Dielectric properties of the non-glycated and in vitro methylglyoxal-glycated cornea of the rabbit eye.

The dielectric properties of the non-glycated and in vitro methylglyoxal-glycated cornea of the rabbit eye were tested in the frequency range of 200 Hz to 100 kHz of the electric field and at temperatures of 25 to 140 °C. The denaturation temperature (Td) for the non-glycated cornea and the non-enzymatically glycated cornea are approximately 45 and 55 °C, respectively. The mechanism of proton conduction up to Td in a glycated cornea requires more energy, i.e. more than twice the activation energy (ΔH) than in non-glycated tissue. The dielectric spectra for both examined tissues showed the same characteristic frequency of about 7 kHz assigned to the orientation relaxation time of the polar side groups inside the corneal stroma. These results may be useful in the surgical treatment of the cornea using conductive keratoplasty and in tissue engineering for clinical applications to regenerate this tissue. The medical use of these physico-biological techniques is important because the human cornea protects all eye tissues from various environmental factors.

Dielectric response to thermal denaturation of lenses in healthy and diabetic rabbits.

The relative permittivity and conductivity of healthy and alloxane-induced diabetic rabbits lenses were measured over a frequency range of 500 Hz to 100 kHz in an electric field and at temperatures from 25 to 150 °C. The dielectric spectra for both tissues showed two separate relaxations with a characteristic frequency of around 4 and 25 kHz assigned to the cortical and nuclear zones, respectively. These two dispersions are due to the interfacial polarization at the surface of the α-crystallin molecules. The denaturation temperature for the non-diabetic lens and the diabetic lens is approximately 70 and 80 °C, respectively. Moreover, the relative permittivity and conductivity values are higher in the diabetic lens than in the non-diabetic tissue at the same temperature and frequency. Our dielectric studies provide a better understanding of the thermal stability of crystallin-water complexes in normal and diseased human lenses.

Dielectric properties of healthy and diabetic alloxan-induced lenses in rabbits.

The dielectric properties of the eye lens were studied for healthy and alloxane-induced diabetic rabbits in the frequency range from 500 Hz to 100 kHz electric field and temperatures from 25 to 50 °C. In the full temperature range, the average relative permittivity and dielectric loss values for a healthy lens are lower than those recorded for diabetic tissue. Dielectric relaxation of polar amino acids on the alpha-crystallin surface with a characteristic frequency of 7 kHz in the range of 25-50 °C for healthy and diabetic samples is accompanied by the activation energy of proton conductivity with an average values of 33 and 39 kJ mol-1, respectively. The permittivity decrement, which characterizes the size of the dielectric dispersion with a central relaxation time of 0.023 ms for a diabetic sample, is more than twice as high as for a healthy sample. Measurements on the rabbit eye lens were carried out at ambient temperature above and below the physiological range, since these conditions provide an appropriate pattern of dielectric behavior for the diagnosis of clinical dysfunction of the human lens.

Micronuclei frequency in peripheral blood lymphocytes and levels of anti-p53 autoantibodies in serum of residents of Kowary city regions (Poland) with elevated indoor concentrations of radon.

INTRODUCTION: Ninety four residents of Kowary city (Poland) have been investigated for environmental radon exposure that ranged from 0.24 WLM to 9.6 WLM (activity concentration range: 35-2700 Bq/m3). Kowary was chosen because of uranium mineralisation in its close vicinity. METHOD: Whole population studied was divided into two groups: exposed to low radon activity concentrations resulting in the exposure of ≤0.55 WLM (value corresponding to the exposure to 100 Bq/m3 during whole year), and exposed to high radon activity concentration (>0.55 WLM). In the two groups two selected biomarkers in blood were assessed: the cytokinesis-block micronucleus assay (CBMN) on peripheral blood lymphocytes (PBL), and the levels of anti-p53 antibodies in serum measured because some data indicate increased expression of the antibodies in individuals after exposure to DNA damaging agents including radon. The potential confounding factors known to influence micronuclei (MN) frequency were also measured in serum: vitamin B12, folic acid, as well as total calcium. RESULTS: In the present study no significant correlation was found between MN frequency in PBL and radon exposure. Among all persons investigated only 11 had detectable levels of the anti-p53 antibodies, whereas only 3 persons had positive result. Therefore, the group was too small to perform any meaningful statistical analysis and to conclude on any association. Cigarette smoking did not significantly influence the number of MN. There was a significant positive correlation observed between MN frequency and age, as well as higher MN frequency was detected in women. CONCLUSION: The problem of the radon exposure is still unresolved and needs further studies on bigger human cohorts in order to search for more sensitive biomarkers.

Is eye lens dosimetry needed in nuclear medicine?

INTRODUCTION: The exact level of exposure experienced by nuclear medicine personnel, whose work often requires performing manual procedures involving radioactive isotopes, is associated with the form of radiation source used. The variety of radionuclides and medical procedures, and the yearly increase in the number of patients, as well as the change of the individual dose limit for the lens of the eye from a value of 150 mSv yr-1 to 20 mSv yr-1, mean that issues of eye lens routine dosimetry become interesting from the radiation protection point of view. OBJECTIVE: This paper presents an analysis of the exposure of the eye lenses of nuclear medicine department personnel, as well as those of personnel in the facilities that produce radiopharmaceuticals for the purpose of diagnosis by positron emission tomography, from the viewpoint of the advisability of routine eye lens exposure monitoring, taking into account changes in the dose limit for the lens of the eye. MATERIALS AND METHODS: The paper considers the two most commonly used radionuclides for diagnostic purposes 99mTc, 18F, and-for therapeutic purposes-131I. Dose measurements were made using thermoluminescent detectors. RESULTS: The estimated exposure analysis identifies the cases when the maximum annual value of the personal dose equivalent, in terms of Hp(3), exceeds threefold the new limit value (20 mSv yr-1). CONCLUSIONS: It is recommended that Hp(3) doses be routinely monitored in the group of radiopharmacists who label pharmaceuticals with the radionuclide 99mTc and in chemists working in 18F-FDG quality control departments in production units, where this is carried out manually.

Dielectric study of interaction of water with normal and osteoarthritis femoral condyle cartilage.

The main goal of this paper is the in vitro study of healthy and osteoarthritis (OA) human cartilage using the dielectric spectroscopy in the alpha-dispersion region of the electric field and in the temperatures from 25 to 140°C. The activation energy of conductivity needed to break the bonds formed by water in the extracellular matrix takes the average values of 61kJ/mol and 44kJ/mol for the control and OA cartilages, respectively. At 28°C, the small difference appears in the permittivity decrement between the control and OA cartilages, while the conductivity increment is about 2 times higher for the control tissue than that for the OA tissue. At 75°C, the conductivity increment for both of these samples is 8 times higher than their respective permittivity decrement. In addition, at 140°C the values of these both parameters for the OA tissue decrease by 8 times as compared to those recorded for the control sample. The relaxation frequency of about 10kHz is similar for both of these samples. The knowledge on dielectric properties of healthy and OA cartilage may prove relevant to tissue engineering focused on the repair of cartilage lesions via the layered structure designing.

Dielectric relaxation of normothermic and hypothermic rat corneas.

This paper aims at the presentation of the results of in vitro research on the dielectric properties of the cornea specimen collected from the rats subjected to in vivo hypothermia. The average values of the relative permittivity and dielectric loss are about 40% higher for the hypothermic cornea than those for the normothermic tissue at the same water content of 12% for both samples and at 25°C. Whereas, at 50°C this effect of increase in the dielectric properties of the hypothermic cornea when compared to the normothermic one is observed clearly only in the relative permittivity of about 19%. In the temperature range of 25-50°C, the activation energy of conductivity associated with the release of loosely bound water takes the average values of 45kJ/mol and 30kJ/mol for the normothermic and hypothermic corneas, respectively. The study provided information on dielectric polarization and conductance mechanisms in the cornea which may be helpful in interpreting clinical results of human cornea examination, currently obtained by means of such electrodiagnostic methods as conductive keratoplasty, electroretinography or electrooculography.

Higher-order rocking filters induced mechanically in fibers with different birefringence dispersion.

We studied the transmission characteristics of higher-order rocking filters induced mechanically in birefringent microstructured fibers and standard elliptical core fibers with varying spectral dependence of phase modal birefringence. We demonstrated the effect of birefringence dispersion on polarization mode coupling induced by a point-like force. We also investigated the spectral dependence of the resonance depth and force-induced resonance wavelength shift in mechanical rocking filters. The observed phenomena were explained by a numerical model linking the spectral dependence of the polarization mode coupling coefficient with the dispersion of intrinsic fiber birefringence and applied force.

Dielectric phenomena associated with the keratin-glucose interactions of nail plate.

In this study, we analyzed the effect of water and frequency on the dielectric properties of the nail plate in healthy individuals and in diabetic patients. The temperature dependencies of the loss tangent for both healthy and diabetic nail represent the relation between the electrical energy lost and stored in keratin-glucose-water complexes of this tissue. The differences between these materials concern the temperature ranges in which there appears the decomposition of loosely bound water. The effect of glycation on the loss tangent of the wet and the dry nail is supported by higher values of this parameter than in those describing the healthy samples in the whole temperature range and above 100°C, respectively. In addition, glycation lead to distinct increase in the dielectric relaxation decrement in permittivity and dielectric loss between the frequency of 500 Hz and 100 kHz for the wet and the dry nail. The results of this study indicate that the dielectric spectroscopy may be useful in observing the decomposition of water in the diabetic nail plate.

Dielectric properties of hypothermic rat artery.

The temperature and frequency dependencies of the dielectric parameters for the rat artery are used to analyse effects of hypothermia on this tissue. Measurements were performed over the frequency range 500 Hz to 100 kHz and at temperatures from 19 to 60°C. The artery samples contained about 12% water by mass at room temperature at a relative humidity of 70%. The frequency dependencies of the loss tangent for the control, mild hypothermic and moderate hypothermic artery exhibit two peaks at 2 kHz and 35 kHz in the α-dispersion region. The results were discussed in terms of the distribution of relaxation frequencies and the activation energy for the conduction and polarization mechanisms particularly in the elastin-water and collagen-water systems. The knowledge about dielectric behavior of the hypothermic rat artery in vitro is important due to clinical application of local and systemic hypothermia.

Sensing characteristics of the rocking filters in microstructured fibers optimized for hydrostatic pressure measurements.

We report on the sensing characteristics of rocking filters fabricated in two microstructured fibers with enhanced polarimetric sensitivity to hydrostatic pressure. The filter fabricated in the first fiber shows a very high sensitivity to pressure ranging from 16.2 to 43.4 nm/MPa, depending on the resonance order and features an extremely low cross-sensitivity between pressure and temperature 28 ÷ 89 × 10(3) K/MPa. The filter fabricated in the second fiber has an extreme sensitivity to pressure ranging from -72.6 to -177 nm/MPa, but a less favorable cross-sensitivity between pressure and temperature of 1.05 ÷ 3.50 × 10(3) K/MPa. These characteristics allow using the rocking filters for pressure measurements with mbar resolution.

Implications of the alpha dispersion for studies on interaction of tobacco smoke--corneal tissue.

In this work, we have carried out a dielectric study to determine the effect of tobacco smoke on the rat corneal function. Measurements were performed over the frequency range of 500 Hz-100 kHz in air and at the temperature of 35°C. The frequency dependencies of the loss tangent for both healthy and smoky cornea exhibit two peaks with different width occurring as a narrow at 2 kHz and a broad at around 16 kHz. The distribution parameter α at 2 kHz has a value of about 0.3, which increases to 0.6 at 16 kHz. The magnitude of the permittivity decrement at 2 and 16 kHz is about two and four times higher, respectively, for the smoky cornea than that for the healthy one. These dielectric studies indicate that the present method is useful in detection of the effect of tobacco smoke exposure on the corneal behavior.

Diabetes mellitus effect on rat corneal dielectric properties.

In the course of the study, we carried out a dielectric examination to determine the effect of diabetes mellitus on the rat corneal function. Measurements were performed over the frequency range of 500 Hz-100 kHz in air and at the temperatures from 25 to 150°C. The frequency dependencies of the loss tangent for the healthy and the diabetic cornea exhibit two peaks at 2 kHz and 16 kHz in the α-dispersion region. The amplitude of these both peaks is smaller for the diabetic cornea than that for the healthy one. The temperature dependencies of the loss tangent for the healthy and the diabetic cornea reveal ß-relaxation in the range of 30-70°C and 50-90°C, respectively. The present study exhibits that the dielectric spectroscopy is useful in detection of the effect of diabetes mellitus on the corneal molecular behavior.

Hand exposure of nuclear medicine workers during administration of radioiodine.

(131)I has been widely used in nuclear medicine for many years, particularly in the form of iodide for the diagnosis and therapy of thyroid cancer and other thyroid diseases. Manual dispensing of radioiodine-based radiopharmaceuticals results in potentially significant radiation doses to the hands of nuclear medicine personnel performing this task. This article reports the results of thermoluminescent dosemeter-based measurement of radiation doses at various points on the hands of personnel dispensing radioiodine radiopharmaceuticals.

Impaired nucleotide excision repair pathway as a possible factor in pathogenesis of head and neck cancer.

Tobacco smoking is one of the major risk factors in pathogenesis of head and neck squamous cell carcinomas (HNSCC). Many of the chemical compounds present in tobacco are well-known carcinogens which form adducts with DNA. Cells remove these adducts mainly by the nucleotide excision repair pathway (NER). NER also eliminates a broad spectrum of pyrimidine dimers (CPD) and photo-products (6-4PP) induced by UV-radiation or DNA cross-links after cisplatin anti-cancer treatment. In this study DNA damage and repair was examined in peripheral blood lymphocytes obtained from 20 HNSCC patients and 20 healthy controls as well as HTB-43 larynx and SSC-25 tongue cancer cell lines. DNA repair kinetics in the examined cells after cisplatin or UV-radiation treatment were investigated using alkaline comet assay during 240min of post-treatment incubation. MTT assay was used to analyse cell viability and the Annexin V-FITC kit specific for kinase-3 was employed to determine apoptosis after treating the cells with UV-radiation at dose range from 0.5 to 60J/m(2). NER capability was assessed in vitro with cell extracts by the use of a bacterial plasmid irradiated with UV-light as a substrate for the repair. The results show that lymphocytes from HNSCC patients and HTB-43 or SSC-25 cancer cells were more sensitive to genotoxic treatment with UV-radiation and displayed impaired DNA repair. Also evidenced was a higher rate of apoptosis induction after UV-radiation treatment of lymphocytes from the HNSCC patients and the HTB-43 cancer cells than after treatment of those from healthy donors. Finally, our results showed that there was a significant decrease in NER capacity in HTB-43 or SSC-25 cancer cells as well as in peripheral blood lymphocytes of HNSCC patients compared to controls. In conclusion, we suggest that the impaired NER pathway might be a critical factor in pathogenesis of head and neck cancer.

Intermodal interferometer for strain and temperature sensing fabricated in birefringent boron doped microstructured fiber.

We present a compact in-line fiber interferometric sensor fabricated in a boron doped two-mode highly birefringent microstructured fiber using a CO(2) laser. The intermodal interference arises at the fiber output due to coupling between the fundamental and the first order modes occurring at two fiber tapers distant by a few millimeters. The visibility of intermodal interference fringes is modulated by a polarimetric differential signal and varies in response to measurand changes. The proposed interferometer was tested for measurements of the strain and temperature, respectively, in the range of 20-700 °C and 0-17 mstrain. The sensitivity coefficients corresponding to fringe displacement and contrast variations are equal respectively for strain -2.51 nm/mstrain and -0.0256 1/mstrain and for temperature 16.7 pm/°C and 5.74×10(-5) 1/°C. This allows for simultaneous measurements of the two parameters by interrogation of the visibility and the displacement of interference fringes.

Correction factors for determination of annual average radon concentration in dwellings of Poland resulting from seasonal variability of indoor radon.

The method for the calculation of correction factors is presented, which can be used for the assessment of the mean annual radon concentration on the basis of 1-month or 3-month indoor measurements. Annual radon concentration is an essential value for the determination of the annual dose due to radon inhalation. The measurements have been carried out in 132 houses in Poland over a period of one year. The passive method of track detectors with CR-39 foil was applied. Four thermal-precipitation regions in Poland were established and correction factors were calculated for each region, separately for houses with and without basements.

Polymorphisms of the DNA repair genes XRCC1 and ERCC4 are not associated with smoking- and drinking-dependent larynx cancer in a Polish population.

BACKGROUND: Tobacco smoking and alcohol drinking generate oxidative DNA damage and may contribute to larynx carcinogenesis. The X-ray repair cross complementing 1 (XRCC1) and excision repair cross-complementing rodent repair deficiency, complementation group 4 (ERCC4(XPF)) genes are important components of DNA excision repair systems, which repair DNA damage induced by various factors, including tobacco smoking and alcohol. AIM: To investigate the association between the genotypes of the XRCC1-Arg399Gln (rs25487) and ERCC4-Arg415Gln (rs1800067) polymorphisms and smoking- and drinking-related larynx cancer in a Polish population. METHODS: The polymorphisms were determined by PCR-RFLP method in 253 patients with squamous cell carcinoma of the larynx and 253 sex- and age-matched controls. RESULTS: We did not find any association between the investigated polymorphisms and larynx carcinoma, dependent on either smoking or drinking status. No association was found between these polymorphisms and larynx cancer grade, stage or age at diagnosis. CONCLUSIONS: The results indicated that Arg399Gln polymorphism of XRCC1 gene and Arg415Gln polymorphism of ERCC4 gene may not be associated with smoking- and drinking-related larynx cancer in Polish population.

Dielectric studies of the paracetamol-lenticular tissue interactions.

This paper reports on the effect of paracetamol on the dielectric behavior of the rabbit lens. Measurements were performed over the frequency range of 100 Hz-100 kHz in air and at the temperature of 35°C. The frequency dependencies of the relative permittivity and dielectric loss for the control and paracetamol-control lenses are described in terms of a power-low, Debye and Cole-Cole relations. The effect of paracetamol on the dielectric properties of the lens is visible in the lower values of the relative permittivity than those for the control sample at the same frequency. In addition, the relaxations around 18 and 46 kHz for the paracetamol-control lens are shifted to lower frequencies compared with the control lens. The results of this work indicate that the present method is useful in detection of the lens toxicity elicited by overdoses of paracetamol in animal.

Supplementation with L-arginine does not influence arterial blood pressure in healthy people: a randomized, double blind, trial.

BACKGROUND AND OBJECTIVES: It cannot be excluded that supplementation with L-arginine, by improving function of endothelium and hypotensive effect, can be advantegeous in prevention of cardiovascular diseases in healthy people. However, reports about hypotensive effect of L-arginine in healthy people are unclear. Moreover, no research including ambulatory blood pressure measurement (ABPM) has been conducted so far. Therefore, the aim of our study was to show if 4-week supplementation of healthy people with L-arginine influences blood pressure measured with ABPM. MATERIALS AND METHODS: The study was carried out on 19 healthy people randomized to 6 g/24-hour, 12 g/24-hours of L-arginine or placebo. ABPM was carried out 4 times: before randomization, after 2 and 4 weeks of supplementation and 2 weeks after finishing supplementation. RESULTS: It was found that 4 weeks of supplementation of healthy people with L-arginine (6 or 12 g/24-hour) led to nonsignificant decrease of systolic and diastolic blood pressure; the decrease was greater during night. CONCLUSION: These findings showed that supplementation with L-arginine is not necessarily advantageous in healthy people.