Hung-ta Chou - Academia.edu (original) (raw)

Papers by Hung-ta Chou

Research paper thumbnail of Application of Multispectral Sensors Carried on Unmanned Aerial Vehicle (UAV) to Trophic State Mapping of Small Reservoirs: A Case Study of Tain-Pu Reservoir in Kinmen, Taiwan

Research paper thumbnail of A micro-machined cantilever PSA sensor with digital wireless interface

2006 Asia-Pacific Microwave Conference, 2006

A reusable miniature silicon sensor for prostate-specific antigen (PSA) is implemented. A micro-m... more A reusable miniature silicon sensor for prostate-specific antigen (PSA) is implemented. A micro-machined cantilever beam is fabricated as the basis of this sensor by photo-lithography. An 8-bit successive approximation analog-to-digital converter (SAR ADC) and an on-off-keying digital wireless transmitter are integrated to enable wireless data transmission. The detectable PSA solution ranges from 0.1 mug/ml to 200 mug/ml. Wireless interface is

Research paper thumbnail of Interaction of cationic antimicrobial peptides with phospholipid vesicles and their antibacterial activity

Peptides, 2010

We have designed and synthesized a series of cationic ␣-helical AMPs with improved antibacterial ... more We have designed and synthesized a series of cationic ␣-helical AMPs with improved antibacterial activity and selectivity against a broad spectrum of G(+) and G(−) bacteria. In the current study, we intended to gain further insight into the mechanisms of action between AMPs and cellular membranes using model liposomes of various phospholipid compositions. Circular dichroism measurements showed that AMPs adopted amphipathic ␣-helical conformation in the presence of negatively charged vesicles (DOPC/DOPG = 1:3), while they were largely unstructured when incubated with neutral vesicles (DOPC). The interaction of AMPs with phospholipid vesicles were further analyzed by calcein leakage experiments. AMPs exhibited weak dye-leakage activity for DOPC (neutral) vesicles, while they effectively induced calcein leakage when interacted with DOPC/DOPG-entrapped vesicles. These results indicated that our newly designed cationic AMPs did show preferences for bacteria-mimicking anionic membranes. All of them exert their cytolytic activity by folding into an amphipathic helix upon selectively binding and insertion into the target membrane, leading to breakdown of the membrane structure, thus causing leakage of cell contents, resulting finally in cell death. Elucidating the mechanism of the membranolytic activity of AMPs may facilitate the development of more effective antimicrobial agents.

Research paper thumbnail of Design and synthesis of cationic antimicrobial peptides with improved activity and selectivity against Vibrio spp

International Journal of Antimicrobial Agents, 2008

Extensive use of classical antibiotics has led to the growing emergence of many resistant strains... more Extensive use of classical antibiotics has led to the growing emergence of many resistant strains of pathogenic bacteria. Evidence has suggested that cationic antimicrobial peptides (AMPs) are of greatest potential to represent a new class of antibiotics. The largest group of AMPs comprises peptides that fold into an amphipathic ␣-helical conformation when interacting with the target microorganism. In the current study, a series of cationic AMPs of 20 amino acids was designed and synthesised based on four structural parameters, including charge, polar angle, hydrophobicity and hydrophobic moment. The effect of these parameters on antimicrobial activity and selectivity was assessed by structural and biological analyses. Our results indicated that high hydrophobicity and amphipathicity (hydrophobic moment) were correlated with increased haemolytic activity, whilst antimicrobial activity was found to be less dependent on these factors. Three of the synthetic AMPs (GW-Q4, GW-Q6 and GW-H1) showed higher antimicrobial activity and selectivity against a broad spectrum of Gram-positive and Gram-negative bacteria compared with the naturally occurring AMPs magainin 2a and pleurocidin. This study also demonstrates that these rationally designed cationic and amphipathic helical AMPs exhibited high selectivity against several Vibrio spp. and are potential agents for future use in the treatment of these marine pathogens.

Research paper thumbnail of A member of the immunoglobulin superfamily, orange-spotted grouper novel immune gene EcVig, is induced by immune stimulants and type I interferon

Fish & shellfish immunology, Jan 22, 2016

A novel grouper immune gene, EcVig was identified in orange-spotted grouper (Epinephelus coioides... more A novel grouper immune gene, EcVig was identified in orange-spotted grouper (Epinephelus coioides). We recently determined that EcVig expression can be induced by infection with nervous necrosis virus (NNV, an RNA virus), whereas NNV replication may be suppressed when EcVig was overexpressed. Although EcVig appeared to be involved in grouper antiviral activity, its immune effects have not been well characterized. In the present study, two PAMPs (pathogen-associated molecular patterns; lipopolysaccharides [LPS] and synthetic double-stranded RNA polyriboinosinic-polyribocytidylic acid [poly(I:C)]), as well as fish DNA virus (red sea bream iridovirus, RSIV; grouper iridovirus, GIV), were used to study EcVig responses in orange-spotted grouper. In addition, groupers were given recombinant type I interferon to determine whether EcVig expression was induced. Poly(I:C) rapidly induced substantial expression of EcVig, whereas LPS stimulation did not appear to have any effect in grouper inte...

Research paper thumbnail of Application of Multispectral Sensors Carried on Unmanned Aerial Vehicle (UAV) to Trophic State Mapping of Small Reservoirs: A Case Study of Tain-Pu Reservoir in Kinmen, Taiwan

Research paper thumbnail of A micro-machined cantilever PSA sensor with digital wireless interface

2006 Asia-Pacific Microwave Conference, 2006

A reusable miniature silicon sensor for prostate-specific antigen (PSA) is implemented. A micro-m... more A reusable miniature silicon sensor for prostate-specific antigen (PSA) is implemented. A micro-machined cantilever beam is fabricated as the basis of this sensor by photo-lithography. An 8-bit successive approximation analog-to-digital converter (SAR ADC) and an on-off-keying digital wireless transmitter are integrated to enable wireless data transmission. The detectable PSA solution ranges from 0.1 mug/ml to 200 mug/ml. Wireless interface is

Research paper thumbnail of Interaction of cationic antimicrobial peptides with phospholipid vesicles and their antibacterial activity

Peptides, 2010

We have designed and synthesized a series of cationic ␣-helical AMPs with improved antibacterial ... more We have designed and synthesized a series of cationic ␣-helical AMPs with improved antibacterial activity and selectivity against a broad spectrum of G(+) and G(−) bacteria. In the current study, we intended to gain further insight into the mechanisms of action between AMPs and cellular membranes using model liposomes of various phospholipid compositions. Circular dichroism measurements showed that AMPs adopted amphipathic ␣-helical conformation in the presence of negatively charged vesicles (DOPC/DOPG = 1:3), while they were largely unstructured when incubated with neutral vesicles (DOPC). The interaction of AMPs with phospholipid vesicles were further analyzed by calcein leakage experiments. AMPs exhibited weak dye-leakage activity for DOPC (neutral) vesicles, while they effectively induced calcein leakage when interacted with DOPC/DOPG-entrapped vesicles. These results indicated that our newly designed cationic AMPs did show preferences for bacteria-mimicking anionic membranes. All of them exert their cytolytic activity by folding into an amphipathic helix upon selectively binding and insertion into the target membrane, leading to breakdown of the membrane structure, thus causing leakage of cell contents, resulting finally in cell death. Elucidating the mechanism of the membranolytic activity of AMPs may facilitate the development of more effective antimicrobial agents.

Research paper thumbnail of Design and synthesis of cationic antimicrobial peptides with improved activity and selectivity against Vibrio spp

International Journal of Antimicrobial Agents, 2008

Extensive use of classical antibiotics has led to the growing emergence of many resistant strains... more Extensive use of classical antibiotics has led to the growing emergence of many resistant strains of pathogenic bacteria. Evidence has suggested that cationic antimicrobial peptides (AMPs) are of greatest potential to represent a new class of antibiotics. The largest group of AMPs comprises peptides that fold into an amphipathic ␣-helical conformation when interacting with the target microorganism. In the current study, a series of cationic AMPs of 20 amino acids was designed and synthesised based on four structural parameters, including charge, polar angle, hydrophobicity and hydrophobic moment. The effect of these parameters on antimicrobial activity and selectivity was assessed by structural and biological analyses. Our results indicated that high hydrophobicity and amphipathicity (hydrophobic moment) were correlated with increased haemolytic activity, whilst antimicrobial activity was found to be less dependent on these factors. Three of the synthetic AMPs (GW-Q4, GW-Q6 and GW-H1) showed higher antimicrobial activity and selectivity against a broad spectrum of Gram-positive and Gram-negative bacteria compared with the naturally occurring AMPs magainin 2a and pleurocidin. This study also demonstrates that these rationally designed cationic and amphipathic helical AMPs exhibited high selectivity against several Vibrio spp. and are potential agents for future use in the treatment of these marine pathogens.

Research paper thumbnail of A member of the immunoglobulin superfamily, orange-spotted grouper novel immune gene EcVig, is induced by immune stimulants and type I interferon

Fish & shellfish immunology, Jan 22, 2016

A novel grouper immune gene, EcVig was identified in orange-spotted grouper (Epinephelus coioides... more A novel grouper immune gene, EcVig was identified in orange-spotted grouper (Epinephelus coioides). We recently determined that EcVig expression can be induced by infection with nervous necrosis virus (NNV, an RNA virus), whereas NNV replication may be suppressed when EcVig was overexpressed. Although EcVig appeared to be involved in grouper antiviral activity, its immune effects have not been well characterized. In the present study, two PAMPs (pathogen-associated molecular patterns; lipopolysaccharides [LPS] and synthetic double-stranded RNA polyriboinosinic-polyribocytidylic acid [poly(I:C)]), as well as fish DNA virus (red sea bream iridovirus, RSIV; grouper iridovirus, GIV), were used to study EcVig responses in orange-spotted grouper. In addition, groupers were given recombinant type I interferon to determine whether EcVig expression was induced. Poly(I:C) rapidly induced substantial expression of EcVig, whereas LPS stimulation did not appear to have any effect in grouper inte...