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Biomedical subjects

G Rodriguez

Publications and source records attributed to G Rodriguez.

At least 145 records · Page 8Linked to original sources
PubMed1988

Studies on the tissue distribution of the puromycin-sensitive enkephalin-degrading aminopeptidases.

An antiserum generated to the soluble form of the rat brain puromycin-sensitive enkephalin-degrading aminopeptidase was used to determine the tissue distribution of the soluble and membrane-associated forms of this enzyme. All tissues examined contained significant levels of the soluble enzyme form, with this enzyme accounting for greater than 90% of the arylamidase activity in brain, heart, and skeletal muscle. Native gel electrophoresis coupled with activity staining as well as inhibition studies were used to confirm the presence of this enzyme in various tissues. Serum was found not to contain this particular aminopeptidase. In contrast to the results obtained with the soluble enzyme form, brain was the only tissue found to contain the membrane-associated enzyme form. Although all tissues contained membrane-associated aminopeptidase activity only the brain enzyme could be maintained in solution in the absence of detergent. In addition, the brain membrane-associated enzyme could be distinguished from the membrane-associated aminopeptidase activity in other tissues on the basis of its sensitivity to inhibition by puromycin.

Aminopeptidases↗
PubMed1987

Reduction of cerebral blood flow in subclinical hepatic encephalopathy and its correlation with plasma-free tryptophan.

Cerebral blood flow (CBF), measured by the noninvasive xenon-133 inhalation method, EEG, and plasma levels of ammonia (NH3) and free tryptophan were determined in 18 hospitalized cirrhotic patients affected with subclinical hepatic encephalopathy, as diagnosed by the Kurtz test. CBF results were significantly lower (p less than 0.001) in the patients' group as compared with a sex- and age-matched normal control population, although seven patients had values in the normal range. NH3 was increased only in six, while free tryptophan was increased in all but two patients. A significant negative correlation (p = 0.02) between CBF and free tryptophan was found, even though it appears to be difficult to interpret. We suggest that CBF impairment in some cirrhotic patients with subclinical hepatic encephalopathy may be related to the systemic metabolic derangement caused by the liver disease; free tryptophan could have some implication in producing CBF reduction.

Adult↗
PubMed1986

A simple technique for entrapping rifampicin and isoniazid into liposomes.

A method for the preparation of liposomes loaded with rifampicin and isoniazid is described. Optimal conditions were established; the lipid suspension was mixed with the aqueous solution of the drugs and was sonicated in a bath for 30 min at 50 degrees C. The optimum composition tested was phosphatidyl choline, cholesterol and cardiolipin in a molar ratio of 7:2:1. The separation of unloaded drug was performed by centrifugation through three successive Sephadex G-25 columns. The liposomes were multilamellar vesicles with a size ranging from 100-300 nm. The drugs were trapped in concentrations from 6.5-9.5 mg/ml. This method is suitable for preparation of liposomes in small laboratories.

Hot Temperature↗
PubMed1986

The use of rifampicin and isoniazid entrapped in liposomes for the treatment of Murine tuberculosis.

Liposomes loaded with rifampicin and isoniazid were used experimentally to treat mice with severe tuberculosis. The animals were distributed in four groups. The control group and the group treated with unloaded liposomes showed the severest disease. Both groups showed the lowest accumulated survival, about 50% after 30 days. The numbers of colony-forming-units (CFU) and root specific lung weight (RSLW) were the highest and the histopathology of the lung showed marked diffuse lesions. However, the group treated with unloaded liposomes showed significantly higher growth of M. tuberculosis compared with the control. The group treated with drug and drug loaded liposomes showed a higher survival, about 85% after 30 days, and the lowest values of CFU and RSLW. The lung histology revealed considerably less inflammation which was focal. The parameters evaluated indicated a significantly better response in the group of animals treated with rifampicin and isoniazid entrapped in liposomes.

Animals↗
PubMed1986

Angiotensin II and adrenocorticotropin release: mediation by endogenous corticotropin-releasing factor.

Recent reports indicate that the main effect of systemically administered angiotensin II (AII) on ACTH release is probably due to some central nervous system mechanism. The present studies were designed to investigate whether the central action of AII on ACTH release is directly mediated through CRF. In order to test the participation of endogenous CRF in the AII-induced ACTH release in vivo, intact and pharmacologically blocked (pretreated with chlorpromazine-morphine-nembutal) female rats were injected iv with AII (8 nmol/100 g BW). Plasma levels of ACTH as well as CRF content in the median eminence (ME) and medial basal hypothalamus (MBH) were evaluated before and 1, 2.5, and 5 min after treatment. These responses were compared with the effect of 1 min ether exposure on hypothalamic CRF content and plasma ACTH levels in unanesthetized animals. AII injection and ether exposure increased plasma ACTH levels several-fold at both 2.5 and 5 min post treatment in intact rats. Conversely, AII failed to induce any significant increase in plasma ACTH levels in centrally blocked rats at any interval studied. On the other hand, AII injection and ether inhalation acted in similar fashion on CRF content in ME, inducing fast depletion at 1 min post treatment, recovering to control values at 2.5 min after injection, and finally, accumulating peptide at 5 min post treatment. In addition, CRF content in the MBH decreased significantly at 5 min, under both experimental conditions; AII had no effect on hypothalamic CRF content in centrally blocked rats. In vitro experiments using whole MBH (containing ME) fragments incubated with either neural peptides or high K+ solutions indicate that AII possesses a CRF releasing effect at concentrations of 10(-6) M or more. Conversely, other hypothalamic peptides, such as LHRH, TRH, and somatostatin did not induce significant release of CRF at any of the concentrations assayed (10(-7) to 10(-5) M). On the other hand, high K+ solutions released CRF in a concentration-related manner (15-60 mM). These studies suggest that the central effect of AII stimulation on ACTH release in vivo could be, at least in part, through the release of hypothalamic CRF into the portal circulation.

Adrenocorticotropic Hormone↗
PubMed1985

Cerebral blood flow in minor cerebral contusion.

Seventeen patients with minor cerebral contusion were selected from a series of patients with head injuries of various severity, who had undergone repeat evaluations of the regional cerebral blood flow. The mean global flow (expressed as mean global initial slope index) on early examination was found to be significantly lower, compared with that recorded in healthy volunteers. A tendency towards the recovery of higher flow values was apparent in repeat evaluations that were performed several weeks after the injury. Interhemispheric asymmetries of flow were a common occurrence, with lower perfusion and reduced attenuation values on computed tomography scans being, however, in good agreement only in approximately half of the cases.

Adolescent↗
PubMed1984

Effects of doxefazepam on normal sleep. An EEG and neuropsychological study.

The effects on sleep of a putative hypnotic, benzodiazepine (doxefazepam), were studied in 7 healthy volunteers. Subjects were administered placebo or the active compound at 10-, 20-, and 40-mg oral dose prior to 13 consecutive nights during which they slept in the EEG laboratory. Full-night EEG recordings were obtained, and the hypnogram was determined. The subjective characteristics of sleep (quality, dreams, etc.) were defined by self-administered rating scales; neuropsychological and quantitative waking EEG measurements were performed before drug/placebo administration and in the morning following the final awakening, in order to identify possible signs of 'hangover'. Volunteers thereafter slept at home for 15 nights, self-administering 10 mg doxefazepam each night, and returned to the laboratory for 2 additional full-night sleep recordings. The drug plasma concentration was monitored during the study. Doxefazepam (10 mg) reduced the number of intermediate awakenings and the shifts between distinct sleep phases; single 20- or 40-mg doses or a 2-week administration of 10 mg doxefazepam increased significantly the total sleep duration and the percent duration of the phase 2 and the synchronized sleep and decreased the percent duration of phase 1 and of the intermediate awakenings. Volunteers reported an improvement in the subjective 'quality' of sleep, while evident signs of 'hangover' were not observed. The compound appeared to be of potential use as a sleep regulator.

Adult↗
PubMed1983

Correlates of adaptation to the sleep laboratory. Behavior, sleep organization, quantitative EEG.

The present study aims at establishing to what extent adaptation phenomena should be taken into consideration for the definition of an independent baseline in sleep research. To this purpose we have studied: (1) a standard battery of neuropsychological test evaluating performance, subjective assessments of moods and sleep quality; (2) classical sleep parameters; (3) data derived from quantitative analysis of sleep EEG. 19 young male volunteers have been recorded for consecutive nights; 7 of them underwent the recordings for 3, 8 for 6 and 4 for 10 nights. Results can be summarized as follows: (A) both interindividual and intraindividual variability show a progressively decreasing trend toward homogeneity for most of the explored parameters; (B) steady state is reached in different times for different groups of parameters; (C) an adequate group homogeneity was achieved from the 5th night onwards. Implications of these data in sleep studies, namely in sleep active drug research are discussed.

Adaptation, Psychological↗
PubMed1983

Effects of a single oral dose of phenobarbital on prolactin, growth hormone and luteinizing hormone in normal women.

The effects of a single oral dose of phenobarbital (PB) on the 24 h secretion of prolactin, growth hormone and luteinizing hormone have been evaluated in normal women. An EEG record was taken and barbiturate levels assayed in serum. A statistically significant decrease of growth hormone 24 h mean levels was observed and growth hormone and prolactin values during sleep were diminished. No changes in luteinizing hormone concentrations were observed. After PB the EEG showed no important alterations in sleep pattern, but on the power analysis an increase above 16 Hz absolute power was detected during the waking period.

Administration, Oral↗
PubMed1982

[Statistical study on the medical management of patients with epilepsy in a district of Reggio Calabria].

The epilepsy service provided by 143 doctors in the district of Vibo Valentia (Calabria) which has a population of 180,000 was studied by a team of specially trained medical students. The answers to a questionnaire given in personal interviews were statistically processed and revealed: a) a 3-4% incidence of epilepsy corresponding closely to the national average (Almost all doctors questioned had epileptic patients). b) that only 3% of the doctors tested drug concentration in the blood, while 33% relied on regular EEG checks. c) that Depakin (valproic acid) was the drug most often used, followed by Metinal-Idontoine (phenytoin + barbiturate), Dintoine (phenytoin) and Gardenal (phenobarbital). Almost all doctors were in favour of refresher courses to improve the service to epileptic patients.

Epilepsy↗
PubMed1982

Regional cerebral blood flow: normal values in healthy volunteers obtained by a 32 probes xenon 133 inhalation system.

Regional cerebral blood flow (CBF) was measured in 15 healthy young volunteers in psycho-sensorial rest by the 32 probes Xe133 inhalation system. The mean hemispheric values are in good agreement with those reported in literature and obtained with a limited number of probes. The regional values of the flow in the gray matter are higher in the basal-temporal and frontal regions. This regional pattern is not evident for the other considered parameters (flow in the white matter, mean flow, "weight" of the gray matter).

Adult↗
PubMed1982

Effects of acute intravenous administration of met-enkephalin in the rabbit: a computer analysis.

Intravenous administration of doses of Met-enkephalin ranging from 33.3 to 5000 micrograms/kg was followed by modifications in the EEG pattern in the rabbit. The changes were a prevalence of strongly synchronized EEG patterns, lasting about 90 min, in the absence of any behavioural sign of drowsiness. A transient fall in arterial blood pressure, lasting 15 sec, was observed immediately following the injection. Quantification of the EEG effects showed a remarkable increase of EEG total power. Such an increase is statistically significant. It was less marked in the posterior leads and appeared to be dose-related as regards its intensity, duration, and latency from injection. Qualitatively such a spectral profile matches the one typical of physiological drowsiness. As regards EEG effects, no tolerance to the peptide developed if the administration was repeated after 90 min. The specific antagonist of opiates both prevented and reversed the hypersynchronization of the tracing. These findings demonstrate that Met-enkephalin crosses the blood-brain barrier in an amount adequate to producing changes in the functional organization of the brain, resulting in EEG patterns corresponding to functional depression.

Animals↗