Functional scaffold-free 3-D cardiac microtissues: a novel model for the investigation of heart cells.

To bridge the gap between two-dimensional cell culture and tissue, various three-dimensional (3-D) cell culture approaches have been developed for the investigation of cardiac myocytes (CMs) and cardiac fibroblasts (CFs). However, several limitations still exist. This study was designed to develop a cardiac 3-D culture model with a scaffold-free technology that can easily and inexpensively generate large numbers of microtissues with cellular distribution and functional behavior similar to cardiac tissue. Using micromolded nonadhesive agarose hydrogels containing 822 concave recesses (800 µm deep × 400 µm wide), we demonstrated that neonatal rat ventricular CMs and CFs alone or in combination self-assembled into viable (Live/Dead stain) spherical-shaped microtissues. Importantly, when seeded simultaneously or sequentially, CMs and CFs self-sorted to be interspersed, reminiscent of their myocardial distribution, as shown by cell type-specific CellTracker or antibody labeling. Microelectrode recordings and optical mapping revealed characteristic triangular action potentials (APs) with a resting membrane potential of -66 ± 7 mV (n = 4) in spontaneously contracting CM microtissues. Under pacing, optically mapped AP duration at 90% repolarization and conduction velocity were 100 ± 30 ms and 18.0 ± 1.9 cm/s, respectively (n = 5 each). The presence of CFs led to a twofold AP prolongation in heterogenous microtissues (CM-to-CF ratio of 1:1). Importantly, Ba(2+)-sensitive inward rectifier K(+) currents and Ca(2+)-handling proteins, including sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a, were detected in CM-containing microtissues. Furthermore, cell type-specific adenoviral gene transfer was achieved, with no impact on microtissue formation or cell viability. In conclusion, we developed a novel scaffold-free cardiac 3-D culture model with several advancements for the investigation of CM and CF function and cross-regulation.

Exceptional, potentially fatal combination of emphysematous pancreatitis and gas-forming cholecystitis: successful multidisciplinary conservative treatment supported by repeated CT-staging.

Usually considered as a life-threatening disease, emphysematous pancreatitis requires early diagnosis and aggressive multidisciplinary treatment including the Departments of Gastroenterology, Intensive Care Medicine, Interventional Radiology and even Surgery. The prognosis for emphysematous cholecystitis is also quite poor. It requires surgery even if a percutaneous cholecystostomy can contribute to a temporary stabilization of the patient. Computed tomography is the imaging modality of choice to detect emphysematous pancreatitis and gas-forming cholecystitis. It enables their grading and helps identify their complications. Moreover, it proves essential in the follow-up of the lesions.

[Orbita - anatomy, development and deformities]. / Orbita - Anatomie, Entwicklung und Fehlbildungen.

The development of the structures of the human orbita is very complex, but understanding the development makes it easier to understand normal anatomy and dysplasia. The following article first discusses the embryonic development of the eye structures and then presents the "normal" radiological anatomy using different investigation techniques and the most common deformities.

[CNS infections in immunocompromised patients]. / ZNS-Infektionen bei immunsupprimierten Patienten.

CNS infections caused by infective agents are rare in immunocompetent hosts, but more frequent in immunocompromised patients. In addition, the spectrum of causative agents is completely different. There are no pathognomonic alterations in radiologic imaging, even in clinically severely ill patients imaging is often non-specific or inconspicious. This article gives a review of the most frequent infective agents and image alterations. Modern radiology is not yet able to replace the gold standard of pathogen detection.

[Treatment of arteriosclerotic diseases of the carotid artery. The carotid stent]. / Behandlung der arteriosklerotischen Erkrankung der A. carotis. Der Karotisstent.

In order to find the most suitable therapy concept for patients with severe stenosis of the carotid bifurcation (>70%), knowledge on the currently available treatment methods is necessary. In addition to carotid endarterectomy, medication therapy and stent angioplasty are also available. The outcome after stent angioplasty must be considered under the aspects of rapid technical development and increasing experience. Results of studies are still only of limited value with respect to the development of protection systems, flexible guiding catheters, low profile and more visible stents and balloons as well as using thrombocyte aggregation.

[Magnetic resonance spectroscopy for inflammatory brain diseases]. / Magnetresonanzspektroskopie bei entzündlichen Hirnerkrankungen.

Magnetic resonance spectroscopy (MRS) is a non-invasive method for investigation of cerebral metabolite concentrations in various pathologic conditions. The clinical use of MRS for intracranial disorders is well established. In this review the characteristic MRS findings for the most important inflammatory brain diseases will be discussed.

[CNS infections in immunocompetent patients]. / ZNS-Infektionen bei immungesunden Patienten.

This article gives a review of the most frequent infective agents reasonable for CNS infections in immunocompetent patients as well as their localisation and imaging specifications. MRI scanning is the gold standard to detect inflammatory conditions in the CNS. Imaging can be normal or nonspecifically altered although the infection is culturally or bioptically proven. There are no pathognomonic, pathogen-specific imaging criteria. The localization and dimension of the inflammation depends on the infection pathway.

Phytochrome-mediated long-term memory of seeds.

The question is how long phytochrome, stored within the cytoplasm of plant diaspores, may stimulate their germination. This question arose from the observation that soil cultivations in darkness for weed control gave inconsistent results. Namely, after a single nighttime or daytime cultivation during spring and summer, differences in weed emergence became hardly detectable after a period of six weeks. However, after nighttime and daytime cultivations in late autumn, emergence differences persisted for up to nine months. To examine whether this differing memory effect is phytochrome-mediated, seeds of Chenopodium album and Stellaria media were sown in pots with wet peat, either in daylight or after sunset. In the latter, seeds were irradiated with far-red light for one day prior to being covered and buried. For more than two years the far-red irradiated seeds produced significantly reduced emergence, indicating that germination and emergence of weeds in the field may be supported by maternal far-red absorbing seed phytochrome B(fr) over several months or even years. This conclusion allows refining of the strategy of lightless tillage.

The action spectrum for maximal photosensitivity of germination.

Fruits of Garden Lettuce, imbibed in 0.01 M KNO3, were depleted of maternal active phytochrome B by saturating deep-red exposure and photosensitized by chilling for 1 week at 4 degrees C. Twenty saturated fluence-response curves for photoinduced germination were elaborated between 300 and 800 nm, using exposure periods from 6 to 600 s at 22.5 degrees C; there is linear and closely parallel regression in the logarithmic probability net. The reciprocals of the half-response fluences obtained gave the apparent conversion spectrum of the controlling pigments and this was corrected for the transmittance of the seed-coat. It is a phytochrome spectrum of Pr with photoconversion cross-sections of 1.2 x 10(9) and 4.5 x 10(3) m2 mol-1 at 666 and 800 nm, respectively. This means that for half-saturated germination of sensitized seed, fewer than 1 out of 200,000 phytochrome A molecules have to be photoconverted to Pfr, and no photo-reversibility by deep-red was found. Therefore, all spectral colours of nightly moon- or skylight should stimulate the germination of sensitized weed seeds if they are exposed at the soil surface between sequential tillage operations.

Delineation of structural domains in eukaryotic 5S rRNA with a rhodium probe.

The three-dimensional folding of Xenopus oocyte 5S rRNA has been examined using the coordination complex Rh(phen)2phi3+ (phen = phenanthroline; phi = phenanthrenequinone diimine) as a structural probe. Rh(phen)2phi3+ binds neither double-helical RNA nor unstructured single-stranded regions of RNA. Instead, the complex targets through photoactivated cleavage sites of tertiary interaction which are open in the major groove and accessible to stacking. The sites targeted by the rhodium complex have been mapped on the wild-type Xenopus oocyte RNA, on a truncated RNA representing the arm of the molecule comprised of helix IV-loop E-helix V, and on several single-nucleotide mutants of the 5S rRNA. On the wild-type 5S rRNA, strong cleavage is found at residues U73, A74, A101, and U102 in the E loop and U80 and G81 in helix IV; additional sites are evident at A22 and A56 in the B loop, C29 and A32 in helix III, and C34, C39, A42, and C44 in the C loop. Given the similarity observed in cleavage between the full 5S RNA and the truncated fragment as well as the absence of any long-range effects on cleavage in mutant RNAs, the results do not support models which involve long-range tertiary interactions. Cleavage results with Rh(phen)2phi3+ do, however, indicate that the apposition of several noncanonical bases as well as stem--loop junctions may result in intimately stacked structures with opened major grooves. In particular, on the basis of cleavage results on mutant RNAs, both loops C and E represent structures where the strands constituting each loop are not independent of one another but are intrinsically structured.(ABSTRACT TRUNCATED AT 250 WORDS)

Conformational studies of the nucleic acid binding sites for Xenopus transcription factor IIIA.

The CD spectrum of a restriction fragment that contains a single copy of a Xenopus borealis somatic 5 S rRNA gene, like those of two smaller fragments from the binding site for transcription factor IIIA (TFIIIA), is that of B-form DNA. Under dehydrating conditions (76% ethanol) the 5 S rDNA undergoes a transition into an A conformation. The spectra of the three fragments, however, do exhibit some perturbation in that the longwave positive peaks are shifted to shorter wavelengths and have enhanced rotational strength compared with reference B-form spectra. The helical repeats measured for the smaller fragments indicate that the helix winding angle can account for these features in the CD spectra. We suggest that G:C-rich boxes that punctuate not only the TFIIIA binding site but the whole 5 S gene are responsible for the conformational perturbation manifest in the CD spectra and may play a role in the recognition of the DNA by the factor. The spectrum of the gene is unchanged in the presence of TFIIIA, indicating that the structural heterogeneity of the DNA persists upon complex formation. The CD spectra of native TFIIIA.5 S rRNA particles isolated from oocytes and of particles reconstituted in vitro are identical and only moderately different from the spectrum of free 5 S rRNA, suggesting that the protein effects only limited changes in the secondary and/or tertiary structure of the RNA. The helical structure of the two binding sites is discussed with respect to a common mode of interaction of TFIIIA with DNA and RNA.

[The effects of night breaks on flowering of sinapis alba L]. / Die Wirkung von "Störlicht" auf die Blütenbildung von Sinapis alba L.

The induction of flowering in mustard (Sinapis alba L.) was studied by means of night-breaks ("Störlicht"). The plants were cultivated under fully controlled conditions: 8000 Lux white light (mixed fluorescent and incandescent) 18°C, 80% relative humidity. Raised under our conditions in short days (8 hours of white light) mustard behaved as a quantitative long-day plant (Fig. 2). Flowering can be promoted by long-day treatment (Fig. 3). The long day (16 hours of white light) can be replaced by a short day plus a night-break. The highest effectiveness of the night-break is found near the middle of the dark period (Figs. 4, 5). -The spectral dependence of flower induction was studied with blue, green, yellow, red (Fig. 1) and far-red light using a 2-hour break near the middle of the dark period. The dose response curves (Fig. 6) and the action spectrum (Fig. 7) indicate a very strong effectiveness in the blue part of the spectrum, a small response in red and yellow light and no response at all in green and far-red light. The participation of phytochrome is indicated (Table 1), but no far-red reversibility could be detected (Table 2). Simultaneous irradiation with red and far-red light yielded significant enhancement effects (Fig. 8). In view of the strong shadowing in the leaves (Figs. 9, 10) these data are interpretable on the basis of phytochrome.

Morphogenesis in Trichoderma: Action spectrum of photoinduced sporulation.

An action spectrum for photoinduced sporulation (conidia formation) in Trichoderma viride is presented. The detectable quantum efficiency was between 350 and 550 nm with peaks near 380 and 440 nm with a minimum at about 400 nm. Essentially no sporulation occurred at 254 nm or from 525 to 1100 nm. The half maximum response is reached with 6.6·10(-10) Einstein/cm(2) at 447 nm.