Non-invasive single-cell biomechanical analysis using live-imaging datasets

The physiological state of a cell is governed by a multitude of processes and can be described by a combination of mechanical, spatial and temporal properties. Quantifying cell dynamics at multiple scales is essential for comprehensive studies of cellular function, and remains a challenge for traditional end-point assays. We introduce an efficient, non-invasive computational tool that takes time-lapse images as input to automatically detect, segment and analyze unlabeled live cells; the program then outputs kinematic cellular shape and migration parameters, while simultaneously measuring cellular stiffness and viscosity. We demonstrate the capabilities of the program by testing it on human mesenchymal stem cells (huMSCs) induced to differentiate towards the osteoblastic (huOB) lineage, and T-lymphocyte cells (T cells) of naïve and stimulated phenotypes. The program detected relative cellular stiffness differences in huMSCs and huOBs that were comparable to those obtained with studies that utilize atomic force microscopy; it further distinguished naïve from stimulated T cells, based on characteristics necessary to invoke an immune response. In summary, we introduce an integrated tool to decipher spatiotemporal and intracellular dynamics of cells, providing a new and alternative approach for cell characterization

Influenza A viruses with different amino acid residues at PB2-627 display distinct replication properties in vitro and in vivo: Revealing the sequence plasticity of PB2-627 position

Sequence analyses of influenza PB2 sequences indicate that the 627 position almost exclusively contains either lysine (K) or glutamic acid (E), suggesting a high sequence constraint at this genetic marker. Here, we used a site-directed random mutagenesis method to demonstrate that PB2-627 position has a high sequence plasticity. Recombinant viruses carrying various amino acid residues at this position are viable in cell cultures. These PB2-627 mutants showed various polymerase activities and replication kinetics in mammalian and avian cells as well as pathogenicity in mice. Serially passaging these mutants in MDCK cells generated some compensatory PB2 mutations that can restore polymerase activities of the PB2-627 mutants. Of these, PB2-D309N was identified as a novel one. Besides showing that influenza virus can tolerate a wide range of amino acid residues at the PB2-627 position, this study also demonstrates a potential strategy to identify novel mutations that can enhance viral polymerase

Oblique axial MR imaging of the normal anterior cruciate ligament bundles

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Is radiation-free ultrasound accurate for quantitative assessment of spinal deformity in idiopathic scoliosis (IS) : a detailed analysis with EOS radiography on 952 patients

202002 bcrcVersion of RecordPublishe

Imaging of ulnar-sided wrist pain

Ulnar-sided wrist pain is a complex entity to diagnose clinically and frequently requires imaging to help confirm or determine the diagnosis. This article reviews the imaging and the logical imaging pathway of the common causes of ulnar-sided wrist pain, and illustrates various pathologies. It also discusses appropriate imaging modalities for various conditions. The causes of ulnar-sided wrist pain are stratified according to the affected anatomical structures, such as bony, soft tissue or neurovascular aetiologies. This review provides a handy imaging framework for non-radiologist clinicians of the common conditions producing ulnar-sided wrist pain. A linked article ( 10.12968/hmed.2019.80.8.456 ) detailing the diagnosis of ulnar-sided wrist pain is included in this issue

Sirtuin 1 is upregulated in a subset of hepatocellular carcinomas where it is essential for telomere maintenance and tumor cell growth

Hepatocellular carcinoma (HCC) is a highly malignant tumor with a poor prognosis. Treatment of HCC is complicated by the fact that the disease is often diagnosed at an advanced stage when it is no longer amenable to curative surgery, and current systemic chemotherapeutics are mostly inefficacious. Sirtuin 1 (SIRT1) is a class III histone deacetylase that is implicated in gene regulations and stress resistance. In this study, we found that SIRT1 is essential for the tumorigenesis of HCC. We showed that although SIRT1 was expressed at very low levels in normal livers, it was overexpressed in HCC cell lines and in a subset of HCC. Tissue microarray analysis of HCC and adjacent nontumoral liver tissues revealed a positive correlation between the expression levels of SIRT1 and advancement in tumor grades. Downregulation of SIRT1 consistently suppressed the proliferation of HCC cells via the induction of cellular senescence or apoptosis. SIRT1 silencing also caused telomere dysfunction-induced foci and nuclear abnormality that were clearly associated with reduced expressions of telomerase reverse transcriptase (TERT), and PTOP, which is a member of the shelterin complex. Ectopic expression of either TERT or PTOP in SIRT1-depleted cells significantly restored cell proliferation. There was also a positive correlation between the level of induction of SIRT1 and PTOP in human HCC. Finally, SIRT1-silencing sensitized HCC cells to doxorubicin treatment. Together, our findings reveal a novel function for SIRT1 in telomere maintenance of HCC, and they rationalize the clinical exploration of SIRT1 inhibitors for HCC therapy. ©2011 AACR.link_to_subscribed_fulltex

Co-circulation of two SARS-CoV-2 variant strains within imported pet hamsters in Hong Kong

202212 bckwVersion of RecordPublishe

Single-nucleotide polymorphism (SNP) of excision repair cross complementation group 1 (ERCC1) in nasopharynx cancer (NPC): A companion biomarker study to Hong Kong NPC Study Group 0502 trial

Poster Highlights Session - Head and Neck Cancer: abstract no. 6029Background: Polymorphisms at ERCC1 has been linked to platinum sensitivity and treatment outcome. We hypothesized that ERCC1 SNP at codon 118 and C8092A is predictive of relapse free survival (RFS) in NPC, and correlates with ERCC1 protein/mRNA in paired tumor samples. Methods: 0502 is a multi-center prospective clinical trial to assess adjuvant chemotherapy in NPC pts with detectable plasma EBV-DNA (pEBV) following primary radiotherapy (RT) or cisplatin-RT (CRT) (NCT00370890). Eligible pts with biopsy proven NPC, AJCC stage IIB-IVB, no persistent locoregional disease or distant metastasis, ECOG 0-1, adequate organ function, were screened by pEBV at 6-8 weeks after completing RT/CRT. Post-RT pEBV -ve pts received no further treatment. pEBV +ve pts underwent work-up and randomization to adjuvant chemotherapy or observation. We tested our hypothesis using samples collected in the 0502 screening cohort. Primary endpoint is relapse free survival (RFS). ERCC1 genotyping was by TaqMan real time PCR. 450 pts is planned to detect a hazard ratio (HR) of 1.5 for the weaker ERCC1 SNP at 80% power and 2-side 5% alpha level. In subset with available tumor biopsies, we quantified ERCC1 protein expression by immunohistochemistry (IHC) or Western blot (WB) with mouse monoclonal antibody (clone 8F1), and ERCC1 mRNA by quantitative RT-PCR. Results: ERCC1 SNP was analyzed in peripheral blood lymphocytes from 478 pts. Median follow up was 3.61 years (90% C.I. 3.36-3.88). 31% pEBV +ve, 17% randomized. ERCC1 genotype distribution at codon 118: 54% CC, 39% CT, 7% TT; C8092A: 38% CC, 50% CA, 12% AA. There was no significant association of ERCC1 SNP with 3-year RFS or overall survival. No significant correlation was observed in ERCC1 SNP and tumor ERCC1 expression by IHC, WB or mRNA. In subset evaluated by ERCC1 IHC (n=79), pts with ERCC1+ve tumor (H-score > median) had worse RFS (HR 2.34, 95% C.I. 1.06-5.16, p=0.036). Multivariate analysis showed pEBV was the most significant adverse prognosticator for all clinical endpoints. Conclusions: We found no association of ERCC1 SNP with NPC survival. pEBV remained the most significant prognostic biomarker in NPC