A high-pressure and high-temperature gas-loading system for the study of conventional to real industrial sized samples in catalysed gas/solid and liquid/solid reactions

A high-pressure–high-temperature gas-loading system (GLS) is described for combinedoperandoX-ray diffraction and mass spectrometry investigations during catalysed gas/solid or liquid/solid reactions. The pressure cell consists of a single-crystal sapphire tube which serves as both high-pressure container and reaction cell, with up to 6 mm inner diameter. The system can operate in two different configurations, under either static high pressure or dynamic pressurized flow. The transportable reaction cell can be filled under inert atmosphere inside a glove box, enabling studies with oxygen-sensitive compounds to be conducted. The five main benefits of this system can be summarized as follows: (i) the temperature, pressure and gas-flow ranges of 298–1273 K, 10−3 mbar–200 bar (0.1–2 × 107 Pa) and 0–1 l min−1, respectively, (ii) the combination of different gases, (iii) the flexibility of the cell design, (iv) the full rotation of the pressurized cell, and (v) the combination of X-ray diffraction and mass spectrometry as analytical tools. These key points open new possibilities for studying the evolution of catalysts or compounds from a fundamental point of view as well as for industrial applications, in both cases inoperandoconditions.

Stability analysis of 4-species Aβ aggregation model: A novel approach to obtaining physically meaningful rate constants

Protein misfolding and concomitant aggregation towards amyloid formation is the underlying biochemical commonality among a wide range of human pathologies. Amyloid formation involves the conversion of proteins from their native monomeric states (intrinsically disordered or globular) to well-organized, fibrillar aggregates in a nucleation-dependent manner. Understanding the mechanism of aggregation is important not only to gain better insight into amyloid pathology but also to simulate and predict molecular pathways. One of the main impediments in doing so is the stochastic nature of interactions that impedes thorough experimental characterization and the development of meaningful insights. In this study, we have utilized a well-known intermediate state along the amyloid-β peptide aggregation pathway called protofibrils as a model system to investigate the molecular mechanisms by which they form fibrils using stability and perturbation analysis. Investigation of protofibril aggregation mechanism limits both the number of species to be modeled (monomers, and protofibrils), as well as the reactions to two (elongation by monomer addition, and protofibril-protofibril lateral association). Our new model is a reduced order four species model grounded in mass action kinetics. Our prior study required 3200 reactions, which makes determining the reaction parameters prohibitively difficult. Using this model, along with a linear perturbation argument, we rigorously determine stable ranges of rate constants for the reactions and ensure they are physically meaningful. This was accomplished by finding the ranges in which the perturbations dieout in a five-parameter sweep, which includes the monomer and protofibril equilibrium concentrations and three of the rate constants. The results presented are a proof-of-concept method in determining meaningful rate constants that can be used as a bonafide way for determining accurate rate constants for other models involving complex biological reactions such as amyloid aggregation.

Traditional vs wireless intragastric pH monitoring: are the two techniques comparable?

BACKGROUND

Few data are available comparing intragastric pH measured with the traditional catheter-based and the more recent wireless system (Bravo), and also comparing intraesophageal and intragastric pH during reflux events. Aims of our study were to elucidate these points.

METHODS

Eleven subjects with functional dyspepsia underwent placement of a Bravo capsule 9 cm below the squamo-columnar junction (SCJ) and of a dual-electrode catheter, so that the distal electrode was located 9 cm below and the proximal one 6 cm above the SCJ.

KEY RESULTS

The wireless system showed lower intragastric pH than the traditional catheter in the postprandial period (median 2.2 wireless vs 2.7 catheter, P < 0.05) but not in the whole 24 h. Moreover, during the 24 h, minimum intraesophageal pH during reflux events was lower than the simultaneous pH in the gastric body recorded using the catheter (2.2 vs 2.4, P < 0.01) and in the postprandial period lower than the one recorded using both techniques (2.3 vs 2.8 wireless and 3.2 catheter, P < 0.001).

CONCLUSIONS & INFERENCES

(i) after meals, in the 1st 2 h postprandial pH in the gastric body is significantly lower when measured with the wireless capsule than with the traditional catheter, presumably because of less buffering by food in proximity of the mucosa, (ii) during reflux events intraesophageal pH is lower than pH in the gastric body, in accordance with the notion of greater intragastric acidity in the subcardial region.

Ovine amniotic epithelial cells: in vitro characterization and transplantation into equine superficial digital flexor tendon spontaneous defects

In vitro expanded and frosted ovine amniotic epithelial cells (oAECs) were evaluated for their phenotype, stemness and attitude to differentiate into tenocytes. Fifteen horses with acute tendon lesions were treated with one intralesional injection of oAECs. Tendon recovery under controlled training was monitored. In vitro expanded oAECs showed a constant proliferative ability, a conserved phenotype and stable expression profile of stemness markers. Differentiation into tenocytes was also regularly documented. US controls showed the infilling of the defect and early good alignment of the fibers and 12 horses resumed their previous activity. Histological and immunohistochemical examinations in an explanted tendon demonstrated the low immunogenicity of oAECs that were able to survive in the healing site. In addition, oAECs supported the regenerative process producing ovine collagen type I amongst the equine collagen fibers. Considering our results, oAECs can be proposed as a new approach for the treatment of spontaneous equine tendon injuries.

Expression of gelatinases (MMP-2, MMP-9) and cyclooxygenases (COX-1, COX-2) in some benign salivary gland tumors

Salivary gland tumors, most of which are rare benign tumors, represent a histologically heterogenous group with the greatest diversity of morphological and cellular features. The aim of this study is to analyse the expression and possible interactions between gelatinases (MMP-2, MMP-9) and cyclooxygenases (COX-1, COX-2) in some benign salivary gland tumors. We investigated the expression of gelatinases and cyclooxigenases in control salivary gland, Pleomorphic adenoma and Warthin's tumor through immunohistochemistry and Reverse Transcription - Polymerase Chain Reaction (PCR). We identified the expression of both classes of enzyme in normal samples and in the two types of pathological samples without any quantitative differences. From the present data no significant differences emerge in the expression of these enzymes among the different pathologies examined. Nevertheless, due to the small number of samples included in this study, general statements regarding correlation between the degree of severity of the tumoral pathology and the quantitative expression of these potential tumoral markers can not be made.

Characterization, GFP gene Nucleofection, and allotransplantation in injured tendons of ovine amniotic fluid-derived stem cells

Amniotic fluid has drawn increasing attention in the recent past as a cost-effective and accessible source of fetal stem cells. Amniotic fluid-derived mesenchymal stem cells (AFMSCs) that display high proliferation rate, large spectrum of differentiation potential, and immunosuppressive features are considered optimal candidates for allogeneic repair of mesenchymal damaged tissues. In this study, ovine AFMSCs (oAFMSCs) isolated from 3-month-old sheep fetuses were characterized for their proliferation rate, specific surface antigen and pluripotency marker expression, genomic stability, and mesenchymal lineage differentiation during their in vitro expansion (12 passages) and after nucleofection. The high proliferation rate of oAFMSCs gradually decreased during the first six subculture passages while the expression of surface molecules (CD29, CD58, CD166) and of pluripotency-associated markers (OCT4, TERT, NANOG, SOX2), the in vitro osteogenic differentiation potential, and a normal karyotype were maintained. Afterwards, oAFMSCs were nucleofected with a selectable plasmid coding for green fluorescent protein (GFP) using two different programs, U23 and C17, previously optimized for human mesenchymal stem cells. Transfection efficiencies were ∼63% and ∼37%, while cell recoveries were ∼10% and ∼22%, respectively. Nucleofected oAFMSCs expressing the GFP transgene conserved their pluripotency marker profile and retained a normal karyotype and the osteogenic differentiation ability. Seven single clones with a GFP expression ranging from 80% to 97% were then isolated and expanded over 1 month, thus providing stably transfected cells with long-term therapeutic potential. The in vivo behavior of GFP-labeled oAFMSCs was tested on a previously validated preclinical model of experimentally induced Achille's tendon defect. The allotransplanted oAFMSCs were able to survive within the host tissue for 1 month enhancing the early phase of tendon healing as indicated by morphological and biomechanical results. Altogether these data suggest that genetically modified oAFMSCs might represent a valuable tool for in vivo preclinical studies in a highly valid translational model.

Achilles tendon regeneration can be improved by amniotic epithelial cell allotransplantation

Amniotic epithelial cells (AECs) are ideal seed cells for tissue regeneration, but no research has yet been reported on their tendon regeneration potential. This study investigated the efficiency of AEC allotransplantation for tendon healing, as well as the mechanism involved. To this aim ovine AECs, characterized by specific surface and stemness markers (CD14(-), CD31(-), CD45(-), CD49f, CD29, CD166, OCT4, SOX2, NANOG, TERT), were allotransplanted into experimentally induced tissue defects in sheep Achilles tendon. In situ tissue repair revealed that AEC-treated tendons had much better structural and mechanical recoveries than control ones during the early phase of healing. Immunohistochemical and biochemical analyses indicated that extracellular matrix remodeling was more rapid and that immature collagen fibers were completely replaced by mature ones in 28 days. Moreover, spatial-temporal analysis of cellularity, proliferation index, vascular area, and leukocyte infiltration revealed that AECs induced a specific centripetal healing process that first started in the tissue closer to the healthy portion of the tendons, where AECs rapidly migrated to then progress through the core of the lesion. This peculiar healing evolution could have been induced by the growth factor stimulatory influence (TGF-β1 and VEGF) and/or by the host progenitor cells recruitment, but also as the consequence of a direct tenogenic AEC differentiation resulting in the regeneration of new tendon matrix. These findings demonstrate that AECs can support tendon regeneration, and their effects may be used to develop future strategies to treat tendon disease characterized by a poor clinical outcome in veterinary medicine.

Isolation, characterization, and in vitro differentiation of ovine amniotic stem cells

Stem cell (SC) regenerative therapy represents an emerging strategy for the treatment of human diseases. Since amniotic fluid-derived cells have been recently proposed as a promising source of human SCs, the present research aimed to amplify in vitro and characterize ovine amniotic fluid-derived SCs collected from the membranes (AMSCs) or fluid (AFSCs). These cells were found to proliferate, express the pluripotent SC markers OCT-4 and TERT, and differentiate in both osteogenic and smooth muscle lineages in vitro. However, AMSCs presented an earlier down-regulation of SC markers and a faster rate of differentiation. Thus, AMSCs and AFSCs may represent sources of characterized pluripotent SCs that can be easily collected and amplified in vitro. These ovine SCs may be used in preclinical studies on large animals to develop future human therapies.

Experimental study on allografts of amniotic epithelial cells in calcaneal tendon lesions of sheep

An experimental protocol was designed to study the survival and behaviour of an allograft of amniotic epithelial cells (AECs) in an ovine model. The study was conducted on three healthy adult sheep. A core lesion was created in both calcaneal tendons under ultrasound (US) guidance by injecting 400 UI of Type 1A collagenase diluted in 0.6 ml saline. The AECs were obtained from a 60-80-day-old fetus and cultured under standard conditions. After 15 days of collagenase treatment, 2 x 10(6) AECs stained with a vital membrane fluorescent probe (PHK26) were injected under US guidance in 500 microl saline solution into the lesion of one limb. The contralateral untreated limb was used as a control. Animals were euthanatized 7 (1) and 30 (2) days later. Histological analyses performed on explanted tendons clearly demonstrate that AECs survived for at least 1 month inside the lesion without any adverse reactions. The damaged tissue of the treated tendons showed a high number of reparative cells in active proliferation that were accumulating collagen within the extracellular matrix. In addition, after 1 month, the neo-collagen began to be organized into parallel arrays of fibers oriented along the longitudinal axis of the tendon.

Non-linear recurrence analysis of NREM human sleep microstructure discloses deterministic oscillation patterns related to sleep stage transitions and sleep maintenance

Sleep is a dynamic process aimed at obtaining the required neurophysiological states at certain times, according to circadian and homeostatic needs and despite external or internal interfering stimuli. In this context, peculiar transient synchronized EEG patterns (TSEP) are supposed to play the main role in the building up of EEG synchronization and in the flexible adaptation against perturbations Our study aimed at disclosing and quantifying attractor driven, hidden periodicity or, conversely, chaotic oscillation patterns in the series of these TSEP related to sleep stage transitions and sleep maintenance. At first we devised a multistep algorithm, able to capture TSEP from EEG during sleep in 10 healthy volunteers. The time series of TSEP were then analyzed according to the Recurrence Plot (RP). TSEP series showed to form a pseudo-periodic series which becomes progressively denser and more stable until steady slow wave NREM sleep is reached, but looses stability just before REM sleep starts. This suggests that deterministic oscillatory patterns maybe adequate descriptors of the balance between homeostatic needs for NREM sleep and REM sleep pressure, supported by different cortical neuronal populations interactions.

Immunohistochemical and biomolecular identification of orphanin FQ, eNOS, atrial natriuretic factor and oxytocin in rat seminal vesicles

In previous studies performed on rodents, we detected the presence of adreno-cholinergic and peptidergic innervation in seminal vesicles and other organs of the male genital system, such as prostate and deferent duct, in which we also investigated the expression of NOS and NADPH-diaphorase. During this project, we focused our attention on the expression of some peptides involved in local control of smooth muscle relaxation, contractility, vasodilatation and control of blood flow in rat seminal vesicles. We investigated, through immunohistochemistry and RT-PCR, the presence of four peptides: orphanin, eNOS, ANF and oxytocin. Immunohistochemistry was used to detect the presence of the proteins, whereas RT-PCR analysis confirmed gene expression of orphanin, eNOS and ANF, but not oxytocin. In our opinion, orphanin, eNOS and ANF could have paracrine effects regulating the function of seminal vesicles, whereas oxytocin, which may reach this anatomical district through the blood flow, may have a hormonal action. This is a pilot study that, with further investigation, may allow to better clarify the role of these molecules in the control of seminal vesicle tissues' homeostasis.

Fusion as the result of sperm–somatic cell interaction

The research has been designed to investigate whether acrosome-reacted spermatozoa can fuse with somatic cells and to check whether this event may involve the molecular machinery implicated in the sperm–egg fusion. Boar spermatozoa were capacitatedin vitroand then treated with A23187 to induce acrosome reaction and activate their fusogenic potential. Reacted spermatozoa, loaded with the membrane-permeant fluorescent dye calcein AM, were incubated with plated granulosa cells or cells derived from stable cell lines: CRFK, VERO, and ESK4. The fusion between spermatozoa and somatic cells was revealed by the diffusion of the fluorescent dye from the sperm to the cell as membrane fusion and cytoplasmic continuity between the two cells were established. The involvement of integrin α6 and tetraspanin CD9 in the process of fusion was assessed by carrying out the experiment in the presence of antibodies against these molecules. Moreover, the incidence of fusion displayed by the different cell types used was analyzed in relation to their content in the above molecules assessed by western blot and immunostaining. The role of CD9 was additionally investigated by using CD9-negative cells. The data presented demonstrate that boar spermatozoa can fuse with different somatic cell types derived from different species and the process requires the combined presence of both integrin and tetraspanin molecules on the cell plasma membrane.

Immunohistochemical and transcriptional expression of the matrix metalloproteinases MMP-2 and MMP-9 in normal and pathological human oral mucosa

The oral cavity is exposed to chronic or recurrent, physical and chemical trauma that could lead to mucosal reactions (e.g. hyperplasia, dysplasia and tumors). The objective of this study is to investigate the expression and the possible changes of the two matrix metalloproteinases MMP-2 and MMP-9 in normal and pathological human oral mucosa samples. Normal oral mucosa samples and three different types of pathological conditions (hyperplasia, dysplasia and carcinoma) were used for this study. Immunohistochemical analysis was used to evaluate protein expression for the two enzymes, while Reverse Transcription ? Polymerase Chain Reaction (RT-PCR) was used to investigate gene expression. Image analysis was used to give a quantitative evaluation of the immunohistochemical data. In control samples we identified a weak expression of both MMP-2 and MMP-9 in the epithelial layers. In hyperplasia samples MMPs expression is limited to epithelial layers but the immunoreactivity is more intense than in the control. In dysplasia and carcinoma samples the two matrix metalloproteases are expressed not only in epithelium but also in some cells of the connective tissue and in the vessel walls. Qualitative RT-PCR and image analysis confirmed the immunohistochemical data. The results obtained in this study suggest the existence of a possible relationship between the entity of morphological disorganization of the oral mucosa in different pathologies and the increase of MMP-2 and MMP-9 expression.

An atypical case of sporadic fatal insomnia

Fatal insomnia is a rare human prion disease characterised by sleep-wake disturbances, thalamic degeneration and deposition of type 2 disease-specific prion protein (PrP(Sc)). This report details a patient with sporadic fatal insomnia who exhibited cerebral deposition of type 1 PrP(Sc) and neuropathological changes largely in the basal ganglia. Previous damage of this brain region by a surgically removed colloid cyst and the insertion of two intracerebral shunts may have influenced the distribution of PrP(Sc) through a chronic inflammatory process. These findings add to our knowledge of the phenotypic variability of human prion diseases with prominent sleep disturbances.

Space Charge Regions in Fixed Charge Membranes and the Associated Property of Capacitance

The Poisson-Boltzmann equation, which was derived by Shockley in his treatment of the p-n semiconductor junction at equilibrium, is applied to fixed charge ionic membranes. The fixed charges in ionic membranes play the same role as "doping" ions in semiconductors, the major difference between the two systems being that in the former the mobile particles are ions while in the latter the particles are electrons and phenomenological particles, "holes." An important consequence of spatial gradients of fixed charge is the presence of space charge regions which give rise to an intrinsic electric field and potential. These quantities are established first for the single "lattice" thus providing a continuous treatment of the Donnan equilibrium invoked by Teorell-Meyer-Sievers in their treatment of fixed charge membranes. It is shown further that when a positive and negative membrane are juxtaposed, the space charge region in the "junction" so formed provides a mechanism for the storage of electrical energy. Thus while the system is basically a "conductor" the presence of transition regions of fixed charge give rise to the additional property of capacitance. Experimental data are presented on ionic and p-n junctions. The implications of this mechanism for the physical basis of capacitance in biological cells are discussed.

Equivalent Circuits as Related to Ionic Systems

The purpose of this paper is to clarify the relationship between certain "equivalent circuits" and the fundamental flux equations of Nernst and Planck. It is shown that as a direct algebraic consequence of these equations one may construct two types of equivalent circuits for a homogeneous (charged or uncharged) membrane. The one, which we term the "pure electrical equivalent circuit," correctly predicts all of the electrical properties of the membrane for both steady and transient states. The other, which we call the "mixed equivalent circuit," predicts the steady state I, Psi characteristics of the membrane and the steady state ionic fluxes; it is not applicable to non-steady state properties or measurements. We emphasize that with regard to the portrayal of the physical basis of the properties of a homogeneous membrane, the mixed equivalent circuit can be misleading. This is particularly significant because this same circuit can also be used to depict a mosaic membrane, in which case the circuit gives a realistic pictorialization of the physical origin of the membrane properties. It is hoped that our analysis will be of aid to workers in electrophysiology who make use of equivalent circuit terminology in discussing the behavior of the plasma membrane.