Ischemia/Reperfusion Injury Alters Sphingolipid Metabolism in the Gut.

BACKGROUND: Intestinal ischemia/reperfusion injury (I/R) is a significant cause of morbidity and mortality in surgical patients. Ceramide is a mediator of apoptosis and has been implicated as increasing bacterial infection susceptibility. The metabolite of ceramide, sphingosine, was recently shown to play an important role in the cell-autonomous, innate immune response of the upper respiratory tract by killing bacterial pathogens. The role of ceramide and/or sphingosine after mesenteric I/R is unknown. We investigated the specific effects of intestinal I/R on tissue ceramide and sphingosine concentration and resulting susceptibility to bacterial invasion. METHODS: To simulate intestinal I/R, C57BL/6 mice underwent 30 minutes of vascular clamp-induced occlusion of the superior mesenteric artery followed by variable reperfusion times. Jejunum segments and intraluminal contents were analyzed for ceramide, sphingosine and bacteria using immunohistochemistry. Jejunum samples were also homogenized and cultured to quantify bacterial presence in the proximal intestine. RESULTS: We hypothesized that I/R induces an increase of ceramide in the intestine resulting in increased permeability, while a concomitant decrease of sphingosine may permit bacterial overgrowth. Control mice had no measurable bacteria in their proximal jejunum as measured by tissue culture and immunohistochemistry. After I/R, bacterial counts in the jejunum increased in a time-dependent manner, reaching a peak at 12 hours after reperfusion. Immunohistochemical analysis revealed a marked increase in ceramide in the vasculature of jejunal villi. In contrast, while ceramide concentrations in the epithelial cells decreased after I/R, sphingosine levels appeared to remain unchanged. Surprisingly, bacteria present in the jejunal lumen following I/R contained a ceramide coat. CONCLUSION: These data indicate that intestinal I/R leads to small intestine bacterial overgrowth as well as ceramide formation in the jejunal vasculature, which may contribute to the gut permeability associated with this injury. Moreover, our novel finding of ceramide in bacterial membranes represents a new opportunity to investigate the dynamic pathogenicity of the gut microbiome. The hypothesis that a decrease of sphingosine after I/R permits bacterial overgrowth in the intestine was not confirmed.

Aneurysm of the cranial mesenteric artery as a site of carriage of Salmonella enterica subsp. enterica serovar Abortusequi in the horse.

Salmonella enterica subsp. enterica serovar Abortusequi is a pathogen restricted to horses. Our investigation targeted 4 draft horses (9-10 months old) kept on a Japanese farm that had suffered an outbreak of S. Abortusequi abortion. The 4 horses were suspected to be carriers of the bacterium owing to their high agglutination titers (≥1:2,560) in tube agglutination testing. The owners' on-farm observations confirmed that the horses had no apparent abnormalities, and S. Abortusequi was not isolated from their blood, rectal swabs, or sternal bone marrow fluid at antemortem investigation. However, at autopsy, all horses displayed the following: suppurative aneurysm of the cranial mesenteric artery with heavy infection with Strongylus vulgaris larvae; heavy intestinal parasitic infection with Gasterophilus intestinalis, Parascaris equorum, Anoplocephala perfoliata, and S. vulgaris; and enlargement of the systemic lymph nodes. In each case, large numbers of S. Abortusequi were isolated from the anterior mesenteric artery thrombus. The thrombus isolates harbored a single virulence plasmid, and the pulsed-field gel electrophoresis profiles of the isolates were identical not only to each other but also to those of Japanese enzootic strains of S. Abortusequi. These results reveal that parasitic aneurysms of the cranial mesenteric artery should be considered an important possible site of carriage of S. Abortusequi in horses. The results also suggest high clonality of the isolated serovar in the horse population in Japan.

Polybacterial Periodontal Pathogens Alter Vascular and Gut BH4/nNOS/NRF2-Phase II Enzyme Expression.

Periodontal disease is a highly prevalent chronic inflammatory disease and is associated with complex microbial infection in the subgingival cavity. Recently, American Heart Association supported a century old association between periodontal disease and atherosclerotic vascular disease. We have recently shown that polybacterial periodontal infection led to aortic atherosclerosis and modulation of lipid profiles; however the underlying mechanism(s) has not been yet demonstrated. Altered nitric oxide (NO) synthesis and tetrahydrobiopterin (BH4), a cofactor for nitric oxide synthases (NOS) has long been shown to be associated with vascular dysfunction and gastrointestinal motility disorders. We sought to examine the mechanism of periodontal infection leading to altered vascular and gastrointestinal smooth muscle relaxation, focusing on the BH4/nNOS pathways. In addition, we also have investigated how the antioxidant system (NRF2-Phase II enzyme expression) in vascular and GI specimens is altered by oral infection. Eight week old male ApoEnull mice were either sham-infected or infected orally for 16 weeks with a mixture of major periodontal bacteria Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia to induce experimental periodontitis. Serum, vascular (mesenteric), stomach, and colon specimens were collected at the end of periodontal pathogen infection. Bacterial infection induced significant (p<0.05) reductions in the levels of BH4,in ratio of BH4:BH2+B and also in nitric oxide levels compared to sham-infected controls. In addition, we identified a significant (p<0.05) reduction in eNOS dimerization, nNOS dimerization and protein expression of BH4 biosynthesis enzymes; GCH-1, DHFR and NRF2 & Phase II enzymes in infected mice versus controls in both mesenteric artery and colon tissues. However, we found no differences in nNOS/BH4 protein expression in stomach tissues of infected and sham-infected mice. This suggests that a polybacterial infection can cause significant changes in the vascular and colonic BH4/nNOS/NRF2 pathways which might lead to impaired vascular relaxation and colonic motility.

[Native valve Aspergillus fumigatus endocarditis with blood culture positive and negative for galactomannan antigen. Case report and literature review]. / Endocarditis por Aspergillus fumigatus en válvula nativa con hemocultivo positivo y galactomanano negativo. Descripción de un caso y revisión de la literatura.

Native valve endocarditis caused by Aspergillus spp. is an uncommon disease with a high mortality rate. Generally, Aspergillus is isolated from affected valve in post-mortem or biopsy specimens. However, its isolation from blood cultures is exceedingly rare. We report a case of fungal endocarditis in a native mitral valve with the isolation of Aspergillus fumigatus both in valve vegetation and in blood culture bottles. The patient underwent valve replacement and antifungal treatment with voriconazole and caspofungin, but he died on post-operative day 45 with disseminated aspergillosis confirmed by necropsy. Paradoxically, galactomannan antigen detection in serum was negative. This is the third case of Aspergillus endocarditis with positive blood culture reported in the literature.

Gastrin induces leukocyte-endothelial cell interactions in vivo and contributes to the inflammation caused by Helicobacter pylori.

Gastric mucosal inflammation causes hypergastrinemia, and gastrin receptors have been detected in several leukocyte types. We have analyzed whether gastrin affects the leukocyte-endothelial cell interactions in vivo by monitoring leukocyte rolling, adhesion, and emigration in rat mesenteric venules using intravital microscopy. Mesenteric superfusion with exogenous gastrin increased these processes in a concentration- and time-dependent manner, effects prevented by the cholecystokinin (CCK)-2 receptor antagonists (proglumide, L-365,260) but not by the CCK-1 receptor antagonist devazepide. A similar response was induced by exogenous CCK or endogenously released gastrin. CCK-2 receptors were localized in mesenteric macrophages and polymorphonuclear leukocytes. This effect of gastrin is not modulated by somatostatin and is independent of the endogenous release of histamine. To analyze whether hypergastrinemia elicited by Helicobacter pylori (HP) modulates the inflammation induced by the germ, rats were chronically administered with an extract of a CagA+/VacA+ strain of HP. This protocol increased gastrinemia and induced an inflammatory response in the rat mesentery. Blockade of CCK-2 receptors attenuated this response and induced a qualitative change in the leukocyte infiltrate suggestive of a receding inflammatory process. Our results reveal a new proinflammatory role of gastrin that seems to contribute to the maintenance of the inflammation elicited by HP components.

Infected aortic aneurysms: imaging findings.

PURPOSE: To determine the imaging characteristics of infected aortic aneurysms. MATERIALS AND METHODS: Review of records of patients with surgical and/or microbiologic proof of infected aortic aneurysm obtained over a 25-year period revealed 31 aneurysms in 29 patients. This study included 21 men and eight women (mean age, 70 years). One radiologist reviewed 28 computed tomographic (CT) studies (22 patients underwent CT once and three patients underwent CT twice), 12 arteriograms (12 patients underwent arteriography once), eight nuclear medicine studies (six patients underwent nuclear medicine imaging once and one patient underwent nuclear medicine imaging twice), and three magnetic resonance (MR) studies (three patients underwent MR imaging once). Features evaluated included aneurysm size, shape, and location; branch involvement; aortic wall calcification; gas; radiotracer uptake on nuclear medicine studies; and periaortic and associated findings. The location of infected aortic aneurysms was compared with that of arteriosclerotic aneurysms. RESULTS: Aneurysms were located in the ascending aorta (n = 2, 6%), descending thoracic aorta (n = 7, 23%), thoracoabdominal aorta (n = 6, 19%), paravisceral aorta (n = 2, 6%), juxtarenal aorta (n = 3, 10%), infrarenal aorta (n = 10, 32%), and renal artery (n = 1, 3%). Two patients had two infected aortic aneurysms. CT revealed 25 saccular (93%) and two fusiform (7%) aneurysms with a mean diameter at initial discovery of 5.4 cm (range, 1-11 cm). Paraaortic soft-tissue mass, stranding, and/or fluid was present in 13 (48%) of 27 aneurysms, and early periaortic edema with rapid aneurysm progression and development was present in three (100%) patients with sequential studies. Other findings included adjacent vertebral body destruction with psoas muscle abscess (n = 1, 4%), kidney infarct (n = 1, 4%), absence of calcification in the aortic wall (n = 2, 7%), and periaortic gas (n = 2, 7%). Angiography showed 13 saccular aneurysms with lobulated contour in 10 (77%). Nuclear medicine imaging showed increased activity consistent with infection in six (86%) of seven aneurysms. MR imaging showed three saccular aneurysms. Adjacent abnormal vertebral body marrow signal intensity was seen in one (33%) of three patients. CONCLUSION: Saccular aneurysms (especially those with lobulated contour) with rapid expansion or development and adjacent mass, stranding, and/or fluid in an unusual location are highly suspicious for an infected aneurysm.

The effects of hemodynamic shock and increased intra-abdominal pressure on bacterial translocation.

BACKGROUND: We hypothesized that hemorrhagic shock followed by the abdominal compartment syndrome (ACS) resulted in bacterial translocation (BT) from the gastrointestinal (GI) tract. METHODS: Nineteen Yorkshire swine (20-30 kg) were divided into two groups. In the experimental group, group 1 (n = 10), animals were hemorrhaged to a mean arterial pressure (MAP) of 25-30 mm Hg for a period of 30 minutes and resuscitated to baseline MAP. Subsequently, intra-abdominal pressure (IAP) was increased to 30 mm Hg above baseline by instilling sterile normal saline into the peritoneal cavity. The IAP was maintained at this level for 60 minutes. Acid/base status, gastric mucosal ph (pHi), superior mesenteric artery (SMA) blood flow, and hemodynamic parameters were measured and recorded. Blood samples were analyzed by polymerase chain reaction (PCR) for the presence of bacteria. Spleen, lymph node, and portal venous blood cultures were obtained at 24 hours. Results were analyzed by ANOVA and are reported as mean +/- SEM. The second group was the control. These animals did not have the hemorrhage, resuscitation, or intra-abdominal hypertension (IAH) but were otherwise similar to the experimental group in terms of laparotomy and measured parameters. RESULTS: SMA blood flow in group 1 (baseline of 0.87 +/- 0.10 l/min) decreased in response to hemorrhage (0.53 +/- 0.10 l/min, p = 0.0001) and remained decreased with IAH (0.63 l/min +/- 0.10, p = 0.0006) as compared to control and returned towards baseline (1.01 +/- 0.5 l/min) on relief of IAH. pHi (baseline of 7.21 +/- 0.03) was significantly decreased with hemorrhage (7.04 +/- 0.03, p = 0.0003) and decreased further after IAH (6.99 +/- 0.03, p = 0.0001) in group 1 compared to control, but returned toward baseline at 24 hours (7.28 +/- 0.04). The mean arterial pH decreased significantly from 7.43 +/- 0.01 at baseline to 7.27 +/- 0.01 at its nadir within group 1 (p = 0.0001) as well as when compared to control (p = 0.0001). Base excess was also significantly decreased between groups 1 and 2 during hemorrhage (3.30 +/- 0.71 vs. 0.06 +/- 0.60, p = 0.001) and IAH (3.08 +/- 0.71 vs. -1.17 +/- 0.60, p = 0.0001). In group 1, 8 of the 10 animals had positive lymph node cultures, 2 of the 10 had positive spleen cultures, and 2 of the 10 had positive portal venous blood cultures for gram-negative enteric bacteria. Only 2 of the 10 animals had a positive PCR. In group 2, five of the nine animals had positive lymph node cultures, zero of the nine had positive spleen cultures, and one of the nine had positive portal venous blood cultures. Two of the nine animals had positive PCRs. There was no significant difference in cultures or PCR results between the two groups (Fisher's exact test, p = 0.3). CONCLUSION: In this study, hemorrhage followed by reperfusion and a subsequent insult of IAH caused significant GI mucosal acidosis, hypoperfusion, as well as systemic acidosis. These changes did not appear to be associated with a significant bacterial translocation as judged by PCR measurements, tissue, or blood cultures.

Effects of group B Streptococcus on the responses to U46619, endothelin-1, and noradrenaline in isolated pulmonary and mesenteric arteries of piglets.

The release of endogenous vasoconstrictors together with changes in the vascular responses are central to the pathophysiology of sepsis. The effects of in vitro incubation for 20 h with heat-killed group B Streptococcus (GBS, 3 x 10(7) colony-forming units mL-1) on the vasoconstrictor responses to noradrenaline (NA, 10(-8) to 10(-4) M), the thromboxane A2 analog 9,11-dideoxy-11 alpha, 9 alpha-epoxymethanoprostaglandin F2 alpha (U46619; 10(-10) M to 10(-6) M) and endothelin-1 (ET-1, 10(-11) to 3 x 10(-9) M) were evaluated on isolated intrapulmonary and mesenteric arteries from 10-17-d-old piglets. The incubation with GBS reduced the maximal contractile response to NA and ET-1 (p < 0.01) in both arteries. The nitric oxide (NO) synthase (NOS) inhibitor N omega-nitro-L-arginine methyl ester (L-NAME; 10(-4) M) completely reversed this hyporesponsiveness. GBS-treated mesenteric arteries also showed a significant reduction of the maximal contractions induced by U46619 (p < 0.05) and this effect was inhibited by 10(-4) M L-NAME. In contrast, the maximal contractile responses to U46619 were similar in control and in GBS-treated pulmonary arteries. Addition of L-NAME did not modify the contractile responses to U46619 in GBS-treated pulmonary arteries. In conclusion, GBS-treated systemic arteries from neonatal piglets showed decreased responses to NA, U46619, and ET-1 due to enhanced NO release. GBS-treated pulmonary arteries also exhibited decreased responses to NA and ET-1 but not to U46619. Induction of NOS in vascular smooth muscle may play a key role in the hypotension and loss of systemic vascular responsiveness that occurs in GBS sepsis. The absence of pulmonary hyporesponsiveness to U46619 may partially explain the coexistence during sepsis of pulmonary hypertension and lung NOS induction.

[Study on translocation of intestinal microflora into the blood of mesenteric vessels and lymph nodes in children with portal hypertension syndrome]. / Izuchenie translokatsii kishechnoi mikroflory v krov mezenterialnykh sosudov i limfouzly u detei s sindromom portalnoi gipertenzii.

A total of 42 children aged 6 months to 14 years who had the portal hypertension syndrome were studied. Blood and a lymph node were taken during a planned surgery by applying venous anastomosis. Translocation to the veins of the small and large bowels and to the mesenteric lymph nodes were recorded in 35 (83.3%), 34 (81%), and 17 (41%) patients, respectively. Translocation of aerobic bacteria (81, 78.6, and 40.5%) was more common than that of anaerobic ones (11.9, 11.9, and 4.8%) to the blood of the small and large bowels and lymph nodes, respectively, gram-negative bacteria heading the list in their frequency, Streptococci ranking next to the latter. The data on the composition of fecal microflora in the same children prior to surgery are given in the paper, which suggests that they had compensatory dysbacteriosis. A contribution of various factors (portal hypertension, operative stress, dysbacteriosis, etc.) to the development of translocation and its pathogenetic value are discussed too.