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Biomedical subjects

K H Mild

Publications and source records attributed to K H Mild.

At least 19 recordsLinked to original sources
PubMed2002

Case-control study on the use of cellular and cordless phones and the risk for malignant brain tumours.

PURPOSE: To investigate the use of cellular and cordless phones and the risk for malignant brain tumours. MATERIALS AND METHODS: A case-control study was performed on 649 patients aged 20-80 years of both sexes with malignant brain tumour diagnosed from 1 January 1997 to 30 June 2000. All patients were alive during the time of the study and had histopathology verified brain tumours. One matched control to each case was selected from the Swedish Population Register. The study area was the Uppsala-Orebro, Stockholm, Linköping and Göteborg medical regions of Sweden. RESULTS: Exposure was assessed by a questionnaire answered by 588 (91%) cases and 581 (90%) controls. Phone usage was defined as 'ever use' and usage starting within 1 year before diagnosis was disregarded. Overall, no significantly increased risks were found: analogue cellular phones yielded an odds ratio (OR)=1.13, 95% confidence interval (CI)=0.82-1.57, digital cellular phones OR=1.13, CI=0.86-1.48, and cordless phones OR=1.13, CI=0.85-1.50. For ipsilateral (same side) radiofrequency exposure, analogue mobile phones gave OR=1.85, CI=1.16-2.96, for all malignant brain tumours. For astrocytoma, this risk was OR=1.95, CI=1.12-3.39. For all malignant brain tumours, digital mobile phones yielded OR=1.59, CI=1.05-2.41, and cordless phones yielded OR=1.46, CI=0.96-2.23, in the analysis of ipsilateral exposure. CONCLUSION: The ipsilateral use of an analogue cellular phone yielded a significantly increased risk for malignant brain tumours.

Adult↗
PubMed2001

Chromosomal aberrations in peripheral lymphocytes of train engine drivers.

Studies of Swedish railway employees have indicated that railroad engine drivers have an increased cancer morbidity and incidence of chronic lymphatic leukemia. The drivers are exposed to relatively high magnetic fields (MF), ranging from a few to over a hundred microT. Although the possible genotoxic potential of MF is unclear, some earlier studies have indicated that occupational exposure to MF may increase chromosome aberrations in blood lymphocytes. Since an increased level of chromosomal aberrations has been suggested to predict elevated cancer risk, we performed a cytogenetic analysis on cultured (48 h) peripheral lymphocytes of Swedish train engine drivers. A pilot study of 18 engine drivers indicated a significant difference in the frequency of cells with chromosomal aberrations (gaps included or excluded) in comparison with seven concurrent referents (train dispatchers) and a control group of 16 office workers. The engine drivers had about four times higher frequency of cells with chromosome-type aberrations (excluding gaps) than the office workers (P < 0.01) and the dispatchers (P < 0.05). Seventy-eight percent of the engine drivers showed at least one cell per 100 with chromosome-type aberrations compared with 29% among the dispatchers and 31% among the office workers. In a follow-up study, another 30 engine drivers showed an increase (P < 0.05) in the frequency of cells with chromosome-type aberrations (gaps excluded) as compared with 30 referent policemen. Sixty percent of the engine drivers had one or more cells (per 100 cells) with chromosome-type aberrations compared with 30% among the policemen. In conclusion, the results of the two studies support the hypothesis that exposure to MF at mean intensities of 2-15 microT can induce chromosomal damage.

Adult↗
PubMed2001

Induced current measurements in whole body exposure condition to radio frequency electric fields.

The current induced in a human exposed to radio frequency electric fields has been studied by the use of a stripline, in which whole body exposure to vertical electric fields (3-27 MHz) can be produced. We have examined two different techniques to measure the induced current; parallel plate meters and current probes. When the subject has good connection to the ground, the choice of measurement technique is not crucial, since there are only minor differences in readings between the instruments. But when the subject is wearing shoes and/or standing on a wooden plate, the difference between the instruments increases considerably. The difference can mainly be explained by the capacitive coupling between the parallel plate meters and the ground; therefore, the current probes are preferred when the subject does not have perfect contact with the ground. Since the International Commission on Non-Ionizing Radiation Protection guidelines demand measurements of induced current in humans exposed to radio frequency fields in the range of 10-110 MHz, the importance of finding an appropriate measurement procedure becomes apparent.

Biophysics↗
PubMed2001

[Ca2+](i) rise in Jurkat E6-1 cell lines from different sources as a response to 50 Hz magnetic field exposure as a reproducible effect and independent of poly-L-lysine treatment.

Jurkat E6-1 cells obtained from three different sources were compared with respect to intracellular calcium response to a 50 Hz, 0.15 mT, magnetic field, to treatment with poly-L-lysine and to protein expression at the cell surface. The fura-2 single cell measurements were a replication study performed by three members of our group. The cells responded to the applied magnetic fields, although the percentage of responding cells was lower than in earlier studies. The geomagnetic field was backed off without changing the outcome of the intracellular calcium measurements. Fluorometric analyses showed no difference between the E6-1 cells obtained from three sources with respect to the expression of cell surface marker molecules. The addition of the cell adhesive peptide, poly-L-lysine, did not itself cause any effects on the intracellular calcium concentration.

Antigens, Differentiation, T-Lymphocyte↗
PubMed2001

ELF magnetic fields initiate protein tyrosine phosphorylation of the T cell receptor complex.

The human T cell line Jurkat registers a sinusoidal extremely low frequency (ELF), 0.10 mT magnetic fields (MFs) at the level of the plasma membrane. In this study, the protein tyrosine phosphorylation (PY) of two membrane-associated proteins in Jurkat cells were examined following a short-term MFs exposure, the zeta chains and the Src kinases p56lck. These proteins are interesting to study since the earliest biochemical event upon T cell receptor (TcR) activation is PY of the zeta chains. These signalling chains in the TcR complex was assessed using Western blotting and the activation of the p56lck kinase was analysed by in vitro kinase assay. The MFs exposure of Jurkat for 5 min activated p56lck and resulted in PY of zeta. These findings are in line with earlier reports on how MFs exposure affects signal transduction in Jurkat.

Blotting, Western↗
PubMed2001

Ionizing radiation, cellular telephones and the risk for brain tumours.

A case-control study on brain tumours included 233 patients aged 20-80 years and alive at the study time. They had histopathologically verified brain tumour and lived in the Uppsala-Orebro region (1994-1996) or the Stockholm region (1995-1996). Two matched controls to each case were selected from the Swedish Population Register. Two hundred and nine cases (90%) and 425 controls (91%) answered the questionnaire. Results are presented for the whole study group, as given here, and for malignant and benign tumours separately. For workers in the chemical industry the odds ratio (OR) was 4.10, 95% confidence interval (95% CI) 1.25-13.4 and laboratory workers OR 3.21, 95% CI 1.16-8.85. Radiotherapy of the head and neck region gave OR 3.61, 95% CI 0.65-19.9. Medical diagnostic X-ray of the same area yielded OR 1.64, 95% CI 1.04-2.58. Work as a physician gave OR 6.00, 95% CI 0.62-57.7. All three cases had worked with fluoroscopy. Ipsilateral (same side) use of a cellular telephone increased the risk of tumours in the temporal, temporoparietal and occipital areas, with OR 2.42, 95% CI 0.97-6.05 (i.e. the anatomical areas with highest exposure to microwaves from a mobile phone).

Adult↗
PubMed2001

Provocation study of persons with perceived electrical hypersensitivity and controls using magnetic field exposure and recording of electrophysiological characteristics.

The aim of the present study was to investigate possible neurophysiological effects of intermittent 15 sec on/off cycle, 60 Hz, 10 microT magnetic field exposure on patients with perceived "electromagnetic hypersensitivity" (EHS), and control subjects during rest and performance of a mental arithmetic task. Twenty participants (15 female, 5 male, 31-60 years old, mean 45.8 +/- 0.7 years) were invited from the group of EHS patients. Twenty volunteers (15 female, 5 male, 31-59 years old, mean 45.0 +/- 0.7 years?) served as a control group. The test protocol consisted of a set of examinations: EEG, visual evoked potentials, electrodermal activity, ECG, and blood pressure. The total duration of the test was 40 min, divided into two 10 min rest periods and two 10 min periods of mathematical performance. Magnetic field and sham exposures were presented randomly during these periods, resulting in four different conditions: Field-Rest, Sham-Rest, Field-Math, and Sham-Math. The data showed significant main effects of the Group factor (EHS vs. control subjects) on heart rate (F(1,80) = 20.6; P < 0.01), heart rate spectrum ratio (F(1,80) = 9.5; P = 0.02), and electrodermal activity (F(1,76) = 4.2; P = 0.04), whereas EEG characteristics did not differ between groups. The Condition factor (mathematical task vs. relaxed) showed main effects for heart rate (F(1,80) = 14.8; P < 0.01), heart rate spectrum ratio (F(1,80) = 7.8; P = 0.06), electrodermal activity (F(1,76) = 56.8; P < 0.01), and alpha and theta spectral bands of EEG. Magnetic field exposure did not affect autonomous system or electroencephalographic variables of either group. These data do not indicate that EHS patients or control are affected by low-level 60 Hz magnetic field exposure. However, persons reporting EHS differed from the control subjects in baseline values of investigated physiological characteristics. Perhaps EHS patients have a rather distinctive physiological predisposition to sensitivity to physical and psychosocial environmental stressors.

Adult↗
PubMed2000

Symptoms experienced in connection with mobile phone use.

Many people in Norway and Sweden reported headaches, fatigue, and other symptoms experienced in connection with the use of a mobile phone (MP). Therefore, we initiated a cross-sectional epidemiological study among 17,000 people, all using an MP in their job. Thirty-one percent of the respondents in Norway and 13% of those in Sweden had experienced at least one symptom in connection with MP use. Next to the sensations of warmth on the ear and behind/around the ear, burning sensations in the facial skin and headaches were most commonly reported. Most symptoms usually began during or within half an hour after the call and lasted for up to 2 h. Relatively few had consulted a physician or been on sick leave because of the symptoms, but about 45% among those with an MP attributed symptom had taken steps to reduce the symptom. These results suggest an awareness of the symptoms, but not necessarily a serious health problem.

Acute Disease↗
PubMed1998

Mammary tumours in Sprague-Dawley rats after initiation with DMBA followed by exposure to 50 Hz electromagnetic fields in a promotional scheme.

In order to test whether a transient-producing intermittent magnetic field (MF) acts as a promoter in rat mammary tumour development, a study of a 50 Hz sinusoidal MF with flux densities of 0.25 and 0.5 mT was performed on female Sprague-Dawley rats. A single administration of 7 mg of 7,12-dimethyl-benz[a]anthracene (DMBA) was given by gavage to 52-day-old animals. After 1 week, exposure to an intermittent (15 s on/15 s off) transient-associated magnetic field was started. MF exposure was performed for 19 or 21 h per day up to 25 weeks, when the study was terminated. Twice a week a careful examination with palpation for tumours was done. Tumour incidence, the number of tumours per animal, tumour volume and tumour weight were recorded. A total of 70% of MF-exposed animals developed tumours. For animals exposed to DMBA alone the correspondent figure was 71.7%. No statistical differences were seen either for tumour-bearing animals or for the total number of tumours. A slightly larger total tumour weight and tumour volume was seen for animals exposed to 0.25 mT MF. These differences were not statistically significant.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Steady-state visual evoked potentials to computer monitor flicker.

In the present study, steady-state visual evoked potentials (S-VEP) in response to amplitude-modulated light from a computer monitor (colour sVGA, 15-inch tube) have been examined. S-VEPs to computer monitors with different refresh rates (60 Hz or 72 Hz) and screen brightness (65 cd/m2 or 6 cd/m2) were recorded in 13 subjects with normal or corrected-to-normal vision. EEG samples were amplified, averaged and stored using Cadwell Excel EMG-EP recorder and a regression model was applied for the amplitude analysis. The mean values of S-VEP amplitude at 60 Hz were found to be significantly higher at 60 Hz refresh rate vs. 72 Hz (F1,12 = 14.1; P = 0.003). Effect of screen brightness (F2,24 = 6.5; e = 0.62; P = 0.00075) as well as the interaction effect of refresh rate and screen brightness (F2,24 = 11.6; P = 0.0003) were also found to be significant. Data obtained show that the characteristics of amplitude-modulated light from a computer monitor (frequency, brightness, waveform) are sufficient to elicit S-VEP, and the influence is not only restricted to the peripheral divisions of the visual system as it was shown earlier, but also extends to the central brain structures.

Adult↗
PubMed1997

The psychosocial work environment and skin symptoms among visual display terminal workers: a case referent study.

BACKGROUND: This study is a part of the interdisciplinary project The Office Illness Project in Northern Sweden, which was initiated with a questionnaire study in late 1988. Previously published results from the project have shown that facial skin symptoms reported among visual display terminal (VDT) workers are associated with a number of exogenous factors. This part of the project investigated the relation between the psychosocial work environment and facial skin complaints. METHODS: From an initial questionnaire study among 4943 office workers, 163 VDT workers were selected for a case referent study of facial skin symptoms. The data comprise a self-administered questionnaire filled out by 149 subjects and interviews with representatives of the organizations concerned. RESULTS: Psychosocial conditions, especially lack of social support from co-workers, were associated with an increased risk of reporting skin symptoms. Stratification by sex showed that the associations between some psychosocial factors and health differed between men and women. The results indicate that there might be an interaction between psychosocial factors and electric fields in the workplace which increases the risk of reporting skin symptoms. CONCLUSIONS: This study supports the idea that the aetiological basis of facial skin symptoms among VDT-workers includes physical as well as psychosocial factors, and that the interaction between such factors might be significant in the understanding of skin complaints among VDT workers.

Adult↗