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21.
Adam R Meir Jeremy CT Fairbank Deborah A Jones Donal S McNally Jill PG Urban 《Scoliosis》2007,2(1):1-16
Background
Loads acting on scoliotic spines are thought to be asymmetric and involved in progression of the scoliotic deformity; abnormal loading patterns lead to changes in bone and disc cell activity and hence to vertebral body and disc wedging. At present however there are no direct measurements of intradiscal stresses or pressures in scoliotic spines. The aim of this study was to obtain quantitative measurements of the intradiscal stress environment in scoliotic intervertebral discs and to determine if loads acting across the scoliotic spine are asymmetric. We performed in vivo measurements of stresses across the intervertebral disc in patients with scoliosis, both parallel (termed horizontal) and perpendicular (termed vertical) to the end plate, using a side mounted pressure transducer (stress profilometry)Methods
Stress profilometry was used to measure horizontal and vertical stresses at 5 mm intervals across 25 intervertebral discs of 7 scoliotic patients during anterior reconstructive surgery. A state of hydrostatic pressure was defined by identical horizontal and vertical stresses for at least two consecutive readings. Results were compared with similar stress profiles measured during surgery across 10 discs of 4 spines with no lateral curvature and with data from the literature.Results
Profiles across scoliotic discs were very different from those of normal, young, healthy discs of equivalent age previously presented in the literature. Hydrostatic pressure regions were only seen in 14/25 discs, extended only over a short distance. Non-scoliotic discs of equivalent age would be expected to show large centrally placed hydrostatic nuclear regions in all discs. Mean pressures were significantly greater (0.25 MPa) than those measured in other anaesthetised patients (<0.07 MPa). A stress peak was seen in the concave annulus in 13/25 discs. Stresses in the concave annulus were greater than in the convex annulus indicating asymmetric loading in these anaesthetised, recumbent patients.Conclusion
Intradiscal pressures and stresses in scoliotic discs are abnormal, asymmetrical and high in magnitude even in the absence of significant applied muscle loading. The origin of these abnormal stresses is unclear. 相似文献22.
The effects of sucrose and fructose on the free energy of unfolding, DeltaG(N-->D), and on the change in hydrodynamic radius, R(H), upon unfolding were measured for RNase A and alpha-lactalbumin. Recently we analyzed the results for RNase A and showed that the effects of the carbohydrates on the protein's thermal stability can be accurately accounted for by scaled particle theory (SPT), and are thus largely entropic in nature. In this paper we extend this analysis to alpha-lactalbumin and demonstrate the generality of this finding. We also investigate the relationship between SPT and the thermodynamic formalism of preferential interactions. The preferential binding parameters calculated using SPT are in excellent agreement with experimentally measured values available in the literature. This agreement is expected to hold as long as enthalpic interactions between the cosolute and the protein are not important, as appears to be the case here. Finally we use the experimental data and SPT to calculate the change in the number of sugar molecules excluded from the protein surface during unfolding from knowledge of the preferential binding parameter for the native and denatured state of the protein. 相似文献
23.
Protein purification with vapor-phase carbon dioxide 总被引:2,自引:0,他引:2
Winters MA Frankel DZ Debenedetti PG Carey J Devaney M Przybycien TM 《Biotechnology and bioengineering》1999,62(3):247-258
Gaseous CO2 was used as an antisolvent to induce the fractional precipitation of alkaline phosphatase, insulin, lysozyme, ribonuclease, trypsin, and their mixtures from dimethylsulfoxide (DMSO). Compressed CO2 was added continuously and isothermally to stationary DMSO solutions (gaseous antisolvent, GAS). Dissolution of CO2 was accompanied by a pronounced, pressure-dependent volumetric expansion of DMSO and a consequent reduction in solvent strength of DMSO towards dissolved proteins. View cell experiments were conducted to determine the pressures at which various proteins precipitate from DMSO. The solubility of each protein in CO2-expanded DMSO was different, illustrating the potential to separate and purify proteins using gaseous antisolvents. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS-PAGE) was used to quantify the separation of lysozyme from ribonuclease, alkaline phosphatase from insulin, and trypsin from catalase. Lysozyme biological activity assays were also performed to determine the composition of precipitates from DMSO initially containing lysozyme and ribonuclease. SDS-PAGE characterizations suggest that the composition and purity of solid-phase precipitated from a solution containing multiple proteins may be accurately controlled through the antisolvent's pressure. Insulin, lysozyme, ribonuclease, and trypsin precipitates recovered substantial amounts of biological activity upon redissolution in aqueous media. Alkaline phosphatase, however, was irreversibly denaturated. Vapor-phase antisolvents, which are easily separated and recovered from proteins and liquid solvents upon depressurization, appear to be a reliable and effective means of selectively precipitating proteins. 相似文献
24.
Kosala GAD Weerakoon Senanayake AM Kularatne Deepthika H Edussuriya Sarachchandra KA Kodikara Laxman PG Gunatilake Vasanti G Pinto Ashoka B Seneviratne Sunethra Gunasena 《BMC research notes》2011,4(1):268
Background
In 2009, an outbreak of dengue caused high fatality in Sri Lanka. We conducted 5 autopsies of clinically suspected myocarditis cases at the General Hospital, Peradeniya to describe the histopathology of the heart and other organs.Methods
The diagnosis of dengue was confirmed with specific IgM and IgG ELISA, HAI and RT-PCR techniques. The histology was done in tissue sections stained with hematoxylin and eosin.Results
Of the 319 cases of dengue fever, 166(52%) had severe infection. Of them, 149 patients (90%) had secondary dengue infection and in 5 patients, DEN-1 was identified as the causative serotype. The clinical diagnosis of myocarditis was considered in 45(27%) patients. The autopsies were done in 5 patients who succumbed to shock (3 females and 2 males) aged 13- 31 years. All had pleural effusions, ascites, bleeding patches in tissue planes and histological evidence of myocarditis. The main histological findings of the heart were interstitial oedema with inflammatory cell infiltration and necrosis of myocardial fibers. One patient had pericarditis. The concurrent pulmonary abnormalities were septal congestion, pulmonary haemorrhage and diffuse alveolar damage; one case showed massive necrosis of liver.Conclusions
The histology supports occurrence of myocarditis in dengue infection.25.
Cultures of 12 South African isolates of an undescribedFusarium species resembling but distinct fromF camptoceras were analysed for the presence of diacetoxyscirpenol (DAS), neosolaniol monoacetate (NMA), and T-2 toxin, by capillary gas chromatography utilizing electron capture detection. No DAS or T-2 toxin could be detected in any of the cultures of the isolates. NMA was, however, detected in 10 of the 12 isolates at levels ranging from 310 to 2060 ng/g. The method used, was primarily developed for the determination of DAS and T-2 toxin in fungal cultures and grain samples but was found to be suitable for the coextraction of NMA at an average recovery of 80.8%, with a detection limit in the order of 100 ng/g. Supportive evidence for the presence of the NMA was obtained by capillary gas chromatography / mass spectrometry. Regarded as a relatively rare trichothecene, NMA has never been reported to occur naturally and has previously been shown to be produced by only a fewFusarium strains. 相似文献
26.
Glauber P Arêas R?de BB Schuab Felipe PG Neves Rosana R Barros 《Memórias do Instituto Oswaldo Cruz》2014,109(7):935-939
Streptococcus pyogenes is responsible for a variety of infectious
diseases and immunological complications. In this study, 91 isolates of S.
pyogenes recovered from oropharynx secretions were submitted to
antimicrobial susceptibility testing, emm typing and pulsed-field
gel electrophoresis (PFGE) analysis. All isolates were susceptible to ceftriaxone,
levofloxacin, penicillin G and vancomycin. Resistance to erythromycin and clindamycin
was 15.4%, which is higher than previous reports from this area, while 20.9% of the
isolates were not susceptible to tetracycline. The macrolide resistance phenotypes
were cMLSB (10) and iMLSB (4). The ermB gene was predominant,
followed by the ermA gene. Thirty-two emm types and
subtypes were found, but five (emm1, emm4,
emm12, emm22, emm81) were detected in
48% of the isolates. Three new emm subtypes were identified
(emm1.74, emm58.14, emm76.7).
There was a strong association between emm type and PFGE clustering.
A variety of PFGE profiles as well as emm types were found among
tetracycline and erythromycin-resistant isolates, demonstrating that antimicrobial
resistant strains do not result from the expansion of one or a few clones. This study
provides epidemiological data that contribute to the development of suitable
strategies for the prevention and treatment of such infections in a poorly studied
area. 相似文献
27.
Three new coumarins, 5-hydroxy-6,7-methylenedioxycoumarin, 5-(2-hydroxy-3-methoxy-3-methylbutoxy)-6,7-methylenedioxycoumarin and 5-(2-hydroxy-3-methyl-3-butenyloxy)coumarin, were isolated from the petrol ether extract of the aerial parts of Pterocaulon virgatum. Their structures were elucidated based on spectroscopic evidence. 相似文献
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