To study spin flipping within the antiferromagnet IrMn, we extended prior Current-Perpendicular-t... more To study spin flipping within the antiferromagnet IrMn, we extended prior Current-Perpendicular-to-Plane (CPP) Giant Magnetoresistance (GMR) studies of Py-based exchange-biased-spin-valves containing IrMn inserts to thicker IrMn layers-5 nm less than or equal to t(IrMn) less than or equal to 30 nm. Unexpectedly, A{\Delta}R = A[R(AP) - R(P)]--the difference in specific resistance between the anti-parallel (AP) and parallel (P) magnetic states
Subterranean termite species, their habitat preferences and nest habits at Xuan Son National Park... more Subterranean termite species, their habitat preferences and nest habits at Xuan Son National Park, a lowland and lower mountain evergreen and limestone forest in northern Vietnam, were investigated in 2002 and 2003. A total of 234 collections were obtained from 588 sampling sites, on 12 transects, among four different habitat types. Fifteen species in eight genera and two families were recorded. Termitidae was the dominant family with six genera and 12 species. The genus Odontotermes with five species contained the most abundant species. Five species were new records for northern Vietnam: Odontotermes maesodensis Ahmad, 1965, Nasutitermes ovatus Fan, 1983, Pericaptitermes latignathus (Holmgren, 1913), Pericaptitermes nitobei Shiraki, 1909 and Bulbitermes laticephalus Ahmad, 1965. The inventory included eight fungus-growing species: Macrotermes barneyi Light, 1924, Ma. annandalei (Silvestri, 1914), O. yunnanensis Tsai et Chen, 1963, O. hainanensis Light, 1924, O. formosanus Sharaki, 1909, O. maesodensis Ahmad, 1965, O. graveli (Silvestri, 1914) and Microtermes pakistanicus Ahmad, 1965. Five species: M. barneyi, O. yunnanensis, O. hainanensis, O. formosanus and M. pakistanicus occurred in all habitat types. The scrubland/grassland habitat contained 14 species, forest habitats 12 species, cultivated lands eight species and residential areas contained only six species. In forest habitats 56.2% of sample plots yielded termites, in scrubland/grasslands 54.5%, 32% of plots on cultivated land produced termites and in residential habitats only 18% had termites. Six species identified are considered special pests because their activities weaken earthen structures: M. pakistanicus, M. barneyi, M. annandalei, O. yunnanensis, O. hainanensis and O. formosanus. Nesting patterns of surveyed species are noted with special attention to species that inhabit earthen structures.
Gram-positive bacteria code for one or more enzymes termed sortases which catalyze the covalent a... more Gram-positive bacteria code for one or more enzymes termed sortases which catalyze the covalent anchoring of substrate proteins on their cell wall. They recognize an amino acid sequence designated sorting motif, present close to the C-terminal end of the substrate proteins, cleave within this motif and catalyze anchoring of the polypeptide chain to the peptide crossbridge linking the peptidoglycan strands in a transpeptidation reaction. Bacillus subtilis has been reported to code for two different sortases but the sorting sequences recognized by them are yet unknown. To be able to immobilize proteins on the surface of B. subtilis cells, we introduced the srtA gene coding for sortase A of Listeria monocytogenes with the known sorting motif (LPXTG) into B. subtilis. L. monocytogenes and B. subtilis share the same peptide crossbridge. Next, we fused the coding region of an alpha-amylase gene to the C-terminal region of Staphylococcus aureus fibronectin binding protein B containing the ...
The aim of this study was to determine the intracellular activity of moxifloxacin against a refer... more The aim of this study was to determine the intracellular activity of moxifloxacin against a reference strain and a clinical strain and to study the factors compromising the intracellular activity of moxifloxacin. The bactericidal activity of moxifloxacin at therapeutic concentrations was studied against extracellular (broth) and intracellular (infected THP-1 monocytes) forms of Staphylococcus aureus and compared with that of levofloxacin. The activity of moxifloxacin was also evaluated in the presence of alkalinizing agents, in intracellular salt medium mimicking the phagolysosomal environment and in cell lysate. Moxifloxacin, bactericidal against two S. aureus strains (ATCC 25923 and a clinical isolate, Sa2669) in broth, accumulated over 6-fold in monocytes. Against intracellular bacteria, moxifloxacin displayed a markedly reduced activity, not better than levofloxacin, with a maximal reduction of 1 log(10) cfu at 5 h. Cellular accumulation of moxifloxacin was not modified by the a...
Small-colony variant (SCV) strains of Staphylococcus aureus show reduced antibiotic susceptibilit... more Small-colony variant (SCV) strains of Staphylococcus aureus show reduced antibiotic susceptibility and intracellular persistence, potentially explaining therapeutic failures. The activities of oxacillin, fusidic acid, clindamycin, gentamicin, rifampin, vancomycin, linezolid, quinupristin-dalfopristin, daptomycin, tigecycline, moxifloxacin, telavancin, and oritavancin have been examined in THP-1 macrophages infected by a stable thymidine-dependent SCV strain in comparison with normal-phenotype and revertant isogenic strains isolated from the same cystic fibrosis patient. The SCV strain grew slowly extracellularly and intracellularly (1- and 0.2-log CFU increase in 24 h, respectively). In confocal and electron microscopy, SCV and the normal-phenotype bacteria remain confined in acid vacuoles. All antibiotics tested, except tigecycline, caused a net reduction in bacterial counts that was both time and concentration dependent. At an extracellular concentration corresponding to the maxim...
In a companion paper (H. A. Nguyen et al., Antimicrob. Agents Chemother. 53:1434-1442, 2009), we ... more In a companion paper (H. A. Nguyen et al., Antimicrob. Agents Chemother. 53:1434-1442, 2009), we showed that vancomycin, oxacillin, fusidic acid, clindamycin, linezolid, and daptomycin are poorly active against the intracellular form of a thymidine-dependent small-colony variant (SCV) strain isolated from a cystic fibrosis patient and that the activity of quinupristin-dalfopristin, moxifloxacin, rifampin, and oritavancin remains limited (2- to 3-log CFU reduction) compared to their extracellular activity. Antibiotic combination is a well-known strategy to improve antibacterial activity, which was examined here against an intracellular SCV strain using combinations with either rifampin or oritavancin. Time-kill curve analysis using either concentrations that caused a static effect for each antibiotic individually or concentrations corresponding to the maximum concentration in human serum showed largely divergent effects that were favorable when antibiotics were combined with rifampin...
Streptomyces ambofaciens synthesizes spiramycin, a 16-membered macrolide antibiotic used in human... more Streptomyces ambofaciens synthesizes spiramycin, a 16-membered macrolide antibiotic used in human medicine. The spiramycin molecule consists of a polyketide lactone ring (platenolide) synthesized by a type I polyketide synthase, to which three deoxyhexoses (mycaminose, forosamine, and mycarose) are attached successively in this order. These sugars are essential to the antibacterial activity of spiramycin. We previously identified four genes in the spiramycin biosynthetic gene cluster predicted to encode glycosyltransferases. We individually deleted each of these four genes and showed that three of them were required for spiramycin biosynthesis. The role of each of the three glycosyltransferases in spiramycin biosynthesis was determined by identifying the biosynthetic intermediates accumulated by the corresponding mutant strains. This led to the identification of the glycosyltransferase responsible for the attachment of each of the three sugars. Moreover, two genes encoding putative ...
Perioperative hypothermia has been reported to increase the occurrence of cardiovascular complica... more Perioperative hypothermia has been reported to increase the occurrence of cardiovascular complications. By increasing the activity of sympathetic nervous system, perioperative hypothermia also has the potential to increase cardiac injury and dysfunction associated with subarachnoid hemorrhage. The Intraoperative Hypothermia for Aneurysm Surgery Trial randomized patients undergoing cerebral aneurysm surgery to intraoperative hypothermia (n = 499, 33.3 degrees +/- 0.8 degrees C) or normothermia (n = 501, 36.7 degrees +/- 0.5 degrees C). Cardiovascular events (hypotension, arrhythmias, vasopressor use, myocardial infarction, and others) were prospectively followed until 3-month follow-up and were compared in hypothermic and normothermic patients. A subset of 62 patients (hypothermia, n = 33; normothermia, n = 29) also had preoperative and postoperative (within 24 h) measurement of cardiac troponin-I and echocardiography to explore the association between perioperative hypothermia and s...
The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technol... more The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technology means that a large amount of data from each pixel in the image needs to be processed rapidly and system resources need to be used efficiently. Conventional processing algorithms that are utilized in single point or scanning systems are therefore not an ideal solution as they will consume too much system resource. Two processing algorithms that address this problem are described and efficiently implemented in a field programmable gate array. The algorithms are simple enough to use low system resource but effective enough to produce accurate flow measurements. This enables the processing unit to be integrated entirely in an embedded system, such as in an application-specific integrated circuit. The first algorithm uses a short Fourier transformation length (typically 8) but averages the output multiple times (typically 128). The second method utilizes an infinite impulse response filte...
The gene chi, coding for a GH18 chitinase from the Gram-positive bacterium Bacillus licheniformis... more The gene chi, coding for a GH18 chitinase from the Gram-positive bacterium Bacillus licheniformis DSM13 (ATCC 14580), was cloned into the inducible lactobacillal expression vectors pSIP403 and pSIP409, derived from the sakacin-P operon of Lactobacillus sakei, and expressed in the host strain Lactobacillus plantarum WCFS1. Both the complete chi gene including the original bacillal signal sequence as well as the mature chi gene were compared, however, no extracellular chitinase activity was detected with any of the constructs. The chitinase gene was expressed intracellularly as an active enzyme with these different systems, at levels of approximately 5mg of recombinant protein per litre of cultivation medium. Results obtained for the two different expression vectors that only differ in the promoter sequence were well comparable. To further verify the suitability of this expression system, recombinant, His-tagged chitinase Chi was purified from cell extracts of L. plantarum and charact...
The survival characteristics of the mosquito Aedes aegypti affect transmission rates of dengue be... more The survival characteristics of the mosquito Aedes aegypti affect transmission rates of dengue because transmission requires infected mosquitoes to survive long enough for the virus to infect the salivary glands. Mosquito survival is assumed to be high in tropical, dengue endemic, countries like Vietnam. However, the survival rates of wild populations of mosquitoes are seldom measured due the difficulty of predicting mosquito age. Hon Mieu Island in central Vietnam is the site of a pilot release of Ae. aegypti infected with a strain of Wolbachia pipientis bacteria (wMelPop) that induces virus interference and mosquito life-shortening. We used the most accurate mosquito age grading approach, transcriptional profiling, to establish the survival patterns of the mosquito population from the population age structure. Furthermore, estimations were validated on mosquitoes released into a large semi-field environment consisting of an enclosed house, garden and yard to incorporate natural en...
Homologous recombination is a crucial mechanism that repairs a wide range of DNA lesions, includi... more Homologous recombination is a crucial mechanism that repairs a wide range of DNA lesions, including the most deleterious ones, double-strand breaks (DSBs). This multistep process is initiated by the resection of the broken DNA ends by a multisubunit helicase-nuclease complex exemplified by Escherichia coli RecBCD, Bacillus subtilis AddAB, and newly discovered Mycobacterium tuberculosis AdnAB. Here we show that in Streptomyces, neither recBCD nor addAB homologues could be detected. The only putative helicase-nuclease-encoding genes identified were homologous to M. tuberculosis adnAB genes. These genes are conserved as a single copy in all sequenced genomes of Streptomyces. The disruption of adnAB in Streptomyces ambofaciens and Streptomyces coelicolor could not be achieved unless an ectopic copy was provided, indicating that adnAB is essential for growth. Both adnA and adnB genes were shown to be inducible in response to DNA damage (mitomycin C) and to be independently transcribed. I...
We describe the construction of six novel plasmid-based IPTG-inducible expression vectors for Bac... more We describe the construction of six novel plasmid-based IPTG-inducible expression vectors for Bacillus subtilis and related species. While one vector allows intracellular production of recombinant proteins, the second provides a strong secretion signal. The third vector allows addition of the c-Myc epitope tag, and the remaining three vectors provide the purification tags His and Strep. The versatility of all six
In the last three decades, the transboundary Red River basin (169,000 km² at the sea outlet inclu... more In the last three decades, the transboundary Red River basin (169,000 km² at the sea outlet including the Thai Binh river system) and its tributaries, as the Lo river (38,165 km² at the Viet Tri outlet), in the northern part of Vietnam, have experienced significant changes with the construction of major reservoirs for hydropower, flood control and irrigation purposes. Because
Temperature-dependent photoluminescence (PL) of graphene oxide (GO) reduced with hydrazine and he... more Temperature-dependent photoluminescence (PL) of graphene oxide (GO) reduced with hydrazine and heat has been measured to investigate the effect of reduction type on the bandgap of the reduced GO. Nitrogen functionalities formed in the hydrazine-treated GO were responsible for a strong localization of carriers that caused in a fluctuation in PL peak position with temperature. The intensity of C-OH peak
... Condensed Matter Physics, Universidade de Brasilia, Caixa Postal 0+667, 70919-900 Brasilia-DF... more ... Condensed Matter Physics, Universidade de Brasilia, Caixa Postal 0+667, 70919-900 Brasilia-DF, Brazil NGUYEN TRUNG DAN Department of ... nonequilibrium phase transition in physical systems far away from thermal equilibrium was first theoret-ically predicted by Szoke ...
We have developed improved cavity-finesse methods for characterizing the diffraction efficiencies... more We have developed improved cavity-finesse methods for characterizing the diffraction efficiencies of large gratings at the Littrow angle. These methods include measuring cavity length with optical techniques, using a Michelson interferometer to calibrate piezoelectric transducer nonlinearities and angle-tuning procedures to confirm optimal alignment. We used these methods to characterize two 20 cm scale dielectric gratings.
Journal of the American Society of Nephrology, 2006
Differences in coronary disease have been reported among ethnic minorities in the US population. ... more Differences in coronary disease have been reported among ethnic minorities in the US population. Whether these persist in patients with chronic kidney disease is unknown. The prevalence of myocardial infarction (MI) and angina was compared by race and GFR in the Third National Health and Nutrition Examination Survey using the Modification of Diet in Renal Disease Study equation. Age-gender standardized estimates were computed for each GFR category (>90, 60 to 89, and <60 ml/min per 1.73 m 2 ), and odds ratios were compared using weighted multivariable logistic regression for each race. The age-gender standardized prevalence of MI was 3.0, 3.1, and 4.9% in white individuals; 2.8, 3.8, and 9.9% in black individuals; and 1.9, 2.9, and 3.8% in Mexican-American individuals in each category: >90, 60 to 89, and <60 ml/min, respectively. Compared with the referent (Mexican-American; GFR >90 ml/min; odds ratio 1.00), Mexican-American individuals with GFR of 60 to 89 and <60 ml/min had more than four and nine times the odds for MI; black individuals at successively lower GFR levels had 1.6, 6.1, and 16.3 times the odds for MI, whereas white individuals had 1.9, 4.7, and 20.2 times that of the referent, respectively. After adjustment for traditional risk factors, the inverse association of GFR with MI was substantially attenuated in black and white individuals and completely abolished in Mexican-American individuals. The burden of coronary disease is lower in Mexican-American than in white or black individuals with reduced kidney function even accounting for differences in traditional risk factors.
To study spin flipping within the antiferromagnet IrMn, we extended prior Current-Perpendicular-t... more To study spin flipping within the antiferromagnet IrMn, we extended prior Current-Perpendicular-to-Plane (CPP) Giant Magnetoresistance (GMR) studies of Py-based exchange-biased-spin-valves containing IrMn inserts to thicker IrMn layers-5 nm less than or equal to t(IrMn) less than or equal to 30 nm. Unexpectedly, A{\Delta}R = A[R(AP) - R(P)]--the difference in specific resistance between the anti-parallel (AP) and parallel (P) magnetic states
Subterranean termite species, their habitat preferences and nest habits at Xuan Son National Park... more Subterranean termite species, their habitat preferences and nest habits at Xuan Son National Park, a lowland and lower mountain evergreen and limestone forest in northern Vietnam, were investigated in 2002 and 2003. A total of 234 collections were obtained from 588 sampling sites, on 12 transects, among four different habitat types. Fifteen species in eight genera and two families were recorded. Termitidae was the dominant family with six genera and 12 species. The genus Odontotermes with five species contained the most abundant species. Five species were new records for northern Vietnam: Odontotermes maesodensis Ahmad, 1965, Nasutitermes ovatus Fan, 1983, Pericaptitermes latignathus (Holmgren, 1913), Pericaptitermes nitobei Shiraki, 1909 and Bulbitermes laticephalus Ahmad, 1965. The inventory included eight fungus-growing species: Macrotermes barneyi Light, 1924, Ma. annandalei (Silvestri, 1914), O. yunnanensis Tsai et Chen, 1963, O. hainanensis Light, 1924, O. formosanus Sharaki, 1909, O. maesodensis Ahmad, 1965, O. graveli (Silvestri, 1914) and Microtermes pakistanicus Ahmad, 1965. Five species: M. barneyi, O. yunnanensis, O. hainanensis, O. formosanus and M. pakistanicus occurred in all habitat types. The scrubland/grassland habitat contained 14 species, forest habitats 12 species, cultivated lands eight species and residential areas contained only six species. In forest habitats 56.2% of sample plots yielded termites, in scrubland/grasslands 54.5%, 32% of plots on cultivated land produced termites and in residential habitats only 18% had termites. Six species identified are considered special pests because their activities weaken earthen structures: M. pakistanicus, M. barneyi, M. annandalei, O. yunnanensis, O. hainanensis and O. formosanus. Nesting patterns of surveyed species are noted with special attention to species that inhabit earthen structures.
Gram-positive bacteria code for one or more enzymes termed sortases which catalyze the covalent a... more Gram-positive bacteria code for one or more enzymes termed sortases which catalyze the covalent anchoring of substrate proteins on their cell wall. They recognize an amino acid sequence designated sorting motif, present close to the C-terminal end of the substrate proteins, cleave within this motif and catalyze anchoring of the polypeptide chain to the peptide crossbridge linking the peptidoglycan strands in a transpeptidation reaction. Bacillus subtilis has been reported to code for two different sortases but the sorting sequences recognized by them are yet unknown. To be able to immobilize proteins on the surface of B. subtilis cells, we introduced the srtA gene coding for sortase A of Listeria monocytogenes with the known sorting motif (LPXTG) into B. subtilis. L. monocytogenes and B. subtilis share the same peptide crossbridge. Next, we fused the coding region of an alpha-amylase gene to the C-terminal region of Staphylococcus aureus fibronectin binding protein B containing the ...
The aim of this study was to determine the intracellular activity of moxifloxacin against a refer... more The aim of this study was to determine the intracellular activity of moxifloxacin against a reference strain and a clinical strain and to study the factors compromising the intracellular activity of moxifloxacin. The bactericidal activity of moxifloxacin at therapeutic concentrations was studied against extracellular (broth) and intracellular (infected THP-1 monocytes) forms of Staphylococcus aureus and compared with that of levofloxacin. The activity of moxifloxacin was also evaluated in the presence of alkalinizing agents, in intracellular salt medium mimicking the phagolysosomal environment and in cell lysate. Moxifloxacin, bactericidal against two S. aureus strains (ATCC 25923 and a clinical isolate, Sa2669) in broth, accumulated over 6-fold in monocytes. Against intracellular bacteria, moxifloxacin displayed a markedly reduced activity, not better than levofloxacin, with a maximal reduction of 1 log(10) cfu at 5 h. Cellular accumulation of moxifloxacin was not modified by the a...
Small-colony variant (SCV) strains of Staphylococcus aureus show reduced antibiotic susceptibilit... more Small-colony variant (SCV) strains of Staphylococcus aureus show reduced antibiotic susceptibility and intracellular persistence, potentially explaining therapeutic failures. The activities of oxacillin, fusidic acid, clindamycin, gentamicin, rifampin, vancomycin, linezolid, quinupristin-dalfopristin, daptomycin, tigecycline, moxifloxacin, telavancin, and oritavancin have been examined in THP-1 macrophages infected by a stable thymidine-dependent SCV strain in comparison with normal-phenotype and revertant isogenic strains isolated from the same cystic fibrosis patient. The SCV strain grew slowly extracellularly and intracellularly (1- and 0.2-log CFU increase in 24 h, respectively). In confocal and electron microscopy, SCV and the normal-phenotype bacteria remain confined in acid vacuoles. All antibiotics tested, except tigecycline, caused a net reduction in bacterial counts that was both time and concentration dependent. At an extracellular concentration corresponding to the maxim...
In a companion paper (H. A. Nguyen et al., Antimicrob. Agents Chemother. 53:1434-1442, 2009), we ... more In a companion paper (H. A. Nguyen et al., Antimicrob. Agents Chemother. 53:1434-1442, 2009), we showed that vancomycin, oxacillin, fusidic acid, clindamycin, linezolid, and daptomycin are poorly active against the intracellular form of a thymidine-dependent small-colony variant (SCV) strain isolated from a cystic fibrosis patient and that the activity of quinupristin-dalfopristin, moxifloxacin, rifampin, and oritavancin remains limited (2- to 3-log CFU reduction) compared to their extracellular activity. Antibiotic combination is a well-known strategy to improve antibacterial activity, which was examined here against an intracellular SCV strain using combinations with either rifampin or oritavancin. Time-kill curve analysis using either concentrations that caused a static effect for each antibiotic individually or concentrations corresponding to the maximum concentration in human serum showed largely divergent effects that were favorable when antibiotics were combined with rifampin...
Streptomyces ambofaciens synthesizes spiramycin, a 16-membered macrolide antibiotic used in human... more Streptomyces ambofaciens synthesizes spiramycin, a 16-membered macrolide antibiotic used in human medicine. The spiramycin molecule consists of a polyketide lactone ring (platenolide) synthesized by a type I polyketide synthase, to which three deoxyhexoses (mycaminose, forosamine, and mycarose) are attached successively in this order. These sugars are essential to the antibacterial activity of spiramycin. We previously identified four genes in the spiramycin biosynthetic gene cluster predicted to encode glycosyltransferases. We individually deleted each of these four genes and showed that three of them were required for spiramycin biosynthesis. The role of each of the three glycosyltransferases in spiramycin biosynthesis was determined by identifying the biosynthetic intermediates accumulated by the corresponding mutant strains. This led to the identification of the glycosyltransferase responsible for the attachment of each of the three sugars. Moreover, two genes encoding putative ...
Perioperative hypothermia has been reported to increase the occurrence of cardiovascular complica... more Perioperative hypothermia has been reported to increase the occurrence of cardiovascular complications. By increasing the activity of sympathetic nervous system, perioperative hypothermia also has the potential to increase cardiac injury and dysfunction associated with subarachnoid hemorrhage. The Intraoperative Hypothermia for Aneurysm Surgery Trial randomized patients undergoing cerebral aneurysm surgery to intraoperative hypothermia (n = 499, 33.3 degrees +/- 0.8 degrees C) or normothermia (n = 501, 36.7 degrees +/- 0.5 degrees C). Cardiovascular events (hypotension, arrhythmias, vasopressor use, myocardial infarction, and others) were prospectively followed until 3-month follow-up and were compared in hypothermic and normothermic patients. A subset of 62 patients (hypothermia, n = 33; normothermia, n = 29) also had preoperative and postoperative (within 24 h) measurement of cardiac troponin-I and echocardiography to explore the association between perioperative hypothermia and s...
The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technol... more The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technology means that a large amount of data from each pixel in the image needs to be processed rapidly and system resources need to be used efficiently. Conventional processing algorithms that are utilized in single point or scanning systems are therefore not an ideal solution as they will consume too much system resource. Two processing algorithms that address this problem are described and efficiently implemented in a field programmable gate array. The algorithms are simple enough to use low system resource but effective enough to produce accurate flow measurements. This enables the processing unit to be integrated entirely in an embedded system, such as in an application-specific integrated circuit. The first algorithm uses a short Fourier transformation length (typically 8) but averages the output multiple times (typically 128). The second method utilizes an infinite impulse response filte...
The gene chi, coding for a GH18 chitinase from the Gram-positive bacterium Bacillus licheniformis... more The gene chi, coding for a GH18 chitinase from the Gram-positive bacterium Bacillus licheniformis DSM13 (ATCC 14580), was cloned into the inducible lactobacillal expression vectors pSIP403 and pSIP409, derived from the sakacin-P operon of Lactobacillus sakei, and expressed in the host strain Lactobacillus plantarum WCFS1. Both the complete chi gene including the original bacillal signal sequence as well as the mature chi gene were compared, however, no extracellular chitinase activity was detected with any of the constructs. The chitinase gene was expressed intracellularly as an active enzyme with these different systems, at levels of approximately 5mg of recombinant protein per litre of cultivation medium. Results obtained for the two different expression vectors that only differ in the promoter sequence were well comparable. To further verify the suitability of this expression system, recombinant, His-tagged chitinase Chi was purified from cell extracts of L. plantarum and charact...
The survival characteristics of the mosquito Aedes aegypti affect transmission rates of dengue be... more The survival characteristics of the mosquito Aedes aegypti affect transmission rates of dengue because transmission requires infected mosquitoes to survive long enough for the virus to infect the salivary glands. Mosquito survival is assumed to be high in tropical, dengue endemic, countries like Vietnam. However, the survival rates of wild populations of mosquitoes are seldom measured due the difficulty of predicting mosquito age. Hon Mieu Island in central Vietnam is the site of a pilot release of Ae. aegypti infected with a strain of Wolbachia pipientis bacteria (wMelPop) that induces virus interference and mosquito life-shortening. We used the most accurate mosquito age grading approach, transcriptional profiling, to establish the survival patterns of the mosquito population from the population age structure. Furthermore, estimations were validated on mosquitoes released into a large semi-field environment consisting of an enclosed house, garden and yard to incorporate natural en...
Homologous recombination is a crucial mechanism that repairs a wide range of DNA lesions, includi... more Homologous recombination is a crucial mechanism that repairs a wide range of DNA lesions, including the most deleterious ones, double-strand breaks (DSBs). This multistep process is initiated by the resection of the broken DNA ends by a multisubunit helicase-nuclease complex exemplified by Escherichia coli RecBCD, Bacillus subtilis AddAB, and newly discovered Mycobacterium tuberculosis AdnAB. Here we show that in Streptomyces, neither recBCD nor addAB homologues could be detected. The only putative helicase-nuclease-encoding genes identified were homologous to M. tuberculosis adnAB genes. These genes are conserved as a single copy in all sequenced genomes of Streptomyces. The disruption of adnAB in Streptomyces ambofaciens and Streptomyces coelicolor could not be achieved unless an ectopic copy was provided, indicating that adnAB is essential for growth. Both adnA and adnB genes were shown to be inducible in response to DNA damage (mitomycin C) and to be independently transcribed. I...
We describe the construction of six novel plasmid-based IPTG-inducible expression vectors for Bac... more We describe the construction of six novel plasmid-based IPTG-inducible expression vectors for Bacillus subtilis and related species. While one vector allows intracellular production of recombinant proteins, the second provides a strong secretion signal. The third vector allows addition of the c-Myc epitope tag, and the remaining three vectors provide the purification tags His and Strep. The versatility of all six
In the last three decades, the transboundary Red River basin (169,000 km² at the sea outlet inclu... more In the last three decades, the transboundary Red River basin (169,000 km² at the sea outlet including the Thai Binh river system) and its tributaries, as the Lo river (38,165 km² at the Viet Tri outlet), in the northern part of Vietnam, have experienced significant changes with the construction of major reservoirs for hydropower, flood control and irrigation purposes. Because
Temperature-dependent photoluminescence (PL) of graphene oxide (GO) reduced with hydrazine and he... more Temperature-dependent photoluminescence (PL) of graphene oxide (GO) reduced with hydrazine and heat has been measured to investigate the effect of reduction type on the bandgap of the reduced GO. Nitrogen functionalities formed in the hydrazine-treated GO were responsible for a strong localization of carriers that caused in a fluctuation in PL peak position with temperature. The intensity of C-OH peak
... Condensed Matter Physics, Universidade de Brasilia, Caixa Postal 0+667, 70919-900 Brasilia-DF... more ... Condensed Matter Physics, Universidade de Brasilia, Caixa Postal 0+667, 70919-900 Brasilia-DF, Brazil NGUYEN TRUNG DAN Department of ... nonequilibrium phase transition in physical systems far away from thermal equilibrium was first theoret-ically predicted by Szoke ...
We have developed improved cavity-finesse methods for characterizing the diffraction efficiencies... more We have developed improved cavity-finesse methods for characterizing the diffraction efficiencies of large gratings at the Littrow angle. These methods include measuring cavity length with optical techniques, using a Michelson interferometer to calibrate piezoelectric transducer nonlinearities and angle-tuning procedures to confirm optimal alignment. We used these methods to characterize two 20 cm scale dielectric gratings.
Journal of the American Society of Nephrology, 2006
Differences in coronary disease have been reported among ethnic minorities in the US population. ... more Differences in coronary disease have been reported among ethnic minorities in the US population. Whether these persist in patients with chronic kidney disease is unknown. The prevalence of myocardial infarction (MI) and angina was compared by race and GFR in the Third National Health and Nutrition Examination Survey using the Modification of Diet in Renal Disease Study equation. Age-gender standardized estimates were computed for each GFR category (>90, 60 to 89, and <60 ml/min per 1.73 m 2 ), and odds ratios were compared using weighted multivariable logistic regression for each race. The age-gender standardized prevalence of MI was 3.0, 3.1, and 4.9% in white individuals; 2.8, 3.8, and 9.9% in black individuals; and 1.9, 2.9, and 3.8% in Mexican-American individuals in each category: >90, 60 to 89, and <60 ml/min, respectively. Compared with the referent (Mexican-American; GFR >90 ml/min; odds ratio 1.00), Mexican-American individuals with GFR of 60 to 89 and <60 ml/min had more than four and nine times the odds for MI; black individuals at successively lower GFR levels had 1.6, 6.1, and 16.3 times the odds for MI, whereas white individuals had 1.9, 4.7, and 20.2 times that of the referent, respectively. After adjustment for traditional risk factors, the inverse association of GFR with MI was substantially attenuated in black and white individuals and completely abolished in Mexican-American individuals. The burden of coronary disease is lower in Mexican-American than in white or black individuals with reduced kidney function even accounting for differences in traditional risk factors.
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