Disulfide bond assignment in human interleukin-7 by matrix-assisted laser desorption/ionization mass spectroscopy and site-directed cysteine to serine mutational analysis

Interleukin-7 (IL-7) is a proteinaceous biological response modifier that has a bioactive tertiary structure dependent on disulfide bond formation. Disulfide bond assignments in human (h)IL-7 are based upon the results of matrix-assisted laser desorption/ionization (MALDI) mass spectroscopy and Cys to Ser mutational analyses. A gene encoding the hIL-7 was synthesized incorporating Escherichia coli codon usage bias and was used to express biologically active protein as determined by stimulation of precursor B-cell proliferation. MALDI mass spectroscopic analysis of trypsin-digested hIL-7 was performed and compared with the anticipated results of a simulated tryptic digestion. Many of the anticipated hIL-7 tryptic fragments were detected including one with a molecular mass equivalent to the sum of two polypeptides linked through a disulfide bond formed from Cys residues (Cys3 and Cys142). Subsequently, Cys to Ser substitution mutational analyses were performed. A hIL-7 variant with all six Cys substituted with Ser was found to be biologically inactive (EC50 > 1 x 10(-7) M). In contrast, a family of single disulfide bond-forming variants of hIL-7 were constructed by reintroducing Cys pairs (Cys3-Cys142, Cys35-Cys130, and Cys48-Cys93), and each could stimulate cell proliferation with an EC50 of 4 x 10(-9), 2 x 10(-8), and 2 x 10(-9) M, respectively. In single disulfide bond-forming mutants of hIL-7, the ability to stimulate cell proliferation was abolished in the presence of 2 mM dithiothreitol. The results presented strongly suggest that only a single disulfide bond is required for hIL-7 to form a tertiary structure capable of stimulating precursor B-cell proliferation.     

Nanoindentation Characterization of Submicro- and Nano-Sized Liquid-Phase-Sintered SiC Ceramics

Submicro- and nano-sized liquid-phase-sintered SiC ceramics were mechanically tested by nanoindentation in the peak load range 5–400 mN. The submicro-sized sample showed a marked indentation size effect which the nano-sized samples did not exhibit. The relevance of indentation depth with respect to the microstructural scale has been outlined. In the investigated grain-size range, the hardness dependence on the grain size could be described by a load-dependent inverse Hall–Petch relation. Young's modulus was less microstructure- and load-dependent. Because of the very fine microstructure, the nano-sized SiC materials gave lower elastic values than the submicro-sized SiC ceramic.     

High-Temperature Stiffness and Damping Measurements to Monitor the Glassy Intergranular Phase in Liquid-Phase-Sintered Silicon Carbides

Detailed stiffness and internal friction ( Q ⁻¹) versus temperature curves were obtained for liquid-phase-sintered silicon carbides using advanced resonant beam analysis up to 1400°C. As-sintered materials display a stable Q ⁻¹-peak near 1100°C, superimposed on an increasing background. The change of stiffness associated with the damping peak is quantitatively related to the amount of matter in pockets of the amorphous intergranular phase in which the refractory SiC matrix grains are embedded. The successful removal of the amorphous pockets by annealing at 1900°C is deduced from the disappearance of the damping peak and confirmed with transmission electron microscopy.     

X-ray crystal structure of the dye 2-cyano-4-bromo-4′-N,N-diethylaminoazobenzene

The crystal structure and molecular conformation of 2-cyano-4-bromo-4′-N,N-diethylaminoazobenzene (C₁₇H₁₇N₄Br, mol. wt. = 357·2 a.m.u) has been determined from X-ray diffraction data; triclinic, P$\text{1}$ (No. 2), a = 10·132(11) Å, b = 12·216(16) Å, c = 6·966(11) Å, α = 104·21(9)°, β = 92·67(12)°, γ = 97·22(7)°, V = 826·5(9) ų, Z = 2, D_c = 1·436 g cm^?3, F(000) = 378, λ(MoKα) = 0·71069 Å, μ(MoKα) = 26·0 cm^?1. The structure was solved by the multiple solution direct method and refined by full-matrix least-squares to R = 0·059 for 1538 independent observed reflections. The azobenzene skeleton is planar to within 0·06 Å. Most significant bonding data are: NN, 1·290(8) Å; BrC, 1·866(6) Å; mean CN (azo) 1·380(8) Å; NNC, 113·6(4) and 115·3(4)°; NCC (cis relative to NN) 125·9(4)° and 126·7(4)°; NCC (trans) 116·8°(5)° and 116·1(4)°.     

Ultimate behavior of axially loaded RC wall-like columns confined with GFRP

The assessment of the effectiveness of the fiber reinforced polymer (FRP) confinement on rectangular reinforced concrete (RC) columns with high aspect ratio (wall-like) still represents an unresolved issue. The present paper aims at providing more experimental evidence about the behavior of such members confined with both uni-directional and quadri-directional glass FRP laminates. Particular attention is devoted to issues related to the premature failure of confining fibers experimentally observed in wall-like columns. Test results on nine axially loaded columns are herein presented; emphasis is also given to the analysis of FRP strain profiles along the sides of the cross-section. The analysis of test results highlights that glass FRP (GFRP) confinement could determine significant strength and ductility increases; the discussion of failure modes points out that the failure of GFRP confined wall-like columns is controlled by the shape of the cross-section and occurs at transverse strains in the jacket much lower than those ultimate of the fibers. Theoretical–experimental comparisons are performed using some available models for strength prediction of such members.     

Non-invasive monitoring of water content and textural changes in clay-rocks using spectral induced polarization: A laboratory investigation

Seven well-characterized clay-rocks have been taken from three test sites to perform spectral induced polarization (SIP) measurements during desiccation of these samples. These test sites include (1) the Tournemire site (IRSN) located in south of France, (2) The Bure test site (ANDRA) located in west of France, and (3) the Super-Sauze earthflow located in south western of France. We dried the samples at ambient temperature followed by heating between 65 °C and 105 °C. The quadrature conductivity, at very low-frequency, was able to discriminate between the loss of free water from the macropores and the loss of water in the micropores associated with textural changes. The calcite and quartz grain size distributions had a significant effect on the low-frequency spectrum. The inversion of our SIP data demonstrated that the generalized Cole–Cole model is an appropriate empirical and practical model for monitoring changes in water content of clay-rocks.     

Mesenteric vein thrombosis: a rare cause of abdominal pain in cirrhotic patients--two case reports

Mesenteric vein thrombosis is a rare disorder which can develop rapidly with intestinal infarction or subacutely with abdominal pain due to intestinal ischemia. Despite the availability of modern diagnostic tools, which allow an early diagnosis in most cases, the mortality from this disease has not significantly diminished over the years. The problem is that the syndrome is rare and unusual and the clinical presentation is usually vague or confusing. Particularly in cirrhotic patients, this diagnosis requires the exclusion of several other complications of liver disease, like spontaneous bacterial peritonitis, tense ascites or portal thrombosis. Here, we report the occurrence of acute mesenteric vein thrombosis in two patients with liver cirrhosis. Severe subcontinuous abdominal pain out of proportion to the physical findings and abdominal distension were the major symptoms in both patients. Magnetic resonance imaging in one case and ultrasound scan with color Doppler followed by computed tomography in the other patient confirmed the diagnosis and enabled an appropriate early therapy to be undertaken.