Metal sensing in Salmonella: implications for pathogenesis.
ABSTRACT Both the essentiality and toxicity of transition metals are exploited as part of mammalian immune defenses against bacterial infection. Salmonella serovars continue to cause serious medical and veterinary problems worldwide and detecting deficiency and excess of different metal ions (such as copper, iron, zinc, manganese, nickel, and cobalt) is fundamental to their virulence. This involves multiple DNA-binding metal-responsive transcription factors that discriminate between elements and trigger expression of genes that mediate appropriate responses to metal fluxes. This review focuses on the metal stresses encountered by Salmonella during infection and the roles of the different metal-sensing regulatory proteins and their target genes in adapting to these changing metal levels. Current knowledge regarding the mechanisms of metal-regulated gene expression and the structural features of sensory metal binding sites are described. In addition, the principles governing the ability of the different sensors to detect specific metals within a cell to control cytosolic metal levels are also discussed. These proteins represent potential targets for the development of new therapeutic approaches.
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ABSTRACT: Diverting stomas are commonly performed during ileoanal and coloanal anastomoses. We studied a series of patients after loop ileostomy closure to determine risk factors and the impact of the interval from primary operation on morbidity. Ninety-three consecutive patients undergoing loop ileostomy closure at a single institution after coloanal or ileoanal anastomosis were retrospectively reviewed. Complications were classified as medical or surgical according to its treatment requirements. Results were correlated to clinical and operative features. Of the 93 patients, 43 were male and 50 were female with mean age of 56 years. Overall, complication rate was 17.2 percent. The most common complication was small-bowel obstruction. Complications required operative management in 3.2 percent and medical management alone in 14 percent. There was no mortality. There was no correlation between complication occurrence and age, gender, type of suture (manual or mechanical), and operative time. Complications were significantly associated with primary disease and shorter interval between primary operation and ileostomy closure. Regarding the optimal interval between primary surgery and ileostomy closure, the cutoff value for increased risk of developing postoperative complications was 8.5 weeks, below which the risk of such occurrence was significantly higher with a sensitivity rate of 88 percent. Diverting loop ileostomy adds little cumulative morbidity to the primary operation and is a safe option for diversion to protect a low colorectal anastomosis. To further reduce morbidity, the interval between primary operation and ileostomy closure should be no shorter than 8.5 weeks.Diseases of the Colon & Rectum 11/2006; 49(10):1539-45. · 3.34 Impact Factor
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ABSTRACT: The purpose of this study was to determine the natural history of anastomotic leakage after elective colorectal resection and supraperitoneal anastomosis without temporary stoma. Medical records from 1990 to 1997 were studied; 655 consecutive patients underwent colonic or rectal resection (without stoma). Patients were divided into two groups: those with clinical anastomotic leakage confirmed by laparotomy (group 1) and those without anastomotic leakage (group 2). Postoperative clinical and biologic findings were compared between the two groups. Anastomotic leakage occurred in 39 of 655 patients (6%). Clinically suspected anastomotic leakage was only confirmed by contrast radiography in 13 of 24 patients (54%), and by CT in 8 of 9 patients (89%). Significantly more patients in group 1 than group 2 had the following: fever (> 38 degrees C) on day 2 (p < 0.001); absence of bowel action on day 4 (p < 0.001); diarrhea before day 7 (p < 0.001); collection of more than 400 mL of fluid through abdominal drains from day 0 to day 3 (p < 0.01); renal failure on day 3 (p < 0.02); and leukocytosis after day 7 (p < 0.02). Among the 39 patients in group 1, 28 (71%) had at least one of these clinical or biologic manifestations before day 5, but the mean delay for reoperation was only 8 days. The combination of signs observed before day 5 was associated with an increased risk of anastomotic leakage, from 18% with two signs to 67% with three signs. Overall mortality rate was 2% (13 of 655) and was significantly higher in group 1 than group 2: 5 of 39 (13%) versus 8 of 616 (1%, p < 0.001). In patients with anastomotic leakage, death occurred in 5 of 23 patients (22%) reoperated on after day 5, versus 0 of 11 patients (0%) reoperated on before day 5 (NS). Univariate analysis showed that three clinical characteristics were associated with a significantly high risk of mortality after reoperation for anastomotic leakage: age greater than 65 years (p < 0.01), American Anesthesiologist Association score greater than 3 (p < 0.05), and blood transfusions during the first operation (p < 0.02). In our study, some postoperative clinical and biologic signs were associated with a higher risk of anastomotic leakage. The knowledge of these findings might help in the early diagnosis and management of patients with anastomotic leakage after large bowel resection.Journal of the American College of Surgeons 01/2000; 189(6):554-9. · 4.50 Impact Factor
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ABSTRACT: Despite improvement in surgical techniques and stapling devices during the last 10 years, colorectal anastomoses are still prone to leakage. The purpose of this study was to assess the performance and safety of stapled anastomoses in rectal surgery and to identify factors that influence the occurrence of anastomotic leaks. A review was undertaken of 1,014 patients who underwent stapled anastomoses to the rectum or anal canal for colorectal cancer or benign disease between 1989 and 1995 in a tertiary care institution. Indications for operations, comorbidities at admission, preoperative bowel preparation, stapler size, intraoperative events, associated surgical procedures, and clinical outcomes were tested for any association with anastomotic leak. A double stapled technique was used in 154 patients and a conventional single stapler technique was used in 860. Postoperative mortality was 1.6%, and the overall morbidity was 18.4%. Clinically apparent anastomotic leak developed in 29 patients (2.9%). Anastomotic dehiscence occurred in 22 of 284 patients (7.7%) after low stapling (within 7 cm from the anal verge) and in 7 of 730 patients (1%) after high stapling (p < 0.001). Diabetes mellitus, use of pelvic drainage, and duration of surgery were significantly related to the occurrence of anastomotic leak by the univariate analysis. Multivariate regression analysis identified an anastomotic distance from the anal verge within 7 cm as the only variable related to the occurrence of postoperative leak (p < 0.001). Low anastomoses were associated with a leak rate greater than with high colorectal anastomoses. We conclude that anastomoses to the rectum using the circular stapler can be done with low mortality and morbidity.Journal of the American College of Surgeons 08/1997; 185(2):105-13. · 4.50 Impact Factor