Lead toxicity in Saccharomyces cerevisiae : the role of glutathione

Lead is a non-essential metal for biological functions and is classified by the International Agency for Research on Cancer (IARC) as a probable human carcinogen. S. cerevisiae is a suitable model for studying Pb toxic effects since it is an eukaryote cell that can be easily manipulated and has a completely sequenced genome. In the present work, the role of reduced glutathione (GSH) as a defense mechanism against Pbinduced toxicity in S. cerevisiae was investigated. Yeast cells exposed to Pb (3h) lost cell viability (quantified by a clonogenic assay), accumulated intracellular reactive oxygen species (ROS) (evaluated by 2′,7′-dichlorodihydrofluorescein diacetate, H2 DCFDA) and decreased GSH level (assessed by monochlorobimane, mBCl). Yeast cells lacking the GSH1 (Dgsh1) or GSH2 (Dgsh2) genes were compared with wild type (WT) cells for loss of cell viability and Pb-induced ROS accumulation. We verified that Dgsh1 and Dgsh2 cells did not exhibit an increased loss of viability and did not experience ROS accumulation compared with WT cells. However, the treatment of WT cells with iodoacetamide (an alkylating agent which binds covalently to thiol groups) enhanced sensitivity to Pb. Incubation of WT cells with an amino acid mixture constituting GSH (L-glutamic acid, L-cysteine and glycine) reduced oxidative stress and loss of Pb-induced proliferation capacity. Together, the results suggest that intracellular GSH is involved in the defense against Pb-induced toxicity; however, it seems insufficient to sustain the oxidative stress and Pb-induced loss of cell viability

Documentation of model components EXPAMOD and CAPRI

Agricultural and Food Policy, Environmental Economics and Policy, Land Economics/Use, Production Economics,

EXPAMOD: A methodological Tool for Linking Farm and Market Models by Means of Econometric Response Functions

Technical change at the farm level or changes in input prices often entail that the firm's supply function changes. These changes can take place in numerous ways. This paper presents a methodology that increases the consistency in supply responses across various sets of agricultural products and farm types with a market model based on a statistical response function approach. Since most farm simulation models are limited to a subset of regions and farm types, the linkage to an aggregated model requires a procedure for expanding these results to non sample regions, so that full regional coverage is achieved. This paper addresses theoretical aspects related to the consistency between micro and market level models. Next it deals with some empirical findings related to the selection of different functional forms for extrapolation. We conclude with a critical reflection on applicability of this method in addressing further needs on up-scaling of other economic as well as non-economic indicators.farm models, market models, extrapolation, Farm Management,

Chiral photoelectron angular distributions from ionization of achiral atomic and molecular species

We show that the combination of two achiral components - atomic or molecular target plus a circularly polarized photon - can yield chirally structured photoelectron angular distributions. For photoionization of CO, the angular distribution of carbon K-shell photoelectrons is chiral when the molecular axis is neither perpendicular nor (anti-)parallel to the light propagation axis. In photo-double-ionization of He, the distribution of one electron is chiral, if the other electron is oriented like the molecular axis in the former case and if the electrons are distinguishable by their energy. In both scenarios, the circularly polarized photon defines a plane with a sense of rotation and an additional axis is defined by the CO molecule or one electron. This is sufficient to establish an unambiguous coordinate frame of well-defined handedness. To produce a chirally structured electron angular distribution, such a coordinate frame is necessary, but not sufficient. We show that additional electron-electron interaction or scattering processes are needed to create the chiral angular distribution

Suicide methods in Europe: a gender-specific analysis of countries participating in the "European Alliance Against Depression"

Objective: To identify the most frequent gener-specific suicide methods in Europe. Design: Proportions of seven predominant suicide methods utilised in 16 countries participating in the European Alliance Against Depression (EAAD)were reported in total and cross-nationally. Relative risk (RR)relating to suicide methods and gender was calculated. To group countries by pattern of suicide methods, hierarchical clustering was applied. Setting and participants: Data on suicide methods for 119 122 male and 41 338 female cases in 2000-4/5 from 16 EAAD countries, covering 52% of European population were obtained. Results: Hanging was the most prevalent suicide method among both males (54.3%) and females (35.6%). For males, hanging was followed by firearms (9.7%) and poisoning by drugs (8.6%); for females, by poisoning by drugs (24.7%)and jumping from a high place (14.5%). Only in Switzerland did hanging rank as second for males after firearms. Hanging ranked first among females in eight countries, poisoning by drugs in five and jumping from a high place in three. In all countries, males had a higher risk than females of using firearms and hanging and a lower risk of poisoning by drugs, drowning and jumping. Grouping showed that countries might be divided into five main groups among males; for females, grouping did not yield clear results. Conclusions: Research on suicide methods could lead to the development of gender-specific intervention strategies. Nevertheless, other approaches, such as better identification and treatment of mental disorders and the improvement of toxicological aid should be put in place

Prospectus, March 15, 1989

https://spark.parkland.edu/prospectus_1989/1005/thumbnail.jp

Optical Light Curve of the Type Ia Supernova 1998bu in M96 and the Supernova Calibration of the Hubble Constant

We present the UBVRI light curves of the Type Ia supernova SN 1998bu which appeared in the nearby galaxy M96 (NGC 3368). M96 is a spiral galaxy in the Leo I group which has a Cepheid-based distance. Our photometry allows us to calculate the absolute magnitude and reddening of this supernova. These data, when combined with measurements of the four other well-observed supernovae with Cepheid based distances, allow us to calculate the Hubble constant with respect to the Hubble flow defined by the distant Calan/Tololo Type Ia sample. We find a Hubble constant of 64.0 +/- 2.2(internal) +/- 3.5(external) km/s/Mpc, consistent with most previous estimates based on Type Ia supernovae. We note that the two well-observed Type Ia supernovae in Fornax, if placed at the Cepheid distance to the possible Fornax spiral NGC 1365, are apparently too faint with respect to the Calan/Tololo sample calibrated with the five Type Ia supernovae with Cepheid distances to the host galaxies.Comment: AAS LaTeX, 20 pages, 4 figures, 6 tables, accepted for publication in the Astronomical Journal. Figure 1 (finding chart) not include

Associating optical measurements of MEO and GEO objects using Population-Based Meta-Heuristic methods

Currently several thousands of objects are being tracked in the MEO and GEO regions through optical means. The problem faced in this framework is that of Multiple Target Tracking (MTT). The MTT problem quickly becomes an NP-hard combinatorial optimization problem. This means that the effort required to solve the MTT problem increases exponentially with the number of tracked objects. In an attempt to find an approximate solution of sufficient quality, several Population-Based Meta-Heuristic (PBMH) algorithms are imple- mented and tested on simulated optical measurements. These first results show that one of the tested algorithms, namely the Elitist Genetic Algorithm (EGA), consistently displays the desired behavior of finding good approximate solutions before reaching the optimum. The results further suggest that the algorithm possesses a polynomial time complexity, as the computation times are consistent with a polynomial model. With the advent of improved sensors and a heightened interest in the problem of space debris, it is expected that the number of tracked objects will grow by an order of magnitude in the near future. This research aims to provide a method that can treat the association and orbit determination problems simultaneously, and is able to efficiently process large data sets with minimal manual intervention

Spin Foam Models of Riemannian Quantum Gravity

Using numerical calculations, we compare three versions of the Barrett-Crane model of 4-dimensional Riemannian quantum gravity. In the version with face and edge amplitudes as described by De Pietri, Freidel, Krasnov, and Rovelli, we show the partition function diverges very rapidly for many triangulated 4-manifolds. In the version with modified face and edge amplitudes due to Perez and Rovelli, we show the partition function converges so rapidly that the sum is dominated by spin foams where all the spins labelling faces are zero except for small, widely separated islands of higher spin. We also describe a new version which appears to have a convergent partition function without drastic spin-zero dominance. Finally, after a general discussion of how to extract physics from spin foam models, we discuss the implications of convergence or divergence of the partition function for other aspects of a spin foam model.Comment: 23 pages LaTeX; this version to appear in Classical and Quantum Gravit