Accurate chromosome segregation requires timely bipolar spindle formation during mitosis. The tra... more Accurate chromosome segregation requires timely bipolar spindle formation during mitosis. The transforming acidic coiled-coil (TACC) family proteins and the ch-TOG family proteins are key players in bipolar spindle formation. They form a complex to stabilize spindle microtubules, mainly dependent on their localization to the centrosome (the spindle pole body [SPB] in yeast). The molecular mechanism underlying the targeting of the TACCch-TOG complex to the centrosome remains unclear. Here we show that the fission yeast Schizosaccharomyces pombe TACC orthologue alp7p is recruited to the SPB by csi1p. The csi1p-interacting region lies within the conserved TACC domain of alp7p, and the carboxylterminal domain of csi1p is responsible for interacting with alp7p. Compromised interaction between csi1p and alp7p impairs the localization of alp7p to the SPB during mitosis, thus delaying bipolar spindle formation and leading to anaphase B lagging chromosomes. Hence our study establishes that csi1p serves as a linking molecule tethering spindle-stabilizing factors to the SPB for promoting bipolar spindle assembly.
International Journal of Enterprise Information Systems, 2000
E-banking is seen as the newest delivery channel for banking services in many developed countries... more E-banking is seen as the newest delivery channel for banking services in many developed countries and is believed to have a significant impact on the bank market. E-banking is providing numerous opportunities for banks and non-bank financial institutions to add a low cost distribution channel to their existent distribution channels. Little research on factors influencing the adoption of e-banking has been implemented in countries with very high economic growth rates (such as Vietnam) that are emerging as new potential markets. Thus, this study has, based on an extensive literature review on e-banking benefits for both banks and their customers and relevant theories on innovation adoption, proposed alternative models (including both moderator and mediating effects) of e-banking intention to use by customers in Vietnam. Furthermore, a set of model hypotheses presenting relationships among factors influencing e-banking intention to use have been set up. Practical implications and future studies were also discussed.
Bacterial infection remains one of the most serious issues affecting the successful installation ... more Bacterial infection remains one of the most serious issues affecting the successful installation and retention of orthopedic implants. Many bacteria develop resistance to current antibiotics, which complicates or prevents traditional antibiotic-dependent eradication therapy. In this study, a hybrid coating of titanium dioxide and polydimethylsiloxane (PDMS) was synthesized to regulate the release of silver. The coatings were benefited from the antimicrobial activity of silver ion, the biocompatibility of titanium dioxide, and the flexibility of the polymer. Three studied silver doped coatings with different titanium dioxide-PDMS ratios effectively inhibited the attachment and growth of Staphylococcus aureus and Staphylococcus epidermidis in a dose-dependent manner. The coatings were successfully applied on the discs of polyether ether ketone (PEEK), a common spinal implant material and antibacterial property of these coatings was assessed via Kirby Bauer assay. More importantly, these selected coatings completely inhibited biofilm formation. The release study demonstrated that the release rate of silver from the coating depended on doping levels and also the ratios of titanium dioxide and PDMS. This result is crucial for designing coatings with desired silver release rate on PEEK materials for antimicrobial applications.
Staphylococcus aureus is a key bacterium commonly found in numerous infections. S. aureus infecti... more Staphylococcus aureus is a key bacterium commonly found in numerous infections. S. aureus infections are difficult to treat due to their biofilm formation and documented antibiotic resistance. While selenium has been used for a wide range of applications including anticancer applications, the effects of selenium nanoparticles on microorganisms remain largely unknown to date. The objective of this in vitro study was thus to examine the growth of S. aureus in the presence of selenium nanoparticles. Results of this study provided the first evidence of strongly inhibited growth of S. aureus in the presence of selenium nanoparticles after 3, 4, and 5 hours at 7.8, 15.5, and 31 μg/mL. The percentage of live bacteria also decreased in the presence of selenium nanoparticles. Therefore, this study suggests that selenium nanoparticles may be used to effectively prevent and treat S. aureus infections and thus should be further studied for such applications.
Physical chemistry chemical physics : PCCP, Jan 28, 2012
In the drive to devise catalytic systems to convert solar energy into the energy of chemical bond... more In the drive to devise catalytic systems to convert solar energy into the energy of chemical bonds, chemists and electrochemists are seeking inspiration from our understanding of enzymes involved in bioenergetics. This is particularly true for generating molecular hydrogen from high energy electrons derived from solar driven water splitting. In this case the natural enzymes are the [NiFe]- and [FeFe]-hydrogenases. In this article we review our present understanding of the structure and mechanistic functioning of these enzymes and how they are providing a blue print to the design and understanding of the mechanism of a variety of synthesized catalysts for proton reduction chemistry.
Wetting properties of biomaterials, in particular nanomaterials, play an important role, as these... more Wetting properties of biomaterials, in particular nanomaterials, play an important role, as these influence interactions with biological elements, such as proteins, bacteria, and cells. In this study, the wetting phenomenon of titanium substrates coated with selenium nanoparticles was studied using experimental and mathematical modeling tools. Importantly, these selenium-coated titanium substrates were previously reported to increase select protein adsorption (such as vitronectin and fibronectin), to decrease bacteria growth, and increase bone cell growth. Increased selenium nanoparticle coating density resulted in higher contact angles but remained within the hydrophilic regime. This trend was found in disagreement with the Wenzel model, which is widely used to understand the wetting properties of rough surfaces. The trend also did not fit well with the Cassie-Baxter model, which was developed to understand the wetting properties of composite surfaces. A modified wetting model was thus proposed in this study, to understand the contributing factors of material properties to the hydrophilicity/ hydrophobicity of these nanostructured selenium-coated surfaces. The analysis and model created in this study can be useful in designing and/or understanding the wetting behavior of numerous biomedical materials and in turn, biological events (such as protein adsorption as well as bacteria and mammalian cell functions).
Fission yeast cells are rod-shaped unicellular organism that is normally imaged horizontally with... more Fission yeast cells are rod-shaped unicellular organism that is normally imaged horizontally with its long axis parallel to image plane. This orientation, while practical, limits the imaging resolution of biological structures which are oriented perpendicular to the long axis of the cell. We present here a method to prepare agarose pads with micro-sized holes to load single fission yeast cell vertically and image cell with its long axis perpendicular to the image plane. As a demonstration, actomyosin ring contraction is shown with this new imaging device.
Materials science & engineering. C, Materials for biological applications, 2014
The development of smooth, featureless surfaces for biomedical microelectronics is a challenging ... more The development of smooth, featureless surfaces for biomedical microelectronics is a challenging feat. Other than the traditional electronic materials like silicon, few microelectronic circuits can be produced with conductive features without compromising the surface topography and/or biocompatibility. Diamond is fast becoming a highly sought after biomaterial for electrical stimulation, however, its inherent surface roughness introduced by the growth process limits its applications in electronic circuitry. In this study, we introduce a fabrication method for developing conductive features in an insulating diamond substrate whilst maintaining a planar topography. Using a combination of microwave plasma enhanced chemical vapour deposition, inductively coupled plasma reactive ion etching, secondary diamond growth and silicon wet-etching, we have produced a patterned substrate in which the surface roughness at the interface between the conducting and insulating diamond is approximately 3 nm. We also show that the patterned smooth topography is capable of neuronal cell adhesion and growth whilst restricting bacterial adhesion.
Abstract Two common problems with implantation after cancerous tumor resection are cancer recurre... more Abstract Two common problems with implantation after cancerous tumor resection are cancer recurrence and bacteria infection at the implant site. Tumor resection surgery sometimes can not remove all the cancerous cells, thus, cancer can return after ...
Microtubules exhibit dynamic instability, stochastically switching between infrequent phases of g... more Microtubules exhibit dynamic instability, stochastically switching between infrequent phases of growth and shrinkage. In the cell, microtubule dynamic instability is further modulated by microtubule-associated proteins and motors, which are specifically tuned to cell cycle stages. For example, mitotic microtubules are more dynamic than interphase microtubules. The different parameters of microtubule dynamics can be measured from length versus time data, which are generally obtained from time-lapse acquisition using the optical microscope. The typical maximum resolution of the optical microscope is ~λ/2 or ~300 nm. This scale represents a challenge for imaging fission yeast microtubule dynamics specifically during early mitosis, where the bipolar mitotic spindle contains many short dynamic microtubules of ~1-μm scale. Here, we present a novel method to image short fission yeast mitotic microtubules. The method uses the thermosensitive reversible kinesin-5 cut7.24(ts) to create monopolar spindles, where asters of individual mitotic microtubules are presented for imaging and subsequent analysis.
ABSTRACT There are currently no orthopedic materials which are made to prevent either the occurre... more ABSTRACT There are currently no orthopedic materials which are made to prevent either the occurrence or reoccurrence of cancer. Due to the above, the objective of this study was to create a new biomaterial which can both restore bone and, at the same time, prevent cancer growth at the implant interface. In the present study, three types of surfaces with different surface densities were prepared. Competitive cell co-culture studies showed promoted growth of healthy bone cells and inhibited growth of cancerous cells when they were co-seeded on high dose selenium (Se) coated titanium (Ti) substrates. Thus, this study provided for the first time a material to the orthopedic community which may inhibit bone cancer growth and promote healthy bone growth.
Metallic bone implants possess numerous problems limiting their efficacy, such as poor osseointeg... more Metallic bone implants possess numerous problems limiting their efficacy, such as poor osseointegration, stress shielding, and corrosion in in vivo environments. In addition, these materials were not originally developed to simultaneously serve as an orthopedic implant and treat bone cancer (for which some patients require an orthopedic implant). This study is to investigate the potential use of selenium in bone
Until recently, traditional orthopedic implant materials termed bioactive have been engineered ... more Until recently, traditional orthopedic implant materials termed bioactive have been engineered to actively promote integration with living bone. We propose to look beyond this traditional form of bioactivity (specifically for orthopedics, in which bioactivity refers to osseointegration ...
Bacteria colonization on medical devices remains one of the most serious complications following ... more Bacteria colonization on medical devices remains one of the most serious complications following implantation. Traditional antibiotic treatment has proven ineffective, creating an increasingly high number of drug-resistant bacteria. Polymeric medical devices represent a significant portion of the total medical devices used today due to their excellent mechanical properties (such as durability, flexibility, etc). However, many polymers (such as polyvinyl chloride (PVC), polyurethane (PU) and silicone) become readily colonized and infected by bacteria immediately after use. Therefore, in this study, a novel antimicrobial coating was developed to inhibit bacterial growth on PVC, PU and silicone. Specifically, here, the aforementioned polymeric substrates were coated with selenium (Se) nanoparticles in situ. The Se-coated substrates were characterized using scanning electron microscopy, energy dispersive x-ray spectroscopy and bacteria assays. Most importantly, bacterial growth was significantly inhibited on the Se-coated substrates compared to their uncoated counterparts. The reduction of bacteria growth directly correlated with the density of Se nanoparticles on the coated substrate surfaces. In summary, these results demonstrate that Se should be further studied as a novel anti-bacterial polymeric coating material which can decrease bacteria functions without the use of antibiotics.
Accurate chromosome segregation requires timely bipolar spindle formation during mitosis. The tra... more Accurate chromosome segregation requires timely bipolar spindle formation during mitosis. The transforming acidic coiled-coil (TACC) family proteins and the ch-TOG family proteins are key players in bipolar spindle formation. They form a complex to stabilize spindle microtubules, mainly dependent on their localization to the centrosome (the spindle pole body [SPB] in yeast). The molecular mechanism underlying the targeting of the TACCch-TOG complex to the centrosome remains unclear. Here we show that the fission yeast Schizosaccharomyces pombe TACC orthologue alp7p is recruited to the SPB by csi1p. The csi1p-interacting region lies within the conserved TACC domain of alp7p, and the carboxylterminal domain of csi1p is responsible for interacting with alp7p. Compromised interaction between csi1p and alp7p impairs the localization of alp7p to the SPB during mitosis, thus delaying bipolar spindle formation and leading to anaphase B lagging chromosomes. Hence our study establishes that csi1p serves as a linking molecule tethering spindle-stabilizing factors to the SPB for promoting bipolar spindle assembly.
International Journal of Enterprise Information Systems, 2000
E-banking is seen as the newest delivery channel for banking services in many developed countries... more E-banking is seen as the newest delivery channel for banking services in many developed countries and is believed to have a significant impact on the bank market. E-banking is providing numerous opportunities for banks and non-bank financial institutions to add a low cost distribution channel to their existent distribution channels. Little research on factors influencing the adoption of e-banking has been implemented in countries with very high economic growth rates (such as Vietnam) that are emerging as new potential markets. Thus, this study has, based on an extensive literature review on e-banking benefits for both banks and their customers and relevant theories on innovation adoption, proposed alternative models (including both moderator and mediating effects) of e-banking intention to use by customers in Vietnam. Furthermore, a set of model hypotheses presenting relationships among factors influencing e-banking intention to use have been set up. Practical implications and future studies were also discussed.
Bacterial infection remains one of the most serious issues affecting the successful installation ... more Bacterial infection remains one of the most serious issues affecting the successful installation and retention of orthopedic implants. Many bacteria develop resistance to current antibiotics, which complicates or prevents traditional antibiotic-dependent eradication therapy. In this study, a hybrid coating of titanium dioxide and polydimethylsiloxane (PDMS) was synthesized to regulate the release of silver. The coatings were benefited from the antimicrobial activity of silver ion, the biocompatibility of titanium dioxide, and the flexibility of the polymer. Three studied silver doped coatings with different titanium dioxide-PDMS ratios effectively inhibited the attachment and growth of Staphylococcus aureus and Staphylococcus epidermidis in a dose-dependent manner. The coatings were successfully applied on the discs of polyether ether ketone (PEEK), a common spinal implant material and antibacterial property of these coatings was assessed via Kirby Bauer assay. More importantly, these selected coatings completely inhibited biofilm formation. The release study demonstrated that the release rate of silver from the coating depended on doping levels and also the ratios of titanium dioxide and PDMS. This result is crucial for designing coatings with desired silver release rate on PEEK materials for antimicrobial applications.
Staphylococcus aureus is a key bacterium commonly found in numerous infections. S. aureus infecti... more Staphylococcus aureus is a key bacterium commonly found in numerous infections. S. aureus infections are difficult to treat due to their biofilm formation and documented antibiotic resistance. While selenium has been used for a wide range of applications including anticancer applications, the effects of selenium nanoparticles on microorganisms remain largely unknown to date. The objective of this in vitro study was thus to examine the growth of S. aureus in the presence of selenium nanoparticles. Results of this study provided the first evidence of strongly inhibited growth of S. aureus in the presence of selenium nanoparticles after 3, 4, and 5 hours at 7.8, 15.5, and 31 μg/mL. The percentage of live bacteria also decreased in the presence of selenium nanoparticles. Therefore, this study suggests that selenium nanoparticles may be used to effectively prevent and treat S. aureus infections and thus should be further studied for such applications.
Physical chemistry chemical physics : PCCP, Jan 28, 2012
In the drive to devise catalytic systems to convert solar energy into the energy of chemical bond... more In the drive to devise catalytic systems to convert solar energy into the energy of chemical bonds, chemists and electrochemists are seeking inspiration from our understanding of enzymes involved in bioenergetics. This is particularly true for generating molecular hydrogen from high energy electrons derived from solar driven water splitting. In this case the natural enzymes are the [NiFe]- and [FeFe]-hydrogenases. In this article we review our present understanding of the structure and mechanistic functioning of these enzymes and how they are providing a blue print to the design and understanding of the mechanism of a variety of synthesized catalysts for proton reduction chemistry.
Wetting properties of biomaterials, in particular nanomaterials, play an important role, as these... more Wetting properties of biomaterials, in particular nanomaterials, play an important role, as these influence interactions with biological elements, such as proteins, bacteria, and cells. In this study, the wetting phenomenon of titanium substrates coated with selenium nanoparticles was studied using experimental and mathematical modeling tools. Importantly, these selenium-coated titanium substrates were previously reported to increase select protein adsorption (such as vitronectin and fibronectin), to decrease bacteria growth, and increase bone cell growth. Increased selenium nanoparticle coating density resulted in higher contact angles but remained within the hydrophilic regime. This trend was found in disagreement with the Wenzel model, which is widely used to understand the wetting properties of rough surfaces. The trend also did not fit well with the Cassie-Baxter model, which was developed to understand the wetting properties of composite surfaces. A modified wetting model was thus proposed in this study, to understand the contributing factors of material properties to the hydrophilicity/ hydrophobicity of these nanostructured selenium-coated surfaces. The analysis and model created in this study can be useful in designing and/or understanding the wetting behavior of numerous biomedical materials and in turn, biological events (such as protein adsorption as well as bacteria and mammalian cell functions).
Fission yeast cells are rod-shaped unicellular organism that is normally imaged horizontally with... more Fission yeast cells are rod-shaped unicellular organism that is normally imaged horizontally with its long axis parallel to image plane. This orientation, while practical, limits the imaging resolution of biological structures which are oriented perpendicular to the long axis of the cell. We present here a method to prepare agarose pads with micro-sized holes to load single fission yeast cell vertically and image cell with its long axis perpendicular to the image plane. As a demonstration, actomyosin ring contraction is shown with this new imaging device.
Materials science & engineering. C, Materials for biological applications, 2014
The development of smooth, featureless surfaces for biomedical microelectronics is a challenging ... more The development of smooth, featureless surfaces for biomedical microelectronics is a challenging feat. Other than the traditional electronic materials like silicon, few microelectronic circuits can be produced with conductive features without compromising the surface topography and/or biocompatibility. Diamond is fast becoming a highly sought after biomaterial for electrical stimulation, however, its inherent surface roughness introduced by the growth process limits its applications in electronic circuitry. In this study, we introduce a fabrication method for developing conductive features in an insulating diamond substrate whilst maintaining a planar topography. Using a combination of microwave plasma enhanced chemical vapour deposition, inductively coupled plasma reactive ion etching, secondary diamond growth and silicon wet-etching, we have produced a patterned substrate in which the surface roughness at the interface between the conducting and insulating diamond is approximately 3 nm. We also show that the patterned smooth topography is capable of neuronal cell adhesion and growth whilst restricting bacterial adhesion.
Abstract Two common problems with implantation after cancerous tumor resection are cancer recurre... more Abstract Two common problems with implantation after cancerous tumor resection are cancer recurrence and bacteria infection at the implant site. Tumor resection surgery sometimes can not remove all the cancerous cells, thus, cancer can return after ...
Microtubules exhibit dynamic instability, stochastically switching between infrequent phases of g... more Microtubules exhibit dynamic instability, stochastically switching between infrequent phases of growth and shrinkage. In the cell, microtubule dynamic instability is further modulated by microtubule-associated proteins and motors, which are specifically tuned to cell cycle stages. For example, mitotic microtubules are more dynamic than interphase microtubules. The different parameters of microtubule dynamics can be measured from length versus time data, which are generally obtained from time-lapse acquisition using the optical microscope. The typical maximum resolution of the optical microscope is ~λ/2 or ~300 nm. This scale represents a challenge for imaging fission yeast microtubule dynamics specifically during early mitosis, where the bipolar mitotic spindle contains many short dynamic microtubules of ~1-μm scale. Here, we present a novel method to image short fission yeast mitotic microtubules. The method uses the thermosensitive reversible kinesin-5 cut7.24(ts) to create monopolar spindles, where asters of individual mitotic microtubules are presented for imaging and subsequent analysis.
ABSTRACT There are currently no orthopedic materials which are made to prevent either the occurre... more ABSTRACT There are currently no orthopedic materials which are made to prevent either the occurrence or reoccurrence of cancer. Due to the above, the objective of this study was to create a new biomaterial which can both restore bone and, at the same time, prevent cancer growth at the implant interface. In the present study, three types of surfaces with different surface densities were prepared. Competitive cell co-culture studies showed promoted growth of healthy bone cells and inhibited growth of cancerous cells when they were co-seeded on high dose selenium (Se) coated titanium (Ti) substrates. Thus, this study provided for the first time a material to the orthopedic community which may inhibit bone cancer growth and promote healthy bone growth.
Metallic bone implants possess numerous problems limiting their efficacy, such as poor osseointeg... more Metallic bone implants possess numerous problems limiting their efficacy, such as poor osseointegration, stress shielding, and corrosion in in vivo environments. In addition, these materials were not originally developed to simultaneously serve as an orthopedic implant and treat bone cancer (for which some patients require an orthopedic implant). This study is to investigate the potential use of selenium in bone
Until recently, traditional orthopedic implant materials termed bioactive have been engineered ... more Until recently, traditional orthopedic implant materials termed bioactive have been engineered to actively promote integration with living bone. We propose to look beyond this traditional form of bioactivity (specifically for orthopedics, in which bioactivity refers to osseointegration ...
Bacteria colonization on medical devices remains one of the most serious complications following ... more Bacteria colonization on medical devices remains one of the most serious complications following implantation. Traditional antibiotic treatment has proven ineffective, creating an increasingly high number of drug-resistant bacteria. Polymeric medical devices represent a significant portion of the total medical devices used today due to their excellent mechanical properties (such as durability, flexibility, etc). However, many polymers (such as polyvinyl chloride (PVC), polyurethane (PU) and silicone) become readily colonized and infected by bacteria immediately after use. Therefore, in this study, a novel antimicrobial coating was developed to inhibit bacterial growth on PVC, PU and silicone. Specifically, here, the aforementioned polymeric substrates were coated with selenium (Se) nanoparticles in situ. The Se-coated substrates were characterized using scanning electron microscopy, energy dispersive x-ray spectroscopy and bacteria assays. Most importantly, bacterial growth was significantly inhibited on the Se-coated substrates compared to their uncoated counterparts. The reduction of bacteria growth directly correlated with the density of Se nanoparticles on the coated substrate surfaces. In summary, these results demonstrate that Se should be further studied as a novel anti-bacterial polymeric coating material which can decrease bacteria functions without the use of antibiotics.
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