Small bowel intussusception and concurrent jejunal polyp with neoplastic transformation: a new diagnosis of Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is a rare hereditary disease characterised by hyperpigmentation of the oral mucosa and gastrointestinal hamartomatous polyps. We report a case of a 27-year-old man who presented with a 5-day history of epigastric pain and rectal bleeding. Computed tomography suggested small bowel obstruction secondary to ileocolic intussusception and an incidental polyp in the mid jejunum. The patient underwent exploratory laparotomy during which right hemicolectomy and small bowel resection were performed. Histology from surgical specimens revealed Peutz-Jeghers polyps, one of which had low-grade dysplasia. This case emphasises that although rare, adults with PJS can present with intussusception. Also illustrated is the extremely rare possibility of concurrent polyps occurring in different parts of the bowel with neoplastic transformation. Intussusception is a challenge to diagnose because the presentation is often non-specific. Clinical history-taking and physical examination along with prompt axial imaging is important for the diagnosis. Careful examination of the bowel and polypectomy during laparotomy may prevent neoplastic transformation and short bowel syndrome.

Prospective study of urine cytology screening for BK polyoma virus replication in renal transplant recipients

OBJECTIVE

BK virus (BKV) may be associated with interstitial nephritis in renal transplant recipients and this can lead to irreversible chronic allograft dysfunction. Early diagnosis of BKV nephropathy determines its progress because no specific antiviral therapy exists. Urine cytology, detection of viral DNA in urine or blood and renal biopsy are the main diagnostic tools. The purpose of this study was to evaluate the use of urine cytology for diagnosis of BKV replication in renal graft recipients.

PATIENTS AND METHODS

We studied 32 de novo renal transplant recipients prospectively with sequential urine samples for a period of 1 year. Thin-Prep methodology was used to prepare the slides. Cytology results were correlated with polymerase chain reaction (PCR) in urine and blood.

RESULTS

Decoy cells indicative of BKV infection were detected in 14 (7.3%) of the 190 urine samples derived from 11 recipients. In three cases with positive decoy cells, BK viraemia and viruria were simultaneously identified. In a further three cases, BKV active replication was confirmed in urine by both cytology and PCR.

CONCLUSIONS

Urine cytology is an easy and rapid method of detecting decoy cells in cases where renal biopsy is not possible. However, the low incidence of detection of decoy cells in the present study, together with poor correlation with PCR results, questions its sensitivity and specificity in diagnosing BKV reactivation.

N and C-terminal Sub-regions in the c-Myc Transactivation Region and their Joint Role in Creating Versatility in Folding and Binding

The proto-oncogene c-myc governs the expression of a number of genes targeting cell growth and apoptosis, and its expression levels are distorted in many cancer forms. The current investigation presents an analysis by proteolysis, circular dichroism, fluorescence and Biacore of the folding and ligand-binding properties of the N-terminal transactivation domain (TAD) in the c-Myc protein. A c-Myc sub-region comprising residues 1-167 (Myc1-167) has been investigated that includes the unstructured c-Myc transactivation domain (TAD, residues 1-143) together with a C-terminal segment, which appears to promote increased folding. Myc1-167 is partly helical, binds both to the target proteins Myc modulator-1 (MM-1) and TATA box-binding protein (TBP), and displays the characteristics of a molten globule. Limited proteolysis divides Myc1-167 in two halves, by cleaving in a predicted linker region between two hotspot mutation regions: Myc box I (MBI) and Myc box II (MBII). The N-terminal half (Myc1-88) is unfolded and does not alone bind to target proteins, whereas the C-terminal half (Myc92-167) has a partly helical fold and specifically binds both MM-1 and TBP. Although this might suggest a bipartite organization in the c-Myc TAD, none of the N and C-terminal fragments bind target protein with as high affinity as the entire Myc1-167, or display molten globule properties. Furthermore, merely linking the MBI with the C-terminal region, in Myc38-167, is not sufficient to achieve binding and folding properties as in Myc1-167. Thus, the entire N and C-terminal regions of c-Myc TAD act in concert to achieve high specificity and affinity to two structurally and functionally orthogonal target proteins, TBP and MM-1, possibly through a mechanism involving molten globule formation. This hints towards understanding how binding of a range of targets can be accomplished to a single transactivation domain.

The new MATH: homology suggests shared binding surfaces in meprin tetramers and TRAF trimers

Although apparently functionally unrelated, intracellular TRAFs and extracellular meprins share a region with conserved meprin and traf homology, MATH(1). Both TRAFs and meprins require subunit assembly for function. By structural analysis of the sequences, we provide an explanation of how meprins, which form tetramers, and TRAF molecules, which form trimers, can share homology. Our analysis suggests it is highly likely that the same oligomerization surface is used. The analysis has implications for the widely distributed group of proteins containing MATH domains.