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Biomedical subjects

J A Escobar

Publications and source records attributed to J A Escobar.

14 recordsLinked to original sources
PubMed2001

Smoking-related attitudes, characteristics, and opinions in a group of young men with asthma.

UNLABELLED: The objective of this study was to examine the attitudes, characteristics, and opinions about smoking of a group of young asthmatic men. POPULATION AND METHODS: An anonymous, personal questionnaire was administered to 611 young male volunteers who had been diagnosed with asthma (according to the National Heart, Lung, and Blood Institute/World Health Organization Global Initiative for Asthma, 1995) in the respiratory disease and allergy clinics of the Burgos Military Hospital (Spain). This questionnaire contained items related to personal information, asthma characteristics, opinions about smoking, and information related to smoking habits. RESULTS: Six hundred patients with asthma completed the questionnaire. All were men, mean age 20.16 +/- 3.03 years; 189 (31.5%) were smokers and 16 (2.5%) were ex-smokers. Mean age at onset of regular smoking was 16.46 +/- 2 years. Sixty-five percent (65.07%) smoked fewer than 10 cigarettes per day. Most of the smoking asthmatics had mild asthma (58.9%). Eighty-eight percent (88.3%) had moderate dependence. Many of the smoking asthmatics were contemplating stopping smoking (54%), and 59% had tried before to stop. Concern about health was the main reason given for stopping smoking. Asthmatics who smoked had a higher percentage of smokers among family members, friends, and colleagues than nonsmoking asthmatics. Attitudes toward smoking were more permissive among smoking asthmatics. Only 36.64% of the total had received information about tobacco previously. In the sample group, 7% claimed that they did not smoke but their carbon monoxide concentration in exhaled air was 10 ppm or higher. CONCLUSIONS: There were no differences in the onset of the smoking habit between asthmatic and nonasthmatic young people. A large percentage of the smoking asthmatics were considering smoking cessation, motivated mainly by their asthma condition. The group as a whole had little previous information about tobacco.

Adult↗
PubMed1996

Sod and catalase inactivation by singlet oxygen and peroxyl radicals.

Both superoxide dismutase and catalase are readily deactivated by singlet oxygen and by the radicals produced in the pyrolysis of 2,2'-azo-bis-(2-amidinpropano) under aerobic conditions. The rate constant for the loss of enzymatic activity induced by singlet oxygen are 3.9 x 10(7) and 2.5 x 10(7) M-1 sec-1 for SOD and catalase, respectively. The similarity between these values implies that in systems where SOD and catalase are exposed to similar singlet oxygen concentrations, it can be expected a parallel inactivation of both enzymes. The inactivation of both enzymes by the radicals produced by 2,2'-azo-bis-(2-amidinopropane) pyrolysis under aerobic conditions follows a first-order kinetics at low enzyme concentrations and a zero-order kinetics at higher concentrations. Although at low enzymatic concentrations the rate of inactivation of both enzymes is similar, this results from a compensation of effects because there are wide differences in the reactivity of both enzymes towards peroxyalkyl radicals. Catalase is considerably more reactive, but a large number of protein/radical reactive interactions are needed to inactivate one enzyme. On the other hand, the reactivity of SOD is smaller, but the average enzyme activity decreases by nearly 20% in each SOD/radical reactive interaction.

Animals↗
PubMed1993

The peroxidative metabolism of tenoxicam produces excited species.

The peroxidative metabolism of the nonsteroid anti-inflammatory oxicams generates metabolites of the type expected from a dioxetane intermediate. Therefore, electronically excited metabolites may be expected. Consistent with this possibility, both direct and sensitized light emission are observed when tenoxicam is exposed to horseradish peroxidase or when added to leukocytes, where it undergoes a myeloperoxidase-catalyzed aerobic oxidation. The similarity between peroxidative metabolism with concomitant oxygen uptake and photodegradation brought about by singlet oxygen addition to the substrate is pointed out. As a whole, the results strengthen the view that electronically excited species should also be considered when analyzing the effect(s) of xenobiotics.

Animals↗
PubMed1992

Horseradish peroxidase-catalyzed aerobic oxidation and peroxidation of indole-3-acetic acid. I. Optical spectra.

A study of the indole-3-acetate reaction with horse-radish peroxidase, in the absence or presence of hydrogen peroxide, has been performed, employing rapid scan and conventional spectrophotometry. We present here the first clear spectral evidence, obtained on the millisecond time scale, indicating that at pH 5.0 and for high [enzyme/substrate] ratios peroxidase compound III is formed. Most, if not all, of the compound III is formed by oxygenation of the ferrous peroxidase. There is an inhibitory effect of superoxide dismutase and histidine on compound III formation which indicates the involvement of the active oxygen species superoxide and singlet oxygen. It is concluded that the oxidation of indole-3-acetate by horseradish peroxidase at pH 5.0 proceeds through compound III formation to the catalytically inactive forms P-670 and P-630. A reaction path in which the enzyme is directly reduced by indole-3-acetate might be involved as an initiation step. Rapid scan spectral data, which indicate differences in the formation and decay of enzyme intermediate compounds at pH 7.0, in comparison with those observed at pH 5.0, are also presented. At pH 7.0 compound II is a key intermediate in oxidation--peroxidation of substrate. Mechanisms of reactions consistent with the experimental data are proposed and discussed.

Aerobiosis↗
PubMed1992

Horseradish peroxidase-catalyzed aerobic oxidation of indole-3-acetic acid. II. Oxygen uptake and chemiexcitation.

Light emission from the horseradish peroxidase-catalyzed aerobic or anaerobic oxidation of indole-3-acetic acid has been investigated under opposite extreme conditions of enzyme/substrate ratio. The O2-dependent chemiluminescent processes represent a minor part of the total oxygen consumption. Superoxide is involved in chemiexcitation as is evident from the observed inhibitory effect of superoxide dismutase. At high enzyme/substrate ratio, only a part of the emission is dependent on superoxide ion; at low ratio the dependence is extensive. At high ratio, some of the emission is independent of superoxide and O2. The identical quenching effects of D- and L-tryptophan are consistent with the formation of the quenching species only in bulk solution. The similarity of the emission spectra under extreme conditions indicates that the same main emitters are formed. This is also supported by the effect of quenchers. Possibly some of the emitters originate in the oxidative cleavage of the 2,3-double bond of the indole ring.

Aerobiosis↗
PubMed1992

Free radicals and excited species in the metabolism of indole-3-acetic acid and its ethyl ester by horseradish peroxidase and by neutrophils.

The peroxidative metabolization of indole-3-acetic acid, a biologically important process, has been followed by EPR spectroscopy with the aim of obtaining information on the mechanism of generation of electronically excited species. The skatole-3-methylene radical detected during oxidation by horseradish peroxidase, does not appear to be involved in a major oxygen consuming process or in the generation of singlet oxygen. The chemiluminescence spectrum exhibits several maxima, which are also observed when the ethyl ester of indole-3-acetic acid is metabolized by horseradish peroxidase or by myeloperoxidase in neutrophils. When the ester is metabolically activated in either of these systems, the EPR spectrum indicates a tertiary carbon-centered radical. This radical centered on the carbon in the 3-position participates in a chemiexcitation/emissive route. Within the cell, this emissive process is responsible for a large part of the oxygen consumed. Some of the emitters originate in the cleavage of the 2,3 double bond. The ester, which is capable of penetrating into the cells, also emits with other myeloperoxidase-containing cells. This compound may have useful applications as an intracellular chemiluminescent probe for the presence of myeloperoxidase.

Animals↗
PubMed1992

Effect of emulsion concentration on biodistribution of perflubron in tumor-bearing mice.

Perflubron (perfluoroocytlbromide, PFOB) emulsion concentrations of 100%, 90%, or 60% w/v were administered to mice with and without 3 types of murine malignant tumor implants, and the distribution in blood, tumor, lung, liver and spleen were studied 48 hours after a dose of 10 or 3 g/Kg of PFOB. The most important changes were seen in the blood where the PFOB concentration [PFOB] was decreased in tumor bearing mice (TBM). Blood [PFOB] was also decreased in TBM and normal mice (NM) that received the 60% emulsion. Liver [PFOB] was increased in TBM. Lung [PFOB] was directly proportional to the emulsion concentration with the 10g/Kg dose. No major differences were seen in the biodistribution between the 100% and 90% emulsions using 10g/Kg, in spite of differences in composition and manufacturing history.

Animals↗
PubMed1992

Cyclooxygenase inhibition with ibuprofen: effect on biodistribution of perflubron emulsions in mice with mammary tumor.

The biodistribution of Perflubron (perfluorocytylbromide, PFOB) was studied by infusing 10 or 3 g/Kg doses of 90% and 100% w/v emulsions into Balb C mice with and without malignant mammary tumor implants. PFOB concentrations were measured in blood, liver, spleen, lung and tumor, and X-rays were taken 48 hours after infusion. Ibuprofen (IBU) was given intraperitoneally 10 mg/Kg dialy for 3 days to study the effects of cyclooxygenase blockade. The results showed that the blood [PFOB] in tumor-bearing mice (TBM) was only 3.6% of that measured in normal mice (NM), and the liver [PFOB] was increased by 59%. The lung [PFOB] increase with IBU therapy in NM was highly significant. IBU therapy resulted in a 98% and 468% increase in blood [PFOB] in normal and TBM, respectively. Smaller but statistically significant changes occurred in blood [PFOB] with saline and sham injections. Tumor [PFOB] was lower by 17% (P = .028) in mice treated with IBU. Smaller decreases were seen with saline and sham injections but did not achieve statistical significance. In conclusion, the presence of this malignant tumor resulted in changes that might influence the usefulness of PFOB as a contrast agent and as an adjuvant for radiation and chemotherapy. This study shows that cyclooxygenase inhibition significantly modified the pharmacodynamics of PFOB emulsions in blood, tumor and lung. The changes seen in the saline placebo and sham category were attributed to stress from procedures.

Animals↗
PubMed1990

Effects induced in neutrophils by a precursor of triplet acetone.

The addition of a precursor of the enol form of isobutanal to neutrophils results in formation of triplet acetone, as attested to by emission from appropriate acceptors and cell damage (Nascimento et al., 1986 Biochim. Biophys. Acta 888, 337-342). The present study confirms the formation of triplet acetone by detection of the direct emission (lambda max 430 nm) and differentiates between effects produced by triplet acetone and by the enol substrate itself. Thus, triplet acetone: (1) enhances the release of ribonucleic acid; (2) promotes lipid peroxidation (N3(-)-inhibitable formation of thiobarbituric acid reactive products and concomitant light emission peaking at 480-500 nm); (3) increases myeloperoxidase activity, presumable as a result of damage and consequent increased exposure of the enzyme. On the other hand, the enol greatly enhances the release of protein(s) into the medium. These results confirm the utility of the neutrophil as a model system for the study of chemiexcitation processes induced at the cellular level. They also provide the first demonstration that an excited species formed at the cellular level may induce release of nucleic acids, thus reflecting the occurrence of deleterious processes in situ.

1-Propanol↗
PubMed1977

[Fibrinogen estimation. A simplified gravimetric method (author's transl)].

UNLABELLED: A simplified gravimetric method is proposed for fibrinogen estimation in plasma. Technic: 0.5 ml plasma (citrated) are diluted to up 5 ml with saline. A stick, 5 to 6 cm long, made of a glass capillary tube, or, aluminium foil, with ends bended as a hock, are weighted up to 0.001 g. Introduce one stick previously weighted in diluted plasma. Place two drops of thrombin (10 U/ml), and mix. In seconds, all fibrinogen is transformed in fibrin, deposited around the stick. Remove the stick with the fibrin, and press gently with the fingers, expelling the liquid in excess. Hang the stick with the fibrin, on the rim of a dry centrifuge tube. Centrifuge at 3.000 rpm for 10 minutes (dry centrifugation). Centrifugal forces acting on the fibrin clot expell all liquid particles. Fibrin consist of a very thin layer adhered on the stick. The weight difference (initial and final), represents the solid fibrin. CALCULATION: difference of weight added by 0.1 of the difference (anticoagulant dilution) x 200 to convert in dl. The method is highly reproductible, and takes about 20 minutes to be completed.

Fibrinogen↗
PubMed1976

Etiology of respiratory tract infections in children in Cali, Colombia.

One hundred eighty children hospitalized for acute respiratory disease were studied in Cali, Colombia. In the majority of patients, pneumonia was the reason for hospitalization and remained the final diagnosis. Fifty-one cases of pneumonia of indeterminate etiology comprised the largest single diagnostic category, followed by 38 cases of pneumonia associated with measles, and 22 cases assocaited with serologic evidence of infection with other viral agents or Mycoplasma pneumoniae. Etiologic diagnosis could be assigned with a reasonable degree of confidence in 116 of the 180 patients (64%). The laboratory procedure found most likely to provide the etiologic diagnosis in this series was paired sera specimens for demonstration of rise in antibody titer against the common viral respiratory pathogens. Those most frequently implicated serologically as etiologic agents in the cases studied were, in order of decreasing frequency, measles, influenza, parainfluenza, and adenoviruses.

Adolescent↗
PubMed1975

Pneumonia associated with measles.

Thirty-three children were hospitalized for pneumonia associated with measles. Eight did not have rash but had serologic evidence of measles infection and an otherwise compatible clinical picture. Lung puncture and tracheal aspirations were performed on 21 of the patients. Mortality was 15.2% (five patients) and was not associated with the use of these procedures.

Adolescent↗
PubMed1975

Mortality from tuberculous meningitis reduced by steroid therapy.

In this study of 99 tuberculous meningitis patients from Cali, Colombia, treatment with steroids (in conjunction with antituberculous drugs) was shown to be more effective in reducing mortality than treatment with antibacterial drugs alone. Results further suggest that low dosages of steroids (1 mg/kg of prednisone daily for r 30 days) are equally effective in treating the disease as high dosages (10 mg/kg of prednisone at the start of treatment, gradually reduced over a 30-day period). These results are band 4(-43 and -kk mg/100 ml) demonstrated cerebral release. Arterial blood hyperammonemia can be detoxified safely in the brain as long as the levels do not exceed approximately 300 mug/100 ml. Beyond that level lactic acidosis is observed, particularly in cerebral venous drainage. Arterial blood hyperammonemia was also related to the extent of alveolar hyperventilation. These findings are very similar to those seen in experimental hyperammonemia and support the concept that neurotoxicity in children with Reye's syndrome is at least partly due to impaired oxidative metabolism secondary to hyperammonemia.

Adolescent↗