Serum sulfatide abnormality is associated with increased oxidative stress in hemodialysis patients

Sulfatides are major glycosphingolipids of lipoproteins that influence atherosclerosis and blood coagulation. Our previous cross‐sectional study of hemodialysis patients showed that serum sulfatide levels decreased markedly with increasing duration of hemodialysis treatment, which may contribute to the development of cardiovascular disease. However, this past study could not demonstrate the time‐dependent change in serum sulfatide levels in each patient, and the underlying mechanism is unknown. To confirm the time‐dependent aggravation of serum sulfatide abnormality, 95 stable hemodialysis outpatients were followed up for 3 years. To show the underlying mechanisms, we statistically analyzed correlations between serum sulfatide levels and clinical factors, including an oxidative stress marker, malondialdehyde. Serum sulfatides were quantified by mass spectrometry after conversion to lysosulfatides. Malondialdehyde was measured using a colorimetric assay. The results showed a time‐dependent decrease in serum sulfatide levels associated with increased malondialdehyde levels, although the absolute level of serum malondialdehyde does not determine the baseline level of serum sulfatides. Multiple linear regression analysis showed a significant correlation only between the time‐dependent change in serum sulfatide levels and the time‐dependent change in serum malondialdehyde levels. This study demonstrated, for the first time, a time‐dependent aggravation of serum sulfatide abnormality in hemodialysis patients, as well as the potential relationship between serum sulfatide abnormality and increasing oxidative stress. These findings suggest that oxidative stress might be an aggravating factor in serum sulfatide abnormality. As continuation of hemodialysis treatment hardly improves abnormal serum sulfatide levels or increased oxidative stress, development of novel therapeutic strategies may be important.     

Thermal Behavior of Nitrocellulose with Inorganic Salts and their Mechanistic Action

In this study, we investigated the effects of inorganic salts on the stability of NC and its reaction mechanism. Under isothermal conditions at 120 °C in an O₂ atmosphere, the induction time period for NC heat release was prolonged in the presence of Li₂CO₃, Na₂CO₃, CaCO₃, Mg(OH)₂, Ca(OH)₂, and MgO, all of which produce alkaline saturated solutions with a pH value of 10–12. In addition, the induction time period depended on this pH value. This suggests that these salts stabilized NC by neutralizing acids that would otherwise accelerate the hydrolysis of the O‐NO₂ bond. However, Sr(OH)₂ ⋅ 8H₂O and K₂CO₃, which produce strongly alkaline saturated solutions with pH>13, decreased the induction time period. It is possible that these strong bases caused alkaline decomposition of NC. In addition, for Sr(OH)₂ ⋅ 8H₂O, the released water of crystallization appeared to be related to NC destabilization. SrCO₃, NaHCO₃, K₂SO₄, CaSO₄, ZnSO₄, NaCl, CaCl₂, AgCl, and NaNO₂, which produce near‐neutral saturated solutions, slightly decreased the NC induction time period. The NC induction time period with these salts depended upon the solubility of the added salt. This may indicate that in the presence of these inorganic salts, the boiling point of water is increased, which reduces the vaporization of water from NC and thus accelerates the hydrolysis of NC.     

Thermal conductivity of five normal alkanes in the temperature range 283–373 k at pressures up to 250 MPa

Experimental data on the thermal conductivity of five liquid n-alkanes-hexane, heptane, octane, decane, and dodecane-are presented in the temperature range from 283 to 373 K at pressures up to 250 MPa or the freezing pressures. The measurements were performed on an absolute basis by an automated transient hot-wire apparatus. The uncertainty of the reported data is estimated to be within ±1%. The thermal conductivity of each alkane decreases almost linearly with rising temperature at a constant pressure and increases with increasing pressure at a constant temperature. Both the temperature coefficient of the thermal conductivity ¦(/T) _p¦ and the pressure coefficient (/P) _T decrease with increasing carbon number of alkanes. The experimental results were correlated with temperature and pressure by a similar expression to the Tait equation. It is also found that both the dense hard-sphere model presented by Menashe et al. and the modified significant structure theory proposed by Prabhuram and Saksena provide good representations of the present experimental results.     

Thermomechanical properties of a magnetically and mechanically oriented liquid crystalline copolyester,xydar

Elastic moduli and linear coefficients of thermal expansion (CTE) of a random thermotropic liquid crystalline copolyester, oriented in a magnetic field and by mechanical methods were measured in the directions parallel and perpendicular to the orientation direction. The axial elastic modulus of the magnetically oriented film was lower than that of the uniaxially stretched film. The elastic modulus measured in the transverse direction was higher for the magnetically oriented film. In the axial direction, both the mechanically stretched and magnetically oriented films exhibited shrinkage at low temperatures (CTE ≈ -2 · 10^?5 K^?1) and exhibited expansion at elevated temperatures. In the transverse direction, expansion was observed except for the biaxially stretched film at low temperatures. The magnetically oriented film showed the lowest axial CTE at elevated temperatures.     

Tumor necrosis factor alpha regulates nitric oxide synthase expression in portal hypertensive gastric mucosa of rats

While the clinical features of sclerosing cholangitis secondary to opportunistic infections of the biliary tree in patients with acquired immunodeficiency syndrome (AIDS) are well known, the mechanisms by which microbial pathogens such as Cryptosporidium parvum associated with this syndrome actually cause disease are obscure. We established an in vitro model of biliary cryptosporidiosis employing a human biliary epithelial cell line. Using morphological and biochemical techniques, we examined the interaction of C. parvum with cultured human cholangiocytes. When the apical plasma membrane of polarized, confluent monolayers of human biliary epithelial cells was exposed to C. parvum oocysts that had been excysted in vitro, sporozoites attached to and invaded the cells in a time-, dose-, temperature-, and pH-dependent manner. The infectious process was both plasma membrane domain- and cell-specific, because no attachment or invasion occurred when the basolateral membrane of cholangiocytes was exposed to the parasite, or when a human hepatocyte cell line (HepG2) was used. Time-lapse video microscopy and scanning electron microscopy (SEM) showed that sporozoite attachment was rapid, involved extensive cholangiocyte membrane ruffling, and culminated in parasite penetration into a tight-fitting vacuole formed by invagination of the plasma membrane similar to those found in naturally occurring infection in vivo. Transmission electron microscopy (TEM) showed that C. parvum organisms formed parasitophorus vacuoles and were able to undergo a complete reproductive cycle, forming both asexual and sexual reproductive stages. Unexpectedly, direct cytopathic effects were noted in infected monolayers, with widespread programmed cell death (i.e., apoptosis) of biliary epithelial cells as assessed both morphologically and biochemically beginning within hours after exposure to the organism. The novel finding of specific cytopathic invasion of biliary epithelia by C. parvum may be relevant to the pathogenesis and possible therapy of the secondary sclerosing cholangitis seen in AIDS patients with biliary cryptosporidiosis.     

The Effects of Engineering Modules on Student Learning in Middle School Science Classrooms

The Teachers Integrating Engineering into Science (TIES) Program is a collaborative project among faculty from the College of Education and the College of Engineering at the University of Nevada, Reno. The TIES project paired university faculty with middle school science teachers to create three units that included engineering design using a variety of interactive learning activities in order to engage a wide range of students. The units included a Web‐based simulation activity, lesson plans, a design project, and three types of assessments that were standardized across schools. Results of assessments were disaggregated by gender, ethnicity, special education, and socio‐economic level. Mean scores for these student population groups were compared to mean scores for the same groups on the 2004 Nevada eighth grade science criterion referenced test. These results indicate that engaging students in engineering curriculum activities may diminish achievement gaps in science for some student populations.     

Performance of an unprotected steel structure subjected to repeated fire at a firefighter training facility

An evaluation of a single story unprotected steel structure exposed to repeated fire during the training of fire fighters is described. Temperatures are monitored on the structure using resistance temperature detectors connected to a data acquisition system. Temperatures of up to 384 °C are measured in the steel of the structures, which are below levels likely to cause much degradation in stiffness or strength. Uniform heating of the columns was shown to result in minimal stresses in the structure as the columns were relatively free to deform axially. Differential temperatures, however, where one side of the member is heated by a greater amount than the opposite side of the member, resulted in stresses calculated using an elastic analysis, up to 16 times greater than the yield strength and can thus explain large permanent curvatures observed in the columns. Coupon tests on steel samples from the columns exposed to repeated fire showed some hardening of the steel, possibility attributed to the plastic deformations in the columns, although the ultimate strain in the material was not greatly affected. Based on the monitoring and analysis, no aspects of the structure are considered to present an immediate hazard to the safety of the users. However, without improved cooling, plastic deformation of some members is expected.     

Cyclic response of plate steels under large inelastic strains

In structures subjected to extreme loading, plate steels are relied upon to plastically deform under large repeated strains. Nevertheless, limited data exists on the hysteretic stress-strain response and low-cycle fatigue life of these steels. In the study described in this paper, axial coupons were tested for five types of plate steel, including conventional and high performance A709 steel as well as specialty low yield point steels, to investigate the material response under repeated inelastic demands of constant amplitude between 1% and 7% strain. Parameters for analytical models were established for cyclic stress-strain and low-cycle fatigue life relationships. Based on this study, it was found that the low-cycle fatigue life of the different types of plate steels was similar and that the effect of increased strain rate was minimal. However, the maximum cyclic stress was found to exceed the yield strength by a factor of 2.0 for the conventional grade steel and up to 4.8 times for the low yield point steels, within just a few reversals in the considered strain ranges. The maximum cyclic stress behavior was not related to the yield strength as much as it was to the manufacturing specifications. This behavior should be considered when using these materials in the limit state design of structures for extreme events such as earthquakes.     

A rolled sheet of collagen gel with cultured Schwann cells: Model of nerve conduit to enhance neurite growth

We prepared a rolled sheet of collagen gel with cultured mouse Schwann cells (SCs) as a nerve conduit (a medical device for neurosurgeons to repair an injured peripheral nerve). PC12 cells and dorsal root ganglion (DRG) cells were used as neuronal cells for evaluating the neurite growth-promoting activity of the device. As a control, we compared the rolled device with a rod device. Those neuronal cells inoculated at the terminal part of the rolled device migrated into the central part along the inter-layer space of the collagen gel layer, and then differentiated into neurons, extending many neurites for 3–12 days in culture. Significantly, this migration of neuronal cells into the device and their subsequent neurite growth was not observed in the absence of the SCs. We conclude that our rolled sheet of collagen gel with SCs was well designed and very effective to promote neurite growth, and is a promising candidate for the nerve conduit.     

Seismic Behavior of Steel Girder Bridge Superstructures

Recent earthquakes exposed the vulnerabilities of steel plate girder bridges when subjected to ground shaking. This paper discusses the behavior of steel plate girder bridges during recent earthquakes such as Petrolia, Northridge, and Kobe. The paper also discusses the recent experimental and analytical investigations that were conducted on steel plate girder bridges and their components. Results of these investigations showed the importance of shear connectors in distributing and transferring the lateral forces to the end and intermediate cross frames. Also, these investigations showed the potential of using end cross frames as ductile elements that can be used to dissipate the earthquake input energy. The paper also gives an update on specifications and guidelines for the seismic design of steel plate girder bridges in the United States.