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PubMed1995

Myocardial temperatures during in vivo endocardial Nd:YAG laser irradiation.

To determine safety and efficacy of neodymium:YAG laser irradiation of the endocardium, temperatures at both the epicardium and the endocardium were recorded for thermal damage evaluation. A total of 48 coagulation lesions were created at power settings of 20 and 30 W in 20 open chest dogs by transcatheter endocardial laser irradiation. Tissue temperatures were monitored by epicardial thermography (Tepi), and by endocardial thermocouples at the catheter tip (Tprox) and 4 mm below the endocardial surface (Tdist). In group I the optical fiber extended 1 mm from the catheter and irradiation times ranged from 3 to 60 sec. Tepi reached > or = 57 degrees after a weighted average of 5 sec of laser irradiation (n = 44). In group II the fiber was retracted 1 mm from the catheter tip, and irradiation times were 100 to 150 sec. Tepi reached > or = 57 degrees C after a weighted average of 30 sec (n = 4). Blood vessels were recognized as heat sinks until coagulation occurred. Lesion volume showed a proportional increase with total delivered energy. From the observed timeframes in epicardial temperature rise it is suggested that total direct light absorption at the epicardium was the main contribution to Tepi, and the Nd:YAG laser can efficiently create transmural lesions. The epicardial temperatures remained below 80 degrees C in combination with the constant movement of the epicardial wall suggested safety from thermal damage to the ambient organs.

Animals↗
PubMed2004

Shock waves increase T-cell proliferation or IL-2 expression by activating p38 MAP kinase.

Shock waves were elicited by transient pressure disturbances, which could be used to treat musculoskeletal disorders. In present studies, we investigated whether the low-density shock waves (LDSWs), which are able to damage plasma membrane without impairing the vimentin or other organelles, might augment T-cell proliferation as well as IL-2 expression, and if mitogen activated protein kinase p38 (p38 MAPK) might be an underlying mechanism through which the LDSWs enhanced T-cell function. We found that the LDSWs increased activation of p38 MAPK in Jurkat T cells. The LDSWs alone didn't result in the T-cell proliferation and IL-2 expression. However, in combination with other stimuli, LDSWs could augment the T-cell proliferation and IL-2 expression. Inhibition of p38 MAPK using SB203580 reduced the stimulatory effects of the LDSWs, which indicated that the LDSWs enhanced IL-2 expression through a mechanism that involved p38 MAPK activation. We concluded that the p38 MAPK activation played a key role in the regulation of T cells function by the LDSWs.

CD3 Complex↗
PubMed2001

The data sources which may help strengthen the epidemiological evidence for the hormonal hypothesis of sex determination in man.

The hypothesis that parental hormone levels around the time of conception partially control offspring sex ratios-though here taken to be true in substance-will need a great deal of work to specify with any accuracy. We do not know with any certainty which hormones are involved, nor how they are implicated. Answers to these two questions are only likely to emerge after prolonged experimental work. And it is fair to say that that work has not yet started. I assume that experimental workers will not embark on such a project until it is perfectly clear that there is a watertight case that mammalian parental hormone levels somehow influence offspring sex ratios. The present note indicates where further (human) evidence for that case will be found. In regard to human beings, much of the required information is held by clinics and registries not primarily concerned with reproductive biology. This point is illustrated here in regard to toxicology, teratology, radiation medicine, neurology, psychiatry, oncology, dermatology, rheumatology, occupational medicine and sports medicine as well as obstetrics and gynaecology. Tests (based on the hypothesis) are offered for intrauterine endocrine causes of malformations, and for pre- and post-natal endocrine causes of disease.

Congenital Abnormalities↗
PubMed1989

Childhood nervous system tumours: an assessment of risk associated with paternal occupations involving use, repair or manufacture of electrical and electronic equipment.

Parental occupational exposures to chemical carcinogens have been associated with malignancies in offspring. Recent studies have raised the issue that electromagnetic fields may play a role in carcinogenesis. We conducted a population-based case-control study testing for an association between the occurrence of a nervous system tumour in a child and paternal employment at the time of the child's birth in occupations involving potential exposure to low frequency electromagnetic fields, primarily in the electrical and electronics industries. Birth certificate data, including parental occupation information, of 499 children who died in Texas from intracranial and spinal cord tumours were compared with 998 controls randomly selected from Texas livebirths. The odds ratio for paternal employment in industries involving potential electromagnetic field exposure was 1.6 (p less than 0.07). A risk of 3.5 (p less than 0.05) was detected for fathers who were electricians. The additional presence of chemical exposures in these diverse occupations and industries must also be considered.

Case-Control Studies↗
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↗
PubMed1993

Radar guns.

Explore the source record for details and available documents.

Humans↗
PubMed1999

Extremely low frequency electromagnetic fields (EMF) and brain cancer in adults and children: review and comment.

Epidemiologic and experimental research on the potential carcinogenic effects of extremely low frequency electromagnetic fields (EMF) has now been conducted for over two decades. Cancer epidemiology studies in relation to EMF have focused primarily on brain cancer and leukemia, both from residential sources of exposure in children and adults and from occupational exposure in adult men. Because genotoxic effects of EMF have not been shown, most recent laboratory research has attempted to show biological effects that could be related to cancer promotion. In this report, we briefly review residential and occupational EMF studies on brain cancer. We also provide a general review of experimental studies as they relate both to the biological plausibility of an EMF-brain cancer relation and to the insufficiency of such research to help guide exposure assessment in epidemiologic studies. We conclude from our review that no recent research, either epidemiologic or experimental, has emerged to provide reasonable support for a causal role of EMF on brain cancer.

Adult↗
PubMed1999

Radiofrequency electrocution (196 MHz).

Radiofrequency (RF) electrocutions are uncommon. A case of electrocution at 196 MHz is presented partly because there are no previous reports with frequencies as high as this, and partly to assist in safety standard setting. A 53-year-old technician received two brief exposures to both hands of 2A current at 196 MHz. He did not experience shock or burn. Progressively over the next days and months he developed joint pains in the hands, wrists and elbows, altered temperature and touch sensation and parasthesiae. Extensive investigation found no frank neurological abnormality, but there were changes in temperature perception in the palms and a difference in temperature between hands. His symptoms were partly alleviated with ultra-sound therapy, phenoxybenzamine and glyceryl trinitrate patches locally applied, but after several months he continues to have some symptoms. The biophysics and clinical aspects are discussed. It is postulated that there was mainly surface flow of current and the micro-vasculature was effected. Differences to 50 Hz electrocution are noted. Electrocution at 196 MHz, even in the absence of burns may cause long-term morbidity to which physicians should be alerted. Safety standards should consider protection from electrocution at these frequencies.

Arthralgia↗
PubMed1992

Magnetic field effects on pineal indoleamine metabolism and possible biological consequences.

In recent years, there has been a great deal of publicity concerning the possible health effects of electric and/or magnetic field exposure. One of the most frequently reported observations after the exposure of animals to either electric or magnetic fields relates to alterations in the metabolism of serotonin (5HT) to melatonin within the pineal gland. This review summarizes these results particularly in animals exposed to intermittently inverted, non-time varying magnetic fields, i.e., pulsed static magnetic fields. When exposure occurs at night, the conversation of 5HT to melatonin is typically depressed, not unlike that after light exposure at night. The mechanisms by which pulsed magnetic fields alter the ability of the pineal to convert 5HT to the chief pineal hormone melatonin remains unknown but may involve effects on any or all of the following: the retinas, the suprachiasmatic nuclei, the peripheral sympathetic nervous system, and the pinealocytes. Results to date suggest that induced electrical currents (eddy currents) produced by the pulsed magnetic fields are particularly detrimental to pineal indoleamine metabolism and may be an important causative factor in the metabolic changes measured. The physiological consequences of perturbations in the melatonin rhythm induced by magnetic field exposure remain unknown.

Animals↗
PubMed2004

Turning on stem cell cardiogenesis with extremely low frequency magnetic fields.

Modulation of stem cell differentiation is an important assignment for cellular engineering. Embryonic stem (ES) cells can differentiate into cardiomyocytes, but the efficiency is typically low. Here, we show that exposure of mouse ES cells to extremely low frequency magnetic fields triggered the expression of GATA-4 and Nkx-2.5, acting as cardiac lineage-promoting genes in different animal species, including humans. Magnetic fields also enhanced prodynorphin gene expression, and the synthesis and secretion of dynorphin B, an endorphin playing a major role in cardiogenesis. These effects occurred at the transcriptional level and ultimately ensued into a remarkable increase in the yield of ES-derived cardiomyocytes. These results demonstrate the potential use of magnetic fields for modifying the gene program of cardiac differentiation in ES cells without the aid of gene transfer technologies and may pave the way for novel approaches in tissue engineering and cell therapy.

Cell Differentiation↗
PubMed2001

Radio frequency radiation exposure standards: considerations for harmonization.

Radio frequency radiation exposure standards vary in origin, development process, legal status, and in the actual exposure limits. To identify the sources of differences in limits, we evaluated technical aspects of eight standards that included supporting information on the scientific data and rationale. Comparisons were made among the standards by examining the scope of the underlying database, the rationales for safety factors and other issues underlying exposure limits in the energy-deposition range (0.1 MHz to 10.0 GHz) and in the surface-heating range (about 10 or 15 GHz to 300 GHz). The framework for this assessment was based on the methods recommended by the scientific and regulatory organizations for developing health-based exposure limits. General guidelines for performing risk assessments for threshold acting agents have been developed by the U.S. Environmental Protection Agency, Health Canada's Environmental Health Directorate, and the International Program on Chemical Safety of the World Health Organization. This general methodology was applied to radiofrequency radiation for this assessment. Because these methods strive to identify scientific issues and separate them from risk management or policy, they provide a basis for evaluation of standards in this paper. This distinction can provide a foundation for the longer-term goal of global harmonization of radio frequency radiation standards. Each of the standards evaluated in the energy-deposition range was found to use the same basic restriction, based on biological data and a 10-fold safety factor, yet explanations reflect different interpretations of the underlying biological data. Rationales differ for the magnitude of the safety factor, for the circumstances of exposure, for the nature of sensitive populations, and for the presumed health status of the individuals for whom the basic restriction is applicable. In the surface-heating range, broad variability in exposure limits are seen in the limit itself, as well as in the approach to time averaging and frequency dependence. Averaging times differ among standards, as do tissue geometries for defining partial-body exposures. The differences in approaches to develop the standards do not completely explain differences among the exposure limits, and methods for computing exposure limits from basic restrictions are not always defined. This analysis suggests harmonization of standards will require more detailed review and coordination of biological and engineering data and of policy options.

Canada↗
PubMed2002

Medical aspects of radiofrequency radiation overexposure.

Despite seemingly widespread concerns about radiofrequency radiation overexposure to the general population, there is very little in the medical literature that addresses this issue. This article is written by a consensus-forming body composed of physicians, biologists, engineers, and physical scientists. It addresses those aspects of radiofrequency radiation exposure that are pertinent to clinical medicine. It is intended to provide basic information on radiofrequency radiation injuries to be helpful to physicians should they ever be presented with a patient who was overexposed to radiofrequency radiation. Salient features of radiofrequency radiation physics, radiofrequency radiation injuries, and national safety standards are discussed. A synopsis of the signs and symptoms of radiofrequency radiation overexposure and a statement concerning the role of a physician are also included. This Note is intended to update practitioners on the best available information on radiofrequency radiation exposure management and the results of recent national and international standard setting activities.

Biophysical Phenomena↗