Crossing the eukaryote-prokaryote divide:A ubiquitin homolog in the human commensal bacterium Bacteroides fragilis

The resident microbiota of the human gastrointestinal (GI) tract is comprised of ~2,000 bacterial species, the majority of which are anaerobes. Colonization of the GI tract is important for normal development of the immune system and provides a reservoir of catabolic enzymes that degrade ingested plant polysaccharides. Bacteroides fragilis is an important member of the microbiota because it contributes to T helper cell development, but is also the most frequently isolated Gram-negative anaerobe from clinical infections. During the annotation of the B. fragilis genome sequence, we identified a gene predicted to encode a homolog of the eukaryotic protein modifier, ubiquitin. Previously, ubiquitin had only been found in eukaryotes, indicating the bacterial acquisition as a potential inter-kingdom horizontal gene transfer event. Here we discuss the possible roles of B. fragilis ubiquitin and the implications for health and disease. © 2012 Landes Bioscience

The addition of arsenic trioxide to low-dose Ara-C in older patients with AML does not improve outcome

Most patients with acute myeloid leukaemia (AML) are older, with many unsuitable for conventional chemotherapy. Low-dose Ara-C (LDAC) is superior to best supportive care but is still inadequate. The combination of arsenic trioxide (ATO) and LDAC showed promise in an unrandomised study. We report a randomised trial of LDAC versus LDAC + ATO. Patients with AML according to WHO criteria or myelodysplastic syndrome with > 10% blasts, considered as unfit for conventional chemotherapy, were randomised between subcutaneous Ara-C (20mg b.d. for 10 days) and the same LDAC schedule with ATO (0.25 mg/kg) on days 1-5, 9 and 11, for at least four courses every 4 to 6 weeks. Overall 166 patients were entered; the trial was terminated on the advice of the DMC, as the projected benefit was not observed. Overall 14% of patients achieved complete remission (CR) and 7% CRi. Median survival was 5.5 months and 19 months for responders (CR: not reached; CRi: 14 months; non-responders: 4 months). There were no differences in response or survival between the arms. Grade 3/4 cardiac and liver toxicity, and supportive care requirements were greater in the ATO arm. This randomised comparison demonstrates that adding ATO to LDAC provides no benefit for older patients with AML. Leukemia (2011) 25, 1122-1127; doi:10.1038/leu.2011.59; published online 8 April 2011

TACHYKININS WITH UNUSUAL STRUCTURAL FEATURES FROM A URODELE, THE AMPHIUMA, AN ELASMOBRANCH, THE HAMMERHEAD SHARK, AND AN AGNATHAN, THE RIVER LAMPREY

Tachykinins were purified from extracts of gastrointestinal tissues of the urodele, Amphiuma tridacrylum (three-toed amphiuma), and the elasmobranch Sphyrna lewini (hammerhead shark), and from the brain of the agnathan Lampetra fluviatilis (river lamprey). The amphiuma substance P (SP) (DNPSVGQFYGLM-NH2) contains 12 amino residues compared with 11 for mammalian SP and lacks the Arg/Lys-Pro-Xaa-Pro motif that is characteristic of NK, receptor-selective agonists. Lampetra SP (RKPHPKEFVGLM-NH2) is identical to SP from the sea lamprey and the shark SP-related peptide (AKFDKFYGLM-NH2) is identical to dogfish scyliorhinin L. Amphiuma neurokinin A (NKA) (HKDAFIGLM-NH2) and lamprey NKA (HFDEFVGLM-NH2) contain 9 amino acid residues compared with 10 for mammalian NKA. The shark NKA-related peptide (ASGPTQAGIV(10)GRKRQKGEMF(20)VGLM-NH2) shows limited structural similarity to mammalian neuropeptide gamma and the teleost tachykinin, carassin but contains 24 rather than 21 amino acid residues. The data show that the primary structures of the tachykinins have been very poorly conserved during vertebrate evolution and that pressure has acted only to maintain the functionally important sequence -Phe-Xaa-Gly- Leu-Met-NH2 at the COOH-termini of the peptides.

Treatment of intestinal Behçet's syndrome with chimeric tumour necrosis factor alpha antibody

Few patients with Behçet's syndrome have gastrointestinal ulceration. Such patients are difficult to treat and have a higher mortality. Faced with refractory symptoms in two patients with intestinal Behçet's, we used the tumour necrosis factor alpha (TNF-alpha) monoclonal antibody infliximab to induce remission. Both women (one aged 27 years, the other 30 years) presented with orogenital ulceration, pustular rash, abdominal pain, bloody diarrhoea due to colonic ulceration, weight loss, and synovitis. One had thrombophlebitis, digital vasculitis, perianal fistula, and paracolic abscess; the other had conjunctivitis and an ulcer in the natal cleft. Treatment with prednisolone, methyl prednisolone, and thalidomide in one and prednisolone, colchicine, and cyclosporin in the other was ineffective. After full discussion, infliximab (3 mg/kg, dose reduced because of recent sepsis in one, and 5 mg/kg in the other) was administered. Within 10 days the ulcers healed, with resolution of bloody diarrhoea and all extraintestinal manifestations. A second infusion of infliximab was necessary eight weeks later in one case, followed by sustained (>15 months) remission on low dose thalidomide. Remission was initially sustained for 12 months in the other but thalidomide had to be stopped due to intolerance, and a good response to retreatment lasted only 12 weeks without immunosuppression, before a third infusion. The cause of Behçet's syndrome is unknown but peripheral blood CD45 gammadelta T cells in Behçet's produce >50-fold more TNF-alpha than controls when stimulated with phorbol myristate acetate and anti-CD3. Infliximab could have a role for inducing remission in Behçet's syndrome.

Diagnosis of common bile duct stones by intravenous cholangiography:prediction by ultrasound and liver function tests compared with endoscopic retrograde cholangiography

Routine intravenous cholangiography using the safer contrast medium, meglumine iotroxate, may be a useful investigation prior to laparoscopic cholecystectomy for the detection of suspected common bile duct stones. We compared this with endoscopic cholangiography.

Detection of undiagnosed coeliac disease with atypical features using antireticulin and antigliadin antibodies

Eighteen patients with a variety of non-gastrointestinal symptoms were incidentally found to have circulating antireticulin antibody and on subsequent testing were also positive for antigliadin antibody. They prospectively underwent jejunal biopsy to determine whether or not they had coeliac disease. Their age range was 21-79 years (mean 42 years). Enteropathy was present in 13 (72 per cent) and was always associated with circulating IgA antigliadin antibody. Enteropathy was not present in the five cases who had only IgG antibody. Clinical improvement occurred in eight of 11 patients who complied with a gluten-free diet and was paralleled by an improvement in the mucosal histology in seven of eight who were re-biopsied. The most remarkable cases were two patients who presented with severe debility and no apparent haematological or biochemical abnormalities, and who subsequently made a dramatic recovery on a gluten-free diet. It is concluded that antireticulin antibody detected by routine autoantibody screening and confirmed to have IgA antigliadin antibody specificity is a useful indicator of an otherwise undiagnosed enteropathy. This serves to emphasize that the condition can sometimes be associated with atypical features and significant morbidity.

Gastric emptying in patients with flatulent dyspepsia, with and without gallbladder disease

It has been suggested that the symptoms of flatulent dyspepsia are caused by a functional disturbance of the upper gastrointestinal tract. The aim of this study was to investigate delayed gastric emptying as the basis of symptoms in patients with and without gallbladder disease and after cholecystectomy. There were 13 dyspeptic patients with gallbladder disease, 12 with normal gallbladders, and 13 post-cholecystectomy patients. Gastric emptying was measured by means of a 99mTc-labelled scrambled egg meal and external scintillation counter. The rate of emptying in the symptomatic groups was compared with that in 24 asymptomatic normal control subjects and 12 non-dyspeptic patients with gallbladder disease. Delayed gastric emptying tended to occur in patients with gallbladder disease with and without dyspepsia and was not specifically associated with symptoms.

5-Fluorouracil:identification of novel downstream mediators of tumour response

5-Fluorouracil (5-FU) is routinely used in the treatment of gastrointestinal, breast and head and neck cancers. A major limitation to the use of this drug is acquired or inherent resistance.

Patients on H2-receptor antagonists--are we investigating them?

A survey was made of patients receiving H2-receptor antagonists in a group practice serving 8600 patients. Two hundred and twelve patients (2%) who had received at least one prescription for H2 antagonists in a 12 month period were identified. When compared with the practice population, men and patients over 50 years old were more likely to be taking these drugs (P less than 0.01 and P less than 0.001, respectively). One hundred and fifty-seven patients (74%) were investigated before commencing therapy; 114 (73%) of these patients were investigated via the hospital outpatient department, despite the general practitioners having full open access to barium meals. Only 23 (15%) of the patients investigated were found to have no active pathology. Twenty-nine (14%) of the 212 study patients had received one or more gastrointestinal investigations in the 18 months subsequent to starting H2-antagonist therapy. Twenty-five of these patients had also received an investigation before starting therapy. One hundred and eleven patients (52%) had had their H2 antagonist therapy initiated by their general practitioner.

Oxaliplatin/capecitabine versus oxaliplatin/infusional 5-FU in advanced colorectal cancer: The MRC COIN Trial.

Background:

COIN compared first-line continuous chemotherapy with the same chemotherapy given intermittently or with cetuximab in advanced colorectal cancer (aCRC).


Methods:

Choice between oxaliplatin/capecitabine (OxCap) and oxaliplatin/leucovorin (LV)/infusional 5-FU (OxFU) was by physician and patient choice and switching regimen was allowed. We compared OxCap with OxFU and OxCap+cetuximab with OxFU+cetuximab retrospectively in patients and examined efficacy, toxicity profiles and the effect of mild renal impairment.


Results:

In total, 64% of 2397 patients received OxCap(±cetuximab). Overall survival, progression free survival and overall response rate were similar between OxCap and OxFU but rate of radical surgeries was higher for OxFU. Progression free survival was longer for OxFU+cetuximab compared with OxCap+cetuximab but other efficacy measures were similar. Oxaliplatin/LV/infusional 5-FU (±cetuximab) was associated with more mucositis and infection whereas OxCap(±cetuximab) caused more gastrointestinal toxicities and palmar-plantar erythema. In total, 118 patients switched regimen, mainly due to toxicity; only 16% came off their second regimen due to intolerance. Patients with creatinine clearance (CrCl) 50–80?ml?min-1 on OxCap(±cetuximab) or OxFU+cetuximab had more dose modifications than those with better renal function.


Conclusions:

Overall, OxFU and OxCap are equally effective in treating aCRC. However, the toxicity profiles differ and switching from one regimen to the other for poor tolerance is a reasonable option. Patients with CrCl 50–80?ml?min-1 on both regimens require close toxicity monitoring.

Identification of the F1-ATPase at the cell surface of colonic epithelial cells:role in mediating cell proliferation

F1F0-ATPase was initially believed to be strictly expressed in the mitochondrial membrane. Interestingly, recent reports have shown that the F1 complex can serve as a cell surface receptor for apparently unrelated ligands. Here, we show for the first time the presence of the F1-ATPase at the cell surface of normal or cancerous colonic epithelial cells. Using Surface Plasmon Resonance technology and mass spectrometry, we identified a peptide hormone product of the gastrin gene (glycine-extended gastrin, G-gly), as a new ligand for the F1-ATPase. By molecular modeling, we identified the motif in the peptide sequence (EE/DxY), which directly interacts with the F1-ATPase and the amino-acids in the F1-ATPase which bind this motif. Replacement of the E9 residue by an alanine in the EE/DxY motif resulted in a strong decrease of G-gly binding to the F1-ATPase and the loss of its biological activity. In addition we demonstrated that F1-ATPase mediates the growth effects of the peptide. Indeed, blocking ATPase activity decreases G-gly-induced cell growth. The mechanism likely involves ADP production by the membrane F1-ATPase which is induced by G-gly. These results suggest an important contribution of cell surface ATPase in the pro-proliferative action of this gastrointestinal peptide.

Examining acute and chronic effects of short- and long-chain fatty acids on peptide YY (PYY) gene expression, cellular storage and secretion in STC-1 cells

PURPOSE: Peptide YY (PYY) is a gastrointestinal hormone with physiological actions regulating appetite and energy homoeostasis. The cellular mechanisms by which nutrients stimulate PYY secretion from intestinal enteroendocrine cells are still being elucidated.

METHODS: This study comprehensively evaluated the suitability of intestinal STC-1 cells as an in vitro model of PYY secretion. PYY concentrations (both intracellular and in culture media) with other intestinal peptides (CCK, GLP-1 and GIP) demonstrated that PYY is a prominent product of STC-1 cells. Furthermore, acute and chronic PYY responses to 15 short (SCFAs)- and long-chain (LCFAs) dietary fatty acids were measured alongside parameters for DNA synthesis, cell viability and cytotoxicity.

RESULTS: We found STC-1 cells to be reliable secretors of PYY constitutively releasing PYY into cell culture media (but not into non-stimulatory buffer). We demonstrate for the first time that STC-1 cells produce PYY mRNA transcripts; that STC-1 cells produce specific time- and concentration-dependent PYY secretory responses to valeric acid; that linoleic acid and conjugated linoleic acid 9,11 (CLA 9,11) are potent PYY secretagogues; and that chronic exposure of SCFAs and LCFAs can be detrimental to STC-1 cells.

CONCLUSIONS: Our studies demonstrate the potential usefulness of STC-1 cells as an in vitro model for investigating nutrient-stimulated PYY secretion in an acute setting. Furthermore, our discovery that CLA directly stimulates L-cells to secrete PYY indicates another possible mechanism contributing to the observed effects of dietary CLA on weight loss.

Aneurysms increase the risk of rebleeding after stereotactic radiosurgery for hemorrhagic arteriovenous malformations

BACKGROUND AND PURPOSE:
The purpose of this study was to define the risk of rebleeding after stereotactic radiosurgery (SRS) for hemorrhagic arteriovenous malformations with or without associated intracranial aneurysms.

METHODS:
Between 1987 and 2006, we performed Gamma Knife SRS on 996 patients with brain arteriovenous malformations; 407 patients had sustained an arteriovenous malformation hemorrhage. Sixty-four patients (16%) underwent prior embolization and 84 (21%) underwent prior surgical resection. The median target volume was 2.3 mL (range, 0.1-20.7 mL). The median margin dose was 20 Gy (range, 13.5-27 Gy).

RESULTS:
The overall rate of total obliteration defined by angiography or MRI was 56%, 77%, 80%, and 82% at 3, 4, 5, and 10 years, respectively. Before obliteration, 33 patients (8%) sustained an additional hemorrhage after SRS. The overall annual hemorrhage rate until obliteration after SRS was 1.3%. The presence of a patent aneurysm was significantly associated with an increased rehemorrhage risk after SRS (annual hemorrhage rate, 6.4%) compared with patients with a clipped or embolized aneurysm (annual hemorrhage rate, 0.8%; P=0.033).

CONCLUSIONS:
When an aneurysm is identified in patients with arteriovenous malformations selected for SRS, additional endovascular or surgical strategies should be considered to reduce the risk of bleeding during the latency interval.