Influence of the isolation method on characteristics and functional activity of mesenchymal stromal cell-derived extracellular vesicles

BACKGROUND AIMS

Extracellular vesicle (EV) isolation methods are based on different physicochemical properties and may result in the purification of distinct EV populations. We compared two different isolation methods suitable for producing clinical-grade mesenchymal stromal cell-derived EVs (MSC-EVs)-ion exchange chromatography (IEX) and ultrafiltration (UF)-and evaluated their impact on the composition and functional properties of EVs.

METHODS

EVs were purified from conditioned culture medium using an anion exchange resin (IEX) or Amicon filters with a 100-kDa cutoff (UF) (MilliporeSigma, Burlington, MA, USA). We assessed nanoparticle size and distribution by nanoparticle tracking analysis (NTA) and tunable resistive pulse sensing (TRPS) and morphology by transmission electron microscopy. We also measured protein, lipid and total RNA concentration and immunophenotyped both EV populations by flow cytometry (MACSPlex assay; Miltenyi Biotec, Bergisch Gladbach, Germany). Moreover, immunomodulatory activity was tested using a standardized macrophage polarization assay and T-cell stimulation assay. Finally, proteomic analysis and cytokine quantification were carried out to better characterize both EV populations.

RESULTS

We found by both TRPS and NTA that IEX and UF yielded a comparable amount of total particles with similar size and distribution. In addition, a similar quantity of lipids was obtained with the two procedures. However, IEX yielded 10-fold higher RNA quantity and a larger amount of proteins than UF. MSC-EVs isolated from IEX and UF were positive for the exosome markers CD9, CD63 and CD81 and showed a comparable surface marker expression pattern. Both populations demonstrated immunomodulatory activity in vitro, as they prevented acquisition of the M1 phenotype in lipopolysaccharide-stimulated macrophages and inhibited acquisition of the activation markers CD69 and CD25 on T cells, but the IEX-EVs exerted a significantly greater immunomodulatory effect on both macrophages and T cells compared with UF-EVs. Proteomic analysis and gene ontology enrichment analysis revealed no major differences between the preparations. Finally, cytokine quantification revealed that IEX-EVs were more enriched in some crucial anti-inflammatory and immunomodulatory cytokines (e.g., IL-2, IL-10, transforming growth factor beta and vascular endothelial growth factor) compared with UF-EVs.

CONCLUSIONS

MSC-EVs isolated by IEX and UF displayed similar physicochemical, phenotypic and functional characteristics. In our conditions, both EV populations demonstrated important anti-inflammatory activity in macrophages and T cells. However, IEX-EVs were more potent than UF-EVs, which may indicate the superiority of this method for the production of clinical-grade EVs.

Loss of the batten disease protein CLN3 leads to mis-trafficking of M6PR and defective autophagic-lysosomal reformation

Batten disease, one of the most devastating types of neurodegenerative lysosomal storage disorders, is caused by mutations in CLN3. Here, we show that CLN3 is a vesicular trafficking hub connecting the Golgi and lysosome compartments. Proteomic analysis reveals that CLN3 interacts with several endo-lysosomal trafficking proteins, including the cation-independent mannose 6 phosphate receptor (CI-M6PR), which coordinates the targeting of lysosomal enzymes to lysosomes. CLN3 depletion results in mis-trafficking of CI-M6PR, mis-sorting of lysosomal enzymes, and defective autophagic lysosomal reformation. Conversely, CLN3 overexpression promotes the formation of multiple lysosomal tubules, which are autophagy and CI-M6PR-dependent, generating newly formed proto-lysosomes. Together, our findings reveal that CLN3 functions as a link between the M6P-dependent trafficking of lysosomal enzymes and lysosomal reformation pathway, explaining the global impairment of lysosomal function in Batten disease.

Development of a platform of 3D adipogenesis to model, at higher scale, the impact of LY2090314 compound on fibro/adipogenic progenitor adipogenic drift

In human dystrophies, the progressive muscle wasting is exacerbated by ectopic deposition of fat and fibrous tissue originating from fibro/adipogenic progenitors (FAPs). In degenerating muscles, the ability of these cells to adjuvate a successful healing is attenuated and FAPs aberrantly expand and differentiate into adipocytes and fibroblasts. Thus, arresting the fibroadipogenic fate of FAPs, without affecting their physiological role, represents a valuable therapeutic strategy for patients affected by muscle diseases. Here, using a panel of adipose progenitor cells including human-derived FAPs coupled with pharmacological perturbations and proteome profiling, we report that LY2090314 interferes with a genuine adipogenic program acting as WNT surrogate for the stabilization of a competent b-catenin transcriptional complex. To predict the beneficial impact of LY2090314 in limiting ectopic deposition of fat in human muscles, we combined the Poly-Ethylene-Glycol-Fibrinogen biomimetic matrix with these progenitor cells to create a miniaturized 3D model of adipogenesis. Using this scalable system, we demonstrated that a two-digit nanomolar dose of this compound is effective to repress adipogenesis in a higher 3D scale, thus offering a concrete proof for the use of LY2090314 to limit FAP-derived fat infiltrates in dystrophic muscles.

Small intestinal submucosa-derived extracellular matrix as a heterotopic scaffold for cardiovascular applications

Structural cardiac lesions are often surgically repaired using prosthetic patches, which can be biological or synthetic. In the current clinical scenario, biological patches derived from the decellularization of a xenogeneic scaffold are gaining more interest as they maintain the natural architecture of the extracellular matrix (ECM) after the removal of the native cells and remnants. Once implanted in the host, these patches can induce tissue regeneration and repair, encouraging angiogenesis, migration, proliferation, and host cell differentiation. Lastly, decellularized xenogeneic patches undergo cell repopulation, thus reducing host immuno-mediated response against the graft and preventing device failure. Porcine small intestinal submucosa (pSIS) showed such properties in alternative clinical scenarios. Specifically, the US FDA approved its use in humans for urogenital procedures such as hernia repair, cystoplasties, ureteral reconstructions, stress incontinence, Peyronie's disease, penile chordee, and even urethral reconstruction for hypospadias and strictures. In addition, it has also been successfully used for skeletal muscle tissue reconstruction in young patients. However, for cardiovascular applications, the results are controversial. In this study, we aimed to validate our decellularization protocol for SIS, which is based on the use of Tergitol 15 S 9, by comparing it to our previous and efficient method (Triton X 100), which is not more available in the market. For both treatments, we evaluated the preservation of the ECM ultrastructure, biomechanical features, biocompatibility, and final bioinductive capabilities. The overall analysis shows that the SIS tissue is macroscopically distinguishable into two regions, one smooth and one wrinkle, equivalent to the ultrastructure and biochemical and proteomic profile. Furthermore, Tergitol 15 S 9 treatment does not modify tissue biomechanics, resulting in comparable to the native one and confirming the superior preservation of the collagen fibers. In summary, the present study showed that the SIS decellularized with Tergitol 15 S 9 guarantees higher performances, compared to the Triton X 100 method, in all the explored fields and for both SIS regions: smooth and wrinkle.

Phosphorylation of FAM134C by CK2 controls starvation-induced ER-phagy

Selective degradation of the endoplasmic reticulum (ER) via autophagy (ER-phagy) is initiated by ER-phagy receptors, which facilitate the incorporation of ER fragments into autophagosomes. FAM134 reticulon family proteins (FAM134A, FAM134B, and FAM134C) are ER-phagy receptors with structural similarities and nonredundant functions. Whether they respond differentially to the stimulation of ER-phagy is unknown. Here, we describe an activation mechanism unique to FAM134C during starvation. In fed conditions, FAM134C is phosphorylated by casein kinase 2 (CK2) at critical residues flanking the LIR domain. Phosphorylation of these residues negatively affects binding affinity to the autophagy proteins LC3. During starvation, mTORC1 inhibition limits FAM134C phosphorylation by CK2, hence promoting receptor activation and ER-phagy. Using a novel tool to study ER-phagy in vivo and FAM134C knockout mice, we demonstrated the physiological relevance of FAM134C phosphorylation during starvation-induced ER-phagy in liver lipid metabolism. These data provide a mechanistic insight into ER-phagy regulation and an example of autophagy selectivity during starvation.

Compositional and Morphological Characterization of ‘Sorrento’ and ‘Chandler’ Walnuts

In Italy, most of the cultivated walnuts belong to the Sorrento ecotype, and they are considered commercially valuable due to their specific organoleptic characteristics. The aim of this study is to evaluate and compare the morphological and compositional characteristics of walnuts sampled from ‘Sorrento’ trees cultivated in different locations in Campania and trees of both the ‘Chandler’ and ‘Sorrento’ varieties derived from the same location. The results demonstrated that ‘Sorrento’ and ‘Chandler’ walnuts have different biometric characteristics and a different fat content, with the highest fat content being found in the ‘Sorrento’ variety. Regarding the fatty acid (FA) composition, the content of monounsaturated and saturated fatty acids (MUFAs and SFAs) was highest in the ‘Sorrento’ variety (from 13 to 15% for MUFAs and from 11 to 13% for SFAs), while the polyunsaturated fatty acids (PUFAs) content was highest in the ‘Chandler’ variety (77%). The total phenolics content (TPC) was highest in the ‘Sorrento’ variety (from 910 to 1230 mg GAE/100 g), while no difference in γ-tocopherol content was found. Furthermore, the influence of walnut area cultivation was shown for fat content, FA composition and TPC. Therefore, both walnut varieties demonstrated good nutritional properties considering the PUFAs and γ-tocopherol content.

Effect of the substrate on the electrical transport and fluctuation processes in NbRe and NbReN ultrathin films for superconducting electronics applications

NbRe-based superconducting thin films recently received relevant interest in the field of low-temperature electronics. However, for these materials the electrical conduction mechanisms, in particular in the normal state, still need to be investigated in more detail. Here, NbRe and NbReN films of different thicknesses have been deposited on two different substrates, namely monocrystalline Si and [Formula: see text] buffered Si. The films were characterized by DC electrical transport measurements. Moreover, a connection with the charge carriers fluctuation processes has been made by analyzing the electrical noise generated in the normal state region. Despite the films morphology seems not to be affected by the substrate used, a lower noise level has been found for the ones grown on [Formula: see text], in particular for NbReN. From this study it emerges that both NbRe and NbReN ultrathin films are of very good quality, as far as the low-temperature electrical noise and conduction are concerned, with noise levels competitive with NbN. These results may further support the proposal of using these materials in a nanowire form in the field of superconducting electronics.

Role of FAM134 paralogues in endoplasmic reticulum remodeling, ER-phagy, and Collagen quality control

Degradation of the endoplasmic reticulum (ER) via selective autophagy (ER‐phagy) is vital for cellular homeostasis. We identify FAM134A/RETREG2 and FAM134C/RETREG3 as ER‐phagy receptors, which predominantly exist in an inactive state under basal conditions. Upon autophagy induction and ER stress signal, they can induce significant ER fragmentation and subsequent lysosomal degradation. FAM134A, FAM134B/RETREG1, and FAM134C are essential for maintaining ER morphology in a LC3‐interacting region (LIR)‐dependent manner. Overexpression of any FAM134 paralogue has the capacity to significantly augment the general ER‐phagy flux upon starvation or ER‐stress. Global proteomic analysis of FAM134 overexpressing and knockout cell lines reveals several protein clusters that are distinctly regulated by each of the FAM134 paralogues as well as a cluster of commonly regulated ER‐resident proteins. Utilizing pro‐Collagen I, as a shared ER‐phagy substrate, we observe that FAM134A acts in a LIR‐independent manner and compensates for the loss of FAM134B and FAM134C, respectively. FAM134C instead is unable to compensate for the loss of its paralogues. Taken together, our data show that FAM134 paralogues contribute to common and unique ER‐phagy pathways.

Reviewing chemical and biological risks in urban agriculture: A comprehensive framework for a food safety assessment of city region food systems

Attention to urban agriculture (UA) has recently grown among practitioners, scientists, and the public, resulting in several initiatives worldwide. Despite the positive perception of modern UA and locally grown, fresh produce, the potential food safety risks connected to these practices may be underestimated, leading to regulatory gaps. Thus, there is a need for assessment tools to evaluate the food safety risks connected to specific UA initiatives, to assist practitioners in self-evaluation and control, and to provide policy makers and scholars a means to pursue and assess food safety in city regions, avoiding either a lack or an excess of regulation that could ultimately hinder the sector. To address this aim, this paper reviews the most recent and relevant literature on UA food safety assessments. Food safety indicators were identified first. Then, a food safety assessment framework for UA initiatives was developed. The framework uses business surveys and food analyses (if available) as a data source for calculating a food safety index for single UA businesses and the whole UA landscape of a given city region. The proposed framework was designed to allow its integration into the CRFS (City Region Food System) toolkit developed by FAO (Food and Agriculture Organization of the United Nations), RUAF foundation (Resource Centres on Urban Agriculture and Food Security) and Wilfrid Laurier University.

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Connection of several biological and chemical food safety risks to UA techniques.

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Identifiable food safety risk factors for diverse UA practices.

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Framework for the assessment of food safety levels of UA initiatives.

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Development of a risk-based assessment that can be integrated into the FAO CRFS framework.

NbN superconducting nanonetwork fabricated using porous silicon templates and high-resolution electron beam lithography

Superconducting NbN nanonetworks with a very small number of interconnected nanowires, with diameter of the order of 4 nm, are fabricated combining a bottom-up (use of porous silicon nanotemplates) with a top-down technique (high-resolution electron beam lithography). The method is easy to control and allows the fabrication of devices, on a robust support, with electrical properties close to a one-dimensional superconductor that can be used fruitfully for novel applications.

Enteric glia: A new player in inflammatory bowel diseases

In addition to the well-known involvement of macrophages and neutrophils, other cell types have been recently reported to substantially contribute to the onset and progression of inflammatory bowel diseases (IBD). Enteric glial cells (EGC) are the equivalent cell type of astrocyte in the central nervous system (CNS) and share with them many neurotrophic and neuro-immunomodulatory properties. This short review highlights the role of EGC in IBD, describing the role played by these cells in the maintenance of gut homeostasis, and their modulation of enteric neuronal activities. In pathological conditions, EGC have been reported to trigger and support bowel inflammation through the specific over-secretion of S100B protein, a pivotal neurotrophic factor able to induce chronic inflammatory changes in gut mucosa. New pharmacological tools that may improve the current therapeutic strategies for inflammatory bowel diseases (IBD), lowering side effects (i.e. corticosteroids) and costs (i.e. anti-TNFα monoclonal antibodies) represent a very important challenge for gastroenterologists and pharmacologists. Novel drugs capable to modulate enteric glia reactivity, limiting the pro-inflammatory release of S100B, may thus represent a significant innovation in the field of pharmacological interventions for inflammatory bowel diseases.

Superconducting nanowire quantum interference device based on Nb ultrathin films deposited on self-assembled porous Si templates

Magnetoresistance oscillations were observed on networks of superconducting ultrathin Nb nanowires presenting evidence of either thermal or quantum activated phase slips. The magnetic transport data, discussed in the framework of different scenarios, reveal that the system behaves coherently in the temperature range where the contribution of the fluctuations is important.

Distinct subcellular localization of the neuronal marker HuC/D reveals hypoxia-induced damage in enteric neurons

BACKGROUND

Correct neuronal identification is essential to study neurons in health and disease. Although commonly used as pan-neuronal marker, HuC/D's expression pattern varies substantially between healthy and (patho)physiological conditions. This heterogenic labeling has received very little attention. We sought to investigate the subcellular HuC/D localization in enteric neurons in different conditions.

METHODS

The localization of neuronal RNA-binding proteins HuC/D was investigated by immunohistochemistry in the mouse myenteric plexus using different toxins and caustic agents. Preparations were also stained with Sox10 and glial fibrillary acidic protein (GFAP) antibodies to assess enteric glial cell appearance.

KEY RESULTS

Mechanically induced tissue damage, interference with the respiratory chain and oxygen (O2 ) deprivation increased nuclear HuC/D immunoreactivity. This effect was paralleled by a distortion of the GFAP-labeled glial network along with a loss of Sox10 expression and coincided with the activation of a non-apoptotic genetic program. Chemically induced damage and specific noxious stimuli did not induce a change in HuC/D immunoreactivity, supporting the specific nature of the nuclear HuC/D localization.

CONCLUSIONS & INFERENCES

HuC/D is not merely a pan-neuronal marker but its subcellular localization also reflects the condition of a neuron at the time of fixation. The functional meaning of this change in HuC/D localization is not entirely clear, but disturbance in O2 supply in combination with the support of enteric glial cells seems to play a crucial role. The molecular consequence of changes in HuC/D expression needs to be further investigated.

Neurotransmitters involved in fast excitatory neurotransmission directly activate enteric glial cells

BACKGROUND

The intimate association between glial cells and neurons within the enteric nervous system has confounded careful examination of the direct responsiveness of enteric glia to different neuroligands. Therefore, we aimed to investigate whether neurotransmitters known to elicit fast excitatory potentials in enteric nerves also activate enteric glia directly.

METHODS

We studied the effect of acetylcholine (ACh), serotonin (5-HT), and adenosine triphosphate (ATP) on intracellular Ca(2+) signaling using aequorin-expressing and Fluo-4 AM-loaded CRL-2690 rat and human enteric glial cell cultures devoid of neurons. The influence of these neurotransmitters on the proliferation of glia was measured and their effect on the expression of c-Fos as well as glial fibrillary acidic protein (GFAP), Sox10, and S100 was examined by immunohistochemistry and quantitative RT-PCR.

KEY RESULTS

Apart from ATP, also ACh and 5-HT induced a dose-dependent increase in intracellular Ca(2+) concentration in CRL-2690 cells. Similarly, these neurotransmitters also evoked Ca(2+) transients in human primary enteric glial cells obtained from mucosal biopsies. In contrast with ATP, stimulation with ACh and 5-HT induced early gene expression in CRL-2690 cells. The proliferation of enteric glia and their expression of GFAP, Sox10, and S100 were not affected following stimulation with these neurotransmitters.

CONCLUSIONS & INFERENCES

We provide evidence that enteric glial cells respond to fast excitatory neurotransmitters by changes in intracellular Ca(2+). On the basis of our experimental in vitro setting, we show that enteric glia are not only directly responsive to purinergic but also to serotonergic and cholinergic signaling mechanisms.

Increased severity of dyspeptic symptoms related to mental stress is associated with sympathetic hyperactivity and enhanced endocrine response in patients with postprandial distress syndrome

BACKGROUND

Mental stress (MS) may alter gastric sensory-motor function. The aim of the study was to assess postprandial autonomic nervous system activity and stress hormones in response to acute mental stress in dyspeptic patients.

METHODS

A total of 25 patients with postprandial distress syndrome (PDS; 11 mol L(-1), age 35.9 ± 9.3 years) and 12 healthy controls (5 mol L(-1), age 25.8 ± 4.6 years) underwent electrogastrography and (13) C-octanoate gastric emptying study using a 480 kcal solid meal. Heart rate variability (LF/HF ratio) and corticotrophin-releasing factor, adrenocorticotropic hormone (ACTH), and cortisol serum levels were also evaluated. Dyspeptic symptoms were scored by analogue visual scale and expressed as symptoms total score (TS). The protocol was repeated twice in each subject, with and without a mental stress test before the meal.

KEY RESULTS

Mental stress significantly increased postprandial symptoms severity in patients (TS: stress 111 ± 18 vs basal 50 ± 10; P < 0.05). Low-/high-frequency component ratio was significantly higher in patients after MS at 120 min (stress 5.46 ± 0.41 vs basal 3.41 ± 0.64; P < 0.01) and 180 min (stress 5.29 ± 0.2 vs basal 3.58 ± 0.19; P < 0.05). During stress session, in patients we found a significantly higher ACTH level than baseline at 30, 60, 90, 150, 210, 240, and 270 min and a significantly higher cortisol level at 30, 60, 90, 120, 210, and 270 min. Gastric emptying rate and electrical activity were not influenced by MS.

CONCLUSIONS & INFERENCES

In PDS patients, administration of MS before meal increases symptoms severity by inducing sympathetic hyperactivity and increased stress hormones levels. As the gastric emptying looks not altered, we conclude that these neurohormonal responses mainly affect sensitive function.

Role of serotonin in gastrointestinal physiology and pathology

Serotonin is one of the most abundant molecules in the gastrointestinal tract and it plays a crucial role in the regulation of several physiological functions, such as motility, secretion and visceral sensitivity. Besides this well documented physiological role, increasing evidence supports the concept that 5-HT is directly involved in pathological mechanisms, as well as the modulation of immune/inflammatory responses within the gut. The wide range of pathophysiological actions exerted by 5-HT are mediated by several different serotonergic receptor types and subtypes. Depending on the receptor bound and its localization, 5-HT evokes different and, sometimes, opposite responses. Therapeutic interventions aiming at modulating 5-HT signaling are mainly focused on the development of receptor agonists/antagonists, characterized by high affinity and selectivity for serotonergic receptors in the gut, to avoid the presence of adverse effects in the brain, where 5-HT is important in control mood. This review summarizes the vast current knowledge on 5-HT as a physiological mediator and analyzes the increasing body of literature describing 5-HT signaling abnormalities in functional and inflammatory disorders both in animal models and in humans. Finally, an overview on the therapeutic agents used in clinical practice is provided.

Proinflammatory stimuli activates human-derived enteroglial cells and induces autocrine nitric oxide production

BACKGROUND

Enteric glial cells (EGCs) have been recently indicated as key regulators of intestinal inflammation in animals. Whether or not this is true and how these cells participate to inflammatory responses in humans is unknown.

METHODS

We isolated primary EGCs from human small bowel and then, we purified and characterized those using specific glial markers, such as S100B and glial fibrillary acidic protein (GFAP). To mimic an inflammatory scenario, we exposed EGCs to exogenous stimuli, such as lipopolysaccharide and interferon-gamma (LPS and IFN-γ), alone or in combination, to evaluate glial activation [measuring GFAP, S100B level together with c-fos, major histocompatibility complex (MHC) class II, inducible nitric oxide (iNOS) proteins expression and nitric oxide (NO) production] and proliferation, respectively.

KEY RESULTS

We showed that, when challenged with a combination of LPS and IFN-γ, EGCs are significantly activated, as indicated by their positivity to c-fos and MHC class II. Similarly, pro-inflammatory stimuli significantly increase the cell proliferation rate, the expression of both S100B and GFAP, and the NO production consequent to the induction of EGCs-derived iNOS protein, with the last being dependent on S100B-RAGE (receptor for advanced glycation endproducts) interaction.

CONCLUSIONS & INFERENCES

Our data provide the first evidence that human EGCs directly respond to pro-inflammatory stimuli by changing their expression profile and by proliferating. The finding that stimulated EGCs are able to produce NO points to a role of this cell population in the scenario of intestinal inflammation.

Increased mucosal nitric oxide production in ulcerative colitis is mediated in part by the enteroglial-derived S100B protein

In the central nervous system glial-derived S100B protein has been associated with inflammation via nitric oxide (NO) production. As the role of enteroglial cells in inflammatory bowel disease has been poorly investigated in humans, we evaluated the association of S100B and NO production in ulcerative colitis (UC). S100B mRNA and protein expression, inducible NO synthase (iNOS) expression, and NO production were evaluated in rectal biopsies from 30 controls and 35 UC patients. To verify the correlation between S100B and NO production, biopsies were exposed to S100B, in the presence or absence of specific receptor for advanced glycation end-products (RAGE) blocking antibody, to measure iNOS expression and nitrite production. S100B and iNOS expression were evaluated after incubation of biopsies with lipopolysaccharides (LPS) + interferon-gamma (IFN-gamma) in the presence of anti-RAGE or anti-S100B antibodies or budesonide. S100B mRNA and protein expression, iNOS expression and NO production were significantly higher in the rectal mucosa of patients compared to that of controls. Exogenous S100B induced a significant increase in both iNOS expression and NO production in controls and UC patients; this increase was inhibited by specific anti-RAGE blocking antibody. Incubation with LPS + IFN-gamma induced a significant increase in S100B mRNA and protein expression, together with increased iNOS expression and NO production. LPS + IFN-gamma-induced S100B up-regulation was not affected by budesonide, while iNOS expression and NO production were significantly inhibited by both specific anti-RAGE and anti-S100B blocking antibodies. Enteroglial-derived S100B up-regulation in UC participates in NO production, involving RAGE in a steroid insensitive pathway.

Upper critical magnetic fields in superconductor/ferromagnet hybrids

We measured parallel upper critical magnetic fields in Nb/PdNi and Nb/CuNi bilayers and Nb/PdNi/Nb and Nb/CuNi/Nb trilayers. In the bilayers case the measurements reveal a dependence of the reduced two-dimensional-three-dimensional crossover temperature, t(cr) = T(cr)/T(c), on the different values of the superconductor (S)/ferromagnet (F) interface transparencies. In the case of the trilayers we observe that the reduced crossover temperature as a function of the ferromagnetic layer thickness, d(F), reaches a value equal to one only when the π-phase occurs in these systems. Also in this case the influence of the interface transparency on the observed results is discussed.

Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films

We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

Sweetened carbonated drinks do not alter upper digestive tract physiology in healthy subjects

Sweetened carbonated beverages are widely consumed, which has fuelled several conflicting opinions about their effects on upper digestive tract functions. We aimed to evaluate the effect of sweetened carbonated drinks, consumed with a standard meal, on gastro-oesophageal reflux, gastric emptying and gallbladder contraction and postmeal sensations in healthy subjects. Thirteen healthy volunteers (seven women, six males; median age 22 years) were tested following the intake of 300 mL sweetened water containing increasing concentrations of carbon dioxide (seven subjects), and of 300 mL sweetened commercial flavoured drink with and without carbon dioxide (six subjects). Gastro-oesophageal reflux, gastric emptying and gallbladder contraction were studied by pH-impedance, octanoic acid breath test and ultrasound respectively. Gastro-oesophageal refluxes were significantly increased 1 h after meal with both water and commercial beverages; only sweetened water without carbon dioxide determined a persistently increasing number of refluxes 2 h postmeal. No differences were found for gastric emptying, gallbladder contraction or postmeal symptoms with any of the beverages tested. This study shows that 300 mL of sweetened carbonated beverage with different levels of carbonation or a commercial soft drink do not modify the physiology of the upper digestive tract.

[The Hartmann procedure in colorectal emergencies. Report of 76 cases]

The Hartmann procedure has, in emergency colo-rectal surgery, many implications. The decision is based on clinical, radiological, instrumental and pathological findings. The authors report the results of 76 Hartmann's procedures performed between 1986 and 1995 and compare their results with those found in the current medical literature on the topic. In particular, they draw attention to an increased use of this procedures in colo-rectal emergencies; the morbility and mortality rates confirm the severity of the clinical cases that can be treated with this operation. To improve results the authors propose a therapeutic plan that uses a score for stratification of the risk (MPI, APA-CHE II, SSI, Hinchey); so the surgeon can choose the best surgical operation. Finally, the authors underline the importance of the principles of oncology surgery in colo-rectal cancer.

Adhesion of human neuroblasts to HIV-1 tat

Several neuropathologic findings in infants and children with human immunodeficiency virus type-1 (HIV-1) infection are different from those observed in adults, probably related to the fact that the retroviral infection occurs in the setting of neuro-development. This report describes the interaction and biologic activity of tat, the HIV-1 trans-activating protein on human neuroblasts. Two human neuroblastoma cell lines, LAN-5 and GI-CA-N, have been studied for their capability to adhere to tat (full recombinant protein) and to two different peptide residues of it. Both cells adhere to tat and tat46-60 basic domain, although not to tat65-80 residue, which contains the RGD (arginine-glycine-aspartic acid) motif. Adhesion to collagen I was inhibited by preincubating GI-CA-N cells with tat,46-60 although not with tat,65-80 indicating the capability of the basic residue to interfere with collagen I-induced cellular adhesion. The expression of 200-kD neurofilaments induced by collagen I was not induced by tat,46-60 indicating that neural differentiation along the same pathway is not mimicked by this peptide. Neuroblast cell proliferation was not affected by adhesion to tat46-60 nor to tat.65-80 GI-CA-N cells are not permissive to HIV-1 infection. However, proviral DNA was documented in the cell lysate for 14 consecutive in vitro passages, whereas HIV-1 transcription was never detectable. This would exclude the possibility that tat would be transduced by these cells. GI-CA-N stained negative for CD4, although positive for Gal-C, which may explain HIV-1 entry. Results show that immature human neural cells interact with tat protein and/or its basic residue in vitro. A mechanism similar to that herein described would possibly be active in vivo, which may help in clarifying the pathogenic mechanisms of neurologic dysfunction and destruction of the CNS observed in infants infected with HIV-1.

Effect of interferon-alpha therapy in a patient with common variable immunodeficiency and chronic Epstein-Barr virus infection

We report an 18-year-old boy with common variable immunodeficiency who presented with splenomegaly as well as left axillary and lateral cervical lymphadenopathy. Main laboratory investigations showed severe thrombocytopenia. Epstein-Barr virus (EBV) DNA was detected in the patient's throat-washing specimens and lymph node biopsy. Lymphocytes from the lymph node biopsy were also positive for EBV nuclear antigen. Serology for EBV and cytomegalovirus was negative. A therapeutic attempt with acyclovir did not influence the course of infection. Six months' treatment with human lymphoblastoid interferon-alpha (IFN alfa) brought about the normalization of clinical and hematologic conditions. Detection on throat-washing specimens carried out 1 year after therapy was negative. Our preliminary experience suggests that human lymphoblastoid IFN-alpha is a valid alternative in therapy of immunodeficient EB virus-infected patients.

Dual-centre, double-blind, randomised trial of lymphoblastoid interferon alpha with or without steroid pretreatment in children with chronic hepatitis B

Thirty-five children with chronic HBV infection, HBV-DNA and eAg serum positivity, and HBcAg in liver tissue were treated with lymphoblastoid human interferon alpha with (16 cases) or without (19 cases) prednisolone pretreatment. The patients were double-blind randomized to receive steroid or placebo for 4 weeks, followed after 2 weeks by 5 or 10 MU/m2 interferon for 12 weeks. The e anti-e seroconversion rate reached 48%, which is much higher than the spontaneous seroconversion rate. The influence of "prednisolone priming" was not statistically significant. HBeAg clearance was similar in both groups (44% after prednisolone/interferon and 53% after interferon alone). The response to either treatment did not correlate with the pretreatment serum transaminase. HBV-DNA or degree of histological activity. Interferon was well tolerated, the side effects being less severe than in adults, and never led to suspension of the treatment.

Occurrence of human immunodeficiency virus type 1 (HIV-1)-specific cytolytic T cell activity in apparently uninfected children born to HIV-1-infected mothers

Human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T lymphocyte (CTL) activity against different viral antigens, including env, gag/pol, and nef, was detected in peripheral blood lymphocytes of as many as 25% of uninfected children born to HIV-1-infected mothers. The relatively high frequency of this finding in uninfected, exposed children suggests that CTL-mediated immunity may play a key role in the control or even elimination of the virus. Further characterization of this natural model of potentially protective immunity could provide new insight and suggest further strategies for the development of HIV-1 vaccines.

Zidovudine therapy of HIV-1 infection during pregnancy: assessment of the effect on the newborns

Zidovudine (ZDV) administration during pregnancy has been suggested for the prevention of mother-to-child HIV-1 transmission. Reliable levels of the drug have been observed in the fetus and in the newborn. Seven HIV-1-infected pregnant women who declined to have abortions and whose immunological status required antiretroviral treatment were administered oral ZDV 18 mg/kg in four daily doses, the initial dose being administered anytime from the 16th to the 30th week of gestation up until the time of delivery. Follow-up of the seven infants from birth with a mean duration of 22 months (range 16-32 months) revealed mild drug-related toxicity: anemia in two infants and macrocytosis in all seven, both conditions resolved by the second month of life. All infants remained HIV-1 seronegative, according to the 1987 CDC classification, and all stayed clinically well. Other virological parameters including virus culture, in vitro antibody production, and polymerase chain reaction, repeatedly performed in the infants, remained negative. Although none of the mothers transmitted HIV-1 infection to the offspring, the size of this study and the relatively low transmission rate (13%) in Europe do not permit us to draw a definite conclusion about treatment efficacy in preventing maternal-fetal transmission. However, the drug caused only limited toxicity among the infants, and its administration to large numbers of mothers in treatment trials should be considered relatively safe for both mother and child.

Repeated course of interferon treatment in chronic hepatitis B in childhood

Ten children affected by HBV chronic hepatitis, not responding to a previous treatment with interferon (IFN), have been treated with a reiterated IFN therapy. The response obtained is not encouraging and only one patient became negative for HBeAg and HBV-DNA.

Association between HLA class I antigens and response to interferon therapy in children with chronic HBV hepatitis

In this preliminary study, children with chronic HBV hepatitis, as was also previously shown for adults, respond to interferon therapy in an HLA class I antigen dependent manner. If this can be confirmed on a large scale, HLA typing may serve as a useful indication of interferon-therapy responders.

Treatment of children with chronic hepatitis B with a combination of steroids and human lymphoblastoid interferon

The efficacy of human lymphoblastoid interferon (Wellferon) therapy was measured in 20 children with chronic hepatitis B with or without pretreatment with prednisolone. Patients were randomised to receive 0.6 mg/kg/day prednisolone for 3 weeks, then at 0.3 mg/kg for a fourth week or placebo. All patients then received interferon 5 MU/m2 i.m. for 12 weeks; daily for 5 days then three times a week for the remaining 11 weeks. Preliminary results show that 25% of children had a permanent loss of viral markers of replication. However, response to interferon varied widely between individuals and a prolonged follow-up is required in order to determine the influence of prednisolone pretreatment on the efficacy of interferon therapy.

Purification to homogeneity and biochemical characterization of two suppressor factors from human malignant T-cells

A cell clone (GI-CO-T-9) derived from a long term T-cell culture (PF-382), established from a patient affected by acute T-lymphoblastic leukemia (T-ALL), was selected for the presence in the culture medium of factors suppressing T-cell proliferation. The crude supernatant has been subjected to a multi-step chromatographic fractioning, including: preparative gel permeation, anion exchange, and hydrophobic interaction High Performance Liquid Chromatography (HPLC). The highly purified material was characterized by polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS-PAGE), revealing single bands of 115 Kd and 80 Kd. The isoelectric points (pI), determined by flat-bed isoelectric-focusing, were 7.4 for High Molecular Weight Suppressor Factor (HMWSF) and 3.5-3.6 for Low Molecular Weight Suppressor Factor (LMWSF).