Polarization holograms allow highly efficient generation of complex light beams.

We report a viable method to generate complex beams, such as the non-diffracting Bessel and Weber beams, which relies on the encoding of amplitude information, in addition to phase and polarization, using polarization holography. The holograms are recorded in polarization sensitive films by the interference of a reference plane wave with a tailored complex beam, having orthogonal circular polarizations. The high efficiency, the intrinsic achromaticity and the simplicity of use of the polarization holograms make them competitive with respect to existing methods and attractive for several applications. Theoretical analysis, based on the Jones formalism, and experimental results are shown.

Novel path to IL-6 trans-signaling through thrombin-induced soluble IL-6 receptor release by platelets.

Interleukin (IL)-6 is a multifunctional cytokine with a critical role in inflammatory, immunoregulatory and haemopoietic responses. Its receptor consists of an ubiquitously expressed membrane transducing element (gp130) and of the specific element IL-6R-alpha (gp80), present only on hepatocytes and some leukocyte subsets. IL-6R-alpha also exists as soluble protein (sIL-6R) that, in the presence of IL-6, forms a complex able to bind gp130 and, thanks to the mechanism called trans-signaling, transduces IL-6 effect through tyrosine phosphorylation and activation of the signal transducer and transcription activator (STAT)-3. The aim of this study was to analyze the bidirectional relationships between platelet aggregation and IL-6-dependent effects. While platelets do not produce IL-6, we found that resting platelets express gp130, but not gp80, on their membranes. Upon activation by thrombin or calcium ionophore A23187, but not by ADP, the IL-6R-alpha is released in soluble form, while cangrelor, the specific inhibitor of P2Y12 receptor, can partially inhibit sIL-6R release. This sIL-6R is biologically active and, in the presence of IL-6, can trigger IL-6 trans-signaling, inducing an autocrine activation loop (as measured by an increase in gp80 and gp130 content) and STAT3 phosphorylation. On the other hand, IL-6 trans-signaling has no effect on platelet degranulation or aggregation by itself, nor on thrombin-induced platelet aggregation. Our data add an important piece to the puzzle of thrombosis and inflammation: in the presence of IL-6, which can be produced by stressed endothelial cells, the platelet-derived IL-6 trans-signaling could be crucial for the evolution of inflammation within a damaged vessel.

Skeletal muscle cells: from local inflammatory response to active immunity.

The skeletal muscles are the major living component of the human body. They are constituted by stable cells, the myofibres, and by adult multipotent stem cells, the satellite cells, which can multiply to regenerate and repair the damaged tissues. Injections of DNA in muscle cells have been used to produce recombinant proteins with opposite goals: somatic reparation of genetic defects, which needs to elicit no inflammatory or immune response, and DNA vaccination, which needs a robust immune response. Because of possible therapeutical interventions, a growing body of information is being produced dealing with every aspect of the myofibres during inflammatory and autoimmune responses: skeletal muscle-antigen presenting cell (APC) interaction and intrinsic APC capabilities of myoblasts and myocytes, the response to released cytokines and their endogenous production, the regulation of Toll-like receptors and major histocompatibility complex expression. According to these data, the muscle tissue is now emerging no longer as a passive bystander, but more as an active player that, when correctly manipulated, can drive tolerance or immunization to these de novo produced proteins. In the present review, we summarize the recent developments on the control of muscle immune function.

Maintenance of the differentiated state in skeletal muscle: activation of v-Src disrupts sarcomeres in quail myotubes.

We have used quail skeletal myotubes expressing a temperature-sensitive allele of the v-src oncogene to address the issue of the homeostasis of sarcomeric myofibrils in differentiated muscle cells. Reactivation of the v-Src tyrosine kinase by shifting the cultures to the permissive temperature leads within minutes to the formation of F-actin-containing bodies (ABs), that originate in the ventral region of the myotubes and increase in number concomitantly with the dismantling of the I-Z-I complex of the sarcomeres. This process is detailed by confocal and electron microscopy. Indirect immunofluorescence reveals that ABs contain muscle-specific protein isoforms associated with the I-Z-I complexes and vinculin, a component of the cytoskeletal network. Anti-phosphotyrosine antibodies label proteins in ABs and Z-discs. Evidence is presented indicating that this phenomenon specifically depends on the persistent activation of v-Src, rather than on a general increase in phosphotyrosine content such as that induced by vanadate. AB formation is prevented by activation of protein kinase C by phorbol ester or by treatment with the kinase inhibitor 2-aminopurine, without any detectable effect on tyrosine phosphorylation. Taken together these findings indicate that phosphorylation of specific target proteins by v-Src, although necessary, is not sufficient per se to induce AB formation. In addition, the signal transduction cascade that culminates in MAP kinase activation and its nuclear translocation is activated both by v-Src and phorbol ester, and is relatively unaffected by 2-aminopurine. These findings imply that both phorbol esters and 2-aminopurine operate, at least in part, at the level of alternative pathways that may diverge upstream of the MAP kinase and are presumably mediating the early effects of v-Src on the differentiated phenotype.

Tunable Surface Patterning of Azopolymer by Vectorial Holography: The Role of Photoanisotropies in the Driving Force.

The capability to pattern polymer surfaces at different length scales is an important goal in different research fields, including display technologies, microelectronics, optics, as well as biorelated and medical science. However, the ability to optically and dynamically manipulate topography is a key feature enabling remote control of associated effects/processes mediated by the surface. Azopolymers are largely investigated to this aim based on their sensitivity to optical fields and reconfigurability capabilities. In this work, surface relief formation induced by polarization patterns on an amorphous azopolymer structurally engineered to have large photoinduced birefringence has been investigated both experimentally and theoretically. Based on the different light polarization patterns, depth and shape of the relief grating can be controlled. An optically induced gradient force model that includes both the spatial distribution and the anisotropy of the material permittivity has been theoretically analyzed. The proposed approach is able to explain the experimental results and to overcome the limitation of existing models.

Surface-induced photorefractivity in twistable nematics: toward the all-optical control of gain.

We report the first two-beam coupling investigation of the surface-induced photorefractive effect (SIPRE) in optically twistable nematic liquid crystal cell. The unique space-charge field of SIPRE is exploited to achieve optical tuning of the photorefractive gain. A reconfigurable photoaligning substrate is used to adjust the twist angle, which is proved to be a control parameter for the photorefractive gain. The amplitude of the optical modulation increases gradually with the twist. Its phase shift changes from 0 degrees to 90 degrees with the polarization state of the two interfering beams. These results pave the way to the all-optical control of the photorefractive gain.

Electrically tunable two-dimensional liquid crystals gratings induced by polarization holography.

Two-dimensional (2D) gratings made up of an array of differently twisted nematic structures are obtained by crossed assembling of 1D polarization holograms recorded at the photoaligning substrates. The rotating linear polarization pattern, produced by the interference of two opposite circularly polarized beams, is recorded on the azo-dye doped polyimide aligning layers. The 2D gratings diffract light in different directions with different polarization states, that can be optically controlled. Orthogonal circularly and linearly polarized diffraction orders are simultaneously obtained irradiating the grating with a linearly polarized beam. An external ac voltage allows to completely control the diffracted energy distribution.

Light-induced rotations of chiral birefringent microparticles in optical tweezers.

We study the rotational dynamics of solid chiral and birefringent microparticles induced by elliptically polarized laser light in optical tweezers. We find that both reflection of left circularly polarized light and residual linear retardance affect the particle dynamics. The degree of ellipticity of laser light needed to induce rotations is found. The experimental results are compared with analytical calculations of the transfer of angular moment from elliptically polarized light to chiral birefringent particles.

Light manipulation of nanoparticles in arrays of topological defects.

We report a strategy to assemble and manipulate nanoparticles arrays. The approach is based on the use of topological defects, namely disclination lines, created in chiral liquid crystals. The control of nanoparticle-loaded topological defects by low power light is demonstrated. Large-scale rotation, translation and deformation of quantum dots light-emitting chains is achieved by homogeneous LED illumination. Full reconfigurability and time stability make this approach attractive for future developments and applications.

MicroRNA-222 regulates muscle alternative splicing through Rbm24 during differentiation of skeletal muscle cells.

A number of microRNAs have been shown to regulate skeletal muscle development and differentiation. MicroRNA-222 is downregulated during myogenic differentiation and its overexpression leads to alteration of muscle differentiation process and specialized structures. By using RNA-induced silencing complex (RISC) pulldown followed by RNA sequencing, combined with in silico microRNA target prediction, we have identified two new targets of microRNA-222 involved in the regulation of myogenic differentiation, Ahnak and Rbm24. Specifically, the RNA-binding protein Rbm24 is a major regulator of muscle-specific alternative splicing and its downregulation by microRNA-222 results in defective exon inclusion impairing the production of muscle-specific isoforms of Coro6, Fxr1 and NACA transcripts. Reconstitution of normal levels of Rbm24 in cells overexpressing microRNA-222 rescues muscle-specific splicing. In conclusion, we have identified a new function of microRNA-222 leading to alteration of myogenic differentiation at the level of alternative splicing, and we provide evidence that this effect is mediated by Rbm24 protein.

Transformation of NIH3T3 cells by Rous sarcoma virus occurs with high efficiency in the absence of proviral rearrangements or amplification.

NIH3T3 cells could be transformed by a mammaltropic strain of Rous sarcoma virus (RSV) with an efficiency 10(3) times greater than that observed in Balb/c 3T3 cells or other mammalian cell lines and almost identical to that of chick embryo fibroblasts. In infected NIH3T3 cells a single, properly integrated, provirus was sufficient to induce focus formation; moreover, kinase activity of pp60v-src and tyrosine phosphorylation of cellular proteins could be detected very soon after infection in the majority of cells. On the other hand, in transformed foci from RSV-infected Balb/c 3T3 cells both rearrangements and amplification of proviral sequences were frequently detected. Accordingly, expression of pp60v-src and ensuing tyrosine phosphorylation of cellular proteins occurred, at high levels, only in a minority of the infected cells. Furthermore, by using a murine retrovirus carrying the v-src oncogene and an independent selectable marker, we found that Balb/c 3T3 cells were transformed with a 100-fold lower efficiency than NIH3T3 cells, yet the majority of infected untransformed Balb/c 3T3 cells expressed active pp60v-src. These findings are consistent with the existence in most mammalian cell lines of a major restriction to v-src-induced transformation, operating at the level of proviral expression, that is apparently absent in NIH3T3 cells.

Regulation of the tyrosine kinase substrate Eps8 expression by growth factors, v-Src and terminal differentiation.

SH3-containing proteins are involved in signal transduction by a number of growth factor receptors and in the organization of the cytoskeleton. The recently identified Eps8 protein, which contains an SH3 domain, is coupled functionally and physically to the EGFR and is tyrosine phosphorylated by this receptor and other receptors as well. Here, we examined the regulation of eps8 expression in response to mitogenic or differentiative signals. We show that Eps8 is expressed at low levels in resting fibroblasts, but its expression is strongly induced during activation by serum, phorbol esters and the v-src oncogene. Conversely, expression of Eps8, but not of other EGFR substrates such as Shc or Eps15, is virtually extinguished in non-proliferating, terminally differentiated murine myogenic cells. The putative role of Eps8 protein as a v-Src substrate was analysed in murine fibroblasts and in quail myogenic cells expressing a temperature-sensitive variant of the tyrosine kinase. Tyrosine phosphorylation of Eps8 was detected only at the permissive temperature. A non-myristylated, transformation-defective mutant of v-Src did not phosphorylate Eps8, whereas it phosphorylated Shc. Together, these findings indicate that Eps8 may be a critical substrate of v-Src. They further establish Eps8 as an example of a signal transducer whose expression senses the balance between growth and differentiation and might, therefore, be involved in the determination of the phenotype.

Chiral resolution of spin angular momentum in linearly polarized and unpolarized light.

Linearly polarized (LP) and unpolarized (UP) light are racemic entities since they can be described as superposition of opposite circularly polarized (CP) components of equal amplitude. As a consequence they do not carry spin angular momentum. Chiral resolution of a racemate, i.e. separation of their chiral components, is usually performed via asymmetric interaction with a chiral entity. In this paper we provide an experimental evidence of the chiral resolution of linearly polarized and unpolarized Gaussian beams through the transfer of spin angular momentum to chiral microparticles. Due to the interplay between linear and angular momentum exchange, basic manipulation tasks, as trapping, spinning or orbiting of micro-objects, can be performed by light with zero helicity. The results might broaden the perspectives for development of miniaturized and cost-effective devices.

Regulation of acetylcholine receptor gene expression in rats treated with alpha-bungarotoxin.

Regulation of acetylcholine receptor (AChR) gene expression was analyzed in alpha-bungarotoxin (alpha-BTX) treated rats. A reduction in available 125I-alpha-BTX binding sites was accompanied by an increase in the various AChR transcripts. The increase in the AChR alpha-, beta- epsilon- and delta-subunit mRNAs was similar to that observed in rats with experimental autoimmune myasthenia gravis (EAMG). Unlike in EAMG, the gamma-subunit transcripts reappeared following alpha-BTX treatment. The quantitative differences in the levels of AChR transcripts between alpha-BTX treatment and EAMG on one hand and denervation on the other hand, support the notion that the regulation of AChR gene expression is controlled by muscle activity and by neuronal factors as well. We also demonstrate in this report that myogenin transcripts increase following alpha-BTX treatment as well as following denervation, whereas MyoD1 transcripts remain stable.

Modulation of low-affinity nerve growth factor receptor in injured adult rat spinal cord motoneurons.

Spinal and brainstem motoneurons of the adult rat reexpress low-affinity nerve growth factor receptor (LNGFR) and its mRNA after axotomy. We have previously reported the time courses of this reexpression after cut (no regeneration) or crush (followed by regeneration) of the sciatic nerve. We have shown that the length of the different phases of this reexpression (appearance, maintenance and disappearance) can vary according to the type of axotomy. With the present study we expand our previous data and describe and analyze the modulation the LNGFR expression in adult spinal cord motoneurons following different lesion paradigms. In one approach we have imposed three traumatic injuries that still allow regeneration of the sciatic nerve but with a different time course with respect to the crush injury (application of a silicone regeneration chamber, multiple crushes and delayed repair of ligated nerves). In a second approach, we have determined the capability of three toxic or metabolic injuries to induce LNGFR expression without any direct trauma of the nerve (experimental diabetogenesis, botulinum and alpha-bungarotoxin intoxication and 2,5-hexanedione intoxication). In a third approach, we have investigated the effect of the block of the axoplasmic transport on the LNGFR expression following different topical applications of vincristine combined with a nerve crush. The results we present are consistent with the idea that: (1) LNGFR immunoreactivity in adult motoneurons is expressed by motoneurons that are attending to an axonal outgrowth and not a generic signal of cellular damage or impairment of the motor function; (2) LNGFR expression in these motoneurons is related to and parallels the outgrowth process time frame, and (3) the signal/s that trigger and sustain this reexpression may be retrogradely transported from the periphery.

Effect of transforming growth factor-beta1 on interleukin-6 secretion in human myoblasts.

Transforming growth factor-beta (TGF-beta) is involved in several autoimmune neurological diseases. It is still unclear whether its local action can be pro-inflammatory or anti-inflammatory in the muscle tissue, because of the few reports on this subject. We have previously shown that human myoblasts secrete interleukin-6 (IL-6) when stimulated with inflammatory cytokine such as interleukin-1beta (IL-1beta) or tumor necrosis factor alpha. In the present report, we show that TGF-beta1 can induce IL-6 production; moreover, costimulation or short term pre-incubation with TGF-beta1 increases IL-1beta effect, while a longer incubation inhibits its action.

Neonatal myasthenia gravis: clinical and immunological study of seven mothers and their newborn infants.

We studied 7 mothers with myasthenia gravis (MG) and their infants. We confirmed that the development of neonatal MG was not related to the serum titer of maternal anti-acetylcholine receptor antibody (anti-AChR ab). To investigate the possibility that specific immunization of the newborn infant had occurred, serial serum determinations of total and 'specific' anti-AChR IgG and IgM were performed. We found that: the decay in total IgG was within the normal range in all the babies; there was a shorter half-life of 'specific' IgG, compared to total IgG, in 3 of the cases, 2 of which did have neonatal MG; no difference was found between the decay of anti-AChR ab in the babies who had neonatal MG and those who did not; there was no anti-AChR IgM-associated activity. Our data suggest that neonatal MG is due to maternal anti-AChR abs and that affected infants do not produce specific antibodies.

Constitutive and cytokine-induced expression of MHC and intercellular adhesion molecule-1 (ICAM-1) on human myoblasts.

We studied the expression of MHC-I and MHC-II molecules and ICAM-1 in cultured human myoblasts in response to IL-1beta, IL-4, IL-6, IFN-gamma and LPS. IFN-gamma, LPS and IL-4 greatly increase MHC-I molecule expression. MHC-II molecule expression is induced only by IFN-gamma. Membrane ICAM-1 and mRNA expression are absent under basal conditions, but can be induced by IFN-gamma, IL-1beta, IL-4, LPS and IL-6 with different efficiencies and time-courses. Soluble ICAM-1 secretion can be induced to a different extent by all cytokines. Our study shows that the expression of adhesion-related molecules in muscle is finely regulated by these cytokines.

Effects of sciatic nerve grafts on choline acetyltransferase and p75 expression in transected adult hypoglossal motoneurons.

We previously reported that a permanent transection of adult rat sciatic and hypoglossal nerves resulted in distinct changes in the levels of both low-affinity nerve growth factor receptor (p75) and choline acetyltransferase in the corresponding motoneurons as determined by immunoreactivity. Permanent axotomy of hypoglossal motoneurons induced a progressive loss of choline acetyltransferase immunoreactivity and a persistent expression of p75 immunoreactivity, phenomena that were not observed in spinal motoneurons. These observations indicated that spinal and brainstem motoneurons respond to permanent axotomy with a differential immunoreactivity for p75 and choline acetyltransferase. Such differences could be ascribed to specific intrinsic properties of each population of motoneurons or, alternatively, to different factors present in the periphery (nerve stump or target muscle). The aim of the present study was to test these two possibilities by determining if a segment of sciatic nerve transplanted to a transected hypoglossal nerve may counteract or attenuate the loss of choline acetyltransferase immunoreactivity in injured hypoglossal motoneurons. In addition, as further parameter, we analysed the presence of p75 immunoreactivity. Prior to grafting, segments of sciatic nerve were prepared by one of three methods: (i) a fresh piece; (ii) a degenerated piece; and (iii) a heated piece. Seven and 30 days following the placement of grafts, hypoglossal motoneurons were analysed for choline acetyltransferase and p75 immunolabelling. The results revealed that viable sciatic grafts (fresh and degenerated) are able to partially attenuate the loss in the number of choline acetyltransferase-positive injured hypoglossal motoneurons, even if an important decrease in choline acetyltransferase still persists with respect to the contralateral nucleus. In addition, viable sciatic grafts decreased the number of p75 immunoreactive hypoglossal motoneurons both at seven and at 30 days. In conclusion, the effects of viable sciatic grafts on the number of choline acetyltransferase and p75-labelled hypoglossal motoneurons indicate that these adult neurons are able to respond to factors released from the sciatic nerve, and that the number of injured motoneurons positive for choline acetyltransferase and p75 can be influenced by the presence of factors that may reach their proximal stumps. Furthermore, we hypothesize that the differential expression patterns between hypoglossal and sciatic motoneurons may be due, at least in part, to factors released from the nerve trunks themselves.

Effect of pro-inflammatory/anti-inflammatory agents on cytokine secretion by peripheral blood mononuclear cells in rheumatoid arthritis and systemic lupus erythematosus.

We studied a well-selected population of patients with active rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE) without immunosuppressive therapy. Control and patient peripheral blood mononuclear cells (PBMC) were incubated with IL-1beta, IL-10, TGF-beta or LPS for 20 h and the in vitro basal and stimulated secretions of IL-6, TNF-alpha, IL-1beta and IL-1ra were measured by ELISA. We found that in the SLE patients the basal secretion of IL-6 was significantly lower and that of IL-1ra significantly higher than in control subjects, while in the RA group the basal IL-1ra secretion was higher than in healthy subjects. SLE and RA PBMC responded to LPS and IL-1beta reaching higher cytokine secretion values than controls. The in vitro response of SLE and RA PBMC to TGFbeta was normal, while that to IL-10 was defective: IL-10 was able to stimulate the production of IL-6 and IL-1ra in PBMC from normal subjects, but it was unable to enhance IL-6 secretion in RA cells and it was also completely ineffective in inducing IL-1ra secretion in both SLE and RA PBMC. Our work add new data useful for the evaluation of IL-10 and IL-1ra as therapeutic agents in rheumatic diseases.