Zoltán Berente

17β-Estradiol and progesterone prevent cuprizone provoked demyelination of corpus callosum in male mice

Sex hormones, for example, estrogen and progesterone, are thought to affect and delay progression of multiple sclerosis (MS) in pregnant women. Although both steroid hormones are neuroprotective in the brain and elevated during pregnancy, only estrogen was tested in clinical trials. To evaluate the role of 17β‐estradiol (E) and progesterone (P) in prevention demyelination, young adult male mice were fed with cuprizone for a defined time interval and simultaneously treated with steroids by repeated injections into the neck region. The status of myelination was analyzed by magnetic resonance imaging and conventional histological staining. The individual application of E and P resulted only in a moderate prevention of demyelination in the corpus callosum (CC). The combined treatment with both steroid hormones counteracted the process of demyelination. Expression of the mature (PLP and MBP) and premature (PDGF‐α‐R) oligodendrocyte markers were significantly increased after hormone application in the affected CC. In addition, both hormones stimulated astrogliosis and the expression of IGF‐1. Microglial invasion in demyelinated CC was pronounced and additionally localized in the midline of CC after hormone treatment. These data show that sex steroids can protect the brain from demyelination and stimulate remyelination. It appears that only the administration of both hormones is fully effective. The beneficial steroid effect requires interactions with oligodendrocytes possibly by preventing their degeneration or recruitment from precursor cells which are stimulated to remyelinated fibers. The positive hormonal influence on myelination in the CNS may be a future therapeutically strategy for the treatment of MS.

Decrease of the inflammatory response and induction of the Akt/protein kinase B pathway by poly-(ADP-ribose) polymerase 1 inhibitor in endotoxin-induced septic shock

The lack of efficacy of anti-inflammatory drugs, anti-coagulants, anti-oxidants, etc. in critically ill patients has shifted interest towards developing alternative treatments. Since inhibitors of the nuclear enzyme poly-(ADP-ribose) polymerase (PARP) were found to be beneficial in many pathophysiological conditions associated with oxidative stress and PARP-1 knock-out mice proved to be resistant to bacterial lipopolysaccharide (LPS)-induced septic shock, PARP inhibitors are candidates for such a role. In this study, the mechanism of the protective effect of a potent PARP-1 inhibitor, PJ34 was studied in LPS-induced (20mg/kg, i.p.) septic shock in mice. We demonstrated a significant inflammatory response by magnetic resonance imaging in the dorsal subcutaneous region, in the abdominal regions around the kidneys and in the inter-intestinal cavities. We have found necrotic and apoptotic histological changes as well as obstructed blood vessels in the liver and small intestine. Additionally, we have detected elevated tumor necrosis factor-alpha levels in the serum and nuclear factor kappa B activation in liver of LPS-treated mice. Pre-treating the animals with PJ34 (10mg/kg, i.p.), before the LPS challenge, besides rescuing the animals from LPS-induced death, attenuated all these changes presumably by activating the phosphatidylinositol 3-kinase-Akt/protein kinase B cytoprotective pathway.

The existence of biexponential signal decay in magnetic resonance diffusion-weighted imaging appears to be independent of compartmentalization.

It is generally believed that the apparent diffusion coefficient (ADC) changes measured by diffusion‐weighted imaging (DWI) in brain pathologies are related to alterations in the water compartments. The aim of this study was to elucidate the role of compartmentalization in DWI via biexponential analysis of the signal decay due to diffusion. DWI experiments were performed on mouse brain over an extended range of b‐values (up to 10000 mm–2 s) under intact, global ischemic, and cold‐injury conditions. DWI was additionally applied to centrifuged human erythrocyte samples with a negligible extracellular space. Biexponential signal decay was found to occur in the cortex of the intact mouse brain. During global ischemia, in addition to a drop in the ADC in both components, a shift from the volume fraction of the rapidly diffusing component to the slowly diffusing one was observed. In cold injury, the biexponential signal decay was still present despite the electron‐microscopically validated disintegration of the membranes. The biexponential function was also applicable for fitting of the data obtained on erythrocyte samples. The results suggest that compartmentalization is not an essential feature of biexponential decay in diffusion experiments. Magn Reson Med 51:278–285, 2004.

BGP-15 — a novel poly(ADP-ribose) polymerase inhibitor — protects against nephrotoxicity of cisplatin without compromising its antitumor activity

Nephrotoxicity is one of the major dose limiting side effects of cisplatin chemotherapy. The antitumor and toxic effects are mediated in part by different mechanisms, thus, permitting a selective inhibition of certain side effects. The influence of O-(3-piperidino-2-hydroxy-1-propyl)nicotinic amidoxime (BGP-15) - a poly(ADP-ribose) polymerase (PARP) inhibitor - on the nephrotoxicity and antitumor efficacy of cisplatin has been evaluated in experimental models. BGP-15 either blocked or significantly reduced (60-90% in 100-200 mg/kg oral dose) cisplatin induced increase in serum urea and creatinine level in mice and rats and prevented the structural degeneration of the kidney, as well. The nephroprotective effect of BGP-15 treatment was revealed also in living mice by MRI analysis manifesting in the lack of oedema which otherwise developed as a result of cisplatin treatment. The protective effect was accompanied by inhibition of cisplatin-induced poly-ADP-ribosylation and by the restoration of the disturbed energy metabolism. The preservation of ATP level in the kidney was demonstrated in vivo by localized NMR spectroscopy. BGP-15 decreased cisplatin-induced ROS production in rat kidney mitochondria and improved the antioxidant status of the kidney in mice with cisplatin-induced nephropathy. In rat kidney, cisplatin caused a decrease in the level of Bcl-x, a mitochondrial protective protein, and this was normalized by BGP-15 treatment. On the other hand, BGP-15 did not inhibit the antitumor efficacy of cisplatin in cell culture and in transplantable solid tumors of mice. Treatment with BGP-15 increased the mean survival time of cisplatin-treated P-388 leukemia bearing mice from 13 to 19 days. PARP inhibitors have been demonstrated to diminish the consequences of free radical-induced damage, and this is related to the chemoprotective effect of BGP-15, a novel PARP inhibitor. Based on these results, we propose that BGP-15 represents a novel, non-thiol chemoprotective agent.

Inhibiting poly(ADP-ribose) polymerase: a potential therapy against oligodendrocyte death

Oligodendrocyte loss and demyelination are major pathological hallmarks of multiple sclerosis. In pattern III lesions, inflammation is minor in the early stages, and oligodendrocyte apoptosis prevails, which appears to be mediated at least in part through mitochondrial injury. Here, we demonstrate poly(ADP-ribose) polymerase activation and apoptosis inducing factor nuclear translocation within apoptotic oligodendrocytes in such multiple sclerosis lesions. The same morphological and molecular pathology was observed in an experimental model of primary demyelination, induced by the mitochondrial toxin cuprizone. Inhibition of poly(ADP-ribose) polymerase in this model attenuated oligodendrocyte depletion and decreased demyelination. Poly(ADP-ribose) polymerase inhibition suppressed c-Jun N-terminal kinase and p38 mitogen-activated protein kinase phosphorylation, increased the activation of the cytoprotective phosphatidylinositol-3 kinase-Akt pathway and prevented caspase-independent apoptosis inducing factor-mediated apoptosis. Our data indicate that poly(ADP-ribose) polymerase activation plays a crucial role in the pathogenesis of pattern III multiple sclerosis lesions. Since poly(ADP-ribose) polymerase inhibition was also effective in the inflammatory model of multiple sclerosis, it may target all subtypes of multiple sclerosis, either by preventing oligodendrocyte death or attenuating inflammation.

In vivo brain edema classification: New insight offered by large b-value diffusion-weighted MR imaging

To assess the role of large b‐value diffusion weighted imaging (DWI) in the characterization of the physicochemical properties of the water in brain edema under experimental and clinical conditions.

Facile Synthesis of Steroidal Phenyl Ketones via Homogeneous Catalytic Carbonylation

Steroidal phenyl ketones were synthesised in high yields by palladium-catalysed carbonylation reactions of 17-iodo-androst-16-ene derivatives in the presence of NaBPh4 under mild reaction conditions. Alkenyl bromides or enol triflates gave lower yields in the same reaction.

Ferulaldehyde, a Water-Soluble Degradation Product of Polyphenols, Inhibits the Lipopolysaccharide-Induced Inflammatory Response in Mice

Antiinflammatory properties of polyphenols in natural products, traditional medicines, and healthy foods were recently attributed to highly soluble metabolites produced by the microflora of the intestines rather than the polyphenols themselves. To provide experimental basis for this hypothesis, we measured antiinflammatory properties of ferulaldehyde (FA), a natural intermediate of polyphenol metabolism of intestinal microflora, in a murine lipopolysaccharide (LPS)-induced septic shock model. We found that intraperitoneally administered FA (6 mg/kg) prolonged the lifespan of LPS-treated (40 mg/kg) mice, decreased the inflammatory response detected by T(2)-weighted in vivo MRI, decreased early proinflammatory cytokines such as tumor necrosis factor-alpha and interleukin (IL)-1beta, and increased the antiinflammatory IL-10 in the sera of the mice. Additionally, FA inhibited LPS-induced activation of nuclear factor kappaB transcription factor in the liver of the mice. According to our data, these effects were probably due to attenuating LPS-induced activation of c-Jun N-terminal kinase and Akt. Furthermore, FA decreased free radical and nitrite production in LPS plus interferon-gamma-treated primary mouse hepatocytes, whose effects are expected to contribute to its antiinflammatory property. These data provide direct in vivo evidence, that a water-soluble degradation product of polyphenols could be responsible for, or at least could significantly contribute to, the beneficial antiinflammatory effects of polyphenol-containing healthy foods, natural products, and traditional medicines.

In vivo water quantification in mouse brain at 9.4 Tesla in a vasogenic edema model.

The aim of our study was to establish a simple in vivo method for water quantification in vasogenic edema, and provide data on imaging of mouse brain at 9.4 Tesla. Apparent T1 and spin density values determined by MRI were found to strongly correlate with the gravimetric water content of mouse brain undergoing cold injury. Using a two‐point calibration line between the spin density values for pure water and cortex of mouse brain, as well as the corresponding water contents in vivo, water could be quantified with satisfactory accuracy. Magn Reson Med 46:1246–1249, 2001.

Fast in vivo water quantification in rat brain oedema based on T1 measurement at high magnetic field

Summary.Summary. Background: In vivo water content determination based on magnetic resonance (MR) method is of importance in clinical practice as well as in animal studies to follow up the treatment given in order to reduce brain oedema. The methods proposed in the literature so far are largely time consuming. The aim of this study was to find a fast in vivo water quantification method having real advantage for patients suffering from critical conditions. Method: Cold injury was applied to provoke brain oedema in fourteen rats. T1 values of both the oedematous area and the contralateral normal cortex were determined by two independent methods 24 hours after the cold impact. First, from a series of images recorded by inversion recovery spin echo (IRSE) sequence and then by progressive saturation experiment performed by localised MR spectroscopy using stimulated echo acquisition mode (STEAM). To reduce the acquisition time, a two-element repetition time array was optimised for the STEAM experiment, whereas four inversion times were used for T1 mapping. Both methods were validated against gel phantoms with known T1 values. After the MR measurements the animals were sacrificed and the water contents of the regions of interest were determined by gravimetric wet-dry method. Findings: The reciprocals of the in vivo measured T1 values were correlated with the reciprocals of the brain water contents. STEAM experiment showed stronger correlation (r=0.96) than IRSE (r=0.93). In addition, STEAM provided more accurate T1 values in the phantom study. Determination of brain water content based on T1 measurement does work also at high magnetic field. Determination of brain water content by Magnetic Resonance Spectroscopy is feasible within 2 minutes. Interpretation: Using the presented fast method, water content can be determined within a couple of minutes in animal experiments as well as in the daily clinical practice.