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91.
MH Mullerworth P Angelopoulos MA Couyant AM Horton SM Robinson OU Petring PJ Mitchell JJ Presneill 《Canadian Metallurgical Quarterly》1998,66(4):1242-1245
The use of PCR to amplify a specific virA gene fragment serves as a highly specific and sensitive method to detect virulent bacteria of the genus Shigella and enteroinvasive Escherichia coli. Amplification of a 215-bp DNA band was obtained by using isolated genomic DNA of Shigella, individual cells of Shigella dysenteriae, and mayonnaise contaminated with S. dysenteriae. Moreover, a multiplex PCR with specific (virA) and bacterium-restricted (16S ribosomal DNA) primers generated an amplification product of approximately 755 bp for all bacteria tested and an additional 215-bp product for Shigella and enteroinvasive E. coli. 相似文献
92.
PJ Johnson SC Tyagi LC Katwa VK Ganjam LA Moore JM Kreeger NT Messer 《Canadian Metallurgical Quarterly》1998,142(15):392-396
Samples of connective tissue obtained from the hoof of six laminitic and eight non-laminitic adult horses were analysed zymographically to investigate whether connective tissue matrix metalloproteinases are activated or induced during laminitis. The activity or matrix metalloproteinases was substantially greater in the tissues from the laminitic horses than in the tissues from the non-laminitic horses. A comparison of the collagenolytic activity in the laminitic and control tissues showed that collagenolytic activities corresponding to the 92 kDa (P < 0.001), 72 kDa (P < 0.01) and 66 kDa (P < 0.01) bands were induced in the laminitic tissues. 相似文献
93.
CR Dudley B Keavney IM Stratton RC Turner PJ Ratcliffe 《Canadian Metallurgical Quarterly》1995,48(6):1907-1911
We performed a case-control study to determine whether molecular variants of genes of the renin-angiotensin system were associated with the presence of albuminuria in non-insulin dependent diabetes mellitus (NIDDM). A total of 180 diabetic patients with persistent microalbuminuria [median urinary albumin (interquartile range) of 74 (54 to 126 mg/liter)] were matched with two control groups of diabetic patients without microalbuminuria [median urinary albumin 7 (5 to 10) mg/liter] for variables known to be associated with raised urinary albumin concentration including hemoglobin A1c and triglyceride. One control group was also matched for blood pressure and the other group was not, to allow assessment of interactions with hypertension. Association with the I/D polymorphism of the ACE gene and M235T variant of the angiotensinogen gene (AGT) with microalbuminuria and retinopathy was examined. There were no significant differences in genotype frequency between cases and controls for ACE or AGT irrespective of blood pressure matching. However, among subjects with microalbuminuria, those with the ACE DD genotype had a significantly greater urinary albumin excretion than individuals with a non-DD genotype [median 88 (68 to 170) mg/liter vs. 67 (53 to 113) mg/liter, P < 0.001]. More subjects with the DD than non-DD genotype had persistent albuminuria > 100 mg/liter, twice the upper normal range (60% vs. 38%, P = 0.006). When increased albumin excretion occurs, the presence of the ACE DD genotype appears to be associated with higher urinary albumin levels. No association with retinopathy was observed. 相似文献
94.
Influenza caused low levels of mortality and morbidity in England and Wales in the 1997/98 season. Influenza viruses of the H3N2 and H1N1 subtypes were isolated in small numbers from community and hospital patients in November and December. Their numbers subsequently increased to peak in February, H1N1 a week or two before H3N2. Most of the H1N1 isolates were similar to the A/Bayern/7/95-like virus, included in the vaccine recommended for 1997-98, whereas most H3N2 isolates were A/Sydney/5/97-like, a virus not covered by the season's vaccine but recommended for 1998/99. Consultation rates in general practice for influenza-like illnesses remained low until early February, when a small increase coincided with the increase in laboratory confirmed influenza. Fewer deaths directly attributed to influenza were registered during the surveillance period than in recent years. Localised outbreaks occurred in schools and nursing homes towards the end of the winter. 相似文献
95.
LS Melchers M Apotheker-de Groot JA van der Knaap AS Ponstein MB Sela-Buurlage JF Bol BJ Cornelissen PJ van den Elzen HJ Linthorst 《Canadian Metallurgical Quarterly》1994,5(4):469-480
A novel chitinase gene of tobacco was isolated and characterized by DNA sequence analysis of a genomic clone and a cDNA clone. Comparative sequence analysis of both clones showed an identity of 94%. The proteins encoded by these sequences do not correspond to any of the previously characterized plant chitinases of classes I-IV and are designated as class V chitinases. Comparison of the chitinase class V peptide sequence with sequences in the Swiss Protein databank revealed significant sequence similarity with bacterial exo-chitinases from Bacillus circulans, Serratia marcescens and Streptomyces plicatus. It was demonstrated that class V chitinase gene expression is induced after treatment of tobacco with different forms of stress, like TMV-infection, ethylene treatment, wounding or ultraviolet irradiation. Two related chitinase class V proteins of 41 and 43 kDa were purified from Samsun NN tobacco leaves inoculated with tobacco mosaic virus. The proteins were purified by Chelating Superose chromatography and gel filtration. In vitro assays demonstrated that class V chitinases have endo-chitinase activity and exhibit antifungal activity toward Trichoderma viride and Alternaria radicina. In addition, it was shown that class V chitinase acts synergistically with tobacco class I beta-1,3-glucanase against Fusarium solani germlings. 相似文献
96.
N-methyl-D-aspartate (NMDA) glutamate receptors mediate critical components of cardiorespiratory control in anesthetized animals. The role of NMDA receptors in the ventilatory responses to peripheral and central chemoreceptor stimulation was investigated in conscious, freely behaving rats. Minute ventilation (VE) responses to 10% O2, 5% CO2, and increasing intravenous doses of sodium cyanide were measured in intact rats before and after intravenous administration of the NMDA receptor antagonist MK-801 (3 mg/kg). After MK-801, eupcapnic tidal volume (VT) decreased while frequency increased, resulting in a modest reduction in VE. Inspiratory time (TI) decreased, whereas expiratory time remained unchanged. The VE responses to hypercapnia were qualitatively similar in control and MK-801 conditions, with slight reductions in respiratory drive (VT/TI) after MK-801. In contrast, responses to hypoxia were markedly attenuated after MK-801 and were primarily due to reduced frequency changes, whereas VT was unaffected. Sodium cyanide doses associated with significant VE increases were 5 and 50 microg/kg before and after MK-801, respectively. Thus 1-log shift to the right of individual dose-response curves occurred with MK-801. Selective carotid body denervation reduced VE during hypoxia by 70%, and residual hypoxic ventilatory responses were abolished after MK-801. These findings suggest that, in conscious rats, carotid and other peripheral chemoreceptor-mediated hypoxic ventilatory responses are critically dependent on NMDA receptor activation and that NMDA receptor mechanisms are only modestly involved during hypercapnia. 相似文献
97.
Fiona J. Stevens McFadden Barry J. Welch Pual C. Austin 《JOM Journal of the Minerals, Metals and Materials Society》2006,58(2):42-47
This paper investigates the application of multivariable model-based control to improve the regulatory control of electrolyte
temperature, aluminum fluoride concentration, liquidus temperature, superheat, and electrolyte height. Also examined are therappropriateness
of different control structures and the possible inclusion of recently developed sensors for alumina concentration and individual
cell duct flowrate, temperature, and heat loss. For the smelter in this study, the maximum improvement possible with a multivariable
model-based controller is predicted to be 30–40% reduction in standard deviation in electrolyte temperature, aluminum fluoride
concentration, liquidus temperature, and superheat, and around half this for electrolyte height. Three control structures
were found to be appropriate; all are different than the existing control structure, which was found to be suboptimal. Linear
Quadratic Gaussian controllers were designed for each control structure and their predicted performance compared.
Comalco Research. 相似文献
98.
Michael K. Cinibulk John R. Welch Randall S. Hay 《Journal of the American Ceramic Society》1996,79(9):2481-2484
A method of preparing transmission electron microscopy (TEM) specimens of coated ceramic fibers has been developed, which produces large electron transparent areas due to the minimal preferential milling of the fiber, coating, or epoxy matrix. Multiple individual fibers or tows are impregnated with a high-temperature epoxy and contained to assure a high fiber-to-epoxy volume ratio. The samples are then sectioned and mechanically thinned either parallel or normal to the fiber axes using a wedge polisher on diamond lapping films to achieve a thickness of less than 5 μ.m. The thinned sample is then ion-milled to electron transparency in less than 30 min, giving representative specimens of the coating, fiber, and coating-fiber interface. This technique is also well suited to preparing extremely flat specimens for scanning electron microscopy analysis of thin coatings. Examples of TEM sections of coated fibers prepared using this technique are presented. 相似文献
99.
The reduction of dissolved sulphur and the soluble species formed during the electrolysis of PbS dissolved in the PbCl2NaCl eutectic has been studied chronopotentiometrically. The pre-lead reduction process reported earlier[1] can now be assigned to a subsulphide species that is generated electrochemically. At higher PbS concentrations (eg 10?3 mol cm?3), elemental sulphur introduces a new reduction wave in addition to the subsulphide. The saturation solubility of sulphur is approximately proportional to the square of the PbS concentration. It has been estimated to be 2.3× 10?4 mol S cm?3 at 430°C for a melt containing 2.4× 10?3 mol PbS cm?3 in the PbCl2-NaCl eutectic. 相似文献
100.
Sowdhamini R; Mitchell TJ; Andrew PW; Morgan PJ 《Protein engineering, design & selection : PEDS》1997,10(3):207-215
Pneumolysin and proaerolysin are bacterial toxins that form pores in host
cells by oligomerization. We propose that they may have similar structures
despite a poor sequence identity. The crystal structure of proaerolysin
reveals a protein composed of four domains, arranged in the shape of an
elongated comma. Electron microscopy of the pneumolysin monomer shows a
similar arrangement of domains. The sequence of pneumolysin recognizes the
template of proaerolysin from a library of protein folds. A
three-dimensional model of pneumolysin has been constructed by the
comparative approach using the structure of proaerolysin. This model,
together with results on the activity of site- specific mutants and the
positions of antigenic sites, has been used to propose functional roles of
individual domains.
相似文献