NADPH- and iron-dependent lipid peroxidation inhibit aromatase activity in human placental microsomes

During pregnancy placenta is the most significant source of lipid hydroperoxides and other reactive oxygen species (ROS). The increased production of lipid peroxides and other ROS is often linked to pre-eclampsia. It is already proved that placental endoplasmic reticulum may be an important place of lipid peroxides and superoxide radical production. In the present study we revealed that NADPH- and iron-dependent lipid peroxidation in human placental microsomes (HPM) inhibit placental aromatase--a key enzyme of estrogen biosynthesis in human placenta. We showed that significant inhibition of this enzyme is caused by small lipid peroxidation (TBARS (thiobarbituric acid-reactive substances)<4nmol/mg microsomal protein (m.p.)). More intensive lipid peroxidation (TBARS>9nmol/mg microsomal protein) diminishes aromatase activity to value being less than 5% of initial value. NADPH- and iron-dependent lipid peroxidation also causes disappearance of cytochrome P450 parallel to observed aromatase activity inhibition. EDTA, alpha-tocopherol, MgCl(2) and superoxide dismutase (SOD) prevent aromatase activity inhibition and cytochrome P450(AROM) degradation. Mannitol and catalase have not effect on TBARS synthesis, aromatase activity and cytochrome P450 degradation. In view of the above we postulate that the inhibition of aromatase activity observed is mainly a consequence of cytochrome P450(AROM) degradation induced by lipid radicals. The role of hydroxyl radical in cytochrome P450 degradation is negligible in our experimental conditions. The results presented here also suggest that the inhibition of aromatase activity can also take place in placenta at in vivo conditions.     

Association analysis of vitamin D receptor gene polymorphisms with bone mineral density in young women with Graves' disease

Graves' (GD) hyperthyroidism induces accelerated bone turnover that leads to decreased bone mineral density (BMD). The role of the VDR gene in predisposition to primary osteoporosis has been recognized. Recent studies show associations between the VDR gene polymorphisms and susceptibility to autoimmune diseases. Here we analyzed if VDR gene polymorphisms: BsmI, ApaI, TaqI, and FokI may predispose women with Graves' hyperthyroidism to BMD reduction or to disease development. The subjects were 75 premenopausal female Polish patients with GD and 163 healthy women. The genotyping was performed by the use of the restriction fragment length polymorphism analysis (RFLP). We studied the association of the VDR polymorphisms and their haplotypes with patients' BMD and also SNPs and haplotypes association with Graves' disease. We found a strong linkage disequilibrium for the BsmI, ApaI, and TaqI polymorphims that formed three most frequent haplotypes in Graves' women: baT (47.9%), BAt (34.9%), and bAT (16.4%). We did not show statistically significant association of analyzed VDR polymorphisms or haplotypes with decreased bone mineral density in Graves' patients. However, the presence of F allele had a weak tendency to be associated with Graves' disease (with OR=1.93; 95% CI: 0.97-3.84; p=0.058). In conclusion: VDR gene polymorphisms do not predict the risk of decreased BMD in Polish women with Graves'. It may be speculated that the F allele carriers of the VDR-FokI polymorphism are predisposed to Graves' disease development.     

Structural changes of eIF4E upon binding to the mRNA 5' monomethylguanosine and trimethylguanosine Cap

Recognition of the 5' cap by the eukaryotic initiation factor 4E (eIF4E) is the rate-limiting step in the ribosome recruitment to mRNAs. The regular cap consists of 7-monomethylguanosine (MMG) linked by a 5'-5' triphosphate bridge to the first transcribed nucleoside, while some primitive eukaryotes possess a N (2), N (2),7-trimethylguanosine (TMG) cap structure as a result of trans splicing. Mammalian eIF4E is highly specific to the MMG form of the cap in terms of association constants and thermodynamic driving force. We have investigated conformational changes of eIF4E induced by interaction with two cap analogues, 7-methyl-GTP and N (2), N (2),7-trimethyl-GTP. Hydrogen-deuterium exchange and electrospray mass spectrometry were applied to probe local dynamics of murine eIF4E in the apo and cap-bound forms. The data show that the cap binding induces long-range conformational changes in the protein, not only in the cap-binding pocket but also in a distant region of the 4E-BP/eIF4G binding site. Formation of the complex with 7-methyl-GTP makes the eIF4E structure more compact, while binding of N (2), N (2),7-trimethyl-GTP leads to higher solvent accessibility of the protein backbone in comparison with the apo form. The results suggest that the additional double methylation at the N (2)-amino group of the cap causes sterical effects upon binding to mammalian eIF4E which influence the overall solution dynamics of the protein, thus precluding formation of a tight complex.     

Alternations in phenolic acids content in developing rye grains in normal environment and during enforced dehydration

A series of high pressure liquid chroamtography analyses revealed the presence of five phenolic acids in rye caryopses (vanillic, caffeic, p-coumaric, ferulic and sinapic), three of which (p-coumaric, ferulic and sinapic) were found in the free phenolic fraction. Ferulic acid was predominant, both among free acids and total phenolic acids (i.e. free, liberated from soluble esters and glycosides). The highest content of the free phenolic acids in rye caryopses was observed at the beginning of development, when on 22 DAF it was estimated at 11.55 μg·g⁻¹ DW. During dehydratation the total level of free phenolic acids in rye caryopses decreased in all investigated samples. Although total phenolic acids contents in all samples of unripe rye caryopses always decreased after dehydration, in rye sample collected in full ripeness (57 DAF), the amount of these compounds increased after the enforced dehydration. It should be added that in ester-bound-soluble phenolic acids fraction (the largest part in the total phenolic acids fraction), irrespective of the total amount decrease, much increase of sinapic acid content in this fraction was observed after dehydratation treatment in all investigated samples of caryopses of various ripeness. During the development and ripening of rye caryopses, a gradual increase in the precocious germination ability of the grain was observed. The enforced dehydration stimulated the process of precocious germination of developing and ripening rye caryopses. A possible role of phenolics in preventing precocious germination and acclimation to dehydration of developing and ripening rye grains is discussed.     

Trophic state of a lowland reservoir during 10 years after restoration

The restored Maltañski Reservoir was studied from its filling with water in 1990 till 2000. Total phosphorus, chlorophyll-a, and Secchi depth, as well as the Carlson's trophic state index (TSI) values based on those three parameters showed characteristic patterns of changes among seasons and years. Within each year, the lowest trophic state was usually observed in winter and the highest in summer. Because of the high loads of phosphorus received by the reservoir, this element did not limit primary production. TSI values calculated on the basis of total phosphorus were always markedly higher than calculated on chlorophyll-a and Secchi depth (similar to each other). The trophic upsurge phase lasted only a few months after the filling of the reservoir in 1990. Similar symptoms were observed after its refilling in the spring of 1993. The trophic depression phase lasted until the end of 1995. After that time a significant correlation between phosphorus concentration in the reservoir and in river waters flowing into the reservoir was observed. The successive phases of reservoir ageing, determined on the basis of phosphorus concentration, were not accompanied by changes in chlorophyll-a content. The influence of the top-down mechanism (biomanipulation effect) resulted in relatively low values of chlorophyll-a after the filling of the reservoir with water in 1990 and in 1993. As early as 1992 chlorophyll-a values reached a very high level and stayed at that level until the end of the study in 2000 (except for the short decline in 1993).

     

X-ray fluorescence determination of the loss of chosen electrolytes in the urine of children with a congenital cyanotic heart defect and after heart transplantation

In this paper results of the analysis of urine samples of healthy children and children with a congenital cyanotic heart defect and after heart transplantation are presented. The analysis of urine samples was carried out by X-ray fluorescence spectrometry with wavelength dispersion and using CRM urine Seronorm as a reference. It was found that for patients with a congenital cyanotic heart defect the loss of electrolytes like Na, Cl and K was increased. Moreover, urine samples of children from areas of different degree of environmental pollution were analysed. We observed (as expected) higher concentrations of heavy metals in the urine of children from ecological polluted areas.     

Cumulative consumption of the lake macrophyte Elodea by abundant generalist invertebrate herbivores

Previous investigations have shown that macrophyte biomass can be substantially reduced by invertebrate herbivores but have not provided evidence for the links between the magnitude of the observed damage and the densities of herbivores. The results of this study support the hypothesis that the abundant occurrence of the epiphytic generalist herbivores may result in their cumulative consumption which, in turn, can be regarded as the mechanism responsible for often observed relatively high level of herbivory on freshwater macrophytes. The percentage of Elodea sp. biomass consumed by invertebrates was estimated for six European lakes, based on analysis of gut contents, daily rations and the density of epiphytic herbivores. Although the daily ration of these invertebrates when feeding upon Elodea averaged only 14.6% of their dry mass, their biomass was relatively high (from 0.163 to 1.161 g DW per 100 g DW plant). The estimated percentage of Elodea biomass consumed during one summer month by epiphytic invertebrates ranged from 0.5 to 5.9%. These values, after extrapolating to the whole growing season would mean that the biomass of Elodea lost to herbivory was between about 2 and 23%, an estimate which are within the range of consumption reported by other authors.     

Aeromonas spp.-mediated cell-contact cytotoxicity is associated with the presence of type III secretion system

In the study we examined the production of cytotonic and cytotoxic toxins and the presence of a type III secretion system (TTSS) in 64 Aeromonas spp. strains isolated from fecal specimens of patients with gastroenteritis. We observed that contact of the bacteria with host epithelial cells is a prerequisite for their cytotoxicity at 3 h incubation. Cell-contact cytotoxic activity of the strains was strongly associated with the presence of the TTSS. Culture supernatants of the strains induced low cytotoxicity effects at the same time of incubation. Cell-free supernatants of 61 (95%) isolates expressed cytotoxic activity which caused the destruction of HEp-2 cells at 24 h. Moreover, 44% strains were cytotonic towards CHO cells and 46% of strains invaded epithelial cells.     

Hepatocyte nuclear factors as possible C-reactive protein transcriptional inducer in the liver and white adipose tissue of rats with experimental chronic renal failure

Little is known about the effects of coffee that are not related to the presence of caffeine. The aim of the study was to analyse changes in kidney function and nucleotide metabolism related to high intake of decaffeinated coffee. Mice consumed decaffeinated coffee extract for two weeks. Activities of AMP deaminase, ecto5′-nucleotidase, adenosine deaminase, purine nucleoside phosphorylase were measured in kidney cortex and medulla by analysis of conversion of substrates into products using HPLC. Concentration of nucleotides in kidney cortex, kidney medulla and serum were estimated by HPLC. Activity of ecto5′-nucleotidase increased from 0.032 ± 0.006 to 0.049 ± 0.014 nmol/mg tissue/min in kidney cortex of mice administered high-dose decaffeinated coffee (HDC) together with increase in cortex adenosine concentration and decrease in plasma creatinine concentration. HDC leads to increased activity of ecto5′-nucleotidase in kidney cortex that translates to increase in concentration of adenosine. Surprisingly this caused improved kidney excretion function.