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361.
362.
Germann MW Aramini JM Kalisch BW van de Sande JH 《Nucleosides, nucleotides & nucleic acids》2001,20(4-7):493-499
We employ NMR structure determination, thermodynamics, and enzymatics to uncover the structural, thermodynamic and enzymatic properties of alpha/beta-ODNs containing 3'-3' and 5'-5' linkages. RNase H studies show that alpha/beta-gapmers that are designed to target erbB-2 efficiently elicit RNase H activity. NMR structures of DNA.DNA and DNA.RNA duplexes reveal that single alpha-anomeric residues fit well into either duplex, but alter the dynamic properties of the backbone and deoxyriboses as well as the topology of the minor groove in the DNA.RNA hybrid. 相似文献
363.
The interaction of natural calf thymus DNA with Cr(3+) ions was studied at room temperature by means of vibrational CD (VCD) and infrared absorption (ir) spectroscopy, and atomic force microscopy (AFM). Cr(3+) ion binding mainly to N(7) (G) and to phosphate groups was demonstrated. Psi-type VCD spectra resembling electronic CD (ECD) spectra, which appear during psi-type DNA condensation, were observed. These spectra are characterized mainly by an anomalous, severalfold increase of VCD intensity. Such anomalous VCD spectra were assigned to DNA condensation with formation of large and dense particles of a size comparable to the wavelength of the probing ir beam and possessing large-scale helicity. Atomic force microscopy confirmed DNA condensation by Cr(3+) ions and the formation of tight DNA particles responsible for the psi-type VCD spectra. Upon increasing the Cr(3+) ion concentration the shape of the condensates changed from loose flower-like structures to highly packed dense spheres. No DNA denaturation was seen even at the highest concentration of Cr(3+) ions studied. The secondary structure of DNA remained in a B-form before and after the condensation. VCD and ir as well as AFM proved to be an effective combination for investigating DNA condensation. In addition to the ability of VCD to determine DNA condensation, VCD and ir can in the same experiment provide unambiguous information about the secondary structure of DNA contained in the condensed particles. 相似文献
364.
F.H. van de Sande M.S. Azevedo R.G. Lund M.C.D.N.J.M. Huysmans M.S. Cenci 《Biofouling》2013,29(9):1057-1063
Microcosm biofilms formed in microplates have demonstrated complex community dynamics similar to natural dental biofilm. No simplified microcosm models to evaluate enamel demineralization and dose-response effect to anticariogenic therapies have yet been established, thus this study was designed to develop a pre-clinical model fulfilling this purpose. Experiments were carried out to establish the time of biofilm formation and the sucrose concentration and exposure regimen. Biofilms were initiated from saliva and grown for up to 10 days on bovine enamel discs in 24-well plates, with a saliva analogue medium. Data were collected as pH readings and thepercentage enamel surface hardness change. A dose-response evaluation was performed with chlorhexidine, which significantly affected the pH and mineral loss. Overall, the established model parameters, 5 days of biofilm growth with intermittent 1% sucrose exposure of 6 h per day, was suitable as a pre-clinical model for enamel demineralization and dose-response studies. 相似文献
365.
Dorai Deepa Shanta Achanta Jyoti Jaju Koteswara Rao Rani Samyukta Mareli Claassens Ajay M. V. Kumar Vishnu PH 《PloS one》2013,8(10)
Background
Multi drug resistant and rifampicin resistant TB patients in India are treated with the World Health Organization (WHO) recommended standardized treatment regimens but no guidelines are available for the management of isoniazid (INH) resistant TB patients. There have been concerns that the standard eight-month retreatment regimen being used in India (2H3R3Z3E3S3/1H3R3Z3E3/5H3R3E3; H-Isoniazid; R-Rifampicin; Z-Pyrazinamide; E-Ethambutol; S-Streptomycin) may be inadequate to treat INH resistant TB cases and leads to poor treatment outcomes. We aimed to assess if INH resistance is associated with unfavorable treatment outcomes (death, default, failure and transferred out) among a cohort of smear positive retreatment TB patients registered in three districts of Andhra Pradesh, India.Methods
We conducted a retrospective record review of all smear positive retreatment TB patients without rifampicin resistance registered during April–December 2011.Results
Of 1,947 TB patients, 1,127 (58%) were tested with LPA—50 (4%) were rifampicin resistant, 933 (84%) were sensitive to INH and rifampicin and 144 (12%) were INH resistant. Of 144 INH resistant cases, 64 (44%) had poor treatment outcomes (25 (17%) default, 22 (15%) death, 12 (8%) failure and 5 (3%) transfer out) as compared to 287 (31%) among INH sensitive cases [aRR 1.46; 95%CI (1.19–1.78)].Conclusion
Our study confirms that INH resistance is independently associated with unfavorable treatment outcomes among smear positive retreatment TB patients, indicating that the current treatment regimen may be inadequate. These findings call for an urgent need for randomized controlled trials to discover the most effective treatment regimen for managing INH resistant TB. 相似文献366.
Although the Madurella mycetomatis grains seem to interfere with the host defense mechanisms and impede the antifungal drugs penetration, yet their histological features are not fully known and hence this study was set out to determine that. The study included 80 patients with confirmed M. mycetomatis eumycetoma. After informed written consent, surgical biopsies were obtained from the excised tissues during the patients’ surgical treatment. All sections were stained with haematoxylin and eosin, Grocott’s hexamine silver, Periodic Acid-Schiff’s, Masson-Fontana, Perl’s Prussian Blue, Von-kossa’s, Formalin Inducing Fluorescence and Schmorl’s stains. Modified bleaching technique was used. The concentrations of Zinc, Copper, Calcium, Iron, Lead, Cobalt and Nickel were determined by Atomic Absorption Spectrophotometer. The M. Mycetomatis grains appeared to consist of lipid, protein and melanin. The melanin was located on the hyphal wall as thick layers. The Zinc, Copper and Calcium concentrations in the grains were four, six, and sixteen folds higher than in normal tissue respectively, the other metals were found in the same concentrations as in normal tissue. In the grains, calcium was located in the melanin vicinity. From this study, it can be concluded that, the grains contain melanin, heavy metals, proteins, lipids and they contribute in the formation of the grain cement matrix. These elements seem to contribute in the organism pathogenicity and might impede the penetration of various anti-fungal agents. 相似文献
367.
Boris V. Schmid Eelco A. B. Over Ingrid V. F. van den Broek Eline L. M. Op de Coul Jan E. A. M. van Bergen Johan S. A. Fennema Hannelore M. G?tz Christian J. P. A. Hoebe G. Ardine de Wit Marianne A. B. van der Sande Mirjam E. E. Kretzschmar 《PloS one》2013,8(3)
Background
A large trial to investigate the effectiveness of population based screening for chlamydia infections was conducted in the Netherlands in 2008–2012. The trial was register based and consisted of four rounds of screening of women and men in the age groups 16–29 years in three regions in the Netherlands. Data were collected on participation rates and positivity rates per round. A modeling study was conducted to project screening effects for various screening strategies into the future.Methods and Findings
We used a stochastic network simulation model incorporating partnership formation and dissolution, aging and a sexual life course perspective. Trends in baseline rates of chlamydia testing and treatment were used to describe the epidemiological situation before the start of the screening program. Data on participation rates was used to describe screening uptake in rural and urban areas. Simulations were used to project the effectiveness of screening on chlamydia prevalence for a time period of 10 years. In addition, we tested alternative screening strategies, such as including only women, targeting different age groups, and biennial screening. Screening reduced prevalence by about 1% in the first two screening rounds and leveled off after that. Extrapolating observed participation rates into the future indicated very low participation in the long run. Alternative strategies only marginally changed the effectiveness of screening. Higher participation rates as originally foreseen in the program would have succeeded in reducing chlamydia prevalence to very low levels in the long run.Conclusions
Decreasing participation rates over time profoundly impact the effectiveness of population based screening for chlamydia infections. Using data from several consecutive rounds of screening in a simulation model enabled us to assess the future effectiveness of screening on prevalence. If participation rates cannot be kept at a sufficient level, the effectiveness of screening on prevalence will remain limited. 相似文献368.
369.
Damián Dorfman Marcos L. Aranda María Florencia González Fleitas Mónica S. Chianelli Diego C. Fernandez Pablo H. Sande Ruth E. Rosenstein 《PloS one》2014,9(7)
Diabetic retinopathy is a leading cause of reduced visual acuity and acquired blindness. Available treatments are not completely effective. We analyzed the effect of environmental enrichment on retinal damage induced by experimental diabetes in adult Wistar rats. Diabetes was induced by an intraperitoneal injection of streptozotocin. Three days after vehicle or streptozotocin injection, animals were housed in enriched environment or remained in a standard environment. Retinal function (electroretinogram, and oscillatory potentials), retinal morphology, blood-retinal barrier integrity, synaptophysin, astrocyte and Müller cell glial fibrillary acidic protein, vascular endothelial growth factor, tumor necrosis factor-α, and brain-derived neurotrophic factor levels, as well as lipid peroxidation were assessed in retina from diabetic animals housed in standard or enriched environment. Environmental enrichment preserved scotopic electroretinogram a-wave, b-wave and oscillatory potential amplitude, avoided albumin-Evan''s blue leakage, prevented the decrease in retinal synaptophysin and astrocyte glial fibrillary acidic protein levels, the increase in Müller cell glial fibrillary acidic protein, vascular endothelial growth factor and tumor necrosis factor-α levels, as well as oxidative stress induced by diabetes. In addition, enriched environment prevented the decrease in retinal brain-derived neurotrophic factor levels induced by experimental diabetes. When environmental enrichment started 7 weeks after diabetes onset, retinal function was significantly preserved. These results indicate that enriched environment could attenuate the early diabetic damage in the retina from adult rats. 相似文献
370.
César Pérez-Cruzado Benjamín Sande Beatriz Omil Pere Rovira Manuel Martin-Pastor Nieves Barros Josefa Salgado Agustín Merino 《Plant and Soil》2014,374(1-2):381-398