Carbon monoxide (CO) is a stress-inducible gas generated by heme oxygenase (HO) eliciting adaptive responses against toxicants; however, mechanisms for its reception remain unknown. Serendipitous observation in metabolome analysis in CO-overproducing livers suggested roles of cystathionine ␤-synthase (CBS) that rate-limits transsulfuration pathway and H 2 S generation, for the gas-responsive receptor. Studies using recombinant CBS indicated that CO binds to the prosthetic heme, stabilizing 6-coordinated CO-Fe(II)-histidine complex to block the activity, whereas nitric oxide (NO) forms 5-coordinated structure without inhibiting it. The CO-overproducing livers down-regulated H 2 S to stimulate HCO 3 ؊ -dependent choleresis: these responses were attenuated by blocking HO C arbon monoxide (CO) is generated from inducible heme oxygenase 1 (HO-1) and constitutive heme oxygenase 2 (HO-2), respectively, and has the ability to regulate neurovascular functions, 1,2 apoptotic responses, 3,4 and metabolism of xenobiotics and toxicants. 5,6 This gas is overproduced through increased delivery of heme as a substrate and the HO-1 induction on exposure to stressors such as hypoxia and oxidative stress. Mechanisms by which CO regulates cell functions appear to involve an activation of soluble guanylate cyclase (sGC), the enzyme that allows the gas to bind to the prosthetic heme to synthesize cyclic guanosine monophosphate as a second messenger. 1 Distinct from nitric oxide (NO) that forms 5-coordinated NO-Fe(II) complex to trigger full activation of the enzyme, CO activates this enzyme only modestly because the gas binding stabilizes 6-coordinated CO-Fe(II)-histidine complex. 7 Mitogen-activated protein kinase has also been shown to serve as a CO-responsive signal transducer. 8 Gene disruption of HO-1 increases sensitivity to overproduction of reactive oxygen species, inflammatory mediators or xenobiotic metabolism, whereas the gene transfer or CO inhalation under these circumstances suppresses such pathogenic responses. 7-9 However, direct mechanisms for the CO reception to trigger these adaptive responses of metabolism remain unknown.Because this gas has the ability to inhibit ferrous form of the prosthetic heme of enzymes, tryptophan 2,3-dioxygenase or cytochromes P450 have been considered puta-

To investigate the trends of antimicrobial resistance in pathogens isolated from surgical site infections (SSI), a Japanese surveillance committee conducted the first nationwide survey. Seven main organisms were collected from SSI at 27 medical centers in 2010 and were shipped to a central laboratory for antimicrobial susceptibility testing. A total of 702 isolates from 586 patients with SSI were included. Staphylococcus aureus (20.4 %) and Enterococcus faecalis (19.5 %) were the most common isolates, followed by Pseudomonas aeruginosa (15.4 %) and Bacteroides fragilis group (15.4 %). Methicillin-resistant S. aureus among S. aureus was 72.0 %. Vancomycin MIC 2 μg/ml strains accounted for 9.7 %. In Escherichia coli, 11 of 95 strains produced extended-spectrum β-lactamase (Klebsiella pneumoniae, 0/53 strains). Of E. coli strains, 8.4 % were resistant to ceftazidime (CAZ) and 26.3 % to ciprofloxacin (CPFX). No P. aeruginosa strains produced metallo-β-lactamase. In P. aeruginosa, the resistance rates were 7.4 % to tazobactam/piperacillin (TAZ/PIPC), 10.2 % to imipenem (IPM), 2.8 % to meropenem, cefepime, and CPFX, and 0 % to gentamicin. In the B. fragilis group, the rates were 28.6 % to clindamycin, 5.7 % to cefmetazole, 2.9 % to TAZ/PIPC and IPM, and 0 % to metronidazole (Bacteroides thetaiotaomicron; 59.1, 36.4, 0, 0, 0 %). MIC₉₀ of P. aeruginosa isolated 15 days or later after surgery rose in TAZ/PIPC, CAZ, IPM, and CPFX. In patients with American Society of Anesthesiologists (ASA) score ≥3, the resistance rates of P. aeruginosa to TAZ/PIPC and CAZ were higher than in patients with ASA ≤2. The data obtained in this study revealed the trend of the spread of resistance among common species that cause SSI. Timing of isolation from surgery and the patient's physical status affected the selection of resistant organisms.

Characteristics of atherosclerotic isolated iliac artery aneurysms (IAAs) and various strategies for their treatment were assessed retrospectively. The computerized medical records of 18 patients who underwent surgical or endovascular treatment of an IAA during the 10 years from April 1993 to March 2003 at our university hospital were reviewed to obtain information on patient demographics, risk factors, type of IAA treatment, and outcome. Additional data were obtained by mail and telephone. Patients with an IAA were compared with 168 patients treated for an abdominal aortic aneurysm (AAA) also at our institution. Early in the series of isolated IAA repairs, patients underwent prosthetic graft interposition ( n = 7) or thromboexclusion ( n = 4). Subsequently, patients had either endovascular thromboembolization ( n = 4) or endovascular thromboembolization with femorofemoral crossover bypass ( n = 3). No perioperative deaths occurred in the series. Deep venous thrombosis developed postoperatively in one patient; there were no other serious complications. The cumulative patency rate for the implanted interposition grafts during the mean observation time of 5.5 years was 100%. No endoleakage was observed after the endovascular procedures. In the long-term, five patients died of causes unrelated to the IAA treatment. A statistical analysis revealed no significant differences between the IAA group and the AAA group with respect to atherosclerotic risk factors. In conclusion, open surgical procedures to repair isolated IAAs generally have a good outcome, although the risk of injury to adjacent iliac veins remains. Endovascular treatments appear to have some advantages, but studies including long-term follow-up are needed to assess the efficacy and durability of prosthetic grafts used for these procedures.

A 37-year-old male patient presented with abdominal pain and diarrhea. Computed tomography showed a large superior mesenteric vein aneurysm. The patient had a history of Crohn's disease and underwent an ileocecal resection 7 years previously. A selective angiogram of the superior mesenteric artery revealed that a dilated branch of this artery fed directly into the superior mesenteric vein. The iatrogenic superior mesenteric arteriovenous fistula was successfully closed by transarterial coil embolization. Successful endovascular treatment for a superior mesenteric arteriovenous fistula has been recently reported; however, the complications of this new modality are not well understood. We herein review the current literature and discuss endovascular treatment.