James Dooley

Wilson's disease

Progressive hepatolenticular degeneration, or Wilsons disease, is a genetic disorder of copper metabolism. Knowledge of the clinical presentations and treatment of the disease are important both to the generalist and to specialists in gastroenterology and hepatology, neurology, psychiatry, and paediatrics. Wilsons disease invariably results in severe disability and death if untreated. The diagnosis is easily overlooked but if discovered early, effective treatments are available that will prevent or reverse many manifestations of this disorder. Studies have identified the role of copper in disease pathogenesis and clinical, biochemical, and genetic markers that can be useful in diagnosis. There are several chelating agents and zinc salts for medical therapy. Liver transplantation corrects the underlying pathophysiology and can be lifesaving. The discovery of the Wilsons disease gene has opened up a new molecular diagnostic approach, and could form the basis of future gene therapy.

Aire-Dependent Alterations in Medullary Thymic Epithelium Indicate a Role for Aire in Thymic Epithelial Differentiation

The prevalent view of thymic epithelial differentiation and Aire activity holds that Aire functions in terminally differentiated medullary thymic epithelial cells (MTECs) to derepress the expression of structural tissue-restricted Ags, including pancreatic endocrine hormones. An alternative view of these processes has proposed that Aire functions to regulate the differentiation of immature thymic epithelial cells, thereby affecting tissue-restricted Ag expression and negative selection. In this study, we demonstrate that Aire impacts several aspects of murine MTECs and provide support for this second model. Expression of transcription factors associated with developmental plasticity of progenitor cells, Nanog, Oct4, and Sox2, by MTECs was Aire dependent. Similarly, the transcription factors that regulate pancreatic development and the expression of pancreatic hormones are also expressed by wild-type MTECs in an Aire-dependent manner. The altered transcriptional profiles in Aire-deficient MTECs were accompanied by changes in the organization and composition of the medullary epithelial compartment, including a reduction in the medullary compartment defined by keratin (K) 14 expression, altered patterns of K5 and K8 expression, and more prominent epithelial cysts. These findings implicate Aire in the regulation of MTEC differentiation and the organization of the medullary thymic compartment and are compatible with a role for Aire in thymic epithelium differentiation.

The thymic epithelial microRNA network elevates the threshold for infection-associated thymic involution via miR-29a mediated suppression of the IFN-α receptor

Thymic output is a dynamic process, with high activity at birth punctuated by transient periods of involution during infection. Interferon-α (IFN-α) is a critical molecular mediator of pathogen-induced thymic involution, yet despite the importance of thymic involution, relatively little is known about the molecular integrators that establish sensitivity. Here we found that the microRNA network dependent on the endoribonuclease Dicer, and specifically microRNA miR-29a, was critical for diminishing the sensitivity of the thymic epithelium to simulated infection signals, protecting the thymus against inappropriate involution. In the absence of Dicer or the miR-29a cluster in the thymic epithelium, expression of the IFN-α receptor by the thymic epithelium was higher, which allowed suboptimal signals to trigger rapid loss of thymic cellularity.

Familial autoinflammation with neutrophilic dermatosis reveals a regulatory mechanism of pyrin activation

A mutation in pyrin that disrupts regulation leads to autoinflammatory disease. Guarding inflammation The innate immune system is hard-wired to protect people from infection. However, mutations in these protective genes can lead to uncontrolled inflammation, resulting in autoinflammatory disease. Now, Masters et al. describe a family with an autoinflammatory disease caused by a previously unreported mutation in pyrin. This mutation disrupts pyrin regulation and mimics the effect of pathogen sensing by pyrin, leading to proinflammatory interleukin-1β (IL-1β) production. Indeed, targeting IL-1β resolved disease in one patient. These data suggest that pyrin is regulated through a guard-like mechanism, which guards against autoinflammation in humans. Pyrin responds to pathogen signals and loss of cellular homeostasis by forming an inflammasome complex that drives the cleavage and secretion of interleukin-1β (IL-1β). Mutations in the B30.2/SPRY domain cause pathogen-independent activation of pyrin and are responsible for the autoinflammatory disease familial Mediterranean fever (FMF). We studied a family with a dominantly inherited autoinflammatory disease, distinct from FMF, characterized by childhood-onset recurrent episodes of neutrophilic dermatosis, fever, elevated acute-phase reactants, arthralgia, and myalgia/myositis. The disease was caused by a mutation in MEFV, the gene encoding pyrin (S242R). The mutation results in the loss of a 14-3-3 binding motif at phosphorylated S242, which was not perturbed by FMF mutations in the B30.2/SPRY domain. However, loss of both S242 phosphorylation and 14-3-3 binding was observed for bacterial effectors that activate the pyrin inflammasome, such as Clostridium difficile toxin B (TcdB). The S242R mutation thus recapitulated the effect of pathogen sensing, triggering inflammasome activation and IL-1β production. Successful therapy targeting IL-1β has been initiated in one patient, resolving pyrin-associated autoinflammation with neutrophilic dermatosis. This disease provides evidence that a guard-like mechanism of pyrin regulation, originally identified for Nod-like receptors in plant innate immunity, also exists in humans.

Endoscopic extraction of bile duct stones: management related to stone size.

Endoscopic sphincterotomy has become the first line treatment for patients with common bile duct (CBD) stones. This technique may fail, however, due to difficult anatomy, previous surgery, periampullary diverticula or the presence of a large stone. The importance of stone size to the success of endoscopic sphincterotomy has not been fully assessed. A prospective study was carried out over the period January 1987 to December 1989 on 100 patients (45 male, 55 female, median age 69 years, range 19-97) with CBD stones in which a policy of early duct clearance was followed. Endoscopic retrograde cholangiopancreatography (ERCP) was performed and the stone size and number recorded from the cholangiograms and corrected for magnification. Sphincterotomy was performed using a diathermy unit with a cutting current and stones were extracted using a balloon catheter or a Dormia basket. Of the 100 patients with CBD stones receiving ERCP, successful clearance of the biliary tree was possible in seven without endoscopic sphincterotomy and five were felt to be unsuitable for endoscopic sphincterotomy. Of the remaining 88 patients endoscopic sphincterotomy was successful in 75 (85%). Of the 75 patients having endoscopic sphincterotomy stone clearance was successful in 44 (59%). There were no deaths and only four complications, which rapidly resolved on conservative treatment (two acute pancreatitis, two bleeding). The number of CBD stones present was similar in those patients with successful endoscopic sphincterotomy and duct clearance (median 1, range 1-10, n = 44) as in those in whom it failed (median 2, range 1-6, n = 31). In contrast there was a highly significant difference when stone size was analysed (successful clearance median stone size 10 mm, range 3-27 mm; unsuccessful: median 18 mm, range 10-42, p<0.001). Stones less than 10 mm in diameter (n=21) were all removed successfully whereas in patients with stones over 15 mm (n=25) only three were removed endoscopically (12%). All patients with evidence of residual stones had additional treatment. Of these 31 patients, 10 had surgery, 11 had insertion of an endoprosthesis, and 10 had dissolution treatment with methyl-tert-butyl ether through a nasobiliary catheter. This study shows the importance of stone size to the success rate of endoscopic removal of bile duct stones.

A prospective controlled study comparing brush and bile exfoliative cytology for diagnosing bile duct strictures.

Imaging of biliary strictures may suggest malignancy but cytology can provide a tissue diagnosis. The aim of this study is to compare the diagnostic value of brush cytology and bile cytology. Thirty two patients (20 males, 12 females, median age 66 years, range 31-84) with biliary strictures at endoscopic retrograde cholangio pancreatography (24) or percutaneous transhepatic cholangiography (8) had bile cytology and brush cytology. Brushings were taken using a modified Geenan cytology brush (6 Fr gauge, Wilson Cook) passed alongside a guide wire placed through the stricture. Bile was aspirated after insertion of an internal/external catheter or an endoprosthesis. Bile and brushings were examined by one experienced cytologist (AD) and was reported as positive or negative for malignant cells. Twenty nine patients had malignant strictures. Sixteen were confirmed by histology and 13 had malignancy suggested by clinical follow up. Three patients had resection of histologically benign strictures. The overall sensitivity of brush cytology (17 of 29 positive, 59%) was significantly greater than bile cytology (seven of 29 positive, 24%) (p < 0.01) as was the diagnostic accuracy (63 v 31%, p < 0.01). None of the patients had positive bile cytology with negative brush cytology. There were no procedure related complications and the average sampling time once the guide wire had been inserted was less than five minutes. It is concluded that brush cytology is more sensitive than bile cytology and with the technique described is safe and rapid.

Molecular control over thymic involution: From cytokines and microRNA to aging and adipose tissue

The thymus is the primary organ for T‐cell differentiation and maturation. Unlike other major organs, the thymus is highly dynamic, capable of undergoing multiple rounds of almost complete atrophy followed by rapid restoration. The process of thymic atrophy, or involution, results in decreased thymopoiesis and emigration of naïve T cells to the periphery. Multiple processes can trigger transient thymic involution, including bacterial and viral infection(s), aging, pregnancy and stress. Intense investigations into the mechanisms that underlie thymic involution have revealed diverse cellular and molecular mediators, with elaborate control mechanisms. This review outlines the disparate pathways through which involution can be mediated, from the transient infection‐mediated pathway, tightly controlled by microRNA, to the chronic changes that occur through aging.

Alterations of the medullary epithelial compartment in the Aire-deficient thymus: implications for programs of thymic epithelial differentiation.

A widely held model of thymic epithelial differentiation is based on patterns of keratin expression, where a K8+K5+ progenitor gives rise to K8+K5/K14− cortical thymic epithelium (CTEC), and medullary thymic epithelium (MTEC) are K8−K5+K14+. The thymic phenotype of p63-deficient mice indicates that p63 is an important regulator of proximal stages of thymic epithelial differentiation. In this study, we have examined several features of the thymic medullary compartment in wild-type and Aire-deficient thymi in an effort to integrate the proapoptotic activity of Aire with these different perspectives of TE differentiation. Patterns of keratin and p63 expression by MTEC described here are difficult to reconcile with postmitotic MTEC that express a K8−K14+ phenotype and suggest that the patterns of p63 and keratin expression reflecting differentiation programs of other epithelial tissues provide a useful framework for revising models of TE differentiation. Alterations of the Aire−/− MTEC compartment included reduced expression of p63, increased frequency of MTEC expressing truncated Aire protein, and shifts in the pattern of keratin expression and epithelial morphology. These data suggest a scenario where cellular targets of Aire-mediated apoptosis are postmitotic MTEC that have not yet completed their terminal differentiation program. According to this view, the minor population of globular K8+K14−/low MTEC observed in the Aire+/+ thymus and significantly expanded in the Aire−/− thymic medulla represent end-stage, terminally differentiated MTEC. These Aire-dependent alterations of the MTEC compartment suggest that the activity of Aire is not neutral with respect to the program of MTEC differentiation.

NON-SURGICAL TREATMENT OF BILIARY OBSTRUCTION

Bileduct catheterisation percutaneously through the liver can be used in patients with obstructive jaundice as an adjunct or as an alternative to surgery. Preoperative drainage allows adequate treatment of severe cholangitis and reduces jaundice. Palliative drainage, whether internal or external, can be used instead of surgery. Drainage through the liver succeeded in 40 of 41 patients. Two complications followed the procedure and were treated conservatively. Bile drainage was established through an endoprosthesis into the duodenum in 7 patients and externally through a catheter in the remaining 33. The technique is described, and its use in patients with suppurative cholangitis and benign and malignant biliary strictures is illustrated.

Value of exfoliative cytology for investigating bile duct strictures.

The cause of a biliary tract stricture may be difficult to determine radiologically. Exfoliative biliary cytology was evaluated in 62 patients (median age 65 years, range 30-94) with biliary tract strictures presenting to the Hepatobiliary Unit between January 1984 and December 1989. Bile samples were taken during endoscopic retrograde cholangiopancreatography (ERCP) in 42 patients, percutaneous cholangiography in 14, and both in six. The site of stricturing was upper third of the bile duct in 43% (n = 27), middle third in 10% (n = six), and lower third in 47% (n = 29). Of the 47 patients with radiological appearances of a malignant stricture, 22 (47%) had histological confirmation by biopsy either under computed tomography guidance, at endoscopy, at operation, or at necropsy. Fourteen of the 47 patients had positive cytology (30%). In seven patients cytology alone established the presence of malignancy (15%) and in the other seven positive cytology was confirmed by histology. The addition of cytology to tissue biopsy therefore allowed malignancy to be confirmed in 29 of the 47 patients (62%). None of the 15 patients subsequently shown to have benign disease had positive cytology. Sensitivity of the technique was 30% and specificity 100%. Samples for exfoliative cytology are simple to obtain, the results are highly specific and should be a routine part of the investigation of biliary strictures.