Expression of matrix metalloproteinases and their inhibitors in aneurysms and normal aorta

BACKGROUND: Abdominal aortic aneurysms (AAAs) are characterized by degradation of collagen and elastin resulting from increases in matrix metalloproteinase (MMP) activity. Previous authors have identified isolated increases in expression of specific MMPs in AAAs, but none have compared relative levels of expression of particular MMPs to one another or to those of their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). This study proposes to quantify relative mRNA levels for interstitial collagenase (MMP-1), 72 kd type IV collagenase (MMP-2), 92 kd type IV collagenase (MMP-9), TIMP-1, and TIMP-2 in normal aorta (NA) and AAA to provide insight as to the relative importance of each in aneurysm formation. METHODS: Competitive polymerase chain reactions (PCRs) with gene-specific external standards and cDNA derived from AAAs (n = 8; mean age, 67.4 years) and NA (n = 5; mean age, 40.6 years) were used to quantify mRNA levels. Results were normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels, determined by means of competitive PCR, and compared by means of Mann-Whitney statistics. RESULTS: Significant increases in MMP mRNA expression in AAA over NA were observed for MMP-1 (3.64 versus 0.3, p = 0.007), MMP-9 (78.03 versus 3.35, p = 0.003), TIMP-1 (835.32 versus 477.2, p = 0.027), and TIMP-2 (18.09 versus 4.14, p = 0.003). The ratio of MMP to TIMP mRNA levels was higher in AAA than NA (0.135 versus 0.045, p = 0.018). CONCLUSIONS: Increases in expression of MMP-1, MMP-9, and MMP/TIMP ratios may result in increased proteolysis and matrix degradation, which characterize AAAs. MMP-9 appears to be the predominant metalloproteinase expressed in AAA, because its mRNA levels were more than 20 times and 2 times higher than those of MMP-1 and MMP-2, respectively. TIMP-1 mRNA levels were in molar excess to those of any of the metalloproteinases studied.     

Nanoindentation mapping of mechanical properties of cement paste and natural rocks

This paper reports a study to assess nanoindentation mapping of mechanical properties of cement paste and natural rocks. Initial work seems to show that mechanical property mapping by nanoindentation is feasible and can be related to microscopic information. Further work is however required on the effect of indent size and spacing. Such a testing technique can be very useful for materials with different phases to study the intrinsic properties of each component, and also the interaction and properties of the interfacial regions of different phases. The values of Young's modulus and hardness of the individual mineral phases were also determined by statistically analysing a large number of experimental data.     

A comparison of the dissolution of model compounds and the kerogen of Green River oil shale by oxidation with perchloric acid — A model for the kerogen of Green River oil shale

A stepwise degradation of a kerogen concentrate of Green River oil shale was effected by oxidation with perchloric acid of varying boiling point and concentration. Dissolution of the kerogen concentrate occurred between 160 and 170°C. Several model compounds were also oxidized with perchloric acid. The model compounds were polyethylene, graphite, nylon, and polyethylene oxide. The results indicated that the kerogen was similar to polyethylene oxide. The results of this study and previous work were used to present a model for the structure of the kerogen of Green River oil shale.     

Dentine hypersensitivity: a clinical trial to compare 2 strontium densensitizing toothpastes with a conventional fluoride toothpaste

Sixty-nine patients, aged 63-98 years and admitted at the Geneva Geriatric Hospital, were included in the present retrospective study. They received clomipramine orally, 50 or 75 mg/day. Blood concentrations of clomipramine were measured as part of a routine drug monitoring program. Comparison with a reference population of patients aged < or = 65 years indicated that elderly patients with concomitant somatic diseases reach higher dose-normalized concentrations of clomipramine and increased parent drug to demethylated metabolite ratios, as a consequence of impaired demethylation (approximately 50%) and hydroxylation (approximately 25%). Sixty-five percent of patients showed clinical improvement, with a maximum rate of satisfactory response observed in major depression. Severe side effects, such as symptomatic hypotension or confusion, were seen in 20% of patients. Because of 10- and 15-fold interindividual variations in the concentrations of clomipramine and its metabolite, respectively, therapeutic drug monitoring can provide valuable assistance to clinical judgment in individual dose adjustment for patients whose old age, associated somatic diseases, and comedication necessitate additional precautions.     

Activation energies for the deformation of superplastic alloys and their phases derived from hot microhardness studies

Activation energies for two superplastic alloys (Zn78-AI22 and Cu60-Zn4O) and their individual phases have been determined by plottingH/E againstT _m/T and utilizing the relationshipH/E = G exp (Q/nRT). Hot hardness measurements were made with a microhardness tester and Young's modulus values were obtained over the appropriate temperature range using the Rayleigh vibration technique. The activation energies obtained are compared, wherever possible, with those reported in the literature and are found to be in reasonably good agreement. These data help in the understanding of the mechanisms of superplasticity in these alloys.     

Use of electron microscopy on microstructure characterization of high chromium cast irons

The physical metallurgy underlying the development of cast microstructures in abrasion resistant high chromium cast irons, and their structural modification by thermal treatments is relatively complex. Structural characterisation via electron microscopy therefore has a key role to play in furthering our understanding of the phase transformations that control the microstructures and hence the service performances of these irons as wear parts. This paper shows how both scanning and especially transmission electron microscopy can provide valuable information on the nature of eutectic and secondary carbides and on the matrix structures in these irons. Particular attention is given to current characterisation research on conventionally cast 30%Cr irons that are used for applications involving corrosive wear e.g. slurry pumps and on a semi-solid cast 27%Cr iron that has a potential for applications in industry.     

New epoxy resins. I. The stability of epoxy–trialkoxyboroxines triaryloxyboroxine system

A polymer with high aromaticity and/or cyclic ring structures chain backbone usually has high heat, thermal, and flame resistance. Two diglycidyl ethers of bisphenols were prepared from 4,4′ isopropylidenediphenol (DGEBA) and 9,9-bis(4-hydroxyphenyl) fluorene (DGEBF) for evaluation. Four boroxines—trimethoxyboroxine (TMB), triethoxyboroxine (TEB), triisopropoxyboroxine (TIPB) and triphenoxyboroxine (TPB)—were used as the curing agents. DGEBA and DGEBF cured with various boroxines indicate that the trend for their respective glass transition temperature (T_g's), degradation temperatures (T_d's), and gel fractions are TMB-cured epoxy ≈ TEB-cured epoxy < TIPB cured epoxy < TPB cured epoxy. The DGEBF system usually has a higher T_g, T_d, gel fraction, oxygen index (OI), and char yield than the related DGEBA system. DGEBF/DGEBA (80/20 mol ratio) shows a synergistic effect in regard to char formation. This effect exists not only in the copolymer system but also in blended homopolymers of the separately cured resins. A modified mechanism for the polymerization of phenyl glycidyl ether (PGE) with TMB has been proposed.