Effects of functional transient receptor potential channels on adipogenesis and proliferation in human preadipocytes

BACKGROUND: Preadipocytes are extensively used as a type of proliferative cell culture model to investigate proliferation and differentiation of adipocytes and lipodystrophy (eg obesity)-related metabolic dysfunctions and disorders. However, cell biology is not well understood in human preadipocytes. The present study was to investigate the ...published_or_final_versionThe 17th Medicial Research Conference, Department of Medicine, The University of Hong Kong, 14 January 2012. In Hong Kong Medical Journal, 2012, v. 18 n. 1, suppl. 1, p. 24, abstract no. 3

Effects of functional transient receptor potential channels on proliferation and migration in human cardiac c-kit+ cells

Poster PresentationINTRODUCTION: Human adult c-kit+ cardiac stem cell are characterised by the expression of c-kit in the absence of lineage markers such as Nkx2.5. They are self-renewing, clonogenic and multipotent, giving rise to a minimum of three differentiated cell types: myocytes, smooth muscle, and endothelial vascular cells. These cells, although not specifically programmed for myocardial differentiation, have been shown to improve cardiac function in a myocardial injury/reconstitution assay. However, cell biology is not fully understood. The present study was to investigate the expression of transient receptor potential (TRP) channels in hum…published_or_final_versio

Revisit of the Cardiac Inward Rectifier Potassium Current IK1

Inward rectifier potassium currents are present in different types of cells. In the heart, the inward rectifier potassium current IK1 plays a crucial role in maintaining cardiac resting membrane potential and excitability. It is generally believed that the strong inward rectification of cardiac IK1 channels makes it conduct substantial current near the resting potential but carry little or no current at depolarized potentials. However, recent studies in native cardiac myocytes and HEK 293 cell line stably expressing human Kir2.1 gene have demonstrated that a significant transient outward current carried by IK1 channels is activated by the upstroke of action potential. This review will revisit cardiac IK1 channels, especially the previously-ignored transient outward component of IK1 carried by Kir2.1 channels.published_or_final_versio

Functional expression of transient receptor potential channels in human preadipocytes

published_or_final_versionThe 16th Medical Resarch Conference (MRC), The University of Hong Kong, Hong Kong, China, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 32, abstract no. 4

Locality of connective constants

The connective constant $\mu(G)$ of a quasi-transitive graph $G$ is the exponential growth rate of the number of self-avoiding walks from a given origin. We prove a locality theorem for connective constants, namely, that the connective constants of two graphs are close in value whenever the graphs agree on a large ball around the origin (and a further condition is satisfied). The proof exploits a generalized bridge decomposition of self-avoiding walks, which is valid subject to the assumption that the underlying graph is quasi-transitive and possesses a so-called unimodular graph height function

The Flexible Group Spatial Keyword Query

We present a new class of service for location based social networks, called the Flexible Group Spatial Keyword Query, which enables a group of users to collectively find a point of interest (POI) that optimizes an aggregate cost function combining both spatial distances and keyword similarities. In addition, our query service allows users to consider the tradeoffs between obtaining a sub-optimal solution for the entire group and obtaining an optimimized solution but only for a subgroup. We propose algorithms to process three variants of the query: (i) the group nearest neighbor with keywords query, which finds a POI that optimizes the aggregate cost function for the whole group of size n, (ii) the subgroup nearest neighbor with keywords query, which finds the optimal subgroup and a POI that optimizes the aggregate cost function for a given subgroup size m (m <= n), and (iii) the multiple subgroup nearest neighbor with keywords query, which finds optimal subgroups and corresponding POIs for each of the subgroup sizes in the range [m, n]. We design query processing algorithms based on branch-and-bound and best-first paradigms. Finally, we provide theoretical bounds and conduct extensive experiments with two real datasets which verify the effectiveness and efficiency of the proposed algorithms.Comment: 12 page

Both ion channels and calcium signals regulate proliferation in human adult mesenchymal stem cells from bone marrow

BACKGROUND: It has been recognized that human bone marrow-derived mesenchymal stem cells (MSCs) are present within the bone marrow cavity and serve as a reservoir for the ...postprintThe 9th Annual Meeting of the International Society for Stem Cell Research (ISSCR 2011), Toronto, Canada, 15-18 June 2011. In Thursday Poster Abstracts of ISSCR, 2011, p. 156, poster board no. 301

Roles of Functional Ion Channels In Human Cardiac C-Kit+ Progenitor Cells

Poster PresentationBackground and objectives: Cardiac progenitor cells play an important role in cardiac repair and regeneration; however, cellular biology and electrophysiology are not understood. The present study was to investigate the functional ion channel expression in human cardiac c-kit+ progenitor cells and the 53 potential roles of these ion channels in regulating proliferation and migration. Methods: Multiple experimental approaches were employed in this study, including whole-cell patch voltage-clamp, RT-PCR, Western blots, cell proliferation and migration assays, etc. Results: Several ionic currents were heterogeneously expressed in human cardiac c-kit+ progenitor cells, including a large conductance Ca2+-activated K+ current (BKCa) in most (93%) of cells, an inwardly-rectifying K+ current (IKir) in 87% of cells, a transient outward K+ current (Ito) in 39% of cells, a voltage-gated tetrodotoxin-sensitive Na+ currents (INa,TTX) in 76% of cells. Molecular identities of these ionic currents were determined with RT-PCR and Western blot analysis. KCa.1.1 (for BKCa), Kir2.1 (for IKir), Kv4.2, Kv4.3 (for Ito), NaV1.2, NaV1.3, NaV1.6, NaV1.7 (for INa.TTX) were expressed in human cardiac progenitor cells. Inhibition of BKCa with paxilline, Ito with 4-aminopyridine, but not INa.TTX with TTX and IKir with Ba2+, decreased cell proliferation. Silencing of KCa.1.1, Kv4.2 or Kv4.3, but not Kir2.1, with siRNA targeting corresponding channels reduced proliferation. Inhibition of KCa1.1 or Kv4.2 or Kv4.3 channels accumulated cells at G0/G1 phase. Interestingly, down regulation of KCa1.1, Kv4.2 or Kv4.3 channels decreased, while of Kir2.1 channels increased migration in human c-kit+ progenitor cells. Conclusions: These results demonstrate for the first time that multiple ion channels are expressed in human cardiac c-kit+ cells. KCa1.1, Kv4.2, and Kv4.3 channels, but not Na+ channels and Kir 2.1 channels, participate in regulating proliferation. KCa1.1, Kv4.2 or Kv4.3 channels promote, while Kir2.1 channels reduce cell migration in human cardiac c-kit+ progenitor cells.published_or_final_versio

Detection of Bacteroides forsythus and Porphyromonas gingivalis from root canals

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Epidermal Growth Factor Stimulates Cell Proliferation by Activating Voltage-Gated Potassium Channels in Rat Bone Marrow-Derived Mesenchymal Stem Cells

Poster PresentationBackground and objective: We have previously found that voltage-gated delayed rectifier potassium current (IKDR, encoded by Kv1.2 and Kv2.1) participated in regulation of cell cycling progression in rat mesenchymal stem cells (MSCs) from bone marrow. The present study was designed to investigate whether epidermal growth factor (EGF) regulates cell growth is mediated by activating IKDR. Methods: Whole-cell patch voltage-clamp, RT-PCR, Western blots, siRNA, cell proliferation assay were employed in the present study Results: EGF increased cell proliferation in a concentration-dependent manner, and the effect was countered by the broad spectrum protein tyrosine (PTK) inhibitor genistein and the EGFR kinase inhibitor AG556. We found that genistein and AG556 inhibited IKDR in a concentration-dependent manner, The protein tyrosine phosphatase (PTP) inhibitor orthovanadate enhanced IKDR, and counted the inhibitory effect of IKDR by genistein or AG556, suggesting the PTK-mediating modulation of IKDR. Interestingly EGF also increased IKDR, Downregulation of IKDR with siRNA targeting to Kv1.2 or Kv2.1 channels inhibited basal proliferation, and prevented EGF-stimulated proliferation in rat MSCs. Conclusion: These results demonstrate for the first time that EGF stimulates cell proliferation activating IKDR, and silencing Kv1.2 or Kv2.1 channels prevents the augmentation of proliferation by EFG, indicating that Kv1.2 and Kv2.1 channels mediate EGF effect in regulating cell growth in rat MSCs.published_or_final_versio