Systemic oxidative stress is implicated in the pathogenesis of brain edema in rats with chronic liver failure

Chronic liver failure leads to hyperammonemia, a central component in the pathogenesis of hepatic encephalopathy (HE); however, a correlation between blood ammonia levels and HE severity remains controversial. It is believed oxidative stress plays a role in modulating the effects of hyperammonemia. This study aimed to determine the relationship between chronic hyperammonemia, oxidative stress, and brain edema (BE) in two rat models of HE: portacaval anastomosis (PCA) and bile-duct ligation (BDL). Ammonia and reactive oxygen species (ROS) levels, BE, oxidant and antioxidant enzyme activities, as well as lipid peroxidation were assessed both systemically and centrally in these two different animal models. Then, the effects of allopurinol (xanthine oxidase inhibitor, 100mg/kg for 10days) on ROS and BE and the temporal resolution of ammonia, ROS, and BE were evaluated only in BDL rats. Similar arterial and cerebrospinal fluid ammonia levels were found in PCA and BDL rats, both significantly higher compared to their respective sham-operated controls (p<0.05). BE was detected in BDL rats (p < 0.05) but not in PCA rats. Evidence of oxidative stress was found systemically but not centrally in BDL rats: increased levels of ROS, increased activity of xanthine oxidase (oxidant enzyme), enhanced oxidative modifications on lipids, as well as decreased antioxidant defense. In PCA rats, a preserved oxidant/antioxidant balance was demonstrated. Treatment with allopurinol in BDL rats attenuated both ROS and BE, suggesting systemic oxidative stress is implicated in the pathogenesis of BE. Analysis of ROS and ammonia temporal resolution in the plasma of BDL rats suggests systemic oxidative stress might be an important "first hit", which, followed by increases in ammonia, leads to BE in chronic liver failure. In conclusion, chronic hyperammonemia and oxidative stress in combination lead to the onset of BE in rats with chronic liver failure.

Esophageal leiomyoma: experience from a single institution

Esophageal leiomyomas are rare. We report the clinicopathologic features of one of the largest series of esophageal leiomyomas from a single institution. We retrospectively reviewed the Cleveland Clinic pathology database (1985-2010) for patients with a diagnosis of esophageal leiomyoma(s). Clinicopathologic features of 30 cases from 28 patients were analyzed. The group included 15 females and 13 males with a mean age at diagnosis of 56 years. These include 9 excisions, 9 esophagectomies, and 12 endoscopic biopsies. Only one partial esophagectomy was performed solely for a symptomatic 14-cm leiomyoma; the remainder of the resections (n= 8) were for other indications, including esophageal cancer (Barrett's esophagus-related adenocarcinoma and squamous cell carcinoma) and emergent esophageal perforation, with leiomyoma being an incidental finding. One patient (2.5%) had two synchronous leiomyomas (14 cm and 0.3 cm). Tumor size ranged from 0.1 to 14 cm (mean = 2.0 cm). Mean tumor size among symptomatic patients was 5.2 cm, as compared with 0.4 cm in asymptomatic patients. Dysphagia was the most common complaint in symptomatic patients (71.4%). Sixty-nine percent of the tumors were located in the distal and middle thirds of the esophagus, with most (69.6%) arising from muscularis propria. Histologically, these tumors were composed of bland spindle cells with low cellularity, no nuclear atypia, or mitotic activity. Only one case (14 cm) showed focal moderate cellularity and nuclear atypia, with low mitotic activity (<1/10 high power field). Immunohistochemical studies showed tumor cells were positive for smooth muscle actin, and negative for CD34 and CD117. Follow-up information was available for 22 patients (78.6%), and none had adverse events related to leiomyoma. In summary, esophageal leiomyoma is a rare benign tumor of the esophagus. Patients with larger tumors were more likely to have symptoms. The majority of the tumors were in the lower and mid-esophagus, and arose from muscularis propria. These tumors behave in a clinically benign fashion.

Reliability test of an electron cyclotron resonance ion source for accelerator driven sub-critical system

The reliability test of an electron cyclotron resonance ion source developed for accelerator driven sub-critical system is carried out in China Institute of Atomic Energy. A unique technique to improve the reliability is adopted. The source is operated for more than 200 h at 75 keV, 100 mA extracted hydrogen current, while 2 beam trips are recorded in the period, and uninterrupted operation time is about 150 h. The experimental result is described.

Sugar phosphorylation activity in ruminal acetogens

Acetogenic bacteria Acetitomaculum ruminis, Acetobacterium woodii, and Eubacterium limosum were compared for phosphoenolpyruvate (PEP) and ATP-dependent phosphorylation of glucose and 2-deoxy-glucose. Rate of phosphorylation activity was measured in toluene-treated acetogenic cells using PEP and ATP and radiolabled glucose or 2-deoxy glucose. Eubacterium limosum, most likely has a glucose phosphotransferase system (PTS). In contrast, A. ruminis, and A. woodii had PEP-dependent glucose phosphorylation rates very similar to control rates, suggesting the lack of PTS activity. These results were confirmed by PEP dependent 2-deoxyglucose phosphorylation data. The rates of ATP-dependent glucose phosphorylation were higher than PEP-dependent glucose dependent in all organisms surveyed. Only E. limosum appeared to have PTS. The presence of PTS in E. limosum could explain why it is not capable of utilizing sugars and H(2)/CO(2) simultaneously and why acetogenesis is not as prominant in the rumen because of the availability of carbohydrates as alternative energy substrates.

Brain-derived neurotrophic factor-activated astrocytes produce mechanical allodynia in neuropathic pain

Neuropathic pain management is challenging for physicians and a vexing problem for basic researchers. Recent studies reveal that activated spinal astrocytes may play a vital role in nerve injury-induced neuropathic pain, although the mechanisms are not fully understood. We have found increased glial fibrillary acidic protein (GFAP) expression, a hallmark of reactive gliosis, and elevated brain-derived neurotrophic factor (BDNF) expression in the dorsal horn in a rat model of allodynia induced by spinal nerve ligation (SNL). The high GFAP expression and mechanical allodynia that SNL induces were prevented by the intrathecal injection of the BDNF-sequestering fusion protein TrkB/Fc. Additionally, mechanical allodynia and GFAP overexpression was induced by the spinal administration of exogenous BDNF to naive rats, and exogenous BDNF given together with fluorocitrate, an astrocytic metabolism inhibitor, inhibited allodynia and GFAP upregulation. Exogenous BDNF also activated the astrocytes directly when tested in vitro. Furthermore, intrathecal administration of BDNF-stimulated astrocytes also induced mechanical allodynia in naive rats. All of these results indicate that astrocytes activated by BDNF might contribute to mechanical allodynia development in neuropathic pain in rats.

Inhibition of Toll-like receptor 4 with vasoactive intestinal peptide attenuates liver ischemia-reperfusion injury

BACKGROUND

Toll-like receptor 4 (TLR4) has attracted a great deal of attention in ischemia-reperfusion (IR) injury in recent years. Vasoactive intestinal peptide (VIP) plays an important role in anti-inflammatory and immunomodulatory activity in several animal models. There are no data available regarding the effect of VIP on TLR4 expression in IR injury in vivo. In the present study, we study the effect of VIP on TLR4 expression in mouse macrophage cell line RAW 264.7 and a mouse partial IR model.

METHODS

The potential inhibitory effect of VIP on TLR4 mRNA and protein in a mouse macrophage cell line and in a mouse model of partial warm hepatic IR injury was assessed. We also assessed the expression tumor necrosis factor (TNF)-α and interleukin (IL)-6 in this model.

RESULTS

Expression of TLR4 mRNA levels was significantly decreased at 6, 12, and 24 hours after treat with VIP in mouse macrophage cell line RAW 264.7. Expression of TLR4 mRNA, TLR4 protein, alanine aminotransferase, TNF-α, and IL-6 levels were significantly increased in the IR group but significantly decreased in groups pretreated with VIP at a concentration of 5 and 10 nmol. Hematoxylin and eosin staining show apparent edema and necrosis were observed in the IR group, but in the VIP pretreatment group, edema and necrosis in IR modes were reduced.

CONCLUSION

This study showed that VIP might inhibit TLR4 in vitro and in vivo, and pretreatment with VIP might inhibited TLR4 activation and reduced warm IR injury.

The detection of 3 leptin receptor isoforms in crucian carp gill and the influence of fasting and hypoxia on their expression

To understand leptin signaling pathway in the crucian carp (Carassius carassius), we cloned 3 leptin receptor isoform complementary DNAs (ie, the long form [cclpr-L], the short form [cclpr-s1], and the secreted form [cclpr-s2]). Variant cclpr-L had a 3,255-bp open reading frame and a complete intracellular domain with box 1 and box 2 consensus sequences. By contrast, cclpr-s1 contained only 4 amino acids in its intracellular domain, without the "box 1" motif, which is conserved among membrane-bound leptin receptor short isoforms in mammals. Variant cclpr-s2 had no transmembrane domain, suggesting that it is a soluble form of the receptor, and alternative splicing of cclpr-s2 mRNA employs a different mechanism for the generation of soluble leptin receptor by intron retention. The fasting-treated fish showed significantly lower cclpr-L mRNA levels in gill tissue than the control group, whereas cclpr-s2 mRNA levels did not vary significantly among the groups. Treatment with hypoxia significantly increased mRNA levels of both cclpr-L and cclpr-s2 in gill tissue. To our knowledge, this is the first study of leptin receptor isoforms expression in teleosts.

Immunogenicity and protective efficacy of a fusion protein vaccine consisting of antigen Ag85B and HspX against Mycobacterium tuberculosis infection in mice

Subunit vaccines have the potential advantage to boost Mycobacterium bovis Bacillus Calmette-Guérin (BCG)-primed immunity in adults. However, most candidates are antigens highly expressed in replicating bacilli but not in dormant or persisting bacilli, which exist during Mycobacterium tuberculosis infection. We constructed M. tuberculosis fusion protein Ag85B-Mpt64(190-198) -HspX (AMH) and Ag85B-Mpt64(190-198) -Mtb8.4 (AMM), which consist of Ag85B, the 190-198 peptide of Mpt64, HspX (Rv2031c) and Mtb8.4 (Rv1174c), respectively. AMH and/or AMM were mixed with adjuvants composed of dimethyl-dioctyldecyl ammonium bromide and BCG polysaccharide nucleic acid (DDA-BCG PSN) to construct subunit vaccines. Mice were immunized thrice with Ag85B, AMH and AMM vaccines and the immunogenicity of the fusion protein vaccines was determined. Then, mice were primed with BCG and boosted twice with Ag85B, AMH, AMM and AMM + AMH vaccines, respectively, followed by challenging with M. tuberculosis virulent strain H37Rv, and the immune responses and protective effects were measured. It was found that mice immunized with AMH vaccine generated high levels of antigen-specific cell-mediated responses. Compared with the group injected only with BCG, the mice boosted with AMM, AMH and AMM + AMH produced higher levels of Ag85B-specific IgG1 and IgG2a and IFN-γ-secreting T cells upon Ag85B and Mycobacterium tuberculosis purified protein derivative (PPD) stimulation. It is interesting that only mice boosted with AMM + AMH had significantly lower bacterial count in the lungs than those receiving BCG, whereas mice boosted with AMH or AMM did not. The results suggest that AMH consisting of HspX, the antigen highly expressed in dormant bacilli, could be combined with antigens from replicating bacilli to enhance BCG primed immunity so as to provide better protection against both growing and non-growing bacteria that occur during the infection process.

CD40-specific costimulation blockade enhances neonatal porcine islet survival in nonhuman primates

The widespread clinical implementation of alloislet transplantation as therapy for type 1 diabetes has been hindered by the lack of suitable islet donors. Pig-to-human islet xenotransplantation is one strategy with potential to alleviate this shortage. Long-term survival of porcine islets has been achieved using CD154-specific antibodies to interrupt the CD40/CD154 costimulation pathway; however, CD154-specific antibodies seem unlikely candidates for clinical translation. An alternative strategy for CD40/CD154 pathway interruption is use of CD40-specific antibodies. Herein, we evaluate the ability of a chimeric CD40-specific monoclonal antibody (Chi220) to protect islet xenografts. Neonatal porcine islets (~50,000 IEQ/kg) were transplanted intraportally into pancreatectomized diabetic macaques. Immunosuppression consisted of induction therapy with Chi220 and the IL-2 receptor-specific antibody basiliximab, and maintenance therapy with sirolimus and the B7-specific fusion protein belatacept. Chi220 effectively promoted xenoislet engraftment and survival, with five of six treated recipients achieving insulin-independent normoglycemia (median rejection-free survival 59 days; mean 90.8 days, maximum 203 days). No thromboembolic phenomena were observed. CD40 represents a promising alternative to CD154 as a therapeutic target, and the efficacy of CD40-specific antibodies in islet xenotransplantation warrants further investigation.

Detection of membrane protein two-dimensional crystals in living cells

It is notoriously difficult to grow membrane protein crystals and solve membrane protein structures. Improved detection and screening of membrane protein crystals are needed. We have shown here that second-order nonlinear optical imaging of chiral crystals based on second harmonic generation can provide sensitive and selective detection of two-dimensional protein crystalline arrays with sufficiently low background to enable crystal detection within the membranes of live cells. The method was validated using bacteriorhodopsin crystals generated in live Halobacterium halobium bacteria and confirmed by electron microscopy from the isolated crystals. Additional studies of alphavirus glycoproteins indicated the presence of localized crystalline domains associated with virus budding from mammalian cells. These results suggest that in vivo crystallization may provide a means for expediting membrane protein structure determination for proteins exhibiting propensities for two-dimensional crystal formation.

39Ar detection at the 10(-16) isotopic abundance level with atom trap trace analysis

Atom trap trace analysis, a laser-based atom counting method, has been applied to analyze atmospheric 39Ar (half-life=269  yr), a cosmogenic isotope with an isotopic abundance of 8×10(-16). In addition to the superior selectivity demonstrated in this work, the counting rate and efficiency of atom trap trace analysis have been improved by 2 orders of magnitude over prior results. The significant applications of this new analytical capability lie in radioisotope dating of ice and water samples and in the development of dark matter detectors.

Influences of Interfacial Properties on High-Performance Concrete Composites

There is a strong motivation to study the interfacial properties of concrete composites because the interfacial region is often the phase where fracture first develops. The aim of this study is to understand phenomena which are unique at high-performance concrete composite interfaces, and how these influence the bulk properties of a concrete composite. Since processes at interfaces must be considered over a range of scales varying from the atomic to the macroscopic, multidisciplinary research approaches are desirable. Model cement/rock (aggregate) and matrix/fiber interaction experiments were carried out. Morphology and microstructure of interfacial regions among mortar/rock, and fiber/matrix were examined utilizing SEM. Computer image analysis performed along a perpendicular to the interface revealed compositional and physical irregularities. The variations in the volume of pores adjacent to interface zones are documented and supported by microscopic observation. The influences of interfacial properties on concrete composite strength and durability are discussed, and influences of fibers on the fracture and fracture resistance behavior are also discussed. Analyses of debonding along interfaces are used to define the role of debonding in fiber-reinforced concrete composites.

Damage Response to Irradiation Temperature and Ion Fluence In C+-Irradiated 6H-SiC

Irradiation experiments have been performed 60° off the surface normal for 6H-SiC single crystals at various temperatures (185-870 K) using 550 keV C+ ions over a fluence range from 1×1018 to 5×109 ions/m2. Atomic disorder on the Si sublattice, as determined by in-situ RBS/channeling analysis, ranged from dilute defects to complete amorphization. The critical amorphization dose of ∼0.23 dpa (on the Si sublattice) at 185 K has been determined. Asymmetric shapes in angular yield profiles across the crystallographic axis <0001> emerged above 1.5×1019 C−/m2 (∼0.05 dpa in the near-surface region), which might be associated with the lattice disturbance in the crystal structure. A gradual decrease in half-angular width was observed with the increase of ion fluence in the experiment. The minimum yield exhibits a rather linear relationship with ion dose at the surface. Post-irradiation annealing at the irradiation temperature did not result in measurable recovery for fluences ranging from 4 × 1018 to 2×1019 C+/m2 at 300, 470 and 670 K. Results also show that low fluence (<8×1018 C+/m2) irradiation at 185 K followed by thermal annealing results in similar defect concentrations to irradiation at that same temperature to the same ion fluence. Thus, at low fluences, the accumulated defects are in thermal equilibrium with the structure.