Classical many-body potential for concentrated alloys and the inversion of order in iron-chromium alloys

Atomistic simulations of alloys at the empirical level face the challenge of correctly modeling basic thermodynamic properties. In this Letter we propose a methodology to generalize many-body classic potentials to incorporate complex formation energy curves. Application to Fe-Cr allows us to correctly predict the order vs segregation tendency in this alloy, as observed experimentally and calculated with ab initio techniques, providing in this way a potential suitable for radiation damage studies.

Diagnostic performance of arginase activity in colorectal cancer

Arginase activity was measured in serum and biopsy from healthy individuals and colorectal cancer patients. Arginase activity in tumor samples (87 +/- 7.7 U/g tissue) was significantly higher than in controls (40.7 +/- 3.3 U/g tissue). However, serum arginase activity did not show any significant change in both groups. Finally, the micromethod used to quantify arginase activity in this study is superior to other methods because it has increased sensitivity, requires less sample, and is less time-consuming. Arginase differences are significant, according to the t-test (P<0.05)

A clinical case of canine mycotic pneumonia

A bronchopneumonic process diagnosed as mycotic in origin is described. The dog fully recovered after 120 days of treatment with ketoconazole. Determination of the serological level of anti-IgG against Aspergillus was very useful in the follow-up, because the clinical improvement of the animal was evident long before the antibody level dropped significantly.

Nitric oxide generation by soybean embryonic axes. Possible effect on mitochondrial function

Nitric oxide (NO) generation and its effect on mitochondrial enzymes were investigated in soybean embryonic axes at the onset of germination. NO was detected in homogenates from soybean embryonic axes by EPR. Enzymatic sources of NO, such as nitrate reductase activity and nitric oxide synthase, assessed as NADPH-diaphorase activity, were measured in homogenates incubated up to 48 h. Both NO content and the activity of the enzymes showed a similar profile as function of the imbibition time, with maximal levels at 15-24h. Total O2 consumption in enriched-mitochondrial fraction was inhibited by NO in a concentration-dependent manner. O2 consumption dependent on cytochrome oxidase activity was more sensitive than alternative oxidase pathway to NO exposure. Half maximal effects of NO at 0.3 and 3.6 microM were measured for cytochrome oxidase and alternative oxidase, respectively. Enriched-mitochondrial fractions from soybean embryonic axes treated with NO (up to 1 microM) showed increased H2O2 production. The data presented suggest that NO could modulate O2 consumption in soybean embryonic axes. This process could affect the pro-oxidant/antioxidant balance and the cellular energy yield in the germinating embryonic axes, and could have a role in soybean germination.

Physiological changes of Salmonella typhimurium cells under osmotic and starvation conditions by image analysis

The effects of starvation and salinity on the physiology of Salmonella typhimurium were investigated in a microcosm study. The physiological changes were monitored by using fluorochromes dyes such as DAPI (4',6-diamidino-2-phenylindole) for evaluation of the genomic content, CTC (5-cyano-2,3-ditolyl tetrazolium chloride) for respiratory activity and syto 9 and propidium iodide for cytoplasmic membrane damages. The metabolic activity of the cellular population was assessed with the method of Kogure (direct viable count), to enumerate the substrate-responsive cells. These different staining procedures were objectively analysed by an image analysis system. This paper describes the progressive alteration of Salmonella typhimurium physiology under salinity and starvation conditions.

Viability and virulence of experimentally stressed nonculturable Salmonella typhimurium

Maintenance of pathogenicity of viable but nonculturable Salmonella typhimurium cells experimentally stressed with UV-C and seawater, was investigated relative to the viability level of the cellular population. Pathogenicity, tested in a mouse model, was lost concomitantly with culturability, whereas cell viability remained undamaged, as determined by respiratory activity and cytoplasmic membrane and genomic integrities.

Effect of in vivo iron supplementation on oxygen radical production by soybean roots

Both total iron content and the in vitro rate of iron reduction were higher in roots grown in the presence of exogenously added iron (up to 500 microM) than in roots grown in absence of supplemented iron. In vivo generation of reactive O2 species by intact roots was assessed employing 2',7'-dichlorofluorescein diacetate oxidation to a fluorescent product. Roots developed in the presence of 500 microM Fe-EDTA, showed significantly increased fluorescence (64%), as compared to roots developed in absence of added iron, suggesting that iron supplementation led to oxidative stress in vivo. At the subcellular level, iron content and Fe-EDTA reduction rate were significantly increased in microsomes isolated from roots developed in the presence of exogenously added iron, as compared to microsomes from roots grown in the absence of iron. Microsomes from Fe supplemented plants exhibited a 51% increase in 2',7'-dichlorofluorescein diacetate oxidation rate, a 55% increase in superoxide anion generation, and a four-fold increase in hydroxyl radical production as compared to controls. Iron supplementation did not affect the activity of antioxidant enzymes or the content of total thiols, however alpha-tocopherol content was significantly decreased in the homogenates and the microsomes isolated from roots supplemented with iron, as compared with values in roots developed in absence of iron. These data suggest that in vivo iron supplementation increased oxygen radical generation.

Oxidative Stress Affects [alpha]- Tocopherol Content in Soybean Embryonic Axes upon Imbibition and following Germination

The content of [alpha]-tocopherol ([alpha]T) in isolated soybean (Glycine max, var Hood) embryonic axes was measured upon germination. Dry, high-vigor axes contained 1.2 [plus or minus] 0.1, nmol/axis and after an increase during the initial 6 h of imbibition, there was a decline to 1.0 [plus or minus] 0.1 nmol/axis at 24 h of incubation. Incubation in the presence of the redox-cycling agent paraquat (4 mM) for 24 h increased the [alpha]T content to 1.9 [plus or minus] 0.2 nmol/axis. When the incubation medium was supplemented with 500 [mu]M Fe-EDTA over 24 h, the content of [alpha]T increased to 1.8 [plus or minus] 0.1 nmol/axis. Isolated axes from soybean seeds stored for 56 months contained 6.5 [plus or minus] 0.3 nmol of [alpha]T/axis after 24 h of imbibition as compared to 1.0 [plus or minus] 0.1 nmol of [alpha]T/axis in axes from soybean seeds stored for 8 months. In all of these experimental situations, oxidant production as assessed in vivo by a fluorometric assay was increased by 4 mM paraquat (8-fold), 500 [mu]M iron (2-fold), and 56 months of storage (4-fold) after 24 h of imbibition. The data presented here suggest that the cellular content of [alpha]T is physiologically adjusted as a response to conditions of oxidative stress.