Complementary cathodoluminescence lifetime imaging configurations in a scanning electron microscope.

Cathodoluminescence (CL) spectroscopy provides a powerful way to characterize optical properties of materials with deep-subwavelength spatial resolution. While CL imaging to obtain optical spectra is a well-developed technology, imaging CL lifetimes with nanoscale resolution has only been explored in a few studies. In this paper we compare three different time-resolved CL techniques and compare their characteristics. Two configurations are based on the acquisition of CL decay traces using a pulsed electron beam that is generated either with an ultra-fast beam blanker, which is placed in the electron column, or by photoemission from a laser-driven electron cathode. The third configuration uses measurements of the autocorrelation function g(2) of the CL signal using either a continuous or a pulsed electron beam. The three techniques are compared in terms of complexity of implementation, spatial and temporal resolution, and measurement accuracy as a function of electron dose. A single sample of InGaN/GaN quantum wells is investigated to enable a direct comparison of lifetime measurement characteristics of the three techniques. The g(2)-based method provides decay measurements at the best spatial resolution, as it leaves the electron column configuration unaffected. The pulsed-beam methods provide better detail on the temporal excitation and decay dynamics. The ultra-fast blanker configuration delivers electron pulses as short as 30 ps at 5 keV and 250 ps at 30 keV. The repetition rate can be chosen arbitrarily up to 80 MHz and requires a conjugate plane geometry in the electron column that reduces the spatial resolution in our microscope. The photoemission configuration, pumped with 250 fs 257 nm pulses at a repetition rate from 10 kHz to 25 MHz, allows creation of electron pulses down to a few ps, with some loss in spatial resolution.

Conclusions from the HIV in Europe Copenhagen 2012 Conference and ways forward: working together for optimal HIV testing and earlier care.

The objective of this article is to set the scene for this supplement by presenting and discussing the overall outcomes of the HIV in Europe Copenhagen 2012 Conference and how the HIV in Europe initiative intends to further address challenges and themes raised during the conference.

EuSANH workshop "Reasons behind the differences in national vaccination schedules for under-five", European Public Health pre-conference workshop, Malta, 8 November 2012.

Vaccination schedules for under-five children in the EU member states differ markedly, mainly as a consequence of differences in programme organization, decision making and history, and to a limited extent by epidemiological differences. There is little willingness towards unification since little evidence exists to prefer one schedule over the others, but the differences might impact on public confidence. Monitoring key determinants influencing individual decision making on immunization ('soft impacts') is thus as important as other existing monitoring systems of the 'hard' impacts of immunization programmes, and both should focus on the impact of these schedule differences. Harmonization of vaccination schedules is not the main issue, but the reasons behind the differences should be explained in an understandable and coherent way to the public. Scientists and advisory bodies should look over the country borders and communicate any crucial information, in order to improve scientific consensus on immunization schedules and programmes. These were the main conclusions of a members' experts panel of the European network of independent science advisory bodies on health (EuSANH), at a workshop in November 2012.

The case for indicator condition-guided HIV screening.

One-half of the estimated 2.5 million people who now live with HIV in the World Health Organization (WHO) European Region are still diagnosed late. A central question is which clinical scenarios should trigger an HIV test recommendation in order to avoid late presentation. Drawing on the work of the HIV Indicator Diseases across Europe Study (HIDES), new guidance brings together in one place a list of the conditions that should result in an HIV screening recommendation.

Synchronous x-ray and radio mode switches: a rapid global transformation of the pulsar magnetosphere.

Pulsars emit from low-frequency radio waves up to high-energy gamma-rays, generated anywhere from the stellar surface out to the edge of the magnetosphere. Detecting correlated mode changes across the electromagnetic spectrum is therefore key to understanding the physical relationship among the emission sites. Through simultaneous observations, we detected synchronous switching in the radio and x-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio-"bright" mode, the x-rays show only an unpulsed, nonthermal component. Conversely, when the pulsar is in a radio-"quiet" mode, the x-ray luminosity more than doubles and a 100% pulsed thermal component is observed along with the nonthermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories.

Deep-subwavelength imaging of the modal dispersion of light.

Numerous optical technologies and quantum optical devices rely on the controlled coupling of a local emitter to its photonic environment, which is governed by the local density of optical states (LDOS). Although precise knowledge of the LDOS is crucial, classical optical techniques fail to measure it in all of its frequency and spatial components. Here, we use a scanning electron beam as a point source to probe the LDOS. Through angular and spectral detection of the electron-induced light emission, we spatially and spectrally resolve the light wave vector and determine the LDOS of Bloch modes in a photonic crystal membrane at an unprecedented deep-subwavelength resolution (30-40 nm) over a large spectral range. We present a first look inside photonic crystal cavities revealing subwavelength details of the resonant modes. Our results provide direct guidelines for the optimum location of emitters to control their emission, and key fundamental insights into light-matter coupling at the nanoscale.

Late presentation of HIV infection: a consensus definition.

OBJECTIVES: Across Europe, almost a third of individuals infected with HIV do not enter health care until late in the course of their infection. Surveillance to identify the extent to which late presentation occurs remains inadequate across Europe and is further complicated by the lack of a common clinical definition of late presentation. The objective of this article is to present a consensus definition of late presentation of HIV infection. METHODS: Over the past year, two initiatives have moved towards a harmonized definition. In spring 2009, they joined efforts to identify a common definition of what is meant by a 'late-presenting' patient. RESULTS: Two definitions were agreed upon, as follows. Late presentation: persons presenting for care with a CD4 count below 350 cells/µL or presenting with an AIDS-defining event, regardless of the CD4 cell count. Presentation with advanced HIV disease: persons presenting for care with a CD4 count below 200 cells/µL or presenting with an AIDS-defining event, regardless of the CD4 cell count. CONCLUSION: The European Late Presenter Consensus working group believe it would be beneficial if all national health agencies, institutions, and researchers were able to implement this definition (either on its own or alongside their own preferred definition) when reporting surveillance or research data relating to late presentation of HIV infection.

Overcoming obstacles to late presentation for HIV infection in Europe.

OBJECTIVE: The central goal of the HIV in Europe Initiative is to promote testing and treatment throughout Europe and Central Asia in order to decrease the number of people living with HIV presenting late for care. This article summarizes the results from the HIV in Europe 2009 Conference and the early results of the projects set up by the initiative, and discusses their implications for the future. METHODS: In November 2009, 100 key stakeholders from 25 countries met in Stockholm at the HIV in Europe Conference. The focus was to address five key issues that contribute to the barriers to testing identified in 2007 at an innovative HIV conference. The conference discussed barriers to testing and other reasons for late presentation and outlined concrete recommendations to address the problem. RESULTS: An early result of the initiative has been stimulation of the process of reaching a consensus definition of what is meant by a 'late presenter', with this definition to be implemented at the European level. Steps are being taken to advocate for appropriate health policies and surveillance data related to HIV throughout Europe. Also, the initiative has set up projects related to the barriers to testing, i.e. criminalization law, stigmatization and lack of offering of testing for people presenting with certain indicator diseases. CONCLUSIONS: The final results of ongoing projects will be published and widely disseminated in 2010 and beyond. The HIV in Europe Initiative will continue to reinforce collaboration, advocacy and networking activities in the field throughout Europe.

Optimal HIV testing and earlier care: the way forward in Europe.

The articles in this supplement were developed from a recent pan-European conference entitled 'HIV in Europe 2007: Working together for optimal testing and earlier care', which took place on 26-27 November in Brussels, Belgium. The conference, organized by a multidisciplinary group of experts representing advocacy, clinical and policy areas of the HIV field, was convened in an effort to gain a common understanding on the role of HIV testing and counselling in optimizing diagnosis and the need for earlier care. Key topics discussed at the conference and described in the following articles include: current barriers to HIV testing across Europe, trends in the epidemiology of HIV in the region, problems associated with undiagnosed infection and the psychosocial barriers impacting on testing. The supplement also provides a summary of the World Health Organization's recommendations for HIV testing in Europe and an outline of an indicator disease-guided approach to HIV testing proposed by a committee of experts from the European AIDS Clinical Society (EACS). We hope that consideration of the issues discussed in this supplement will help to shift the HIV field closer towards our ultimate goal: provision of optimal HIV testing and earlier care across the whole of the European region.

[HIV should not become a notifiable disease]. / Hiv moet niet meldingsplichtig worden.

There is a need for effective strategies in HIV control. However, there is no evidence that making HIV a notifiable disease will contribute to more effective prevention. Making HIV a notifiable disease does not result in more HIV testing and it may even hamper the current proactive testing policy. Moreover, it does not contribute to better surveillance as the current HIV monitoring system provides excellent data on the state of the epidemic. In conclusion, making HIV a notifiable disease should not be introduced.

Prevalence of urogenital Chlamydia trachomatis infections in the Netherlands suggests selective screening approaches. Results from the PILOT CT Population Study.

Chlamydia trachomatis screening is being considered in the Netherlands, but policy recommendations are hampered by the lack of population-based data. We studied the prevalence of chlamydia infection in 15-29-year-old women and men in a national representative sample of 21,000 inhabitants of rural and urban areas in the Netherlands. Of this sample, 41% responded by sending in urine and an answered questionnaire, while 11% returned a refusal card. The overall prevalence of chlamydia infection was 2.0% (CI: 1.7-2.3); 2.5% (CI: 2.0-3.0) in women and 1.5% (1.1-1.8) in men. Chlamydia prevalence was significantly greater in very highly urbanized areas (3.2%, CI: 2.4-4.0) compared to rural areas (0.6%, CI: 0.1-1.1). In very highly urbanized areas the greatest prevalence was found among 15-19-year-old women (4.3%) and among 25-29-year-old men (4.2%). A risk profile could be determined and a prediction rule was developed. These data suggest that nationwide systematic screening is not indicated in the Netherlands and that targeted approaches are a better option. Roll-out of selective screening is recommended.

A fast method to study the secretory activity of neuroendocrine cells at the ultrastructural level.

Cryo field emission scanning electron microscopy (cryo-FE-SEM) is a versatile technique that allows the investigation of the three-dimensional organization of cells at the ultrastructural level over a wide range of magnifications. Unfortunately, cryopreparation of the specimens for this technique remains cumbersome, in particular because ice crystal formation must be prevented during freezing. Here we report that a light prefixation with glutaraldehyde and incubation in glycerol as cryoprotectant or a high-pressure freezing approach are both excellent procedures for cryopreparation of animal cells to be used in combination with cryo-FE-SEM. Using the proopiomelanocortin-producing intermediate pituitary melanotrope cells of Xenopus laevis as a physiologically inducible neuroendocrine system, we compared the ultrastructural characteristics of inactive and hyperactive neuroendocrine cells. The overall quality of the ultrastructural images was comparable for the two cryopreparation procedures, although some fine structures were better conserved using high-pressure freezing. Melanotrope cells in a secretory inactive state contained numerous storage granules and a poorly developed endoplasmic reticulum (ER), while large amounts of rough ER were present in hyperactive cells. Thus, the cryo-FE-SEM approach described here allows a fast ultrastructural study on the secretory activity of neuroendocrine cells.

Equal allergenic potency of beta-lactam antibiotics produced by chemical or enzymatic manufacturing--mouse IgE test.

BACKGROUND: Cephalexin and amoxicillin are semisynthetic beta-lactam antibiotics with a broad spectrum of antibacterial activity against gram-positive and gram-negative microorganisms. Both antibiotics are produced by a new 'green' process in which enzyme technology is used to combine the intermediate structure and the side chain in an aqueous medium to yield cephalexin or amoxicillin, thus avoiding the use of several chemical reagents and volatile organic solvents. As a result of the enzyme technology a new residual protein impurity has been identified. To check for the sensitizing capacity of the residual protein, a mouse IgE test was used to detect differences in the production of specific IgE by chemical or enzymatic preparations of the antibiotics. METHODS: Balb/c female mice were immunized intraperitoneally with alum and conjugates of different amoxicillins or cephalexins with ovalbumin (OVA). After 16 days, the amoxicillin mice were injected with one half the original amount of antigen. After 19-23 days, the sera were tested for specific IgE by the passive cutaneous anaphylaxis assay in Sprague-Dawley rats. The greatest dilution of sera which resulted in a positive response was the titer of specific IgE. RESULTS: No significant differences were found between the titers of specific IgE caused by the chemically and enzymatically produced beta-lactam antibiotics, indicating that the antibiotics are equal in allergenicity. CONCLUSIONS: The data show that a residual level of 35 ppm protein did not affect the allergenic potency of these beta-lactam antibiotics as determined by the mouse allergenicity model.

Safety evaluation of a lactase enzyme preparation derived from Kluyveromyces lactis.

Neutralact(R), the DSM brand name of a lactase enzyme preparation, obtained from a homologous rDNA strain of Kluyveromyces lactis, was subjected to a series of toxicological tests to document the safety for use as a processing aid in the dairy industry. The enzyme preparation was examined for subacute oral toxicity and mutagenic potential. As a result of these tests, no evidence of oral toxicity, mutagenicity or clastogenicity was found. Administration of the lactase enzyme preparation at doses of 500, 3000 and 10,000 mg/kg body weight/day for 28 days did not induce noticeable signs of toxicity. The no-observed-adverse-effect level (NOAEL) of the enzyme preparation in the acute toxicity study was 10,000 mg/kg body weight/day (equivalent to 114,000 NL units/kg body weight/day). It can be concluded that no safety concerns were identified in the studies conducted with this lactase enzyme preparation derived from Kluyveromyces lactis under controlled fermentation conditions.

Safety evaluation of amino peptidase enzyme preparation derived from Aspergillus niger.

An amino peptidase enzyme preparation obtained from Aspergillus niger was subjected to a series of toxicological tests to document the safety for use as a processing aid for food. The enzyme preparation was examined for subacute and subchronic oral toxicity, and mutagenic potential. No evidence of oral toxicity or mutagenicity was found. Administration of the amino peptidase enzyme preparation at doses of 500, 1000 and 2000 mg/kg body weight/day for 90 days did not induce noticeable signs of toxicity. The no-observed-adverse-effect level (NOAEL) of the enzyme preparation in the subchronic toxicity study was 2000mg/kg body weight/day (equivalent to 1152 PHEA units/kg body weight/day). It can be concluded that no safety concerns were identified in the studies conducted with this amino peptidase enzyme preparation derived from Aspergillus niger and produced under controlled fermentation conditions.

Safety evaluation of lipase derived from Rhizopus oryzae: summary of toxicological data.

A lipase enzyme, obtained from Rhizopus oryzae produced by a fermentation process was subjected to a series of toxicological tests to document the safety for use as a food additive. The enzyme product was examined for acute, subacute and subchronic oral toxicity, and mutagenic potential. An extensive literature search on the production organism has also been conducted. No evidence of (sub)acute oral toxicity or mutagenic potential was found. Administration of the lipase at dosages of 50, 200 and 1000 mg/kg body weight/day for 90 days did not induce noticeable signs of toxicity. A few minor changes in the chemical composition of the blood in the highest dose group were of no toxicological significance. The no-observed-adverse-effect level of the tox-batch in the subchronic toxicity study was 1000 mg/kg body weight/day. It can be concluded that no safety concerns were identified in the studies conducted with this lipase preparation derived from R. oryzae and produced under controlled fermentation conditions.

Safety evaluation of beta-glucanase derived from Trichoderma reesei: summary of toxicological data.

Barlican, a beta-glucanase enzyme obtained from Trichoderma reesei, was produced by a fermentation process and subjected to a series of toxicological tests to document its safety for use as a feed additive. The enzyme product was examined for general oral toxicity, inhalation toxicity, irritation to eye and skin, skin sensitization and mutagenic potential. An extensive literature search on the production organism was also conducted. Furthermore, safety for target species was assessed in a 28-day oral toxicity study with broilers. A strong skin-sensitizing potential of the beta-glucanase enzyme was detected, but no other evidence of oral or inhalation toxicity, mutagenic potential, eye or skin irritancy was found. Feeding of the beta-glucanase enzyme at dietary levels up to 10,000 ppm in the 90-day subchronic toxicity study in rats did not induce noticeable signs of toxicity. In addition, no adverse effects were observed when broiler chicks were fed dietary concentrations of the beta-glucanase enzyme up to eight times the daily recommended dose. It is therefore concluded that this beta-glucanase preparation is safe for use in feed of the intended target species. However, some occupational health precautions should be taken to avoid skin contact and inhalation, as is the case for almost all enzyme proteins.

Modified suspension Ames test for testing proteinaceous substances: an initial step.

The basic Salmonella/microsome assay (Ames test) is a valuable primary tool by which to discriminate mutagens from non-mutagens. For a variety of chemical test substances this test is easily conducted according to international guidelines for genotoxicity testing. However, the testing of proteinaceous substances in the basic Ames test may generate false positives owing to the presence of growth-promoting constituents in the test sample, such as histidine or its precursors. It was hypothesized that the growth-promoting capacities of biological test samples might be overcome by testing according to the 'suspension variant' of the Ames test, which uses very rich growth conditions thereby overwhelming any growth-enhancing constituents present in a biological test sample. This hypothesis appeared to be correct, although several important modifications had to be made to the suspension assay. The most important aspect of this 'new suspension Ames test' appeared to be the plating of overnight regrown bacteria in the poorest way possible (by omitting histidine and nutrient broth from the overlay agar). This study may comprise an initial step in the development of a modified suspension Ames test for testing proteinaceous substances.

Hematology and serum biochemistry of Japanese quail fed dietary tri-n-butyltin oxide during reproduction.

During a subchronic toxicity and reproduction study with tri-n-butyltin oxide (TBTO) concentrations of 0, 24, 60, and 150 mg/kg diet in Japanese quail, preliminary data on hematology and serum biochemistry were obtained. The absence of serious effects in blood parameters in both adult quail and developing chicks are discussed in view of the adverse effects of TBTO on reproduction.

Effects of bis(tri-n-butyltin)oxide in Japanese quail exposed during egg laying period: an interlaboratory comparison study.

The guideline no. 206 for testing of chemicals of the Organization for Economic Cooperation and Development (OECD) comprising an avian reproduction test using the Japanese quail (Coturnix coturnix japonica; Termminck and Schlegel 1849) as pair-hold test organisms has been applied in a version that reduced the treatment period to 6 weeks without any pretreatment. In the present study bis(tri-n-butyltin)oxide, C.A. No. 56-35-9 (tributyltin oxide, TBTO) was examined by five participants in an interlaboratory comparison test. A comparable regimen of dosing was performed by all participants starting either with 24 or 60 mg/kg TBTO in the feed and ending with 150 or 375 mg/kg. Within this dose range no signs of toxicity in adults were observed. Substance-related effects however were obvious with regard to egg production, fertility, hatching success, and survival of 14 day-old chicks. A clear dose dependency was given regarding effects on egg weight and on hatchability. The no-observed-effect concentrations for these two parameters was 60 mg/kg TBTO, characterizing these parameters as the most sensitive in this investigation. With the presented set of test parameters further aspects of subchronic toxicity in adults and chicks can be assessed as well as the validity of the performed test. Comparing the results for most test parameters consistency is obvious, thus confirming the applicability of the presented test guideline.