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C Pardini

Publications and source records attributed to C Pardini.

At least 19 recordsLinked to original sources
PubMed2006

Cytochrome P450 and Parkinson's disease: protective role of neuronal CYP 2E1 from MPTP toxicity.

Elucidation of the biochemical steps leading to the 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP)-induced degeneration of the nigro-striatal dopamine (DA) pathway has provided new clues to the pathophysiology of Parkinson's Disease (PD). In line with the enhancement of MPTP toxicity by diethyldithiocarbamate (DDC), here we demonstrate how other CYP450 (2E1) inhibitors, such as diallyl sulfide (DAS) or phenylethylisothiocyanate (PIC), also potentiate the selective DA neuron degeneration in C57/bl mice. In order to provide direct evidence for this isozyme involvement, CYP 2E1 knockout mice were challenged with MPTP or the combined treatment. Here we show that these transgenic mice have a low sensitivity to MPTP alone, similarly to the wild type SVI, suggesting that it is likely that transgenic mice compensate for the missing enzyme. However, in these CYP 2E1 knockout mice, DDC pretreatment completely fails to enhance MPTP toxicity; this enhancement is instead regularly present in the SVI control animals. This study indicates that the occurrence of CYP 2E1 in C57/bl mouse brain is relevant for MPTP toxicity, and suggests that this isozyme may have a detoxificant role related to the efflux transporter of the toxin.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2000

Dopamine agonists and analogues have an antiproliferative effect on CHO-K1 cells.

Epidemiological studies have shown a reduced incidence of cancer in Parkinson's disease. Since nearly all parkinsonian patients with clinical impairment are treated with L-beta-3,4-dihydroxyphenylalanine (L-DOPA) and dopamine (DA)ergic agonists, a possibility exists that these therapeutic agents can influence the risk of cancer. We studied the antiproliferative effect of these therapeutic agents (and substances structurally correlated) on Chinese hamster ovary (CHO)-K1 cell growth. Among the compounds tested, apomorphine proved to be the most potent inhibitor of CHO-K1 cell growth, with an EC(50) of 3.35 +/- 0.12 micro M. The apomorphine analogues, apocodeine and hydroxyethylnorapomorphine, were less active as inhibitors of CHO-K1 cell growth. The activity of DA, 6-hydroxydopamine (6-OHDA), phenylethylamine (PEA), L-DOPA and bromocriptine as antiproliferative was one order of magnitude lower than that of apomorphine while pergolide was ineffective. To test whether or not the oxidative potential of these compounds was important for their antiproliferative effect, several antioxidants were assayed. Among them glutathione (GSH) and dithiothreitol (DTT) were effective in reversing the anti-proliferative effect of apomorphine, DA, 6-OHDA and PEA, conversely they did not work with bromocriptine. GSH and DTT are sulphydryl-reducing agents; while their effect could explain the efficacy against apomorphine, DA and 6-OHDA, it is difficult to understand why they should have any effect on PEA as this substance does not react with sulphydryl groups. The oxidative potential as a mechanism of action was also questioned by the results obtained with dihydrorhodamine 123, a probe that changes its fluorescent emission wave when oxidized. None of the compounds, with the exception of 6-OHDA, had any effect on the fluorescent emission wave of the probe at the maximal concentrations used to inhibit CHO-K1 cell growth. At concentrations five times higher, apomorphine and DA generated reactive oxygen species but PEA and bromocriptine did not. These data demonstrate that the antiproliferative effect of these compounds is not due to their oxidative potential, but another mechanism must be postulated.

Journal Article↗
PubMed1999

Apomorphine has a potent antiproliferative effect on Chinese hamster ovary cells.

Apomorphine is a potent non selective agonist at the D1 and D2 dopamine receptors acting both pre- and post-synaptically. In this report we describe a novel function of apomorphine, independent from its dopaminergic activity. Apomorphine inhibits Chinese hamster ovary (CHO)-K1 cell proliferation in a dose-dependent manner. The EC50 of apomorphine-induced inhibition of CHO-K1 cell proliferation determined by cell counting was 3.24 +/- 0.07 microM. Remarkably, the dose-response curve obtained by measuring the incorporation of [3H]thymidine was practically identical to the previous one giving an EC50 of 3.52 +/- 0.04 microM. The dopaminergic antagonists SCH23390 and spiperone at a concentration of 10 microM (well beyond their Kd values for the dopamine D1- and D2-like receptors respectively) were not able to antagonize the effect of apomorphine on CHO-K1 cell proliferation. Apomorphine exerts its effect early during incubation; CHO-K1 cells exposed to apomorphine for a period as short as 1 h and then allowed to grow for three days were significantly reduced in number with respect to untreated control cells. After four hours of exposition to apomorphine (10 microM) the antiproliferative effect was similar to that seen when this compound was present in the bath for all three days. Concentrations of apomorphine higher than 10 microM induced cell death, and the colony was completely destroyed at 50 microM. Cytometric analyses showed a significant accumulation of CHO-K1 cells in the G2/M phase.

Animals↗
PubMed1998

The embryonic expression pattern of 40 murine cDNAs homologous to Drosophila mutant genes (Dres): a comparative and topographic approach to predict gene function.

Nature often utilizes the same metabolic 'core groups' of interacting genes or 'pathways' in completely different organs, tissues and cellular compartments. Deciphering the physiological role of a particular gene in a living organism is therefore critical to understanding not only how a gene/protein works, but also where (in which tissue/organ) and when (at what developmental stage) it functions. We have performed systematic RNA in situ hybridization on a subset of murine genes homologous to Drosophila mutant genes, called Drosophila -related expressed sequences (Dres). This approach combines functional information derived from cross-species sequence comparisons and biochemical, physiological and pathological studies performed in the fly with knowledge of the spatial and temporal distribution of gene expression. Forty murine Dres were tested by RNA in situ hybridization on sagittal, coronal and transverse sections at three developmental stages, E10.5, E12.5 and E17.5. For some of them, whole mount in situ hybridization was performed at earlier stages. These data are valuable for establishing how the function of these genes and the genetic programs underlying the development of a particular tissue or organ have evolved during evolution. For example, six Dres genes showed restricted expression domains within the murine retina, suggesting a different role for each of these genes in eye development and functioning. Furthermore, the information derived from this combined approach will be instrumental in predicting the phenotypic consequences of gene dysfunction in both mouse mutants and human genetic diseases.

Animals↗
PubMed1996

L-deprenyl fails to protect mesencephalic dopamine neurons and PC12 cells from the neurotoxic effect of 1-methyl-4-phenylpyridinium ion.

L-Deprenyl, a monoamine oxidase (MAO)-B inhibitor, appears to slow down the progression of Parkinson's disease. While inhibition of MAO-B activity can account for some of the effects of this substance, the basis by which L-deprenyl slows the progression of the disease remains controversial. In recent years, a new mechanism of action has emerged that may explain the ability of L-deprenyl to increase neuronal survival. L-deprenyl has been reported to modify gene expression and protein synthesis in astrocytes and PC12 cells. In this study, we tested the ability of L-deprenyl to protect mouse mesencephalic cells from the toxicity of the 1-methyl-4-phenyl pyridinium ion (MPP+). We exposed mouse mesencephalic cell cultures to L-deprenyl (10 microM) and, 24 h later, to MPP+ (2.5 microM). On the fifth day after L-deprenyl and MPP+ exposition, cells were washed free of drugs, and the following day they were tested for dopamine uptake, intracellular dopamine content and tyrosine hydroxylase immunoreactivity. The experiments were performed either in the presence or in the absence of glia. It was found that L-deprenyl pretreatment failed to achieve any protection against MPP+ toxicity. The fall in dopamine uptake and intracellular dopamine content, and the diminution of tyrosine hydroxylase immunoreactivity observed in cells pretreated with L-deprenyl and then given MPP+ were not significantly different from the values observed in cells treated with MPP+ alone. Additional experiments performed in PC12 cells, confirmed the failure of L-deprenyl to abolish the toxicity of MPP+. Our data seem to be at variance with previous reports demonstrating that the MAO-B inhibitor L-deprenyl protects dopaminergic neurons against MPP+ toxicity [12,20]; furthermore they do not support alternative mechanisms of action of L-deprenyl against MPP+ toxicity.

1-Methyl-4-phenylpyridinium↗
PubMed1996

Emx1 and Emx2 show different patterns of expression during proliferation and differentiation of the developing cerebral cortex in the mouse.

Insights into the complex structure of the forebrain and its regulation have recently come from the analysis of the expression of genes that are likely to be involved in regionalization of this structure. We cloned four new homeo box genes, Emx1, Emx2, Otx1 and Otx2, and showed that in day 10 mouse embryos their expression domains are continuous regions of the developing brain contained within each other in the sequence Emx1 < Emx2 < Otx1 < Otx2. Recently Otx1 has been found to be specifically expressed during neurogenesis of layer 5 and 6 in the developing cerebral cortex. In order to better understand the role of Emx1 and Emx2 in the maturation of the cortex we analysed by in situ hybridization their expression patterns in the developing mouse cerebral cortex, from embryonic day 12.5 to adulthood. We found that Emx2 is expressed exclusively in proliferating cells of the ventricular zone whereas Emx1 is expressed in both proliferating and differentiated neurons, throughout the cortical layers and during all the developmental stages examined. Therefore, Emx2 gene products might control some biological parameters of the proliferation of cortical neuroblasts or of the subsequent cell migration of postmitotic neurons, leaving the cortical germinal zone. Conversely, Emx1 expression, which is confined exclusively to the dorsal telencephalon, characterizes most cortical neurons during proliferation, differentiation, migration and postnatal development and maturation.

Animals↗
PubMed1995

Role of excitatory amino-acids in diethyldithiocarbamate-induced cell death in mesencephalic cultures.

The effects of diethyldithiocarbamate (DDC) and DDC plus glutamate on mesencephalic cell cultures were investigated. DDC 10 microM was toxic for cell cultures as assessed by observation under a phase-contrast microscope and the drop in [3H]dopamine uptake. Moreover, DDC 1 microM greatly potentiated cell death induced by glutamate 10 and 50 microM. (+)MK801, a selective non-competitive antagonist of NMDA receptors, completely prevented the toxicity of the two neurotoxins.

Animals↗
PubMed1995

Cabergoline improves motor disability without modifying L-dopa plasma levels in fluctuating Parkinson's disease patients.

Studies on the influence of some dopamine agonists, particularly bromocriptine, on the pharmacokinetics of L-dopa have furnished contrasting results. Thus, any possible pharmacokinetic interaction should be taken into consideration when adding a new dopamine agonist to L-dopa treatment. In 12 Parkinson's disease (PD) patients with motor fluctuations, cabergoline was added in an 8-week study to their usual L-dopa/carbidopa therapy. Cabergoline was administered once a day at increasing doses of 0.5, 1, 2, and 3mg/day for a period of one week per dose, and 4mg/day for three weeks. Motor performance was assessed weekly evaluating the motor examination of the Unified Parkinson's Disease Rating Scale (UPDRS) and the patients' diaries of daily on-off time. Blood levels of both L-dopa and 3-O-methyldopa (3-OMD) were assayed by HPLC in two different days, over an 8-hour period, before initiating cabergoline and at the end of the study. The results of this study confirm that cabergoline is effective in the management of PD motor fluctuations without modifying L-dopa and 3-OMD pharmacokinetics.

Analysis of Variance↗
PubMed1992

Chinese hamster ovary cells deficient or proficient in O6-alkylguanine-DNA alkyltransferase activity are equally sensitive to X-rays.

In mammalian cells, under aerobic conditions, ionizing radiations and radiomimetic chemical agents can induce an enzymatic activity involved in DNA repair, O6-alkylguanine-DNA alkyltransferase (O6-AT). This catalytic protein is active against alkyl-radical-induced DNA damages. This induction was proposed to be linked to the formation of hydroxyl radicals. The possible involvement of O6-AT in the defense mechanism of the cell against aerobic radiation damage was investigated by comparing the X-ray sensitivity of two Chinese hamster ovary (CHO) cell lines, the first deficient (CHO mex-) and the second proficient by transfection of O6-AT (CHO mex+). The colony-forming ability after X-irradiation was appreciably reduced in CHO mex- in comparison to CHO mex+ cells. Nevertheless, pretreatment of proficient cells with O6-methylguanine, a specific inhibitor of O6-AT, reduced the DNA repair activity but did not modify the degree of sensitivity to X-rays of the CHO mex+ cells. Since the glutathione concentrations as well as the DNA damage amounts induced by X-irradiation were comparable in the variously treated cell lines, these results suggest that the observed induction of O6-AT by ionizing radiation in aerobic conditions could be a generalized rather than a specific response to damage by radicals.

Alkylation↗
PubMed1992

The ability of liver extracts from different-aged rats to repair 'mis-instructive' and 'non-instructive' lesions of DNA.

The ability to repair 'mis-instructive', O6-methylguanine, and 'non-instructive', AP sites, DNA lesions in Fischer 344 rat livers at various ages was determined. Different behaviours were observed. While the AP-endodesoxyribonuclease enzymes displayed a high constant level throughout the animals' lifetime, the O6-methylguanine-DNA methyltransferase activity presented a stepwise modulation (DNA normalisation of results): the O6-MT activity significantly increased within the first month of animal life and enhanced again after 6 months reaching a maximum plateau in the 12-18-month-old animals. Thereafter a net significant decrease of O6-MT enzyme was detected in the 24-month-old group. While the repair of the widely formed AP sites appeared uniformly efficient like 'house keeping' functions, the removal of the rare precancerous O6-methylguanine is age-dependent indicating a decreased protection of the youngest and oldest animals against this 'mis-instructive' damage. However, any extrapolation of the age-associated cancer risk needs further assessment.

Aging↗
PubMedDate not supplied

[Diurnal worsening in Parkinson patients treated with levodopa].

Parkinson's disease (PD) patients show a good response to levodopa in the morning, and reduced duration or complete failure of response later in the day, but the pathophysiology of this phenomenon remains unclear. We evaluated motor performance hourly over a twelve-hour period in patients treated with levodopa/carbidopa (group A), with bromocriptine (group B), and in "de novo" patients (group C). At 8 am, 12 and 4 pm, group A patients received standard doses of levodopa/carbidopa, whereas patients of group B and C took, respectively, 5 mg bromocriptine and placebo. In "de novo" patients and in patients under bromocriptine we did not observe significant diurnal changes in motor score, whereas in patients under levodopa a progressive daytime worsening, which significantly correlated with progressive increase in 3-O-methyldopa plasma levels, was visible. These data seem to indicate a contributory role of pharmacokinetic or pharmacodynamic factors related to levodopa assumption, rather than to the underlying disease, in the afternoon worsening in PD.

Bromocriptine↗