scholarly journals In Vitro Studies on Mg-Zn-Sn-Based Alloys Developed as a New Kind of Biodegradable Metal

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1606
Author(s):  
Yafeng Wen ◽  
Qingshan Liu ◽  
Weikang Zhao ◽  
Qiming Yang ◽  
Jingfeng Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Cell Counting ◽  
Confocal Laser ◽  
Second Phase ◽  
Dead Cell ◽  
Type I ◽  
Alizarin Red

Mg-Zn-Sn-based alloys are widely used in the industrial field because of their low-cost, high-strength and heat-resistant characteristics. However, their application in the biomedical field has been rarely reported. In the present study, biodegradable Mg-1Zn-1Sn and Mg-1Zn-1Sn-0.2Sr alloys were fabricated. Their microstructure, surface characteristics, mechanical properties and bio-corrosion properties were carried out using an optical microscope (OM), X-ray diffraction (XRD), electron microscopy (SEM), mechanical testing, electrochemical and immersion test. The cell viability and morphology were studied by cell counting kit-8 (CCK-8) assay, live/dead cell assay, confocal laser scanning microscopy (CLSM) and SEM. The osteogenic activity was systematically investigated by alkaline phosphatase (ALP) assay, Alizarin Red S (ARS) staining, immunofluorescence staining and quantitative real time-polymerase chain reaction (qRT-PCR). The results showed that a small amount of strontium (Sr) (0.2 wt.%) significantly enhanced the corrosion resistance of the Mg-1Zn-1Sn alloy by grain refinement and decreasing the corrosion current density. Meanwhile, the mechanical properties were also improved via the second phase strengthening. Both Mg-1Zn-1Sn and Mg-1Zn-1Sn-0.2Sr alloys showed excellent biocompatibility, significantly promoted cell proliferation, adhesion and spreading. Particularly, significant increases in ALP activity, ARS staining, type I collagen (COL-I) expression as well as the expressions of three osteogenesis-related genes (runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (Bglap)) were observed for the Mg-1Zn-1Sn-0.2Sr group. In summary, this study demonstrated that Mg-Zn-Sn-based alloy has great application potential in orthopedics and Sr is an ideal alloying element of Mg-Zn-Sn-based alloy, which optimizes its corrosion resistance, mechanical properties and osteoinductive activity.

scholarly journals Bi-layered Nanofibers Membrane Loaded with Titanium Oxide and Tetracycline as Controlled Drug Delivery System for Wound Dressing Applications

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1602 ◽  
Author(s):  
Rezk ◽  
Lee ◽  
Son ◽  
Park ◽  
Kim
Keyword(s):  
Titanium Oxide ◽  
Wound Dressing ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Cell Counting ◽  
Confocal Laser ◽  
Burst Release ◽  
Electrospinning Technique ◽  
Cell Compatibility

: The aim of this study is to develop a novel functional bi-layered membrane loaded titanium oxide (TiO2) and tetracycline (TTC) for application in wound dressing. The advantages of the electrospinning technique have to be considered for the uniform distribution of nanoparticles and TTC drug. The as prepared nanofibers and TiO2 were characterized in terms of morphology, fiber diameter, mechanical properties and surface wettability. The in vitro drug release study revealed initial burst release followed by a sustained control release of TTC for 4 days. The in vitro antibacterial of the bi-layered nanofibers was conducted against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria species showing excellent antibacterial effect for drug loaded samples compared with PCL nanofibers. Subsequently, cell counting kit-8 (CCK-8) and confocal laser scanning microscopy (CLSM) were used to evaluate its biocompatibility in vitro. Our results revealed that the bi-layered membrane has better antibacterial and cell compatibility than the control fiber. This suggests that the fabricated biocompatible scaffold is appropriate for a variety of wound dressing applications.

Bone Response to Cyclic Loading with Anodized Implants

2007 ◽  
Vol 342-343 ◽  
pp. 117-120
Author(s):  
Byung Uk Lee ◽  
Seong Joo Heo ◽  
Jai Young Koak ◽  
Seong Kyun Kim ◽  
Yong Sik Kim ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Anodic Oxidation ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Machined Surface ◽  
Alizarin Red ◽  
Bone Response ◽  
New Zealand White Rabbits ◽  
Oxidation Surface

The purpose of this study was to evaluate the bone interface response to different surface using bone remodeling rate (BRR) under cyclic loading. The tibiae of 10 New Zealand white rabbits were used. Each tibia of rabbits received 2 implants, one with anodic oxidation surface and the other with machined surface. Dynamic loading, a cyclic load of 100 N with 100 cycles was applied for 2 weeks. All implants were divided into 4 groups according to surface treatment and loading; (1) machined surface, unloaded, (2) anodic oxidation surface, unloaded, (3) machined surface, loaded, and (4) anodic oxidation surface, loaded. To determine the rate of bone formation, a series of fluorochrome bone labeling materials (tetracycline, alizarin red, and calcein green) were administrated intramuscularly at 10, 11, 12 weeks. To study the formation time of new bone, ground sections were examined under confocal laser scanning microscopy. Resonance frequency analysis (RFA) values were measured at the time of first surgery, second surgery and sacrifice. From this study, it was concluded that implants with anodic oxidation surface had higher value than machined surface on RFA measurement and anodic oxidation surface has more resistance to loading than machined surface.

scholarly journals The Chromosomal Toxin Gene yafQ Is a Determinant of Multidrug Tolerance for Escherichia coli Growing in a Biofilm

2009 ◽  
Vol 53 (6) ◽  
pp. 2253-2258 ◽  
Author(s):  
Joe J. Harrison ◽  
William D. Wade ◽  
Sarah Akierman ◽  
Caterina Vacchi-Suzzi ◽  
Carol A. Stremick ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Cell Survival ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Cell Counting ◽  
Confocal Laser ◽  
Toxin Gene ◽  
Persister Cells ◽  
E Coli

ABSTRACT Escherichia coli is refractory to elevated doses of antibiotics when it is growing in a biofilm, and this is potentially due to high numbers of multidrug-tolerant persister cells in the surface-adherent population. Previously, the chromosomal toxin-antitoxin loci hipBA and relBE have been linked to the frequency at which persister cells occur in E. coli populations. In the present study, we focused on the dinJ-yafQ-encoded toxin-antitoxin system and hypothesized that deletion of the toxin gene yafQ might influence cell survival in antibiotic-exposed biofilms. By using confocal laser scanning microscopy and viable cell counting, it was determined that a ΔyafQ mutant produced biofilms with a structure and a cell density equivalent to those of the parental strain. In-depth susceptibility testing identified that relative to wild-type E. coli, the ΔyafQ strain had up to a ∼2,400-fold decrease in cell survival after the biofilms were exposed to bactericidal concentrations of cefazolin or tobramycin. Corresponding to these data, controlled overexpression of yafQ from a high-copy-number plasmid resulted in up to a ∼10,000-fold increase in the number of biofilm cells surviving exposure to these bactericidal drugs. In contrast, neither the inactivation nor the overexpression of yafQ affected the tolerance of biofilms to doxycycline or rifampin (rifampicin). Furthermore, deletion of yafQ did not affect the tolerance of stationary-phase planktonic cells to any of the antibacterials tested. These results suggest that yafQ mediates the tolerance of E. coli biofilms to multiple but specific antibiotics; moreover, our data imply that this cellular pathway for persistence is likely different from that of multidrug-tolerant cells in stationary-phase planktonic cell cultures.

Localization of angiotensin II receptor subtypes AT1 and AT2 in the pancreas of rodents

1997 ◽  
Vol 153 (2) ◽  
pp. 269-274 ◽  
Author(s):  
P S Leung ◽  
H C Chan ◽  
L X M Fu ◽  
P Y D Wong
Keyword(s):  
Angiotensin Ii ◽  
Laser Scanning ◽  
Renin Angiotensin System ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Receptor Subtypes ◽  
Similar Distribution ◽  
Type I ◽  
Angiotensin Ii Receptor ◽  
Angiotensin Ii Receptor Subtypes

Abstract Previous studies have demonstrated the existence of several key components of the renin–angiotensin system in the pancreas. In the present study, the localization of angiotensin II receptor subtypes, type I (AT1) and type II (AT2), in the mouse and the rat pancreas was studied by immunocytochemistry using specific antipeptide antibodies against the second extracellular loops of AT1 and AT2 receptors in conjunction with confocal laser scanning microscopy. In the mouse, immunoreactivity for AT1 and AT2 was observed predominantly in the endothelia of the blood vessels and the epithelia of the pancreatic ductal system. Similar distribution of immunoreactivity for AT1 and AT2 was also observed. However, the intensity of immunoreactivity for AT1 and AT2 was stronger in the rat than that found in the mouse pancreas. Much weaker immunostaining for both AT1 and AT2, as compared with that found in ductal regions, was also found in the acini of the rodent pancreas. Together with the previous findings, the present results suggest that AT1 and/or AT2 receptors may play a role in regulating pancreatic functions in the rodent. Journal of Endocrinology (1997) 153, 269–274

scholarly journals Orientation-Dependent Deformation Behavior of 316L Steel Manufactured by Laser Metal Deposition and Casting under Local Scratch and Indentation Load

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1765
Author(s):  
Fabian Pöhl ◽  
Corinna Hardes ◽  
Felicitas Scholz ◽  
Jan Frenzel
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Laser Scanning ◽  
Local Deformation ◽  
Metal Deposition ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Laser Metal Deposition ◽  
Stainless Steel 316L ◽  
Longitudinal Specimen

This study analyzes the local deformation behavior of austenitic stainless steel 316L, manufactured conventionally by casting and additively by laser metal deposition (LMD). We produced directionally solidified 316L specimens with most grains showing (001) orientations parallel to the longitudinal specimen axis. We conducted nanoindentation and scratch experiments for local mechanical characterization and topography measurements (atomic force microscopy and confocal laser scanning microscopy) of indentation imprints and residual scratch grooves for the analysis of the deformation behavior and, in particular, of the pile-up behavior. The local mechanical properties and deformation behavior were correlated to the local microstructure investigated by scanning electron microscopy with energy dispersive X-ray spectroscopy and electron backscatter diffraction analysis. The results show that the local mechanical properties, deformation behavior, and scratch resistance strongly depend on the crystallographic orientation. Nearly (001)-oriented grains parallel to the surface show the lowest hardness, followed by an increasing hardness of nearly (101)- and (111)-oriented grains. Consequently, scratch depth is the greatest for nearly (001)-oriented grains followed by (101) and (111) orientations. This tendency is seen independently of the analyzed manufacturing route, namely Bridgman solidification and laser metal deposition. In general, the laser metal deposition process leads to a higher strength and hardness, which is mainly attributed to a higher dislocation density. Under the investigated loading conditions, the cellular segregation substructure is not found to significantly and directly change the local deformation behavior during indentation and scratch testing.

scholarly journals Visualization of Proteus mirabilis within the Matrix of Urease-Induced Bladder Stones during Experimental Urinary Tract Infection

2002 ◽  
Vol 70 (1) ◽  
pp. 389-394 ◽  
Author(s):  
Xin Li ◽  
Hui Zhao ◽  
C. Virginia Lockatell ◽  
Cinthia B. Drachenberg ◽  
David E. Johnson ◽  
...  
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Proteus Mirabilis ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Wild Type ◽  
Alizarin Red ◽  
Negative Mutant

ABSTRACT The virulence of a urease-negative mutant of uropathogenic Proteus mirabilis and its wild-type parent strain was assessed by using a CBA mouse model of catheterized urinary tract infection. Overall, catheterized mice were significantly more susceptible than uncatheterized mice to infection by wild-type P. mirabilis. At a high inoculum, the urease-negative mutant successfully colonized bladders of catheterized mice but did not cause urolithiasis and was still severely attenuated in its ability to ascend to kidneys. Using confocal laser scanning microscopy and scanning electron microscopy, we demonstrated the presence of P. mirabilis within the urease-induced stone matrix. Alizarin red S staining was used to detect calcium-containing deposits in bladder and kidney tissues of P. mirabilis-infected mice.

scholarly journals Mapping humidity-dependent mechanical properties of a single cellulose fibre

Cellulose ◽  
2021 ◽  
Author(s):  
Julia Auernhammer ◽  
Tom Keil ◽  
Binbin Lin ◽  
Jan-Lukas Schäfer ◽  
Bai-Xiang Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Stress ◽  
Laser Scanning ◽  
Numerical Models ◽  
Cellulose Fibre ◽  
Longitudinal Direction ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Cellulose Fibres ◽  
Colloidal Probe

AbstractModelling of single cellulose fibres is usually performed by assuming homogenous properties, such as strength and Young’s modulus, for the whole fibre. Additionally, the inhomogeneity in size and swelling behaviour along the fibre is often disregarded. For better numerical models, a more detailed characterisation of the fibre is required. Herein, we report a method based on atomic force microscopy to map these properties along the fibre. A fibre was mechanically characterised by static colloidal probe AFM measurements along the longitudinal direction of the fibre. Thus, the contact stress and strain at each loading point could be extracted. Stress–strain curves were be obtained along the fibre. Additionally, mechanical properties such as adhesion or dissipation were mapped. Local variations of the effective fibre radius were recorded via confocal laser scanning microscopy. Scanning electron microscopy measurements revealed the local macroscopic fibril orientation and provided an overview of the fibre topography. By combining these data, regions along the fibre with higher adhesion, dissipation, bending ability and strain or differences in the contact stress when increasing the relative humidity could be identified. This combined approach allows for one to obtain a detailed picture of the mechanical properties of single fibres. Graphic abstract

scholarly journals Water transport and the distribution of aquaporin-1 in pulmonary air spaces

1997 ◽  
Vol 83 (3) ◽  
pp. 1002-1016 ◽  
Author(s):  
R. M. Effros ◽  
C. Darin ◽  
E. R. Jacobs ◽  
R. A. Rogers ◽  
G. Krenz ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Water Transport ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Pulmonary Vasculature ◽  
Confocal Laser ◽  
Alveolar Type ◽  
Type I ◽  
Pulmonary Endothelium ◽  
Aquaporin 1

Effros, R. M., C. Darin, E. R. Jacobs, R. A. Rogers, G. Krenz, and E. E. Schneeberger. Water transport and the distribution of aquaporin-1 in pulmonary air spaces. J. Appl. Physiol. 83(3): 1002–1016, 1997.—Recent evidence suggests that water transport between the pulmonary vasculature and air spaces can be inhibited by HgCl2, an agent that inhibits water channels (aquaporin-1 and -5) of cell membranes. In the present study of isolated rat lungs, clearances of labeled (3HOH) and unlabeled water were compared after instillation of hypotonic or hypertonic solutions into the air spaces or injection of a hypotonic bolus into the pulmonary artery. The clearance of 3HOH between the air spaces and perfusate after intratracheal instillation and from the vasculature to the tissues after pulmonary arterial injections was invariably greater than that of unlabeled water, indicating that osmotically driven transport of water is limited by permeability of the tissue barriers rather than the rate of perfusion. Exposure to 0.5 mM HgCl2 in the perfusate and air-space solution reduced the product of the filtration coefficient and surface area ( P f S) of water from the air spaces to the perfusate by 28% after instillation of water into the trachea. In contrast, perfusion of 0.5 mM HgCl2 in air-filled lungs reduced P f Sof the endothelium by 86% after injections into the pulmonary artery, suggesting that much of the action of this inhibitor is on the endothelial surfaces. Confocal laser scanning microscopy demonstrated that aquaporin-1 is on mouse pulmonary endothelium. No aquaporin-1 was found on alveolar type I cells with immunogold transmission electron microscopy, but small amounts were present on some type II cells.

scholarly journals An olive pollen protein with allergenic activity, Ole e 10, defines a novel family of carbohydrate-binding modules and is potentially implicated in pollen germination

2005 ◽  
Vol 390 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Patricia Barral ◽  
Cinthya Suárez ◽  
Eva Batanero ◽  
Carlos Alfonso ◽  
Juan de Dios Alché ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Laser Scanning ◽  
Plant Cell Wall ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Carbohydrate Binding ◽  
Type I ◽  
Sequence Alignments ◽  
Carbohydrate Binding Modules ◽  
Olive Pollen

CBMs (carbohydrate-binding modules) are the most common non-catalytic modules associated with enzymes active in plant cell-wall hydrolysis. They have been frequently identified by amino acid sequence alignments, but only a few have been experimentally established to have a carbohydrate-binding activity. A small olive pollen protein, Ole e 10 (10 kDa), has been described as a major inducer of type I allergy in humans. In the present study, the ability of Ole e 10 to bind several polysaccharides has been analysed by affinity gel electrophoresis, which demonstrated that the protein bound 1,3-β-glucans preferentially. Analytical ultracentrifugation studies confirmed binding to laminarin, at a protein/ligand ratio of 1:1. The interaction of Ole e 10 with laminarin induced a conformational change in the protein, as detected by CD and fluorescence analyses, and an increase of 3.6 °C in the thermal denaturation temperature of Ole e 10 in the presence of the glycan. These results, and the absence of alignment of the sequence of Ole e 10 with that of any classified CBM, indicate that this pollen protein defines a novel family of CBMs, which we propose to name CBM43. Immunolocalization of Ole e 10 in mature and germinating pollen by transmission electron microscopy and confocal laser scanning microscopy demonstrated the co-localization of Ole e 10 and callose (1,3-β-glucan) in the growing pollen tube, suggesting a role for this protein in the metabolism of carbohydrates and in pollen tube wall re-formation during germination.

scholarly journals Quaternary ammonium silane (k21) based intracanal medicament triggers biofilm destruction

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Esther Sook Kuan Kok ◽  
Xian Jin Lim ◽  
Soo Xiong Chew ◽  
Shu Fen Ong ◽  
Lok Yin See ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Collagen Matrix ◽  
Docking Studies ◽  
Laser Scanning Microscopy ◽  
Calcium Deposition ◽  
Confocal Laser ◽  
Alizarin Red ◽  
Significant Difference ◽  
Biofilm Destruction ◽  
Root Canal Dentin

Abstract Background Compare antimicrobial efficacy of a quarternary ammonium silane (QAS)/k21 as an intracanal medicament against E. faecalis and C. albicans biofilms formed on root dentin. Methodology Dentin blocks were sterilized and E. faecalis and C. albicans microbial colonies were counted for colony-forming-units against 2%k21, 2%CHX and Ca(OH)2 medicaments. Biofilm colonies after 7 days on dentin were analysed using confocal laser scanning microscopy with live/dead bacterial viability staining. TEM was done to study dentin collagen matrix. Dentin discs from 3rd day and 7th day well plate was used for Raman spectra and observed under fluorescent-microscope. Docking studies were carried out on MMP-2 S1 binding-domain with k21. Results There was reduction of E. faecalis/C. albicans when k21, chlorhexidine and calcium hydroxide were used with highest percentage in 2%k21 treated specimens. 2%k21 showed dense and regular collagen network with intact cross-banding and decreased Raman intensity for 2%k21 on 3rd day. NaOCl + k21 showed least adherence, whereas saline groups showed highest adherence of E. faecalis and C. albicans to root-canal dentin. Alizarin red staining of hDPSCs revealed calcium deposition in all groups with significant difference seen amongst 2%k21 groups. MMP-2 ligand binding was seen accurately indicating possible target sites for k21 intervention. Conclusion 2%k21 can be considered as alternative intracanal medicament.

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