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Biomedical subjects

R García

Publications and source records attributed to R García.

At least 37 records · Page 2Linked to original sources
PubMed2003

O/W microemulsions for oral drug delivery.

Quaternary microemulsion compositions for oral administration using isopropyl myristate, polysorbate 80 and ethanol 96 degrees were developed and three ratio of polysorbate to ethanol were selected. Isotropic single-phase compositions were considered as microemulsions and were registered on a Pseudo-Ternary Phase Diagram. The objective was to formulate a therapeutic dose for lorazepam and loperamide in a drop liquid form. Another aim was to obtain a liquid oral formula for nifedipine taking advantage of its insured fast absorption to be used in hypertensive crises. The physical stability of the compositions was evaluated by normal aging, centrifugal resistance time and by cycling as well. The selected formulation characterization included density, pH and conductivity measurements. The particle size distribution was determined by a light scattering method and, finally the carried drugs concentration was valued. The versatility showed by this type of systems allows both to carry drugs of different physico-chemical properties and to deal with a number of pharmacotherapeutic objectives.

Administration, Oral↗
PubMed2002

Capillary electrophoretic analysis of inorganic anions in atmospheric hailstone samples.

A new application of capillary electrophoresis (CE) for measuring inorganic anions in hailstones was carried out. Five hailstone specimens were collected from large blocks of ice that fell in January 2000 in some provinces of Spain. Sample handling and preparation procedures were performed with care. CE analysis of anions was carried out using indirect UV detection at 254 nm with a negative power supply (-15 kV) and hydrostatic injection (10 cm for 30 s) at 35 degrees C. Anion separation was completed in less than 4 min. The working electrolyte consisted of 4.7 mM sodium chromate, 4.0 mM OFM-OH (tetradecyltrimethylammonium hydroxide), 10 mM CHES [2-(N-cyclohexylamino)ethanesulfonic acid], and 0.1 mM calcium gluconate (pH 9.1). Good repeatability of migration times after eight injections (<0.7% RSD), adequate linearity responses (r2>0.9) as well as satisfactory detection limits (<0.35 ppm) were achieved. The analytical results provided by CE were compared with those obtained by traditional wet-chemical (WCH) methods. Most of the results obtained by CE were consistent with those of WCH, except for one sample.

Anions↗
PubMed2002

Effects of extremely hot days on people older than 65 years in Seville (Spain) from 1986 to 1997.

The effects of heat waves on the population have been described by different authors and a consistent relationship between mortality and temperature has been found, especially in elderly subjects. The present paper studies this effect in Seville, a city in the south of Spain, known for its climate of mild winters and hot summers, when the temperature frequently exceeds 40 degrees C. This study focuses on the summer months (June to September) for the years from 1986 to 1997. The relationships between total daily mortality and different specific causes for persons older than 65 and 75 years, of each gender, were analysed. Maximum daily temperature and relative humidity at 7.00 a.m. were introduced as environmental variables. The possible confounding effect of different atmospheric pollutants, particularly ozone, were considered. The methodology employed was time series analysis using Box-Jenkins models with exogenous variables. On the basis of dispersion diagrams, we defined extremely hot days as those when the maximum daily temperature surpassed 41 degrees C. The ARIMA model clearly shows the relationship between temperature and mortality. Mortality for all causes increased up to 51% above the average in the group over 75 years for each degree Celsius beyond 41 degrees C. The effect is more noticeable for cardiovascular than for respiratory diseases, and more in women than in men. Among the atmospheric pollutants, a relation was found between mortality and concentrations of ozone, especially for men older than 75.

Aged↗
PubMed2002

Suppressed ion chromatography for monitoring chemical impurities in steam for geothermal power plants.

A suppressed ion chromatography (IC) technique has been evaluated as a chemical monitoring tool for detecting major anions (F-, Cl-, NO3- and SO4(2-)) of condensed steam in geothermal power plants. It is shown that the suppressed IC technique provides a suitable means for preventing possible damage to generating equipment in the geothermal industry. An electrical conductivity detector (0.1 microS sensitivity) with an anion-exchange column (IonPac AS4A-SC), a micro-membrane suppressor (AMMS II), and an isocratic high-pressure pump system were successfully used for detecting low concentrations of inorganic anions. Method detection limits for the anions of interest were <0.184 mg/L. Details of the IC methodology as well as some experimental results obtained during its application for the chemical monitoring of geothermal steam pipes are also described.

Chromatography, Ion Exchange↗
PubMed2002

Heat waves in Madrid 1986-1997: effects on the health of the elderly.

OBJECTIVE: The objective of this paper is to analyse and quantify the effects exerted on summer mortality by extremes of heat, particularly among persons aged 65-74 and 75 years and over, groups in which mortality is higher. METHODS: The study included the period from 1 January 1986 to 31 December 1997, for all people aged over 65 years resident in Madrid, based on mortality due to all causes except accidents (ICD-9 codes 1-799), and circulatory (390-459) and respiratory (460-487) causes. Meteorological variables analysed were: daily maximum temperature, daily minimum temperature and relative humidity. To control the effect of air pollution on mortality we considered the daily mean values of sulphur dioxide (SO2), total suspended particulate (TSP), nitric oxides (NOx), nitrogen dioxide (NO2) and tropospheric ozone (O3). Univariate and multivariate ARIMA models were used. Box-Jenkins pre-whitening was performed. RESULTS: The results yielded by this study indicate a mortality increase up to 28.4% for every degree the temperature rises above 36.5 degrees C, with particular effect in women over the age of 75 years and circulatory-cause mortality. The first heat wave that leads to the greatest effects on mortality, due to the higher number of susceptible people and the duration of the heat wave, show an exponential growth in mortality. Furthermore, low relative humidity enhances the effects of high temperature, linking dryness to air pollutants, ozone in particular. CONCLUSIONS: Since a warmer climate is predicted in the future, the incidence of heat wave should increase, and more comprehensive measures, both medical and social, should be adopted to prevent the effects of extreme heat on the population, particularly the elderly.

Aged↗
PubMed2002

[Massive bilateral adrenal hemorrhage after conservative tumor surgery in the isthmus of a horseshoe kidney].

OBJECTIVE: To present a fatal case of massive bilateral suprarrenal haemorrhage (MBSH) after partial nephrectomy. CLINICAL CASE: An 82 year old male treated with oral anticoagulants was diagnosed by means of CT scan and arteriography of having an avascular tumor located at the isthmus of a horseshoe kidney. A tumorectomy with safety surgical margins was performed; It was diagnosed of having a renal adenocarcinoma, which was almost completely necrotic. During the postoperative period, the patient presented abdominal pain, nausea, fever, hypotension and severe respiratory distress. Biochemical studies showed mild hyponatremia and azotemia, accompanied by anemia, leucocytosis and thrombocytosis. An abdominal CT scan demonstrated a MBSH, which produced the patients death soon afterwards. DISCUSSION: Tumoral pathology of horseshoe kidneys presents important topographic and anatomopathologic differences with respect to non-fused kidneys. MBSH is a rare complication of many stress processes especially if an anticoagulant treatment coexists. The treatment has to be initiated as soon as we suspect MBSH, which should be confirmed by hormonal determinations and/or the presence of hyperdense suprarenal lesions at the CT scan.

Adenocarcinoma↗
PubMed2002

Enzymatic esterification of an acid with an epoxide using an immobilized lipase from Mucor miehei as catalyst: optimization of the yield and isomeric excess of ester by statistical analysis.

We have developed the methodology for the esterification of an acid with an epoxide using 2-chlorobutyric acid and 1,2-epoxy-5-hexene catalysed by a Mucor miehei-immobilized lipase. Thus, this methodology could be applied to obtain 2-chloroesters. A factorial design of experiments and a central composite design have been used to optimise the synthesis of these esters. The variables chosen were temperature and initial catalyst concentration, while the responses were yield and isomeric excess of the ester. According to this study, temperature was the most important factor, having a positive influence on the yield and a small negative influence on the isomeric excess of the ester. The yield and isomeric excess of the ester show a greater dependence on temperature compared to the catalyst concentration. Although the effect of the catalyst concentration on both responses is smaller than the temperature effect, the higher selectivity presented by the biocatalyst towards the studied ester considerably decreased the final product distribution.

Acids↗
PubMed2002

[Analysis of survival in dialysis: hemodialysis versus peritoneal dialysis and the significance of comorbidity].

To choose the best possible dialysis technique for those patients with end-stage renal disease continues to be a matter of debate. Even after putting aside the evident influence that economic and geographic factors as well as the health politics may have in the selection of the technique, different studies comparing survival between hemodialysis (HD) and peritoneal dialysis (PD) have shown contradictory results which could be explained by the differing methodological and statistical methods used together with the different influence assigned to the comorbidity found when starting the treatment, a situation that has increased the confusion about this topic. Based on this we performed a retrospective analysis with a follow-up time of seven years including all those patients who started dialytic treatment in our area, with a final number of 3.106 hemodialysis patients and 542 peritoneal dialysis patients. Those patients who were transferred to another treatment technique during the time of the study were excluded. Age higher than 70 years, cardiovascular disease, liver disease, diabetes mellitus and the presence of dyslipidemia were included as comorbidity factors. Peritoneal dialysis patients were younger than those treated by hemodialysis (54.53 vs 60.1 years), but suffered from higher cardiovascular comorbidity and were more often diabetic. The global survival was the same in both groups up to 32 months of treatment. Although no differences were found when comparing those patients without comorbidity factors, those with comorbidity had better survival on hemodialysis. Age higher than 70 years was the only comorbidity factor with statistically significant difference for a better survival in hemodialysis.

Adolescent↗
PubMed2002

[Factors modulating the efficacy of psychosocial treatment in children with attention deficit hyperactivity disorder].

INTRODUCTION: Treatment of patients with attention deficit hyperactivity disorder (ADHD) in recent decades has not been in one way only but rather by using various approaches (pharmacological, behavioural, cognitive, etc.). It is becoming increasingly obvious that hyperactivity requires a multi-disciplinary approach with clear instructions for parents and teachers. Teachers need most information regarding ADHD and its treatment so as to use the techniques which are most effective for directing behaviour in the classroom. OBJECTIVES: This study had two objectives. Firstly, we wished to analyze the efficacy of a psychosocial programme with multiple components (programme for individualized treatment in the classroom) in 50 children with ADHD using the methodology of significant clinical change analysis of Jacobson and Truax (1991). Secondly, to try to define the variables which may modulate cognition and behaviour and possibly affect the results and success or failure of the programme. DEVELOPMENT: Regarding the first objective, it was found that a much more significant proportion improved after following the hyperactivity/impulsivity programme, in the opinions of parents and teachers. Regarding the second objective the results show that the variables which may modulate the efficacy of treatment are deficits in inhibitory control, anxiety, disobedience, isolation and social inadaptation.

Attention Deficit Disorder with Hyperactivity↗
PubMed2001

Regulation of endothelial nitric oxide synthase expression in the vascular wall and in mononuclear cells from hypercholesterolemic rabbits.

BACKGROUND: We recently obtained evidence demonstrating that cultured bovine endothelial cells contain cytosolic proteins that form complexes with the 3'-untranslated region of endothelial nitric oxide synthase (eNOS) mRNA and are associated with its destabilization. The aim of this study was to determine the presence of such proteins and eNOS expression in hypercholesterolemic rabbits as an in vivo model of endothelial dysfunction. METHODS AND RESULTS: Endothelium-dependent relaxation to acetylcholine and the calcium ionophore A23187 was reduced in aortic segments from hypercholesterolemic rabbits compared with controls. Treatment of hypercholesterolemic rabbits with cerivastatin (0.1 mg. kg body wt(-1). d(-1)) restored endothelium-dependent relaxation. Aortic eNOS expression was reduced in hypercholesterolemic rabbits and was accompanied by enhanced binding activity of a 60-kDa cytosolic protein and reduced stability of eNOS mRNA. Cerivastatin treatment upregulated eNOS expression and reduced the interaction of the cytosolic protein with the 3'-untranslated region of eNOS mRNA. Mononuclear cells from hypercholesterolemic rabbits also showed a marked reduction of eNOS expression and eNOS mRNA stability and an increase in binding activity of the cytosolic protein, which were also prevented by cerivastatin treatment. CONCLUSIONS: These results demonstrate the presence of a 60-kDa protein that binds to eNOS mRNA and reductions in eNOS expression in both vascular wall and mononuclear cells that are prevented by cerivastatin.

3' Untranslated Regions↗
PubMed2001

Capillary electrophoresis for measuring major and trace anions in thermal water and condensed-steam samples from hydrothermal springs and fumaroles.

A new application of capillary electrophoresis for measuring major and trace anions in thermal water and condensed-steam samples is presented. Ten fluid samples were collected from hydrothermal springs and fumaroles located in a volcanic zone of Deception Island, Antarctica. Anion separation was achieved in less than 6 min using indirect UV detection at 254 nm with a negative power supply (-15 kV). The electrolyte consisted of 4.7 mM sodium chromate, 4.0 mM electroosmotic flow modifier (OFM) hydroxide, 10 mM 2-(N-cyclohexylamino)ethanesulfonic acid and 0.1 mM calcium gluconate (pH 9.1). Major anions (Cl-, SO4(2), PO4H2+, and CO3H-) were measured using hydrostatic injection (10 cm for 30 s) at 25 degrees C. Trace amounts of anions (F-, Br-, and NO3-) were better determined by electromigration injection (4 kV, 10 s) at 15 degrees C. Good reproducibility of the migration times (<0.72% RSD), a satisfactory linear response and accuracy as well as acceptable detection limits were successfully obtained.

Anions↗
PubMed2001

Adhesion Forces between Lewis(X) Determinant Antigens as Measured by Atomic Force Microscopy.

The adhesion forces between individual molecules of Lewis(X) trisaccharide antigen (Le(X) ) have been measured in water and in calcium solution by using atomic force microscopy (AFM, see graph). These results demonstrate the self-recognition capability of this antigen, and reinforce the hypothesis that carbohydrate-carbohydrate interaction could be considered as the first step in the cell-adhesion process in nature.

antigens↗
PubMed2001

Long-term depolarization regulates the alpha1s, subunit of skeletal muscle Ca2+ channels and the amplitude of L-type Ca2+ currents.

The effects of long-term depolarization on the level of alpha1s and on L-type Ca2+ currents of skeletal muscle were investigated. Long-term depolarization (14 h) caused a 50% decrease of alpha1s, revealed with the Western blot technique. This decline was prevented by preincubation with the Ca2+ channel blocker nifedipine. Electrophysiological experiments using the voltage-clamp technique were performed to measure the actions of long-term depolarization on Ca2+ currents and charge movement. A progressive decline in the amplitude of the Ca2+ currents by depolarizations lasting 0.5-14 h was observed. Similar to Western blot results, the fall in current amplitude was prevented by nifedipine, and it depended on external Ca2+. The nonlinear charge mobilized by step pulses was also significantly reduced (50%) by long-term depolarization. It is suggested that alpha1s subunit is down-regulated by long-term depolarization by a very stringent mechanism and that, in this process, Ca2+ ions permeating through L-type channels play a key role. A new role for the L-type Ca2+ current in skeletal muscle fibers in which the channels are self-regulated is proposed.

Aniline Compounds↗
PubMed2001

Vinorelbine, ifosfamide and cisplatin as first-line treatment in patients with inoperable non-small cell lung cancer.

To assess, in a multicenter setting, the effectiveness of a combination of vinorelbine, ifosfamide and cisplatin in the treatment of non-small cell lung cancer, 123 patients (males=116) with a mean age of 60 years (range 27-75) with stage IIIb/IV non-small cell lung cancer (NSCLC) and performance status <or=2 were treated with vinorelbine (VNR; 25 mg/m(2)) on days 1 and 8; ifosfamide (IFO; 3 g/m(2)) on day 1; and cisplatin (CDDP; 80 mg/m(2)) on day 1, in repeated cycles of 21 days. Response rates, overall patient survival and toxicity profiles of the three-drug combination were assessed. The number of evaluable patients was 112, with a total of 441 cycles administered (mean=3.6 cycles/patient). Dose intensities (mg/m(2)/week; calculated in patients who concluded the proposed treatment and expressed as mean, median, and standard deviation) were: VNR 13.65, 13.32, 4.7; IFO 918.88, 868.97, 258.1; CDDP 23, 24.68, 6.98. Response rates were: complete response=3 (2.4%); partial response=58 (47.2%%); stable disease=20 (16.3%). The most frequent toxic events were nausea and vomiting (G1=33%, G2=31%, G3=8%). Neutropenia was the dose limiting toxicity (G1=6%, G2=11%, G3=10%, G4=7%). Alopecia G3 was a common undesirable effect in all the patients. Time to progression was 296 days (95% confidence interval 261-332) and the mean survival time was 338 days (95% CI 301-374). We conclude that the described therapeutic schedule is effective with good survival rates and response ratios together with a good tolerance and an acceptable toxicity level.

Adult↗
PubMed2001

Characterization of protein glycoforms with N-linked neutral and phosphorylated oligosaccharides: studies on the glycosylation of endoglucanase 1 (Cel7B) from Trichoderma reesei.

Using anion-exchange chromatography the catalyticdomain of endoglucanase 1 (Cel7B) from Trichoderma reesei was resolved in multiple fractions with different isoelectric points, presumably related to different glycoforms of the enzyme. The protein fractions were analysed using lectins and electrospray MS. Isolated N-glycans were analysed by fluorophore-assisted carbohydrate electrophoresis and amine-adsorption HPLC. The results show that this particular preparation contained at least 14 different glycoforms. The major isoform contained only one GlcNAc, presumably N-linked, and one mannose, most probably O-linked to serine/threonine at a separate site. Except for a small population containing Man(5)GlcNAc(2)+1-2 Man, the rest of the protein had negatively charged phosphate-containing N-glycans. All glycoforms contained at least one O-linked mannose residue. The increased negative charge of the protein, introduced by oligosaccharide phosphorylation, is the most probable reason for the different isoelectric points and the occurrence of multiple peaks during purification.

Carbohydrate Conformation↗
PubMed2001

Flow cytometry and the study of central nervous disease in patients with acute leukaemia.

Central nervous system (CNS) leukaemia is still a matter of debate and new technologies are required to improve the classic morphological definition. One hundred and sixty-eight cerebrospinal fluid (CSF) samples from 31 patients with acute leukaemia were analysed by flow cytometry and conventional cytology. Concordant positive and negative findings were found in 158 samples but 10 produced discrepant results. Cytology seemed to offer more precise information in one CSF sample and flow cytometric accuracy could be demonstrated in five samples. We conclude that flow cytometry is of great help in confirming CNS leukaemia and eliminating other conditions. Therefore, leukaemic patients can benefit from double cytological and flow cytometric CSF studies.

Acute Disease↗