Low-frequency electromagnetic fields influence the expression of calcium metabolism related proteins in leukocytic cell lines.

Our study aimed to verify the hypothesis concerning low-frequency magnetic fields (LF-MFs)-related changes in cell viability through the biomechanism(s) based on calcineurin (CaN)-mediated signaling pathways triggered via ROS-like molecules. For experiments, Mono Mac 6 and U937 leukocytic cell lines were chosen and exposed to various LF-MFs and/or puromycin (PMC). The protein expression level of key regulatory proteins of calcium metabolism was examined by Western Blot analysis. In turn, the reactive oxygen species (ROS) and cell viability parameters were evaluated by cytochrome C reduction assay and flow cytometry, respectively. The simultaneous action of applied MF and PMC influenced cell viability in a MF-dependent manner. The changes in cell viability were correlated with protein expression and ROS levels. It was verified experimentally that applied stress stimuli influence cell susceptibility to undergo cell death. Moreover, the evoked bioeffects might be recognized as specific to both types of leukocyte populations.

A survey on electromagnetic hypersensitivity: the example from Poland.

Idiopathic environmental intolerance attributed to electromagnetic field (IEI-EMF) called electromagnetic hypersensitivity or electrosensitivity appeared in Polish society awareness due to a considerable change made at the end of 2019 in Polish telecommunication laws. The aims of the project were to access the prevalence of IEI-EMF in Poland and to define a reliable methodology to study this phenomenon. The first step was the internet survey performed at the end of 2018. The IEI-EMF prevalence estimated at the level of 39.7% suggested considerable bias affecting the results. The faults of the first approach were analysed and then a second study stage was performed as a telephone survey at the end of 2020. The latter survey allowed estimating the prevalence of IEI-EMF as less than 1.8%. These discrepancies in the results of both surveys were connected to the medium used in the first survey (Internet) indirectly causing that the group pooled was not representative. The second pitfall was the definition of the criteria used for an electrosensitive person classification. This is why the IEI-EMF prevalence was investigated in the second stage with the use of numerous criteria. The application of different criteria allowed for essential conclusions concerning the appropriate methodology for such kinds of studies. Corrections of the methodology before the second survey allowed reliable results consistent with the results obtained in similar studies performed in other countries. Our findings also show that the IEI-EMF frequency reports presented in the literature have to be treated carefully and with some dose of scepticism.

The Impact of Mobile Phone Use on Tinnitus: A Systematic Review and Meta-Analysis.

Tinnitus is a perception of sound in the absence of an external source. The aim of our study was to investigate with a meta-analytical approach, whether mobile phone (MP) use increases the risk of tinnitus. Eight studies reporting the risk of tinnitus in relation to MP use were identified, and six high-quality studies (two cohort studies, one case-control study, and three cross-sectional ones) were included in the meta-analysis. The quality assessment was performed using the Newcastle-Ottawa scale. The risk of tinnitus was analyzed depending on the exposure to MPs in subgroups according to the study design and method of exposure assessment. Two cohort studies, which assessed the exposure to MPs using network operator data, indicated no significantly increased risk of tinnitus among highly exposed MP users in comparison to lightly exposed individuals (odds ratio [OR]: 1.03 [95% confidence interval [CI]: 0.93-1.15]). Likewise, the self-reported exposure data from two cohorts/case-control and four cross-sectional studies did not find an association between exposure to MPs and tinnitus (OR: 1.20 [95% CI: 0.40-3.61] and OR: 1.73 [95% CI: 0.67-4.49], respectively). Current scientific knowledge, including high-quality studies with a reliable exposure assessment based on network operator data, does not support the hypothesis that MP use is associated with tinnitus. © 2020 Bioelectromagnetics Society.

Which sources of electromagnetic field are of the highest concern for electrosensitive individuals? - Questionnaire study with a literature review.

The primary goal of the study was to identify sources of electromagnetic field (EMF) which are attributed to negative health outcomes by a general population of electrohypersensitive (EHS) individuals. Secondary goal was to investigate the differences in indicated sources in subgroups distinguished based on gender, sex, place of living, place of work and the distance between place of living and the nearest mobile phone base station (MPBS). The cross-sectional study aiming to describe and analyze the population of EHS subjects was performed using a web-based questionnaire. The full survey consisted of 32 questions and concerned participants' baseline characteristics and details on sensitivity to electronic devices. Participants were regarded as EHS if they answered "yes" to the question "Do the electric/electronic/telecommunication devices negatively affect your well-being?" and indicated at least one device which in their opinion had such an impact. We identified 408 EHS subjects, out of which 288 (70.73%) were females and 120 (29.27%) were males. Phones, especially mobile devices, were attributed to negative health outcomes by the highest number of subjects (309, 75.74% and 267, 65.44% for phones and mobile phones, respectively). Additional subgroup analysis indicated that older participants and participants who live closer to MPBS more often complained of physical symptoms attributed to MPBS impact (p = .02 and p < .01, respectively). Phones, especially mobile devices, are the most important source of EMF influencing EHS subjects. People who self-reported living closer to MPBS and older individuals seem to be remarkably more concerned about MPBS health impact.

Does the short-term exposure to radiofrequency electromagnetic field originating from mobile phone affect auditory functions as measured by Acoustic Admittance and Evoked Otoacoustic Emission tests?

BACKGROUND: Mobile phones constitute an important source of radiofrequency electromagnetic field (RF-EMF) for humans. Taking into account high sensitivity of sensory hair cells of the inner ear to endogenous and exogenous agents, the potential impact of mobile phone usage on auditory organs is of particular interest. AIM: The aim of the study was to evaluate the impact of short-term exposure to RF-EMF generated by a mobile phone during 15-minute simulated phone call on human hearing as measured by Transient Evoked Otoacoustic Emission (TEOAE) and Acoustic Admittance Testing (AAT). MATERIAL AND METHODS: Within-subject study was performed on 23 healthy volunteers. All of the participants underwent TEOAE and AAT before and immediately after 15-minute simulated phone call with the use of a standard, modern smartphone. Analyzed parameters included: static compliance of tympanic membrane, middle ear pressure, ipsi- and contralateral acoustic reflex thresholds and percentage of signal reproducibility in TEOAE for exposed and non-exposed ear. Additionally, the results were compared in subgroups distinguished basing on self-reported sensitivity to RF-EMF originating from mobile phones. RESULTS: No statistically significant differences were identified between results of TEOAE and AAT before and after exposure, both in exposed and non-exposed ear. The results of EMF sensitive and non-sensitive subjects were comparable in all performed tests. CONCLUSIONS: Short-term exposure to mobile phone electromagnetic field did not influence auditory functions as measured by Evoked Otoacoustic Emission test and Acoustic Admittance Testing.

Physicochemical characterization of mineral deposits in human ligamenta flava.

The aim of our study was the detailed characterization of calcium deposits in ligamenta flava. The use of microcomputed tomography allowed extending the routine medical investigations to characterize mineral grains in the microscopic scale. A possible connection between spinal stenosis and ligament mineralization was investigated. The studies were carried out on 24 surgically removed ligamentum flavum samples divided into control and stenosis groups. Physicochemical characterization of the inorganic material was performed using X-ray fluorescence, X-ray diffraction, and Fourier transform infrared spectroscopy. The minerals were present in 14 of 24 ligament samples, both in stenosis and control groups. The inorganic substance constitutes on average ~0.1% of the sample volume. The minerals are scattered in the soft tissue matrix without any regular pattern. It was confirmed that minerals possess an internal structure and consist of the organic material and small inorganic grains mixture. The physicochemical analyses show that the predominant crystalline phase was hydroxyapatite (HAP). In the stenosis group calcium pyrophosphate dehydrate (CPPD) was identified. Both structures were never present in a single sample. Two different crystal structures suggest two independent processes of mineralization. The formation of CPPD may be treated as a more intense process since CPPD minerals are characterized by bigger values of the structural parameters and higher density than HAP deposits. The formation of HAP minerals is a soft tissue degeneration process that begins, in some cases, at early age or may not occur at all. Various density and volume of mineral grains indicate that the mineralization process does not occur in a constant environment and proceeds with various speeds. The formation of minerals in ligamenta flava is not directly associated with diagnosed spinal canal stenosis.

Repeated Transcranial Direct Current Stimulation Induces Behavioral, Metabolic and Neurochemical Effects in Rats on High-Calorie Diet.

Due to its high prevalence, obesity is considered an epidemic, which stimulated research on non-invasive methods to reduce excess body fat. Transcranial direct current stimulation (tDCS) is a non-invasive technique used to modulate the activity of cerebral cortex, which has already found increasing interest in medicine as a promising methodology. The aim of this study was to analyze the impact of tDCS on feeding behavior, metabolic abnormalities and neurotransmitters in certain brain areas involved in appetite control of obese rats. The male Wistar rats were divided into five subgroups depending on consumed diet effect (lean, obese) and tDCS type (anodal, cathodal, sham, and no stimulation). Two 10-min daily sessions of tDCS for 8 consecutive days of the study were applied. Rats subjected to active tDCS (anodal right or cathodal left of the prefrontal cortex) had reduced appetite and showed lesser body weight gain than the animals subjected to sham procedure or those receiving no stimulation at all. Furthermore, tDCS contributed to reduction of epididymal fat pads and to a decrease in blood concentration of leptin. Neurochemical examination revealed that tDCS modulated serotonin pathways of the reward-related brain areas and contributed to a significant decrease in the density of D2 but not D1 dopamine receptors in the dorsal striatum, recorded 5 h after the last stimulation. No significant effect of tDCS on dopamine and it's metabolites in examined brain regions was observed. It seems that the hypothalamus was not affected by tDCS application as no changes in measured neurotransmitters were detected at any examined time point. However, these results do not exclude the possibility of the delayed response of the monoamines in the examined brain areas to tDCS application. Altogether, these findings imply that repeated tDCS of the prefrontal cortex may change feeding behavior of obese rats. Either right anodal or left cathodal tDCS were sufficient to decrease food intake, to reduce body adiposity and to normalize other metabolic anomalies. These beneficial effects can be at least partially explained by changes in serotoninergic and in lesser extent dopaminergic system activity within some brain areas belonging to reward system.

Thermographic assessment of skin prick tests in comparison with the routine evaluation methods.

INTRODUCTION: The skin prick test is still the first and basic procedure in the diagnosis of allergic diseases. The possibility of using a sensitive thermographic method supported by the mathematical model for the assessment of skin test results will be highlighted in the studies. AIM: To compare the proposed approach with routine planimetric and thermographic methods. MATERIAL AND METHODS: A mathematical model of allergic reaction was developed. Simplifying assumptions of the IgE-mediated skin reaction is the essence of the model. Investigations were performed in a group of 40 patients. RESULTS: Using the spatio-temporal evolution of temperature distributions, the ratios of the histamine released from mast cells to the control histamine were determined. The obtained values very well correlate with the standard evaluation of skin prick tests (correlation coefficient = 0.98). CONCLUSIONS: The proposed method of skin test evaluation presents several advantages. The continuous acquisition of data provides the monitoring of time course of the allergic response. The transport of mediator and its concentration were distinctly discriminated, which may be diagnostically useful, especially for abnormal cases. The high sensitivity of the method enables studying patients regardless of age and skin sensitivity.

Cell viability modulation through changes of Ca(2+)-dependent signalling pathways.

The aim of the study was to determine the correlations between intracellular calcium ion level and a cell's ability to survive. The intracellular concentration of Ca(2+) ions, maintained through different mechanisms, plays an important role in signalling in cells. The deregulation of these mechanisms by various cell stressors (e.g. cytotoxic agents) can disturb Ca(2+) homeostasis and influence Ca(2+)-dependent signalling pathways in the cell. Perturbations of intracellular electrochemical equilibrium may lead to changes in cell function or even to cell death. According to some experimental results, one of the cell stressors may be exposure to magnetic fields (MF). Because of the wide distribution of MF sources in our environment, magnetic fields have recently been intensively examined in relation to the occurrence of cancer. Nevertheless, two questions still remain unanswered: Is the influence of MF on cells positive or negative, and what mechanism(s) underlie the effects of MF action on cells? Most studies focus on the influence of MF on Ca(2+) ion fluxes as calcium ions play the role of intracellular second messengers, triggering many signalling cascades. Physical models assuming the mechanisms generating the disturbance of ionic transport and/or the dysfunction of ion-protein complexes in cells due to MF action have been widely discussed in the literature, but a detailed explanation of experimental results is still awaited. The dynamics of the concentration of intracellular calcium ions can be detected by various methods, including optical and non-optical techniques. This review combines an insight into basic intracellular Ca(2+) regulative mechanisms and common techniques used to detect changes in Ca(2+) concentration inside the cell. The emphasis here is on the determination of Ca(2+) regulative mechanisms developed in non-excitable cells (e.g. U937 cells, HeLa, etc.), which are probably mainly involved in cell responses to external stress (e.g. MF stimuli).

The ratio of anterior and posterior vertebral heights reinforces the utility of DXA in assessment of vertebrae strength.

The objective of the study was to introduce a new parameter describing bone strength with greater precision than the widely used antero-posterior DXA (dual-energy X-ray absorptiometry), which measures areal bone mineral density (aBMD). The adjusted areal bone mineral density (AaBMD) defined as the ratio between aBMD and h a/h p (h a and h p: anterior and posterior vertebral body heights measured on the lateral view, respectively) is proposed: AaBMD = aBMD/(h a/h p). The utility of AaBMD in prediction of bone strength was assessed by in vitro measurements of cadaver L3 vertebrae. The AaBMD of 31 vertebrae was correlated with the ultimate stress (P max) and load (F max) values obtained in mechanical tests. The correlations were compared to those obtained for aBMD and for volumetric bone mineral density (vBMD) measured by computed tomography. The correlation of AaBMD to F max adjusted for donor's age was significantly higher than for aBMD and vBMD (r = 0.740, 0.658, and 0.609, respectively, p < 0.05). The differences between partial correlation coefficients for P max to AaBMD, aBMD and vBMD relationships were smaller (r = 0.764, 0.720, and 0.732, respectively, p < 0.05), but also showed the superiority of AaBMD. Combining antero-posterior DXA aBMD and the lateral h a/h p ratio, measured, for example, by the Vertebral Fracture Assessment software of the new generation of DXA devices, seems to accurately predict the mechanical vertebral parameters related to bone strength. It is assumed that the proposed AaBMD parameter may be more predictive for fracture risk assessment, which requires further studies.

Physicochemical and micro-tomographic characterization of inorganic deposits associated with aortic stenosis.

BACKGROUND AND THE AIM OF THE STUDY: A major feature of aortic stenosis is massive mineralization of the aortic valve, though the mechanism of the process remains unclear. The study aim was to characterize the chemical composition and morphology of inorganic deposits from surgically excised natural aortic valves and to seek similarities to minerals in bones and teeth. METHODS: Mineral deposits from 30 surgically excised natural aortic valves were examined. The control group consisted of autopsy samples (aortic valves, vertebral bodies) and teeth obtained after extraction. Micro-computed tomography (micro-CT) was used to describe the morphology and density of the minerals. X-ray fluorescence and Fourier transform infrared spectroscopy were applied to determine the chemical composition. RESULTS: A poorly crystalline, B-type carbonate-containing hydroxyapatite (HAP) was found to constitute the mineral phase of the aortic valve leaflets. No other chemical compounds were identified. The elemental composition of the minerals in aortic valves and bone/tooth did not differ markedly, except that the Mg concentration was fourfold higher in valve material. The aortic valve deposits were irregular in shape and occupied ca. 40% of the leaflet volume. The volume of the deposits were spread over a broad range (0.001-0.3 mm3), while the density ranged from that of dentine to enamel (average value 2.2 g/cm3), slightly higher than that of compact bone. CONCLUSION: The aortic valve deposits were identified as B-type carbonate-containing HAP, and were not identical to those found in bones and teeth, the main difference being a fourfold elevated Mg content. Mg may have been deposited as a separate compound, as micro-CT results suggested that the formation of mineral deposits in aortic valves was a multi-factorial process. The morphological parameters and densities of the valve deposits were spread over a broad range (factor approximately 300). An unequivocal identification of the mechanism responsible for the aortic valve pathological calcification was not possible, however.

A novel in-vitro model of human aortic valve mineralization.

BACKGROUND AND AIM OF THE STUDY: The study aim was to develop an in-vitro model of human aortic valve homograft (AVH) mineralization, as a basis for further research on the subject of calcific aortic valve disease (CAVD). METHODS: Human aortic valves were excised during autopsy (12-24 h post-mortem) from donors who had died due to accident or suicide. The mean (±SD) donor age was 32.5 ± 11.4 years. Under sterile conditions each aortic cusp (three cusps per valve) was cut in half to provide a total of 240 tissue samples. AVH mineralization was assessed in solutions with different Ca and P concentrations and CaxPO4 ionic product values. The impact of time on aortic valve mineralization rate was assessed using energy-dispersive X-ray fluorescence (ED-XRF). RESULTS: The model showed that human AVH mineralization can be best observed in a solution with a CaxPO4 ionic product of 2.2 mmol2/l2. The optimum incubation time for observing AVH mineralization was 21 days. CONCLUSION: A novel in-vitro AVH mineralization model was developed for use in future studies.

Influence of static and alternating magnetic fields on U937 cell viability.

Presented studies were conducted to assess the influence of alternating (AC) and/or static (DC) magnetic fields (MF) or combined with puromycin (PMC) on U937 cell line viability. The magnitude of DC MF was enclosed in the range (2 ÷ 6) mT. In case of AC MF, four frequencies were set: 12 Hz, 25 Hz, 35 Hz, 50 Hz and magnetic induction value was adjusted to 6.5(rms) mT. The reaction of samples exposed to MF and/or PMC was presented as cell viability coefficient S defined as a ratio of viable cells in the sample to viable cells in the relevant control sample, analyzed by flow cytometry. For PMC treated sample the percentage of viable cells decreased about factor 3. MF alone did not influence cell viability regardless of the type of exposure while simultaneous action of ACDC MF mode and PMC significantly influenced viability of U937 cells. The viability coefficient S was in the range of (0.13 ∓ 0.07 ÷ 0.64 ∓ 0.20) and exerted a non-linear relation with frequency of the AC MF component. The maximal lethal influence (S = 0.13 ∓ 0.07) was observed for DC MF = 6 mT and frequency of AC MF equal to 35 Hz. Observed bio-effects were confronted with the physical models assuming the Ca2+ ions transport disturbance and/or protein complexes dysfunction in cells due to MF action.

Combining areal DXA bone mineral density and vertebrae postero-anterior width improves the prediction of vertebral strength.

OBJECTIVE: Areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry (DXA) is an important determinant of bone strength (BS), despite the fact that the correlation between aBMD and BS is relatively weak. Parameters that describe BS more accurately are desired. The aim of this study was to determine whether the geometrical corrections applied to aBMD would improve its ability for BS prediction. We considered new parameters, estimated from a single DXA measurement, as well as BMAD (bone mineral apparent density) reported in the literature. MATERIALS AND METHODS: In vitro studies were performed with the L3 vertebrae from 20 cadavers, which were studied with DXA and quantitative computed tomography (QCT). A mechanical strength assessment was carried out. Two new parameters were introduced: vBMD(min) = aBMD/W(PA)(min) and vBMD(av) = aBMD/W(PA)(av) (W PA(min) -minimal vertebral body width in postero-anterior (PA) view, W(PA)(av) - average PA vertebral body width). Volumetric BMD measured by QCT (vBMD), aBMD, BMAD, vBMD(min), and vBMD(av) were correlated to ultimate load and ultimate stress (P(max)) to find the best predictor of vertebrae BS. RESULTS: The coefficients of correlation between P(max) and vBMD(min), vBMD(av), as well as BMAD, were r = 0.626 (p = 0.005), r = 0.610 (p = 0.006) and r = 0.567 (p = 0.012), respectively. Coefficients for vBMD and aBMD are r = 0.648 (p = 0.003) and r = 0.511 (p = 0.03), respectively. CONCLUSIONS: Our results showed that aBMD normalized by vertebrae dimensions describes vertebrae BS better than aBMD alone. The considered indices vBMD(av), vBMD(min), and BMAD can be measured in routine PA DXA and considerably improve BS variability prediction. vBMD(min) is superior compared to vBMD(av) and BMAD.

Application of geometrical measurements in the assessment of vertebral strength.

BACKGROUND: The study was aimed at the development of parameters that could be used as predictors of vertebral strength. Proposed parameters describing vertebral geometry and/or shape can be established on the basis of routine spine roentgenograms, making roentgenography a novel tool for vertebral fracture risk assessment in the future. MATERIAL/METHODS: 20 human cadaveric L3 vertebrae were included in the study. Dual-energy X-ray absorptiometry (DXA) was used for an assessment of bone mineral density (BMD). Quantitative computed tomography (QCT) was performed to measure the volumetric bone density as the most reliable parameter in vertebral fracture risk assessment. Geometrical measurements were performed on the basis of high quality and high resolution computer tomography 3-dimensional images. Biomechanical tests were performed to measure vertebral strength. Two parameters were defined on the basis of extensive research: the ratio between vertebral base area and its height (A/H), and the ratio of vertebral coronal width to coronal height (W/H). Correlations between vertebral mechanical strength - its BMD, QCT density, A/H and W/H were calculated. RESULTS: The best correlation to bone durability was achieved for QCT density (r=0.882), while correlation strength for BMD (r=0.779) and A/H (r=-0.773) were comparable. W/H correlated better than BMD to mechanical strength (-0.788). CONCLUSIONS: Geometrical parameters of vertebrae potentially measured on spine radiograms could be used as predictors of vertebral durability. The calculated correlation coefficients suggest that one of the proposed parameters works better than the commonly used BMD.

Chemical composition and morphology of renal stones.

Two issues related to nephrolithiasis are explored: (1) does the chemical composition and morphology of renal calculi in South Poland overlap with the studies from other countries? and (2) are there possibilities to evaluate in vivo chemical composition of stones using computed tomography? The study was conducted on 108 renal stones. X-ray fluorescence, X-ray diffraction and Fourier transformed infrared spectroscopy were used to determine the chemical composition. The morphology of the stones was examined using micro computed tomography. The stone chemical composition in South Poland indicate that calcium oxalate monohydrate was overwhelmingly dominant (84%) followed by hydroxyapatite (8%) and struvite (6%). The occurrence of uric acid stones was very low (2%). The relative frequency of various stone types is similar in South Poland to other industrialized countries. The studied renal stones were characterized by a large variability in the concentrations of both major and trace elements. The maximum/minimum concentration ratio exceeds two orders of magnitude. Significant morphological differences have been observed between different types of stones. The stones were composed of oxalate polyhedrons stuck together or had the phosphate core overlaid with layers oxalate and organic mater. The use of CT to identify stone type seems to be limited.

Oversampling in the computed tomography measurements applied for bone structure studies as a method of spatial resolution improvement.

BACKGROUND: Our purpose was to check the potential ability of oversampling as a method for computed tomography axial resolution improvement. The method of achieving isotropic and fine resolution, when the scanning system is characterized by anisotropic resolutions is proposed. In case of typical clinical system the axial resolution is much lower than the planar one. The idea relies on the scanning with a wide overlapping layers and subsequent resolution recovery on the level of scanning step. MATERIAL/METHODS: Simulated three-dimensional images, as well as the real microtomographic images of rat femoral bone were used in proposed solution tests. Original high resolution images were virtually scanned with a wide beam and a small step in order to simulate the real measurements. The low resolution image series were subsequently processed in order to back to the original fine one. Original, virtually scanned and recovered images resolutions were compared with the use of modulation transfer function (MTF). RESULTS/CONCLUSIONS: A good ability of oversampling as a method for the resolution recovery was showed. It was confirmed by comparing the resolving powers after and before resolution recovery. The MTF analysis showed resolution improvement. The resolution improvement was achieved but the image noise raised considerably, which is clearly visible on image histograms. Despite this disadvantage the proposed method can be successfully used in practice, especially in the trabecular bone studies because of high contrast between trabeculae and intertrabecular spaces.

Application of thermography for the assessment of allergen-induced skin reactions.

PURPOSE: The allergic response is commonly identified and assessed by skin testing. The usual method to quantify skin reactions is to mark wheal and erythema regions and assess the surfaces affected by the reactions; however, subjective interpretation of the outcome may cause errors. Skin thermography supplemented by a mathematical model based on the pathophysiology of heat generation was evaluated as a novel, objective, and sensitive indicator of the skin prick test result. METHODS: TH measurements were performed simultaneously with routine skin prick tests for 24 patients. Eight allergens and control (histamine) were examined. Thermographic images of both forearms were acquired every 70 s from 0 to 910 s after skin prick and analyzed with the use of dedicated software. The introduction of potential allergens and histamine at sites on the skin induces a complex sequence of events known as the local inflammatory response. The crucial steps of the process have been considered in the model. In the model, the authors assumed that the reaction takes place in the thin skin layer and that histamine is the principal mediator of the allergic reaction. Histamine penetrates the skin and binds to receptors of nearby capillaries and venules. The engorged vessels are, in turn, responsible for skin redness and an increase in skin temperature. RESULTS: The model parameters were determined by fitting the analytical solutions to the spatiotemporal distributions of the differences between measured and baseline temperatures. The model reproduces experimental data very well. The coefficient of determination ranged from 0.805 to 0.995. Seven model parameters were tested to find the optimal marker of the intensity and kinetics of the allergic reaction. The parameter which quantifies a release of histamine after allergen injection has appeared to be the best indicator of the allergen-induced response. The parameter correlates with the routine assessment based on wheal and erythema areas (correlation coefficient = 0.98). CONCLUSIONS: It was demonstrated that the thermographic measurements supplemented by the mathematical model offer a new approach to the quantification of allergen-induced skin reactions. Despite the applied simplifications, the proposed model reflected properly the mechanism of heat generation during skin prick test. Moreover, the continuous recording of the skin temperature represents an additional possibility to investigate the mechanism of the allergic reaction.

The elemental composition of renal and ureteral stones determined with the energy dispersive X-ray fluorescence method (ED-XRF).

Many theories describe the lithogenesis within urinary tract. In addition, trace amounts of some heavy metals have been found in urinary calculi. However, their role in lithogenesis is still debated. Trace and heavy metals may be involved in induction of crystallization, depending on the relationships between metals and solutes able to crystallize in urine. Many papers have evaluated the elemental concentration of kidney stones, however there are still less data concerning the elemental composition of kidney and ureteral stones.

Fresh-wet storage accelerates aortic homograft calcification.

The studies were focused on the influence of the fresh-wet storage procedure on aortic valve homograft (AVH) mineralization. Thirty-four aortic valves excised at autopsy were investigated. The cusps were divided into halves, the first one was used as a control while the second half was stored in Morgan, Morton, and Parker's Medium 199 supplemented with an antibiotic mixture at 4 degrees C for 28 days. The elemental compositions of the samples were determined by the energy dispersive X-ray fluorescence method. The Ca/P ratio and Ca concentration was used as markers of the mineralization development. It was found that the AVH mineralization was accelerated by the applied fresh-wet storage procedure. The aggravation of the AVH mineralization was correlated with the Ca content before storage especially in case of old donors. For donors older than 40 years an increase of Ca concentrations by approximately 40% was observed. To limit AVH mineralization due to fresh-wet storage, age of donors should not exceed approximately 40 years. Another method to reduce AVH mineralization relies on a modification of the medium commonly applied in the fresh-wet storage procedure, and research are ongoing.