Mother trees, altruistic fungi, and the perils of plant personification.

There are growing doubts about the true role of the common mycorrhizal networks (CMN or wood wide web) connecting the roots of trees in forests. We question the claims of a substantial carbon transfer from 'mother trees' to their offspring and nearby seedlings through the CMN. Recent reviews show that evidence for the 'mother tree concept' is inconclusive or absent. The origin of this concept seems to stem from a desire to humanize plant life but can lead to misunderstandings and false interpretations and may eventually harm rather than help the commendable cause of preserving forests. Two recent books serve as examples: The Hidden Life of Trees and Finding the Mother Tree.

Tools to compare antibody gold nanoparticle conjugates for a small molecule immunoassay.

Antibody gold nanoparticle conjugates as recognition elements are essential for the overall performance of lateral flow assays. When immobilizing antibodies on gold nanoparticles, the challenge is to prevent aggregation and to ensure that the antibodies are correctly oriented so that they remain functional and their paratopes remain accessible. There are many methods available, and it is difficult to decide which one to use. To help selecting the most appropriate conjugate production method, different synthetic routes of binding antibodies to gold nanoparticles are systematically investigated for the purpose of a quantitative lateral flow test for small molecules. The direct comparison of different conjugate syntheses shows how to select a suitable conjugate for a lateral flow assay. The syntheses examined are direct adsorption of antibody, direct adsorption of reduced antibody, covalent binding to polyethylene glycol linker, and binding via biotin-streptavidin interaction. The conjugates are characterized using UV-Vis spectroscopy and dynamic light scattering to determine their stability. Their performance on structured lateral flow test strips is examined using calibrations for different amitriptyline concentrations. It was shown that the best conjugate for quantification of amitriptyline was realized by direct adsorption of an UV-light irradiated antibody to gold nanoparticles. The methods employed can serve as a guide for selecting the most appropriate conjugate for an application and enhance the performance of lateral flow assays.

The α3 subunit of GABAA receptors promotes formation of inhibitory synapses in the absence of collybistin.

Signaling at nerve cell synapses is a key determinant of proper brain function, and synaptic defects-or synaptopathies-are at the basis of many neurological and psychiatric disorders. Collybistin (CB), a brain-specific guanine nucleotide exchange factor, is essential for the formation of γ-aminobutyric acidergic (GABAergic) postsynapses in defined regions of the mammalian forebrain, including the hippocampus and basolateral amygdala. This process depends on a direct interaction of CB with the scaffolding protein gephyrin, which leads to the redistribution of gephyrin into submembranous clusters at nascent inhibitory synapses. Strikingly, synaptic clustering of gephyrin and GABAA type A receptors (GABAARs) in several brain regions, including the cerebral cortex and certain thalamic areas, is unperturbed in CB-deficient mice, indicating that the formation of a substantial subset of inhibitory postsynapses must be controlled by gephyrin-interacting proteins other than CB. Previous studies indicated that the α3 subunit of GABAARs (GABAAR-α3) binds directly and with high affinity to gephyrin. Here, we provide evidence (i) that a homooligomeric GABAAR-α3A343W mutant induces the formation of submembranous gephyrin clusters independently of CB in COS-7 cells, (ii) that gephyrin clustering is unaltered in the neuronal subpopulations endogenously expressing the GABAAR-α3 in CB-deficient brains, and (iii) that exogenous expression of GABAAR-α3 partially rescues impaired gephyrin clustering in CB-deficient hippocampal neurons. Our results identify an important role of GABAAR-α3 in promoting gephyrin-mediated and CB-independent formation of inhibitory postsynapses.

Comparative Cytotoxic Activity of Wild Harvested Stems and In Vitro-Raised Protocorms of Dendrobium chryseum Rolfe in Human Cervical Carcinoma and Glioblastoma Cell Lines.

From the medicinal orchid Dendrobium chryseum Rolfe, which is used in traditional and folk Chinese medicine, the protocorms were raised in Murashige and Skoog (MS) media in three strengths, full strength (FMS), half strength (1/2 MS), and quarter strength (1/4 MS), with or without the phytohormones 6-benzylaminopurine (BAP) and 1-naphthaleneacetic acid (NAA) and coconut water (CW). The comparative cytotoxic activities of the wild and in vitro-raised protocorms were evaluated in human cervical carcinoma (HeLa) and human glioblastoma (U251) cell lines by MTT assay. In in vivo and in vitro, the methanol extracts of D. chryseum showed significant cytotoxic activities. Significant growth inhibition (%) and potent IC50 values were demonstrated in HeLa cell lines (49.79% (210.5 µg/mL) for in vitro-raised Dendrobium chryseum (DCT) versus 46.97% (226.5 µg/mL) for wild Dendrobium chryseum (DCW)). Similarly, activities against U251 cell lines exhibited also significant inhibition (28.76% (612.54 µg/mL) for DCW and 17.15% (1059.92 µg/mL) for DCT). The cytotoxic activities of both, wild and tissue-cultured samples, were superior in HeLa cells. In U251 cells, the wild sample was more active than the tissue-cultured one with a moderate cytotoxic effect. Hence, protocorm culture may therefore be a promising future tool for producing pharmacologically bioactive compounds in medicinal orchids. Such sustainable technology approach will minimize the pressure on the natural population of threatened but commercially important medicinal orchids.

Cytotoxic effect of selected wild orchids on two different human cancer cell lines.

Majority of the orchid species are used in the traditional medicines for the treatment of several diseases. They are the sources of polysaccharides, phenanthrenes, bibenzyl derivatives, revesteral, stilbenoids and polyphenol compounds. This study explored the cytotoxic activity of seven wild orchid species and identification of medicinally active compounds. The extracts of orchid species were screened for cytotoxic effect on the human cervical cancer cells (HeLa) and human glioblastoma cells (U251) using an MTT assay. The medicinally active compounds of high cytotoxic extracts were identified by GC-MS resulting in many stilbenoids and phenolic derivatives. The extract of Dendrobium transparens (DTs) and Vanda cristata (VCw) showed high cytotoxic effect towards the HeLa and U251 cell lines (IC50 of DTs: 382.14 µg/ml and 75.84 µg/ml respectively and IC50 of VCw: 317.23 µg/ml and 163.66 µg/ml respectively). This study concludes that they could be used as cancer therapeutics.

Advanced Boundary Electrode Modeling for tES and Parallel tES/EEG.

This paper explores advanced electrode modeling in the context of separate and parallel transcranial electrical stimulation (tES) and electroencephalography (EEG) measurements. We focus on boundary condition-based approaches that do not necessitate adding auxiliary elements, e.g., sponges, to the computational domain. In particular, we investigate the complete electrode model (CEM) which incorporates a detailed description of the skin-electrode interface including its contact surface, impedance, and normal current distribution. The CEM can be applied for both tES and EEG electrodes which are advantageous when a parallel system is used. In comparison to the CEM, we test two important reduced approaches: the gap model (GAP) and the point electrode model (PEM). We aim to find out the differences of these approaches for a realistic numerical setting based on the stimulation of the auditory cortex. The results obtained suggest, among other things, that GAP and GAP/PEM are sufficiently accurate for the practical application of tES and parallel tES/EEG, respectively. Differences between CEM and GAP were observed mainly in the skin compartment, where only CEM explains the heating effects characteristic to tES.

Optimized auditory transcranial alternating current stimulation improves individual auditory temporal resolution.

BACKGROUND: Temporal resolution of cortical, auditory processing mechanisms is suggested to be linked to peak frequency of neuronal gamma oscillations in auditory cortex areas (individual gamma frequency, IGF): Individuals with higher IGF tend to have better temporal resolution. HYPOTHESIS: Modulating ongoing gamma activity with transcranial alternating current stimulation (tACS) is expected to improve performance in gap detection (GD) tasks (shorter GD thresholds) if the frequency is higher and to decrease GD performance (longer GD thresholds) if the frequency is lower than IGF. METHODS: For 26 healthy participants the IGF and temporal resolution were identified using an auditory steady state response (ASSR) paradigm and a between-channel GD task. Finite element modelling was used to generate an optimized tACS electrode montage (one channel per hemisphere: FC5-TP7/P7 and FC6-TP8/P8). Afterwards, GD thresholds were examined during tACS (tACS frequency group A: above IGF, tACS frequency group B: below IGF). Relative changes of GD thresholds were compared between groups. Additionally, effects of tACS on oscillatory activity were investigated comparing relative changes of ASSR amplitudes before and after stimulation. RESULTS: Performance of group-A-participants improved significantly during tACS in comparison to performance of group-B-participants. Significant relative changes of ASSR amplitudes were found in both groups. CONCLUSION: The possibility to improve gap detection with individualized stimulation protocols for tACS further supports the link between oscillatory activity and temporal resolution, whereby the improvement of temporal resolution is particularly relevant for the clinical aspect of auditory tACS.

Impact of uncertain head tissue conductivity in the optimization of transcranial direct current stimulation for an auditory target.

OBJECTIVE: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique to modify neural excitability. Using multi-array tDCS, we investigate the influence of inter-individually varying head tissue conductivity profiles on optimal electrode configurations for an auditory cortex stimulation. APPROACH: In order to quantify the uncertainty of the optimal electrode configurations, multi-variate generalized polynomial chaos expansions of the model solutions are used based on uncertain conductivity profiles of the compartments skin, skull, gray matter, and white matter. Stochastic measures, probability density functions, and sensitivity of the quantities of interest are investigated for each electrode and the current density at the target with the resulting stimulation protocols visualized on the head surface. MAIN RESULTS: We demonstrate that the optimized stimulation protocols are only comprised of a few active electrodes, with tolerable deviations in the stimulation amplitude of the anode. However, large deviations in the order of the uncertainty in the conductivity profiles could be noted in the stimulation protocol of the compensating cathodes. Regarding these main stimulation electrodes, the stimulation protocol was most sensitive to uncertainty in skull conductivity. Finally, the probability that the current density amplitude in the auditory cortex target region is supra-threshold was below 50%. SIGNIFICANCE: The results suggest that an uncertain conductivity profile in computational models of tDCS can have a substantial influence on the prediction of optimal stimulation protocols for stimulation of the auditory cortex. The investigations carried out in this study present a possibility to predict the probability of providing a therapeutic effect with an optimized electrode system for future auditory clinical and experimental procedures of tDCS applications.

Using data from seed-dispersal modelling to manage invasive tree species: the example of Fraxinus pennsylvanica Marshall in Europe.

Management strategies to control invasive species need information about dispersal distances to predict establishment potential. Fraxinus pennsylvanica is a North American anemochorous tree species that is invasive in many Central European floodplain forests. To predict seed-dispersal potential, the stochastic model WaldStat was used, which enables different options for directionality (isotropic and anisotropic) to be simulated. In this article, we (1) show empirical results of fructification and seed dispersal for this tree species. The model predicts approximately 250,000 seeds for one F. pennsylvanica tree. These results were used to (2) calculate species-specific dispersal distances and effects of wind direction. To consider the influence of wind on dispersal potential of the tree species, long-distance dispersal (LDD [95th percentile dispersal distance]) was calculated. Mean dispersal distances varied between 47 and 66 m. LDD values modelled along the main wind direction ranged from 60 to 150 m. Seed production, dispersal distance, and direction data were (3) incorporated into theoretical management scenarios for forest ecosystems. Finally (4), we discuss management options and the practical relevance of model scenarios in relation to the accuracy of spatial dispersal predictions. Further analyses should be focused on possible, well-adapted management concepts at stand level that could restrict the potential spread of invasive species.

Finite-Element Model Predicts Current Density Distribution for Clinical Applications of tDCS and tACS.

Transcranial direct current stimulation (tDCS) has been applied in numerous scientific studies over the past decade. However, the possibility to apply tDCS in therapy of neuropsychiatric disorders is still debated. While transcranial magnetic stimulation (TMS) has been approved for treatment of major depression in the United States by the Food and Drug Administration (FDA), tDCS is not as widely accepted. One of the criticisms against tDCS is the lack of spatial specificity. Focality is limited by the electrode size (35 cm(2) are commonly used) and the bipolar arrangement. However, a current flow through the head directly from anode to cathode is an outdated view. Finite-element (FE) models have recently been used to predict the exact current flow during tDCS. These simulations have demonstrated that the current flow depends on tissue shape and conductivity. To face the challenge to predict the location, magnitude, and direction of the current flow induced by tDCS and transcranial alternating current stimulation (tACS), we used a refined realistic FE modeling approach. With respect to the literature on clinical tDCS and tACS, we analyzed two common setups for the location of the stimulation electrodes which target the frontal lobe and the occipital lobe, respectively. We compared lateral and medial electrode configuration with regard to their usability. We were able to demonstrate that the lateral configurations yielded more focused stimulation areas as well as higher current intensities in the target areas. The high resolution of our simulation allows one to combine the modeled current flow with the knowledge of neuronal orientation to predict the consequences of tDCS and tACS. Our results not only offer a basis for a deeper understanding of the stimulation sites currently in use for clinical applications but also offer a better interpretation of observed effects.

Urokinase plasminogen activator, uPAR, MMP-2, and MMP-9 in the C6-glioblastoma rat model.

BACKGROUND: In glioblastoma multiforme (GBM), the serine protease urokinase plasminogen activator (uPA), and matrix metalloproteases (MMP-2/MMP-9) contribute to its invasive growth pattern, which is the major obstacle to successful surgical treatment. MATERIALS AND METHODS: The expression of uPA was determined in monolayers and spheroids of the rodent GBM cell line C6 by immunohistochemistry and polymerase chain reaction (PCR). The longitudinal expression of proteases was studied in orthotopically implanted spheroids by semi-quantitative immunohistochemistry (IHC) in Sprague Dawley rats (n=40). The tumor volume was monitored by magnetic resonance imaging (MRI). RESULTS: In vitro, the GBM cell line C6 expresses high levels of uPA. In vivo, a continuous increase of uPA, uPA-receptor (uPAR), MMP-2, and MMP-9 expression was found in the infiltration zone. uPA was located exclusively in the infiltration zone and in the vascular basal layers. The mean tumor volume 23 days after implantation was 3.2 mm3. CONCLUSION: uPA, uPAR, MMP-2 and MMP-9 play an important role in GBM growth. Blockade of uPA and interruption of the proteolytic cascade could become a useful tool in the therapy of GBM.

Activation of the lectin pathway in murine lupus nephritis.

In systemic lupus erythematosus (SLE), hypocomplementaemia and complement deposition have been described both in man and in experimental models. A major involvement of the classical pathway of complement activation has been demonstrated in this disease, however relatively little is known about the involvement of the lectin pathway. Therefore in the present study we have analyzed the activity of all three pathways of complement activation in murine models of SLE. In the mouse, MBL is expressed in two forms, namely MBL-A and MBL-C. In the present study young and old MRL-lpr and control MRL+/+ mice were compared for the levels of complement activity with specific attention for the lectin pathway. It was found that upon aging of both MRL-lpr and MRL+/+ mice, a marked decrease in the activity of the classical pathway (CP) occurs. Levels of alternative pathway (AP) and lectin pathway (LP) activity remain unchanged. Key-molecules of these pathways, C1q, C3, MBL-A and MBL-C were analyzed and were all found to be decreased in aged mice of both strains. The levels of MBL-A and MBL-C showed a high degree of correlation and decreased equally. In aged MRL-lpr mice in which autoimmunity is most pronounced, we observed high autoantibody titers and strong deposition of glomerular immune complexes in association with deposition of C1q, C3, MBL-A and MBL-C. In conclusion, these data suggest that in addition to the classical pathway and the alternative pathway also the lectin pathway of complement activation is involved in murine lupus nephritis.

Influence of VEGF-R2 inhibition on MMP secretion and motility of microvascular human cerebral endothelial cells (HCEC).

Neovascularization and invasion are key features of malignant gliomas. Matrix metalloproteinases (MMPs) are supposed to play a major role mediating these processes. To analyze the expression patterns of MMPs in microvascular human cerebral endothelial cells (HCEC), we isolated endothelial cells from normal human brain microvessels. Characterization of cellular origin was performed by immunostaining, using the endothelial cell markers Ulex europaeus Agglutinin-1, von-Willebrand-Factor and Glucose-transporter-1. Contamination by other cell types was tracked by immunohistochemistry for GFAP (astrocytes), ASM (pericytes) and CD68 (macrophages). Secretion of MMPs was evaluated by ELISA and zymography. To determine whether HCEC show any difference in MMP expression compared to endothelial cells of other origin we analyzed human umbilical vein endothelial cells (HUVEC). HCEC show a decrease of MMP-3 and MMP-2 protein when treated with SU5416, a VEGF-R2 (KDR/flk-1) inhibitor, whereas MMP expression remained unchanged in HUVEC. To determine whether these findings show any effect in the motility of these cells we used a three-dimensional co-culture assay of avascular glioblastoma spheroids with primary HCEC spheroids. Untreated controls showed invasion of both cell populations into each other whereas treatment of the co-cultures with SU5416 resulted in complete inhibition of endothelial cell invasion hence indicating that flk-1 related motility of endothelial cells is critically involved in this process and can be studied with this assay. The results of different effects of anti-angiogenic treatment on proteolytic properties of two endothelial cell populations suggest that neovascularization of human brain tumors in vitro is dependent on the surrounding endothelial cell type and should therefore be studied with organ-specific human microvascular cerebral endothelial cells.

Characteristic gene expression profile of primary human cerebral endothelial cells.

Endothelial cells of blood vessels forming the interphase between systemic circulation and tissues are crucial for maintenance of homeostasis and organ-related functions. Recent experiments support organ-specific endothelial differentiation and suggest differential gene expression patterns in endothelial cells. Here, we compared gene expression in primary human cerebral endothelial cells (HCEC), which are major constituents of the blood brain barrier (BBB), with human umbilical vein endothelial cells (HUVEC) by using cDNA array analysis of 375 genes. Under basal culture conditions, 35 genes were expressed only in HCEC, whereas 20 gene transcripts were detected only in HUVEC. A total of 78 genes were expressed in both endothelial cell types partly with distinct expression levels. Genes expressed by cerebral endothelial cells are important in vasculo- and angiogenesis (VEGF, erbB1) and immunoregulation (OSM-Rbeta, decorin, IL-6) or have growth-supporting properties (brain-derived neurotrophic factor, stem cell factor, transforming growth factor-beta). The differential gene expression profiles were confirmed at the protein level of cell cultures (ELISA, immunoblotting) and human tissues (immunohistochemistry). Identification and further functional characterization of genes specifically expressed by cerebral endothelial cells will have important impact on our understanding of endothelial function at the BBB.