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991.
Soil structure stability was studied in every diagnostic horizons of six soil types (Haplic Chernozem, Greyic Phaeozem, two
Haplic Luvisols, Haplic Cambisol, Dystric Cambisol) using different techniques investigating various destruction mechanisms
of soil aggregates. Soil aggregate stability, assessed by the index of water stable aggregates (WSA), varied depending on the organic matter content, clay content and pHKCl. The presence of clay and organic matter coatings and fillings, and presence of iron oxides in some soils increased stability
of soil aggregates. On the other hand periodical tillage apparently decreased aggregate stability in the Ap horizons. Coefficients
of aggregate vulnerability resulting from fast wetting (KV
1) and slow wetting (KV
2) tests showed similar trends of the soil aggregate stability as the WSA index, when studied for soils developed on the similar parent material. There was found close correlation between the WSA index and the KV
1 value, which depended also on the organic matter content, clay content and pHKCl. Less significant correlation was obtained between the WSA index and the KV
2 value, which depended on the organic matter content and clay content. Coefficients of vulnerability resulting from the shaking
after pre-wetting test (KV
3) showed considerably different trends in comparison to the other tests due to the different factors affecting aggregate stability
against the mechanical destruction. The KV
3 value depended mostly on cation exchange capacity, pHKCl and organic matter content. 相似文献
992.
Ferdinand ?porka Zuzana Pastuchová Ladislav Hamerlík Marcela Dobia?ová Pavel Beracko 《Biologia》2009,64(6):1196-1205
A method is presented for defining the five classes of ecological quality based on a multimetric index (MMI) of macroinvertebrates,
as required for implementation of the Water Framework Directive for small (catchment area 10–100 km2), medium (101–1000 km2) and large (> 1000 km2) streams. Our method (expert judgment) allows us to overcome an absence of reference sites for some stream types. The key
was selection of suitable metrics for all stream types. The whole procedure was divided into two parts. 1. Small streams with
reference sites: suitable metrics were selected according to their ability to distinguish reference and monitoring sites —
SI, Oligo [%], BMWP, RhiTI, Rheoindex, IBCR, % Aka+Lit+Psa [%] and EPT. Here the high-good boundary value was set as the 25th (for metrics decreasing with increasing pollution) or 75th percentile (for metrics increasing with increasing pollution). 2. Medium and large streams which lack reference sites: here
the idea was applied that some metrics, the values of which change along an altitudinal gradient, also react to anthropogenic
stress — SI, Oligo [%], BMWP, [%] metarhithral, RhiTI, Aka+Lit+Psa [%] and EPT for both medium and large streams with, in
addition, IBCR and NFam for medium streams. This assumption was supported by regression analysis of altitude and metrics from
small streams. Not all the metrics were related to altitude but metrics with a good ability to separate reference and monitoring
sites did show a significant relationship to altitude. The boundary between high and good class for medium and large streams
was set as the 95th or 5th percentiles. 相似文献
993.
Pedilanthus tithymaloides (L.) Poit. (Euphorbiaceae) is a low tropical American shrub with a reported wide range of healing properties such as emetic, anti-inflammatory, antibiotic, antiseptic, antihemorrhagic, antiviral, antitumoral, and abortive. In the present study, a tincture from P. tithymaloides collected in Cuba was evaluated for its in vivo anti-inflammatory activity, using the rat paw oedema assay, and for its in vitro scavenging effects on reactive oxygen species (ROS) (HO*, O2*-, HOCl, ROO* and H2O2), reactive nitrogen species (RNS) (ONOO- and *NO), and DPPH* radical. The protein, free amino acid, and phenolic contents of the tincture were also determined. Pertaining to the anti-inflammatory activity, the intraperitoneal administration of the tincture inhibited carrageenan-induced rat paw oedema, whereas in the scavenging assays the tincture showed to be effective against all the assayed ROS and RNS, specially for HO* (IC50 = 345+/-77 microg/mL), O2*- (IC50 = 143+/-7 microg/mL), HOCl (IC50 = 113+/-20 microg/mL), ONOO- (IC50 = 44+/-3 microg/mL), and *NO (IC50 = 54+/-4 microg/mL), but displayed weak activity in the DPPH* assay. The protein content of the tincture was 0.70%, and twenty free amino acids were identified and quantified. The content of total phenolics was 17.4+/-0.15 mg of gallic acid equivalents (GAE)/g dry material. These results provide scientific support for the empirical use of P. tithymaloides tincture as an anti-inflammatory medicine. 相似文献
994.
We have previously reported that white spot syndrome virus-infected Penaeus vannamei (also called Litopenaeus vannamei) maintained at 32 degrees C show higher survival rates and a significant increase in number of apoptotic cells when compared to infected shrimp kept at 26 degrees C. As apoptosis plays an important part in the antiviral response of invertebrates, we hypothesized that this process would reduce WSSV replication, allowing the shrimp to control the disease and survive. To test this hypothesis, shrimp were orally infected and maintained at either 26 degrees C (Group 1) or 32 degrees C (Group 2), DNA was extracted from haemolymph collected at various times from 6 to 216 h post-infection, and the number of viral units was quantified by real time PCR using SYBR Green. In parallel, histological examination was carried out to confirm the WSSV infection and to rule out concomitant diseases. Linear regression of real time PCR units (rtPCRU) of WSSV from Group 1 showed a significant increase with time post-infection (r2 = 0.7383; p < 0.001). Conversely, there was no increase in rtPCRU with time post-infection in Group 2 (r2 = 0.142), indicating that hyperthermia inhibited, either directly or indirectly, viral replication. In addition, comparison between the groups showed no difference in WSSV rtPCRU up to 48 h post-infection. After 72 h, shrimp from Group 1 had a significantly higher viral rtPCRU (ANOVA, p < 0.001). We conclude that hyperthermia-associated WSSV rtPCRU reduction could reflect either an increase in the shrimp antiviral response, or a direct negative effect on viral replication, or both. 相似文献
995.
996.
997.
Racedo S Villena J Medina M Agüero G Rodríguez V Alvarez S 《Microbes and infection / Institut Pasteur》2006,8(9-10):2359-2366
The effect of the oral administration of Lactobacillus casei on the prevention of a Streptococcus pneumoniae lung infection in a mouse experimental model was studied, analyzing the innate and specific immune response. Adult Swiss albino mice were treated with L. casei (10(9)CFU/day) for 2, 5 and 7 d. Mice were infected intranasally with S. pneumoniae (10(6)CFU/mouse) after each treatment and the microbiological, histopathological and host responses were determined for 15 d after infection. Feeding L. casei for 2 d induced a faster clearance of S. pneumoniae, with a lower number of pneumococci in lung and a shorter period of septicemia than in the control group. L. casei administration induced activation of phagocytes as evidenced by the strong myeloperoxidase activity and the nitro blue tetrazolium assay in lung. Mice given L. casei for 2 d showed higher levels of anti-pneumococcal serum IgG and bronchoalveolar lavage IgA than the control mice. The group fed L. casei for 2 d could beneficially regulate the balance between tumor necrosis factor alpha and interleukin 10, allowing a more effective immune response against infection and modulating the inflammatory response, with less damage to the lung. 相似文献
998.
Gurfinkel DM Chow S Hurren R Gronda M Henderson C Berube C Hedley DW Schimmer AD 《Apoptosis : an international journal on programmed cell death》2006,11(9):1463-1471
Triterpenoids are a novel class of compounds being investigated as potential therapeutic agents for the treatment of prostate
cancer and other malignancies. Asiatic acid (AA) is a member of the ursane family of triterpenoids and has anticancer activity,
but its mechanism of action is not completely understood. To investigate its mechanism of action, PPC-1 prostate cancer cells
were treated with AA at increasing concentrations and times. AA induced rapid caspase-dependent and independent cell death
that peaked within 8 h of treatment. AA-induced death was associated with early activation of caspases 2, 3, and 8, but not
caspase 9. Within 2.5 h of treatment, release of calcium from intracellular stores and dilatation of the endoplasmic reticulum
was observed. Thus, disruption of the endoplasmic reticulum and alterations in calcium homeostasis are early events in AA-induced
death. 相似文献
999.
Lareschi M Gettinger D Venzal JM Arzua M Nieri-Bastos FA Barros-Battesti DM Gonzalez EM 《Neotropical Entomology》2006,35(5):596-601
Information is presented for the first time on laelapid mites associated with wild rodents in Uruguay. Specimens of the following species were identified: Laelapinae: Androlaelaps fahrenholzi (Berlese), Androlaelaps rotundus (Fonseca), Gigantolaelaps wolffsohni (Oudemans), Laelaps paulistanensis (Fonseca), Laelaps manguinhosi (Fonseca) and Mysolaelaps microspinosus Fonseca; Haemogamasinae: Eulaelaps stabularis (Koch). Most of the ectoparasite-host associations are reported for the first time. New host and locality records presented in this study are in accordance with previous findings on the same and/or related host species in nearby South American localities. 相似文献
1000.
Marín-Hernández A Rodríguez-Enríquez S Vital-González PA Flores-Rodríguez FL Macías-Silva M Sosa-Garrocho M Moreno-Sánchez R 《The FEBS journal》2006,273(9):1975-1988
Control analysis of the glycolytic flux was carried out in two fast-growth tumor cell types of human and rodent origin (HeLa and AS-30D, respectively). Determination of the maximal velocity (V(max)) of the 10 glycolytic enzymes from hexokinase to lactate dehydrogenase revealed that hexokinase (153-306 times) and phosphofructokinase-1 (PFK-1) (22-56 times) had higher over-expression in rat AS-30D hepatoma cells than in normal freshly isolated rat hepatocytes. Moreover, the steady-state concentrations of the glycolytic metabolites, particularly those of the products of hexokinase and PFK-1, were increased compared with hepatocytes. In HeLa cells, V(max) values and metabolite concentrations for the 10 glycolytic enzyme were also significantly increased, but to a much lesser extent (6-9 times for both hexokinase and PFK-1). Elasticity-based analysis of the glycolytic flux in AS-30D cells showed that the block of enzymes producing Fru(1,6)P2 (i.e. glucose transporter, hexokinase, hexosephosphate isomerase, PFK-1, and the Glc6P branches) exerted most of the flux control (70-75%), whereas the consuming block (from aldolase to lactate dehydrogenase) exhibited the remaining control. The Glc6P-producing block (glucose transporter and hexokinase) also showed high flux control (70%), which indicated low flux control by PFK-1. Kinetic analysis of PFK-1 showed low sensitivity towards its allosteric inhibitors citrate and ATP, at physiological concentrations of the activator Fru(2,6)P2. On the other hand, hexokinase activity was strongly inhibited by high, but physiological, concentrations of Glc6P. Therefore, the enhanced glycolytic flux in fast-growth tumor cells was still controlled by an over-produced, but Glc6P-inhibited hexokinase. 相似文献