Nanomoulding of Functional Materials,a Versatile Complementary Pattern Replication Method to Nanoimprinting

We describe a nanomoulding technique which allows low-cost nanoscale patterning of functional materials, materials stacks and full devices. Nanomoulding combined with layer transfer enables the replication of arbitrary surface patterns from a master structure onto the functional material. Nanomoulding can be performed on any nanoimprinting setup and can be applied to a wide range of materials and deposition processes. In particular we demonstrate the fabrication of patterned transparent zinc oxide electrodes for light trapping applications in solar cells.     

Photosynthesis supported by a chlorophyll f-dependent,entropy-driven uphill energy transfer in Halomicronema hongdechloris cells adapted to far-red light

Photosynthesis Research - The phototrophic cyanobacterium Halomicronema hongdechloris shows far-red light-induced accumulation of chlorophyll (Chl) f, but the involvement of the pigment in...     

Stem cells: cross-talk and developmental programs

The thesis advanced in this essay is that stem cells-particularly those in the nervous system-are components in a series of inborn 'programs' that not only ensure normal development, but persist throughout life so as to maintain homeostasis in the face of perturbations-both small and great. These programs encode what has come to be called 'plasticity'. The stem cell is one of the repositories of this plasticity. This review examines the evidence that interaction between the neural stem cell (as a prototypical somatic stem cell) and the developing or injured brain is a dynamic, complex, ongoing reciprocal set of interactions where both entities are constantly in flux. We suggest that this interaction can be viewed almost from a 'systems biology' vantage point. We further advance the notion that clones of exogenous stem cells in transplantation paradigms may not only be viewed for their therapeutic potential, but also as biological tools for 'interrogating' the normal or abnormal central nervous system environment, indicating what salient cues (among the many present) are actually guiding the expression of these 'programs'; in other words, using the stem cell as a 'reporter cell'. Based on this type of analysis, we suggest some of the relevant molecular pathways responsible for this 'cross-talk' which, in turn, lead to proliferation, migration, cell genesis, trophic support, protection, guidance, detoxification, rescue, etc. This type of developmental insight, we propose, is required for the development of therapeutic strategies for neurodegenerative disease and other nervous system afflictions in humans. Understanding the relevant molecular pathways of stem cell repair phenotype should be a priority, in our view, for the entire stem cell field.     

Artifact production in the assay of anhydroecgonine methyl ester in serum using gas chromatography-mass spectrometry

The detection of the pyrolysis product anhydroecgonine methyl ester (AEME, methylecgonidine) after cocaine smoking using gas chromatography-mass spectrometry is hampered by the artifactual production of AEME. The amount of AEME increases with the amount of cocaine used producing false positive values in authentic samples. A method for the correction of quantitative values was established using calibration of pyrolysis and estimation of the artifactual AEME. Authentic AEME in serum was differentiated from the artifact above 3.5 microg/l, 99% prediction limits of the quantitation were +/-3.1 microg/l. In 16 serum samples and five postmortem blood samples, cocaine and AEME were detected, but after application of the correction method only ten were truly positive for AEME.     

Effects of a plant product consisting of green tea and curcuma extract on milk production and the expression of hepatic genes involved in endoplasmic stress response and inflammation in dairy cows

During the periparturient phase, cows are typically in an inflammation-like condition, and it has been proposed that inflammation associated with the induction of stress of the endoplasmic reticulum (ER) in the liver contributes to the development of fatty liver syndrome and ketosis. In the present study, the hypothesis that supplementation of dairy cows with a plant product consisting of green tea (95%) and curcuma extract (5%) rich in polyphenols attenuates inflammation and ER stress in the liver during early lactation was investigated. Twenty-seven cows were assigned to two groups, either a control group (n = 14) or a treatment group (n = 13). Both groups of cows received a total mixed ration, and the ration of the treatment group was supplemented with 0.175 g of the plant product per kg dry matter from week 3 prepartum to week 9 postpartum. Dry matter intake and energy balance during week 2 to week 9 postpartum were not different between the two groups. However, cows supplemented with the plant product had a greater amount of energy-corrected milk during week 2 to week 9 postpartum and lower concentrations of triacylglycerols and cholesterol in the liver in week 1 and week 3 postpartum than cows of the control group (p < 0.05). Cows supplemented with the plant product showed a trend towards a reduced mRNA concentration of haptoglobin (p < 0.10), while relative mRNA concentrations of eight genes of the unfolded protein response considered in the liver were not different between the two groups of cows. Relative hepatic mRNA concentration of fibroblast growth factor, a stress hormone induced by various stress conditions, was reduced at week 1 and week 3 postpartum in cows supplemented with the plant product (p < 0.05). Overall, the data of this study suggest that – although there were only minor effects on the occurrence of ER stress and inflammation – a supplementation of polyphenols might be useful to improve milk yield and prevent fatty liver syndrome in dairy cows.     

Cross-Sectional Comparison of Small Animal [18F]-Florbetaben Amyloid-PET between Transgenic AD Mouse Models

We aimed to compare [¹⁸F]-florbetaben PET imaging in four transgenic mouse strains modelling Alzheimer’s disease (AD), with the main focus on APPswe/PS2 mice and C57Bl/6 mice serving as controls (WT). A consistent PET protocol (N = 82 PET scans) was used, with cortical standardized uptake value ratio (SUVR) relative to cerebellum as the endpoint. We correlated methoxy-X04 staining of β-amyloid with PET results, and undertook ex vivo autoradiography for further validation of a partial volume effect correction (PVEC) of PET data. The SUVR in APPswe/PS2 increased from 0.95±0.04 at five months (N = 5) and 1.04±0.03 (p<0.05) at eight months (N = 7) to 1.07±0.04 (p<0.005) at ten months (N = 6), 1.28±0.06 (p<0.001) at 16 months (N = 6) and 1.39±0.09 (p<0.001) at 19 months (N = 6). SUVR was 0.95±0.03 in WT mice of all ages (N = 22). In APPswe/PS1G384A mice, the SUVR was 0.93/0.98 at five months (N = 2) and 1.11 at 16 months (N = 1). In APPswe/PS1dE9 mice, the SUVR declined from 0.96/0.96 at 12 months (N = 2) to 0.91/0.92 at 24 months (N = 2), due to β-amyloid plaques in cerebellum. PVEC reduced the discrepancy between SUVR-PET and autoradiography from −22% to +2% and increased the differences between young and aged transgenic animals. SUVR and plaque load correlated highly between strains for uncorrected (R = 0.94, p<0.001) and PVE-corrected (R = 0.95, p<0.001) data. We find that APPswe/PS2 mice may be optimal for longitudinal amyloid-PET monitoring in planned interventions studies.     

The Ca2+-binding protein calretinin is selectively enriched in a subpopulation of the epithelial rests of Malassez

During tooth development, the inner and outer enamel epithelia fuse by mitotic activity to produce a bilayered epithelial sheath termed Hertwig’s epithelial root sheath (HERS). The epithelial rests of Malassez (ERM) are the developmental residues of HERS and remain in the adult periodontal ligament (PDL). Although the cellular regulation of the Ca²⁺-binding proteins parvalbumin, calbindin-D28k, and calretinin has been reported in the inner and outer enamel epithelia during tooth development, an involvement of Ca²⁺-binding proteins in the ERM has not so far been characterized. Among the three Ca²⁺-binding proteins tested (calbindin D28k, parvalbumin, calretinin), we have only been able to detect calretinin in a subpopulation of adult rat molar ERM, by using quantitative immunohistochemical and confocal immunofluorescence techniques. TrkA (a marker for ERM) is present in numerous epithelial cell clusters, whereas calretinin has been localized in the cytosol and perinuclear region of a subpopulation of TrkA-positive cells. We conclude that, in inner and outer enamel epithelial cells, Ca²⁺ is regulated by calbindin, parvalbumin, and calretinin during tooth development, whereas in the ERM of adult PDL, Ca²⁺ is regulated only by calretinin. The expression of Ca²⁺-binding proteins is restricted in a developmental manner in the ERM.     

Stem cells act through multiple mechanisms to benefit mice with neurodegenerative metabolic disease

Intracranial transplantation of neural stem cells (NSCs) delayed disease onset, preserved motor function, reduced pathology and prolonged survival in a mouse model of Sandhoff disease, a lethal gangliosidosis. Although donor-derived neurons were electrophysiologically active within chimeric regions, the small degree of neuronal replacement alone could not account for the improvement. NSCs also increased brain beta-hexosaminidase levels, reduced ganglioside storage and diminished activated microgliosis. Additionally, when oral glycosphingolipid biosynthesis inhibitors (beta-hexosaminidase substrate inhibitors) were combined with NSC transplantation, substantial synergy resulted. Efficacy extended to human NSCs, both to those isolated directly from the central nervous system (CNS) and to those derived secondarily from embryonic stem cells. Appreciating that NSCs exhibit a broad repertoire of potentially therapeutic actions, of which neuronal replacement is but one, may help in formulating rational multimodal strategies for the treatment of neurodegenerative diseases.     

Strategies for gathering structural information on unknown peaks in the GC/MS analysis of Corynebacterium glutamicum cell extracts

A comprehensive analysis of low molecular weight compounds in biological samples by the hyphenated method of GC/MS in general detects a large number of peaks which can not be identified by searching of commercially available mass spectral libraries. Therefore, more information is required for a successful identification of these compounds. Some structural features like molecular weight and number of derivatization groups present in the molecule can be determined by variation of the derivatization prior to GC/MS. The use of deuterated derivatizing reagents and the newly developed N-methyl-N-ethyldimethylsilyl-trifluoracetamide for this purpose is described. The knowledge of these structural properties alone undoubtedly will not lead to the structure elucidation of novel metabolites. However, it may be helpful in identifying derivatives of known metabolites or artifacts. Thus, by use of the molecular weight as search criterion it is possible to find plausible candidates in metabolic pathway databases. It is shown that the application of this method to a hydrophilic extract of C. glutamicum lead to the identification of 31 in previous analyses unidentified peaks, in their majority representing minor derivatives of common metabolites.