Nanopore and Illumina data, we optimise Nanopore variant filters for detecting single-nucleotide polymorphisms (SNPs; using BCFtools software). We then used those SNPs to compare transmission clusters identified by Nanopore with the currently used UK Health Security Agency Illumina pipeline (COMPASS). We compared Illumina and Nanopore WGS-based DST predictions using the Mykrobe software and mutation catalogue. FINDINGS: The Nanopore BCFtools pipeline identified SNPs with a median precision of 99.3% (IQR 99.1-99.6) and recall of 90.2% (88.1-94.2) compared with a precision of 99.6% (99.4-99.7) and recall of 91.9% (87.6-98.6) using the Illumina COMPASS pipeline. Using a threshold of 12 SNPs for putative transmission clusters, Illumina identified 98 isolates as unrelated and 53 as belonging to 19 distinct clusters (size range 2-7). Nanopore reproduced 15 out of 19 clusters perfectly; two clusters were merged into one cluster, one cluster had a single sample missing, and one cluster had an additional sample adjoined. Illumina-based clusters were also closely replicated using a five SNP threshold and clustering accuracy was maintained using mixed Illumina and Nanopore datasets. Genotyping resistance variants with Nanopore was highly concordant with Illumina, having zero discordant SNPs across more than 3000 SNPs and four insertions or deletions (indels), across 60 000 indels. INTERPRETATION: Illumina and Nanopore technologies can be used independently or together by public health laboratories performing M tuberculosis genotypic DST and outbreak investigations. As a result, clinical and public health institutions making decisions on which sequencing technology to adopt for tuberculosis can base the choice on cost (which varies by country), batching, and turnaround time. FUNDING: Academy for Medical Sciences, Oxford Wellcome Institutional Strategic Support Fund, and the Swiss South Africa Joint Research Award (Swiss National Science Foundation and South African National Research Foundation)

    Attitudes to smoking cessation and triggers to relapse among Chinese male smokers

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    BACKGROUND: Smoking is related to many diseases, and the relapse to smoking after cessation in China is noticeable. We examined the attitudes of Chinese male smokers regarding smoking cessation and reasons for relapse. METHODS: We interviewed 201 male smokers in Hangzhou City, Zhejiang province, China who had tried to quit smoking at least once in order to identify reasons for quitting and situations triggering relapse. RESULTS: The most significant reported reasons for quitting included personal health (77.1%), the cost of cigarettes (53.7%), and family pressures to quit (29.9%). The most common factors triggering relapse were social situations (34.3%), feeling negative or down (13.4%) and times of being alone (8.4%). CONCLUSION: Health and family concerns, personal factors, the influence of others and a lack of cessation resources were cited as salient factors concerning smoking cessation among male smokers in this study. Effective smoking control efforts in China will require attention to these influences if China is to curb its current smoking epidemic

    Genetic relationships within and among Iberian fescues (Festuca L.) based on PCR-amplified markers

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    The genus Festuca comprises approximately 450 species and is widely distributed around the world. The Iberian Penninsula, with more than 100 taxa colonizing very diverse habitats, is one of its main centers of diversification. This study was conducted to assess molecular genetic variation and genetic relatedness among 91 populations of 31 taxa of Iberian fescues, based on several molecular markers (random amplified polymorphic DNA, amplified fragment length polymorphisms, and trnL sequences). The analyses showed the paraphyletic origin of the broad-leaved (subgenus Festuca, sections Scariosae and Subbulbosae, and subgenus Schedonorus) and the fine-leaved fescues (subgenus Festuca, sections Aulaxyper, Eskia, and Festuca). Schedonorus showed a weak relationship with Lolium rigidum and appeared to be the most recent of the broad-leaved clade. Section Eskia was the most ancient and Festuca the most recent of the fine-leaved clade. Festuca and Aulaxyper were the most related sections, in concordance with their taxonomic affinities. All taxa grouped into their sections, except F. ampla and F. capillifolia (section Festuca), which appeared to be more closely related to Aulaxyper and to a new independent section, respectively. Most populations clustered at the species level, but some subspecies and varieties mixed their populations. This study demonstrated the value in combining different molecular markers to uncover hidden genetic relationships between populations of Festuca

    Symptoms and quality of life in late stage Parkinson syndromes: a longitudinal community study of predictive factors

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    BACKGROUND Palliative care is increasingly offered earlier in the cancer trajectory but rarely in Idiopathic Parkinson's Disease(IPD), Progressive Supranuclear Palsy(PSP) or Multiple System Atrophy(MSA). There is little longitudinal data of people with late stage disease to understand levels of need. We aimed to determine how symptoms and quality of life of these patients change over time; and what demographic and clinical factors predicted changes. METHODS We recruited 82 patients into a longitudinal study, consenting patients with a diagnosis of IPD, MSA or PSP, stages 3-5 Hoehn and Yahr(H&Y). At baseline and then on up to 3 occasions over one year, we collected self-reported demographic, clinical, symptom, palliative and quality of life data, using Parkinson's specific and generic validated scales, including the Palliative care Outcome Scale (POS). We tested for predictors using multivariable analysis, adjusting for confounders. FINDINGS Over two thirds of patients had severe disability, over one third being wheelchair-bound/bedridden. Symptoms were highly prevalent in all conditions - mean (SD) of 10.6(4.0) symptoms. More than 50% of the MSA and PSP patients died over the year. Over the year, half of the patients showed either an upward (worsening, 24/60) or fluctuant (8/60) trajectory for POS and symptoms. The strongest predictors of higher levels of symptoms at the end of follow-up were initial scores on POS (AOR 1.30; 95%CI:1.05-1.60) and being male (AOR 5.18; 95% CI 1.17 to 22.92), both were more predictive than initial H&Y scores. INTERPRETATION The findings point to profound and complex mix of non-motor and motor symptoms in patients with late stage IPD, MSA and PSP. Symptoms are not resolved and half of the patients deteriorate. Palliative problems are predictive of future symptoms, suggesting that an early palliative assessment might help screen for those in need of earlier intervention

    Supplementation with estradiol-17 beta before the last gonadotropin-releasing hormone injection of the ovsynch protocol in lactating dairy cows

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    The aim of this study was to determine whether an increase in circulating estrogen concentrations would increase percentage pregnant per artificial insemination (PP/AI) in a timed AI protocol in high-producing lactating dairy cows. We analyzed only cows having a synchronized ovulation to the last GnRH of the Ovsynch protocol (867/1,084). The control group (n = 420) received Ovsynch (GnRH - 7 d - PGF2α - 56 h - GnRH -16 h - timed AI). The treatment group (n = 447) had the same timed AI protocol with the addition of 1 mg of estradiol-17β (E2) at 8 h before the second GnRH injection. Ovarian ultrasound and blood samples were taken just before E2 treatment of both groups. In a subset of cows (n = 563), pressure-activated estrus detection devices were used to assess expression of estrus at 48 to 72 h after PGF2α treatment. Ovulation was confirmed by ultrasound 7 d after timed AI. Treatment with E2 increased expression of estrus but overall PP/ AI did not differ between E2 and control cows. There was an interaction between treatment and expression of estrus such that PP/AI was greater in E2-treated cows that showed estrus than in E2-treated or control cows that did not show estrus and tended to be greater than control cows that showed estrus. There was evidence for a treatment by ovulatory follicle size interaction on PP/AI. Supplementation with E2 improved PP/ AI in cows ovulating medium (15 to 19 mm) but not smaller or larger follicles. The E2 treatment also tended to improve PP/AI in primiparous cows with low (S2.5) body condition score, and in cows at first postpartum service compared with Ovsynch alone. In conclusion, any improvements in PP/AI because of E2 treatment during a timed AI protocol appear to depend on expres sion of estrus, parity, body condition score, and size of ovulatory follicle

    Genomic epidemiology of complex, multi-species, plasmid-borne blaKPC carbapenemase in Enterobacterales in the UK, 2009-2014

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    Carbapenem resistance in Enterobacterales is a public health threat. Klebsiella pneumoniae carbapenemase (encoded by alleles of the blaKPC family) is one of the most common transmissible carbapenem resistance mechanisms worldwide. The dissemination of blaKPC historically has been associated with distinct K. pneumoniae lineages (clonal group 258 [CG258]), a particular plasmid family (pKpQIL), and a composite transposon (Tn4401). In the United Kingdom, blaKPC has represented a large-scale, persistent management challenge for some hospitals, particularly in North West England. The dissemination of blaKPC has evolved to be polyclonal and polyspecies, but the genetic mechanisms underpinning this evolution have not been elucidated in detail; this study used short-read whole-genome sequencing of 604 blaKPC-positive isolates (Illumina) and long-read assembly (PacBio)/polishing (Illumina) of 21 isolates for characterization. We observed the dissemination of blaKPC (predominantly blaKPC-2; 573/604 [95%] isolates) across eight species and more than 100 known sequence types. Although there was some variation at the transposon level (mostly Tn4401a, 584/604 [97%] isolates; predominantly with ATTGA-ATTGA target site duplications, 465/604 [77%] isolates), blaKPC spread appears to have been supported by highly fluid, modular exchange of larger genetic segments among plasmid populations dominated by IncFIB (580/604 isolates), IncFII (545/604 isolates), and IncR (252/604 isolates) replicons. The subset of reconstructed plasmid sequences (21 isolates, 77 plasmids) also highlighted modular exchange among non-blaKPC and blaKPC plasmids and the common presence of multiple replicons within blaKPC plasmid structures (>60%). The substantial genomic plasticity observed has important implications for our understanding of the epidemiology of transmissible carbapenem resistance in Enterobacterales for the implementation of adequate surveillance approaches and for control
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