AIM: To study the computed tomography (CT) signs in facilitating early diagnosis of necrotic stercoral colitis (NSC).

METHODS: Ten patients with surgically and pathologically confirmed NSC were recruited from the Clinico-Pathologic-Radiologic conference at Chang Gung Memorial Hospital, Taoyuan, Taiwan. Their CT images and medical records were reviewed retrospectively to correlate CT findings with clinical presentation.

RESULTS: All these ten elderly patients with a mean age of 77.1 years presented with acute abdomen at our Emergency Room. Nine of them were with systemic medical disease and 8 with chronic constipation. Seven were with leukocytosis, two with low-grade fever, two with peritoneal sign, and three with hypotensive shock. Only one patient was with radiographic detected abnormal gas. Except the crux of fecal impaction, the frequency of the CT signs of NSC were, proximal colon dilatation (20%), colon wall thickening (60%), dense mucosa (62.5%), mucosal sloughing (10%), perfusion defect (70%), pericolonic stranding (80%), abnormal gas (50%) with pneumo-mesocolon (40%) in them, pericolonic abscess (20%). The most sensitive signs in decreasing order were pericolonic stranding, perfusion defect, dense mucosal, detecting about 80%, 70%, and 62.5% of the cases, respectively.

CONCLUSION: Awareness of NSC and familiarity with the CT diagnostic signs enable the differential diagnosis between NSC and benign stool impaction.

Background

Traumatic brain injury (TBI) initiates a neuroinflammatory cascade that contributes to neuronal damage and behavioral impairment. This study was undertaken to investigate the effects of wogonin, a flavonoid with potent anti-inflammatory properties, on functional and histological outcomes, brain edema, and toll-like receptor 4 (TLR4)- and nuclear factor kappa B (NF-κB)-related signaling pathways in mice following TBI.

Methodology/Principal Findings

Mice subjected to controlled cortical impact injury were injected with wogonin (20, 40, or 50 mg·kg−1) or vehicle 10 min after injury. Behavioral studies, histology analysis, and measurement of blood-brain barrier (BBB) permeability and brain water content were carried out to assess the effects of wogonin. Levels of TLR4/NF-κB-related inflammatory mediators were also examined. Treatment with 40 mg·kg−1 wogonin significantly improved functional recovery and reduced contusion volumes up to post-injury day 28. Wogonin also significantly reduced neuronal death, BBB permeability, and brain edema beginning at day 1. These changes were associated with a marked reduction in leukocyte infiltration, microglial activation, TLR4 expression, NF-κB translocation to nucleus and its DNA binding activity, matrix metalloproteinase-9 activity, and expression of inflammatory mediators, including interleukin-1β, interleukin-6, macrophage inflammatory protein-2, and cyclooxygenase-2.

Conclusions/Significance

Our results show that post-injury wogonin treatment improved long-term functional and histological outcomes, reduced brain edema, and attenuated the TLR4/NF-κB-mediated inflammatory response in mouse TBI. The neuroprotective effects of wogonin may be related to modulation of the TLR4/NF-κB signaling pathway.

Microbial fuel cells (MFCs) represent a novel technology for wastewater treatment with electricity production. Electricity generation with simultaneous nitrate reduction in a single-chamber MFC without air cathode was studied, using glucose (1 mM) as the carbon source and nitrate (1 mM) as the final electron acceptor employed by Bacillus subtilis under anaerobic conditions. Increasing current as a function of decreased nitrate concentration and an increase in biomass were observed with a maximum current of 0.4 mA obtained at an external resistance (Rext) of 1 KΩ without a platinum catalyst of air cathode. A decreased current with complete nitrate reduction, with further recovery of the current immediately after nitrate addition, indicated the dependence of B. subtilis on nitrate as an electron acceptor to efficiently produce electricity. A power density of 0.0019 mW/cm2 was achieved at an Rext of 220 Ω. Cyclic voltammograms (CV) showed direct electron transfer with the involvement of mediators in the MFC. The low coulombic efficiency (CE) of 11% was mainly attributed to glucose fermentation. These results demonstrated that electricity generation is possible from wastewater containing nitrate, and this represents an alternative technology for the cost-effective and environmentally benign treatment of wastewater.

Since the development of the polymerase chain reaction (PCR) technique, genomic information has been retrievable from lesser amounts of DNA than previously possible. PCR-based amplifications require high-precision instruments to perform temperature cycling reactions; further, they are cumbersome for routine clinical use. However, the use of isothermal approaches can eliminate many complications associated with thermocycling. The application of diagnostic devices for isothermal DNA amplification has recently been studied extensively. In this paper, we describe the basic concepts of several isothermal amplification approaches and review recent progress in diagnostic device development.

The alternative transcription factor σB is responsible for transcription in Staphylococcus aureus during the stress response. Many virulence-associated genes are directly or indirectly regulated by σB. We hypothesized that treatment with antibiotics may act as an environmental stressor that induces σB activity in antibiotic-resistant strains. Several antibiotics with distinct modes of action, including ampicillin (12 µg/ml), vancomycin (16 or 32 µg/ml), chloramphenicol (15 µg/ml), ciprofloxacin (0.25 µg/ml), and sulfamethoxazole/trimethoprim (SXT, 0.8 µg/ml), were investigated for their ability to activate this transcription factor. We were especially interested in the stress response in vancomycin-resistant S. aureus (VRSA) strains treated with vancomycin. The transcription levels of selected genes associated with virulence were also measured. Real-time quantitative reverse transcription PCR was employed to evaluate gene transcription levels. Contact hemolytic and cytotoxicity assays were used to evaluate cell damage following antibiotic treatment. Antibiotics that target the cell wall (vancomycin and ampicillin) and SXT induced σB activity in VRSA strains. Expression of σB-regulated virulence genes, including hla and fnbA, was associated with the vancomycin-induced σB activity in VRSA strains and the increase in cytotoxicity upon vancomycin treatment. These effects were not observed in the sigB-deficient strain but were observed in the complemented strain. We demonstrate that sub-minimum inhibitory concentration (sub-MIC) levels of antibiotics act as environmental stressors and activate the stress response sigma factor, σB. The improper use of antibiotics may alter the expression of virulence factors through the activation of σB in drug-resistant strains of S. aureus and lead to worse clinical outcomes.

In this study the “green chemistry” use of the biosurfactant surfactin for the synthesis of calcium phosphate using the reverse microemulsion technique was demonstrated. Calcium phosphates are bioactive materials that are a major constituent of human teeth and bone tissue. A reverse microemulsion technique with surfactin was used to produce nanocrystalline brushite particles. Structural diversity (analyzed by SEM and TEM) resulted from different water to surfactin ratios (W/S; 250, 500, 1000 and 40,000). The particle sizes were found to be in the 16–200 nm range. Morphological variety was observed in the as-synthesized microemulsions, which consisted of nanospheres (~16 nm in diameter) and needle-like (8–14 nm in diameter and 80–100 nm in length) noncalcinated particles. However, the calcinated products included nanospheres (50–200 nm in diameter), oval (~300 nm in diameter) and nanorod (200–400 nm in length) particles. FTIR and XRD analysis confirmed the formation of brushite nanoparticles in the as-synthesized products, while calcium pyrophosphate was produced after calcination. These results indicate that the reverse microemulsion technique using surfactin is a green process suitable for the synthesis of nanoparticles.

The separation of mercury ions from artificially contaminated water by the foam fractionation process using a biosurfactant (surfactin) and chemical surfactants (SDS and Tween-80) was investigated in this study. Parameters such as surfactant and mercury concentration, pH, foam volume, and digestion time were varied and their effects on the efficiency of mercury removal were investigated. The recovery efficiency of mercury ions was highly sensitive to the concentration of the surfactant. The highest mercury ion recovery by surfactin was obtained using a surfactin concentration of 10 × CMC, while recovery using SDS required < 10 × CMC and Tween-80 >10 × CMC. However, the enrichment of mercury ions in the foam was superior with surfactin, the mercury enrichment value corresponding to the highest metal recovery (10.4%) by surfactin being 1.53. Dilute solutions (2-mg L−1 Hg2+) resulted in better separation (36.4%), while concentrated solutions (100 mg L−1) enabled only a 2.3% recovery using surfactin. An increase in the digestion time of the metal solution with surfactin yielded better separation as compared with a freshly-prepared solution, and an increase in the airflow rate increased bubble production, resulting in higher metal recovery but low enrichment. Basic solutions yielded higher mercury separation as compared with acidic solutions due to the precipitation of surfactin under acidic conditions.

The function of orf4 in the sigB cluster in Bacillus cereus ATCC 14579 remains to be explored. Amino-acid sequence analysis has revealed that Orf4 is homologous with bacterioferritins and Dps. In this study, we generated an orf4-null mutant and produced recombinant protein rOrf4 to establish the role of orf4. In vitro, the purified rOrf4 was found to exist in two distinct forms, a dimeric form and a polymer form, through size exclusion analysis. The latter form exhibited a unique filament structure, in contrast to the typical spherical tetracosamer structure of bacterioferritins; the former can be induced to form rOrf4 polymers immediately after the addition of FeCl2. Catalysis of the oxidation of ferrous irons by ferroxidase activity was detected with rOrf4, and the mineralized irons were subsequently sequestered only in the rOrf4 polymer. Moreover, rOrf4 exerted DNA-protective activity against oxidative damage via DNA binding in a nonspecific manner, as is seen with Dps. In vivo, deletion of orf4 had no effect on activation of the alternative sigma factor σB, and therefore, orf4 is not associated with σB regulation; however, orf4 can be significantly upregulated upon environmental stress but not H2O2 treatment. B. cereus strains with constitutive Orf4 expression exhibited a viability higher than that of the orf4-null mutant, under specific oxidative stress or heat shock. Taken together, these results suggest that Orf4 functions as a Dps-like bacterioferritin in response to environmental stress and can provide cell protection from oxidative damage through iron sequestration and DNA binding.

Bacillus subtilis has developed an intricate signal transduction cascade to respond to the imposition of a variety of stresses on the cell. Reversible protein phosphorylation and the formation of alternative protein-protein complexes modulate the activity of σB, the RNA polymerase sigma factor subunit responsible for the transcription of the general stress response genes. Some of the regulators of σB, such as RsbR and RsbS, are known to associate in a 25S complex, called the stressosome, that can bind RsbT until RsbT phosphorylates target residues in RsbR and RsbS. To date, the RsbR-RsbS complex appears to be the most upstream component of the σB regulatory pathway. This large structure is thought to play an important role in sensing and/or integrating signals from different physical stresses. The roles of the paralogues of RsbR that are found in B. subtilis remain unclear. We describe here how the RsbR paralogues copurify with RsbR from B. subtilis cell lysates, and we demonstrate in vitro that the paralogues form large complexes either with RsbS or with a prepurified RsbR-RsbS binary complex. We conclude from these biochemical studies that stressosomes in B. subtilis cells contain minimally RsbS and all of the RsbT-phosphorylatable RsbR paralogues.

In the pathway that controls σB activity, the RsbR-RsbS complex plays an important role by trapping RsbT, a positive regulator of σB of Bacillus subtilis. We have proposed that at the onset of stress, RsbR becomes phosphorylated, resulting in an enhanced activity of RsbT towards RsbS. RsbT is then free to interact with and activate RsbU, which in turn ultimately activates σB. In this study with purified proteins, we used mutant RsbR proteins to analyze the role of its phosphorylatable threonine residues. The results show that the phosphorylation of either of the two RsbT-phosphorylatable threonine residues (T171 and T205) in RsbR enhanced the kinase activity of RsbT towards RsbS. However, it appeared that RsbT preferentially phosphorylates T171. We also present in vitro evidence that identifies RsbX as a potential phosphatase for RsbR T205.

Background

Traumatic brain injury (TBI) induces a complex sequence of apopototic cascades that contribute to secondary tissue damage. The aim of this study was to investigate the effects of salidroside, a phenolic glycoside with potent anti-apoptotic properties, on behavioral and histological outcomes, brain edema, and apoptosis following experimental TBI and the possible involvement of the phosphoinositide 3-kinase/protein kinase B (PI3K)/Akt signaling pathway.

Methodology/Principal Findings

Mice subjected to controlled cortical impact injury received intraperitoneal salidroside (20, or 50 mg/kg) or vehicle injection 10 min after injury. Behavioral studies, histology analysis and brain water content assessment were performed. Levels of PI3K/Akt signaling-related molecules, apoptosis-related proteins, cytochrome C (CytoC), and Smac/DIABLO were also analyzed. LY294002, a PI3K inhibitor, was administered to examine the mechanism of protection. The protective effect of salidroside was also investigated in primary cultured neurons subjected to stretch injury. Treatment with 20 mg/kg salidroside_significantly improved functional recovery and reduced brain tissue damage up to post-injury day 28. Salidroside_also significantly reduced neuronal death, apoptosis, and brain edema at day 1. These changes were associated with significant decreases in cleaved caspase-3, CytoC, and Smac/DIABLO at days 1 and 3. Salidroside increased phosphorylation of Akt on Ser473 and the mitochondrial Bcl-2/Bax ratio at day 1, and enhanced phosphorylation of Akt on Thr308 at day 3. This beneficial effect was abolished by pre-injection of LY294002. Moreover, delayed administration of salidroside at 3 or 6 h post-injury reduced neuronal damage at day 1. Salidroside treatment also decreased neuronal vulnerability to stretch-induced injury in vitro.

Conclusions/Significance

Post-injury salidroside improved long-term behavioral and histological outcomes and reduced brain edema and apoptosis following TBI, at least partially via the PI3K/Akt signaling pathway.