Alpha particle spectroscopy using FNTD and SIM super-resolution microscopy.

Structured illumination microscopy (SIM) for the imaging of alpha particle tracks in fluorescent nuclear track detectors (FNTD) was evaluated and compared to confocal laser scanning microscopy (CLSM). FNTDs were irradiated with an external alpha source and imaged using both methodologies. SIM imaging resulted in improved resolution, without increase in scan time. Alpha particle energy estimation based on the track length, direction and intensity produced results in good agreement with the expected alpha particle energy distribution. A pronounced difference was seen in the spatial scattering of alpha particles in the detectors, where SIM showed an almost 50% reduction compared to CLSM. The improved resolution of SIM allows for more detailed studies of the tracks induced by ionising particles. The combination of SIM and FNTDs for alpha radiation paves the way for affordable and fast alpha spectroscopy and dosimetry.

More severe clinical course of cardiovascular dysfunction in intensive care unit patients with the 894TT eNOS genotype.

The endothelial nitric oxide synthase (eNOS) plays an important homeostatic role in the cardiovascular system (CVS) by maintaining appropriate blood pressure through production of nitric oxide. The 894TT genotype of 894G>T (Glu298Asp, rs1799983), a polymorphic variant of eNOS, has been associated with several vascular diseases. On the basis of this strong relationship, we monitored daily 585 critically ill adult patients according to their degree of CVS dysfunction and investigated their disease progression by the 894G>T genotype. To obtain information of the general population, we obtained the 894G>T genotypic and allelic frequencies in a random group of 149 healthy subjects. The patients were genotyped for the eNOS 894G>T polymorphism and daily evaluated according to their degree of CVS dysfunction through the Cardiovascular Sequential Organ Failure Assessment (SOFA) score. The mean value of the global CVS dysfunction score was significantly higher in 894TT patients (1.35 ± 0.57) than in non-894TT patients (1.23 ± 0.37; P = 0.035). This score remained significantly higher in 894TT patients, even in different patient clusters (all patients, septic, and non-septic patients) during the 1st week at the intensive care unit (1.86 ± 0.8 versus 1.63 ± 0.62, P = 0.005; 2.32 ± 0.10 versus 2.06 ± 0.08, P = 0.009; 0.84 ± 0.09 versus 0.64 ± 0.08, P = 0.027; respectively). This result shows that the mean values of the cardiovascular SOFA score were higher in 894TT patients in all subgroups. The present study provides evidence that the 894TT eNOS genotype is associated with a higher degree of CVS dysfunction in critically ill patients.

Sex hormone binding globulin levels across the adult lifespan in women--the role of body mass index and fasting insulin.

SHBG is a major carrier of androgens. In men, SHBG levels increase with age, while in women data are scant. There is evidence that body mass index (BMI) and fasting insulin influence SHBG concentration. Since low SHBG levels are predictors of insulin resistance and diabetes, understanding the relationship of SHBG with age, insulin, and BMI is important to gain insight into the role of SHBG as a cardiovascular risk factor in women. Differences in SHBG across adult life span and their relationship with insulin and BMI were evaluated in a representative cohort of 616 Italian women free of diabetes and not on hormone replacement therapy enrolled in the InCHIANTI Study. The relationship of SHBG with age, BMI, and fasting insulin levels was analyzed using linear regression and by loess smoother. Serum SHBG levels showed a U-shaped trajectory with age, declining from the 2nd to the 6th decade of life and increasing after the 6th decade (p<0.0001). Age-related trends for BMI and fasting insulin mirrored the trend observed for SHBG. After adjusting for fasting insulin, the relationship between log (SHBG) and age square was attenuated (beta coefficient from 0.00044 to 0.00039) and was further reduced after adjustment for BMI (from 0.00039 to 0.00028). SHBG levels show an age-related U-shaped trajectory. These changes mirror the age-related changes in BMI and fasting insulin, suggesting that BMI and insulin negatively influence SHBG concentration.

Fluorescent nuclear track detectors for alpha radiation microdosimetry.

BACKGROUND: While alpha microdosimetry dates back a couple of decades, the effects of localized energy deposition of alpha particles are often still unclear since few comparative studies have been performed. Most modern alpha microdosimetry studies rely for large parts on simulations, which negatively impacts both the simplicity of the calculations and the reliability of the results. A novel microdosimetry method based on the Fluorescent Nuclear Track Detector, a versatile tool that can measure individual alpha particles at sub-micron resolution, yielding accurate energy, fluence and dose rate measurements, was introduced to address these issues. METHODS: Both the detectors and U87 glioblastoma cell cultures were irradiated using an external Am241 alpha source. The alpha particle tracks measured with a Fluorescent Nuclear Track Detector were used together with high resolution 3D cell geometries images to calculate the nucleus dose distribution in the U87 glioblastoma cells. The experimentally obtained microdosimetry parameters were thereafter applied to simulations of 3D U87 cells cultures (spheroids) with various spatial distributions of isotopes to evaluate the effect of the nucleus dose distribution on the expected cell survival. RESULTS: The new experimental method showed good agreement with the analytically derived nucleus dose distributions. Small differences (< 5%) in the relative effectiveness were found for isotopes in the cytoplasm and on the cell membrane versus external irradiation, while isotopes located in the nucleus or on the nuclear membrane showed a substantial increase in relative effectiveness (33 - 51%). CONCLUSIONS: The ease-of-use, good accuracy and use of experimentally derived characteristics of the radiation field make this method superior to conventional simulation-based microdosimetry studies. Considering the uncertainties found in alpha radionuclide carriers in-vivo and in-vitro, together with the large contributions from the relative biological effectiveness and the oxygen enhancement ratio, it is expected that only carriers penetrating or surrounding the cell nucleus will substantially benefit from microdosimetry.

Distraction or cognitive overload? Using modulations of the autonomic nervous system to discriminate the possible negative effects of advanced assistance system.

The interaction with Advanced Driver Assistance Systems has several positive implications for road safety, but also some potential downsides such as mental workload and automation complacency. Malleable attentional resources allocation theory describes two possible processes that can generate workload in interaction with advanced assisting devices. The purpose of the present study is to determine if specific analysis of the different modalities of autonomic control of nervous system can be used to discriminate different potential workload processes generated during assisted-driving tasks and automation complacency situations. Thirty-five drivers were tested in a virtual scenario while using head-up advanced warning assistance system. Repeated MANOVA were used to examine changes in autonomic activity across a combination of different user interactions generated by the advanced assistance system: (1) expected take-over request without anticipatory warning; (2) expected take-over request with two-second anticipatory warning; (3) unexpected take-over request with misleading warning; (4) unexpected take-over request without warning. Results shows that analysis of autonomic modulations can discriminate two different resources allocation processes, related to different behavioral performances. The user's interaction that required divided attention under expected situations produced performance enhancement and reciprocally-coupled parasympathetic inhibition with sympathetic activity. At the same time, supervising interactions that generated automation complacency were described specifically by uncoupled sympathetic activation. Safety implications for automated assistance systems developments are considered.

Additional value of typing Noroviruses in gastroenteritis outbreaks in Amsterdam, The Netherlands.

BACKGROUND: In Amsterdam, 17 of the 55 gastroenteritis (GI) outbreaks reported from January 2002 to May 2003 were confirmed to be caused by noroviruses (NV). OBJECTIVE: In this study, we describe the molecular epidemiology of a group of nine outbreaks associated with a catering firm and two outbreaks, 5 months apart, in an Amsterdam hospital. All outbreaks were typed to confirm their linkage, and the hospital-related cases were studied to see if the two outbreaks were caused by one persisting NV strain or by a reintroduction after 5 months. RESULTS AND CONCLUSIONS: For the outbreaks associated with the catering firm one NV genogroup I strain was found which was identical in sequence among customers and employees of the caterer. This was not the strain that predominantly circulated in 2002/2003 in and around Amsterdam, which was the NV genogroup II4 "new variant" (GgII4nv) strain. In the Amsterdam hospital, the two outbreaks were caused by this predominant GgII4nv type, and we argue that NV was most likely reintroduced in the second outbreak from the Amsterdam community.

Optically and thermally stimulated luminescence characteristics of MgO:Tb3+.

In this paper main optically stimulated luminescence (OSL) and thermoluminescence (TL) characteristics are presented of a newly synthesised material MgO doped with terbium (Tb) developed at the Institute of Nuclear Science, Vinca. A thermally stimulated emission spectrum showed the characteristic lines of Tb3+ in a wide range of wavelengths. The TL sensitivity of the main TL glow peak at 315 degrees C is 1.7 times higher than the TL of Al2O3:C. The highest OSL sensitivity was obtained under green lamp (500-570 nm) stimulation. The fast component in the OSL decay curve is 2.4 times faster than Al2O3:C. The OSL signal is linear with dose up to 10 Gy. The lower limit of detection was found to be 100 microGy. These first results show that the newly synthesised material has some promising properties for the application in radiation dosimetry.

Is the apoE4 allele an independent predictor of coronary events?

PURPOSE: Although the apolipoprotein E genotype epsilon4 (apoE4) has been associated with high cholesterol levels, whether it is an independent predictor of coronary events is not certain. SUBJECTS AND METHODS: We measured apoE genotypes in 730 participants in the Baltimore Longitudinal Study of Aging (421 men and 309 women, mean [+/- SD] age of 52+/-17 years) who were free of preexisting coronary heart disease. A proportional hazards regression model was used to study the association between risk factors and the occurrence of coronary events, defined as angina pectoris, documented myocardial infarction by history or major Q waves on the electrocardiogram (Minnesota Code 1:1 or 1:2), or coronary death, adjusted for other risk factors, including total plasma cholesterol level. RESULTS: The apoE4 allele was observed in 200 subjects (27%), including 183 heterozygotes and 17 homozygotes. Coronary risk factor profiles were similar in those with and without apoE4. Coronary events developed in 104 (14%) of the 730 subjects, including 77 (18%) of the 421 men during a mean follow-up of 20 years and 27 (9%) of the 309 women during a mean follow-up of 13 years. Coronary events occurred significantly more frequently in subjects with apoE4 (n = 40, 20%) than in those without this allele (64, 12%, P <0.05). In a multivariate model, apoE4 was an independent predictor of coronary events in men (risk ratio [RR]= 2.9, 95% confidence interval [CI]: 1.8 to 4.5, P<0.0001) but not in women (RR = 0.9, 95% CI: 0.4 to 1.9, P = 0.62). CONCLUSION: The apoE4 genotype is a strong independent risk factor for coronary events in men, but not women. The association does not appear to be mediated by differences in total cholesterol levels.

On the applicability of the AAPM TG-60/TG-43 dose calculation formalism to intravascular line sources: proposal for an adapted formalism.

Despite the widely recognized usefulness of the AAPM TG-43 brachytherapy dose calculation formalism, a straightforward application of this approach to describe the dose distribution about intravascular line sources as proposed by TG-60 may be difficult or even impossible, especially when these line sources emit low-energy photons or beta particles. The causes of these limitations are investigated and illustrated by means of some numerical examples. In order to solve the observed limitations an adapted formalism is proposed, intended specifically for the description of the dose rate distribution about line sources but conceptually similar to the TG-43/TG-60 formalism. Several examples are presented to illustrate the usefulness of the proposed line source dose calculation formalism.

Modelling of a 188W/188Re beta line source for coronary brachytherapy by means of EGS4 Monte Carlo simulations.

In this paper, we present results from three different simulation models that are used to determine the dose distribution around a 188W/188Re coronary brachytherapy source with EGS4 Monte Carlo simulations. The three models are found to give similar results within 10%. Agreement was found with experimental data from measurements in a PMMA phantom. It has been shown that in the therapeutically relevant region the beta line source can be characterized by the radial depth-dose distribution in water.

Incorporation routes of elements into human hair; implications for hair analysis used for monitoring.

A study has been made on the incorporation of some trace elements and minerals into human hair by measuring their distributions across hair diameters. For this study the Particle Induced X-ray Emission (PIXE) technique using the proton microbeam of the Vrije Universiteit of Amsterdam has been applied. Results of measurements on single hair strands at different positions in the root and outside the skin provide evidence that the elements not only can enter the cortex via the matrix but also via the hair root sheaths. Moreover, there are indications that the distribution of an endogenous element is not always homogeneously spread over a cross section of the hair. Endogenous Fe and Pb seem to be peaked on the periphery of the hair by natural means, while the elements S,Zn and Cu of the samples measured are found to be distributed homogeneously across the hair diameter. The consequences for hair analysis in use for monitoring the trace elements status of an individual are discussed.

First microdosimetric measurements with a TEPC based on a GEM.

A new type of mini multi-element tissue-equivalent proportional counter (TEPC) based on a gas electron multiplier (GEM) has been designed and constructed. This counter is in particular suitable to be constructed with a small sensitive volume so that it can be used for microdosimetry in intense pulsed radiation fields to measure the microdosimetric spectrum in the beam of, for instance, a clinical linear accelerator. The concept lends itself also for a mini multi-element version of the counter to be used for applications in which a high sensitivity is required. In this paper, we present the first microdosimetric measurements of this novel counter exposed to a 14 MeV monoenergetic neutron beam and a californium (252Cf) source for a counter cavity diameter of 1.8 mm simulating 1.0 microm tissue site size. The measured spectra showed an excellent agreement with spectra from the literature. The specific advantages of the TEPC-GEM are discussed.

Fast-neutron OSL sensitivity of thallium-doped ammonium salts.

The main problem in selecting suitable thermoluminescent (TL) materials for fast-neutron dosimetry is finding a material that is both tissue-equivalent and not damaged upon heating. Optically stimulated luminescence (OSL) avoids the need to heat the materials and allows the use of materials with a high content of hydrogen (responsible for 90% of the absorbed dose of fast-neutrons). The choice of studying the ammonium salts for their OSL properties was based on the calculation of their neutron kerma factor. A constant ratio of an ammonium salt's kerma coefficients to the tissue's kerma coefficients (in the fast-neutron range) is a prerequisite for a similar energy response to neutrons, i.e. tissue equivalency. The salts studied are NH4Br and (NH4)2SiF6 both doped with Tl+. This paper describes the OSL properties of Tl(+)-doped NH4Br and (NH4)2SiF6 after exposure to 14.5 MeV neutrons to explore their potential for developing new, tissue-equivalent OSL materials suitable for fast-neutron dosimetry. The relative neutron sensitivity, k, defined as the ratio of the sensitivity of the material to neutrons to its sensitivity to gamma rays, has been determined for 14.5 MeV neutrons and varies between k = 0.15 and k = 0.5. The latter value is a factor 2.5 higher than that found for known TL materials (k < or = 0.2). A drawback of these materials is the fast fading of the OSL signal.

A TL/OSL emission spectrometer extension of the Risø reader.

The integration of a low cost, compact sized spectrometer with the Risø reader is described. The luminescence light emitted by the sample is transmitted by an optical fibre onto a fixed entrance slit of a spectrograph. The light is measured with a high sensitivity 2048-element CCD-linear array detector (Avantes PC2000) sensitive in the UV-VIS region. The CCD array has a low readout noise and a photon sensitivity of 86 photons per count. Examples are given of both thermally and optically stimulated 3-D spectra showing the luminescence spectra as a function of temperature and time respectively. Spectra from CaF2:Tm (TLD-300) chips could be distinguished from the background (2 SD) at a 0.7 Gy dose level.

Optically and thermally stimulated luminescence of KMgF3:Ce3 and NaMgF3:Ce3+.

The potentialities of optically stimulated luminescence (OSL) for personal dosimetry of ionising radiation have stimulated the search for new synthetic materials with good dosimetric properties. The sensitivity of two new OSL materials KMgF3 and NaMgF3 doped with Ce3+ ions has been evaluated and found to be of the same order of magnitude as that of Al2O3:C. Several other characteristics have also been investigated. Promising results for KMgF3:Ce are the high sensitivity and the low fading. However, this material suffers from a high self-dose due to the presence of 40K. NaMgF5:Ce is sensitive as well but shows strong fading. Interesting information on the mechanism has been obtained by correlating the signals of OSL and TL. Furthermore, the different bleachabilities under blue LED illumination of the strongly overlapping glow peaks allowed the extraction of one single peak for KMgF3:Ce3+. The results demonstrate new possibilities offered by the combination of TL and OSL.

[Effects of aging on urinary secretion of 3-hydroxyproline and its importance for cancer screening in the elderly with ROC analysis].

OBJECTIVE: to observe the influence of aging on urinary secretion of 3-hydroxyproline (3-Hyp) in normal subjects and in cancer patients and study the effects of aging on the accuracy of urinary 3-Hyp as a general-purpose cancer screening test. DESIGN: We reanalyzed, from the aspect of gerontology, the amounts of 3-Hyp in the urine samples of the 211 healthy persons and 94 patients with cancer reported earlier. The two groups were divided in 3 age subgroups: adult, 30 to 44 years, middle-aged, 45 to 64 years, and aged, 65 years and older. The cancer stage was separated into 3 categories: stage 1, the early stage without any invasion, stage 2, locally invasive with no distant metastasis, and stage 3, advanced cancer. The correlation of age and urinary 3-Hyp was analyzed in normal subjects and cancer patients. Sensitivity and specificity were calculated for different cutoff points in the diverse groups to construct the receiver operating characteristic (ROC) curves. MAIN RESULTS: We observed that aging decreases the urinary secretion of 3-Hyp in normal subjects, with a correlation coefficient of -0.250 (p < 0.001). The mean levels of urinary 3-Hyp in patients with cancer were significantly higher than in the normal subjects, p = 0.005. The correlation coefficient of urinary 3-Hyp and age was not significant (0.100) in cancer patients. The cutoff points of 0.800 mg/g creatinine of urinary 3-Hyp for persons under 65 years of age and 0.600 mg/g creatinine for persons 65 years or older were the best thresholds for cancer screening. In the ROC analyses, we observed that 3-Hyp has higher accuracy for cancer screening in the aged group for all stages together and in the aged and middle-aged for early stages of cancer. CONCLUSIONS: The urinary 3-Hyp test was more effective for cancer screening in old persons (65 years or older), where cancer is more frequent and more difficult to discover. The authors stress the necessity and importance of verifying the effectiveness of urinary 3-Hyp for general cancer screening in a larger population and in a community set.

The relationship of obesity and the development of coronary heart disease to longitudinal changes in systolic blood pressure.

In an investigation of the relationship of obesity and the development of coronary heart disease (CHD) to longitudinal changes in systolic blood pressure (SBP), a sample of 1029 male participants from the Baltimore Longitudinal Study of Baltimore (BLSA), who were free of CHD at the beginning of the study, were examined with a total of 4111 examinations (mean of four examinations per person) conducted during the study period. The mean follow-up time was 8.1 years with a maximum of 16 examinations and 30.9 years of follow-up. During the follow-up period, 192 participants developed CHD, and these participants' data collected after the CHD event were excluded from the analysis. A proportional hazards regression model was used to calculate the relative risk of developing CHD for several CHD risk factors. Both simple and multiple proportional hazards regression models indicate a strong association between body mass index (BMI), cholesterol, cigarette smoking, and systolic blood pressure (SBP) with the risk of developing CHD. In addition, a linear mixed-effects model was used to examine changes in SBP measurements over time and to identify factors, including the age at first examination and time in study, that are related to that change. The results from the linear mixed-effects model analysis indicate that those in the obese group (BMI > or = 30 kg/m2) have SBP measurements that are on average 9.0 mm Hg higher than those in the normal group (20 < or = BMI < 25). Also, SPB measurements were on average 6.6 mm Hg higher in those who developed CHD during the study period than those who remained free of disease. In addition, SPB showed a quadratic relationship with time, and its patterns of change with time were different among the different age groups. Also, the relationship between changes in SBP with respect to cholesterol was dependent on time in the study as well.

Comparative epidemiology of oral cancer in Brazil and India.

A comparison of the risk factors and occurrence of oral cancer in Brazil and India is presented. These two countries have among the highest incidence rates for such cancer in the world. A distinct pattern of risk factors was observed for each country: in India, tobacco chewing was the predominant risk factor: in Brazil, the major risk factor was the combination of tobacco smoking and alcohol consumption. Observations by descriptive epidemiology reveal high age-standardized incidence rates of oral cancer along with some distinctive differences associated with age distribution, sex ratios, and trends in each country. The desirability of additional oral cancer prevention research is also emphasized.

Luminescence emission from metastable Sm2+ defects in Y PO4:Ce,Sm.

Ce(3+) and Sm(3+) both form stable defect centres in Y PO(4), and their emission properties are well known. However, by irradiating co-doped Y PO(4):Ce,Sm with x-rays or UV light the charge states of the defects can be modified to become Ce(4+) and Sm(2+), which are metastable, and their behaviour acts as a model system for understanding carrier dynamics in charge storage phosphors. Here we report on the luminescence emission behaviour of the Sm(2+) defects that can be observed after x-irradiation. Under suitable excitation conditions, emission from both the stable Sm(3+) and metastable Sm(2+) can be monitored simultaneously. The Sm(2+) luminescence is found to be comprised of a series of narrow lines in the energy range 1.5-1.8 eV, identifiable as internal 4f-4f transitions, accompanied by a series of phonon replicas (phonon energy, 20.4 meV). The intensity of the metastable Sm(2+) emission increases in proportion to the x-irradiation time as their population is increased; under 1.92 eV laser stimulation, the PL is found to fully quench at temperatures above 150 K due to photo-thermal ionization of the defect.

[Comparison between subjective and objective methods for sodium intake estimate among hypertensive persons]. / Comparación entre los métodos subjetivo y objetivo para estimar el consumo de sodio en hipertensos.

INTRODUCTION: High sodium intake contributes to arterial hypertension; the relationship between high blood pressure and human aging is stronger among populations with high sodium intake. OBJECTIVES: The aim of this research is to compare subjective and objective methods on the estimate of the consumption of sodium. METHODS: This is a retrospective investigation along with secondary topics from the raw data base. The subjective method used was result of the score of the application of a questionary about the sodium intake, where the sodium consumption report was converted into daily mg of sodium intake. The objective method was the result of the urine excretion of hypertensive persons older than 50 years during 24 hours. The topics were analyzed by the software SPSS using the Spearman correlation. RESULTS: The main results did not show a significant linear correlation between the values of the sodium intake reported in the questionnaire and the values of the sodium (Na) 24 h collections. CONCLUSION: New studies possibly will elucidate the present results among the divergence faced with other studies.