Search

The homeobox gene Pdx1 is a key regulator of pancreas and foregut development. Loss of Pdx1 expression results in pancreas agenesis and impaired development of the gastro-duodenal domain including Brunner’s glands. We previously demonstrated a key role for Pdx1 in maintaining the integrity and function of insulin-secreting beta cells in the adult pancreas. In the present study, we aimed to determine if expression of Pdx1 is required to maintain the cellular identity of the gastro-duodenal domain in adult mice. Immunohistological studies were performed in a mouse model in which expression of Pdx1 was conditionally repressed with the doxycycline-responsive tetracycline transactivator system. Mice in which Pdx1 was chronically repressed developed hamartomas in the gastro-duodenal domain. These lesions appeared to arise from ectopic foci of anteriorized cells, consistent with a localised anterior homeotic shift. They emerge with the intercalation of tissue between the anteriorized and normal domains and appear strikingly similar to lesions in the colon of mice heterozygous for another Parahox gene, Cdx2. Continuing expression of Pdx1 into adult life is required to maintain regional cellular identity in the adult foregut, specifically at the gastro-duodenal boundary. Loss of Pdx1 expression leads to anterior transformation and intercalary regeneration of ectopic tissue. We propose a model in which the posterior dominance of classical Hox genes is mirrored by the Parahox genes, providing further evidence of the functional conservation of the Parahox genes. These findings may have implications for further understanding the molecular basis of gastro-duodenal metaplasia and gastro-intestinal transformations such as Barrett’s esophagus.

Pancreas stem cells are a potential source of insulin-producing β cells for the therapy of diabetes. In adult tissues the 'side population' (SP) of cells that effluxes the DNA binding dye Hoechst 33342 through ATP-binding cassette transporters has stem cell properties. We hypothesised therefore that the SP would expand in response to β cell injury and give rise to functional β cells. SP cells were flow sorted from dissociated pancreas cells of adult mice, analysed for phenotype and cultured with growth promoting and differentiation factors before analysis for hormone expression and glucose-stimulated insulin secretion. SP cell number and colony forming potential (CFP) increased significantly in models of type diabetes, and after partial pancreatectomy, in the absence of hyperglycaemia. SP cells, ∼1% of total pancreas cells at 1 week of age, were enriched >10-fold for CFP compared to non-SP cells. Freshly isolated SP cells contained no insulin protein or RNA but expressed the homeobox transcription factor Pdx1 required for pancreas development and β cell function. Pdx1, along with surface expression of CD326 (Ep-Cam), was a marker of the colony forming and proliferation potential of SP cells. In serum-free medium with defined factors, SP cells proliferated and differentiated into islet hormone-expressing cells that secreted insulin in response to glucose. Insulin expression was maintained when tissue was transplanted within vascularised chambers into diabetic mice. SP cells in the adult pancreas expand in response to β cell injury and are a source of β cell progenitors with potential for the treatment of diabetes.

Detection of human Ag-specific T cells is limited by sensitivity and blood requirements. As dendritic cells (DCs) can potently stimulate T cells, we hypothesized that their induction in PBMCs in situ could link Ag processing and presentation to Ag-specific T-cell activation. To this end, unfractionated PBMCs (fresh or frozen) or whole blood were incubated for 48 hours with protein or peptide Ag together with different DC-activating agents to rapidly and sequentially induce, pulse, and mature DCs. DC activation was therefore lined up with Ag recognition by neighboring T cells, thus telescoping the sequential steps of T-cell activation. Efficient processing of protein Ags made prior knowledge of epitopes and HLA restrictions dispensable. While reducing stimulation time, manipulation and blood requirements, in situ DC induction specifically amplified Ag-specific T-cell responses (cytokine secretion, proliferation, CD137/CD154 up-regulation, and binding of peptide-HLA multimers). IL-1β, although released by DCs, was also secreted in an Ag-specific fashion, thus providing an indirect biomarker of T-cell responses. These accelerated cocultured DC (acDC) assays offered a sensitive means with which to evaluate T-cell responses to viral and melanoma Ag vaccination, and may therefore find application for immune monitoring in viral, tumor, autoimmune, and transplantation settings.

Steroid hormones induce changes in gene expression by binding to intracellular receptors that then translocate to the nucleus. Steroids have also been shown to rapidly modify cell function by binding to surface membrane receptors. We identified a candidate steroid membrane receptor, the progestin and adipoQ receptor (PAQR) 10, a member of the PAQR family, in a screen for genes differentially expressed in mouse pancreatic beta-cells. PAQR10 gene expression was tissue restricted compared with other PAQRs. In the mouse embryonic pancreas, PAQR10 expression mirrored development of the endocrine lineage, with PAQR10 protein expression confined to endocrine islet-duct structures in the late embryo and neonate. In the adult mouse pancreas, PAQR10 was expressed exclusively in islet cells except for its reappearance in ducts of maternal islets during pregnancy. PAQR10 has a predicted molecular mass of 29 kDa, comprises seven transmembrane domains, and, like other PAQRs, is predicted to have an intracellular N-terminus and an extracellular C-terminus. In silico analysis indicated that three members of the PAQR family, PAQRs 9, 10, and 11, have a candidate mitochondrial localization signal (MLS) at the N-terminus. We showed that PAQR10 has a functional N-terminal MLS and that the native protein localizes to mitochondria. PAQR10 is structurally related to some bacterial hemolysins, pore-forming virulence factors that target mitochondria and regulate apoptosis. We propose that PAQR10 may act at the level of the mitochondrion to regulate pancreatic endocrine cell development/survival.

Increased plasma levels of several acute phase proteins, such as C-reactive protein (CRP), have been documented among different patients with chronic renal failure (CRF). The aim of the present study was to determine whether pentraxin-3 (PTX3) is a reliable marker of inflammation in CRF. Plasma samples and monocytes were taken from 43 patients before and after undergoing haemodialysis (HD), from 45 uraemic patients (UR) without HD treatment and from 25 healthy controls. Plasma and monocyte samples were analyzed by ELISA for levels of PTX3, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6); all of these protein levels were higher in CRF patients with respect to the controls. After HD, plasma PTX3 and cytokine levels increased. Inter- and intra-individual variations in CRP were observed in HD patients, while PTX3 plasma levels were stable. Release of PTX3, TNF-alpha, IL-1beta and IL-6 by unstimulated monocytes from patients, before and after HD, was higher with respect to UR patients and controls. After lipopolysaccharide stimulation, all values were higher in patients before HD than those in UR patients, but lower when compared to those in the controls. In contrast, no changes were observed after HD. A significant correlation among plasma PTX3 versus fibrinogen, TNF-alpha and IL-1beta was observed in HD and UR patients. Collectively, these data suggest that PTX3 protein may represent an additional and stable marker of inflammation in CRF.

The homeodomain transcription factor Pdx1 is essential for pancreas development. To investigate the role of Pdx1 in the adult pancreas, we employed a mouse model in which transcription of Pdx1 could be reversibly repressed by administration of doxycycline. Repression of Pdx1 in adult mice impaired expression of insulin and glucagon, leading to diabetes within 14 days. Pdx1 repression was associated with increased cell proliferation predominantly in the exocrine pancreas and upregulation of genes implicated in pancreas regeneration. Following withdrawal of doxycycline and derepression of Pdx1, normoglycemia was restored within 28 days; during this period, Pdx1(+)/Ins(+) and Pdx(+)/Ins(-) cells were observed in association with the duct epithelia. These findings confirm that Pdx1 is required for beta-cell function in the adult pancreas and indicate that in the absence of Pdx1 expression, a regenerative program is initiated with the potential for Pdx1-dependent beta-cell neogenesis.

Mutations in the triple PDZ domain-containing protein harmonin have been identified as the cause of Usher deafness syndrome type 1C. Independently, we identified harmonin in a screen for genes expressed in pancreatic beta cells. Using a yeast two-hybrid assay, we show that the first PDZ domain of harmonin interacts with a novel protein, designated harp for harmonin-interacting, ankyrin repeat-containing protein. This interaction was confirmed in an over-expression system and in mammalian cells, and shown to be mediated by the three C-terminal amino acids of harp. Harp is expressed in many of the same epithelia as harmonin and co-localization of native harp and harmonin was demonstrated by confocal microscopy in pancreatic duct epithelium and in a pancreatic beta-cell line. Harp, predicted molecular mass 48 kDa, has a domain structure which includes three ankyrin repeats and a sterile alpha motif. Human harp maps to chromosome 16, and its mouse homologue to chromosome 7. Sequences with similarity to harp include the sans gene, mutations of which are responsible for deafness in the Jackson shaker 2 (js) mutant mouse and in human Usher syndrome type 1G. The functional domain structures of harp and harmonin, their interaction under native conditions and their co-localization suggest they constitute a scaffolding complex to facilitate signal transduction in epithelia.

Tissue function is regulated by the extracellular microenvironment including cell basement membranes, in which laminins are a major component. Previously, we found that laminin-1 promotes differentiation and survival of pancreatic islet cells. Here we characterize the expression pattern of laminins and their integrin receptors in adult pancreas. Although they are expressed in the basement membrane of acinar cells and duct epithelium, no laminin chains examined were detected extracellularly in the pancreatic islets. In contrast to laminin beta(1)- and gamma(1)-chains, the alpha(1)-chain, unique to laminin-1, was not detected. Laminin-10 (alpha(5)beta(1)gamma(1)) was expressed in acinar tissue, whereas laminins-2 (alpha(2)beta(1)gamma(1)) and -10 were expressed in the blood vessels. The laminin connector molecule, nidogen-1, had a distribution similar to that of laminin beta(1) and gamma(1), whereas fibulin-1 and -2, which compete with nidogen-1, were mostly confined to blood vessels. Integrin subunits alpha(6) and alpha(3) were detected in acinar cells and duct epithelial cells, but alpha(6) was absent in islet cells. Integrin alpha(6)beta(4) was detected only in duct cells, alpha(6)beta(1) in both acinar and ductal cells, and alpha(3)beta(1) in acinar, duct, and islet cells. These findings are a basis for further investigation of the role of extracellular matrix molecules and their receptors in pancreas function.

Cytokine receptors from the IL-6 receptor family are comprised of ligand specific alpha chains and a common signalling chain, gp-130, which is also required for high affinity binding. A cDNA library generated from the beta-TC3 SV40 T-antigen transformed insulinoma cell line was screened for members of this receptor family potentially relevant to both beta cell development and autoimmunity. Degenerate oligonucleotide primers to a consensus region of these receptors were used and the IL-11 receptor alpha chain was identified. Despite confirmation of IL-11 receptor mRNA expression, iodinated bioactive IL-11 did not bind specifically to beta-TC3 cells and gp-130-dependent cytokines did not elicit signalling events in beta cell lines. This was explained by absence of gp-130 protein or mRNA in the beta cell lines tested and in primary islets. We conclude from these results that the previously recognised effects of IL-6 family member cytokines on pancreatic islets must be indirect via other non-beta cells within the islet, rather than due to direct effects on beta cells themselves.

We have cloned a member of the STE20/SPS1 protein kinase family from a transformed rat pancreatic beta cell line. SPAK (STE20/SPS1-related, proline alanine-rich kinase) belongs to the SPS1 subfamily of STE20 kinases and is highly conserved between species. SPAK is expressed ubiquitously, although preferentially in brain and pancreas. Biochemical characterization of SPAK catalytic activity demonstrates that is a serine/threonine kinase that can phosphorylate itself and an exogenous substrate in vitro. SPAK is immunoprecipitated from transfected mammalian cells as a complex with another, as yet uncharacterized, serine/threonine kinase which is capable of phosphorylating catalytically-inactive SPAK and myelin basic protein in an in vitro kinase assay. SPAK specifically activates the p38 pathway in cotransfection assays. Like MST1 and MST2, SPAK contains a putative caspase cleavage site at the junction of the catalytic domain and the C-terminal region. Full-length SPAK is expressed in the cytoplasm in transfected cells, while a mutant corresponding to caspase-cleaved SPAK is expressed predominantly in the nucleus. The similarity of SPAK to other SPS1 family members, its ability to activate the p38 pathway, in addition to its putative caspase cleavage site, provide evidence that SPAK may act as a novel mediator of stress-activated signals. Oncogene (2000) 19, 4290 - 4297

Purpose: To report the use of an aortic endograft to treat a ruptured false aneurysm at the anastomosis of an aortofemoral bypass graft., Methods and Results: A 68-year-old man with a 30-year-old aorto-right femoral bypass and multiple comorbidities was admitted to the hospital complaining of acute abdominal pain. Imaging identified a 60-mm ruptured aortic false aneurysm with associated retroperitoneal hematoma, a 9-cm right femoral false aneurysm, and a calcified 23-mm left common iliac aneurysm. Two slightly overlapping Vanguard straight stent-grafts were implanted in the aorta and left common iliac artery in an emergency procedure owing to the patient's high surgical risk. The anastomotic false aneurysm and the bypass were excluded. A left-to-right femorofemoral bypass was performed to re-establish flow to the right femoral artery with ligation of the external iliac artery. The patient recovered uneventfully. He remained well with a successful repair until his death of a myocardial infarction 6 months after the procedure., Conclusions: Endovascular grafting can be used successfully for the urgent treatment of aortic false aneurysm rupture.

To obtain a better understanding of the immune response to Epstein-Barr virus (EBV), we measured the cytokines tumour necrosis factor (TNF)-alpha/beta, interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the conditioned medium of peripheral blood mononuclear cells from 10 healthy adults before and at 48 h and at 1, 2, 3 and 4 weeks following infection in vitro with EBV. Cultures were examined for regression of outgrowths of nascent virus-transformed B cells, and populations of cells in the cultures were analysed by flow cytometry. TNF-alpha/beta was not detected in infected or non-infected cultures. In infected cultures assayed at the nominated times, the highest levels of IL-2 were detected at 48 hours, IFN-gamma at 1 week, IL-6 at 2 weeks and GM-CSF between 2 and 4 weeks. IL-6 and GM-CSF, but not IL-2 or IFN-gamma, were detected in non-infected cultures but at lower levels than in infected cultures. Nine of the 10 healthy adults showed regression of outgrowths of virus-transformed B cells and, of these, seven had antibodies to the EBV capsid antigen (VCA). Strong regression was associated with sequential increases in IL-2, IFN-gamma, and low levels of IL-6 and GM-CSF. Absent or weak regression was associated with an undetectable level of IL-2, a low level of IFN-gamma, high levels of IL-6 and GM-CSF and an increased frequency of cells bearing the phenotype CD20 and HLA-DR in the final weeks of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Between May 1978 and March 1990, 700 patients were operated on with direct coronary surgery without extracorporeal circulation (ECC): 529 (76 percent) were male and 171 (24 percent) were female. The average age was 64 years (range, 35 to 86 years), 454 (65 percent) had unstable angina, 163 (23 percent) had stable angina, 51 (7 percent) had postmyocardial infarction angina, and 32 (5 percent) had acute myocardial infarction at the moment of the operation. In this series of patients, all branches of the coronary arteries were bypassed; the mammary artery was used in 40 percent of the cases, the average bypass per patient was 2.2 (range, 1 to 5), and 26 percent had associated disease of high risk to undergo ECC. The morbidity was 4 percent and the mortality for this series of patients was 1 percent; the probability of survival at seven years was 90 percent. This experience shows us that this surgery is an alternative in the treatment of coronary disease, especially for aged patients with associated disease, in some cases of acute transmural infarction, and also for patients who need coronary angioplasty. Also, it can improve the relation cost/benefit in coronary surgery.

We describe a new surgical technique for the treatment of fibrosed interventricular septum, with or without left ventricular aneurysm. It is designed for patients whose ventriculograms revealed important septal dysfunction. Eleven patients ranging from 37 to 66 years of age were operated upon between 1984 and 1988. The left ventricle was opened through the aneurysm or the anterior wall when only anterior septal fibrosis was present. In patients with large aneurysms, two purse-string sutures were placed on the inside surface of the intact ventricle, around its limits, for approximation. The fibrosed septum was thus excluded from the new ventricular cavity. A patch was placed between the fibrosed and the healthy septum, reaching to the ventricular wall, all around the transitional edge. Both, ventricular geometry and function were improved. All patients were asymptomatic after one year follow-up.

Sera from 120 patients with suspected autoimmune rheumatic disease and antinuclear antibodies of anti-SS-B/La specificity were examined by Western blotting for reactivity with the SS-B/La polypeptide of HeLa cells and recombinant SS-B/La derived from a 1.4 kilobase (kb) cDNA encoding approximately 90% of the SS-B/La molecule. All sera reacted with the HeLa cell and the recombinant SS-B/La. One hundred and fourteen (95%) reacted with a set of three Staph. aureus V8 protease-resistant peptides of Mr 30,000, 29,00 and 28,000 from a methionine-rich region of HeLa cell SS-B/La designated the X domain, and 98 (82%) reacted with another set of two protease-resistant peptides of Mr 24,000 and 23,000 from a phosphorylated region of HeLa cell La designated the Y domain. One reacted weakly with the Y domain only. All sera that reacted with X and Y reacted more strongly with X, suggesting that X was the major epitope. Antibodies affinity purified from the X domain reacted strongly with the X peptides but not with the Y peptides and conversely, antibodies affinity purified from the Y domain reacted with the Y peptides but not with the X peptides. Both antibodies reacted with a fusion protein comprising 102 amino acids at the carboxyl terminus of the SS-B/La molecule. This protein contained no methionine, demonstrating that methionines were not involved in the antibody-binding site. Over 80% of patients whose only criteria for selection was the presence of anti-SS-B/La had the clinical, histologic, serologic and phenotypic features of Sjögren's syndrome whilst the remaining 20% had at least two of the features.(ABSTRACT TRUNCATED AT 250 WORDS)

Human recombinant La nucleoprotein was purified from cultures of Escherichia coli containing a vector with a 1.4 kilobase cDNA encoding La; the nucleoprotein was used to test for antinuclear antibodies (ANA) to La. Serum samples from 260 patients with autoimmune diseases associated with ANA and 100 healthy subjects were tested by an enzyme-linked immunosorbent assay (ELISA). Samples from 47 (94%) of 50 patients with primary Sjögren's syndrome and 1 (7%) of 14 patients with secondary Sjögren's syndrome reacted with the recombinant La. No reactivity was demonstrated in 196 patients with other ANA-associated autoimmune diseases or in 100 healthy subjects. The study confirms the high correlation between ANA, anti-La, and primary Sjögren's syndrome and shows how gene cloning can provide large quantities of human autoantigens for use in highly specific and sensitive diagnostic assays.

Tests for anticardiolipin antibodies (ACL) on sera from 100 male homosexuals and 60 male heterosexuals showed that 57% of the homosexuals, in contrast to none of the heterosexuals, were ACL positive. The ACL were predominantly of the immunoglobulin G isotype and, in a high proportion of cases tested (82%), were reactive with other phospholipids, especially those with a negative charge. ACL were not related to the clinical status of the homosexuals, being evenly distributed among 40 with acquired immunodeficiency syndrome (AIDS), 20 with AIDS-related complex (ARC), 20 with asymptomatic infection with human immunodeficiency virus (HIV) and/or lymphadenopathy syndrome, and 20 who were HIV-antibody negative. Nor were they associated with thrombocytopenia, thrombosis, neurologic disease, a biological false-positive test for syphilis (BFP), or antibodies to DNA. It is concluded that factors other than infection with HIV are responsible for ACL positivity in homosexual males and that the epitopes recognized by ACL in this group are distinct from those associated with thromboembolism or the BFP reaction or cross-reactive with DNA.