scholarly journals Monitoring and Assessing the Degradation Rate of Magnesium-Based Artificial Bone In Vitro Using a Wireless Magnetoelastic Sensor

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3066 ◽  
Author(s):  
Limin Ren ◽  
Kun Yu ◽  
Yisong Tan
Keyword(s):  
Output Power ◽  
Degradation Rate ◽  
Alkaline Media ◽  
Internal Environment ◽  
Artificial Bone ◽  
Engineering Software ◽  
Degradation Rates ◽  
Novel Method ◽  
Degradation Time

A magnetoelastic-based (MB) sensor was employed as a novel method to monitor and assess the degradation rate of magnesium-based artificial bone (MBAB) in vitro, which can be used as an implant to repair a bone defect, providing a quantitative method to depict the degradation rate of MBAB. MBABs were fabricated by the Pro/Engineering software and a precision machine tool using high-purity (HP) magnesium. The MB sensor was embedded in the neutral surface of MBAB by an unharmful quick adhesive, forming the MB sensor-embedded MBAB (EMBAB). The modified simulated body fluid (MSBF) media (PH = 7.4), mimicking the human internal environment, and the NaOH media (PH = 12), accelerating EMBAB’s degradation, were used to immerse the EMBAB for 15 days at 37 °C. The EMBAB was then tested daily on a self-developed experimental platform to monitor the relative output power under a 100 N external force. The results showed that the relative output power of the sensing coil gradually increased with the EMBAB’s degradation. The degradation rate of the EMBAB could be calculated on the basis of the changes of the relative output power caused by the MB sensor and of the degradation time. With the EMBAB’s degradation, an increasing strain directly worked on the MB sensor, significantly changing the value of the relative output power, which means that the EMBAB was characterized by a quick degradation rate. During the 15 days of the experiment, the degradation rates on the 7th and 15th days were 0.005 dbm/day and 0.02 dbm/day, and 0.02 dbm/day and 0.04 dbm/day in MSBF and alkaline media, respectively. Therefore, the MB sensor provides a wireless and passive method to monitor and assess the degradation rate of bone implants in vitro.

scholarly journals Nutritional diversity of Brachiaria ruziziensis clones

2018 ◽  
Vol 48 (2) ◽  
Author(s):  
Ellen de Almeida Moreira ◽  
Shirley Motta de Souza ◽  
Alexandre Lima Ferreira ◽  
Thierry Ribeiro Tomich ◽  
José Augusto Gomes Azevêdo ◽  
...  
Keyword(s):  
Degradation Rate ◽  
Neutral Detergent Fiber ◽  
Ruminal Fermentation ◽  
Dry Matter Digestibility ◽  
Brachiaria Ruziziensis ◽  
Hierarchical Grouping ◽  
Degradation Rates ◽  
Main Components ◽  
Lower Contribution

ABSTRACT: The aim of this study was to evaluate the nutritional diversity of Brachiaria ruziziensis clones through chemical composition and in vitro kinetics of ruminal fermentation. Twenty three clones of Brachiaria ruziziensis were used (15, 16, 46, 174, 411, 590, 651, 670, 768, 776, 844, 859, 950, 965, 970, 975, 1067, 1093, 1296, 1765, 1806, 1894 and 1972) and Brachiaria ruziziensis cv. ‘Kennedy’, Brachiaria brizantha cv. ‘Marandu’ and Brachiaria decumbens cv. ‘Basilisk’ as controls within 27 days of harvesting. The experimental design used randomized blocks with 26 treatments (genotypes) and three replications. Evaluation of the nutritional divergence was performed using principal components analysis, based on the following discriminatory variables: in vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), lignin, crude protein (CP), degradation rate of non-fibrous carbohydrates (KdNFC) and degradation rate of fibrous carbohydrates (KdFC). The evaluation of the nutritional diversity of Brachiaria genotypes was based on the two main components (IVDMD and NDF), which explains 96.2% of the total variance Variables of lower contribution to the discrimination of the clones were as degradation rates of the fibrous and non-fibrous carbohydrates. In the agglomerative hierarchical grouping analysis, five distinct groups were identified, where V group, formed by clones 46, 768 and 1067 have higher values of IVDMD compared to the other clones.

scholarly journals In Vivo Simulation of Magnesium Degradability Using a New Fluid Dynamic Bench Testing Approach

2019 ◽  
Vol 20 (19) ◽  
pp. 4859 ◽  
Author(s):  
Ole Jung ◽  
Dario Porchetta ◽  
Marie-Luise Schroeder ◽  
Martin Klein ◽  
Nils Wegner ◽  
...  
Keyword(s):  
Degradation Rate ◽  
Test Bench ◽  
Fluid Dynamic ◽  
Dynamic Test ◽  
Gas Production ◽  
Hydrogen Gas ◽  
Human Blood Plasma ◽  
Degradation Rates

The degradation rate of magnesium (Mg) alloys is a key parameter to develop Mg-based biomaterials and ensure in vivo-mechanical stability as well as to minimize hydrogen gas production, which otherwise can lead to adverse effects in clinical applications. However, in vitro and in vivo results of the same material often differ largely. In the present study, a dynamic test bench with several single bioreactor cells was constructed to measure the volume of hydrogen gas which evolves during magnesium degradation to indicate the degradation rate in vivo. Degradation medium comparable with human blood plasma was used to simulate body fluids. The media was pumped through the different bioreactor cells under a constant flow rate and 37 °C to simulate physiological conditions. A total of three different Mg groups were successively tested: Mg WE43, and two different WE43 plasma electrolytically oxidized (PEO) variants. The results were compared with other methods to detect magnesium degradation (pH, potentiodynamic polarization (PDP), cytocompatibility, SEM (scanning electron microscopy)). The non-ceramized specimens showed the highest degradation rates and vast standard deviations. In contrast, the two PEO samples demonstrated reduced degradation rates with diminished standard deviation. The pH values showed above-average constant levels between 7.4–7.7, likely due to the constant exchange of the fluids. SEM revealed severe cracks on the surface of WE43 after degradation, whereas the ceramized surfaces showed significantly decreased signs of corrosion. PDP results confirmed the improved corrosion resistance of both PEO samples. While WE43 showed slight toxicity in vitro, satisfactory cytocompatibility was achieved for the PEO test samples. In summary, the dynamic test bench constructed in this study enables reliable and simple measurement of Mg degradation to simulate the in vivo environment. Furthermore, PEO treatment of magnesium is a promising method to adjust magnesium degradation.

scholarly journals Mg-Zn-Ca Alloys for Hemostasis Clips for Vessel Ligation: In Vitro and In Vivo Studies of Their Degradation and Response

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3039 ◽  
Author(s):  
Yen-Hao Chang ◽  
Chun Chieh Tseng ◽  
Chih-Yeh Chao ◽  
Chung-Hwan Chen ◽  
Sung-Yen Lin ◽  
...  
Keyword(s):  
Degradation Rate ◽  
Protective Layer ◽  
Dip Coating ◽  
In Vivo Studies ◽  
Surface Measurement ◽  
In Vivo Experiments ◽  
Degradation Rates ◽  
And Behavior

To control the degradation rate of magnesium (Mg) alloys, chitosan (CHI) and L-glutamic acid (LGA) were used as coatings on Mg-Zn-Ca alloys via dip coating. In this study, either two or seven CHI/LGA layers were applied as a coating on Mg-2.8Zn-0.8Ca alloy (ZX31) and Mg-2.8Zn-0.8Ca hemostasis clips (ZX31 clips). The morphologies, compositions, and surface roughness of the specimens were characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, and surface measurement devices. The degradation rates and behavior of the specimens were evaluated by immersing them in simulated body fluids and by applying these ZX31 clips on rabbits’ uterine tubes for five weeks. The specimen with seven layers (ZX31(CHI/LGA)7) exhibited improved corrosion behavior when compared with ZX31 or ZX31(CHI/LGA)2, with a reduced degradation rate of the Mg alloy in a simulated body environment. In vivo experiments showed that ZX31 clips exhibited good biocompatibilities in each group but could not maintain the clamping function for five weeks. The weight loss of ZX31(CHI/LGA)7 was significantly lower than that of the other groups. Consequently, it was verified that CHI can be used as a protective layer on a magnesium alloy surface via in vitro and in vivo experiments.

scholarly journals Rumen protein degradation rates estimated by non-linear regression analysis of Michaelis–Menten in vitro data

1992 ◽  
Vol 67 (1) ◽  
pp. 27-42 ◽  
Author(s):  
Glen A. Broderick ◽  
Murray K. Clayton
Keyword(s):  
Linear Regression ◽  
Protein Degradation ◽  
Degradation Rate ◽  
Soya Bean ◽  
Protein Sources ◽  
Degradation Rates ◽  
Non Linear ◽  
Bean Meal ◽  
Soya Bean Meal

An in vitro method applying Michaelis–Menten saturation kinetics was developed as an alternative approach for estimating protein degradation rates in the rumen. Non-linear regression (NLR) analysis of the integrated Michaelis–Menten equation yielded fractional degradation rates,kd, from direct estimates of the maximum velocity: Michaelis constant ratio (kd=Vmax:Km). Degradation rates obtained using data from a series of 2 h inhibitor in vitro incubations were respectively 0.989, 0.134, and 0.037 /h for casein, solvent soya-bean meal (SSBM) and expeller soya-bean meal (ESBM). Degradation rates obtained from 2 h incubations had lower standard errors than those obtained using 1 h incubations; 2 h rates were not significantly different from 1 h rates, suggesting end-product inhibition was not significant at 2 h. The NLR Michaelis–Menten method was used to determine degradation rates for twelve protein sources: casein, bovine serum albumin, two samples of lucerne (Medicago sativa) hay, and four samples each of SSBM and ESBM. Statistical analysis of NLR results revealed significant differences among the twelve protein sources. Casein was degraded most rapidly (0.827 /h), and the four ESBM samples most slowly (0.050–0.098 /h). Degradation rate for serum albumin was 0.135 /h; rates for SSBM and lucerne hays ranged from 0.160 to 0.208 /h. Degradation rates estimated using the NLR method were more rapid than those obtained with a limited substrate approach; NLR rates were more consistent with in vivo estimates of rumen protein escape. Greater concentrations of slowly degraded proteins were needed with the NLR method to define curvilinearity of the degradation curve more accurately.Protein degradation rate: Rumen protein escape: Michaelis–Menten kinetics: Non-linear regression

The Effect of Poly(Ethylene succinate) on Mechanical Property of PLLA/PES Composite in the In Vitro Degradation Process

2012 ◽  
Vol 602-604 ◽  
pp. 790-793
Author(s):  
Xin Fan ◽  
Qi Yuan Chen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Degradation Rate ◽  
Degradation Process ◽  
Melt Blending ◽  
Bending Properties ◽  
Poly Ethylene ◽  
Degradation Time

Poly(L-lactide)/poly(ethylene succinate)(PLLA/PES) composites were prepared via melt-blending. The bending properties of PLLA/PES composites and PLLA materials were determined. And the effect of degradation time on mechanical properties of PLLA/PES composites and PLLA were too discussed. The results show that the degradation rate of PLLA/PES composites is faster than that of PLLA materials, especially after the degradation time of 12 weeks.

scholarly journals The role of N-terminal modification of MeCP2 in the pathophysiology of Rett syndrome

2017 ◽  
Author(s):  
Taimoor I. Sheikh ◽  
Alexia Martínez de Paz ◽  
Shamim Akhtar ◽  
Juan Ausió ◽  
John B. Vincent
Keyword(s):  
Missense Mutation ◽  
Rett Syndrome ◽  
Degradation Rate ◽  
Regulatory Protein ◽  
Translational Efficiency ◽  
Disease Genes ◽  
Degradation Rates ◽  
Exon 1 ◽  
Syndrome Protein

AbstractMethyl CpG-binding protein 2 (MeCP2), the mutated protein in Rett syndrome (RTT), is a crucial chromatin-modifying and gene-regulatory protein that has two main isoforms (MeCP2_E1 and MeCP2_ E2) due to the alternative splicing and switching between translation start codons in exons one and two. Functionally, these two isoforms appear to be virtually identical; however, evidence suggests that only MeCP2_E1 is relevant to RTT, including a single RTT missense mutation in exon 1, p.Ala2Val. Here, we show that N-terminal co- and post- translational modifications differ for MeCP2_E1, MeCP2_E1-p.Ala2Val and MeCP2_E2, which result in different protein degradation rates in vitro. We report partial N-methionine excision (NME) for MeCP2_E2, whereas NME for MeCP2_E1 is complete. Surprisingly, we also observed evidence of excision of multiple alanine residues from the N-terminal polyalanine stretch. Regarding MeCP2_E1-Ala2Val, we also observed only partial NME and N-acetylation (NA) of either methionine or valine. The localization of MeCP2_E1 and co-localization with chromatin appear to be unaffected by the p.Ala2Val mutation. However, a higher proteasomal degradation rate was observed for MeCP2_E1-Ala2Val compared with that for wild type (WT) MeCP2_E1. Thus, the etiopathology of p.Ala2Val is likely due to a reduced bio-availability of MeCP2 because of the faster degradation rate of the unmodified defective protein. MeCP2_E1 is thought to have a much higher translational efficiency than MeCP2_E2. Our data suggest that this increased efficiency may be balanced by a higher degradation rate. The higher turnover rate of the MeCP2_E1 protein suggests that it may play a more dynamic role in cells than MeCP2_E2.Significance statementThe Rett syndrome protein, MeCP2, undergoes a number of modifications before becoming functionally active in the body’s cells. Here, we report the presence of N-terminal modifications in both MeCP2 isoforms, MeCP2_E1 and MeCP2_E2, and that the only reported Rett missense mutation in exon 1, p.Ala2Val, disrupts these modifications, decreasing the longevity of the protein. Interestingly, p.Ala2Val mutations have been reported in many other disease genes, such as DKCX, ECHS1, IRF6, SMN1, and TNNI3, and the etiopathological mechanism(s) have never been explained. Thus, this work is important not only for the understanding of the pathophysiology of Rett syndrome but also for a deeper understanding of the effects of genetic mutations at the N-terminal end of genes in general.

Biodegradability of Cellulose Fibers and the Fabrics in Activated Sludge

2012 ◽  
Vol 217-219 ◽  
pp. 918-922 ◽  
Author(s):  
Jian Tao Niu ◽  
Xiao Ying Zhang ◽  
Na Na Pei ◽  
Qi Lei Tian
Keyword(s):  
Crystal Structure ◽  
Surface Roughness ◽  
Activated Sludge ◽  
Degradation Rate ◽  
Morphological Structure ◽  
Cellulose Fibers ◽  
Degradation Rates ◽  
Ramie Fibers ◽  
Diffraction Peaks ◽  
Degradation Time

Fabrics of cellulose fibers such as cotton, ramie and viscose were buried in activated sludge, the biodegradability of cellulose fibers and their fabrics were studied. And the relations between degradation rates, morphological structure and crystal structure of these fibers and degradation time were analyzed. The results indicated that, under the same conditions, degradation rate of viscose fiber was higher than that of cotton and ramie fibers. With the increase of degradation time, breakage to the fabrics occurred, meanwhile, fibers showed an increase of surface roughness and displayed a lot of tiny cavities and cracks. In the process of degradation, these cellulose fibers of cotton, ramie and viscose all formed new diffraction peaks near the place of 2θ=26.5°, in addition, the degrees of crystallinity of these fibers were fluctuated.

Effects of food deprivation and refeeding on total protein and actomyosin degradation

1984 ◽  
Vol 246 (1) ◽  
pp. E32-E37 ◽  
Author(s):  
J. B. Li ◽  
S. J. Wassner
Keyword(s):  
Protein Degradation ◽  
Food Deprivation ◽  
Total Protein ◽  
Degradation Rate ◽  
Muscle Protein ◽  
Major Effect ◽  
Fed State ◽  
Degradation Rates ◽  
Total Muscle

Total protein and actomyosin degradation rates were determined in perfused rat hemicorpus preparations. By simultaneously measuring the release of two nonmetabolizable amino acids phenylalanine and N tau-methylhistidine from the hemicorpus, the respective rates of total protein and actomyosin degradation could be calculated. When rats were deprived of food for 48 h, the rate of total protein degradation increased to 148% of the fed controls. If rats were food deprived and then refed for 24 h, the degradation rate decreased to only 79% of the rate of fed controls. Measurement of N tau-methylhistidine release indicated that food deprivation led to a dramatic increase in the rate of actomyosin degradation (427% of fed), whereas refeeding decreased the actomyosin degradation rate to that of the fed controls. Calculations of the fractional degradation rates show that actomyosin breaks down at a much slower rate than the nonactomyosin proteins (1.5 vs. 20.8%/day in preparations from fed rats, and 6.2 vs. 28.2%/day in preparations from food-deprived rats). Therefore, the contribution of actomyosin breakdown to total muscle protein breakdown is small in the fed state (11%) and increased threefold after food deprivation. The addition of insulin to the perfusion medium decreased the rate of total protein degradation by 18% in preparations from food-deprived rats with no significant effect on actomyosin degradation. Thus, in vitro, insulin's major effect may be to decrease the degradation of more rapidly turning over, nonactomyosin proteins. Protein degradation, as well as protein synthesis, contributes to the adaptation of muscle to starvation and refeeding.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Evaluation of Terpenes’ Degradation Rates by Rumen Fluid of Adapted and Non-adapted Animals

2020 ◽  
Author(s):  
I. Poulopoulou ◽  
I. Hadjigeorgiou
Keyword(s):  
Degradation Rate ◽  
Rumen Fluid ◽  
Reaction Medium ◽  
Anaerobic Conditions ◽  
Degradation Rates ◽  
Preliminary Study ◽  
Over Time

Abstract The aim of the present study was to evaluate terpenes degradation rate in the rumen fluid from adapted and non-adapted animals. Four castrated healthy animals, two rams and two bucks, were used. Animals were daily orally dosed for 2 weeks with 1 g of each of the following terpenes, α-pinene, limonene and β-caryophyllene. At the end of each week, rumen fluid (RF) samples were assayed in vitro for their potential to degrade terpenes over time. For each animal, a 10 mL reaction medium (RM) at a ratio 1:9 (v/v) was prepared and a terpenes solution at a concentration of 100 μg/ml each, was added in each RM tube. Tubes were incubated at 39 °C under anaerobic conditions and their contents sampled at 0, 2, 4, 8, 21 and 24 h. RF could degrade terpenes as it was shown by the significantly (P < 0.05) higher overall degradation rates. Individual terpene degradation rates, were significantly (P < 0.05) higher in week 5 for limonene and marginally (P = 0.083) higher also in week 5 for α-pinene. In conclusion, the findings of the present preliminary study suggest that terpenes can be degraded in the rumen fluid.

Degradation of Internal Fixation Materials Based on Antibacterial and Absorbable Silk Containing Different Gentamicin Concentrations

2021 ◽  
Author(s):  
Chenglong Shi ◽  
Xuqiang Liao ◽  
Xiaobing Pu ◽  
Xiushi Li ◽  
Ruihui Wu ◽  
...  
Keyword(s):  
Internal Fixation ◽  
Water Absorption ◽  
Clinical Application ◽  
Degradation Rate ◽  
Material Degradation ◽  
Antibacterial Performance ◽  
Degradation Rates ◽  
Gentamicin Concentration ◽  
Application Requirements

Abstract Adding gentamicin to silk fibroin enhances both the antibacterial performance and degradation rate of silk-based materials. The increased material degradation rate can affect the strength of early internal fixation, resulting in internal fixation failure. This study sought to adjust the gentamicin concentration to control the material degradation rate, thereby better meeting clinical application requirements. The in vitro degradation, water absorption rate, and expansion rate of silk-based materials containing different gentamicin concentrations were studied. A gentamicin-loaded silk-based screw (GSS) was implanted into the femurs of New Zealand rabbits. Micro-computed tomography (Micro-CT) was used to measure the screw diameter, which was then used to calculate the degradation rate. The in vitro results revealed increasing material degradation rates with increasing gentamicin concentration but no significant differences in water absorption rates with different gentamicin concentrations. The degradation rates of gentamicin-loaded (4 mg/g) silk-based rod-like materials were approximately 11.08% at three months in vitro and 9.4% in the animal experiment. The time for complete degradation was predicted from the fitting curve to be approximately 16 months. The degradation of material containing 4 mg/g gentamicin meets clinical application requirements, and previous experimental results demonstrate good antibacterial performance is retained by materials containing this gentamicin concentration.

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