A benchmark for Monte Carlo simulations in gamma-ray spectrometry Part II: True coincidence summing correction factors.

The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.

[Health risk assessment associated with priority potentially hazardous chemical compounds detected in canned meat and meat-and-vegetable food for infants].

Assessment of public health safety associated with chemical contaminants consumed with food is an important component for solving the tasks of ensuring the sanitary and epidemiological well-being of the population. For these purposes, it is necessary to establish priority potentially dangerous compounds among the identified undeclared and unintended chemical contaminants for further consumers risk assessment. In conditions of unacceptable levels of health risk, it is necessary to decide whether it is advisable to develop new or change existing hygiene standards for these substances. The aim of the study was to assess the health risk associated with priority potentially dangerous unintended chemical components of contamination in canned meat and meat-and-vegetable products for infants (using the example of N-nitrosoamines). Material and methods. The selection of priority chemical compounds and public health risk assessment were carried out in accordance with the procedure for identifying undeclared and potentially dangerous unintended chemicals in food and using modified approaches based on the results of previous studies. Health risk assessment for infants consuming canned meat and meat-and-vegetables containing priority chemicals was carried out in accordance with the methodology approved by the Eurasian Economic Commitee, as well as using the Guidelines for assessing risks to public health when exposed to environmental pollutants. To characterize the calculated risk levels, the classification proposed in the draft document «Guidelines for assessing risks to public health when exposed to environmental pollutants¼ was used. Results. N-nitrosoamines are classified as chemical contaminants that are a priority for public health risk assessment, identified on the basis of the potential hazard category. A comparative health risk assessment for the target group consumers of canned meat and meat-and-vegetables sold on the territory of the Russian Federation and the Socialistic Republic of Vietnam showed the presence of an unacceptable risk to the health of the Russian population in relation to non-carcinogenic adverse health effects associated with the intake of N-nitrosodimethylamine (NDMA) (hazard quotient HQ=1.1) and N-nitrosodibuthylamine (HQ=5.25). Many experimental (animal) researches confirm the formation of negative effects and potential harm to humans, formed by the consumption of N-nitrosoamines with food. At the same time, the level of the exposure of N-nitrosoamines during oral administration was assessed mainly from the side of carcinogenic effects, however, this study reflects the hazard, including from non-carcinogenic risks associated not only with NDMA and N-nitrosodiethylamine, for which there is a hygienic standard, but also for other N-nitrosoamines, for which there is no hygienic regulation. In turn, the European Food Safety Agency's (EFSA) study notes that it is necessary to conduct a risk assessment for human health in relation to other N-nitrosoamines identified in food, and, if necessary, rationing of these compounds, which is also confirmed by this study. Conclusion. The conducted health risk assessment of the target population of Russia (infants from 6 months to 3 years) consuming the studied types of products containing N-nitrosoamines showed the presence of unacceptable levels of non-carcinogenic health risks in relation to the development processes and impaired liver function. In connection with the identified risks to the health of the target population, it is advisable to establish maximum permissible levels not only for the amount of NDMA and N-nitrosodiethylamine, but also for other N-nitrozoamines identified by the results of the study, with their subsequent regulation.

Longitudinal sampling is required to maximize detection of intrahost A/H3N2 virus variants.

Seasonal human influenza viruses continually change antigenically to escape from neutralizing antibodies. It remains unclear how genetic variation in the intrahost virus population and selection at the level of individual hosts translates to the fast-paced evolution observed at the global level because emerging intrahost antigenic variants are rarely detected. We tracked intrahost variants in the hemagglutinin and neuraminidase surface proteins using longitudinally collected samples from 52 patients infected by A/H3N2 influenza virus, mostly young children, who received oseltamivir treatment. We identified emerging putative antigenic variants and oseltamivir-resistant variants, most of which remained detectable in samples collected at subsequent days, and identified variants that emerged intrahost immediately prior to increases in global rates. In contrast to most putative antigenic variants, oseltamivir-resistant variants rapidly increased to high frequencies in the virus population. Importantly, the majority of putative antigenic variants and oseltamivir-resistant variants were first detectable four or more days after onset of symptoms or start of treatment, respectively. Our observations demonstrate that de novo variants emerge, and may be positively selected, during the course of infection. Additionally, based on the 4-7 days post-treatment delay in emergence of oseltamivir-resistant variants in six out of the eight individuals with such variants, we find that limiting sample collection for routine surveillance and diagnostic testing to early timepoints after onset of symptoms can potentially preclude detection of emerging, positively selected variants.

Value of lipocalin 2 as a potential biomarker for bacterial meningitis.

OBJECTIVES: Central nervous system (CNS) infections are common causes of morbidity and mortality worldwide. We aimed to discover protein biomarkers that could rapidly and accurately identify the likely cause of the infections, essential for clinical management and improving outcome. METHODS: We applied liquid chromatography tandem mass spectrometry on 45 cerebrospinal fluid (CSF) samples from a cohort of adults with and without CNS infections to discover potential diagnostic biomarkers. We then validated the diagnostic performance of a selected biomarker candidate in an independent cohort of 364 consecutively treated adults with CNS infections admitted to a referral hospital in Vietnam. RESULTS: In the discovery cohort, we identified lipocalin 2 (LCN2) as a potential biomarker of bacterial meningitis (BM) other than tuberculous meningitis. The analysis of the validation cohort showed that LCN2 could discriminate BM from other CNS infections (including tuberculous meningitis, cryptococcal meningitis and virus/antibody-mediated encephalitis), with sensitivity of 0.88 (95% confident interval (CI), 0.77-0.94), specificity of 0.91 (95% CI, 0.88-0.94) and diagnostic odds ratio of 73.8 (95% CI, 31.8-171.4). LCN2 outperformed other CSF markers (leukocytes, glucose, protein and lactate) commonly used in routine care worldwide. The combination of LCN2, CSF leukocytes, glucose, protein and lactate resulted in the highest diagnostic performance for BM (area under the receiver operating characteristics curve, 0.96; 95% CI, 0.93-0.99). Data are available via ProteomeXchange with identifier PXD020510. CONCLUSIONS: LCN2 is a sensitive and specific biomarker for discriminating BM from a broad spectrum of other CNS infections. A prospective study is needed to assess the diagnostic utility of LCN2 in the diagnosis and management of CNS infections.

Consistency test of coincidence-summing calculation methods for extended sources.

An internal consistency test of the calculation of coincidence-summing correction factors FC for volume sources is presented. The test is based on exact equations relating the values of FC calculated for three ideal measurement configurations. The test is applied to a number of 33 sets of FC values sent by 21 teams. Most sets passed the test, but not the results obtained using the quasi-point source approximation; in the latter case the test qualitatively indicated the magnitude of the bias of FC.

A benchmark for Monte Carlo simulation in gamma-ray spectrometry.

Monte Carlo (MC) simulation is widely used in gamma-ray spectrometry, however, its implementation is not always easy and can provide erroneous results. The present action provides a benchmark for several MC software for selected cases. The examples are based on simple geometries, two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The action outputs (input files and efficiency calculation results, including practical recommendations for new users) are made available on a dedicated webpage.

Highly Pathogenic Avian Influenza Virus A/H5N1 Infection in Vaccinated Meat Duck Flocks in the Mekong Delta of Vietnam.

We investigated episodes of suspected highly pathogenic avian influenza (HPAI)-like illness among 12 meat duck flocks in two districts in Tien Giang province (Mekong Delta, Vietnam) in November 2013. In total, duck samples from 8 of 12 farms tested positive for HPAI virus subtype A/haemagglutinin 5 and neuraminidase 1 (H5N1) by real-time RT-PCR. Sequencing results confirmed clade of 2.3.2.1.c as the cause of the outbreaks. Most (7/8) laboratory-confirmed positive flocks had been vaccinated with inactivated HPAI H5N1 clade 2.3.4 vaccines <6 days prior to onset of clinical signs. A review of vaccination data in relation to estimated production in the area suggested that vaccination efforts were biased towards larger flocks and that vaccination coverage was low [21.2% ducks vaccinated with two shots (range by district 7.4-34.9%)]. The low-coverage data, the experimental evidence of lack of cross-protection conferred by the currently used vaccines based on clade 2.3.4 together with the short lifespan of meat duck flocks (60-70 days), suggest that vaccination is not likely to be effective as a tool for control of H5N1 infection in meat duck flocks in the area.

Comparison of RAPD and ISSR markers for assessment of genetic diversity among endangered rare Dalbergia oliveri (Fabaceae) genotypes in Vietnam.

Dalbergia oliveri is a leguminous tree of the Fabaceae family. This species is popular and valuable in Vietnam and is currently listed on the Vietnam Red List and on the IUCN Red List as endangered. Two PCR techniques using RAPD and inter-simple sequence repeat (ISSR) markers were used to make a comparative analysis of genetic diversity in this species. Fifty-six polymorphic primers (29 RAPD and 27 ISSR) were used. The RAPD primers produced 63 bands across 35 genotypes, of which 24 were polymorphic. The number of amplified bands varied from one to four, with a size range from 250 to 1400 bp. The percentage polymorphism ranged from 0 to 75. Amplification of genomic DNA of the 35 genotypes, using ISSR analysis, yielded 104 fragments, of which 63 were polymorphic. The number of amplified fragments using ISSR primers ranged from one to nine and varied in size from 250 to 1500 bp. The percentage polymorphism ranged from 0 to 100. ISSR markers were relatively more efficient than RAPDs. The mental test between two Jaccard's similarity matrices gave r ≥0.802, showing good fit correlation between ISSRs and RAPDs. Clustering of isolates remained more or less the same for RAPDs compared to combined RAPD and ISSR data. The similarity coefficient ranged from 0.785 to 1.000, 0.698 to 0.956 and 0.752 to 0.964 with RAPD, ISSR, and the combined RAPD-ISSR dendrogram, respectively.

Recent avian influenza virus A/H5N1 evolution in vaccinated and unvaccinated poultry from farms in Southern Vietnam, January-March 2010.

We report 15 new avian influenza virus A/H5N1 haemagglutinin (HA) sequences sampled from visibly sick domestic poultry in southern Vietnam, between 1 January 2010 and 6 March 2010. These HA sequences form a new sub-clade of the clade 1 H5N1 viruses that have been circulating in Vietnam since 2003/2004. The viruses are characterized by a change from isoleucine to valine at position 514 (I514V) and are 1.8% divergent at the nucleotide level from HA sequences sampled in Vietnam in 2007. Five new amino acid changes were observed at previously identified antigenic sites, and three were located within structural elements of the receptor-binding domain. One new mutation removed a potential N-linked glycosylation site, and a methionine insertion was observed in one virus at the polybasic cleavage site. Five of these viruses were sampled from farms where poultry were vaccinated against H5N1, but there was no association between observed amino acid changes and flock vaccination status. Despite the current lack of evidence for antigenic drift or immune escape in Vietnamese H5N1 viruses, continued surveillance remains a high priority.

Determination activity of radionuclides in marine sediment by gamma spectrometer with anti cosmic shielding.

In this work, the activities of radionuclides in a marine sediment sample have been determined. The gamma spectrometer comprises an N type coaxial HPGe detector with active shielding to reduce cosmic background. The mass activities of radionuclides have been derived and found to be around a few Bq kg(-1) to several hundreds Bq kg(-1) with relative uncertainties in this paper quoted corresponding to the combined standard uncertainties (k=1).

Proteomic characterization of the thermostable toxins from Naja naja venom

Naja naja snake venom presents abundant thermostable peptides. Many of them possess useful pharmacological activity that may be employed for drug development. For the proteomic characterization of such toxins, in the present study, Naja naja venom solution was heated up to 100°C for 10, 30, 60, 120, 180 and 300 minutes and protein fractions of non-heated and heated venom were analyzed by two-dimensional nano-liquid chromatography coupled online with tandem mass spectrometry. After heating for 300 minutes, a total of 32 peptides were still detected in the supernatant. The identified peptides belong to the following groups: cardiotoxins, neurotoxins and cytotoxins. It was found that thermostable peptides are able to preserve their analgesic activity after a long heating time in formalin test. Mice injected with 15 µg/g of 60-minute heated venom or with 25 µg/g of 300-minute heated venom revealed even a better analgesic activity than those treated with lidocaine.(AU)

One year recurrence of trachomatous trichiasis in routinely operated Cuenod Nataf procedure cases in Vietnam.

BACKGROUND: Recurrence of trichiasis following surgery remains unacceptably high, regardless of the surgical procedure. Few prospective studies of sufficient size are available to assess the rate of recurrence and the factors contributing to recurrence. A prospective study of the modified Cuenod Nataf surgical procedure was conducted in Vietnam to determine recurrence and co-factors. METHODS: The prospective study of Cuenod Nataf surgery for trachomatous trichiasis took place in four districts of Vietnam. All patients from identified villages who had surgery were followed for a period of 1 year. 10 Surgeons using standard techniques and recording procedures carried out the surgery. The presence of an eyelash touching the eyeball in the operated eye was considered as recurrence. Information on all subjects was recorded preoperatively, intraoperatively, and postoperatively. An independent examiner recorded postoperative information. Relative risks were calculated to assess the contribution of various risk factors to recurrence (by eye and by person). Cox proportional hazards modelling was used to assess the independent contribution of relevant factors to the outcome. RESULTS: 471 individuals had trichiasis surgery; 463 were followed for a period of 1 year. Overall, the recurrence rate was 10.8% (95% CI 8.0 to 13.6). Among people having surgery recurrence (one or both eyes) was most common in the most elderly (relative risk (RR) 2.49) and among those with a history of previous surgery (RR = 2.49). Cox proportional hazards analysis (by eye) revealed that visual acuity, conjunctival scarring, and suture adjustment were associated with recurrence at 1 year. CONCLUSION: The Cuenod Nataf procedure, which is well accepted in the community and by eye care providers in Vietnam, has an acceptable 1 year success rate. Individuals with severe conjunctival scarring have the highest rate of recurrence suggesting that other surgical approaches are needed to manage these patients or that these patients need to be educated regarding the risk of recurrence. Active follow up of these patients would be warranted. The association with suture adjustment requires further investigation.