Synthesis and Release of Dopamine in Rat Striatal Slices: Requirement for Exogenous Tyrosine in the Medium

When incubated in a tyrosine-free medium, the tissue dopamine (DA) level of rat striatal slices increased by about 921 ± 15 pmol/mg protein during 90 min of preincubation. In contrast, the tissue-free tyrosine level declined only 130 pmol/mg protein in the same assay period. Depolarization of the slices with high K⁺ increased both DA and DOPAC outputs and depleted tissue DA level by about 75%. Although 60 min of resting after high K⁺ depolarization significantly restored the tissue DA levels, neither this restoration nor depolarization-induced DA release was altered by exogenous tyrosine. Similarly, failure of exogenous tyrosine was also observed during three successive depolarization periods of striatal slices. These results indicate that nigrostriatal dopaminergic neurons are able to synthesize and release the DA in the absence of exogenous tyrosine in the medium. Since the free tyrosine level in the slices does not seem to be a sufficient source, it is likely that tyrosine mobilized from its bound source(s) supports the DA synthesis under in vitro experimental conditions.     

The Wittig-cyclization procedure: acid promoted intramolecular formation of 3-C-branched-chain 3,6-anhydro furano sugars via 2'-oxopropylene derivatives

Some olefinic Wittig products, 3-deoxy-5,6-O-isopropylidene-3-C-(2'-oxopropylene)-1,2-O-alkylidene hexofuranose derivatives were converted to the branched-chain 3,6-anhydro-3-C-(2'-oxopropyl) derivatives on treatment with ion exchange resin Amberlite 120 (H(+)) in methanol-water at room temperature. Hydrolysis of 5,6-isopropylidene groups and intramolecular ring-closures took place in one pot reactions.     

Immobilization of tyrosinase and alcohol oxidase in conducting copolymers of thiophene functionalized poly(vinyl alcohol) with pyrrole

Immobilization of tyrosinase and alcohol oxidase is achieved in the copolymer of pyrrole with vinyl alcohol with thiophene side groups (PVATh-co-PPy) which is a newly synthesized conducting polymer. PVATh-co-PPy/alcohol oxidase and PVATh-co-PPy/tyrosinase electrodes are constructed by the entrapment of enzyme in conducting copolymer matrix during electrochemical copolymerization. For tyrosinase and alcohol oxidase enzymes, catechol and ethanol are used as the substrates, respectively. Kinetic parameters: maximum reaction rates (V(max)) and Michaelis-Menten constants (K(m)) are obtained. V(max) and K(m) are found as 2.75 micromol/(minelectrode) and 18 mM, respectively, for PVATh-co-PPy/alcohol oxidase electrode and as 0.0091micromol/(minelectrode) and 40 mM, respectively, for PVATh-co-PPy/tyrosinase electrode. Maximum temperature and pH values are investigated and found that both electrodes have a wide working range with respect to both temperature and pH. Operational and storage stabilities show that although they have limited storage stabilities, the enzyme electrodes are useful with respect to operational stabilities.     

Functions and oxidative stress status of leukocytes in patients with nephrotic syndrome

This study was conducted to establish the functions and oxidative stress status in leukocytes of adult patients with nephrotic syndrome. Thirty adult patients with nephrotic syndrome and 32 controls were included. Phagocytosis ability, the killing ability of the micro-organism phagosited of polymorphonuclear leukocytes (PMNL) and monocytes, along with oxidative stress parameters of PMNLs were assessed. There was no statistically significant difference in phagocytosis function of PMNLs and monocytes of patients when compared to those of controls. PMNL burst activities of the patient and control groups also showed no difference; however, the monocyte burst activities of patients were significant (p = 0.012). The glutathione peroxidase (GSH-Px) activities in PMNLs of the patients with nephrotic syndrome were significantly higher (p = 0.026) when compared to those of controls. In comparison with those of the control subjects, the patients had also higher selenium levels in their PMNLs (p < 0.001). Although PMNL malonyldialdehyde (MDA) levels of the patients seem to be higher than those of controls, the difference had no statistical significance (p = 0.071). Conclusively, in the patients with nephrotic syndrome, PMNLs appear to be exposed to an oxidative stress as indicated by their increased GSH-Px activities and selenium content. However, PMNLs in nephrotic syndrome patients seem to be coping with the insulting oxidative stress, as suggested by their near-normal MDA productions. Furthermore, these data suggest that nephrotic syndrome appears not to have an influence on phagocytosis and killing abilities of granulocytes and monocytes as long as these cells can overcome the oxidative stress to which they are exposed in this disease.     

Leaf-applied sodium chloride promotes cadmium accumulation in durum wheat grain

Cadmium (Cd) accumulation in durum wheat grain is a growing concern. Among the factors affecting Cd accumulation in plants, soil chloride (Cl) concentration plays a critical role. The effect of leaf NaCl application on grain Cd was studied in greenhouse-grown durum wheat (Triticum turgidum L. durum, cv. Balcali-2000) by immersing (10 s) intact flag leaves into Cd and/or NaCl-containing solutions for 14 times during heading and dough stages. Immersing flag leaves in solutions containing increasing amount of Cd resulted in substantial increases in grain Cd concentration. Adding NaCl alone or in combination with the Cd-containing immersion solution promoted accumulation of Cd in the grains, by up to 41%. In contrast, Zn concentrations of grains were not affected or even decreased by the NaCl treatments. This is likely due to the effect of Cl complexing Cd and reducing positive charge on the metal ion, an effect that is much smaller for Zn. Charge reduction or removal (CdCl₂⁰ species) would increase the diffusivity/lipophilicity of Cd and enhance its capability to penetrate the leaf epidermis and across membranes. Of even more significance to human health was the ability of Cl alone to penetrate leaf tissue and mobilize and enhance shoot Cd transfer to grains, yet reducing or not affecting Zn transfer.     

Derivation and comparison of C57BL/6 embryonic stem cells to a widely used 129 embryonic stem cell line

Typically, embryonic stem (ES) cells derived from 129 mouse substrains are used to generate genetically altered mouse models. Resulting chimeric mice were then usually converted to a C57BL/6 background, which takes at least a year, even in the case of speed congenics. In recent years, embryonic stem cells have been derived from various mouse strains. However, 129 ES cells are still widely used partially due to poor germline transmission of ES cells derived from other strains. Availability of highly germline-competent C57BL/6 ES cells would enormously facilitate generation of genetically altered mice in a pure C57BL/6 genetic background by eliminating backcrossing time, and thus significantly reducing associated costs and efforts. Here, we describe establishment of a C57BL/6 ES cell line (LK1) and compare its efficacy to a widely used 129SvJ ES cell line (GSI-1) in generating germline chimeras. In contrast to earlier studies, our data shows that highly germline-competent C57BL/6 ES cell lines can be derived using a simple approach, and thus support broader use of C57BL/6 ES cell lines for genetically engineered mouse models. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Reduced root mycorrhizal colonization as affected by phosphorus fertilization is responsible for high cadmium accumulation in wheat

Plant and Soil - Grass pea is a legume species with recognized resistance to several diseases and thus important for the improvement of related major legume crops. It is infected by the soil-borne...     

Comparison of the selenium level with GSH-Px activity in the liver of mice treated with 7,12 DMBA

In this study, the relationship between selenium (Se) and glutathione peroxidase (GSHPx) levels was investigated in 7,12-dimethylbenz(a)anthracene (7,12-DMBA)-treated mouse liver. The potential mammary carcinogen 7,12-DMBA, was injected intraperitoneally (20 mg kg(-1) day(-1)) into 10-12 month old female mice. After 21 days of application the mice were sacrificed and GSHPx and Se levels of liver homogenates were measured. Se and GSHPx levels in 7,12-DMBA-treated mice were significantly lower than those of controls (p < 0.05). The control group exhibited 0.9 +/- 0.066 U mg(-1) protein and 0.86 +/- 0.058 p.p.m. levels of GSHPx and Se respectively. The 7,12-DMBA-treated group had significantly (p < 0.05) decreased GSHPx and Se levels (0.42 +/- 0.062 U mg(-1) protein and 0.69 +/- 0.034 p.p.m. respectively). The results show a direct relationship between Se and GSHPx activity and a negative correlation between antioxidant capacity and existence of a carcinogen in metabolism.