PubMed Health⌕ Search

Biomedical subjects

I Rodríguez

Publications and source records attributed to I Rodríguez.

At least 37 records · Page 2Linked to original sources
PubMed2004

Determination of natural and synthetic estrogens in water by gas chromatography with mass spectrometric detection.

A procedure for the determination of six natural and synthetic estrogens (diethylstilbestrol, estrone, 17beta-estradiol, mestranol, 17alpha-ethinylestradiol and estriol) in water samples is described. Samples, up to 2000 ml, were concentrated using Oasis HLB solid-phase extraction cartridges. Analytes were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide and determined by GC-MS or GC-MS-MS. The reactivity of several silylation reagents versus aliphatic and aromatic hydroxyl groups contained in the structure of the selected analytes was evaluated. Influence of parameters such as sample pH, nature of the water samples and derivatization conditions on the performance of the whole analytical procedure was systematically studied. Under optimal conditions, quantification limits between 1 and 3 ng/l were achieved for the determination of the considered estrogens in sewage water.

Estrogens↗
PubMed2004

Applicability of solid-phase microextraction combined with gas chromatography atomic emission detection (GC-MIP AED) for the determination of butyltin compounds in sediment samples.

The performance of solid-phase microextraction (SPME) applied to the determination of butyltin compounds in sediment samples is systematically evaluated. Matrix effects and influence of blank signals on the detection limits of the method are studied in detail. The interval of linear response is also evaluated in order to assess the applicability of the method to sediments polluted with butyltin compounds over a large range of concentrations. Advantages and drawbacks of including an SPME step, instead of the classic liquid-liquid extraction of the derivatized analytes, in the determination of butyltin compounds in sediment samples are considered in terms of achieved detection limits and experimental effort. Analytes were extracted from the samples by sonication using glacial acetic acid. An aliquot of the centrifuged extract was placed on a vial where compounds were ethylated and concentrated on a PDMS fiber using the headspace mode. Determinations were carried out using GC-MIP AED.

Acetic Acid↗
PubMed2004

Liver disease in heavy drinkers with and without alcohol withdrawal syndrome.

BACKGROUND: Withdrawal syndrome is a hallmark of alcohol dependence. The characteristics of alcohol consumption, closely related to dependence, could influence the development of alcoholic liver disease. The study aimed to investigate if patients with severe alcohol withdrawal syndrome have a peculiar profile of liver disease. METHODS: The study included 256 heavy drinkers (aged 19-75 years, 70.3% males) admitted to an Internal Medicine Department. Patients admitted for complications of liver disease were not included. Severe alcohol withdrawal syndrome (seizures, disordered perceptions, or delirium) developed in 150 patients (58.6%). Alcohol consumption (daily quantity, duration, and pattern [regular or irregular]) was assessed by questionnaire. Liver biopsy was performed in all cases. RESULTS: Patients with alcohol withdrawal syndrome showed a lower prevalence of liver cirrhosis and a higher prevalence of alcoholic hepatitis than patients without it. The negative association of alcohol withdrawal syndrome with liver cirrhosis persisted after we adjusted for sex, daily intake, duration, and pattern of alcohol consumption. Alcoholic hepatitis was independently associated with the irregular pattern of alcohol consumption, which was closely associated with severe alcohol withdrawal syndrome. CONCLUSIONS: The profile of liver injury is different in heavy drinkers who develop and who do not develop a severe alcohol withdrawal syndrome when admitted to the hospital.

Adult↗
PubMed2004

Factors associated with mortality of patients with myxoedema coma: prospective study in 11 cases treated in a single institution.

This study was carried out to investigate the clinical and biochemical factors which might be of importance in predicting the outcome of patients with myxoedema coma. Eleven patients (ten female) aged 68.1+/-19.5 years attended our institution over a period of 18 years. Glasgow and APACHE II scores and serum free thyroxine and TSH were measured in all the patients on entry. Patients were selected at random to be treated with two different regimens of l-thyroxine. Four patients died with the mortality rate being 36.4%. The patients in coma at entry had significantly higher mortality rates than those with minor degrees of consciousness (75% vs 14.3% respectively, P=0.04). The surviving patients had significantly higher Glasgow scores than those who died (11.85+/-2.3 vs 5.25+/-2.2 respectively, P<0.001). Comparison of the mean values of APACHE II scores between the surviving group and those who died was significantly different (18.0+/-2.08 vs 31.5+/-2.08 respectively, P<0.0001). The degree of consciousness, the Glasgow score and the severity of the illness measured by APACHE II score on entry were the main factors that determined the post-treatment outcome of patients with myxoedema coma.

APACHE↗
PubMed2003

Determination of acidic drugs in sewage water by gas chromatography-mass spectrometry as tert.-butyldimethylsilyl derivatives.

A procedure is described for the determination of five acidic non-steroidal anti-inflammatory pharmaceuticals (ibuprofen, naproxen, ketoprofen, tolfenamic acid and diclofenac) in sewage water. The analytical method involves the concentration of water samples using a solid-phase extraction polymeric sorbent, functionalized with N-vinylpyrrolidone. Analytes were eluted with ethyl acetate. derivatized using N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and analyzed by GC-MS. Influence of time, temperature and volume of MTBSTFA in the yield of the derivatization step were studied in detail using a factorial central composite design. Quantification limits of the analytical procedure for 500 ml of sewage water ranged from 20 to 50 ng/l. Recoveries from 90 to 115% were found for sewage water samples spiked with the studied compounds at the low ng/ml level. Results obtained for real samples show the presence of ibuprofen and naproxen in both influent and effluent of a sewage water treatment plant.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Production and characterization of monoclonal antibodies to E1 Tor toxin co-regulated pilus of Vibrio cholerae.

Murine monoclonal antibodies (MAbs) against Vibrio cholerae toxin co-regulated pilus (TCP) were generated using conventional hybridoma procedures. Four hybridomas were obtained and two characterized. Hybridomas 10E10E1 and 4D6F9 secreted antibodies of the IgG2a and IgG1 isotypes, respectively, that reacted with a 24-kDa antigen corresponding to the product of the El Tor tcpA gene fused to a six Histidine tail. Additionally, MAbs produced by 4D6F9 selectively recognized the major pilin subunit (TcpA) of El Tor and O139 vibrios in western immunoblot, while MAbs from 10E10E1 also cross-reacted with classical TcpA. Furthermore, vibrios expressing TCP on their surface selectively inhibited binding of the antibodies secreted by both hybridomas to TcpA-coated microtiter plates. Thus, the MAbs reported in this work detected the structural subunit of the pilus either denatured or assembled on the bacterial surface.

Animals↗
PubMed2003

Helium-3 MRI diffusion coefficient: correlation to morphometry in a model of mild emphysema.

Hyperpolarised gases have been most recently used in magnetic resonance imaging to demonstrate new image-derived pulmonary function parameters. One of these parameters is the apparent diffusion coefficient, which reflects the sizes of the structures that compartmentalise gas within the lung (i.e. alveolar space). In the present study, noninvasive parameters were compared to microscopic measurements (mean linear intercept and mean alveolar internal area). Nonselective helium-3 gas density coronal ex vivo images and apparent diffusion maps were acquired in control and elastase-induced panacinar emphysema rats. Total lung capacity was considered the reference for both imaging experiments and lung fixation. A mild degree of emphysema was found based on mean linear intercept (134 +/- 25 microm) versus control (85 +/- 14 microm). The apparent diffusion coefficients were significantly different between the two groups (0.18 +/- 0.02 and 0.15 +/- 0.01 cm2 x s(-1) for elastase and control, respectively). A significant correlation between the apparent diffusion coefficient and corresponding morphometric parameters in mild emphysema was demonstrated for the first time. This study opens the possibility of estimating absolute airspace size using noninvasive techniques.

Animals↗
PubMed2002

Effect of vigabatrin on the pharmacokinetics of carbamazepine.

OBJECTIVE: To evaluate a possible interaction between vigabatrin and carbamazepine in epileptic patients. METHODS: Steady-state serum concentrations of carbamazepine with and without vigabatrin were compared. The study group consisted of 15 patients (eight females, seven males, and mean age 31 +/- 12 years), with refractory partial epilepsy. They received vigabatrin as add-on therapy. Patients received carbamazepine monotherapy for at least 6 months and the carbamazepine-vigabatrin combination for at least 3 months. Blood samples were obtained in the morning, before the first daily dose and the carbamazepine plasma concentrations were analysed by fluorescence polarization immunoassay (TDx System). RESULTS: No statistically significant differences were found in mean carbamazepine daily dose. Mean trough concentrations were 7.9 +/- 1.4 microg/mL with carbamazepine alone, and 6.5 +/- 2.0 microg/mL with carbamazepine-vigabatrin association (P < 0.03). The mean values of pharmacokinetic parameters were: level/dose ratio (L/D) = 0.59 +/- 0.20 vs. 0.45 +/- 0.15 (P < 0.05) and plasma clearance (Cl) = 78.5 +/- 25.8 vs. 105.8 +/- 38.9 mL/h/kg (P < 0.05), with carbamazepine alone and carbamazepine-vigabatrin combination, respectively. CONCLUSION: Vigabatrin produced a statistically significant increase in the plasma clearance of carbamazepine when the two drugs were given simultaneously.

Administration, Oral↗
PubMed2002

Subclinical pain and thermal sensory dysfunction in children and adolescents with Type 1 diabetes mellitus.

AIMS: To assess cutaneous thermal and pain thresholds in upper and lower limbs in neurologically asymptomatic children and adolescents, and to study the relationships of clinical parameters and these sensory thresholds in subclinical diabetic neuropathy. METHODS: Thirty-five neurologically asymptomatic patients, aged 8-16 years, diagnosed with Type 1 diabetes mellitus (DM), and a control group of 35 healthy age-matched subjects participated in the study. Warmth, cold, and heat-induced pain thresholds were measured in the dorsum of the right arm and foot, using quantitative sensory testing (QST). Relevant clinical parameters, retrieved from medical records or measured at the QST session, were obtained for each patient. RESULTS: Compared with controls, diabetic patients had increased thresholds for warmth in the hand (P = 0.002), and cold and warmth in the foot (P = 0.015 and P = 0.004, respectively). Of the diabetic patients, 43% showed abnormality of at least one sensory threshold. A significant correlation was observed for duration of diabetes and heat-induced pain threshold in the hand (P = 0.045), but no correlation was found for age, height, weight, pre-test blood glucose, age of onset, current insulin dose, and mean of glycosylated haemoglobin determinations of the previous 18 months. No significant correlation was found for other sensory thresholds. CONCLUSIONS: Using QST, abnormal cutaneous thermal perception is a common finding, in both upper and lower limbs, in neurologically asymptomatic young diabetic patients. Heat-induced pain threshold in the hand was correlated with the duration of the diabetes.

Adolescent↗
PubMed2001

Chimeric synthetic peptides from the nucleocapsid p24 protein of human immunodeficiency virus type-1.

Two chimeric synthetic peptides incorporating antigenic sequences from N-terminal (peptide C14) (134-163) and C-terminal (peptide C15) (335-364) of the p24 protein of human immunodefiency virus (HIV- 1), were synthesized. Peptides C14-GG-C15 and C15-GG-C14 represented sequences from the p24 protein in both possible orders, separated by two glycine residues as arm spacers. These peptides were evaluated as antigen in an Ultramicroenzyme-linked immunosorbent assay (UMELISA) using sera of HIV-1-infected individuals (n = 16) with different titers of antibodies and the specificity was evaluated with healthy blood donors (n = 20). The results were compared to plates coated with monomeric peptides C14 and C15. The chimeric peptide C14-GG-C15 was the most antigenic. Those results may be related to the peptide structure, the sequence order in the chimeric peptide, and epitope accessibility to the antibodies. This chimeric peptide would be very useful for HIV-1 diagnostics.

Amino Acid Sequence↗
PubMed2001

Simultaneous determination of butyltin and phenyltin species in sediments using ultrasound-assisted leaching.

A fast and simple procedure is presented for the simultaneous leaching of butyl (mono, di and tributyl) and phenyl organotin species from sediment samples. Leached compounds are further ethylated with sodium tetraethylborate in aqueous medium, and analyzed by gas chromatography. After testing the stability of triphenyltin under different extraction conditions, ultrasound-assisted leaching at room temperature in the presence of acetic acid was been proposed as an extraction procedure compatible with the simultaneous determination of phenyl- and butyltin compounds in sediments. Recoveries between 70 and 90% were obtained for phenyl species in spiked samples prepared in the laboratory. Results for butyltin species were validated by use of the reference material PACS-2. Quantification limits, using GC-MIP-AES as measurement technique, were approximately 5-10 ng g(-1). Precision in the consecutive analysis of three sediment samples varied between 3 and 10%.

Chromatography, Gas↗
PubMed2001

Regulation of serine-type exoproteinases by endogenous inhibitors present in exoantigens of the mycelial form of Paracoccidioides brasiliensis.

We have partially characterized some biochemical properties of exoproteinases secreted into culture medium by the mycelial form of Paracoccidioides brasiliensis, a dimorphic fungus that causes human disease in Latin America. Proteinase activity was analyzed in solid- and liquid-phase systems using zymography and Azocoll, respectively. Minimal or no gelatinase activity was observed by zymography in the crude filtrates among proteins with a relative mobility greater than 200 kDa. When the crude filtrate was fractionated by isoelectric focusing or ion exchange chromatography, we observed striking activation of gelatinases, both those of high apparent molecular mass and alkaline isoelectric points (pI), as well as those of lower molecular mass and acidic pI. The apparent high molecular mass gelatinases, pI 10, showed optimal activity at pH 7.0. They were totally inhibited by phenylmethylsulfonylfluoride and partially inhibited by incubation with previously neutralized fractions of pI 5.4 and 6.1. The latter inhibition could be reversed by exposure to 10% isopropanol. These results provide evidence of regulatory mechanisms controlling proteinase activity in secreted proteins. The principal mechanism appears to be the formation of reversible complexes with endogenous inhibitors.

Antigens, Fungal↗
PubMed2001

Pneumococcal pyomyositis.

Pyomyositis is most commonly caused by Staphylococcus aureus. A 25-month-old child developed infection of the biceps brachialis muscle caused by Streptococcus pneumoniae. The child had no underlying immune or anatomic defect.

Child, Preschool↗
PubMed2000

Solid-phase extraction of phenols.

Sample preparation for phenol analysis using solid-phase extraction (SPE) is reviewed. The scope of the review has been restricted to the literature dealing with the analysis of phenols as the main objective. The use, advantages and disadvantages of silica sorbents, polymeric, functionalized, carbon-based and mixed available sorbents, when applied to the separation and preconcentration of phenols, as well as the available experimental devices, are discussed. Other aspects such as phenol derivatisation prior to SPE, solid-phase microextraction, matrix effects and the storage of phenols in SPE cartridges, have been also discussed.

Chromatography, Liquid↗
PubMed2000

Very high expression of an anti-carcinoembryonic antigen single chain Fv antibody fragment in the yeast Pichia pastoris.

In this paper we report the development of a recombinant strain of the yeast Pichia pastoris, which secretes an anti-carcinoembryonic antigen single chain Fv (scFv) antibody fragment to the culture supernatant as a biologically active protein, at levels of 1.2 g l(-1). The yeast scFv was purified by IMAC, with a final yield of approximately 0.440 g of 93% pure scFv per liter of culture supernatant. The specific activity in ELISA of the yeast scFv was almost three times higher than that of a bacterial periplasmic counterpart. These results reaffirm that the yeast P. pastoris is a suitable host for high level production of scFv antibody fragments with potential in vivo diagnostic and therapeutic applications.

Adenosine Triphosphatases↗
PubMed2000

High-speed chiral separations on microchip electrophoresis devices.

High-speed electrophoretic chiral separations have been successfully performed in a microfabricated device by employing cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC). Utilizing short separation channels and relatively high field strengths in combination with small volume-defined injection plugs, and operating in counter-electroosmotic flow conditions, fast and efficient separations of fluorescein insothiocyanate (FITC)-labeled amino acid enantiomers were obtained. Analysis time ranged from 75 s for the most basic amino acids to 160 s for the most acidic ones with associated efficiencies from 7000 up to 28 000 effective plates (100 000 to 395 000 plates/m). Buffer parameters were varied in order to study the effect on chiral resolution. A buffer system consisting of 100 mM borate (pH 9.4), 30 mM of SDS, and 10 mM gamma-CD as chiral selector provided adequate resolution of the majority of FITC-amino acid enantiomers tested.

Animals↗