The mass spectra of diethylstilbestrol and related compounds

The low resolution mass spectra of E-3,4-bis-(p-hydroxyphenyl)-hex-3-ene (diethylstilbestrol), E-[1,1,1-3H3]3,4-bis-(p-hydroxyphenyl)-hex-3-ene, E-2,3-bis-(p-hydroxyphenyl)-but-2-ene (dimethylstilbestrol), E,E-3,4-bis-(p-hydroxyphenyl)hexa-2,4-diene (dienestrol) and 3,4-bis-(p-hydroxyphenyl)-hexane (hexestrol) were examined as the parent compounds, their diacetates, dimethyl ethers, and bis-trimethylsilyl ethers. In addition, the mass spectra of the diethyl ether and the hexadeuteriodimethyl ether of E-3,4-bis-(p-hydroxyphenyl)-hex-3-ene were studied. Each compound gives rise to several sets of characteristic fragment ions associated with loss of alkyl groups, loss of aryl groups and rearrangements. An ion of m/e 165 (C13H9) was found in the spectra of all the compounds studied. With the aid of high resolution mass spectrometry empirical formulae were assigned to major ions of the free diphenols.     

Autoantibodies against p53 are not increased in human ascites and pleural effusions

 Mutated human p53 may give rise to the formation of autoantibodies and may be a marker for a worse prognosis. We speculated that ascites or pleural effusions may enhance the formation of such autoantibodies in cancer patients and, therefore, we measured the presence of autoantibodies in the ascites or pleural effusion of 40 patients with advanced malignancies. As controls, p53 autoantibodies were measured in 15 patients with effusions who did not have a malignancy. Using a specific enzyme-linked immunosorbent assay, p53 autoantibodies could only be detected in the effusions of 5/40 patients (12.5%) with known malignancies. The formation of autoantibodies did not correlate with the presence or absence of tumor cells in the effusion. The effusions of the patients without tumor were all negative for p53 autoantibodies. Our study shows that malignant or reactive effusions do not stimulate the local or systemic production of autoantibodies against p53. Received: 14 November 1995 / Accepted: 8 February 1996     

Observations on the function of a slowly-adapting mechanoreceptor associated with filoplumes in the feathered skin of pigeons

Summary The response properties of a slowlyadapting mechanoreceptor located at the base of filoplumes in the feathered skin of the pigeon have been studied electrophysiologically. Both a strong dynamic component and an irregular firing rate and a cold-sensitivity show considerable similarity to the type SA I receptor in the mammalian skin whose morphological basis is a Merkel cell receptor. The functional characteristics have been studied with regard to excitation under natural conditions. The filoplumes are usually associated with contour feathers and excitation occurs only during lateral displacement of contour feather or movement of filoplume. This points to a role of the SA receptor in sensing disorders of the plumage. This is supported by the finding that one afferent fiber innervates only one feather which means a high spacial resolution. Furthermore a possible role in bird flight is discussed.Abbreviation SA slowly-adapting     

A mosquito predator survey in Townsville, Australia, and an assessment of Diplonychus sp. and Anisops sp. predatorial capacity against Culex annulirostris mosquito immatures.

A twelve-month survey for mosquito predators was conducted in Townsville, Queensland, Australia, which is located in the arid tropics. The survey revealed the presence of five predaceous insects but only Anisops sp. (backswimmers) and Diplonychus sp. were common. Predatorial capacity and factors influencing this capacity were then assessed for adult Anisops sp. and adult and nymph stages of Diplonychus sp. against Culex annulirostris mosquito immatures under laboratory conditions. Predatorial capacity bioassays showed that adult Diplonychus sp. preyed upon both larval and pupal stages of Cx. annulirostris quite successfully. Nymphs of Diplonychus sp. proved to be more successful with smaller prey immatures, and Anisops sp adults did not prey successfully on any prey pupae. Increasing the foraging area and introducing aquatic vegetation significantly reduced the predatorial capacity of Diplonychus sp. nymphs, while only vegetation and not foraging area had a significant effect on adult Diplonychus sp. predation capacity. Overall, adult Diplonychus sp. proved to be a more efficient predator than Anisops sp., and field trials are now recommended to further assess the potential of Diplonychus sp. as a biocontrol agent.     

Zentrifugalversuche mit Kernteilungen

Ohne ZusammenfassungMit 21 Textabbildungen.     

Reduction in Turgor Pressure as a Result of Extremely Brief Exposure to CO(2)

CO₂ depresses water influx into sunflower hypocotyl segments of low water potential; by contrast, it stimulates flux into segments of high water potential. When segments of high potential were placed in a series of mannitol concentrations and allowed to achieve steady rates of water uptake, influx into CO₂-treated tissue in a solution of 3 atm equalled that into control tissue in water. Reasons are given for deducing that a change in internal osmotic concentration (π_i) of the order of 40% would be necessary to account for this result on the basis of π_i. Direct measurements (by cryoscopy and by the minimum volume method) detected no difference in the steady state value for π_i as between CO₂-treated and control tissue. It was therefore concluded that CO₂ had caused some reduction in turgor pressure.

Water uptake into tissue treated with CO₂ for only the first 2 minutes of a 30-minute period was equal to that into tissue treated continuously with CO₂, i.e. 3 times the control value. Ten seconds' CO₂ treatment produced a significant stimulation. When the cycles of treatment were repeated the samples receiving flashes of CO₂ maintained a rate of water uptake superior to that of the control, whereas influx into continuously treated tissue fell below the control value after 1 hour.

CO₂ treatment applied in a moist air chamber stimulated subsequent water influx when the tissue was transferred to water. Fifteen seconds' treatment was sufficient to produce a marked effect. Even when a transition period of 30 minutes in the moist chamber was interposed between CO₂ treatment (5 minutes) and transfer to water, a stimulation was observed. The CO₂ effect could be achieved at zero degrees; 5 minutes' treatment in the moist chamber at zero degrees, followed by a 15-minute transition period at the same temperature, substantially increased subsequent water uptake at 25°.

     

Individually Adapted Imagery Improves Brain-Computer Interface Performance in End-Users with Disability

Brain-computer interfaces (BCIs) translate oscillatory electroencephalogram (EEG) patterns into action. Different mental activities modulate spontaneous EEG rhythms in various ways. Non-stationarity and inherent variability of EEG signals, however, make reliable recognition of modulated EEG patterns challenging. Able-bodied individuals who use a BCI for the first time achieve - on average - binary classification performance of about 75%. Performance in users with central nervous system (CNS) tissue damage is typically lower. User training generally enhances reliability of EEG pattern generation and thus also robustness of pattern recognition. In this study, we investigated the impact of mental tasks on binary classification performance in BCI users with central nervous system (CNS) tissue damage such as persons with stroke or spinal cord injury (SCI). Motor imagery (MI), that is the kinesthetic imagination of movement (e.g. squeezing a rubber ball with the right hand), is the "gold standard" and mainly used to modulate EEG patterns. Based on our recent results in able-bodied users, we hypothesized that pair-wise combination of "brain-teaser" (e.g. mental subtraction and mental word association) and "dynamic imagery" (e.g. hand and feet MI) tasks significantly increases classification performance of induced EEG patterns in the selected end-user group. Within-day (How stable is the classification within a day?) and between-day (How well does a model trained on day one perform on unseen data of day two?) analysis of variability of mental task pair classification in nine individuals confirmed the hypothesis. We found that the use of the classical MI task pair hand vs. feed leads to significantly lower classification accuracy - in average up to 15% less - in most users with stroke or SCI. User-specific selection of task pairs was again essential to enhance performance. We expect that the gained evidence will significantly contribute to make imagery-based BCI technology become accessible to a larger population of users including individuals with special needs due to CNS damage.     

Massive light-dependent cycling of inorganic carbon between oxygenic photosynthetic microorganisms and their surroundings

Membrane inlet mass spectrometry indicated massive light-dependent cycling of inorganic carbon between the medium and the cells of various phytoplankton species representing the main groups of aquatic primary producers. These included diatoms, symbiotic and free living dinoflagellates, a coccolithophorid, a green alga and filamentous and single cell cyanobacteria. These organisms could maintain an ambient CO₂ concentration substantially above or below that expected at chemical equilibrium with HCO₃ ⁻. The coccolithophorid Emiliania huxleyishifted from net CO₂ uptake to net CO₂ efflux with rising light intensity. Differing responses of CO₂ uptake and CO₂ fixation to changing light intensity supported the notion that these two processes are not compulsorily linked. Simultaneous measurements of CO₂ and O₂ exchange and of the fluorescence parameters in Synechococcus sp. strain PCC 7942, showed that CO₂ uptake can serve as a sensitive probe of the energy status of the photosynthetic reaction centers. However, during transitions in light intensity, changes in CO₂ uptake did not accord with those expected from fluorescence change. Quantification of the net fluxes of CO₂, HCO₃ ⁻ and of photosynthesis at steady-state revealed that substantial HCO₃ ⁻ efflux accompanied CO₂ uptake and fixation in the case of `CO<sub>2</sub> users'. On the other hand, `HCO₃ ⁻ users' were characterized by a rate of net CO₂ uptake below that of CO₂ fixation. The results support the notion that entities associated with the CCM function not only in raising the CO₂ concentration at the site of Rubisco; they may also serve as a means of diminishing photodynamic damage by dissipating excess light energy. This revised version was published online in August 2006 with corrections to the Cover Date.