Bilateral persistent hypoglossal arteries: MRI findings

Persistence of foetal anastomoses between carotid and vertebrobasilar arteries is well recognised, but their bilateral presence is rare. We report a case of bilateral persistent hypoglossal arteries. Absence of bilateral vertebral arteries was incidentally noted on neck ultrasound examination. Subsequent MRI confirmed this and revealed persistent hypoglossal arteries that arose bilaterally from the cervical internal carotid artery, entered the cranium through the hypoglossal canal and joined the lower portion of the basilar artery.

Molecular and clinical characterization of plasmid-mediated AmpC β-lactamase-producing Escherichia coli bacteraemia: a comparison with extended-spectrum β-lactamase-producing and non-resistant E. coli bacteraemia

Plasmid-mediated AmpC β-lactamase-producing Escherichia coli (AmpC-E) bacteraemia was characterized by comparison with bacteraemia caused by extended-spectrum β-lactamase (ESBL)-producing E. coli (ESBL-E) and non-resistant E. coli (NR-E) in the era of the worldwide spread of the CTX-M-15-producing O25b-ST131-B2 clone. Of 706 bloodstream E. coli isolates collected between 2005 and 2010 in three Japanese university hospitals, 111 ESBL screening-positive isolates were analysed for AmpC and ESBL genes by PCR. A case-control study was performed in which the cases consisted of all of the patients with AmpC-E bacteraemia. Phylogenetic groups, sequence types and O25b serotype were determined. Twenty-seven AmpC-E isolates (26 of which were of the CMY-2 type) were identified, and 54 ESBL-E and 54 NR-E isolates were selected for the controls. Nineteen AmpC-E isolates were also positive for ESBL. CTX-M-14 was the most prevalent ESBL type among both the AmpC-E and ESBL-E isolates. The O25b-ST131-B2 clone was the most prevalent among the ESBL-E isolates (26%) and the second most prevalent among the NR-E isolates (13%), but only one O25b-ST131-B2 clone was found among the AmpC-E isolates. Twenty-three different sequence types were identified among the AmpC-E isolates. When compared with bacteraemia with ESBL-E, previous isolation of multidrug-resistant bacteria and intravascular catheterization were independently associated with a lower risk for AmpC-E. When compared with NR-E bacteraemia, prior use of antibiotics was the only significant risk factor for AmpC-E. Unlike the spread of the O25b-ST131-B2 clone between ESBL-E and NR-E, the AmpC-E isolates were not dominated by any specific clone.

Experimental observation of the bifurcation dynamics of an intrinsic localized mode in a driven 1D nonlinear lattice

Linear response spectra of a driven intrinsic localized mode in a micromechanical array are measured as it approaches two fundamentally different kinds of bifurcation points. A linear phase mode associated with this autoresonant state softens in frequency and its amplitude grows as the upper frequency bifurcation point is approached, similar to the soft-mode kinetic transition for a single driven Duffing resonator. A lower frequency bifurcation point occurs when the four-wave-mixing partner of this same phase mode intercepts the top of the extended wave branch, initiating a second kinetic transition process.

Regional spread and control of vancomycin-resistant Enterococcus faecium and Enterococcus faecalis in Kyoto, Japan

The purpose of this investigation was to control the post-outbreak prevalence of vancomycin-resistant enterococci (VRE) in the affected Kyoto region. The study period was from 2005 to 2010. Faecal samples were subjected to VRE screening, and vancomycin resistance genes were detected by polymerase chain reaction (PCR). The genotype was determined by pulsed-field gel electrophoresis (PFGE) of genomic DNA digested with SmaI and by multilocus sequence typing (MLST). A VRE control programme was established in 2006, consisting of a laboratory-based faecal VRE screening system, annual surveillance of hospital inpatients and the promotion of adequate infection control measures. vanA-Enterococcus faecium, vanB-E. faecium and vanB-E. faecalis were detected at 35, 12 and 5 hospitals, respectively. Genotype analysis revealed that all of the vancomycin-resistant E. faecium isolates obtained since 2005 belonged to ST78, and that clonally related vanB-E. faecalis of ST64 had spread to three hospitals. The rate of faecal VRE carriage among the patients enrolled in the annual surveillance increased until 2007, when it reached 24 (1.2%) of the 2,035 enrolled patients. The rate began to decrease in 2008 and, by 2010, reached a low of 4 (0.17%) of the 2,408 enrolled patients. While VRE did spread within the Kyoto region, the VRE control programme succeeded in controlling the overall VRE spread.

Identification of functional domains and novel binding partners of STIM proteins

With a signal trap method, we previously identified stromal interaction molecule (STIM: originally named as SIM) as a protein, which has a signal peptide in 1996. However, recent works have accumulated evidences that STIM1 and STIM2 reside in endoplasmic reticulum (ER) and that both mainly sense ER Ca(2+) depletion, which plays an essential role in store operated calcium entry. In the present study, we extensively analyzed the domain functions and associated molecules of STIMs. A STIM1 mutant lacking the coiled-coil domains was massively expressed on the cell surface while mutants with the coiled-coil domains localized in ER. In addition, STIM1 mutants with the coiled-coil domains showed a longer half-life of proteins than those without them. These results are likely to indicate that the coiled-coil domains of STIM1 are essential for its ER-retention and its stability. Furthermore, we tried to comprehensively identify STIM1-associated molecules with mass spectrometry analysis of co-immunoprecipitated proteins for STIM1. This screening clarified that both STIM1 and STIM2 have a capacity to bind to a chaperone, calnexin as well as two protein-transporters, exportin1 and transportin1. Of importance, our result that glycosylation on STIM1 was not required for the association between STIM1 and calnexin seems to indicate that calnexin might function on STIM1 beyond a chaperone protein. Further information concerning regulatory mechanisms for STIM proteins including the data shown here will provide a model of Ca(2+) control as well as a useful strategy to develop therapeutic drugs for intracellular Ca(2+)-related diseases including inflammation and allergy.

De-escalation of antimicrobials in the treatment of bacteraemia due to antibiotic-sensitive pathogens in immunocompetent patients

BACKGROUND

The aim of this study was to examine the safety and efficacy of de-escalating antimicrobial therapy in immunocompetent patients presenting with bacteraemia due to antibiotic-sensitive pathogens.

METHODS

We screened 1,350 positive blood cultures identified in a single, 1,065-bed university hospital over 5 years, and retained 310 cases of bacteraemia due to antibiotic-sensitive pathogens, including (1) methicillin-sensitive staphylococci, (2) penicillin-sensitive streptococci, (3) β-lactam-sensitive (a) Escherichia coli, and (b) Klebsiella species. The efficacy of appropriate initial empirical antimicrobial therapy, the performance of de-escalated pathogen-directed therapy, and the safety and efficacy of de-escalated therapy were evaluated.

RESULTS

Among 270 appropriately treated patients, 16 (6%) died, versus 6 (15%) among 40 who were inappropriately treated (p = 0.04). While 201 of 270 patients (74%) who received appropriate initial empirical therapy were candidates for de-escalation, the treatment was de-escalated in only 79 (39%). De-escalation was associated with (1) a trend toward a lower (a) death rate (1 vs. 5%) and (b) treatment failure (4 vs. 10%), and (2) (a) a 4-day longer median duration and (b) a $50 higher median cost of antimicrobial therapy (p < 0.001).

CONCLUSIONS

When the pathogen was sensitive to antimicrobial therapy and the initial empirical treatment was effective, de-escalation of antimicrobial therapy in immunocompetent patients with bacteraemia was safe and associated with acceptable outcomes. The rate of de-escalation of antimicrobial therapy was low.

Transforming growth factor-β decreases the cancer-initiating cell population within diffuse-type gastric carcinoma cells

Stem cells in normal tissues and cancer-initiating cells (CICs) are known to be enriched in side population (SP) cells. However, the factors responsible for the regulation of expression of ABCG2, involved in efflux of dyes, in SP cells have not been fully investigated. Here, we characterized the SP cells within diffuse-type gastric carcinoma, and examined the effects of transforming growth factor-β (TGF-β) on SP cells. Diffuse-type gastric carcinoma cells established from four independent patients universally contained SP cells between 1 and 4% of total cells, which displayed greater tumorigenicity than non-SP cells did. TGF-β repressed the transcription of ABCG2 through direct binding of Smad2/3 to its promoter/enhancer, and the number of SP cells and the tumor-forming ability of cancer cells were decreased by TGF-β, although ABCG2 is not directly involved in the tumor-forming ability of SP cells. Cancer cells from metastatic site expressed much higher levels of ABCG2 and included a greater percentage of SP cells than parental cancer cells did. SP cells are thus responsible for the progression of diffuse-type gastric carcinoma, and TGF-β negatively contributes to maintain the CICs within the cancer.

Predictability of the response to tyrosine kinase inhibitors via in vitro analysis of Bcr-Abl phosphorylation

It would be of great value to predict the efficacy of tyrosine kinase inhibitors (TKIs) in the treatment of individual CML patients. We propose an immunoblot system for detecting the phosphorylation of Crkl, a major target of Bcr-Abl, in blood samples after in vitro incubation with TKIs. When the remaining phosphorylated Crkl after treatment with imatinib was evaluated as the "residual index (RI)", high values were found in accordance with imatinib resistance. Moreover, RI reflected the outcome of imatinib- as well as second generation TKIs with a high sensitivity and specificity. Therefore, this system should be useful in the selection of TKIs.

Transforming growth factor-β decreases the cancer-initiating cell population within diffuse-type gastric carcinoma cells

Stem cells in normal tissues and cancer-initiating cells (CICs) are known to be enriched in side population (SP) cells. However, the factors responsible for the regulation of expression of ABCG2, involved in efflux of dyes, in SP cells have not been fully investigated. Here, we characterized the SP cells within diffuse-type gastric carcinoma, and examined the effects of transforming growth factor-β (TGF-β) on SP cells. Diffuse-type gastric carcinoma cells established from four independent patients universally contained SP cells between 1 and 4% of total cells, which displayed greater tumorigenicity than non-SP cells did. TGF-β repressed the transcription of ABCG2 through direct binding of Smad2/3 to its promoter/enhancer, and the number of SP cells and the tumor-forming ability of cancer cells were decreased by TGF-β, although ABCG2 is not directly involved in the tumor-forming ability of SP cells. Cancer cells from metastatic site expressed much higher levels of ABCG2 and included a greater percentage of SP cells than parental cancer cells did. SP cells are thus responsible for the progression of diffuse-type gastric carcinoma, and TGF-β negatively contributes to maintain the CICs within the cancer.

GRIP1 enhances estrogen receptor alpha-dependent extracellular matrix gene expression in chondrogenic cells

OBJECTIVE

The role of postmenopause on the pathogenesis of cartilage degeneration has been an open question. We assessed cartilage degeneration in estrogen receptor (ER)alpha null mice and examined the role of glucocorticoid receptor-interacting protein 1 (GRIP1) in the ERalpha-dependent transcription of a type II collagen gene (col2a1) with special reference to a crosstalk with the transforming growth factor (TGF)-beta signaling pathway.

METHODS

The vertebral cartilaginous endplate from female ERalpha null mice was subjected to histological analyses. Col2a1 expression of primary chondrocytes (PCs) obtained from ERalpha null mice after 17beta-estradiol (E(2)) and TGF-beta1 stimulation was examined by reverse transcription polymerase chain reaction (RT-PCR). Estrogen response element (ERE) or col2a1 promoter-enhancer luciferase reporter system was used to investigate the crosstalk among ERalpha, GRIP1, and MKK6. Col2a1 expression and glycosaminoglycan (GAG) content were measured in ATDC5 cells treated with GRIP1 small interfering RNA (siRNA).

RESULTS

ERalpha deficiency clearly accelerated impairment of the vertebral cartilaginous endplate. E(2) and TGF-beta1 stimulation increased col2a1 expression in PC from wild-type mice, but not that from ERalpha null mice. The same stimulation increased the col2a1 promoter-enhancer reporter activity, and the elevated activity was decreased by dominant-negative ERalpha and p38 mitogen-activated protein kinase (MAPK) inhibitor. GRIP1 increased the E(2)-dependent ERE activation in the presence of ERalpha and constitutive-active MKK6. GRIP1 siRNA repressed col2a1 expression and GAG production in ATDC5 cells.

CONCLUSIONS

Crosstalks between ERalpha/GRIP1 and TGF-beta/MKK6/p38 MAPK pathway have protective roles on cartilage metabolism via regulating the extracellular matrices expression. The finding may lead to the development of a novel therapeutic approach for cartilage degeneration.

Patients achieving clearance of HCV with interferon therapy recover from decreased retinol-binding protein 4 levels

Retinol-binding protein 4 (RBP4) is a recently identified adipokine that is elevated in the blood in several insulin-resistant states. We investigated the association between plasma RBP4 and histological and biochemical characteristics of chronic hepatitis C (CHC), as well as changes in RBP4 levels following interferon therapy. Eighty-one patients with CHC infected with genotype 1 received treatment with peginterferon plus ribavirin. Histological data were available for 41 out of 81 patients before treatment, and the degree of fibrosis, inflammation and steatosis was assessed. Plasma levels of RBP4 were determined in serial samples (before, at the end of treatment, and at 6 months post-treatment). RBP4 levels were lower in CHC patients than in control subjects (34.6 +/- 12.3 microg/mL vs 46.2 +/- 10.5 microg/mL; P <or= 0.001). Higher RBP4 levels were linked to lower alanine aminotransferase (ALT) (P < 0.01), higher cholinesterase (P < 0.01), hyperlipidaemia (P < 0.01), hyperglycaemia (P < 0.05), and higher platelet (P < 0.01) count in CHC patients. Plasma RBP4 levels tended to decrease concomitantly with the grade of histological fibrosis, activity, and steatosis. RBP4 levels at baseline were not a predictor of the response to antiviral therapy in CHC patients. After peginterferon plus ribavirin therapy, only patients who had achieved clearance of hepatitis C virus had higher post-treatment RBP4 levels. This study suggests that an association between RBP4 levels and abnormal metabolic features, and that liver function may determine RBP4 levels in CHC patents. This is further supported by the observation that RBP4 levels increased significantly after treatment only in sustained virological response (SVR) patients and reached levels comparable to those of healthy subjects.

Food webs in Mongolian grasslands: the analysis of 13C and 15N natural abundances

Overgrazing often lowers species richness and productivity of grassland communities. For Mongolian grassland ecosystems, a lack of detailed information about food-web structures makes it difficult to predict the effects of overgrazing on species diversity and community composition. We analysed the delta13C and delta15N signatures of herbaceous plants, arthropods (grouped by feeding habit), wild and domestic mammals, and humans in central Mongolia to understand the predominant food-web pathways in this grassland ecosystem. The delta13C and delta15N values of mammals showed little variation within species, but varied considerably with slope position for arthropods. The apparent isotopic discrimination between body tissue and hair of mammals was estimated as 2.0 per thousand for delta13C and 2.1 per thousand for delta15N, which was large enough to cause overestimation of the trophic level of mammals if not taken into account when using hair samples to measure isotopic enrichment.

Comparison of hepatic oxidative DNA damage in patients with chronic hepatitis B and C

8-Hydroxydeoxyguanosine (8-OHdG) is a promutagenic DNA lesion produced by hydroxyl radicals and is recognized as a useful marker in estimating DNA damage induced by oxidative stress. The aim of this study was to clarify the clinical significance of hepatic 8-OHdG levels in patients with chronic viral hepatitis. Hepatic 8-OHdG accumulation was investigated in patients with chronic hepatitis C (CH-C) (n = 77) and chronic hepatitis B (CH-B) (n = 34) by immunohistochemical staining of liver biopsy samples. 8-OHdG positive hepatocytes were significantly higher in patients with CH-C compared to CH-B (median 55.0 vs 18.8 cells/10(5) mum(2), P < 0.0001). The number of positive hepatocytes significantly increased with the elevation of serum aminotransferase levels, especially in CH-C patients (8-OHdG vs alanine aminotransferase (ALT)/aspartate aminotrasferase (AST) were r = 0.738/0.720 in CH-C and 0.506/0.515 in CH-B). 8-OHdG reactivity was strongly correlated with body and hepatic iron storage markers in CH-C (vs serum ferritin, r = 0.615; vs hepatic total iron score, r = 0.520; vs hepatic hepcidin mRNA levels, r = 0.571), although it was related to serum HBV-DNA titers (r = 0.540) and age of patients (r = -0.559) in CH-B. These results indicate that hepatic oxidative DNA damage is common in chronic viral hepatitis, in particular chronic HCV-infected patients, suggesting a possible link between chronic hepatic inflammation and hepatocarcinogenesis. The strong positive correlation between hepatic DNA damage and iron overload suggests that iron content is one of the most likely mediators of hepatic oxidative stress and iron reduction may be beneficial to reduce the incidence of hepatic cancer in CH-C patients.