Both resistance- and endurance-type exercise reduce the prevalence of hyperglycaemia in individuals with impaired glucose tolerance and in insulin-treated and non-insulin-treated type 2 diabetic patients.

AIMS/HYPOTHESIS: The present study compares the impact of endurance- vs resistance-type exercise on subsequent 24 h blood glucose homeostasis in individuals with impaired glucose tolerance (IGT) and type 2 diabetes. METHODS: Fifteen individuals with IGT, 15 type 2 diabetic patients treated with exogenous insulin (INS), and 15 type 2 diabetic patients treated with oral glucose-lowering medication (OGLM) participated in a randomised crossover experiment. Participants were studied on three occasions for 3 days under strict dietary standardisation, but otherwise free-living conditions. Blood glucose homeostasis was assessed by ambulatory continuous glucose monitoring over the 24 h period following a 45 min session of resistance-type exercise (75% one repetition maximum), endurance-type exercise (50% maximum workload capacity) or no exercise at all. RESULTS: Average 24 h blood glucose concentrations were reduced from 7.4 ± 0.2, 9.6 ± 0.5 and 9.2 ± 0.7 mmol/l during the control experiment to 6.9 ± 0.2, 8.6 ± 0.4 and 8.1 ± 0.5 mmol/l (resistance-type exercise) and 6.8 ± 0.2, 8.6 ± 0.5 and 8.5 ± 0.5 mmol/l (endurance-type exercise) over the 24 h period following a single bout of exercise in the IGT, OGLM and INS groups, respectively (p < 0.001 for both treatments). The prevalence of hyperglycaemia (blood glucose >10 mmol/l) was reduced by 35 ± 7 and 33 ± 11% over the 24 h period following a single session of resistance- and endurance-type exercise, respectively (p < 0.001 for both treatments). CONCLUSIONS/INTERPRETATION: A single session of resistance- or endurance-type exercise substantially reduces the prevalence of hyperglycaemia during the subsequent 24 h period in individuals with IGT, and in insulin-treated and non-insulin-treated type 2 diabetic patients. Both resistance- and endurance-type exercise can be integrated in exercise intervention programmes designed to improve glycaemic control. TRIAL REGISTRATION: Clinicaltrials.gov NCT00945165. FUNDING: The Netherlands Organization for Health Research and Development (ZonMw, the Netherlands).

Calculation of the indoor gamma dose rate distribution due to building materials in the Netherlands.

In this study, a model to determine the indoor absorbed dose rate in air due to building materials is applied to a representative set of 1336 Dutch dwellings of which the areas occupied by the various kinds of building material are well documented. Using a Monte Carlo method, the building material and housing data are combined with activity concentrations and densities of 90 samples of building material. From (100,000) repeated calculations according to the model, the distribution of the absorbed dose rate in Dutch livings is computed. The outcomes are compared with those of earlier national measuring campaigns on the indoor dose rate. When corrected for cosmic and terrestrial radiation, a similar distribution of the indoor dose rate is found with an average value within 5% of that found by measurements. A sensitivity analysis revealed that the three most influential input parameters of the model are the density and thickness of the construction parts, the presence of doors and windows and attenuation by the inner cavity wall.

Repeated-sprint performance and plasma responses following beetroot juice supplementation do not differ between recreational, competitive and elite sprint athletes.

PURPOSE: There is an ongoing debate whether highly trained athletes are less responsive to the ergogenic properties of nitrate. We assessed the effects of nitrate supplementation on plasma nitrate and nitrite concentrations and repeated-sprint performance in recreational, competitive and elite sprint athletes. METHODS: In a randomized double-blinded cross-over design, recreational cyclists (n = 20), national talent speed-skaters (n = 22) and Olympic-level track cyclists (n = 10) underwent two 6-day supplementation periods; 140 mL/d nitrate-rich (BR; ∼800 mg/d) and nitrate-depleted (PLA; ∼0.5 mg/d) beetroot juice. Blood samples were collected and three 30-s Wingate tests were performed. RESULTS: Plasma nitrate and nitrite concentrations were higher following BR vs PLA (P < .001), with no differences between sport levels (all P > .10). Peak power over the three Wingates was not different between BR and PLA (1338 ± 30 vs 1333 ± 30 W; P = .62), and there was no interaction between treatment (BR-PLA) and Wingate number (1-2-3; P = .48). Likewise, mean power did not differ between BR and PLA (P = .86). In contrast, time to peak power improved by ∼2.8% following BR vs PLA (P = .007). This improvement in BR vs PLA was not different between Wingate 1, 2 and 3. Moreover, the effects of BR vs PLA did not differ between sport levels for any Wingate parameter (all P > .30). CONCLUSION: The plasma and repeated-sprint performance responses to beetroot juice supplementation do not differ between recreational, competitive and elite sprint athletes. Beetroot juice supplementation reduces time to reach peak power, which may improve the capacity to accelerate during high-intensity and sprint tasks in recreational as well as elite athletes.

Scanning an individual monitoring database for multiple occurrences using bi-gram analysis.

Maintaining the integrity of the databases is one of the important aspects of quality assurance at individual monitoring services and national dose registers. This paper presents a method for finding and preventing the occurrence of duplicate entries in the databases that can occur, e.g. because of a variable spelling or misspelling of the name. The method is based on bi-gram text analysis techniques. The methods can also be used for retrieving dose data in historical databases in the framework of dose reconstruction efforts of persons of whom the spelling of the name as originally entered, possibly decades ago, is uncertain.

Evaluating the uncertainty in measurement of occupational exposure with personal dosemeters.

In the 1990 Recommendations of the ICRP it is stated that an uncertainty in a dose measured with a personal dosemeter under workplace conditions of a factor 1.5 in either direction 'will not be unusual'. In many documents similar to the EU Technical recommendations, the IAEA Safety Guides and papers in scientific journals, this statement is understood to be a basis for developing type-test criteria and criteria for the approval of dosimetric systems. The methods for evaluating the standard uncertainty as proposed in the above mentioned documents and in national and international standards use an approach that is based on the Law of Propagation of Uncertainties (LPU). This approach needs a number of assumptions, the validity of which cannot easily be verified for personal dosemeters. The current paper presents a numerical method based on Monte Carlo simulation for the calculation phase of the evaluation of uncertainties. The results of applying the method on the type-test data of the NRG TL-dosemeter indicate that the combined standard uncertainty estimated using the LPU approach might well not be realistic. The numerical method is simple and can be precisely formulated, making it suitable for being part of approval or accreditation procedures.

Thermoluminescence glow curve deconvolution and its statistical analysis using the flexibility of spreadsheet programs.

Analysing thermoluminescence glow curves involves the solving of a system of non-linear equations. These equations are either differential equations that must be solved numerically or functional approximations for their solution. The current paper presents software with the functions needed for the study of glow curves that is not a stand-alone computer program but an extension of MS Excel. It supplies functions that solve the general one trap model for the thermoluminescence process without the use of approximating functions. Combined with the Solver utility of Excel this gives a very flexible system for the analysis of glow curves. Functions for analysing the statistics of the deconvolution results are included.

On the assessment of the performance of personal dosemeters and individual monitoring services.

Based on recommendations of the International Commission on Radiological Protection, recommendations and requirements on the performance of dosimetric systems and individual monitoring services have been formulated in national and international standards and other documents of relevance. Although these all have essentially the same aim, the formulated criteria and the guidance given vary. Using the individual monitoring service of NRG in Arnhem and its thermoluminescence dosemeter as an example, the current paper reviews a number of ways to estimate the uncertainty in dose assessments and compares the criteria given in recommendations and standards. An attempt is made to contribute to some convergence of recommendations and requirements on aspects of dosimetric performance.

Uncertainties in personal dosimetry for external radiation: a Monte Carlo approach.

This paper explores the possibilities of numerical methods for uncertainty analysis of personal dosimetry systems. Using a numerical method based on Monte Carlo sampling the probability density function (PDF) of the dose measured using a personal dosemeter can be calculated using type-test measurements. From this PDF the combined standard uncertainty in the measurements with the dosemeter and the confidence interval can be calculated. The method calculates the output PDF directly from the PDFs of the inputs of the system such as the spectral distribution of the radiation and distributions of detector parameters like sensitivity and zero signal. The method can be used not only in its own right but also for validating other methods because it is not limited by restrictions that apply to using the Law of Propagation of Uncertainty and the Central Limit Theorem. The use of the method is demonstrated using the type-test data of the NRG-TLD.

Thermoluminescent detectors applied in individual monitoring of radiation workers in Europe--a review based on the EURADOS questionnaire.

Among the activities of EURADOS Working Group 2 formed by experts from several European countries is the harmonisation of individual monitoring as part of radiation protection of occupationally exposed persons. Here, we provide information about thermoluminescent detectors (TLDs) applied by the European dosimetric services and the dosimetric characteristics of dosemeters in which these detectors are applied. Among 91 services from 29 countries which responded to the EURADOS questionnaire, 61 apply dosemeters with TLDs for the determination of personal dose equivalent H(p)(10) for photons and beta radiation, and 16 services use TLDs for neutron albedo dosemeters. Those most frequently used are standard lithium fluoride TLDs (mainly TLD-100, TLD-700, Polish MTS-N and MTS-7, Russian DTG-4), high-sensitive lithium fluoride (GR-200, MCP-N) and lithium borate TLDs. Some services use calcium sulphate and calcium fluoride detectors. For neutron dosimetry, most services apply pairs of LiF:Mg,Ti TLDs with (6)Li and (7)Li. The characteristics (energy response) of individual dosemeters are mainly related to the energy response of the detectors and filters applied. The construction of filters in dosemeters applied for measurements of H(p)(10) and their energy response are also reviewed.

Individual monitoring for internal exposures in Europe: conclusions of an EURADOS action.

Once the EC Directive 96/29 has been implemented into national regulation across Europe, the coordination of dosimetry laboratories for the monitoring of occupational exposures becomes the principal aim to achieve. Within this framework the European Radiation Dosimetry Group, EURADOS, carried out an Action on 'Harmonisation of Individual Monitoring' (2000-2004) to promote coordination in the field of individual monitoring of occupational exposures throughout Europe. With reference to internal exposures, the main aims were the completion of a catalogue of internal dosimetry services and an inventory of methods and techniques used for individual monitoring at European internal dosimetry facilities. At the end of this EURADOS Action, a report was published in Radiation Protection Dosimetry in 2004. The information collected related to various topics: the equipments used for the measurement of internal exposures, calibration and sensitivity data, the methods applied for the assessment of internal doses, Quality Control procedures, Quality Assurance Programmes in the facilities and legal requirements. The information to be presented here will give a general overview of the actual status of individual monitoring for internal exposures in Europe.

Aspects of harmonisation of individual monitoring for external radiation in Europe: conclusions of a EURADOS action.

Following the publication of the EU Council Directive 96/29, EURADOS coordinated two working groups (WGs) for promoting the process of harmonisation on individual monitoring of occupationally exposed persons in Europe. An overview of the major findings of the second WG is presented. Information on the technical and quality standards and on the accreditation and approval procedures has been compiled. The catalogue of dosimetric services has been updated and extended. An overview of national regulations and standards for protection from radon and other natural sources in workplaces has been made, attempting to combine the results from individual monitoring for external, internal and workplace monitoring. A first status description of the active personal dosemeters, including legislative and technical information, and their implementation has been made. The importance of practical factors on the uncertainty in the dose measurement has been estimated. Even if a big progress has been made towards harmonisation, there is still work to be done.

UNCERTAINTY EVALUATION FOR MULTIDETECTOR PASSIVE DOSEMETERS USING A TWO-STAGE MEASUREMENT MODEL AND THE MONTE CARLO METHOD.

This paper proposes a method for evaluating the standard uncertainty in the measurements with passive personal dosemeters using a numerical method (Monte Carlo). The paper builds on a previous paper where a two-stage measurement model for passive dosemeters was proposed. This model follows the course of events during the measurement, which also consists of two stages: (1) the exposure of the dosemeter in the workplace where a signal develops in the form of, e.g. electron/hole pairs in solid-state detectors and film or damages to a molecular structure in track films, the latent signal and (2) the evaluation at the service where the latent signal is 'developed' into an observable signal. In this paper, the study is extended to multielement dosemeters that have multiple outputs. The charm of the proposed method is that it needs no mathematical approximations and does inherently include any correlations that may exist between input quantities and, in the case of multiple outputs like Hp(10) and Hp(0.07), between these outputs.

Heterologous Expression of Fungal Secondary Metabolite Pathways in the Aspergillus nidulans Host System.

Heterologous expression of fungal secondary metabolite genes allows for the product formation of otherwise silent secondary metabolite biosynthesis pathways. It also allows facile expression of mutants or combinations of genes not found in nature. This capability makes model fungi an ideal platform for synthetic biology. In this chapter a detailed description is provided of how to heterologously express any fungal secondary metabolite gene(s) in a well-developed host strain of Aspergillus nidulans. It covers all the necessary steps from identifying a gene(s) of interest to culturing mutant strains to produce secondary metabolites.

Influence of fluoride and carbonate on in vitro remineralization of bovine enamel.

The influence of fluoride, carbonate, and fluoride in combination with carbonate on the in vitro remineralization of bovine enamel was investigated with the use of a sandwich technique. After demineralization, enamel slices were subjected for 610 h to remineralizing solutions with 0.03 or 1.0 ppm fluoride. At each fluoride level, either 0, 1, 10, 20, or 25 mmol/L carbonate was tested. After 0, 22, 62, 126, 192, 329, and 610 h of remineralization, contact microradiographs were made by Cu K alpha-radiation. At 0.03 ppm fluoride, carbonate had an inhibiting influence on remineralization. At 1.0 ppm fluoride, the inhibiting influence of carbonate changed into a stimulation of remineralizatization at 20 and 25 mmol/L carbonate. At 0, 1, and 10 mmol/L carbonate, fluoride had an inhibiting influence on remineralization. The differences in remineralization between the groups were explained by events concerning crystal growth, i.e., different types of minerals might have precipitated with differences in precipitation rates, and retardation of a precipitation step might have occurred under the various remineralization conditions. There was a mutual influence of fluoride and carbonate on the remineralization process. We conclude that the composition of the remineralizing solution with respect to fluoride and carbonate concentrations is important for the remineralization process.

Dissolution and precipitation reactions in human tooth enamel under weak acid conditions.

Slices of enamel were demineralized in weak acid solutions at pH 5. The solutions were analysed for Ca, P, Na and Mg. A substantial increase of the Ca/P ratio in the solution after about 6 h of demineralization was ascribed to brushite formation. The ratios of liberated Ca/Na, P/Na, Ca/Mg and P/Mg were always lower than the correspondent ratios in sound enamel. It was concluded that precipitation of brushite, and a preferential dissolution of Na and Mg compounds from the enamel both play a role in the dissolution-precipitation reactions in dental enamel during acid attack.

Diffusion in mammalian tooth enamel in relation to the caries process.

For the rate of demineralization of enamel during caries, three physicochemical processes are of importance: the diffusion into and out of the enamel, the dissolution of mineral and the complexation of ions. The interpretation of diffusion experiments in conjunction with artificial caries experiments and computer simulations is described. In the caries process, relevant diffusion coefficients of small ions and molecules are of the order of magnitude 10(-9)--10(-7) cm2 s-1.

The mineral content of human enamel studied by polarizing microscopy, microradiography and scanning electron microscopy.

The total observed birefringence and mineral content of the outer 300 micron of longitudinal sections of sound buccal premolar enamel were measured and three-dimensional contour maps were made. Using similar contour maps of calcium, carbonate and magnesium content from the literature, it seemed possible to explain the differences between the contour maps of total observed birefringence and mineral content. Scanning electron micrographs provided information about the orientation of the prisms. The cervical part of the enamel had a high intrinsic birefringence which may explain the difference between mineral content and total observed birefringence. This high intrinsic birefringence may be caused by a high carbonate content in cervical enamel.

Effect of time, degree of saturation, pH and acid concentration of buffer solutions on the rate of in-vitro demineralization of human enamel.

The rate of demineralization of the artificial caries-like process was measured using two methods. The rate calculated from microradiography of the demineralized enamel appeared to be equal to the one calculated from calcium and phosphate analysis of the demineralizing buffer. In small volumes of demineralizing solution, the rate of demineralization decreased with time, due to the increase in saturation of the solution during the demineralization of the enamel. With increasing saturation, with respect to hydroxyapatite, and with increasing pH the rate of demineralization decreased. Increasing acid concentration had a marked influence only at the lower concentrations; a further increase had no effect on the rate of demineralization.

The effect of undissociated acetic-acid concentration of buffer solutions on artificial caries-like lesion formation in human tooth enamel.

A chemical system for lesion production was used. The influence on lesion characteristics of the concentration of undissociated acetic acid in a calcium and phosphate-containing buffer solution was investigated. Artificial lesions obtained after demineralization in buffers with a pH of 4.0, 4.5, 5.0 or 6.0 at 5 or 6 different acid concentrations for different demineralization times were investigated micro-radiographically. The lesion characteristics studied were: the mineral content of the surface layer; the mineral content of the body of the lesion; and the depth at which these mineral levels were reached; the depth of the lesion. The concentration of undissociated acetic acid had little effect on the lesion characteristics at low pH. When lower concentration buffers at pH 6.0 were used, the effect was more pronounced. At this level, the buffer capacity of the acetic acid/acetate buffer is small.

Caries in fissures of permanent first molars as a predictor for caries increment.

A group of 268 children were checked for caries experience at the age of 7.2 yr later at the age of 9 and 4 yr later at the age of 11 yr. Caries experience of fissures in permanent first molars at the age of 7 yr served as a screening criterion for caries increment between the ages of 7 and 11 yr. This screening resulted in a sensitivity of 0.62, a specificity of 0.82, and a diagnostic power of 0.83 for total caries increment in the permanent dentition and in a sensitivity of 0.68, a specificity of 0.80, and a diagnostic power of 0.78 for caries increment in fissures of permanent first molars. It was concluded that this screening offered the best method available for identifying children at risk from fissure caries in their permanent first molars. Cost effectiveness of preventive treatment directed towards individuals, for instance the application of fissure sealants, can be improved by using this screening method.