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Biomedical subjects

R Muñoz

Publications and source records attributed to R Muñoz.

At least 19 recordsLinked to original sources
PubMed1992

Oxidation of hydroquinone by both cellular and extracellular grapevine peroxidase fractions.

The oxidation of hydroquinone by two peroxidase (EC 1.11.1.7) fractions obtained from the cells and spent medium of cell cultures of grapevine (Vitis vinifera cv Monastrell) has been studied, and their comparative efficacy (kcat/KM ratio) studied in both the H2O2-consuming and hydroquinone-consuming reactions. While the efficacy in the H2O2-consuming reaction is practically identical for both enzyme fractions, the cellular peroxidase has five-fold more efficacy in the hydroquinone-consuming reaction than the peroxidase located in the spent medium. Screening of cellular peroxidases capable of oxidizing hydroquinone on polyacrylamide gels, by means of a staining reaction based on the nucleophilic attack of 4-aminoantipyrine on p-benzoquinone in acidic media, reveals that all the cellular peroxidase isoenzymes are capable of oxidizing hydroquinone, probably yielding a quinone-diimine as a product of the staining reaction. Since isoperoxidases found in cellular fractions are also present in the spent medium, the values found for the different efficacies in the hydroquinone-consuming reaction must be considered as the results of the different proportions in which each peroxidase isoenzyme was found in the two fractions. The localization of a benzoquinone-generating system of high efficacy inside the plant cell, and probably located in vacuoles, is discussed with respect to the harmful role which the quinone/semiquinone pair might play in cell death, as part of the hypersensitive response expressed within the mechanism of plant disease resistance.

Ampyrone↗
PubMed1992

Genetics of resistance to third-generation cephalosporins in clinical isolates of Streptococcus pneumoniae.

Resistance to third-generation cephalosporins in a clinical isolate of Streptococcus pneumoniae was shown to be due to the production of altered forms of penicillin-binding proteins (PBPs) 2X and 1A. The cloned PBP2X gene from the resistant strain was able to transform a susceptible strain to an intermediate level of resistance. The resulting transformant could be transformed to the full level of resistance of the clinical isolate using the cloned PBP1A gene from the latter strain. Chromosomal DNA from the resistant strain (and from other resistant strains) could readily transform a susceptible strain to the full level of resistance to third-generation cephalosporins (greater than 250-fold for cefotaxime; greater than 100-fold for ceftriaxone) in a single step (transformation frequency of about 10(-5)). The resistant transformants obtained with chromosomal DNA were shown by gene fingerprinting to have gained both the PBP1A and PBP2X genes from the DNA donor.

Bacterial Proteins↗
PubMed1992

Hammett rho sigma correlation for the inhibition by indoles of coniferyl alcohol oxidation catalyzed by cell wall peroxidases.

The inhibitory effect of indole-3-acetic acid, and of its peroxidase-mediated degradation products of an indole nature, on the oxidation rate of coniferyl alcohol catalyzed by cell wall peroxidases has been studied. The results show that the inhibitory effect of indole-3-acetic acid and indole-3-carbinol may be explained, in part, by their properties as peroxidase substrates. However, I50 values for a series of indole compounds not regarded as peroxidase substrates show a good correlation with the electron-donating or electron-withdrawing nature of the 3-substituents, as judged by the linearity of the Hammett rho sigma plot. These results suggest that although the properties of indole compounds as peroxidase substrates may be responsible, in part, for their inhibitory effects on the peroxidase-mediated oxidation of coniferyl alcohol, the inhibitory effect appears to be mainly determined by the acidity of the imino group of the indole nucleus.

Catalysis↗
PubMed1992

Presence of single-chain ribosome-inactivating protein-like activities in several plant species.

The present screening work was devoted to the search for new ribosome-inactivating proteins (RIPs) in 21 plant species. Eight plants proved to be very active, inhibiting protein synthesis in eukaryotic in vitro systems (rat liver, Vicia sativa and wheat germ). They fulfil the major requirements for consideration as type 1 RIPs. Also, eight plants were found to contain haemagglutinating activity of human red cells but this was not related to the simultaneous presence of RIPs.

Animals↗
PubMed1992

[Mortality from Parkinson's disease in Spain (1980-1985). Distribution by age, sex and geographic areas].

An approximation of Parkinson's disease in Spain was carried out based on the data of mortality by this disease over the period 1980-1985. The annual number of deaths by Parkinson's disease as well as its distribution by sex, age groups and Spanish provinces was obtained from information published annually by the National Institute of Statistics in the Natural Movement of the Spanish Population. The global mortality rate during the period studied was of 2.14 per 100,000 inhabitants. The specific mortality rate by Parkinson's disease in males was slightly higher than that of females. A specific mortality rate was also observed by age groups being higher in the older age groups. From the point of geographical distribution, higher rates were observed in the northern provinces with respect to the south and in rural areas compared to provinces capitals. Following the analysis of the results obtained and upon comparing the findings published in other countries it was concluded that place of residence may be related to the development of Parkinson's disease. From these data new epidemiological studies are required oriented to the identification of the environmental factors which may play a role in the etiology of this entity.

Age Factors↗
PubMed1991

Effect of L-azetidine 2-carboxilic acid on the activity of the general amino-acid permease from Saccharomyces cerevisiae var. ellipsoideus.

Addition of the L-proline analogue L-azetidine 2-carboxylic acid to growing cultures of Saccharomyces cerevisiae var. ellipsoideus promoted fast deactivation of the general aminoacid permease, measured as L-valine uptake, without an immediate decrease in the growth rate. Cells preincubated with the analogue for 3 h were unable to restore either growth ability or general aminoacid permease activity in analogue-free medium. Eadie-Hofstee plots of L-valine uptake in the presence of the analogue are consistent with a strong reduction in the number of active molecules of the general amino-acid permease located in the plasma membrane. Inhibitory effects on protein synthesis were seen after preincubations of the yeast with the analogue for 3 h although a 30 min preincubation had no effect.

Amino Acid Transport Systems↗
PubMed1991

Changes in sensitivity of in vitro rat brain protein synthesis to the acute action of ethanol and isopropanol as a consequence of the long-term ingestion of isopropanol.

Long-term treatment of rats with isopropanol in the drinking water results in a change or process of adaptation occurring in in vitro brain protein synthesis which increases the resistance of the ribosomal machinery to the acute effect of either ethanol or isopropanol. Such an increase was observed both in the system coded by endogenous messenger and in the system coded by polyuridylic acid. In both translation systems, the adaptation seems to affect the ribosomal step of polypeptide chain elongation. The increase in resistance to the alkanols apparently did not affect the inhibitory action of puromycin, fusidic acid and cycloheximide on the ribosome.

Adaptation, Physiological↗
PubMed1991

Intercontinental spread of a multiresistant clone of serotype 23F Streptococcus pneumoniae.

Isolates of serotype 23F Streptococcus pneumoniae with high levels of resistance of penicillin have been commonly recovered in Spain for more than a decade. Recently penicillin-resistant serotype 23F S. pneumoniae strains were also isolated from children attending a day-care center in Cleveland. A number of Spanish and Cleveland isolates were compared by electrophoretic analysis of penicillin-binding protein (PBP) profiles and DNA restriction endonuclease cleavage profiles of the PBP 2X and 2B genes amplified with the polymerase chain reaction and by multilocus enzyme electrophoresis. All strains were identical by these criteria. The findings demonstrate that the Spanish and Cleveland isolates are clonally related and suggest that this antibiotic resistant clone of serotype 23F S. pneumoniae has spread intercontinentally from Spain to the United States.

Bacterial Proteins↗
PubMed1991

[The treatment of hyperkalemia with salbutamol].

For several years now, it has been known that the administering of adrenergic beta antagonists, especially of the beta-2 type, induce hypokalemia as a result of the entering of potassium into the skeletal muscle cells. This fall in kalemia occurs independently from the effect of insulin, aldosterone or kidney excretion, is mediated by the beta-2 receptors and require the intervention of cAMP joined at the cell membrane and the subsequent stimulation of the Na-K-ATPase which bring the potassium into the striated muscle cell. Among the most outstanding drugs with beta-2 effect is salbutamol, which maintains the hypokalemic effect whether administered intravenously or inhaled. It has been used in cases of hyperkalemia, in both children and adults. The initially used intravenous dosage (0.5 mg) caused several side-effects, especially rapid heart beat, seen more in children. It has been recently found that the use of doses as low as 4 micrograms/kg lower the kalemia to values averaging 1.4 to 1.6 mEq/L (mmol/L); in addition, using these dosages intravenously in an average of 20 minutes, no side-effects were seen, even when administered to newborns. For the above, we considered that salbutamol, in the suggested dosages, constitutes an efficient and secure therapeutic method for the initial treatment of severe hyperkalemic patients.

Albuterol↗
PubMed1991

Effect of long-term n-butanol ingestion on rat brain polypeptide synthesis directed by endogenous messengers.

Long-term ingestion of sublethal n-butanol doses by rats led to a noteworthy increase in the resistance of in vitro brain ribosomal function to the acute inhibitory action of ethanol and isopropanol. Withdrawal of n-butanol did not change this adaptation process immediately. The step affected seems to be the elongation of polypeptide chains. The dependence of in vitro translation on incubation temperature was affected by the adaptation process, the translation system of chronic animals being less stimulatable than that of control animals at low temperature.

1-Propanol↗
PubMed1990

Oxidation of coniferyl alcohol by cell wall peroxidases at the expense of indole-3-acetic acid and O2. A model for the lignification of plant cell walls in the absence of H2O2.

The oxidation of coniferyl alcohol (CA), a lignin precursor, by cell wall peroxidases may take place at the expense of indole-3-acetic acid (IAA) and O2, and in the absence of H2O2. The peroxidase-catalyzed oxidation of CA shows an optimum at an IAA concentration of 0.33 mM, while higher IAA concentrations are inhibitory. The observation that the oxidation of CA by cell wall peroxidase at the expense of IAA and O2 is inhibited by genistein, a putative endogenous inhibitor of lignification in lupin hypocotyls, supports the view that the H2O2-generating system coexists with cell wall peroxidase activities involved in lignification, and that it takes place at the expense of IAA and O2.

Cell Wall↗
PubMed1990

Zymographic screening of plant peroxidase isoenzymes oxidizing 4-hydroxystilbenes.

A zymographic assay is described for the detection of peroxidase isoenzymes oxidizing 4-hydroxystilbene following isoelectric focusing. The assay is based on coupling intermediate products of the oxidation of 4-hydroxystilbene with 4-aminoantipyrine, with resultant formation of dye complexes. Control experiments in the absence of 4-hydroxystilbene and hydrogen peroxide demonstrate the peroxidative nature of the 4-hydroxystilbene-dependent dye reaction.

Ampyrone↗
PubMed1990

Identification of atypical strains of Streptococcus pneumoniae by a specific DNA probe.

A specific DNA probe containing a 0.65 Kb fragment coding for the aminoterminal region of the major pneumococcal autolysin (amidase) was constructed, deleting the region involved in the specific recognition of cell wall choline residues. The high specificity of this probe was demonstrated in tests with Streptococcus pneumoniae related species including Streptococcus oralis, which contains choline in its cell wall. The probe was used to characterize pneumococcal isolates showing atypical responses in conventional identification tests. The hybridization obtained with 27 atypical pneumococci and 11 of 17 isolates presumptively identified as viridans streptococci confirmed that the probe is suitable for diagnostic use.

DNA Probes↗
PubMed1990

A spectrophotometric assay for quantitative analysis of the oxidation of 4-hydroxystilbene by peroxidase-H2O2 systems.

A new and sensitive spectrophotometric assay has been developed to study and to characterize kinetically the oxidation of 4-hydroxystilbene (an analogue of the putative viniferin precursor, trans-resveratrol, directly involved in the resistance mechanism of the grapevine to fungal diseases) by peroxidase-H2O2 systems. The technique measures the overall increase in absorbance at 248 nm in the reaction media, probably due to the formation of a phenoxy radical of the 4-hydroxystilbene (4-HS). This technique was developed by using the purified isoenzyme C of horseradish peroxidase and all the validity criteria (sensitivity and reproducibility) were checked. The results show that it is especially suitable for low activity measurements. It was finally applied to the determination of the oxidation rate of 4-HS by peroxidases isolated from the media of suspension-cultured grapevine cells, at two different developmental stages.

Fruit↗
PubMed1990

Thirty years' experience with biliary tract reconstruction by hepaticoenterostomy and transhepatic T tube.

This study shows long-term results of biliary tract reconstruction in cases of high stenosis of the hepatic duct. Hepaticoenterostomy was performed with transhepatic insertion of a T tube following an original technique. A portion of the horizontal limb of the T tube is placed in the left hepatic duct, the other portion in the duodenum or jejunum, and the vertical limb extends into the right hepatic duct and the right lobe of the liver and is brought out through the abdominal wall. This tube is irrigated daily and removed after 12 months in order to keep the stent in place for a sufficient duration to prevent stenosis. This technique was used in 45 patients who underwent operations from 1954 to 1984. There were 6 postoperative deaths. Of the 39 patients discharged from the hospital, 37 were followed up. Excellent results were obtained in 30 patients who remained asymptomatic after observation from 1 to 14 years. In three patients, results were good, but there were occasional episodes of fever that subsided with antibiotics; one of these patients was observed for 17 years. Results were poor in four patients who developed a recurrent stenosis; three of them underwent reoperations, with satisfactory results. Long-term observation has shown that the described surgical procedure is useful in cases of high stenosis of the hepatic duct, because a stent can be left in place for a year and usually will prevent stenosis at the biliary intestinal anastomosis.

Adult↗
PubMed1990

Differential D-glucose requirements of the general amino-acid permease and protein synthesis in Saccharomyces cerevisiae var. ellipsoideus.

The dependence of the general aminoacid permease and protein synthesis on the availability of D-glucose as energy source was studied. Stimulation by the sugar was immediate once added to the cell suspensions and seems to be mediated by energy derived directly from glycolysis. The general aminoacid permease was saturated linearly with D-glucose whereas protein synthesis was saturated sigmoidealy requiring much higher concentration of the sugar than the general aminoacid permease.

Amino Acid Transport Systems↗