Antiviral resistance of influenza A (H3N2) strains isolated in northern Greece between 2004 and 2007.

The prevention and control of influenza with vaccines and antiviral drugs is of great importance. M2 inhibitors, amantadine and rimantadine have been extensively used in some countries. The next generation of antiviral drugs, neuraminidase (NA) inhibitors oseltamivir and zanamivir, are being stockpiled for a potential influenza pandemic. The emergence of resistant strains is thus an important issue. The purpose of this study was to examine the sensitivity to M2 and NA inhibitors of Greek influenza A(H3N2) strains isolated during three influenza seasons between 2004 and 2008 and to determine the phylogenetic clades of those strains. M2 and NA sequences of 34 patient isolates were checked for known resistance mutations. In addition, haemagglutinin (HA) sequences were used to determine the phylogenetic relationship between resistant and sensitive strains. All influenza A(H3N2) strains isolated during the season 2004-5 were found susceptible to adamantanes, bearing the S31N mutation, compared to 88% of the strains isolated in 2005-6 and 75% of the strains isolated in 2006-7. Molecular analysis of the HA gene showed a correlation of the mutants with specific phylogenetic clades. No known mutations in the NA or HA gene that have been implicated in resistance to NA inhibitors were found in the A(H3N2) strains isolated in the three influenza seasons. Despite the fact that amantadine is the only drug approved for prophylaxis in Greece, it has not been extensively used. So it seems that resistant strains circulating in the area after 2005 followed the global trend of replacement of susceptible strains by resistant ones. Oseltamivir and zanamivir are currently approved only for therapeutic use in Greece and has not been extensively used either.

Serologic prevalence of coxsackievirus group B in Greece.

Coxsackieviruses are human enteroviruses, which have been associated with myocarditis/pericarditis and sudden death. In one investigation (Spanakis N, Manolis EN, Tsakris A, Tsiodras S, Panagiotopoulos T, Saroglou G, and Legakis NJ: J Clin Pathol 2005;58:357-360), a cluster of cases of fatal myocarditis in Greece was linked to coxsackievirus B3. The information from this investigation prompted us to study serologically the prevalence of coxsackieviruses B throughout Greece. Sera were obtained from 506 healthy blood donors from various transfusion centers, covering the entire country. All sera were tested for the presence of IgG and IgM antibodies, using ELISAs with various antigenic specificities: (1) heat-denatured coxsackievirus type B1 and B5 virions, (2) a synthetic peptide from the N terminus of the VP1 protein of coxsackievirus B3, and (3) a synthetic peptide from the N terminus of the VP1 protein of coxsackievirus B4. Sera positive for IgG antibodies against coxsackieviruses B1/B5, B3, and B4 were detected in 6.7 to 21.6% of the individuals tested in the various regions of Greece. Statistical analysis revealed that the highest prevalence of IgG antibodies against coxsackieviruses B1/B5 was found in blood donors from Crete (p = 0.025), whereas the highest prevalence against coxsackievirus B4 was detected in blood donors from Athens (p = 0.01). IgM antibodies against coxsackievirus B were detected at low percentage, less than 5%, with no significant viral preference for particular geographic regions. The preference of anti-coxsackievirus IgG antibodies for particular geographic regions could be potentially related to the previously reported clustering of cases of insulin-dependent diabetes mellitus and myocarditis in Athens and Crete, respectively.

Stark broadening of high principal quantum number hydrogen Balmer lines in low-density laboratory plasmas.

We present results for Stark broadening of high principal quantum number (up to n=15 ) Balmer lines, using an analytical (the "standard theory") approach and two independently developed computer simulation methods. The line shapes are calculated for several sets of plasma parameters, applicable to radio-frequency discharge (N(e) approximately 10(13) cm(-3)) and magnetic fusion (N(e) approximately 10(15) cm(-3)) experiments. Comparisons of the calculated line profiles to the experimental data show a very good agreement. Density and temperature dependences of the linewidths, as well as relative contributions of different Stark-broadening mechanisms, are analyzed. It is seen that the standard theory of line broadening is sufficiently accurate for the entire set of plasma conditions and spectral transitions considered here, while an alternative theory ("advanced generalized theory") is shown to be inadequate for the higher-density region. A discussion of possible reasons for this disagreement is given.

Stark broadening of hydrogen lines in dense plasmas: analysis of recent experiments.

In recent years experiments conducted by a number of different groups on line broadening of hydrogen lines, mainly H(alpha) on dense plasmas of densities larger than or equal to 10(18) e/cm3 have claimed significant differences from the predictions of the standard theory. At these high densities the standard theory predictions depend on some cutoffs, necessary to preserve unitarity, the long range approximation and to ensure the validity of a semiclassical picture. Furthermore, a new, supposedly "advanced" theory based on a number of incorrect assumptions and/or approximations with extra exotic effects has claimed good agreement with these experiments. In this work we produce benchmark simulation calculations for these data to identify relevant and not relevant physics for the parameters of these experiments. In this way, we evaluate claims of electron-ion coupling, ion dynamics, electron vs ion broadening, nonimpact effects, and nonperturbative effects. At least one data set is seen to be dubious, in agreement with previous analyses.

Standard line broadening impact theory for hydrogen including penetrating collisions.

In recent years there has been significant interest in the emission spectra from high-density plasmas, as manifested by a number of experiments. At these high densities short range (small impact parameter) interactions become important and these cannot be adequately handled by the standard theory, whose predictions depend on some cutoffs, necessary to preserve unitarity, the long range approximation, and to ensure the validity of a semiclassical picture. Very recently, as a result of a debate concerning the broadening of isolated ion lines, the importance of penetration of bound electron wave functions by plasma electrons has been realized. By softening the interaction, penetration makes perturbative treatments more valid. The penetration effect has now been included analytically into the standard theory. It turns out that the integrations may be done in closed form in terms of the modified Bessel functions K0 and K1. This work develops the new theory and applies it to experimental measurements.

Cardiovascular responses to swimming.

The authors examined cardiovascular responses to long-distance fin swimming as compared to freestyle swimming. Elite male fin swimmers (n = 17) swam 8 km in the open sea (group A) and 17 top freestyle endurance swimmers (group B) swam 6 km in the open sea. The swimming times of the 2 groups did not differ significantly. The heart rate and mean blood pressure were higher in group B than in group A after exercise. As estimated from the systolic time intervals (STI), total electromechanical systole index (QS(2)I) and electrical systole index (QTI) increased and QT-QS(2) decreased in both types of swimming. These changes were more marked in fin swimmers. Moreover, the preejection period (PEPI) and the preejection period to left ventricular ejection time ratio (PEP/LVET) significantly decreased in both groups, while LVET remained constant in the 2 swimming events. Likewise, the amount of change in PEP/LVET was more pronounced in group A. Finally, only the QT-QS(2) changes were associated with performance efforts in both groups. Therefore, there are quantitative cardiovascular differences between these types of swimming that should be primarily attributed to the different muscle mass effort involved.

Changes of plasma fibrinogen and fibrinolysis in response to competition stress in swimming coaches.

AIM: The aim of the paper is to investigate the effects of competition stress in swimming coaches. METHODS: The effect of competition stress on fibrinogen and t-PA antigen concentrations was studied in 14 coaches during an international swimming meeting. Three blood samples were collected at the 1st day of the swimming meeting: a) 30 min before the start of the 1st event of the morning session, b) 10 min before the start of the most important event, and c) during the event itself. These were analyzed for plasma fibrinogen and t-PA antigen. RESULTS: An increase of plasma fibrinogen and t-PA antigen was observed during the race compared to 30 min before the start of the 1st day's event and 10 min before the race. CONCLUSION: It is concluded that competition stress in a very important event has significant effects on plasma fibrinogen and t-PA antigen concentrations.

Cardiac function after exhaustive open-sea swimming.

AIM: The present study examined the acute effects of exhaustive 25-km open-sea swimming on left ventricular (LV) function and morphology. METHODS: Twenty elite male swimmers (22.3+/-4.1 years) participated in this study. Two-dimensionally guided M-mode echocardiograms, and electrocardiographic, phonocardiographic and carotid pulse tracings were performed simultaneously before and immediately after prolonged exhaustive swimming to evaluate the LV function and morphology, and the cardiac sympathetic outflow. Blood samples were also collected before and after the race to determine the hematocrit and the plasma concentrations of K+, Na+, Ca2+, a-ANP, renin, myoglobulin, CPK-MB, and lactate. RESULTS: Exhaustive swimming was associated with a significant reduction in LV fractional shortening (-13%), ejection fraction (-11%), stroke volume (-25%), and LV internal diastolic diameter (-7%). In contrast, cardiac index was increased by 31%, total peripheral resistance was increased by 7%, and LV circumferential and meridional wall stresses were increased by 101% and 102%, respectively. Significant relationships were found between the increases in total peripheral resistance and LV circumferential wall stress and the decrease in ejection fraction. On the contrast, no significant relationship was found between the increased hematocrit and decreased ejection fraction. Furthermore, the pre-ejection period increased by 11%, the pre-ejection period to LV ejection time ratio increased by 15%, and the electrical to electromechanical systole relationship increased from -8 to 10 ms. Immediately after the race, there were significant increases in hematocrit (9%), and plasma concentrations of a-ANP (211%), renin (161%) and lactate (72%), myoglobulin (421%), and CPK-MB (141%) compared to pre-race values. CONCLUSIONS: In elite athletes, prolonged exhaustive swimming is associated with depressed LV function, as suggested by reduced stroke volume, ejection fraction, and LV fractional shortening. This alteration is mainly due to increased afterload.

Genetic heterogeneity of HIV-1 in Greece.

The aim of this study was to detect and determine the genetic variation of HIV-1 in Greece and to analyze the phylogenetic relationships and transmission dynamics of identified variants. Eighty-six blood samples from HIV-1 seroconverted patients of different risk groups were collected from the AIDS clinic, AHEPA Hospital, Thessaloniki, Greece. Retroviral DNA was extracted from uncultured peripheral blood mononuclear cells. HIV-1 DNA sequences encoding a 500-bp fragment of the gp120 C2-C3 region were amplified from each study subject, and they were genetically subtyped by heteroduplex mobility assay and DNA sequencing. Genetic distances and phylogenetic relationships of DNA sequences were estimated using PHYLIP software. Our results revealed that 82 out of 86 (95.3%) subjects carried subtype B sequences, while four (4.7%) carried subtype A sequences. Subtype A in Greek individuals not having traveled abroad was documented. An average of intrasubtype B genetic divergence of 15% was noted. Our findings demonstrate the presence of at least two genetic subtypes of HIV-1 in northern Greece--subtype B and subtype A. The predominant subtype is subtype B, which was transmitted into Greece by multiple sources. Our observations lend support to the argument that the distribution of HIV-1 subtypes is determined by founder effects or other processes rather than any tropism for particular cell types or mode of transmission.

HIV-1 co-receptor CCR5 and CCR2 mutations among Greeks.

The frequency of CCR5 and CCR2 alleles in human immunodeficiency virus (HIV)-positive and HIV-negative populations of Northern Greece was investigated. The frequency of the CCR5Delta32 allele among the HIV-negative subjects was 0.052, while it was approximately two-fold lower among the seropositives, suggesting that the heterozygous genotype confers a partial resistance to the HIV infection. No significant difference in CCR2 allele frequency between the two groups was observed.

Influenza surveillance in N. Greece during 1983-1993.

Following the WHO programme to monitor influenza, the National Influenza Centre for N. Greece presents the results of a laboratory surveillance during 1983-93. Influenza viruses were isolated every year except for 1986-87 and 1987-88 seasons. Type A viruses predominated in 1983-84, 1985-86, 1988-89 and 1989-90. Type B viruses were prevalent in 1990-91 and 1992-93. Both types of A and B viruses circulated concurrently in the community during the winters of 1984-85 and 1991-92. Seroconversions (CF tests) occurred each year against A, B or both types of influenza viruses. In 1986-87 and 1987-88 when no viruses were recovered, there were seroconversions to B viruses, suggesting influenza B activity in the area. Serological surveys by haemagglutination inhibition (HI) tests were also conducted in 1986-87 and 1988-89. The patterns of the isolated strains were similar to those recorded worldwide at the same time. There have been however differences in the virulence of the viruses and the duration of influenza seasons in this part of the world during 1983-93.

Hydrogen Balmer-alpha broadening in dense plasmas.

This work presents a theoretical analysis of experimental results for the hydrogen Balmer-alpha line in dense plasmas, with electron densities between 2x10(18) and 9x10(18) e/cm(3) A simulation of both electrons and ions is employed to produce reliable theoretical widths. These results are essentially in agreement with standard theory results and, for the most part, disagree with the experimental results. Consequently, either mechanisms not accounted for in the theoretical results (such as quadrupoles) are more important than previously thought at these densities, or else there is a problem in the experimental data (such as a possible reabsorption, which is not ruled out by the experimental data).

Isolation of Legionella pneumophila from hotels of Greece.

Twenty water samples collected from 6 hotels situated in various areas of Greece were examined for the presence of Legionella pneumophila and Legionella-like organisms. Five of the six hotels included in this investigation were associated with cases of legionellosis. Legionella pneumophila serogroups 1 and 8 were isolated from four of six hotels, mainly from the hot water supply system. This is the first isolation and identification of L. pneumophila in Greece.

Line shape measurement and isolated line width calculations: quantal versus semiclassical methods.

In a recent paper Griem, Ralchencko, Bray [Phys. Rev. E 56, 7186 (1998)] perform quantum-mechanical calculations of the line width of the B III 2s-2p transition and find agreement with previous quantum-mechanical results. The quantum-mechanical widths are a factor approximately 2 smaller than those measured in a recent experiment where the full width at half maximum for the B III 2s-2p transition was measured in a plasma with a measured electron temperature and density of 10 eV and 2 x 10(18) cm(-3). The quantum-mechanical results also disagree with a nonperturbative semiclassical calculation. We will illustrate that Griem, Ralchencko, and Bray are incorrect in stating that the experimental results are in error and that the semiclassical calculations are inapplicable.