Activation of hematoporphyrin in alternating magnetic field: possible implications for cancer treatment

A new mechanism of cell damage by alternating magnetic field with hematoporphyrin is described. C6 glioblastoma cell suspensions were exposed to an alternating magnetic field with frequency 180 kHz up to 60 min in the presence of hematoporphyrin in H2O and in D2O. The results presented suggest that an alternating magnetic field is able to activate hematoporphyrin, and this method may be a basis for cancer treatment.     

Carboxymethylated glucan inhibits lipid peroxidation in liposomes

Protective capabilities were studied of carboxymethylated (1-->3)-beta-D-glucan from Saccharomyces cerevisiae cell wall against lipid peroxidation in phosphatidylcholine liposomes induced by OH radicals produced with Fenton's reagent (H2O2/Fe2+) and also by microwave radiation using absorption UV-VIS spectrophotometry. A significant decrease in the conjugated diene production, quantified as Klein oxidation index, was observed in the presence of a moderate amount of added glucan. Increase of the oxidation index was accompanied with enhanced carboxyfluorescein leakage as a result of liposome membrane destabilization. This process was markedly suppressed with glucan present in the liposome suspension. Therefore, glucan may be considered as a potent protector against microwave radiation-induced cell damage.     

Larval toxocariasis and its clinical manifestation in childhood in the Slovak Republic

Results are presented of 90 children aged 1-15 years hospitalized with toxocariasis. Blood count analysis and laboratory examination were done by routine clinical laboratory methods. Anti-Toxocara antibodies were detected in the serum of patients using an ELISA method. Demographic analysis of the children's families exposed to the risk of disease allowed estimation of age-specific rates for clinical toxocariasis. The probability of toxocaral infection and the intensity of its clinical manifestations in children are determined by the epidemiology of this zoonosis and by the risk factors in the family. The presence of high titres of specific IgG antibodies in all age categories correlates with the clinical manifestations of toxocariasis. The highest admission rate is in the age categories of 3-5 years (43.3%) and 6-10 years (36.7%). Laboratory findings show that the most conspicuous changes occur in the age category 1-5 years. The high percentage of seropositive dog-keeping and puppy-breeding families and the possibility of infection with repeated doses of larvae stimulate eosinophilia, which prevails in children under the age of five years. We present the percentage of patients whose parameters showed deviations from the reference values for a particular age category. Analyses of laboratory indices and of clinical manifestations will contribute to the accuracy of diagnosis and effectiveness of treatment of this disease.     

Phosphorylated aspartate in the structure of a response regulator protein

Phosphorylation of aspartic acid residues is the hallmark of two- component signal transduction systems that orchestrate the adaptive responses of micro-organisms to changes in their surroundings. Two-component systems consist of a sensor kinase that interprets environmental signals and a response regulator that activates the appropriate physiological response. Although structures of response regulators are known, little is understood about their activated phosphorylated forms, due to the intrinsic instability of the acid phosphate linkage. Here, we report the phosphorylated structure of the receiver/phosphoacceptor domain of Spo0A, the master regulator of sporulation, from Bacillus stearothermophilus. The phosphoryl group is covalently bonded to the invariant aspartate 55, and co-ordinated to a nearby divalent metal cation, with both species fulfilling their electrostatic potential through interactions with solvent water molecules, the protein main chain, and with side-chains of amino acid residues strongly conserved across the response regulator family. This is the first direct visualisation of a phosphoryl group covalently linked to an aspartic acid residue in any protein, with implications for signalling within the response regulator family.     

Mapping of quantitative trait loci for seminal vesicle mass and litter size to rat chromosome 8

The spontaneously hypertensive rat (SHR) and the Brown Norway (BN) rat differ significantly in litter size (7.6 versus 4.5 pups). In the HXB and BXH sets of recombinant inbred (RI) strains derived from SHR and BN rats, heritability of litter size and of selected male reproductive parameters such as sperm production, sperm count, sperm morphology and motility, and the mass of the testis, epididymides, and seminal vesicles were estimated and a search was undertaken for quantitative trait loci (QTL) associated with these phenotypes. The mass of seminal vesicles was significantly associated with a QTL near the D8Cebr204S21 marker on chromosome 8 (LOD score = 4.1, P = 0.00001); this QTL was responsible for 46% of the genetic variability of the trait. The same gene marker on chromosome 8 also showed a suggestive association with the litter size. Litter size was significantly correlated with the mass of seminal vesicles (r = 0.58, P = 0.003). These findings indicate that the variability in litter size among RI strains may be due in part to differences in the mass of seminal vesicles and it is possible that both mass of seminal vesicles and litter size are determined by a pleiotropic effect of the same QTL on rat chromosome 8.     

Transgenic UCP1 in white adipocytes modulates mitochondrial membrane potential

To test if mitochondrial uncoupling in white adipocytes is responsible for obesity resistance of the aP2-Ucp transgenic mice expressing ectopic uncoupling protein 1 (UCPI) in white fat, mitochondrial membrane potential (delta psi(m)) was estimated by flow cytometry in adipocytes isolated from gonadal fat. Ectopic UCP1 (approximately 0.8 mol UCP1/mol respiratory chain) decreased the delta psi(m) and rendered the potential sensitive to GDP and fatty acids. These ligands of UCP1 had no effect on delta psi(m) in white adipocytes from non-transgenic mice, suggesting that the function of endogenous UCP2 in adipocytes was not affected. The results support the hypothesis that mitochondrial uncoupling in white fat may prevent development of obesity.     

Modulation of endocytosis in nuclear factor IL-6(-/-) macrophages is responsible for a high susceptibility to intracellular bacterial infection

Activated macrophages kill bacteria, a function known to depend on the expression of NF-IL-6. Here, it is demonstrated that the attenuated Brucella abortus vaccine strain 19 replicates much better in NF-IL-6-/- than in NF-IL-6(+/+) and NF-IL-6(+/+)-activated murine macrophages and at levels comparable to those observed in normal macrophages infected with the pathogenic strain 2308. The role of NF-IL-6 in the inhibition of intracellular bacterial replication is related to its control of endocytosis and membrane fusion between endosomes and Brucella-containing phagosomes. Addition of the granulocyte-CSF (G-CSF), whose induction is impaired in NF-IL-6(-/-) macrophages, restores both endocytosis and the morphology of endosomes, together with bactericidal activity. Regulation of membrane traffic in endocytosis by G-CSF whose expression is controlled by NF-IL-6 may explain how a host cell can control intracellular bacterial replication.     

Stobadine and heart mitochondria

Previous work has shown, that stobadine-hydrochloride (-)cis-2,8-dimethyl-2,3,4,4a,5,9b-hexahydro-14-pyrido(4,3b) indole administered in a single dose 2 mg/kg of body weight reduces cardiotoxic effect of isoproterenol (1 mg/kg) as shown by lowered serum enzyme activities of AST, CPK, LDH and ALT. We studied the effect of stobadine in vivo on respiration, the level of ATP, malondialdehyde (MDA) and superoxiddismutase (SOD) in heart mitochondria. Serum enzyme activities of AST, CPK and LDH after stobadine application were significantly decreased. In mitochondria, respiration and activity of SOD were inhibited, level of MDA was increased and level of ATP was unchanged. The cardioprotective effect of stobadine is not linked to preservation of mitochondrial function. This effect is probably more complex and mediated on the level of the whole organism.     

Effect of stobadine on lipid peroxidation in brain and heart after ischemia and reperfusion of the brain

Stobadine (ST), a novel drug with pyridoindol structure, was recently found to prevent reperfusion injury in rat brain. The aim of the present study was to reveal whether ST may prevent peroxidative changes in the heart and brain that were triggered by postischemic reperfusion of the brain. In the brain, reperfusion significantly increased the contents of malondialdehyde (MDA) by 43.8% and conjugated diens (CD) by 24.5% when compared with the end of ischemia. In the heart, contents of MDA and CD in reperfusion became elevated three fold and by 41.7%, respectively, when comparing to the values at the end of ischemia. In the heart, no significant changes in activities of the superoxide dismutase (SOD) and glutathione peroxidase (GPx) induced by ischemia or reperfusion were detected. In contrast, reperfusion induced a slight decrease in GPx activity in the brain. In accordance with our previous results, an application of ST (2 mg/kg) to the femoral artery shortly prior to reperfusion of the ischemic brain, prevented significantly MDA and CD accumulation in brain. Nevertheless, ST was not able to prevent the brain-ischemia/reperfusion-induced elevation of MDA and CD contents in the heart.     

Effect of stobadine on oxygen free radical generation in stimulated human polymorphonuclear leukocytes

The generation both superoxide and a mixture of reactive oxygen species was recorded in a suspension of human polymorphonuclear leukocytes stimulated with phorbol myristate acetate. While stobadine dose-dependently decreased chemiluminescence, only its highest concentration used reduced significantly superoxide generation. The results suggest that stobadine is a more effective scavenger of free radicals rather than a quencher of superoxide anion.