In Vitro Stain Transport in Canaliculi of Rat Femora Under Cyclic Loading

2000 ◽  
Author(s):  
Bixia Li ◽  
Timothy L. Norman
Keyword(s):  
Fluid Flow ◽  
Cyclic Loading ◽  
Confocal Microscopy ◽  
Mechanical Loading ◽  
Cyclic Load ◽  
Flow Behavior ◽  
Load Level ◽  
Static Conditions ◽  
Rat Bone

Abstract In this study, rat femurs were used to test the diffusion and mechanical transport properties of a fluroscein stain tracer in microvessels of bone. Fluroscein was used as a tracer to visualize the fluid flow behavior using confocal microscopy. It was found that stain transport occurs due to diffusion under static conditions and due to mechanical loading. The transport increased with cyclic load level and frequency. Our results also show that stain transport at the canaliculi level occurs rapidly in rat bone.

Influence of Cyclic Loading on Mechanical Loosening of Hinged Knee Prostheses

1978 ◽  
Vol 7 (4) ◽  
pp. 235-239 ◽  
Author(s):  
D. H. van Campen ◽  
H. W. Croon ◽  
J. Lindwer
Keyword(s):  
Experimental Investigation ◽  
Cyclic Loading ◽  
Mechanical Loading ◽  
Knee Prosthesis ◽  
In Vitro Experiments ◽  
Knee Prostheses ◽  
Normal Walking ◽  
Fresh Cadaver ◽  
Unfavourable Effect

A combined theoretical and experimental investigation is reported with respect to the influence of mechanical loading on loosening at the cement bone interface of knee prostheses with intermedullary stems. The in vitro experiments have been performed under cyclic loading conditions with the tibial part of a Shiers knee prosthesis implanted in fresh cadaver tibiae. The experimental results indicate an unfavourable effect of peak loading (as occurring in walking up stairs) on loosening as compared with loading due to normal walking conditions.

scholarly journals TAMI-15. THE EFFECT OF INTERSTITIAL FLUID FLOW AND ASTROCYTES / MICROGLIA ON INVASION, PROLIFERATION AND STEMNESS OF PATIENT-DERIVED GLIOMA STEM CELLS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii216-ii216
Author(s):  
Naciye Atay ◽  
Jessica Yuan ◽  
Chase Cornelison ◽  
Jennifer Munson
Keyword(s):  
Stem Cells ◽  
Fluid Flow ◽  
Interstitial Fluid ◽  
Pressure Head ◽  
Molecular Classification ◽  
Patient Specific ◽  
Glioma Stem Cells ◽  
Interstitial Fluid Flow ◽  
Static Conditions

Abstract SIGNIFICANCE Glioblastoma is a highly infiltrative, malignant, and deadly glioma that can be classified into subtypes based on molecular classification. Treatment resistant glioma stem cells (GSCs) depend on the tumor microenvironment (TME) to drive recurrence. Cellular composition and interstitial fluid flow (IFF) are significant aspects of the TME. IFF and astrocyte and microglia (A+M) presence have independently been shown to mediate invasion. This study’s goal is to expand our knowledge of IFF and A+M effects on invasion to proliferation and stemness. METHODS Seven patient-derived GSC lines were tested in an in vitro 3D model, which consists of GSCs ± A+M resuspended in 0.2% hyaluronan / 0.12% rat tail collagen I gel. The gel was applied to an 8um pore 96-well transwell system. Flow and static conditions were modeled with and without a pressure head above the gel, respectively. Cells beyond the transwell membrane after 18 hrs of incubation were considered invaded. Stemness and proliferation were determined via flow cytometry for CD71 and Ki67, respectively. RESULTS/CONCLUSIONS The three mesenchymal GSC lines tested exhibited the largest IFF fold increases in stemness, proliferation, and invasion with averages of 23.9, 19.1, and 2.1, respectively. CD44+ cell populations, highest in mesenchymal cells, had a strong correlation with proliferation (R=0.8439) and stemness (R=0.7829) under flow. Furthermore, depending on the cell line/subtype, the addition of A+M either amplified, reduced, reversed, mitigated, or kept constant the effect of IFF on invasion and proliferation. Incorporating A+M never amplified the effect of IFF on stemness. Adding A+M had a strong effect on the IFF fold change of at least one parameter in six of the cell lines. This is the first presentation showing that IFF, patient-specific, and context-specific factors contribute to both increased proliferation, and maintenance of stem-like phenotypes in glioma.

scholarly journals A Low Protein Diet Alters Bone Material Level Properties and the Response toIn VitroRepeated Mechanical Loading

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Victor Dubois-Ferrière ◽  
René Rizzoli ◽  
Patrick Ammann
Keyword(s):  
Cyclic Loading ◽  
Mechanical Loading ◽  
Protein Diet ◽  
Female Rats ◽  
Low Protein Diet ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Bone Material ◽  
Low Protein

Low protein intake is associated with an alteration of bone microstructure and material level properties. However, it remains unknown whether these alterations of bone tissue could influence the response to repeated mechanical loading. The authors investigated thein vitroeffect of repeated loading on bone strength in humeri collected from 20 6-month-old female rats pair-fed with a control (15% casein) or an isocaloric low protein (2.5% casein) diet for 10 weeks. Bone specimens were cyclically loaded in three-point bending under load control for 2000 cycles. Humeri were then monotonically loaded to failure. The load-displacement curve of thein vitrocyclically loaded humerus was compared to the contralateral noncyclically loaded humerus and the influence of both protein diets. Material level properties were also evaluated through a nanoindentation test. Cyclic loading decreased postyield load and plastic deflection in rats fed a low protein diet, but not in those on a regular diet. Bone material level properties were altered in rats fed a low protein diet. This suggests that bone biomechanical alterations consequent to cyclic loading are more likely to occur in rats fed a low protein diet than in control animals subjected to the samein vitrocyclic loading regimen.

scholarly journals Effects of chondrogenic priming duration on mechanoregulation of engineered cartilage anlagen

2020 ◽  
Author(s):  
Anna M. McDermott ◽  
Emily A. Eastburn ◽  
Daniel J. Kelly ◽  
Joel D. Boerckel
Keyword(s):  
Dynamic Loading ◽  
Mechanical Loading ◽  
Endochondral Ossification ◽  
Bone Development ◽  
Mechanical Compression ◽  
Dynamic Mechanical ◽  
Matrix Deposition ◽  
Static Conditions

AbstractBone development and repair occur by endochondral ossification of a cartilage anlage, or template. Endochondral ossification is regulated by mechanical cues. Recently, we found that in vivo mechanical loading promoted regeneration of large bone defects through endochondral ossification, in a manner dependent on the timing of load initiation. Here, we have developed an in vitro model of the cartilage anlage to test whether the chondrogenic differentiation state alters the response to dynamic mechanical compression. We cultured human bone marrow stromal cells (hMSCs) at high cell density in fibrin hydrogels under chondrogenic priming conditions for periods of 0, 2, 4, or 6 weeks prior to two weeks of dynamic mechanical loading. Samples were evaluated by biomechanical testing, biochemical analysis of collagen and glycosaminoglycan (GAG) deposition, gene expression analysis, and immunohistological analysis, in comparison to time-matched controls cultured under static conditions. We found that dynamic loading increased the mechanical stiffness of engineered anlagen in a manner dependent on the duration of chondrogenic priming prior to load initiation. For chondrogenic priming times of 2 weeks or greater, dynamic loading enhanced the expression of type II collagen and aggrecan, although no significant changes in overall levels of matrix deposition was observed. For priming periods less than 4 weeks, dynamic loading generally supressed markers of hypertrophy and osteogenesis, although this was not observed if the priming period was extended to 6 weeks, where loading instead enhanced the expression of type X collagen. Taken together, these data demonstrate that the duration of chondrogenic priming regulates the endochondral response to dynamic mechanical compression in vitro, which may contribute to the effects of mechanical loading on endochondral bone development, repair, and regeneration in vivo.

Influence of Uniaxial Tensile Cyclic Load on the Porosity of High Performance Concrete

2011 ◽  
Vol 94-96 ◽  
pp. 1500-1504
Author(s):  
Fu Xiang Jiang ◽  
Tie Jun Zhao ◽  
Ming Lei Hao
Keyword(s):  
Cyclic Loading ◽  
High Performance ◽  
Cyclic Load ◽  
High Performance Concrete ◽  
Tensile Load ◽  
Total Porosity ◽  
Load Level ◽  
Uniaxial Tensile ◽  
Cycle Number ◽  
Axial Tensile

The total porosity of the high performance concrete under cyclic loading was measured in this present paper. Results show that finite cycles of cyclic axial tensile load causes permanent damage to concrete, which can be measured after unloading. The higher the applied upper load level or the more the cycle number is, the more obvious will be the connection and development of micro cracks. Then the higher will be the total porosity. Especially, with the increase of cyclic load number, the total porosity of the concrete shows obvious stage characteristics. And there is a linear relationship between the total porosity and cyclic loading cycles in the second developing stage of fatigue strain.

Analysis of the Dynamics of the Electric Capacitance of a Cell Monolayer at the Late Stages of Caco-2 cell Differentiation

2019 ◽  
Vol 35 (6) ◽  
pp. 87-90
Author(s):  
S.V. Nikulin ◽  
V.A. Petrov ◽  
D.A. Sakharov
Keyword(s):  
Impedance Spectroscopy ◽  
Cell Monolayer ◽  
Microfluidic Chips ◽  
Russian Science ◽  
Electric Capacitance ◽  
A Cell ◽  
Static Conditions ◽  
Late Stages

The real-time monitoring of electric capacitance (impedance spectroscopy) allowed obtaining evidence that structures which look like intestinal villi can be formed during the cultivation under static conditions as well as during the cultivation in microfluidic chips. It was shown in this work via transcriptome analysis that the Hh signaling pathway is involved in the formation of villus-like structures in vitro, which was previously shown for their formation in vivo. impedance spectroscopy, intestine, villi, electric capacitance, Hh The study was funded by the Russian Science Foundation (Project 16-19-10597).

Improved Production of Two Anti-Candida Lipopeptide Homologues Co- Produced by the Wild-Type Bacillus subtilis RLID 12.1 under Optimized Conditions

2020 ◽  
Vol 21 (5) ◽  
pp. 438-450
Author(s):  
Ramya Ramchandran ◽  
Swetha Ramesh ◽  
Anviksha A ◽  
RamLal Thakur ◽  
Arunaloke Chakrabarti ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Pathogenic Fungi ◽  
Fold Increase ◽  
Production Yield ◽  
Yield Enhancement ◽  
Bioactive Metabolites ◽  
Candida Auris ◽  
Media Formulation ◽  
Static Conditions

Background:: Antifungal cyclic lipopeptides, bioactive metabolites produced by many species of the genus Bacillus, are promising alternatives to synthetic fungicides and antibiotics for the biocontrol of human pathogenic fungi. In a previous study, the co- production of five antifungal lipopeptides homologues (designated as AF1, AF2, AF3, AF4 and AF5) by the producer strain Bacillus subtilis RLID 12.1 using unoptimized medium was reported; though the two homologues AF3 and AF5 differed by 14 Da and in fatty acid chain length were found effective in antifungal action, the production/ yield rate of these two lipopeptides determined by High-Performance Liquid Chromatography was less in the unoptimized media. Methods:: In this study, the production/yield enhancement of the two compounds AF3 and AF5 was specifically targeted. Following the statistical optimization (Plackett-Burman and Box-Behnken designs) of media formulation, temperature and growth conditions, the production of AF3 and AF5 was improved by about 25.8- and 7.4-folds, respectively under static conditions. Results:: To boost the production of these two homologous lipopeptides in the optimized media, heat-inactivated Candida albicans cells were used as a supplement resulting in 34- and 14-fold increase of AF3 and AF5, respectively. Four clinical Candida auris isolates had AF3 and AF5 MICs (100 % inhibition) ranging between 4 and 16 μg/ml indicating the lipopeptide’s clinical potential. To determine the in vitro pharmacodynamic potential of AF3 and AF5, time-kill assays were conducted which showed that AF3 (at 4X and 8X concentrations) at 48h exhibited mean log reductions of 2.31 and 3.14 CFU/ml of C. albicans SC 5314, respectively whereas AF5 at 8X concentration showed a mean log reduction of 2.14 CFU/ml. Conclusion:: With the increasing threat of multidrug-resistant yeasts and fungi, these antifungal lipopeptides produced by optimized method promise to aid in the development of novel antifungal that targets disease-causing fungi with improved efficacy.

Dosage and Passage Dependent Neuroprotective Effects of Exosomes Derived from Rat Bone Marrow Mesenchymal Stem Cells: An In Vitro Analysis

2018 ◽  
Vol 18 ◽  
Author(s):  
Chaitra Venugopal ◽  
Christopher Shamir ◽  
Sivapriya Senthilkumar ◽  
Janitri Venkatachala Babu ◽  
Peedikayil Kurien Sonu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Neuroprotective Effects ◽  
Marrow Mesenchymal Stem Cells ◽  
Vitro Analysis ◽  
In Vitro Analysis ◽  
Rat Bone

Microneedle-Assisted Percutaneous Transport of Magnesium Sulfate

2020 ◽  
Vol 17 (2) ◽  
pp. 140-147
Author(s):  
Karna B. Ghimirey ◽  
Kevin Ita
Keyword(s):  
Confocal Microscopy ◽  
Stratum Corneum ◽  
Magnesium Sulfate ◽  
Inductively Coupled Plasma ◽  
Optical Emission ◽  
Magnesium Concentration ◽  
Porcine Skin ◽  
Time Curve ◽  
Student’S T

Objective: In vitro diffusion experiments were performed to assess the permeation of magnesium sulfate across pig skin. Method: The mean thickness of the dermatomed porcine skin was 648 ± 12 µm. Magnesium concentration was measured using inductively coupled plasma-optical emission spectroscopy. Transdermal flux of magnesium sulfate across MN-treated and untreated porcine skin was obtained from the slope of the steady-state linear portion of cumulative amount versus time curve. Results: Statistical analysis of the results was done with Student’s t-test. The transdermal flux of magnesium sulfate across microneedle-treated porcine skin was 134.19 ± 2.4 µg/cm2/h and transdermal flux across untreated porcine skin was 4.64 ± 0.05 µg/cm2/h. Confocal microscopy was used to visualize the microchannels created by a solid microneedle roller (500 µm). Conclusion: From our confocal microscopy studies, it was evident that the 500 μm long microneedles disrupted the stratum corneum and created microchannels measuring 191 ± 37 µm. The increase in transdermal flux across the microneedle-treated skin was statistically significant compared to that of controls, i.e., without the application of microneedles. With the application of microneedles, the transdermal flux of magnesium permeated over 12 h was approximately 33-fold higher in comparison to passive diffusion across an intact stratum corneum.

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