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1.
Hong Kong Med J ; 29(6): 514-523, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37968897

ABSTRACT

INTRODUCTION: The utilisation of extracorporeal membrane oxygenation (ECMO) has been rapidly increasing in Hong Kong. This study examined 10-year trends in the utilisation and clinical outcomes of ECMO in Hong Kong. METHODS: We retrospectively reviewed the records of all adult patients receiving ECMO who were admitted to the intensive care units (ICUs) of public hospitals in Hong Kong between 2010 and 2019. Temporal trends across years were assessed using the Mann-Kendall test. Observed hospital mortality was compared with the Acute Physiology and Chronic Health Evaluation (APACHE) IV-predicted mortality. RESULTS: The annual number of patients receiving ECMO increased from 18 to 171 over 10 years. In total, 911 patients received ECMO during the study period: 297 (32.6%) received veno-arterial ECMO, 450 (49.4%) received veno-venous ECMO, and 164 (18.0%) received extracorporeal cardiopulmonary resuscitation. The annual number of patients aged ≥65 years increased from 0 to 47 (27.5%) [P for trend=0.001]. The median (interquartile range) Charlson Comorbidity Index increased from 1 (0-1) to 2 (1-3) [P for trend<0.001] while the median (interquartile range) APACHE IV score increased from 90 (57-112) to 105 (77-137) [P for trend=0.003]. The overall standardised mortality ratio comparing hospital mortality with APACHE IV-predicted mortality was 1.11 (95% confidence interval=1.01-1.22). Hospital and ICU length of stay both significantly decreased (P for trend=0.011 and <0.001, respectively). CONCLUSION: As ECMO utilisation increased in Hong Kong, patients put on ECMO were older, more critically ill, and had more co-morbidities. It is important to combine service expansion with adequate resource allocation and training to maintain quality of care.


Subject(s)
Cardiopulmonary Resuscitation , Extracorporeal Membrane Oxygenation , Adult , Humans , Hong Kong , Retrospective Studies , APACHE
2.
Oncogene ; 35(12): 1504-16, 2016 Mar 24.
Article in English | MEDLINE | ID: mdl-26165844

ABSTRACT

Reactive astrocytes are integral to the glioma microenvironment. Connexin43 (Cx43) is a major gap junction protein in astrocytes and its expression is enhanced significantly in glioma-associated astrocytes, especially at the peri-tumoral region. Although downregulation of Cx43-mediated intercellular communication is associated with increased malignancy in tumor cells, the role of Cx43 in stromal cells in glioma progression is not defined. Using a mouse model consisting of syngeneic intracranial implantation of GL261 glioma cells into Nestin-Cre:Cx43(fl/fl) mice where Cx43 was eliminated in astrocytes, we demonstrate a role of astrocytic Cx43 in the dissemination of glioma cells from the tumor core. To determine whether heterocellular communication between astrocytes and glioma cells is essential for reduced invasion in the absence of astrocytic Cx43, we abolished channel formation between glioma cells and astrocytes by either knocking down Cx43 in glioma cells with short hairpin RNA (shRNA) or overexpressing a dominant-negative channel-defective Cx43-T154A mutant in these cells. Although Cx43shRNA in glioma cells reduced invasion, expression of Cx43-T154A had no effect on glioma invasion, suggesting tumoral Cx43 may influence motility independently from its channel function. Alteration in astrocytic Cx43 function, such as by replacing the wild-type allele with a C-terminal truncated Cx43 mutant exhibiting reduced intercellular coupling, is sufficient to reduce glioma spreading into the brain parenchyma. Our results reveal a novel role of astrocytic Cx43 in the formation of an invasive niche and raise the possibility to control glioma progression by manipulating the microenvironment.


Subject(s)
Astrocytes/pathology , Brain Neoplasms/pathology , Connexin 43/physiology , Glioma/pathology , Neoplasm Invasiveness , Animals , Cell Adhesion , Female , Male , Mice , Mice, Knockout
4.
Glia ; 55(15): 1554-64, 2007 Nov 15.
Article in English | MEDLINE | ID: mdl-17823969

ABSTRACT

Gliomas are particularly difficult to cure owing largely to their invasive nature. The neoplastic changes of astrocytes which give rise to these tumors frequently include a reduction of connexin43 (Cx43), the most abundant connexin isoform expressed in astrocytes. Cx43 is a subunit of gap junctions (GJ), intercellular channels which directly link the cytosol of adjacent cells and allow the regulated passage of ions and small molecules. To examine the role of Cx43 in glioma motility, we identified two variant C6 cell lines which endogenously express high (C6-H) or low (C6-L) levels of Cx43. In wound healing and transwell assays, C6-H cells were more motile than C6-L cells. To deduce whether Cx43 mediated these differences, assays were conducted on C6-H cells retrovirally transduced with Cx43 shRNA. Coincident with the stable knockdown of endogenous Cx43, a decrease in motility and invasion was observed. Gap junctional intercellular communication was also decreased, however motility assays conducted in the presence of GJ inhibitors did not reveal significant differences in cell motility. C6 cells transfected with full length or C-terminal truncated Cx43 (Cx43DeltaCT) were subjected to the aforementioned motility assays to expose alternate mechanisms of Cx43-mediated motility. Cells expressing full length Cx43 exhibited increased motility while cells expressing Cx43DeltaCT did not. This report, the first in which RNAi has been employed to reduce Cx43 expression in gliomas, indicates that the downregulation of Cx43 decreases motility of C6 cells. Furthermore, it is the first report to suggest that the Cx43 CT plays an important role in glioma motility.


Subject(s)
Brain Neoplasms/pathology , Carcinogens , Connexin 43/chemistry , Connexin 43/physiology , Glioma/pathology , Animals , Blotting, Western , Cell Line, Tumor , Cell Movement/physiology , Gap Junctions/drug effects , Immunohistochemistry , Neoplasm Invasiveness/pathology , RNA, Small Interfering/pharmacology , Rats , Structure-Activity Relationship , Wound Healing/physiology
5.
Neuron ; 29(3): 583-91, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11301019

ABSTRACT

We report an electroporation technique for targeting gene transfer to individual cells in intact tissue. Electrical stimulation through a micropipette filled with DNA or other macromolecules electroporates a single cell at the tip of the micropipette. Electroporation of a plasmid encoding enhanced green fluorescent protein (GFP) into the brain of intact Xenopus tadpoles or rat hippocampal slices resulted in GFP expression in single neurons and glia. In vivo imaging showed morphologies, dendritic arbor dynamics, and growth rates characteristic of healthy cells. Coelectroporation of two plasmids resulted in expression of both proteins, while electroporation of fluorescent dextrans allowed direct visualization of transfer of molecules into cells. This technique will allow unprecedented spatial and temporal control over gene delivery and protein expression.


Subject(s)
Electroporation , Gene Transfer Techniques , Animals , Culture Techniques , Dextrans/administration & dosage , Fluorescein/administration & dosage , Green Fluorescent Proteins , Hippocampus/metabolism , Interneurons/metabolism , Larva/metabolism , Luminescent Proteins/genetics , Microscopy, Confocal , Neurons/chemistry , Neurons/metabolism , Pyramidal Cells/metabolism , Rats , Rhodamines/administration & dosage , Superior Colliculi/chemistry , Superior Colliculi/metabolism , Transfection/methods , Xenopus
6.
Mol Cell Biol ; 18(11): 6325-39, 1998 Nov.
Article in English | MEDLINE | ID: mdl-9774649

ABSTRACT

The regulation of morphological changes in eukaryotic cells is a complex process involving major components of the cytoskeleton including actin microfilaments, microtubules, and intermediate filaments (IFs). The putative effector of RhoA, RhoA-binding kinase alpha (ROKalpha), is a serine/threonine kinase that has been implicated in the reorganization of actin filaments and in myosin contractility. Here, we show that ROKalpha also directly affects the structural integrity of IFs. Overexpression of active ROKalpha, like that of RhoA, caused the collapse of filamentous vimentin, a type III IF. A RhoA-binding-deficient, kinase-inactive ROKalpha inhibited the collapse of vimentin IFs induced by RhoA in HeLa cells. In vitro, ROKalpha bound and phosphorylated vimentin at its head-rod domain, thereby inhibiting the assembly of vimentin. ROKalpha colocalized predominantly with the filamentous vimentin network, which remained intact in serum-starved cells. Treatment of cells with vinblastine, a microtubule-disrupting agent, also resulted in filamentous vimentin collapse and concomitant ROKalpha translocation to the cell periphery. ROKalpha translocation did not occur when the vimentin network remained intact in vinblastine-treated cells at 4 degreesC or in the presence of the dominant-negative RhoAN19 mutant. Transient translocation of ROKalpha was also observed in cells subjected to heat shock, which caused the disassembly of the vimentin network. Thus, the translocation of ROKalpha to the cell periphery upon overexpression of RhoAV14 or growth factor treatment is associated with disassembly of vimentin IFs. These results indicate that Rho effectors known to act on microfilaments may be involved in regulating the assembly of IFs. Vimentin when phosphorylated also exhibits reduced affinity for the inactive ROKalpha. The translocation of ROKalpha from IFs to the cell periphery upon action by activated RhoA and ROKalpha suggests that ROKalpha may initiate its own cascade of activation.


Subject(s)
GTP-Binding Proteins/metabolism , Intermediate Filaments/metabolism , Protein Serine-Threonine Kinases/metabolism , Vimentin/metabolism , Animals , Cell Line , Fluorescent Dyes/metabolism , Gene Expression Regulation/genetics , Humans , Immunohistochemistry , Intracellular Signaling Peptides and Proteins , Mice , Microinjections , Microscopy, Fluorescence , Phosphorylation , Protein Serine-Threonine Kinases/genetics , Recombinant Proteins/genetics , Vinblastine/pharmacology , rho-Associated Kinases , rhoA GTP-Binding Protein
7.
Mol Cell Biol ; 13(8): 4986-98, 1993 Aug.
Article in English | MEDLINE | ID: mdl-8336731

ABSTRACT

n-Chimerin (alpha 1-chimerin) is a brain GTPase-activating protein (GAP) for the ras-related p21rac. We now report the occurrence of another form of chimerin, termed alpha 2-chimerin. This is the product of an alternately spliced transcript of the human n-chimerin gene encoding an N-terminal SH2 (src homology 2) domain in addition to the phorbol ester receptor and GAP domains. alpha 1- and alpha 2-chimerin mRNAs were expressed differently. In the rat brain, only alpha 1-chimerin mRNA was expressed in cerebellar Purkinje cells, although both alpha 1- and alpha 2-chimerin mRNAs occurred in neurons in the cerebral cortex, hippocampus, and thalamus. Only alpha 2-chimerin RNA was expressed in rat testes, in early pachytene spermatocytes. A 45-kDa SH2-containing chimerin corresponding to the alpha 2 form was purified from rat brain. As with Escherichia coli 45-kDa recombinant alpha 2-chimerin, purified brain alpha 2-chimerin exhibited racGAP activity which was stimulated by phosphatidylserine. The recombinant SH2 domain bound several 32P-labelled phosphoproteins of PC12 cells, whose phosphorylation increased in response to trophic factors, including nerve growth factor. To examine the relationships of alpha 1- and alpha 2-chimerin transcripts, human genomic DNA clones were characterized. In alpha 2-chimerin mRNA, a 3' splice acceptor site within exon 1 of alpha 1-chimerin mRNA was used, replacing its 5' untranslated region and N-terminal coding sequence. The single human n-chimerin gene was mapped to chromosome 2q31-q32.1, colocalizing with the CRE-BP1 transcription factor gene (2q32). It contained several splice junctions conserved with the sequence-related protein kinase C and bcr genes. alpha 2-Chimerin is only the second SH2-containing GAP and the first example of an SH2 domain generated by alternate splicing.


Subject(s)
Nerve Tissue Proteins/genetics , Protein-Tyrosine Kinases , Proteins/genetics , Alternative Splicing , Amino Acid Sequence , Animals , Base Sequence , Brain/metabolism , Chimerin 1 , Chromosomes, Human, Pair 2 , Cloning, Molecular , DNA/genetics , Exons , GTP-Binding Proteins/metabolism , GTPase-Activating Proteins , Humans , Male , Molecular Sequence Data , PC12 Cells , Phosphatidylserines/metabolism , Phosphoproteins/metabolism , Protein Kinase C/genetics , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-bcr , Restriction Mapping , Sequence Alignment , Spermatocytes/metabolism , Testis/metabolism , rac GTP-Binding Proteins , ras GTPase-Activating Proteins
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