Identification of the alpha-enolase P46 in the extracellular membrane vesicles of Bacteroides fragilis

BACKGROUND Members of the Bacteroides fragilis group are the most important components of the normal human gut microbiome, but are also major opportunistic pathogens that are responsible for significant mortality, especially in the case of bacteraemia and other severe infections, such as intra-abdominal abscesses. Up to now, several virulence factors have been described that might explain the involvement of B. fragilis in these infections. The secretion of extracellular membrane vesicles (EMVs) has been proposed to play a role in pathogenesis and symbiosis in gram-negative bacteria, by releasing soluble proteins and other molecules. In B. fragilis, these vesicles are known to have haemagglutination and sialidosis activities, and also contain a capsular polysaccharide (PSA), although their involvement in virulence is still not clear. OBJECTIVE The aim of this study was to identify proteins in the EMV of the 638R B. fragilis strain by mass spectrometry, and also to assess for the presence of Bfp60, a surface plasminogen (Plg) activator, previously shown in B. fragilis to be responsible for the conversion of inactive Plg to active plasmin, which can also bind to laminin-1. METHODS B. fragilis was cultured in a minimum defined media and EMVs were obtained by differential centrifugation, ultracentrifugation, and filtration. The purified EMVs were observed by both transmission electron microscopy (TEM) and immunoelectron microscopy (IM). To identify EMV constituent proteins, EMVs were separated by 1D SDS-PAGE and proteomic analysis of proteins sized 35 kDa to approximately 65 kDa was performed using mass spectrometry (MALDI-TOF MS). FINDINGS TEM micrographs proved the presence of spherical vesicles and IM confirmed the presence of Bfp60 protein on their surface. Mass spectrometry identified 23 proteins with high confidence. One of the proteins from the B. fragilis EMVs was identified as an enolase P46 with a possible lyase activity. MAIN CONCLUSIONS Although the Bfp60 protein was not detected by proteomics, α-enolase P46 was found to be present in the EMVs of B. fragilis. The P46 protein has been previously described to be present in the outer membrane of B. fragilis as an iron-regulated protein.

Distal malignant biliary obstruction: a prospective randomised trial comparing plastic and uncovered self-expanding metal stents in the palliation of symptomatic jaundice

Background: The aim of this study was to determine the safety and clinical effectiveness of 10Fr plastic biliary stents compared to uncovered self-expanding metal stents (SEMS) for palliative treatment of patients with inoperable extra-hepatic malignant biliary obstruction in a public hospital in South Africa.Methods: From January 2009 to December 2013, 40 patients who were admitted to a tertiary academic centre because of distal malignant biliary obstruction were enrolled in a prospective randomized study. Patients were randomly assigned to receive an uncovered SEMS or a plastic stent deployed through the biliary stricture during endoscopic retrograde cholangiopancreatography (ERCP).Results: Patient survival time in the two groups did not differ significantly (median: SEMS ­ 114 days; plastic ­ 107 days). Stent failure was more common in the plastic stent group (7/19 vs. 1/21). The results became significant after 6 months of follow-up. There was no significant difference between the two groups in the incidence of serious adverse events.Conclusions: SEMS had a longer duration of patency than plastic stents, which recommends their use in the palliative treatment of patients with biliary obstruction due to distal malignant biliary obstruction

Resection of biliary mucinous cystic neoplasms of the liver: a prospective cohort series of 13 consecutive patients

Background: Biliary mucinous cystic neoplasms (BMCNs) are uncommon neoplastic septated intrahepatic cysts which are often incorrectly diagnosed and have the potential for malignant transformation.Objectives:To assess the outcome of surgical resection of BMCNs.Methods:A prospective liver surgery database was used to identify patients who underwent surgery at Groote Schuur Hospital Complex for BMCN from 1999 to 2015. Demographic variables including age and gender were documented as well as detailed preoperative imaging, location and size, operative treatment, extent of resection, histology, postoperative complications and outcome.Results:Thirteen female patients (median age 45 years) had surgery. Eleven were diagnosed by imaging for symptoms. Two were jaundiced. One cyst was found during an elective cholecystectomy. Five cysts were located centrally in the liver. Before referral three cysts were treated with percutaneous drainage and two were treated with operative deroofing. Six patients had anatomical liver resections and seven patients had non anatomical liver resections of which two needed ablation of residual cyst wall. One patient needed a biliary-enteric reconstruction to treat a fistula. Median operative time was 183 minutes (range: 130­375). No invasive carcinoma was found. There was no operative mortality. One surgical site infection and one intra-abdominal collection were treated. Two patients developed recurrent BMCN after 24 months.Conclusion:BMCNs should be considered in middle aged women who have well encapsulated multilocular liver cysts. Treatment of large central BMCNs adjacent to vascular and biliary structures may require technically complex liver resections and are best managed in a specialised hepato-pancreatico-biliary unit

Outcome of liver resection for small bowel neuroendocrine tumour metastases

Background: Small bowel neuroendocrine tumours frequently metastasise to the liver. While liver resection improves survival and provides symptomatic relief, multifocal bilobar disease adds complexity to surgical management.Objectives: This study evaluated outcome in patients with small bowel neuroendocrine liver metastases who underwent liver resection at Groote Schuur Hospital and UCT Private Academic Hospital.Methods: All patients with small bowel neuroendocrine liver metastases treated with resection from 1990­2015 were identified from a prospective departmental database. Demographic data, operative management, morbidity and mortality using the Accordion classification were analysed. Survival was assessed using the Kaplan-Meier method.Results: Seventeen patients (9 women, 8 men, median age 55 years, range 31­76) underwent resection. Each patient had all identifiable liver metastases resected and/or ablated (median n = 3, range 1­20). Ten patients had major anatomical liver resections. Three patients had five segments resected, and seven had four resected. Nine patients (53%) had a concurrent bowel resection of the small bowel NET primary and a regional mesenteric lymphadenectomy. Median operating time was 255 min (range 150­720). Median blood-loss was 800 ml (range 200­10,000). Five patients required intraoperative blood transfusion. Hepatic vascular inflow control was used in ten patients (56.5 min median, range 20­150 min), which included hepatic inflow control n = 8, total hepatic exclusion n = 1, and selective hepatic exclusion n = 1. Median postoperative hospital stay was 9 days (range 2­28). Thirteen complications occurred in seven patients. Accordion grades were 1 n = 3, 2 n = 4, 3 n = 3, 4 n = 2, 6 n = 1. One patient required reoperation for bleeding and a bile leak. One patient died of a myocardial infarction 36 hours postoperatively. Sixteen patients (94%) had symptomatic improvement. Five-year overall survival was 91% (median follow-up 36 months, range 14­86 months).Conclusion: Our data show that liver resection can be safely performed for small bowel NET metastases with a good 5-year survival. However, a substantial number of patients require a major liver resection and these patients are best managed at a multidisciplinary referral centre

Previsäo de dose terapêutica do lítio / Foresight of lithium therapeutic doses

A previsäo da dose terapêutica de lítio, isto é, da dose diária de lítio que produza concentraçöes séricas dentro da faixa terapêutica é importante na clínica, principalmente em situaçöes em que se deseja obter o efeito terapêutico no menor tempo possível. Um método de previsäo, com algumas modificaçöes, foi utilizado em 17 voluntários sadios, os quais posteriormente receberam lítio durante o período de um mês. No final desse período, todos os voluntários apresentavam concentraçöes séricas na faixa terapêutica estabelecida (0,6 a 1,0 mEq/l). Essas concentraçöes apresentaram correlaçäo (r = 0,41; p < 0,05) com as concentraçöes medidas 24 horas após a dose inicial, as quais serviram para a previsäo da dose. As modificaçöes introduzidas no método de previsäo utilizado diminuíram muito a sua precisäo, limitando a sua utilidade clínica em larga escala