Biomedical subjects

A Gallardo

Publications and source records attributed to A Gallardo.

At least 19 recordsLinked to original sources

PubMed2006

The role played by environmental factors in the integration of a transfer station in a municipal solid waste management system.

Transfer stations are an integral part of present-day municipal solid waste management systems. The main criteria used to decide on the location of a transfer station has traditionally been the minimization of transport costs, since it is cheaper to transport great amounts of waste over long distances in large loads than in small ones. In this study, we are going to consider the environmental factor in order to compare the feasibility of using a transfer station integrated within a waste management system. Applying the Life Cycle Assessment technique will enable us to obtain an objective parameter that quantifies the environmental impact of transportation and of operating a transfer station. Taking the current rates of solid wastes generation in the Plana region of Castellón (Spain) as our starting point, in this study we compare the environmental costs involved in the process of taking municipal wastes directly to the nearest waste treatment facility, with those involved in a waste management system integrating a transfer station. Comparing these two cases, an average reduction of 16.8% in the environmental impact can be obtained when a transfer station is incorporated in the waste management system.

Environment↗

PubMed2005

Histological evaluation of scar tissue inflammatory response: the role of hGH in diabetic rats.

This paper describes a polymer site-specific delivery system containing human growth hormone in an in vivo model of scarring in the diabetic state. Copolymer discs with the hormone were introduced into incisions made in rats previously injected with streptozotocin in order to induce diabetes. Tissue specimens for evaluation were obtained at 3, 7 or 10 days after the procedure. Study groups were healthy rats and diabetic rats untreated or treated with/without the hormone. Histological sections were prepared for light microscopy examination of wound zones. Three and 7 days after surgery, polymer remains could be observed in the subcutaneous tissue. These remnants induced a moderate foreign body reaction. The number of macrophages detected was directly related to neovessel formation and metalloelastase expression. The CD4+/CD8+ ratio was low during the initial follow up stages (3 and 7 days) in untreated diabetic rats, yet an increased ratio corresponding to areas around the polymer remains was noted in the animals treated with copolymer loaded with the growth hormone. Copolymer is biodegradable in vivo and may be used as a vehicle for the slow release of active substances. The presence of the hormone at the site of skin injury induces cell proliferation and enhances the repair process.

Animals↗

PubMed2003

Rupture of the lesser gastric curvature after a Heimlich maneuver.

BACKGROUND: We present a case of lesser gastric curvature injury after a Heimlich maneuver due to obstruction of the breathing tract that was repaired by laparoscopic surgery. METHODS: A patient with perforation of the lesser gastric curvature as a result of closed abdominal traumatism was operated on using the laparoscopic approach with the use of four trocars as work openings. With this technique, the diagnosis was confirmed, the injury repaired, and the abdominal cavity washed. RESULTS: The postoperative period was favorable and the patient was released from the hospital on day 7 without any complications. CONCLUSIONS: Laparoscopic surgery can be technically reproduced in the treatment of gastric injury as a result of closed abdominal traumatism.

Aged↗

PubMed2002

Fast and sensitive capillary electrophoresis method to quantitatively monitor ibuprofen enantiomers released from polymeric drug delivery systems.

In this work, the capability of two polymeric drug delivery systems (DDS) containing racemic ibuprofen (IBU) for controlled release of IBU in different media was studied carrying out assays in-vitro. To quantitatively monitor the release of R(-)- and S(+)-IBU, a fast, sensitive and inexpensive capillary electrophoresis (CE) method was developed. To do this, different chiral selectors, temperatures, buffer compositions and pHs were tested. This new CE method uses bare silica columns together with a buffer containing 6% Dextrin in a 150 mM sodium tetraborate buffer at pH 9. Baseline separations of R(-)- and S(+)-IBU were achieved in less than 5 min at 20 degrees C. By using this method, both enantiomers can be determined at concentrations as low as 1 microg/ml, allowing the detection of enantiomeric percentages of 0.5% of R(-)-IBU in the presence of 99.5% of the optical antipode. Moreover, the method shows a high reproducibility for the same day and different days. The usefulness of this method to quantitatively monitor the release of R(-)- and S(+)-IBU from two different polymeric DDS is demonstrated. It is shown that the release rate of IBU depends on the spacer of the side residue used in the polymeric device. Also, it is demonstrated that the release of both enantiomers is enzymatically activated in rat plasma.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2002

Monitoring ibuprofen enantiomers released from polymeric systems.

Two methacrylic derivatives of ibuprofen (N-[4-[2-(4-isobutylphenyl)propionyloxy]phenyl] methacrylamide (MAI) and 2-[(4-isobutylphenyl)propionyloxy]ethyl methacrylate (MEI)) were used together with 2-hydroxyethyl methacrylate (HEMA) to synthesize four polymeric materials: two hydrophobic homopolymers, PMAI and PMEI, and two hydrophilic copolymers containing 70% (w/w) HEMA, MAI-HEMA 30 and MEI-HEMA 30. The enantiomeric determination of R- and S-IBU released from these four systems has been carried out by capillary electrophoresis. Release of R- and S-IBU was monitored during in vitro assays done at 37 degrees C at pH 7.4 and 10 in buffered solutions and rat plasma. There is a hydrolytical activation in plasma and at pH 10 compared to pH 7.4; moreover, the release rate from the copolymers is much higher than from the homopolymers as a consequence of the greater hydrophilic character. A slight excess of the S-enantiomer of IBU is observed in all the experiments, being more relevant at higher release rates, i.e. copolymers at pH 10.

Animals↗

PubMed2001

Modulated release of cyclosporine from soluble vinyl pyrrolidone--hydroxyethyl methacrylate copolymer hydrogels. A correlation of 'in vitro' and 'in vivo' experiments.

Soluble, uncrosslinked and high molecular weight copolymers of vinylpyrrolidone, VP, with 2-hydroxyethyl methacrylate, HEMA, prepared by free radical copolymerization, are proposed as supports for the modulated release of the immunosuppressor cyclosporine. Two copolymeric systems with copolymer compositions f(VP)=0.52 (namely VP--HEMA 60--40) and 0.42 (VP--HEMA 40--60) have been prepared and tested in vitro and in vivo using rats as animal model. Micellar electrokinetic capillary chromatography, MEKC, has been used for the simultaneous detection of the polymer reabsorption and the drug release for the in vitro experiments. The composition and microstructural distribution of the copolymer system controls the solubilization rate which modulates the in vitro release of the drug (with time profiles from a few days to several weeks for the VP--HEMA 60--40 and 40--60, respectively) and the in vivo response that correlates with the previous in vitro results: the more hydrophobic implant (VP--HEMA 40--60) reverts the immune response more slowly (2--4 weeks) compared to the more hydrophilic one (VP--HEMA 60--40, 1--2 weeks).

Animals↗

PubMed2001

NSAIDs bound to methacrylic carriers: microstructural characterization and in vitro release analysis.

Chemically controlled drug delivery systems or 'polymeric drugs' based on copolymers of 2-hydroxyethyl methacrylate, HEMA, and five methacrylic derivatives which incorporate ibuprofen or ketoprofen in their chemical structure by means of labile ester bonds, MAI, MAK, MAEK, MEI and MEK, have been prepared by free radical polymerization in solution at 50 degrees C. Three different spacers have been incorporated to the monomer structure: an aromatic amide, an aliphatic ester and a combined aromatic amide/aliphatic ester. Copolymerization reactions of the methacrylamide derivatives with HEMA follow the terminal model with reactivity ratio values, determined by the Tidwell and Mortimer (J. Polym. Sci. A 1965;3:369-378) non-linear least-squares treatment, of r(MAI)=0.38, r(HEMA)=1.69; r(MAK)=0.30, r(HEMA)=0.48; and r(MAEK)=0.66, r(HEMA)=2.85. From these values and considering that the methacrylates MEI and MEK are structurally related to HEMA, the microstructural analysis give us a random distribution of the monomeric units. The HEMA-rich copolymers, used for the in vitro experiments, showed a very high population of sequences with the active residue isolated by HEMA units. The in vitro release experiments were carried out at pH 7.4 and 9, using six different compositions for each copolymer system (1, 2.5, 5, 10, 20 and 30 wt% of the active acrylic monomer). The results show a controlled release in terms of weeks with very different profiles which depend on the type of spacer (the aromatic ester is more susceptible to hydrolysis than the aliphatic one), drug (ketoprofen release rate is higher than the ibuprofen one), composition of the copolymer (as a general rule, the release rate increases with the content of the attached drug until some composition where this effect is reverted because of the global increase in hydrophobicity) and pH (the release rate is noticeably higher in a strong basic medium, pH 9).

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2001

[Hemarthrosis as a hemorrhagic complication after thrombolytic treatment].

Hemorrhage of variable severity is the main complication of thrombolytic treatment. We present the case of a rare hemorrhagic location after the use of this treatment for acute myocardial infarction, as ankle hemarthrosis. In the first twelve hours the patient had a joint hemorrhagic effusion with refractory pain and arthrocentesis was required. Recurrence occurred while receiving heparin and after discontinuation of heparin perfusion stopped the patient developed occlusion of the coronary artery related to the infarct requiring emergency angioplasty. We discuss the severity and possible treatment of this situation.

Adult↗

PubMed2001

Microbial synthesis of poly(beta-hydroxyalkanoates) bearing phenyl groups from pseudomonas putida: chemical structure and characterization.

New poly(beta-hydroxyalkanoates) having aromatics groups (so-called PHPhAs) from a microbial origin have been characterized. These polymers were produced and accumulated as reserve materials when a beta-oxidation mutant of Pseudomonas putida U, disrupted in the gene that encodes the 3-ketoacyl-CoA thiolase (fadA), was cultured in a chemically defined medium containing different aromatic fatty acids (6-phenylhexanoic acid, 7-phenylheptanoic acid, a mixture of them, or 8-phenyloctanoic acid) as carbon sources. The polymers were extracted from the bacteria, purified and characterized by using (13)C nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Structural studies revealed that when 6-phenylhexanoic acid was added to the cultures, an homopolymer (poly-3-hydroxy-6-phenylhexanoate) was accumulated. The feeding with 8-phenyloctanoic acid and 7-phenylheptanoic acid leads to the formation of copolymers of the corresponding units with the n - 2 carbons formed after deacetylation, copoly(3-hydroxy-8-phenyloctanoate-3-hydroxy-6-phenylhexanoate) and copoly(3-hydroxy-7-phenylheptanoate-3-hydroxy-5-phenylvalerate), respectively. The mixture of 6-phenylhexanoic acid and 7-phenylheptanoic acid gave rise to the corresponding terpolymer, copoly(3-hydroxy-7-phenylheptanoate-3-hydroxy-6-phenylhexanoate-3-hydroxy-5-phenylvalerate). Studies on the chemical structure of these three polyesters revealed that they were true copolymers but not a mixture of homopolymers and that the different monomeric units were randomly incorporated in the macromolecular chains. Thermal behavior and molecular weight distribution were also discussed. These compounds had a dual attractive interest in function of (i) their broad use as biodegradable polymers and (ii) their possible biomedical applications.

Biocompatible Materials↗

PubMed2001

Incorporation of salicylic acid derivatives to hydrophilic copolymer systems with biomedical applications.

Hydrogels based on polymeric derivatives of salicylic acid have been prepared for biomedical applications by free radical copolymerization of 2-hydroxy-4-methacrylamidobenzoic acid, 4HMA, and 2-hydroxy-5-methacrylamidobenzoic acid, 5HMA, with 2- hydroxyethylmethacrylate, HEMA, in a wide range of compositions. The reactivity ratios of 4HMA and 5HMA with HEMA in radical copolymerization processes have been determined from their 1H NMR spectra by applying linearization methods and non-linear least square treatments. Tgs of the corresponding copolymers were analyzed by DSC. The swelling behavior in water of the prepared copolymers was studied in comparison to poly-(HEMA), poly-(4HMA) and poly-(5HMA) hydration degrees, being in all cases superior to 35%. The hydrolytical behavior of the synthesized copolymers was studied at three different pHs (2, 7.4 and 10) determining the release percentage of the salicylic acid derivatives, 4-amino salicylic acid, 4ASA, and 5-amino salicylic acid, 5ASA, analyzed by high performance liquid chromatography (HPLC). The release analysis was followed during 230 days and a pH dependence was observed obtaining the highest release percentages at pH=10, whereas at physiological pH (7.4) the release percentages were in range from 2 to 5% at that time for all copolymer systems. The hydrolytical stability is enough for long-term applications like bone cements, ionomers, etc.

Journal Article↗

PubMed2001

Genetically engineered Pseudomonas: a factory of new bioplastics with broad applications.

New bioplastics containing aromatic or mixtures of aliphatic and aromatic monomers have been obtained using genetically engineered strains of Pseudomonas putida. The mutation (-) or deletion (Delta) of some of the genes involved in the beta-oxidation pathway (fadA(-), fadB(-) Delta fadA or Delta fad BA mutants) elicits a strong intracellular accumulation of unusual homo- or co-polymers that dramatically alter the morphology of these bacteria, as more than 90% of the cytoplasm is occupied by these macromolecules. The introduction of a blockade in the beta-oxidation pathway, or in other related catabolic routes, has allowed the synthesis of polymers other than those accumulated in the wild type (with regard to both monomer size and relative percentage), the accumulation of certain intermediates that are rapidly catabolized in the wild type and the accumulation in the culture broths of end catabolites that, as in the case of phenylacetic acid, phenylbutyric acid, trans-cinnamic acid or their derivatives, have important medical or pharmaceutical applications (antitumoral, analgesic, radiopotentiators, chemopreventive or antihelmintic). Furthermore, using one of these polyesters (poly 3-hydroxy-6-phenylhexanoate), we obtained polymeric microspheres that could be used as drug vehicles.

Biodegradation, Environmental↗

PubMed2001

Porous starch-based drug delivery systems processed by a microwave route.

Abstract-A new simple processing route to produce starch-based porous materials was developed based on a microwave baking methodology. This innovative processing route was used to obtain non-loaded controls and loaded drug delivery carriers, incorporating a non-steroid anti-inflammatory agent. This bioactive agent was selected as model drug with expectations that the developed methodology might be used for other drugs and growth factors. The prepared systems were characterized by 1H and 13C NMR spectroscopy which allow the study of the interactions between the starch-based materials and the processing components, i.e, the blowing agents. The porosity of the prepared materials was estimated by measuring their apparent density and studied by comparing drug-loaded and non-loaded carriers. The behaviour of the porous structures, while immersed in aqueous media, was studied in terms of swelling and degradation, being intimately related to their porosity. Finally, in vitro drug release studies were performed showing a clear burst effect, followed by a slow controlled release of the drug over several days (up to 10 days).

Biocompatible Materials↗

PubMed2001

Integrated analysis for pre-sorting and waste collection schemes implemented in Spanish cities.

Over recent years, European cities have been questioning their traditional pre-sorting and waste collection practices and looking for new schemes to improve environmental problems generated by waste disposal. This paper presents an integral methodology for four pre-sorting practices that are beginning to be implemented in Spanish cities. A great effort has been made to compile information to be able to estimate a large number of valuation indexes. Based on this information, the methodology is supported by the forecasting of waste generation, the use of GIS techniques, the definition of objectives and their evaluation taking into account legal, social, performance, environmental and economic issues. Special attention is given to environmental impact, for which life cycle assessment methodology is used.

Cities↗

PubMed2000

Vinylpyrrolidone-N,N'-dimethylacrylamide water-soluble copolymers: synthesis, physical-chemical properties and proteic interactions.

The radical copolymerization of N-vinyl-2-pyrrolidone (NVP) with N,N'-dimethylacrylamide (DMAm) has been studied. The copolymer compositions were determined from 1H-NMR. The radical reactivity ratios for DMAm (M1) and VP (M2) were found to be r1 = 2.232 and r2 = 0.186. An analysis of the water vapor absorption isotherms as a function of the lactam content in the copolymer is reported. It was observed that the water vapor absorption decreases with increasing VP content in the copolymer and show anomalous diffusion behavior with increasing temperature due to the coupling of diffusion and polymer relaxation mechanisms. From the water vapor sorption data the Arrhenius activation parameter (ED) and enthalpy of sorption (deltaH S) were determined. The activation parameters are found to follow the conventional trend. The poly(DMAm-co-VP) copolymers exhibited a decreased critical solution temperature (LCST) in proportion to their lactam content. Contact angle data were evaluated for the determination of surface free energy components (gamma d SV, gamma P SV and gamma SV) of the synthesized polymers. The dispersion force component (gamma d SV) of copolymers increased only slightly with the VP content whereas the polar force component (gamma P SV) decreased with the lactam content. No dependence was observed between the surface free energy (gamma SV) and copolymer compositions. The complex formation between bovine serum albumin (BSA) and the VP-DMAm copolymers in water was studied by fluorescence spectroscopy. It was found that the copolymers bind to BSA non-specifically on the surface. Phase separation was not observed after addition of copolymers to BSA solutions at pH higher or lower than isoelectric point of BSA.

Acrylamides↗

PubMed2000

Controlled release of cyclosporine from VP-HEMA copolymer systems of adjustable resorption monitorized by MEKC.

Soluble, uncrosslinked and high molecular weight copolymers of vinylpyrrolidone, VP, with 2-hydroxyethyl methacrylate, HEMA, prepared by free radical copolymerization, are proposed as supports for the modulated release of drugs, taking cyclosporine as a model system. The copolymerization parameters described as reactivity ratios, rVP = 0.08 and rHEMA = 7.97, indicate that the copolymer systems prepared at high conversion have two main components with a microstructural arrangement which depends on the average composition, i.e., an initial HEMA-rich copolymer and a final PVP homopolymer or VP-rich copolymer. This microstructural distribution controls the resorption rate of the polymeric support and therefore the release process of cyclosporine which is demonstrated experimentally by the application of a modern technique known as micellar electrokinetic capillary chromatography (MEKC).

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2000

Recombinant growth hormone delivery systems based on vinylpyrrolidone-hydroxyethyl methacrylate copolymer matrices: monitoring optimization by capillary zone electrophoresis.

Experimental conditions for the fabrication of two new polymeric devices (i.e. films and slabs) useful for the controlled release of recombinant growth hormone (GH) are given. The release rate is controlled by the resorption profile of the vinylpyrrolidone-hydroxyethyl methacrylate (VP-HEMA) tested systems which is related to the copolymer composition. The suitability of capillary electrophoresis (CE) for following the complete preparation of the different VP-HEMA devices is shown. Moreover, CE allows simultaneous monitoring of the controlled release of GH and dissolved polymer during in vitro experiments. From these results, guidelines are given for the fabrication of polymeric devices containing protein as active drug as well as for the correct selection of conditions during in vitro experiments.

Biocompatible Materials↗

PubMed2000

HEMA-based methacrylic carriers incorporating ketoprofen: chain flexibility and swelling behaviour.

The chain flexibility, swelling and release behaviour of several copolymer systems of pharmacological interest have been studied. The systems are copolymers of 2-hydroxyethyl methacrylate with two support comonomers, i.e. N-(4-hydroxyphenyl) methacrylamide and N-[4-(2-hydroxy)ethoxyphenyl] methacrylamide and copolymers of 2-hydroxyethyl methacrylate with these carrier structures bearing ketoprofen (N-(4-[2-(3-benzoylphenyl)propionyloxy]phenyl methacrylamide and N-(4-[2-(3-benzoylphenyl)propionyloxy]2-ethoxyphenyl methacrylamide). In these copolymers ketoprofen was attached via different spacer groups, i.e. 4-aminophenoxy and 4-aminoethoxyphenyl. The chain structures are discussed on the basis of reactivity ratios. The properties of the polymeric drugs and of the parent carriers were studied comparatively by DSC and through the swelling of films from DMF solutions in pH 7.4 buffers. Data are discussed in terms of chain flexibility and swelling.

Drug Carriers↗

PubMed1999

Self-curing membranes of chitosan/PAA IPNs obtained by radical polymerization: preparation, characterization and interpolymer complexation.

Chitosan/polyacrylic acid I PN's were prepared by radical polymerization of acrylic acid, AA, activated at low temperature, in an aqueous/alcoholic chitosan dispersion. AA monomer to polymer conversion and membrane compositions were determined by elemental analysis and FTIR. Evidences of interpolyelectrolite complex formation were found from the FTIR spectra as well. The gravimetric measurements and the elemental analysis after some exhaustive PAA extraction support the existence of some PAA grafting on the reactive amine group of the chitosan. Swelling degree of the membranes is highly dependent on pH and composition, showing a higher swelling in membranes richer in AA and increased pH due to the breaking of interpolyelectrolite salt bonds.

Acrylic Resins↗