A microfluidic device for parallel 3-D cell cultures in asymmetric environments

We demonstrate a concept for how a miniaturized 3-D cell culture in biological extracellular matrix (ECM) or synthetic gels bridges the gap between organ-tissue culture and traditional 2-D cultures. A microfluidic device for 3-D cell culture including microgradient environments has been designed, fabricated, and successfully evaluated. In the presented system stable diffusion gradients can be generated by application of two parallel fluid flows with different composition against opposite sides of a gel plug with embedded cells. Culture for up to two weeks was performed showing cells still viable and proliferating. The cell tracer dye calcein was used to verify gradient formation as the fluorescence intensity in exposed cells was proportional to the position in the chamber. Cellular response to an applied stimulus was demonstrated by use of an adenosine triphosphate gradient where the onset of a stimulated intracellular calcium release also depended on cell position.     

Transition rates in97Tc

The de-excitation of the 215 keV $\text{7}\text{2}{}^{\mathrm{+}}$ and 324 keV $\text{5}\text{2}{}^{\mathrm{+}}$ levels in⁹⁷Tc, as observed in ⁹⁷Ru decay, was studied by means of internal conversion electron spectroscopy and the delayed electron-electron coincidence technique. From L-subshell intensity ratios, the E2 content in the 108 and 215 keV transitions were found to be (65 ± 12)% and (7 ± 4)%, respectively. The obtained level mean-lives were 0.75 ± 0.09 ns for the 324 keV level and 74 ± 15 ps for the 215 keV level.     

Photosynthetic Activity in Marine and Brackish Water Strains of Fucus vesiculosus and Fucus radicans (Phaeophyceae) at Different Light Qualities

This study investigates the effects of different light qualities on the photosynthetic capacity of the brown algae Fucus vesiculosus, from the Norwegian Sea, and Fucus radicans and F. vesiculosus, from the Bothnian Sea. The electron transport rates (ETR) obtained for F. vesiculosus from the Norwegian Sea showed significantly higher levels of light saturation compared with both species of algae from the Bothnian Sea. The maximum of ETR values for the Norwegian Sea strain showed no significant changes due to varying light quality compared with the initial values. For F. vesiculosus, from the Bothnian Sea, treatment with blue light showed an effect after 1 week of 30 and 90 μmol photons m^?2 s^?1 (P < 0.01), and for F. radicans from the Bothnian Sea, at the irradiance of 90 μmol photons m^?2 s^?1 and 1 week (P < 0.01). After 1 week in the Bothnian Sea species and after 2 weeks in F. vesiculosus from the Norwegian Sea, the photosynthetic efficiency (α) was significantly higher regardless of light quality and irradiance compared with the initial values. Variation in light quality and irradiance had minor effects on the F_v:F_m values of the three algal strains studied.     

Decay studies of Au isotopes in the mass number region 186–189

Internal conversion electrons and gamma-rays emitted in the decays of the neutron deficient gold isotopes with mass numbers 186–189 have been studied with a double focussing beta-ray spectrometer and a Ge(Li) detector. Multipolarities for the strongest transitions have been deduced. A revised level scheme for¹⁸⁹Pt is proposed. The half-lives of¹⁸⁶Au,¹⁸⁸Au and¹⁸⁹Au are found to be (10.7±0.5), (9.0±0.4) and (28.6±1.0) minutes respectively.     

Towards high-throughput single cell/clone cultivation and analysis

In order to better understand cellular processes and behavior, a controlled way of studying high numbers of single cells and their clone formation is greatly needed. Numerous ways of ordering single cells into arrays have previously been described, but platforms in which each cell/clone can be addressed to an exact position in the microplate, cultivated for weeks and treated separately in a high-throughput manner have until now been missing. Here, a novel microplate developed for high-throughput single cell/clone cultivation and analysis is presented. Rapid single cell seeding into microwells, using conventional flow cytometry, allows several thousands of single cells to be cultivated, short-term (72 h) or long-term (10-14 days), and analyzed individually. By controlled sorting of individual cells to predefined locations in the microplate, analysis of single cell heterogeneity and clonogenic properties related to drug sensitivity can be accomplished. Additionally, the platform requires remarkably low number of cells, a major advantage when screening limited amounts of patient cell samples. By seeding single cells into the microplate it is possible to analyze the cells for over 14 generations, ending up with more than 10 000 cells in each well. Described here is a proof-of-concept on compartmentalization and cultivation of thousands of individual cells enabling heterogeneity analysis of various cells/clones and their response to different drugs.