Imaging mass spectrometry of intraspecies metabolic exchange revealed the cannibalistic factors of Bacillus subtilis

During bacterial cannibalism, a differentiated subpopulation harvests nutrients from their genetically identical siblings to allow continued growth in nutrient-limited conditions. Hypothesis-driven imaging mass spectrometry (IMS) was used to identify metabolites active in a Bacillus subtilis cannibalism system in which sporulating cells lyse nonsporulating siblings. Two candidate molecules with sequences matching the products of skfA and sdpC, genes for the proposed cannibalistic factors sporulation killing factor (SKF) and sporulation delaying protein (SDP), respectively, were identified and the structures of the final products elucidated. SKF is a cyclic 26-amino acid (aa) peptide that is posttranslationally modified with one disulfide and one cysteine thioether bridged to the α-position of a methionine, a posttranslational modification not previously described in biology. SDP is a 42-residue peptide with one disulfide bridge. In spot test assays on solid medium, overproduced SKF and SDP enact a cannibalistic killing effect with SDP having higher potency. However, only purified SDP affected B. subtilis cells in liquid media in fluorescence microscopy and growth assays. Specifically, SDP treatment delayed growth in a concentration-dependent manner, caused increases in cell permeability, and ultimately caused cell lysis accompanied by the production of membrane tubules and spheres. Similarly, SDP but not SKF was able to inhibit the growth of the pathogens Staphylococcus aureus and Staphylococcus epidermidis with comparable IC₅₀ to vancomycin. This investigation, with the identification of SKF and SDP structures, highlights the strength of IMS in investigations of metabolic exchange of microbial colonies and also demonstrates IMS as a promising approach to discover novel biologically active molecules.     

Subepicardial Aneurysm: Echocardiographic Evaluation and Evolution

Subepicardial aneurysms (SEA) are an infrequent and serious form of subacute cardiac rupture complicating myocardial infarction. An early diagnosis and surgical repair may be life saving. SEA comprise an abrupt interruption of the myocardium, with a narrow neck and thin wall containing only the epicardium. It may progress to fatal cardiorrhexis. We describe the echocardiographic evolution of this type of cardiac rupture and the contribution of contrast-enhanced echocardiography. A possible pathophysiological mechanism is proposed.     

Preventative effects of a probiotic, Lactobacillus salivarius ssp. salivarius, in the TNBS model of rat colitis

AIM: To investigate the intestinal anti-inflammatory effect and mechanism of a probiotic Lactobacillus salivarius ssp. salivarius CECT5713 in the TNBS model of rat colitis. METHODS: Female Wistar rats (180-200 g) were used in this study. A group of rats were administered orally the probiotic L. salivarius ssp. salivarius(5×108 CFU suspended in 0.5 mL of skimmed milk) daily for 3 wk. Two additional groups were used for reference, a non-colitic and a control colitic without probiotic treatment, which received orally the vehicle used to administer the probiotic. Two weeks after starting the experiment, the rats were rendered colitic by intracolonic administration of 10 mg of TNBS dissolved in 0.25 mL of 500 mL/L ethanol. One week after colitis induction, all animals were killed and colonic damage was evaluated both histologically and biochemically. The biochemical studies performed in colonic homogenates include determination of myeloperoxidase (MPO) activity, glutathione (GSH) content, leukotriene B4 (LTB4) and tumor necrosis factor a (TNF-α) levels, as well as inducible nitric oxide synthase (iNOS) expression. In addition, the luminal contents obtained from colonic samples were used for microbiological studies, in order to determine Lactobacilli and Bifidobacteria counts. RESULTS: Treatment of colitic rats with L salivarius ssp. salivarius resulted in amelioration of the inflammatory response in colitic rats, when compared with the corresponding control group without probiotic treatment. This anti-inflammatory effect was evidenced macroscopically by a significant reduction in the extent of colonic necrosis and/or inflammation induced by the administration of TNBS/ethanol (2.3±0.4 cm vs 53.4±0.3 cm in control group, P<0.01) and histologically by improvement of the colonic architecture associated with a reduction in the neutrophil infiltrate in comparison with non-treated colitic rats. The latter was confirmed biochemically by a significant reduction of colonic MPO activity (105.3±26.0 U/g vs 180.6±21.9 U/g, P<0.05) a marker of neutrophil infiltration. The beneficial effect was associated with an increase of the colonic GSH content (1 252±42 nmol/g vs 1 087±51 nmol/g,P<0.05), which is depleted in colitic rats, as a consequence of the oxidative stress induced by the inflammatory process. In addition, the treatment of colitic rats with L. salivarius resulted in a significant reduction of colonic TNF-α levels (509.4±68.2 pg/g vs 782.9±60.1 pg/g, P<0.01) and in a lower colonic iNOS expression, when compared to TNBS control animals without probiotic administration. Finally, treated colitic rats showed higher counts of Lactobacilli species in colonic contents than control colitic rats, whereas no differences were observed in Bifidobacteria counts. CONCLUSION: Administration of the probiotic L. salivarius ssp. salivarius CECT5713 facilitates the recovery of the inflamed tissue in the TNBS model of rat colitis, an effect associated with amelioration of the production of some of the mediators involved in the inflammatory response in the intestine, such as cytokines, including TNF-α and NO. This beneficial effect could be ascribed to its effect on the altered immune response that occurs in this inflammatory condition.     

Chagas disease in rural areas of Chaco Province, Argentina: epidemiologic survey in humans, reservoirs, and vectors

We studied the seroprevalence of antibodies against Trypanosoma cruzi in the human population along with domiciliary infestation by triatomine bugs in an area endemic for Chagas disease in the Chaco Province of Argentina. In addition, we carried out parasitologic surveys in patients, dogs, wild mammals, and vectors. The mean seroprevalence in humans was 27.81% (109 of 392) and 24.14% (63 of 261) in 1-15-year-old children. The minimum domiciliary infestation rate was 13.33%, with certain areas reaching 53.85%. The prevalence was 15.09% (16 of 106) in dogs and 35.71% (10 of 28) in opossums. Infection with T. cruzi was detected in 30.10% (59 of 196) of the Triatoma infestans tested. Compared with nationwide studies, our data suggest that 1) there are zones requiring immediate sanitary action, and 2) nationwide estimates are based on very heterogeneous epidemiologic situations. This heterogeneity emphasizes the importance of in-depth studies of restricted areas to provide additional information for a better understanding of the present status of Chagas disease in Argentina.     

Gallstones are associated with carotid atherosclerosis

Background/Aims: Gallstone disease (GD) and cardiovascular disease (CD) are common diseases worldwide with considerable economical impact and they are strongly associated. Carotid atherosclerosis is an excellent marker of risk for CD like stroke and myocardial infarction. The aim of this study was to assess the association between gallstones and carotid atherosclerosis. Methods: A cross‐sectional study was conducted. We evaluated subjects with ultrasonographical evidence of GD and asymptomatic subjects without such evidence. Anthropometric, clinical and biochemical variables were collected. The Metabolic syndrome was evaluated using adult treatment panel III criteria. Carotid artery intima–media thickness (CIMT) was determined by a standard ultrasound protocol. Insulin‐like growth factor‐1 (IGF‐1) serum levels were measured in all subjects. Results: We studied 191 subjects: 62 subjects with GD (53.2% males) and 129 asymptomatic subjects without GD (65.9% males). Subjects with GD exhibited a higher body mass index, body fat percent, insulin serum levels and CIMT (P<0.05 for all). The prevalence of GD was higher in subjects with a CIMT>0.75 independently of other factors [odds ratio (OR) 2.12, 95% confidence interval (CI) 1.04–4.34; P=0.039], and for every 0.1 mm increase in CIMT the independent probability to be a case of GD increased by a factor of 1.25 (95% CI 1.02–1.53; P=0.027). IGF‐1 levels did not differ among groups. Conclusions: Subjects with GD exhibit greater carotid atherosclerosis, and therefore have a higher risk for stroke and myocardial infarction.     

Intraductal papillary mucinous tumor: diagnostic and therapeutic approach

Primary cystic pancreatic neoplasms are rare tumors, with an approximate prevalence of 10% of cystic pancreatic lesions. Most of these lesions correspond to mucinous cystic neoplasm, serous cystoadenoma and intraductal papillary mucinous tumor (IPMT). IPMT is characterized by diffuse dilatation of the main pancreatic duct and/or side branches with inner defects related to mucin or tumor, or mucin extrusion from a patent ampulla. IPMT has a low potential for malignancy, with a low growth rate, a low rate of metastatic spread and postsurgical recurrence. Over the last few years, major advances have been made in the diagnostic and therapeutic management of this tumor.     

Plasma levels of cell adhesion molecules during hyperinsulinemia and modulation of vasoactive mediators

Endothelial expression of cell adhesion molecules (CAMs) plays an important role in atherosclerosis. Atherosclerosis is increased in hyperinsulinemic states, but whether insulin per se is proatherogenic remains unclear. To investigate the effects of hyperinsulinemia on CAM expression, plasma levels of ICAM-1, VCAM-1 and E-selectin were measured before and after forearm infusion of insulin in healthy subjects. Insulin administration for 2h resulted in significant hyperinsulinemia, whereas no significant change was observed in soluble CAMs (all p > 0.05). Because insulin stimulates endothelial release of both endothelin-1 (ET-1) and nitric oxide (NO), which may modulate the expression of CAMs, we also investigated the response of CAMs to ET-1 receptor blockade, alone and in combination with NO synthesis inhibition. ET-1 receptor blockade during hyperinsulinemia resulted in a vasodilator response, but did not affect soluble CAMs (all p > 0.05). Superimposition of NO inhibition by L-NMMA reversed the vasodilator effect of ET-1 blockade, without affecting soluble CAMs (all p > 0.05). In conclusion, acute hyperinsulinemia, alone or during ET-1 and NO pathway blockade, does not affect soluble CAMs. These results do not support a direct effect of insulin on endothelial cells to affect leukocyte adhesiveness to the vascular wall.