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Biomedical subjects

E Linares

Publications and source records attributed to E Linares.

At least 19 recordsLinked to original sources
PubMed2003

Kinetics and mechanism of the reaction of a nitroxide radical (tempol) with a phenolic antioxidant.

In the absence of redox-active transition metal ions, the removal of Tempol by Trolox occurs by a simple bimolecular reaction that, most probably, involves a hydrogen transfer from phenol to nitroxide. The specific rate constant of the process is small (0.1 M(-1) s(-1)). Metals can catalyze the process, as evidenced by the decrease in rate observed in the presence of diethylenetriaminepentaacetic acid (DTPA). Furthermore, addition of Fe(II) (20 microM ferrous sulfate and 40 microM EDTA) produces a noticeable increase in the rate of Tempol consumption.

Antioxidants↗
PubMed2003

Short- and medium-term clinical efficacy of three endoscopic therapies for achalasia: a single-blinded prospective study.

OBJECTIVE: to compare the efficacy of three endoscopic therapies for achalasia and to identify predictors of response. DESIGN: prospective, single-blinded study at short and medium term. MATERIAL AND METHODS: 22 patients (9M/13 F; mean age: 47.45 +/- 21.01 years) with confirmed clinical and manometric achalasia were randomised in three groups: intrasphincteric injections of botulinum toxin (group 1: 10 patients ), injections of 1% polidocanol (group 2:6 patients), and a combined therapy with both of them (group 3: 6 patients). Clinical response was evaluated by a score (0-5) of tested symptoms (dysphagia, regurgitation and chest pain) at 1 and 24 weeks post-treatment. RESULTS: at 24 weeks post-treatment group 2 had the best complete response (CR) rate (33.33%), whereas CR in both the botulinum toxin and combined therapy groups was 10 and 0%, respectively. Groups 1 and 2 got an overall improvement in clinical score at 1 (p= 0.02) and 24 weeks (p= 0.04). Five patients (50%) in group 1, two patients (33.33%) in group 2, and three patients (50%) in group 3 needed other therapies (dilation or surgery) because of treatment failure. Separately, neither age nor sex, time from diagnosis or type of therapy could distinguish responders from non-responders in these three groups. However, absence of response within the first week, and an initial clinical score above 7 were predictive factors of poor response at six months. CONCLUSIONS: short- and medium-term clinical response to these endoscopic therapies was limited. The absence of response at seven days and a severe initial clinical score were predictive factors of poor medium-term response.

Adult↗
PubMed2001

Role of peroxynitrite in macrophage microbicidal mechanisms in vivo revealed by protein nitration and hydroxylation.

The cytotoxins produced by phagocytic cells lacking peroxidases such as macrophages remain elusive. To elucidate macrophage microbicidal mechanisms in vivo, we compared the lesion tissue responses of resistant (C57Bl/6) and susceptible (BALB/c) mice to Leishmania amazonensis infection. This comparison demonstrated that parasite control relied on lesion macrophage activation with inducible nitric oxide synthase expression (iNOS), nitric oxide synthesis, and extensive nitration of parasites inside macrophage phagolysosomes at an early infection stage. Nitration and iNOS expression were monitored by confocal microscopy; nitric oxide synthesis was monitored by EPR. The main macrophage nitrating agent was shown to be peroxynitrite derived because parasite nitration occurred in the virtual absence of polymorphonuclear cells (monitored as peroxidase activity) and was accompanied by protein hydroxylation (monitored as 3-hydroxytyrosine levels). In vitro studies confirmed that peroxynitrite is cytotoxic to parasites whereas nitric oxide is cytostatic. The results indicate that peroxynitrite is likely to be produced close to the parasites and most of it reacts with carbon dioxide to produce carbonate radical anion and nitrogen dioxide whose concerted action leads to parasite nitration. In parallel, some peroxynitrite decomposition to the hydroxyl radical should occur due to the detection of hydroxylated proteins in the healing tissues. Consequently, peroxynitrite and derived radicals are likely to be important macrophage-derived cytotoxins.

Animals↗
PubMed2001

Antibacterial activity of Rhizophora mangle bark.

The aqueous extract of Rhizophora mangle bark, also formulated to ensure physical and chemical stability, was found to inhibit the growth of seven bacteria frequent in infected wounds.

Anti-Bacterial Agents↗
PubMed2001

New modified eremophilanes from the roots of Psacalium radulifolium.

The investigation of the chemical constituents from the roots of Psacalium radulifolium, a member of the matarique complex of medicinal plants, which includes several members of the Asteraceae, resulted in the isolation of four new modified eremophilanes: radulifolin A (4), epi-radulifolin A (5), radulifolin B (6), and radulifolin C (7), together with the known natural substances cacalol, cacalone, epi-cacalone, O-methyl-1,2-dehydrocacalol, adenostin A, decompostin, and neoadenostylone. Antimicrobial evaluation of the extracts and the isolated compounds indicated that cacalol was the major active compound.

Asteraceae↗
PubMed2001

Antiinflammatory constituents from Heterotheca inuloides.

Three new compounds, cadalen-15-oic acid (1), 3,7-dihydroxy-3(4H)-isocadalen-4-one (2), and dicadalenol (3), were isolated from the aerial parts of Heterotheca inuloides (Mexican arnica), together with the known compounds 7-hydroxycadalene (4), 7-hydroxy-4alphaH-3,4-dihydrocadalene (5), 1alpha-hydroxy-1(4H)-isocadalen-4-one (6), 1alpha-hydroxy-4alphaH-1,2,3,4-tetrahydrocadalen-15-oic acid (7), 7-(3,3-dimethylallyloxy)coumarin, caryolan-1,9beta-diol, and quercetin. The structures of the new compounds were elucidated by spectroscopic methods. The antiinflammatory activities of the extracts and the isolated compounds were evaluated by determining the inhibition of TPA-induced mouse ear edema. The natural products 3, caryolan-1,9beta-diol, and quercetin were the most active substances tested and displayed dose-dependent activities.

Animals↗
PubMed2001

Food services for the homeless in Spain: Caritas Programme for the Homeless.

Homelessness includes a wide range of people, from those living on the street (strictly homeless) to people living temporarily with relatives or friends because they have lost their home. Programmes for the homeless should design strategies aimed at encouraging insertion processes, thus considering the different dimensions involved. Within this framework Caritas delivers an array of assistance services for the homeless facing the stages of insertion. In Spain there are 315 centres offering meals for 20000 people, most of them along with other services such as reception, residential premises or day-care centres. Caritas is responsible for 42% of them. Overall, it is easier to get a lunch than any other meal during the day, followed by dinner, while it is difficult to get a breakfast. Social dining rooms are valuable places for a first contact (first stage of the insertion process) and even to start the second stage (personal recovery).

Adolescent↗
PubMed2000

New phenylethanoids from Buddleja cordata subsp. cordata.

Bioassay-guided fractionation of a crude extract of the stem bark of Buddleja cordata subsp. cordata with significant antimycobacterial activity led to the isolation of a mixture composed by ten new long-chain esters of 2[4'-hydroxyphenyl]-ethanol (1-10), along with the lichen metabolites methyl beta-orcinolcarboxylate (11) and beta-orcinolcarboxylate (12). Extensive HPLC allowed the separation of the major components of the mixture, which were characterized by spectral means as 2[4'-hydroxyphenyl]-ethyl stearate (3), 2[4'-hydroxyphenyl]-ethyl behenate (6), and 2[4'-hydroxyphenyl]-ethyl lignocerate (8). The minor esters were identified as 2[4'-hydroxyphenyl]-ethyl palmitate (1), 2[4'-hydroxyphenyl]-ethyl heptadecanoate (2), 2[4'-hydroxyphenyl]-ethyl nonadecanoate (4), 2[4'-hydroxyphenyl]-ethyl arachidate (5), 2[4'-hydroxyphenyl]-ethyl tricosanoate (7), 2[4'-hydroxyphenyl]-ethyl pentacosanoate (9), and 2[4'-hydroxyphenyl]-ethyl hexacosanoate (10) by GC-MS analysis of the methyl esters derivatives of the fatty acids obtained by alkaline hydrolysis of the mixture. Compound 8 exhibited moderate antibacterial activity against Mycobacterium tuberculosis (MIC = 64 micrograms/ml).

Glucosides↗
PubMed2000

Leishmania amazonensis infection does not inhibit systemic nitric oxide levels elicited by lipopolysaccharide in vivo.

Leishmaniasis is a parasitic disease that leads to chronic inflammation. Macrophages, depending on their activation state, are either hosts or killers of the parasites. Downregulation of nitric oxide (NO) synthesis by the parasite infecting the macrophages has been proposed to be an important evading mechanism based on in vitro studies. We confirmed inhibition of NO release by macrophages infected with Leishmania amazonensis in vitro. To examine the role of the parasite in regulating NO production in vivo, we monitored systemic NO levels elicited by challenging naive and L. amazonensis-infected BALB/c mice with lipopolysaccharide (LPS). Animals were challenged after 1, 2, 6, and 9 wk of infection. NO production was monitored by electron paramagnetic resonance spectroscopy as the levels of hemoglobin nitrosyl complexes (HbNO) present in the animal's blood. No significant differences in HbNO levels were observed between LPS-treated naive and inoculated mice at any time during infection. To control for increased macrophage numbers in infected mice, naive mice were injected with a macrophage cell line before LPS challenge; this treatment did not increase produced NO levels. The results argue against a major role for the parasite in downregulating NO production in vivo.

Animals↗
PubMed1999

Gemfibrozil for the secondary prevention of coronary heart disease in men with low levels of high-density lipoprotein cholesterol. Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial Study Group.

BACKGROUND: Although it is generally accepted that lowering elevated serum levels of low-density lipoprotein (LDL) cholesterol in patients with coronary heart disease is beneficial, there are few data to guide decisions about therapy for patients whose primary lipid abnormality is a low level of high-density lipoprotein (HDL) cholesterol. METHODS: We conducted a double-blind trial comparing gemfibrozil (1200 mg per day) with placebo in 2531 men with coronary heart disease, an HDL cholesterol level of 40 mg per deciliter (1.0 mmol per liter) or less, and an LDL cholesterol level of 140 mg per deciliter (3.6 mmol per liter) or less. The primary study outcome was nonfatal myocardial infarction or death from coronary causes. RESULTS: The median follow-up was 5.1 years. At one year, the mean HDL cholesterol level was 6 percent higher, the mean triglyceride level was 31 percent lower, and the mean total cholesterol level was 4 percent lower in the gemfibrozil group than in the placebo group. LDL cholesterol levels did not differ significantly between the groups. A primary event occurred in 275 of the 1267 patients assigned to placebo (21.7 percent) and in 219 of the 1264 patients assigned to gemfibrozil (17.3 percent). The overall reduction in the risk of an event was 4.4 percentage points, and the reduction in relative risk was 22 percent (95 percent confidence interval, 7 to 35 percent; P=0.006). We observed a 24 percent reduction in the combined outcome of death from coronary heart disease, nonfatal myocardial infarction, and stroke (P< 0.001). There were no significant differences in the rates of coronary revascularization, hospitalization for unstable angina, death from any cause, and cancer. CONCLUSIONS: Gemfibrozil therapy resulted in a significant reduction in the risk of major cardiovascular events in patients with coronary disease whose primary lipid abnormality was a low HDL cholesterol level. The findings suggest that the rate of coronary events is reduced by raising HDL cholesterol levels and lowering levels of triglycerides without lowering LDL cholesterol levels.

Aged↗
PubMed1998

Influence of the shape of phospholipid vesicles on the measurement of their size by photon correlation spectroscopy.

The influence of shape transformation of large unilamellar vesicles (LUV) on their size measurement by photon correlation spectroscopy (PCS) has been investigated. The experimental size of vesicles after hyperosmotic contractions of increasing intensities have been compared to the theoretical volume decrease determined by applying Boyle Van't Hoff's law. The main observation is that PCS size measurement gives overestimated values when LUV have been subjected to a volume decrease of more than 20% of their initial volume. The PCS size overestimation is related to the influence of the shape transformation of the vesicles on their diffusion coefficient (D) as shown by modelling the evolution of D of a sphere which is transformed into an ellipsoid by internal volume reduction under constant area.

Absorptiometry, Photon↗
PubMed1998

In vivo formation of electron paramagnetic resonance-detectable nitric oxide and of nitrotyrosine is not impaired during murine leishmaniasis.

Recent studies have provided evidence for a dual role of nitric oxide (NO) during murine leishmaniasis. To explore this problem, we monitored the formation of NO and its derived oxidants during the course of Leishmania amazonensis infection in tissues of susceptible (BALB/c) and relatively resistant (C57BL/6) mice. NO production was detected directly by low-temperature electron paramagnetic resonance spectra of animal tissues. Both mouse strains presented detectable levels of hemoglobin nitrosyl (HbNO) complexes and of heme nitrosyl and iron-dithiol-dinitrosyl complexes in the blood and footpad lesions, respectively. Estimation of the nitrosyl complex levels demonstrated that most of the NO is synthesized in the footpad lesions. In agreement, immunohistochemical analysis of the lesions demonstrated the presence of nitrotyrosine in proteins of macrophage vacuoles and parasites. Since macrophages lack myeloperoxidase, peroxynitrite is likely to be the nitrating NO metabolite produced during the infection. The levels of HbNO complexes in the blood reflected changes occurring during the infection such as those in parasite burden and lesion size. The maximum levels of HbNO complexes detected in the blood of susceptible mice were higher than those of C57BL/6 mice but occurred at late stages of infection and were accompanied by the presence of bacteria in the cutaneous lesions. The results indicate that the local production of NO is an important mechanism for the elimination of parasites if it occurs before the parasite burden becomes too high. From then on, elevated production of NO and derived oxidants aggravates the inflammatory process with the occurrence of a hypoxic environment that may favor secondary infections.

Animals↗
PubMed1997

Smooth muscle relaxing flavonoids and terpenoids from Conyza filaginoides.

Activity-guided fractionation of the smooth muscle relaxing, chloroform-methanol (1:1) extract of Conyza filaginoides (D.C.) Hieron (Asteraceae) led to the isolation of three flavonoids (quercetin 3-glucoside, rutin, and pinostrobin), one sterol (alpha-spinasterol), a sesquiterpenoid (beta-caryophyllene 4,5-alpha-oxide), and two triterpenoids (erythrodiol and 3-beta-tridecanoyloxy-28-hydroxyolean-12-ene). 3-beta-Tridecanoyloxy-28-hydroxy-olean-12-ene is a new naturally occurring terpenoid. All the isolated compounds induced a concentration-dependent inhibition of the spontaneous contractions of rat ileum. The spasmolytic activity exhibited by the extract and active principles tends to support the traditional use of C filaginoides as an antispasmodic agent.

Animals↗
PubMed1996

Formation of nitrosyl hemoglobin and nitrotyrosine during murine leishmaniasis.

Peroxynitrite, the potent oxidant formed by the fast reaction between nitric oxide and superoxide anion, has been suggested to be the reactive intermediate responsible for some of the pathologies associated with an over-production of nitric oxide. In this report, we demonstrate that both nitric oxide and peroxynitrite are formed during infection of the susceptible mouse strain, BALB/c, with Leishmania amazonensis. Nitric oxide was detected as the nitrosyl hemoglobin complex by EPR analysis of blood drawn from mice at 35, 64 and 148 days of infection. The levels of nitrosyl hemoglobin complex increased with disease evolution, which in the murine model used is characterized by skin lesions, ulceration and visceralization of the parasites. Peroxynitrite formation was inferred from immunoreaction of homogenates obtained from footpad lesions in the late stages of the infection with anti-nitrotyrosine antibody; homogenates from parasites drawn from the lesions were also immunoreactive, although to a lesser extent. Analysis of protein homogenates by gel electrophoresis and western blots suggests that peroxynitrite may degrade proteins in vivo, in addition to nitrating them. The results demonstrate that peroxynitrite is formed during murine leishmaniasis and may play a role in the aggravation of the disease.

Animals↗
PubMed1996

Possible roles of nitric oxide and peroxynitrite in murine leishmaniasis.

Activated macrophages simultaneously synthesize nitric oxide and superoxide anion which can react with each other producing peroxynitrite. Consequently, it has been difficult to assess the precise contribution of each of the formed reactive oxygen- and nitrogen-derived species to the microbicidal activities of macrophages, particularly in vivo. To explore this problem, we are examining the formation and potential roles of nitrogen-derived intermediates in Leishmania amazonensis murine infection. Thus far, our results have demonstrated that peroxynitrite is a potent leishmanicidal agent in vitro and that both nitric oxide and peroxynitrite are formed during infection of the susceptible BALB/c mouse strain. Nitric oxide was detected as the nitrosyl-hemoglobin complex by electron paramagnetic resonance analysis of blood drawn from mice at different times of infection, and it was shown to increase with the evolution of the disease. These results will be discussed in the context of the dual physiological role of nitric oxide either as a signaling molecule or as a deleterious agent.

Animals↗
PubMed1995

Vasoactive effects of aqueous extracts from five Mexican medicinal plants on isolated rat aorta.

The present investigation describes the effects of aqueous extracts from Chiranthodendron pentadactylon flowers, Galphimia glauca leaves and flowers, Ipomoea stans roots, Juglans regia leaves and Taxodium mucronatum aerial parts on isolated rat thoracic aorta precontracted by noradrenaline (NA). In all cases, the aqueous extracts (0.5-12 mg/ml) significantly inhibited, in a concentration-dependent manner, the maximal contractile response induced by NA in rat aorta. The most active extract was that of G. glauca flowers. These findings indicate that the active principle(s) present in the crude extracts can exert a vasorelaxant effect.

Animals↗
PubMed1988

Effect of intravenous isosorbide dinitrate versus nitroglycerin on elevated pulmonary arterial wedge pressure during acute myocardial infarction.

To compare the acute and sustained effect of intravenous isosorbide dinitrate to intravenous nitroglycerin in patients with acute myocardial infarction and elevated pulmonary artery wedge pressure, 111 patients were randomized and studied within 96 hours of admission to the coronary care unit. All patients had a pulmonary artery wedge pressure greater than or equal to 10 mm Hg and received either isosorbide dinitrate (74 patients) or nitroglycerin (37 patients) for 24 to 48 hours. Blood pressure, heart rate, pulmonary artery wedge pressure, cardiac output, medication dose in micrograms per minute and retitration episodes were compared at baseline and at 6, 12, 18 and 24 hours. Both drugs significantly (p less than 0.05) lowered pulmonary artery wedge pressure and blood pressure and increased cardiac output. Isosorbide dinitrate required fewer retitration episodes and less increases in dosage than nitroglycerin at 24 hours. In the patient with acute myocardial infarction complicated by high pulmonary artery wedge pressure who requires intravenous nitrates for 24 hours, isosorbide dinitrate may offer the benefit of a more stable hemodynamic effect.

Aged↗