Future prospects for partially ionized solar plasmas: the prominence case.

Partially ionized plasmas (PIP) constitute an essential ingredient of our plasma universe. Historically, the physical effects associated with partial ionization were considered in astrophysical topics such as the interstellar medium, molecular clouds, accretion disks and, later on, in solar physics. PIP can be found in layers of the Sun's atmosphere as well as in solar structures embedded within it. As a consequence, the dynamical behaviour of these layers and structures is influenced by the different physical effects introduced by partial ionization. Here, rather than considering an exhaustive discussion of partially ionized effects in the different layers and structures of the solar atmosphere, we focus on solar prominences. The reason is that they represent a paradigmatic case of a partially ionized solar plasma, confined and insulated by the magnetic field, constituting an ideal environment to study the effects induced by partial ionization. We present the current knowledge about the effects of partial ionization in the global stability, mass cycle and dynamics of solar prominences. We revise the identified observational signatures of partial ionization in prominences. We conclude with prospects for PIP research in prominences, proposing the path for advancing in the prominence modelling and theory and using new and upcoming instrumentation. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'.

Picoflare jets power the solar wind emerging from a coronal hole on the Sun.

Coronal holes are areas on the Sun with open magnetic field lines. They are a source region of the solar wind, but how the wind emerges from coronal holes is not known. We observed a coronal hole using the Extreme Ultraviolet Imager on the Solar Orbiter spacecraft. We identified jets on scales of a few hundred kilometers, which last 20 to 100 seconds and reach speeds of ~100 kilometers per second. The jets are powered by magnetic reconnection and have kinetic energy in the picoflare range. They are intermittent but widespread within the observed coronal hole. We suggest that such picoflare jets could produce enough high-temperature plasma to sustain the solar wind and that the wind emerges from coronal holes as a highly intermittent outflow at small scales.

Ultra-high-resolution observations of persistent null-point reconnection in the solar corona.

Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet observations of persistent null-point reconnection in the corona at a scale of about 390 km over one hour observations of the Extreme-Ultraviolet Imager on board Solar Orbiter spacecraft. The observations show formation of a null-point configuration above a minor positive polarity embedded within a region of dominant negative polarity near a sunspot. The gentle phase of the persistent null-point reconnection is evidenced by sustained point-like high-temperature plasma (about 10 MK) near the null-point and constant outflow blobs not only along the outer spine but also along the fan surface. The blobs appear at a higher frequency than previously observed with an average velocity of about 80 km s-1 and life-times of about 40 s. The null-point reconnection also occurs explosively but only for 4 minutes, its coupling with a mini-filament eruption generates a spiral jet. These results suggest that magnetic reconnection, at previously unresolved scales, proceeds continually in a gentle and/or explosive way to persistently transfer mass and energy to the overlying corona.

Expression of µ-protocadherin is negatively regulated by the activation of the ß-catenin signaling pathway in normal and cancer colorectal enterocytes.

Mu-protocadherin (MUCDHL) is an adhesion molecule predominantly expressed by colorectal epithelial cells which is markedly downregulated upon malignant transformation. Notably, treatment of colorectal cancer (CRC) cells with mesalazine lead to increased expression of MUCDHL, and is associated with sequestration of ß-catenin on the plasma membrane and inhibition of its transcriptional activity. To better characterize the causal relationship between ß-catenin and MUCDHL expression, we performed various experiments in which CRC cell lines and normal colonic organoids were subjected to culture conditions inhibiting (FH535 treatment, transcription factor 7-like 2 siRNA inactivation, Wnt withdrawal) or stimulating (LiCl treatment) ß-catenin activity. We show here that expression of MUCDHL is negatively regulated by functional activation of the ß-catenin signaling pathway. This finding was observed in cell culture systems representing conditions of physiological stimulation and upon constitutive activation of ß-catenin in CRC. The ability of MUCDHL to sequester and inhibit ß-catenin appears to provide a positive feedback enforcing the effect of ß-catenin inhibitors rather than serving as the primary mechanism responsible for ß-catenin inhibition. Moreover, MUCDHL might have a role as biomarker in the development of CRC chemoprevention drugs endowed with ß-catenin inhibitory activity.

A novel 2,3-benzodiazepine-4-one derivative AMPA antagonist inhibits G2/M transition and induces apoptosis in human leukemia Jurkat T cell line.

It has been shown that the antagonism of glutamate receptors activity was able inhibit proliferation and induce apoptosis in several neuronal and non-neuronal cancer cell lines. In addition, it has been shown that glutamate might facilitate the spread and growth of leukemia T cells through interactions with AMPA receptors. The aim of the present study was to investigate the modulation of cell cycle elicited by a novel 2,3-benzodiazepine-4-one non-competitive AMPA antagonist derivative in the human leukemia Jurkat T cells. Our results indicated that the 1-(4-amino-3,5-dimethylphenyl)-3,5-dihydro-7,8-ethylenedioxy-4h-2,3-benzodiazepin-4-one, named 1g, exerted a significant growth inhibition of leukemia Jurkat T cells in a time and dose dependent manner, arresting the transition of G2/M phase through activation of Myt-1. The molecule also induced apoptosis through the enhanced expression of the pro-apoptotic p53, and the inhibition of Bcl-2, and Bcl-xl, followed by the activation of caspase-3. The results suggested that compound 1g might act mostly as a cytostatic rather than cytotoxic compound. Although further studies are necessary, in order to identify others specific pathways involved in the activity of the present molecule, the presented results identified a novel molecule acting on specific G2/M checkpoint regulation pathway. Finally, our data suggest that compound 1g might be a good molecule for future development in the cancer research.

Periodontal healing after 'orthodontic extraction' of mandibular third molars: a retrospective cohort study.

In this study we investigated periodontal healing of mandibular second molars following 'orthodontic extraction' of adjacent impacted third molars, under the null hypothesis that there would be no difference in probing pocket depths (PPD) and clinical attachment levels (CAL) at the distal aspect of second molars before and after treatment. A retrospective survey was conducted of 64 patients who consecutively underwent 'orthodontic extraction' of mandibular third molars in close anatomical relationship with the mandibular canal from January 1997 to January 2011. Age, smoking habit, and PPD and CAL at the distal aspect of second molars before and after treatment were recorded. A statistically significant difference was found in PPD and CAL before and after treatment for the overall sample and for the sample classified by age (>25 or ≤25 years), smoking habit (smoker or non-smoker), and type of third molar impaction (horizontal, mesioangular, or vertical). Median PPD and CAL reductions amounted to 6mm and 5mm, respectively. The null hypothesis was rejected and orthodontic extraction proved to be indicated for those impacted mandibular third molars at high risk of a postoperative periodontal defect at the distal aspect of the adjacent second molar.

Detection of specific antibodies against West Nile and Usutu viruses in healthy blood donors in northern Italy, 2010-2011.

Neutralizing antibodies against West Nile (WNV) and Usutu (USUV) viruses were measured in 6000 samples collected, between 1 September 2010 and 30 June 2011, from blood donors living in different districts of Emilia-Romagna, northeastern Italy. On the basis of the microneutralization assay (MNTA), 47 (0.78%) subjects were positive for WNV and 14 (0.23%) for USUV. These results were compared with those obtained 2 years ago and suggest an increased circulation of USUV among humans in Emilia-Romagna.

Reliability of different methods for measuring the inclination of the maxillary canines on panoramic radiographs.

OBJECTIVES: To test the reliability of 4 different methods of measuring maxillary canine inclination (CI) on panoramic radiographs, and to determine whether examiner experience level influenced these measurements under ideal experimental conditions. SETTING AND SAMPLE POPULATION: The sample consisted of 20 high-quality panoramic radiographs obtained under standardized conditions using the same radiological apparatus. MATERIAL AND METHODS: Canine inclination (CI) was measured as either the angle formed by the canine long axis and the midline (method A), a line passing through the suborbitary points (method B), the most superior points of condyles (method C) or the mesiobuccal cusp tip of the first molars (method D). Measurements were made at initial observation (T1) and after 3 months (T2) by 5 experienced orthodontists and 5 undergraduate dental students. RESULTS: Mean T1-T2 differences for the measurements were close to zero, with no relationship between their magnitude or direction for each method. Intra-rater reliability was excellent, with the lowest values being observed for method B and the highest for method C. No influence of the examiner experience level was detected. CONCLUSION: The four methods used in this study to measure CI showed excellent intra-rater and inter-rater reliability, irrespective of examiner experience level. Method B was the least reliable and method C the most reliable, if compared with the others.

Mesalazine inhibits the beta-catenin signalling pathway acting through the upregulation of mu-protocadherin gene in colo-rectal cancer cells.

BACKGROUND: Several reports indicate that mesalazine (5-aminosalicylic acid, 5-ASA) is a promising candidate for the chemoprevention of colo-rectal cancer because of its ability to reach the purpose avoiding the unwanted side effects usually associated with prolonged administration of nonsteroidal anti-inflammatory drugs. This activity of 5-ASA is probably the consequence of a number of effects determined on colo-rectal cancer cells, consisting of reduced proliferation, increased apoptosis and activation of cell cycle checkpoints and DNA repair processes. A recent observation has suggested that inhibition of beta-catenin signalling could induce these cellular effects. AIM: To characterize better the capacity of 5-ASA to inhibit the beta-catenin signalling pathway. METHODS: Genes belonging to the beta-catenin signalling pathway were analysed in colo-rectal cancer cell lines treated with 5-ASA using a combination of laboratory assays that are able to detect their phenotypic expression and functional activity. RESULTS: The results obtained indicated that 5-ASA induces the expression of a protein called mu-protocadherin that belongs to the cadherin superfamily and is able to sequester beta-catenin on the plasmatic membrane of treated cells hampering its function. CONCLUSION: These findings suggest that mu-protocadherin might be employed as a biological marker to monitor the chemopreventive efficacy of 5-ASA.

Identification of a molecular signature predictive of sensitivity to differentiation induction in acute myeloid leukemia.

Acute myeloid leukemia (AML) blasts are immature committed myeloid cells unable to spontaneously undergo terminal maturation, and characterized by heterogeneous sensitivity to natural differentiation inducers. Here, we show a molecular signature predicting the resistance or sensitivity of six myeloid cell lines to differentiation induced in vitro with retinoic acid or vitamin D. The identified signature was further validated by TaqMan assay for the prediction of response to an in vitro differentiation assay performed on 28 freshly isolated AML blast populations. The TaqMan assay successfully predicts the in vitro resistance or responsiveness of AML blasts to differentiation inducers. Furthermore, performing a meta-analysis of publicly available microarray data sets, we also show the accuracy of our prediction on known phenotypes and suggest that our signature could become useful for the identification of patients eligible for new therapeutic strategies.

Long term follow-up of mild chronic active hepatitis.

A group of 41 patients (25 males and 16 females) with mild chronic active hepatitis was studied for a mean follow-up period of 6.5 years. All patients had liver biopsy on admission and a second biopsy during the follow-up period. All but 7 patients were treated with prednisolone. Most of the patients were asymptomatic. There was no history of alcohol abuse or chronic administration of drugs. Fourteen patients were HBsAg positive and 27 HBsAg negative. Circulating autoantibodies were absent. Thirty-three patients did not demonstrate any change in disease activity. Four developed liver cirrhosis and four were apparently cured.