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排序方式: 共有187条查询结果,搜索用时 234 毫秒
31.
Grzegorz Mędza Jacek Wierzchowski Borys Kierdaszuk David Shugar 《Bioorganic & medicinal chemistry》2009,17(6):2585-2591
Fluorescence emission properties of 8-azacaffeine, 8-azatheophylline and other N-alkylated 8-azaxanthines (8-azaXan) have been examined. It is shown that N-methylated 8-azaxanthines, as well as 8-azatheophylline, are highly fluorescent in aqueous medium as the neutral, and, in some instances, also as the monoanionic, forms. 8-Azacaffeine exhibits moderate emission, but its isomer, 1,3,8-trimethyl-8-azaXan, is highly fluorescent. All three 8-azaxanthines monomethylated on the triazole ring, as well as 8-azaxanthosine, exhibit increased acidity in the excited state. Some fluorescent pyrazolo[4,3-d]pyrimidine-5,7-diones, xanthine congeners of pyrazolo[4,3-d]pyrimidines, are also reported. Many of these are good fluorescent probes in enzymatic, receptor binding, and nucleic acid systems, some examples of which are presented. In particular, 8-azaXan is an excellent fluorescent probe for purine nucleoside phosphorylases, as a fluorogenic substrate in the reverse, synthetic pathway. 相似文献
32.
16S rDNA Pyrosequencing Analysis of Bacterial Community in Heavy Metals Polluted Soils 总被引:1,自引:0,他引:1
Marcin Gołębiewski Edyta Deja-Sikora Marcin Cichosz Andrzej Tretyn Borys Wróbel 《Microbial ecology》2014,67(3):635-647
Soil contamination with heavy metals is a widespread problem, especially prominent on grounds lying in the vicinity of mines, smelters, and other industrial facilities. Many such areas are located in Southern Poland; they are polluted mainly with Pb, Zn, Cd, or Cu, and locally also with Cr. As for now, little is known about most bacterial species thriving in such soils and even less about a core bacterial community—a set of taxa common to polluted soils. Therefore, we wanted to answer the question if such a set could be found in samples differing physicochemically and phytosociologically. To answer the question, we analyzed bacterial communities in three soil samples contaminated with Pb and Zn and two contaminated with Cr and lower levels of Pb and Zn. The communities were assessed with 16S rRNA gene fragments pyrosequencing. It was found that the samples differed significantly and Zn decreased both diversity and species richness at species and family levels, while plant species richness did not correlate with bacterial diversity. In spite of the differences between the samples, they shared many operational taxonomic units (OTUs) and it was possible to delineate the core microbiome of our sample set. The core set of OTUs comprised members of such taxa as Sphingomonas, Candidatus Solibacter, or Flexibacter showing that particular genera might be shared among sites ~40 km distant. 相似文献
33.
Laura L. Hammitt John Ojal Mahfudh Bashraheil Susan C. Morpeth Angela Karani Ahsan Habib Dorota Borys David Goldblatt J. Anthony G Scott 《PloS one》2014,9(1)
Background
The impact on carriage and optimal schedule for primary vaccination of older children with 10-valent pneumococcal non-typeable Haemophilus influenzae protein-D conjugate vaccine (PHiD-CV) are unknown.Methods
600 Kenyan children aged 12–59 months were vaccinated at days 0, 60 and 180 in a double-blind randomized controlled trial according to the following vaccine sequence: Group A: PHiD-CV, PHiD-CV, diphtheria/tetanus/acellular pertussis vaccine (DTaP); Group B: PHiD-CV, DTaP, PHiD-CV; Group C: hepatitis A vaccine (HAV), DTaP, HAV. Nasopharyngeal carriage of Streptococcus pneumoniae was measured at five timepoints. In 375 subjects, serotype-specific responses were measured by 22F-inhibition ELISA and opsonophagocytic killing assays (OPA) one month after vaccination.Results
Following one dose of PHiD-CV, >90% of recipients developed IgG≥0.35 µg/mL to serotypes 1, 4, 5, 7F, 9V and 18C and OPA≥8 to serotypes 4, 7F, 9V, 18C, 23F. After a second dose >90% of recipients had IgG≥0.35 µg/mL to all vaccine serotypes and OPA≥8 to all vaccine serotypes except 1 and 6B. At day 180, carriage of vaccine-type pneumococci was 21% in recipients of two doses of PHiD-CV (Group A) compared to 31% in controls (p = 0.04). Fever after dose 1 was reported by 41% of PHiD-CV recipients compared to 26% of HAV recipients (p<0.001). Other local and systemic adverse experiences were similar between groups.Conclusions
Vaccination of children aged 12–59 months with two doses of PHiD-CV two to six months apart was immunogenic, reduced vaccine-type pneumococcal carriage and was well-tolerated. Administration of PHiD-CV would be expected to provide effective protection against vaccine-type disease.Trial Registration
ClinicalTrials.gov NCT01028326相似文献34.
Araceli Cuellar Atsuyuki Inui Michelle A. James Dariusz Borys A. Hari Reddi 《The journal of histochemistry and cytochemistry》2014,62(7):488-498
The expression of bone morphogenetic proteins (BMPs) and their cognate receptors (BMPRs) in osteochondromas has not been investigated. We determined the immunohistochemical localization and distribution of BMP-2/4, -6 and -7; BMP receptors BMPR-1A, BMPR-1B and BMPR-2; signal transducing proteins phosphorylated Smad1/5/8; and BMP antagonist noggin in the cartilaginous cap of solitary (SO) and multiple (MO) human osteochondromas and compared these with bovine growth plate and articular cartilage. The distribution and localization patterns for BMP-6, BMP-7, BMPR-1A and BMPR-2 were similar between the cartilaginous cap and the growth plate. BMP-2/4 and BMPR-1B were present throughout the growth plate. However, BMP-2/4 and phosphorylated Smad1/5/8 were mainly detected in proliferating chondrocytes of the cartilaginous cap. Also, BMPR-1B was found in hypertrophic chondrocytes of SO and proliferating chondrocytes of MO. Noggin was observed in resting chondrocytes and, to a lesser extent, in clustered proliferating chondrocytes in SO. On the other hand, noggin in MO was observed in proliferating chondrocytes. Since BMPs can stimulate proliferation and hypertrophic differentiation of chondrocytes, these findings suggest that there is an imbalance of BMP-2/4 and noggin interactions that may lead to abnormal regulation of chondrocyte proliferation and differentiation in the cartilaginous cap of human osteochondromas. 相似文献
35.
36.
The tautomerism of the natural 1-substituted pyrimidines and 9-substituted purines found in nucleic acids has been re-examined
in the light of new experimental data on various nitrogen heterocycles in solution, in the gas phase and, in part, in low-temperature
inert matrices. The results are compared with those obtained by quantum chemical calculations, including improved versions
of the latter. Examples are presented of natural nucleosides which exhibit appreciable tautomerism in solution,e.g. formycins A and B, isoguanosine, but are not found in DNA. Illustrations are given of synthetic promutagenic nucleosides
with pronounced tautomerism in solution relevant to their role in mutagenesis, such as the N4-hydroxy-and N4-methoxy cytidines. The amino-imino tautomeric equilibria of the promutagenic N6-hydroxy-and N6 -methoxy-adenosines are highly dependent on the solvent medium, the proportion of the imino species varying from 10% in CCl4 to 90% in aqueous medium. The type of base pairing of these is dependent on the conformation of the exocyclic hydroxy or
methoxy groups. At the monomer level, addition of a potentially complementary base leads to a shift in the tautomeric equilibrium
in favour of the species which pairs with this base. Biological and genetical implications of the foregoing are described. 相似文献
37.
We have investigated conditions that inhibit the tendency of CHO K1 cells to form cellular bridges between microcarriers and
dense clumps of cellular overgrowth in microcarrier cultures. Microcarrier aggregation by cellular bridge formation was found
to occur only during periods of rapid cell growth. The level of microcarrier aggregation decreased with increasing agitation
intensity. Dense masses of cellular overgrowth formed inside bridges connecting the microcarriers and in clumps that protruded
off the microcarrier surface. To replace cells that were continuously sheared from the microcarriers, cell growth occurred
preferentially in areas of overgrowth after confluent microcarriers were maintained in a serum-free medium. This ultimately
led to poor surface coverage as bare spots developed on the microcarrier away from the areas of dense cellular overgrowth.
The development of bare spots was inhibited when confluent microcarriers were maintained in medium supplemented with 1% serum.
The development of cellular overgrowth was inhibited by dimethyl sulfoxide. Thus, maintaining confluent microcarriers in medium
supplemented with 1% dimethyl sulfoxide and 1% calf serum resulted in microcarriers that appeared similar to monolayer cultures.
There was also a decrease in bridging in cultures supplemented with either 1% calf serum or 1% dimethyl sulfoxide/1% calf
serum compared to serum-free cultures. 相似文献
38.
39.
Anna Żółciak Katarzyna Sikora Justyna Anna Nowakowska Monika Małecka Małgorzata Borys Anna Tereba 《Biocontrol Science and Technology》2016,26(12):1706-1718
Polymerase chain reaction-amplified and sequenced isolates of Antrodia gossypium, Phlebiopsis gigantea and Heterobasidion parviporum from decaying Norway spruce wood blocks after three and six months, which exhibited linear growth, were investigated. P. gigantea strains showed the fastest growth, whereas A. gossypium growth was five times slower. The differences between the mean daily increment of A. gossypium and the other examined isolates (except Hp2) were statistically significant. There were also significant differences in wood decay between densities over time. These results were confirmed by the decay acceleration index (DAI) and decay activity index, which were positively correlated with wood density regardless of the fungus species. The registered P. gigantea strains (Rotstop and PG Suspension) exhibited a strong decomposition ability (28% after six months); the weight loss caused by A. gossypium after six months of decay (15.2%) was similar to the results of P. gigantea (GB) after just three months (13.2%). All tested H. parviporum isolates showed rather rapid growth and equally strong wood decay (20–25%) compared to those of P. gigantea. DAI showed that A. gossypium may significantly contribute to wood decomposition over time, particularly in less dense wood samples. The use of both saprotrophs as biological agents against root pathogens is discussed. 相似文献
40.
Michał W. Borys 《Plant and Soil》1966,24(3):476-478
Summary A breaking of petioles of potatoes is described as due to a deficient level of phosphorus in the nutrient medium. 相似文献