Interactions of Meso-tetra-(4-N-oxyethylpyridyl) Porphyrin,Its 3-N Analog and Their Metallocomplexes with Duplex DNA

Abstract

Interactions of meso-tetra-(4-N-oxyethylpyridyl) porphyrin (TOEPyP(4)), its 3-N analog (TOEPyP(3)) and their Co, Cu, Ni, Zn metallocomplexes with duplex DNA have been investigated by uv/visible absorbance and circular dichrosim spectroscopies. Results reveal the interactions of these complexes with duplex DNA are of two types. (1) External binding of duplex DNA by metalloporphyrins containing Zn and Co, and (2) Binding of duplex DNA both externally and internally (by intercalation) by porphyrins not containing metals, and metalloporphyrins containing Cu and Ni. Results indicate that (4N-oxyethylpyridyl) porphyrins intercalate more preferably in the structure of duplex DNA and have weaker external binding than 3N-porphyrins.     

Intestinal microflora of autistic children

Autistic behavior is often accompanied by numerous disturbing symptoms on the part of gastrointestinal system, such as abdominal pain, constipation or diarrhea. These problems are often connected with deregulation of physiological microflora in intestine. The aim of this study was to determine differences in intestinal microflora of autistic and healthy children. Strains of Clostridium spp. and enterococci were isolated more frequently from stool samples of autistic children and rarely lactobacilli. Quantitative differences were observed maliny among staphylococci, Candida spp. and Clostridium perfringens. Monitoring and stabilization of intestinal microflora and knowledge about role of particular strains in etiology of autistic disorders can increase the chances for appropriate therapy.     

Lethal factor of Clostridium histolyticum kills cells by apoptosis

In this study, for the first time, Clostridium histolyticum lethal factor was purified by ammonium sulfate precipitation of culture broth, centrifugation through an Amicon filter device and hydrophobic interaction chromatography. The purified lethal factor was devoid of proteolytic activity. At a concentration of 150 ng mL(-1) the lethal factor killed 50% of HeLa cells within 24 h of exposure. Abrogation of actin filaments, activation of caspases, fragmentation of nuclear DNA as well as ultrastructural changes indicated that the cell death occurred by apoptosis. The apoptotic action of the lethal factor is in agreement with changes induced in animal tissues by administration of C. histolyticum culture medium.     

Vacuolating,lethal, collagenase and clostripain activities of six reference ATCC <Emphasis Type="Italic">Clostridium histolyticum</Emphasis> strains

We have previously demonstrated that C. histolyticum reference strain ATCC 19401 produces not only lethal factor but also hitherto unrecognized vacuolating toxin. The aim of this study was to compare vacuolating and lethal activities of six reference C. histolyticum strains (ATCC 6282, 8034, 17859, 17860, 19401 and 25770) and to determine whether production of vacuolating toxin is strain-dependent and how the amounts of both toxins produced by the same strain are related to each other and also to protease, collagenase and clostripain activities. All strains produced vacuolating and lethal toxins as well as collagenase, clostripain and proteases, but with different yield. Strain ATCC 19401 demonstrated considerable vacuolating and lethal activities and low activity of collagenase, clostripain and proteases. In other strains such relationship was not evident. Positive correlations were observed in collagenase and clostripain activities of all studied C. histolyticum strains (r = 0.71). Positive correlations were detected also in vacuolating activities of studied strains and clostripain (r = 0.62) and collagenase (r = 0.87) production, and this effect was statistically significant (P < 0.05). Negative non-significant correlations were detected: (a) in lethal activities of studied strains and clostripain, or collagenase activities, (b) in vacuolating activities and protease production.     

The blockade of endothelin A receptor protects astrocytes against hypoxic injury: common effects of BQ-123 anderythropoietin on the rejuvenation of the astrocyte population

In the present study the role of endothelin (ET) and its receptors (ETA-R and ETB-R) in cellular mechanisms underlying the resistance of astroglial cells to low oxygen level and development of hypoxia has been investigated. To define the influences of ET and its receptors on survival and on antigenic as well as morphologic differentiation of rat astroglial cells in normoxic (NC) and hypoxic culture (HC) the selective antagonists of ETA-R (BQ-123) and ETB-R (BQ-788) were used. Treatment of HC with BQ-123 caused an increase in cell number and inhibited the hypoxia-induced apoptosis by 37%. BQ-123 decreased the hypoxia-induced cytotoxicity in HC. These effects of BQ-123 were abolished in cultures simultaneously treated with BQ-123 and BQ-788. Administration of BQ-788 alone decreased the number of living cells in NC, but not in HC. The activity of caspase-3/-7 was not changed by exposure of NC and HC to BQ-788. The protection provided by BQ-123 to astroglial cells against cytotoxicity in NC and HC was similar to that of erythropoietin (EPO), a cytokine with established neuroprotective effects. The functional improvement of astroglial cells and slowing down of their differentiation under exposure to BQ-123, or EPO, or BQ-123 + EPO has been evidenced by an increased number of nestin+/glial fibrillary acidic protein-positive (GFAP+) astrocytes accompanied by decrease of nestin-/GFAP+ cells. The simultaneous treatment with BQ-123 and EPO additionally decreased the activities of caspase-3/-7 (64%) and release of LDH into the medium (94%). The benefits in the functional states of astrocytes obtained by combined treatment of HC with BQ-123 and EPO suggest a new therapeutic strategy in treatment of hypoxic brain injury.     

Evaluation of blood cultures of children hospitalized in Upper Silesian Health Center of Child and Mother in Katowice

Blood cultures (1613) taken from children hospitalized in 13 wards of Upper Silesian Health Center of Child and Mother were studied using Bact/Alert 240 monitoring system (bioMerieux). Around 17.7% of studied cultures were positive: 285 microorganisms were isolated. Gram-positive cocci dominated: 32.3% were strains of MRCNS Gram-negative rods, mainlyEnterobacteriaceae were isolated in 18.6% of cases, non-fermenters--in 12.9%, yeasts (mainly C. albicans)--in 10.5%. More frequently blood cultures were positive in Intensive Care Unit (37.5%).     

POTENTIATION OF AMP-AMINOHYDROLASE ACTIVITY OF BRAIN MITOCHONDRIA BY HEXOKINASE

Abstract— The addition of hexokinase (yeast and brain) to mitochondrial fractions of brain (rat) resulted in a considerable increase of formation of ammonia from AMP. The mechanisms underlying the activation of AMP-aminohydrolase of brain mitochondria by ATP and hexokinase are quite different. In the activation of AMP-aminohydrolase by hexokinase the SH-groups of both enzymes particularly of the latter are of importance. Brain mitochondria contain low-molecular dialysable substances of unknown nature which are necessary for the interaction of both enzymes.     

Further similarities between astrocytes and perisinusoidal stellate cells of liver (Ito cells): Colocalization of desmin and glial fibrillary acidic protein in astroglial primary cultures

The colocalization of desmin and glial fibrillary acidic protein (GFAP) in astrocytes was inferred from previous studies demonstrating a unique antigenic composition comprising GFAP, desmin and vimentin in perisinusoidal stellate cells (PSC) of liver which share several features with astrocytes. In the present study the colocalization of GFAP and desmin was investigated by double-immunolabeling experiments in 12-day-old rat astroglial primary cultures with antiserum against GFAP and two commercial monoclonal antibodies against desmin, antibodies of clone DEU-10 and clone DEB-5. These antibodies selectively decorated the perisinusoidal stellate cells (PSC) of liver for which desmin is known to be a marker. The results obtained with astroglial cells demonstrate that both GFAP and desmin are coexpressed in morphologically different types, process-bearing and process-lacking astrocytes. The expression of desmin was apparently more pronounced in process-lacking astrocytes and was considerably lower in process-bearing ones. In process-lacking astrocytes, in contrast to filamentous cytoplasmic staining for GFAP, the immunoreactivity for desmin was non-filamentous and was irregularly spread in the perinuclear cytoplasm of the cells, while in process-bearing astrocytes the pattern of staining for desmin was similar to that of GFAP. The variability in the intensity and pattern of staining for desmin in astrocytes might be due to transitional stages of differentiation for part of the cells. This interpretation was supported by the presence of GFAP in the cells weakly expressing smooth muscle alpha-actin and the absence of GFAP in the cells enriched with microfilaments.     

Copper (II) Ions Affect <Emphasis Type="Italic">Escherichia coli</Emphasis> Membrane Vesicles’ SH-Groups and a Disulfide-Dithiol Interchange Between Membrane Proteins

The SH-groups in Escherichia coli membrane vesicles, prepared from cells grown in fermentation conditions on glucose at slightly alkaline pH, have a role in the F0F1-ATPase operation. The changes in the number of these groups by ATP are observed under certain conditions. In this study, copper ions (Cu2+) in concentration of 0.1 mM were shown to increase the number of SH-groups in 1.5- to 1.6-fold independent from K+ ions, and the suppression of the increased level of SH-groups by ATP was determined for Cu2+ in the presence of K+. Moreover, the increase in the number of SH-groups by Cu2+ was absent as well as the inhibition in ATP-dependent increasing SH-groups number by Cu2+ lacked when vesicles were treated with N-ethylmaleimide (NEM), specific thiol-reagent. Such an effect was not observed with zinc (Zn2+), cobalt (Co2+), or Cu+ ions. The increased level of SH-groups was observed in the hycE or hyfR mutants with defects in hydrogenases 3 or 4, whereas the ATP-dependent increase in the number of these groups was determined in hycE not in hyfR mutants. Both changes in SH-groups number disappeared in the atp or hyc mutants deleted for the F0F1-ATPase or hydrogenase 3 (no activity of hydrogenase 4 was detected in the hyc mutant used). A direct effect of Cu2+ but not Cu+ on the F0F1-ATPase is suggested to lead to conformational changes or damaging consequences, increasing accessible SH-groups number and disturbing disulfide-dithiol interchange within a protein-protein complex, where this ATPase works with K+ uptake system or hydrogenase 4 (Hyd-4); breaks in disulfides are not ruled out.     

ON THE MECHANISM OF STIMULATION OF AMP-AMINOHYDROLASE ACTIVITY BY HEXOKINASE IN BRAIN TISSUE

—A hexokinase has been isolated from brain tissue on Sephadex G-100 and DEAE cellulose which is similar to yeast enzyme in stimulating the AMP-aminohydrolase activity of rat brain soluble fractions. This effect of hexokinase is influenced neither by N-acetyl-glucosamine nor noradrenaline. An isoenzyme of hexokinase isolated from brain tissue on DEAE cellulose, having properties similar to that of the muscle enzyme, has no effect on AMP-aminohydrolase activity. The activating effect of yeast hexokinase is not due to its oligomeric structure. Enzyme subunits obtained by the treatment of native yeast enzyme by urea also activate AMP-aminohydrolase of rat brain soluble fractions.