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Biomedical subjects

F Veiga

Publications and source records attributed to F Veiga.

13 recordsLinked to original sources
PubMed2003

[Multicenter, prospective study comparing enoxaparin with unfractionated heparin in the treatment of submassive pulmonary thromboembolism].

OBJECTIVE: To compare the safety and efficacy of enoxaparin and unfractionated heparin in the treatment of submassive pulmonary thromboembolism (PTE). MATERIAL AND METHODS: Fifty-six patients with PTE who did not need fibrinolytic treatment were enrolled prospectively. The patients were randomly assigned to 2 treatment groups: Group A received enoxaparin (1 mg/kg every 12 hours) and Group B received adjusted doses of unfractionated heparin. The oral anticoagulant therapy was started on confirmation of the diagnosis and continued for 6 months. Incidences of recurrence of thromboembolism and of severe bleeding were assessed at the end of this period. RESULTS: Six patients were withdrawn from the study. Twenty-nine of the 50 remaining patients were in Group A (enoxaparin) and 21 in Group B (unfractionated heparin). A recurrence of thromboembolism was diagnosed in 3 patients from Group A (10.7%) and 2 patients from Group B (9.5%). There were no significant differences. Two patients died, one death being attributed to bleeding secondary to the oral anticoagulant treatment (Group A) and the other to a process unrelated to PTE. CONCLUSIONS: Enoxaparin seems to be as effective and safe as unfractionated heparin in the initial treatment of PTE.

Aged↗
PubMed2003

Effect of polymer hydration on the kinetic release of drugs: a study of ibuprofen and ketoprofen in HPMC matrices.

Samples of drug/hydroxypropylmethylcellulose (HPMC) mixtures and matrices (drug/HPMC mixtures plus excipients) were allowed to equilibrate in closed chambers with defined relative humidities (RHs). Their water uptake and drug release were evaluated by differential scanning calorimetry/thermogravimetric analysis and dissolution studies, respectively. Analysis of the thermal behaviors of the drug/HPMC mixtures and of the polymer alone, as functions of RH, leads to the conclusion that most of the hydration water is retained by the polymer, and points to the occurrence of different types of hydration water, from the strongly polymer-bound water molecules at RH values up to 81%, to the almost "free water" for RH values close to 100%. In addition, application of the Korsmeyer model to the dissolution results leads to the conclusion that the rate determining dissolution processes are predominantly of the fickian type.

Calorimetry, Differential Scanning↗
PubMed2002

Physical properties of chitosan pellets produced by extrusion-spheronisation: influence of formulation variables.

Pellets comprising chitosan, cellulose microcrystalline, povidone, filler excipient and diclofenac sodium as model drug were prepared by extrusion-spheronisation. The effects of chitosan load (zero, 0%, low, 4% and high, 16% levels), type of filler (lactose, tribasic calcium phosphate and beta-cyclodextrin) and composition of the binding liquid (ethanol/water mixtures 20 and 50%) on physical characteristics of pellets were evaluated. A three-factor factorial design was employed in the study. Analysis of variance (ANOVA) indicated that single factors had significant effect on the physical characteristics of the pellets. The type of filler followed by polymer load markedly affected the density. The type of binding liquid had negligible effect on the shape and surface roughness of the pellets. Increase in the chitosan load resulted in pellets of lower porosity values. This could be attributed to the binding capacity of chitosan and povidone leading to more compacted structures. Chitosan load and type of filler had significant influence on the surface roughness. The surface of pellets became rougher as the chitosan load increased, however, there was no significant difference between zero and low contents of chitosan. Pellets prepared using tribasic calcium phosphate showed a smoother surface when compared with formulations including lactose or beta-cyclodextrin. Chitosan was useful to provide pellets of acceptable physical characteristics when employing an alcohol/water mixture 50% (v/v) as binding liquid for the extrusion-spheronisation process.

Analysis of Variance↗
PubMed2001

Dynamics of glyphosate and aminomethylphosphonic acid in a forest soil in Galicia, north-west Spain.

Residues of the herbicide glyphosate (N-phosphonomethylglicine) and its main metabolite, aminomethylphosphonic acid (AMPA), were determined in a forest soil in north-west Spain, previously treated with 5 and 8 l ha(-1) of glyphosate. Both products were monitored in the solid and liquid soil phases for an 8-week period after the treatment. Soil samples were extracted by KH2PO4. Concentrated extracts and liquid phase samples were derivatized with 9-fluorenylmethyl chloroformate (FMOC) before determination by HPLC using an anion exchange column and spectrofluorometric detection. The treated soil peaked at 6.9 microg g(-1) of glyphosate, whereas soil water samples peaked at 0.74 microg ml(-1) of glyphosate. One month after the treatment, both glyphosate and AMPA concentrations in soil and water samples were almost negligible. AMPA peaked at 0.77 microg ml(-1) in soil water samples. Glyphosate and AMPA exhibited high vertical mobility in the treated soil, quickly reaching high concentrations in subsurface horizons where the degradation is slower.

Environmental Monitoring↗
PubMed2001

Influence of the preparation method on the physicochemical properties of tolbutamide/cyclodextrin binary systems.

Tolbutamide (TBM) was found to form an inclusion complex with beta cyclodextrin (beta-CD) in solution and in solid state. Inclusion complex formation between tolbutamide and beta-cyclodextrin in aqueous solution was studied by phase solubility and spectral shift methods. The apparent stability constant Ks calculated by these techniques, in water, were estimated as 195.7 and 236.5 M(-1), respectively. The phase solubility studies revealed a B(S)-type diagram with an inclusion complex of 1:2 molar ratio. The solid inclusion complexes of TBM and beta-CD were prepared at a molar ratio of 1:2 by kneading, coprecipitation, freeze-drying, and spray-drying methods. In addition, the physical mixture was prepared. Characterization of TBM: beta-CD inclusion was performed using differential scanning calorimetry (DSC), Raman spectroscopy, and X-ray diffractometry and by application of a so-called ether wash method. All the inclusion systems investigated led to a significant improvement in the dissolution over free TBM, and the dissolution rate of the active material was observed to be independent of the preparation method.

Calorimetry, Differential Scanning↗
PubMed2000

Oral bioavailability and hypoglycaemic activity of tolbutamide/cyclodextrin inclusion complexes.

The purpose of the present study was to evaluate the enhancement of tolbutamide (TBM) oral bioavailability and hypoglycaemic activity through complexation with beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD). TBM and its freeze-dried inclusion complexes were administered to rabbits (New zealand breed; n=6), in a dose of 20 mg/kg. TMB plasma levels were measured by HPLC and glucose levels were analysed according to Trinder (Trinder, P., 1969. Determination of glucose in blood using glucose oxidase with an alternative oxygen acceptor. Ann. Clin. Biochem. 6, 24-28). The pure drug attained a maximum of plasma concentration (C(max)) of 18.58+/-3.27 microg/ml at 8.5 h (T(max)), whereas with inclusion complexes, C(max) increased about two times and appeared at ca. 4 h. AUC(0-24) of complexes was about 1.6 times as much as that of the pure drug. Thus, the extent of oral absorption of TBM from inclusion complexes was significantly greater and faster when compared with drug alone. In addition, without cyclodextrins the maximum hypoglycaemic effect (CVG(max)) of TBM (34. 1%) was observed at 5.6 h (Tg(max)). CVG(max) of TBM/beta-CD and TBM/HP-beta-CD inclusion complexes were 34.1% (at 6.5 h) and 37.7% (at 5.1 h), respectively. AAC(0-24) of inclusion complexes was 1.4 times larger than that of pure drug. Hence, the oral administration of complexed TBM not only improved the drug absorption, but also the TBM hypoglycaemic activity.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2000

The influence of diluent on the release of theophylline from hydrophilic matrix tablets.

The role of beta-cyclodextrin (beta-CD) on the apparent solubility of theophylline was investigated by the solubility method. Binary systems of theophylline and beta-CD were prepared using the dry co-grinding method. Their characterization was performed by differential scanning calorimetry (DSC). The dissolution rate of theophylline and theophylline/beta-CD and dissolution studies of matrix tablets prepared from mixtures containing theophylline and ground theophylline were carried out. It can be concluded that beta-CD is related to an increase in the apparent solubility and dissolution rate of the drug, promoting improvement on the release of theophylline from matrices manufactured with hydroxypropylmethylcellulose (HPMC). This can be attributed to the amorphous state and the increased wettability of the drug.

Bronchodilator Agents↗
PubMed2000

Low molecular weight heparin (enoxaparin) versus oral anticoagulant therapy (acenocoumarol) in the long-term treatment of deep venous thrombosis in the elderly: a randomized trial.

This study aims to establish the relative effectiveness and safety of low molecular weight heparin in elderly patients with venous thrombosis in order to find an alternative to oral anticoagulant therapy with less bleeding complications in the long-term treatment of deep venous thrombosis (DVT). One hundred consecutive elderly patients (>75 years old) with venographically demonstrated proximal DVT were included in a randomized trial. All patients were treated for ten days with adjusted doses of intravenous heparin. Informed consent was obtained and on the eight day, patients were randomly allocated to receive acenocoumarol (INR 2.0-3.0) or subcutaneous enoxaparin (4000 anti-Xa units once a day) for three months. All patients were followed-up clinically and venographically for a one year period. The results were analyzed with Fisher's exact test or chi-square test as appropriate. During the treatment and surveillance period, 6 of the 50 patients (12%) who received acenocoumarol and 8 of the 50 patients (16%) who received enoxaparin had new episodes of venous thromboembolism confirmed by objective testing (p = 0.6; 95% CI for the difference: -19.5 to 11.5). Hemorrhagic complications occurred in six of the 50 patients (12%) who received acenocoumarol and in one (2%) of those on enoxaparin (p = 0.1; 95% CI for the difference: -1.8 to 21.8). Vertebral fractures developed in 2 patients (4%) in the enoxaparin group (p = 0.5; 95% CI for the difference: -11.4 to 3.4). These results show that fixed dose enoxaparin seems to be effective and safe in the long-term treatment of proximal DVT in the elderly. In comparison with oral anticoagulants, the findings are inconclusive due to the wide confidence intervals for differences between outcomes, however they suggest that the former may have less bleeding complications with similar efficacy.

Acenocoumarol↗
PubMed1997

Dynamic three-dimensional echocardiography: a new era in ultrasound technology.

The use of noninvasive methods to visualise the heart has had an extraordinary development over the last decade, with echocardiography demonstrating a particularly fast growth. Despite its unquestionable role in the diagnosis of heart disease and in the management of cardiac patients, it does have some limitations, both in the morphological visualisation, as well as in the functional assessment of the heart, such as blood flow, quantification of intracardiac volumes, etc. The recent development of dynamic three-dimensional (3D) echocardiography from two dimensional images has opened new perspectives in the study of cardiac pathophysiology. There are basically two methods of displaying three dimensional data sets: (1) a two-dimensional display from individual selected cut planes (any-plane echocardiography) or from parallel short axis cuts; (2) a volume rendered technique: from any defined cut plane, different algorithms are applied to represent the information in space. There are several potential clinical applications of 3D such as the measurement and serial follow-up of left ventricular volumes; in valvular heart disease (the abnormalities can be delineated more precisely and in greater detail than conventional imaging, including a detailed definition of mitral apparatus in mitral stenosis), in mitral valve prolapse both leaflets can be seen from the left atrial view and in endocarditis it can aid in deciding when and how to intervene; in complex congenital heart disease, such as reconstruction of double outlet right ventricle, left-sided obstructive and regurgitant lesions and subaortic obstructive cases, in atrial and ventricular septal defects, displaying size, geometry and relationships to other structures; another expression of cardiac disorders are blood flow disturbances (visualisation of flows in 3D could allow a better qualitative and quantitative assessment of their size and severity; the pictures so far generated allow a good perception of the size and shape of mitral, aortic and tricuspid regurgitation jets, by examining them from a new perspective, it also has the potential to display the flow convergence zone and quantify the regurgitant volume). Recent studies have clearly demonstrated the feasibility of performing three-dimensional imaging in a variety of cardiac diseases, but continued development of ultrasound technology must be made to improve better image resolution. The prolonged acquisition time is the most important limiting factor that currently restricts the routine use of 3D echocardiography. The development of faster computers will shorten the time needed for image acquisition, postprocessing, and data analysis, contributing to the goal of easy access and wide use. With improvements in computer technology and production of interactive software, 3D echocardiography will provide a dynamic view of the surgical anatomy of the heart. Thus, the three-dimensional reconstruction concept has the potential to and diagnostic assessment of cardiac pathology in every facet.

Cardiovascular Diseases↗
PubMed1994

Functional, histologic, and ultrastructural study of the protective effects of verapamil in experimental ischemic acute renal failure in the rabbit.

The present study was performed in vivo in rabbits to evaluate the functional and morphologic effects of verapamil in a model of ischemic acute renal failure (ARF). Particularly impressive was the ultrastructural integrity of renal tubules in the animals exposed to both ischemia and verapamil. Three groups were studied: Group A: no ischemia; Group B: renal ischemia alone; and Group C: renal ischemia with verapamil. Creatinine clearance was higher in Group C (0.77 mL/min/kg) compared to Group B (0.13 mL/min/kg) at 24 h of reperfusion (p < .005) as well as at 48 and 72 h (0.73 mL/min/kg) vs. 0.35 mL/min/kg; p < .05 and 0.90 mL/min/kg vs. 0.46 mL/min/kg; p < 0.05, respectively). Light microscopic evaluation of Group C rabbits revealed significantly better preservation of proximal tubule (PT) brush border (p < .0005) and less desquamation of PT (p < .05) compared to Group B. Ultrastructural examination of in vivo perfused kidneys also demonstrated decreased loss of microvilli of PT (p < .0005) as well as less cellular edema (p < .005), fewer cells with apical PT membrane rupture (p < .01), better preservation of mitochondria (p < .005), less flattening of the PT basolateral labyrinth (p < .05), and fewer hypertrophic actin bands at the basal surface of PT epithelial cells (p < .05). These results suggest that verapamil markedly attenuates PT morphologic injury in a rabbit model of reversible ischemic ARF. The functional protection observed in these studies may be related, in part, to the improved structural integrity of the renal tubules. Renal transplantation and anticipated renal ischemia (i.e., surgical interventions) are two important situations where treatment with verapamil or other calcium channel blockers may prove to be clinically beneficial.

Acute Kidney Injury↗