-
Environmental Science & Technology Jun 2024With octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) being considered for evaluation under the UN Stockholm Convention on Persistent Organic...
Low Dietary Uptake Efficiencies and Biotransformation Prevent Biomagnification of Octamethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5) in Rainbow Trout.
With octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) being considered for evaluation under the UN Stockholm Convention on Persistent Organic Pollutants, which specifically acknowledges risks of biomagnification of persistent organic pollutants in traditional foods, a study into the mechanism of the biomagnification process of D4 and D5 in Rainbow trout was conducted by combining the absorption-distribution-metabolism-excretion for bioaccumulation (ADME-B) approach to determine intestinal and somatic biotransformation rates and radiochemical analyses to identify metabolite formation. High rates of intestinal biotransformation of D4 and D5 (i.e., 2.1 (0.70 SE) and 0.88 (0.67 SE) day, respectively) and metabolite formation [i.e., 52.0 (17 SD)% of D4 and 56.5% (8.2 SD)% of D5 were metabolized] were observed that caused low dietary uptake efficiencies of D4 and D5 in fish of 15.5 (2.9 SE)% and 21.0 (6.5 SE)% and biomagnification factors of 0.44 (0.08 SE) for D4 and 0.78 (0.24 SE) kg-lipid·kg-lipid for D5. Bioaccumulation profiles indicated little effect of growth dilution on the bioaccumulation of D4 and D5 in fish and were substantially different from those of PCB153. The study highlights the importance of intestinal biotransformation in negating biomagnification of substances in organisms and explains differences between laboratory tests and field observations of bioaccumulation of D4 and D5.
Topics: Animals; Biotransformation; Oncorhynchus mykiss; Siloxanes; Water Pollutants, Chemical; Bioaccumulation; Diet
PubMed: 38811014
DOI: 10.1021/acs.est.4c00457 -
Waste Management (New York, N.Y.) Jul 2024Simulated landfill bioreactors were established and operated for 635 days to investigate the dynamic release of seven siloxanes in landfill biogas (denoted by...
Simulated landfill bioreactors were established and operated for 635 days to investigate the dynamic release of seven siloxanes in landfill biogas (denoted by octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4), dodecamethylpentasiloxane (L5), hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6)). In total, 259.45, 252.73, 233.30, 80.40, 4.35, 1.67 and 1.10 mg of D5, D3, D4, D6, L4, L5 and L3 were discharged from 57 kg of municipal solid waste (MSW). More than 70 % of the siloxanes were released before day 119, indicating that the peak period of siloxane discharge occurred during the hydrolysis and acid production stage. The cyclosiloxanes (D3, D4, D5 and D6) were the dominant siloxane species in the biogas. The mass load of discharged cyclosiloxanes was more than 98 % of that of the total siloxanes. In addition to the variation in the concentration distribution profiles of the different siloxane species in the MSW, transformations among species may have an important effect on the release of siloxanes. The main transformation products were D3 and D4 with high release rates (>20 %) and high measured contents of trimethylsilanol (TMSOH) and functional microorganisms (Pseudomonas) were observed during landfilling. These results suggested that MSW degradation and transformation of siloxanes both drive the dynamic release of siloxanes during long-term landfilling.
Topics: Siloxanes; Waste Disposal Facilities; Biofuels; Solid Waste; Refuse Disposal; Bioreactors
PubMed: 38810395
DOI: 10.1016/j.wasman.2024.05.038 -
Arquivos Brasileiros de Oftalmologia 2024
Topics: Humans; Silicone Oils; Anterior Chamber; Male; Emulsions; Female; Vitrectomy
PubMed: 38808910
DOI: 10.5935/0004-2749.2024-0058 -
Ugeskrift For Laeger May 2024Around 2,500 women receive a breast augmentation with silicone-based implants yearly in Denmark. A number of these women report various uncharacteristic systemic... (Review)
Review
Around 2,500 women receive a breast augmentation with silicone-based implants yearly in Denmark. A number of these women report various uncharacteristic systemic symptoms, which they attribute to the breast implants, including impaired cognition, joint pain, etc. This condition has been termed "breast implant illness" and is currently not a recognised diagnosis. The correlation between the patient's self-reported symptoms and breast implants has not been established and there is limited evidence that surgery has any effect. In this review, the current literature on the topic has been reviewed.
Topics: Humans; Breast Implants; Female; Self Report; Arthralgia; Silicone Gels; Denmark; Breast Implantation
PubMed: 38808767
DOI: 10.61409/V12230801 -
BMC Oral Health May 2024The aim of this in vitro study was to evaluate the changes the rheological properties of some soft lining materials, to compare the rheological properties and... (Comparative Study)
Comparative Study
PURPOSE
The aim of this in vitro study was to evaluate the changes the rheological properties of some soft lining materials, to compare the rheological properties and viscoelastic behaviour at different temperatures.
MATERIALS AND METHODS
Five soft lining materials (acrylic and silicone based) were used. the storage modulus (G'), loss modulus (G"), tan delta (tan δ) and complex viscosity (η') were chosen and for each material, measurements were repeated at 23, 33 and 37 °C, using an oscillating rheometer. All data were statistically analyzed using the Mann Whitney U test, Kruskal Wallis test and Conover's Multiple Comparison test at the significance level of 0.05.
RESULTS
Soft lining materials had different viscoelastic properties and most of the materials showed different rheological behavior at 23, 33 and 37 °C. At the end of the test (t¹5), at all the temperatures, Sofreliner Tough M had the highest storage modulus values while Visco Gel had the highest loss Tan delta values.
CONCLUSIONS
There were significant changes in the rheological parameters of all the materials. Also temperature affected the initial rheological properties, and polymerization reaction of all the materials, depending on temperature increase.
CLINICAL IMPLICATIONS
Temperature affected the initial rheological properties, and polymerization reaction of soft denture liner materials, and clinical inferences should be drawn from such studies conducted. It can be recommended to utilize viscoelastic acrylic-based temporary soft lining materials with lower storage modulus, higher tan delta value, and high viscosity in situations where pain complaint persists and tissue stress is extremely significant, provided that they are replaced often.
Topics: Rheology; Viscosity; Temperature; Materials Testing; Acrylic Resins; Elasticity; Denture Liners; Elastic Modulus; Dental Cavity Lining; Silicones; Polymerization; Humans; Oscillometry
PubMed: 38807138
DOI: 10.1186/s12903-024-04393-5 -
Biomaterials Science Jun 2024Cell encapsulation devices are expected to be promising tools that can control the release of therapeutic proteins secreted from transplanted cells. The protein...
Cell encapsulation devices are expected to be promising tools that can control the release of therapeutic proteins secreted from transplanted cells. The protein permeability of the device membrane is important because it allows the isolation of transplanted cells while enabling the effectiveness of the device. In this study, we investigated free-standing polymeric ultra-thin films (nanosheets) as an intrinsically semi-permeable membrane made from polydimethylsiloxane (PDMS). The PDMS nanosheet with a thickness of 600 nm showed intrinsic protein permeability, and the device fabricated with the PDMS nanosheet showed that VEGF secreted from implanted adipose tissue-derived stem cells (ASCs) could be released for at least 5 days. The ASC encapsulation device promoted angiogenesis and the development of granulation tissue 1 week after transplantation to the subcutaneous area of a mouse. This cell encapsulation device consisting of PDMS nanosheets provides a new method for pre-vascularization of the subcutaneous area in cell transplantation therapy.
Topics: Dimethylpolysiloxanes; Adipose Tissue; Animals; Mice; Stem Cells; Neovascularization, Physiologic; Nanostructures; Vascular Endothelial Growth Factor A; Permeability; Angiogenesis
PubMed: 38804980
DOI: 10.1039/d4bm00460d -
Scientific Reports May 2024Colonoscopy is the standard procedure for screening, and surveillance of colorectal cancer, including the treatment for colonic lesions. Colonic spasm is an important... (Randomized Controlled Trial)
Randomized Controlled Trial
Colonoscopy is the standard procedure for screening, and surveillance of colorectal cancer, including the treatment for colonic lesions. Colonic spasm is an important problem from colonoscopy that affects both surgeons and patients. The spasm also might be the cause of longer cecal intubation time, difficulty of the procedure, and increased pain. Previous reports indicated that antispasmodic agents can decrease such symptoms. Therefore, we conducted this study to investigate the cecal intubation time of antispasmodic agents. A single blinded randomized controlled trial was conducted from 01/11/2020 to 31/08/2021. One hundred four patients were allocated to antispasmodic agent group and control group, in 1:1 ratio. The efficacy of median (range) cecal intubation time showed similar results of 5 (2, 14) and 5 (2, 15) minutes with no statistically significant difference. The mean scores of all domains i.e., pain, spasm, cleanliness, and difficulty were better in the antispasmodic agent group about 2.6 (1.4), 1.8 (0.8), 2.4 (0.9), and 2.0 (0.9), respectively, than control group but there were spasm and cleanliness showed statistically significant difference. Moreover, the satisfaction scores showed better efficacy in decreased spasm, decreased difficulty, and increased cleanliness than control group. Prescribing of antispasmodic drugs before colonoscopy might be the choice of treatment for the patients. The antispasmodic drugs will be beneficial to both of the patient and the doctor.
Topics: Humans; Colonoscopy; Male; Female; Middle Aged; Simethicone; Parasympatholytics; Aged; Adult; Single-Blind Method; Propylamines
PubMed: 38802518
DOI: 10.1038/s41598-024-62922-2 -
International Journal of Biological... Jun 2024In this research, poly-chloropropylmethyl-silsesquioxanen was prepared and decorated with ZIF-8 in order to investigate its loading capacity for acyclovir and...
Polysilsesquioxane decorated ZIF-8 as a potential pH-responsive vehicle for topical delivery and release of acyclovir and tetracycline: Investigation of blood compatibility, cytotoxicity and antibacterial properties.
In this research, poly-chloropropylmethyl-silsesquioxanen was prepared and decorated with ZIF-8 in order to investigate its loading capacity for acyclovir and tetracycline. Before and after drug loadings, the composites were characterized by FT-IR, SEM-EDS, XRD, and XPS analyses. Then, the in-vitro release of these drugs was investigated by UV-Vis spectroscopy in different buffers (pH = 5, 7.4, and 9.1). The results showed that the release of ACV reached a maximum amount of 41.3 mg at pH = 7.4 during 12 h. In comparison, the release of TC reached a maximum amount of 22.5 mg at pH = 5 during 6 h. The blood compatibility, in-vitro cytotoxicity on the L929 fibroblast cells line, and antibacterial assay against Staphylococcus aureus and Pseudomonas aeruginosa were also investigated for this composite as a drug carrier.
Topics: Anti-Bacterial Agents; Acyclovir; Hydrogen-Ion Concentration; Tetracycline; Animals; Mice; Staphylococcus aureus; Drug Liberation; Drug Carriers; Organosilicon Compounds; Cell Line; Humans; Pseudomonas aeruginosa
PubMed: 38801848
DOI: 10.1016/j.ijbiomac.2024.132542 -
Molecules (Basel, Switzerland) May 2024In this work, we present the modification of a medical-grade silicone catheter with the -vinylimidazole monomer using the grafting-from method at room temperature and...
In this work, we present the modification of a medical-grade silicone catheter with the -vinylimidazole monomer using the grafting-from method at room temperature and induced by gamma rays. The catheters were modified by varying the monomer concentration (20-100 vol%) and the irradiation dose (20-100 kGy). Unlike the pristine material, the grafted poly(-vinylimidazole) chains provided the catheter with hydrophilicity and pH response. This change allowed for the functionalization of the catheters to endow it with antimicrobial features. Thus, the quaternization of amines with iodomethane and bromoethane was performed, as well as the immobilization of silver and ampicillin. The inhibitory capacity of these materials, functionalized with antimicrobial agents, was challenged against and strains, showing variable results, where loaded ampicillin was amply better at eliminating bacteria.
Topics: Escherichia coli; Staphylococcus aureus; Silicones; Imidazoles; Catheters; Microbial Sensitivity Tests; Polyvinyls; Anti-Infective Agents; Anti-Bacterial Agents; Ampicillin; Gamma Rays
PubMed: 38792087
DOI: 10.3390/molecules29102225 -
The Analyst Jun 2024Bioinspired nanochannel-based sensors have elicited significant interest because of their excellent sensing performance, and robust mechanical and tunable chemical...
Bioinspired nanochannel-based sensors have elicited significant interest because of their excellent sensing performance, and robust mechanical and tunable chemical properties. However, the existing designs face limitations due to material constraints, which hamper broader application possibilities. Herein, a heteromembrane system composed of a periodic mesoporous organosilica (PMO) layer with three-dimensional (3D) network nanochannels is constructed for glutathione (GSH) detection. The unique hierarchical pore architecture provides a large surface area, abundant reaction sites and plentiful interconnected pathways for rapid ionic transport, contributing to efficient and sensitive detection. Moreover, the thioether groups in nanochannels can be selectively cleaved by GSH to generate hydrophilic thiol groups. Benefiting from the increased hydrophilic surface, the proposed sensor achieves efficient GSH detection with a detection limit of 1.2 μM by monitoring the transmembrane ionic current and shows good recovery ranges in fetal bovine serum sample detection. This work paves an avenue for designing and fabricating nanofluidic sensing systems for practical and biosensing applications.
Topics: Glutathione; Limit of Detection; Porosity; Organosilicon Compounds; Animals; Cattle; Biosensing Techniques; Membranes, Artificial; Electrochemical Techniques
PubMed: 38787653
DOI: 10.1039/d4an00559g