Differences between rats and mice in induction of 4S beta-naphthoflavone-binding protein expression by treatment with beta-naphthoflavone

Sprague-Dawley rats and several inbred strains of mice were compared with respect to the induction of 4S BNF-binding protein expression by treatment with beta-naphthoflavone (BNF), an aryl hydrocarbon receptor (AhR) ligand. Inbred strains of mice chosen for the study encompassed 3 allelic forms of AhR found in Mus musculus so far. As it was reported by us earlier, treating rats with BNF caused a significant induction of BNF-binding protein expression. By contrast, no BNF-binding protein was detected in mice treated with BNF in corn oil as a vehicle or with corn oil itself.     

Elongation factor 2 as a target for selective inhibition of protein synthesis in vitro by the novel aromatic biasamidine

By the formation of cGMP the NO-sensitive guanylyl cyclase plays a key role within the NO/cGMP signaling cascade involved in vascular regulation and neurotransmission. The prosthetic heme group of the enzyme acts as the NO sensor, and binding of NO induces conformational changes leading to an up to 200-fold activation of the enzyme. The unexpected fast dissociation half-life of NO of a few seconds is fast enough to account for the deactivation of the enzyme in biological systems. YC-1 and its analogues acting as NO sensitizers uncovered a new pharmacologically and conceivably physiologically relevant regulatory principle of the enzyme.Two existing isoforms of the heterodimeric guanylyl cyclase (₁₁, ₂₁) are known that are functionally indistinguishable. Up to now, the NO-sensitive guanylyl cyclase has been considered as a soluble enzyme. However, recent evidence about the ₂₁ isoform interacting with a PDZ domain of the postsynaptic scaffold protein PSD-95 suggests that the ₂ subunit directs a membrane association of this isoform. The interaction with PSD-95 locates the ₂₁ isoform in close proximity to the NO-generating NO synthase thereby enabling the NO sensor to respond to locally raised NO concentrations.     

The influence of various modified nucleotides placed as 3'-dangling end on thermal stability of RNA duplexes

The ribonucleic acids (RNA) form highly folded structures, which behind the helical fragments contain several secondary and tertiary structural motives. All of them have an influence on thermodynamic stability of the RNA. The 5'- and 3'-dangling ends are one of those structural motives, which effect stability of the adjacent helixes. In this paper, we described the influence of 14 different modified nucleotides, placed as 3'-dangling ends, on thermal stability of the RNA duplexes. Collected data demonstrate that: (i) 5-substituents of the uridine have an impact on the 3'-dangling end effect and the largest changes were observed for 5-chloro, bromo and methyl substituents; (ii) position of the methyl group within the uracil residue affect the thermal stability of the duplex; (iii) increasing a size of the heterocycle base placed as the 3'-terminal unpaired nucleotide enhances stabilization of duplexes.     

Lipopolysaccharide from Proteus mirabilis O29 induces changes in red blood cell membrane lipids and proteins

Alterations in red blood cell (RBC) plasma membranes, i.e. in lipids and proteins, and osmotic fragility of these cells after treatment with Proteus mirabilis O29 endotoxin (lipolysaccharide (LPS)) were examined using a spin labelling method. At the highest concentration of LPS, insignificantly decreased fluidity of membrane lipids was observed. Changes in conformation of membrane proteins were determined by two covalently bound spin labels, 4-maleimido-2,2,6,6-tetramethylpiperidine-1-oxyl (MSL) and 4-iodoacetamido-2,2,6,6-tetramethylpiperidine-1-oxyl (ISL). The analysis of spectra of MSL and ISL showed modifications in membrane proteins in red blood cells treated with the highest concentration of lipopolysaccharide. On the other hand, in the case of isolated membranes, disturbances in membrane were observed for all concentrations of LPS. The alterations in membrane lipids and proteins are paralleled in a significant rise in osmotic fragility of RBCs upon endotoxin treatment. These results provide experimental evidence that P. mirabilis O29 LPS causes deleterious changes in membranes of human red blood cells. They show that action of lipopolysaccharide mainly concerns the membrane cytoskeleton.     

Biochemical evidence for a cGMP-regulated protein kinase in Pharbitis nil

It is known that the level of cGMP is modulated in response to a number of stimuli in plant cells but intracellular events distal to cGMP metabolism are not clear. Cyclic GMP-dependent protein kinase (Pk-G) is a major effector of cGMP action in animals and yeasts. We wanted to determine whether such kinase is present in plant cells. A soluble protein kinase was isolated from seedlings of Pharbitis nil and purified following purification methods including anion-exchange and affinity-chromatography. The enzyme consists of a single polypeptide of M(r) 70 kDa as determined by SDS-PAGE. From conventional modulators only cyclic GMP, when applied in low concentration, was able to accelerate the enzyme activity in the presence of histones. The enzyme autophosphorylated on serine and threonine residues and phosphorylated some substrates only on serine residues. Mixture of histones and histones H2B, H3 were the best phosphate acceptors. The process of autophosphorylation was accelerated by a low concentration of cGMP and reduced by high concentration of this second messenger. Antibodies raised against catalytic domain of animals Pk-G I alpha and beta cross-reacted with protein kinase from Pharbitis nil tissue. These data, taken together, demonstrate the presence of functional enzyme, which activity is regulated by cGMP and allow to classify this protein kinase as a member of the second messenger regulated group of enzymes.     

Arsenic content in the femur head of the residents of southern and central Poland

Arsenic content was assayed in the samples of the femur head of the people living in southern and central Poland (Kraków, n=13; Silesian region, n=13; Łódź, n=12). The average age being 68.7±8.7 yr. Arsenic content in the femur head was determined applying the hydride generation atomic absorption spectrometry (HG-AAS) method after microwave mineralization. The average arsenic contents in the femur head of the residents of the Łódź, Kraków, and Silesian regions were 0.41 μg/g, 0.37 μg/g, and 0.18 μg/g, respectively. No correlation has been found between arsenic content in the femur head and the content of other metals. Neither the age nor sex of the people tested affected the arsenic content in the femur head.     

The assessment of LIF in uterine flushing--a possible new diagnostic tool in states of impaired fertility

The objective of this study was to assess the LIF (leukemia inhibitory factor) concentration in uterine flushing and serum (ELISA) of women with proven fertility, infertile women and women with recurrent miscarriage. In addition, progesterone level was determined in serum. A decreased production of LIF in the uterine microenvironment was found in states of impaired fertility. With a cut-off point of 8.23 pg/ml for LIF level in uterine flushings we have achieved 86.7% sensitivity and 100% specificity in detection of women with idiopathic infertility compared to fertile controls. No correlation between LIF in serum and uterine flushing was demonstrated, rendering LIF measurements in serum useless for diagnosis of impaired infertility. We conclude that LIF measurement in uterine flushing could be a useful diagnostic tool to predict unsuccessful implantation.     

Evaluation and comparison of random amplification of polymorphic DNA, pulsed-field gel electrophoresis and ADSRRS-fingerprinting for typing Serratia marcescens outbreaks

Amplification of DNA fragments surrounding rare restriction sites (ADSRRS-fingerprinting) is a novel assay based on suppression of polymerase chain reaction (PCR). This phenomenon allows the amplification of only a limited subset of DNA fragments, since only those with two different oligonucleotides ligated at the ends of complementary DNA strands are amplified in the PCR. The DNA fragments can be easily analyzed on polyacrylamide gels, stained with ethidium bromide. We have implemented this method using a set of clinical Serratia marcescens isolates from three outbreaks ongoing in the Public Hospital in Gdańsk (Poland). Clustering of ADSRRS-fingerprinting data matched epidemiological, microbiological, random amplification of polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) data. Based on this study, we found that there is at least a similar power of discrimination between the present 'gold-standard' PFGE and the novel method, ADSRRS-fingerprinting. Although the ADSRRS-fingerprinting method may appear to be more complex than the RAPD technique, we found it fast and reproducible.