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91.
Antibiotic Susceptibility of Lactobacillus and Bifidobacterium Species from the Human Gastrointestinal Tract 总被引:2,自引:0,他引:2
One hundred and twenty-two strains of Bifidobacterium and Lactobacillus species have been tested against 12 antibiotics and two antibiotic mixtures by a commercial system (Sensititre Anaero3; Treck Diagnostic Systems). The upper limits of some minimum inhibitory concentrations (MICs) were completed on MRS agar plates by the NCCLS procedure. All strains were sensitive to chloramphenicol and imipenem and most of the strains were resistant to metronidazole. Bifidobacteria isolates were susceptible to cefoxitin, whereas about half of the lactobacilli were resistant. Approximately 30% of the Bifidobacterium isolates were resistant to tetracycline, as well as five Lactobacillus strains belonging to four different species. None of the tested Bifidobacterium isolates was resistant to vancomycin, whereas a species-dependent resistance was found among the lactobacilli. Single strains of Bifidobacterium longum, Bifidobacterium pseudocatenulatum, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Lactobacillus brevis were resistant to erythromycin and/or clindamycin. Most of the observed resistances seemed to be intrinsic, but some others could be compatible with transmissible determinants. 相似文献
92.
Naus S Reipschläger S Wildeboer D Lichtenthaler SF Mitterreiter S Guan Z Moss ML Bartsch JW 《Biological chemistry》2006,387(3):337-346
ADAM proteases are type I transmembrane proteins with extracellular metalloprotease domains. As for most ADAM family members, ADAM8 (CD156a, MS2) is involved in ectodomain shedding of membrane proteins and is linked to inflammation and neurodegeneration. To identify potential substrates released under these pathologic conditions, we screened 10-mer peptides representing amino acid sequences from extracellular domains of various membrane proteins using the ProteaseSpot system. A soluble ADAM8 protease containing a pro- and metalloprotease domain was expressed in E. coli and purified as active protease owing to autocatalytic prodomain removal. From 34 peptides tested in the peptide cleavage assay, significant cleavage by soluble ADAM8 was observed for 14 peptides representing membrane proteins with functions in inflammation and neurodegeneration, among them the beta-amyloid precursor protein (APP). The in vivo relevance of the ProteaseSpot method was confirmed by cleavage of full-length APP with ADAM8 in human embryonic kidney 293 cells expressing tagged APP. ADAM8 cleaved APP with similar efficiency as ADAM10, whereas the inactive ADAM8 mutant did not. Exchanging amino acids at defined positions in the cleavage sequence of myelin basic protein (MBP) revealed sequence criteria for ADAM8 cleavage. Taken together, the results allowed us to identify novel candidate substrates that could be cleaved by ADAM8 in vivo under pathologic conditions. 相似文献
93.
Iyú D Atucha NM Martínez-Prieto C Ortiz MC García-Estañ J 《Cell communication and signaling : CCS》2004,2(1):1
Background
In the present study we have analyzed the mechanisms of calcium entry and mobilization in platelets obtained from rats chronically treated with the nitric oxide synthesis inhibitor, N-nitro L-arginine methyl ester [L-NAME, 40 mg/kg/day, 5 days). The platelets were obtained the day of the experiment, washed and loaded with fura-2. The intracellular calcium levels were determined in suspension of cells by means of fluorescence spectroscopy. 相似文献94.
C. C. Marques A. C. Nunes T. Pinheiro P. A. Lopes M. C. Santos A. M. Viegas-Crespo M. G. Ramalhinho M. L. Mathias 《Biological trace element research》2006,109(1):75-89
Time-dependent effects of lead (Pb) toxicity were studied in Algerian mice (Mus spretus) treated with Pb acetate via drinking water (1 g Pb acetate/L) for different periods of exposure (15, 45, and 90 d). End
points included the determination of hepatic Pb concentration and the assessment of some morphophysiological, biochemical
and cytogenetical parameters. A control group receiving distilled water was also monitored for comparative purposes. Hepatic
Pb accumulation increased with the time of exposure and was significantly higher in treated mice when compared to controls.
In association with significant body mass loss in Pb-exposed mice, for 15 and 45 d, a significant increase in the relative
spleen mass was observed after 45 d of intoxication. Pb-exposed mice also showed significant decreases in red blood cells,
hematocrit, and mean corpuscular hemoglobin. On the contrary, changes in plasma transferases (aspartate aminotransferase and
alanine aminotransferase) and hepatic superoxide dismutase activities did not reach statistical significance. A significant
increase in the frequency of micronucleated polychromatic bone marrow erythrocytes was also found in the 90-d-exposed mice,
compared to nontreated mice and the other exposed groups. Exposure to Pb acetate resulted also in a slight time-dependent
decrease of the polychromatic-normochromatic ratio. These results support the concept that a long-term chronic exposure to
Pb induced alterations upon some morphophysiological and genetic paramaters in Algerian mice. 相似文献
95.
Trace Element Composition of Selected Fertilizers Used in Chile: Phosphorus Fertilizers as a Source of Long-Term Soil Contamination 总被引:2,自引:0,他引:2
Mauricio Molina Fabián Aburto Raúl Calderón Marcia Cazanga Mauricio Escudey 《Soil & Sediment Contamination》2009,18(4):497-511
Anthropogenic activities like agriculture have resulted in increased concentrations of some trace elements of toxicological and environmental concern in soils. Application of fertilizers has been one of the major inputs of these contaminants to agricultural soils in developing countries. Twenty-two fertilizers, including straight nitrogen (N), phosphorus (P), potassium (K), and NK fertilizers and micronutrient sources, were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) for arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn). As expected, the trace element content of fertilizers was highly variable and related to the origin of the material. Phosphorus fertilizers, especially triple superphosphate, presented the highest As, Cd, Cu, Cr, Ni, V, and Zn concentrations. In some of these fertilizers, the Cr, V, and Zn contents reached values greater than 3475 mg kg?1 of P, and the Cd content (up to 288 mg kg?1 of P) was several times higher than the regulatory limits of different countries. Some micronutrient sources presented the highest concentrations of Mn and Pb. In the cases of N, K, and NK fertilizers, the trace element concentration was very low, sometimes below the detection limits. In some agricultural systems the input of trace elements such as As and Cd to the soil through P fertilizers application may be higher than the outputs through plant uptake and leaching; therefore the long-term use of these fertilizers may cause the trace element concentration to increase in the plow layer of agricultural soils. 相似文献
96.
Paulo Cesar Gomes Bibiana Monson de Souza Nathalia Baptista Dias Patrícia Brigatte Danilo Mourelle Helen Andrade Arcuri Marcia Perez dos Santos Cabrera Rodrigo Guerino Stabeli João Ruggiero Neto Mario Sergio Palma 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
The peptide Paulistine was isolated from the venom of wasp Polybia paulista. This peptide exists under a natural equilibrium between the forms: oxidised — with an intra-molecular disulphide bridge; and reduced — in which the thiol groups of the cysteine residues do not form the disulphide bridge. The biological activities of both forms of the peptide are unknown up to now.Methods
Both forms of Paulistine were synthesised and the thiol groups of the reduced form were protected with the acetamidemethyl group [Acm-Paulistine] to prevent re-oxidation. The structure/activity relationships of the two forms were investigated, taking into account the importance of the disulphide bridge.Results
Paulistine has a more compact structure, while Acm-Paulistine has a more expanded conformation. Bioassays reported that Paulistine caused hyperalgesia by interacting with the receptors of lipid mediators involved in the cyclooxygenase type II pathway, while Acm-Paullistine also caused hyperalgesia, but mediated by receptors involved in the participation of prostanoids in the cyclooxygenase type II pathway.Conclusion
The acetamidemethylation of the thiol groups of cysteine residues caused small structural changes, which in turn may have affected some physicochemical properties of the Paulistine. Thus, the dissociation of the hyperalgesy from the edematogenic effect when the actions of Paulistine and Acm-Paulistine are compared to each other may be resulting from the influence of the introduction of Acm-group in the structure of Paulistine.General significance
The peptides Paulistine and Acm-Paulistine may be used as interesting tools to investigate the mechanisms of pain and inflammation in future studies. 相似文献97.
María C. Ortiz María F. Albertoni Borghese Sabrina E. Balonga Agustina Lavagna Ana L. Filipuzzi Rosana Elesgaray María A. Costa Mónica P. Majowicz 《PloS one》2014,9(8)
The aim of this study was to evaluate whether L-Arginine (L-Arg) supplementation modifies nitric oxide (NO) system and consequently aquaporin-2 (AQP2) expression in the renal outer medulla of streptozotocin-diabetic rats at an early time point after induction of diabetes. Male Wistar rats were divided in four groups: Control, Diabetic, Diabetic treated with L-Arginine and Control treated with L-Arginine. Nitric oxide synthase (NOS) activity was estimated by [14C] L-citrulline production in homogenates of the renal outer medulla and by NADPH-diaphorase staining in renal outer medullary tubules. Western blot was used to detect the expression of AQP2 and NOS types I and III; real time PCR was used to quantify AQP2 mRNA. The expression of both NOS isoforms, NOS I and NOS III, was decreased in the renal outer medulla of diabetic rats and L-Arg failed to prevent these decreases. However, L-Arg improved NO production, NADPH-diaphorase activity in collecting ducts and other tubular structures, and NOS activity in renal homogenates from diabetic rats. AQP2 protein and mRNA were decreased in the renal outer medulla of diabetic rats and L-Arg administration prevented these decreases. These results suggest that the decreased NOS activity in collecting ducts of the renal outer medulla may cause, at least in part, the decreased expression of AQP2 in this model of diabetes and constitute additional evidence supporting a role for NO in contributing to renal water reabsorption through the modulation of AQP2 expression in this pathological condition. However, we cannot discard that another pathway different from NOS also exists that links L-Arg to AQP2 expression. 相似文献
98.
99.
The impact on protein evolution of the physical laws that govern folding remains obscure. Here, by analyzing in silico-evolved sequences subjected to evolutionary pressure for fast folding, it is shown that: First, a subset of residues in the thermodynamic folding nucleus is mainly responsible for modulating the protein folding rate. Second and most important, the protein topology itself is of paramount importance in determining the location of these residues in the structure. Further stabilization of the interactions in this nucleus leads to fast folding sequences. Third, these nucleation points restrict the sequence space available to the protein during evolution. Correlated mutations between positions around these hot spots arise in a statistically significant manner, and most involve contacting residues. When a similar analysis is carried out on real proteins, qualitatively similar results are obtained. 相似文献
100.