Conjugative transfer of glycopeptide and macrolide resistant genes among Enterococci and from Enterococcus faecalis to Staphylococcus aureus

The resistance determinants were transferred from clinical strains of enterococci to Staphylococcus aureus strains. As recipients methicillin-resistant and methicillin-susceptible strains were used and the filter-mating procedure was performed. The transconjugants resistant to erythromycin were obtained in the case of all recipients, in one case the vanA determinant conferring the resistance to vancomycin was transferred together with erythromycin resistance. However the resistance was very unstable and the level was not as high as in the case of Enterococcus faecalis donor strain. The vanA determinant was easily transferred between enterococcal strains by the conjugation and a transfer occurred of vanA alone or together with erythromycin resistance.     

Polymerase chain reaction in diagnosis of toxoplasmosis of the central nervous system: effect of methods for isolating DNA from samples of cerebrospinal fluid on results of the reaction

We examined influence of the method of isolation of DNA from cerebrospinal fluid samples on results of PCR in the diagnosis of toxoplasmosis of the central nervous system. Three different protocols of DNA isolation were used for DNA extraction from 360 samples made of cerebrospinal fluid spiked with tachyzoites of Toxoplasma gondii: thermic, enzymatic and enzymatic-filtering. Purified DNA samples were tested by PCR with primers T15 and T16 designed for the B1 gene of the parasite. Enzymatic method of DNA isolation appeared most effective allowing detection of T. gondii DNA in 50% of samples containing single parasite cell.     

Purinergic regulation of glucose and glutamine synthesis in isolated rabbit kidney-cortex tubules

The effects of extracellular purinergic agonists and their breakdown products on glucose and glutamine synthesis in rabbit kidney-cortex tubules incubated with aspartate + glycerol or alanine + glycerol + octanoate were investigated. A rapid extracellular degradation of ATP was accompanied by an accumulation of AMP, inosine, and hypoxanthine. Extracellular ATP and its breakdown products accelerated glucose synthesis in renal tubules, while ammonium released from adenine-containing compounds enhanced glutamine synthesis and diminished the degree of gluconeogenesis stimulation. In contrast to AMP and inosine, ATP evoked calcium signals, while both ATP and inosine decreased intracellular cAMP content and accelerated the flux through fructose-1,6-bisphosphatase as concluded from changes in gluconeogenic intermediates. Since (i) the activity of partially purified renal fructose-1,6-bisphosphatase was increased upon protein phosphatase-1 treatment and decreased following treatment of previously dephosphorylated enzyme with protein kinase A catalytic subunit and (ii) both 8-bromoadenosine 3',5'-cyclic monophosphate and 8-(4-chlorophenyltio)-cAMP inhibited renal glucose synthesis, it seems likely that in rabbit renal tubules ATP and inosine stimulate gluconeogenesis via cAMP decrease, which favors the appearance of a more active, dephosphorylated form of fructose-1,6-bisphosphatase, a key gluconeogenic enzyme.     

Palmitoylcarnitine modulates interaction protein kinase C delta-GAP-43

Palmitoylcarnitine, reported previously to promote neuronal differentiation, was observed to affect distribution of protein kinase C (PKC) isoforms in neuroblastoma NB-2a cells, leading to retardation in cytoplasm of high molecular weight species of PKCbeta and delta. Growth cone protein-GAP-43, a PKC substrate, was co-immunoprecipitated with all the conventional and novel PKCs: palmitoylcarnitine, however, decreased its amount exclusively in the complex with PKCdelta. Administration of palmitoylcarnitine, although did not change the subcellular distribution of GAP-43, decreased its phosphorylation, which could regulate other signal transduction pathways (calmodulin and G(0)-dependent).     

Green fluorescent protein as a molecular marker in microbiology

Molecular markers such as: lacZ (b-galactosidase), xylE (catechol 2,3-dioxygenase), lux (bacterial luciferase), luc (insect luciferase), phoA (alkaline phosphatase), gusA and gurA (beta-glucuronidase), gfp (green fluorescent protein), bla (beta-lactamase) and other antibiotic resistance markers, heavy metals resistance genes are commonly used in environmental microorganisms research (Errampaii et al., 1998; Kohler et al., 1999). Most of these markers require one or more substrates, complex media and/or expensive equipment for detection. The gfp gene is widely used as a marker because of its very useful properties such as high stability, minimal toxicity, non-invasive detection and the ability to generate the green light without addition of external cofactors and without application of expensive equipment. Various applications of that reporter gene were showed starting from monitoring of microorganism's survival in complex biological systems such as activated sludge to biodegradation of chemical compounds in soil. GFP allowed the detection, determination of spatial location and enumeration of bacterial cells from diverse environmental samples such as biofilm and water. The gfp as a biomarker was very useful in monitoring of gene expression and protein localisation in bacterial cells, too. The techniques with using gfp marker promise to supply a better understanding of environmental processes. It can make possible to use that knowledge in designing more effective and more efficient methods of biodegradation of toxic compounds from different environments.     

Germ cells with nuclear DNA fragmentation related to apoptotic cells in rat testis in experimental hyperprolactinemia induced by metoclopramide

The cells with nuclear DNA fragmentation related to apoptosis were detected by TUNEL technique in the seminiferous epithelium of control rats and of rats with experimental hyperprolactinemia induced by metoclopramide. The percentage of convoluted tubules with apoptotic cells and the number of apoptotic cells (predominantly spermatogonia and spermatocytes) was increased in the experimental group. The results indicated stage-specific germ cell apoptosis. In the experimental group, apoptotic cells were most evident at early (I-IV), middle (VII-VIII) and late (XII-XIV) stages of the seminiferous epithelium cycle, as revealed by light and electron microscopy. We suggest that a decreased concentration of testosterone and an increased concentration of prolactin could disturb spermatogenesis and contribute to the intensive apoptosis of germ cells in rats with hyperprolactinemia. Sertoli cells which have receptors for testosterone and prolactin and play an important role in spermatogenesis and in the initiation of apoptosis in seminiferous epithelium, could mediate such an influence of both hormones.     

Protein kinase C involvement in proliferation and survival of breast cancer cells

Members of protein kinase C (PKC) family have been widely implicated in the regulation of cell proliferation, differentiation and survival. Increased protein C activity in malignant breast tissue and in most aggressive breast cancer cell lines suggests possible role of PKC in the development and progression of breast cancer. PKC may be therefore a target for breast cancer treatment. In our study we attempted to investigate the effect of: phorbol ester (PMA)-PKC activator, and bisindolylmaleimide II (GF II), a highly selective PKC inhibitor, on the proliferation as well as induction of apoptosis and necrosis in breast cancer cell line MDA-MB-231. Our results provide evidence for multidirectional effects of PKC on the proliferation of this type of breast cancer cells. The effects of both compounds were different after short time of exposition (1-3 h). PMA induced proliferation, while GF II showed an opposite effect. After 24 h, however, both compounds exhibited relatively high inhibitory effect on the proliferation and proved to be effective in induction of necrosis and apoptosis.     

IL-1-mediated inhibition of IL-6-induced STAT3 activation is modulated by IL-4, MAP kinase inhibitors and redox state of HepG2 cells

It is known that during acute phase reaction IL-6 activates STAT3 in hepatoma cells and IL-1 downregulates this response. We found that the inhibitory properties of IL-1 on STAT signalling cascade in human hepatoma HepG2 cells are considerably decreased not only in the presence of MAP kinase inhibitors SB203580 and PD98059 but also by some antioxidants (N-acetyl cysteine and pyrrolidine dithiocarbamate) and by anti-inflammatory cytokine IL-4. It appears that cytokine crosstalk between IL-6 and IL-1 includes a direct pathway sensitive to antioxidants and MAP kinase inhibitors, whereas the indirect prolonged response depends probably on synthesis of suppressors of cytokine signalling (SOCS).     

Calcium-cadmium competition in ovarian vitellogenic follicles of Galleria mellonella as revealed by X-ray microanalysis

Dissected ovarioles of Galleria mellonella were exposed for 60 min to cadmium, supplied to insect culture medium in amount equalling that of calcium therein. The sections of ovarioles treated with a fixative precipitating both elements and embedded in epon were examined using energy-dispersive X-ray microanalysis system. Analysis of the digital maps obtained suggests a free inflow of Ca2+ and Cd2+, in approximately equal amounts. Calcium-cadmium competition was revealed within the whole sample as well as in the zoomed fragments comprising ooplasm filled with yolk and trophocyte nucleolus.