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At least 451 records · Page 25Linked to original sources

PubMed1997

High-energy transurethral microwave thermotherapy for large severely obstructing prostates and the use of biodegradable stents to avoid catheterization after treatment.

OBJECTIVE: To assess the use of high-energy transurethral microwave thermotherapy (TUMT) for large severely obstructing benign prostatic hyperplasia (BPH) and to compare the use of a biodegradable stent with that of a urethral Foley catheter after TUMT. PATIENTS AND METHODS: The study comprised 30 men (mean age 71 years, range 49-82) scheduled for prostatectomy for symptomatic BPH. Pre-operative investigations included the measurement of urinary free flow rate, residual urine volume (ultrasonographically), a digital rectal examination, transrectal ultrasonography, a symptom score, cystoscopy, cystometry and pressure-flow. The obstruction was graded according to the Schäfer nomogram. The patients were treated using the Prostatron (EDAP-Technorned, France) TUMT system; the software used provided a maximum power of 70 W. Patients were catheterised after treatment with either a Foley catheter or a biodegradable stent. After 3 months, the measurements and obstruction grading were repeated, and the effect of the stent assessed. RESULTS: In the entire group, the mean (SD) free flow increased from 7.7 (2.4) to 14.0 (3.3) mL/s, the residual urine decreased from 125 (86) to 23 (25) mL and the symptom score decreased from 16 (8) to 5 (4). The mean (SD) degree of obstruction decreased from 81.0 (16) to 62.6 (15). The biodegradable stent completely avoided post-treatment retention. CONCLUSION: High-energy TUMT can be used on large severely obstructing prostates with major subjective and objective improvements. The biodegradable stent is useful in relieving the problems of catheterization after treatment.

Aged↗

PubMed1997

Biodegradable scleral implant for intravitreal controlled release of fluconazole.

PURPOSE: To evaluate the feasibility of using a biodegradable polymeric scleral implant containing fluconazole (FLCZ), a bis-triazole antifungal agent, as a potential intravitreal-controlled drug delivery system. METHODS: The scleral implants, loaded with 10, 20, 30, and 50% FLCZ, were prepared with biodegradable polymers of poly (DL-lactide-co-glycolide). Those with all loading doses were used for the in vitro release studies; those with 30% FLCZ were used for the intravitreal release studies in pigmented rabbits. The in vitro and in vivo release rates of FLCZ from the implants were measured periodically with spectrophotometry and high performance liquid chromatography, respectively. The effects of the implants on ocular tissues were evaluated ophthalmoscopically, histologically, and electrophysiologically. RESULTS: The scleral implants loaded with 10, 20, and 30% doses gradually released FLCZ over 4 weeks in vitro; those with 50% FLCZ released most of the drug in one week. FLCZ concentration in the rabbit vitreous remained within the 99% inhibitory concentration for Candida albicans for 3 weeks after implantation. The scleral implant gradually biodegraded, and it disappeared by 4 months after implantation. The electrophysiologic and histopathologic findings demonstrated no substantial toxic reactions in the ocular tissues. CONCLUSION: The current study suggests that a biodegradable, polymeric scleral implant containing FLCZ may be a promising intravitreal drug delivery system to treat fungal endophthalmitis.

Animals↗

PubMed2005

Respirometry for assessing the biodegradation of petroleum hydrocarbons.

The respiration method using the Micro-Oxymax respirometer was applied to evaluate the bioremediation potential of hydrocarbon-contaminated soils in two biopiles at the oil refinery in Czechowice-Dziedzice, Poland. In biopiles 1 and 2, two different technologies, i.e., enhanced (engineered) bioremediation and monitored natural attenuation (MNA) were used, respectively. In biopiles 1 and 2, the bioremediation process lasted 6 years and 8 months, respectively. The biodegradation of petroleum hydrocarbons was evaluated on the basis of CO2 production and O2 uptake. The CO2 production and O2 consumption rates during hydrocarbon biodegradation were calculated from the slopes of cumulative curve linear regressions. The results confirmed the hydrocarbon biodegradation process in both biopiles. However, in biopile 2 the process was more effective compared to biopile 1. In biopile 2, the O2 consumption and CO2 production means were 3.37 and 2.4 milliliters per kilogram of soil (dry weight) per minute, respectively. Whereas, in biopile 1, the O2 consumption and CO2 production means were 1.52 and 1.07 milliliters per kilogram of soil (dry weight) per minute, respectively. The mean biodegradation rate for biopile 2 was two times higher--67 mg hydrocarbons kg d.w.(-1)day(-1) compared with biopile 1, where the mean was 30 mg hydrocarbons kg d.w.(-1)day(-l). The results were correlated with petroleum hydrocarbon concentrations and microbial activity measured by dehydrogenase assay.

Biodegradation, Environmental↗

PubMed1992

A rapid in situ respiration test for measuring aerobic biodegradation rates of hydrocarbons in soil.

An in situ test method to measure the aerobic biodegradation rates of hydrocarbons in contaminated soil is presented. The test method provides an initial assessment of bioventing as a remediation technology for hydrocarbon-contaminated soil. The in situ respiration test consists of ventilating the contaminated soil of the unsaturated zone with air and periodically monitoring the depletion of oxygen (O2) and production of carbon dioxide (CO2) over time after the air is turned off. The test is simple to implement and generally takes about four to five days to complete. The test was applied at eight hydrocarbon-contaminated sites of different geological and climatic conditions. These sites were contaminated with petroleum products or petroleum fuels, except for two sites where the contaminants were primarily polycyclic aromatic hydrocarbons. Oxygen utilization rates for the eight sites ranged from 0.02 to 0.99 percent O2/hour. Estimated biodegradation rates ranged from 0.4 to 19 mg/kg of soil/day. These rates were similar to the biodegradation rates obtained from field and pilot studies using mass balance methods. Estimated biodegradation rates based on O2 utilization were generally more reliable (especially for alkaline soils) than rates based on CO2 production. CO2 produced from microbial respiration was probably converted to carbonate under alkaline conditions.

Aerobiosis↗

PubMed2006

Microbially treated peat-cellulose fabric as a biodegradable oil-collection cloth.

The aim of this work was to study the use of a fully biodegradable peat-cellulose fabric as a first aid in collecting and removing spilled oil. The fabric itself was made from entirely biodegradable natural components. Another aspect investigated was whether drying microbial suspension--specifically enriched for the degradation of oil hydrocarbons while maintaining a high survival rate and rapid initial growth--to the fabric would improve the degradation of absorbed oil along with the fabric. The results show that the oil absorption capacity of the biodegradable fabric was comparable to commercial products, and that the oil absorbed to the fabric degraded readily when incubated at various conditions. The microbial inoculum enhanced the degradation rate to some degree in sand, but in garden soil no significant difference existed. It was concluded that an oily fabric can be disposed of by biodegradation, e.g., by composting, but that a microbial inoculum is not essential for this purpose.

Absorption↗

PubMed2007

Influence of nutrient level on biodegradation and bioconcentration of phthalate acid esters in Chlorella vulgaris.

Influences of major nutrients (N, P) on the biodegradation and bioconcentration of dibutyl phthalate (DBP) and di-2-ethylexyl phthalate (DEHP) by Chlorella vulgaris in lake water were investigated in this work. Our study demonstrated that nutrient addition obviously influenced biodegradation rate constants and apparent bioconcentration factors (BCFs) of DBP and DEHP in Chlorella vulgaris. The effects of P addition on biodegradation were less pronounced than the effects of N addition as a result of N-limitation status of phytoplankton in the lake water, while addition of both N and P more greatly affected biodegradation than addition of N or P. BCFs of DBP and DEHP decreased with increasing algal exudate as measured by dissolved organic carbon (DOC) and a strong correlation between BCFs and DOC was obtained. The results indicate that DOC plays an important role in the bioconcentration of DBP and DEHP.

Biodegradation, Environmental↗

PubMed2004

Effects of photocatalysis on the biodegradability of Cibacron Brilliant Yellow 3G-P (reactive yellow 2).

In this study, the biodegradability of an untreated and photocatalytically treated solution containing Cibacron Brilliant Yellow 3G-P was examined. Both untreated and partially treated dyes by photocatalysis were used in the biological treatment process. Respirometric measurements indicated that the untreated dye was not inhibitory to biological treatment at the concentration of 100 mg/L. In addition, no significant biodegradation of both untreated and photocatalytically pre-treated dye occurred by either respirometric or conventional BOD tests using activated sludge. Respirometric measurements also suggested that both untreated and treated dye solutions were not biodegradable even with synthetic sewage. Under aerobic condition, partially treated dye solution showed better color removal rate than that of untreated solution. However, biodegradability of the 100 mg/L untreated dye solution was improved by 50% in terms of Oxygen Uptake Rate (OUR) in respirometry by using acclimated sludge.

Azo Compounds↗

PubMed2004

Treatment and biodegradation kinetics of microbially treated domestic wastewater sludge.

A laboratory-scale study was undertaken to evaluate the liquid state bioconversion (LSB) in terms of biodegradation of microbially treated domestic wastewater sludge (biosolids) as well as its kinetics. The potential fungal strains and process factors developed from previous studies were used throughout the study. The results presented in this study showed that an effective biodegradation occurred with the biosolids (sludge cake) accumulated. The maximum biosolids (sludge cake) accumulated (93.8 g/kg of liquid sludge) enriched with the biomass protein (30.2 g/kg of dry biosolids), was achieved which improved the effluent quality by enhancing the removal of chemical oxygen demand (COD), reducing sugar (RS), soluble protein (SP), total dissolved solids (TDS), and total suspended solids (TSS). The higher reduction of specific resistance to filtration (SRF) was observed during bioconversion process. The kinetics results showed that the experimental data were better fitted for the biodegradation efficiency, and biosolids accumulation and biodegradation rate.

Biodegradation, Environmental↗

PubMed2000

The future of biodegradable osteosyntheses.

In the last 3 decades, much progress has been made in the development of biodegradable osteosyntheses. Despite this progress, these materials are still only used in small numbers, and the scope of their application has been limited. The limitations of biodegradable osteosyntheses mainly are related to problems with their mechanical properties and, in particular, biocompatibility. These problems need to be solved so that biodegradable osteosyntheses can perform up to their full potential and thus, eventually, make their general clinical application routine. This paper presents a historical perspective on the development of biodegradable osteosyntheses, discusses the successful developmental achievements and the still-existing problems, and gives a perspective on their future development.

Animals↗

PubMed1998

Spatially controlled cell engineering on biodegradable polymer surfaces.

Controlling receptor-mediated interactions between cells and template surfaces is a central principle in many tissue engineering procedures (1-3). Biomaterial surfaces engineered to present cell adhesion ligands undergo integrin-mediated molecular interactions with cells (1, 4, 5), stimulating cell spreading, and differentiation (6-8). This provides a mechanism for mimicking natural cell-to-matrix interactions. Further sophistication in the control of cell interactions can be achieved by fabricating surfaces on which the spatial distribution of ligands is restricted to micron-scale pattern features (9-14). Patterning technology promises to facilitate spatially controlled tissue engineering with applications in the regeneration of highly organized tissues. These new applications require the formation of ligand patterns on biocompatible and biodegradable templates, which control tissue regeneration processes, before removal by metabolism. We have developed a method of generating micron-scale patterns of any biotinylated ligand on the surface of a biodegradable block copolymer, polylactide-poly(ethylene glycol). The technique achieves control of biomolecule deposition with nanometer precision. Spatial control over cell development has been observed when using these templates to culture bovine aortic endothelial cells and PC12 nerve cells. Furthermore, neurite extension on the biodegradable polymer surface is directed by pattern features composed of peptides containing the IKVAV sequence (15, 16), suggesting that directional control over nerve regeneration on biodegradable biomaterials can be achieved.

Animals↗

PubMed1992

Use of biodegradable plates and screws in a rabbit model.

During the last decade, rigid internal fixation with miniplates and screws has gained widespread acceptance in the correction of both congenital and acquired craniomaxillofacial deformities. Recent studies have proposed that the currently employed metallic plates and screws may require removal because of potential facial growth restriction in growing children. Others have reported bone resorption under the plate due to stress shielding, infection, extrusion, and palpability in regions where there is minimal tissue coverage. Because these implants are radiopaque, they generate significant that interfere with radiological studies and with radiation therapy in patients undergoing treatment for malignancies. There is no question that the use of a biodegradable plating system would eliminate each of these potential or real problems, because stability is necessary only for a reasonably short period until the fracture segments have become united. We report the initial phase of a long-term study examining various materials that will be available for fabrication of a biodegradable plate and screw system. We evaluated a commercially developed biodegradable plate and screw system to treat zygomatic arch fractures in a rabbit model. Fractures were surgically created at the midpoint of each zygomatic arch. The experimental animals were then divided into three equal groups. Fractures in the first group were permitted to heal without any form of stabilization. In the second group, segments were secured with standard titanium plates and screws. Biodegradable plates and screws were employed for stabilization in the experimental group. Animals were then killed, and radiographs were obtained at 2, 4, 6, and 8 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Cell transplantation of genetically altered cells on biodegradable polymer scaffolds in syngeneic rats.

Many severe metabolic deficiencies in children are caused by a single gene defect with a resultant single gene product deficiency. These diseases may be amenable to permanent cure using new techniques of gene transfer and cell transplantation. In many in vivo models of retroviral mediated gene therapy, a significant limiting factor is the ability to transplant a sufficient number of modified cells. To potentially circumvent this problem, we have developed a biodegradable polymer implant system capable of supporting large numbers of genetically modified cells. In this study, we inserted a reporter gene into syngeneic cultured normal fibroblasts and then transplanted these genetically modified cells into animals using synthetic biodegradable polymer fibers as temporary cell delivery scaffolds. To begin to develop a system capable of delivering desirable proteins secreted by genetically modified cells, Fischer 344 adult rat fibroblasts were transduced in tissue culture with a retrovirus containing the reporter gene Lac Z. These genetically modified cells (1.1 x 10(7) cells/graft) were then attached to the biodegradable polymer fibers and the polymer-cell graft was transplanted subdermally into syngeneic recipients (n = 9). There was persistence of the modified cells with expression of the reporter gene for at least 30 days. The estimated number of genetically modified cells per implanted graft decreased from a pretransplant value of 1.1 +/- 0.6 x 10(7) to 3.2 +/- 0.7 x 10(6) by 15 days after transplantation (P < 0.01). Thereafter, the cell number did not vary significantly to the conclusion of the study at day 30 (3.6 +/- 1.0 x 10(6) cells/graft). Evidence of ingrowth and incorporation of other stromal elements was present in the graft by 1 week post-transplantation, as judged by counterstained hematoxylin and eosin micrograph sections. Migration of modified cells to areas outside of the polymer-cell graft was not detected. Over the course of the study, there was little degradation of the polymer implant, although by day 30, evidence of early dissolution was evident. The number of polymer fibers per high power field increased slightly from 62.5 +/- 5.8 on day 1 to 77.3 +/- 26.6 on day 30 (P > 0.2). These data suggest that the use of biodegradable polymer fibers may permit the transplantation of genetically modified cells in sufficient numbers to deliver a therapeutically useful product. Polymer matrices allow for the attachment and site-specific transplantation of genetically modified cells.

Animals↗

PubMed2005

Cavernous nerve reconstruction with a biodegradable conduit graft and collagen sponge in the rat.

PURPOSE: We investigated the efficacy of a biodegradable conduit graft for axonal regeneration of the injured cavernous nerve in a rat model. MATERIALS AND METHODS: Bilateral cavernous nerves were resected in 8-week-old Sprague-Dawley rats. We interposed a nerve gap with a 4 mm poly L-lactic acid and E-caprolactone copolymer conduit. The 56 rats were divided into 4 groups, namely group 1-biodegradable conduit alone, group 2-biodegradable conduit plus collagen sponge, group 3-sham operation as a positive control and group 4-unconnected conduit as a negative control. RESULTS: Immunohistochemical study revealed that neuronal nitric oxide synthase positive nerve fibers significantly increased in all rats in the conduit graft groups at 3 months. In a retrograde tracing study with FluoroGold (Fluorochrome, Englewood, Colorado) at 3 months the conduit plus collagen group showed a significant increase in FluoroGold positive cells in major pelvic ganglia. Intracavernous pressure elicited by medial preoptic area stimulation significantly increased in all rats in the conduit graft groups, especially in the conduit plus collagen group. CONCLUSIONS: This study suggests that a biodegradable conduit is effective for axonal regeneration of the injured cavernous nerve. Moreover, a conduit with a collagen sponge facilitates axonal sprouting and re-projection to its target organ, and ensures functional recovery.

Absorbable Implants↗

PubMed1995

Rapid screening for bacterial phenotypes capable of biodegrading anionic surfactants: development and validation of a microtitre plate method.

The Biolog microtitre plate assay, which is based on tetrazolium dye reduction as an indicator of sole-carbon-source utilization, has been evaluated as a rapid method to investigate the biodegradation of five classes of anionic surfactant by pure and mixed cultures of bacteria. The assay gave reproducible results over a fourfold range of inoculum optical density, and the surfactant concentration was selected to provide a compromise between the length of the lag period prior to colour production and the maximum colour produced. A kinetic model was developed and used to analyse the appearance of colour in the assay and was found to give rise to three biologically significant parameters describing the processes underlying the assay. No false-positives were obtained with environmental isolates. The small number of false-negatives obtained (< 8% of the total) could be explained by the methodology used to prepare the bacterial inoculum. All isolates which were positive in the Biology assay were shown to be both primary and ultimate degraders of the test surfactant. These results show that the method provides a useful means of studying the biodegradation of anionic surfactants by both pure and mixed cultures of bacteria and will find use in the rapid analysis of biodegradation kinetics and specificities of larger numbers of individual isolates than hitherto possible. In addition, an important benefit of the methodology is that it can be used for direct analysis of the biodegradation potential of whole bacterial communities without having to make an artificial selection during laboratory growth.

Bacteria↗

PubMed2002

Biodegradable polymers for the environment.

Biodegradable polymers are designed to degrade upon disposal by the action of living organisms. Extraordinary progress has been made in the development of practical processes and products from polymers such as starch, cellulose, and lactic acid. The need to create alternative biodegradable water-soluble polymers for down-the-drain products such as detergents and cosmetics has taken on increasing importance. Consumers have, however, thus far attached little or no added value to the property of biodegradability, forcing industry to compete head-to-head on a cost-performance basis with existing familiar products. In addition, no suitable infrastructure for the disposal of biodegradable materials exists as yet.

Biodegradation, Environmental↗

PubMed1986

Biodegradation of tert-butylphenyl diphenyl phosphate.

The biodegradation of tert-butylphenyl diphenyl phosphate (BPDP) was examined in microcosms containing sediment and water from five different ecosystems as part of our studies to elucidate the environmental fate of phosphate ester flame retardants. Biodegradation of [14C]BPDP was monitored in the environmental microcosms by measuring the evolution of 14CO2. Over 37% of BPDP was mineralized after 8 weeks in microcosms from an ecosystem which had chronic exposure to agricultural chemicals. In contrast, only 1.7% of BPDP was degraded to 14CO2 in samples collected from a noncontaminated site. The exposure concentration of BPDP affected the percentage which was degraded to 14CO2 in microcosms from the two most active ecosystems. Mineralization was highest at a concentration of 0.1 mg of BPDP and was inhibited with 10- and 100-fold higher concentrations of BPDP in these microcosms. Indigenous heterotrophic and BPDP-utilizing microbial populations and phosphoesterase enzyme activities were highest in sediments which had the highest biodegradation of BPDP. We observed adaptive increases in both microbial populations and phosphoesterase enzymes in some sediments acclimated to BPDP. Chemical analyses of the residues in the microcosms indicated undegraded BPDP and minor amounts of phenol, tert-butylphenol, diphenyl phosphate, and triphenyl phosphate as biodegradation products. These data suggest that the microbial degradation of BPDP results from at least three catabolic processes and is highest when low concentrations of BPDP are exposed to sediment microorganisms of eutrophic ecosystems which have high phosphotri- and diesterase activities and previous exposure to anthropogenic chemicals.

Animals↗

PubMed1986

Biodegradation of chlorinated ethenes by a methane-utilizing mixed culture.

Chlorinated ethenes are toxic substances which are widely distributed groundwater contaminants and are persistent in the subsurface environment. Reports on the biodegradation of these compounds under anaerobic conditions which might occur naturally in groundwater show that these substances degrade very slowly, if at all. Previous attempts to degrade chlorinated ethenes aerobically have produced conflicting results. A mixed culture containing methane-utilizing bacteria was obtained by methane enrichment of a sediment sample. Biodegradation experiments carried out in sealed culture bottles with radioactively labeled trichloroethylene (TCE) showed that approximately half of the radioactive carbon had been converted to 14CO2 and bacterial biomass. In addition to TCE, vinyl chloride and vinylidene chloride could be degraded to products which are not volatile chlorinated substances and are therefore likely to be further degraded to CO2. Two other chlorinated ethenes, cis and trans-1,2-dichloroethylene, were shown to degrade to chlorinated products, which appeared to degrade further. A sixth chlorinated ethene, tetrachloroethylene, was not degraded by the methane-utilizing culture under these conditions. The biodegradation of TCE was inhibited by acetylene, a specific inhibitor of methane oxidation by methanotrophs. This observation supported the hypothesis that a methanotroph is responsible for the observed biodegradations.

1-Propanol↗

PubMed1993

Biodegradation, sorption, and transport of 2,4-dichlorophenoxyacetic acid in saturated and unsaturated soils.

The fate of an organic contaminant in soil depends on many factors, including sorption, biodegradation, and transport. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model compound to illustrate the impact of these interacting factors on the fate of an organic contaminant. Batch and column experiments performed with a sandy loam soil mixture under saturated and unsaturated conditions were used to determine the effects of sorption and biodegradation on the fate and transport of 2,4-D. Sorption of 2,4-D was found to have a slight but significant effect on transport of 2,4-D under saturated conditions (retardation factor, 1.8) and unsaturated conditions (retardation factor, 3.4). Biodegradation of 2,4-D was extensive under both batch and column conditions and was found to have a significant impact on 2,4-D transport in column experiments. In batch experiments, complete mineralization of 2,4-D (100 mg kg-1) occurred over a 4-day period following a 3-day lag phase under both saturated and unsaturated conditions. The biodegradation rate parameters calculated for batch experiments were found to be significantly different from those estimated for column experiments.

2,4-Dichlorophenoxyacetic Acid↗