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31.
Hallab Nadim J. Mikecz Katalin Vermes Csaba Skipor Anastasia Jacobs Joshua J. 《Molecular and cellular biochemistry》2001,222(1-2):127-136
Metal toxicity from sources such as orthopaedic implants was investigated in terms of immune system hyper-reactivity to metal implant alloy degradation products. Lymphocyte response to serum protein complexed with metal from implant alloy degradation was investigated in this in vitro study using primary human lymphocytes from healthy volunteers (n = 10). Cobalt chromium molybdenum alloy (CoCrMo, ASTM F75) and titanium alloy (Ti6Al4V, ASTM F136) beads (70 m) were incubated in agitated human serum at 37 degrees Celsius to simulate naturally occurring metal implant alloy degradation processes. Particulate free serum samples, which were incubated with metal, were then separated into molecular weight based fractions. The amounts of soluble Cr and Ti within each serum fraction were measured and correlated with lymphocyte proliferation response to the individual serum fractions. Lymphocytes from each subject were cultured with 11 autologous molecular weight based serum fractions either with or without added metal. Two molecular weight ranges of human serum proteins were associated with the binding of Cr and Ti from CoCrMo and Ti implant alloy degradation (at < 30 and 180–330 kDa). High molecular weight serum proteins ( 180 kDa) demonstrated greater lymphocyte reactivity when complexed with metal released from CoCrMo alloy and Ti alloy than with low (5–30 kDa) and midrange (30–77 kDa) serum proteins. When the amount of lymphocyte stimulation was normalized to both the moles of metal and the moles of protein within each fraction (MetalProtein Complex Reactivity Index, MPCRI), Cr from CoCrMo alloy degradation demonstrated approximately 10 fold greater reactivity than Ti in the higher molecular weight serum proteins ( 180–250 kDa). This in vitro study demonstrated a lymphocyte proliferative response to both CoCrMo and Ti alloy metalloprotein degradation products. This response was greatest when the metals were complexed with high molecular weight proteins, and with metalprotein complexes formed from CoCrMo alloy degradation. 相似文献
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Agalya Periasamy Nadim Shadiac Amritha Amalraj Soňa Garajová Yagnesh Nagarajan Shane Waters Haydyn D.T. Mertens Maria Hrmova 《生物化学与生物物理学报:生物膜》2013,1828(2):743-757
A membrane-embedded curdlan synthase (CrdS) from Agrobacterium is believed to catalyse a repetitive addition of glucosyl residues from UDP-glucose to produce the (1,3)-β-d-glucan (curdlan) polymer. We report wheat germ cell-free protein synthesis (WG-CFPS) of full-length CrdS containing a 6xHis affinity tag and either Factor Xa or Tobacco Etch Virus proteolytic sites, using a variety of hydrophobic membrane-mimicking environments. Full-length CrdS was synthesised with no variations in primary structure, following analysis of tryptic fragments by MALDI-TOF/TOF Mass Spectrometry. Preparative scale WG-CFPS in dialysis mode with Brij-58 yielded CrdS in mg/ml quantities. Analysis of structural and functional properties of CrdS during protein synthesis showed that CrdS was co-translationally inserted in DMPC liposomes during WG-CFPS, and these liposomes could be purified in a single step by density gradient floatation. Incorporated CrdS exhibited a random orientation topology. Following affinity purification of CrdS, the protein was reconstituted in nanodiscs with Escherichia coli lipids or POPC and a membrane scaffold protein MSP1E3D1. CrdS nanodiscs were characterised by small-angle X-ray scattering using synchrotron radiation and the data obtained were consistent with insertion of CrdS into bilayers. We found CrdS synthesised in the presence of the Ac-AAAAAAD surfactant peptide or co-translationally inserted in liposomes made from E. coli lipids to be catalytically competent. Conversely, CrdS synthesised with only Brij-58 was inactive. Our findings pave the way for future structural studies of this industrially important catalytic membrane protein. 相似文献
35.
Introduction
Pulmonary function abnormalities have been described in multiple sclerosis including reductions in forced vital capacity (FVC) and cough but the time course of this impairment is unknown. Peak cough flow (PCF) is an important parameter for patients with respiratory muscle weakness and a reduced PCF has a direct impact on airway clearance and may therefore increase the risk of respiratory tract infections. Lung volume recruitment is a technique that improves PCF by inflating the lungs to their maximal insufflation capacity.Objectives
Our goals were to describe the rate of decline of pulmonary function and PCF in patients with multiple sclerosis and describe the use of lung volume recruitment in this population.Methods
We reviewed all patients with multiple sclerosis referred to a respiratory neuromuscular rehabilitation clinic from February 1999 until December 2010. Lung volume recruitment was attempted in patients with FVC <80% predicted. Regular twice daily lung volume recruitment was prescribed if it resulted in a significant improvement in the laboratory.Results
There were 79 patients included, 35 of whom were seen more than once. A baseline FVC <80% predicted was present in 82% of patients and 80% of patients had a PCF insufficient for airway clearance. There was a significant decline in FVC (122.6 mL/y, 95% CI 54.9–190.3) and PCF (192 mL/s/y, 95% 72–311) over a median follow-up time of 13.4 months. Lung volume recruitment was associated with a slower decline in FVC (p<0.0001) and PCF (p = 0.042).Conclusion
Pulmonary function and cough decline significantly over time in selected patients with multiple sclerosis and lung volume recruitment is associated with a slower rate of decline in lung function and peak cough flow. Given design limitations, additional studies are needed to assess the role of lung volume recruitment in patients with multiple sclerosis. 相似文献36.
Saoussen Ben Khedher Nabil Zouari Nadia Messaddeq Patrick Schultz Samir Jaoua 《Current microbiology》2011,62(1):38-43
Asporogenic and oligosporogenic Bacillus
thuringiensis mutants having the ability to overproduce insecticidal crystal protein were generated by using nitrous acid (50 mg/ml), as
chemical mutagenic agent. Insecticidal crystal proteins produced by asporogenic mutants remained encapsulated within the cells.
Delta-endotoxin production by most of mutants was improved compared to the corresponding wild strains BNS3 and a mutant M26.
The overproduction by asporogenic and oligosporogenic mutants was attributed to defect in genes involved in sporulation and
to random mutations affecting cell metabolism at different pathways and delta-endotoxin synthesis. Sporeless bioinsecticides
could be developed based on stable and environmentally safe Bacillus
thuringiensis mutants. 相似文献
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Regulatory roles for small RNAs in bacteria 总被引:1,自引:0,他引:1
39.
Toxoplasma gondii autophagy‐related protein ATG9 is crucial for the survival of parasites in their host 下载免费PDF全文
Rana El Hajj Nadim Tawil Laurence Berry Maryse Lebrun Yann Bordat Sébastien Besteiro 《Cellular microbiology》2017,19(6)
Autophagy is a conserved, life‐promoting, catabolic process involved in the recycling of nonessential cellular components in response to stress. The parasite Toxoplasma gondii is an early‐diverging eukaryote in which part of the autophagy machinery is not exclusively involved in a catabolic process but instead has been repurposed for an original function in organelle inheritance during cell division. This function, depending essentially on protein TgATG8 and its membrane conjugation system, is crucial for parasite survival and prevented an in depth study of autophagy in the mutants generated so far in Toxoplasma. Thus, in order to decipher the primary function of canonical autophagy in the parasites, we generated a cell line deficient for TgATG9, a protein thought to be involved in the early steps of the autophagy process. Although the protein proved to be dispensable for the development of these obligate intracellular parasites in vitro, the absence of TgATG9 led to a reduced ability to sustain prolonged extracellular stress. Importantly, depletion of the protein significantly reduced parasites survival in macrophages and markedly attenuated their virulence in mice. Altogether, this shows TgATG9 is important for the fate of Toxoplasma in immune cells and contributes to the overall virulence of the parasite, possibly through an involvement in a canonical autophagy pathway. 相似文献
40.
Oxidation of biphenyl by a multicomponent enzyme system from Pseudomonas sp. strain LB400. 总被引:5,自引:7,他引:5 下载免费PDF全文
Pseudomonas sp. strain LB400 grows on biphenyl as the sole carbon and energy source. This organism also cooxidizes several chlorinated biphenyl congeners. Biphenyl dioxygenase activity in cell extract required addition of NAD(P)H as an electron donor for the conversion of biphenyl to cis-2,3-dihydroxy-2,3-dihydrobiphenyl. Incorporation of both atoms of molecular oxygen into the substrate was shown with 18O2. The nonlinear relationship between enzyme activity and protein concentration suggested that the enzyme is composed of multiple protein components. Ion-exchange chromatography of the cell extract gave three protein fractions that were required together to restore enzymatic activity. Similarities with other multicomponent aromatic hydrocarbon dioxygenases indicated that biphenyl dioxygenase may consist of a flavoprotein and iron-sulfur proteins that constitute a short electron transport chain involved in catalyzing the incorporation of both atoms of molecular oxygen into the aromatic ring. 相似文献