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Results for “Biodegradation”

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At least 1,117 records · Page 62Linked to original sources

PubMed1994

Induction of specific IgA responses in rats after oral vaccination with biodegradable microspheres containing a recombinant protein.

Diseases which affect mucosal surfaces cause considerable mortality and morbidity. New vaccine technologies are now available which justify a reappraisal of oral delivery not only for infectious disease control but also to control mucosal physiological processes such as fertility. Biodegradable microspheres have been investigated for their use as an oral delivery vehicle in rats using a recombinant antigen derived from fox sperm. Unencapsulated antigen administered in saline by the oral route produced a negligible response although an improved response was obtained if administered directly into the duodenum. This response was considerably enhanced if Peyer's patch (PP) priming was performed by direct injection of antigen in Freund's complete adjuvant (FCA) prior to intraduodenal (ID) delivery. In contrast, microencapsulated antigen given orally produced a substantial response, which was predominantly IgA specific, and almost equal in magnitude to that obtained by PP priming and ID boosting with native antigen. Direct ID delivery produced a similar response but when PP were primed with microencapsulated antigen in FCA the response to ID boosting was greater than with any of the other protocols investigated. These data demonstrate the efficacy of biodegradable microspheres in producing an IgA antibody response following oral vaccination.

Administration, Oral↗

PubMed1990

The influence of bacterial contaminations on the biodegradation of PLA implants.

Metal implants employed in orthopaedic surgery have certain disadvantages. Intensive research work is therefore being done in the field of biodegradable implants, the behavior of which in the case of possible contamination or infection at the operation site has not yet been studied. In-vitro experiments on PLA-test bodies were performed to clarify the influence of bacteria on the polymer degradation. The investigated parameters were germ growth, course of the pH-value of the culture media, bending stiffness of the PLA-test bodies and the decrease in their molecular weight. The experiments performed did not demonstrate an accelerated degradation of PLA specimen in vitro incubated in different bacterial contaminated media. Therefore bacterial contamination may possibly not lead to a premature collapse of the PLA used in connection with fracture treatment by biodegradable osteosynthesis implants.

Bacterial Infections↗

PubMed1992

Biodegradable implants in orthopaedic surgery--a review on the state-of-the-art.

Until recently, internal fixation of fractured bones and joints has been managed by metal implants. Certain disadvantages of the metal implants are: the properties of the materials are stiffer than those of cortical bone and removal of the implants requires a second operation. About 40 different biodegradable polymers, copolymers and composites have been developed in order to substitute the metal implants for internal fracture fixation. First experimental and clinical results demonstrate the limitations of these new methods. The main problem of the material is the loss of mechanical strength within a time interval not long enough to guarantee bone healing. The development of sterile sinus at the site of implantation is also a problem reported by various groups. Despite some drawbacks, there are indications for the isolated or the adjuvant implantation of biodegradable materials.

Biocompatible Materials↗

PubMed1985

Toxicity, biodegradability, and accumulation of a number of Cl/N-containing compounds for classification and establishing water quality criteria.

The evaluation of the ecotoxicity of chemical compounds is often hampered by the scarcity of the literature data on toxicity, biodegradability, and accumulation. In this study additional data on 16 Cl/N-containing organic compounds were gathered by laboratory experiments. For assignment to so-called gray or black lists, two different classification schemes were used. According to both schemes 3-nitrotoluene, 1,2- and 1,3-dichlorobenzene, the 1-chloro-nitrobenzenes, 2,3-dichloronitrobenzene, 2-chloroaniline, and 2-chloro-4-nitroaniline were marked as black list substances, primarily based on poor biodegradability; 2- and 4-nitrotoluene, nitrobenzene, and 2-methoxyaniline were classified as gray list substances. For 3- and 4-methoxyaniline and 1,4-dichlorobenzene no agreement in classification was obtained. Additionally, water quality criteria are proposed for 2-, 3-, and 4-nitrotoluene and nitrobenzene, based on long-term toxicity data: respectively 0.3, 0.2, 0.4, and 1.0 mg/liter.

Animals↗

PubMed1995

Comparison of high-performance liquid chromatography and capillary zone electrophoresis in penciclovir biodegradation kinetic studies.

High-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE) were used in biodegradation kinetic studies. This paper describes a rapid penciclovir separation using CZE with detection limits comparable to HPLC. The ionic-strength mediated stacking technique was employed while good resolution was maintained. With a shorter analysis time, comparable detection limits and no organic solvent consumption, CZE is a better method for penciclovir biodegradation studies than conventional reversed-phase HPLC (RP-HPLC).

Acyclovir↗

PubMed1995

Arthroscopic fixation of superior labral lesions using a biodegradable implant: a preliminary report.

Twenty-two patients were treated for symptomatic lesions of the superior glenoid labrum in association with instability of the tendinous insertion of the long head of the biceps brachii. A biodegradable implant was used to fix the labrum to the bony glenoid using an arthroscopic technique. At 2-year average follow-up, satisfactory results were obtained in 86% of the patients. Two patients, both of whom had undergone concomitant subacromial decompression, continued to complain of pain after the procedure; 3 patients had restricted motion postoperatively, and 1 required manipulation under anesthesia. Twelve of 13 overhead athletes were able to return to full premorbid function. Arthroscopic fixation of unstable lesions of the superior labrum led to a resolution of symptoms in the majority of patients. There were no complications related to the use of the biodegradable implant.

Adolescent↗

PubMed2004

Prospective randomized study evaluating a biodegradable polymeric sealant for sealing intraoperative air leaks that occur during pulmonary resection.

BACKGROUND: To evaluate the safety and effectiveness of a new biodegradable polymeric sealant to close intraoperative air leaks after pulmonary resection. METHODS: In a multicenter prospective randomized trial, 161 patients with a median age of 67 years old (range 18-85 years old), were randomized in a 2:1 ratio to receive sealant or control for at least one significant air leak (> or = 2.0 mm in size) after pulmonary resection. In the sealant group, all significant air leaks underwent attempted repair by standard methods (sutures, staples, or cautery) prior to the application of sealant. The control group underwent only standard methods. Blood was analyzed for immunologic response. Patients were followed up 1 month after surgery. RESULTS: Intraoperative air leaks were sealed in 77% of the sealant group compared with 16% in the control group (p < 0.001). The sealant group had significantly fewer patients with postoperative air leaks compared with the control group (65% vs 86%, p = 0.005). Median length of hospitalization was 6 days (range, 3-23 days) for the sealant group compared with 7 days (range 4-38 days) for controls (p = 0.028). There was no difference in mortality, morbidity, duration of chest tubes, or immune responses between the two groups. CONCLUSIONS: This study demonstrates the effectiveness of a biodegradable polymer when used as an adjunct to standard closure methods for sealing significant intraoperative air leaks that develop from pulmonary surgery. Use of the sealant led to a reduction in postoperative air leaks, which may have decreased the length of hospitalization.

Adolescent↗

PubMed2004

Mutual influence of cholesterol esterase and pseudocholinesterase on the biodegradation of dental composites.

It has been demonstrated that human saliva contains cholesterol esterase (CE)- and pseudocholinesterase (PCE)-like hydrolase activities. While PCE has been shown to preferentially degrade triethylene glycol dimethacrylate (TEGDMA) and its derivatives, CE has a greater catalytic effect on the breakdown of bis-phenol-A-diglycidyl dimethacrylate (bisGMA) components in composite dental resins. The current study seeks to determine if there is a mutual influence between the different esterases with respect to the biodegradation of resin composite. Photopolymerized model composite resin samples (containing 60% by weight fraction of silanated barium glass filler) based on bisGMA/TEGDMA (bis) or urethane-modified bisGMA/TEGDMA/bisEMA (ubis) monomers were incubated in buffer, CE and/or PCE solutions (pH=7.0, 37 degrees C) for 8 and 16 days. The incubation solutions were analyzed for degradation products using high-performance liquid chromatography, UV spectroscopy and mass spectrometry. In the bis system, higher amounts (p<0.05) of a bisGMA derived product, bishydroxy-propoxyphenyl-propane (bisHPPP), were detected in the combined enzyme group as compared to the sum of the two individual enzyme groups. In the ubis system, similar comparisons showed that higher levels (p<0.05) of bisHPPP were detected in the combined group at 8 days while higher amounts (p<0.05) of a bisEMA derived product, ethoxylated bis-phenol A, were detected in the combined group at 16 days. The study concluded that CE and PCE act synergistically to increase the biodegradation of both composite resin materials.

Acrylic Resins↗

PubMed2004

Novel biodegradable electrospun membrane: scaffold for tissue engineering.

Nonwoven fibrous matrixes have been widely used as scaffolds in tissue engineering, and modification of microstructure of these matrices is needed to organize cells in three-dimensional space with spatially balanced proliferation and differentiation required for functional tissue development. The objective of this study was fabrication of nanofibrous matrix from novel biodegradable poly(p-dioxanone-co-L-lactide)-block-poly(ethylene glycol) (PPDO/PLLA-b-PEG) copolymer, and to examine cell proliferation, morphology of cell-matrix interaction with the electrospun nanofibrous matrix. The electrospun structure composed of PPDO/PLLA-b-PEG fibers with an average diameters of 380 nm, median pore size 8 microm, porosity more than 80% and mechanical strength 1.4 MPa, is favorable for cell-matrix interaction and supports the active biocompatibility of the structure. NIH 3T3 fibroblast cell seeded on the structure tend to maintain phenotypic shape and guided growth according to nanofiber orientation. Good capability of the nanofibrous structure for supporting the cell attachment and proliferation are observed. This novel biodegradable scaffold will be applicable for tissue engineering based upon its unique architecture, which acts to support and guide cell growth.

3T3 Cells↗

PubMed2005

Electrospun dual-porosity structure and biodegradation morphology of Montmorillonite reinforced PLLA nanocomposite scaffolds.

Combining a nanocomposite technique and the electrospinning process, a robust dual-porosity scaffold structure was developed for a facile transport of metabolic nutrients and wastes through the nano-sized pores and for the cell implantation and blood vessel invasion through the micro-sized pores. The montmorillonite (MMT) nano-sized platelets were incorporated into poly(L-lactic acid) (PLLA) solution, which was subsequently electrospun and mechanically entangled by a cold compression molding process for a robust 3-dimensional scaffold structure. Using a salt leaching/gas forming method, micro-sized pores were developed in the electrospun fiber bundles giving a dual-porosity scaffold structure. Compared with the pristine PLLA scaffold, the developed nanocomposite fibrous scaffold structure exhibited increased strength and improved structural integrity during the biodegradation process. The nanocomposite scaffold systems also exhibited many tiny pinholes desirably generated on the scaffold walls without serious fragmentation during biodegradation reactions.

Bentonite↗

PubMed2005

Influence of anionic monomer content on the biodegradation and toxicity of polyvinyl-urethane carbonate-ceramic interpenetrating phase composites.

The objective of this study was to characterize a series of anionic biodegradable polymer resins for their compatibility in a biological environment, comparing them with respect to the influence of ionic function on enzyme catalyzed biodegradation when the polymers were incorporated into a porous calcium polyphosphate (CPP) 3-D structure to form an interpenetrating phase composite (IPC). The swelling behavior of the polymers was investigated by immersing the cured polymer resins in growth media at 37 degrees C. In vitro cytotoxicity of the polymer resins was assessed using a HeLa cell line. Cell viability increased when the amount of low molecular weight monomer was minimized. Despite observing that the addition of carboxylic acid groups into the polymer resin chains contributed to an improvement of the chemical bonding between the polymer and the CPP, the addition of high ionic content into the resin led to the greatest loss of bending strength for the samples incubated in phosphate buffer and cholesterol esterase enzyme solutions, when compared to their as made state. The increased degradation for the higher ionic component materials and their loss of physical strength was attributed to enhanced hydrolysis within the materials and by water transport deep within the composites, via the anionic components of the resin. The findings indicated that the introduction of anionic content must be optimized to promote increased mechanical performance for the CPP, balancing the features of polymer CPP bonding versus polymer swelling and cytotoxicity.

Anions↗

PubMed2005

Synthesis and evaluation of poly(diol citrate) biodegradable elastomers.

Herein, we report the synthesis and evaluation of a novel family of biodegradable and elastomeric polyesters, poly(diol citrates). Poly(diol citrates) were synthesized by reacting citric acid with various diols to form a covalent cross-linked network via a polycondensation reaction without using exogenous catalysts. The tensile strength of poly(diol citrates) were as high as 11.15+/-2.62 MPa and Young's modulus ranged from 1.60+/-0.05 to 13.98+/-3.05 MPa under the synthesis conditions that were investigated. Elongation was as high as 502+/-16%. No permanent deformation was found during mechanical tests. The equilibrium water-in-air contact angles of measured poly(diol citrates) films ranged from 15 degrees to 53 degrees . The mechanical properties, degradation and surface characteristics of poly(diol citrates) could be controlled by choosing different diols as well as by controlling the cross-link density of the polyester network. Various types of poly(diol citrate) scaffolds were fabricated to demonstrate their processing potential. These scaffolds were soft and could recover from deformation. In vitro and in vivo evaluation using cell culture and subcutaneous implantation, respectively, confirmed cell and tissue compatibility. The introduction of poly(diol citrates) will expand the repertoire of currently available biodegradable polymeric elastomers and should help meet the requirements of tissue engineering applications.

Animals↗

PubMed2005

The mechanical properties and in vitro biodegradation and biocompatibility of UV-treated poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

Strong mechanical properties and controllable biodegradability, together with biocompatibility, are the important requirement for the development of medical implant materials. In this study, an ultraviolet (UV) radiation method was developed to achieve controlled degradation for bacterial biopolyester poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) which has a low biodegradation rate that limits its application for many implant applications required quick degradation. When UV radiation was applied directly to PHBHHx powder, significant molecular weight (Mw) losses were observed with the powder, Mw reduction depended on the UV radiation time. At the same time, a broad PHBHHx Mw distribution was the result of inhomogeneous radiation. Interestingly, this inhomogeneous radiation helped maintain the mechanical properties of films made of the UV-radiated powder. In comparison, the PHBHHx films subjected to direct UV radiation became very brittle although their degradation was faster than that of the PHBHHx powders subjected to direct UV radiation. After 15 weeks of degradation in simulated body fluid (SBF), films prepared from 8 and 16h UV-treated PHBHHx powders maintained 92% and 87% of their original weights, respectively, while the untreated PHBHHx films lost only 1% of its weight. Significant increases in growth of fibroblast L929 were observed on films prepared from UV-radiated powders. This improved biocompatibility could be attributed to increasing hydrophilic functional groups generated by increasing polar groups C-O and CO. In general, UV-treated PHBHHx powder had a broad Mw distribution, which contributed to fast degradation due to dissolution of low Mw polymer fragments, and strong mechanical property due to high Mw polymer chains. Combined with its improved biocompatibility, PHBHHx is one more step close to become a biomedical implant material.

3-Hydroxybutyric Acid↗

PubMed2006

Evaluation of the osteogenesis and biodegradation of porous biphasic ceramic in the human spine.

The histological reports on porous biphasic calcium phosphate ceramic (PBC) in human spine are limited. The osteogenesis and biodegradation of PBC are insufficiently known in human. In present study, the undecalcified histological study was carried out on 20 samples retrieved from posterior spinal fusion in order to reveal the osteogenesis and biodegradation of the PBC in human spine. The quantitative study was performed in 14 samples with sufficient size. Newly formed bone was found in all the samples. More new bone was formed in those samples closely in contact with autogenous bone. The PBC degradation particles were present both in the macrophages and around the tissue. However, those phenomena were highly variable among the samples. New bone formation increased with time and decreased with age. The PBC degradation decreased with age, but it did not differ greatly with time. New bone formation was higher and the residual material was lower in the fusion group than that in non-fusion group. The PBC is a kind of osteoconductive material and do not transform into new bone after a relatively long time. The PBC should be well mixed with the autogenous bone in order to achieve high new bone colonization. The PBC degradation particles and related active phagocytotic activity have been noted.

Absorbable Implants↗

PubMed2006

In vitro biodegradation of three brushite calcium phosphate cements by a macrophage cell-line.

Depending upon local conditions, brushite (CaHPO4 x 2 H2O) cements may be largely resorbed or (following hydrolysis to hydroxyapatite) remain stable in vivo. To determine which factors influence cement resorption, previous studies have investigated the solution-driven degradation of brushite cements in vitro in the absence of any cells. However, the mechanism of cell-mediated biodegradation of the brushite cement is still unknown. The aim of the current study was to observe the cell-mediated biodegradation of brushite cement formulations in vitro. The cements were aged in the presence of a murine cell line (RAW264.7), which had the potential to form osteoclasts in the presence of the receptor for nuclear factor kappa B ligand (RANKL) in vitro, independently of macrophage colony stimulating factor (M-CSF). The cytotoxicity of the cements on RAW264.7 cells and the calcium and phosphate released from materials to the culture media were analysed. Scanning electron microscopy (SEM) and focused ion beam (FIB) microscopy were used to characterise the ultrastructure of the cells. The results showed that the RAW264.7 cell line formed multinucleated TRAP positive osteoclast-like cells, capable of ruffled border formation and lacunar resorption on the brushite calcium phosphate cement in vitro. In the osteoclast-like cell cultures, ultrastructural analysis by SEM revealed phenotypic characteristics of osteoclasts including formation of a sealing zone and ruffled border. Penetration of the surface of the cement, was demonstrated using FIB, and this showed the potential demineralising effect of the cells on the cements. This study has set up a useful model to investigate the cell-mediated cement degradation in vitro.

Animals↗

PubMed2004

Production of biodegradable plastics from activated sludge generated from a food processing industrial wastewater treatment plant.

Most of the excess sludge from a wastewater treatment plant (60%) is disposed by landfill. As a resource utilization of excess sludge, the production of biodegradable plastics using the sludge has been proposed. Storage polymers in bacterial cells can be extracted and used as biodegradable plastics. However, widespread applications have been limited by high production cost. In the present study, activated sludge bacteria in a conventional wastewater treatment system were induced, by controlling the carbon: nitrogen ratio to accumulate storage polymers. Polymer yield increased to a maximum 33% of biomass (w/w) when the C/N ratio was increased from 24 to 144, where as specific growth yield decreased with increasing C/N ratio. The conditions which are required for the maximum polymer accumulation were optimized and are discussed.

Bacteria↗

PubMed2005

Biodegradation of octylphenol polyethoxylate surfactant Triton X-100 by selected microorganisms.

Octylphenol polyethoxylate (OPEO(n)) surfactants are used in numerous commercial and industrial products. Large amounts of such surfactants and their various residual biodegradation by-products are ultimately released into the environment. OPEO(n) biodegradation was performed in this study using pure cultures of Pseudomonas species and strains under different environmental conditions. Environmental factors including the pH, nitrogen sources, and growth kinetics of the cells were investigated. The intermediates of Triton X-100 biotransformation were detected by high performance liquid chromatography-mass spectrophotograph (HPLC-MS). We found the highest specific growth rate (mu) was 0.56 h(-1) and this was achieved by strain E with an initial concentration of Triton X-100 of 5000 mg L(-1). A pH level of 7 was most favorable for cell growth for all five strains. The highest specific growth rate was achieved using (NH(4))(2)SO(4) as the sole nitrogen source for strain E. Strain A showed an enhancement of growth when between 0.2 and 1.4 mg L(-1) of H(2)O(2) was added. Detection of intermediates was possible after four days of transformation and the octylphenol triethoxylate (OPEO(3)) peak was predominant, while the high molecular weight peaks had all disappeared. The kinetic analysis demonstrated that the greatest maximum specific growth rate (mu(max)) and the greatest saturation constant (K(s)) of 0.83 h(-1) and 5.24 mg L(-1), respectively, were obtained for strain E in 5000 mg L(-1) Triton X-100. The higher K(i) revealed that strain A was resistant to higher Triton X-100 concentrations.

Base Sequence↗

PubMed2005

Decolorisation, biodegradation and detoxification of benzidine based azo dye.

The present study deals with the decolorisation, biodegradation and detoxification of Direct Black-38, a benzidine based azo dye, by a mixed microbial culture isolated from an aerobic bioreactor treating textile wastewater. The studies revealed a biotransformation of Direct Black-38 into benzidine and 4-aminobiphenyl followed by complete decolorisation and biodegradation of these toxic intermediates. From cytotoxicity studies, it was concluded that detoxification of the dye took place after degradation of the toxic intermediates by the culture.

Adsorption↗