Subjective symptoms among mobile phone users—A consequence of absorption of radiofrequency fields?

In a previous epidemiological study, where we studied the prevalence of subjective symptoms among mobile phone (MP) users, we found as an interesting side finding that the prevalence of many of the subjective symptoms increased with increasing calling time and number of calls per day. In this extrapolative study, we have selected 2402 people from the epidemiological study who used any of the four most common GSM MP. We used the information about the prevalence of symptoms, calling time per day, and number of calls per day and combined it with measurements of the Specific Absorption Rate (SAR). We defined three volumes in the head and measured the maximum SAR averaged over a cube of 1 g tissue (SAR(1g)) in each volume. Two new exposure parameters Specific Absorption per Day (SAD) and Specific Absorption per Call (SAC) have been devised and are obtained as combinations of SAR, calling time per day, and number of calls per day, respectively. The results indicates that SAR values >0.5 W/kg may be an important factor for the prevalence of some of the symptoms, especially in combination with long calling times per day.     

Chromosomal aberrations in human amniotic cells after intermittent exposure to fifty hertz magnetic fields

Our recent studies have shown a significant increase in the frequency of chromosomal aberrations in human amniotic cells after exposure to a sinusoidal 50 Hz, 30 μT (rms) magnetic field. To evaluate further interactions between chromosomes and electromagnetic fields, we have analyzed the effects of intermittent exposure. Amniotic cells were exposed for 72 h to a 50 Hz, 30 μT (rms) magnetic field in a 15 s on and 15 s off fashion. Eight experiments with cells from different fetuses were performed. The results show a 4% mean frequency of aberrations among exposed cells compared to 2% in sham-exposed cells. The difference is statistically significant, with P < 0.05 both excluding and including gaps. In another series of eight experiments, the cells were exposed in the same way but with the field on for 2 s and off for 20 s. Also in these experiments a similar increase in the frequency of chromosomal aberrations was seen, but only when the analysis included gaps. Continuous exposure for 72 h to 300 μT, 50 Hz, did not increase the frequency of chromosomal aberrations. The background electromagnetic fields at different locations within the two incubators used was carefully checked and was nowhere found to exceed 120 nT. Likewise, the background level of chromosomal aberrations in cells cultured at different locations in the incubators showed no significant interculture differences. © 1994 Wiley-Liss, Inc.     

Determination of reactive oxygen and nitrogen species in rat aorta using the dichlorofluorescein assay

A method for the determination of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in macroscopic sections of vessels has been developed on the basis of the dichlorofluorescein (DCF) assay. DCF was measured by fluorescence in extracts of vessels. The main artifact of the method is the oxidation of dichlorodihydrofluorescein (DCFH₂) which is released from vessels together with DCF during the extraction procedure. This problem was resolved by decreasing pH during the extraction. The optimal conditions and the time for aorta incubation with DCFH₂-DA and for the extraction of DCF from aorta have been determined. The ROS/RNS production in different aorta segments and the dependence of ROS/RNS production on rat age have been studied. It was shown that thoracic aorta sections produced the same amounts of ROS/RNS and the intermediate between the thoracic and the abdominal aorta part produced ROS and RNS by 14% more than the thoracic aorta. It was found that ROS/RNS production in aorta increases with rat age: the doubling time of ROS/RNS production rate is 113 days from birth.     

Gα<Subscript>16</Subscript> interacts with tetratricopeptide repeat 1 (TPR1) through its β3 region to activate Ras independently of phospholipase Cβ signaling

Background  

G protein-coupled receptors constitute the largest family of cell surface receptors in the mammalian genome. As the core of the G protein signal transduction machinery, the Gα subunits are required to interact with multiple partners. The GTP-bound active state of many Gα subunits can bind a multitude of effectors and regulatory proteins. Yet it remains unclear if the different proteins utilize distinct or common structural motifs on the Gα subunit for binding. Using Gα₁₆ as a model, we asked if its recently discovered adaptor protein tetratricopeptide repeat 1 (TPR1) binds to the same region as its canonical effector, phospholipase Cβ (PLCβ).