Revising two-point discrimination assessment in normal aging and in patients with polyneuropathies.

OBJECTIVES: To revise the static and dynamic normative values for the two-point discrimination test and to examine its applicability and validity in patients with a polyneuropathy. METHODS: Two-point discrimination threshold values were assessed in 427 healthy controls and 99 patients mildly affected by a polyneuropathy. The controls were divided into seven age groups ranging from 20-29, 30-39,..., up to 80 years and older; each group consisted of at least 30 men and 30 women. Two-point discrimination examination took place under standardised conditions on the index finger. Correlation studies were performed between the scores obtained and the values derived from the Weinstein Enhanced Sensory Test (WEST) and the arm grade of the Overall Disability SumScore (ODSS) in the patients' group (validity studies). Finally, the sensitivity to detect patients mildly affected by a polyneuropathy was evaluated for static and dynamic assessments. RESULTS: There was a significant age-dependent increase in the two-point discrimination values. No significant gender difference was found. The dynamic threshold values were lower than the static scores. The two-point discrimination values obtained correlated significantly with the arm grade of the ODSS (static values: r = 0.33, p = 0.04; dynamic values: r = 0.37, p = 0.02) and the scores of the WEST in patients (static values: r = 0.58, p = 0.0001; dynamic values: r = 0.55, p = 0.0002). The sensitivity for the static and dynamic threshold values was 28% and 33%, respectively. CONCLUSION: This study provides age-related normative two-point discrimination threshold values using a two-point discriminator (an aesthesiometer). This easily applicable instrument could be used as part of a more extensive neurological sensory evaluation.

Determination of soil, sand and ore primordial radionuclide concentrations by full-spectrum analyses of high-purity germanium detector spectra.

The full-spectrum analysis (FSA) method was used to determine primordial activity concentrations (ACs) in soil, sand and ore samples, in conjunction with a HPGe detector. FSA involves the least-squares fitting of sample spectra by linear combinations of (238)U, (232)Th and (40)K standard spectra. The differences between the FSA results and those from traditional windows analyses (using regions-of-interest around selected photopeaks) are less than 10% for all samples except zircon ore, where FSA yielded an unphysical (40)K AC.

Gamma-ray spectrometry of radon in water and the role of radon to representatively sample aquifers.

Measurement of radon in water by gamma-ray spectrometry using a HPGe detector has been investigated to determine aquifer characteristics. The radon activity concentration is determined by taking the weighted average of the concentrations derived from gamma-ray lines associated with (214)Pb and (214)Bi decay. The role of accurate radon data to representatively sample aquifers was also investigated by studying a semi-cased borehole. A simplified physical model describing the change of radon concentration with the pumping time, reproduces the data and predicts the time for representative sampling of the aquifer.

Long-life vibration-free 4.5 K sorption cooler for space applications.

A breadboard 4.5 K helium sorption cooler for use in vibration-sensitive space missions was developed and successfully tested. This type of cooler has no moving parts and is, therefore, essentially vibration-free. The absence of moving parts also simplifies scaling down of the cooler to small sizes, and it contributes to achieving a very long lifetime. In addition, the cooler operates with limited dc's so that hardly any electromagnetic interference is generated. This cooler is a favorite option for future missions such as ESA's Darwin mission, a space interferometer in which the sensitive optics and detectors can hardly accept any vibration. The system design consists of a hydrogen stage cooling from 80 to 14.5 K and a helium stage establishing 5 mW at 4.5 K. Both stages use microporous activated carbon as the adsorption material. The two cooler stages need about 3.5 W of total input power and are heat sunk at two passive radiators at temperatures of about 50 and 80 K-radiators which are constructed at the cold side of the spacecraft. We developed, built, and tested a demonstrator of the helium cooler. This demonstrator has four sorption compressor cells in two compressor stages. Test experiments on this cooler showed that it performs within all specifications imposed by ESA. The cooler delivered 4.5 mW at 4.5 K with a long-term temperature stability of 1 mK and an input power of 1.96 W. So far, the cooler has operated continuously for a period of 2.5 months and has not shown any sign of performance degradation.

Detection by competitive enzyme-linked immunosorbent assay of a bovine serum albumin peptide (ABBOS) in infant formulas based on hydrolyzed cow's milk protein.

OBJECTIVE: Our aim was to determine whether currently available products based on hydrolyzed milk protein and a small peptide (ABBOS) in bovine serum albumin (BSA) (positions 126-144) share common antigenic sites. The commercial products are primarily developed to reduce cow's milk protein-associated allergenicity, but whether they also could be used in intervention trials to elucidate the role of BSA in the etiology of IDDM is not known. RESEARCH DESIGN AND METHODS: A sensitive competitive enzyme-linked immunosorbent assay (ELISA) using a rabbit polyclonal antibody raised against the ABBOS peptide in BSA was developed. With this method, we determined cross-reactivity between the ABBOS peptide and commercially available products: four milk protein hydrolysates and eight infant formulas based on hydrolyzed milk protein. The products were further characterized by physicochemical techniques. RESULTS: Hydrolyzed milk protein products are found to inhibit competitively the binding of ABBOS peptide to antibody. The number of residual reactive sites varied considerably among products and was not strongly related to the degree of hydrolysis (DH) or the molecular mass distribution of the hydrolysates. CONCLUSIONS: The presence of possible immunoreactive peptides in infant formulas based on hydrolyzed cow's milk protein cannot be adequately predicted by the DH or molecular mass distribution of the hydrolysates. Its specific determination is needed to ensure infant formulas free of cross-reactive ABBOS antibody binding sites for use in ongoing and forthcoming intervention trials to elucidate the role of BSA as a possible environmental triggering agent of IDDM.

Incomplete elimination of the ABBOS epitope of bovine serum albumin under simulated gastrointestinal conditions of infants.

OBJECTIVE: Because the bovine serum albumin residues 126-144 (ABBOS) have been reported to be responsible for the autoimmune reaction directed against pancreatic islet cells, it was our aim to study the potential survival of the ABBOS epitope during digestion in the gastrointestinal tract. RESEARCH DESIGN AND METHODS: Either nontreated (commercially available) or heat-treated bovine serum albumin (BSA) was hydrolyzed in vitro with pepsin at a pH of 2.0, 3.0, and 4.0 and subsequently with pancreatic enzymes at a pH of 7.5. Cross-reactivity between the ABBOS peptide and the BSA hydrolysates was determined by competitive enzyme-linked immunosorbent assay (ELISA) using a rabbit polyclonal antibody raised against the ABBOS peptide in BSA. RESULTS: Biochemical findings clearly showed that the degradation of BSA during simulated physiological digestion depended on its conformation and on the pH of its pepsin-catalyzed hydrolysis. Raising the pH of the pepsin-catalyzed hydrolysis from 2.0 to 4.0 decreased the efficiency of the process, especially when BSA had first been denatured by heat treatment. As a consequence, a large proportion of the cross-reactive anti-ABBOS antibody-binding sites was still intact in the final hydrolysates. CONCLUSIONS: The present results suggest that the ABBOS epitope of BSA will not be completely eliminated during digestion under conditions that prevail in the stomach of infants (pH 3-4).

Effect of paracetamol (acetaminophen) on body temperature in acute ischemic stroke: a double-blind, randomized phase II clinical trial.

BACKGROUND AND PURPOSE: Body temperature is a strong predictor of outcome in acute stroke. However, it is unknown whether antipyretic treatment leads to early and clinically worthwhile reduction of body temperature in patients with acute stroke, especially when they have no fever. The main purpose of this trial was to study whether early treatment of acute ischemic stroke patients with acetaminophen (paracetamol) reduces body temperature. METHODS: Seventy-five patients with acute ischemic stroke confined to the anterior circulation were randomized to treatment with either 500 mg (low dose) or 1000 mg (high dose) acetaminophen or with placebo, administered as suppositories 6 times daily during 5 days. Body temperatures were measured with a rectal electronic thermometer at the start of treatment and after 24 hours and with an infrared tympanic thermometer at 2-hour intervals during the first 24 hours and at 6-hour intervals thereafter. The primary outcome measure was rectal temperature at 24 hours after the start of treatment. RESULTS: Treatment with high-dose acetaminophen resulted in 0.4 degrees C lower body temperatures than placebo treatment at 24 hours (95% CI 0.1 degrees C to 0.7 degrees C). The mean reduction from baseline temperature with high-dose acetaminophen was 0.3 degrees C (95% CI 0 degrees C to 0.6 degrees C) higher than that in placebo-treated patients. Treatment with low-dose acetaminophen did not result in lower body temperatures. After 5 days of treatment, no differences in temperature were found between the placebo and the high- or low-dose acetaminophen groups. CONCLUSIONS: Treatment with a daily dose of 6000 mg acetaminophen may result in a small, but potentially beneficial, decrease in body temperature shortly after ischemic stroke, even in normothermic and subfebrile patients. Further studies should determine whether this effect is reproducible and whether early reduction of body temperature leads to improved outcome.

Resorption of cesium radionuclides by various fungi.

Uptake of 134Cs, 137Cs and 40K is determined by gamma-ray spectroscopy for samples of fungi and humus. For these samples also the stable Cs content is determined by atomic absorption spectrophotometry. The fungi resorpted only the alkali metals and none of the other fission products from the Chernobyl accident. The measurements show a large variation in space and time for fungi of the same species in the stable and radioactive cesium content. Compared to this variation the variation between the different species is in general small. Cs content in mycorrhizal fungi is in general higher than in saprophytic fungi, but differences in absorption in saprophytic and mycorrhizal fungi could not be confirmed. The assumption that certain saprophytic fungi mainly grow in either litter, fermentation or humus layer is not supported by this experiment.

Selective hydrolysis of milk proteins to facilitate the elimination of the ABBOS epitope of bovine serum albumin and other immunoreactive epitopes.

Milk proteins are hydrolyzed to prevent immunological reactions, but immunoreactive epitopes, including the ABBOS epitope of bovine serum albumin (BSA), can still be detected in commercially available milk protein hydrolysates. We used lactococcal cell-envelope proteinase (CEP) for the hydrolysis of the individual milk proteins and of mixtures thereof, or for the hydrolysis of sodium caseinate (contaminated with whey proteins). CEP exclusively degraded casein, leaving the four major whey proteins intact. This property facilitated the removal of the intact whey proteins from the casein fragments by ultrafiltration. Depending on the molecular mass of the whey protein to be removed, membranes with cutoff values between 3 and 30 kDa were used, resulting in casein hydrolysates free of protein fragments with cross-reactive whey-protein-specific IgE (immunoglobulin E) or ABBOS antibody-binding sites. Even the casein itself was degraded in such a way by CEP that cross-reactive casein-specific IgE antibody-binding sites could be eliminated. The product could find application in infant formulas for therapeutic and preventive treatment of children with cow's milk allergy; in addition, the preventive use of such formulas in children genetically susceptible to the development of insulin-dependent diabetes mellitus (IDDM) should be considered if a relationship between the consumption of BSA and IDDM were to become more apparent. The method is also applicable for preparing casein-free whey protein preparations.

Measurements of time-averaged radon-daughter concentrations with passive dosemeters.

With standard dosemeters of the Karlsruhe type it is possible to measure simultaneously time-integrated radon and radon-daughter concentrations. For this purpose the dosemeters were equipped with a lid and a bottom foil. Pre-etching conditions for either type of foil were optimized; under these conditions no effects of plate-out were observed. The method seems to be sensitive to neutral radon daughters only. Possible improvements of the dosemeter geometry are indicated.

Survey of radon concentrations in Dutch dwellings.

A survey of radon concentrations in Dutch dwellings reveals a median value of 24 Bq/m3, while no excessive high values were observed. Correlations between radon concentration and (combinations of) building parameters will be presented and discussed in terms of the various sources of indoor radon.

Experimental set-up for measuring diffusive and advective transport of radon through building materials.

This study describes an approach for measuring and modelling diffusive and advective transport of radon through building materials. The goal of these measurements and model calculations is to improve our understanding concerning the factors influencing the transport of radon through building materials. To reach this goal, a number of experiments have to be conducted. These experiments, including measurements in a large cylinder for creating diffusive and advective transport of radon under controlled, 'dwelling-like' conditions, are described here and the initial results are presented. A better understanding about the transport of radon through building materials will lead to more effective ways to decrease or to prevent the entrance of radon into dwellings.

Lowering body temperature in acute ischemic stroke without artificial ventilation and heavy sedation: a feasibility study.

BACKGROUND AND PURPOSE: We assessed the feasibility of inducing very mild hypothermia in 8 patients with acute ischemic anterior circulation stroke, without artificial ventilation and heavy sedation, until 24 hours after onset of symptoms. METHODS: Four regimes (A, B, C, and D) with increasing monitoring and treatment intensity were studied. Two patients in in regime A were monitored only. In regime B, 2 patients were treated with acetaminophen suppositoria of 1 g at 4-hour intervals. Additionally, the patients in regime C were cooled with a cooling blanket until 24 hours after the onset of symptoms. The target body temperature was 35 degrees C to 36 degrees C. During the cooling procedure, slight sedation was induced by continuous intravenous administration of low-dose midazolam. In regime D, sponging with 70% alcohol could be applied. RESULTS: In these 4 patients, the mean reduction in body temperature after 8 hours of treatment amounted to 1.25 degrees C. No clinically important changes in vital parameters occurred. CONCLUSIONS: The present study suggests that mild hypothermia in noncomatose stroke patients during a period of 24 hours after the ictus may be accomplished with a cooling blanket and light sedation with midazolam in a well-equipped stroke unit.

Moisture dependence of radon transport in concrete: measurements and modeling.

The moisture dependence of the radon-release rate of concrete was measured under well controlled conditions. It was found that the radon-release rate almost linearly increases up to moisture contents of 50 to 60%. At 70 to 80% a maximum was found and for higher moisture contents the radon-release rate decreases very steeply. It is demonstrated that this dependence can be successfully modeled on basis of the multi-phase radon-transport equation in which values for various input parameters (porosity, diffusion coefficient, emanation factor, etc.) were obtained from independent measurements. Furthermore, a concrete structure development model was used to predict at any moment in time the values of input parameters that depend on the evolution of the concrete microstructure. Information on the concrete manufacturing recipe and curing conditions (temperature, relative humidity) was used as input for the concrete structure model. The combined radon transport and concrete structure model supplied sufficient information to assess the influence of relative humidity on the radon source and barrier aspects of concrete. More specifically, the model has been applied to estimate the relative contributions to the radon exhalation rate of a 20-cm-thick concrete slab of radon produced in the concrete slab itself and due to diffusive transport through the slab of radon from soil gas.

Measurements of radon-daughter concentrations in and around dwellings in the northern part of The Netherlands; a search for the influences of building materials, construction and ventilation.

The concentration of radon daughters has been determined in and around 80 dwellings located in the northern part of the Netherlands by using a one-filter method. Median values of 2.0 and 0.4 mWL were measured for the indoor and outdoor concentrations, respectively. The average outdoor concentration was about an order of magnitude higher for wind directions between SE and SW than for SW-NW. On the average, dwellings with double-pane windows and/or concrete floors were found to have significantly higher radon concentrations than those with single-pane windows and/or wooden floors. For the living room of a particular dwelling 18 measurements were carried out. The data for this dwelling indicate a linear relation between the concentration indoors and outdoors with a slope of 3.8 +/- 2.0. This unexpected behaviour is thought to be related to ventilation via the crawl space. Measurements of ventilation patterns and measurements of radon concentrations in the living room and the crawl space are consistent with this picture.

Combined diffusive and advective transport of radon in a homogeneous column of dry sand.

To validate a model for radon transport in soil, measurements of combined advective and diffusive radon transport under well-defined and controlled conditions have been made in a homogeneous column of dry sand with and without an air-filled volume on top. This volume simulates a crawl space. The measurements concern steady-state as well as time-dependent combined advective and diffusive transport and are performed in the framework of a systematic validation study which will also cover more complex situations (e.g., presence of pore-water). The experimental data were compared with results of a two-dimensional numerical model based on the finite-difference approach of the differential equation describing radon transport. Validations of the numerical model with analytical solutions were carried out for one-dimensional steady-state combined diffusive and advective transport, and for two-dimensional time-dependent diffusive transport. The results of the measurements with combined advective and diffusive transport are in good agreement with (numerical) model calculations with maximum deviations <10%.

Diffusive transport of radon in a column of moisturized sand.

Diffusive transport of radon in a moisturized sand column was investigated under well-defined and controlled conditions using a laboratory facility that consists of a cylindrical vessel (height and diameter 2 m) filled with sand. Equilibrium pore-gas radon-concentration profiles in the sand column were measured as a function of depth for several different levels of the ground-water table. The measurements were performed in the framework of a systematic validation study that also covered experiments with dry sand. The experimental data were compared with results of model calculations. Most parameters in the transport model were obtained from separate experiments on small sand samples. In this manner, the radon diffusion coefficient and emanation coefficient were determined as functions of pore-water content, as well as the water-retention characteristics of the sand. In general, the experimental data are reasonably well reproduced by the calculations with differences of 10%-40%. However, with respect to earlier results with dry sand indicating differences of generally smaller than 10%, the agreement between experiment and model for moisturized sand is clearly worse. The main part of the disagreement probably results from inhomegeneities in the sand column that are not accounted for in the transport model.

Diffusive transport of radon in a homogeneous column of dry sand.

To validate a model for radon transport in soil, measurements of diffusive radon transport under well-defined and controlled conditions have been made in a homogeneous column of dry sand with an air-filled volume on top. This volume simulates a crawl space. The measurements concern time-dependent diffusive transport with several different crawl-space heights and steady-state diffusive transport with different crawl-space ventilation rates. This study forms part of an extensive validation which will also cover more complex situations (e.g., advective transport, presence of pore-water). Properties of the sand that are presently being used in the radon transport model were determined from independent measurements. The comparison between model calculations and experimental results showed a good correspondence with maximum deviations of less than 10%.

Radionuclide concentrations in the northern part of The Netherlands after the Chernobyl reactor accident.

Concentrations of radionuclides originating from the Chernobyl reactor accident were measured as a function of time in air, rainwater, grass, cow's milk, vegetables and dust by means of high-resolution gamma-ray spectroscopy. Special attention was paid to grass and milk originating from the same meadows. Also, milk of cows temporarily kept inside after the accident was monitored until a few days after their release from the stables. Activity ratios in various types of samples and the implication of the sheltering measures for cows are discussed.

Foil coverage of a crawl-space floor: measurements and modeling of radon entry.

The mitigative impact of covering the floor of a crawl space with a membrane has been studied under well-defined and controlled conditions. The measurements have been done with a homogeneous column of dry sand covered with a sheet of polyethylene foil. An air-filled volume on top of the column simulates a crawl space. The experiments mainly concern long-term measurements of the crawl-space radon concentration in combination with steady-state diffusive and combined advective and diffusive transport through the sand column and crawl space. The experimental data are analyzed with both simplified mass-balance models for radon entry into the crawl space and with a two-dimensional numerical model based on a finite-difference approach. In all experiments the influence of atmospheric pressure variations is clearly present. For most experiments the agreement between calculations, which make use of independently measured transport parameters for both sand and foil, and measurements is within 10%. However, the discrepancy is larger for experiments with continuous advective transport from the crawl space to the sand. With undamaged foil, the calculations overestimate the measurements by 20%. Reversely, with an opening in the center of the foil, the calculations underestimate the measurements by 20-40%. The results show that under controlled conditions radon transport from a foil-covered sand column into a crawl-space can be described within 40% on basis of separately measured parameters.