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Biomedical subjects

R Farré

Publications and source records attributed to R Farré.

At least 55 records · Page 3Linked to original sources
PubMed2000

Evaluation of a method for assessing respiratory mechanics during noninvasive ventilation.

Noninvasive assessment of respiratory resistance (Rrs) and elastance (Ers), which is not easy with conventional methods, could be useful in the optimization of pressure support ventilation. The aim of this study was to evaluate a simple noninvasive method (Delta-inst) of measuring Rrs during nasal pressure support ventilation. Rrs and Ers (Delta-inst) were computed from inspiratory mask pressure, flow and volume recorded during pressure support ventilation. The Delta-inst method was compared with the forced oscillation technique (FOT) in seven patients with chronic obstructive pulmonary disease (COPD) and in eight healthy subjects without and with added resistance (3.1 cmH2O x s x L(-1)). Rrs measured by Delta-inst (5.2+/-1.7, 7.2+/-0.5 and 6.9+/-1.2 cmH2O x s x L(-1)) and by FOT (5.0+/-0.7, 7.6+/-0.9 and 8.1+/-2.7 cmH2O x s x L(-1)) in healthy subjects without and with added resistance and COPD, respectively, were not significantly different (p>0.05). Rrs measured by both techniques showed a significant coefficient of linear correlation (r=0.70 s) (p<0.01). In the COPD patients, the variability of Delta-inst Rrs (30%) was greater than that of FOT Rrs (21%). The agreement between Ers obtained by Delta-inst and by FOT was less than that found for Rrs. Delta-inst is a noninvasive and simple method for reliably assessing resistance. Therefore, it is useful for monitoring airway obstruction and is potentially helpful in adapting the settings for pressure support ventilation in accordance with patient mechanics.

Adult↗
PubMed2000

Pharmacological and molecular characterization of muscular cholecystokinin receptors in the human lower oesophageal sphincter.

In vitro cholecystokinin (CCK) contracts the human lower oesophageal sphincter by stimulating muscular receptors. The aim of this study was to characterize the muscular CCK receptor subtypes in the human lower oesophageal sphincter. Twenty-five circular strips from six patients were studied. RNA was extracted, reverse transcribed, and cDNAs were amplified with primers for human CCK-A and B receptors. The potency of the contraction induced by CCK-8, desulphated CCK-8, and gastrin-I, and the effect of the CCK-A (loxiglumide and SR 27897) and the CCK-B (YM022 and L-365 260) specific receptor antagonists were compared. Both CCK-A and CCK-B receptor mRNAs were found in functional lower oesophageal sphincter strips. The potency of the CCK-8 concentration-dependent contraction was two and three orders of magnitude higher than that of desulphated CCK-8 and gastrin-I, respectively. The CCK-8-induced contraction was blocked by the CCK-A receptor antagonists loxiglumide (IC50 11 micromol L-1) and SR 27897 (IC50 74 nmol L-1) but not by CCK-B receptor antagonists (1 micromol L-1). Our data suggest that, although the human lower oesophageal sphincter expresses both CCK-A and CCK-B receptors, the contractile effect of CCK-8 on the circular muscle is mainly due to the activation of CCK-A receptors.

Adult↗
PubMed2000

Amino acid profile of milk-based infant formulas.

The protein content and amino acid profile of three milk-based infant formulas, two of which were powdered (adapted and follow-on) and the third liquid, were determined to check their compliance with the EU directive and to evaluate whether or not they fulfil an infant's nutritional needs. To obtain the amino acid profile proteins were subjected to acid hydrolysis, prior to which the sulfur-containing amino acids were oxidized with performic acid. The amino acids were derivatized with phenylisothiocyanate (PITC) and then determined by ion-pair reverse phase high performance liquid chromatography (HPLC) In the case of tryptophan a basic hydrolysis was applied and there was no need of derivatization. The protein contents of the analysed formulas were in the ranges established by the EU directive for these products and the amino acid contents were in the ranges reported by other authors for these types of formulas. In all cases the tryptophan content determined the value of the chemical score, which was always lower than 80% of the reference protein but in the ranges reported by other authors. The analysed adapted infant formula provides amino acids in amounts higher than the established nutritional requirements.

Amino Acids↗
PubMed2000

A simplified method for monitoring respiratory impedance during continuous positive airway pressure.

The forced oscillation technique is useful in detecting changes in upper airway obstruction in patients with sleep apnoea undergoing continuous positive airway pressure (CPAP) ventilation. The aim of this study was to implement and evaluate a method for estimating respiratory impedance (Zrs) from the pressure and flow recorded at the inlet of the CPAP tubing. The method is based on correcting impedance measured at the inlet of the CPAP tubing (Zi) for the effect of the tubing and the exhalation port. The method was evaluated in mechanical analogues and in a healthy subject. Sinusoidal oscillation of 5, 10 and 20 Hz were superimposed on CPAP (5-15 cmH2O). At 5 Hz, the changes in airflow obstruction were substantially underestimated by Zi. Furthermore, Zi exhibited a negative dependence on Zrs at 20 Hz. The assessment of Zrs was greatly improved after correcting Zi for the effects of the CPAP tubing and the exhalation port. Zrs was well estimated at low frequencies, reaching very high values during total occlusion (>60 cmH2O x s x L(-1) at 5-10 Hz). These results indicate that changes in airflow obstruction can be detected using the forced oscillation technique from pressure and flow recorded on the continuous positive airway pressure device. This facilitates the clinical application of the forced oscillation technique for monitoring upper airway patency during sleep.

Airway Resistance↗
PubMed2000

Selenium, copper, and zinc indices of nutritional status: influence of sex and season on reference values.

The objective was to estimate the possible influence of season or season and sex on the selenium, glutathione peroxidase (GSH-Px), copper, zinc, and superoxide dismutase (SOD) values in plasma with a view to establishing reference values. For this purpose, 55 healthy volunteers (36 women and 19 men) were selected and their whole-blood samples were collected four times a year at the beginning of each season. In the population as a whole, no statistically significant seasonal differences were detected in copper, selenium, and GSH-Px values in plasma, whereas zinc and SOD values in plasma depended on the season. In general, the variability was higher among the women. In view of the differences detected according to sex and/or season in the parameters studied, we recommend taking samples from men and women and from different seasons to establish reference values.

Copper↗
PubMed2000

In vitro dialyzability of zinc from different salts used in the supplementation of infant formulas.

Seven zinc salts--acetate, chloride, lactate, sulfate, citrate, gluconate, and oxide--were added to milk--and soy-based infant formulas to estimate possible differences in zinc availability depending on the type of salt used. For this purpose, an in vitro method that estimates the dialyzability of the element (i.e., the fraction available for absorption) was applied. Zinc dialyzability is always higher in milk-based products than in soy products, even when the total zinc contents are higher in the latter. The salts can be classified according to the zinc dialyzability in the two types of formulas as follows: oxide > gluconate = chloride = lactate > citrate = acetate > sulfate. Therefore, according to the dialysis percentage, oxide and gluconate are the compounds of choice for zinc supplementation of infant formulas.

Animals↗
PubMed2000

A study of factors that may influence the determination of copper, iron, and zinc in human milk during sampling and in sample individuals.

The aim of this study was to establish the possible effects of the sampling protocol (between-breast, within-feed, and diurnal differences) and the mother's personal factors (age, parity, iron supplementation, smoking habits, and lactation period) on the copper, iron, and zinc contents in human milk. One hundred thirty-six human milk samples identified by their origin and sampling conditions were analyzed. The samples were obtained from the 2nd to 15th d postpartum from 62 women. The data on the individuals required for the study were available. Mineral determinations were analyzed by flame atomic absorption spectrometry following a standardized protocol. The results showed that iron contents were higher in hind-milk samples and at the nighttime feeding and depended on the breast from which the sample was taken. The copper and zinc concentrations showed no significant variations. There was no significant relationship among the mothers' age, parity, smoking habits, iron supplementation, and copper content. Milk from older women had lower zinc contents than that of younger women. Increased amounts of iron were found in multiparous women. Between colostrum and transitional milk, a sharp decrease in zinc content was observed, whereas copper and iron contents remained constant. All of these results make it clear that standardized sampling protocols are needed in order to obtain comparable values.

Adult↗
PubMed1999

Cadmium and lead in infant cereals--electrothermal-atomic absorption spectroscopic determination.

Because infant cereals are an important component of the infant diet from the fourth month of life onwards and therefore contribute to the dietetic intake of metals by infants, cadmium and lead were measured in samples of cereals commercially available in Spain. For this purpose an electrothermal atomic absorption (ET-AAS) method for determining cadmium and lead in these products was studied. The ET-AAS instrumental conditions and temperature/time furnace program were selected. The analytical parameters of the method (linearity, detection and quantification limits and precision) show its usefulness in measuring cadmium and lead in infant cereal products. The method was applied to eight different types of infant cereals from four different manufacturers, in all 29 different infant cereal products commercially available in Spain. The cadmium and lead contents of milk-free infant cereals range from 6.6 to 35.8 ng/g and from 36.1 to 305.6 ng/g, respectively, while the ranges corresponding to milk-added infant cereals are 2.9-40.0 ng/g for cadmium and 53.5-598.3 ng/g for lead. The cadmium and lead contents of cereal products of the same type from different manufacturers is responsible for the large confidence intervals and made it impossible to detect significant differences among the different products. Given the values found for lead and the correlation between chronic exposure to low lead doses and neuropsychological damage in early childhood, efforts should be made to reduce lead contamination.

Cadmium↗
PubMed1999

Selenium contents of human milk and infant formulas in Spain.

The selenium content of Spanish human milk samples and different milk-based and soy-based infant formulas has been estimated by using a flow injection hydride atomic absorption spectrometric method after microwave digestion of the organic matter. Mean values of 11.4 +/- 3.7 and 10.7 +/- 4.6 ng/ml for colostrum and transitional milk, 8.4 +/- 3.4 and 5.3 +/- 1.9 ng/ml for mature milk at 1 month and up to 2 months respectively, was obtained. These values are close to those reported by others authors in Europe, and lower than the ones from the US, Japan and Korea. Selenium contents of the analyzed infants' formulas ranged from 2.7 to 9.6 ng/ml and from 1.8 to 7.5 ng/ml for soy and milk-based infant formulas, respectively. The variability in selenium contents is large, although mean values are close to the ones given in other European countries. Selenium contents are not usually given on the product. The selenium intakes were estimated assuming that infants fed only human milk. The intakes ranged from 2.0 to 8.4 micrograms/day and from 3.4 to 12.9 micrograms/day for colostrum and transitional milk, respectively, and from 2.6 to 10.3 micrograms/day for mature milk at 1 month, and from 1.2 to 8.3 micrograms/day for milk up to 2 months. The analyzed infant formulas provide significantly less selenium than the 10 micrograms/day corresponding to the recommended daily allowance for infants from 0 to 6 months.

Animals↗
PubMed1999

Whole blood selenium content in pregnant women.

The selenium content in the blood of pregnant women in the Valencian Community, Spain was determined until the end of gestation in order to assess its evolution and detect possible differences in relation to the values corresponding to non-pregnant women of fertile age. A total of 158 blood samples were obtained from 137 pregnant women. Samples were classified as: (a) first; (b) second; and (c) third trimester. Selenium was determined by a flow injection hydride atomic absorption spectrometric method (Seronorm whole blood was used as a quality control check). The selenium values obtained for the three trimesters followed a Gaussian distribution. The intervals for mean found were: (a) 75.7-85.5 micrograms/l; (b) 72.6-81.4 micrograms/l; and (c) 69.9-77.5 micrograms/l. Although a tendency to decrease was observed, no statistical significant differences between the three trimesters of the gestational period were observed. When we compare the values obtained with the blood selenium content of women of fertile age in the Valencian community (87.8-98.8 micrograms/l) by using an ANOVA test, statistically significant differences are found between the selenium values of women of fertile age and those corresponding to pregnant women. The differences, however, are very small and can be partially explained by the level of hemodilution during pregnancy, however, reference values of blood selenium contents in pregnant women should be taken into account.

Adult↗
PubMed1999

Assessment of bronchial reactivity by forced oscillation admittance avoids the upper airway artefact.

The forced oscillation technique (FOT) allows easy assessment of bronchial reactivity. The use of a standard FOT generator (SG) results in changes in respiratory system resistance (delta Rrs,SG) which are affected by an artefact caused by the extrathoracic upper airway (EUA). The aim was to improve the FOT assessment of bronchial reactivity with the SG by computing the change in FOT admittance (delta Ars,SG), which is theoretically unaffected by this artefact. Delta Rrs,SG and delta Ars,SG after bronchial challenge in 17 children were compared with the values measured with a head generator (HG) FOT setup (delta Rrs,HG and delta Ars,HG, respectively), which were taken as a reference, since HG provides data virtually freed from the EUA artefact. At 10 Hz, the SG significantly underestimated the resistance change: delta Rrs,SG=1.77+/-0.62 versus delta Rrs,HG=6.09+/-1.23 hPa x L(-1) x s. Delta Rrs,SG and delta Rrs,HG did not show a significant correlation. By contrast, the amplitude of the change in admittance measured by SG was close to the one obtained with the reference HG: /delta Ars,SG/=29.5+/-4.6 versus /delta Ars,HG/=32.7+/-3.9 mL x hPa(-1) x s(-1). /Delta Ars,SG/ and /delta Ars,HG/ showed a significant correlation (r=0.65, p>0.01). Similar results were found up to 20 Hz. The extrathoracic upper airway artefact was minimized when computing the change in admittance with the standard generator. This forced oscillation technique index may improve the sensitivity in assessing bronchial reactivity with the standard generator setup, which is the most common and easiest to use method for routine lung function testing.

Airway Resistance↗
PubMed1999

Forced oscillation total respiratory resistance and spontaneous breathing lung resistance in COPD patients.

Forced-oscillation total respiratory resistance (Rrs) has been shown to underestimate spontaneous breathing lung resistance (RL,sb) in patients with airway obstruction, probably owing to upper airway shunting. The present study reinvestigates that relationship in seven severely obstructed chronic obstructive pulmonary disease patients using a technique that minimizes that artefact. Rrs at 8 and 16 Hz was computed for each successive forced oscillation cycle. Inspiratory and expiratory RL,sb were obtained by analysing transpulmonary pressure (Ptp) with a four-coefficient model, and compared to Rrs over the same periods. "Instantaneous" values of RL,sb were also obtained by computing the dynamic component of Ptp, and compared to simultaneous values of Rrs. In both respiratory phases, good agreement between Rrs and RL,sb was observed up to RL,sb values of approximately 15 hPa x s(-1) x L(-1) at 8 Hz and 10 hPa x s(-1) x L(-1) at 16 Hz. Instantaneous Rrs and RL,sb varied systematically during the respiratory cycle, exhibiting various amounts of flow- or volume-dependence in the seven patients; the amplitudes of their variations were significantly correlated, but Rrs was much more flow-dependent than RL,sb in three patients. Also, Rrs exceeded RL,sb at end-expiration in three instances, which could be related to expiratory flow limitation. In conclusion, total respiratory resistance is reliable up to much higher levels of airway obstruction than previously thought, provided upper airway shunting is avoided.

Adult↗
PubMed1999

Lipid peroxidation and antioxidant enzyme activities in patients with type 1 diabetes mellitus.

To evaluate oxidative stress in type I diabetes mellitus, two antioxidant enzymes in erythrocytes, copper-zinc superoxide dismutase (SOD EC 1.15.1.1.) and seleno-dependent glutathione peroxidase (GSH-Px; EC 1.11.19), and two indexes of peroxidation in plasma, thiobarbituric acid reactive substances (TBARS) and organic hydroperoxides (OHP), were measured in 118 patients with insulin-dependent diabetes mellitus (IDDM), classified in accordance with the presence or absence of vascular complications and the degree of metabolic control established by the HbA1c level. Ninety healthy subjects made up the control group. According to our results, plasmatic TBARS and OHP concentrations are significantly higher in diabetics than in controls, and these differences are accentuated in diabetic people with vascular disorders. The GSH-Px activity was significantly reduced in diabetic patients with poor and medium metabolic control in relation to the control group, regardless of the existence or absence of vascular disorders. No differences in SOD activity between diabetic and control groups were found. A significant positive correlation between TBARS and HPO (r=0.683, p<0.001) was found in both the control and diabetic groups. Among the lipid parameters studied, there were only significantly positive correlations between TBARS and total cholesterol; TBARS and triglycerides; OHP and total cholesterol and OHP and triglycerides. Positive correlations between TBARS and HbA1c and between OHP and and HbA1c, and negative correlations between GSH-Px and HbA1c and between SOD and HbA1c were also found. The multiple regression analysis shows that TBARS and HPO correlate negatively with GSH-Px. There was no significant correlation with SOD.

Adult↗
PubMed1998

Importance of the pulse oximeter averaging time when measuring oxygen desaturation in sleep apnea.

The accuracy of pulse oximeters in measuring transient changes in oxygen saturation (SaO2) may be affected by the oximeter time response. The aim of this study was to assess the effect of modifying the pulse oximeter averaging time (T) on the measurement of SaO2 in patients with the sleep apnea-hypopnea syndrome (SAHS). Twelve patients with severe SAHS were studied during a nap with conventional oximeters: Ohmeda 3740 and Criticare 501. We compared the readings of each patient's oxygen desaturation measured simultaneously with two identical pulse oximeters. One oximeter was the control (T = 3 seconds), and in the other T was set from 3 seconds to 21 seconds. No significant differences in SaO2 were found when both oximeters were set to the same T (3 seconds). In contrast, increasing T to 12 seconds and 21 seconds in one of the oximeters resulted in considerable and significant differences in the measured SaO2: oxygen desaturation was underestimated by up to 60% when compared with the control. The misestimation of SaO2 induced by settings of T which are within the range selectable in conventional oximeters may be of epidemiological significance when pulse oximetry is used as a complementary diagnostic tool to classify sleep events in SAHS.

Adult↗
PubMed1998

Determination of vitamin B6 (pyridoxamine, pyridoxal and pyridoxine) in pork meat and pork meat products by liquid chromatography.

A liquid chromatographic method for determining vitamin B6 compounds in pork meat and pork meat products is examined. It uses the same extraction procedure as that applied for thiamin and riboflavin determination, followed by a liquid chromatographic separation on a reversed-phase C18 column with 0.01 M H2SO4 as mobile phase at 30 degrees C. 4-Deoxypyridoxine is used as internal standard. The analytical parameters linearity, precision of the method (R.S.D. = 7.3 and 6.9% for pyridoxamine and pyridoxal, respectively) and accuracy obtained by recovery assays (99 and 85.1% for pyridoxamine and pyridoxal, respectively) show that the studied method is useful to measure these compounds in pork meat.

Animals↗
PubMed1998

Selenium, zinc and copper in plasma of patients with type 1 diabetes mellitus in different metabolic control states.

The Studies of selenium (Se), zinc (Zn) and copper (Cu) levels in diabetic patients have led to contradictory findings as the possible relationship between the degree of diabetic control and the changes in mineral contents. In the present study the plasma Cu, Se, and Zn contents of diabetic patients and healthy people were measured and the relationship between these contents and diabetic metabolic control, as determined by glycosylated hemoglobin (HbA1c), was studied. The mean plasma Se content in diabetic patients was significantly lower than in controls (p < 0.01) and a negative correlation between the plasma contents of Se and HbA1c was found. No statistically significant differences in plasma Zn contents, either between patients with type 1 diabetes mellitus and control, were found. A statistically significant sex difference in plasma Cu contents was observed in the control population. In females, statistically significant differences were found in plasma Cu contents between the control subjects and the diabetic patients with medium or poor metabolic control, as well as between diabetic patients with good and poor metabolic control. In males, the only statistically significant differences were between the control subjects and diabetic patients with poor metabolic control. The correlation between plasma contents of Cu and HbA1c is not significant.

Adolescent↗
PubMed1998

Assessment of airflow obstruction during CPAP by means of forced oscillation in patients with sleep apnea.

The forced oscillation technique (FOT) is a noninvasive method to measure respiratory resistance (Rrs) potentially useful for monitoring upper airway obstruction in patients with obstructive sleep apnea/hypopnea syndrome (SAHS). The aim of this work was to test the clinical suitability of FOT in assessing dynamic changes in airflow obstruction in patients with SAHS during continuous positive airway pressure (CPAP) and to investigate the CPAP dependence of Rrs. Forced oscillation (5 Hz) was applied to six male patients with SAHS submitted to CPAP titration procedure. Esophageal pressure was measured with a balloon-tipped catheter. Mid-inspiratory resistance (Rrs,i), mid-expiratory resistance (Rrs,e), and esophageal pressure swings (deltaPes) were computed for the respiratory events recorded at each CPAP level. Rrs,i decreased markedly and significantly from 36.0 +/- 4.0 cm H2O x s/L (mean +/- SEM) at baseline CPAP (4 cm H2O) to 13.1 +/- 2.8 cm H2O x s/L at optimal CPAP (11.3 +/- 0.4 cm H2O). Rrs,e showed a faster decrease with increasing CPAP reaching normal values at approximately 8 cm H2O. Rrs,i was strongly correlated (r2 = 0.94) with deltaPes. Our results suggest that FOT can be used as an alternative to the esophageal balloon for assessing airflow obstruction in patients with SAHS and for CPAP titration. Moreover, FOT allows us to detect phasic changes in resistance within the breathing cycle.

Adult↗