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.     

Prevention of processes coupled with free radical formation prevents also the development of calcium-resistance in the diabetic heart

Recently it was shown that besides their negative role in pathogenesis of diabetes, reactive oxygen species (ROS) and particularly the products of non-enzymatic glycation of proteins (NEGP) may also participate in some processes of adaptation of the myocardium to diabetes, such as in the mechanism of development of calcium resistance of the heart. Our study revealed that the hearts of rats with experimentally induced diabetes (single dose of streptozotocin, 45 mg/kg i.v., 6 U/kg insulin daily) develop considerable resistance against calcium overload (induced by means of Ca-paradox). On the day 63 after the beginning of experiment, when the diabetic cardiomyopathy became fully developed but the hearts were still not failing, their calcium resistance was increased to 83.33%. Our results provide evidence that, when applied in a special regimen, resorcylidene aminoguanidine (RAG, 4 mg/kg) prevented both, the formation of fructosamine (a source of ROS generation), and also that of the advanced Maillard products, in the heart sarcolemma of diabetic rats. The effect of RAG was accompanied by a decrease in calcium resistance in the group of rats with chronic diabetes (63 days) from 83.3 to 46.7%. It is concluded that NEGP and ROS formation are inevitably needed for development of calcium resistance in the diabetic hearts.     

Pretreatment with granulocyte colony-stimulating factor reduces myelopoiesis in irradiated mice

The purpose of this study was to investigate effects of the treatment prior to irradiation with granulocyte colony-stimulating factor (G-CSF) on hematopoiesis in B10CBAF1 mice exposed to a sublethal dose of 6.5 Gy of 60Co gamma radiation. G-CSF was administered in a 4-day regimen (3 microg/day); irradiation followed 3 h after the last injection of G-CSF. Such a treatment was found to stimulate granulopoiesis, as shown by increased counts of granulocyte-macrophage progenitor cells (GM-CFC) and of granulocytic cells in the femoral marrow and spleen at the time of irradiation. However, postirradiation counts of GM-CFC and granulocytic cells in the marrow of mice pretreated with G-CSF were reduced up to day 18 after irradiation. Interestingly, the D0 values for marrow GM-CFC determined 1 h after in vivo irradiation were 1.98 Gy for controls and 2.47 Gy for mice pretreated with G-CSF, indicating a decreased radiosensitivity of these cells after drug treatment. The inhibitory effects of the pretreatment with G-CSF on the postirradiation granulopoiesis could be attributed to the phenomenon of "rebound quiescence" which can occur after cessation of the treatment with growth factors. Postirradiation recovery of erythropoiesis in the spleen of mice pretreated with G-CSF exhibited a dramatic increase and compensated for the decreased erythropoiesis in the marrow at the time of irradiation. This complexity of the hematopoietic response should be taken into account when administering G-CSF in preirradiation regimens.     

Spectral properties of the oxyferrous complex of the heme domain of cytochrome P450 BM-3 (CYP102)

Here we describe for the first time the formation of a complex of reduced CYP102 (cytochrome P450 BM-3) heme domain with molecular oxygen. To stabilize the oxycomplex, the experiments had to be done under argon atmosphere at cryogenic temperatures (-25 degrees C) in the presence of 50% glycerol. The spectral properties of this species were different from those of another P450-type autosuffisant enzyme, i.e., the neuronal nitric oxide synthase. On the contrary, the oxyferrous complex of CYP102 possesses spectral properties similar to those of complexes of microsomal cytochromes P450, e.g., CYP2B4.     

Sequence-dependent conformational changes in DNA induced by polynuclear platinum complexes

In this work, the B-->Z transition of poly(dG-dC).poly(dG-dC) and the B-->A transition of poly(dG).poly(dC) and of calf thymus (CT) DNA fragments modified by antitumor bifunctional polynuclear platinum complexes were investigated by circular dichroism (CD). The transition from the B- to Z-form of DNA was inducible with all three compounds studied, as indicated by an inversion of the B-form spectra. The B-->A transition in poly(dG).poly(dC) was induced easily by platinum complex binding alone, while the B-->A transition in CT DNA was induced by ethanol but inhibited by coordination of all polynuclear platinum compounds used here. It was shown that the compound [?cis-PtCl(NH3)2?2 mu-?H2N(CH2)6NH2?] (NO3)2 (1,1/c,c) was most effective at inhibiting the B-->A transition in CT DNA, and [?trans-PtCl(NH3)2?2 mu-?trans-Pt(NH3)2(H2N(CH2)6NH2)2?] (NO3)4 (1,0,1/t,t,t) was least effective, while the effectiveness of [?trans-PtCl(NH3)2?2 mu-?H2N(CH2)6NH2?] (NO3)2 (1,1/t,t) fell between the two. This corresponded to the relative amounts of interstrand crosslinks in double-stranded DNA caused by each compound.     

Epizoic amoebae from the gills of turbot Scophthalmus maximus

Species of amoebae belonging to the genera Platyamoeba Page, 1969, Vannella Bovee, 1965 and Flabellula Schaeffer, 1926 were found to accompany Paramoeba sp., the agent of amoebic gill disease (AGD), in clinically diseased turbots. The same community of epizoic gymnamoebae was found on the gills of turbots which revealed no gill abnormalities but slight behavioral signs indicative of suboptimal health status. The assemblage of the above-mentioned free-living amoebae capable of colonizing gill tissue of turbots was supplemented with species recognized in samples fixed from primary isolates for transmission electron microscopy. The pathogenic potential of epizoic gill amoebae in turbots is discussed.     

Kabataia gen. n., a new genus proposed for Microsporidium spp. infecting trunk muscles of fishes

Based on a fine structural study, a new genus, Kabataia gen. n., is proposed for Microsporidium arthuri Lom, Dyková and Shaharom, 1990. It develops in trunk muscles of a South-East Asian freshwater fish, Pangasius sutchi. The genus has nuclei isolated throughout the cycle, merogony stages are multinucleate, sporogony proceeds in 2 steps: multinucleate sporont segments into sporoblast mother cells which produce 2 sporoblasts. Sporoblasts and early spores are characterized by a dense globule at the site of the posterior vacuole. Mature spores are of a rather variable shape. Their exospore is raised into small, irregular fields. The polaroplast is relatively small and its posterior part consists of flat vesicles with dense contents. The polar tube makes a small number (4 to 6) of turns. A congeneric species is Kabataia seriolae (Egusa, 1982) comb. nov. from cultured marine yellowtails Seriola quinqueradiata. Kabataia inflicts heavy damage on muscle tissue. The sarcoplasm within which Kabataia develops is reduced to an amorphous mass with tubule-like fibrils, microfibrils and small vesicles.