Our previous reports demonstrated an alarming in crease in resistance to adamantanes among influenza A(H3N2) viruses isolated in 2001–2005. To continue monitoring drug resistance, we conducted a ...comprehensive analysis of influenza A(H3N2) and A(H1N1) viruses isolated globally in 2005–2006. The results obtained by pyrosequencing indicate that 96.4% (n=761) of A(H3N2) viruses circulating in the United States were adamantane resistant. Drug resistance has reached 100% among isolates from some Asian countries. Analysis of correlation between the appearance of drug resistance and the evolutionary pathway of the hemagglutinin (HA) gene suggests at least 2 separate introductions of resistance into circulating populations that gave rise to identifiable subclades. It also indicates that resistant A(H3N2) viruses may have emerged in Asia in late 2001. Among A(H1N1) viruses isolated worldwide, resistance reached 15.5% in 2005–2006; in the United States alone, it was 4.0%. Phylogenetic analysis of the HA and M genes indicates that the acquisition of resistance in A(H1N1) viruses can be linked to a specific genetic group and was not a result of reassortment between A(H3N2) and A(H1N1) viruses. The results of the study highlight the necessity of close monitoring of resistance to existing antivirals as wells as the need for new therapeutics.
Adamantanes have been used to treat influenza A virus infections for many years. Studies have shown a low incidence of resistance to these drugs among circulating influenza viruses; however, their ...use is rising worldwide and drug resistance has been reported among influenza A (H5N1) viruses isolated from poultry and human beings in Asia. We sought to assess adamantane resistance among influenza A viruses isolated during the past decade from countries participating in WHO's global influenza surveillance network.
We analysed data for influenza field isolates that were obtained worldwide and submitted to the WHO Collaborating Center for Influenza at the US Centers for Disease Control and Prevention between Oct 1, 1994, and Mar 31, 2005. We used pyrosequencing, confirmatory sequence analysis, and phenotypic testing to detect drug resistance among circulating influenza A H3N2 (n=6524), H1N1 (n=589), and H1N2 (n=83) viruses.
More than 7000 influenza A field isolates were screened for specific aminoacid substitutions in the M2 gene known to confer drug resistance. During the decade of surveillance a significant increase in drug resistance was noted, from 0·4% in 1994–1995 to 12·3% in 2003–2004. This increase in the proportion of resistant viruses was weighted heavily by those obtained from Asia with 61% of resistant viruses isolated since 2003 being from people in Asia.
Our data raise concerns about the appropriate use of adamantanes and draw attention to the importance of tracking the emergence and spread of drug-resistant influenza A viruses.
A periodic sequence of ultrashort superradiance pulses during the current pulse of an electron beam with a duration of about 40 ns has been generated in an experiment with a relativistic ...backward-wave oscillator with wave reflectors at the edges of the electron–wave interaction region. The pulse repetition period has been specified by the electron–wave feedback time and is 5.9 ns, which corresponds to the repetition frequency of 170 MHz at a FWHM duration of about 0.8 ns. The frequency of microwave oscillations is 10 GHz. The peak power of pulses is 0.8–1.3 GW. The corresponding conversion coefficients defined as the ratio of the peak power of the ultrashort microwave pulse to the power of the electron beam are 0.7–1.2.
Practical quantum cryptography Balygin, K. A.; Zaitsev, V. I.; Klimov, A. N. ...
JETP letters,
05/2017, Letnik:
105, Številka:
9
Journal Article
Recenzirano
A quantum cryptography system based on a 4-basis protocol with geometrically uniform states is tested in a series of experiments. Quantum states of light transmitted through real fiber optic ...communication channels to a distance of 32 km in the presence of uncontrolled external actions are prepared, transformed, and measured. It is shown that the chosen algorithms of processing quantum information are adequate and can be used as foundations of practical devices in protected communication lines.
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The adamantanes, amantadine and rimantadine, have been used as first-choice antiviral drugs against community outbreaks of influenza A viruses for many years. Rates of viruses resistant to these ...drugs have been increasing globally. Rapid surveillance for the emergence and spread of resistant viruses has become critical for appropriate treatment of patients.
To investigate the frequency of adamantane-resistant influenza A viruses circulating in the United States during the initial months of the 2005-2006 influenza season.
Influenza isolates collected from 26 states from October 1 through December 31, 2005, and submitted to the US Centers for Disease Control and Prevention were tested for drug resistance as part of ongoing surveillance. Isolates were submitted from World Health Organization collaborating laboratories and National Respiratory and Enteric Virus Surveillance System laboratories.
Using pyrosequencing and confirmatory assays, we identified viruses containing mutations within the M2 gene that are known to confer resistance to both amantadine and rimantadine.
A total of 209 influenza A(H3N2) viruses isolated from patients in 26 states were screened, of which 193 (92.3%) contained a change at amino acid 31 (serine to asparagine S31N) in the M2 gene known to be correlated with adamantane resistance. Two of 8 influenza A(H1N1) viruses contained the same mutation. Drug-resistant viruses were distributed across the United States.
The high proportion of influenza A viruses currently circulating in the United States demonstrating adamantane resistance highlights the clinical importance of rapid surveillance for antiviral resistance. Our results indicate that these drugs should not be used for the treatment or prophylaxis of influenza in the United States until susceptibility to adamantanes has been reestablished among circulating influenza A isolates.
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•Different shapes of commercial catalyst were tested under particulates trapping.•The developed discrete model allows simulating clogging of hydrotreating reactor.•VGO hydrotreating ...reactor was simulated based on experimental filter coefficients.•Optimized scheme of guard-beds demonstrated the lowest pressure drop.
A new approach to optimize grading guard systems for gas oil hydrotreating reactor based on the phenomenon of clogging of catalyst beds with microparticulates and coke deposits was developed. Pellets with different shapes have been tested to obtain dynamic dependencies of filter coefficient and pressure drop buildup. The experiments were performed in the trickle-flow regime with different ensembles of microparticulates having sizes from 15 to 165 μm. The observed effect of a filter cake formation was characterized in terms of average porosity of the interface beds and it was introduced in simulations plugging of catalyst bed. Estimation of the growth of coke deposits was made using modified Voorhies’s equation and experimental samples obtained in the microreactor under hydrotreating process conditions using foulants of industrial gas oil hydrotreater. The analysis of coked samples was carried out using TGA. Based on the discrete model and experimental data, optimization procedure of grading guard systems was carried out using brute force search. All combinations of schemes of guard-beds were compared using integrated hydrodynamic resistance as a criterion. It was shown that an optimized scheme of guard-beds can reduce hydrodynamic resistance as compared to the schemes without guard-beds or with non-optimized guard-beds.
Transmission of Equine Influenza Virus to Dogs Crawford, P. C.; Dubovi, Edward J.; Castleman, William L. ...
Science (American Association for the Advancement of Science),
10/2005, Letnik:
310, Številka:
5747
Journal Article
Recenzirano
Molecular and antigenic analyses of three influenza viruses isolated from outbreaks of severe respiratory disease in racing greyhounds revealed that they are closely related to H3N8 equine influenza ...virus. Phylogenetic analysis indicated that the canine influenza virus genomes form a monophyletic group, consistent with a single interspecies virus transfer. Molecular changes in the hemagglutinin suggested adaptive evolution in the new host. The etiologic role of this virus in respiratory disease was supported by the temporal association of rising antibody titers with disease and by experimental inoculation studies. The geographic expansion of the infection and its persistence for several years indicate efficient transmission of canine influenza virus among greyhounds. Evidence of infection in pet dogs suggests that this infection may also become enzootic in this population.
A method for triggering a laser synchro-signal diode in a single-pass quantum cryptographic system is proposed. The method allows reducing the level of stray influence in an optical fiber from ...scattered laser radiation by
2 orders of magnitude and increasing the length of a single-fiber communication line when generating a secret key to 95 km.
It was previously shown that hemagglutinin residues Thrl55, Glul58, and Ser228 are crucial for the recognition of Neu5Gc. In this study, we demonstrated that the ability to bind the Neu5Gc-terminated ...receptor is related to the amino acid 145: viruses of years 1972–1999 with Lysl45bindto the receptor, whereas viruses with Asnl 45 do not. Sporadic appearance and disappearance of the ability to bind Neu5Gc oligosaccharides and the absence of Neu5Gc in the composition of human glycoconjugates indicate the non-adaptive nature of this ability. It was previously shown that unlike H1N1 viruses, H3N2 viruses of years 1968–1989 did not distinguish between Neu5Acα2-6Galβ1-4Glc (6′SL) and Neu5Acα2-6Galβ1-4GlcNAc (6′SLN). H3N2 viruses isolated after 1993 have acquired the ability to distinguish between 6’SL and 6′SLN, similarly to H1N1 viruses. We found that the affinity for 6′SLN has gradually increased from 1992 to 2003. After 2003, the viruses lost the ability to bind a number of sialosides, including 6′SL, that were good receptors for earlier H3N2 viruses, and retained high affinity for 6′SLN only, which correlated with the acquisition of new glycosylation sites at positions 122, 133, and 144, as well as Glul90Asp and Gly225Asp substitutions, in hemagglutinin. These substitutions are also responsible for the receptor-binding phenotype of human H1N1 viruses. We conclude that the convergent evolution of the receptor specificity of the H1N1 and H3N2 viruses indicates that 6’SLN is the optimal natural human receptor for influenza viruses.
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