Imaging cytoplasmic cAMP in mouse brainstem neurons

Background  

cAMP is an ubiquitous second messenger mediating various neuronal functions, often as a consequence of increased intracellular Ca²⁺ levels. While imaging of calcium is commonly used in neuroscience applications, probing for cAMP levels has not yet been performed in living vertebrate neuronal tissue before.     

Steroide und Sexualhormone. 244. Mitteilung. Synthese der C-20 epimeren 7,8-Dihydrobatrachotoxinine

A novel synthesis leading to the C(20) epimeric 7,8-dihydroderivatives 16 [1] and 34 of batrachotoxinin A ( 1 ) [5] is described.     

Das 13C-INDOR-Spektrum des A3X-Systems einer Methylgruppe

The natural abundance ¹³C INDOR spectrum of the A₃X system of the methyl group in a substituted toluene was investigated at a very small value of the perturbing rf field H₂. The relative line intensities can be explained in terms of a redistribution of the equilibrium spin populations due to the polarizing field H₂. The double resonance method is suggested for accurate determination of the chemical shift of ¹³C in medium-size compounds where the carbon atom under consideration couples with only one set of magnetically equivalent hydrogen nuclei.     

Über kritische Drehzahlen unter pulsierender Torsion

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Book reviews

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Notices bibliographiques

     

Präparative Hochdruck-Säulenflüssigkeits-Chromatographie

Several aspects of the apparatus and column technology of modern preparative column liquid chromatography are described together with a review of the present state of the art. We can state: one can today so construct and fill preparative high-speed columns that the separation and isolation of individual components from mixtures in quantities sufficient for tentative identification (spectroscopic and CHN analysis c. 1 mg), structural elucidation, or mechanical, physical, electrical and last but not least, biological tests (ca. 100 mg) is possible. Additionally, by optimal use of “scale up” columns one can provide an additional tool, which may be used for research and development on the gram scale and may be described as a modern time- and money-saving technique. Unfortunately, up until now, only few systematic studies and applications which make full use of the preparative possibilities of modern column chromatography have been published. Only a few of the instrument manufacturers and accessory suppliers are active in this area. For this reason, compared to the rate of development in analytical aspects, the development of commercial preparative equipment is less well advanced. There remain, therefore, several questions open regarding apparatus and operation of such preparative columns, e.g. batch versus continuous operation, or maximum attainable diameter of columns.     

Isolating quantum coherences in structural imaging using intermolecular double-quantum coherence MRI

Intermolecular multiple-quantum coherence (iMQC) MR imaging provides a fundamentally different contrast mechanism. It allows probing tissue microstructure by tuning the direction and strength of the correlation gradient. However, iMQC images of a specific quantum-coherence can easily be contaminated by leakage signals from undesired quantum coherences (zero, single, and triple quantum coherence in this work). Using a modified double-quantum CRAZED imaging sequence, we show that signals originating from various coherence orders (M=0, 1, 2, 3) can be predicted in k-space and effectively isolated by means of a four-step phase cycling scheme and judicious choice of flip angles. Finally, preliminary data suggest the method to be able to provide information on trabecular bone architecture such as regional mean trabecular plate separation.     

Relationship between cancellous bone induced magnetic field and ultrastructure in a rat ovariectomy model

The site-dependent variations in trabecular bone morphology were studied in the rat tibia by magnitude and phase difference three-dimensional nuclear magnetic resonance microscopy and image processing, and the implications of ovariectomy were evaluated. Specimens excised from the proximal tibial metaphysis in ovariectomized (n = 7) and intact control (n = 4) rats were imaged at 9.4T with their anatomic axes parallel to the direction of the magnetic field. An echo-offset 3D rapid spin-echo excitation pulse sequence was used to generate phase difference maps, from which the standard deviation of the phase difference, sigma(delta psi), was calculated. In addition, a fictitious rate constant, R2', was calculated from the slope of the exponential portion of the Fourier transform of the phase difference histogram. Trabecular bone volume fraction was also determined in the same volume of interest. The results show strong correlations between bone volume fraction and both sigma(delta psi) and R2', suggesting that these parameters could be useful for nondestructive assessment of trabecular bone volume.