Bar-Ilan University

About: Bar-Ilan University is a education organization based out in Ramat Gan, Israel. It is known for research contribution in the topics: Population & Poison control. The organization has 12835 authors who have published 34964 publications receiving 995648 citations. The organization is also known as: Bar Ilan University & BIU.

Remote Magnetic Orientation of 3D Collagen Hydrogels for Directed Neuronal Regeneration

Abstract: Hydrogel matrices are valuable platforms for neuronal tissue engineering. Orienting gel fibers to achieve a directed scaffold is important for effective functional neuronal regeneration. However, current methods are limited and require treatment of gels prior to implantation, ex-vivo, without taking into consideration the pathology in the injured site. We have developed a method to control gel orientation dynamically and remotely in situ. We have mixed into collagen hydrogels magnetic nanoparticles then applied an external magnetic field. During the gelation period the magnetic particles aggregated into magnetic particle strings, leading to the alignment of the collagen fibers. We have shown that neurons within the 3D magnetically induced gels exhibited normal electrical activity and viability. Importantly, neurons formed elongated cooriented morphology, relying on the particle strings and fibers as supportive cues for growth. The ability to inject the mixed gel directly into the injured site as a solutio...

Generation of peripheral sensory and sympathetic neurons and neural crest cells from human embryonic stem cells.

Abstract: Human embryonic stem cells (hESCs) have been directed to differentiate into neuronal cells using many cell-culture techniques. Central nervous system cells with clinical importance have been produced from hESCs. To date, however, there have been no definitive reports of generation of peripheral neurons from hESCs. We used a modification of the method of Sasai and colleagues for mouse and primate embryonic stem cells to elicit neuronal differentiation from hESCs. When hESCs are cocultured with the mouse stromal line PA6 for 3 weeks, neurons are induced that coexpress (a) peripherin and Brn3a, and (b) peripherin and tyrosine hydroxylase, combinations characteristic of peripheral sensory and sympathetic neurons, respectively. In vivo, peripheral sensory and sympathetic neurons develop from the neural crest (NC). Analysis of expression of mRNAs identified in other species as NC markers reveals that the PA6 cells induce NC-like cells before neuronal differentiation takes place. Several NC markers, including SNAIL, dHAND, and Sox9, are increased at 1 week of coculture relative to naive cells. Furthermore, the expression of several NC marker genes known to be downregulated upon in vivo differentiation of NC derivatives, was observed to be present at lower levels at 3 weeks of PA6-hESC coculture than at 1 week. Our report is the first on the expression of molecular markers of NC-like cells in primates, in general, and in humans, specifically. Our results suggest that this system can be used for studying molecular and cellular events in the almost inaccessible human NC, as well as for producing normal human peripheral neurons for developing therapies for diseases such as familial dysautonomia.

Orchestrating rapid long-distance signaling in plants with Ca2+, ROS and electrical signals

Abstract: Plants show a rapid systemic response to a wide range of environmental stresses, where the signals from the site of stimulus perception are transmitted to distal organs to elicit plant-wide responses. A wide range of signaling molecules are trafficked through the plant, but a trio of potentially interacting messengers, reactive oxygen species (ROS), Ca2+ and electrical signaling ('trio signaling') appear to form a network supporting rapid signal transmission. The molecular components underlying this rapid communication are beginning to be identified, such as the ROS producing NAPDH oxidase RBOHD, the ion channel two pore channel 1 (TPC1), and glutamate receptor-like channels GLR3.3 and GLR3.6. The plant cell wall presents a plant-specific route for possible propagation of signals from cell to cell. However, the degree to which the cell wall limits information exchange between cells via transfer of small molecules through an extracellular route, or whether it provides an environment to facilitate transmission of regulators such as ROS or H+ remains to be determined. Similarly, the role of plasmodesmata as both conduits and gatekeepers for the propagation of rapid cell-to-cell signaling remains a key open question. Regardless of how signals move from cell to cell, they help prepare distant parts of the plant for impending challenges from specific biotic or abiotic stresses.

An Efficient Protocol for Secure Two-Party Computation in the Presence of Malicious Adversaries

Abstract: We show an efficient secure two-party protocol, based on Yao's construction, which provides security against malicious adversaries. Yao's original protocol is only secure in the presence of semi-honest adversaries, and can be transformed into a protocol that achieves security against malicious adversaries by applying the compiler of Goldreich, Micali, and Wigderson (the "GMW compiler"). However, this approach does not seem to be very practical as it requires using generic zero-knowledge proofs. Our construction is based on applying cut-and-choose techniques to the original circuit and inputs. Security is proved according to the ideal/real simulation paradigm, and the proof is in the standard model (with no random oracle model or common reference string assumptions). The resulting protocol is computationally efficient: the only usage of asymmetric cryptography is for running $$O(1)$$ O ( 1 ) oblivious transfers for each input bit (or for each bit of a statistical security parameter, whichever is larger). Our protocol combines techniques from folklore (like cut-and-choose) along with new techniques for efficiently proving consistency of inputs. We remark that a naive implementation of the cut-and-choose technique with Yao's protocol does not yield a secure protocol. This is the first paper to show how to properly implement these techniques, and to provide a full proof of security. Our protocol can also be interpreted as a constant-round black-box reduction of secure two-party computation to oblivious transfer and perfectly hiding commitments, or a black-box reduction of secure two-party computation to oblivious transfer alone, with a number of rounds which is linear in a statistical security parameter. These two reductions are comparable to Kilian's (20th STOC, 1988) reduction, which uses OT alone but incurs a number of rounds which is linear in the depth of the circuit.

Tyrosine Phosphorylation of Protein Kinase Cδ Is Essential for Its Apoptotic Effect in Response to Etoposide

Abstract: Protein kinase Cδ (PKCδ) is involved in the apoptosis of various cells in response to diverse stimuli. In this study, we characterized the role of PKCδ in the apoptosis of C6 glioma cells in response to etoposide. We found that etoposide induced apoptosis in the C6 cells within 24 to 48 h and arrested the cells in the G1/S phase of the cell cycle. Overexpression of PKCδ increased the apoptotic effect induced by etoposide, whereas the PKCδ selective inhibitor rottlerin and the PKCδ dominant-negative mutant K376R reduced this effect compared to control cells. Etoposide-induced tyrosine phosphorylation of PKCδ and its translocation to the nucleus within 3 h was followed by caspase-dependent cleavage of the enzyme. Using PKC chimeras, we found that both the regulatory and catalytic domains of PKCδ were necessary for its apoptotic effect. The role of tyrosine phosphorylation of PKCδ in the effects of etoposide was examined using cells overexpressing a PKCδ mutant in which five tyrosine residues were mutated to phenylalanine (PKCδ5). These cells exhibited decreased apoptosis in response to etoposide compared to cells overexpressing PKCδ. Likewise, activation of caspase 3 and the cleavage of the PKCδ5 mutant were significantly lower in cells overexpressing PKCδ5. Using mutants of PKCδ altered at individual tyrosine residues, we identified tyrosine 64 and tyrosine 187 as important phosphorylation sites in the apoptotic effect induced by etoposide. Our results suggest a role of PKCδ in the apoptosis induced by etoposide and implicate tyrosine phosphorylation of PKCδ as an important regulator of this effect.