Biomedical subjects

Alberto Machado

Publications and source records attributed to Alberto Machado.

22 records · Page 2Linked to original sources

PubMed2002

Differential regulation of glutamic acid decarboxylase mRNA and tyrosine hydroxylase mRNA expression in the aged manganese-treated rats.

Recent studies have implicated chronic elevated exposures to environmental agents, such as metals (e.g. manganese, Mn) and pesticides, as contributors to neurological disease. Eighteen-month-old rats received intraperitoneal injections of manganese chloride (6 mg Mn/kg/day) or equal volume of saline for 30 days in order to study the effect of manganese on the dopamine- and GABA-neurons. The structures studied were substantia nigra, striatum, ventral tegmental area, nucleus accumbens and globus pallidus. First, we studied the enzymatic activity of mitochondrial complex II succinate dehydrogenase (SDH). We found an overall decrease of SDH in the different brain areas analyzed. We then studied the mRNA levels for tyrosine hydroxylase (TH) and the dopamine transporter (DAT) by in situ hybridization. TH mRNA but not DAT mRNA was significantly induced in substantia nigra and ventral tegmental area following Mn treatment. Correspondingly, TH immunoreactivity was increased in substantia nigra and ventral tegmental area. Manganese treatment significantly decreased GAD mRNA levels in individual GABAergic neurons in globus pallidus but not in striatum. We also quantified the density of glial fibrillary acidic protein (GFAP)-labeled astrocytes and OX-42 positive cells. Reactive gliosis in response to Mn treatment occurred only in striatum and substantia nigra and the morphology of the astrocytes was different than in control animals. These results suggest that the nigrostriatal system could be specifically damaged by manganese toxicity. Thus, changes produced by manganese treatment on 18-month-old rats could play a role in the etiology of Parkinson's disease.

Aging↗

PubMed2002

Impairment of mineralocorticoid receptor (MR)-dependent biological response by oxidative stress and aging: correlation with post-translational modification of MR and decreased ADP-ribosylatable level of elongating factor 2 in kidney cells.

Acute and chronic treatments of mice with the glutathione-depleting agent, L-buthionine-(SR)-sulfoximine (BSO), impaired the mineralocorticoid receptor (MR)-dependent biological response by inhibiting aldosterone binding. This steroid-binding inhibition was fully reversed when reducing agents were added to kidney cytosol obtained from mice treated for 5 h, but it was only partially reversed in cytosol obtained from mice treated for 10 days. Although the oligomeric structure of the MR-hsp90 heterocomplex was always unaffected, a decreased amount of MR protein was evidenced after the long term treatment. Such a deleterious effect was correlated with a post-translational modification of MR, as demonstrated by an increased level of receptor carbonylation. In addition, a failure at the elongation/termination step was also observed during the receptor translation process in a reticulocyte lysate system. Thus, a high polyribosomes/monomers ratio and both increased proteolysis and decreased ADP-ribosylatable concentration of elongation factor 2 (EF-2) were shown. Importantly, similar observations were also performed in vivo after depletion of glutathione. Notwithstanding the EF-2 functional disruption, not all renal proteins were equally affected as the MR. Interestingly, both EF-2 and MR expressed in old mice were similarly affected as in L-buthionine-(SR)-sulfoximine-treated young mice. We therefore propose that a dramatic depletion of glutathione in kidney cells mimics the cumulative effect of aging which, at the end, may lead to a renal mineralocorticoid dysfunction.

ADP-Ribosylation Factors↗

PubMed2002

Melatonin induces tyrosine hydroxylase mRNA expression in the ventral mesencephalon but not in the hypothalamus.

We have evaluated the effect of chronic administration of melatonin in terms of mRNA expression for tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, and in the terms of dopamine (DA) transporter (DAT) by means of in situ hybridization. Experimental rats received daily late afternoon injections of 1.5 mg/kg melatonin for 30 days and analysis were performed in the ventral mesencephalon including the substantia nigra (SN) and ventral tegmental area (VTA), and hypothalamus. In the ventral mesencephalon, melatonin treatment significantly induced TH mRNA levels in individual dopaminergic neurons in SN and VTA. In contrast, DAT mRNA levels remained at control levels. Striatal synaptosomal DA uptake was not modified by melatonin treatment as compared with controls. Analysis of glutamic acid decarboxylase (GAD) mRNA in SN, the biosynthetic enzyme for GABAergic neurons, revealed no effect of melatonin treatment on mRNA levels for this marker. In the hypothalamus, we performed mRNA quantitation for TH in arcuate nucleus (Arc) and supraoptic nucleus (SO). Melatonin treatment failed to alter mRNA levels in either area. We detected weak but significant mRNA levels for DAT in Arc, SO, zona incerta (ZI) and periventricular hypothalamic nucleus (Pe). However, because of the low levels of mRNA in hypothalamic areas we were unable to perform a reliable measurement of DAT mRNA levels in response to melatonin treatment. We conclude that melatonin administration, that combines antioxidant capacity and a tissue-specific TH inducing effect, may be useful as a pharmacological agent to protect dopaminergic neurons from degeneration.

Animals↗

PubMedDate not supplied

[DIGESTIVE TUBERCULOSIS IN THE EDGARDO REBAGLIATI MARTINSHOSPITAL (HNERM): A RETROSPECTIVE STUDY OVER A FIVE-YEAR PERIOD (1993-1998)]

INTRODUCTION: Tuberculosis is a common disease in Peru.Although there is evidence of the decrease in lung infections, abdominaltuberculosis and other extrapulmonary varieties show an increase in incidence. This study was performed in order lo determine incidence, clinical picture, diagnostic methods and procedures, compromised tissues and organs and treatment given to patients with Digestive Tuberculosis in the Hospitalization Area of the Digestive Disease Department of the Peruvian "Edgard Rebagliati Martins" Hospital in Lima-Peru, a 1-500 bed Center. METHODS: 77 clinical records were reviewed, of patients discharged and diagnosed with Abdominal or Digestive Tuberculosis between January 1993 to May 1998. Fifty eight of these records fuifilled the requirements. Results: The mean duration of symptoms was 5.49 months. The clinical characteristics are unspecific. The most frequent symptoms were weight loss, chronic diarrhea, abdominal pain and fever (over 70% of cases). The most common signs were abdominal pain, ascites and cachexia in more than 50% of the cases. The Laboratory tests are typical for chronic diseases and emphasize the erythrocite sedimentation rate that was high in 98% of cases. Adenosin Deaminase Assay (ADA) in ascific fluid was high in 95% of cases when peritoneal compromise was present and fluid could be obtained. The Radiology tests such as barium colon enema and intestinal transit tests were helpful together with Ultrasound and Computerized Tomography in detecting the intestinal location of the disease, the organs that had been affected as well assisting as to the decision to perform further invasive tests. We found 27.58% with gastrointestinal location, 43% with only peritoneal affection and 27.58% of mixed forms (gastrointestinal plus peritoneal). The endoscopic procedures have been decisive for the diagnosis of up to 90% of cases and Laparascopy has been of value, in up to 70% of the cases, for the detection of peritoneal affection. Six patients of our series have required exploratory Laparascopy for diagnosis. Treatment has been effective in 86% of cases. CONCLUSION: The diagnosis of Digestive Tuberculosis continues to be long, tedious and expensive. The incidence of this disease has increased in our Hospitalization Center since 1993. All cases reviewed require invasive procedures (endoscopic) or surgery for their final diagnosis. We emphasize the use of Laparoscopy tests for the evaluation of p0eritoneal affection.

Journal Article↗