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Biomedical subjects

R Rodríguez

Publications and source records attributed to R Rodríguez.

At least 271 records · Page 15Linked to original sources
PubMed1982

Peroxidase and IAA oxidase in germinating seeds of Cicer arietinum L.

Peroxidase and indole acetic oxidase (IA oxidase) activities in seeds of Cicer arietinum L. were studied at 72 h of germination. Both activities behaved differently in relation to optimum pH, stability against temperature and time of storage of 4 degrees C. Disc electrophoresis on polyacrilamide gel showed the existence of five anionic and three cationic isoenzymes with peroxidase activity by using benzidine as substrate; three of the anionic isoenzymes and one cationic isoenzyme possessed a simultaneous IAA oxidase activity as well.

Chromatography, Gel↗
PubMed1982

Pigeon egg white lysozyme. Purification, structural and enzymic characterization.

Lysozyme from pigeon egg white has been purified by ion exchange chromatography and gel filtration. The overall yield of the purification procedure is 65%. The specific activity of the enzyme is 15 000 units/mg. The influence of pH and ionic strength on the lytic activity of the protein, as well as its thermal stability, have been studied. The molecular weight, secondary structure estimation, amino acid composition, NH2- and COOH-terminal sequence of the protein are also reported. The pigeon enzyme has been classified as a chicken type lysozyme (lysozyme c) according to the obtained results.

Amino Acids↗
PubMed1981

Pharmacological characterization of opiate physical dependence in the isolated ileum of the guinea-pig.

1 Physical dependence was produced in ilea from naive guinea-pigs by exposure of the tissue to different opiates for logarithmically-spaced periods of time (20-320 min). The responsiveness of the tissue to naloxone, as indicated by a strong contracture of the ileum, was enhanced in contrast to that found in intestines not exposed to opiates. 2 The dose-response curves to naloxone obtained in tissues individually exposed to different opiates showed that their relative potency in increasing sensitivity to naloxone was as follows: levorphan greater than morphine greater than Met-enkephalin greater than nalorphine greater than pentazocine. 3 The naloxone-induced response was dose-dependent and was directly related to the opiate concentration and length of exposure. 4 Dextrorphan the inactive isomer of levorphan, did not increase the responsiveness of the tissues to the narcotic antagonist, indicating that the phenomenon is stereospecific. 5 The naloxone-induced contraction in ilea exposed for 320 min to morphine (1 x 10(-6)M) was not prevented or suppressed by the administration of a large dose of morphine (1 x 10(-5)M) before or immediately after the naloxone challenge. 6 The evidence presented here shows that a phenomenon resembling in vivo opiate physical dependence can be acutely produced in vitro with pharmacological characteristics similar to other naloxone-induced abstinence effects.

Animals↗
PubMed1981

CT findings in subacute perforation of the gallbladder: report on 5 cases.

Perforation of the gallbladder is a serious complication of acute and subacute cholecystitis which is rarely recognized before operation, either by clinical or radiological methods. Five cases of walled-off perforation of the gallbladder have been diagnosed by computed tomographic (CT) studies, within a period of less than one year. The studies were routinely made in the supine projection, with or without an intravenous injection of contrast medium. Scanning time was 4.7 seconds. The patients did not receive any pre-medication. CT demonstrated direct signs of the perforations: calculi outside the gallbladder; the ruptured segment of the wall. Indirect signs were also readily detected: localized abscesses, occasionally multiple or situated distant from the gallbladder; gallstones; thickening of the wall of the gallbladder. CT may have an important role in preoperative diagnosis of complicated acute cholecystitis and in the surgical management of patients with this condition, if ultrasound examination fails to establish the diagnosis or cannot be done for technical reasons.

Aged↗
PubMed1980

Toward a behavioral toxicology of paint thinner.

Few experiments have been carried out to evaluate the effects of toxic industrial substances such as the solvents on operant behavior. Laboratory rats trained in a mult FR DRL reinforcement schedule showed a differential impairment in performance when exposed to various doses of paint thinner in the experimental chamber, the FR performance being more sensitive to the solvent than DRL responding. Another study of rats working under a FI schedule suggested that the effects of paint thinner are rate-dependent, a finding which suggests a similarity of thinner with the amphetamines in regard to the behavioral effect. Two other experiments addressed to the behavioral effects of chronic exposure to the solvent showed a decrease in locomotor activity and an impaired acquisition of a complex temporal discrimination task in laboratory rats exposed to paint thinner during four, eight of sixteen weeks. These findings are suggestive of brain dysfunction associated with thinner inhalation but further experiments are needed for more definite conclusions.

Amphetamine↗
PubMed1979

Effects of solvents on schedule-controlled behavior.

Operant conditioning techniques have been shown to be sensitive to the acute effects of industrial solvents. In the first experiment, five rats trained in a multiple schedule with a fixed-ratio (FR) 10 component and a differential reinforcement of low rates (DRL) 20-sec component, with a time out 60-sec between reinforcement periods, were exposed to 0.25, 0.50, 1 and 2 ml of toluene in the experimental chamber. The effects were dose-dependent, with an increase in rate in the DRL component and a decrease in FR responding. A second experiment assessing the effects of chronic exposure to thinner in the acquisition of a timing behavior in rats showed an impairment in DRL learning after 4, 8 or 16 weeks of exposure to the solvent: however, rats having a resting period did not differ from control animals. Whereas this finding suggests a reversible impairment in the acquisition of a complex behavior, further research is needed to achieve more definitive conclusions.

Administration, Inhalation↗