Sonic hedgehog expression correlates with fundic gland differentiation in the adult gastrointestinal tract

Background: Sonic hedgehog (Shh) is an important endodermal morphogenetic signal during the development of the vertebrate gut. It controls gastrointestinal patterning in general, and gastric gland formation in particular. We have previously shown that Shh regulates gastric gland proliferation in the adult but detailed analysis of its expression along the adult gastrointestinal tract has never been undertaken. We therefore studied Shh expression along the normal human and rodent adult gastrointestinal tract as well as in intestinal metaplasia of the stomach, gastric and intestinal metaplasia of the oesophagus, and gastric heterotopia in Meckel’s diverticulum.Methods: The studies were performed with in situ hybridisation and by immunohistochemistry using an antibody that recognises the Shh precursor form.Results: We found that in the normal gastrointestinal tract, high levels of Shh were expressed in the fundic glands of the stomach. Shh expression was also found in fundic gland metaplasia and heterotopia. However, Shh expression was lost in intestinal metaplasia of the stomach.Conclusion: We found a strong correlation between Shh expression and fundic gland differentiation. Our current study therefore provides evidence that in addition to its role in gastric epithelial development, Shh plays a unique role in gastric epithelial differentiation in adults.     

Murine monoclonal antibodies to DNA. A comparison of MRL/lpr NZB/W and chronically graft-versus-host-diseased mice

Hybridomas producing monoclonal antibodies to DNA were prepared from NZB/W F1 (n = 20), MRL/lpr (n = 13), mice with a chronical graft versus-host-disease (GVHD) (n = 8) and polyclonally stimulated mice (n = 9). Screening was performed by means of an anti-DNA ELISA. Reaction patterns in four different anti-DNA assays (anti-DNA ELISA, indirect immunofluorescence on Crithidia luciliae, PEG assay and Farr assay) as well as avidity and cross-reactivity of these monoclonals were studied in relation to anti-DNA (sub)class and murine origin of the clones. It was found that monoclonal anti-DNA derived from mice with chronic GVHD did not differ from monoclonal anti-DNA derived from NZB/W F1 or MRL/lpr mice, with respect to isotype distribution, avidity towards DNA, cross-reactivity and assay behaviour in the anti-DNA assays mentioned before. In contrast, monoclonal anti-DNA obtained from polyclonally stimulated mice were all of the IgM isotype and displayed a stronger cross-reactive behaviour than the other three models. Altogether, these results exclude the possibility that anti-DNA in the GVHD mice originates from the non-specific pool of natural autoantibodies and further emphasize the relevance of chronic GVHD as a murine model of systemic lupus erythematosus.     

Identification of mutations in the AIPL1, CRB1, GUCY2D, RPE65, and RPGRIP1 genes in patients with juvenile retinitis pigmentosa

Objective: To identify mutations in the AIPL1, CRB1, GUCY2D, RPE65, and RPGRIP1 genes in patients with juvenile retinitis pigmentosa. Methods: Mutation analysis was carried out in a group of 35 unrelated patients with juvenile autosomal recessive retinitis pigmentosa (ARRP), Leber''s congenital amaurosis (LCA), or juvenile isolated retinitis pigmentosa (IRP), by denaturing high performance liquid chromatography followed by direct sequencing. Results: All three groups of patients showed typical combinations of eye signs associated with retinitis pigmentosa: pale optic discs, narrow arterioles, pigmentary changes, and nystagmus. Mutations were found in 34% of patients: in CRB1 (11%), GUCY2D (11%), RPE65 (6%), and RPGRIP1 (6%). Nine mutations are reported, including a new combination of two mutations in CRB1, and new mutations in GUCY2D and RPGRIP1. The new GUCY2D mutation (c.3283delC, p.Pro1069ArgfsX37) is the first pathological sequence change reported in the intracellular C-terminal domain of GUCY2D, and did not lead to the commonly associated LCA, but to a juvenile retinitis pigmentosa phenotype. The polymorphic nature of three previously described (pathological) sequence changes in AIPL1, CRB1, and RPGRIP1 was established. Seven new polymorphic changes, useful for further association studies, were found. Conclusions: New and previously described sequence changes were detected in retinitis pigmentosa in CRB1, GUCY2D, and RPGRIP1; and in LCA patients in CRB1, GUCY2D, and RPE65. These data, combined with previous reports, suggest that LCA and juvenile ARRP are closely related and belong to a continuous spectrum of juvenile retinitis pigmentosa.     

Dose-dependent effect of angiotensin II on human erythropoietin production

Current evidence suggests that angiotensin II may be involved in the regulation of renal erythropoietin (EPO) production. The present study assessed the role of angiotensin II (A II) in different doses in the control of EPO production in humans. In a parallel, randomized, placebo-controlled open design, 60 healthy male volunteers received a 6-h intravenous infusion of: placebo (placebo, electrolyte solution), a pressor dose of A II (1-3 microg/min; A II press), a combination of a pressor dose of A II and the selective AT1-receptor blocker losartan, 50 mg (A II press + L), a subpressor dose of A II (0.0375-0.15 microg/min; A II subpress) and a combination of a subpressor dose of A II and losartan (A II subpress + L). A II press treatment resulted in a significant increase of the maximum EPO concentration (CmaxEPO, 41% higher versus placebo) and the amount of EPO produced in 24 h (AUCEPO(0-24 h), 61% larger versus placebo), A II subpress treatment increased CmaxEPO (35% higher versus placebo) and AUC(EPO)(0-24 h) (34% larger versus placebo). A II press + L and A II subpress + L treatments did not significantly increase CmaxEPO and AUCEPO(0-24 h) compared to placebo. A II affects EPO production in a dose-dependent manner. The signal seems to be mediated via AT1-receptors. A II appears to be one modulator EPO production in humans.     

IgD expression on B cells is more efficient than IgM but both receptors are functionally equivalent in up-regulation CD80/CD86 co-stimulatory molecules

The expression and function of IgM and IgD antigen receptors were studied in a series of anti-hen egg lysozyme (HEL) immunoglobulin (Ig)-transgenic mice expressing either IgM alone, IgD alone, or both IgM and IgD. B cell surface expression of IgD was found to be more efficient than that of IgM. Thus antigen receptor density on IgD⁺, IgM^? B cells was twofold higher than on IgM⁺, IgD^? B cells despite the presence of sevenfold lower levels of membrane heavy chain mRNA, and coexpression of IgD with IgM led to almost complete inhibition of surface IgM. In addition, less extensive down-regulation of IgD occurred following exposure to antigen in vitro. When regulation of CD80/CD86 co-stimulatory molecules by surface Ig was examined, up-regulation of the former was initiated at lower antigen concentrations on IgM^?, IgD⁺ compared to IgM⁺, IgD^? B cells. On correcting for antigen receptor density, however, induction of CD80/CD86 by IgM and IgD was comparable. Taken together, these results reinforced the functional similarity of IgM and IgD antigen receptors while at the same time revealing differences in expression which may explain their simultaneous presence on mature B cells.     

The phantom portion of the American College of Radiology (ACR) computed tomography (CT) accreditation program: practical tips, artifact examples, and pitfalls to avoid

The ACR CT accreditation program, begun in 2002, requires the submission of approximately 20 images, several completed data sheets and printouts of three Excel worksheets. The procedure manual is very detailed, yet participants unfamiliar with the program or having minimal CT experience have needed to redo aspects of their submission, or in some cases do not receive accreditation, due to mistakes made by the physicist. This review of the phantom portion of the ACR CT accreditation program supplements the ACR provided instructions with additional photos of phantom setup, region-of-interest (ROI), and image placement on the film sheets, and examples of completed portions of actual (but anonymous) submissions. Common mistakes, as well as uncommon but interesting images, are shown and explanations are given as to what could have been done to avoid the problem. Additionally, a review of CT dose measurement techniques and calculations will enable the physicist to better assist sites where typical exam doses are above the ACR reference values.     

Comparative analysis of the expression of the Epstein-Barr virus (EBV) anti-apoptotic gene BHRF1 in nasopharyngeal carcinoma and EBV-related lymphoid diseases

Epstein-Barr virus (EBV) has been identified in a wide range of neoplastic and non-neoplastic disorders. The EBV open reading frame BHRF1 encodes a protein with partial sequence and functional homology to the anti-apoptotic onco-protein Bcl-2 and may therefore have a role in the proliferation of EBV positive cells. We have developed a rat monoclonal antibody against pBHRF1, which can detect BHRF1 in paraffin sections. While a number of mutant versions of BHRF1 were recognised, the monoclonal did not detect the BHRF1 homologue encoded by Herpesvirus papio or two mutants with deletions in the BH2 region. This novel rat monoclonal antibody (6A9) was used to examine tissue sections from 39 cases of non-keratinising undifferentiated nasopharyngeal carcinoma (NPC), 6 cases of metastatic NPC, 7 cases of EBV-positive NPC with squamous differentiation from Chinese patients, 15 cases of EBV-positive post-transplant lymphoproliferative disorder (PTLD), 6 EBV-containing lymphoblastoid cell lines, and 2 cases of oral hairy leukoplakia (OHL). In 11 cases of undifferentiated NPC, RT-PCR data were available for comparison with the immunohistochemistry. Both cases of OHL and two cases of LCL were positive for BHRF1 but none of the PTLD showed positive staining. All cases of undifferentiated NPC were positive for Bcl-2 but only one BHRF1 positive cell was identified in 1 of 39 cases of primary undifferentiated NPC. The 6A9 antibody produced less background staining and no nuclear positivity compared with the commercially available mouse monoclonal 5B11. It is concluded that BHRF1 can not be detected by immunohistochemistry in NPC and therefore it appears not to play a significant anti-apoptotic role in the progression of this EBV-associated tumour. The 6A9 monoclonal appears to be superior to 5B11 for the detection of pBHRF1 in tissue sections.     

Comparison of the nucleotide sequences of diabetogenic and nondiabetogenic encephalomyocarditis virus

The nucleotide sequences of a diabetogenic variant of encephalomyocarditis (EMC) virus (D variant, ifp- phenotype) and a nondiabetogenic variant of EMC virus (B variant, ifp+ phenotype) have been compared. These variants differ at eight sites. The poly(C) tract of EMC-B is three bases shorter than that of EMC-D. Of the seven sites at which nucleotide substitutions were confirmed using RNA templates, four resulted in amino acid changes in three different proteins, the leader peptide, 1B (VP2), and 1D (VP1). The biological significance of these differences can now be investigated.