Effects Of Degradation Products Research Articles

Effects of degradation products from gelatin spongy scaffolds on angio-osteogenic capacity

ABSTRACT The objective of this study was to determine whether degradation products from spongy gelatin scaffolds can enhance angiogenesis and orthotopic bone regeneration. Spongy gelatin disks were prepared using gelatin solution concentrations ranging from 1% to 7% (v/w) within cylindrical tubes through programmed freezing, lyophilization, cutting, and dehydrothermal crosslinking and implanted in critical-sized defects of rat calvaria for up to 8 weeks. Analyses of disk implantation into rat calvaria defects by microfocus X-ray computed tomography and histomorphometry indicated that the bone volume was significantly larger in the 5% and 7% gelatin sponge groups than in the 1% and 3% gelatin sponge groups and tended to increase progressively from 5% to 7%. The histomorphometric analysis also showed that the largest number of new vessels was formed in the defect treated with 5% gelatin sponge compared to other gelatin sponges. Immunohistochemistry of matrix metalloproteinase (MMP) indicated that the gelatin concentration in the disks affected the appearance of MMP-2 and MMP-9 positive cells around the skeleton of the gelatin sponges. The degradation products of gelatin by MMP-9 and prolyl endopeptidase enhanced the formation of a capillary-like structure in human umbilical vein endothelial cells in vitro. These results suggested that the higher-density gelatin sponges tended to supply their own molecules via biodegradation, resulting in enhanced orthotopic osteogenesis through the expected function of gelatin molecules in angiogenesis and bone formation.

CHARACTERIZATION OF A NOVEL ANTIMICROBIAL SOL-GEL DEVICE COATING TO PREVENT PERIPROSTHETIC JOINT INFECTION

An increasing elderly population means joint replacement surgery numbers are projected to increase, with associated complications such as periprosthetic joint infections (PJI) also rising. PJI are particularly challenging due to antimicrobial resistant biofilm development on implant surfaces and surrounding tissues, with treatment typically involving invasive surgeries and systemic antibiotic delivery. Consequently, functionalisation of implant surfaces to prevent biofilm formation is a major research focus. This study characterises clinically relevant antimicrobials including gentamicin, clindamycin, daptomycin, vancomycin and caspofungin within a silica-based, biodegradable sol-gel coating for prosthetic devices.Antimicrobial activity of the coatings against clinically relevant microorganisms was assessed via disc diffusion assays, broth microdilution culture methods and the MBEC assay used to determine anti-biofilm activity. Human and bovine cells were cultured in presence of antimicrobial sol-gel to determine cytotoxicity using Alamar blue and antibiotic release was measured by LC-MS. Biodegradability in physiological conditions was assayed by FT-IR, ICP-MS and measuring mass change. Effect of degradation products on osteogenesis were studied by culturing mesenchymal stem cells in the presence of media in which sol-gel samples had been immersed.Antimicrobial-loaded coatings showed strong activity against a wide range of clinically relevant bacterial and fungal pathogens with no loss of activity from antibiotic alone. The sol-gel coating demonstrated controlled release of antimicrobials and initial sol-gel coatings showed no loss of viability on MSCs with gentamicin containing coatings. Current work is underway investigating cytotoxicity of sol-gel compositions against MG-63 cells and primary osteoblasts.This research forms part of an extended study into a promising antimicrobial delivery strategy to prevent PJI. The implant coating has potential to advance PJI infection prevention, reducing future burden upon healthcare costs and patient wellbeing.

VALIDATED MICROBIOLOGICAL ASSAY FOR JOSAMYCIN DETERMINATION IN ITS PHARMACEUTICAL FORMULATIONS

A simple, inexpensive and efficient agar diffusion bioassay, applying cylinder plate method, for determination of josamycin (JOS) in pure and pharmaceutical dosage forms was studied. Using a strain of Micrococcus luteus ATCC 9341 as the test organism, JOS at concentrations ranging from 0.1 to 0.5 µg/mL could be measured. The calibration graph was linear with good correlation coefficient (r = 0.999), and the method validation showed that it was specific and robust. The interference effects of degradation products and excipients were investigated in order to assess the method selectivity. The proposed method was successfully applied to estimate JOS content in tablets and suspension with good precision (intra-day RSD=0.87%; inter-day RSD=1.25%) and accuracy; the recovery values were between 97.74 and 101.13%. Bioassay was correlated with UV spectrophotometric and high performance liquid chromatographic techniques. The results obtained by these three methods were statistically analyzed by analysis of variance (ANOVA), which indicated that there was no significant difference among these methods. Therefore, we recommend this microbiological assay for drug analysis in routine quality control of josamycin in pharmaceuticals as an alternative to the physicochemical methods reported in the literature.

Field observation and simulation experiments on nutrient transformation during phytoplankton-derived particulate matter deposition.

Phytoplankton-derived particulate matter (PPM) is the active component of the solid particles in eutrophic shallow lakes. To date, understanding of the degradation characteristics of PPM and the effect of degradation products on nutrient cycling in water are limited. In this study, field observations and simulation experiments were carried out to elaborate the nutrient transformation during phytoplankton-derived particulate matter deposition in the cyanobacterial blooming area of Lake Taihu. Results showed that the deposition of the PPM was strongly facilitated by the cyanobacterial bloom and the sediment resuspension. The main variation characteristics of phosphorus (P) species in PPM are shown in the increase of Ortho-P and the decrease of biodegradable phosphorus (Poly-P, DNA-P) during the deposition of PPM. The degradation of the PPM resulted in the release of dissolved nitrogen (N) and P to the water body. The conversion of easily degradable particulate N and P in the PPM to ammonium nitrogen (NH3-N) and soluble reactive phosphorus were believed to be responsible for this phenomenon. The cycling of nutrients and the cyanobacterial bloom status might therefore be altered because of the deposition and degradation of PPM. More considerations should be given on this process in future works.

The Impact of Iron–Molybdenum Polyoxometalates and a Mixture of Nanoparticle Components on the Content of Nucleic Acids and Histone Proteins in Rat Blood Lymphocytes

Nanomaterials can exhibit a more pronounced genotoxic effect compared to the individual components contained in them, changing the structure of DNA and histone proteins, as well as the amount of these substances. We analyzed the impact of the Keplerate-type nanocluster iron–molybdenum polyoxometalate (POM) and POM degradation products in solutions on the content of nucleic acids, free nucleotides, and histone proteins in blood lymphocytes of Wistar rats. We revealed a reversible increase in the amount of DNA after a single injection of POM with a dose of 0.15 mg/100 g and no decrease in the histone content after 1, 7, and 30 injections. On the contrary, the products of degradation of the same POM dose changed the level of DNA, RNA, free nucleotides, total histone number, and the histone fractions. Preservation of the total number of lymphocytes during thirty-fold exposure to POM, in contrast to the effects of degradation products, confirms the less pronounced toxic effect of POM compared to the action of the POM component mixture.

Prokaryotic RNA activates endothelial cells promoting neutrophil transmigration.

Endothelial cell (EC)-neutrophil (PMN) interactions are crucial in the resolution of bacterial infections. Prokaryotic RNA (pRNA) has been reported as a pathogen-associated molecular pattern that is released from bacteria upon death and is able to activate PMN. In this work, we studied the effects of pRNA on EC and investigated whether these effects could modulate EC-PMN interaction. For this purpose, we purified total pRNA from Escherichia coli and used it as a stimulus for Human Umbilical Vein Endothelial Cells (HUVEC). We found that the incubation of pRNA with HUVEC caused the increase of surface intercellular adhesion molecule 1 (ICAM-1 or CD54) expression on HUVEC, and the secretion of IL-8 and von Willebrand factor, characteristics consistent with HUVEC activation, without causing toxic effects. Moreover, pRNA-treated HUVEC also induced PMN adhesion and the conditioned medium obtained from treated-HUVEC was chemotactic for PMN and caused their activation, as determined by CD11b upregulation. As reported previously, the degradation products of pRNA induced similar biological effects. The treatment of HUVEC with endocytosis inhibitors revealed that the entry of pRNA partially relied on a clathrin-dependent mechanism, whereas the effects of degradation products could not be inhibited by any of the inhibitors tested. Using a transwell system, we found that pRNA or degraded pRNA were also able to stimulate HUVEC when recognized from the basolateral side. Ourresults indicate that pRNA activates EC, resulting in the modulation ofEC-PMN interaction by inducing PMN chemotaxis, adhesion and activation. In the context of infection, pRNA sensed by EC and PMN could favor bacterial clearance.

Quantifying pretreatment degradation compounds in solution and accumulated by cells during solids and yeast recycling in the Rapid Bioconversion with Integrated recycling Technology process using AFEX™ corn stover

Effects of degradation products (low molecular weight compounds produced during pretreatment) on the microbes used in the RaBIT (Rapid Bioconversion with Integrated recycling Technology) process that reduces enzyme usage up to 40% by efficient enzyme recycling were studied. Chemical genomic profiling was performed, showing no yeast response differences in hydrolysates produced during RaBIT enzymatic hydrolysis. Concentrations of degradation products in solution were quantified after different enzymatic hydrolysis cycles and fermentation cycles. Intracellular degradation product concentrations were also measured following fermentation. Degradation product concentrations in hydrolysate did not change between RaBIT enzymatic hydrolysis cycles; the cell population retained its ability to oxidize/reduce (detoxify) aldehydes over five RaBIT fermentation cycles; and degradation products accumulated within or on the cells as RaBIT fermentation cycles increased. Synthetic hydrolysate was used to confirm that pretreatment degradation products are the sole cause of decreased xylose consumption during RaBIT fermentations.

Pyrene degradation accelerated by constructed consortium of bacterium and microalga: effects of degradation products on the microalgal growth.

Abundant microbes including bacteria, fungi, or algae are capable of biodegrading polycyclic hydrocarbons (PAHs). However, pure cultures never occur in the contaminated environments. This study aimed to understand the general potential mechanisms of interactions between microbes under pollution stress by constructing a consortium of PAH-degrading microalga (Selenastrum capricornutum) and bacterium (Mycobacterium sp. strain A1-PYR). Bacteria alone could grow on the pyrene, whereas the growth of algae alone was substantially inhibited by the pyrene of 10 mg L(-1). In the mixing culture of algae and bacteria, the growth rate of algae was significantly increased from day 4 onward. Rapid bacterial degradation of pyrene might mitigate the toxicity of pyrene to algae. Phenolic acids, the bacterial degradation products of pyrene, could serve as the phytohormone for promoting algal growth in the coculture of algae and bacteria. In turn, bacterial growth was also enhanced by the algae presented in the mixing culture. Consequently, the fastest degradation of pyrene among all biodegradation systems was achieved by the consortium of algae and bacteria probably due to such interactions between the two species by virtue of degradation products. This study reveals that the consortium containing multiple microbial species is high potential for microbial remediation of pyrene-contaminated environments, and provides a new strategy to degrade the recalcitrant PAHs.

Foaming study combined with physical characterization of aqueous MDEA gas sweetening solutions

This study has been carried out to investigate the foaming behavior of aqueous Methyldiethanolamine (MDEA) in presence of different degradation products and other contaminants as additives. This foaming study was combined with physical characterization of the tested solution to enhance the understanding of the foaming behavior. The foaming tendency of aqueous MDEA solution was reported in terms of foam volume. Foam stability was reported on the basis of the time required for the last bubble to break. The effect of degradation products and heavy and light dissolved organics on solution physical properties i.e. density, surface tension and viscosity were studied. The addition of 2.5 wt% of propionic acid decreased the foam volume by about 4% and the foam stability by about 7.14%, while the heaver organic acids (C5–C7) increased foaming. All organic acids increased the solution viscosity and density and decreased the solution surface tension by various extents. Formaldehyde increased the foaming tendency and enhanced the stability of the foam on MDEA solution. Iron(II) sulfide increased the foaming tendency by about 39.7%, although it decreased the foam stability by about 95.6%. The addition of both pentane and heptane decreased the foaming tendency and stability of the 50 wt% MDEA solution. Finally, a mathematical model was proposed to understand the parametric effects behind the foaming problem of aqueous MDEA solutions and to facilitate the tracking of the sources of foaming and alleviate them or reduce their impact.

Degradation of human collagen isoforms by Clostridium collagenase and the effects of degradation products on cell migration

Clostridium collagenase has been widely used in biomedical research to dissociate tissues and isolate cells; and, since 1965, as a therapeutic drug for the removal of necrotic wound tissues. Previous studies found that purified collagenase-treated extracellular matrix stimulated cellular response to injury and increased cell proliferation and migration. This article presents an in vitro study investigating the digestive ability of Clostridium collagenase on human collagen types I, III, IV, V and VI. Our results showed that Clostridium collagenase displays proteolytic power to digest all these types of human collagen, except type VI. The degradation products derived were tested in cell migration assays using human keratinocytes (gold surface migration assay) and fibroblasts (chemotaxis cell migration assay). Clostridium collagenase itself and the degradation products of type I and III collagens showed an increase in keratinocyte and fibroblast migration, type IV-induced fibroblast migration only, and the remainder showed no effects compared with the control. The data indicate that Clostridium collagenase can effectively digest collagen isoforms that are present in necrotic wound tissues and suggest that collagenase treatment provides several mechanisms to enhance cell migration: collagenase itself and collagen degradation products.

Effect of amine degradation products on the membrane gas absorption process

Abstract The effect of the presence of monoethanolamine (MEA) degradation products on membrane hollow fibers was investigated using untreated polypropylene (PP) as a model material. Common amine oxidative degradation products were added to MEA to simulate a degraded solution. The effect of these degradation products on the membrane gas absorption process using PP hollow fiber membrane was quantified. When PP membrane which has been exposed to amine degradation products is used in a membrane gas absorption contactor, the mass transfer rate of CO 2 is reduced relative to the use of unexposed PP. It was found that the presence of oxalic acid reduced the mass transfer rate of CO 2 in MEA most significantly followed by formic acid and then acetic acid. These acids are believed to adsorb into the PP, altering the surface properties and reducing the hydrophobicity of the membrane. This in turn increases the degree of wetting of the membrane pores. The membrane was characterized before and after use in a membrane gas absorption contactor containing degraded MEA solvent and studies showed that membrane pore wetting increased by 22–31% after 69 h of use. SEM images and XPS spectra of exposed PP membrane indicate that wetting may be due to both morphological and chemical changes in the membrane due to contact with the solvent. This study highlights the need to consider reductions in the mass transfer rate of membrane gas absorption processes associated with inevitable changes in the solvent composition that comes with prolonged use.

ATP protects, by way of receptor-mediated mechanisms, against hypoxia-induced injury in renal proximal tubules

We examined the effect of ATP on hypoxia-induced injury in freshly isolated rat renal proximal tubules and compared it with the effects of stable ATP analogues and ATP degradation products. Extracellular ATP significantly reduced hypoxia-induced structural cell damage (lactate dehydrogenase release). P2-receptor agonistic ATP analogues, including 2′-methylthio-ATP (2-Me-S-ATP), were also protective. In contrast, the P1-agonistic degradation products AMP and adenosine were not protective. Hypoxia-induced functional cell damage (loss of cellular potassium) was not changed by ATP or 2-Me-S-ATP. We therefore conclude that the protective property of ATP is not based on an effect of the degradation products or on a direct effect on cellular energy metabolism. The data indicate that the protective effect of ATP is mediated by P2 receptors. (J Lab Clin Med 2003;141:67-73)

The Degradation of Strong Basic Anion Exchange Resins and Mixed-Bed Ion-Exchange Resins: Effect of Degradation Products on Radionuclide Speciation

The most important water-soluble products of the radiolytic degradation of anion exchange resins in a cementitious environment are ammonia and methylamines. These ligands do not form complexes with most radionuclides. Exceptions are Ni, Ag, and Pd, which form strong complexes with amines.Other degradation products of anion and mixed-bed ion-exchange resins are of no importance concerning the complexation of trivalent radionuclides. This is shown indirectly by adsorption experiments: The degradation products do not have a significant effect on the adsorption of Eu(III) on calcite.The effect of ammonia and methylamines on the complexation of Ni, Ag, and Pd is investigated by chemical modeling. For Ni and Ag, rather reliable predictions can be made using available thermodynamic data. In the case of Pd, large uncertainties are encountered due to unreliable data and gaps in the set of important species.The system Pd(II)-ammonia-water is explored in detail. Predominant species are inferred by chemical analogy, and their thermodynamic data are estimated. The uncertainty in these estimated and measured but unreliable data is bound by qualitative and quantitative chemical reasoning.

Degradation of Cellulosic Materials under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate Level Radioactive Waste. Part III: Effect of Degradation Products on the Sorption of Radionuclides on Feldspar

Article Degradation of Cellulosic Materials under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate Level Radioactive Waste. Part III: Effect of Degradation Products on the Sorption of Radionuclides on Feldspar was published on August 1, 1999 in the journal Radiochimica Acta (volume 86, issue 3-4).

In vitro cultivation of cartilage tissue for reconstructive surgery: effect of L(+)-lactate and glycolate on cultivated human chondrocytes

Within the scope of producing cartilage tissue in a three-dimensional culture design, the stability of the used delivery substance in-vitro tissue product has to be improved. For this, carrier materials consisting of bioresorbable polymers, e. g. poly(L[+]-lactic acid) and poly(glycolic acid) can be used. In respect of the biocompatibility of these polymers, the effect of degradation products on chondrocytes is of major interest. The available biomaterials were tested on chondrocytes in form of their monomers, glycolic acid and L(+)-lactic acid. Effects in regard of cell activity were determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide( MTT)test. A non-pH-effect was examined by buffering with concentrated NaOH. In a short-term testing with increasing monomer concentrations as well as in a test over a twelve-day period, L(+)-lactic acid proved to have a lower cytotoxic effect on chondrocytes than glycolic acid. Similar results were obtained with buffered culture media. Therefore, poly(L[+]-lactic acid) can be recommended for the development of chondrocytes-polymer constructs for in-vitro engineering of cartilage tissue.

Studies of the Effects of Degradation Products on the Sorption of Tin and Radium

ABSTRACTThe effects on sorption on geological media caused by the presence of materials derived from a cementitious repository have been studied. This work includes an investigation of the influence of cellulosic degradation products on the sorption of tin and radium on London clay and Caithness flagstones and the sorption of radium as a function of calcium concentration.Experimental conditions were chosen to simulate those expected close to a cementitious repository (pH=l1) and at the edge of the zone of migration of the calcium plume (pH=8). Work was carried out, (i) under baseline conditions in the absence of organic materials; (ii) with gluconate, acting as a well-characterized organic degradation product simulant; (iii) with authentic cellulosic degradation products.This investigation has shown that the sorption of tin can be affected by the presence of cellulosic degradation products whereas the sorption of radium is little affected. The sorptive behaviour of radium is however strongly influenced by the calcium concentration.

The effects of degradation products on the rates of photo-reactions in polystyrene films

Polystyrene films have been exposed to 254 nm radiation under high vacuum at 25°C. The time evolution characteristics of new ultraviolet-absorbing chromophores have been examined; in particular, increased absorptions at 240 nm and 400 nm have been measured. Whilst the initial rates of increase in these absorbances are relatively rapid, they are not maintained, and decline gradually with increasing irradiation. The fall-off in rates has been attributed to an optical filter effect, the products, which have higher extinction coefficients for 254 nm radiation, absorbing some of the incident radiation in direct competition with the polymer. The results were analysed in terms of a model which allowed for an appropriately reduced rate of absorption by the polymer, and a good correlation between experimental data and theoretical prediction was observed. Other factors which could contribute to the apparent inhibition of chromophore formation are discussed, and their effects assessed.

Determination of catecholamines in pharmaceutical preparations by differential pulse polarography at the glassy carbon electrode

A polarographic method has been developed for the assay of catecholamines in pharmaceutical preparations. The compounds were determined by direct anodic oxidation at the glassy carbon electrode using differential pulse polarography. Peak current was found to be linearly related to catecholamine concentration and the glassy carbon surface was not fouled by the products of the electrochemical oxidation. The effects of degradation products and of antioxidant on the polarographic method were investigated. The method was used to determine adrenaline and noradrenaline in solution formulations, and isoprenaline and methyldopa m tablets, and was found to give accurate and reproducible results. The polarographic method had the advantages of rapidity and simplicity, making it suitable for application in routine quality control of these preparations.

Determination of metiamide (SKF 92058) by differential-pulse polarography

Metiamide (SKF 92058) undergoes anodic oxidation at the dropping-mercury electrode with the formation of mercury salt(s). Differential-pulse polarographic analysis has been carried out on several formulations in 0.1 M sodium hydroxide solution as supporting electrolyte using the peak corresponding to this oxidation process. The effects of degradation products and anti-oxidants on this determination have been investigated in addition to comparing the polarographic method with one involving high-performance liquid chromatography.