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Biomedical subjects

R Menendez

Publications and source records attributed to R Menendez.

At least 19 recordsLinked to original sources
PubMed2001

Cost-efficacy analysis of fluticasone propionate versus zafirlukast in patients with persistent asthma.

OBJECTIVE: To compare the relative value of an inhaled corticosteroid, fluticasone propionate 88 microg twice daily, versus an oral leukotriene receptor antagonist, zafirlukast 20 mg twice daily, in patients with persistent asthma currently receiving short acting beta2-agonists alone. STUDY DESIGN: A cost-efficacy analysis using resource utilisation and clinical data obtained prospectively from a multicentre, randomised, double-blind, double-dummy, placebo-controlled 12-week clinical trial conducted in the US. PERSPECTIVE: Third-party payor. PATIENTS AND METHODS: A total of 451 corticosteroid-naive patients with persistent asthma were treated with either fluticasone propionate 88 microg twice daily or zafirlukast 20 mg twice daily. All patients were given salbutamol (albuterol) to be used as rescue medication. Data were examined using intent-to-treat analysis. RESULTS: Mean daily per person cost-efficacy ratios using improvement in forced expiratory volume in 1 second (FEV1) [> or = 12% increase from baseline] were $US 3.47 for fluticasone propionate compared with $US 7.81 for zafirlukast (1999 values). The mean daily per person cost-efficacy ratios for symptom-free days obtained were $US 5.51 for fluticasone propionate compared with $US 14.98 for zafirlukast. These cost-efficacy ratios remained in favour of fluticasone propionate after a robust sensitivity analysis. CONCLUSIONS: Treatment with fluticasone propionate 88 kg twice daily was the most cost effective treatment compared with zafirlukast 20 mg twice daily in this 12-week clinical trial. This analysis supports the use of fluticasone propionate 88 microg twice daily as first-line treatment in patients with persistent asthma previously treated with short-acting beta2-agonist alone.

Adult↗
PubMed1999

Oxidative stabilization of C/C tow pregs studied by light microscopy

Tow pregs obtained from polyacrylonitrile-based carbon fibres and a commercial binder coal-tar pitch were stabilized by oxidation at 548, 588 and 623 K for periods ranging between 1 and 15 h. The microstructural changes involved in the stabilization of tow pregs on the carbonized laminates were studied by light microscopy. Under the conditions studied, the oxidative stabilization of tow pregs produced a significant increase in carbon yield. At the same time, the development of porosity on carbonization was avoided and the size of the optical texture was reduced. However, the extreme oxidation of pitch components at the edges of the carbonized laminate adversely affected pitch binding capability and the sinterizability of the laminates.

Journal Article↗
PubMed1999

Microstructure and properties of pitch-based carbon composites

Pitches prepared in the laboratory by thermal treatment and air-blowing of a commercial coal-tar pitch were used as matrix precursors of carbon composites using granular petroleum coke, foundry coke, amorphous graphite and anthracite. Pitches were characterized by standard procedures (elemental analysis, softening point, solubility tests and carbon yield) and light microscopy (mesophase content). Pitch pyrolysis behaviour was monitored by thermogravimetric analysis and from the optical texture of cokes. Pitch wettability to the different carbons, at different temperatures, was also studied. Experimental conditions selected for the preparation of composites were based on pitch composition and properties. The main microstructural features of composites were determined by light microscopy and scanning electron microscopy. Composite properties were described in terms of their density, porosity and compressive strength, and related to composite microstructure and the characteristics of the precursors. Thermal treatment and air-blowing of pitch improved carbon composite structure and properties. The lowest porosities and best mechanical properties were observed in those composites obtained with the thermally treated pitches combined with foundry coke and anthracite.

Journal Article↗
PubMed1998

Failure of zafirlukast to prevent ibuprofen-induced anaphylaxis.

BACKGROUND: Anaphylaxis to nonsteroidal anti-inflammatory drugs is thought to depend on cycloxygenase inhibition coupled to upregulation of 5-lipoxygenase-dependent pathways. The introduction of leukotriene-receptor antagonists afforded the opportunity to test this hypothesis. These agents provide at least partial protection against aspirin-induced anaphylaxis during controlled challenges but we did not know whether the level of protection was high enough to block symptoms from ingestion of a full dose of aspirin. METHODS: We report a patient with moderately severe asthma who experienced an episode of anaphylaxis following ingestion of 400 mg of ibuprofen while under therapy with 20 mg of zafirlukast given twice a day. RESULTS: No further episodes of anaphylaxis have been noted following institution of complete avoidance to all nonsteroidal anti-inflammatory drugs. CONCLUSIONS: Patients who are sensitive to cycloxygenase inhibitors should practice complete avoidance of these drugs even while under therapy with leukotriene modifiers.

Adolescent↗
PubMed1996

Effect of policosanol on the hepatic cholesterol biosynthesis of normocholesterolemic rats.

We have suggested previously, measuring 14C-acetate incorporation into free cholesterol, that oral administration of policosanol inhibits hepatic cholesterol biosynthesis in rats. Nevertheless, since acetate has limitations to study cholesterol synthesis in vivo, we now investigate rates of incorporation of labeled water into hepatic sterol after policosanol treatment. Absolute rates of incorporation of 3H-water in sterols were depressed by policosanol by about 20%, giving a more accurate degree of cholesterol biosynthesis inhibition in this species. Since policosanol did not inhibit labeled mevalonate incorporation into cholesterol in rat liver, we also studied the effect of policosanol on hydroxy-methylglutaryl-coenzyme A (HMG-CoA) reductase. Reductase activity assayed in microsomes treated with policosanol remained unchanged, suggesting that cholesterol synthesis is not inhibited by a direct action of policosanol on this enzyme.

Animals↗
PubMed1995

Efficacy of once daily extended-release theophylline in decreasing the use of inhaled beta 2-agonists in stable, mild-to-moderate asthma patients.

BACKGROUND/OBJECTIVE: The purpose of this study was to determine whether the addition of extended-release theophylline to the daily treatment regimen of inhaled beta 2-agonist users would result in decreased use of beta 2-agonist while maintaining similar efficacy for treatment of asthma. METHODS: This was a single-blind, multicenter (six sites) study. Sixty-one patients with a history of mild-to-moderate asthma treated with inhaled beta 2-agonist were randomized to treatment with Theo-24 (anhydrous extended-release capsules) plus inhaled beta 2-agonist or placebo plus beta 2-agonist. Patients kept daily symptom diaries, measured peak flow rates, recorded puffs of inhaled beta 2-agonist, and adverse events during a 4-week treatment period. RESULTS: Fifty-five patients were included in the efficacy analysis. The primary efficacy variable in this study was the mean number of puffs (adjusted for baseline differences) of beta 2-agonist inhaled per day. In this study, the addition of theophylline to the daily regimen of inhaled beta 2-agonist for 4 weeks significantly reduced the total daily dose of inhaled beta 2-agonist at weeks 3 and 4 of treatment compared with placebo. The differences were significant at the P < .05 level. For patients in the theophylline group, the number of puffs decreased from an unadjusted mean of 9.81 at baseline to an adjusted mean of 6.78 after 4 weeks of treatment compared with 9.91 at baseline and 8.17 for the placebo group. There were no unexpected or serious adverse events. CONCLUSIONS: In this study, the addition of once daily, extended-release theophylline to the daily regimen of inhaled beta 2-agonist for 4 weeks significantly reduced the total daily dose of inhaled beta 2-agonist at weeks 3 and 4 of treatment compared with placebo, while maintaining acceptable asthma symptom scores.

Administration, Inhalation↗
PubMed1994

Prognostic factors in childhood asthma: a logistic regression analysis.

Thirty-two factors related to childhood asthma were studied in 200 asthmatic children. Remission of asthma was defined as a period of at least 2 years free of asthma while receiving no treatment. Univariate analysis showed significant associations between persistence of asthma and perennial symptoms with an odds ratio (OR) of 2.5 (95% confidence intervals 1.2 to 5.5); sensitization to house dust mites OR 3.5 (1.2 to 9.6); sensitization to molds, OR 7.9 (2.9 to 21.6); sensitization to pollen, OR 4.8 (1.4 to 16.3); and sensitization to milk protein, OR 5.4 (1.8 to 15.9). There was a positive association of remission of asthma with good treatment compliance, OR 12.1 (1.6 to 91.6). A stepwise logistic regression analysis selected the variables: perennial symptoms (S: 0 = no, 1 = yes), length of follow-up time (T: number of months), treatment compliance (C: 0 = poor, 1 = good), sensitization to fungi (F: 0 to 4), and sensitization to milk protein (M: 0 to 4). The analysis yielded the following formula for calculation of probability of asthma remission P(R): [formula: see text] where S indicates perennial symptoms; T, follow-up time in months; C, compliance; F, allergy to fungi; and M, allergy to milk.

Adolescent↗
PubMed1994

Policosanol inhibits cholesterol biosynthesis and enhances low density lipoprotein processing in cultured human fibroblasts.

Policosanol is a mixture of aliphatic primary alcohols isolated and purified from sugar cane wax, that induces cholesterol-lowering effects in experimental models and human beings. When human lung fibroblasts were incubated with policosanol for 48 hours prior to the experiment, a dose dependent inhibition of 14C-acetate incorporation into total cholesterol was observed, whereas labeled mevalonate incorporation was not inhibited. Even when cholesterol synthesis was not strongly inhibited, low density lipoprotein (LDL) processing was markedly enhanced. Thus, LDL binding, internalization and degradation were significantly increased after policosanol treatment. In addition, despite the fact that'cholesterol generation was not inhibited at the lowest dose of policosanol assayed, LDL processing was significantly increased. The current data indicate that policosanol inhibits cholesterol synthesis at the earliest steps of the cholesterol biosynthetic pathway. On the other hand, this study suggests that the increase in LDL processing may be partially explained by the inhibition of cholesterol biosynthesis, even though an sterol-independent mechanism might be responsible for the enhancement of LDL-receptor activity.

Anticholesteremic Agents↗
PubMed1992

Effect of fat and fat-free mass deposition during pregnancy on birth weight.

OBJECTIVES: The purposes of our study were to describe the patterns and location of fat and fat-free mass deposition during pregnancy and to evaluate their effects on fetal growth. STUDY DESIGN: Our study is a prospective follow-up of 105 healthy pregnant women who were delivered of term infants. Body composition was evaluated eight times during gestation with anthropometric measures and bioimpedance techniques. Body fat and fat-free mass were calculated with equations specifically developed for this population. RESULTS: Total weight gain was 10.0 +/- 3.5 kg; net weight gain was 3.7 +/- 0.31 kg; birth weight was 3211 +/- 467 gm (values are mean +/- SEM). In these women fat was deposited mostly in the thigh and subscapular region for a total of 6.23 +/- 0.19 kg at term. The period of pregnancy of the largest maternal fat deposition per week is between the twentieth and thirtieth weeks. After adjusting by prepregnancy weight, birth weight is associated with maternal changes in thigh skin folds and fat gain before the thirtieth week of gestation. Infants born to mothers with low fat gain before the thirtieth week were 204 gm lighter than infants born to mothers with fat gain > or = 25th percentile of this population. CONCLUSION: Maternal nutritional status at the beginning of gestation and the rate of fat gain early in pregnancy are the two nutritional indicators most strongly associated with fetal growth in this population.

Adipose Tissue↗
PubMed1989

Effect of chest wall oscillation on mucus clearance: comparison of two vibrators.

This study was designed to investigate the effect of an experimental low-energy chest wall oscillator and of a commercial chest percussor on central airway mucociliary clearance. Five normal dogs were anesthetized, intubated, and placed supine in a trough to which the oscillator or percussor was mounted. Tracheal mucus velocity (TMV) was measured by radiopaque particle or charcoal spot movement. The commercial percussor (a fixed sinusoidal device) used at its minimum frequency of 40 Hz, produced a mean (+/- SE) maximum expiratory flow rate of 0.25 +/- 0.04 L/sec at the airway opening, and had no measurable effect on TMV. The experimental oscillator, when operated at a level sufficient to generate flows of 2-3 L/sec, and with an unbiased 13-Hz sine wave (estimated energy, 150 W), increased mean TMV to 204 +/- 13% of control (P less than 0.003); the percent increase was independent of baseline TMV. We conclude that moderate oscillatory power applied to the chest wall can enhance mucus clearance in central airways, but that currently available commercial percussors may not meet the mechanical requirements for this effect.

Animals↗
PubMed1988

Double-blind evaluation of nebulized cromolyn, terbutaline, and the combination for childhood asthma.

To evaluate whether the potency of a long-acting selective beta 2-agonist negates the need for cromolyn, 27 children, aged 6 to 12 years, with mild to moderate asthma requiring long-term medication, were assessed for the therapeutic effects of cromolyn and/or terbutaline by jet nebulizer. Patients received either cromolyn, 20 mg, terbutaline, 0.1 mg/kg up to 4 mg, or the combination, three times daily. The study design was double-blind, crossover with each patient receiving the three treatment regimens in randomized order for a period of 8 weeks each. Daily diary mean scores generally demonstrated best symptom control with cromolyn or the combination than with terbutaline alone. Cough was significantly less with cromolyn than with terbutaline (p less than 0.05). Morning peak flow measures were higher with combination therapy than with terbutaline (p less than 0.05). Evening peak flow measures were higher with the combination and cromolyn alone than with terbutaline alone (p less than 0.01). Methacholine challenge demonstrated less bronchial hyperreactivity with the combination or cromolyn alone than with terbutaline alone (p less than 0.02). The effectiveness of the nebulizer regimen for children with chronic asthma is better when cromolyn is used alone or in combination with terbutaline than when the beta-agonist is used alone.

Asthma↗
PubMed1988

Perinatal data reliability in a large teaching obstetric unit.

In this inter-rater agreement study of antenatal and neonatal variables collected in a large teaching obstetric unit, information routinely collected by hospital staff was compared with that collected by a specially trained physician and a social worker. Agreement between the two sources of data was evaluated using kappa statistics and intraclass correlation coefficients. Excellent agreement was observed for some variables such as maternal and newborn anthropometric measures, and previous birthweight, but there was poor agreement for others such as indicators of physical activity, work during pregnancy and blood pressure measures. Some of the limitations are due to problems in phrasing questions, patients' recall, interviewer bias and abstracting data. We recommend that epidemiological studies should always include a reliability component, proper standardization of personnel and instruments and include, when published, validity data and examples of questions used.

Adult↗
PubMed1988

Improved lactose digestion during pregnancy: a case of physiologic adaptation?

Loss of intestinal lactase activity among adults could theoretically limit milk consumption and hence dietary availability of calcium during pregnancy. The present study sought to define, using breath hydrogen (H2) production as an index of incomplete carbohydrate absorption, the prevalence during pregnancy of lactose maldigestion of 360 mL of milk (18 g of lactose), and to determine whether lactose digestion improved as pregnancy advanced. The prevalence of lactose maldigestion among 114 pregnant women tested before the 15th week of gestation was 54%. By term, 44% of those originally classified as maldigesters had become digesters. There was a significant reduction in the four-hour sum of the changes in breath H2 concentration from the period before 15 weeks (116.6 +/- 9.6 ppm) to the time after 36 weeks (54.4 +/- 7.3 ppm; P less than .01). This apparent adaptive improvement in intestinal handling of milk lactose during gestation has implications for calcium intake and absorption.

Acidosis, Respiratory↗