Optical computation of a spin glass dynamics with tunable complexity.

Spin glasses (SGs) are paradigmatic models for physical, computer science, biological, and social systems. The problem of studying the dynamics for SG models is nondetermistic polynomial-time (NP) hard; that is, no algorithm solves it in polynomial time. Here we implement the optical simulation of an SG, exploiting the N segments of a wavefront-shaping device to play the role of the spin variables, combining the interference downstream of a scattering material to implement the random couplings between the spins (the [Formula: see text] matrix) and measuring the light intensity on a number P of targets to retrieve the energy of the system. By implementing a plain Metropolis algorithm, we are able to simulate the spin model dynamics, while the degree of complexity of the potential energy landscape and the region of phase diagram explored are user defined, acting on the ratio [Formula: see text] We study experimentally, numerically, and analytically this Hopfield-like system displaying a paramagnetic, ferromagnetic, and SG phase, and we demonstrate that the transition temperature [Formula: see text] to the glassy phase from the paramagnetic phase grows with α. We demonstrate the computational advantage of the optical SG where interaction terms are realized simultaneously when the independent light rays interfere on the detector's surface. This inherently parallel measurement of the energy provides a speedup with respect to purely in silico simulations scaling with N.

Production of antigen-specific human IgGs by in vitro immunization.

BACKGROUND: We previously developed in vitro immunization based on a fusion protein containing the transcriptional transactivator (Tat) of human immunodeficiency virus and a double domain, called ZZ, derived from protein A of Staphylococcus aureus. In this approach, naïve human peripheral blood mononuclear cells (PBMCs) trigger a specific IgM antibody (Ab) response in the presence of ZZTat. In the present study, we attempted to raise a specific IgG Ab response. RESULTS: We found that PBMCs incubated with ZZTat and a mixture containing anti-CD40, IL4 and IL21 secrete anti-Tat IgG Abs in their supernatants, indicating that the cytokine cocktail provides an isotypic switch. Then, we deciphered the Tat determinant involved in the phenomenon and found that it is located in the region 22-57 and that, within this region, the cysteine-rich domain and the basic residues play a crucial role. Finally, we prepared a fusion protein containing a fragment derived from the NY-ESO-1 cancer/testis antigen (Ag) and showed that PBMCs incubated with ZZfNY-ESO-1Tat trigger a specific anti-fNY-ESO-1 IgG Ab response, which demonstrates the possibility of transferring immunizing ability to an Ag unrelated to Tat. CONCLUSION: Our ZZTat-based in vitro immunization approach that offers the possibility to raise an IgG Ab response against NY-ESO-1 might represent a valuable first stage for the generation of fully human IgG specific Abs.

Comparison of methods for the fabrication and the characterization of polymer self-assemblies: what are the important parameters?

The ability to self-assemble was evaluated for a large variety of amphiphilic block copolymers, including poly(ethyleneoxide-b-ε-caprolactone), poly(ethyleneoxide-b-d,l-lactide), poly(ethyleneoxide-b-styrene), poly(ethyleneoxide-b-butadiene) and poly(ethyleneoxide-b-methylmethacrylate). Different methods of formation are discussed, such as cosolvent addition, film hydration or electroformation. The influence of experimental parameters and macromolecular structures on the size and morphology of the final self-assembled structures is investigated and critically compared with the literature. The same process is carried out regarding the characterization of these structures. This analysis demonstrates the great care that should be taken when dealing with such polymeric assemblies. If the morphology of such assemblies can be predicted to some extent by macromolecular parameters like the hydrophilic/hydrophobic balance, those parameters cannot be considered as universal. In addition, external experimental parameters (methods of preparation, use of co-solvent, …) appeared as critical key parameters to obtain a good control over the final structure of such objects, which are very often not at thermodynamic equilibrium but kinetically frozen. A principal component analysis is also proposed, in order to examine the important parameters for forming the self-assemblies. Here again, the hydrophilic/hydrophobic fraction is identified as an important parameter.

A model eye for fluorescent characterization of retinal cultures and tissues.

Many human neural or neurodegenerative diseases strongly affect the ocular and retinal environment showing peculiar alterations which can be employed as specific disease biomarkers. The noninvasive optical accessibility of the retina makes the ocular investigation a potentially competitive strategy for screening, thus the development of retinal biomarkers is rapidly growing. Nevertheless, a tool to study and image biomarkers or biological samples in a human-like eye environment is still missing. Here we report on a modular and versatile eye model designed to host biological samples, such as retinal cultures differentiated from human induced pluripotent stem cells and ex-vivo retinal tissue, but also suited to host any kind of retinal biomarkers. We characterized the imaging performance of this eye model on standard biomarkers such as Alexa Fluor 532 and Alexa Fluor 594.

Preauricular incision outlining during a face-lift: a step-by-step description.

UNLABELLED: The data on the proper way to establish the preauricular incision (PAI) line and manage skin tension during lifting are limited. Undoubtedly, proper tissue handling represents a true challenge during a lifting procedure and is a crucial step in avoiding disfiguration. The authors describe their approach to PAI demarcation and local skin tension management performed in 165 cases since 2007. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors at www.springer.com/00266.

Presentation of antigen in immune complexes is boosted by soluble bacterial immunoglobulin binding proteins.

Using a snake toxin as a proteic antigen (Ag), two murine toxin-specific monoclonal antibodies (mAbs), splenocytes, and two murine Ag-specific T cell hybridomas, we showed that soluble protein A (SpA) from Staphylococcus aureus and protein G from Streptococcus subspecies, two Ig binding proteins (IBPs), not only abolish the capacity of the mAbs to decrease Ag presentation but also increase Ag presentation 20-100-fold. Five lines of evidence suggest that this phenomenon results from binding of an IBP-Ab-Ag complex to B cells possessing IBP receptors. First, we showed that SpA is likely to boost presentation of a free mAb, suggesting that the IBP-boosted presentation of an Ag in an immune complex results from the binding of IBP to the mAb. Second, FACS analyses showed that an Ag-Ab complex is preferentially targeted by SpA to a subpopulation of splenocytes mainly composed of B cells. Third, SpA-dependent boosted presentation of an Ag-Ab complex is further enhanced when splenocytes are enriched in cells containing SpA receptors. Fourth, the boosting effect largely diminishes when splenocytes are depleted of cells containing SpA receptors. Fifth, the boosting effect occurs only when IBP simultaneously contains a Fab and an Fc binding site. Altogether, our data suggest that soluble IBPs can bridge immune complexes to APCs containing IBP receptors, raising the possibility that during an infection process by bacteria secreting these IBPs, Ag-specific T cells may activate IBP receptor-containing B cells by a mechanism of intermolecular help, thus leading to a nonspecific immune response.

Effects of the beta3-adrenoceptor (Adrb3) agonist SR58611A (amibegron) on serotonergic and noradrenergic transmission in the rodent: relevance to its antidepressant/anxiolytic-like profile.

SR58611A is a selective beta(3)-adrenoceptor (Adrb3) agonist which has demonstrated antidepressant and anxiolytic properties in rodents. The present study confirmed the detection of Adrb3 mRNA transcript in rodent brain sub-regions and evaluated the effect of SR58611A on serotonergic and noradrenergic transmission in rats and mice in an attempt to elucidate the mechanism(s) underlying these properties. SR58611A (3 and 10 mg/kg, p.o.) increased the synthesis of 5-HT and tryptophan (Trp) levels in several rodent brain areas (cortex, hippocampus, hypothalamus, striatum). Moreover, SR58611A (10 mg/kg, p.o.) increased the release of 5-HT assessed by in vivo microdialysis in rat prefrontal cortex. Systemic (3 mg/kg, i.v.) or chronic administration of SR58611A (10 mg/kg, p.o.), in contrast to fluoxetine (15 mg/kg, p.o.), did not modify the activity of serotonergic neurons in the rat dorsal raphe nucleus. The increase in 5-HT synthesis induced by SR58611A was not observed in Adrb3s knockout mice, suggesting a selective involvement of Adrb3s in this effect. SR58611A (3 and 10 mg/kg, p.o.) did not modify norepinephrine synthesis and metabolism but increased its release in rat brain. Repeated administration of SR58611A (10 mg/kg, p.o.) did not modify basal norepinephrine release in rat prefrontal cortex whereas it prevented its tail-pinch stress-induced enhancement similarly to reboxetine (15 mg/kg, p.o.). Finally SR58611A increased the firing rate of noradrenergic neurons in the rat locus coeruleus following systemic (3 mg/kg, i.v.) or local (0.01 and 1 microM) but not chronic (10 mg/kg, p.o.) administration. These results suggest that the anxiolytic- and antidepressant-like activities of SR58611A involve an increase of brain serotonergic and noradrenergic neurotransmissions, triggered by activation of Adrb3s.

2-Chloro-N-[(S)-phenyl [(2S)-piperidin-2-yl] methyl]-3-trifluoromethyl benzamide, monohydrochloride, an inhibitor of the glycine transporter type 1, increases evoked-dopamine release in the rat nucleus accumbens in vivo via an enhanced glutamatergic neurotransmission.

2-Chloro-N-S-phenyl 2S-piperidin-2-yl methyl]-3-trifluoromethyl benzamide, monohydrochloride (SSR504734) is a potent and selective inhibitor of the glycine transporter type 1, which increases central N-methyl-D aspartate glutamatergic tone. Since glutamate has been shown to play a role in the regulation of the dopaminergic system in dopamine-related disorders, such as schizophrenia, we investigated the possibility that SSR504734 may modify the basolateral amygdala-elicited stimulation of dopamine release in the nucleus accumbens via an augmentation of glutamate receptor-mediated neurotransmission. First, our data confirmed that SSR504734 is an inhibitor of GlytT1. In the nucleus accumbens of anesthetized rat, SSR504734 (10 mg/kg, i.p.) induced an increase of extracellular levels of glycine as measured by microdialysis coupled with capillary electrophoresis with laser-induced fluorescence detection. Second, the data demonstrated that SSR504734 (10 mg/kg, i.p.) enhanced the facilitatory influence of glutamatergic afferents on dopamine neurotransmission in the nucleus accumbens. Using an electrochemical technique, we measured dopamine release in the nucleus accumbens evoked by an electrical stimulation of the basolateral amygdala. SSR504734 facilitated dopamine release evoked by a 20 or a 40 Hz frequency basolateral amygdala stimulation. This facilitatory effect was dependent on glutamatergic tone, as intra-nucleus accumbens application of 6-7-dinitroquinoxaline-2,3-dione (10(-3) M) or DL-2-amino-5-phosphonopentanoic acid (10(-3) M), alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and N-methyl-D aspartate receptors antagonists, respectively, inhibited dopamine release evoked by basolateral amygdala stimulation. Furthermore DL-2-amino-5-phosphonopentanoic acid co-administrated with SSR504734 hampered the dopamine-evoked release facilitation. These data underline the in vivo implication of the glycine uptake mechanism in the control of subcortical glutamate/dopamine interactions.

Effects of the vasopressin (V1b) receptor antagonist, SSR149415, and the corticotropin-releasing factor 1 receptor antagonist, SSR125543, on FG 7142-induced increase in acetylcholine and norepinephrine release in the rat.

Arginine vasopressin and corticotropin-releasing factor are two neuroactive peptides that regulate hypothalamic-pituitary-axis and associated stress response. While the potential antidepressant and anxiolytic profiles of corticotropin-releasing factor 1 antagonists have been well studied, the concept of blockade of vasopressin system as another approach for the treatment of emotional processes has only been made available recently by the synthesis of the first non-peptide antagonist at the V1b receptor, SSR149415. In the present study SSR149415 has been compared with the corticotropin-releasing factor 1 antagonist SSR125543 and with anxiolytic and antidepressant drugs on the response of hippocampal cholinergic and cortical noradrenergic systems to the anxiogenic benzodiazepine receptor inverse agonist FG 7142. Acute (0.3-10 mg/kg, i.p.) and long-term administration (10 mg/kg, i.p., 21 days) of SSR149415 and SSR125543 reduced the FG 7142-induced increase in extracellular concentrations of acetylcholine in the hippocampus of anesthetized rats measured by microdialysis. By contrast acute and long-term administration of SSR149415 failed to reduce the FG 7142-induced increase in the release of norepinephrine in the cortex of freely moving rats. The present results demonstrate that the two compounds have similar profiles in a model of activation by an anxiogenic drug of the hippocampal cholinergic system and they suggest that SSR149415 and SSR125543 may have anti-stress anxiolytic and antidepressant effects via a mechanism of action different from classical benzodiazepine ligands and noradrenergic antidepressants.

Anti-idiotypic and anti-anti-idiotypic responses to a monoclonal antibody directed to the acetylcholine receptor binding site of curaremimetic toxins.

Serotherapy, an approach currently used to protect humans against animal bites or stings, is often too specific. To broaden antiserum paraspecificity, use of antibodies directed against areas shared by all members of a toxin family was previously proposed. MST2 is a mAb that recognizes all long-chain curaremimetic toxins (Charpentier et al. (1990) J. Mol. Recog. 3, 74-81). It binds to toxin residues that make contact with the toxin's target, e.g., the nicotinic acetylcholine receptor (AcChoR). We now show that MST2 also recognizes (-) nicotine, an agonist of AcChoR. Binding properties of MST2 therefore mimick, at least partially, binding properties of AcChoR. Injection in rabbits of MST2 mixed with adjuvant, elicited anti-idiotypic (anti-Id) antibodies that inhibited binding of the toxin to AcChoR. A proportion of these anti-Id antibodies specifically bound AcChoR and thereby mimicked the toxin. Furthermore, rabbits immunized with MST2 elicited auto-anti-anti-Id antibodies capable of binding the toxin. Our data provide a molecular explanation for the previously reported signs of myasthenia gravis as triggered by antibodies raised against cholinergic antagonists. Implications in the design of antisera to toxic proteins are discussed.

CD and FTIR studies of an immunogenic disulphide cyclized octadecapeptide, a fragment of a snake curaremimetic toxin.

In a previous paper, the systematic epitope screening of a snake curaremimetic toxin or toxin a was described by this group using a panel of synthetic octadecapeptides. The disulphide cyclized peptide (Cys-23,40)(23-40) corresponding to loop II of the native toxin was found to elicit, with no linkage to a carrier, neutralizing antisera against the toxin. We have now undertaken the conformational study of this immunogenic disulphide cyclized peptide by CD and FTIR. The CD study of the peptide was carried in aqueous solution under various conditions (pH, temperature, presence of micelles) and in trifluoroethanol solution. Low temperature, SDS micelles and trifluoroethanol were found to induce a beta-sheet formation (16 to 39%). FTIR spectra of the peptide in the solid state (dry film) and in D2O solution or deuterated-TFE solution (hydrated film) displayed some characteristic bands indicating the presence of beta-sheet (1623 cm-1) and beta-turn (1637 cm-1; 1694 cm-1). These studies indicate that the immunogenic disulphide cyclized peptide (23-40) can adopt in solution an ordered structure.

Boc-Cys(Npys)-OH (BCNP): an appropriate reagent for the identification of T cell epitopes in cystine and/or cysteine-containing proteins.

Some T cell epitopes become inactive when their thiols are blocked with various irreversible reagents (Régnier-Vigouroux, 1988; Maillère, 1992; Maillère et al., 1993). Blocking protein and peptide thiols with BCNP (Boc-Cys(Npys)-OH) constitutes a most appropriate strategy when searching for thiol-containing T cell epitopes. Free cysteines can thus be readily transformed into disulphide-like moieties which not only resist undesirable oxidative reactions but which also remain susceptible to reduction by antigen presenting cells, a prerequisite for the activity of thiol-dependent T cell epitopes. We describe the use of this reagent in a study of the intact disulphide-rich protein, toxin alpha from Naja nigricollis, and also two disulphide-containing toxin fragments.

Recombinant antibody-alkaline phosphatase conjugates for diagnosis of human IgGs: application to anti-HBsAg detection.

We have designed an expression vector permitting the production in the periplasm of Escherichia coli of a fusion protein comprising a dimer of bacterial alkaline phosphatase (PhoA) and two Fab or scFv fragments of a monoclonal antibody directed against human IgG. Each hybrid protein expressed both high specificity for the antigen and full PhoA activity. We show that crude periplasmic extracts containing these conjugates can be used as such in enzyme immunoassays for the detection of human IgG, as exemplified in the case of anti-hepatitis B immunoglobulin.

Comparative effects of neurotensin, neurotensin(8-13) and [D-Tyr(11)]neurotensin applied into the ventral tegmental area on extracellular dopamine in the rat prefrontal cortex and nucleus accumbens.

Ejections of 10(-5)-10(-3)M neurotensin into the ventral tegmental area increased dopamine efflux measured by electrochemical approaches in the prefrontal cortex of anaesthetized rats. In the same conditions, the effects evoked on dopamine efflux by 10(-5)M neurotensin(8-13) and [D-Tyr(11)]neurotensin were different from each other and depended on the explored area: the prefrontal cortex and the caudal and rostral nucleus accumbens. In the prefrontal cortex, neurotensin(8-13) was as potent as neurotensin, whereas [D-Tyr(11)]neurotensin was ineffective. In the caudal nucleus accumbens, when considering the initial intensity of the effect, neurotensin(8-13) and neurotensin appeared more potent than [D-Tyr(11)]neurotensin. In contrast, in the rostral nucleus accumbens, neurotensin(8-13) was less potent than [D-Tyr(11)]neurotensin and neurotensin. These results support the differential involvement of two pharmacologically distinct neurotensin receptor entities on ventral tegmental area neurons in the modulation of mesolimbic and mesocortical dopaminergic activity.

Production of human antibodies by in vitro immunization using a fusion protein containing the transcriptional transactivator of HIV-1.

Antigen-specific activation of human B cells represents a key step for the production of monoclonal antibodies. Several approaches have been developed over the last thirty years in order to improve the process of lymphocyte activation in vitro. In the present study, we investigated whether the transcriptional transactivator (Tat) of human immunodeficiency virus, which possesses numerous biological activities, is able to trigger antibody secretion when incubated with human peripheral blood mononuclear cells. No such effect was observed when using Tat as a free protein. However, we found a significant IgM antibody production when Tat was previously fused to a double domain, called ZZ, derived from protein A of Staphylococcus aureus. The effect was also observed when the fusion protein, called ZZTat101, was incubated with purified B cells, indicating that the phenomenon does not require T-cell help. Antibody secretion was observed in the absence of cytokines that are usually used during in vitro immunization experiments, indicating that ZZTat101 provides the signals required for the initiation of the immune response. Antibody secretion was observed using a ZZTat mutant, containing only the Tat residues 22 to 57, called ZZTat22-57, indicating that this region is sufficient to initiate the immune response. In contrast, the effect was not found with a ZZTat22-57 mutant devoid of the seven Tat cysteines located between residues 22 and 37, demonstrating that these residues play a crucial role in the phenomenon. Our results pave the way to the development of a new in vitro immunization method based on antigens associated with ZZTat.

Condensation in disordered lasers: theory, 3D+1 simulations, and experiments.

The complex processes underlying the generation of a coherent emission from the multiple scattering of photons and wave localization in the presence of structural disorder are still mostly unexplored. Here we show that a single nonlinear Schrödinger equation, playing the role of the Schwalow-Townes law for standard lasers, quantitatively reproduces experimental results and three-dimensional time-domain parallel simulations of a colloidal laser system.

Contribution of the Nernst potential to stiffness constants: the asymmetrical case.

Inside biological membranes, one of the fundamental functions of active proteins such as pumps is to generate some electrochemical gradient across the membrane and then, to establish a new stationary state. The membrane electric potential generated by activity modifies the stiffness constants of the membrane. A spontaneous curvature appears if the inner and outer Debye lengths are different. The corresponding characteristic radius falls in the range from 0.08 microm to 50 microm. The bending elastic modulus is always increased. This effect is only noticeable in the limit of large Debye length from 0.5 microm to 0.09 microm. For a Nernst potential of 100 mV and a Debye length of 0.2 microm, the bending modulus can reach 40k(B)T.

Cotransport-induced instability of membrane voltage in tip-growing cells.

A salient feature of stationary patterns in tip-growing cells is the key role played by the symports and antiports, membrane proteins that translocate two ionic species at the same time. It is shown that these cotransporters destabilize generically the membrane voltage if the two translocated ions diffuse differently and carry a charge of opposite (same) sign for symports (antiports). The orders of magnitude obtained for the time and length scale are in agreement with experiments. A weakly nonlinear analysis characterizes the bifurcation.

Pattern formation of stationary transcellular ionic currents in Fucus.

Stationary and nonstationary spatiotemporal pattern formations emerging from the cellular electric activity are a common feature of biological cells and tissues. The nonstationary ones are well explained in the framework of the cable model. Inversely, the formation of the widespread self-organized stationary patterns of transcellular ionic currents remains elusive, despite their importance in cell polarization, apical growth, and morphogenesis. For example, the nature of the breaking symmetry in the Fucus zygote, a model organism for the experimental investigation of embryonic pattern formation, is still an open question. Using an electrodiffusive model, we report here an unexpected property of the cellular electric activity: a phase-space domain that gives rise to stationary patterns of transcellular ionic currents at finite wavelength. The cable model cannot predict this instability. In agreement with experiments, the characteristic time is an ionic diffusive one (<2 min). The critical radius is of the same order of magnitude as the cell radius (30 microm). The generic salient features are a global positive differential conductance, a negative differential conductance for one ion, and a difference between the diffusive coefficients. Although different, this mechanism is reminiscent of Turing instability.