Oligosaccharide structure determines prebiotic role of β-galactomannan against Salmonella enterica ser. Typhimurium in vitro

Prebiotics and probiotics are considered natural alternatives to dietary antibiotics in animal production. Plant extracts and yeast cell walls are mannose—rich products that can be used as substrate for adhesion of Gram-negative bacteria. We assessed whether the structure of these saccharides is relevant to develop their role as prebiotics and therefore, their suitability to be used as alternatives to antibiotics to prevent intestinal infections in pigs. The prebiotic functionality of β-galactomannan (βGM), mannanoligosaccharide from yeast Saccharomyces cerevisiae (Mannan SC) and monosaccharide D-Mannose were studied in porcine intestinal epithelial cells (IPI-2I) challenged with Salmonella enterica ser. Typhimurium. Results showed that in vitro challenge with Salmonella induces the secretion of proinflammatory cytokine IL6 and chemokine CXCL8 compared with control without infection. Both βGM and Mannan SC, attenuate Salmonella-induced secretion of IL6 and CXCL8. Interestingly, cells treated with D-mannose showed similar levels of proinflammatory IL6 and CXCL8 compared with the control of infection. These data suggest that prebiotic role of βGM is related to its oligosaccharide structure.     

Invasive Salmonella enterica Serotype Typhimurium Infections,Democratic Republic of the Congo, 2007–2011

Infection with Salmonella enterica serotype Typhimurium sequence type (ST) 313 is associated with high rates of drug resistance, bloodstream infections, and death. To determine whether ST313 is dominant in the Democratic Republic of the Congo, we studied 180 isolates collected during 2007–2011; 96% belonged to CRISPOL type CT28, which is associated with ST313.     

Luminal Salmonella Endotoxin Affects Epithelial and Mast Cell Function in the Proximal Colon of Pigs

Background: The effects of proximal small-bowel resection on absorption and synthesis of cholesterol are unclear. Methods: To study cholesterol absorption and synthesis after proximal gut resections of variable length, plasma plant sterols, cholestanol, and cholesterol precursors were measured 1 and 2 months after 50% and 75% proximal small-bowel resection or transection. To examine the effect of increased crypt cell proliferation and brush border development on cholesterol absorption, the results were related to the mucosal morphology, crypt cell proliferation, and disaccharidase activities of the remaining small bowel. Results: Campesterol levels in proportion to cholesterol decreased markedly more, and those of cholestanol markedly less, than would be expected simply due to the amount of proximal small intestine removed, whereas sitosterol proportions decreased in proportion to the length of gut resection. Campesterol proportions markedly (P = 0.06) increased between 1 and 2 months after 50% resection but remained unchanged after 75% resection. Crypt cell proliferation was only increased in the 75% resection group (P < 0.05). The longer the proximal gut resection, the lower was the mucosal enzyme activity. Both resection groups showed increased plasma cholesterol precursor proportions and crypt depth (P < 0.05), whereas villus height remained unchanged. After massive proximal resection campesterol and sitosterol proportions were inversely related to crypt cell proliferation (r = -0.86-0.83, P < 0.01). Conclusions: Increased crypt cell proliferation activated by massive proximal gut resection may act as a previously unrecognized factor in aggravating cholesterol malabsorption and retarding its recovery during the early postoperative period. These findings warrant further investigation.     

Differential expression from two iron-responsive promoters in Salmonella enterica serovar Typhimurium reveals the presence of iron in macrophage-phagosomes

The metal status of macrophage-phagosomes during Salmonella infection is largely unknown. In this study, we have precisely calibrated the metal-specificities of two metal-responsive promoters, P_iroBCDE and P_sodB, from Salmonella enterica serovar Typhimurium and used these to directly monitor iron-levels in Salmonella-containing macrophage-phagosomes. Expression from the P_iroBCDE promoter is highly elevated in metal-depleted media but low in media supplemented with iron or cobalt, and to a lesser extent manganese. In contrast, P_sodB shows low levels of expression in metal-depleted media but is induced in media supplemented with iron but no other metals at maximum permissive concentrations. In both cases, iron-responsive expression corresponds to changes in the number of iron atoms per bacterial cell and is unaffected by pH or the presence of reactive oxygen species (hydrogen peroxide and superoxide). Importantly, expression from P_iroBCDE remained low while expression from P_sodB was elevated during infection of both Nramp1^+/+ and Nramp1^−/− macrophages. Expression from a control promoter, P_polA, unaffected by metal ions, remained unchanged. These findings are therefore consistent with the presence of iron within Salmonella-containing macrophage-phagosomes and support a model in which the toxic potential of iron may be exploited as a component of the respiratory burst killing mechanism.     

螺旋藻精片毒性实验研究

目的探讨螺旋藻精片安全性毒性实验。方法采用小鼠急性经口毒性试验、Ames试验、小鼠骨髓嗜多染红细胞微核试验和小鼠精子畸形试验及大鼠30天喂养试验。结果螺旋藻对小鼠急性经口毒性实验结果大于15000mg/kgBW,体内体外致突变实验结果均为阴性,30天喂养试验,以3334、5000、6667mg/kgBW(分别相当成人日用量的50、75、100倍)3个剂量组的样品掺入饲料中,连续喂养30天,试验期间动物生长发育良好,各剂量组的动物体重、增重量和进食量及食物利用率组间相比无差异,与对照组比较,差异均无显著性(P>0.05);各剂量组血常规和生化检测指标、脏器重量及脏器/体重比值与对照组比较,差异均无显著性(P>0.05);病理组织学检查结果,各实验组大鼠肝、肾、胃肠、脾、睾丸和卵巢等组织均未见有病理改变。结论本试验提示螺旋藻对大鼠30天毒性实验及小鼠毒性试验未产生不良影响。     

Paediatric acalculous cholecystitis

Three cases of acalculous cholecystitis were found in a review of gall bladder disease over a 34-year period. Each case is presented and the literature is reviewed. Offprint requests to: K. B. Stokes     

Multiply Resistant (MR) Salmonella enterica Serotype Typhimurium DT 12 and DT 120: A Case of MR DT 104 in Disguise?

Multiresistant Salmonella enterica serotype Typhimurium definitive phage type (DT) 12 and DT 120 are more closely related to DT 104 than to non-multiresistant strains of their respective phage types. Multiresistant DT 12 and DT 120 appear to have arisen due to changes in phage susceptibility of DT 104 rather than horizontal transfer of resistance genes.