The Chinese University of Hong Kong

About: The Chinese University of Hong Kong is a education organization based out in Hong Kong, China. It is known for research contribution in the topics: Population & Cancer. The organization has 43411 authors who have published 93672 publications receiving 3066651 citations.

Gene silencing in cancer by histone H3 lysine 27 trimethylation independent of promoter DNA methylation

Abstract: Epigenetic silencing in cancer cells is mediated by at least two distinct histone modifications, polycomb-based histone H3 lysine 27 trimethylation (H3K27triM) and H3K9 dimethylation. The relationship between DNA hypermethylation and these histone modifications is not completely understood. Using chromatin immunoprecipitation microarrays (ChIP-chip) in prostate cancer cells compared to normal prostate, we found that up to 5% of promoters (16% CpG islands and 84% non-CpG islands) were enriched with H3K27triM. These genes were silenced specifically in prostate cancer, and those CpG islands affected showed low levels of DNA methylation. Downregulation of the EZH2 histone methyltransferase restored expression of the H3K27triM target genes alone or in synergy with histone deacetylase inhibition, without affecting promoter DNA methylation, and with no effect on the expression of genes silenced by DNA hypermethylation. These data establish EZH2-mediated H3K27triM as a mechanism of tumor-suppressor gene silencing in cancer that is potentially independent of promoter DNA methylation.

Recovering Realistic Texture in Image Super-Resolution by Deep Spatial Feature Transform

Abstract: Despite that convolutional neural networks (CNN) have recently demonstrated high-quality reconstruction for single-image super-resolution (SR), recovering natural and realistic texture remains a challenging problem. In this paper, we show that it is possible to recover textures faithful to semantic classes. In particular, we only need to modulate features of a few intermediate layers in a single network conditioned on semantic segmentation probability maps. This is made possible through a novel Spatial Feature Transform (SFT) layer that generates affine transformation parameters for spatial-wise feature modulation. SFT layers can be trained end-to-end together with the SR network using the same loss function. During testing, it accepts an input image of arbitrary size and generates a high-resolution image with just a single forward pass conditioned on the categorical priors. Our final results show that an SR network equipped with SFT can generate more realistic and visually pleasing textures in comparison to state-of-the-art SRGAN [27] and EnhanceNet [38].

Frequency of hepatitis B virus reactivation in cancer patients undergoing cytotoxic chemotherapy: a prospective study of 626 patients with identification of risk factors

Abstract: Hepatitis B virus (HBV) reactivation is a well-described complication in cancer patients who receive cytotoxic chemotherapy and may result in varying degrees of liver damage. As chemotherapy is used increasingly in cancer patients, HBV reactivation during cytotoxic treatment may become a more common problem. In lymphoma patients, the incidence of chronic HBV infection has been reported to be 26%, of whom 47% developed HBV reactivation during chemotherapy. However, corresponding data for patients with other malignancies undergoing cytotoxic chemotherapy are not known. In this prospective study, hepatitis B surface antigen (HBsAg) was determined in 626 consecutive cancer patients who received cytotoxic chemotherapy over a 12-month period. Seventy-eight patients (12%) were found to be HBsAg positive. Thirty-four (44%) developed raised alanine transaminase during their course of chemotherapy. In these 34 patients, hepatitis was attributed to HBV reactivation in 15 patients (44%), chronic active HBV infection in 1 patient (3%), hepatitis C infection in 1 patient (3%), malignant hepatic infiltration in 2 patients (6%), and the use of hepatotoxic chemotherapeutic agents in 11 patients (32%). The causes of hepatitis were unknown in 4 patients (12%). HBV reactivation was more likely to develop in patients who were male, younger age, HBeAg seropositive, and those with lymphoma. Presence of malignant hepatic infiltration, baseline pre-treatment alanine transaminase, total bilirubin, and HBV DNA levels did not correlate with the development of HBV reactivation. Of the 15 patients who developed HBV reactivation, antiviral therapy with lamivudine was available and used in 9. There was no HBV-related mortality during chemotherapy. It is concluded that in patients with chronic HBV infection under chemotherapy, HBV reactivation occurs in nearly 20% of them and accounts for 44% of hepatitis cases. The risk factors identified include male sex, younger age, HBeAg seropositive, and the diagnosis of lymphoma. In HBV endemic areas, patients with risk factors for HBV reactivation should be identified prior to receiving cytotoxic treatment and monitored closely. The potential benefit of lamivudine requires further confirmation.

Implant-derived magnesium induces local neuronal production of CGRP to improve bone-fracture healing in rats

Abstract: Orthopedic implants containing biodegradable magnesium have been used for fracture repair with considerable efficacy; however, the underlying mechanisms by which these implants improve fracture healing remain elusive. Here we show the formation of abundant new bone at peripheral cortical sites after intramedullary implantation of a pin containing ultrapure magnesium into the intact distal femur in rats. This response was accompanied by substantial increases of neuronal calcitonin gene-related polypeptide-α (CGRP) in both the peripheral cortex of the femur and the ipsilateral dorsal root ganglia (DRG). Surgical removal of the periosteum, capsaicin denervation of sensory nerves or knockdown in vivo of the CGRP-receptor-encoding genes Calcrl or Ramp1 substantially reversed the magnesium-induced osteogenesis that we observed in this model. Overexpression of these genes, however, enhanced magnesium-induced osteogenesis. We further found that an elevation of extracellular magnesium induces magnesium transporter 1 (MAGT1)-dependent and transient receptor potential cation channel, subfamily M, member 7 (TRPM7)-dependent magnesium entry, as well as an increase in intracellular adenosine triphosphate (ATP) and the accumulation of terminal synaptic vesicles in isolated rat DRG neurons. In isolated rat periosteum-derived stem cells, CGRP induces CALCRL- and RAMP1-dependent activation of cAMP-responsive element binding protein 1 (CREB1) and SP7 (also known as osterix), and thus enhances osteogenic differentiation of these stem cells. Furthermore, we have developed an innovative, magnesium-containing intramedullary nail that facilitates femur fracture repair in rats with ovariectomy-induced osteoporosis. Taken together, these findings reveal a previously undefined role of magnesium in promoting CGRP-mediated osteogenic differentiation, which suggests the therapeutic potential of this ion in orthopedics.