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At least 1,045 records · Page 58Linked to original sources
PubMed1999

Exposure of the critically ill patient to extremely low-frequency electromagnetic fields in the intensive care environment.

OBJECTIVE: To measure the electromagnetic emission of intensive care medical equipment, in order to assess whether a potentially dangerous magnetic flux is present around the patient, and to evaluate the exposure conditions of the patient to extremely-low-frequency electromagnetic fields (ELF EMF). DESIGN: Descriptive study. SETTING: Intensive care unit (ICU) at a general hospital. MEASUREMENT AND RESULTS: The flux density of alternating (AC) 50-H2, EMF was measured and mapped around electrical devices in a six-beds adult ICU furnished with standard equipment (ventilator, monitor, infusion pumps, heated airbed, humidifier). The overall flux density in the patient area was assessed by measuring the field intensity at the patient's head during the day and at night over 6 days. The magnetic flux density was not uniformly distributed around each device, being higher [up to 40 microTesla (microT)] close to fan motors and mains supply. In 83 % of the patients a field intensity > 0.20 microT (safety limit) was detected. CONCLUSIONS: The ICU environment is at risk from electromagnetic pollution, the long-term stay of chronic patients and their "day-long" exposure are additional risk factors. EMFs drop off as the distance from the equipment is increased, according to the inverse-square law, and the exposure risk may be minimized by keeping a safety distance from the EMF source. The actual value of that safety distance may be variable and depends on several factors: (1) type of equipment, (2) orientation of equipment, (3) equipment "overcrowding" and (4) available space in each bed space. The magnetic flux density should be monitored regularly in every ICU for the specific design of each unit.

Aged↗
PubMed2002

Effectiveness of bioremediation of crude oil contaminated subantarctic intertidal sediment: the microbial response.

A field study was initiated in February 1996 in a remote sandy beach of The Grande Terre (Kerguelen Archipelago, 69 degrees 42 degrees E, 49 degrees 19 degrees S) with the objective of determining the long-term effects of some bioremediation agents on the biodegradation rate and the toxicity of oil residues under severe subantarctic conditions. A series of 10 experimental plots were settled firmly into sediment. Each plot received 2L of Arabian light crude oil and some of them were treated with bioremediation agents: slow release fertilizer Inipol EAP-22 (Elf Atochem) or fish composts. Plots were sampled on a regular basis over a 3-year period. A two-order of magnitude increase of saprophytic and hydrocarbon-utilizing microorganisms occurred during the first month of the experiment in all treated enclosures, but no clear differences appeared between the plots. Very high microbial populations were present during the experiment. Biodegradation within treated spots was faster than within the untreated ones and appeared almost complete after 6 months as indicated by the degradation index of aliphatic hydrocarbons within all plots. The analysis of interstitial water collected below the oily residues presented no toxicity. However, a high toxicity signal, using Microtox solid phase, appeared for all oiled sand samples with a noticeable reduction with time even if the toxicity signal remained present and strong after 311 days of oil exposition. As a conclusion, it is clear that the microbial response was rapid and efficient in spite of the severe weather conditions, and the rate of degradation was improved in presence of bioremediation agents. However, the remaining residues had a relatively high toxicity.

Animals↗
PubMed2003

Biostimulation of natural microbial assemblages in oil-amended vegetated and desert sub-Antarctic soils.

A field study was initiated in December 2000 in two selected soils of The Grande Terre (Kerguelen Archipelago) with the objective of determining the long-term effects of fertilizer addition on the biodegradation rate and the toxicity of oil residues under severe sub-Antarctic conditions. Two soils were selected. The first site supports an abundant vegetal cover; the second one was desert soil, devoid of plant material. These two soils were located in the vicinity of the permanent station of Port-aux-Français (69 degrees 42'E; 49 degrees 19'S). A series of five experimental plots (0.75 x 0.75 m) were settled firmly into each of the studied soils. Each plot received 500 mL of diesel or Arabian light crude oil, and some of them were treated with a bioremediation agent: slow-release fertilizer Inipol EAP-22 (Elf Atochem). All the plots were sampled on a regular basis over a 1 year period. Heterotrophic and hydrocarbon-degrading microorganisms increased by two orders of magnitude during the first month of the experimentation in all treated enclosures, but differences appeared between the different plots. The microbial response was improved by bioremediation treatments. However, fertilizer addition had a greater impact on the desert soil when compared to the vegetated one. All chemical indices show a reduction of alkanes and light aromatics. Toxicity results show a high variability between treatments and environmental conditions. As a conclusion, it is clear that the microbial response was rapid and efficient in spite of the severe weather conditions, and the rate of degradation was improved by bioremediation treatments. However, after 1 year of treatment, the signal of a relatively high toxicity of oiled residues remained present in the two studied soils.

Acridine Orange↗
PubMed2003

Extremely low frequency magnetic fields affect transposition activity in Escherichia coli.

The aim of this study was to verify whether extremely low frequency (ELF) magnetic fields (MF) could affect transposition activity like some environmental stress factors such as heat shock or UV irradiation. Using an Escherichia coli Lac Z(-) strain transformed with a plasmid containing a Tn 10 derivative element expressing beta-galactosidase only after transposition, it was possible to determine the events of transposition evaluating the rate at which the colonies developed dark coloured papillae (Lac Z(+)). We found that those bacteria that had been exposed for a long time (58 h) to a 50 Hz low intensity MF (0.1-1 mT) gave colonies with significantly lower transposition activity compared to sham-exposed bacteria. Such reduction in transposition activity was positively correlated to the intensity of the MF, in a dose-effect manner. This phenomenon was not affected by bacterial cell proliferation, since no significant differences were observed in number, diameter and perimeter between sham-exposed and MF-exposed colonies.

Cell Cycle↗
PubMed2006

Exposure to extremely low frequency magnetic fields in an urban area.

Magnetic field levels were studied in an urban area--the city of Cáceres (Spain). The study included systematic spot measurements throughout the city, an analysis of the temporal variation of the magnetic field, and the incorporation of the data into a geographic information system. The levels detected were at most 7.3% of the ICNIRP reference levels, and the highest fields were found in the oldest neighborhoods. Considered overall, the ELF magnetic flux density levels determined in the present study were between those found in residential and in working environments. Knowledge of the levels of such fields in urban areas is therefore fundamental in evaluating the population's overall exposure, especially for people who work outdoors.

Environmental Exposure↗
PubMed1999

Induction of cAMP-dependent protein kinase A activity in human skin fibroblasts and rat osteoblasts by extremely low-frequency electromagnetic fields.

Sinusoidal extremely low-frequency electromagnetic fields (ELF-EMF; 7-8 mT, 20 Hz) have already been shown to inhibit proliferation and to accelerate terminal differentiation of human skin fibroblasts in vitro. In order to elucidate the underlying processes of signal transduction, we analysed the activity of cAMP-dependent protein kinase (PKA). EMF exposure for 60 min resulted in an increased PKA activity in human skin fibroblasts (2-fold) and rat embryonic osteoblasts (1.7-fold). Long-term exposure for up to 7 days with a constant 1 h-on/1 h-off EMF exposure rhythm indicated a transient stimulation of PKA activity during the first two exposure rhythms followed by a decrease to the baseline levels of sham-exposed controls. Based on these results, we postulate that a modulation of proliferation and differentiation processes in cells of mesenchymal origin is triggered by an immediate and transient EMF-induced increase in PKA activity.

Animals↗
PubMed1997

Regulation of topographic projection by the Eph family receptor Bsk (EphA5) and its ligands.

Topographic projection is a general feature of brain architecture and is critical for appropriate information processing and coding. Nevertheless, little is known about the mechanisms that govern topographic organization. The Eph family receptor tyrosine kinases and ligands have recently been implicated in the specification of topographic maps. We have shown that Bsk, an Eph family receptor, and its ligands are expressed in a complementary fashion in neurons and targets, respectively, in several neural systems. For example, in the hippocampus, Bsk is expressed in an increasing lateral to medial gradient. In contrast, at least three different ligands, viz., Elf-1, LERK3/Ehk1-L, and AL-1/RAGS/LERK7, are transcribed in complementary (opposing) gradients in the hippocampal subcortical target, the lateral septum. However, the spatial and temporal distribution of the ligands are different, such that combinatorially they specify the full target region during development. Consistent with a key role in hippocamposeptal topographic projection, the ligands selectively inhibit the growth of the topographically inappropriate medial hippocampal neurites but sustain the growth of the appropriate lateral neurites. Our studies indicate that the interaction of Bsk and its ligands restricts the receptor-positive medial neurons to the topographically appropriate, ligand-poor dorsal septal target. In addition to the hippocamposeptal system, Bsk and its ligands are also expressed in afferents and targets of several other systems, including the olfactory and the retinotectal systems. Consequently, Bsk and its ligands may play important roles in neuron-target interactions in multiple neural circuits.

Animals↗
PubMed2005

The role of dental evaluation and cephalometric analysis in the diagnosis of Williams-Beuren syndrome.

Williams-Beuren syndrome (WS) is a genetic condition with an incidence of 1 in 20,000-50,000 live births. The syndrome consists of supravalvular aortic stenosis, characteristic dysmorphic facial features named "elf face" and intellectual disability. Early diagnosis of the syndrome is important since many of its features require treatment, and the prognosis can be dramatically improved by early recognition and management. This developmental disorder is well known to be clinically heterogeneous, making diagnosis difficult if based on the clinical picture. However, genetic testing is expensive and it is not cost effective to screen all patients based on clinical suspicion. Our goal was to develop a novel clinical screening method that would be sensitive, specific, inexpensive and readily available. We performed cephalometric analysis and dental evaluation of 33 patients with genetically proven WS. Cephalometric analysis of soft tissues showed that with normal SNA, SNB and ANB angles, the lips were in front of the line of harmony. This finding was present in all WS patients (n = 33) but in none of the age-matched controls (n = 100). No other differences were found between WS and control patients. This cephalometric finding is specific and sensitive for WS and can be used in the diagnostic procedure, whereas none of the conventional dental evaluations are useful.

Adolescent↗
PubMed2005

Identification of CBFA1-regulated genes on SaOs-2 cells.

Current knowledge about mechanisms controlling osteoblast-specific gene expression has led to the identification of Cbfa1 as a key regulator of osteoblast differentiation. Several essential questions about this transcription factor remain to be addressed, e.g., the nature of stimuli that may modulate its own expression, as well as the genetic repercussions following alterations in Cbfa1 levels. To identify such Cbfa1-responsive genes, the SaOs-2 cell line was stably transfected with a dominant negative mutant of Cbfa1 (DeltaCbfa1). Comparison of gene expression patterns by differential display on selected SaOs-2 clones allowed the identification of four new genes that may be under the control of Cbfa1. Three of them, SelM, elF-4AI, and RPS24, seemed to be linked to a global change in cellular metabolism and cell growth. The fourth, the CD99/MIC2 gene, was strongly overexpressed (around tenfold) in cells presenting high levels of Deltacbfa1. This observation adds evidence to show that this marker of Ewing family tumors is linked to the osteoblast lineage. The exact function of CD99 remains largely undefined, and this is the first time that its regulation by an essential transcription factor involved in osteoblast differentiation has been observed.

12E7 Antigen↗
PubMed2001

Influence of macrolide antibiotics on promotion of resistance in the oral flora of children.

BACKGROUND: The long elimination half-life of azithromycin allows subinhibitory serum and epithelial lining fluid (ELF) concentrations over a period of several weeks post treatment, which may have an impact on the emergence of macrolide resistance. In this prospective, open-label, randomized study, four macrolides and the azalide azithromycin were studied for their likelihood to promote resistance in the oral flora of children with respiratory tract infections. PATIENTS AND METHODS: Children were randomly assigned to receive azithromycin, clarithromycin, erythromycin, roxithromycin and josamycin. Throat swabs were obtained prior to treatment and weekly for 6 weeks. Minimum inhibitory concentrations (MICs) for resistant strains were assessed by E-test and National Committee for Clinical laboratory Standards (NCClS) broth microdilution. RESULTS: One week post treatment, up to 90% of children harbored macrolide-resistant strains in their oral flora. Except for azithromycin, the percentage of patients colonized by resistant organisms decreased to a rate of 17% for clarithromycin (10/60), erythromycin (2/12) and josamycin (2/12) and 33% for roxithromycin (4/12) after 6 weeks. In the azithromycin group, 85% (51/60) of patients were colonized by macrolide-resistant organisms after 6 weeks, 11.6% (7/60) of children suffered from reinfection. CONCLUSION: Azithromycin therapy appears to put selective pressure on the infective and native flora of children, promoting the carriage of macrolide-resistant strains.

Adolescent↗
PubMed1996

Induction of gamma-glutamylcysteine synthetase by cigarette smoke is associated with AP-1 in human alveolar epithelial cells.

Increased levels of glutathione (GSH) occur in the epithelial lining fluid (ELF) of chronic cigarette smokers. Therefore we investigated the effect of cigarette smoke condensate solution (CSC) on GSH synthesis and the regulation of gamma-glutamylcysteine synthetase (gammaGCS) in human type II alveolar epithelial cells (A549). CSC exposure increased GSH levels, gammaGCS activity and gammaGCS heavy subunit (HS) mRNA, as well as increasing DNA binding of the activator protein-1 (AP-1) and the human antioxidant response element (hARE). Transfection of deletion constructs of the gammaGCS-HS promoter in a chloramphenicol acetyl transferase (CAT) reporter system revealed that an hARE, present within promoter, is not required for the CSC mediated induction. We conclude that CSC induction of gammaGCS-HS expression is associated with AP-1/AP-1-like responsive elements.

Antioxidants↗
PubMed1992

Lack of direct correlation between p220 cleavage and the shut-off of host translation after poliovirus infection.

Poliovirus induces a drastic inhibition of host protein synthesis soon after infection of susceptible cells. The correlation between this inhibition and the cleavage of p220, a polypeptide that forms part of protein synthesis initiation factor elF-4F, has been examined in detail. Measurements of protein synthesis at half-hourly intervals after infection with poliovirus show the lack of direct correlation between p220 cleavage and the blockade of cellular translation. Moreover, the use of inhibitors of poliovirus RNA synthesis helped to dissociate those two events more clearly. Thus, in the presence of guanidine or Ro 09-0179 when little shut-off was induced by poliovirus extensive proteolytic degradation of p220 took place. When HeLa cells infected with poliovirus are placed at 28 degrees the inhibition of host protein synthesis is prevented and cellular translation continues for at least 8 hr, albeit at a reduced level compared to cells incubated at 37 degrees. At 28 degrees, cleavage of p220 is observed and about 80% of p220 is degraded after 6 hr of incubation at that temperature. Strikingly, when cells in which more than 50% of p220 is cleaved are shifted to 37 degrees, cellular translation recuperates to 100%, in spite of the fact that no detectable p220 is present. Furthermore, if poliovirus-infected cells are incubated for 2 hr at 37 degrees to permit the cleavage of p220 and then are shifted to 28 degrees in the presence of guanidine, cellular proteins are synthesized at the same level as uninfected HeLa cells incubated at 28 degrees. These results show that translation of cellular mRNAs takes place in cells containing a cleaved p220 and indicate that this cleavage is not directly responsible for the shut-off of host translation induced by poliovirus.

Antiviral Agents↗
PubMed1986

A mechanism for the control of protein synthesis by adenovirus VA RNAI.

In the absence of VA RNAI, protein synthesis in adenovirus-infected HeLa cells fails because of defective initiation. Earlier work showed that the defect results from phosphorylation of the initiation factor elF-2 on its alpha subunit. We have identified the protein kinase responsible as the dsRNA-activated inhibitor of protein synthesis (DAI). DAI is present in uninfected state. It is activated in cells infected with the adenovirus mutant Ad5 dl331, which produces no VA RNAI, but not in cells infected with wild-type virus. Activation occurs during the late phase of infection with the mutant virus, and the activator appears to be dsRNA produced by symmetrical transcription of the viral genome. VA RNAI antagonizes the activation of DAI by dsRNA, but it cannot inhibit the activity of DAI once activated. We propose a mechanism for VA RNAI action based on its partially double-stranded nature.

Adenoviruses, Human↗
PubMed1982

Evidence for growth inhibition by platinum electrodes at low current levels.

Platinum is considered to be a noble metal and is often used for electrodes in biological investigations. However, platinum electrodes can form inhibitory compounds, as pointed out by Rosenberg et al. 1965. The aim of this study was to investigate whether platinum electrodes are inert in the extremely low frequency (ELF) range of currents. Human bone marrow cells cultured in agar were used as target cells and were grown under various electrical conditions. A 50% reduction in growth compared with controls was obtained by average currents of 2300 microA at 8 Hz and 110 microA at 80 Hz, the current being derived from a square bipolar voltage waveform. D.c. currents were also inhibitory, with a value of 50% at the 1.4 microA level. The cells were probably not affected directly by the current, since inhibitory properties could be stored in agar and saline and because titanium electrodes at equal current levels did not produce the same effect.

Bone Marrow↗
PubMed1993

Influence of short-term exposure of magnetic field on the bioelectrical processes of the brain and performance.

The influence of an extremely-low-frequency (ELF) magnetic field on the bioelectrical processes of brain and performance was studied by EEG spectral analysis, auditory-evoked potentials (AEP), reaction time (RT) and target-deletion test (TDT). Fourteen volunteers were exposed for 15 min to an intermittent (1 s on/off) 45-Hz magnetic field at 1000 A/m (1.26 mT). Each person received one real and one sham exposure. Statistically significant increases in spectral power through alpha- and beta-bands, as well as in mean frequency of the EEG spectrum were observed after magnetic field exposure. Field-dependent changes of N100 were also revealed. No changes in the amplitudes or latencies of the earlier peaks were observed. No direct effects on RT, nor on TDT performance were seen. However, practice effects on RT (decrease of RT in the course of the test-sessions) seemed to be interrupted by exposure to the magnetic field.

Brain↗
PubMed1995

[Variability of blood pressure. Clinical and therapeutic implications].

The high degree of the intra-individual variability of blood pressure (BP) is related both to biological and technological factors: the biological components of variability are either linked to sympathetic system and respiratory movements or induced by physical and psycho-sensorial stresses; the technological sources of variability are the apparatus and the doctor. The consequences of this high variability can be quantified: the risk for a between-visit change of 35 mmHg for systolic BP (and 17 mmHg for diastolic BP) to be due to the spontaneous BP variability, is as high as 95%. Moreover, according to the regression to the mean, in selected patients with a mean SBP as high as 160 mmHg, a mean spontaneous decrease of 9 mmHg is expected to occur, at the next visit. The physician has then to manage the lack of accuracy of clinic BP measurements. For this purpose, three strategies have to be used: thoroughly examining the patient (if associated with an organ damage, the high BP undoubtedly requires to be treated); rigorously taking into account the published recommendations of BP measurements (the sources of error are now well known and may be easily corrected); finally, using the most sophisticated methods of BP measurements (elf BP measurement), semi-ambulatory or ambulatory BP monitoring, exercise testing), which in some circumstances, may provide useful additional information.

Adult↗
PubMed1995

Magnetic field effects on biomolecules, cells, and living organisms.

This article surveys three major areas of biomagnetic research: (a) the magneto-orientation effect; (b) the role of the geomagnetic field in bird orientation and navigation; and (c) the biological effects of extremely low-frequency magnetic fields. The magneto-orientation effect is caused by diamagnetic anisotropy of highly ordered biological structures, such as visual photoreceptor and chloroplast membranes, in a homogeneous magnetic field of about 10 kG. While it is not possible to orient the individual constituent molecules with such a field because of thermal fluctuation, these ordered structures can be oriented as a whole by virtue of summing the anisotropy over a large number of mutually oriented molecules. While the magneto-orientation effect seems to require the use of unphysiologically strong magnetic fields, certain birds apparently have highly sensitive sensors to detect the geomagnetic field for the purpose of orientation and navigation. However, the advances in this latter field were made mainly in the behavioral studies; the magneto-sensors the the neural mechanisms remain elusive. A number of candidates of the sensors are evaluated. We suggest that pecten oculi, which is unique to avian eyes, should not be overlooked for its possible role as a magneto-sensor based on the magneto-orientation effect. Birds primarily use a static (DC) magnetic field for orientation, but recent investigations indicate that weak alternating (AC) magnetic fields with extremely low frequency (ELF) may have hazardous health effects. Such reports are often received with skepticism, because the effects usually involve magnetic energies that are less than the kT energy. However, some of the in vitro studies yield experimental results that are too significant to be ignored. Here, we propose an argument to explain why low-level magnetic fields can be detected without being overshadowed by thermal noises. Relevance of biomagnetic research to the development of biosensors and novel computational paradigms is also discussed.

Animals↗
PubMed1995

The 'LXCXE' hydropathic superfamily of ligands for retinoblastoma protein: a proposal.

The present study reports structural similarities between viral oncoproteins, growth factors belonging to the insulin family, members of the steroid/thyroid receptor superfamily, a D-type cyclin, the Elf-1 transcription factor and Bcl oncoproteins in regions that have been shown or proposed to mediate complex formation of these proteins with the tumor suppressor retinoblastoma protein (RB). This relationship predicts a common intracellular pathway for mitogenic signals and molecules promoting cell survival. Conversely, the structural evidence described here suggests that RB may play a central role both at the boundary between negative and positive cell growth regulation as well as in developmental decisions between cell death and cell survival.

Amino Acid Sequence↗