Alterations of pancreatic beta-cell mass and islet number due to Ins2-controlled expression of Cre recombinase: RIP-Cre revisited; part 2.

Tissue-specific disruption of genes by targeted expression of Cre recombinase in insulin-producing cells has been widely used to explore pathways involved in regulation of pancreatic beta-cell mass. One particular line of transgenic mice [B6.Cg-Tg(Ins2-cre)25Mgn/J], commonly called RIP-Cre, in which the expression of Cre recombinase is controlled by a short fragment of the rat insulin II gene promoter has been used on at least 20 genes in at least 27 studies. In the majority of these studies (15 out of 27) inactivation of the gene of interest was associated with alterations in islet architecture, islet mass, or pancreatic insulin content. We have tested the hypothesis that genomic integration or expression of Cre recombinase alone causes alterations of beta-cell mass by quantifying islet number and mass in RIP-Cre mice. We have observed a significant hypoplasia of beta-cells in young RIP-Cre mice, and a significant hyperplasia of islets in older RIP-Cre animals. These findings suggest that glucose intolerance and impaired insulin secretion previously described for younger RIP-Cre mice might be caused by transgene-associated islet hypoplasia, and that hyperplasia in older mice might reflect a compensatory response to transgene-related glucose intolerance.     

Rehydration temperature is critical for metabolic competence and for membrane integrity in active dry yeast (ADY)

Respiration and fermentation were lower in active dry yeast (ADY) rehydrated at 0°C than in ADY rehydrated at 40°C. In agreement with other reports, it was found that membrane permeability increased during rehydration. In addition, ADY rehydrated at 0° did not reseal, even after hours of incubation at 40°C. Using ³²P-nuclear magnetic resonance it was found that the cellular concentration of sugar phosphates, phosphate, pyrophosphate, NADH and ATP were lower in ADY rehydrated at 0°C. In addition, the phospholipid peak had a higher height to broadness ratio at 0°C than at 40°C, suggesting that membranes in the 0° sample were more disordered. The lower fermentation rate in ADY rehydrated at 0° could not be due solely to membrane permeation since addition of cofactors that leaked from these cells did not reactivate fermentation. In cell free extracts or in toluenized cells it was observed that some activities were modified after rehydration at 0°C. In the 40°C sample a lower activity of pyruvate decarboxylase and higher fructose-1,6-bisphosphatase and ATPase activities were detected. As a result, higher levels of ADP and pyruvate were found in the cell. Higher ADP levels could contribute to the higher fermentation rate of the cells rehydrated at 40°C. Enzyme modification might explain the low viability of ADY observed by a plating method, even in cells that were impermeable to a vital dye.Abbreviations ADY Active dry yeast - MES 2(N-morpholino)-ethanesulfonic acid     

In vivo evaluation of bioprinted prevascularized bone tissue

Bioprinting can be considered as a progression of the classical tissue engineering approach, in which cells are randomly seeded into scaffolds. Bioprinting offers the advantage that cells can be placed with high spatial fidelity within three-dimensional tissue constructs. A decisive factor to be addressed for bioprinting approaches of artificial tissues is that almost all tissues of the human body depend on a functioning vascular system for the supply of oxygen and nutrients. In this study, we have generated cuboid prevascularized bone tissue constructs by bioprinting human adipose-derived mesenchymal stem cells (ASCs) and human umbilical vein endothelial cells (HUVECs) by extrusion-based bioprinting and drop-on-demand (DoD) bioprinting, respectively. The computer-generated print design could be verified in vitro after printing. After subcutaneous implantation of bioprinted constructs in immunodeficient mice, blood vessel formation with human microvessels of different calibers could be detected arising from bioprinted HUVECs and stabilization of human blood vessels by mouse pericytes was observed. In addition, bioprinted ASCs were able to synthesize a calcified bone matrix as an indicator of ectopic bone formation. These results indicate that the combined bioprinting of ASCs and HUVECs represents a promising strategy to produce prevascularized artificial bone tissue for prospective applications in the treatment of critical-sized bone defects.     

Effect of matrine on primary human hepatocytes in vitro

Matrine is a bioactive component of the traditional Chinese medical herb Sophora flavescens that has been used in China to treat various kinds of diseases including virus hepatitis. However, the molecular mechanisms underlying its hepatoprotective effects remains elusive. In the present study, primary human hepatocytes were employed to elucidate the protective effects and molecular mechanisms of matrine. We observed that low concentrations of matrine had no significant impact on albumin secretion, but high concentrations (>140 mg/L) of matrine decreased the albumin secretion in hepatocytes. Western blot data indicated that matrine at 140 mg/L at 72 h induced protein expression of CYP2A6, CYP2B6 and CYP3A4. Furthermore, high concentrations of matrine reduced LDH and AST levels and were cytotoxic to hepatocytes, leading to a decreased cell viability and total protein amount. Moreover, low concentrations of matrine, enhanced the ECOD activity and decreased the level of NO₂⁻ induced by cytokines in human hepatocytes. Taken together, the present study sheds novel light on the molecular mechanisms of matrine and potential application of matrine in hepatic diseases.

Electronic supplementary material

The online version of this article (doi:10.1007/s10616-013-9680-1) contains supplementary material, which is available to authorized users.     

Effects of Spider Chemotactile Cues on Arthropod Behavior

Predation risk can strongly affect the behavior of prey species. However, empirical evidence for changes in behavior driven by spider cues is restricted to relatively few taxa. Here, we conducted a series of behavioral experiments to test for changes in activity among a wide range of terrestrial arthropods. We confronted 13 insect and eight spider species with chemotactile cues of three spider species. We applied two different experimental setups: In the ‘no-choice experiment’ prey individuals were either put on control filter papers or on filter papers previously occupied by a spider. In the ‘choice experiment’, the prey individuals were able to choose between filter paper halves with and without spider cues. In both setups, the response to spider cues depended significantly on prey species, with some species increasing and others decreasing their activity. Surprisingly few prey species responded to the spider cues at all. Our results indicate that predator recognition upon contact with cue bearing filter papers is strongly prey-specific and that behavioral effects driven by spider chemotactile cues are an exception rather than the rule among terrestrial arthropods.     

Response of Benthic Foraminifera to Organic Matter Quantity and Quality and Bioavailable Concentrations of Metals in Aveiro Lagoon (Portugal)

This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to metals enrichment.     

Influence of temperature changes on migraine occurrence in Germany

Many factors trigger migraine attacks. Weather is often reported to be one of the most common migraine triggers. However, there is little scientific evidence about the underlying mechanisms and causes. In our pilot study, we used smartphone apps and a web form to collect around 4,700 migraine messages in Germany between June 2011 and February 2012. Taking interdiurnal temperature changes as an indicator for changes in the prevailing meteorological conditions, our analyses were focused on the relationship between temperature changes and the frequency of occurrence of migraine attacks. Linear trends were fitted to the total number of migraine messages with respect to temperature changes. Statistical and systematic errors were estimated. Both increases and decreases in temperature lead to a significant increase in the number of migraine messages. A temperature increase (decrease) of 5 °C resulted in an increase of 19?±?7 % (24?±?8 %) in the number of migraine messages.     

A Novel Cytotoxic Cerium Complex: Aquatrichloridobis(1,10‐phenanthroline)cerium(III) (KP776). Synthesis,Characterization, Behavior in H2O,Binding towards Biomolecules,and Antiproliferative Activity

The lanthanide complex aquatrichloridobis(1,10‐phenanthroline)cerium(III) [Ce(phen)₂(H₂O)Cl₃] (KP776) was fully characterized by elemental analysis, IR‐, and ¹H‐ and ¹³C‐NMR spectroscopy, as well as TG/DTA measurements, and its behavior in H₂O, important for the application as a chemotherapeutic, was studied. In addition, the binding of KP776 to nucleotides and single serum proteins was investigated by capillary electrophoresis, whereas binding to proteins in human plasma was observed by ICP‐MS. The compound shows promising anticancer properties in vitro: proliferation of human cancer cell lines is strongly inhibited with IC₅₀ values in the very low micromolar range.     

Attention Modulates Visual-Tactile Interaction in Spatial Pattern Matching

Factors influencing crossmodal interactions are manifold and operate in a stimulus-driven, bottom-up fashion, as well as via top-down control. Here, we evaluate the interplay of stimulus congruence and attention in a visual-tactile task. To this end, we used a matching paradigm requiring the identification of spatial patterns that were concurrently presented visually on a computer screen and haptically to the fingertips by means of a Braille stimulator. Stimulation in our paradigm was always bimodal with only the allocation of attention being manipulated between conditions. In separate blocks of the experiment, participants were instructed to (a) focus on a single modality to detect a specific target pattern, (b) pay attention to both modalities to detect a specific target pattern, or (c) to explicitly evaluate if the patterns in both modalities were congruent or not. For visual as well as tactile targets, congruent stimulus pairs led to quicker and more accurate detection compared to incongruent stimulation. This congruence facilitation effect was more prominent under divided attention. Incongruent stimulation led to behavioral decrements under divided attention as compared to selectively attending a single sensory channel. Additionally, when participants were asked to evaluate congruence explicitly, congruent stimulation was associated with better performance than incongruent stimulation. Our results extend previous findings from audiovisual studies, showing that stimulus congruence also resulted in behavioral improvements in visuotactile pattern matching. The interplay of stimulus processing and attentional control seems to be organized in a highly flexible fashion, with the integration of signals depending on both bottom-up and top-down factors, rather than occurring in an ‘all-or-nothing’ manner.