C-fos gene activation in murine thymocytes by a mechanism independent of protein kinase C or a Ca2+ signal.

The accumulation of c-fos mRNA in mouse thymocytes was compared when the cells were stimulated by concanavalin A (Con A), the Ca2+ ionophore A23187 or the phorbol ester, TPA, either separately or by combinations of these mitogens. The c-fos response to mitogenic concentrations of Con A could not be attributed either to the rise in [Ca2+]i it induces or to activation of protein kinase C. Thus, although Con A causes the breakdown of phosphatidylinositol 4,5-bisphosphate in these cells, neither of the signals which can be generated by this response was responsible for the activation of the c-fos gene by Con A. This implies that some other unidentified signal generated by Con A activates the c-fos gene.

RBE and weighting of absorbed dose in ion-beam therapy.

Absorbed dose is the fundamental quantity used to quantify the exposure of any biological system to ionizing radiation. However, the relationship between dose and biological effect is not unique but varies with fractionation and time factor(s), radiation quality and irradiation conditions. In radiation therapy, weighting factors are used to correlate absorbed dose and clinical effects when altering irradiation conditions, or for combining or comparing different technical modalities. For some well established therapy modalities (e.g. fractionated photon beam therapy), a general agreement on weighting factors has been reached: it is based on the linear-quadratic model. For neutron, proton or ion therapy, the differences in radiation quality are currently accounted for using a diversity of methods (almost hospital specific). This paper reviews the current approaches used for evaluating or selecting the weighting factors and their application in clinical practice. The weighting factors take account of the RBE and other factors, such as fractionation when needed. Harmonization of these approaches will facilitate the exchange of information within the radiation oncology community and between centres using different technical modalities. In any case, when reporting the treatments, absorbed dose and irradiation conditions should always be specified in addition to the weighting factor and the weighted dose.

The effect of low-frequency whole-body vibration under different visual conditions on auditory evoked potentials.

Auditory evoked brain potentials (AEP) were recorded from 9 healthy males during sinusoidal whole-body vibration (WBV) in the longitudinal (+/- az) direction with 0.6 Hz, 1.85 ms-2rms (F1), 1.01 Hz, 4.27 ms-2rms (F2) and without WBV (F3) under 3 visual conditions--homogeneous bright visual field (B), normal vision (N), and complete darkness (D). The sequences of the different experimental conditions were arranged according to a 9 X 9 Latin Square design. A subtraction technique was used to eliminate vibration-synchronous activity from the EEG. The N1 and N1P2 amplitudes decreased during F1 and F2, compared to F3. The latencies of N1 and P2 increased during F1 and F2. The effects of F1 and F2 did not differ. The visual conditions exhibited no systematic effect on the AEP. The results suggest (1) F1 and F2 to be equivalent exposure conditions and (2) the dominance of vestibular-auditory interactions, compared with visual-auditory ones.

Estimation of disc compression during transient whole-body vibration.

This study was performed to examine health effects of transient whole-body vibrations on the lumbar spine. The aim was to detect extremes in the time course of compressive load acting on the disc L3-4 in order to estimate the health risk which depends on the amplitude of peak values of compression. Five healthy males were repeatedly exposed to various transient displacements with nearly sinusoidal or half-sinusoidal waveforms, different durations, and peak accelerations between about 1.4 and 4.1 ms(-2). Accelerations in the z direction were measured on the skin over the spinous processes of L3-4 in five subjects and averaged individually. Complete time series of dynamic compressive forces were calculated by means of a biomechanical model using the calculated effective mass of the human body above the disc L3-4 and relative accelerations between the vertebrae L3-4 for the first time. The amplitudes of the absolute peak values of the compressive forces were influenced only by the interaction between the initial direction and the duration of the waveform. Direct comparisons with the results of other authors are impossible due to methodical differences and missing data in the time domain. The nearly constant peak compressive forces with a shorter duration of transients connected with a higher-frequency content support the proposal to put more weight on vibrations above 8 Hz in a revised International Standard ISO 2631. The comparison of the calculated internal forces with results of in-vitro studies indicates a possible health risk for persons with a low vertebral strength during repetitive exposures to moderate transient whole-body vibrations.

Transfer functions as a basis for the verification of models--variability and restraints.

OBJECTIVE: The seat-to-head transfer function of the human body reflects the biodynamic response. Based on measured data, biodynamic models have been proposed to reflect this response. They must satisfy usually the international published mean values of the seat-to-head transfer function. The question arises to what extent mean values reflect individual pattern of biodynamics. METHODS: An experimental study was performed with 39 male subjects sitting on a hard seat without back rest and with supported feet. They were exposed to random whole-body vibration at three intensities with a relaxed and an erect posture. The accelerations in the z-direction were measured at the seat and head. The seat-to-head transfer functions with the associated coherence functions were calculated. RESULTS: The biodynamic response characterised by the maximum of the seat-to-head transmissibility and the frequency of its occurrence is influenced by the posture of the subjects in a dominant way and shows an individual variability of considerable extent. The mean responses suggest a missing effect of vibration intensity, but individually different effects of the intensity were found. Repeated measurements confirmed this result. CONCLUSIONS: The application of a model validated by the comparison with mean values of the transmissibility could cause misleading conclusions, if it is used for the prediction of individual spinal loads. Models prepared for the calculation of individual loads should be validated by a mean individual transmissibility derived from repeated measurements. RELEVANCE: The results illustrate the loss of information by averaging individual transfer functions and the consequence of a limited validity and applicability in occupational health, ergonomics, and design.

Bidimensional accelerations of lumbar vertebrae and estimation of internal spinal load during sinusoidal vertical whole-body vibration: a pilot study.

Accelerations, a, in z- and x-directions were measured on the skin over spinous processes L3 and L4 in three subjects during sinusoidal whole-body vibration (WBV) at 4·5 and 8 Hz and 1·5 and 3·0 ms(-2) r.m.s. A method for the prediction of bone accelerations was applied using measurements on the skin. Relative accelerations were calculated by subtracting aL4 from aL3. The phase relations between relative accelerations in the z-direction indicating compression and the absolute maximum az of L4 exhibited marked between-subject variability. One subject was selected for a detailed analysis in the time domain of head, shoulder and upper trunk accelerations, and for comparison with an invasive study. Bidimensional acceleration data confirmed the suggestion that relative motions in the z-direction are combined with angular motions. The results indicate complex internal loads with coupled bending, compression and shear forces.

The effect of triazole on RNA viruses.

The triazole derivative 4-(1-hydroxy-3-piperid-N-yl-prop-l-yl)-5-methyl-2-methyl-2-phenyl-triazole (HMPT) markedly reduced plaque formation by, RNA bacteriophages and delayed their liberation. Replication of tobacco mosaic virus in a systemic host was hardly affected by HMPT, but local lesion formation in a hypersensitive host was strongly reduced by the drug. The mechanism of action of HMPT was discussed.

[Enhanced formation of plaque in RNA phages/bacteria systems under the effect of surface-active preparations]. / Geförderte Plaquebildung in RNA-Phagen/Bakterien-Systemen unter dem Einfluss oberflächenaktiver Präparate.

The effect of 21 surfactants on the plaque formation was tested in three RNA-phages/Escherichia coli systems and in one RNA-phage/Pseudomonas aeruginosa system. Especially anionic detergents proved to be able to influence the plaque formation substantially. In high concentrations of Metaupon, Fekunil 602, Fekunil S-BA, Emulgator W 270, and Emulgator O-BA the plaque formation by the phages M 12 and f2 was inhibited and in low concentrations it was promoted. In the system Q beta/E. coli AB 301 the effect of the detergents mentioned was restricted to the prevention of the appearance of plaques. The detergent E 30 brought about only plaque inhibitions, too, in all used RNA-phages/E. coli systems. The treatment with effective detergents in the system PP7/P. aeruginosa, however, increased only the number of plaques. This phenomenon was evident in the formation of radiate plaque patterns in the lawn of bacteria. In the case of RNA-phages of E. coli the formation of such trains of lysis depends on the choice of the nutritive medium. The addition of the detergent Fekunil 602 at different times after the contact between phages and host bacteria affects the length of the beams of lysis. The ionogenity of surfactants seems to be of importance for the formation of radiate plaque patterns, since the tested cationic compound and the nonionic surfactants, contrary to anionic surfactants, did not cause any beams of lysis.

[Labeling of yeast protoplasts by neutral red and nile blue for fusion experiments]. / Markierung von Hefeprotoplasten mit Neutralrot und Nilblau für Fusionsexperimente.

Neutral red and Nile blue were found to be suitable for staining protoplasts from various strains of Saccharomyces cerevisiae. The absorption of stains by the protoplasts was dependent on the pH value, for both stains. At a pH of 7.9 the protoplasts of the fusion partners could be stained differently and therefore it was possible to observe the fusion between the various strains of yeast. Consequently the prerequisites were created for the following micromanipulation.

[Effect of the detergent Metaupon on replication of various phages]. / Wirkung des Detergens Metaupon auf die Vermehrung verschiedener Phagen.

As several other surfactants do, the detergent Metaupon acts on the multiplication of bacteriophages. We investigated the influence of Metaupon on the phages phi and lambda, the cyanophage LPP-1, and the RNA-phages f 2, M 12, and Q beta by means of the agar diffusion test, pour plate test, adsorption test, and one-step growth test. The action of Metaupon on the free phages was also tested. Metaupon inhibits the formation of plaques by the phages with exception of lambda. With the phages f 2 and M 12 the substance increases the amount of plaques depending on concentration. The main mode of action of Metaupon was found to be the inhibition of the adsorption of the phages to the host cells. Only in the case of phi 105 free phages were inactivated.

[On the antiviral effect of a triazole compound (author's transl)]. / Zur antiviralen Wirkung einer Triazolverbindung.

4-[Hydroxy-3-piperid-N-yl-prop-1-yl]-5-methyl-2-phenyl-triazole (HMPT) reduced the plaque formation caused by M 12, f 2, and Q beta and retarded the liberation of phages. The concentration of tobacco mosaic virus in primarily infected tobacco leaves was decreased. HMPT inhibited the development of local lesions. Free phages and TMV particles werenot influenced by HMPT.

[Effect of 1,3,5-triazines on various bacteriophages and their hosts]. / Wirkung von 1,3,5-Triazinen auf verschiedene Prokaryontenviren und ihre Wirte.

In the agar diffusion test 24 triazines were investigated with regard to their action on the mulplication of DNA phages (lambda and LPP-1) and RNA phages (M12 and Qbeta). In several cases the amount of plaques was diminished or increased depending on the kind of triazine and virus. The investigations demonstrate the triazines to be able to interfere with the formation of plaques by virulent and temperate viruses of procaryotes.

[On the effect of some morpholinium compounds on the multiplication of RNA viruses (author's transl)]. / Zur Wirkung einiger Morpholinoverbindungen auf die Vermehrung von RNA-Viren.

In the present paper the authors report about the effect of N,N-dimethylmorpholinium chloride (DMMC), N,N-dimethyl-2-oxomorpholinium chloride (DMOMC), and N,N-diethyl-2-oxomorpholinium chloride (DEOMC) on the multiplication of tobacco mosaic virus (TMV), potato virus X (PVX), and cucumber mosaic virus (CMV) as well as the plaque formation by the RNA phages M 12, f 2, and Qbeta. The used morpholinium compounds do not influence strikingly the multiplication of phytoviruses. The results found by serological procedure and by bio-assay are indicated concordantly by the two methods. The plaque formation by bacteriophages is not influenced by DMMC, but enhanced significantly by DMOMC and DEOMC. These effects might be caused by the different hydrolytical behaviour of the morpholinium compounds tested.

Effect of root extract from Boerhaavia diffusa L., containing an antiviral principle upon plaque formation of RNA bacteriophages.

An extract obtained from the roots of Boerhaavia diffusa plants, which inhibits the infection of several plant viruses, was tested by the agar diffusion hole method for its action on RNA-containing bacterial viruses. Plaque formation of the phages was only partially and non-uniformly influenced by the extract so that a uniform principle of action was not realized for the RNA viruses of prokaryotic and eukaryotic host organisms.

Identification of two MADS box genes that are expressed in the apical meristem of the long-day plant Sinapis alba in transition to flowering.

To understand the molecular mechanisms involved in the transition from vegetative to reproductive growth, the photoperiodic-controlled induction of flowering in the long-day plant Sinapis alba was used to screen for regulatory genes which are expressed upon induction in the apical meristem. By using the conserved MADS box-encoding region of the organ identity gene AGAMOUS, the genes SaMADS A and SaMADS B were identified which are expressed in transition stages of mustard. RNA blot analysis has confirmed that the transcript levels of both genes are drastically increased shortly after the induction of flowering and that both genes are expressed earlier than the known MADS box genes. In situ hybridization studies have shown that the expression of the genes is restricted to the apical meristem of induced plants during early phases of reproductive development. The expression of SaMADS A is first detectable in the central zone of the meristem, a region where the earliest changes of an evoked meristem could be detected by classical physiological methods, suggesting that SaMADS A may have an important function during the transition to flowering.