Biomedical subjects

J Cano

Publications and source records attributed to J Cano.

At least 91 records · Page 5Linked to original sources

PubMed1997

Low selenium diet increases the dopamine turnover in prefrontal cortex of the rat.

It has been proposed that interaction of catecholamines and indoleamines with free radicals may result in the formation of endogenous neurotoxins. In order to better understand the mechanisms involved in neurodegenerative disorders showing evidence of oxidative stress, we have studied the basal concentrations and the turnover rates of dopamine, noradrenaline, serotonin and their metabolites in the prefrontal cortex of rats that were fed on control or low selenium diets. Nutritional deficit of selenium decreases the brain antioxidant protection in experimental conditions by the decrease in glutathione peroxidase activity. The dopamine and serotonin turnover increased and noradrenaline and 5-hydroxy-3-indoleacetic acid turnover decreased compared to experimental control animals. The increase of dopamine turnover in experimental rats was accompanied by an increase in tyrosine hydroxylase activity. These results suggest that the decrease of brain protection against oxidative damage could induce brain damage by disturbing the turnover rate of some monoamines.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Less induced 1-methyl-4-phenylpyridinium ion neurotoxicity on striatal slices from guinea-pigs fed with a vitamin C-deficient diet.

The effect of ascorbic acid depletion on the 1-methyl-4-phenylpyridinium ion (MPP+)-induced neurotoxicity in the dopaminergic system has been tested in guinea-pig striatal slices. Guinea-pigs were divided into three groups and fed on a control diet, ascorbic acid-free diet and ascorbic acid-supplemented diet, respectively. Diets were maintained during 30 days. Striatal slices from ascorbic acid-deficient animals showed the highest levels of dopamine following 25 microM MPP+ treatment; the results from animals under this treatment condition were statistically different from both control and ascorbic acid-supplemented animals under identical experimental conditions. In addition, neurochemical analysis demonstrated that the levels of ascorbic acid and dehydroascorbic acid were highly reduced in striatal tissue from ascorbic acid-deficient animals, thus proving scorbutic conditions in our experimental animals. In view of the higher resistance of the ascorbic acid-deficient animals to the neurotoxicity elicited by MPP+, additional dopaminergic parameters were also measured in striatal tissue from ascorbic acid-deficient animals in the absence of MPP+, including levels of dopamine and its metabolites, tyrosine hydroxylase activity and dopamine uptake, with the aim of finding an explanation for this unexpected result. While dopamine levels and tyrosine hydroxylase activity remained close to control levels, dopamine uptake was significantly reduced in striatal synaptosomes from ascorbic acid-deficient animals as compared with control animals. Since MPP+ is actively accumulated into dopaminergic nerve terminals via the high-affinity dopamine uptake system, this finding could explain the higher resistance of ascorbic acid-deficient animals to the dopamine-depleting effect induced by MPP+ toxicity assayed in striatal slices.

1-Methyl-4-phenylpyridinium↗

PubMed1997

Chronic inhibition of the high-affinity dopamine uptake system increases oxidative damage to proteins in the aged rat substantia nigra.

The effect of chronic treatment of aged rats with nomifensine has been studied in the rat nigrostriatal dopaminergic system. The rat substantia nigra suffers an oxidative damage during aging that results in both an increase in carbonyl groups of its total proteins and the oxidative inactivation of tyrosine hydroxylase (TH) enzyme, which are partially reversed by chronic treatment with deprenyl. Different mechanisms may account for this effect, including inhibition of the high-affinity dopamine uptake system. We treated aged rats chronically with nomifensine for 2 months and found some significant effects. Nomifensine treatment significantly increased TH enzyme amount in substantia nigra (39.2%), which was accompanied by a significant increase in TH enzyme activity (47.8%). However, these effects were not observed in the terminal field (striatum). As a further step we quantified the oxidative level of proteins by measuring the number of carbonyl groups coupled either to total proteins or specifically to TH enzyme. The proteins of aged rat substantia nigra showed a significant increase of carbonyl groups following nomifensine treatment. The number of carbonyl groups coupled to nigral TH enzyme also increased in the nomifensine-treated animals. However, this increase was lower than that found in the total homogenate proteins. All these results show that the oxidative damage produced during aging in tyrosine hydroxylase enzyme and total proteins is not reduced by nomifensine treatment. On the contrary, the nomifensine treatment increased the oxidative damage to proteins. These results suggest the capability of deprenyl to induce TH enzyme could be due to inhibition of the high-affinity dopamine uptake system, but its ability to protect against oxidative damage is not produced by this mechanism.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Studies on keratinophilic fungi. IX: Neoarachnotheca gen. nov. and a new species of Nannizziopsis.

Neoarachnotheca is proposed as a new genus of Onygenales. The outstanding generic characteristics are white, spherical ascomata with a wall formed by a network of hyphae and spherical, subhyaline ascospores with an irregular sheath. Nt. keratinophila, the type species, characterized by wavy peridial hyphae has been isolated from marine and river sediments and Myriodontium keratinophilum is its anamorph. Nannizziopsis tropicalis is proposed as a new species based on a strain isolated from soil in Burundi. RFLPs analysis of ITS and 5.8S rDNA support these proposals. The differences with related genera are discussed.

Ascomycota↗

PubMed1997

The X1X2Y sex chromosome system in the fish Hoplias malabaricus. I. G-, C- and chromosome replication banding.

Hoplias malabaricus, a widely distributed neotropical fish (Central America to Argentina), may represent a group of distinct species showing diversified cytotypes with respect to chromosome number, morphology and sex systems. One of these karyotypic forms is characterized by an X1X1X2X2/X1X2Y sex chromosome system, with 2n = 40 and 39 chromosomes in females and males respectively. Analyses with G-, C- and chromosome replication banding permitted a better characterization of the sex chromosomes in this cytotype. The Y chromosome, unique in males, resulted from a translocation event between two biarmed chromosomes: one similar to chromosome 6 (X1) and the other one similar to chromosome 20 (X2), the latter corresponding to a probable identification. On the basis of the observed banding patterns, the Y chromosome may represent a stable dicentric, with an inactive centromere interstitially located on its long arm. The results are also related to a specific satellite DNA subfamily, previously characterized in Hoplias malabaricus, which appears to be associated with the X1 chromosome.

Aneuploidy↗

PubMed1997

Lack of involvement of glutamate-induced excitotoxicity in MPP+ toxicity in striatal dopaminergic terminals: possible involvement of ascorbate.

1. The present study concerns the possible relationship between glutamate excitotoxicity and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/1-methyl-4-phenylpyridinium (MPTP/MPP+) neurotoxicity on striatal dopaminergic terminals. 2. MPP+ neurotoxicity has been studied by means of two MPP+ perfusions separated by 24 h. After the second MPP+ 1 mM perfusion, dopamine extracellular output, measured by microdialysis, was considered to be an index of the dopaminergic neurone damage produced by the first MPP+ 1 mM perfusion. 3. High concentration (10 mM) of glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid (PDC) stimulated basal release of dopamine and protected against the neurotoxic effect of MPP+. 4. PDC 10 mM perfusion produced an increase in the extracellular output of glutamate and aspartate, and a decrease in that of ascorbate. 5. The protective effect against MPP+ toxicity observed with PDC 10 mM was completely abolished when this glutamate uptake inhibitor was co-perfused with ascorbate 0.5 mM. 6. These results suggest that glutamate-induced neurotoxicity is not involved in MPP+ toxicity. The protective effect found with the glutamate uptake inhibitor could be due to a decrease in extracellular ascorbate levels.

1-Methyl-4-phenylpyridinium↗

PubMed1997

Neuroprotective effect of the iron chelator desferrioxamine against MPP+ toxicity on striatal dopaminergic terminals.

Microdialysis was used to evaluate the effect of desferrioxamine (DES) against 1-methyl-4-phenylpyridinium (MPP+) toxicity. The presence of DES (40 fmol-40 nmol/15 min for a total of 90 min) in the Ringer solution, coperfused with MPP+ (40 nmol/15 min) on day 1, produced on day 2 a higher extracellular dopamine output after perfusion of MPP+ than in control MPP+ perfusion experiments, in which no DES was administered on day 1. Both Ringer perfusion alone (control Ringer) and coperfusion of 40 nmol DES with 40 nmol MPP+ on day 1 produced on day 2 similar increases in extracellular dopamine output after a second MPP+ perfusion. In the control Ringer experiment, note that the MPP+ on day 2 is the first MPP+ perfusion. Perfusion of 800 fmol FeCl3/15 min along with 40 nmol MPP+ and 400 fmol DES on day 1 completely abolished on day 2 the neuroprotective effect found with 40 nmol MPP+ and 400 fmol DES; 800 fmol FeCl3 did not increase the neurotoxic effect of 40 nmol MPP+ perfusion. The ability of DES to protect against MPP+ toxicity may indicate a therapeutic strategy in the treatment of diseases when iron is implicated.

1-Methyl-4-phenylpyridinium↗

PubMed1997

Time course changes in the dopaminergic nigrostriatal system following transection of the medial forebrain bundle: detection of oxidatively modified proteins in substantia nigra.

We studied the time course of oxidatively modified proteins in the nigrostriatal dopaminergic system following transection of the medial forebrain bundle by quantifying the number of carbonyl groups coupled to striatal and nigral protein homogenates, an index of metal-catalyzed oxidations. We found a striking effect of axotomy on the number of oxidatively modified proteins in the substantia nigra but not in the striatum within the first 5 days postlesion. This effect was correlated with the neurochemical activity of the dopaminergic and serotoninergic systems in the substantia nigra, which suggests a role of dopamine- and serotonin-derived radical oxygen species in the oxidative stress detected in this brain area. We then searched for the type of cell death in the substantia nigra following axotomy. The fragmentation pattern obtained by agarose gel electrophoresis of DNA isolated from nigral tissue was indicative of cell death being entirely necrotic. In fact, no evidence of apoptosis was detected at any postlesion time as revealed by TdT-mediated dUTP-biotin nick end-labeling (TUNEL) staining. The course of necrotic cell death in the substantia nigra coincided with the maximal levels of oxidatively modified proteins in the substantia nigra, suggesting a link between oxidative stress and nerve cell death and also coinciding with the neurochemical activity of both dopaminergic and serotoninergic systems.

Animals↗

PubMed1997

Increased activity and expression of tyrosine hydroxylase in the rat substantia nigra after chronic treatment with nomifensine.

We have studied the effect of chronic treatment with nomifensine on dopaminergic functioning in the nigrostriatal system. The striatal dopaminergic system was not altered by chronic nomifensine treatment. In contrast, there were overall decreases of different dopamine (DA) metabolites in the cell body region in the substantia nigra after nomifensine treatment, which clearly indicates a diminished DA turnover. These results suggest that long-lasting inhibition of the high affinity DA uptake system triggers long term regulatory, compensatory mechanisms in the cell body region to preserve normal dopaminergic function in the terminal field in striatum. We also tested whether transcriptional regulatory mechanisms were altered. We studied the cellular expression of tyrosine hydroxylase (TH) mRNA in substantia nigra by in situ hybridization, and the amount and activity of TH enzyme in the cell body and terminal field regions. Our results indicate that nomifensine treatment increased TH mRNA levels within individual nigral cells, which paralleled the changes in TH enzyme amount and activity in this brain area. Our data confirm the important role of the high affinity DA uptake system in regulating dopaminergic transmission in the nigrostriatal system.

Animals↗

PubMed1997

Deprenyl induces GFAP immunoreactivity in the intact and injured dopaminergic nigrostriatal system but fails to counteract axotomy-induced degenerative changes.

There is increasing evidence of a trophic-like mechanism for some effects ascribed to deprenyl therapy in the central nervous system. For that, we studied the effect of chronic treatment with deprenyl in an animal model of Parkinson's disease induced by unilateral knife transection of the medial forebrain bundle (MFB) in adult rats. The experimental conditions included a 3-week pretreatment with deprenyl before stereotaxic transection of the MFB. Following surgery, deprenyl treatment was maintained for 3 weeks. Neurochemical and immunohistochemical procedures were used to study the dopaminergic system and reactive astrocytes in the nigrostriatal system. Deprenyl treatment failed to counteract the axotomy-induced degenerative changes of the nigrostriatal dopaminergic system. However, it was effective in increasing the density of reactive astrocytes in terms of glial fibrillary acidic protein (GFAP) immunoreactivity in the intact contralateral substantia nigra and also in further enhancing the axotomy-induced increase of GFAP immunolabeled astrocytes in the lesioned substantia nigra. This deprenyl-induced effect on GFAP immunoreactivity was confined to substantia nigra without effect in striatum. In addition, we found a medial to lateral gradient decrease in the distribution pattern of GFAP immunolabeled astrocytes. Axotomy increased the number of reactive astrocytes in either striatal area examined, but yet the preferential distribution pattern of reactive astrocytes in striatum was still evident.

Animals↗

PubMed1996

Molecular differentiation of Keratinomyces (Trichophyton) species.

The taxonomy of the form-genus Keratinomyces (Trichophyton) within the group of the dermatophytes is based on morphological features which remain insufficient for the distinction of these anamorphic species. The three species included in the genus Keratinomyces, namely K. ajelloi, K. ceretanicus and K. longifusus were examined by means of their mitochondrial-like DNA diversity and compared to few other dermatophytes. The analysis of the mtDNA restriction fragments confirmed that the three species are different and well separate from the other dermatophytes.

Classification↗

PubMed1996

The utility of mitochondrial DNA restriction analysis in the classification of strains of Chrysosporium (hyphomycetes).

The taxonomy of the fungal genus Chrysosporium is mainly based on morphological features. In our current studies we have found several Chrysosporium species which showed intermediate morphological characteristics between several species. For this reason, we have carried out an analysis of the mitochondrial DNA restriction fragments of these strains that have permit us to classify each isolate strain in a species.

Chrysosporium↗

PubMed1996

MK-801 partially protects against the acute MPP+ depleting effect on dopamine levels in rat striatal slices.

We tested the ability of the non-competitive N-methyl-D-aspartate (NMDA) antagonist, dizocilpine (MK-801), to promote protection against the acute effect of 1-methyl-4-phenylpyridinium ion (MPP+) in rat striatal slices. Pretreatment with MK-801 at concentrations higher than 15 microM partially prevented the dopamine (DA)-depleting effect induced by further incubation with 25 microM MPP+ for 60 min in Mg(2+)-free conditions. Incubation of slices with 15 microM MK-801 without MPP+ only affected the levels of 3-methoxytyramine (3-MT). The ratio of 3-MT to 3,4-dihydroxyphenylacetic acid (DOPAC), a proposed index of DA reuptake inhibition, increased +68% of control levels, clearly suggesting an inhibitory effect of MK-801 on the high affinity DA transport system. To test this possibility, we performed a dose-response study of MK-801 on the high-affinity DA transport system in rat striatal synaptosomes. MK-801 induced a dose-dependent inhibition of DA uptake, with an IC50 of 57.0 microM. We present evidence that the protective effect rendered by MK-801 against the acute DA-depleting effect induced by MPP+ is not associated to NMDA receptor function, but rather to an inhibition of the high affinity DA uptake system.

1-Methyl-4-phenylpyridinium↗

PubMed1996

Oxidative inactivation of tyrosine hydroxylase in substantia nigra of aged rat.

Study of the tyrosine hydroxylase enzyme from substantia nigra and striatum during the aging period of the rat has discovered a significant decrease (55%) of TH activity in substantia nigra between 12 and 24 mo of age. The amount of TH in substantia nigra also decreased (30%) during aging. This loss in TH activity of substantia nigra appears to be produced by the decrease in TH content along with an inactivation process. Our finding showed a significant increase of carbonyl groups in the proteins of rat substantia nigra with aging. A statistically significant increase of carbonyl groups in TH enzyme was found in aged rat brain substantia nigra, indicating that oxidative damage could be the inactivation process that explains the decrease in TH activity found during aging. This hypothesis was corroborated by the fact that when rat striatal homogenate was incubated with hydrogen peroxide, there was a time-dependent decrease in TH activity, which highly correlated with measurements of carbonyl groups content of TH enzyme. The importance of these results may be in their relationship, considering that substantia nigra is preferentially affected in many neurodegenerative disorders.

Aging↗

PubMed1996

Nigral and striatal comparative study of the neurotoxic action of 1-methyl-4-phenylpyridinium ion: involvement of dopamine uptake system.

Microdialysis was used in a comparative study of the neurotoxic action of MPP+ in the absence or presence of nomifensine (20 microM) in the striatum and substantia nigra. Three different concentrations of MPP+ (1, 2.5, and 5 mM) were perfused for 15 min at 24 (day 1) and 48 h (day 2) after surgery. The dopamine basal value in the striatum was approximately 17 fmol/min. Nomifensine (20 microM) stimulated dopamine release to approximately 170 fmol/min. The increase of dopamine extracellular output in the striatum after MPP+ perfusion on day 1 was independent of the concentration of MPP+ perfused and of the absence or presence of nomifensine (20 microM), being approximately 2,500 fmol/ min. The dopamine basal value in the substantia nigra was below the detection limit of our HPLC equipment. Nomifensine (20 microM) stimulated dopamine release to approximately 6.3 fmol/min. The increase of dopamine extracellular output in the substantia nigra was MPP+ dose-dependent (1 mM, 75 fmol/min; 2.5 mM, 150 fmol/min; and 5 mM, 250 fmol/min) and independent of the presence or absence of nomifensine. On day 2, the presence of nomifensine on day 1 produced a total protection against MPP+ (1 mM) perfusion in the striatum, which was not observed against MPP+ (5 mM). MPP+ (1 mM) did not produce any neurotoxic action in the substantia in the absence or presence of nomifensine. The MPP+ (2.5 mM) effect on dopamine extracellular output in the absence of nomifensine (20 microM) in the substantia nigra on day 2 was similar to that of MPP+ (1 mM) in the striatum. The presence of nomifensine (20 microM) partially prevented the neurotoxic effect of MPP+ (2.5 mM) on dopaminergic cell bodies/ dendrites in the substantia nigra. The MPP+ (5 mM) effect on dopamine extracellular output was similar in both structures studied in the absence or presence of nomifensine on day 2. These results suggest that terminals in the striatum are more sensitive to the neurotoxicity of MPP+ then cell bodies/dendrites in the substantia nigra.

1-Methyl-4-phenylpyridinium↗

PubMed1996

Protection of the aged substantia nigra of the rat against oxidative damage by (-)-deprenyl.

1. We have studied the effect of (-)-deprenyl on the oxidative damage that the rat substantia nigra suffers during aging. 2. (-)-Deprenyl (2 mg kg-1, three times a week) administered for two months, beginning at 22 months of age, produced a significant increase in tyrosine hydroxylase (TH) activity (2.67 +/- 0.40 and 3.64 +/- 0.38 nmol mg-1 protein h-1 in untreated aged rats and treated aged rats respectively, P < 0.05) and in TH amount (0.072 +/- 0.012 and 0.128 +/- 0.38 absorbance 405 nm in untreated aged and treated aged rats respectively, P < 0.05). 3. The proteins of aged rat substantia nigra showed a significant decrease of carbonyl groups in treated animals compared with saline-injected control rats (136.2 +/- 21.8 and 71.5 +/- 13.2 c.p.m. microgram-1 protein in untreated aged and treated aged rats respectively, P < 0.05). 4. The carbonyl groups measured in TH enzyme showed a statistically significant decrease (42.3%) after (-)-deprenyl treatment (471.4 +/- 73.0 and 271.9 +/- 50.00 c.p.m. in untreated aged and treated aged rats respectively, P < 0.001). 5. All these results suggest that oxidative damage produced during aging is prevented by (-)-deprenyl treatment and could explain the effect of this drug in Parkinson's disease (PD) and other degenerative diseases such as Alzheimer's disease.

Aging↗

PubMed1996

Diagnostic value of three tumor markers determined in pleural effusions.

In order to discriminate between malignant and benign effusions, the values of tissue polypeptide specific antigen,carcinoembryonic antigen and squamous cell carcinoma associated antigen were measured in the pleural fluid of 30 patients with neoplasm, 10 with tuberculous pleurisy, 10 with transudates due to congestive heart failure or cirrhosis, 29 with parapneumonic effusions and 23 with benign diseases other than tuberculosis and pneumonia. Carcinoembryonic antigen and tissue poly-peptide specific antigen levels in effusions due to neoplasms were significantly higher than those in effusions due to other diseases. The areas under Receiver Operating Characteristic curves for carcinoembryonic antigen and tissue polypeptide specific antigen determinations were 0.69 and 0.67, respectively. No significant differences were found in the pleural fluid squamous cell carcinoma associated antigen levels between neoplasms and other diseases. The ability of tissue polypeptide specific antigen and carcinoembryonic antigen to discriminate between benign and malignant effusions may be considered comparable. Although both carcinoembryonic antigen and tissue polypeptide specific antigen showed a low accuracy (the number of undiagnosed pleural effusions is considerably high), both tissue polypeptide specific antigen and carcinoembryonic antigen determinations may contribute to a correct diagnostic classification. Moreover, the combination of these markers provides a specificity of 97.2%. However, the low number of positivities obtained for tissue polypeptide specific antigen and carcinoembryonic antigen together (13 cases in our series) reveals the need for further investigations.

Adult↗

PubMed1995

Implication of dopamine transporter system on 1-methyl-4-phenylpyridinium and rotenone effect in striatal synaptosomes.

The neurotoxic effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) seems to be produced by the inhibition of the respiratory chain by its metabolite 1-methyl-4-phenylpyridinium ion (MPP+). At the same time, its specific selectivity seems to be related especially to the dopamine uptake system. However, it is possible that other specific differences in dopaminergic neurons at the nigrostriatal system, such as constitutive metabolic deficiencies or other differences related to the energy capacity, could determine the greater vulnerability to MPP+. We have addressed this point by studying the effect of MPP+ and different inhibitors of the respiratory chain (rotenone, antimycin A and KCN) on the maximal respiratory rate from both synaptosomes and isolated synaptosomal mitochondria from different brain areas, i.e. cortex, hippocampus and striatum, and in isolated liver mitochondria. The results demonstrate the absence of differences in the effect of the inhibitors in isolated mitochondria. In contrast, a greater inhibition was found in striatal synaptosomes than in cortical or hippocampal synaptosomes when MPP+ and rotenone were used. Moreover, nomifensine or 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl) piperazine dihydrochloride (GBR-12909), inhibitor of the dopamine uptake system, has a protective effect in both cases. Our study indicates the great importance of the dopamine uptake system in the vulnerability of the dopamine striatum system. Moreover, our results show the low selectivity of this dopamine uptake system that is able to transport actively compounds with different chemical structures such as dopamine, MPP+ and rotenone.

1-Methyl-4-phenylpyridinium↗