Cortico-spinal modularity in the parieto-frontal system: A new perspective on action control.

Classical neurophysiology suggests that the motor cortex (MI) has a unique role in action control. In contrast, this review presents evidence for multiple parieto-frontal spinal command modules that can bypass MI. Five observations support this modular perspective: (i) the statistics of cortical connectivity demonstrate functionally-related clusters of cortical areas, defining functional modules in the premotor, cingulate, and parietal cortices; (ii) different corticospinal pathways originate from the above areas, each with a distinct range of conduction velocities; (iii) the activation time of each module varies depending on task, and different modules can be activated simultaneously; (iv) a modular architecture with direct motor output is faster and less metabolically expensive than an architecture that relies on MI, given the slow connections between MI and other cortical areas; (v) lesions of the areas composing parieto-frontal modules have different effects from lesions of MI. Here we provide examples of six cortico-spinal modules and functions they subserve: module 1) arm reaching, tool use and object construction; module 2) spatial navigation and locomotion; module 3) grasping and observation of hand and mouth actions; module 4) action initiation, motor sequences, time encoding; module 5) conditional motor association and learning, action plan switching and action inhibition; module 6) planning defensive actions. These modules can serve as a library of tools to be recombined when faced with novel tasks, and MI might serve as a recombinatory hub. In conclusion, the availability of locally-stored information and multiple outflow paths supports the physiological plausibility of the proposed modular perspective.

Biologically friendly room temperature ionic liquids and nanomaterials for the development of innovative enzymatic biosensors.

Main purpose of the work is assembling, testing and optimizing new disposable amperometric biosensors to analyze substances in different application fields as agribusiness, clinical chemistry and environment protection. Many kinds of modified electrodes have been prepared and tested to build portable devices to analyze quickly many analytes, in a simple and cost-effective manner. Bare electrodes of the screen-printed type, with silver as reference, have been used for modification. The glassy carbon electrodes with multi-walled carbon nanotubes or graphene or gold nanoparticles depositions were modified with generation IV ionic liquids. Choline as cation and amino acids, such as glycine, serine, phenylalanine and histidine, as anions have been employed for these ionic liquids. The presence of nanostructured materials on the electrode brings an increased contact surface between analytes and receptor and, consequently, an amplification of the amperometric signal and a better sensibility. Moreover the use of new ionic liquids of generation IV, biologically friendly and water soluble, improves the electronic transfer, facilitating and strengthening the redox reaction nearby the electrode. By immobilizing the proper enzymes onto the modified electrode surface, different compounds of analytical interest can be determined by means of sensitive, properly designed amperometric biosensors. Analytes such as antioxidant components in extra-virgin olive oils, alcohols in beverages and glucose in food matrices have been tested, using a suitable enzyme: microbial lipase, alcohol dehydrogenase and glucose oxidase, respectively.

Development of motor coordination during joint action in mid-childhood.

The ability to act jointly with others is a hallmark of primate evolution and is fundamental for human development. In recent years, the study of coordination strategies between individuals performing joint actions has received growing attention. However, when, in the course of post-natal development, this cognitive-motor function emerges is still unknown. Here, we studied dyads of peers aged 6-9 years, as well as adult subjects, while they performed a task where the same action, namely, exerting hand force on an isometric joystick to move a visual cursor from a central toward a peripheral target, was performed in a "solo" and in a social "cooperative" context. The results revealed that during joint action planning, an attempt to synchronize one's own action with that of a partner emerges at 7 years of age, together with a reduction in the duration and variability of the reaction times. A critical time is 8 years, when "solo" performance reaches a high level of accuracy. From this age, another coordination strategy, based on the online monitoring of the peer's behavior, seems to be implemented during the execution of joint action. The motor and cognitive development occurring during childhood are discussed as possible mechanisms mediating, respectively, the capability and the propensity to take into account the peer's behavior for implementing a common action plan.

Water and hexane in an ionic liquid: computational evidence of association under high pressure.

High pressures may strongly affect the mesoscopic structure of some ionic liquids. In particular, the so called sponge-like structure is gradually destroyed when an increasing pressure is applied. Here we show how a polar solute, an apolar solute or a mixture thereof behave in the ionic liquid trihexyl, tetradecylphosphonium bis (trifluoromethyl-sulfonyl) imide when the pressure is raised up to 10 kbar. Our calculations clearly show an association between molecules that would not interact in ordinary conditions.

Structural and vibrational study of 2-MethoxyEthylAmmonium Nitrate (2-OMeEAN): Interpretation of experimental results with ab initio molecular dynamics.

In this work we report an analysis of the bulk phase of 2-methoxyethylammonium nitrate based on ab initio molecular dynamics. The structural and dynamical features of the ionic liquid have been characterized and the computational findings have been compared with the experimental X-ray diffraction patterns, with infrared spectroscopy data, and with the results obtained from molecular dynamics simulations. The experimental infrared spectrum was interpreted with the support of calculated vibrational density of states as well as harmonic frequency calculations of selected gas phase clusters. Particular attention was addressed to the high frequency region of the cation (ω > 2000 cm(-1)), where the vibrational motions involve the NH3+ group responsible for hydrogen bond formation, and to the frequency range 1200-1400 cm(-1) where the antisymmetric stretching mode (ν3) of nitrate is found. Its multiple absorption lines in the liquid arise from the removal of the degeneracy present in the D3h symmetry of the isolated ion. Our ab initio molecular dynamics leads to a rationalization of the frequency shifts and splittings, which are inextricably related to the structural modifications induced by a hydrogen bonding environment. The DFT calculations lead to an inhomogeneous environment.

Silver-Doped Calcium Phosphate Bone Cements with Antibacterial Properties.

Calcium phosphate bone cements (CPCs) with antibacterial properties are demanded for clinical applications. In this study, we demonstrated the use of a relatively simple processing route based on preparation of silver-doped CPCs (CPCs-Ag) through the preparation of solid dispersed active powder phase. Real-time monitoring of structural transformations and kinetics of several CPCs-Ag formulations (Ag = 0 wt %, 0.6 wt % and 1.0 wt %) was performed by the Energy Dispersive X-ray Diffraction technique. The partial conversion of ß-tricalcium phosphate (TCP) phase into the dicalcium phosphate dihydrate (DCPD) took place in all the investigated cement systems. In the pristine cement powders, Ag in its metallic form was found, whereas for CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, CaAg(PO3)3 was detected and Ag (met.) was no longer present. The CPC-Ag 0 wt % cement exhibited a compressive strength of 6.5 ± 1.0 MPa, whereas for the doped cements (CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt %) the reduced values of the compressive strength 4.0 ± 1.0 and 1.5 ± 1.0 MPa, respectively, were detected. Silver-ion release from CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, measured by the Atomic Emission Spectroscopy, corresponds to the average values of 25 µg/L and 43 µg/L, respectively, rising a plateau after 15 days. The results of the antibacterial test proved the inhibitory effect towards pathogenic Escherichia coli for both CPC-Ag 0.6 wt % and CPC-Ag 1.0 wt % cements, better performances being observed for the cement with a higher Ag-content.

Pressure-induced mesoscopic disorder in protic ionic liquids: first computational study.

It has been recently shown that pressure may affect the mesoscopic heterogeneity in aprotic ionic liquids, owing to the long alkyl chain folding on itself. Here we explore protic ionic liquids, using classical molecular dynamics. These compounds have shorter and stiffer alkyl chains, harder to fold. We observed that high pressure affects the mesoscopic structure of the studied chemicals and, indeed, the effect may be ascribed to chain folding.

Interaction and dynamics of ionic liquids based on choline and amino acid anions.

The combination of amino acid anions with the choline cation gives origin to a new and potentially important class of organic ionic liquids that might represent a viable and bio-compatible alternative with respect to the traditional ones. We present here a detailed study of the bulk phase of the prototype system composed of the simplest amino acid (alanine) anion and the choline cation, based on ab initio and classical molecular dynamics. Theoretical findings have been validated by comparing with accurate experimental X-ray diffraction data and infrared spectra. We find that hydrogen bonding (HB) features in these systems are crucial in establishing their local geometric structure. We have also found that these HBs once formed are persistent and that the proton resides exclusively on the choline cation. In addition, we show that a classical force field description for this particular ionic liquid can be accurately performed by using a slightly modified version of the generalized AMBER force field.

Visually-guided correction of hand reaching movements: The neurophysiological bases in the cerebral cortex.

The ability of human and non-human primates to make fast corrections to hand movement trajectories after a sudden shift in the target's location is a key feature of visuo-motor behavior. In healthy individuals, hand movements smoothly adapt to a change in target location without needing to complete the movement to the first target location, as typical of parietal patients. This finding indicates that the nervous system continuously monitors the visual scene and is able to integrate new information in order to produce an efficient motor response. In this paper, we review the kinematics, reaction times and muscle activity observed during the online correction of hand movements as well as the underlying neurophysiological processes studied through single-cell neural recordings in monkeys. Brain stimulation, lesion and imaging studies in humans are also discussed. We demonstrate that while online correction mechanisms strongly depend on the activity of a parieto-frontal network of which the posterior parietal cortex is a crucial node, these mechanisms proceed smoothly and are similar to what is observed during simple point-to-point movements. Online correction of hand movements would rely on feedforward and feedback mechanisms in the parietal cortex, as part of the activity within the fronto-parietal network for the planning and execution of visuo-motor tasks.

A visuomotor disorder in the absence of movement: does optic ataxia generalize to learned isometric hand action?

Visuomotor deficits in parietal patients suffering from Optic Ataxia (OA) have been so far studied during natural reaching movements. We aimed at understanding if these disorders are also present when more abstract visuomotor transformations are involved. A patient with unilateral OA was tested during both standard reaches and isometric actions, therefore in the absence of hand displacement. Isometric action was affected similarly to standard reaches, with endpoint errors to visual targets that were found in both central and peripheral vision. The dissociation of perceptual and motor components of errors highlighted the existence of field, hand and hemispace effects, which depended on the type of error investigated. A generalization of the reaching disorder to learned isometric conditions would suggest that lesions of posterior parietal cortex (PPC) affect sensory-motor transformations not only for standard reaches, but also when visual signals need to be aligned with information from hand force receptors, therefore regardless of the specific remapping required to generate the directional motor output. The isometric impairment emerged with high and similar severity regardless of whether targets were in central or peripheral vision. Since under all isometric conditions gaze and hand position were decoupled, the spatial correspondence between the hand and the gaze seems to play a critical role in this syndrome. This indicates that regardless of the action to be performed and the specific remapping required, there exists in PPC an abstract representation of the directional motor output, where the computation of eye-hand alignment by parietal neurons plays a crucial role.

The structural organization of N-methyl-2-pyrrolidone + water mixtures: a densitometry, x-ray diffraction, and molecular dynamics study.

A combined approach of molecular dynamics simulations, wide angle X-ray scattering experiments, and density measurements was employed to study the structural properties of N-methyl-2-pyrrolidone (NMP) + water mixtures over the whole concentration range. Remarkably, a very good agreement between computed and experimental densities and diffraction patterns was achieved, especially if the effect of the mixture composition on NMP charges is taken into account. Analysis of the intermolecular organization, as revealed by the radial and spatial distribution functions of relevant solvent atoms, nicely explained the density maximum observed experimentally.

Amino acid anions in organic ionic compounds. An ab initio study of selected ion pairs.

The combination of amino acids in their deprotonated and thus anionic form with a choline cation gives origin to a new and potentially important class of organic ionic compounds. A series of such neutral ion pairs has been investigated by first principle methods. The results reveal intriguing structural motives as well as regular patterns in the charge distribution and predict a number of vibrational and optical properties that could guide the experimental investigation of these compounds. The replacement of choline with its phosphocholine analogue causes the spontaneous reciprocal neutralization of cations and anions, taking place through the transfer of a proton between the two ions. Systems of this kind, therefore, provide a wide and easily accessible playground to probe the ionic/polar transition in organic systems, while the easy transfer of H(+) among neutral and ionic species points to their potential application as proton conductors. The analysis of the ab initio data highlights similarities as well as discrepancies from the rigid-ions force-field picture and suggests directions for the improvement of empirical models.

A prototypical ionic liquid explored by ab initio molecular dynamics and Raman spectroscopy.

We present an analysis of the liquid and of a small isolated cluster of n-ethyl ammonium nitrate based on "first principles" molecular dynamics. We discover that the peculiar properties of ionic liquids make such compounds ideal candidates for such an analysis. We have been able to characterize some important features of the liquid structure and we have validated our simulations by comparing our findings with experimental vibrational spectra of the liquid phase. Theoretical spectra, which present a remarkable agreement with the measurements, besides the assignment of the main spectra features, allow an interpretation of the spectra at high frequencies where the vibrational motions involve the hydrogen-bonded atoms, thus providing a picture of the hydrogen bonding network that exists in such compounds.

Structure of geminal imidazolium bis(trifluoromethylsulfonyl)imide dicationic ionic liquids: a theoretical study of the liquid phase.

In this work, we report molecular dynamics simulations of the bulk liquid phase of geminal di-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids. We characterize a few interesting features of the local structure in the liquid phase, and we make a comparison both with gas phase structures and with the monoimidazolic counterparts. We analyze in detail the diffraction properties of these fluids by simulating X-ray and neutron scattering factors and we report on the long-range structural order that seems to also arise in one of these compounds.

Structure of the molten salt methyl ammonium nitrate explored by experiments and theory.

We present an analysis of the structure of the monomethylammonium nitrate (MMAN) compound. Vibrational Raman spectroscopy and X-ray powder diffraction have been used to characterize the bulk phases of MMAN, and assignment of the resonant frequencies has been performed by ab initio (DFT) computations on small clusters of the compound. The theoretical spectra are in excellent agreement with the experimental ones and provide a means by which an interpretation of the hydrogen-bonding network that exists in such compound can be analyzed. In particular, we found that the spectrum of one of the solid phases is structurally very similar to that of the liquid. We present experimental evidence for the existence of such phase both from X-ray data and Raman spectra which, in turn, is easily interpreted with a one-to-one correspondence with the ab initio simulation of the small clusters. A geometric structure of the short-range local arrangement in these two bulk phases is therefore proposed.

Pseudoaneurysm of the hepatic artery and hemobilia: a rare complication of laparoscopic cholecystectomy; clinical case and literature review.

Laparoscopic cholecystectomy is the Gold Standard for the treatment of symptomatic cholelithiasis. There is still an increase in the rate of incidence of biliary and vascular injuries with laparoscopy. Hepatic artery pseudoaneurysm is a rare but serious complication associated with laparoscopic cholecystectomy and bile duct injury. The diagnosis may be difficult. Our experience of a case of iatrogenic lesion of the right hepatic artery with the formation of pseudoaneurysm treated by means of embolization of the artery is presented here.

The structure of geminal imidazolium bis(trifluoromethylsulfonyl)amide ionic liquids: a theoretical study of the gas phase ionic complexes.

In this work we report molecular mechanics and ab initio calculations on the geminal di-imidazolium bis(trifluoromethylsulfonyl)amide ionic liquid in the gas phase. We report the likely energetically preferred geometries of the ionic complex and its main features in terms of charge distribution, electronic density, structure, and energetics. We find that the gas phase structure of the ionic complex is quite compact and that the alkyl chain connecting the two imidazolium charged rings is strongly bent in order to maximize their electrostatic interactions with the two anions.

[Intestinal perforation by ingested foreign bodies in the digestive tract: an insidious pathology always of interest. Our experience]. / La complicanza perforativa da ingestione di corpi estranei alimentari: una patologia insidiosa sempre attuale. Nostra esperienza.

The authors want to present five cases (from May 1999 to May 2009) of acute abdomen from perforation of the foreign body introduced with food. They highlight how the accidental ingestion is very common but the perforation is rare. The preoperative diagnosis, in these cases, is always very difficult and the radiological examinations are not always able to resolve the diagnostic doubt with other acute intestinal diseases that are responsible of perforation. Then, the surgery procedure is, necessarily, the only possible diagnostic and therapeutic means. The mortality and the morbidity remain still high first of all for the delay in the diagnosis and the advanced age of patients.

Are PEI-coated SWCNTs conjugated with hepatitis A virus? A chemical study with SEM, Z-potential, EDXD and RT-PCR.

The conjugation between nanotubes, coated with different doses of polyethylene imine (PEI) and hepatitis A virus (HAV) was investigated by scanning electron microscopy, Z-potential, thermogravimetric and differential thermal analysis, transmission electron microscopy, energy dispersive x-ray diffraction (EDXD) and reverse transcript polymerase chain reaction (RT-PCR). For the first time, to our knowledge, evidence is obtained that conjugation between the nanotubes and the HAV occurs and that it has an (at least a partial) electrostatic character. Since all components of the conjugated systems, nanotubes, coating material and virus are characterized by different peak shapes in the selected q range, it was possible to infer that conjugation occurred. RT-PCR measurements confirmed that the conjugation of the coated nanotubes and HAV occurred and the result was stable. This opens up the prospect of probing the coated nanotubes as intra-cellular carriers in transfection processes of the virus. Further biological applications will concern a possible vaccine especially for non-replicative viruses.