Biomedical subjects

R Cortés

Publications and source records attributed to R Cortés.

At least 55 records · Page 3Linked to original sources

PubMed1991

[Obtainment of pineapple juice powder by foam-mat drying].

The foam-mat production and stability using pineapple juice concentrate (25, 30 and 40 degrees Brix), adding a surfactants mixture and maltodextrin (DE 10) as co-adjuvant, stirred in a commercial mixer, was studied. Adequate foam formation conditions were as follows: concentrate of 25 degrees Brix using surface active agents (Sorbac 60-Polisorbac 80) 0.285% surface active agent/total solids, HLB = 6, and stirring time, 7 min. The foam was dehydrated in an oven dried with a horizontal air flow circulation set at 60, 70 and 80 degrees C using 3, 5 and 10 mm bed depths. The best conditions were obtained at 60 degrees C and 5 mm bed depth. The product had a particle size of sieve 40-80, and a moisture content of 3%. It was then packaged in multilayer plastic film and stored at environmental conditions. No brown color formation or mold growth was detected during storage. Pineapple juice and a refreshing drink were prepared. The general acceptability in a community indicated that 95% of the population involved accepted the product.

Beverages↗

PubMed1990

Differential effects of intracerebroventricular colchicine administration on the expression of mRNAs for neuropeptides and neurotransmitter enzymes, with special emphasis on galanin: an in situ hybridization study.

The axonal transport blocker colchicine has been extensively used in immunohistochemical studies to induce accumulation of neuroactive compounds, especially neuropeptides, in neuronal somata and thus improve their visualization. To assess whether colchicine might, in addition, influence the synthesis of such compounds, we have now used in situ hybridization to examine the levels of mRNAs encoding for several neuropeptides (galanin [GAL], cholecystokinin [CCK], somatostatin [SOM], neuropeptide Y [NPY]) and neurotransmitter-synthesizing enzymes (choline acetyltransferase [ChAT], tyrosine hydroxylase [TH], amino acid decarboxylase [AADC], and glutamic acid decarboxylase [GAD]) after intraventricular administration of the drug. The results show that colchicine differentially modifies the levels of several mRNA species in different brain areas. Thus GAL mRNA levels increase in virtually all regions examined, including the basal forebrain, hypothalamus, dorsal raphe nucleus, locus coeruleus, and nucleus tractus solitarii. In addition, after colchicine treatment, GAL mRNA appears to be induced in the ipsilateral hemisphere in regions such as the cortex, hippocampus, striatum, lateral septum, and some nuclei of the thalamus as well as within white matter, where it cannot be detected in control animals. Although GAL mRNA in the vast majority of cases is neuronal, some findings indicate a possible glial localization. In parallel, colchicine depletes ChAT mRNA and increases GAD mRNA in the basal forebrain and striatum and decreases AADC mRNA in the dorsal raphe nucleus and locus coeruleus. In the latter nucleus, NPY and TH mRNA levels are increased by colchicine. In contrast, TH mRNA and also CCK mRNA levels decrease in the substantia nigra. In the cortex, hippocampus, and thalamus ipsilateral to colchicine injection CCK mRNA levels are markedly decreased, whereas SOM mRNA is decreased and NPY mRNA increased in the hippocampus but unchanged in the cortex. The results are discussed with reference to the possible artifacts that the use of colchicine might induce in immunohistochemical mapping studies and in relation to possible neurotoxic actions of colchicine, in some cases perhaps related to impaired retrograde transport of growth factor(s).

Animals↗

PubMed1990

Peptides and transmitter enzymes in hypothalamic magnocellular neurons after administration of hyperosmotic stimuli: comparison between messenger RNA and peptide/protein levels.

In situ hybridization histochemistry and indirect immunofluorescence histochemistry were used to study changes in the expression of vasopressin (VP), oxytocin (OXY), tyrosine hydroxylase (TH), galanin (GAL), dynorphin (DYN) and cholecystokinin (CCK) in hypothalamic magnocellular neurons of the paraventricular (PVN) and supraoptic (SON) nuclei of rats. After prolonged administration of 2% sodium chloride as drinking water (salt-loading), the treatment increased the levels of VP, OXY, TH, GAL, DYN and CCK mRNA in the PVN and SON. The increase in CCK mRNA was, however, proportionally higher in the PVN than in the SON. Within cell bodies of the PVN and SON of salt-loaded rats, a depletion of VP- and OXY-like immunoreactivity (LI) and an increase in TH-LI were seen. In salt-loaded/colchicine-treated rats, a marked decrease in GAL- and DYN-LI, but no specific changes in CCK-LI were observed. Within nerve fibers of the posterior pituitary of salt-loaded rats, a marked depletion of VP-, GAL- and DYN-LI was found. Less pronounced depletion was observed in OXY- and CCK-LI, and no specific changes in TH-LI were seen. The results show that high plasma osmolality induces increased mRNA levels for VP, OXY, TH, GAL, DYN and CCK, presumably indicating increased synthesis, an increased export from cell somata of VP, OXY, GAL and DYN, and a decrease in levels of these peptides in the posterior pituitary, suggesting increased release. The catecholamine-synthesizing enzyme TH, however, which has a cytoplasmic localization and is not released from nerve endings, remains high in the cell bodies and nerve endings during this state of increased activity.

Administration, Oral↗

PubMed1990

Neuropeptide gene expression in hypothalamic magnocellular neurons of normal and hypophysectomized rats: a combined immunohistochemical and in situ hybridization study.

Hypothalamic magnocellular neurons of the paraventricular and supraoptic nuclei contain several peptides and non-peptide putative neurotransmitters co-existing with vasopressin and oxytocin. However, the functional role of these substances is still unknown. In the present paper the temporal course of changes in the expression of vasopressin, oxytocin, galanin, cholecystokinin, dynorphin and tyrosine hydroxylase in magnocellular hypothalamic neurons of rats subjected to hypophysectomy was examined. Following different survival times the animals were processed either for immunohistochemistry with antibodies against the above mentioned peptides or for in situ hybridization with synthetic oligonucleotide probes complementary to the mRNAs encoding for the peptides. The results obtained showed a marked rise in vasopressin mRNA levels at two days followed by a decrease up to 36 days of survival. Oxytocin mRNA responded to the lesion with a transient decrease, with its lowest values between five and seven days. This was followed by a recovery which almost reached normal values at 36 days of survival. The results also showed a marked, transient activation of the synthetic pathway for galanin and cholecystokinin. The numbers of cells expressing these peptides were maximal between five and seven days, and the respective mRNA levels were significantly increased at these survival times. This was followed by a decrease in the amount of galanin- and cholecystokinin-like immunoreactivity as well as in the levels of their respective mRNAs. Dynorphin-like immunoreactivity showed a course similar to that of galanin and cholecystokinin in operated animals. However, the amounts of dynorphin mRNA were significantly increased at two days, but were followed by a reduction at five days and remained low throughout the different survival times tested. The experiments performed with the tyrosine hydroxylase antibodies and probe showed undetectable levels of the enzyme and its mRNA in normal and hypophysectomized animals. These results demonstrate that, in magnocellular hypothalamic neurons, expression of several peptides occur in differential ways after hypophysectomy. The possibility is discussed that these changes represent part of the mechanisms underlying the process of degeneration and regeneration known to occur in magnocellular hypothalamic neurons after hypophysectomy.

Animals↗

PubMed1990

Effects of central nervous system lesions on the expression of galanin: a comparative in situ hybridization and immunohistochemical study.

We have used in situ hybridization and immunohistochemistry to study the expression of galanin mRNA and galanin-like immunoreactivity after decortication and lesions of the ventral hippocampus. After decortication the levels of both galanin mRNA and galanin-like immunoreactivity were increased in the dorsal raphe nucleus. In addition, in decorticated rats, but not in controls, galanin mRNA could be seen in dorsal and ventral nuclei of the thalamus and in the remaining parts of the cortex. Increases in galanin mRNA and galanin-like immunoreactivity were also observed in the septum-vertical diagonal band after electrocoagulation lesions of the ventral hippocampus. In contrast, no changes were found after ibotenic acid lesions of the same hippocampal area. These results suggest that increases in the expression of galanin occur in certain neuron populations after direct lesion of their axons and/or terminal fields.

Animals↗

PubMed1990

[Spontaneous bacterial peritonitis in the cirrhotic patient. A study by discriminant analysis].

Infection of peritoneal fluid in cirrhotic patients requires an early diagnosis and treatment. Different parameters have been used for the diagnosis of this complication, however, the statistical study has not used multivariable analysis techniques. We have therefore designed this work performing a discriminating analysis in order to find the best variable combination. Twenty-six cirrhotic patients who were consecutively admitted to our hospital have been studied. Total adn polymorphonuclear leukocytes, glucose, LDH, and lactic acid were determined in peritoneal fluid. Eighteen peritoneal fluids were classified as non infected and the rest as infected. The criteria obtained from the discriminating function which combines total leukocytes, LDH, and glucose has been chosen as optimal. The utility of discriminating analysis is discussed and we conclude with the need to verify in a later study the value of the calculated function.

Ascites↗

PubMed1990

Prevalence and characteristics of smoking among adolescents.

The purpose of this study was to determine the prevalence of smoking and factors associated to the use of cigarettes in the adolescent population of the Francisco Oller High School in Cataño, Puerto Rico. A survey was administered to 106 randomly chosen students, regarding previous use of cigarette, age of first exposure, source of cigarettes, and smoking among peers. The average age was 16 years old. Fifty six percent (56%) of the participants denied ever using cigarettes, 34.5% admitted having used cigarettes and 9.5% admitted to be smokers. A higher prevalence of cigarette experimentation was reported among females (43% versus 26% in males). Smoking was reported among 16% of males vs 3% of females. A 44% admitted having used cigarettes before 14 years of age. A 42.5% of the adolescents reported obtaining their knowledge of tobacco effect from the communication media. This data is similar to published information on adolescents smoking in the United States.

Adolescent↗

PubMed1989

Dopamine receptors in human brain: autoradiographic distribution of D1 and D2 sites in Parkinson syndrome of different etiology.

The distribution and density of dopamine D1 and D2 receptors were examined by autoradiography in postmortem brain tissue from patients with pathological diagnosis of Parkinson's disease, status lacunaris, clinical parkinsonism without neuropathological lesions and in age-matched controls. The D1 antagonist [3H]SCH 23390 and the D2 agonist [3H]CV 205-502 were used as ligands. No significant differences in the distribution or density of D1 or D2 receptors were found in Parkinson's disease in the areas examined, including the nucleus caudatus, putamen, globus pallidus and substantia nigra. In contrast, cases presenting lacunar lesions in the striatum showed marked decreases in D1 and D2 receptor densities in this region. Patients clinically diagnosed as parkinsonians but without Parkinson's disease lesions or striatal lacunar softenings showed reduced densities of D2 receptors in the nucleus caudatus and putamen, while in the substantia nigra the densities were comparable to controls. In the basal ganglia of these cases D1 receptors were slightly decreased.

Aged↗

PubMed1989

Dopamine receptors in human brain: autoradiographic distribution of D1 sites.

The distribution of dopamine D1 receptors has been determined in post mortem human brain tissues using in vitro receptor autoradiography, with ([3H]N-methyl) SCH 23390 as ligand. The highest densities of dopamine D1 sites were seen in the nucleus caudatus, putamen, globus pallidus pars medialis and substantia nigra. Intermediate densities were associated with the amygdala, mammillary bodies, cerebral cortex and CA1. The remaining part of the hippocampus as well as the diencephalon, brainstem and cerebellum contained low levels of [3H]SCH 23390 binding sites. The distribution of D1 receptors in the human brain closely resembles that reported for the rat brain. In addition, there was a good correlation between the anatomical localization of D1 sites and the distribution of dopaminergic nerve terminals in the central nervous system. The densities of D1 receptors in the human brain were observed to markedly decrease with age during the first decades of life. However, no further modifications were found beyond the age of 40 years. We did not observe any significant influence of other parameters such as gender and post mortem delay in our samples.

Aging↗

PubMed1989

Dopamine receptors in human brain: autoradiographic distribution of D2 sites.

We have studied the detailed anatomical distribution of D2 receptors in human post mortem brain tissue using quantitative autoradiographic techniques. D2 receptors were labeled using the specific D2 agonist [3H]CV 205-502 and the antagonist [3H]spiroperidol. The pattern of D2 receptor distribution observed with the two ligands was very similar. The highest densities were found in the nucleus caudatus, putamen, nucleus accumbens and olfactory tubercle followed by the substantia nigra, where D2 receptors were mainly concentrated in the pars compacta. Lower but still significant densities were associated with the lateral part of the globus pallidus and CA1 and CA3 fields of the hippocampus. The medial part of the globus pallidus, the dentate gyrus and the amygdala showed low to very low densities of D2 receptors. Almost negligible amounts of binding were observed in the olfactory bulb, diencephalon, brainstem, cerebellum and most parts of the neocortex. Our results are comparable with previously reported localizations of D2 receptors in the human and rat brain. We also report the lack of the so-called spirodecanone binding sites in the human brain. The localization of D2 receptors is compared with the distribution of D1 receptors.

Aging↗

PubMed1989

Neuropeptide expression in rat dorsal root ganglion cells and spinal cord after peripheral nerve injury with special reference to galanin.

The temporal course of changes in peptide expression in the dorsal root ganglia L4 and L5 and in the dorsal horn of the spinal cord has been studied in rats subjected to a sciatic nerve transection at a mid-thigh level following different survival times. Galanin-, substance P-, vasoactive intestinal polypeptide-, peptide histidine-isoleucine- and calcitonin gene-related peptide-like immunoreactivities have been studied both by immunohistochemistry and radioimmunoassay. Galanin messenger ribonucleic acid has also been studied by in situ hybridization in the dorsal root ganglia of normal and lesioned animals. In addition, a group of animals with a sciatic nerve crush was studied to compare possible differences in peptide expression after both types of lesions. The results show that the transection induces an increase in the number of cell bodies expressing galanin-like immunoreactivity in the ganglia, and that the galanin levels rise about 120-fold after three and 14 days of survival. This increase reflected increased synthesis of the peptide, since there was a rise in the galanin messenger ribonucleic acid already at 24 h post-lesion, which was maintained for at least 60 days. In the spinal cord there was an increase of staining in the midportion of the outer layers of the dorsal horn that corresponded to fibers thought to arise from cells of the dorsal root ganglia affected by the transection. Also a depletion of substance P-like and an increase in vasoactive intestinal polypeptide- and peptide histidine-isoleucine-like immunoreactivities in the dorsal root ganglia were confirmed. These changes were shown to be rapidly detectable and were paralleled by similar changes in the dorsal horn of the spinal cord. For calcitonin gene-related peptide the immunohistochemistry was inconclusive, and the radioimmunoassay showed no detectable changes. After nerve crush a transient increase in the number of galanin immunoreactive neurons was observed, as well as a decrease in the number of neurons showing substance P-like immunoreactivity. These changes were most noticeable between six and 14 days of survival. After this, peptide expression seemed to return slowly to normal, that is by day 45 post-crush only a few cells showed galanin-like, and many sensory neurons expressed substance P-like immunoreactivity. The results demonstrate that when primary sensory neurons are peripherally lesioned they respond in a complex manner, altering their normal production of peptides by increasing or decreasing their synthesis.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Dopamine- and cAMP-regulated phosphoprotein (DARPP-32) and dopamine DA1 agonist-sensitive Na+,K+-ATPase in renal tubule cells.

The cellular localization of DARPP-32, a dopamine- and cAMP-regulated phosphoprotein of Mr 32,000 that appears to mediate certain actions of dopamine in the mammalian brain by acting as an inhibitor of protein phosphatase 1, was studied in the kidney of several species. DARPP-32 mRNA and DARPP-32-like immunoreactivity were found in the cytoplasm of cells in the thick ascending limb of the loop of Henle. The specific dopamine DA1 agonist SKF 82526 caused a dose-dependent inhibition of Na+,K+-ATPase activity, which could be blocked by SCH 23390, a specific DA1 antagonist, and by PKI-(5-24) amide, a specific inhibitor of cAMP-dependent protein kinase. The results indicate that DA1 dopamine receptors and DARPP-32, an intracellular third messenger for dopamine, are part of the signal-transduction process for dopamine acting on renal tubule cells.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1989

Hypothalamic neurosecretory systems and their messenger molecules.

The distribution and cellular localization of several transmitters, transmitter synthesizing enzymes and peptides in the arcuate, paraventricular and supraoptic nuclei are described with special focus on coexistence of messenger molecules. The role of these compounds in various neuroendocrine events is discussed.

Animals↗

PubMed1988

Decreased densities of dopamine D1 receptors in the putamen and hippocampus in senile dementia of the Alzheimer type.

The density and distribution of dopamine D1 receptors as labeled with [3H]SCH 23390 was analyzed in post-mortem brain tissue from patients with senile dementia of the Alzheimer type (SDAT) and in controls using quantitative autoradiography. In SDAT patients D1 receptor densities were markedly decreased in parts of the hippocampus, with reductions of up to 89% compared to the control values in the molecular layer of the dentate gyrus, 57% in the strata oriens and pyramidalis of the CA1 and 74% in the CA3 subfields. Significant decreases in D1 receptors were also observed in the putamen (23%) but not in the caudate and substantia nigra. A slight but not significant decrease of D1 binding was observed in most external layers of the temporal and occipital cortices.

Aged↗

PubMed1988

Differential modification of muscarinic cholinergic receptors in the hippocampus of patients with Alzheimer's disease: an autoradiographic study.

We have used quantitative light microscopic autoradiographic techniques to analyze changes in muscarinic cholinergic receptors in the hippocampus in Alzheimer type dementia (ATD). The density and distribution of muscarinic cholinergic receptors has been correlated with the density of neurons, neuritic plaques and neurofibrillary tangles in the CA1 subfield of the hippocampus of control and ATD patients. The number of pyramidal cells per mm2 in the CA1 sector was significantly decreased in ATD cases as compared to controls, although there were large variations among cases. The most marked reductions in cell counts were observed in patients with a history of profound dementia. The densities of muscarinic receptors, as well as the proportions of M1 and M2 subtypes, in the CA1 sector and dentate gyrus were not significantly different between ATD and old non-demented patients. Neuritic plaques, even in high numbers, did not affect the density of muscarinic receptors; moreover, the densities of receptors over the neuritic plaques did not differ from the surrounding neuropil. However, in some ATD cases there was a marked decrease in the concentration of these receptors in the CA1 sector and subiculum, with no change in the proportions of muscarinic receptor sybtypes. These patients exhibited frequent extracellular remnants of neurofibrillary tangles (ghost tangles), but scarce neuritic plaques, and were those showing severe losses of pyramidal cells. There was a significant positive correlation between the total concentration of muscarinic receptors in the CA1 and the density of pyramidal cells, suggesting that decreases in receptor concentration result from a severe neuronal loss. We observed that the ratio of muscarinic receptors per pyramidal cell was significantly increased in ATD patients. This might indicate a possible up-regulatory mechanism for muscarinic receptors in the population of remaining neurons in ATD However, decreases of receptor numbers following severe neuronal fall out suggest that compensatory mechanisms are no longer possible in such cases. The question is raised whether these differences between cases reflect different diseases or different stages of the same disease.

Aged↗

PubMed1988

Neurotransmitter receptors in the avian brain. II. Muscarinic cholinergic receptors.

The characteristics and distribution of muscarinic cholinergic receptors were examined in the pigeon brain using in vitro receptor autoradiography. The antagonist N-[3H]methylscopolamine was used as ligand and the presence of the putative subtypes M1 and M2 of the muscarinic cholinergic receptors examined using carbachol and pirenzepine as displacers. The highest densities of muscarinic cholinergic receptors in the pigeon brain were localized in the paleostriatum augmentatum and the lobus parolfactorius, areas homologous to the mammalian corpus striatum. In contrast, the paleostriatum primitivum, corresponding to the mammalian globus pallidus, was poor in muscarinic cholinergic receptors. The rest of the telencephalon was also rich in muscarinic cholinergic receptors, while thalamic, hypothalamic and brainstem areas, as well as the tectum, presented intermediate densities, similar to the mammalian brain. Exceptions to that were the hippocampus, which was poorly labeled in the bird brain and the cerebellum, which presented intermediate to high densities of muscarinic cholinergic receptors in the bird brain. Preliminary pharmacological studies suggest differences between avian and mammalian receptor subtypes, since carbachol and pirenzepine apparently did not recognize two different receptor subpopulations.

Animals↗

PubMed1988

Neurotransmitter receptors in the avian brain. III. GABA-benzodiazepine receptors.

GABA/benzodiazepine (BZ) receptors were localized in the pigeon brain by in vitro receptor autoradiography using [3]flunitrazepam as ligand. Highest densities of binding sites were observed in the optic tectum, in the nucleus pretectalis, the nucleus intercollicularis and the substantia gelatinosa of the spinal cord. Intermediate densities were found in the forebrain, particularly the paleostriatum primitivum, the nucleus rotundus and the cerebellum. Low densities were detected in the midbrain and brainstem. The paleostriatum primitivum and cerebellum were enriched in receptors of the BZ type I, as indicated by their high affinity for compound CL 218872. The addition of GABA resulted in an enhanced binding of the ligand in all brain regions. All these results indicate that GABA/BZ receptors in the pigeon brain present similar pharmacological properties and comparable anatomical distribution to those in mammalian brain.

Animals↗

PubMed1988

Mapping dopamine receptors in the human brain.

We have investigated the anatomic localization of dopamine D1 and D2 receptors in the human brain using selective high affinity ligands for both types of dopamine receptors and the technique of receptor autoradiography. Dopamine D1 receptors were labeled in postmortem human brain tissue sections using the antagonist [3H]SCH 23390. Dopamine D2 receptors were labeled in consecutive tissue sections using the agonist [3H]205-502 and the antagonist [3H]spiroperidol. D1 and D2 dopamine receptors presented a heterogeneous distribution in the human brain. The highest concentrations of both D1 and D2 receptors were found in parts of the basal ganglia, particularly the nucleus caudatus and putamen. Lower concentrations were seen in other areas for example, the lateral globus pallidus was enriched in D2 receptors and the medial globus pallidus in D1 receptors. The substantia nigra contained intermediate densities of both D1 and D2, D1 receptors being present in higher concentrations. Dopamine D1 receptors were also localized in areas outside of the basal ganglia, particularly in the neocortex, amygdala and hippocampal formation. Dopamine D2 receptors were also present in areas outside of the basal ganglia, the most significant densities being found in the hippocampal formation. We observed a marked age-dependent decline in the density of D1 receptors during the first decades of life. In contrast, D2 receptor concentrations appeared to be unaltered with age. The distribution and densities of dopamine receptors were examined in 12 cases of Parkinson's disease and compared to a control adult population. No significant differences in density and distribution were seen for either D1 nor D2 receptors.

Adolescent↗