A tissue-like culture system using microstructures: influence of extracellular matrix material on cell adhesion and aggregation

Special microenvironmental conditions are required to induce and/or maintain specific qualities of differentiated cells. An important parameter is the three-dimensional tissue architecture that cannot be reproduced in conventional monolayer systems. Advanced tissue culture systems will meet many of these demands, but may reach their limits, especially when gradients of specific substances over distinct tissue layers must be established for long-term culture. These limitations may be overcome by incorporating microstructures into tissue-like culture systems. The microstructured cell support presented consists of a flat array of 625 cubic microcontainers with porous bottoms, in which cells can be supplied with specific media from both sides of the tissue layer. Permanent cell lines and primary rat hepatocytes have been used to test the culture system. In order to define reproducible conditions for tissue formation and for cell adherence to the structure, several ECM (extracellular matrix) components were tested for coating of microstructured substrata. The described tissue culture system offers great flexibility in adapting the cell support to specific needs.

Microsystems in medicine

The complexity of modern surgical and analytical methods requires the miniaturisation of many medical devices. The LIGA technique and also mechanical microengineering are well known for the batch fabrication of microsystems. Actuators and sensors are developed based on these techniques. The hydraulic actuation principle is advantageous for medical applications since the energy may be supplied by pressurised balanced salt solution. Some examples are turbines, pumps and valves. In addition, optical sensors and components are useful for analysis and inspection as represented by microspectrometers and spherical lenses. Finally, plastic containers with microporous bottoms allow a 3-dimensional growth of cell culture systems.

29Si CP/MAS NMR of phosphorus-bearing organosilicon compounds

While liquid-state 29Si NMR of phosphorus-bearing organosilicon compounds with more than one phosphorus per molecule can take advantage of the presence of J-coupling nJ(31P29Si) for purposes of structural assignment from J-coupling patterns, conventional 29Si CP/MAS spectra of such molecular solids do not reveal structural details in a straightforward manner. For such compounds it is necessary to obtain 29Si CP/MAS spectra under conditions of simultaneous 1H- and 31P-high power decoupling in order to derive reliable 29Si chemical shift information. 29Si CP/MAS NMR spectra, obtained with and without 31P high power decoupling during the acquisition time, of several organosilicon compounds containing SixPy (x = 1-10, y = 1-10) moieties are reported.

Determination of 113Cd shielding tensor components in cadmium-phosphine complexes from 31P-decoupled 113Cd cross-polarisation/magic angle spinning spectra

Owing to the simultaneous presence of various anisotropic interactions within the isolated M-31P and M(31P)2 fragments in solid transition metal phosphine complexes MX2.PR3 and MX2.2PR3 with, for instance, M = Cd, Hg or Pt, it is not normally possible to unequivocally determine the shielding tensor components of the metal nucleus M from simple 113Cd, 199Hg or 195Pt cross-polarisation/magic angle spinning (CP/MAS) spectra. In this paper it is shown that additional 31P on-resonance high-power decoupling during the acquisition time does allow the determination of the shielding tensor components of M from CP/MAS spectra. Two cadmium(II) complexes, Cd(OAc)2.Pchex3, (chex = cyclohexyl) and Cd(ClO4)2.2Pchex3 were chosen as examples; the 113Cd CP/MAS experiments were carried out at a low external magnetic field strength B0 = 2.35 T.

One- and two-dimensional 1H magic-angle spinning experiments on hydrous silicate glasses

Applications of various one- and two-dimensional 1H magic-angle spinning nuclear magnetic resonance (MAS NMR) techniques for the elucidation of structural properties of hydrous silicate glasses are described. Advantages and limitations of one-dimensional experiments [MAS and combined rotation and multiple-puls spectroscopy (CRAMPS)] and of two-dimensional approaches (spin-exchange experiments, "MAS-CRAMPS" correlation plus extended versions) are discussed. The various 1H MAS NMR techniques are illustrated by practical examples of spectra obtained from a hydrous silicate glass of Na2O.4SiO2.0.7H2O composition.

[Chorionic biopsy in prenatal chromosome diagnosis]

This paper reports on 110 chromosome analyses of prenatal diagnosis after chorion biopsy. Normal findings were recorded in 105 cases (51 female, 54 male), and 5 chromosomic abnormalities were found, including triploidy, rarely to be observed in the second trimester, and a trisomy 8. Both direct preparation and long-term cultures were employed for chromosome diagnosis. With long-term cultures, three mosaic findings were recorded that were not confirmed in subsequent examinations of amniotic cells. The observation of certain cells with female karyotype in a long-term culture with otherwise definitely male karyotype illustrates the necessity of polymorphic comparison in order to exclude maternal contamination in the analysis of long-term cultures.