No detectable bioeffects following acute exposure to high peak power ultra-wide band electromagnetic radiation in rats

A wide range assessment of the possible bioeffects of an acute exposure to high peak power ultra-wide band (UWB) electromagnetic radiation was performed in rats. The UWB-exposure consisted of 2 min of pulsed (frequency: 60 Hz, pulse width: 5-10 ns) UWB (bandwidth: 0.25-2.50 GHz) electromagnetic radiation. Rats were examined using one of the following: 1) a functional observational battery (FOB); 2) a swimming performance test; 3) a complete panel of blood chemistries; or 4) determination of the expression of the c-fos protein in immunohistologically-stained sections of the brain. No significant differences were found between UWB- or sham-exposed rats on any of the measured parameters.     

Increased flight surgeon role in military aeromedical evacuation

BACKGROUND: Physicians were involved in the development of aeromedical evacuation (medevac) and flight surgeons flew as crewmembers on the first U.S. military medevac flights. However, since World War II flight surgeons have not been routinely assigned to operational medevac units. The aeromedical literature addressing the role of physicians in medevac is controversial. Recent contingencies involving the U.S. Air Force (USAF) have required the augmentation of medevac units with flight surgeons. RECENT CHANGES IN THE EUROPEAN THEATER: Beginning in 1992, the United States Air Forces Europe (USAFE) assigned three flight surgeons to the medevac squadron. Between 2 February 1993 and 24 March 1994 USAFE moved 241 patients on 29 missions out of the former Yugoslavia--most of these missions had a flight surgeon on the crew. Because advance medical information on the status of these patients is often nonexistent, the presence of a physician on the crew proved life-saving in some instances. In peacetime operations, there has been a recent trend in the European theater for the USAF to move more unstable patients. OBSERVED BENEFITS OF PHYSICIANS IN MEDEVAC: Dedicated medevac flight surgeons have proven to have the specific experience and training to perform effectively in the role of in-flight medical attendant. In addition, they are effective in negotiating with referring physicians about the urgency of movement, required equipment, the need for medical attendants, etc. These flight surgeons also provide medical coverage of transiting patients in the Aeromedical Staging Flight (ASF), thus providing needed continuity in the medevac system. CONCLUSION: Dedicated medevac flight surgeons fill a unique and valuable role in medevac systems. Agencies with medevac units should consider assigning flight surgeons to these units.     

Further analysis of the reliability of the posterior tangent lateral lumbar radiographic mensuration procedure: concurrent validity of computer-aided X-ray digitization

OBJECTIVE: To investigate the reliability of a specific method of radiographic analysis of the geometric configuration of the lumbopelvic spine in the sagittal plane, and to investigate the concurrent validity of a computer-aided digitization procedure designed to replace the more tedious and time-consuming manual measurement process. DESIGN: A blind, repeated-measures design was used. The results of radiographic measures derived through the traditional manual marking method were compared with measures derived by computer-aided digitization of lateral lumbopelvic radiographs. SETTING: Private chiropractic clinic. MAIN OUTCOME MEASURES: Pearson's product-moment correlation coefficients, paired sample t tests and intraclass correlation co-efficients (ICC) were used to examine intraexaminer reliability, and repeated measures of analysis of variance were used to examine interexaminer reliability for relative rotation angles for T12-L1, L1-L2, L2-L3, L3-L4, L4-L5, L5-S1, overall lordosis measurement [absolute rotation angle (ARA)] from L1-L5 and Cobb angle of overall lordosis measured from the inferior surface of T12 to the superior surface of S1, Ferguson's sacral base angle to horizontal, angle of pelvic tilt (arcuate angle) to horizontal and anteroposterior thoracic translation (Sz) in millimeters. RESULTS: ICC estimates for intraexaminer reliability were in the range of 0.96-0.98 for the L1-L5 ARA, a range of 0.87-0.99 for the arcuate angle measurement, 0.83-0.94 for the Ferguson's angle measurement, 0.88-0.95 for the Cobb angle measurement from the inferior surface of T12 compared with the superior surface of S1 and 0.98-1.00 for the translation measurement of the lower thoracic spine to S1 (Sz). The intersegmental measurement's (T12-L1, L1-L2, L2-L3, L3-L4, L4-L5, L5-S1) correlations ranged from a low of 0.55 to a high of 0.97. Examination of these findings suggests that the reliability for the three doctors is acceptable with only the T12-L1 intersegmental measure falling below 0.70 for the least experienced examiner. Average ICC of interexaminer reliability for manual and computer-aided digitizing examiners were the following: 0.96 for the L1-L5 ARA; 0.84 for the arcuate angle measurement; 0.82 for the Ferguson's angle measurement; 0.88 for the Cobb angle measurement; 1.00 for the Sz translation measurement; and values of 0.65, 0.73, 0.74, 0.75, 0.89 and 0.81 for relative rotation angle measurements T12-L1, L1-L2, L2-L3, L3-L4, L4-L5 and L5-S1, respectively. CONCLUSION: The data tend to support the reliability of this method of radiographic analysis of the geometric configuration of the lumbopelvic spine as viewed on lateral lumbopelvic radiographs. The additional data presented here tend to support the concurrent validity of the computer-aided digitization method of analysis inasmuch as the measures determined by the digitizing examiners are essentially identical to those determined by the manual method plus or minus the average standard error of measure of each value.     

Muscle strain during aerial combat maneuvering exercise

BACKGROUND: Little is known about the in-flight muscular strain of fighter pilots. HYPOTHESIS: The purpose of this study was to measure fighter pilots' mean and peak muscular strain during aerial combat maneuvering exercises. The results obtained were compared against existing ergonomic recommendations. METHODS: Six pilots volunteered to serve as test subjects. Their mean age (+/- SD) was 28.5 +/- 5 yr, height 181 +/- 7 cm, and weight 75 +/- 10 kg. They performed one-to-one dog-fight exercises in the morning and in the afternoon. During the flights, the pilots' electromyographic activity (EMC) was measured from the thigh, abdomen, back, and lateral neck. The mean and peak muscular strain for each muscle was calculated as the percentage of maximal voluntary contraction (%MVC). RESULTS: The results showed that the mean muscular strain was 5.2-19.8% MVC, the strain in the lateral neck being the highest. Peak muscular strain (over 50% MVC) occurred almost only during the encounters and usually in the lateral neck. Other muscles were subjected to fewer peak strain episodes; most of these occurred in the back. At least one peak strain episode exceeding 100% MVC was recorded for every muscle studied. The highest peak strain 257% MVC, was measured in the lateral neck. This peak strain episode caused an injury to the lateral neck area, and the flight mission was discontinued. CONCLUSIONS: The mean muscular strain measured in this study was rather low. However, the strain occurring in the lateral neck and the back exceeds the ergonomic recommendations for static work. Especially in the lateral neck, and to some extent in the back, peak strain occurs frequently, in a magnitude that is well above the maximal voluntary contraction; in these areas, the peak strain presents a potential risk of injury and negative health effects. The level and frequent occurrence of peak strain episodes means that fighter pilots' muscular strength and muscular endurance, especially in the neck and shoulder area, are subjected to demands clearly higher than those of the average population.     

Extra-cellular volume estimation by electrical impedance--phase measurement or curve fitting: a comparative study

The intestinal polyamine transporters have not yet been identified. Our aim was to characterize specific polyamine binding sites in rabbit intestinal brush-border membranes (IBBM) as a starting step for identification of polyamine transporters. This was investigated at 4 degrees and at low membrane concentration. Saturation isotherms for [3H]putrescine (PUT) binding indicated a single population of sites (puT) with a dissociation equilibrium constant Kd of 3.8 microM and a density of sites Bmax of 58 pmol/mg of protein. [3H]spermidine (SPD) binding also involved only one class of sites (spD), albeit with a lower affinity (Kd = 106 microM) and higher abundance (Bmax = 1240 pmol/mg of protein) than puT. On the contrary, [14C]spermine (SPM) bound two classes of sites (spM1 and spM2) differing in their affinity (Kd = 2.5 and 31.4 microM) and abundance (Bmax = 467 and 1617 pmol/mg of protein, respectively). Membrane association of SPM at 4 degrees was much faster than that of SPD and PUT, both of which proceeded at a similar rate. In contrast to PUT and SPD dissociation, SPM dissociation at 23 degrees did not follow a first-order reaction. Specifically bound [3H]PUT, unlike [3H]SPD and [14C]SPM, dissociated at 23 degrees independently of the addition of nonradioactive polyamine. Methylglyoxal-bis-(guanylhydrazone) was an extremely potent inhibitor of PUT binding (Ki = 3.2 +/- 1.5 nM), but as with PUT and cadaverine (CAD), it did not alter [3H]SPD and [14C]SPM binding substantially. The intestinal brush-border membrane may contain at least three sites specific for polyamine binding and exhibiting different ligand selectivity. Site puT might be associated with the transport system already described for intestinal uptake of PUT.     

FGF is a prospective competence factor for early activin-type signals in Xenopus mesoderm induction

Normal pattern formation during embryonic development requires the regulation of cellular competence to respond to inductive signals. In the Xenopus blastula, vegetal cells release mesoderm-inducing factors but themselves become endoderm, suggesting that vegetal cells may be prevented from expressing mesodermal genes in response to the signals that they secrete. We show here that addition of low levels of basic fibroblast growth factor (bFGF) induces the ectopic expression of the mesodermal markers Xbra, MyoD and muscle actin in vegetal explants, even though vegetal cells express low levels of the FGF receptor. Activin, a potent mesoderm-inducing agent in explanted ectoderm (animal explants), does not induce ectopic expression of these markers in vegetal explants. However, activin-type signaling is present in vegetal cells, since the vegetal expression of Mix.1 and goosecoid is inhibited by the truncated activin receptor. These results, together with the observation that FGF is required for mesoderm induction by activin, support our proposal that a maternal FGF acts at the equator as a competence factor, permitting equatorial cells to express mesoderm in response to an activin-type signal. The overlap of FGF and activin-type signaling is proposed to restrict mesoderm to the equatorial region.