Coloduodenovesical Fistula After Simultaneous Pancreas-Kidney Transplant: Case Report and Review of the Literature.

BACKGROUND: Complicated diverticulitis after transplantation occurs in as many as 3.5% of cases and carries a 25% mortality rate. Diagnosis of complicated diverticulitis in this population can be challenging because of abnormal presentations caused by immunosuppression. Only 4 cases of fistulization after kidney transplantation are described in the literature; none occurred after simultaneous pancreas-kidney transplant. METHODS: We present a first case of a coloduodenovesical fistula in a patient 9 years after simultaneous pancreas-kidney transplant. The patient presented with intermittent episodes of elevated creatinine and recurrent urinary tract infection. The presence of fistula was strongly suspected in cystoscopy, but, despite extensive investigation, a fistula tract could not be identified. RESULTS: The patient ultimately underwent surgical exploration for positive cystoscopy examination, continuation of urinary complaints, and presence of multiple colonic diverticula in computed tomography scan. At surgical exploration, a fistula track was identified between the sigmoid colon and duodenal stump of the pancreas allograft. Subsequently, sigmoidectomy, bladder repair, and enteric conversion of the pancreas transplant were performed. CONCLUSIONS: Complications of diverticulitis should be considered in organ transplant recipients presenting with recurrent urinary infection and elevated creatinine, and surgical exploration might be indicated even if unable to well-define the fistula tract.

Unusual expression of human lymphocyte antigen class II in normal renal microvascular endothelium.

BACKGROUND: The human lymphocyte antigen (HLA) class II proteins (DR, DQ, and DP) and DM, a protein involved in loading antigenic peptide onto the class II molecules, have a coordinate regulation that facilitates antigen presentation to CD4+ T cells. CIITA is a specific transcription factor responsible for the coordinate regulation of these genes. DR expression in the kidney was described to be constitutive on renal microvascular endothelium in the early 1980s, but expression of other genes involved in class II antigen presentation (DQ, DP, DM, and CIITA) has not been characterized. METHODS: Expression of the HLA class II proteins, DM, and CIITA in normal human kidney cortex was evaluated by immunofluorescence microscopy, Northern blots, and reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: The endothelium of glomerular and peritubular capillaries constitutively express DR, as indicated by colocalization of DR and CD31 antibodies. However, the endothelium of larger renal blood vessels is devoid of class II proteins. Capillaries that express DR do not have detectable DQ, DP, or DM by immunofluorescence. Northern blots identified DR, DP, and DM mRNAs but not DQ mRNA. CIITA was amplified by RT-PCR at a level that could account for the class II expressed by the microvascular endothelium. CONCLUSION: The renal microvascular endothelium constitutively expresses DR without the other class II proteins or DM. This discoordinate expression of HLA class II genes is unusual and may contribute to the kidney's ability to control CD4+ T-cell responses.

Discoordinate surface expression of IFN-gamma-induced HLA class II proteins in nonprofessional antigen-presenting cells with absence of DM and class II colocalization.

We compared HLA class II expression in a human melanoma line (a nonprofessional APC), induced by IFN-gamma or by stable transfection with CIITA, with constitutive class II expression in an EBV-transformed B lymphoblastoid cell line (a professional APC) from the same donor. IFN-gamma-induced and CIITA-transfected melanoma cells expressed DR, DP, and DQ at levels similar to those expressed by the professional APC; however, DP and DQ proteins and DM-dependent DR epitopes were delayed in appearing on the cell surface when induced by IFN-gamma. The delay in cell surface expression of some IFN-gamma-induced class II epitopes was observed even though Northern blots demonstrated class II and DM genes to be coordinately transcribed and their mRNA levels to be equivalent to that in B lymphoblastoid cells. Confocal microscopy suggests that discoordinate cell surface expression of class II results from different intracellular trafficking for IFN-gamma-induced class II proteins in the melanoma line compared with that in professional APCs. Specifically, although DR and DM proteins were present 2 days after IFN-gamma induction, colocalization of DR and DM proteins intracellularly was not apparent in cells at any time after induction. Failure of DR and DM proteins to colocalize suggests that IFN-gamma-induced cells lack an intracellular MIIC-like compartment. The absence of a compartment containing DR and DM to facilitate interaction between the two proteins may account for the delayed surface expression of class II epitopes whose formation requires both class II and DM.

Novel mutants define genes required for the expression of human histocompatibility leukocyte antigen DM: evidence for loci on human chromosome 6p.

We and others have shown that the products of the HLA-DM locus are required for the intracellular assembly of major histocompatibility complex class II molecules with cognate peptides for antigen presentation. HLA-DM heterodimers mediate the dissociation of invariant chain (Ii)-derived class II-associated Ii peptides (CLIP) from class II molecules and facilitate the loading of class II molecules with antigenic peptides. Here we describe novel APC mutants with defects in the formation of class II-peptide complexes. These mutants express class II molecules which are conformationally altered, and an aberrantly high percentage of these class II molecules are associated with Ii-derived CLIP. This phenotype resembles that of DM null mutants. However, we show that the defects in two of these new mutants do not map to the DM locus. Nevertheless, our evidence suggests that the antigen processing defective phenotype in these mutants results from deficient DM expression. These mutants thus appear to define genes in which mutations have differential effects on the expression of conventional class II molecules and DM molecules. Our data are most consistent with these factors mapping to human chromosome 6p. Previous data have suggested that the expression of DM and class II genes are coordinately regulated. The results reported here suggest that DM and class II can also be differentially regulated, and that this differential regulation has significant effects on class II-restricted antigen processing.

Plasmapheresis maintained renal function in an allograft with recurrent membranoproliferative glomerulonephritis type I.

Six months posttransplant, a 38-year-old woman developed acute renal failure due to recurrent idiopathic membranoproliferative glomerulonephritis (MPGN) type I. MPGN was associated with an elevated rheumatoid factor and IgM deposition in the mesangium. Plasmapheresis with albumin replacement improved and maintained renal function for over a year while cytotoxic agents were administered in an attempt to control the glomerulonephritis. The patient currently has a functional renal allograft 2 years posttransplant.

Characterization of recombinant and endogenous ADP-ribosylation factors synthesized in Sf9 insect cells.

ADP-ribosylation factors (ARFs) are a family of highly conserved, 20-kDa guanine nucleotide-binding proteins that participate in protein trafficking and enhance cholera toxin-catalyzed ADP-ribosylation. ARF 2 from bovine retinal cDNA was expressed in Sf9 insect cells using recombinant baculovirus and compared to the major insect cell ARF (Sf9 ARF) and to recombinant ARF 2 expressed in Escherichia coli (E. coli rARF 2). The 150000g supernatant and particulate fractions of freeze-thawed, recombinant ARF 2 baculovirus-infected cells contained immunoreactive proteins of 20 and 21 kDa at significantly higher levels than were found in uninfected cells. Infected Sf9 cells incorporated [3H]myristate only into the 20-kDa protein. Sf9 cell recombinant ARF 2 (Sf9 rARF 2) and Sf9 ARF were separated by isoelectric focusing or ion-exchange chromatography and identified by microsequencing of HPLC-purified tryptic peptides. Sf9 ARF displayed considerable sequence identity to mammalian class I ARFs. Both Sf9 ARF and Sf9 rARF 2 stimulated in a GTP-dependent manner cholera toxin-catalyzed ADP-ribosylation. The Ka for GTP of Sf9 ARF was, however, significantly lower than that of Sf9 rARF 2 or E. coli rARF 2. Myristoylation did not significantly affect the ability of ARF 2 to enhance cholera toxin-catalyzed ADP-ribosylation or the Ka for GTP. Despite the sequence identities and the fact that both were synthesized in insect cells, the endogenous Sf9 ARF was functionally different from Sf9 rARF 2.

Histopathology and prognosis in childhood hepatoblastoma and hepatocarcinoma.

To determine the relationship between outcome and histologic type, the authors examined data from 168 cases of hepatoblastoma (HB) and 28 cases of hepatocarcinoma (HC) accrued from children over a 14-year period. After adjustment for stage of disease, there was no significant difference in median survival between HB and HC. Mitotic activity was associated with poor prognosis. Necrosis or vascular invasion did not influence prognosis. In 55 cases of completely resected HB, pure fetal histologic type (PFH) was associated with improved survival when compared with all other histologic patterns of HB (92% versus 57% 24 months' survival; P = 0.02). A prognostic effect of PFH was not demonstrable in incompletely resected HB, but the absence of mitoses and the presence of differentiated mesenchymal elements improved survival. The fibrolamellar pattern of HC demonstrated survival similar to that of the typical pattern of HC. The authors conclude that features consistent with differentiation in HB convey improved prognosis for survival. These observations may be important in designing future therapy for children with hepatic tumors.

Incorporation of danyslated phospholipids and dehydroergosterol into membranes using a phospholipid exchange protein.

A nonspecific phospholipid exchange protein (PLEP) preparation was used to transfer dansyl [3H]phosphatidylethanolamine (DNS-PE), dansyl[3H]phosphatidylserine (DNS-PS), and dehydroergosterol (DHE) from sonicated lipid vesicles to electroplax plasma membrane fragments enriched in Na+,K+-ATPase with retention of 80-90% of Na+,K+-ATPase activity. The transfer of individual fluorescent lipid molecules was distinguished from a nonspecific association of lipid vesicles and membranes by including [14C]triolein, a lipid that is not transferred by PLEPs, in the vesicles. Dansyl 3H-labeled phospholipids (DNS-[3H]PLs) or DHE was considered "incorporated" into the Na+,K+-ATPase membranes when fluorophores pelleted with the Na+,K+-ATPase preparation without the nonexchangeable [14C]triolein. The locations of incorporated DHE and DNS-PLs were also described by iodide quenching experiments. DHE was not accessible to iodide for quenching, while 75% of the DNS-PLs incorporated into Na+,K+-ATPase membrane fragments were accessible to iodide. After a technique was developed for using PLEP to incorporate fluorescent lipids into membranes with the Na+,K+-ATPase preparation, DNS-PE, DNS-PS, and DHE were then analogously incorporated into electroplax plasma membranes enriched in acetylcholinesterase (AChE) and into erythrocyte ghosts in order to evaluate the fluorophores as membrane probes. In the subsequent evaluation, the fluorescent properties of membrane-incorporated DNS-PE, DNS-PS, and DHE were systematically compared to the fluorescent properties of the molecules in lipid vesicles. The fluorescence polarizations of both DNS-PLs were increased by the presence of protein in a bilayer. The fluorescence polarization of DNS-PS was greater than the polarization of DNS-PE in both membranes and vesicles. In contrast, the polarization (and the lifetime) of DHE was the same whether the fluorescent sterol was in a membrane preparation or in vesicles. Fluorescence polarization and intensity of all three fluorophores were measured in the bilayer preparations as a function of temperature. The intensities of all three probes and the polarization of DNS-PE in both membranes and vesicles decreased biphasically with a change in slope occurring at 26.0-27.5 degrees C. DNS-PS in lipid vesicles was depolarized biphasically with increasing temperature, but when incorporated into membranes, DNS-PS was depolarized linearly without a change in slope. The polarization of DHE in either membranous or vesicle bilayers did not change with temperature.(ABSTRACT TRUNCATED AT 400 WORDS)