Severe digital arterial occlusive disease and acute parvovirus B19 infection.

We report a case of arterial occlusive disease and digital ischaemia associated with acute parvovirus B19 infection. Treatment with intravenous epoprostanol improved her symptoms.

Intrinsic photoaffinity labeling of native and recombinant rat pancreatic secretin receptors.

BACKGROUND: Structural characterization of pancreatic secretin receptors has been limited by difficulties in generating suitable radioligands and obtaining sufficient substrate. The aims of this study were to design, synthesize, and characterize high affinity radiolabeled analogues of secretin suitable for "intrinsic" photoaffinity labeling and to clone, express, and characterize the recombinant rat pancreatic secretin receptor. METHODS: The ability of synthetic analogues to stimulate amylase secretion by pancreatic acini was studied. Receptor complementary DNA (cDNA) was cloned by screening a rat pancreatic library with a probe based on the sequence of a neural cell secretin-binding protein. Competition binding and affinity labeling were performed with membranes prepared from rat pancreas and transfected cells. RESULTS: Two probes were fully efficacious secretagogues, which bound in a specific, high-affinity, rapid, and temperature-dependent manner. Only ([125I]Tyr10, pNO2-Phe22) rat secretin 27 covalently labeled a 50,000-62,000-molecular weight pancreatic membrane protein, with labeling inhibited in a concentration-dependent manner by secretin but not vasoactive intestinal polypeptide. Hybridization screening yielded a full-length cDNA identical to the neural clone. Photoaffinity labeling of this recombinant receptor identified a 57,000-62,000-molecular weight protein with specificity similar to that of native pancreas. Both native and recombinant receptors migrated at a molecular weight of 42,000 after endoglycosidase F deglycosylation. CONCLUSIONS: This study provides evidence for the molecular identity of the pancreatic secretin receptor and presents a novel probe important in structural characterization of its agonist-binding domain.

Structural relationships among the H-2 D-regions of murine MHC haplotypes.

The number of genes encoding functional Ag-presenting molecules in the D region of the murine MHC differs among haplotypes. For example, the H-2b D region contains a single "D/L" gene, H-2Db, whereas the d-haplotype encodes two, H-2Dd and Ld. Using D/L specific oligonucleotide probes, we have found that, as with H-2d, the q- and v-haplotypes contain two D/L genes, whereas the other haplotype examined have one. Hybridization analysis using cloned probes that map between H-2Dd and Ld revealed similar structures in each of the three haplotypes (d, q, and v) which have "duplicated" D regions. Two approaches were used to examine allelic relationships among the D/L genes. First, the 5' region of the H-2Db gene was sequenced, and found to be more similar to H-2Ld than to H-2Dd. Second, oligonucleotide probes that distinguish H-2Ld from H-2Dd revealed H-2Ld-related genes in several haplotypes, including the duplicated haplotypes H-2q and H-2v. Analogous probes specific for H-2Dd, however, did not detect similar sequences in the other haplotypes. We interpret these results to mean that the three duplicated D regions arose from a common duplication event, and share the five gene structure of the D region cluster defined in H-2d. However, subsequent events have generated sequence divergence at the D-locus.

Genetic analysis of the H-2D region using a new intra-D-region recombinant mouse strain.

A rare D-region recombination event which gave rise to the B10.RQDB major histocompatibility complex haplotype has been examined to ascertain the nature of the crossover and to determine which class I genes are present in the new alignment of D-region genes. Serologic analysis have shown that the B10 . RQDB major histocompatibility complex recombinant mouse inherited the H-2Dd gene from the B10.T(6R) parental line and the H-2Db gene from the B10.A(2R) parental line, representing the first example of an intra-D-region crossover resulting from an intercross. Previous molecular genetic analyses of the d and b haplotypes revealed structural diversity in the organization of their D-region gene clusters. Hence, the D region is comprised of five class I genes in the d haplotype and only one in the b haplotype. Because allelic relationships among the various D-region genes are not defined, either a homologous or nonhomologous alignment of genes has generated the RQDB crossover. Therefore, the possibility that all three D-region antigen-presenting molecules (Dd, Ld, and Db) might be encoded by the RQDB haplotype was examined. Fluorescence-activated cell sorter and cytotoxic T lymphocyte analyses revealed no detectable levels of H-2Ld cell-surface expression, confirming earlier studies with antibody-mediated cytotoxicity and immunoprecipitation. Southern blot analysis localized the recombination point to within a 1-kb region at the centromeric end of the H-2Ld gene on the B10 . T(6R) chromosome in a region of high homology to the H-2Db gene on the B10 . A(2R) chromosome. Together, these studies define the D region of the RQDB haplotype as containing the five class I genes: Dd, D2d, D3d, D4d, and Db. In addition to providing insight into rare recombination events in the D region, the B10.RQDB mouse should be a useful tool for exploring the function of D-region genes.

Renal involvement in relapsing polychondritis.

Twenty-nine of the 129 patients with RP seen at the Mayo Clinic between 1943 and 1984 had renal involvement. These patients were older, had arthritis and extrarenal vasculitis more frequently, and had a significantly worse survival rate than those without renal involvement. Renal biopsies were obtained in 11 of these 29 patients. The predominant lesions were mild mesangial expansion and cell proliferation, and segmental necrotizing glomerulonephritis with crescents. Small amounts of electron-dense deposits, predominantly mesangial, were noted on electron microscopy. Immunofluorescence revealed faint deposition of C3 and/or IgG or IgM, predominantly in the mesangium. Autopsies were obtained in 13 of the 47 patients who had died. Information regarding the renal pathology was available in 10 of these 13 autopsies. At the time of the initial evaluation at the Mayo Clinic, 6 of these 10 patients had evidence of renal involvement. At autopsy, none of these 10 patients had evidence of active renal vasculitis or segmental necrotizing glomerulonephritis, but 8 of the 10 patients exhibited variable degrees of vascular and glomerular sclerosis, segmental mesangial proliferation, tubular loss, and interstitial lymphocytic infiltrates. These observations expand the limited information available in the literature, which is based on 11 previously published case reports of renal involvement in RP. In only a few of our patients and previously reported patients were the manifestations of the disease limited to the systems characteristically involved in pure RP. The frequent coexistence of other autoimmune and connective tissue diseases supports the role of immune mechanisms in the pathogenesis of this syndrome. Deposition of immune complexes is likely to play a role in the pathogenesis of the glomerular lesions associated with RP. Administration of corticosteroids alone is sufficient to induce a complete remission in some cases, while in others the addition of a cytotoxic agent is necessary to control the activity of the disease or to spare corticosteroid side effects and maintain a remission. Immunosuppression-related infectious complications and undetected relapses after discontinuation of immunosuppressive therapy are largely responsible for the morbidity and mortality observed in these patients.