Plasmodium falciparum: limited genetic diversity of MSP-2 in isolates circulating in Brazilian endemic areas.

The genetic polymorphism of the surface merozoite protein 2 (MSP-2) was evaluated in Plasmodium falciparum isolates from individuals with uncomplicated malaria living in a Brazilian endemic area of Peixoto de Azevedo. The frequency of MSP-2 alleles and the survival of genetically different populations clones in 104 isolates were verified by Southern blot and SSCP-PCR. Single and mixed infections were observed in similar frequencies and the rate of detection of FC27 and 3D7 allelic families was equivalent. Eight alleles were identified and among them, the sequence polymorphism was mainly attributed to variations in the repetitive region. Interestingly, in three alleles nucleotide polymorphism was identical to that detected in a previous study, conducted in 1992, in a near Brazilian endemic area. This finding demonstrated the genetic similarity between two isolate groups, besides the certain temporal stability in the allelic patterns. The implications of these data for studies on the genetic diversity are also discussed.

RGC death in mice after optic nerve crush injury: oxidative stress and neuroprotection.

PURPOSE: To establish a method for morphometric analysis of retrogradely labeled retinal ganglion cells (RGCs) of the mouse retina, to be used for the study of molecular aspects of RGC survival and neuroprotection in this model; to evaluate the effect of overexpression of Cu-Zn-superoxide dismutase (CuZnSOD) on RGC survival after severe crush injury to the optic nerve, and to assess the effect of the alpha2-adrenoreceptor agonist brimonidine, recently shown to be neuroprotective, on RGC survival. METHODS: A severe crush injury was inflicted unilaterally in the orbital portion of the optic nerves of wild-type and transgenic (Tg-SOD) mice expressing three to four times more human CuZnSOD than the wild type. In each mouse all RGCs were labeled 72 hours before crush injury by stereotactic injection of the neurotracer dye FluoroGold (Fluorochrome, Denver, CO) into the superior colliculus. Survival of RGCs was then assessed morphometrically, with and without systemic injection of brimonidine. RESULTS: Two weeks after crush injury, the number of surviving RGCs was significantly lower in the Tg-SOD mice (596.6 +/- 71.9 cells/mm(2)) than in the wild-type control mice (863. 5 +/- 68 cells/mm(2)). There was no difference between the numbers of surviving RGCs in the uninjured retinas of the two strains (3708 +/- 231.3 cells/mm(2) and 3904 +/- 120 cells/mm(2), respectively). Systemic injections of brimonidine significantly reduced cell death in the Tg-SOD mice, but not in the wild type. CONCLUSIONS: Overexpression of CuZnSOD accelerates RGC death after optic nerve injury in mice. Activation of the alpha2-adrenoreceptor pathway by brimonidine enhances survival of RGCs in an in vivo transgenic model of excessive oxidative stress.

Bio-dissolution of spent nickel-cadmium batteries using Thiobacillus ferrooxidans.

In this study, the production of sulphuric acid in bioreactors with Thiobacillus ferrooxidans attached on elemental sulphur was investigated. These bioreactors reached a maximum H+ productivity of 80 mmol kg-1 d-1 of support. This medium was used for the indirect dissolution of spent nickel-cadmium batteries recovering after 93 days 100% of cadmium, 96.5% of nickel and 95.0% of iron. Moreover, recoveries higher than 90.0% were reached when anodic and cathodic materials were directly added to Thiobacillus ferrooxidans cultures with sulphur as the sole energy source. The results presented show an economic and effective method which could be considered the first step to recycle spent and and discarded batteries preventing one of the many problems of environmental pollution.

Hydrogen peroxide-induced motoneuron apoptosis is prevented by poly ADP ribosyl synthetase inhibitors.

The impact of oxidative stress (H2O2) was observed using purified rat motoneuron cultures and H2O2-induced dose-dependent motoneuron death was demonstrated. The apoptotic characteristics of cell death were studied morphologically and using the TUNEL technique. This H2O2-induced motoneuron death was inhibited by the poly ADP ribosyl synthetase (PARS) inhibitors benzamide and nicotinamide. These findings suggest the potential utility of PARS inhibitors in the treatment of neurodegenerative disorders such as amyotrophic lateral sclerosis, in which oxidative stress has been suspected to play an important etiopathogenic role.

Nitric oxide is a mediator of methamphetamine (METH)-induced neurotoxicity. In vitro evidence from primary cultures of mesencephalic cells.

METH is a monoaminergic toxic that destroys dopamine terminals in vivo. Oxidative mechanisms associated with DA metabolism are thought to play an important role in its toxic effects. These ideas were supported by the demonstration that CuZn-superoxide dismutase (CuZnSOD) transgenic mice were protected against the toxic effects of the drug. In the present study, we sought to determine if nitric oxide (NO) production was also involved in METH-induced neurotoxicity using primary cultures obtained from fetal rat mesencephalon. METH caused dose- and time-dependent cell death in vitro. Blockade of nitric oxide (NO) formation with several nitric oxide (NO) synthase blockers attenuated METH-mediated toxicity. Moreover, inhibition of ADP-ribosylation with nicotinamide and benzamide also provided protection against the toxicity of the drug. These results, together with our previous results in transgenic mice, support a role for free radicals in METH-induced toxic effects.

Involvement of oxidative and L-arginine-NO pathways in the neurotoxicity of drugs of abuse in vitro.

1. Inhibitors of nitric oxide (NO) formation or ADP-ribosylation attenuate methamphetamine (METH)- and methylenedioxymetamphetamine (MDMA)-induced neurotoxicity on dopaminergic and serotonergic cells in primary cultures. 2. They also prevent METH-induced reactive gliosis in dopaminergic cultures. 3. Overexpression of superoxide dismutase (SOD) in cells obtained from SOD-transgenic mice also attenuates drug-induced toxicity. 4. These data indicate a role for oxygen-based and NO free radicals in the mechanisms of cell death associated with drugs of abuse in vitro.

Developmentally regulated glycosylation of dopamine transporter.

The dopamine transporter (DAT) in rat striatum was examined during postnatal development and aging after photolabeling with [125I]DEEP. The DAT-[125I]DEEP protein complex from adult rats (2 months) appeared as a broad diffuse band in SDS-PAGE gels with average apparent molecular mass of about 80,000 Da as previously found. However, the molecular mass was lower at birth (day 0) and at postnatal ages 4 and 14 days. In aged rats (104 weeks), the molecular mass was slightly higher than that found in young adults (60 days). In binding experiments with [3H]BTCP, there were age-related differences in Kd and Bmax with decreases in both Kd and Bmax found in aged rats. Treatment of photolabeled membranes with neuraminidase caused a reduction in DAT molecular mass, but age-related differences were maintained. Treatment with N-glycanase greatly reduced or eliminated the age-related differences. Several DAT peptide-specific polyclonal antibodies immunoprecipitated DAT-[125I]DEEP protein complex at different developmental ages. Taken together, these results suggest differential glycosylation of rat DAT occurs during postnatal development and aging; the increase is due to increases in the N-linked sugars rather than changes in either sialic acid content or the polypeptide.

Reduction in dopamine transporter mRNA after cessation of repeated cocaine administration.

Male, Lewis rats were treated intravenously for 2 weeks with saline or cocaine using a dose and injection schedule that is similar to the doses and patterns of cocaine intake in self-administration studies. Ten days after cessation of treatment, dopamine transporter binding levels were decreased in the nucleus accumbens but not in the striatum. In situ hybridization studies revealed decreases in dopamine transporter mRNA that were restricted to cells of the interfascicular and caudal linear nuclei; these dopaminergic cell groups, found in the ventral tegmentum, project to the nucleus accumbens and other limbic areas. Other dopaminergic cell groups in midbrain which project mainly to other areas did not show a decrease in mRNA. These results indicate that gene expression can be altered many days after withdrawal from cocaine, and provide an example of transporter regulation by a change in gene expression.

Methamphetamine (METH) causes reactive gliosis in vitro: attenuation by the ADP-ribosylation (ADPR) inhibitor, benzamide.

We examined the effects of methamphetamine (METH) in an in vitro model of rat fetal mesencephalic cells. METH causes loss of dopamine (DA) cells and neuronal process degeneration. In addition, the drug causes an increase in reactive gliosis as shown by the number of cells that stain for and by the intensity of staining with a glial fibrillary acidic protein (GFAP) antibody. Co-incubation of METH-treated cells with benzamide, which is a known inhibitor of ADP-ribosylation (ADPR), attenuated METH effects on both DA and glial cells. However, the effects of benzamide were somewhat more prominent on the glial cells. These results suggest that ADP-ribosylation may play a very important role in the development of reactive gliosis after the administration of neurotoxic agents.

Protection by BTCP of cultured dopaminergic neurons exposed to neurotoxins.

This study presents 'in vitro' evidence for a protection of cultured dopaminergic neurons against the toxicity of 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenylpyridinium (MPP+) by pretreatment with BTCP, a selective and potent dopamine (DA) uptake blocker. Moreover, we show that, at low concentration (10 nM), treatment with MPP+, which is more selective than 6-OHDA for dopaminergic neurons, is followed by some regeneration of these neurons.

Dopamine transporter mRNA expression is intense in rat midbrain neurons and modest outside midbrain.

Dopamine transporter mRNA expression in individual neurons from the substantia nigra pars compacta. 'All' area, arcuate nucleus of the hypothalamus, retina, and olfactory bulb was assessed by in situ hybridization. High levels of expression were noted over individual neurons in midbrain nuclei; much lower expression was found in cells of the inner nuclear layer of the retina, glomerular cell layer of the olfactory bulb, and medial aspect of the arcuate nucleus of the hypothalamus. The low levels of expression in the latter nuclei are consistent with the paucity of effects of cocaine in visual and olfactory systems, failure to detect photoaffinity-labelled transporter protein in hypothalamus or olfactory bulb, and observations that little or no damage is found in dopaminergic neurons outside the basal midbrain in idiopathic Parkinsonism.