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J Rodrigo

Publications and source records attributed to J Rodrigo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Theoretical evidence of a salt bridge disruption as the initiating process for the alpha1d-adrenergic receptor activation: a molecular dynamics and docking study.

This study reports the building of the three-dimensional structure of the rat alpha1d-adrenergic receptor through a topology approach based on the structure of the rhodopsin receptor from cryoelectron microscopy. The validity and reliability of the receptor model were assessed through exhaustive molecular dynamics and docking studies. Some interesting ligand-receptor interactions were identified along with significant differences between the binding mode of agonists and antagonists. The importance of the disruption of a salt bridge as a possible initial event leading to receptor activation is discussed on the basis of data from mutagenesis and molecular dynamics studies.

Amino Acid Sequence↗
PubMed2001

Immunohistochemical localisation of neuronal nitric oxide synthase in the rainbow trout kidney.

The distribution of nitrergic nervous structures in the trout kidney was studied by peroxidase-linked ABC immunostaining procedures using a polyclonal antibody raised against the neuronal isoform of nitric oxide synthase. The nitrergic plexus reaches the kidney along the vasculature, mainly running with the postcardinal vein where nitrergic fibres, microganglia like cellular clusters and isolated neurones were detected. The atubular head-kidney only showed isolated nitrergic fibres close to the larger arteries. On the other hand, the collecting tubules, collecting ducts, large arteries and glomerular arterioles of the tubular middle and posterior trunks were innervated by nitrergic fibres even though immunoreactive neurones were also observed in close apposition to some tubular elements and large arteries. These results suggest that, according to morphofunctional differences between the fish and mammalian kidneys, nitrergic neural structures may be involved in the control of particular renal functions in the rainbow trout.

Animals↗
PubMed2001

Glutathione depletion, lipid peroxidation and mitochondrial dysfunction are induced by chronic stress in rat brain.

Damage to the mitochondrial electron transport chain has been suggested to be an important factor in the pathogenesis of a range of neurodegenerative disorders. We have previously demonstrated that chronic stress induced an increase in nitric oxide (NO) production via an expression of inducible NO synthase (iNOS) in brain. Since it has been demonstrated that NO regulates mitochondrial function, we sought to study the susceptibility of the mitochondrial respiratory chain complexes to chronic restrain stress exposure in brain cortex. In adult male rats, stress (immobilization for six hours during 21 days) inhibits the activities of the first complexes of the mitochondrial respiratory chain (inhibition of 69% in complex I-III and of 67% in complex II-III), without affecting complex IV activity, ATP production and oxygen consumption. The mitochondrial marker citrate synthase is not significantly affected by stress after 21 days, indicating that at this time the mitochondrial structure is still intact. Moreover, the administration of the preferred inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (400 mg/kg i.p. daily from days 7 to 21 of stress) protects against the inhibition of the activity of complexes of the mitochondrial respiratory chain as well as prevents NO(x)(-) accumulation, lipid peroxidation and glutathione depletion induced by stress. These results suggest that a sustained overproduction of NO via iNOS is responsible, at least in part, of the inhibition of mitochondrial respiratory chain caused by stress and that this pathway also accounts for the oxidative stress found in this situation.

Adenosine Triphosphate↗
PubMed2001

Neuronal nitric oxide synthase immunoreactivity in the guinea-pig liver: distribution and colocalization with neuropeptide Y and calcitonin gene-related peptide.

AIMS/BACKGROUND: The innervation pattern of the guinea-pig liver is similar to that of the human liver. However, many aspects of the distribution of the neuronal isoform of the enzyme nitric oxide synthase (nNOS) in the guinea-pig liver and its colocalization with neuropeptides remain to be elucidated. METHODS: The distribution of nNOS was studied in fixed guinea-pig liver by light microscopic immunohistochemistry. Confocal analysis was used to determine its colocalization with neuropeptide Y (NPY) or calcitonin gene-related peptide (CGRP). RESULTS: nNOS-immunoreactive (nNOS-IR) nerves were observed in relation to hilar and interlobar vessels and in Glisson's capsule. A few nNOS-IR ganglia were observed in the extrahepatic bile duct and close to the interlobar portal triads. In addition, nNOS-IR fibers were located in the interlobular portal triads and pervading the parenchyma. Moreover, nNOS-IR nerves were demonstrated for the first time in the larger central veins and in the hepatic vein. nNOS-NPY and nNOS-CGRP colocalizations were detected in the fibromuscular layer of the bile duct and periductal plexus, respectively. CONCLUSIONS: These results support the phylogenetic conservation of the nNOS-IR hepatic innervation and its possible contribution to the regulation of hepatic blood flow and certain hepatic functions.

Animals↗
PubMed2000

Distribution of adrenomedullin-like immunoreactivity in the rat central nervous system by light and electron microscopy.

Adrenomedullin is a peptide of marked vasodilator activity first isolated from human pheochromocytoma and subsequently demonstrated in other mammalian tissues. Using a polyclonal antiserum against human adrenomedullin-(22-52) amide and the avidin-biotin peroxidase complex technique, we have demonstrated by light and electron microscopy that adrenomedullin-like immunoreactivity is widely distributed in the rat central nervous system. Western blotting of extracts of different brain regions demonstrated the fully processed peptide as the major form in the cerebellum, whereas a 14-kDa molecular species and a small amount of the 18-kDa propeptide were present in other brain regions. Immunoreactive neurons and processes were found in multipolar neurons and pyramidal cells of layers IV-VI of the cerebral cortex and their apical processes, as well as in a large number of telencephalic, diencephalic, mesencephalic, pontine and medullary nuclei. Cerebellar Purkinje cells and mossy terminal nerve fibers as well as neurons of the cerebellar nuclei were immunostained, as were neurons in area 9 of the anterior horn of the spinal cord. Immunoreactivity was also found in some vascular endothelial cells and surrounding processes that probably originated from perivascular glial cells. Electron microscopy confirmed the light microscopy findings and showed the reaction product in relation to neurofilaments and the external membrane of small mitochondria. Immunoreactive terminal boutons were occasionally seen. The distribution of adrenomedullin-like immunoreactivity in the central nervous system suggests that it has a significant role in neuronal function as well as in the regulation of regional blood flow.

Adrenomedullin↗
PubMed2000

Up-regulation of neuronal NO synthase immunoreactivity in opiate dependence and withdrawal.

RATIONALE: Nitric oxide (NO) has been postulated to contribute significantly to analgesic effects of opiates as well as to the development of tolerance and physical dependence to morphine. OBJECTIVE: The present study was undertaken to determine the effect of chronic morphine treatment and abstinence on the expression of neuronal NO synthase (neuronal NOS, nNOS) in several brain regions of mice. METHODS: Seven days after the implantation of a 75 mg morphine pellet, adult male CD1 mice received a SC dose of 1 mg/kg naloxone. Fifteen minutes after the naloxone injection, brains were removed and nNOS expression was studied by using immunohistochemical methods. RESULTS: Morphine-dependence produced an increase in the number of nNOS-positive cells in the main and accessory olfactory bulb, olfactory nuclei, cerebellum, locus coeruleus, medulla oblongata (nucleus of the solitary tract and prepositus hypoglossal nucleus), and a decrease in nNOS immunoreactivity in hypothalamus. The administration of naloxone to morphine-dependent mice to induce abstinence increased nNOS immunoreactivity in the hypothalamus and locus coeruleus. CONCLUSIONS: These results indicate that the chronic treatment with morphine leads to alterations in nNOS expression in important regions implicated in the physical tolerance and dependence to opiates and suggest the use of specific inhibitors of this isoform in these conditions.

Animals↗
PubMed2000

Asymmetrical bilateral traumatic hip dislocation with ipsilateral acetabular fracture.

We report a case of simultaneous asymmetrical bilateral traumatic hip dislocation, with one hip dislocated anteriorly and the other posteriorly, with ipsilateral acetabular fracture, suffered in a traffic accident by a 36-year-old man. Closed reduction of both hips was performed, followed by delayed internal fixation of the acetabular fracture.

Acetabulum↗
PubMed2000

Conformational preferences of the potent dopamine reuptake blocker BTCP and its analogs and their incorporation into a pharmacophore model.

Molecular mechanics calculations using MM3-92 and ab initio quantum mechanical calculations using SPARTAN 5.0 were performed on the structurally similar PCP and BTCP, in which only the latter has a cocaine-like pharmacological profile as a dopamine reuptake blocker. Calculations were also performed on BTCP analogs with a methyl group in various positions of the cyclohexane ring. The results for the cis-2-methyl compound, which retains good pharmacological activity, allowed us to determine that an aryl-axial conformer is the biologically active form for at least some of the compounds in this series. However, an aryl-equatorial conformer presents the identical pharmacophore, as shown by superposition of the two conformers. X-ray crystallographic structures were also obtained for BTCP and related compounds with a 2-methyl group on the cyclohexane ring, with reasonable agreement between the computational and experimental results. Superposition studies were performed with two rigid analogs of cocaine which illustrate the optimal orientations of the ammonium hydrogen for monoamine transporters. There is excellent agreement between a 'back-bridged' cocaine analog that is optimal as a dopamine reuptake blocker and the previously proposed biologically active conformer of methylphenidate. However, BTCP is found to be a better fit to the 'front-bridged' cocaine analog that is optimal for a serotonin reuptake blocker.

Dopamine Uptake Inhibitors↗
PubMed2000

Chronic stress induces the expression of inducible nitric oxide synthase in rat brain cortex.

Long-term exposure to stress has detrimental effects on several brain functions in many species, including humans, and leads to neurodegenerative changes. However, the underlying neural mechanisms by which stress causes neurodegeneration are still unknown. We have investigated the role of endogenously released nitric oxide (NO) in this phenomenon and the possible induction of the inducible NO synthase (iNOS) isoform. In adult male rats, stress (immobilization for 6 h during 21 days) increases the activity of a calcium-independent NO synthase and induces the expression of iNOS in cortical neurons as seen by immunohistochemical and western blot analysis. Three weeks of repeated immobilization increases immunoreactivity for nitrotyrosine, a nitration product of peroxynitrite. Repeated stress causes accumulation of the NO metabolites NO2+ NO3- (NOx-) accumulation in cortex, and these changes occur in parallel with lactate dehydrogenase (LDH) release and impairment of glutamate uptake in synaptosomes. Administration of the selective iNOS inhibitor aminoguanidine (400 mg/kg i.p. daily from days 7 to 21 of stress) prevents NOx- accumulation in cortex, LDH release, and impairment of glutamate uptake in synaptosomes. Taken together, these findings indicate that a sustained overproduction of NO via iNOS expression may be responsible, at least in part, for some of the neurodegenerative changes caused by stress and support a possible neuroprotective role for specific iNOS inhibitors in this situation.

Animals↗
PubMed2000

Molecular and kinetic characterization and cell type location of inducible nitric oxide synthase in fish.

We have found conclusive evidence for inducible nitric oxide synthase (iNOS) activity in rainbow trout (Oncorhynchus mykiss) tissue by means of biochemical, immunohistochemical, and immunoblotting analyses. This Ca(2+)-independent enzyme uses L-arginine to produce nitric oxide and L-citrulline. It was significantly inhibited by the L-arginine analogs N(omega)-monomethyl-L-arginine and N(G)-nitro-L-arginine methyl ester. Kinetic analyses showed typical Michaelian behavior with no evidence of cooperative effects. The specific activities of the liver and head kidney enzymes were 27 and 106 pmoles. min(-1). mg protein(-1), respectively, with similar values for K(m) (11 microM), all of which correspond well with the values for other previously characterized iNOS. Western blot analyses revealed a single band of M(R) = 130 kDa tested with an iNOS antiserum. At the ultrastructural level, cells with NADPH-diaphorase activity and iNOS immunoreactivity were identified as being heterophilic granulocytes in head kidney tissue and neutrophils and macrophages in hepatic tissue. The presence of an iNOS isoform in these fish tissues implies that these cells are capable of generating nitric oxide, thus pointing to the potential role of this enzyme in fish defense mechanisms.

Animals↗
PubMed1999

Local administration of neurotrophic growth factor in subcutaneous silicon chambers enhances the regeneration of the sensory component of the rat sciatic nerve.

An experimental model for local administration of neurotrophic growth factor (NGF) in peripheral nerve lesions is tested. The model consists of a subcutaneous reservoir connected to the sciatic nerve neurorrhaphy. The right sciatic nerves were exposed, severed, and repaired at a level 1.5 cm proximal to their trifurcation. Then, a dome-shaped silicone reservoir connected to the proximal end of a silicone tube was placed subcutaneously in the dorsum of the experimental animal. The distal end of the connecting tube was located in the nerve neurorrhaphy. Two experimental groups were made: Group A (n = 90) received daily doses of a solution containing NGF-7S during the first 4 weeks after surgery and a single weekly dose thereafter. Within this group, three subgroups of 30 rats each were made: A-4 sacrificed 4 weeks after surgery, A-8 sacrificed after 8 weeks, and A-12 after 12 weeks. Group B (n = 90) received the same vehicle solution without NGF under the same schedule and volume as in Group A. Three subgroups were also made as in Group A depending on the survival period. In order to locate the neurons in the dorsal root ganglia, the retrograde tracer horseradish peroxidase was administered at the proximal stump of the sciatic nerve (tibialis branch), which was severed 1 cm distal to the sciatic trifurcation. In respect of the nonoperated side, the percentage between the number of dorsal root ganglia neurons in the NGF-treated group was significantly higher than in the control group (P < 0.001). These results demonstrate that percutaneous administration of multiple doses of NGF in this model enhances sensory nerve regeneration after sciatic lesions evaluated by horseradish peroxidase labeling of dorsal root ganglia neurons.

Animals↗
PubMed1999

Selective nitrergic neurodegeneration in diabetes mellitus - a nitric oxide-dependent phenomenon.

1. In vitro and in vivo studies have demonstrated a dysfunctional nitrergic system in diabetes mellitus, thus explaining the origin of diabetic impotence. However, the mechanism of this nitrergic defect is not understood. 2. In the penises of streptozotocin (STZ)-induced diabetic rats, here, we show by immunohistochemistry that nitrergic nerves undergo selective degeneration since the noradrenergic nerves which have an anti-erectile function in the penis remained intact. 3. Nitrergic relaxation responses in vitro and erectile responses to cavernous nerve stimulation in vivo were attenuated in these animals, whereas noradrenergic responses were enhanced. 4. Activity and protein amount of neuronal nitric oxide synthase (nNOS) were also reduced in the penile tissue of diabetic rats. 5. We, thus, hypothesized that NO in the nitrergic nerves may be involved in the nitrergic nerve damage, since only the nerves which contain neuronal NO synthase underwent degeneration. 6. We administered an inhibitor of NO synthase, N(G)-nitro-L-arginine methyl ester (L-NAME), in the drinking water of rats for up to 12 weeks following the establishment of diabetes with STZ. 7. Here we demonstrate that this compound protected the nitrergic nerves from morphological and functional impairment. Our results show that selective nitrergic degeneration in diabetes is NO-dependent and suggest that inhibition of NO synthase is neuroprotective in this condition.

Animals↗
PubMed1999

Regeneration of the motor component of the rat sciatic nerve with local administration of neurotrophic growth factor in silicone chambers.

The experimental model reported consists of a subcutaneous reservoir connected to a rat sciatic nerve anastomosis. The right sciatic nerve was exposed, served, and repaired at a level 1.5 cm proximal to its trifurcation. Then, a dome-shaped silicone reservoir, connected to the proximal end of a silicone tube, was placed subcutaneously in the dorsum of the experimental animal. The distal end of the connecting tube was located at the nerve anastomosis. There were two experimental groups: Group A animals (n = 90) received daily doses of a solution containing nerve growth factor (NGF)-7S during the first 4 weeks after surgery and a single weekly dose thereafter. Within this group, there were three subgroups of 30 rats each: A-4 sacrificed at 4 weeks after surgery: A-8 sacrificed at 8 weeks; and A-12 at 12 weeks. Group B animals (n = 90) received the same vehicle solution without NGF at the same schedule and volumes as in Group A. There were also three subgroups as in Group A, depending on the survival period: B-4 (n = 30); B-8 (n = 30); and B-12 (n = 30). In order to localize the motoneurons in the spinal cord, the retrograde tracer, horseradish peroxidase (HRP), was administered at the proximal stump of the sciatic nerve (tibialis branch) that was severed 1 cm distal to the sciatic trifurcation (1.5 cm distal to the nerve anastomosis). The number of spinal neurons in the NGF-treated group was statistically significantly higher than in the control group (p < 0.001). These results demonstrate that percutaneous administration of multiple doses of neurotrophic growth factor in this model enhances motor nerve regeneration after sciatic lesions, evaluated by HRP-labeling of spinal motoneurons.

Animals↗
PubMed1999

Cholinergic contraction is altered in nNOS knockouts. Cooperative modulation of neural bronchoconstriction by nNOS and COX.

Endogenous nitric oxide (NO) is a bronchodilator but its physiologic role in small airways is not clear. In this study, we investigated the role of endogenous NO in the regulation of bronchiolar tone in the small airways of wild type and NO synthase (NOS) isoform (eNOS and nNOS)-knockout mice. Pretreatment with the cyclooxygenase inhibitor indomethacin significantly enhanced electrical field stimulation (EFS)-induced contraction in the airways from all types of mice by approximately 60 to 170% (n = 8 in each case), whereas pretreatment with the NOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME) did not (n = 8). Combined pretreatment with L-NAME and indomethacin enhanced airway contraction of wild-type and eNOS-knockout mice to a significantly greater extent (i.e., by 140 to 290%) than did indomethacin alone (n = 8 for each). This potentiation by L-NAME was not seen in nNOS knockout mice (n = 8). Neither indomethacin nor L-NAME alone affected carbachol (CCh) potency or maximal efficacy in the airways of wild-type mice, whereas the combined pretreatment slightly enhanced the maximal response without altering the potency of CCh (n = 6). Our results show that both NO and prostaglandins modulate neuronal contraction of murine small airways. NO is produced by nNOS, which may be located in nerves, and its overall effects are tonically inhibited by cyclooxygenase products.

Animals↗
PubMed1999

Tuberculous pleural effusion in children.

STUDY OBJECTIVES: To describe the age distribution, clinical, laboratory, radiographic, and bacteriologic findings of pediatric patients with tuberculous pleural effusion. DESIGN: A retrospective study. PATIENTS AND METHODS: We have identified all cases of primary pulmonary tuberculosis in children < 18 years, reported to the health department. We have collected information from medical records regarding demographics, clinical findings, bacteriologic results, and evolution. Chest radiographs obtained at the time of initial evaluation were reviewed independently by two groups of radiologists who were blind to the clinical and epidemiologic data. RESULTS: Between January 1983 and December 1996, 175 children < 18 years were diagnosed as having primary pulmonary tuberculosis. Among them, 39 patients (22.1%) showed pleural effusion on chest radiograph. The mean age of patients with tuberculous pleural effusion was significantly higher (13.52+/-0.5 years vs 6.97+/-0.42 years). The sensitivity of the tuberculin test is 97.4% for an induration > or = 5 mm. Pleural fluid analysis shows a lymphocytic exudative effusion. Chest radiograph review showed unilateral pleural effusion in all cases. Pleural effusion was the sole radiographic manifestation in 41% of cases. Parenchymal disease is associated in 23 cases (59%). Bacteriologic confirmation of tuberculosis was achieved in 22 cases (56.4%). Cultures of pleural fluid and biopsy material both yielded Mycobacterium tuberculosis in 15 of 34 (44.1%) and 12 of 18 (66.6%), respectively, for samples under study. Pleural biopsy specimens showed granulomatous inflammation in 18 of 23 cases (78.3%). Antituberculous therapy for 6 to 9 months was effective in all cases. Transient side effects occurred in 1 of 39 patients (2.9%). CONCLUSIONS: Pleural effusion accounts for 22.1% of cases of pediatric pulmonary tuberculosis. Parenchymal consolidation is the most common associated radiographic finding. Bacteriologic confirmation was achieved in 56.4% of cases. A short course of chemotherapy is effective.

Adolescent↗
PubMed1998

Expression of neuronal nitric oxide synthase during embryonic development of the rat cerebral cortex.

The expression of neuronal nitric oxide synthase (nNOS) during the development of the rat cerebral cortex from embryonic day (E) 13 to postnatal day (P) 0 was analyzed by immunocytochemical procedures using a specific antibody against rat brain nNOS. Expression of nNOS was first seen on E14 in cells of Cajal-Retzius morphology located in the marginal zone. Neuronal NOS immunoreactivity persisted in this layer throughout the embryonic period and only began to decrease on E20, when neuronal migration is coming to an end. From E17 onwards, migrating neurons expressing nNOS were observed in the intermediate zone with their leading processes directed towards the cortical plate. At the same time, efferent nNOS-immunoreactive axons originating from cortical plate cells entered the intermediate zone. From E19 onwards, cells expressing nNOS and with the morphological characteristics of migrating cells were observed in and near the subventricular zone. Confocal analysis of double immunostaining for nNOS and glial fibrillary acidic protein or nestin showed no coexpression of nNOS and glial markers in these cells, suggesting that nNOS-positive cells leaving the subventricular zone were not glial cells. Commissural, callosal and fimbrial fibers were seen to express nNOS on E18 and E19. This expression decreased from E20 and was very weak on E21 and P0. The observations suggest that nitric oxide is synthesized during embryonic life in relation to maturational processes such as the organization of cerebral lamination, and is involved in controlling migrational processes and fiber ingrowth.

Animals↗
PubMed1998

Evaluation of peripheral nerve regeneration by nerve growth factor locally administered with a novel system.

An experimental model is presented for the local administration of neurotrophic substances at the site of peripheral nerve lesion. The model consists of a subcutaneously implanted silicone reservoir and a connecting tube with its distal end facing the severed and repaired nerve. Wistar rats (n = 180) were divided into two groups: a control group (saline-treated) (n = 90) and an NGF-treated group (n = 90). After sciatic nerve axotomy, an epineural repair was performed. NGF or saline were injected daily into the subcutaneous reservoir for the first 4 weeks after axotomy and weekly single dose between the 8th and 12th weeks. Both groups were divided into three subgroups of 30 animals each. The animals were sacrificed at 4, 8 and 12 weeks. Myelinated and non-myelinated axonal and thickness of myelin sheaths were quantified at the tibialis branch 25 mm distal to the nerve repair site. Axonal counts showed statistically significant differences between the treated and control groups at 4, 8 and 12 weeks. Finally, at 4 weeks the myelinated axons in the NGF group had significantly thicker myelin sheaths than in the control group. In comparison with other models of administration of different neurotrophic agents, NGF delivered through this system demonstrates a significant capacity for improving nerve regeneration without the problems inherent in multiple anesthesia, device exchange, or short half-life of the NGF single-dose administration.

Animals↗