954 resultados para INDUCED RESPIRATORY DEPRESSION
Resumo:
Historical sediment nutrient concentrations and heavy-metal distributions were studied in five embayments in the Gulf of Finland and an adjacent lake. The main objective of the study was to examine the response of these water bodies to temporal changes in human activities. Sediment cores were collected from the sites and dated using 210Pb and 137Cs. The cores were analyzed for total carbon (TC), total nitrogen (TN), total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP), biogenic silica (BSi), loss on ignition (LOI), grain size, Cu, Zn, Al, Fe, Mn, K, Ca, Mg and Na. Principal component analysis (PCA) was used to summarize the trends in the geochemical variables and to compare trends between the different sites. The links between the catchment land use and sediment geochemical data were studied using a multivariate technique of redundancy analysis (RDA). Human activities produce marked geochemical variations in coastal sediments. These variations and signals are often challenging to interpret due to various sedimentological and post-depositional factors affecting the sediment profiles. In general, the sites studied here show significant upcore increases in sedimentation rates, TP and TN concentrations. Also Cu, which is considered to be a good indicator of anthropogenic influence, showed clear increases from 1850 towards the top part of the cores. Based on the RDA-analysis, in the least disturbed embayments with high forest cover, the sediments are dominated by lithogenic indicators Fe, K, Al and Mg. In embayments close to urban settlement, the sediments have high Cu concentrations and a high sediment Fe/Mn ratio. This study suggests that sediment accumulation rates vary significantly from site to site and that the overall sedimentation can be linked to the geomorphology and basin bathymetry, which appear to be the major factors governing sedimentation rates; i.e. a high sediment accumulation rate is not characteristic either to urban or to rural sites. The geochemical trends are strongly site specific and depend on the local geochemical background, basin characteristics and anthropogenic metal and nutrient loading. Of the studied geochemical indicators, OP shows the least monotonic trends in all studied sites. When compared to other available data, OP seems to be the most reliable geochemical indicator describing the trophic development of the study sites, whereas Cu and Zn appear to be good indicators for anthropogenic influence. As sedimentation environments, estuarine and marine sites are more complex than lacustrine basins with multiple sources of sediment input and more energetic conditions in the former. The crucial differences between lacustrine and estuarine/coastal sedimentation environments are mostly related to Fe. P sedimentation is largely governed by Fe redox-reactions in estuarine environments. In freshwaters, presence of Fe is clearly linked to the sedimentation of other lithogenic metals, and therefore P sedimentation and preservation has a more direct linkage to organic matter sedimentation.
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Recently argued that observed positive relationships between dingoes and small mammals were a result of top-down processes whereby lethal dingo control reduced dingoes and increased mesopredators and herbivores, which then suppressed small mammals. Here, I show that the prerequisite negative effects of dingo control on dingoes were not shown, and that the same positive relationships observed may simply represent well-known bottom-up processes whereby more generalist predators are found in places with more of their preferred prey. Identification of top-predator controlinduced trophic cascades first requires demonstration of some actual effect of control on predators, typically possible only through manipulative experiments with the ability to identify cause and effect.
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The homogeneous serine hydroxymethyltransferase from monkey liver was optimally activate at 60°C and the Arrhenius plot for the enzyme was nonlinear with a break at 15°C. The monkey liver enzyme showed high thermal stability of 62°C, as monitored by circular dichroism at 222 nm, absorbance at 280 nm and enzyme activity. The enzyme exhibited a sharp co-operative thermal transition in the range of 50°-70° (Tm= 65°C), as monitored by circular dichroism. L-Serine protected the enzyme against both thermal inactivation and thermal disruption of the secondary structure. The homotropic interactions of tetrahydrofolate with the enzyme was abolished at high temperatures (at 70°C, the Hill coefficient value was 1.0). A plot of h values vs. assay temperature of tetrahydrofolate saturation experiments, showed the presence of an intermediate conformer with an h value of 1.7 in the temperature range of 45°-60°C. Inclusion of a heat denaturation step in the scheme employed for the purification of serine hydroxymethyltransferase resulted in the loss of cooperative interactions with tetrahydrofolate. The temperature effects on the serine hydroxylmethyltransferase, reported for the first time, lead to a better understanding of the heat induced alterations in conformation and activity for this oligomeric protein.
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Carotenoids prevent different degenerative diseases and improve human health. Microalgae are commercially exploited for carotenoids, including astaxanthin and β-carotene. Two commercially important microalgae, Dunaliella salina and Tetraselmis suecica, were treated with plant hormones salicylic acid (SA) and methyl jasmonate (MJ), or by UV-C radiation (T. suecica only) and a combination thereof. Significant increases in total carotenoids were found for D. salina and T. suecica after treatment with MJ (10 μmol/L) and SA (70–250 μmol/L), respectively. T. suecica also had significant increases in total carotenoids following UV-C radiation compared to control cultures. Among the carotenoids, lutein was the highest induced carotenoid. A combination of these two treatments also showed a significant increase in total carotenoids and lutein for T. suecica, when compared to controls. Plant hormones and UV-C radiation may be useful tools for increasing carotenoid accumulation in green microalgae although the responses are species- and dose-specific and should be trialed in medium to large scale to explore commercial production.
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The frequency-dependent response of a pinned charge density wave is considered in terms of forced vibration of an oscillator held in an anharmonic well. It is shown that the effective pinning-frequency can be reduced by applying a d.c. field. If a strong a.c. field, superposed on a d.c. field is applied on such a system “jumps” can be observed in the frequency dependent response of the system. The conditions at which these “jumps” occur are investigated with reference to NbSe3. The possibility of observing such phenomena in other systems like superionic conductors, non-linear dielectrics like ferroelectrics is pointed out. The characteristics are expressed in terms of some “scaled variables” — in terms of which the characteristics show a universal behaviour
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The comparative role of luteinizing hormone (LH) in maintaining pregnancy and histamine-induced decidualization in the rat was studied with the help of a new system, wherein the above two states could be brought about simultaneously in the same animal, but in different uterine horns. Specific and well-characterized LH antiserum, administered daily, both during the pre-trauma (days 1-4) and post-trauma (days 5-8) periods, resulted in the termination of pregnancy and inhibition of decidualization. This antiserum effect could be reversed by suitable steroid therapy. Results suggest that the antiserum blockade of ovarian steroidogenesis continued even after cessation of its treatment. Early pregnancy and decidualization seem directly comparable in that both are dependent upon LH to stimulate the ovarian synthesis of much-needed progesterone and estrogen.
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Increased consumption of dark-coloured fruits and vegetables may mitigate metabolic syndrome. This study has determined the changes in metabolic parameters, and in cardiovascular and liver structure and function, following chronic administration of either cyanidin 3-glucoside (CG) or Queen Garnet plum juice (QG) containing cyanidin glycosides to rats fed either a corn starch (C) or a high-carbohydrate, high-fat (H) diet. Eight to nine-week-old male Wistar rats were randomly divided into six groups for 16-week feeding with C, C with CG or QG, H or H with CG or QG. C or H were supplemented with CG or QG at a dose of ∼8 mg/kg/day cyanidin glycosides from week 8 to 16. H rats developed signs of metabolic syndrome including visceral adiposity, impaired glucose tolerance, hypertension, cardiovascular remodelling, increased collagen depots in left ventricle, non-alcoholic fatty liver disease, increased plasma liver enzymes and increased inflammatory cell infiltration in the heart and liver. Both CG and QG reversed these cardiovascular, liver and metabolic signs. However, no intact anthocyanins or common methylated/conjugated metabolites could be detected in the plasma samples and plasma hippuric acid concentrations were unchanged. Our results suggest CG is the most likely mediator of the responses to QG but that further investigation of the pharmacokinetics of oral CG in rats is required.
Resumo:
Water stress resulted in a specific response leading to a large and significant increase (80-fold) in free proline content of ragi (Eleusine coracana) leaves and seedlings. L-Proline protected ornithine aminotransferase, an enzyme in the pathway for proline biosynthesis, isolated from normal and stressed ragi leaves against heat inactivation and denaturation by urea and guanidinium chloride. The protection of the stressed enzyme by L-proline was much more complete than that of the enzyme isolated from normal leaves. While L-ornithine, one of the substrates, protected the stressed enzyme against inactivation, it enhanced the rate of inactivation of the normal enzyme. α-Ketoglutarate protected both the normal and stressed enzyme against inactivation and denaturation. These results support the suggestion that ornithine aminotransferase has undergone a structural alteration during water stress. In view of the causal relationship between elevated temperature and water stress of plants under natural conditions, the protection afforded by proline against inactivation and denaturation of the enzyme from stressed leaves assumes significance. These results provide an explanation for a possible functional importance of proline accumulation during water stress.
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Lamb suckling has been suggested to be an important way of infecting a ewe's udder with different bacteria, including Mannheimia haemolytica. To test the potential role of lambs in transferring Mannheimia species to the ewe’s udder, the restriction endonuclease cleavage patterns of isolates obtained from nasopharyngeal swabs were compared with those obtained from cases of mastitis. Sterile cotton swabs were used to collect nasopharyngeal samples from 50 ewes and 36 lambs from three flocks. M. haemolytica and Mannheimia glucosida as well as haemolytic Mannheimia ruminalis-like organisms were detected in the upper respiratory tract of lambs and ewes. Comparison of the restriction endonuclease cleavage patterns of the isolates suggested that the M. haemolytica isolates obtained from different milk samples from ewes with mastitis were more clonal than those obtained from the nasal swabs. However, some nasal isolates within both Mannheimia species had restriction endonuclease cleavage patterns identical to those obtained from milk samples from ewes with mastitis, indicating that lambs may have a role in transferring these organisms to the udder. More clonality was observed between the M. glucosida isolates than between M. haemolytica isolates.
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In this paper we study the phonon-induced exciton-exciton interaction. It is found that the interaction can be attractive under certain conditions. Taking into account this attractive interaction, the pairing of excitons with opposite momenta is studied and the excitation spectrum determined. The results are similar to a system of bosons. There appears to be some possibility of superfluid behaviour.
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Chlamydia trachomatis infections can result in the development of serious sequelae such as pelvic inflammatory disease and tubal infertility. In this study, peripheral blood mononuclear cells from women who were undergoing or had recently undergone IVF treatment were cultured ex vivo with C. trachomatis to identify the immune responses associated with women who had serological evidence of a history of Chlamydia infection. Cytokines secreted into the supernatant from the cultures were measured using ELISA, and the level of IL-1β was found to be significantly higher in Chlamydia positive women than Chlamydia negative women. qRT-PCR analysis of the expression of 88 immune-related genes showed trends towards an upregulation of CXCL10, CXCL11 and HLA-A in Chlamydia positive women compared with Chlamydia negative women. These findings support that some women launch a more marked proinflammatory response upon infection with C. trachomatis and this may be associated with why C. trachomatis induces infertility in some infected women.
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Orgasm is a subjective experience accompanied by involuntary muscle contractions. We hypothesized that orgasm in women would be distinguishable by frequency analysis of a perineal muscle-derived signal. Rectal pressure, an index of perineal muscle activity, was measured continuously in 23 healthy women during different sexual tasks: receiving clitoral stimulation, imitation of orgasm, and attempt to reach orgasm, in which case the women were asked to report whether orgasm had been reached ("orgasm") or not ("failed orgasm attempt"). We performed spectral analysis on the rectal pressure data and calculated the spectral power in the frequency bands delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), and beta (13-25 Hz). The most significant and most important difference in spectral power between orgasm and both control motor tasks (imitation of orgasm and failed orgasm attempt) was found in the alpha band. An objective rule based on spectral power in the alpha band recognized 94% (29/31) of orgasms and correctly labeled 69% (44/64) of all orgasm attempts as either successful or failed. Because outbursts of alpha fluctuations in rectal pressure only occurred during orgasm and not during voluntary imitation of orgasm or failed attempts, we propose that they represent involuntary contractions of muscles in the rectal vicinity. This is the first objective and quantitative measure that has a strong correspondence with the subjective experience of orgasm.
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The kinetics of estrogen-induced elevation in the plasma concentration of riboflavin-binding protein, a minor yolk constituent, was investigated in immature male chicks, using a specific and sensitive radioimmunoassay proceudre. Following a single injection of the hormone, the plasma riboflavin-binding protein content was enhanced several-fold at 6 h. reaching peak levels around 48 h and declining thereafter. A two-fold amplication of the response was evident on secondary stimulation with the hormone. A 4-h lag phase prior to onset of induction was noticed during both primary and secondary stimulat ions with the steroid hormone. The magnitude of the response was dependent on the hormonal dose whereas the initial lag phase and the time of peak riboflavin-binding protein accumulation were unaltered within the range of hormonal doses tested. The half-life of riboflavin-binding protein in the circulation was 10 h, as calculated from measurement of the rate of disappearance of exogenously administered 125I-labelled protein. Simultaneous administration of progestrone did bot affect the kinetics of riboflavin-binding protein production. On the other hand, the antiestrogens, cis- and trans-clomiphene citrates, given 30 min prior to estrogen and cycloheximide, effectively countered the hormone-induced riboflavin-binding protein elaboration. Both progesterone and the anti-esterogens per se were completely ineffective in substituting for estrogen in the inductive ptrocess.
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On the material level of poverty, the work shows how the Great Depression forced rural women and children to enhance their work input and find new ways of coping. The most serious impact of the Depression was poor nutrition, as well as scarcity of food and clothes. Women's and men's ways to make a living started to resemble each other; men had also to consent to wages in form of foodstuff. The research also focuses on immaterial poverty by means of exploring experiences of otherness: shame, hatred and expressions of protest. Substantial humiliation was induced by poor relief and begging. A clear gap prevailed between the poor and the better off people in school, work and at leisure. The economic crisis deepened this gap even further. The dissertation specifies the poor people s every day experiences by taking into account the different worlds of men and women. The analysis of four different memory-based sources is the core in the micro-historical research design. The narrators of the research were survivors, unlike many others, who experienced the Great Depression. Moralization and humiliation of the poor have not ceased in contemporary society. Therefore, the historical perspective of both the material and the immaterial side of poverty could increase the understanding of the multifaceted phenomenon of today s poverty.
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Airport runway pavement always subjected to huge impact loading due to the hard landing of aircraft on the pavement surface. Therefore runway pavements should have sufficient impact resistance capability to avoid damage causing by hard impact like surface deflection in downward or penetration since the repair works is cumbersome within the operating condition of airport and also increases the service life cost of the pavement structure. Several research works have been carried out on airport runway pavement to measure the present condition of pavement and also to predict future performance of it. However, most of the works are confined by pavement response under moving aircraft loading. Nevertheless, no comprehensive research work is yet conducted to identify the controlling factors which might have significant effect in changing the common pavements damage like surface penetration depth under impact of aircraft. Therefore, a 3D FE study is conducted to determine some effective factors in controlling the top surface penetration depth of runway pavement. Among the exterior factors, mass of the impactor, velocity of the impactor, impact angle and boundary conditions are selected and as interior factors, thickness of the runway pavement, compressive strength and density of materials used in the runway pavement are selected.