Correction: Dexamethasone Treatment Induces the Reprogramming of Pancreatic Acinar Cells to Hepatocytes and Ductal Cells.

[This corrects the article DOI: 10.1371/journal.pone.0013650.].

Hnf4α is a key gene that can generate columnar metaplasia in oesophageal epithelium.

Barrett's metaplasia is the only known morphological precursor to oesophageal adenocarcinoma and is characterized by replacement of stratified squamous epithelium by columnar epithelium. The cell of origin is uncertain and the molecular mechanisms responsible for the change in cellular phenotype are poorly understood. We therefore explored the role of two transcription factors, Cdx2 and HNF4α in the conversion using primary organ cultures. Biopsy samples from cases of human Barrett's metaplasia were analysed for the presence of CDX2 and HNF4α. A new organ culture system for adult murine oesophagus is described. Using this, Cdx2 and HNF4α were ectopically expressed by adenoviral infection. The phenotype following infection was determined by a combination of PCR, immunohistochemical and morphological analyses. We demonstrate the expression of CDX2 and HNF4α in human biopsy samples. Our oesophageal organ culture system expressed markers characteristic of the normal SSQE: p63, K14, K4 and loricrin. Ectopic expression of HNF4α, but not of Cdx2 induced expression of Tff3, villin, K8 and E-cadherin. HNF4α is sufficient to induce a columnar-like phenotype in adult mouse oesophageal epithelium and is present in the human condition. These data suggest that induction of HNF4α is a key early step in the formation of Barrett's metaplasia and are consistent with an origin of Barrett's metaplasia from the oesophageal epithelium.

Peripheral limb vascular malformations: an update of appropriate imaging and treatment options of a challenging condition.

Peripheral vascular malformations encompass a wide spectrum of lesions that can present as an incidental finding or produce potentially life- or limb-threatening complications. They can have intra-articular and intraosseous extensions that will result in more diverse symptomology and present greater therapeutic challenges. Developments in classification, imaging and interventional techniques have helped to improve outcome. The onus is now placed on appropriate detailed preliminary imaging, diagnosis and classification to direct management and exclude other more common mimics. Radiologists are thus playing an increasingly important role in the multidisciplinary teams charged with the care of these patients. By fully understanding the imaging characteristics and image-guided procedures available, radiologists will be armed with the tools to meet these responsibilities. This review highlights the recent advances made in imaging and the options available in interventional therapy.

Barrett's esophagus: cancer and molecular biology.

The following paper on the molecular biology of Barrett's esophagus (BE) includes commentaries on signaling pathways central to the development of BE including Hh, NF-κB, and IL-6/STAT3; surgical approaches for esophagectomy and classification of lesions by appropriate therapy; the debate over the merits of minimally invasive esophagectomy versus open surgery; outcomes for patients with pharyngolaryngoesophagectomy; the applications of neoadjuvant chemotherapy and chemoradiotherapy; animal models examining the surgical models of BE and esophageal adenocarcinoma; the roles of various morphogens and Cdx2 in BE; and the use of in vitro BE models for chemoprevention studies.

Dexamethasone treatment induces the reprogramming of pancreatic acinar cells to hepatocytes and ductal cells.

BACKGROUND: The pancreatic exocrine cell line AR42J-B13 can be reprogrammed to hepatocytes following treatment with dexamethasone. The question arises whether dexamethasone also has the capacity to induce ductal cells as well as hepatocytes. METHODOLOGY/PRINCIPAL FINDINGS: AR42J-B13 cells were treated with and without dexamethasone and analyzed for the expression of pancreatic exocrine, hepatocyte and ductal markers. Addition of dexamethasone inhibited pancreatic amylase expression, induced expression of the hepatocyte marker transferrin as well as markers typical of ductal cells: cytokeratin 7 and 19 and the lectin peanut agglutinin. However, the number of ductal cells was low compared to hepatocytes. The proportion of ductal cells was enhanced by culture with dexamethasone and epidermal growth factor (EGF). We established several features of the mechanism underlying the transdifferentiation of pancreatic exocrine cells to ductal cells. Using a CK19 promoter reporter, we show that a proportion of the ductal cells arise from differentiated pancreatic exocrine-like cells. We also examined whether C/EBPß (a transcription factor important in the conversion of pancreatic cells to hepatocytes) could alter the conversion from acinar cells to a ductal phenotype. Overexpression of an activated form of C/EBPß in dexamethasone/EGF-treated cells provoked the expression of hepatocyte markers and inhibited the expression of ductal markers. Conversely, ectopic expression of a dominant-negative form of C/EBPß, liver inhibitory protein, inhibited hepatocyte formation in dexamethasone-treated cultures and enhanced the ductal phenotype. CONCLUSIONS/SIGNIFICANCE: These results indicate that hepatocytes and ductal cells may be induced from pancreatic exocrine AR42J-B13 cells following treatment with dexamethasone. The conversion from pancreatic to hepatocyte or ductal cells is dependent upon the expression of C/EBPß.

The role of Cdx2 in Barrett's metaplasia.

Metaplasia (or transdifferentiation) is defined as the transformation of one tissue type to another. Clues to the molecular mechanisms that control the development of metaplasia are implied from knowledge of the transcription factors that specify tissue identity during normal embryonic development. Barrett's metaplasia describes the development of a columnar/intestinal phenotype in the squamous oesophageal epithelium and is the major risk factor for oesophageal adenocarcinoma. This particular type of cancer has a rapidly rising incidence and a dismal prognosis. The homoeotic transcription factor Cdx2 (Caudal-type homeobox 2) has been implicated as a master switch gene for intestine and therefore for Barrett's metaplasia. Normally, Cdx2 expression is restricted to the epithelium of the small and large intestine. Loss of Cdx2 function, or conditional deletion in the intestine, results in replacement of intestinal cells with a stratified squamous phenotype. In addition, Cdx2 is sufficient to provoke intestinal metaplasia in the stomach. In the present paper, we review the evidence for the role of Cdx2 in the development of Barrett's metaplasia.

Expression of Xhdsi-1VOC, a novel member of the vicinal oxygen chelate (VOC) metalloenzyme superfamily, is up-regulated in leaves and roots during desiccation in the resurrection plant Xerophyta humilis (Bak) Dur and Schinz.

The annotation of novel plant genes is frequently based on sequence and structural similarity to known protein motifs. Understanding the biological function of these genes is dependent on identifying conditions under which they are activated, however. The resurrection plant, Xerophyta humilis is a good model system for identifying and characterizing genes which are important for desiccation tolerance. Desiccation induced-1 (dsi-1(VOC)), a previously uncharacterized plant gene, is up-regulated during desiccation in leaves, roots, and seeds in X. humilis. The X. humilis desiccation induced-1 gene, Xhdsi-1(VOC), shares structural homology with the vicinal oxygen chelate (VOC) metalloenzyme superfamily. Proteins in this superfamily share little sequence similarity, but are characterized by a common betaalphabetabetabeta structural fold. A number of plant orthologues of XhDsi-1(VOC) have been identified, including Arabidopsis thaliana At1g07645, which is currently annotated as a glyoxalase I-like gene, and many ESTs derived from seed cDNA libraries. Xhdsi-1(VOC) and its orthologues do not, however, contain the glutathione and zinc binding sites conserved in glyoxalase I genes. Furthermore, expression of Xhdsi-1(VOC) in yeast failed to rescue a yeast glyoxalase I mutant. Messenger RNA transcripts for At1g07645 accumulate during seed maturation, but are not induced by water loss, salt or mannitol stress in vegetative tissue in Arabidopsis. It is concluded that dsi-1(VOC) is a seed-specific gene in desiccation-sensitive plants that is activated by water loss in vegetative tissues in the resurrection plant X. humilis and plays an important role in allowing plant tissues to survive loss of 95% of their relative water content.

MR imaging of erosions in interphalangeal joint osteoarthritis: is all osteoarthritis erosive?

OBJECTIVE: Erosive osteoarthritis is usually considered as an inflammatory subset of osteoarthritis (OA). However, an inflammatory component is now recognised in all subsets of OA, so this subgroup of erosive or inflammatory OA is more difficult to conceptualise. The aim of this study was to compare routine CR and MRI to investigate erosion numbers and morphology to determine whether hand OA in general is a more erosive disease than previously recognised. DESIGN AND METHODS: Fifteen patients with clinical (OA) of the small joints of the hand underwent MRI of one of the affected proximal interphalangeal (PIP) or distal interphalangeal (DIP) joints. Conventional radiographs (CR) of the hand were also obtained. The MR images were reviewed by two observers for the presence of central and marginal erosions. The site and morphology of any erosions was recorded. CR images of the same hand joint were scored independently for central and marginal erosions by the same observers. RESULTS: There was 100% agreement between the observers for scoring erosions on CR. Agreement for the MRI scores was also excellent (kappa = 0.84). MRI detected 37 erosions, of which only 9 were seen on CR. The increase in sensitivity using MRI was much greater for marginal erosions (1 detected on CR, 19 on MRI) than for central erosions (8 on CR, 18 on MRI). Using MRI 80% of joints examined showed 1 or more erosions compared with 40% using CR. If only marginal erosions were considered 80% of joints were still considered erosive by MRI criteria, but only 1 showed evidence of erosion on CR. Morphologically central erosions appeared to represent areas of subchondral collapse and pressure atrophy. In contrast, marginal erosions resembled those seen in inflammatory arthritides. CONCLUSION: Erosions, and particularly marginal erosions typical of those seen in inflammatory arthritis, are a more common feature of small joint OA than conventional radiographs have previously indicated.

Regulation of the lipidation of beta-secretase by statins.

Statins inhibit the dimerization of beta-secretase [BACE (beta-site amyloid precursor protein-cleaving enzyme)] by inhibiting the lipidation of BACE and associated proteins. Our studies have demonstrated a clearly defined temporal sequence for these reactions in the assembly of the BACE complex, which may provide targets for the treatment of Alzheimer's disease.

Advanced imaging in rheumatoid arthritis: part 2: erosions.

Rheumatoid arthritis (RA) is a chronic and progressive inflammatory disorder primarily affecting the synovium. We now recognise that conventional radiographic images show changes of rheumatoid arthritis late after irreversible joint damage has occured. With the advent of powerful disease-modifying drugs there is a need for early demonstration of rheumatoid arthritis and to monitor progress of the disease and response to therapy. Advanced imaging techniques such as ultrasound and MRI have focussed on the demonstration and quantification of synovitis and erosions and allow early diagnosis of RA. The technology to quantify synovitis and erosions is developing rapidly and now allows change in disease activity to be assessed. However, problems undoubtedly exist in quantification techniques and this review serves to highlight them. Much of the literature on advanced imaging in RA appears in rheumatological journals and may not be familiar to radiologists. This review article aims to increase the awareness of radiologists to this field and to encourage them to participate and contribute to the ongoing development of these modalities. Without this collaboration it is unlikely that these modalities will reach their full potential in the field of rheumatological imaging. This review is in two parts. This first part addresses synovitis imaging. The second part will look at advanced imaging of erosions in RA.

Advanced imaging in rheumatoid arthritis. Part 1: synovitis.

Rheumatoid arthritis (RA) is a chronic and progressive inflammatory disorder primarily affecting the synovium. We now recognise that conventional radiographic images show changes of rheumatoid arthritis long after irreversible joint damage has occured. With the advent of powerful disease-modifying drugs, there is a need for early demonstration of rheumatoid arthritis and a need to monitor progress of the disease and response to therapy. Advanced imaging techniques such as ultrasound and MRI have focussed on the demonstration and quantification of synovitis and erosions and allow early diagnosis of RA. The technology to quantify synovitis and erosions is developing rapidly and now allows change in disease activity to be assessed. However, problems undoubtedly exist in quantification techniques, and this review serves to highlight them. Much of the literature on advanced imaging in RA appears in rheumatological journals and may not be familiar to radiologists. This review article aims to increase the awareness of radiologists about this field and to encourage them to participate and contribute to the ongoing development of these modalities. Without this collaboration, it is unlikely that these modalities will reach their full potential in the field of rheumatological imaging. This review is in two parts. The first part addresses synovitis imaging. The second part will look at advanced imaging of erosions in RA.

Drought tolerance of selected Eragrostis species correlates with leaf tensile properties.

BACKGROUND AND AIMS: Previous studies on grass leaf tensile properties (behaviour during mechanical stress) have focused on agricultural applications such as resistance to trampling and palatability; no investigations have directly addressed mechanical properties during water stress, and hence these are the subject of this study. METHODS: Critical (lethal) relative water contents were determined for three species of grass in the genus Eragrostis varying in their tolerance to drought. Measurements were taken for leaf tensile strength, elastic modulus, toughness and failure load under different conditions of hydration, and light microscopy and histochemical analyses were undertaken. KEY RESULTS: Leaf tensile strength of fully hydrated leaves for the drought-intolerant E. capensis, the moderately drought-tolerant E. tef and the drought-tolerant E. curvula correlated well with drought tolerance (critical relative water content). Eragrostis curvula had higher tensile strength values than E. tef, which in turn had higher values than E. capensis. Measurements on the drought-tolerant grass E. curvula when fully hydrated and when dried to below its turgor loss point showed that tensile strength, toughness and the elastic modulus all increased under conditions of turgor loss, while the failure load remained unchanged. Additional tests of 100 mm segments along the lamina of E. curvula showed that tensile strength, toughness and the elastic modulus all decreased with distance from the base of the lamina, while again the failure load was unaffected. This decrease in mechanical parameters correlated with a reduction in the size of the vascular bundles and the amount of lignification, as viewed in lamina cross-sections. CONCLUSIONS: The results confirm that leaf mechanical properties are affected by both water status and position along the lamina, and suggest a positive correlation between leaf internal architecture, tensile strength, cell wall chemistry and tolerance to dehydration for grasses.

Renovascular hypertension. Radiographic methods.

In recent years the choice of radiographic methods available in the investigation of renovascular hypertension has increased significantly. It can be difficult for the clinician to decide which patients will benefit from screening and which modality to choose. This article seeks to address some of these issues. The role of the plain radiograph and intravenous urogram are briefly mentioned. Doppler ultrasound, MR, CT and conventional arteriography are discussed in detail. Their advantages and pitfalls are reviewed. In our institution ultrasound to document renal size and gadolinium-enhanced 3-D MRA are our recommended first-line investigations unless MRA is contraindicated. Digital subtraction arteriography is reserved for the small subgroup in which MRA fails to obtain an answer, for whatever reason.

Characterisation and genetic organisation of a 24-MDa plasmid from the Brazilian Purpuric Fever clone of Haemophilus influenzae biogroup aegyptius.

Strains of Haemophilus influenzae biogroup aegyptius causing septicaemia were identified in Brazil in the 1980s, causing the life-threatening illness of Brazilian Purpuric Fever (BPF). The strains were found to fall into a single clonal group, the BPF clone, characterised by their possession of the approximately 24MDa "3031" plasmid. In this work we report the characterisation and genetic organisation of this plasmid. Analysis of the gene content of what appears to be a typical broad host range conjugative plasmid, its presence in non-BPF strains as revealed by Southern hybridisation, and the recent discovery of plasmid-lacking BPF strains, has led us to conclude that it is unlikely to play a critical role in bacterial virulence. Establishing its entire sequence has nonetheless been an important step on the road to delineating, by comparison of BPF and non-BPF strains, chromosomal genetic loci that are involved in the special virulence of the BPF clone.

Changes in leaf hexokinase activity and metabolite levels in response to drying in the desiccation-tolerant species Sporobolus stapfianus and Xerophyta viscosa.

The phosphorylation of glucose and fructose is an important step in regulating the supply of hexose sugars for biosynthesis and metabolism. Changes in leaf hexokinase (EC 2.7.1.1) activity and in vivo metabolite levels were examined during drying in desiccation-tolerant Sporobolus stapfianus and Xerophyta viscosa. Leaf hexokinase activity was significantly induced from 85% to 29% relative water content (RWC) in S. stapfianus and from 89% to 55% RWC in X. viscosa. The increase in hexokinase corresponded to the region of sucrose accumulation in both species, with the highest activity levels coinciding with region of net glucose and fructose removal. The decline of hexose sugars and accumulation of sucrose in both plant species was not associated with a decline in acid and neutral invertase. The increase in hexokinase activity may be important to ensure that the phosphorylation and incorporation of glucose and fructose into metabolism exceeded production from potential hydrolytic activity. Total cellular glucose-6-phosphate (Glc-6-P) and fructose-6-phosphate (Fru-6-P) levels were held constant throughout dehydration. In contrast to hexokinase, fructokinase activity was unchanged during dehydration. Hexokinase activity was not fully induced in leaves of S. stapfianus dried detached from the plant, suggesting that the increase in hexokinase may be associated with the acquisition of desiccation-tolerance.

An aldose reductase homolog from the resurrection plant Xerophyta viscosa Baker.

An aldose reductase homologue (ALDRXV4) was cloned from the resurrection plant Xerophyta viscosa Baker using complementation by functional sufficiency in Escherichia coli. A cDNA library constructed from X. viscosa leaves dehydrated to 85%, 37% and 5% relative water contents (RWC) was converted into an infective phagemid library. Escherichia coli (sr1::Tn10) cells transformed with ds-pBluescript phagemids were selected on minimal medium plates supplemented with 1 mM isopropyl beta-D-thiogalactopyranoside and 1.25 M sorbitol. Nine cDNA clones that conferred tolerance to the osmotically stressed E. coli cells were selected. The phagemid from one clone contained the ALDRXV4 insert. The E. coli cells expressing ALDRXV4 were capable of tolerating the osmotic stress, whereas control cultures were not. The ALDRXV4 insert contained an open reading frame that can code for 319 amino acids, and the predicted protein had a calculated Mr of 35,667. Amino acid sequence comparisons revealed significant similarity to several aldose reductases, with the highest similarity to aldose reductase proteins from Hordeum vulgare, Bromus inermis and Avena fatua, in the order of 66%, 65% and 65% respectively. Northern blot analysis revealed that ALDRXV4 was expressed only under dehydration conditions in X. viscosa leaves. Western blot analysis detected a protein of 36 kDa under dehydration conditions only. Aldose reductase activity levels in X. viscosa leaves increased as the leaf RWC decreased, whereas there was no significant change in aldose reductase activity in Sporobolus stafianus as the leaf RWC decreased.

Deficiency in circulating natural killer (NK) cell subsets in common variable immunodeficiency and X-linked agammaglobulinaemia.

Absolute and relative NK cell numbers were determined in peripheral whole blood by flow cytometry in patients with common variable immunodeficiency (CVID) (n = 55) and X-linked agammaglobulinaemia (XLA) (n = 19) on regular immunoglobulin (IVIG) therapy. Absolute CD3-CD16+ NK cell numbers were significantly reduced in CVID patients (median 108/microl, range 23-815), compared with normal subjects (n = 60) (289/microl, range 56-640, P < 0.001). Total lymphocyte concentrations were significantly lower in CVID (median 1587/microl, range 523-7519) compared with normal subjects (median 2019/microl, range 1124-3149, P = 0.004), with the percentage of NK cells also being significantly decreased (median 7.5%, range 3.0-33. 0%, compared with 14.2%, range 2.6-30.8%, P < 0.001). In XLA, absolute NK cell numbers (median 140/microl, range 32-551, P < 0. 001) but not relative numbers were significantly reduced compared with normal controls. We excluded the possibility that IVIG interferes with in vitro binding of CD16 MoAbs. Further analysis of NK cell subsets showed a deficiency of both CD16+ and CD56+ cells in CVID, most marked in the CD3-CD8dim subpopulation, which may be due to increased homing of these cells to the gut. Serial studies on a small number of patients suggest that IVIG therapy has no short-term effect on NK cells, although we cannot exclude an effect with prolonged use. Although there are no obvious clinical effects of the NK depletion in CVID and XLA, this may be a factor in their predisposition to cancer.

Up-regulation of IL-12 in monocytes: a fundamental defect in common variable immunodeficiency.

We show that LPS-stimulated circulating CD14-positive monocytes from patients with common variable immunodeficiency (CVID) express a higher proportion of intracellular IL-12-positive cells than monocytes from patients with X-linked agammaglobulinemia or normal subjects. We used four-color flow cytometry and measured IL-12 with an Ab to the p40 subunit following stimulation with LPS. The raised IL-12 is associated with an increased frequency of IFN-gamma-positive T cells, but not of IFN-gamma-positive CD56+ NK cells. These increases in frequency of cytokine-positive cells are due to a decrease in the absolute numbers of circulating monocytes and T cells that are negative for IL-12 and IFN-gamma, respectively. The increased frequency of IL-12-positive monocytes appears to be selective because TNF-alpha was not increased, and is thus unlikely to reflect a general activation. Chronic infection is also unlikely to explain our data since cells from X-linked agammaglobulinemia patients with a similar Ig deficiency do not show these changes. Our data suggest a fundamental abnormality in the IL-12/IFN-gamma circuit in CVID, with up-regulation of IL-12 being the "primary" factor. This imbalance is likely to skew the immune response away from Ab production and also explains the failure of CVID T cells to make Ag-specific memory cells and the chronic inflammatory and granulomatous complications that are a feature of CVID. This disease appears to be a rare example of a polarized Th1-type response and may in part be due to a genetic defect in the control of IL-12 production.