15 research outputs found
Cellulose derivatives as coatings and vehicles for controlled drug release in medical devices
Use of Vitamin D Bolus in Fortified Juice for Improving Vitamin D Status in Children with Cerebral Palsy
Children with cerebral palsy (CP) are at risk of poor nutrition due to a number of factors. Feeding, eating, drinking, and swallowing (FEDS) problems are common in these children and may result in protein-calorie malnutrition usually accompanied by micronutrient deficiencies. Vitamin D is among the elements whose uptake is obstructed. Insufficient exposure to solar radiation in children and adolescents with CP adds to further decreasing serum vitamin D levels thus potentially affecting growth, bone density, and muscle function. Since maintaining long-term adherence to daily oral administration of vitamin D in this population is often difficult, bolus therapy by using vitamin D-fortified products could be an alternative way of effective and safe vitamin D intake. Purpose: Assessing the efficacy of administration of bolus vitamin D in fortified juice for increasing 25(OH)D levels in a group of 15 children with CP. Results: The juice was well tolerated, and a significant increase in 25(OH)D levels was observed from 54.1 to 110.3 nmol/L (p < 0.0001) 4 weeks after the administration without any case of hypercalcemia. Conclusion: Bolus therapy with vitamin D3-fortified juice is well tolerated and effectively increases 25(OH)D levels in children with CP. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG
Investigation of the drug release time from the biodegrading coating of an everolimus eluting stent
This case-study examines the release time of the everolimus drug from an experimental biodegrading coating of a Rontis corp. drug eluting stent (DES). The controlled drug release is achieved by the degradation of the coating, which consists of a mixture of polylactic co-glycolic acid (PLGA) and everolimus (55:45). In our analysis, we used the outcome of another study, which contains the geometry of an in-silico deployed Rontis corp. stent in a 3D reconstructed coney arterial segment. Using this geometry as input, the everolimus release was simulated using a computational model that includes: i) modeling of the blood flow dynamics, ii) modeling of PLGA degradation, and iii) modeling of the everolimus advection and diffusion towards both the lumen and the arterial wall. The results show the rapid release of everolimus. This is justified due to the high porosity of the coating, which is caused by the initial high concentration of everolimus in the coating.Clinical Relevance - The methodology presented in this work is an additional step towards predicting accurately drug release from DES. Also, the results of our work prove that high drug concentration in the coating causes its rapid release, which could be used as input in the design of new DES. © 2021 IEEE
Impact of Soil Salinity on Barley Allelopathic Potential and Main Secondary Metabolites Gramine and Hordenine
Crop allelopathy is a useful tool in integrated weed suppression. Although the abiotic stresses affect the produced secondary metabolites, the impact of soil salinity on crop allelopathic potential under field conditions has not been investigated. So, the effect of soil salinity on the allelopathic activity of 18 allelopathic barley (Hordeum vulgare L.) varieties was investigated. The allelopathy of barley grown on saline and non-saline soils was investigated during a 2-year field experiment using the Perlite-based bioassay with rigid ryegrass (Lolium rigidum L.) as plant indicator. The two main allelopathic substances in barley, gramine and hordenine, were determined using the high-performance liquid chromatography with tandem mass spectrometry. The results indicated that rigid ryegrass germination and root length were adversely affected by the barley aqueous extracts. The secondary metabolite gramine was detected in greater concentrations than those of hordenine. For most barley varieties, soil salinity reduced the phytotoxicity of aqueous extracts, as well as the concentration of gramine. However, gramine and hordenine were not highly correlated with the barley extract phytotoxicity, indicating the possible involvement of other allelopathic substances. In conclusion, the barley allelopathic potential probably decreases in soils with high salinity. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
FEA of Drug-Eluting Stents and Sensitivity Analysis of a Continuum Damage Model for the Degradation of PLGA Coating
Drug-Eluting Stents (DES) are commonly used in coronary angioplasty operations as a solution against artery stenosis and restenosis. Computational Bioengineering allows for the in-silico analysis of their performance. The scope of this work is to develop a DES Digital Twin, focusing on the mechanical integrity of its biodegradable coating throughout the operational lifecycle. The implementation leverages the Finite Element Method (FEM) to compute the developed mechanical stress field on the DES during the inflation/deflation stage, followed by the degradation of the polymer-based coating. The simulation of the degradation process is based on a Continuum Damage Mechanics (CDM) model that considers bulk degradation. The CDM algorithm is implemented on the NX Nastran solver through a user-defined material (UMAT) subroutine. For benchmarking purposes and to compare with the baseline design of the BioCoStent project, this conceptual study implements an alternative stent design, to study the effect of the geometry on the developed stresses. Additionally, the effect of the degradation rate on the polymer-based coating's lifecycle is studied via sensitivity analysis. © 2021 IEEE
Coupled FEA Model with Continuum Damage Mechanics for the Degradation of Polymer-based coatings on Drug-Eluting Stents
Drug-Eluting Stents (DES) are commonly used in Coronary angioplasty procedures to reduce the phenomenon of restenosis. Numerical simulations are proven to be a useful tool to the Bioengineering community in computing the mechanical performance of stents. BioCoStent is a research project aiming to develop a DES with retinoic acid (RA) coating, in the frame of which FEAC is responsible for the in silico numerical simulation of the coating's degradation in terms of Finite Element Analysis (FEA). The coatings under study are poly(lactic-co-glycolic acid) (PLGA) and polylactide (PLA). The FEA is based on the Continuum Damage Mechanics (CDM) theory and considers a mechanistic model for polymer bulk degradation of the coatings. The degradation algorithm is implemented on the NX Nastran solver through a user-defined material UMAT subroutine. This paper describes the developed numerical model to compute the degradation of biodegradable coatings on DES. The transient numerical model provides useful insight into the critical areas with regards to the scalar damage of the coatings. The FEA results present a complete degradation of polymers after several weeks. © 2021 IEEE
Evaluation of a new paclitaxel-coated balloon catheter in an in vivo porcine peripheral venous model: Feasibility, safety, and drug deliverability
Purpose: To evaluate in vivo the feasibility, safety, and paclitaxel (PTX) deliverability of a newly developed non-commercially available Paclitaxel-Coated Balloon (PCB) catheter in the swine healthy peripheral vein model. Materials and methods: In total 12 PCBs were deployed in 12 venous segments. Primary feasibility endpoint was the successful application of the devices to the veins of the animals. Primary efficacy endpoint was the determination of the drug content in the venous tissue at 24 h and 7 days after balloon expansion, as assessed by analysis of the vein tissue with High Performance Liquid Chromatography (HPLC) coupled with tandem mass spectrometry. Primary safety endpoint was freedom from any major adverse event. Secondary endpoint was the investigation of any independent factor affecting the primary endpoints. Results: Paclitaxel was detected in five out of six tissue samples 24 h post-intervention and five out of six tissues at 7 days following the procedure (10 tissue samples out of 12). The mean weight of tissue that was examined was 0.20604 ± 0.29822 g (range: 1.02823–0.03377 g) and the mean PTX concentration detected was 8.4 ± 13.1 μg/g (range: 0–36.1 μg/g). The average drug content detected at 24 h (17.1 ± 17.1 μg/g) was numerically superior, but non-statistically significant, compared to 7 days (3.1 ± 3.6 μg/g). An average of 33.8% of the drug remained on the balloon after retrieval. According to the multiple linear regression analysis, there was no significant correlation between transition time, PTX remaining on the balloon, time of analysis (24 h/7 days) and PTX tissue concentration. No abnormalities were noted during autopsy. Conclusion: The newly developed PCB successfully delivered within the healthy venous wall a dose of Paclitaxel that inhibits neointimal hyperplasia. No safety issues were raised at short-term follow-up. © The Author(s) 2022
Focus on the use of resveratrol as an adjuvant in glioblastoma therapy
Glioblastoma (GB) represents the most common and malignant form of glioma cancer. The Gold Standard in Glioblastoma is neurosurgical tumor removal and radiotherapy treatment in concomitant with temo-zolomide (TMZ). Unfortunately, because of tumor chemo and radio-resistance during this therapy, the patient’s outcome remains very poor, with a median overall survival of about 14.6 months. Resveratrol is a natural polyphenol with a stilbene structure with chemopreventive and anticancer properties. In the present review, we evaluated data from preclinical studies conducted with resveratrol as a possible adjuvant during the standard protocol of GB. Resveratrol can reach the brain parenchyma at sub-micromolar concentrations when administrated through conventional routes. In this way, resveratrol reduces cell invasion and increases the efficacy of radiotherapy (ra-diosensitizer effects) and temozolomide. The molecular mechanism of the adjuvant action of resveratrol may depend upon the reduction of PI3K/AKT/NF-κB axis and downstream targets O-6-methylguanine-DNA methyl-transferase (MGMT) and metalloproteinase-2 (MMP-2). It has been reported that redox signaling plays an important role in the regulation of autophagy. Resveratrol administration by External Carotid Artery (ECA) injection or by Lumbar Puncture (LP) can reach micromolar concentrations in tumor mass where it would inhibit tumor growth by STAT-3 dependent mechanisms. Preclinical evidences indicate a positive effect on the use of resvera-trol as an adjuvant in anti-GB therapy. Ameliorated formulations of resveratrol with a favorable plasmatic profile for a better brain distribution and timing sequences during radio and chemotherapy could represent a critical aspect for resveratrol use as an adjuvant for a clinical evaluation. © 2020 Bentham Science Publishers
Use of Fortified Bread for Addressing Vitamin D Deficiency
Vitamin D deficiency due to inadequate sun exposure and/or inadequate intake from food is very common worldwide, consisting a major public health problem. As prolonged exposure to ultraviolet radiation involves risks, food fortification of staple foods emerges as a favorable solution for addressing vitamin D deficiency. Bread is a suitable candidate for fortification as it is consumed often and is the main carbohydrate source in European countries. The purpose of this study was the evaluation of the bioavailability of vitamin D from a fortified Greek-type bread that was developed as a means for addressing vitamin D deficiency, by comparing the absorption curve of vitamin D in fortified bread in relation to that of plain vitamin supplementation. Two groups of clinically healthy volunteers consumed 25,000 international units (IU) of vitamin D3 (cholecalciferol) either in fortified bread (Group A) or in a plain supplement form (Group B). The baseline plasma concentrations of cholecalciferol were 8.1 ± 6.0 ng/mL and 6.8 ± 3.4 ng/mL in Groups A and B, respectively. After 12, 24, and 48 h, the concentrations of cholecalciferol in Group A were 16.7 ± 4.8, 15.3 ± 8.3 and 11.9 ± 6.0 ng/mL, respectively, and in Group B, 15.2 ± 3.3, 11.6 ± 2.4, and 9.6 ± 3.6 ng/mL, respectively. In both groups, the concentrations of cholecalciferol at 12 and 24 h were significantly higher than the baseline concentrations (p < 0.01). There were no statistically significant differences between the concentrations of cholecalciferol between Groups A and B, at each time point. Cholecalciferol is bioavailable from Greek-type fortified bread and bread could be used for addressing vitamin D deficiency. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG
Increased Body Mass Index (BMI) and Sunscreen Use Are Associated with Inadequate Vitamin D Status in Greek Adults in Winter: BMI, Sunscreen Use and Vitamin D Status in Greek Adults
Vitamin D deficiency is common even in sunny countries like Greece, especially during winter and is associated with skeletal disorders and additionally with increased risk for chronic diseases and adipose metabolic diseases such as obesity and diabetes. The purpose of this pilot study was the determination of vitamin D status in Greek adults and the investigation of possible correlation with lifestyles and somatometric characteristics. The study was conducted during winter and included 36 members (20 women and 16 men) of a university community in central Greece (latitude 39.6° North). Their age was 36.2 ± 16.3 years, body mass index (BMI) 26.4 ± 4.8 (women 26.6 ± 5.6, men 26.3 ± 3.8), and waist circumference 85.7 ± 13.3 cm (women 81.5 ± 13.0, men 90.7 ± 12.4) (mean ± SD). Mean serum 25(OH)D concentration was 20.1 ± 7.3 ng/mL (women 19.7 ± 7.6, men 20.7 ± 7.1). More than half of the participants had 25(OH)D levels below the 20 ng/mL (50 nmol/L) threshold of deficiency. There was a significant negative association between the use of sunscreen during summer and serum 25(OH)D concentrations during winter and a significant positive association between physical exercise and serum 25(OH)D. Levels of 25(OH)D tended to decrease with increasing BMI in persons with a BMI over 25.0. There is a high prevalence of vitamin D insufficiency in Greek adults during winter. Serum 25(OH)D levels in winter are positively associated with exercise and negatively associated with high BMI and the use of sunscreen during summer. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG