Tissue response of radiation therapy assessed by electrical impedance spectroscopy (EIS) in subcutaneous tumours in rats.

The present investigation aims to evaluate the possibility of using bio-impedance spectrometry to measure tumour and tissue response to radiation therapy. Bio -impedance measurements performed with CythorLab™ equipped with a signal generator with a known high output impedance and signal measuring device able to measure the voltage applied by the generator. The control unit triggers the signal generator that generates an MLS-sequence. The same control unit process the signal that simultaneously measured by the voltage-recording device. An FFT analysis performed to obtain the magnitude of the real and imaginary parts of the impedance spectrum. The effect of various numbers of fractions of radiation therapy (RT) on the impedance measured with surface plate electrodes investigated in male rats of the Fischer-344 strain with rat glioma N32 tumours implanted subcutaneously on the flank. Tumours produced by injecting 100 000 N32 tumour cells just below the skin. Tumours were treated about four weeks after injection when a solid tumour has developed with a diameter of 1-1.5 cm. Before treating the tumours, animals anaesthetised, and the fur over the tumour shaven and carefully to ensure good electrical contact between electrodes and skin. The electrical impedance dispersion of tissue modelled with an RC-equivalent circuit from which collective impedance parameters corresponding the cell membranes, Rm Cm intra -cellular resistance, Ri, and extra-cellular resistance R0.Impedance measurements performed over a tumour before irradiation to 5 Gy and every minute after the irradiation up to 8 minutes. A slight increase of impedance, and with a time constant of 10 minutes. The growth might be due to dry skin after irradiation or a decrease of tumour vascularity during the treatment. The capacitance of the cell membrane related to the characteristic frequency fc does not change significantly before and after radiation exposure. A special parameter, the "Loss Change Index" (LCI) which defined to vary between zero if there is no change in the phase angle and one if the phase angle after exposure approach zero. LCI reach an extreme at the characteristic frequency. The LCI value recorded at the characteristic frequency fc varied with the accumulated absorbed dose and fitted to a sigmoidal dose/response relationship

Nerve cell damage in mammalian brain after exposure to microwaves from GSM mobile phones.

The possible risks of radio-frequency electromagnetic fields for the human body is a growing concern for our society. We have previously shown that weak pulsed microwaves give rise to a significant leakage of albumin through the blood-brain barrier. In this study we investigated whether a pathologic leakage across the blood-brain barrier might be combined with damage to the neurons. Three groups each of eight rats were exposed for 2 hr to Global System for Mobile Communications (GSM) mobile phone electromagnetic fields of different strengths. We found highly significant (p< 0.002) evidence for neuronal damage in the cortex, hippocampus, and basal ganglia in the brains of exposed rats

Proton Microprobe and Particle Induced X-Ray Emission (PIXE) Analysis for Studies of Pathological Brain Tissue

Particle Indiced X-ray Emission and proton microprobe analyses have been applied for the investigation of regional elemental distributions in connection with various pathological states in the brain. Malignant brain tumours and adjacent histologically intact tissue removed during surgery were analysed with PIXE. Systematic elemental variations, e.g., for calcium and selenium, were observed in the tumour front. The proton microprobe was applied to study the Ca and K concentrations in various cell strata in hippocampus following transient ischaemia in rat brain. Significant increases in the Ca level occurred in selectively vulnerable cells within 48 h after the ischaemia

Adaptive regression modeling of biomarkers of potential harm in a population of U.S. adult cigarette smokers and nonsmokers

<p>Abstract</p> <p>Background</p> <p>This article describes the data mining analysis of a clinical exposure study of 3585 adult smokers and 1077 nonsmokers. The analysis focused on developing models for four biomarkers of potential harm (BOPH): white blood cell count (WBC), 24 h urine 8-epi-prostaglandin F_2α(EPI8), 24 h urine 11-dehydro-thromboxane B₂(DEH11), and high-density lipoprotein cholesterol (HDL).</p> <p>Methods</p> <p>Random Forest was used for initial variable selection and Multivariate Adaptive Regression Spline was used for developing the final statistical models</p> <p>Results</p> <p>The analysis resulted in the generation of models that predict each of the BOPH as function of selected variables from the smokers and nonsmokers. The statistically significant variables in the models were: platelet count, hemoglobin, C-reactive protein, triglycerides, race and biomarkers of exposure to cigarette smoke for WBC (R-squared = 0.29); creatinine clearance, liver enzymes, weight, vitamin use and biomarkers of exposure for EPI8 (R-squared = 0.41); creatinine clearance, urine creatinine excretion, liver enzymes, use of Non-steroidal antiinflammatory drugs, vitamins and biomarkers of exposure for DEH11 (R-squared = 0.29); and triglycerides, weight, age, sex, alcohol consumption and biomarkers of exposure for HDL (R-squared = 0.39).</p> <p>Conclusions</p> <p>Levels of WBC, EPI8, DEH11 and HDL were statistically associated with biomarkers of exposure to cigarette smoking and demographics and life style factors. All of the predictors togather explain 29%-41% of the variability in the BOPH.</p

‘Perceptions of non-accidental child deaths as preventable events: The impact of probability heuristics and biases on child protection work'

Anxiety about the possibility of non-accidental deaths of children has had a major influence on child care policy and practice over the last 40 years. The formal inquiry reports and media coverage of these rare events serve to maintain the perception that these are regular incidents that happen far too often and that they could have been prevented. This focus on individual events tends to distort a clear view of the actual probability of non-accidental deaths and serves to reinforce the notion that potentially all child care cases are risky and that any social work practitioner could be involved in such a case. As a result, work with children has become highly risk averse. However, in statistical terms, the probability of non-accidental child deaths is very low and recently has averaged about 55 deaths a year. Children are at considerably higher risk of being killed on the roads. This paper examines the way in which perceptions of the ‘high’ level of risk of possible child deaths are maintained despite the very low statistical probability of such incidents. It draws on thinking from behavioural psychology and, in particular the work of Kahneman and Tversky, to consider some of the biases in probability reasoning affecting people’s perception of risk and explores how inquiry reports into single past events reconfirm risk perceptions. It is suggested that recognition of the essentially unpredictable nature of future non-accidental child deaths would free up childcare professionals to work in a more positive and less risk-averse manner in the present

‘Perceptions of non-accidental child deaths as preventable events: The impact of probability heuristics and biases on child protection work'

Anxiety about the possibility of non-accidental deaths of children has had a major influence on child care policy and practice over the last 40 years. The formal inquiry reports and media coverage of these rare events serve to maintain the perception that these are regular incidents that happen far too often and that they could have been prevented. This focus on individual events tends to distort a clear view of the actual probability of non-accidental deaths and serves to reinforce the notion that potentially all child care cases are risky and that any social work practitioner could be involved in such a case. As a result, work with children has become highly risk averse. However, in statistical terms, the probability of non-accidental child deaths is very low and recently has averaged about 55 deaths a year. Children are at considerably higher risk of being killed on the roads. This paper examines the way in which perceptions of the ‘high’ level of risk of possible child deaths are maintained despite the very low statistical probability of such incidents. It draws on thinking from behavioural psychology and, in particular the work of Kahneman and Tversky, to consider some of the biases in probability reasoning affecting people’s perception of risk and explores how inquiry reports into single past events reconfirm risk perceptions. It is suggested that recognition of the essentially unpredictable nature of future non-accidental child deaths would free up childcare professionals to work in a more positive and less risk-averse manner in the present

The risk of subjective symptoms in mobile phone users in Poland – An epidemiological study

Objectives: To assess the type and incidence of subjective symptoms related to the use of mobile phones in Polish users. Material and Methods: The study was conducted in 2005 using a questionnaire survey. Although it has been quite a long time, up to now, no such data have been published for Poland. The questionnaire consisted of 53 questions concerning sex, age, education, general health, characteristics of a mobile phone (hand-held, loud-speaking unit) as well as the habits associated with its use (frequency and duration of calls, text messages, etc.) and complaints associated with using a mobile phone. Results: As many as 1800 questionnaires were sent. The response was obtained from 587 subjects aged 32.6±11.3 (48.9% women, 51.1% men); the age did not differ significantly between men and women. The subjects owned a cell phone for an average of 3 years. Majority of the respondents used the phone intensively, i.e. daily (74%) or almost daily (20%). Headaches were reported significantly more often by the people who talked frequently and long in comparison with other users (63.2% of the subjects, p = 0.0029), just like the symptoms of fatigue (45%, p = 0.013). Also, the feeling of warmth around the ear and directly to the auricle was reported significantly more frequently by the intensive mobile phone users, compared with other mobile phone users (47.3%, p = 0.00004 vs. 44.6%, p = 0.00063, respectively). Most symptoms appeared during or immediately after a call and disappeared within 2 h after the call. Continuous headache, persisting for longer than 6 h since the end of a call, was reported by 26% of the subjects. Conclusions: Our results show that the mobile phone users may experience subjective symptoms, the intensity of which depends on the intensity of use of mobile phones

Mobile phones and head tumours. The discrepancies in cause-effect relationships in the epidemiological studies - how do they arise?

The uncertainty about the relationship between the use of mobile phones (MPs: analogue and digital cellulars, and cordless) and the increase of head tumour risk can be solved by a critical analysis of the methodological elements of both the positive and the negative studies. Results by Hardell indicate a cause/effect relationship: exposures for or latencies from 65 10 years to MPs increase by up to 100% the risk of tumour on the same side of the head preferred for phone use (ipsilateral tumours) - which is the only one significantly irradiated - with statistical significance for brain gliomas, meningiomas and acoustic neuromas. On the contrary, studies published under the Interphone project and others produced negative results and are characterised by the substantial underestimation of the risk of tumour. However, also in the Interphone studies a clear and statistically significant increase of ipsilateral head tumours (gliomas, neuromas and parotid gland tumours) is quite common in people having used MPs since or for 65 10 years. And also the metaanalyses by Hardell and other Authors, including only the literature data on ipsilateral tumours in people having used MPs since or for 65 10 years - and so also part of the Interphone data - still show statistically significant increases of head tumours