Synthesis and Cellular Labeling of Caged Phosphatidylinositol Derivatives

Phosphatidylinositol (PI) is the biosynthetic precursor for seven phosphoinositides, important signaling lipids in cells. A membrane-permeant caged PI derivative featuring a photo-removable coumarinyl group masking the negative charge of the phosphate, as well as two enzymatically removable butyrate esters for increased lipophilicity and for preventing phosphate migration, were synthesized. Rapid cell entry and cellular labeling in fixed cells was demonstrated by a photo-cross-linkable diazirine followed by attachment of a fluorophore through click chemistry. Using this technique, we found that the multifunctional caged PI derivative resided predominantly at internal membranes but rapidly changed to the plasma membrane after uncaging. Accordingly, a preliminary proteomic analysis of the lipid–protein conjugates revealed that the two major PI transport proteins PITPα and β were prime targets of the photo-cross-linked PI derivative.     

In vivo mapping of functional domains and axonal connectivity in cat visual cortex using magnetic resonance imaging

Noninvasive cognitive neuroimaging studies based on functional magnetic resonance imaging (fMRI) are of ever-increasing importance for basic and clinical neurosciences. The explanatory power of fMRI could be greatly expanded, however, if the pattern of the neuronal circuitry underlying functional activation could be made visible in an equally noninvasive manner. In this study, blood oxygenation level-dependent (BOLD)-based fMRI and diffusion tensor imaging (DTI) were performed in the same cat visual cortex, and the foci of fMRI activation utilized as seeding points for 3D DTI fiber reconstruction algorithms, thus providing the map of the axonal circuitry underlying visual information processing. The methods developed in this study will lay the foundation for in vivo neuroanatomy and the ability for noninvasive longitudinal studies of brain development.     

On the Law of The Iterated Logarithm for Rapidly Increasing Subsequences

The usual law of the iterated logarithm states that the partial sums S_n of independent and identically distributed random variables can be normalized by the sequence a_n = √nlog log n, such that limsup_n→∞ S_n/a_n = √2 a.s. As has been pointed out by Gut (1986) the law fails if one considers the limsup along subsequences which increase faster than exponentially. In particular, for very rapidly increasing subsequences {n_k≥1} one has limsup_k→∞ S_nk/a_nk = 0 a.s. In these cases the normalizing constants a_nk have to be replaced by √nk log k to obtain a non-trivial limiting behaviour: limsup_k→∞ S_nk/ √nk log k = √2 a.s. We will present an intelligible argument for this structural change and apply it to related results.     

Polymer chain dynamics under nanoscopic confinements

It is shown that the confinement of polymer melts in nanopores leads to chain dynamics dramatically different from bulk behavior. This so-called corset effect occurs both above and below the critical molecular mass and induces the dynamic features predicted for reptation. A spinodal demixing technique was employed for the preparation of linear poly(ethylene oxide) (PEO) confined to nanoscopic strands that are in turn embedded in a quasi-solid and impenetrable methacrylate matrix. Both the molecular weight of the PEO and the mean diameter of the strands were varied to a certain degree. The chain dynamics of the PEO in the molten state was examined with the aid of field-gradient NMR diffusometry (time scale, 10(-2)-10(0) s) and field-cycling NMR relaxometry (time scale, 10(-9)-10(-4) s). The dominating mechanism for translational displacements probed in the nanoscopic strands by either technique is shown to be reptation. On the time scale of spin-lattice relaxation time measurements, the frequency dependence signature of reptation (i.e., T1 approximately nu(3/4)) showed up in all samples. A "tube" diameter of only 0.6 nm was concluded to be effective on this time scale even when the strand diameter was larger than the radius of gyration of the PEO random coils. This corset effect is traced back to the lack of the local fluctuation capacity of the free volume in nanoscopic confinements. The confinement dimension is estimated at which the crossover from confined to bulk chain dynamics is expected.     

The <Emphasis Type="Italic">recombination activation gene 1</Emphasis> (<Emphasis Type="Italic">Rag1</Emphasis>) is expressed in a subset of zebrafish olfactory neurons but is not essential for axon targeting or amino acid detection

Background  

Rag1 (Recombination activation gene-1) mediates genomic rearrangement and is essential for adaptive immunity in vertebrates. This gene is also expressed in the olfactory epithelium, but its function there is unknown.     

1-Ethoxycarbonyl-3-ferrocenyl-propan-1,3-dion und Ferrocen-1,1'bis(2,4-dioxobutansäureethylester) als Liganden für Übergangsmetallionen. Kristallstruktur von Bis(1-ethoxycarbonyl-3-ferrocenyl-propan-1,3dionato)kupfer(II)

1-Ethoxycarbonyl-3-ferrocenyl-propane-1,3-dion and Ferrocene-1,1′bis(2,4-dioxobutanoic acid ethylester) as Ligands for Transition Metal Ions. Crystal Structure of Bis(1-ethoxycarbonyl-3-ferrocenyl-propane-1,3dionato)copper(II) The ligands 1-ethoxycarbonyl-3-ferrocenyl-propane-1,3-dion and ferrocene-1,1′-bis(2,4-dioxo-butanoic acid ethylester) have been prepared by reaction of acetylferrocene or 1,1′-diacetylferrocene and diethyl oxalate. They yield neutral chelates with Cu^II, Ni^II, Zn^II, Co^II, and Mn^II. The acid dissociation constants of the ligands and the stability constants of their metal complexes including Fe^II complexes are reported. The structure of bis(1-ethoxycarbonyl-3-ferrocenyl-propane-1,3-dionato)copper(II) was determined by X-ray structure analysis. A cis arrangement with a nearly square planar coordination sphere at the Cu atom is found.     

Preparation of Cr2O3-Al2O3 Solid Solutions by Reactive Magnetron Sputtering

 (Al,Cr)₂O₃ layers were deposited on cemented carbide insert tips at a substrate temperature of 500 °C by means of reactive magnetron sputtering. An Al target was sputtered in RF mode and a Cr target in DC mode simultaneously in an oxygen/argon plasma. The influence of the Al and Cr sputter power and of the oxygen partial pressure on composition and structure of the (Al,Cr)₂O₃ layers as well as on the binding states of their components were investigated. Special attention was paid to the interpretation of the O ls and O-KLL fine structure and peak shifts. For the binary phases γ-Al₂O₃ and Cr₂O₃, a good agreement with literature values was observed in each case. In case of the ternary phases a continuous shift of the energetic position of the O1s peak, the O-KL₂₃L₂₃ transition and the modified Auger parameter α ′ of oxygen between the two binary phases γ-Al₂O₃ and Cr₂O₃ could be detected, indicating a wide range of solid solubility between Al₂O₃ and Cr₂O₃. As revealed by grazing incidence X-ray diffraction, the crystallinity of the ternary phases is less pronounced as compared to the binaries and increases with increasing oxygen flow rate.     

Noise power spectra and recovery rates obtained with different nebulizer systems in ICP atomic emission spectrometric analyses in the case of different types of salts and salt contents

The features of different nebulizer systems (cross-flow-, Meinhard- and GMK-system) in the ICP atomic emission spectrometric analyses of solutions with different contents of different salts were evaluated. As basis for the comparison of the nebulizer systems the recovery rates and noise power spectra were used. Both showed that the GMK-system could be used for the widest diversity of salts (sodium chloride, ammonium sulfate and sodium tetraborate) and concentration range (0–10% (m/v)) followed by the cross-flow-system and the Meinhard-system in ICP-OES using a 1 kW argon ICP. Of all nebulizer systems the nebulizer according to Meinhard has the lowest performance for the salts investigated. The noise power spectra of all nebulizer systems are dominated by interference noise from the sample introduction system. This noise increases with the salt concentration of the solution and the GMK-system shows the lowest increase, followed by the cross-flow- and Meinhard-system. Received: 11 October 1999 / Revised: 5 January 2000 / Accepted: 14 January 2000     

Determination of amines used in the oil and gas industry (upstream section) by ion chromatography

During production and purification of crude oil and natural gas several different amines are used as chemicals or operating materials, e.g. film forming long chain amines as corrosion inhibitors, steam volatile amines for pH correction and corrosion protection, alkanolamines as absorbents in sour gas treatment plants, etc. For analytical checks, e.g. determination of corrosion inhibitor concentration in produced media, classical chemical methods are used predominantly, because most of them can be performed in small field laboratories. Some amines, especially the small molecular aliphatic and heterocyclic amines can also be determined by ion chromatography. In our laboratory two types of separation columns (IonPac CS10 and CS12A) were available for ion chromatographic separation. The analysis of the amines in low-salt-containing water, soft water or steam condensate can be performed without problems. The presence of alkali and/or alkaline earth ions in the sample can lead to coelution with these ions, to poor peak resolution or enhanced analysis times, depending on the chromatographic conditions. This work shows some examples of ion chromatography applications for the determination of low-mo1ecular-mass ethanolamines, morpholine and piperazine and discusses the possible interferences and troubles caused by alkali and alkaline earth ions in the matrix.