Biomedical subjects

Francisco Arias

Publications and source records attributed to Francisco Arias.

7 recordsLinked to original sources

PubMed2006

On-line sample preconcentration using field-amplified stacking injection in microchip capillary electrophoresis.

Previous reports describing sample stacking on microchip capillary electrophoresis (microCE) have regarded the microchip channels as a closed system and treated the bulk flow as in traditional capillary electrophoresis. This work demonstrates that the flows arising from the intersection should be investigated as an open system. It is shown that the pressure-driven flows into or from the branch channels due to bulk velocity mismatch in the main channel should not be neglected but can be used for liquid transportation in the channels. On the basis of these concepts, a sample preconcentration scheme was developed in a commercially available single-cross glass chip for microCE. Similar to field-amplified stacking injection in traditional CE, a low conductivity sample buffer plug was introduced into the separation channel immediately before the negatively charged analyte molecules were injected. The detection sensitivity was improved by 94-, 108-, and 160-fold for fluorescein-5-isothiocyanate, fluorescein disodium, and 5-carboxyfluorescein, respectively, relative to a traditional pinched injection. The calibration curves for fluorescein and 5-carboxyfluorescein demonstrated good linearity in the concentration range (1-60 nM) investigated with acceptable reproducibility of migration time and peak height and area ratios (4-5% RSD). This preconcentration scheme will be of particular significance to the practical use of microCE in the emerging miniaturized analytical instrumentation.

Buffers↗

PubMed2005

Estimation of pK(a) values using microchip capillary electrophoresis and indirect fluorescence detection.

Microchip capillary electrophoresis (CE), coupled with indirect fluorescence detection was investigated for estimating the pK(a) values of non-fluorescent compounds. The CE method is based on the differences in electrophoretic mobility of the analyte as a function of the pH of the running buffer. Nine compounds were tested, including several of pharmaceutical importance, with pK(a) values from 10.3 to 4.6. All buffers contained 5-TAMRA as the fluorescent probe for indirect detection. Calculated pK(a) values agreed well with literature values obtained by traditional methods, differing not more than 0.2 from the literature value. The current work on single lane chips demonstrates the principle of microchip CE with indirect detection as a viable method for estimating pK(a) values. However, increased throughput will be required using a multilane chip to enable the approach to be used practically.

Aniline Compounds↗

PubMed2005

Estimation of logP(ow) values for neutral and basic compounds by microchip microemulsion electrokinetic chromatography with indirect fluorimetric detection (muMEEKC-IFD).

Microchip microemulsion electrokinetic chromatography with indirect fluorimetric detection (muMEEKC-IFD) was used to obtain logP octanol/water (logP(ow)) values for neutral and basic compounds. Six compounds, with logP(ow) values between 0.38 and 5.03, were used to create a calibration curve relating the log of retention factors (logk) obtained from muMEEKC-IFD with the known logP(ow) values. The logP(ow) values for six additional compounds were determined using the logk values obtained by muMEEKC-IFD and the linear relationship between logP(ow) and logk established for the standard compounds. The muMEEKC-IFD buffer was composed of 50 mM 3-[cyclohexylamino]-1-propane-sulfonic acid (CAPS) buffer (pH 10.4) containing 1.2% n-heptane (v/v), 2% sodium dodecylsulfate (w/v), 8% 1-butanol (v/v) and 4 microM 5-carboxytetramethyl-rhodamine (TAMRA) as the fluorophore probe for indirect detection. The muMEEKC-IFD provided an accurate method for estimating logP(ow) values and also a means for analyzing compounds that are non-fluorescent.

Calibration↗

PubMed2005

Assessment of sexual functioning in depressed patients treated with mirtazapine: a naturalistic 6-month study.

UNLABELLED: Antidepressant-induced sexual dysfunction is a frequent side effect which may greatly contribute to treatment non compliance. Mirtazapine has a pharmacological profile expected to result in a lack of sexual dysfunction. The main purpose of this 6-month open-label study was to evaluate the effects of mirtazapine on sexual function of a sample of depressed patients. METHODS: Seventy-eight patients meeting DSM-IV criteria for major depression or adjustment disorder with depressed mood or with mixed anxiety and depressed mood, sexually active prior to the episode, were treated with mirtazapine (15-60 mg/day). Effectiveness was assessed using the 17-item Hamilton rating scale for depression (HAM-D-17), the Hamilton rating scale for anxiety (HAM-A) and the clinical global impression (severity and improvement) scales (CGI). Sexual function was evaluated with the psychotropic-related sexual dysfunction questionnaire (PRSexDQ) which detects clinical changes in sexual dysfunction. RESULTS: Forty-eight patients (61.5%) were experiencing sexual dysfunction at baseline. A return to normal sexual functioning was observed in 27 of 38 (71.1%) patients completing the study. Significant reductions in mean total PRSexDQ scores were detected at day 90 and endpoint and only four patients withdrew or required dose reduction due to mirtazapine-induced sexual dysfunction. A total of 37 patients (47.4%) achieved complete remission of depression (HAM-D-17 score <or= 7) at endpoint. Only seven patients (9.0%) withdrew the study because of adverse events. CONCLUSION: Mirtazapine showed in this study that it is an effective and well-tolerated antidepressant treatment with a possibly lower incidence of sexual side effects than other antidepressants.

Adult↗

PubMed2002

Efficacy of venlafaxine in major depression resistant to selective serotonin reuptake inhibitors.

INTRODUCTION: Some studies suggest that venlafaxine, due to its pharmacodynamic characteristics, could be an effective drug in depression, resistant to other antidepressive agents. This investigation explores the efficacy and tolerability of venlafaxine in major depression, resistant to a selective serotonin reuptake inhibitor (SSRI). METHODS: A multicenter naturalistic study was performed during 6 months and included those patients diagnosed of major depression according to the criteria of DSM-IV who had a minimum score of 18 on the Hamilton Depression Rating Scale (HAM-D) and who had not responded to previous treatment with a SSRI at therapeutic doses for a minimum of 4 weeks. The assessment of efficacy was performed with the HAM-D scale, the Montgomery-Asberg Depression Rating Scale (MADRS), the Hamilton Anxiety Rating Scale (HAM-A) and the Global Clinical Impression (GCI). Tolerability was evaluated by recording the adverse reactions and with the GCI score on overall drug tolerability. RESULTS: A total of 69 patients, of which 59 were evaluable for efficacy (they had fulfilled at least 4 weeks of treatment), were included. About 81% of all of them obtained a reduction of at least 50% in the HAM-D, 74% were considered as "quite improved" or "very improved" in the GCI and 69% met both criteria. The mean dose of venlafaxine used was 170.4 (S.D.=43.8) mg. Of the 21 patients who did not complete the 6 months of treatment, 3 were due to lack of efficacy, 6 due to adverse effects and 12 for other reasons. About 89.2% of side effects were considered as mild or moderate. CONCLUSION: The results of our study support the efficacy and tolerability of venlafaxine in patients suffering from depression who have not responded to SSRI treatment.

Adult↗

PubMed2002

A double-blind, placebo-controlled study of naltrexone in the treatment of alcohol-dependence disorder: results from a multicenter clinical trial.

BACKGROUND: A 12-week, multicenter, double-blind, randomized, parallel-group clinical trial to compare naltrexone and placebo was carried out to determine the efficacy, safety, and tolerability of naltrexone together with a psychosocial intervention in the treatment of alcoholism. METHODS: A total of 202 alcohol-dependent patients were assigned to 12 weeks' treatment with either naltrexone or placebo. The relapse rate was evaluated by means of intention-to-treat analyses. Alcohol consumption, craving, adverse events, and changes in the biochemical markers of heavy drinking and possible toxicity were evaluated in the 192 patients who were considered to be assessable. RESULTS: The survival function for patients who were treated with naltrexone was significantly better than that of the patients who were treated with placebo (Kaplan-Meier log rank = 4, df = 1, p < 0.05). In addition, 7.9% of patients who were treated with naltrexone relapsed as compared with 18.8% of those who received placebo [chi = 5.89, df = 2, p = 0.050]. In comparing naltrexone with placebo-treated patients, the most common adverse events were abdominal pain [8.6% vs. 1%; (chi = 6.1, df = 1, p < 0.05)] and headache [7.5% vs. 1% (chi = 5.1, df = 1, p < 0.05)]. CONCLUSIONS: Naltrexone was well-tolerated, as the rate of adverse events was low, and safe, as it did not interfere with the normalization of biochemical markers of heavy drinking or alter liver function markers. Naltrexone seemed to reduce relapse rate to heavy drinking, but we found no differences in other alcohol consumption variables between naltrexone- and placebo-treated groups. Although the naltrexone group showed a tendency to consume fewer drinks per drinking day and had a longer time to first drink, differences were not statistically significant.

Adult↗

PubMed2002

Nefazodone in the treatment of elderly patients with depressive disorders: a prospective, observational study.

OBJECTIVES: The aim of this study was to evaluate the clinical effectiveness and tolerability of nefazodone for the treatment of depression in elderly patients in clinical routine practice. PATIENTS AND STUDY DESIGN: Seventy-nine patients with a mean age of 72.81 years, who had major depression or dysthymia according to DSM-IV criteria, were enrolled into this open label study. Patients were prescribed nefazodone starting at 50 mg/day, increasing every 4 days until a dosage of 200 mg/day was attained, and subsequently upward to 600 mg/day if no dose-limiting adverse effects appeared. Effectiveness was evaluated at the end of weeks 2, 4, 8 and 12 by completion of the Hamilton Depression Rating Scale (HAM-D), the Geriatric Depression Scale (GDS) and the Clinical Global Impressions scale. The Hamilton Anxiety Rating Scale (HAM-A), the sleep satisfaction item of the Oviedo Sleep Questionnaire (OSQ) and the Short Portable Mental Status Questionnaire (SPMSQ) were used to assess the patients at the end of week 12. Primary efficacy analysis was based on an intention-to-treat, last-observation-carried-forward data set. RESULTS: HAM-D scores decreased progressively from a baseline mean of 22.3 to 14.2 at the study endpoint; although this was a significant reduction, the endpoint score indicates that a significant residual symptomatology remained in the patients. Similarly, the GDS and HAM-A scores had decreased significantly by week 12. Response and remission rates were 47 and 37.5%, respectively. The percentage of patients who were satisfied, much satisfied or very much satisfied with their sleep according to the OSQ increased from 4.2% at baseline up to 62.2% at the study endpoint. A significant reduction in the SPMSQ total score was observed at the study endpoint, although the clinical relevance of this finding is doubtful. Forty-two (53.2%) patients completed the study. The most common reasons for withdrawal from the study were a lack of efficacy and adverse effects. Most adverse reactions were mild to moderate in severity and included dizziness, dry mouth, gastrointestinal distress, sedation, anxiety and malaise. CONCLUSION: Our results suggest that nefazodone may be a well tolerated and effective alternative for treating elderly patients with depression. Although the HAM-D score at study endpoint indicated significant residual symptomatology, a similar finding has been described in several meta-analyses of antidepressant treatment in the elderly. Further research is needed to evaluate a different nefazodone dose regimen, especially a slower dose titration rate, which could result in a reduced discontinuation rate and thus a better treatment outcome.

Aged↗