Helicobacter pylori cholesterol glucosylation modulates autophagy for increasing intracellular survival in macrophages.

Cholesterol-α-glucosyltransferase (CGT) encoded by the type 1 capsular polysaccharide biosynthesis protein J (capJ) gene of Helicobacter pylori converts cellular cholesterol into cholesteryl glucosides. H. pylori infection induces autophagy that may increase bacterial survival in epithelial cells. However, the role of H. pylori CGT that exploits lipid rafts in interfering with autophagy for bacterial survival in macrophages has not been investigated. Here, we show that wild-type H. pylori carrying CGT modulates cholesterol to trigger autophagy and restrain autophagosome fusion with lysosomes, permitting a significantly higher bacterial burden in macrophages than that in a capJ-knockout (∆CapJ) mutant. Knockdown of autophagy-related protein 12 impairs autophagosome maturation and decreases the survival of internalised H. pylori in macrophages. These results demonstrate that CGT plays a crucial role in the manipulation of the autophagy process to impair macrophage clearance of H. pylori.

Mixed Infections of Helicobacter pylori Isolated from Patients with Gastrointestinal Diseases in Taiwan.

Background. Persistent Helicobacter pylori infection may induce several upper gastrointestinal diseases. Two major virulence factors of H. pylori, vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA), are thought to be associated with the severity of disease progression. The distribution of vacA and cag-pathogenicity island (cag-PAI) alleles varies in H. pylori isolated from patients in different geographic regions. Aim. To assess the association between mixed infection of H. pylori clinical isolates from Taiwanese patients and the severity of gastrointestinal diseases. Methods. A total of 70 patients were enrolled in this study. Six distinct and well-separated colonies were isolated from each patient and 420 colonies were analyzed to determine the genotypes of virulence genes. Results. The prevalence of mixed infections of all H. pylori-infected patients was 28.6% (20/70). The rate of mixed infections in patients with duodenal ulcer (47.6%) was much higher than that with other gastrointestinal diseases (P < 0.05). Conclusions. H. pylori mixed infections show high genetic diversity that may enhance bacterial adaptation to the hostile environment of the stomach and contribute to disease development.

The bacterial interactions in the nasopharynx of children receiving adenoidectomy.

Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae are the common pathogens that colonize in the nasopharynx of children. Polymicrobial interactions are thought to play an important role in different sites throughout the human body. However, there are currently very few studies that investigate the interactions between S. aureus, S. pneumoniae, and H. influenzae in the nasopharynx. We retrospectively analyzed the adenoid tissue culture from 269 children who received adenoidectomy. S. aureus, S. pneumoniae, and H. influenzae constituted the major microorganisms which were cultured from these adenoidectomies, at 23.4%, 21.6%, and 18.2%, respectively. S. pneumoniae and H. influenzae were the most prevalent in the preschool-aged children (3 < age ≤ 6), whereas S. aureus was more prevalent in infants and toddlers (age ≤ 3) and school-aged children (age > 6). Bacterial interference was found between S. aureus and S. pneumoniae and between S. aureus and H. influenzae, whereas there was an association found between S. pneumoniae and H. influenzae. The synergism and antagonism among these three species are investigated in the following paper, with the possible mechanisms involved in these interactions also discussed.

Acute and chronic fluctuations in blood glucose levels can increase oxidative stress in type 2 diabetes mellitus.

In order to investigate whether short- or long-term glycemic fluctuations could induce oxidative stress and chronic inflammation, we evaluated the relationships between glycemic variability, oxidative stress markers, and high-sensitivity C-reactive protein (hs-CRP). We enrolled 34 patients with type 2 diabetes. As a measure of short-term glycemic variability, mean amplitude of glycemic excursions (MAGE) was computed from continuous glucose monitoring system data. For determining long-term glycemic variability, we calculated the standard deviation (SD) of hemoglobin A1c (HbA1c) levels measured over a 2-year period. Levels of oxidative stress markers: 8-iso-prostaglandin F2α (8-iso-PGF2α), thiobarbituric acid-reactive substance (TBARS), 8-hydroxydeoxyguanosine (8-OHdG), and hs-CRP were measured. MAGE was significantly correlated with the SD of HbA1c levels (r = 0.73, p < 0.001) but not with HbA1c level. The levels of hs-CRP, TBARS, 8-OHdG, and 8-iso-PGF2α were significantly correlated with MAGE (r = 0.54, p = 0.001; r = 0.82, p < 0.001; r = 0.70, p < 0.001; r = 0.60, p < 0.001) and the SD of HbA1c levels (r = 0.53, p = 0.001; r = 0.73, p < 0.001; r = 0.69, p < 0.001; r = 0.43, p = 0.01) but not with HbA1c level. Relationships between 8-iso-PGF2α and MAGE or the SD of HbA1c levels remained significant after adjusting for other markers of diabetic control (R(2) = 0.684, R(2) = 0.595, p < 0.001, respectively). Both acute and chronic blood glucose variability can induce oxidative stress and chronic inflammation.

High mobility flexible graphene field-effect transistors with self-healing gate dielectrics.

A high-mobility low-voltage graphene field-effect transistor (FET) array was fabricated on a flexible plastic substrate using high-capacitance natural aluminum oxide as a gate dielectric in a self-aligned device configuration. The high capacitance of the native aluminum oxide and the self-alignment, which minimizes access resistance, yield a high current on/off ratio and an operation voltage below 3 V, along with high electron and hole mobility of 230 and 300 cm(2)/V·s, respectively. Moreover, the native aluminum oxide is resistant to mechanical bending and exhibits self-healing upon electrical breakdown. These results indicate that self-aligned graphene FETs can provide remarkably improved device performance and stability for a range of applications in flexible electronics.