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  • Articles  (316)
  • Molecular Sequence Data  (253)
  • Life and Medical Sciences
  • 1990-1994  (316)
  • 1985-1989
  • 1994  (316)
  • Physics  (316)
  • Computer Science  (253)
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  • Energy, Environment Protection, Nuclear Power Engineering
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  • Articles  (316)
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  • 1990-1994  (316)
  • 1985-1989
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 483-487 
    ISSN: 0197-8462
    Keywords: ELF magnetic field ; dosimetry ; electric field probe ; tissue conductivity ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Measuring internal induced electric fields in animals with a miniaturized probe involves a potential error related to the difference between the hole conductivity (σh) and the surrounding tissue conductivity (σt). Theory was developed to describe this phenomenon and checked by probe measurements in agar-filled petri dishes. The value measured in the hole is 2σt/(σh + σt) times the actual field in the tissue. For example, a probe hole in muscle, which is filled with blood, could yield a measurement only about 22% of the true value in the muscle. This potential source of error can be mitigated to some extent by not actually cutting a hole, by using a low-conductivity (e.g., 0.2 S/m) coupling medium in the hole, or by ensuring contact between the probe's electrodes and the tissue. © 1994 Wiley-Liss, Inc.
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  • 2
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 513-518 
    ISSN: 0197-8462
    Keywords: subchronic exposure ; rotating magnetic fields ; neuroendocrine hormone ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We exposed rats to circularly polarized 50 Hz magnetic fields to determine if plasma testosterone concentration was affected. Previous experiments indicate that magnetic fields suppress the nighttime rise in melatonin, suggesting that other neuroendocrine changes might occur as well. Male Wistar-King rats were exposed almost continuously for 6 weeks to magnetic flux densities of 1,5, or 50 μT. Blood samples were obtained by decapitation at 12:00 h and 24:00 h. Plasma testosterone concentration showed a significant day-night difference, with a higher level at 12:00 h when studied in July and December, but the day-night difference disappeared when concentrations were studied in April. In three experiments, magnetic field exposure had no statistically significant effect on plasma testosterone levels compared with the sham-exposed groups. These findings indicate that 6 weeks of nearly continuous exposure to circularly polarized, 50 Hz magnetic fields did not change plasma testosterone concentration in rats. © 1994 Wiley-Liss, Inc.
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  • 3
    ISSN: 0197-8462
    Keywords: magnetic fields ; micelles ; photolysis ; triplet radical pair ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The influence of 60-Hz magnetic fields on free radical reactions can be quantitatively predicted from the knowledge of the effect of static fields on free radical behavior. Studies of radical reactions in micellar systems show that the behavior under a 60-Hz field is identical to that under a static field at any given point in time. © 1994 Wiley-Liss, Inc.
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  • 4
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 519-529 
    ISSN: 0197-8462
    Keywords: electromagnetic fields ; occupational hazards ; fetal development ; carcinogenesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Given the current interest in potential carcinogenic and developmental effects of exposure to extremely-low-frequency electromagnetic fields, there is a need to identify cohorts of exposed female workers for future epidemiologic investigations. This study was designed to test the hypothesis that nurses working in neonatal intensive care units (NICU) may be significantly exposed to power-frequency magnetic fields. An electromagnetic field monitor was used to measure magnetic fields at distances of 5, 15, 30, and 60 cm from the surfaces of each device used in the NICU. Six female nurses assigned to the NICU (the “exposed” group) and six female nurses working in the normal newborn nursery (the “referent” group) wore EMDEX dosimeters for the entire duration of their 12 h shifts. An investigator kept a detailed log of each NICU subject's whereabouts for the first one-third of her shift. Magnetic fields at 5 cm from the front (defined by the nurses' usual work area) of the NICU devices ranged from less than 0.1 to 114 μT and in all cases decreased considerably with increasing distance. The geometric mean of the shift-time-weighted average exposure of the NICU nurses was 0.17 μT compared with 0.11 μT for the normal newborn nurses. The percentage of time when subjects were exposed to magnetic fields of 0.4 μT or greater ranged from 5.8% to 15.6% for the NICU nurses, 0.4% to 2.9% for five of the comparison group nurses, and was 9.4% for one of the normal newborn nurses with unidentified aberrantly high exposures. Log data revealed that the vast majority of observed peaks among NICU nurses occurred while subjects were in close proximity to infant bed units. We conclude that NICU nurses represent one female-intensive job sector with intermittent high exposures to ELF magnetic fields and encourage larger exposure studies of nurses in a variety of medical settings. © 1994 Wiley-Liss, Inc.
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  • 5
    ISSN: 0197-8462
    Keywords: cancer promotion ; initiation ; tumor incidence ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The purpose of this study was to investigate the effects of 2.45 GHz microwave (MW) radiation on dimethylhydrazine (DMH)-induced colon cancer in mice. The subjects were 115 Balb/c mice 4 weeks of age. The animals were divided into group A (control), group B (DMH), group C (DMH + MW), and group D [DMH + 12-O-tetradecanoylphorbol-13-acetate (TPA)]. Radiation (10 mW/cm2) was delivered dorsally with the E field parallel to the mouse's long body axis in an anechoic chamber. Radiations were administered 3 hr daily, 6 days per week, over a period of 5 months. The average SAR was estimated to be 10-12 W/kg. During the course of radiation treatments, DMH was injected once per week. The tumor promoter TPA was administered once per week for 10 weeks, from the third week on, after the initial treatment. The incidence of tumors did not significantly differ between the three test groups (groups B, C, and D; P 〉 0.25). However, the number of tumors, the size of the tumors, and the incidence of protuberant and infiltrative types in tumor-bearing animals were higher in group D compared to groups B and C (P 〈 0.05). No difference was found between groups B and C (P 〉 0.25). The study indicates that 2.45 GHz microwave radiation at 10 mW/cm2 power density did not promote DMH-induced colon cancers in young mice. The study also showed that TPA could accelerate colon tumor production if a tumor was initiated. © 1994 Wiley-Liss, Inc.
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  • 6
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 217-238 
    ISSN: 0197-8462
    Keywords: AC/DC magnetic fields ; mathematical models ; ionic resonance ; IPR ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Theoretical models proposed to date have been unable to clearly predict biological results from exposure to low-intensity electric and magnetic fields (EMF). Recently a predictive ionic resonance model was proposed by Lednev, based on an earlier atomic spectroscopy theory described by Podgoretskii and Podgoretskii and Khrustalev. The ion parametric resonance (IPR) model developed in this paper corrects mathematical errors in the earlier Lednev model and extends that model to give explicit predictions of biological responses to parallel AC and DC magnetic fields caused by field-induced changes in combinations of ions within the biological system. Distinct response forms predicted by the IPR model depend explicitly on the experimentally controlled variables: magnetic flux densities of the AC and DC magnetic fields (Bac and Bdc, respectively); AC frequency (fac); and, implicitly, charge to mass ratio of target ions. After clarifying the IPR model and extending it to combinations of different resonant ions, this paper proposes a basic set of experiments to test the IPR model directly which do not rely on the choice of a particular specimen or endpoint. While the fundamental bases of the model are supported by a variety of other studies, the IPR model is necessarily heuristic when applied to biological systems, because it is based on the premise that the magnitude and form of magnetic field interactions with unhydrated resonant ions in critical biological structures alter ion-associated biological activities that may in turn be correlated with observable effects in living systems. © 1994 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
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    Bioelectromagnetics 15 (1994), S. 239-260 
    ISSN: 0197-8462
    Keywords: AC/DC magnetic fields ; neurite outgrowth ; nerve growth factor ; IPR ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A companion paper describes a predictive ion parametric resonance (IPR) model of magnetic field interactions with biological systems based on a selective relation between the ratio of the flux density of the static magnetic field to the AC magnetic field and the charge-to-mass ratio of ions of biological relevance. Previous studies demonstrated that nerve growth factor (NGF)-stimulated neurite outgrowth (NO) in PC-12 cells can be inhibited by exposure to magnetic fields as a function of either magnetic field flux density or AC magnetic field frequency. The present work examines whether the PC-12 cell response to magnetic fields is consistent with the quasiperiodic, resonance-based predictions of the IPR model. We tested changes in each of the experimentally controllable variables [flux densities of the parallel components of the AC magnetic field (Bac) and the static magnetic field (Bdc) and the frequency of the AC magnetic field] over a range of exposure conditions sufficient to determine whether the IPR model is applicable. A multiple-coil exposure system independently controlled each of these critical quantities. The perpendicular static magnetic field was controlled to less than 2 mG for all tests. The first set of tests examined the NO response in cells exposed to 45 Hz Bac from 77 to 468 mG(rms) at a Bdc of 366 mG. Next, we examined an off-resonance condition using 20 mG Bdc with a 45 Hz AC field across a range of Bac between 7.9 and 21 mG(rms). Finally, we changed the AC frequency to 25 Hz, with a corresponding change in Bdc to 203 mG (to tune for the same set of ions as in the first test) and a Bac range from 78 to 181 mG(rms). In all cases the observed responses were consistent with predictions of the IPR model. These experimental results are the first to support in detail the validity of the fundamental relationships embodied in the IPR model. © 1994 Wiley-Liss, Inc.
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  • 8
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994) 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
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  • 9
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 275-282 
    ISSN: 0197-8462
    Keywords: EMF ; exposure assessment ; wire codes ; 60 Hz ; epidemiology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Wire codes, introduced by Wertheimer and Leeper as a surrogate for residential magnetic fields, divide imputed exposure into several categories based on the configurations of electrical wiring within 40 m of homes. Using the data set gathered by Savitz et al. in the Denver, Colorado, area of the United States, we determined which of the wiring attributes that contribute to Wertheimer-Leeper coding are actually associated with lowpower magnetic fields measured in bedrooms of subjects. The results led us to propose a considerably simplified three-category form of the Wertheimer-Leeper code that 1) drops the distinctions between thick and thin primary wires and between first-span and other secondary lines, 2) adds a new distinction between open (i.e., conductors not in physical contact) and spun secondaries, and 3) explains as much of the between-home variability in log-transformed bedroom fields as does the five categories of the original Wertheimer-Leeper code. The data necessary to classify residences using the modified code are considerably simpler to obtain and should lead to more reliable results. A separate reanalysis of the Denver data set of Savitz et al. shows that the modified code yields risk estimates that are both precise and markedly elevated for the highest exposure category, suggesting that this code may be useful in other studies. © 1994 Wiley-Liss, Inc.
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  • 10
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    Bioelectromagnetics 15 (1994), S. 283-291 
    ISSN: 0197-8462
    Keywords: electromagnetic field ; protein synthesis ; Escherichia coli ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Escherichia coli JM83 {F- ara Δ(lac-proAB) rpsL [φ80dΔ(lacZ)M15]} in midlog growth phase at 30 °C were exposed to 60 Hz sinusoidal magnetic field of 3 mT of nonuniform diverging flux, inducing a nonuniform electric field with a maximum intensity of 32 μV/cm using an inductor coil. Exposed and unexposed control cells were maintained at 30.8 ± 0.1 °C and 30.5 ± 0.1 °C, respectively. Quadruplicate samples of exposed and unexposed E. coli cells were simultaneously radiolabeled with 35S-L-methionine at 10 min intervals over 2 hr. Radiochemical incorporation into proteins was analyzed via liquid scintillation counting and by denaturing 12.5% polyacrylamide gel electrophoresis. The results showed that E. coli exposed to a 60 Hz magnetic field of 3 mT exhibited no qualitative or quantitative changes in protein synthesis compared to unexposed cells. Thus small prokaryotic cells (less than 2 μm × 0.5 μm) under constant-temperature conditions do not alter their protein synthesis following exposure to 60 Hz magnetic fields at levels at 3 mT. © 1994 Wiley-Liss, Inc.
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  • 11
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    Bioelectromagnetics 15 (1994), S. 293-301 
    ISSN: 0197-8462
    Keywords: sinusoidal ; weak ELF magnetic field ; cultured fetal cells ; clastogenic effect ; chromatid and chromosome gaps ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: 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.
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  • 12
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    Bioelectromagnetics 15 (1994), S. 315-328 
    ISSN: 0197-8462
    Keywords: cancer cells ; thermochemiluminescence ; dosimetry ; melanin ; microwave radiation ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Chemical and bacterial synthesis of a thermochemiluminescent polymer known as diazoluminomelanin (DALM) has been previously reported. This paper focuses on the intracellular synthesis of aminomelanin (AM) in mammalian cell lines and subsequent DALM synthesis from this core molecule. B16 melanoma cells, HL-60 myeloid leukemia cells, and RAW 264.7 macrophages show AM and DALM production. Macroscopic image analysis of HL-60 cell lysates containing DALM using the Quantitative Luminescence Imaging System (QLIS) showed increased chemiluminescence (CL) with increased microwave power input and increased temperature. This work represents a first step toward the goal of microscopic radiofrequency dosimetry of individual DALM-loaded cells using image analysis. © 1994 Wiley-Liss, Inc.
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  • 13
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    Bioelectromagnetics 15 (1994), S. 329-336 
    ISSN: 0197-8462
    Keywords: transcription ; translation ; SV-40 ; large T-antigen ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: In its integrated form, SV-40 DNA offers an opportunity to observe the behavior of what is in effect a viral genome within a cellular genome, with transcriptional and translational products that can be clearly distinguished from those of the host cell. Exposure of SV40-transformed human fibroblasts to a 60 Hz continuous-wave sinusoidal electromagnetic (EM) field resulted in increased levels of virally derived mRNA and protein of large T-antigen. These findings provide evidence that a foreign DNA integrated into cells can be affected by EM fields under conditions known to cause increased transcripts from endogenous cellular genes. © 1994 Wiley-Liss, Inc.
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  • 14
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    Bioelectromagnetics 15 (1994), S. 337-347 
    ISSN: 0197-8462
    Keywords: ELF magnetic fields ; exposure assessment ; epidemiology ; misclassification ; statistical power ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The development of a wire code protocol based on a study of electrical installations in Melbourne, Australia, is described. Because of very significant differences between the Melbourne power distribution system and that used in Denver, Colorado, an approach different from that used by Wertheimer and Leeper was required. A combined practical and theoretical approach was used to determine a continuous exposure index, defined as a measure of the potential for exposure due to external electrical installations. The protocol was tested on a convenient sample of 41 homes in which the field was monitored over a 12 hour overnight period. A correlation of 0.85 (95% CI 0.74-0.92, P 〈 .0001) was obtained between the measured time-weighted average and the wire coding exposure index. To assess the efficacy of the wiring configuration index, a computer simulation of a case-control study was then performed. It was concluded that, using the same basic reasoning of the Wertheimer and Leeper code, it is possible to develop a location-specific code that provides a good correlation with the residential time-weighted average and an acceptable degree of exposure misclassification. © 1994 Wiley-Liss, Inc.
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  • 15
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    Bioelectromagnetics 15 (1994), S. 539-547 
    ISSN: 0197-8462
    Keywords: electromagnetic fields ; signal-to-noise ratio ; stochastic resonance ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The most important but still unresolved problem in bioelectromagnetics is the interaction of weak electromagnetic fields (EMFs) with living cells. Thermal and other types of noise pose restrictions in cell detection of weak signals. As a consequence, some extant experimental results that indicate low-intensity field effects cannot be accounted for, and this renders the results themselves questionable. One way out of this dead end is to search for possible mechanisms of signal amplification. In this paper, we discuss a general mechanism in which a weak signal is amplified by system noise itself. This mechanism was discovered several years ago in physics and is known, in its simplest form, as a stochastic resonance. It was shown that signal amplification may exceed a factor of 1000, which renders existing estimations of EMF thresholds highly speculative. The applicability of the stochastic resonance concept to cells is discussed particularly with respect to the possible role of the cell membrane in the amplification process. © 1994 Wiley-Liss, Inc.
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  • 16
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    Bioelectromagnetics 15 (1994), S. 555-561 
    ISSN: 0197-8462
    Keywords: frog ; ventricular muscle ; conduction velocity ; 2,450 MHz ; microwave thermal effect ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Thirty-two frog hearts were divided into four groups and placed individually in temperature-controlled waveguides filled with Ringer's solution. The pacemaker was removed, and stimulation was provided at 0.3 Hz by three carbon-loaded Teflon electrodes located on the aorta and the ventricular muscle. Conduction velocity was measured from the difference between two action potentials. One group served as control; the three other groups were exposed for 2 h to pulsed 2,450 MHz microwave fields (10 μs, 0.001 duty cycle, 16 Hz modulation) at specific absorption rates (SARs) of 0.003, 2, and 6 W/kg, respectively. No significant difference in conduction velocity was found between the control and the exposed groups. © 1994 Wiley-Liss, Inc.
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  • 17
    ISSN: 0197-8462
    Keywords: ELF ; magnetic fields ; cyclotron resonance ; calcium transport ; potassium transport ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We have investigated the effects of sinusoidal electromagnetic fields (EMF) on ion transport (Ca2+, Na+, K+, and H+) in several cell types (red blood cells, thymocytes, Ehrlich ascites tumor cells, and HL60 and U937 human leukemia cells). The effects on the uptake of radioactive tracers as well as on the cytosolic Ca2+ concentration ([Ca2+]i), the intracellular pH (pHi), and the transmembrane potentsial (TMP) were studied. Exposure to EMF at 50 Hz and 100-2000 μT (rms) had no significant effects on any of these parameters. Exposure to EMF of 20-1200 μT (rms) at the estimated cyclotron magnetic resonance frequencies for the respective ions had no significant effects except for a 12-32% increase of the uptake of 42K within a window at 14.5-15.5 Hz and 100-200 μT (rms), which was found in U937 and Ehrlich cells but not in the other cell types. © 1994 Wiley-Liss, Inc.
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  • 18
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    Bioelectromagnetics 15 (1994), S. 589-591 
    ISSN: 0197-8462
    Keywords: dielectric measurement ; human blood ; age ; temperature ; permittivity ; conductivity ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Dielectric properties of human red blood cells (RBCs) in suspension (hematocrit 50%) from 243 healthy persons (120 males, 123 females) were measured at 25 °C in a frequency range of 1-500 MHz, with a coaxial transmission line reflection method (one-side measurement). The measuring system, controlled by an IBM-PC computer, was composed of a network analyzer (HP4195A), an impedance test adapter (HP41951-61001), a coaxial line sensor, and a temperature-controlling set. The data measured revealed a statistically significant age dependence, with a critical age of about 49 years, above which permittivity and conductivity of human RBCs in suspension decreased significantly. © 1994 Wiley-Liss, Inc.
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  • 19
    ISSN: 0197-8462
    Keywords: magnetic fields ; exposure system ; stray fields ; Merritt coils ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Exposure systems that provide good magnetic field uniformity, minimum stray fields, and minimal heating, vibration, and hum, as well as capability for true sham exposure in which current flows in the coils, are needed to determine rigorously the biological effects of weak magnetic fields. Designs based on acrylic polymer coil support structures and twisted pair bifilary coil windings were employed to fabricate several different systems for the exposure of laboratory animals and cell cultures to magnetic fields. These systems exhibit excellent performance characteristics in terms of exposure field uniformity, stray field containment, and exposure field cancellation in the sham exposure mode. A custom-written computer program was used to determine the best arrangement for coils with regard to field uniformity in the exposure volume and stray field containment. For in vivo exposures, modules were made up of four Merritt four-coil sets, built into a single structure and positioned to form an octapole with fields directed in the horizontal plane. For in vitro applications, two different coil configurations were selected to produce the vertical fields required. A quadrupole system, comprising modules consisting of two Merritt four-coil sets arranged side by side to limit stray fields, was built as a prototype. In the second configuration, one Merritt four-coil set was positioned inside the other to form a concentric coil set. In both in vitro systems, exposure chambers were connected to remote commercial incubators in order to reduce ambient magnetic fields in the exposure volume. An active field cancellation circuit was developed for reducing ambient AC magnetic fields in the in vitro sham exposure chamber, when necessary. These design and fabrication approaches provide systems that offer uniform field exposures and excellent stray field containment when needed and are portable, washable, and relatively inexpensive. © 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
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  • 20
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    Bioelectromagnetics 15 (1994), S. 593-597 
    ISSN: 0197-8462
    Keywords: magnetic fields ; AMEX ; average magnetic field exposure system ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Two types of dosimeters for measuring human exposure to 60 Hz magnetic fields were compared. Fifty adults wore the single-axis, wrist model AMEX (average magnetic field exposure system) and the triple axis, hip-pocket or pouch model AMEX-3D meters for 2 days. Ninety-six percent of the tests were accomplished without apparent dosimeter failure. The average root mean square magnetic flux density measurements with the AMEX3D (mean = 0.10 μT, S.D. = 0.07, range = 0.03 - 0.31) were significantly higher than with the AMEX meter (mean = 0.07 μT, S.D. 0.05, range = 0.02 - 0.27 μT) (t test, P 〈 0.01). There was substantial correlation between the AMEX and the AMEX-3D measurements (Pearson's correlation coefficient = 0.65, P 〈 0.01) but poor concordance (Intraclass correlation coefficient = - 0.25). These results suggest that there is a wide variation in exposure to extremely low frequency magnetic fields in the population. Magnetic field measurements with the AMEX-3D are nearly always higher than with the AMEX dosimeters. Caution is advised when comparing magnetic field measurements made with different types of dosimeters. © 1994 Wiley-Liss, Inc.
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  • 21
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    Bioelectromagnetics 15 (1994) 
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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  • 22
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    Bioelectromagnetics 15 (1994), S. 1-1 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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  • 23
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    Bioelectromagnetics 15 (1994), S. 1-2 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Bioelectromagnetics 15 (1994), S. 2-2 
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Bioelectromagnetics 15 (1994), S. 3-4 
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Bioelectromagnetics 15 (1994), S. 5-19 
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Bioelectromagnetics 15 (1994), S. 53-65 
    ISSN: 0197-8462
    Keywords: intermittents ; transients ; EMF ; electric power ; ground currents ; exposure assessment ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The current through the residential grounding circuit is an important source for magnetic fields; field variations near the grounding circuit accurately track fluctuations in this ground current. In this paper, a model is presented which permits calculation of the range of these fluctuations. A discrete network model is used to simulate a local distribution system for a single street, and a statistical model to simulate unbalanced currents in the system. Simulations of three-house and ten-house networks show that random appliance operation leads to ground current fluctuations which can be quite large, on the order of 600%. This is consistent with measured fluctuations in an actual house. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 21-32 
    ISSN: 0197-8462
    Keywords: ELF ; EMF ; exposure assessment ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Research that has attempted to examine the relationship between work exposures to magnetic fields and health effects has suffered from limited exposure information. Power-frequency electric and magnetic (EM) field exposures vary substantially between industries, occupations, and individuals. In this study magnetic field data were collected for a variety of occupational categories within an electric utility. The sampling procedures emphasized craft occupations that were presumed to have higher exposures to magnetic fields. The objectives were to provide better exposure information for an ongoing cancer mortality study, examine the relationship between different summary measures of magnetic field exposure, and make available descriptive information useful for exposure reduction and worker education. Principal components analysis (PCA) and Varimax rotation were used to explore the relationships between the different summary measures among all utility workers and among the subset of electrical craft occupations. Discriminant analysis was used to assess summary measures of exposure that differentiated occupational groups. Measurements for 770 days generated a total of 42378 hours of magnetic field data. Eleven summary indices of exposure were calculated for specific occupational groups. These include arithmetic mean, geometric mean, median, 95th and 99th percentiles, and fraction of measurements exceeding .5, 1, 5, 10, and 100 μT. Electrical craft occupations had higher work exposures than non-craft occupations. Electricians and substation operators had the highest exposures among craft occupations.We identified subsets of summary measures that were intercorrelated. The first PCA axis included the geometric mean, median, and the fractions exceeding 0.5 and 1.0 μT. This set of measures also were best at discriminating occupational groups. The relevance of these findings may become more important if consistent associations are found between particular occupations and disease and particular occupations and magnetic field summary measures. Further research is needed to evaluate these exposure assessment findings. © 1994 Wiley-Liss, Inc.
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    ISSN: 0197-8462
    Keywords: exposure assessment ; environmental magnetic fields ; residential magnetic fields ; epidemiological protocol ; wire codes ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Notes: A study was carried out in 1990 to guide the development of a protocol for assessing residential exposures of children to time-weighted-average (TWA) power-frequency magnetic fields. The principal goal of this dosimetry study was to determine whether area (i.e., spot and/or 24 h) measurements of power-frequency magnetic fields in the residences and in the schools and daycare centers of 29 children (4 months through 8 years of age) could be used to predict their measured personal 24-h exposures. TWA personal exposures, measured with AMEX-3D meters worn by subjects, were approximately log-normally distributed with both residential and nonresidential geometric means of 0.10 μT (1.0 mG). Between-subjects variability in residential personal exposure levels (geometric standard deviation of 2.4) was substantially greater than that observed for nonresidential personal exposure levels (1.4). The correlation between log-transformed residential and total personal exposure levels was 0.97. Time-weighted averages of the magnetic fields measured in children's bedrooms, family rooms, living rooms, and kitchens were highly correlated with residential personal exposure levels (r = 0.90). In general, magnetic field levels measured in schools and daycare centers attended by subjects were smaller and less variable than measured residential fields and were only weakly correlated with measured nonresidential personal exposures. The final measurement protocol, which will be used in a large US study examining the relationship between childhood leukemia and exposure to magnetic fields, contains the following elements: normal- and low-power spot magnetic field measurements in bedrooms occupied by subjects during the 5 years prior to the date of diagnosis for cases or the corresponding date for controls; spot measurements under normal and low power-usage conditions at the centers of the kitchen and the family room; 24-h magnetic-field recordings near subjects' beds; and wire coding using the Wertheimer-Leeper method. © 1994 Wiley-Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.
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    Bioelectromagnetics 15 (1994), S. 115-131 
    ISSN: 0197-8462
    Keywords: tissue culture ; energy efficient device ; DNA synthesis ; frequency spectrum ; collagen production ; collagen synthesis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: An energy efficient electromagnetic stimulator device for fracture healing was compared to a commercially available device in stimulating cell growth in tissue cultures. The energy efficient device, which conserves energy by using a bidirectional time-dependent magnetic wave form, and the commercially available stimulator, which uses a unidirectionaltime-dependent magnetic wave form, were tested on chick tendon fibroblasts in primary culture. Comparing non-stimulated control and cells electromagnetically stimulated with unidirectional and bidirectional waveforms showed that at the growth phase between days 2 and 3, both electrical stimulation techniques increased cell division as measured by DNA synthesis. When cells were dividing rapidly, collagen synthesis was reduced. When the cells reached the confluence there was no difference among the groups (control, unidirectionally stimulated, and bidirectionally stimulated) in terms of number of cells or collagen produced. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 143-161 
    ISSN: 0197-8462
    Keywords: high peak power microwaves ; response latency ; subcutaneous temperature ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: Microwave evoked body movements were studied in mice. A resonant cavity was used to provide head and neck exposure of the mouse to pulsed and gated continuous wave (CW) 1.25 GHz microwaves. No difference in response to pulsed and gated CW stimuli of equal average power was found. The incidence of the microwave evoked body movements increased proportionally with specific absorption (dose) when the whole-body average specific absorption rate was at a constant level (7300 W/kg). Under a constant average specific absorption rate, the response incidence reached a plateau at 0.9 kJ/kg. For doses higher than 0.9 kJ/kg, response incidence was proportional to the specific absorption rate and reached a plateau at 900 W/kg. Body movements could be evoked by a single microwave pulse. The lowest whole-body specific absorption (SA) tested was 0.18 kJ/kg, and the corresponding brain SA was 0.29 kJ/kg. Bulk heating potentials of these SAs were less than 0.1 °C. For doses higher than 0.9 kJ/kg, the response incidence was also proportional to subcutaneous temperature increment and subcutaneous heating rate. The extrapolated absolute thresholds (0% incidence) were 1.21 °C temperature increment and 0.24 °C/s heating rate. Due to high subcutaneous heating rates, these microwaves must be perceived by the mouse as an intense thermal sensation but not a pain sensation because the temperature increment was well below the threshold for thermal pain. Results of the present study should be considered in promulgation of personnel protection guideline against high peak power but low average power microwaves. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 411-426 
    ISSN: 0197-8462
    Keywords: operant conditioning ; Pavlovian conditioning ; magnetic field ; detection ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: Work in our laboratory has revealed autonomic and/or behavioral sensitivity of mice, rats, and a domestic fowl to extremely-low-frequency (ELF) or nominally static magnetic (B) fields at flux densities between 250 and 1700 μT (rms). To extend our work, an automated exposure and data-acquisition system was used with the technique of conditional suppression to assess behavioral sensitivity to time-varying B fields. Each of five rats was exposed aperiodically to a B field during 3 min warning periods that terminated in a brief electric shock. The difference between rates of lever pressing during B-field warning periods and rates during immediately antecedent, 3 min control periods was analyzed at frequencies of 7, 16, 30, 60, and 65.1 Hz. To produce equivalent induced voltages in the rat at each frequency, graded flux densities were established that ranged from 1900 μT at 7 Hz to 200 μT at 65.1 Hz. Analysis of differences in lever-pressing rates revealed that in a given session of testing the rats would increasingly suppress responding when exposed to a B field, but this trend was independent of frequency. This experiment provides evidence of behavioral sensitivity by a mammal to an ELF magnetic field. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 439-446 
    ISSN: 0197-8462
    Keywords: magnetic field ; electric appliances ; time-weighted average exposure ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: Flux density and spectral measurements were carried out on magnetic fields generated by several types of motor-driven personal appliances used near the body. Among the units tested were several for which the average flux densities, as determined at the surfaces of the appliance, exceeded 0.4 mT. Time-rates-of-change (dB/dt) for several units exceeded 1000 T/s, and several units exhibited high-frequency components in the low-MHz range. Use of such appliances, although normally of short duration, can represent exposure to magnetic fields of relatively high flux density, which may also have high-frequency components. Compared to other household and commercial sources of magnetic fields, those generated by certain motor-driven personal appliances may represent a significant contribution to time-weighted average exposure and may represent an important source of local induced currents in the body. Furthermore, high-frequency transients that represent only a minor contribution to time-weighted average exposure may generate significant instantaneous induced currents. © 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
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    Bioelectromagnetics 15 (1994), S. 447-463 
    ISSN: 0197-8462
    Keywords: ELF ; EMF ; humans ; physiology ; performance ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: This human exposure study examined the relationship between field strength and biological response and tested whether the exposure levels at which the greatest effects occur differ for different endpoints. Three matched groups of 18 men each participated in two 6 h exposure test sessions. All subjects were sham exposed in one session. In the other session, each group of subjects was exposed at a different level of combined electric and magnetic field strength (low group: 6 kV/m, 10 μT; medium group: 9 kV/m, 20 μT; and high group: 12 kV/m, 30 μT). The study was performed double blind, with exposure order counterbalanced. Significant slowing of heart rate, as well as alterations in the latency and amplitude of event-related brain potential measures derived from the electro encephalogram (EEG), occurred in the group exposed to the 9 kV/m, 20 μT combined field (medium group). Exposure at the other field strength levels had no influence on cardiac measures and differential effects on EEG activity. Significant decrements in reaction time and in performance accuracy on a time estimation task were observed only in the low group. These results provide support for the hypothesis that humans may be more responsive to some combinations or levels of field strength than to others and that such differences in responsivity may depend, in part, on the endpoint of interest. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 465-482 
    ISSN: 0197-8462
    Keywords: dosimetry ; bone remodeling ; ELF ; electric fields ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A commercially available spreadsheet program is used on a microcomputer to calculate the induced current density and electric field patterns produced in a nonhomogeneous, anisotropic model of tissue by a localized, low-frequency magnetic field source. Specific application is made to coils used to promote the healing of bone fractures in limbs. The variation of the conductivity of the fracture gap during healing causes the induced current density pattern to change correspondingly, whereas the induced electric field remains relatively unchanged. Use of more simplified, isotropic models for the bone and for the soft tissue leads to results that differ significantly from those obtained from the full model. The magnetic field beyond the region of the coils contributes little to the induced currents in the fracture gap if the gap is located near the center of the coils. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 493-493 
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    ISSN: 0197-8462
    Keywords: Wistar-King rats ; circularly polarized magnetic field ; long-term exposure ; recovery process ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Notes: In our earlier paper [Kato et al. (1993): Bioelectromagnetics 14:97-106], melatonin concentration in pineal gland and blood was reported to be suppressed after exposure to a circularly polarized 50 Hz magnetic field for 6 weeks. In the present series of experiments, we investigated the time course of recovery after cessation of the exposure. Rats were exposed to a circularly polarized 50 Hz magnetic field at 1 μT for 6 weeks, and the melatonin concentration of blood of separate groups was determined at the end of the exposure and at 1 week and 4 weeks following cessation of exposure. Nocturnal melatonin concentration was reduced (P 〈 0.05) after 6 weeks of exposure. Melatonin concentration at 1 week following cessation of exposure was normal, and no further change was observed 4 weeks later. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 495-501 
    ISSN: 0197-8462
    Keywords: static field ; bioeffects ; growth rate ; S. cerevisiae ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We have used a clinical magnetic resonance imager to search for the possible effects of a 1.5 T magnetic fields on the growth of the yeast Saccharomyces cerevisiae. Yeast samples were grown in nutrient broth contained in constant-temperature boxes, both in and out of the magnetic field of the imager. Growth was measured by using a hemocytometer and light microscope to calculate cell densities. Over the time span corresponding to approximately seven cell divisions, we find no convincing statistical evidence for an effect of magnetic field on cell density. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 261-270 
    ISSN: 0197-8462
    Keywords: ELF fields ; magnetite ; thermal noise ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: Adair [Bioelectromagnetics 14:1-4, 1993] writes that “the effects of 60 Hz magnetic fields of 5 μT (50 mG) or less on biological structures holding magnetite (Fe3O4) are shown to be much smaller than those from thermal agitation; hence such interactions cannot be expected to be biologically significant.” This conclusion is questioned, because it appears to be based on a model that probably has very limited validity for pertinent biological systems. Furthermore, biologically plausible parameters can be selected to show that even this particular model does not exclude biologically significant effects of 60 Hz magnetic fields below 5 μT. Reported experimental results indicate effects in mammals of 50 Hz fields at the 1 μT level. © 1994 Wiley-Liss, Inc.
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    ISSN: 0197-8462
    Keywords: behavioral teratology ; power frequency fields ; rodents ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: To investigate the potential of magnetic fields to act as a behavioral teratogen, pregnant CD1 mice were exposed or sham-exposed for all of gestation to a 50 Hz/20 mT magnetic field. Maturation of offspring was assessed using a range of standard developmental indices (eye opening, pinna detachment, hair coat, tooth eruption, sexual maturity, and weight) and simple reflexive behaviors (air righting, surface righting, forepaw grasp, cliff avoidance, and negative geotaxis). Activity and coordination levels were explored in juvenile and adult mice using an open field arena, a head-dip board, an accelerating Rotarod, and a residential activity wheel. All assessments were carried out without knowledge of exposure condition. Results from 168 sham-exposed mice from 21 litters and from 184 exposed mice from 23 litters were compared using survival analysis techniques and multivariate regression methods. Three possible field-dependent effects were found: Exposed animals performed the air righting reflex earlier (P 〈 0.01); exposed males (but not females) were significantly lighter in weight (P = 0.008) at 30 days of age; and exposed animals remained on a Rota-rod for less time as juveniles (P = 0.03). Some of these results have not been reported in other studies and may reflect spurious statistical significance, although some effect of magnetic field exposure cannot be ruled out. Overall, these results suggest that prenatal exposure to a 50 Hz magnetic field does not engender any gross impairments in the postnatal development or behavior of mice. This does not preclude such exposure affecting more subtle aspects of behavior. Published 1994 by Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 377-383 
    ISSN: 0197-8462
    Keywords: radiofrequency radiation ; amplitude modulation ; ELF ; 16 Hz ; 60 Hz ; modulation ; enolase activity ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: Some neurochemical effects of low-intensity electric and magnetic fields have been shown to be nonlinear functions of exposure parameters. These effects occurred within narrow ranges of frequency and intensity. Previous studies on membrane-associated endpoints in cell culture preparations demonstrated changes in calcium efflux and in acetylcholinesterase activity following exposure to radiofrequency radiation, amplitude modulated (AM) at 16 and at 60 Hz, at a specific absorption rate of 0.05 W/kg. In this study, these modulation frequencies were tested for their influence on the activity of a cytoplasmic enzyme, enolase, which is being tested clinically for detection of neoplasia. Escherichia coli cultures containing a plasmid with a mammalian gene for enolase were exposed for 30 min, and cell extracts were assayed for enolase activity by measuring absorbance at 240 nm. The enolase activity in exposed cultures was compared to the activity in paired control cultures. Exposure to 147 MHz carrier waves at 0.05 W/kg, AM at 16 Hz showed enolase activity enhanced by 62%, and AM at 60 Hz showed enolase activity reduced by 28%. Similarly, exposure to 16 Hz fields alone, at 21.2 V/mrms (electric) and 97 nTrms (magnetic), showed enhancement in enolase activity by 59%, whereas exposure to 60 Hz fields alone, at 14.1 V/mrms (electric) and 65 nTrms (magnetic), showed reduction in activity by 24%. Sham exposures as well as exposure to continuous-wave 147 MHz radiation at 0.05 W/kg showed no change in enolase activity. Although the underlying basis for these field effects in the cytoplasmic compartment has not been established, differential sensitivities to 16 Hz and to 60 Hz signals provide a clear focus for additional research to determine the responsible mechanism. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 427-437 
    ISSN: 0197-8462
    Keywords: electric field exposure ; electromagnetic fields ; pineal function ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Topics: Biology , Physics
    Notes: Sprague-Dawley male rats, maintained in a 14:10 h light:dark cycl were exposed for 30 days (starting at 56 days of age) to a 65 kV/m, 60 Hz electric field or to a sham field for 20 h/day beginning at dark onset. Pineal N-acetyltransferase (NAT), hydroxy-indole-o-methyl transferase (HIOMT), and melatonin as well as serum melatonin were assayed. Preliminary data on unexposed animals indicated that samples obtained 4 h into the dark period would reveal either a phase delay or depression in circadian melatonin synthesis and secretion. Exposure to electric fields for 30 days did not alter the expected nighttime increase in pineal NAT, HIOMT, or melatonin. Serum melatonin levels were also increased at night, but the electric field-exposed animals had lower levels than the sham-exposed animals. Concurrent exposure to red light and the electric field or exposure to the electric field at a different time of the day-night period did not reduce melatonin synthesis. These data do not support the hypothesis that chronic electric field exposure reduces pineal melatonin synthesis in young adult male rats. However, serum melatonin levels were reduced by electric field exposure, suggesting the possibility that degradation or tissue uptake of melatonin is stimulated by exposure to electric fields. © 1994 Wiley-Liss, Inc.
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    ISSN: 0197-8462
    Keywords: nonionizing fields ; teratogenic effects ; signal waveform ; pulsed magnetic fields ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Several reports have shown that weak, extremely-low-frequency (ELF), pulsed magnetic fields (PMFs) can adversely affect the early embryonic development of the chick. In this study, freshly fertilized chicken eggs were exposed during the first 48 h of postlaying incubation to PMFs with 100 Hz repetition rate, 1.0 μT peak-to-peak amplitude, and 500 μs pulse duration. Two different pulse waveforms were used, having rise and fall times of 85 μs (PMF-A) or 2.1 μs (PMF-B). It has been reported that, with 2 day exposure, these fields significantly increase the proportion of developmental abnormalities. In the present study, following exposure, the eggs were allowed to incubate for an additional 9 days in the absence of the PMFs. The embryos were taken out of the eggs and studied blind. Each of the two PMF-exposed groups showed an excess in the percentage of developmental anomalies compared with the respective sham-exposed samples. This excess of anomalies was not significant for the PMF-A-treated embryos (P = 0.173), whereas it was significant for the PMF-B-exposed group (P = 0.007), which showed a particularly high rate of early embryonic death. These results reveal that PMFs can induce irreversible developmental alterations and confirm that the pulse waveform can be a determinant factor in the embryonic response to ELF magnetic fields. The data also validate previous work based on the study of PMFs' effects at day 2 of embryonic development under field exposure. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 399-409 
    ISSN: 0197-8462
    Keywords: noise ; coherence ; incoherence ; signal to noise ; ornithine decarboxylase ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We have previously demonstrated that a weak, extremely-low-frequency magnetic field must be coherent for some minimum length of time (≍ 10 s) in order to affect the specific activity of ornithine decarboxylase (ODC) in L929 mouse cells. In this study we explore whether or not the superposition of an incoherent (noise) magnetic field can block the bioeffect of a coherent 60 Hz magnetic field, since the sum of the two fields is incoherent. An experimental test of this idea was conducted using as a biological marker the twofold enhancement of ODC activity found in L929 murine cells after exposure to a 60 Hz, 10 μTrms magnetic field. We superimposed an incoherent magnetic noise field, containing frequencies from 30 to 90 Hz, whose rms amplitude was comparable to that of the 60 Hz field. Under these conditions the ODC activity observed after exposure was equal to control levels. It is concluded that the superposition of incoherent magnetic fields can block the enhancement of ODC activity by a coherent magnetic field if the strength of the incoherent field is equal to or greater than that of the coherent field. When the superimposed, incoherent noise field was reduced in strength, the enhancement of ODC activity by the coherent field increased. Full ODC enhancement was obtained when the rms value of the applied EM noise was less than one-tenth that of the coherent field. These results are discussed in relation to the question of cellular detection of weak EM fields in the presence of endogenous thermal noise fields. © 1994 Wiley-Liss, Inc.
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Bioelectromagnetics 15 (1994), S. 163-176 
    ISSN: 0197-8462
    Keywords: pulsed microwaves ; Rhesus monkey ; behavior ; high-peak-power ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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    Notes: Limits on the exposure to high-peak-power, short-duration microwave pulses have only recently been adopted. Additional data, however, are needed to understand the effects that may be produced by exposure to high-peak-power pulsed microwaves. Four male rhesus monkeys (Macaca mulatta) were trained on an operant task for food pellet reward to investigate the behavioral effects of very high-peak-power 5.62 GHz microwaves. The operant task required monkeys to pull one plastic lever on a variable interval schedule (VI-25 s) and then respond to color signals and pull a second lever to obtain food. The monkeys were conditioned to perform a color discrimination task using one of three colors displayed by a fiber-optic cable. A red signal was the discriminative stimulus for responding on the first lever. A response on the second lever when a green signal was presented (1 s duration) delivered a food pellet. If a response on the second lever was made in the presence of a white signal, a 30-s timeout occurred. While performing the behavioral task, the monkeys were exposed to microwave pulses produced by either a military radar (FPS-26A) operating at 5.62 GHz or the same radar coupled to a Stanford linear energy doubler (SLED) pulse-forming device (ITT-2972) that enhanced peak power by a factor of nine by adding a high power pulse to the radar pulse. The effects of both types of pulses were compared to sham exposure. Peak field power densities tested were 518, 1270, and 2520 W/cm2 for SLED pulses and 56, 128, and 277 W/cm2 for the radar pulses. The microwave pulses (radar or SLED) were delivered at 100 pps (2.8 μs radar pulse duration, ≈ 50 ns SLED pulse duration) for 20 min and produced averaged whole-body SARs of 2,4, or 6 W/kg. Compared to sham exposures, significant alterations of lever responding, reaction time, and earned food pellets occurred during microwave exposure at 4 and 6 W/kg but not 2 W/kg. There were no differences between radar or SLED pulses in producing behavioral effects. ©1994 Wiley-Liss, Inc.This is a US Government work and, as such, is in the public domain in the United States of America.
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  • 48
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    Bioelectromagnetics 15 (1994), S. 177-181 
    ISSN: 0197-8462
    Keywords: CW microwaves ; mice ; longevity ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Female CD 1 mice were exposed from the thirty-fifth day of age for the remainder of their lives to 2.45 GHz, CW-microwave radiation at a power density of 3 or 10 m W/cm2 (SAR = 2.0 or 6.8 W/kg). Exposures took place 1 h/day, 5 day/week in an anechoic chamber at an ambient temperature of 22 °C and a relative humidity of 50%. There were 25 animals in each exposure group, and an equal number of controls were concurrently sham exposed. The average life span of animals exposed at 10 mW/cm2 was significantly shorter than that of sham-exposed controls (572 days vs. 706 days; P = .049; truncation 〉20%). In contrast, the average lifespan of the animals exposed at 3 mW/cm2 was slightly, but not significantly, longer (738 days) than that of controls (706 days). © 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
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  • 49
    ISSN: 0197-8462
    Keywords: power frequency fields ; ELF magnetic fields ; teratology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Pregnant CD1 mice were exposed or sham-exposed from day 0 to day 17 of gestation to a 50 Hz sinusoidal magnetic field at 20 mT (rms). Preimplantation and postimplantation survival were assessed and fetuses examined for the presence of gross external, internal, and skeletal abnormalities. There were no statistically significant field-dependent effects on preimplantation or postimplantation survival, sex ratio, or the incidence of fetuses with internal or skeletal abnormalities. Magnetic field exposure was, however, associated with longer and heavier fetuses at term, with fewer external abnormalities. The results lend no support to suggestions of increased rates of spontaneous abortion or congenital malformation following prenatal exposure to power frequency magnetic fields. © 1994 Wiley-Liss, Inc.
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  • 50
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    Bioelectromagnetics 15 (1994) 
    ISSN: 0197-8462
    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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  • 51
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    Bioelectromagnetics 15 (1994), S. 183-192 
    ISSN: 0197-8462
    Keywords: microwaves ; receptors ; protein shedding ; peroxidation ; lipids ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The effects of a continuous wave or pulse-modulated, 900 MHz microwave field were studied by in vitro assays of rat chemoreceptors. The pulsed field was modulated as rectangular waves at rates of 1, 6, 16, 32, 75, or 100 pps. The pulse-period to pulse-duration ratio was 5 in all cases, and specific absorption rates (SARs) ranged from 0.5 to 18 W/kg. Binding of ligands to cell membranes was differentially affected by exposure to microwaves. For example, binding of H3-glutamic acid to hippocampal cells was not altered by a 15 min exposure to a continuous wave field at 1 W/kg, but binding of H3-dihydroalprenolol to liver-cell membranes of neonates underwent a fivefold decrease under the same field conditions. This effect was not dependent on modulation or on a change in the constant of stimulus-receptor binding but depended on a shedding of the membrane's receptor elements into solution. The magnitude of inhibition correlated with the oxygen concentration in the exposed suspension. Antioxidants (dithiothreitol and ionol) inhibited the shedding of receptor elements. The microwave exposure did not cause an accumulation of products from the peroxidation of lipids (POL). Ascorbate-dependent or non-enzymatic POL was not responsible for the inhibition, and POL was not found in other model systems. However, enzymatic POL mechanisms in localized areas of receptor binding remain a possibility. © 1994 Wiley-Liss, Inc.
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  • 52
    ISSN: 0197-8462
    Keywords: exposure indices ; epidemiology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Power-frequency electric and magnetic fields are known to exhibit marked temporal variation, yet in the absence of clear biological indications, the most appropriate summary indices for use in epidemiologic studies are unknown. In order to assess the statistical patterns among candidate indices, data on 4383 worker-days for magnetic fields and 2082 worker-days for electric fields collected for the Electric and Magnetic Field Project for Electric Utilities using the EMDEX meter [Bracken (1990): Palo Alto, CA: Electric Power Research Institute] were analyzed. We examined correlations at the individual and job title group levels among indices of exposure to both electric and magnetic fields, including the arithmetic mean, geometric mean, median, 20th and 90th percentiles, time above lower cutoffs of 20 V/m and 0.2 μT, and time above higher cutoffs of 100 V/m and 2.0 μT. For both electric and magnetic fields, the arithmetic mean was highly correlated with the 90th percentile; moderately correlated with the geometric mean, median, and lower and higher cutoff scores; and weakly correlated with the 20th percentile. Electric and magnetic field indices were generally weakly correlated with one another. Rank-order correlation coefficients were consistently greater than product-moment correlation coefficients. Job title group summary scores showed higher correlations among electric field indices and magnetic field indices and between electric and magnetic field indices than was found for individual worker-days, with only the 20th percentile clearly independent of the others. These results suggest that individuals' exposures are adequately characterized by a measure of central tendency for electric and magnetic fields, such as the arithmetic or geometric mean, and an indicator of a lower threshold or cutoff for each field type, such as the 20th percentile or proportion of time above 20 V/m or 0.2 μT. A single measure of central tendency for each type of field appears to be adequate when exposures are assessed at the job title level. © 1994 Wiley-Liss, Inc.
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  • 53
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    Bioelectromagnetics 15 (1994), S. 205-216 
    ISSN: 0197-8462
    Keywords: PEMF ; stroke ; MRI ; somatosensory evoked potentials ; cerebrovascular disease ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: There is evidence that electromagnetic stimulation may accelerate the healing of tissue damage following ischemia. We undertook this study to investigate the effects of low frequency pulsed electromagnetic field (PEMF) exposure on cerebral injury in a rabbit model of transient focal ischemia (2 h occlusion followed by 4 h of reperfusion). PEMF exposure (280 V, 75 Hz, IGEA Stimulator) was initiated 10 min after the onset of ischemia and continued throughout reperfusion (six exposed, six controls). Magnetic resonance imaging (MRI) and histology were used to measure the degree of ischemic injury. Exposure to pulsed electromagnetic field attenuated cortical ischemic edema on MRI at the most anterior coronal level by 65% (P 〈 0.001). On histologic examination, PEMF exposure reduced ischemic neuronal damage in this same cortical area by 69% (P 〈 0.01) and by 43% (P 〈 0.05) in the striatum. Preliminary data suggest that exposure to a PEMF of short duration may have implications for the treatment of acute stroke. © 1994 Wiley-Liss, Inc.
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  • 54
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    Bioelectromagnetics 15 (1994), S. 503-512 
    ISSN: 0197-8462
    Keywords: physiological effects ; occupational exposure ; electrical workers ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: This investigation studied the effects of 50 Hz electric and magnetic fields on the pulse rate of the human heart. The ECG (electrocardiograms) of 41 male volunteers were recorded with a Holter recorder. Twenty-six subjects were measured in and outside real fields, and 15 subjects were measured in and outside “sham” fields. The blood pressure and EEG (electroencephalogram) were also measured, but this article presents only the results of ECG recordings. The measurements took 3 h. The subjects were first sitting for 1 h outside the fields, then 1 h in the real or “sham” fields, and then, again, 1 h outside the fields. The electric field strength varied from 3.5 to 4.3 kV/m and the magnetic flux density from 1.4 to 6.6 μT. An analysis of the ECG recordings showed that the subjects' pulse rates were the same in and outside the fields. No response occurred when the subjects were exposed to real or “sham” fields. © 1994 Wiley-Liss, Inc.
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  • 55
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    Bioelectromagnetics 15 (1994), S. 303-313 
    ISSN: 0197-8462
    Keywords: microwaves ; Liposome ; permeability changes ; enzyme ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The influence of 2.45 GHz microwave exposure (6 mW/g) on the diffusion processes in enzyme-loaded unilamellar liposomes as bioreactors was studied. The enzyme carbonic anhydrase (CA) was entrapped into cationic unilamellar vesicles. Previous kinetic experiments showed a very low self-diffusion rate of the substrate p-nitrophenyl acetate (PNPA) across intact liposome bilayer. A twofold increase in the diffusion rate of PNPA through the lipid bilayer was observed after 120 min of microwave radiation compared to temperature control samples. The microwave effect was time dependent. The enzyme activity, as a function of increased diffusion of PNPA, rises over 120 min from 22.3% to 80%. The increase in stearylamine concentration reduces the enzyme activity from 80% to 65% at 120 min. No enzyme leakage was observed. © 1994 Wiley-Liss, Inc.
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  • 56
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    Bioelectromagnetics 15 (1994), S. 67-75 
    ISSN: 0197-8462
    Keywords: EEG ; electroencephalography ; LEET ; electromagnetic fields ; sleep ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The sleep inducing effect of a 15 min treatment with either an active or an inactive Low Energy Emission Therapy (LEET) device emitting amplitude-modulated electromagnetic (EM) fields was investigated in a double-blind cross-over study performed on 52 healthy subjects. All subjects were exposed to both active and inactive LEET treatment sessions, with an interval of at least I week between the two sessions. LEET consists of 27.12 MHz amplitude-modulated (sine wave) EM fields emitted intrabuccally by means of an electrically conducting mouthpiece in direct contact with the oral mucosa. The estimated local peak SAR is less than 10 W/kg in the oral mucosa and 0.1 to 100 mW/kg in brain tissue. No appreciable sensation is experienced during treatment, and subjects are therefore unable to tell whether they are receiving an active or an inactive treatment. In this study the active treatment consisted of EM fields intermittently amplitude-modulated (sine wave) at 42.7 Hz for 3 s followed by a pause of 1 s during which no EM fields were emitted. During the inactive treatment no EM fields were emitted. Baseline EEGs were obtained and 15 min post-treatment EEGs were recorded and analyzed according to the Loomis classification.A significant decrease (paired t test) in sleep latency to stage B2 (-1.78 ± 5.57 min, P = 0.013), and an increase in the total duration of stage B2 (1.15 ± 2.47 min, P = 0.0008) were observed on active treatment as compared with inactive treatment. The deepest sleep stage achieved (B1 to D) following active treatment was also significantly higher than that following inactive treatment (P = 0.040). We conclude 27.12 MHz electromagnetic fields, intermittenly amplitude-modulated at 42.7 Hz, result in a significant sleep inducing effect in healthy subjects. © 1994 Wiley-Liss, Inc.
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  • 57
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    Bioelectromagnetics 15 (1994), S. 77-83 
    ISSN: 0197-8462
    Keywords: pulsed magnetic fields ; PMF ; 2-D PAGE ; protein translation ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Quantitative two-dimensional gel electrophoresis of proteins in E. coli exposed for 60 min to weak, pulsed magnetic fields (1.5 mT peak) show that numerous proteins are both increased and decreased by a factor of 2 or more. An increase in the levels of two proteins, the a subunit of DNA-dependent RNA polymerase and NusA, was confirmed by Western blot analysis. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994) 
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    Keywords: Life and Medical Sciences ; Occupational Health and Environmental Toxicology
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  • 59
    ISSN: 0197-8462
    Keywords: azide ; mutagenicity ; magnetic fields ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Forty-eight hours exposure to a two Gauss (0.2 mT) rms 60 Hz time varying sinusoidal electromagnetic field increased the number of azide induced TA100 revertant colonies of Salmonella typhimurium 14% as compared with controls in the ambient 〈 2 milli-Gauss 60 Hz field. In the absence of the electromagnetic field, the numbers of mutant colonies grown within and outside the non-energized coil were nearly identical. Without azide, the number of “spontaneous” mutant colonies forming in the experimental field was not statistically significant from numbers of colonies not exposed to field effects. Experimental temperature variation of 2 °C had little effect on colony formation, and the enhanced production of revertant colonies in the presence of the magnetic field was maintained during continued culture for 5 additional days. © 1994 Wiley-Liss, Inc.
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    Bioelectromagnetics 15 (1994), S. 95-104 
    ISSN: 0197-8462
    Keywords: microwaves ; radial-arm maze ; learning ; memory ; cholinergic systems ; endogenous opioids ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: After 45 min of exposure to pulsed 2450 MHz microwaves (2 μsec pulses, 500 pps, 1 mW/cm2, average whole body SAR 0.6 W/kg), rats showed retarded learning while performing in the radial-arm maze to obtain food rewards, indicating a deficit in spatial “working memory” function. This behavioral deficit was reversed by pretreatment before exposure with the cholinergic agonist physostigmine or the opiate antagonist naltrexone, whereas pretreatment with the peripheral opiate antagonist naloxone methiodide showed no reversal of effect. These data indicate that both cholinergic and endogenous opioid neurotransmitter systems in the brain are involved in the microwave-induced spatial memory deficit. © 1994 Wiley-Liss, Inc.
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  • 61
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    Bioelectromagnetics 15 (1994), S. 271-273 
    ISSN: 0197-8462
    Keywords: electromagnetic fields ; low birth weight ; pregnancy ; preterm delivery ; spontaneous abortion ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The relationship of measured residential magnetic fields and wire codes to pregnancy outcome was examined in data collected for a study of childhood cancer in Denver. Pregnancies in homes with measured fields above 0.2 μT or high wire codes were not more likely to end in miscarriage, low birth weight, or preterm delivery. Lack of data on potential confounders and small numbers of cases limit the study's conclusions. © 1994 Wiley-Liss, Inc.
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  • 62
    ISSN: 0197-8462
    Keywords: noise ; cooperativity ; signal-to-noise ; embryo development ; abnormalities ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Living cells exist in an electrically noisy environment. This has led to the so-called “signal-to-noise” problem whereby cells are observed to respond to extremely-low-frequency (ELF) exogenous fields that are several orders of magnitude weaker than local endogenous fields associated with thermal fluctuations. To resolve this dilemma, we propose that living cells are affected only by electromagnetic fields that are spatially coherent over their surface. The basic idea is that a significant number of receptors must be simultaneously and coherently activated (biological cooperativity) to produce effects on the biochemical functioning of the cell. However, like all physical detection systems, cells are subject to the laws of conventional physics and can be confused by noise. This suggests that a spatially coherent but temporally random noise field superimposed on a coherent ELF signal will defeat the mechanism of discrimination against noise, and any observed field-induced bioeffects would be suppressed. An experimental test of this idea was conducted using morphological abnormalities in developing chick embryos caused by electromagnetic field exposure as the endpoint. At an impressed noise amplitude comparable to the ELF field strength (but roughly one-thousandth of the thermal noise field), the increased abnormality rate observed with only the ELF field present was reduced to a level essentially the same as for the control embryos. © 1994 Wiley-Liss, Inc.
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  • 63
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    Bioelectromagnetics 15 (1994), S. 133-142 
    ISSN: 0197-8462
    Keywords: magnetic field ; neuron ; conductance ; cell volume ; Ca ; water of hydration ; cyclic nucleotide ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Calcium chloride and snail physiological salt solutions were exposed to static magnetic fields (2.3-350 mT), and the physical properties of the solutions as well as their biologic effects were studied. Our preliminary observations show that these fields alter physicochemical properties of CaCl2 solutions and the functional effects of physiological solutions. Experiments on CaCl2 solutions demonstrated field-dependent changes of electrical conductivity, with the magnitude and the direction of conductivity change being a function of both concentration and field intensity. The changes in conductivity were maintained for periods in excess of 1 h after exposure. Conductivity changes were not found after exposure of physiological solutions to static magnetic fields, but changes of biological consequence did occur. Other experiments showed that there were several changes in cellular function observed in ganglia and isolated neurons of Helix pomatia when the perfusing medium was changed from the normal physiologic solution to the same solution after exposure to magnetic fields. These changes include membrane depolarization and increased action potential discharge, reduced uptake of Ca into cells, altered content of cyclic nucleotides in ganglia, and increased volume of isolated cell bodies. A change in hydration of calcium ions may be one of the consequences of magnetic-field exposure, and in physiological solutions this change may have functional consequences. © 1994 Wiley-Liss, Inc.
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  • 64
    Publication Date: 1994-02-25
    Description: Activation of the serine-threonine kinase p34cdc2 at an inappropriate time during the cell cycle leads to cell death that resembles apoptosis. Premature activation of p34cdc2 was shown to be required for apoptosis induced by a lymphocyte granule protease. The kinase was rapidly activated and tyrosine dephosphorylated at the initiation of apoptosis. DNA fragmentation and nuclear collapse could be prevented by blocking p34cdc2 activity with excess peptide substrate, or by inactivating p34cdc2 in a temperature-sensitive mutant. Premature p34cdc2 activation may be a general mechanism by which cells induced to undergo apoptosis initiate the disruption of the nucleus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shi, L -- Nishioka, W K -- Th'ng, J -- Bradbury, E M -- Litchfield, D W -- Greenberg, A H -- New York, N.Y. -- Science. 1994 Feb 25;263(5150):1143-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8108732" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; *Apoptosis ; CDC2 Protein Kinase/*metabolism ; DNA Damage ; Deoxyribonucleases/pharmacology ; Enzyme Activation ; Enzyme Induction ; Membrane Glycoproteins/pharmacology ; Mice ; Mitosis ; Molecular Sequence Data ; Perforin ; Phosphorylation ; Pore Forming Cytotoxic Proteins ; Serine Endopeptidases/pharmacology ; Tumor Cells, Cultured
    Print ISSN: 0036-8075
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  • 65
    Publication Date: 1994-05-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Patience, C -- McKnight, A -- Clapham, P R -- Boyd, M T -- Weiss, R A -- Schulz, T F -- G117/547/Medical Research Council/United Kingdom -- New York, N.Y. -- Science. 1994 May 20;264(5162):1159-60; author reply 1162-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7909960" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD4/*physiology ; Antigens, Differentiation, T-Lymphocyte/*physiology ; Base Sequence ; Cats ; Cell Line ; Dipeptidyl Peptidase 4 ; HIV-1/*physiology ; Humans ; Mink ; Molecular Sequence Data
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  • 66
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    Publication Date: 1994-10-14
    Description: An activity that severs stable microtubules is thought to be involved in microtubule reorganization during the cell cycle. Here, a 48-kilodalton microtubule-severing protein was purified from Xenopus eggs and identified as translational elongation factor 1 alpha (EF-1 alpha). Bacterially expressed human EF-1 alpha also displayed microtubule-severing activity in vitro and, when microinjected into fibroblasts, induced rapid and transient fragmentation of cytoplasmic microtubule arrays. Thus, EF-1 alpha, an essential component of the eukaryotic translational apparatus, appears to have a second role as a regulator of cytoskeletal rearrangements.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shiina, N -- Gotoh, Y -- Kubomura, N -- Iwamatsu, A -- Nishida, E -- New York, N.Y. -- Science. 1994 Oct 14;266(5183):282-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics and Molecular Biology, Kyoto University, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7939665" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/pharmacology ; Amino Acid Sequence ; Animals ; Base Sequence ; Cell Line ; Guanosine Triphosphate/analogs & derivatives/metabolism ; Humans ; Microtubules/drug effects/*metabolism ; Molecular Sequence Data ; Molecular Weight ; Oocytes ; Peptide Elongation Factor 1 ; Peptide Elongation Factors/chemistry/isolation & purification/*physiology ; Rats ; Recombinant Proteins/pharmacology ; Ribonucleoproteins/chemistry/isolation & purification/*physiology ; Sepharose/analogs & derivatives/metabolism ; Xenopus laevis
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  • 67
    Publication Date: 1994-05-13
    Description: In Drosophila, the misexpression or altered activity of genes from the bithorax complex results in homeotic transformations. One of these genes, abd-A, normally specifies the identity of the second through fourth abdominal segments (A2 to A4). In the dominant Hyperabdominal mutations (Hab), portions of the third thoracic segment (T3) are transformed toward A2 as the result of ectopic abd-A expression. Sequence analysis and deoxyribonuclease I footprinting demonstrate that the misexpression of abd-A in two independent Hab mutations results from the same single base change in a binding site for the gap gene Kruppel protein. These results establish that the spatial limits of the homeotic genes are directly regulated by gap gene products.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shimell, M J -- Simon, J -- Bender, W -- O'Connor, M B -- New York, N.Y. -- Science. 1994 May 13;264(5161):968-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology and Biochemistry, University of California, Irvine 92717.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7909957" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Binding Sites ; DNA-Binding Proteins/genetics/metabolism ; *Drosophila Proteins ; Drosophila melanogaster/embryology/*genetics ; Enhancer Elements, Genetic/*genetics ; Gene Expression Regulation ; *Genes, Homeobox ; Genes, Insect ; Kruppel-Like Transcription Factors ; Molecular Sequence Data ; *Nuclear Proteins ; *Point Mutation ; Proteins/*genetics ; Regulatory Sequences, Nucleic Acid ; *Repressor Proteins ; Transcription Factors/genetics/metabolism
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  • 68
    Publication Date: 1994-12-02
    Description: The nucleoli of vertebrate cells contain a number of small RNAs that are generated by the processing of intron fragments of protein-coding gene transcripts. The host gene (UHG) for intro-encoded human U22 is unusual in that it specifies a polyadenylated but apparently noncoding RNA. Depletion of U22 from Xenopus oocytes by oligonucleotide-directed ribonuclease H targeting prevented the processing of 18S ribosomal RNA (rRNA) at both ends. The appearance of 18S rRNA was restored by injection of in vitro-synthesized U22 RNA. These results identify a cellular function for an intron-encoded small RNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tycowski, K T -- Shu, M D -- Steitz, J A -- GM26154/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Dec 2;266(5190):1558-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06536.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7985025" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Blotting, Northern ; Cell Nucleolus/*chemistry ; Humans ; *Introns ; Molecular Sequence Data ; Oligonucleotide Probes ; Oocytes/metabolism ; RNA Precursors/*metabolism ; RNA Processing, Post-Transcriptional ; RNA, Nuclear/chemistry/*genetics/*physiology ; RNA, Ribosomal, 18S/*metabolism ; RNA, Small Nuclear/chemistry/*genetics/*physiology ; Xenopus
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  • 69
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-11-25
    Description: The splicing of group II introns occurs in two steps involving substrates with different chemical configurations. The question of whether these two steps are catalyzed by a single or two separate active sites is a matter of debate. Here, certain bases and phosphate oxygen atoms at conserved positions in domain V of a group II self-splicing intron are shown to be required for catalysis of both splicing steps. These results show that the active sites catalyzing the two steps must, at least, share common components, ruling out the existence of two completely distinct active sites in group II introns.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chanfreau, G -- Jacquier, A -- New York, N.Y. -- Science. 1994 Nov 25;266(5189):1383-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Unite de Genetique Moleculaire des Levures, URA 1149 du CNRS, Departement de Biologie Moleculaire, Institut Pasteur, Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973729" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Catalysis ; Electron Transport Complex IV/genetics ; Electrophoresis, Polyacrylamide Gel ; Exons ; *Introns ; Molecular Sequence Data ; Nucleic Acid Conformation ; *RNA Splicing ; RNA, Fungal/chemistry/*genetics ; Saccharomyces cerevisiae/enzymology/genetics ; Thionucleotides/genetics
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  • 70
    Publication Date: 1994-10-14
    Description: The rate at which the TATA-binding protein (TBP) interacts with the TATA element and promotes transcription by RNA polymerase II was determined in yeast cells. A TBP derivative with altered TATA-element specificity was rapidly induced, and transcription from promoters with appropriately mutated TATA elements was measured. Without a functional activator protein, basal transcription was observed only after a lag of several hours. In contrast, GCN4-activated transcription occurred rapidly upon induction of the TBP derivative. These results suggest that accessibility of TBP to the chromatin template in vivo is rate limiting and that activation domains increase recruitment of TBP to the promoter.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Klein, C -- Struhl, K -- GM30186/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Oct 14;266(5183):280-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7939664" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Chromatin/metabolism ; Copper/pharmacology ; DNA-Binding Proteins/*metabolism ; Fungal Proteins/metabolism/pharmacology ; Hydro-Lyases/genetics ; Molecular Sequence Data ; Protein Kinases/metabolism/pharmacology ; *Saccharomyces cerevisiae Proteins ; *TATA Box ; TATA-Box Binding Protein ; Templates, Genetic ; Transcription Factors/*metabolism/pharmacology ; *Transcriptional Activation ; Yeasts/genetics
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  • 71
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-11-04
    Description: An activity in human cell extracts is described that repairs DNA with loops of five or more unpaired bases. Repair is strand-specific and is directed by a nick located 5' or 3' to the loop. This repair is observed in a colorectal cancer cell line that is devoid of a wild-type hMLH1 gene and is deficient in repair of mismatches. However, a cell line with deletions in both hMSH2 alleles is deficient in repair of both loops and mismatches. Defects in loop repair may be relevant to the repetitive-sequence instability observed in cancers and other hereditary diseases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Umar, A -- Boyer, J C -- Kunkel, T A -- New York, N.Y. -- Science. 1994 Nov 4;266(5186):814-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973637" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing ; Base Composition ; Base Sequence ; Carrier Proteins ; Cell Extracts ; Cell Line ; Colorectal Neoplasms/*genetics ; *DNA Repair ; DNA, Satellite/genetics/metabolism ; *DNA-Binding Proteins ; HeLa Cells ; Humans ; Molecular Sequence Data ; MutS Homolog 2 Protein ; Neoplasm Proteins/*genetics/physiology ; Nuclear Proteins ; Nucleic Acid Heteroduplexes/*metabolism ; Proto-Oncogene Proteins/*genetics/physiology ; Repetitive Sequences, Nucleic Acid ; Tumor Cells, Cultured
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  • 72
    Publication Date: 1994-08-19
    Description: The Xlsirts are a family of transcribed repeat sequence genes that do not code for protein. Xlsirt RNAs become localized to the vegetal cortex of Xenopus oocytes early in oogenesis, before the localization of the messenger RNA Vg1, which encodes a transforming growth factor-beta-like molecule involved in mesoderm formation, and coincident with the localization of Xcat2 transcripts, which encode a nanos-like molecule. Destruction of the localized Xlsirts by injection of antisense oligodeoxynucleotides into stage 4 oocytes resulted in the release of Vg1 transcripts but not Xcat2 transcripts from the vegetal cortex. Xlsirt RNAs, which may be a structural component of the vegetal cortex, are a crucial part of a genetic pathway necessary for the proper localization of Vg1 that leads to subsequent normal pattern formation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kloc, M -- Etkin, L D -- New York, N.Y. -- Science. 1994 Aug 19;265(5175):1101-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Genetics, University of Texas, M.D. Anderson Cancer Center, Houston 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7520603" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cells, Cultured ; Glycoproteins/*genetics ; Molecular Sequence Data ; Oligonucleotides, Antisense/pharmacology ; Oogenesis ; RNA/*genetics ; RNA, Messenger/genetics/*metabolism ; RNA-Binding Proteins/genetics ; Repetitive Sequences, Nucleic Acid ; Transforming Growth Factor beta/genetics ; Xenopus ; *Xenopus Proteins ; Zinc Fingers
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  • 73
    Publication Date: 1994-06-24
    Description: Two ternary complexes of rat DNA polymerase beta (pol beta), a DNA template-primer, and dideoxycytidine triphosphate (ddCTP) have been determined at 2.9 A and 3.6 A resolution, respectively. ddCTP is the triphosphate of dideoxycytidine (ddC), a nucleoside analog that targets the reverse transcriptase of human immunodeficiency virus (HIV) and is at present used to treat AIDS. Although crystals of the two complexes belong to different space groups, the structures are similar, suggesting that the polymerase-DNA-ddCTP interactions are not affected by crystal packing forces. In the pol beta active site, the attacking 3'-OH of the elongating primer, the ddCTP phosphates, and two Mg2+ ions are all clustered around Asp190, Asp192, and Asp256. Two of these residues, Asp190 and Asp256, are present in the amino acid sequences of all polymerases so far studied and are also spatially similar in the four polymerases--the Klenow fragment of Escherichia coli DNA polymerase I, HIV-1 reverse transcriptase, T7 RNA polymerase, and rat DNA pol beta--whose crystal structures are now known. A two-metal ion mechanism is described for the nucleotidyl transfer reaction and may apply to all polymerases. In the ternary complex structures analyzed, pol beta binds to the DNA template-primer in a different manner from that recently proposed for other polymerase-DNA models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pelletier, H -- Sawaya, M R -- Kumar, A -- Wilson, S H -- Kraut, J -- CA17374/CA/NCI NIH HHS/ -- ES06839/ES/NIEHS NIH HHS/ -- GM10928/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1891-903.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, San Diego 92093-0317.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7516580" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; DNA/chemistry/metabolism ; DNA Polymerase I/*chemistry/metabolism ; DNA Primers/*chemistry/metabolism ; DNA-Directed RNA Polymerases/chemistry/metabolism ; Deoxycytosine Nucleotides/*chemistry/metabolism ; Dideoxynucleotides ; HIV Reverse Transcriptase ; Humans ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; RNA-Directed DNA Polymerase/chemistry/metabolism ; Rats ; Recombinant Proteins ; Templates, Genetic ; Thymine Nucleotides/chemistry/metabolism ; Viral Proteins ; Zidovudine/analogs & derivatives/chemistry/metabolism
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  • 74
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-06-17
    Description: Noninfectious, cytoplasmically transmissible viral double-stranded RNAs of the genus Hypovirus cause reduced virulence (hypovirulence) in the chestnut blight fungus Cryphonectria parasitica, providing the basis for virus-mediated biological control of a fungal disease. Synthetic transcripts corresponding to a full-length hypovirus RNA coding strand are infectious when introduced into fungal spheroplasts by electroporation. Hypovirus infections were readily established in Cryphonectria parasitica and in related fungal species not previously reported to harbor viruses. These results demonstrate the use of a synthetic mycovirus transcript to expand fungal host range, thereby broadening the potential application of virus-mediated hypovirulence to control fungal pathogenesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, B -- Choi, G H -- Nuss, D L -- New York, N.Y. -- Science. 1994 Jun 17;264(5166):1762-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8209256" target="_blank"〉PubMed〈/a〉
    Keywords: Ascomycota/genetics/*pathogenicity/physiology ; Base Sequence ; DNA, Complementary/genetics ; Electroporation ; Molecular Sequence Data ; Phenotype ; Plant Diseases ; RNA Viruses/*genetics/physiology ; RNA, Double-Stranded/*genetics ; RNA, Viral/*genetics ; Spheroplasts ; Transfection ; Virulence ; Virus Replication
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  • 75
    Publication Date: 1994-08-12
    Description: Strategies to cleave double-stranded DNA at specific DNA sites longer than those of restriction endonucleases (longer than 8 base pairs) have applications in chromosome mapping, chromosome cloning, and chromosome sequencing--provided that the strategies yield high DNA-cleavage efficiency and high DNA-cleavage specificity. In this report, the DNA-cleaving moiety copper:o-phenanthroline was attached to the sequence-specific DNA binding protein catabolite activator protein (CAP) at an amino acid that, because of a difference in DNA bending, is close to DNA in the specific CAP-DNA complex but is not close to DNA in the nonspecific CAP-DNA complex. The resulting CAP derivative, OP26CAP, cleaved kilobase and megabase DNA substrates at a 22-base pair consensus DNA site with high efficiency and exhibited no detectable nonspecific DNA-cleavage activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pendergrast, P S -- Ebright, Y W -- Ebright, R H -- GM41376/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Aug 12;265(5174):959-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Rutgers University, New Brunswick, NJ 08855.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8052855" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Cyclic AMP Receptor Protein/*chemistry ; DNA/*chemistry/metabolism ; DNA-Binding Proteins/*chemistry ; Molecular Sequence Data ; Molecular Structure ; Nucleic Acid Conformation ; Phenanthrolines/*chemistry
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  • 76
    Publication Date: 1994-11-11
    Description: The venom of the funnel-web spider Agelenopsis aperta contains several peptides that paralyze prey by blocking voltage-sensitive calcium channels. Two peptides, omega-Aga-IVB (IVB) and omega-Aga-IVC (IVC), have identical amino acid sequences, yet have opposite absolute configurations at serine 46. These toxins had similar selectivities for blocking voltage-sensitive calcium channel subtypes but different potencies for blocking P-type voltage-sensitive calcium channels in rat cerebellar Purkinje cells as well as calcium-45 influx into rat brain synaptosomes. An enzyme purified from venom converts IVC to IVB by isomerizing serine 46, which is present in the carboxyl-terminal tail, from the L to the D configuration. Unlike the carboxyl terminus of IVC, that of IVB was resistant to the major venom protease. These results show enzymatic activities in A. aperta venom being used in an unprecedented strategy for coproduction of necessary neurotoxins that possess enhanced stability and potency.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Heck, S D -- Siok, C J -- Krapcho, K J -- Kelbaugh, P R -- Thadeio, P F -- Welch, M J -- Williams, R D -- Ganong, A H -- Kelly, M E -- Lanzetti, A J -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1065-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NPS Pharmaceuticals Incorporated, Salt Lake City, Utah 84108.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973665" target="_blank"〉PubMed〈/a〉
    Keywords: Agatoxins ; Amino Acid Sequence ; Animals ; Base Sequence ; Calcium/metabolism ; Calcium Channel Blockers/chemistry/*metabolism/toxicity ; Calcium Channels/*metabolism ; Isomerases/metabolism ; Molecular Sequence Data ; *Protein Processing, Post-Translational ; Purkinje Cells/metabolism ; Rats ; Serine/*metabolism ; Spider Venoms/chemistry/enzymology/*metabolism/toxicity ; Stereoisomerism ; Structure-Activity Relationship ; Synaptosomes/metabolism
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  • 77
    Publication Date: 1994-11-25
    Description: Alteration of the human mismatch repair gene hMSH2 has been linked to the microsatellite DNA instability found in hereditary nonpolyposis colon cancer and several sporadic cancers. This microsatellite DNA instability is thought to arise from defective repair of DNA replication errors that create insertion-deletion loop-type (IDL) mismatched nucleotides. Here, it is shown that purified hMSH2 protein efficiently and specifically binds DNA containing IDL mismatches of up to 14 nucleotides. These results support a direct role for hMSH2 in mutation avoidance and microsatellite stability in human cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fishel, R -- Ewel, A -- Lee, S -- Lescoe, M K -- Griffith, J -- CA56542/CA/NCI NIH HHS/ -- GM31819/GM/NIGMS NIH HHS/ -- GM42342/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Nov 25;266(5189):1403-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Molecular Genetics, Markey Center for Molecular Genetics, University of Vermont School of Medicine, Burlington 05405.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973733" target="_blank"〉PubMed〈/a〉
    Keywords: Base Composition ; Base Sequence ; DNA Repair ; DNA, Satellite/*metabolism ; *DNA-Binding Proteins ; Humans ; Molecular Sequence Data ; MutS Homolog 2 Protein ; Nucleic Acid Conformation ; Nucleic Acid Heteroduplexes/metabolism ; Oligodeoxyribonucleotides/metabolism ; Proto-Oncogene Proteins/*metabolism
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  • 78
    Publication Date: 1994-08-26
    Description: Experimental autoimmune encephalomyelitis (EAE) is a cell-mediated autoimmune disease that serves as an animal model for multiple sclerosis. Oral administration of myelin basic protein (MBP) suppresses EAE by inducing peripheral tolerance. T cell clones were isolated from the mesenteric lymph nodes of SJL mice that had been orally tolerized to MBP. These clones were CD4+ and were structurally identical to T helper cell type 1 (TH1) encephalitogenic CD4+ clones in T cell receptor usage, major histocompatibility complex restriction, and epitope recognition. However, they produced transforming growth factor-beta with various amounts of interleukin-4 and interleukin-10 and suppressed EAE induced with either MBP or proteolipid protein. Thus, mucosally derived TH2-like clones induced by oral antigen can actively regulate immune responses in vivo and may represent a different subset of T cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, Y -- Kuchroo, V K -- Inobe, J -- Hafler, D A -- Weiner, H L -- AR/A143220/AR/NIAMS NIH HHS/ -- NS29352/NS/NINDS NIH HHS/ -- NS30843/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1994 Aug 26;265(5176):1237-40.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7520605" target="_blank"〉PubMed〈/a〉
    Keywords: Administration, Oral ; Amino Acid Sequence ; Animals ; CD4-Positive T-Lymphocytes/*immunology ; Clone Cells ; Encephalomyelitis, Autoimmune, Experimental/*immunology ; Epitopes/immunology ; *Immune Tolerance ; Interleukin-10/biosynthesis ; Interleukin-4/biosynthesis ; Lymph Nodes/immunology ; Major Histocompatibility Complex ; Mesentery/immunology ; Mice ; Molecular Sequence Data ; Myelin Basic Protein/administration & dosage/*immunology ; Myelin Proteins/immunology ; Myelin Proteolipid Protein ; Receptors, Antigen, T-Cell/immunology ; Transforming Growth Factor beta/biosynthesis
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  • 79
    Publication Date: 1994-09-02
    Description: As a step toward developing poliovirus as a vaccine vector, poliovirus recombinants were constructed by fusing exogenous peptides (up to 400 amino acids) and an artificial cleavage site for viral protease 3Cpro to the amino terminus of the viral polyprotein. Viral replication proceeded normally. An extended polyprotein was produced in infected cells and proteolytically processed into the complete array of viral proteins plus the foreign peptide, which was excluded from mature virions. The recombinants retained exogenous sequences through successive rounds of replication in culture and in vivo. Infection of animals with recombinants elicited a humoral immune response to the foreign peptides.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Andino, R -- Silvera, D -- Suggett, S D -- Achacoso, P L -- Miller, C J -- Baltimore, D -- Feinberg, M B -- AI22346/AI/NIAID NIH HHS/ -- AI35545/AI/NIAID NIH HHS/ -- RR00169/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 2;265(5177):1448-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, University of California, San Francisco.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8073288" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antibodies, Bacterial/biosynthesis ; Antibodies, Viral/biosynthesis ; Antigens, Bacterial/genetics/immunology ; Antigens, Viral/genetics/immunology ; Base Sequence ; Cloning, Molecular ; *Genetic Engineering ; Genetic Vectors ; HeLa Cells ; Humans ; Macaca fascicularis ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Poliovirus/*genetics/immunology/physiology ; Poliovirus Vaccine, Oral/*genetics ; *Protein Biosynthesis ; Proteins/metabolism ; Recombinant Proteins/biosynthesis/metabolism ; Vaccines, Synthetic/genetics/*immunology ; Virus Replication
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  • 80
    Publication Date: 1994-11-11
    Description: For survival, embryonic motoneurons in vertebrates depend on as yet undefined neurotrophic factors present in the limb bud. Members of the neurotrophin family are currently the best candidates for such neurotrophic factors, but inactivation of their receptor genes leads to only partial loss of motoneurons, which suggests that other factors are involved. Glial cell line-derived neurotrophic factor (GDNF), originally identified as a trophic factor specific for dopaminergic neurons, was found to be 75-fold more potent than the neurotrophins in supporting the survival of purified embryonic rat motoneurons in culture. GDNF messenger RNA was found in the immediate vicinity of motoneurons during the period of cell death in development. In vivo, GDNF rescues and prevents the atrophy of facial motoneurons that have been deprived of target-derived survival factors by axotomy. GDNF may therefore be a physiological trophic factor for spinal motoneurons. Its potency and specificity in vitro and in vivo also make it a good candidate for treatment of motoneuron disease.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Henderson, C E -- Phillips, H S -- Pollock, R A -- Davies, A M -- Lemeulle, C -- Armanini, M -- Simmons, L -- Moffet, B -- Vandlen, R A -- Simpson LC corrected to Simmons, L -- Koliatsos, V E -- Rosenthal, A -- NS 10580/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1062-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉INSERM U.382, IBDM, Marseille, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973664" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain-Derived Neurotrophic Factor ; Cell Death ; Cell Survival/drug effects ; Cells, Cultured ; Ciliary Neurotrophic Factor ; Face/innervation ; Glial Cell Line-Derived Neurotrophic Factor ; Growth Inhibitors/pharmacology ; *Interleukin-6 ; Leukemia Inhibitory Factor ; Lymphokines/pharmacology ; Molecular Sequence Data ; Motor Neurons/*cytology/drug effects ; Muscle Fibers, Skeletal/*metabolism ; Nerve Growth Factors/analysis/biosynthesis/genetics/*pharmacology ; Nerve Tissue Proteins/*analysis/biosynthesis/genetics/*pharmacology ; Neurons, Afferent/cytology/drug effects ; Peripheral Nerves/*metabolism ; RNA, Messenger/analysis/genetics ; Rats ; Schwann Cells/metabolism
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  • 81
    Publication Date: 1994-05-13
    Description: In Drosophila and human cells, the TATA binding protein (TBP) of the transcription factor IID (TFIID) complex is tightly associated with multiple subunits termed TBP-associated factors (TAFs) that are essential for mediating regulation of RNA polymerase II transcription. The Drosophila TAFII150 has now been molecularly cloned and biochemically characterized. The deduced primary amino acid sequence of dTAFII150 reveals a striking similarity to the essential yeast gene, TSM-1. Furthermore, like dTAFII150, the TSM-1 protein is found associated with the TBP in vivo, thus identifying the first yeast homolog of a TAF associated with TFIID. Both the product of TSM-1 and dTAFII150 bind directly to TBP and dTAFII250, demonstrating a functional similarity between human and yeast TAFs. Surprisingly, DNA binding studies indicate that purified recombinant dTAFII150 binds specifically to DNA sequences overlapping the start site of transcription. The data demonstrate that at least one of the TAFs is a sequence-specific DNA binding protein and that dTAFII150 together with TBP are responsible for TFIID interactions with an extended region of the core promoter.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Verrijzer, C P -- Yokomori, K -- Chen, J L -- Tjian, R -- New York, N.Y. -- Science. 1994 May 13;264(5161):933-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, University of California, Berkeley 94720-3202.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8178153" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cloning, Molecular ; DNA/*metabolism ; DNA-Binding Proteins/chemistry/genetics/*metabolism ; Drosophila ; *Drosophila Proteins ; Genes, Fungal ; Genes, Insect ; Histone Acetyltransferases ; Humans ; Molecular Sequence Data ; Nuclear Proteins/metabolism ; *Promoter Regions, Genetic ; RNA Polymerase II/metabolism ; Recombinant Proteins/metabolism ; Saccharomyces cerevisiae/genetics ; *Saccharomyces cerevisiae Proteins ; Sequence Alignment ; TATA Box ; *TATA-Binding Protein Associated Factors ; TATA-Box Binding Protein ; Transcription Factor TFIID ; Transcription Factors/chemistry/genetics/*metabolism
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  • 82
    Publication Date: 1994-12-16
    Description: Representational difference analysis was used to isolate unique sequences present in more than 90 percent of Kaposi's sarcoma (KS) tissues obtained from patients with acquired immunodeficiency syndrome (AIDS). These sequences were not present in tissue DNA from non-AIDS patients, but were present in 15 percent of non-KS tissue DNA samples from AIDS patients. The sequences are homologous to, but distinct from, capsid and tegument protein genes of the Gammaherpesvirinae, herpesvirus saimiri and Epstein-Barr virus. These KS-associated herpesvirus-like (KSHV) sequences appear to define a new human herpesvirus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chang, Y -- Cesarman, E -- Pessin, M S -- Lee, F -- Culpepper, J -- Knowles, D M -- Moore, P S -- New York, N.Y. -- Science. 1994 Dec 16;266(5192):1865-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY 10032.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7997879" target="_blank"〉PubMed〈/a〉
    Keywords: Acquired Immunodeficiency Syndrome/*complications ; Amino Acid Sequence ; Base Composition ; Base Sequence ; Blotting, Southern ; Cloning, Molecular ; DNA, Viral/*analysis/chemistry/genetics ; Female ; Herpesviridae/*genetics ; Herpesvirus 2, Saimiriine/genetics ; Herpesvirus 4, Human/genetics ; Humans ; Male ; Molecular Sequence Data ; Nucleic Acid Hybridization ; Open Reading Frames ; Polymerase Chain Reaction ; Retrospective Studies ; Sarcoma, Kaposi/etiology/*virology ; Sequence Homology, Amino Acid
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  • 83
    Publication Date: 1994-11-11
    Description: Signals mediated by the T cell receptor (TCR) are required for thymocyte maturation and selection. To examine the role of TCR zeta chain signals in development, TCR expression was restored in zeta-deficient mice with transgenic zeta chains that partially or completely lacked sequences required for signal transduction. The zeta chain played a role in thymic development by promoting TCR surface expression, but zeta-mediated signals were not essential because TCRs that contained signaling-deficient zeta chains promoted T cell maturation and transduced signals associated with thymic selection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shores, E W -- Huang, K -- Tran, T -- Lee, E -- Grinberg, A -- Love, P E -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1047-50.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Hematologic Products, Food and Drug Administration, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7526464" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antigens, CD/analysis/genetics ; Antigens, CD4/analysis ; Antigens, CD5 ; Antigens, CD8/analysis ; Antigens, Differentiation, T-Lymphocyte/analysis ; *DNA-Binding Proteins ; Down-Regulation ; Gene Expression ; *Homeodomain Proteins ; Lectins, C-Type ; Lymph Nodes/immunology ; Membrane Proteins/genetics/*physiology ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Proteins/genetics ; RNA, Messenger/genetics/metabolism ; Receptors, Antigen, T-Cell/genetics/*physiology ; Signal Transduction ; T-Lymphocytes/cytology/*immunology ; Thymus Gland/immunology
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  • 84
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-08-05
    Description: The microinjection of messenger RNA encoding the eukaryotic translation initiation factor 4E (eIF-4E) into early embryos of Xenopus laevis leads to the induction of mesoderm in ectodermal explants. This induction occurs without a stimulation of overall protein synthesis and is blocked by the co-expression of a dominant negative mutant of the proto-oncogene ras or a truncated activin type II receptor. Although other translation factors have been studied in vertebrate and invertebrate embryos, none have been shown to play a direct role in development. The results here suggest a mechanism for relaying and amplifying signals for mesoderm induction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Klein, P S -- Melton, D A -- New York, N.Y. -- Science. 1994 Aug 5;265(5173):803-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA 02138.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8047887" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Eukaryotic Initiation Factor-1/physiology ; Eukaryotic Initiation Factor-4E ; Gene Expression Regulation/physiology ; Mesoderm/metabolism/*physiology ; Molecular Sequence Data ; Peptide Initiation Factors/genetics/*physiology ; RNA, Messenger ; Xenopus laevis/*embryology
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  • 85
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-11-11
    Description: Long-tailed manakins mate in leks and cooperate in multiyear male-male partnerships. An alpha male is responsible for virtually all mating, whereas a beta male assists in the courtship displays. Such altruism by the beta male poses a problem for evolutionary theory because most theoretical treatments and empirical examples of cooperative behavior involve kin selection or reciprocity. Here it is shown that alpha and beta partners are not relatives and that reciprocity is not involved. Instead, direct, though long-delayed benefits to beta males are demonstrated, which include rare copulations, ascension to alpha status, and female lek fidelity. These benefits maintain this unusual form of male-male cooperation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McDonald, D B -- Potts, W K -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1030-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Archbold Biological Station, Lake Placid, FL 33852-2057.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973654" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; Base Sequence ; Birds/genetics/*physiology ; *Cooperative Behavior ; Copulation ; Female ; Heterozygote ; Male ; Molecular Sequence Data ; Polymerase Chain Reaction ; *Sexual Behavior, Animal
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  • 86
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-03-25
    Description: Significant opportunities and challenges exist in the creation and characterization of biomaterials. Materials have been designed for contact with blood, as replacements for soft and hard tissues, as adhesives, and as dental materials. Current methods of synthesis and characterization of these materials are outlined. Approaches for controlling the interface between tissue and biomaterials and ways in which the engineered materials may contribute to medicine are considered.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Peppas, N A -- Langer, R -- GM25810/GM/NIGMS NIH HHS/ -- GM43337/GM/NIGMS NIH HHS/ -- GM45027/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1994 Mar 25;263(5154):1715-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-1283.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8134835" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; *Biocompatible Materials/chemical synthesis/chemistry ; Dental Materials ; Drug Carriers ; Humans ; Materials Testing ; Molecular Sequence Data ; Prostheses and Implants ; Protein Engineering
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  • 87
    Publication Date: 1994-06-24
    Description: A 175-kilodalton erythrocyte binding protein, EBA-175, of the parasite Plasmodium falciparum mediates the invasion of erythrocytes. The erythrocyte receptor for EBA-175 is dependent on sialic acid. The domain of EBA-175 that binds erythrocytes was identified as region II with the use of truncated portions of EBA-175 expressed on COS cells. Region II, which contains a cysteine-rich motif, and native EBA-175 bind specifically to glycophorin A, but not to glycophorin B, on the erythrocyte membrane. Erythrocyte recognition of EBA-175 requires both sialic acid and the peptide backbone of glycophorin A. The identification of both the receptor and ligand domains may suggest rational designs for receptor blockade and vaccines.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sim, B K -- Chitnis, C E -- Wasniowska, K -- Hadley, T J -- Miller, L H -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1941-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Malaria Research, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8009226" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antigens, Protozoan ; Base Sequence ; Binding Sites ; Carrier Proteins/genetics/*metabolism ; Cell Line ; Erythrocytes/metabolism/*parasitology ; Glycopeptides/chemistry/metabolism ; Glycophorin/chemistry/*metabolism ; Molecular Sequence Data ; Plasmodium falciparum/*metabolism ; Protozoan Proteins/genetics/*metabolism ; Recombinant Fusion Proteins/metabolism ; Sialic Acids/*metabolism
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  • 88
    Publication Date: 1994-03-25
    Description: Fas is an apoptosis-signaling receptor molecule on the surface of a number of cell types. Molecular cloning and nucleotide sequence analysis revealed a human Fas messenger RNA variant capable of encoding a soluble Fas molecule lacking the transmembrane domain because of the deletion of an exon encoding this region. The expression of soluble Fas was confirmed by flow cytometry and immunocytochemical analysis. Supernatants from cells transfected with the variant messenger RNA blocked apoptosis induced by the antibody to Fas. Levels of soluble Fas were elevated in patients with systemic lupus erythematosus, and mice injected with soluble Fas displayed autoimmune features.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cheng, J -- Zhou, T -- Liu, C -- Shapiro, J P -- Brauer, M J -- Kiefer, M C -- Barr, P J -- Mountz, J D -- P01 AR03555/AR/NIAMS NIH HHS/ -- P50 AI23694/AI/NIAID NIH HHS/ -- P60 AR20614/AR/NIAMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1994 Mar 25;263(5154):1759-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of Alabama at Birmingham.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7510905" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antibodies/immunology ; Antigens, CD95 ; Antigens, Surface/chemistry/genetics/immunology/*physiology ; *Apoptosis ; Arthritis, Rheumatoid/blood ; Base Sequence ; Cell Line ; Cell Membrane/chemistry ; Humans ; Lupus Erythematosus, Systemic/blood ; Mice ; Molecular Sequence Data ; RNA, Messenger/genetics ; Solubility ; T-Lymphocyte Subsets/immunology ; Transfection
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  • 89
    Publication Date: 1994-11-04
    Description: Transcription terminators recognized by several RNA polymerases include a DNA segment encoding uridine-rich RNA and, for bacterial RNA polymerase, a hairpin loop located immediately upstream. Here, mutationally altered Escherichia coli RNA polymerase enzymes that have different termination efficiencies were used to show that the extent of transcription through the uridine-rich encoding segment is controlled by the substrate concentration of nucleoside triphosphate. This result implies that the rate of elongation determines the probability of transcript release. Moreover, the position of release sites suggests an important spatial relation between the RNA hairpin and the boundary of the terminator.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McDowell, J C -- Roberts, J W -- Jin, D J -- Gross, C -- New York, N.Y. -- Science. 1994 Nov 4;266(5186):822-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY 14853.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7526463" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; DNA-Directed RNA Polymerases/genetics/*metabolism ; Escherichia coli/enzymology/genetics ; Molecular Sequence Data ; Mutation ; Nucleic Acid Conformation ; Nucleotides/metabolism ; RNA, Bacterial/*genetics/metabolism ; *Terminator Regions, Genetic ; *Transcription, Genetic ; Uridine Triphosphate/metabolism
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  • 90
    Publication Date: 1994-03-18
    Description: Engagement of antigen receptor complexes induces rapid activation of Src-family kinases and association with phosphatidylinositol-3' kinase (PI-3 kinase). Here it was found that the Src homology 3 (SH3) domain of Lyn and Fyn bound to a proline-rich region (residues 84 to 99) within the 85-kilodalton subunit (p85) of PI-3 kinase. The binding of SH3 to the purified kinase led to a five- to sevenfold increase in the specific activity of PI-3 kinase. Ligand-induced receptor stimulation activated PI-3 kinase, and this activation was blocked by a peptide containing residues 84 to 99 of p85. These data demonstrate a mechanism for PI-3 kinase activation and show that binding of SH3 domains to proline-rich target sequences can regulate enzymatic activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pleiman, C M -- Hertz, W M -- Cambier, J C -- A120519/PHS HHS/ -- A121768/PHS HHS/ -- A129903/PHS HHS/ -- New York, N.Y. -- Science. 1994 Mar 18;263(5153):1609-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8128248" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; B-Lymphocytes/*enzymology ; Enzyme Activation ; Lymphocyte Activation ; Mice ; Molecular Sequence Data ; Peptide Fragments/pharmacology ; Phosphatidylinositol 3-Kinases ; Phosphotransferases (Alcohol Group Acceptor)/chemistry/*metabolism ; Proline/chemistry ; Protein-Tyrosine Kinases/chemistry/*metabolism ; Proto-Oncogene Proteins/chemistry/*metabolism ; Proto-Oncogene Proteins c-fyn ; *src-Family Kinases
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  • 91
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-05-20
    Description: A predictive rule for protein folding is presented that involves two recurrent glycine-based motifs that cap the carboxyl termini of alpha helices. In proteins, helices that terminated in glycine residues were found predominantly in one of these two motifs. These glycine structures had a characteristic pattern of polar and apolar residues. Visual inspection of known helical sequences was sufficient to distinguish the two motifs from each other and from internal glycines that fail to terminate helices. These glycine motifs--in which the local sequence selects between available structures--represent an example of a stereochemical rule for protein folding.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aurora, R -- Srinivasan, R -- Rose, G D -- GM 29458/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 May 20;264(5162):1126-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8178170" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Glycine/*chemistry ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Oligopeptides/chemistry ; *Protein Folding ; *Protein Structure, Secondary
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  • 92
    Publication Date: 1994-12-09
    Description: Complete 16S-like ribosomal RNA coding regions were obtained from the fungal symbiont of five genera of attine (leaf-cutting) ants and two free-living fungi. Phylogenetic analyses with distance matrix, maximum likelihood, and parsimony methods revealed that the attine fungal symbionts are homobasidiomycetes in the order Agaricales. Comparison of the topology of the attine fungal symbiont phylogenetic tree with a tree based on attine ant morphology revealed a congruent branching pattern of the more derived attine ants and their fungal symbionts. The parallel branching pattern suggests a long-term coevolution of derived leaf-cutting attine ants and their fungal symbionts.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hinkle, G -- Wetterer, J K -- Schultz, T R -- Sogin, M L -- GM32964/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Dec 9;266(5191):1695-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Marine Biological laboratory, Woods Hole, MA 02543.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7992052" target="_blank"〉PubMed〈/a〉
    Keywords: Agaricales/*classification/genetics/physiology ; Agaricus/classification/genetics ; Animals ; Ants/classification/*microbiology/physiology ; Biological Evolution ; *Genes, Fungal ; Molecular Sequence Data ; *Phylogeny ; RNA, Fungal/*genetics ; RNA, Ribosomal/*genetics ; RNA, Ribosomal, 16S/genetics ; Symbiosis
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  • 93
    Publication Date: 1994-12-23
    Description: The chloroplast outer envelope protein OEP86 functions as a receptor in precursor protein translocation into chloroplasts. Sequence analysis suggests that the precursor of OEP86 is directed to the chloroplast outer envelope by a cleavable, negatively charged, and unusually long amino-terminal peptide. This presequence is unlike other potential targeting signals and suggests the existence of another membrane insertion pathway. Insertion of precursor OEP86 required the hydrolysis of adenosine triphosphate and the existence of surface exposed chloroplast membrane components, and it was not competed by another precursor protein destined for the internal plastid compartments.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hirsch, S -- Muckel, E -- Heemeyer, F -- von Heijne, G -- Soll, J -- New York, N.Y. -- Science. 1994 Dec 23;266(5193):1989-92.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Botanisches Institut, Universitat Kiel, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7801125" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Amino Acid Sequence ; Chloroplast Proteins ; Chloroplasts/*metabolism ; *GTP-Binding Proteins ; Hydrogen-Ion Concentration ; Intracellular Membranes/metabolism ; Molecular Sequence Data ; Molecular Weight ; Peas ; Plant Proteins/chemistry/*metabolism ; Protein Precursors/chemistry/*metabolism ; Protein Processing, Post-Translational ; Ribulose-Bisphosphate Carboxylase/metabolism
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  • 94
    Publication Date: 1994-06-03
    Description: Multi-wavelength anomalous diffraction (MAD) has been used to determine the structure of the regulatory enzyme of de novo synthesis of purine nucleotides, glutamine 5-phosphoribosyl-1-pyrophosphate (PRPP) amidotransferase, from Bacillus subtilis. This allosteric enzyme, a 200-kilodalton tetramer, is subject to end product regulation by purine nucleotides. The metalloenzyme from B. subtilis is a paradigm for the higher eukaryotic enzymes, which have been refractory to isolation in stable form. The two folding domains of the polypeptide are correlated with functional domains for glutamine binding and for transfer of ammonia to the substrate PRPP. Eight molecules of the feedback inhibitor adenosine monophosphate (AMP) are bound to the tetrameric enzyme in two types of binding sites: the PRPP catalytic site of each subunit and an unusual regulatory site that is immediately adjacent to each active site but is between subunits. An oxygen-sensitive [4Fe-4S] cluster in each subunit is proposed to regulate protein turnover in vivo and is distant from the catalytic site. Oxygen sensitivity of the cluster is diminished by AMP, which blocks a channel through the protein to the cluster. The structure is representative of both glutamine amidotransferases and phosphoribosyltransferases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smith, J L -- Zaluzec, E J -- Wery, J P -- Niu, L -- Switzer, R L -- Zalkin, H -- Satow, Y -- DK-42303/DK/NIDDK NIH HHS/ -- GM-24658/GM/NIGMS NIH HHS/ -- R37 DK042303/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 3;264(5164):1427-33.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8197456" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Monophosphate/metabolism ; Allosteric Regulation ; Amidophosphoribosyltransferase/*chemistry/metabolism ; Amino Acid Sequence ; Animals ; Bacillus subtilis/*enzymology ; Binding Sites ; Computer Graphics ; Crystallography, X-Ray ; Humans ; Models, Molecular ; Molecular Sequence Data ; Oxygen/pharmacology ; Protein Folding ; Protein Structure, Secondary ; Saccharomyces cerevisiae
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  • 95
    Publication Date: 1994-09-16
    Description: The evolutionary origins of the protistan phylum, Myxozoa, have long been questioned. Although these obligate parasites are like protozoans in many features, several aspects of their ontogeny and morphology have implied a closer relationship to metazoan lineages. Phylogenetic analyses of 18S ribosomal RNA sequences from myxozoans and other eukaryotes, with the use of parsimony, distance, and maximum-likelihood methods, support the hypothesis that myxozoans are closely related to the bilateral animals. These results suggest that the Myxozoa, long considered an assemblage of protozoans, should be considered a metazoan phylum.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smothers, J F -- von Dohlen, C D -- Smith, L H Jr -- Spall, R D -- New York, N.Y. -- Science. 1994 Sep 16;265(5179):1719-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Idaho State University, Pocatello 83209.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8085160" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Biological Evolution ; Eukaryota/*classification/genetics ; Likelihood Functions ; Molecular Sequence Data ; Parasites/*classification/genetics ; Phylogeny ; Probability ; RNA, Protozoan/genetics ; RNA, Ribosomal, 18S/*genetics
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  • 96
    Publication Date: 1994-06-24
    Description: The structure of the leech protein decorsin, a potent 39-residue antagonist of glycoprotein IIb-IIIa and inhibitor of platelet aggregation, was determined by nuclear magnetic resonance. In contrast to other disintegrins, the Arg-Gly-Asp (RGD)-containing region of decorsin is well defined. The three-dimensional structure of decorsin is similar to that of hirudin, an anticoagulant leech protein that potently inhibits thrombin. Amino acid sequence comparisons suggest that ornatin, another glycoprotein IIb-IIIa antagonist, and antistasin, a potent Factor Xa inhibitor and anticoagulant found in leeches, share the same structural motif. Although decorsin, hirudin, and antistasin all affect the blood clotting process and appear similar in structure, their mechanisms of action and epitopes important for binding to their respective targets are distinct.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Krezel, A M -- Wagner, G -- Seymour-Ulmer, J -- Lazarus, R A -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1944-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8009227" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Hirudins/chemistry ; Invertebrate Hormones/chemistry ; *Leeches ; Magnetic Resonance Spectroscopy ; Molecular Sequence Data ; Oligopeptides/chemistry ; Platelet Membrane Glycoproteins/*antagonists & inhibitors ; Protein Conformation ; Protein Structure, Secondary ; Proteins/*chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 97
    Publication Date: 1994-04-01
    Description: Fetal cardiomyocytes isolated from transgenic mice carrying a fusion gene of the alpha-cardiac myosin heavy chain promoter with a beta-galactosidase reporter were examined for their ability to form stable intracardiac grafts. Embryonic day 15 transgenic cardiomyocytes delivered directly into the myocardium of syngeneic hosts formed stable grafts, as identified by nuclear beta-galactosidase activity. Grafted cardiomyocytes were observed as long as 2 months after implantation, the latest date assayed. Intracardiac graft formation did not induce overtly negative effects on the host myocardium and was not associated with chronic immune rejection. Electron microscopy revealed the presence of nascent intercalated disks connecting the engrafted fetal cardiomyocytes and the host myocardium. These results suggest that intracardiac grafting might provide a useful approach for myocardial repair, provided that the grafted cells can contribute to myocardial function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Soonpaa, M H -- Koh, G Y -- Klug, M G -- Field, L J -- HL45453/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1994 Apr 1;264(5155):98-101.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis 46202-4800.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8140423" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cell Communication ; Cell Differentiation ; Cell Nucleus/metabolism ; *Cell Transplantation ; DNA/biosynthesis ; DNA Primers ; Electrocardiography ; Fetal Heart/*cytology ; *Fetal Tissue Transplantation ; Gap Junctions/physiology/ultrastructure ; Genetic Markers ; Heart/physiology ; Intercellular Junctions/physiology/*ultrastructure ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Myocardium/*cytology/ultrastructure ; beta-Galactosidase/analysis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 98
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-06-24
    Description: The basic notions of transition state theory have been exploited in the past to generate highly selective catalysts from the vast library of antibody molecules in the immune system. These same ideas were used to isolate an RNA molecule, from a large library of RNAs, that catalyzes the isomerization of a bridged biphenyl. The RNA-catalyzed reaction displays Michaelis-Menten kinetics with a catalytic rate constant (kcat) of 2.8 x 10(-5) per minute and a Michaelis constant (Km) of 542 microM; the reaction is competitively inhibited by the planar transition state analog with an inhibition constant (Ki) value of approximately 7 microM. This approach may provide a general strategy for expanding the scope of RNA catalysis beyond those reactions in which the substrates are nucleic acids or nucleic acid derivatives.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prudent, J R -- Uno, T -- Schultz, P G -- GM08352A/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1924-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8009223" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Biphenyl Compounds/chemistry/metabolism ; Catalysis ; Kinetics ; Molecular Sequence Data ; Nucleic Acid Conformation ; Nucleic Acid Denaturation ; Polymerase Chain Reaction ; RNA, Catalytic/chemistry/*metabolism ; Stereoisomerism ; Temperature
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 99
    Publication Date: 1994-07-15
    Description: A subset of patients who have undergone coronary angioplasty develop restenosis, a vessel renarrowing characterized by excessive proliferation of smooth muscle cells (SMCs). Of 60 human restenosis lesions examined, 23 (38 percent) were found to have accumulated high amounts of the tumor suppressor protein p53, and this correlated with the presence of human cytomegalovirus (HCMV) in the lesions. SMCs grown from the lesions expressed HCMV protein IE84 and high amounts of p53. HCMV infection of cultured SMCs enhanced p53 accumulation, which correlated temporally with IE84 expression. IE84 also bound to p53 and abolished its ability to transcriptionally activate a reporter gene. Thus, HCMV, and IE84-mediated inhibition of p53 function, may contribute to the development of restenosis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Speir, E -- Modali, R -- Huang, E S -- Leon, M B -- Shawl, F -- Finkel, T -- Epstein, S E -- New York, N.Y. -- Science. 1994 Jul 15;265(5170):391-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cardiology Branch, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8023160" target="_blank"〉PubMed〈/a〉
    Keywords: Adolescent ; Adult ; Aged ; Aged, 80 and over ; *Angioplasty, Balloon ; Antigens, Viral/*metabolism ; Atherectomy, Coronary ; Base Sequence ; Cells, Cultured ; Coronary Disease/*etiology/pathology/therapy ; Coronary Vessels/cytology/metabolism/microbiology ; Cytomegalovirus/*physiology ; Genes, p53 ; Humans ; Immediate-Early Proteins/*metabolism ; Middle Aged ; Molecular Sequence Data ; Muscle, Smooth, Vascular/cytology/metabolism/microbiology ; Recurrence ; Transcriptional Activation ; Transfection ; Tumor Suppressor Protein p53/genetics/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 100
    Publication Date: 1994-09-30
    Description: The RAD1 and RAD10 genes of Saccharomyces cerevisiae are required for both nucleotide excision repair and certain mitotic recombination events. Here, model recombination and repair intermediates were used to show that Rad1-Rad10-mediated cleavage occurs at duplex-single-strand junctions. Moreover, cleavage occurs only on the strand containing the 3' single-stranded tail. Thus, both biochemical and genetic evidence indicate a role for the Rad1-Rad10 complex in the cleavage of specific recombination intermediates. Furthermore, these data suggest that Rad1-Rad10 endonuclease incises DNA 5' to damaged bases during nucleotide excision repair.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bardwell, A J -- Bardwell, L -- Tomkinson, A E -- Friedberg, E C -- CA12428/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 30;265(5181):2082-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Pathology, University of Texas Southwestern Medical Center at Dallas 75235.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8091230" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; *DNA Repair ; DNA Repair Enzymes ; DNA, Fungal/genetics/*metabolism ; DNA, Single-Stranded/metabolism ; *DNA-Binding Proteins ; Endodeoxyribonucleases/*metabolism ; *Endonucleases ; Fungal Proteins/*metabolism ; Molecular Sequence Data ; Oligodeoxyribonucleotides/metabolism ; *Recombination, Genetic ; Saccharomyces cerevisiae/*genetics/metabolism ; *Saccharomyces cerevisiae Proteins ; Single-Strand Specific DNA and RNA Endonucleases
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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