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21.
Background
The green fluorescent protein (GFP) has been widely used in cell biology as a marker of gene expression, label of cellular structures, fusion tag or as a crucial constituent of genetically encoded biosensors. Mutagenesis of the wildtype gene has yielded a number of improved variants such as EGFP or colour variants suitable for fluorescence resonance energy transfer (FRET). However, folding of some of these mutants is still a problem when targeted to certain organelles or fused to other proteins. 相似文献22.
23.
Pacheco RS de Brito CM Sarquis O Pires MQ Borges-Pereira J Lima MM 《Biochemical genetics》2005,43(9-10):519-530
Eighteen Trypanosoma cruzi strains isolated from naturally infected triatomines were studied genetically. The majority of the strains were from Triatoma brasiliensis, the principal vector of Chagas disease in the northeast of Brazil. Multilocus enzyme electrophoresis (MLEE) and randomly amplified polymorphic DNA (RAPD) analyses were used to investigate the genotypic diversity and the spread of the T. cruzi genotypes in different environments. MLEE clearly distinguished two distinct isoenzyme profiles, and RAPD analysis revealed 10 different genotypes circulating in rural areas. The strains could be typed as isoenzyme variants of the T. cruzi principal zymodeme Z1 (T. cruzi I). An effective program of epidemiological vigilance is required to prevent the spread of T. cruzi I strains into human dwellings. 相似文献
24.
Shelagh M. Redmond Karin Alexander-Kisslig Sarah C. Woodhall Ingrid V. F. van den Broek Jan van Bergen Helen Ward Anneli Uusküla Bj?rn Herrmann Berit Andersen Hannelore M. G?tz Otilia Sfetcu Nicola Low 《PloS one》2015,10(1)
Background
Accurate information about the prevalence of Chlamydia trachomatis is needed to assess national prevention and control measures.Methods
We systematically reviewed population-based cross-sectional studies that estimated chlamydia prevalence in European Union/European Economic Area (EU/EEA) Member States and non-European high income countries from January 1990 to August 2012. We examined results in forest plots, explored heterogeneity using the I2 statistic, and conducted random effects meta-analysis if appropriate. Meta-regression was used to examine the relationship between study characteristics and chlamydia prevalence estimates.Results
We included 25 population-based studies from 11 EU/EEA countries and 14 studies from five other high income countries. Four EU/EEA Member States reported on nationally representative surveys of sexually experienced adults aged 18–26 years (response rates 52–71%). In women, chlamydia point prevalence estimates ranged from 3.0–5.3%; the pooled average of these estimates was 3.6% (95% CI 2.4, 4.8, I2 0%). In men, estimates ranged from 2.4–7.3% (pooled average 3.5%; 95% CI 1.9, 5.2, I2 27%). Estimates in EU/EEA Member States were statistically consistent with those in other high income countries (I2 0% for women, 6% for men). There was statistical evidence of an association between survey response rate and estimated chlamydia prevalence; estimates were higher in surveys with lower response rates, (p = 0.003 in women, 0.018 in men).Conclusions
Population-based surveys that estimate chlamydia prevalence are at risk of participation bias owing to low response rates. Estimates obtained in nationally representative samples of the general population of EU/EEA Member States are similar to estimates from other high income countries. 相似文献25.
Purpose
To identify the relationships between some infectious agents implicated in cardiovascular diseases with the cellular substrate and prosthetic devices in the presence of antibiotics.Specific objectives
Strains isolation and identification, comparative study of antibiotic resistance of planktonic (disk diffusion, E-test, automatic systems) and sessile (using original experimental models for in vitro development of monospecific biofilms) bacterial cells, virulence assays (adherence and invasion of HeLa cells, slime test, soluble virulence factors expression), dynamic study of biofilm development on inert substrata, under the influence of antibiotics, the influence of cellular and soluble bacterial fractions on HeLa cells (by flow cytometry and real-time PCR).Results
The identified strains were isolated from different sources, the etiology being dominated by Gram-negative non-fermentative bacilli, Gram-positive cocci and yeasts, harboring invasion enzymes responsible for development of systemic infections. The isolated strains exhibited a high level of antibiotic resistance to beta-lactams, aminoglycosides and quinolones, and an evident tendency of colonizing the cellular and inert substrate, the degree of colonization depending on the physico-chemical nature of the substrate. By comparison with planktonic ones, the sessile bacterial strains expressed a changed profile of antibiotic resistance, this aspect being very important for the readjustment of the treatment and prevention of infections associated with prosthetic devices. In vitro experiments suggested that different fractions of S. aureus cultures could trigger the release of proinflammatory (TNF-α, IL-1b, IL-6) and anti-inflammatory (IL-8) cytokines and induced apoptosis in HeLa cells. 相似文献26.
Jean de Dieu Tamokou Jean Rodolphe Chouna Eva Fischer-Fodor Gabriela Chereches Otilia Barbos Grigore Damian Daniela Benedec Mihaela Duma Alango Pépin Nkeng Efouet Hippolyte Kamdem Wabo Jules Roger Kuiate Augustin Mot Radu Silaghi-Dumitrescu 《PloS one》2013,8(2)
Traditional remedies have a long-standing history in Cameroon and continue to provide useful and applicable tools for treating ailments. Here, the anticancer, antimicrobial and antioxidant activities of ten antioxidant-rich Cameroonian medicinal plants and of some of their isolated compounds are evaluated.The plant extracts were prepared by maceration in organic solvents. Fractionation of plant extract was performed by column chromatography and the structures of isolated compounds (emodin, 3-geranyloxyemodin, 2-geranylemodin) were confirmed spectroscopically. The antioxidant activity (AOA) was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) bleaching method, the trolox equivalent antioxidant capacity (TEAC), and the hemoglobin ascorbate peroxidase activity inhibition (HAPX) assays. The anticancer activity was evaluated against A431 squamous epidermal carcinoma, WM35 melanoma, A2780 ovary carcinoma and cisplatin-resistant A2780cis cells, using a direct colorimetric assay. The total phenolic content in the extracts was determined spectrophotometrically by the Folin–Ciocalteu method. Rumex abyssinicus showed the best AOA among the three assays employed. The AOA of emodin was significantly higher than that of 3-geranyloxyemodin and 2-geranylemodin for both TEAC and HAPX methods. The lowest IC50 values (i.e., highest cytotoxicity) were found for the extracts of Vismia laurentii, Psorospermum febrifugum, Pentadesma butyracea and Ficus asperifolia. The Ficus asperifolia and Psorospermum febrifugum extracts are selective against A2780cis ovary cells, a cell line which is resistant to the standard anticancer drug cisplatin. Emodin is more toxic compared to the whole extract, 3-geranyloxyemodin and 2-geranylemodin. Its selectivity against the platinum-resistant A2780cis cell line is highest. All of the extracts display antimicrobial activity, in some cases comparable to that of gentamycin. 相似文献
27.
Elena Maria Mosoarca Ingo Pantenburg Gerd Meyer Adelina Han Reni Kalfin Otilia Costisor 《Inorganica chimica acta》2011,370(1):460-468
The compound [Cu(TAMEN)][Cu(NCS)2Cl](DMF)2 containing the Mannich base N,N′-tetra-(4-antipyrylmethyl)-1,2-diaminoethane (TAMEN), as ligand, was synthesized and characterized by conductometric, magnetic, electronic and infrared spectroscopic properties. The single-crystal X-ray structure shows the presence of two well defined complex units, [Cu(TAMEN)]2+ and [Cu(NCS)2Cl]2−.The complex cation contains copper(II) in the elongated pseudo-octahedral environment created by the N2O4 donor set of TAMEN whereas, the counterion exhibits a pseudo trigonal planar geometry around the Cu(I) ion.Both, the pyrazolonic ligand and the complex have been screened for their cytotoxic activity against human tumor cell lines: glioblastoma multiforme, breast cancer, hepatoma and lung carcinoma. The nontumor cell lines MDBK (bovine kidney) and BALB/c 3T3 clone 31 (mouse embryo) were also included in the experiments. In contrast to the ligand TAMEN, the [Cu(TAMEN)][Cu(NCS)2Cl](DMF)2 was found to decrease in a time- and concentration-dependent manner the viability of cultured tumor (MCF-7, A549, 8MGBA, Hep G2) and non-tumor (MDBK, BALB/c 3T3) cell lines. 相似文献
28.
? Responses to simulated nitrogen (N) deposition with or without added phosphorus (P) were investigated for three contrasting lichen species - the N-sensitive Alectoria sarmentosa, the more N-tolerant Platismatia glauca and the N(2) -fixing Lobaria pulmonaria- in a field experiment. ? To examine whether nutrient limitation differed between the photobiont and the mycobiont within the lichen, the biomass responses of the respective bionts were estimated. ? The lichenized algal cells were generally N-limited, because N-stimulated algal growth in all three species. The mycobiont was P-limited in one species (A. sarmentosa), but the growth response of the mycobionts was complex, as fungal growth is also dependent on a reliable carbon export from the photobiont, which may have been the reason for the decrease of the mycobiont with N addition in P. glauca. ? Our findings showed that P availability was an important factor when studying effects of N deposition, as P supply can both mitigate and intensify the negative effects of N on epiphytic lichens. 相似文献
29.
Cheregi O Sicora C Kós PB Barker M Nixon PJ Vass I 《Biochimica et biophysica acta》2007,1767(6):820-828
The photosystem two (PSII) complex found in oxygenic photosynthetic organisms is susceptible to damage by UV-B irradiation and undergoes repair in vivo to maintain activity. Until now there has been little information on the identity of the enzymes involved in repair. In the present study we have investigated the involvement of the FtsH and Deg protease families in the degradation of UV-B-damaged PSII reaction center subunits, D1 and D2, in the cyanobacterium Synechocystis 6803. PSII activity in a DeltaFtsH (slr0228) strain, with an inactivated slr0228 gene, showed increased sensitivity to UV-B radiation and impaired recovery of activity in visible light after UV-B exposure. In contrast, in DeltaDeg-G cells, in which all the three deg genes were inactivated, the damage and recovery kinetics were the same as in the WT. Immunoblotting showed that the loss of both the D1 and D2 proteins was retarded in DeltaFtsH (slr0228) during UV-B exposure, and the extent of their restoration during the recovery period was decreased relative to the WT. However, in the DeltaDeg-G cells the damage and recovery kinetics of D1 and D2 were the same as in the WT. These data demonstrate a key role of FtsH (slr0228), but not the Deg proteases, for the repair of PS II during and following UV-B radiation at the step of degrading both of the UV-B damaged D1 and D2 reaction center subunits. 相似文献
30.
Jenny Tigerholm Marcus?E. Petersson Otilia Obreja Esther Eberhardt Barbara Namer Christian Weidner Angelika Lampert Richard?W. Carr Martin Schmelz Erik Fransén 《Biophysical journal》2015,108(5):1057-1071
Following each action potential, C-fiber
nociceptors undergo cyclical changes in excitability, including a period of
superexcitability, before recovering their basal excitability state. The
increase in superexcitability during this recovery cycle depends upon their
immediate firing history of the axon, but also determines the instantaneous
firing frequency that encodes pain intensity. To explore the mechanistic
underpinnings of the recovery cycle phenomenon a biophysical model of a C-fiber
has been developed. The model represents the spatial extent of the axon
including its passive properties as well as ion channels and the Na/K-ATPase ion
pump. Ionic concentrations were represented inside and outside the membrane. The
model was able to replicate the typical transitions in excitability from
subnormal to supernormal observed empirically following a conducted action
potential. In the model, supernormality depended on the degree of conduction
slowing which in turn depends upon the frequency of stimulation, in accordance
with experimental findings. In particular, we show that activity-dependent
conduction slowing is produced by the accumulation of intraaxonal sodium. We
further show that the supernormal phase results from a reduced potassium current
Kdr as a result of accumulation of periaxonal potassium in
concert with a reduced influx of sodium through Nav1.7 relative
to Nav1.8 current. This theoretical prediction was supported by
data from an in vitro preparation of small rat dorsal root ganglion somata
showing a reduction in the magnitude of tetrodotoxin-sensitive relative to
tetrodotoxin -resistant whole cell current. Furthermore, our studies provide
support for the role of depolarization in supernormality, as previously
suggested, but we suggest that the basic mechanism depends on changes in ionic
concentrations inside and outside the axon. The understanding of the mechanisms
underlying repetitive discharges in recovery cycles may provide insight into
mechanisms of spontaneous activity, which recently has been shown to correlate
to a perceived level of pain. 相似文献