Coordination chemistry of glutathione

The metal ion coordination abilities of reduced and oxidized glutathione are reviewed. Reduced glutathione (GSH) is a very versatile ligand, forming stable complexes with both hard and soft metal ions. Several general binding modes of GSH are described. Soft metal ions coordinate exclusively or primarily through thiol sulfur. Hard ones prefer the amino acid-like moiety of the glutamic acid residue. Several transition metal ions can additionally coordinate to the peptide nitrogen of the gamma-Glu-Cys bond. Oxidized glutathione lacks the thiol function. Nevertheless, it proves to be a surprisingly efficient ligand for a range of metal ions, coordinating them primarily through the donors of the glutamic acid residue.     

Molecular rearrangements of thylakoids after heavy metal poisoning, as seen by Fourier transform infrared (FTIR) and electron spin resonance (ESR) spectroscopy

The specific effects exerted by different heavy metals on both the function and the structure of the photosynthetic apparatus were addressed. The functional analysis performed via the fluorescence induction kinetics revealed that the applied toxic heavy metals can be classified into two groups: Cd and Ni had no significant effect on the photosynthetic electron transport, while Cu, Pb and Zn strongly inhibited the Photosystem II (PS II) activity, as evidenced by the dramatic decreases in both the variable (F_v) and the maximal (F_m) fluorescence. The structural effects of the heavy metal ions on the thylakoid membranes were considered in three relations: (1) lipids, (2) proteins — studied by Fourier transform infrared (FTIR) spectroscopy, and (3) lipid—protein interactions — investigated by electron spin resonance (ESR) spectroscopy using spin-labeled probe molecules. The studied heavy metal ions had only a non-specific rigidifying effect on the thylakoid lipids. As regards proteins, Cd and Ni had no effect on the course of their heat denaturation. The heat denaturation of the proteins was accompanied by a decrease in the -helix content (1656 cm^-1), a parallel increase in the disordered segments (1651 cm^-1), a decrease in the intramolecular -sheet (1636 cm^-1) content and the concomitant appearance of an intermolecular -structure (1621 cm^-1). In contrast with Cd and Ni, Cu and Zn blocked the appearance of the intermolecular -structure. Pb represented an intermediate case. It seems that these heavy metals alter the native membrane structure in such a way that heat-induced aggregation becomes more limited. The ESR data revealed that certain heavy metals also affect the lipid—protein interactions. While Cd and Ni had hardly any effect on the solvation fraction of thylakoid lipids, Cu, Pb and Zn increased the fraction of lipids solvating the proteins. On the basis of the FTIR and ESR data, it seems that Cu, Pb, and Zn increase the surfaces available for lipid—protein interactions by dissociating membrane protein complexes, and that these lipidated proteins have a smaller chance to aggregate upon heat denaturation. The data presented here indicate that the damaging effects of poisonous heavy metals are element-specific, Cu, Pb and Zn interact directly with the thylakoid membranes of the photosynthetic apparatus, while Cd and Ni interfere rather with other metabolic processes of plants.     

A fluorescence study of the molecular interactions of harmane with the nucleobases, their nucleosides and mononucleotides

Fluorescence binding studies of harmane to the elemental components of the nucleic acids were undertaken to investigate the origin of the interaction between the drug and DNA. Most of the tested substrates have been found to induce hypochromism in the absorption spectrum of harmane and to quench its fluorescence. The quenching process induced by the nucleobases and their nucleosides is mainly due to the formation of ground state 1:1 complexes. However, in the case of the mononucleotides a dynamic quenching component is also observed. This quenching component is likely due to the excited state interaction of harmane with the phosphate group of the nucleotides. UV-vis spectral changes and quenching measurements have been used to quantify the ground state association constants of the complexes and the quenching rate constants.     

Expression and activation of Akt/protein kinase B in sexually immature and mature rat uterus

This study investigated the expression and activation of Akt/PKB in developing and adult rat uterus. Expression of Akt was observed in uteri from adult ovariectomized and 7–35-day-old rats and no changes were observed in response to in vivo estradiol treatment (1–100 μg/100 g b.w.). To examine the mechanisms of PKB/Akt activation, phosphorylation at Thr³⁰⁸ and Ser⁴⁷³ regulatory sites were studied in uteri. Akt was constitutively phosphorylated on Ser⁴⁷³ residue in the untreated, control uteri, while phosphorylation of Thr³⁰⁸ was observed only after estradiol 17β (E2) treatment. The effects of E2 treatment were age dependent, no response was induced in 11-day-old uteri, while in 28 days and older rats the activation of Akt at both regulatory sites, Ser⁴⁷³ and Thr³⁰⁸, increased, the first response was detected 2 h after treatment, reaching the highest rate at 6 h. The rate of phosphorylation was stronger at Ser⁴⁷³ residue. The results suggest that the regulation of Akt activation at two regulatory sites in rat uteri are different, phosphorylation of Thr³⁰⁸ seems to be entirely estrogen dependent, while the phosphorylation of Ser⁴⁷³ is regulated by other factors as well as estrogen.     

Essential oil composition of aerial parts of Angelica glauca growing wild in North-West Himalaya (India)

Fresh aerial parts of Angelica glauca, growing wild in Kashmir valley in higher Himalaya (Jammu and Kashmir, India), collected at flowering stage from different locations, on hydro-distillation provided a refreshing light pale coloured essential oil with characteristic floral woody flavour. The oil was found to be a complex mixture of mono- and sesquiterpenes and 34 compounds accounting for nearly 97.4% of the oil were characterized with the help of capillary GC, GC-MS, and NMR. Major compounds of the oil were characterized as alpha-phellandrene (13.5%), trans-carveol (12.0%), beta-pinene (11.7%), thujene (7.5%), beta-caryophyllene oxide (7.2%), beta-caryophyllene (7.0%), gamma-terpinene (6.7%), nerolidol (6.5%), beta-bisabolene (5.2%) and germacrene D (4.5%). It is the first report to exploit the essential oil from Himalayan A. glauca herb collected at flowering stage.     

Effects of a GnRH agonist on oocyte number and maturation in mice superovulated with eCG and hCG

The objective was to investigate the effects of a gonadotropin-releasing hormone agonist (GnRH) on ovulation rate and the number and maturation of oocytes in mice superovulated with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG). Thirty 3-month-old BALB/C female mice (weight: 25-30 g) were assigned to three experimental groups: control, superovulated, and superovulated with GnRH pretreatment (n=10 per group). Control mice received an i.p. injection of 0.1 ml physiological saline solution. Superovulation was induced with 5 IU eCG (i.p.) and 5 IU hCG 48 h later. Mice in the superovulated with GnRH pretreatment group were given GnRH (20 mg/kg Fertirelin, i.m.), 24 h before superovulation. Thirteen hours after hCG administration, mice were sacrificed by cervical dislocation and blood samples were collected to determine serum progesterone concentration (by radioimmunoassay). Ovaries and oviducts were also harvested to enumerate corpora lutea and cumulus-enclosed oocytes. Progesterone concentrations were not significantly different among groups. The oocyte number and the maturation, ovulation rate, and the number of corpora lutea were higher in GnRH-treated mice than both controls and superovulated mice. In conclusion, GnRH given 24 h before superovulation with eCG-hCG increased the number and maturation of oocytes and the rate of ovulation in mice.     

Levels of some trace elements and rheumatoid factor in sheep with brucellosis

Brucellosis is a zoonotic disease that is encountered in sheep rather frequently. In this study, 100 sheep diagnosed with brucellosis that had aborts and 40 healthy sheep were used as materials. Analyses for Cu, Zn, Fe, Cr, Ca, Mg, and K were performed with the atomic absorption spectrophotometric method on blood collected from vena jugularis of all the sheep and rheumatoid factor levels were determined by the nephelometry method. Although it was found that Cu, Ca, and rheumatoid factor values in the sera of the sheep with brucellosis were high when compared to the control group (p<0.001, p<0.05, p<0.001, respectively), their serum Zn values were low (p<0.05). No significant changes in serum Cr, Fe, K, and Mg levels were found.     

Effects of in ovo treatment with PACAP antagonist on general activity, motor and social behavior of chickens

Pituitary adenylate cyclase activating polypeptide (PACAP) has been shown to influence nervous system development. The aim of the present study was to investigate the effects of in ovo treatment with the PACAP antagonist PACAP6-38 during embryonic life (E8 and E16) on motor activity and social behavior in chicken. Our results showed that a single injection of PACAP6-38 during the first half of embryonic life caused subtle transient changes in general behavior and motor control when compared to saline-treated controls. Increased activity and reduced anxiety were observed also in a novel environment at 2 days after hatching. However, most of these behavioral differences disappeared by 2 weeks. PACAP6-38-treatment during the first half of embryonic life resulted in markedly reduced social behavior, which was still present at 2 weeks of age. Treatment during the second half of embryonic life resulted in no behavioral differences between control and PACAP6-38-treated chicken. PACAP content in different brain areas was not different between control and PACAP6-38-treated chicken at 5 days or 3 weeks of age, but it decreased significantly with age in both groups. In summary, our results show that PACAP6-38 treatment at E8 caused transient changes in motor behavior, and long-lasting reduction in social behavior.     

Joint explorative analysis of neuroreceptor subsystems in the human brain: application to receptor-transporter correlation using PET data

Positron emission tomography (PET) has proved to be a highly successful technique in the qualitative and quantitative exploration of the human brain's neurotransmitter-receptor systems. In recent years, the number of PET radioligands, targeted to different neuroreceptor systems of the human brain, has increased considerably. This development paves the way for a simultaneous analysis of different receptor systems and subsystems in the same individual. The detailed exploration of the versatility of neuroreceptor systems requires novel technical approaches, capable of operating on huge parametric image datasets. An initial step of such explorative data processing and analysis should be the development of novel exploratory data-mining tools to gain insight into the "structure" of complex multi-individual, multi-receptor data sets. For practical reasons, a possible and feasible starting point of multi-receptor research can be the analysis of the pre- and post-synaptic binding sites of the same neurotransmitter. In the present study, we propose an unsupervised, unbiased data-mining tool for this task and demonstrate its usefulness by using quantitative receptor maps, obtained with positron emission tomography, from five healthy subjects on (pre-synaptic) serotonin transporters (5-HTT or SERT) and (post-synaptic) 5-HT(1A) receptors. Major components of the proposed technique include the projection of the input receptor maps to a feature space, the quasi-clustering and classification of projected data (neighbourhood formation), trans-individual analysis of neighbourhood properties (trajectory analysis), and the back-projection of the results of trajectory analysis to normal space (creation of multi-receptor maps). The resulting multi-receptor maps suggest that complex relationships and tendencies in the relationship between pre- and post-synaptic transporter-receptor systems can be revealed and classified by using this method. As an example, we demonstrate the regional correlation of the serotonin transporter-receptor systems. These parameter-specific multi-receptor maps can usefully guide the researchers in their endeavour to formulate models of multi-receptor interactions and changes in the human brain.