Effect of diethylstilbesterol and prolactin on the induction of follicle stimulating hormone receptors in immature and cycling rats

Induction of follicle stimulating hormone receptor in the granulosa cells of intact immature rat ovary by diethylstilbesterol, an estrogen, has been studied. A single injection of 4 mg of diethylstilbesterol produced 72 h later a 3-fold increase in follicle stimulating hormone receptor concentration as monitored by [125I]-oFSH binding to isolated cells. The newly induced receptors were kinetically indistinguishable from the preexisting ones, as determined by Lineweaver-Burk plot of the binding data. The induced receptors were functional as evidenced by increased ability of the granulosa cells to incorporate [3H]-leucine into cellular proteins. Neutralization of endogenous follicle stimulating hormone and luteinizing hormone by administering specific antisera had no effect on the ability of diethylstilbesterol to induce follicle stimulating hormone receptors, whereas blockade of endogenous prolactin secretion by ergobromocryptin administration significantly inhibited (∼ 30 %) the response to diethylstilbesterol; this inhibition could be completely relieved by ovine prolactin treatment. However, ovine prolactin at the dose tried did not by itself enhance follicle stimulating hormone receptor level. Administration of ergobromocryptin to adult cycling rats at noon of proestrus brought about as measured on diestrusII, (a) a reduction of both follicle stimulating hormone (∼ 30 %) and luteinizing hormone (∼ 45 %) receptor concentration in granulosa cells, (b) a drastic reduction in the ovarian tissue estradiol with no change in tissue progesterone and (c) reduction in the ability of isolated granulosa cells to convert testosterone to estradiol in response to follicle stimulating hormone. Ergobromocryptin treatment affected only prolactin and not follicle stimulating hormone or luteinizing hormone surges on the proestrus evening. Treatment of rats with ergobromocryptin at proestrus noon followed by an injection of ovine prolactin (1 mg) at 1700 h of the same day completely reversed the ergobromocryptin induced reduction in ovarian tissue estradiol as well as the aromatase activity of the granulosa cells on diestrus II, thus suggesting a role for proestrus prolactin surge in the follicular maturation process.

Roundabout design guidelines and cycling safety

Review conducted as part of a Queensland Department of Transport and Main Roads funded project ‘Roundabout design review’. The project examined: - Design guidelines - Factors that affect safety at roundabouts

Adriamycin affects plasma membrane redox functions

Adriamycin (Doxorubicin) stimulates NADH oxidase activity in liver plasma membrane, but does not cause NADH oxidase activity to appear where it is not initially present, as in erythrocyte membrane. NADH dehydrogenase from rat liver and erythrocyte plasma membranes shows similar adriamycin effects with other electron acceptors. Both NADH ferricyanide reductase and vanadate-stimulated NADH oxidation are inhibited by adriamycin, as is a cyanide insensitive ascorbate oxidase activity, whereas NADH cytochrome c reductase is not affected. The effects may contribute to the growth inhibitory (control) and/or deleterious effects of adriamycin. It is clear that adriamycin effects on the plasma membrane dehydrogenase involve more than a simple catalysis of superoxide formation.

Curing And Thermal Cycling Processes In Pvc Graphite Thick-Films

Abstract is not available.

Plant secondary compounds and soil microbial processes in carbon and nitrogen cycling in relation to tree species

The aim of this study was to explore soil microbial activities related to C and N cycling and the occurrence and concentrations of two important groups of plant secondary compounds, terpenes and phenolic compounds, under silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.) as well as to study the effects of volatile monoterpenes and tannins on soil microbial activities. The study site, located in Kivalo, northern Finland, included ca. 70-year-old adjacent stands dominated by silver birch, Norway spruce and Scots pine. Originally the soil was very probably similar in all three stands. All forest floor layers (litter (L), fermentation layer (F) and humified layer (H)) under birch and spruce showed higher rates of CO2 production, greater net mineralisation of nitrogen and higher amounts of carbon and nitrogen in microbial biomass than did the forest floor layers under pine. Concentrations of mono-, sesqui-, di- and triterpenes were higher under both conifers than under birch, while the concentration of total water-soluble phenolic compounds as well as the concentration of condensed tannins tended to be higher or at least as high under spruce as under birch or pine. In general, differences between tree species in soil microbial activities and in concentrations of secondary compounds were smaller in the H layer than in the upper layers. The rate of CO2 production and the amount of carbon in the microbial biomass correlated highly positively with the concentration of total water-soluble phenolic compounds and positively with the concentration of condensed tannins. Exposure of soil to volatile monoterpenes and tannins extracted and fractionated from spruce and pine needles affected carbon and nitrogen transformations in soil, but the effects were dependent on the compound and its molecular structure. Monoterpenes decreased net mineralisation of nitrogen and probably had a toxic effect on part of the microbial population in soil, while another part of the microbes seemed to be able to use monoterpenes as a carbon source. With tannins, low-molecular-weight compounds (also compounds other than tannins) increased soil CO2 production and nitrogen immobilisation by soil microbes while the higher-molecular-weight condensed tannins had inhibitory effects. In conclusion, plant secondary compounds may have a great potential in regulation of C and N transformations in forest soils, but the real magnitude of their significance in soil processes is impossible to estimate.

Cadmium stress alters the redox reaction and hormone balance in oilseed rape (Brassica napus L.) leaves

In order to understand the physiological response of oilseed rape (Brassica napus L.) leaves to cadmium (Cd) stress and exploit the physiological mechanisms involved in Cd tolerance, macro-mineral and chlorophyll concentrations, reactive oxygen species (ROS) accumulation, activities of enzymatic antioxidants, nonenzymatic compounds metabolism, endogenous hormonal changes, and balance in leaves of oilseed rape exposed to 0, 100, or 200 μM CdSO4 were investigated. The results showed that under Cd exposure, Cd concentrations in the leaves continually increased while macro-minerals and chlorophyll concentrations decreased significantly. Meanwhile, with increased Cd stress, superoxide anion (O 2 • − ) production rate and hydrogen peroxide (H2O2) concentrations in the leaves increased significantly, which caused malondialdehyde (MDA) accumulation and oxidative stress. For scavenging excess accumulated ROS and alleviating oxidative injury in the leaves, the activity of enzymatic antioxidants, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), was increased significantly at certain stress levels. However, with increased Cd stress, the antioxidant enzyme activities all showed a trend towards reduction. The nonenzymatic antioxidative compounds, such as proline and total soluble sugars, accumulated continuously with increased Cd stress to play a long-term role in scavenging ROS. In addition, ABA levels also increased continuously with Cd stress while ZR decreased and the ABA/ZR ratio increased, which might also be providing a protective role against Cd toxicity.

Catalyst effectiveness factor for redox model kinetic equation

A generalized isothermal effectiveness factor correlation has been proposed for catalytic reactions whose intrinsic kinetics are based on the redox model. In this correlation which is exact for asymptotic values of the Thiele parameter the effect of the parameters appearing in the model, the order of the reaction and particle geometry are incorporated in a modified form of Thiele parameter. The relationship takes the usual form: Image and predicts effectiveness factor with an error of less than 2% in a range of Thiele parameter that accommodates both the kinetic and diffusion control regimes.

Below-ground processes in meadow soil under elevated ozone and carbon dioxide : - Greenhouse gas fluxes, N cycling and microbial communities

This thesis focuses on how elevated CO2 and/or O3 affect the below-ground processes in semi-natural vegetation, with an emphasis on greenhouse gases, N cycling and microbial communities. Meadow mesocosms mimicking lowland hay meadows in Jokioinen, SW Finland, were enclosed in open-top chambers and exposed to ambient and elevated levels of O3 (40-50 ppb) and/or CO2 (+100 ppm) for three consecutive growing season, while chamberless plots were used as chamber controls. Chemical and microbiological analyses as well as laboratory incubations of the mesocosm soils under different treatments were used to study the effects of O3 and/or CO2. Artificially constructed mesocosms were also compared with natural meadows with regards to GHG fluxes and soil characteristics. In addition to research conducted at the ecosystem level (i.e. the mesocosm study), soil microbial communities were also examined in a pot experiment with monocultures of individual species. By comparing mesocosms with similar natural plant assemblage, it was possible to demonstrate that artificial mesocosms simulated natural habitats, even though some differences were found in the CH4 oxidation rate, soil mineral N, and total C and N concentrations in the soil. After three growing seasons of fumigations, the fluxes of N2O, CH4, and CO2 were decreased in the NF+O3 treatment, and the soil NH4+-N and mineral N concentrations were lower in the NF+O3 treatment than in the NF control treatment. The mesocosm soil microbial communities were affected negatively by the NF+O3 treatment, as the total, bacterial, actinobacterial, and fungal PLFA biomasses as well as the fungal:bacterial biomass ratio decreased under elevated O3. In the pot survey, O3 decreased the total, bacterial, actinobacterial, and mycorrhizal PLFA biomasses in the bulk soil and affected the microbial community structure in the rhizosphere of L. pratensis, whereas the bulk soil and rhizosphere of the other monoculture, A. capillaris, remained unaffected by O3. Elevated CO2 caused only minor and insignificant changes in the GHG fluxes, N cycling, and the microbial community structure. In the present study, the below-ground processes were modified after three years of moderate O3 enhancement. A tentative conclusion is that a decrease in N availability may have feedback effects on plant growth and competition and affect the N cycling of the whole meadow ecosystem. Ecosystem level changes occur slowly, and multiplication of the responses might be expected in the long run.

Redox-linked proton transfer by cytochrome c oxidase

The respiratory chain is found in the inner mitochondrial membrane of higher organisms and in the plasma membrane of many bacteria. It consists of several membrane-spanning enzymes, which conserve the energy that is liberated from the degradation of food molecules as an electrochemical proton gradient across the membrane. The proton gradient can later be utilized by the cell for different energy requiring processes, e.g. ATP production, cellular motion or active transport of ions. The difference in proton concentration between the two sides of the membrane is a result of the translocation of protons by the enzymes of the respiratory chain, from the negatively charged (N-side) to the positively charged side (P-side) of the lipid bilayer, against the proton concentration gradient. The endergonic proton transfer is driven by the flow of electrons through the enzymes of the respiratory chain, from low redox-potential electron donors to acceptors of higher potential, and ultimately to oxygen. Cytochrome c oxidase is the last enzyme in the respiratory chain and catalyzes the reduction of dioxygen to water. The redox reaction is coupled to proton transport across the membrane by a yet unresolved mechanism. Cytochrome c oxidase has two proton-conducting pathways through which protons are taken up to the interior part of the enzyme from the N-side of the membrane. The K-pathway transfers merely substrate protons, which are consumed in the process of water formation at the catalytic site. The D-pathway transfers both substrate protons and protons that are pumped to the P-side of the membrane. This thesis focuses on the role of two conserved amino acids in proton translocation by cytochrome c oxidase, glutamate 278 and tryptophan 164. Glu278 is located at the end of the D-pathway and is thought to constitute the branching point for substrate and pumped protons. In this work, it was shown that although Glu278 has an important role in the proton transfer mechanism, its presence is not an obligatory requirement. Alternative structural solutions in the area around Glu278, much like the ones present in some distantly related heme-copper oxidases, could in the absence of Glu278 support the formation of a long hydrogen-bonded water chain through which proton transfer from the D-pathway to the catalytic site is possible. The other studied amino acid, Trp164, is hydrogen bonded to the ∆-propionate of heme a3 of the catalytic site. Mutation of this amino acid showed that it may be involved in regulation of proton access to a proton acceptor, a pump site, from which the proton later is expelled to the P-side of the membrane. The ion pair that is formed by the ∆-propionate of heme a3 and arginine 473 is likely to form a gate-like structure, which regulates proton mobility to the P-side of the membrane. The same gate may also be part of an exit path through which water molecules produced at the catalytically active site are removed towards the external side of the membrane. Time-resolved optical and electrometrical experiments with the Trp164 to phenylalanine mutant revealed a so far undetected step in the proton pumping mechanism. During the A to PR transition of the catalytic cycle, a proton is transferred from Glu278 to the pump site, located somewhere in the vicinity of the ∆-propionate of heme a3. A mechanism for proton pumping by cytochrome c oxidase is proposed on the basis of the presented results and the mechanism is discussed in relation to some relevant experimental data. A common proton pumping mechanism for all members of the heme-copper oxidase family is moreover considered.

The role of lakes in carbon cycling in boreal catchments

Lakes are an important component of ecosystem carbon cycle through both organic carbon sequestration and carbon dioxide and methane emissions, although they cover only a small fraction of the Earth's surface area. Lake sediments are considered to be one of rather perma-nent sinks of carbon in boreal regions and furthermore, freshwater ecosystems process large amounts of carbon originating from terrestrial sources. These carbon fluxes are highly uncer-tain especially in the changing climate. -- The present study provides a large-scale view on carbon sources and fluxes in boreal lakes situated in different landscapes. We present carbon concentrations in water, pools in lake se-diments, and carbon gas (CO2 and CH4) fluxes from lakes. The study is based on spatially extensive and randomly selected Nordic Lake Survey (NLS) database with 874 lakes. The large database allows the identification of the various factors (lake size, climate, and catchment land use) determining lake water carbon concentrations, pools and gas fluxes in different types of lakes along a latitudinal gradient from 60oN to 69oN. Lakes in different landscapes vary in their carbon quantity and quality. Carbon (C) content (total organic and inorganic carbon) in lakes is highest in agriculture and peatland dominated areas. In peatland rich areas organic carbon dominated in lakes but in agricultural areas both organic and inorganic C concentrations were high. Total inorganic carbon in the lake water was strongly dependent on the bedrock and soil quality in the catchment, especially in areas where human influence in the catchment is low. In inhabited areas both agriculture and habitation in the catchment increase lake TIC concentrations, since in the disturbed soils both weathering and leaching are presumably more efficient than in pristine areas. TOC concentrations in lakes were related to either catchment sources, mainly peatlands, or to retention in the upper watercourses. Retention as a regulator of the TOC concentrations dominated in southern Finland, whereas the peatland sources were important in northern Finland. The homogeneous land use in the north and the restricted catchment sources of TOC contribute to the close relationship between peatlands and the TOC concentrations in the northern lakes. In southern Finland the more favorable climate for degradation and the multiple sources of TOC in the mixed land use highlight the importance of retention. Carbon processing was intensive in the small lakes. Both CO2 emission and the Holocene C pool in sediments per square meter of the lake area were highest in the smallest lakes. How-ever, because the total area of the small lakes on the areal level is limited, the large lakes are important units in C processing in the landscape. Both CO2 and CH4 concentrations and emissions were high in eutrophic lakes. High availability of nutrients and the fresh organic matter enhance degradation in these lakes. Eutrophic lakes are often small and shallow, enabling high contact between the water column and the sediment. At the landscape level, the lakes in agricultural areas are often eutrophic due to fertile soils and fertilization of the catchments, and therefore they also showed the highest CO2 and CH4 concentrations. Export from the catchments and in-lake degradation were suggested to be equally important sources of CO2 and CH4 in fall when the lake water column was intensively mixed and the transport of sub-stances from the catchment was high due to the rainy season. In the stagnant periods, especially in the winter, in-lake degradation as a gas source was highlighted due to minimal mixing and limited transport of C from the catchment. The strong relationship between the annual CO2 level of lakes and the annual precipitation suggests that climate change can have a major impact on C cycling in the catchments. Increase in precipitation enhances DOC export from the catchments and leads to increasing greenhouse gas emissions from lakes. The total annual CO2 emission from Finnish lakes was estimated to be 1400 Gg C a-1. The total lake sediment C pool in Finland was estimated to be 0.62 Pg, giving an annual sink in Finnish lakes of 65 Gg C a-1.

Effect of mechanical cycling on the stress-strain response of a martensitic Nitinol shape memory alloy

An experimental investigation into the ambient temperature, load-controlled tension�tension fatigue behavior of a martensitic Nitinol shape memory alloy (SMA) was conducted. Fatigue life for several stress levels spanning the critical stress for detwinning was determined and compared with that obtained on an alloy similar in composition but in the austenitic state at room temperature. Results show that the fatigue life of the pseudo-plastic alloy is superior to superelastic shape memory alloy. The stress�strain hysteretic response, monitored throughout the fatigue loading, reveals progressive strain accumulation with the cyclic loading. In addition, the area of hysteresis and recoverable and frictional energies were found to decrease with increasing number of fatigue cycles. Post-mortem characterization of the fatigued specimens through calorimetry and fractography was conducted in order to get further insight into the fatigue micromechanisms. These results are discussed in terms of reversible and irreversible microstructural changes that take place during cyclic loading. Aspects associated with self-heating of martensitic alloy undergoing high frequency stress cycling are discussed.

Ruthenium(II)-CO complexes of N-[(2-pyridyl)methyliden]-alpha(or beta)-aminonaphthalene: Synthesis, spectral studies, crystal structure, redox properties and DFT calculation

The characterization and properties of trans-(X)-[RuX2(CO)(2)(alpha/beta-NaiPy)] (1, 2) (alpha-NaiPy (a), beta-NaiPy (b); X = Cl (1), I (2)) are described in this work. The structures are confirmed by single crystal X-ray diffraction studies. Reaction of these compounds with Me3NO in MeCN has isolated monocarbonyl trans-(X)-RuX2(CO)(MeCN)(alpha/beta-NaiPy)] (3, 4). The complexes show intense emission properties. Quantum yields of 1 and 2 (phi= 0.02-0.08) are higher than 3 and 4 (phi = 0.006-0.015). Voltammogram shows higher Ru(III)/Ru(II) (1.3-1.5 V) potential of 1 and 2 than that of 3 and 4 (0.8-0.9 V) that may be due to coordination of two pi-acidic CO groups in former. The electronic spectra and redox properties of the complexes are compared with the results obtained by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) using polarizable continuum model (CPCM).

Electrochemical Functionalization of a Gold Electrode with Redox-Active Self-Assembled Monolayer for Electroanalytical Application

The electrochemical functionalization of a Au electrode with a redox-active monolayer and the electroanalytical applications of the functionalized electrode are described. Reaction of the electrochemically derived o-quinone on the self-assembled monolayer (SAM) of 6-mercaptopurine (MPU) on a Au electrode gives a redox-active 4-(6-mercapto-purin-9-yl)benzene-1,2-diol (MPBD) self-assembly under optimized conditions. Electrochemical quartz crystal microbalance technique has been employed to follow the functionalization of the electrode in real time. Electrochemically derived o-quinone reacts at the N(9) position of the self-assembled MPU in neutral pH. Raman spectral measurement confirms the reaction of o-quinone on MPU self-assembly. MPBD shows a well-defined reversible redox response, characteristic of a surface-confined redox mediator at 0.21 V in neutral pH. The anodic peak potential (Epa) of MPBD shifts by −60 mV while changing the solution pH by 1 unit, indicating that the redox reaction involves two electrons and two protons. The surface coverage (Γ) of MPBD was 7.2 ± 0.3 × 10-12 mol/cm2. The apparent heterogeneous rate constant (ksapp) for MPBD was 268 ± 6 s-1. MPBD efficiently mediates the oxidation of nicotinamide adenine dinucleotide (NADH) and ascorbate (AA). A large decrease in the overpotential and significant increase in the peak current with respect to the unmodified electrode has been observed. Surface-confined MPBD has been successfully used for the amperometric sensing of NADH and AA in neutral pH at the nanomolar level.