Thermal Damage Prediction for Collagenous Tissues Part I: A Clinically Relevant Numerical Simulation Incorporating Heating Rate Dependent Denaturation*

2005 ◽  
Vol 127 (1) ◽  
pp. 85-97 ◽  
Author(s):  
Alptekin Aksan ◽  
John J. McGrath ◽  
David S. Nielubowicz,
Keyword(s):  
Heating Rate ◽  
Thermal Damage ◽  
Element Analysis ◽  
Ho:Yag Laser ◽  
Damage Prediction ◽  
Rate Dependent ◽  
Collagenous Tissue ◽  
The Stability ◽  
Collagenous Tissues

Subablative thermotherapy is frequently used for the treatment of joint instability related diseases. In this therapy, mechanically deformed collagenous tissues are thermally shrunk and the stability of the tissue is re-established. In this research, the thermal damage fields generated by three different clinical heating modalities (monopolar and bipolar radio frequency and Ho:YAG laser) are compared numerically using finite element analysis. The heating rate dependent denaturation characteristics of collagenous tissues are incorporated into the model using experimental data from in vitro experimentation with rabbit patellar tendons. It is shown that there are significant differences among the thermal damage profiles created by these modalities, explaining the main reason for the discrepancies reported in the literature in terms of the efficacy and safety of each modality. In the complementary paper, the accuracy of the model presented here is verified by in vitro experimentation with a model collagenous tissue and by quantifying the denaturation-induced birefringence change using Optical Coherence Tomography and Magnetic Resonance Imaging.

scholarly journals THE PATHOGENESIS OF CHRONIC INFLAMMATION IN EXPERIMENTAL ANTIGEN-INDUCED ARTHRITIS

1972 ◽  
Vol 135 (2) ◽  
pp. 323-338 ◽  
Author(s):  
T. Derek Cooke ◽  
Eric R. Hurd ◽  
Morris Ziff ◽  
Hugo E. Jasin
Keyword(s):  
Joint Inflammation ◽  
Chronic Arthritis ◽  
Radioactive Material ◽  
Collagenous Tissue ◽  
Vitro Binding ◽  
Articular Ligaments ◽  
Antigen Antibody ◽  
Collagenous Tissues ◽  
Arthritic Joints

In an experimental arthritis induced by injection of bovine serum albumin or egg albumin into the joints of previously immunized animals, it has been demonstrated that the major portion of the radioactively labeled antigens injected was localized to avascular collagenous tissues in the joint, i.e., articular cartilage, menisci, and intra-articular ligaments. The antigens were partially eluted from the tissues with 5 M guanidine solution, but not with acid buffers or by 3 M magnesium chloride. The radioactive material eluted with guanidine was at least 80% precipitable by specific antisera. The radioactively labeled-inducing antigen was identified on the surface of articular collagenous tissues from arthritic joints by radioautography and immunofluorescence. Rabbit immunoglobulin and C3 were demonstrated in the same sites by immunofluorescence. The presence of specific antibody in collagenous tissues was demonstrated by the selective in vitro binding of 125I-labeled-inducing antigen to menisci from arthritic joints of immunized animals. The evidence obtained indicates that in this model of chronic arthritis, the inducing antigen persists for long periods of time in the form of immune complexes in the surface layers of the intra-articular collagenous tissue. The antigen retained in this form may be responsible for the chronicity of the synovitis by serving as a direct stimulus for the maintenance of prolonged antibody synthesis in the synovium and by providing a source of complement-fixing antigen-antibody complexes for the mediation of joint inflammation.

Investigation into the Stability, Crystallization Kinetics, and Heating Rate Dependent Crystallization of Amorphous Posaconazole

2020 ◽  
Vol 20 (8) ◽  
pp. 5129-5142 ◽  
Author(s):  
Shahab Ud Din ◽  
Helen Hughes ◽  
Niall J. O’Reilly ◽  
Helen Cathcart ◽  
Thomas O’Ceallaigh ◽  
...  
Keyword(s):  
Heating Rate ◽  
Crystallization Kinetics ◽  
Rate Dependent ◽  
The Stability

scholarly journals Periprosthetic Tissue Removal in Minimally Invasive Hip Refix Procedures

2010 ◽  
Vol 4 (2) ◽  
Author(s):  
Gert Kraaij
Keyword(s):  
Minimally Invasive ◽  
Thermal Damage ◽  
Hip Prosthesis ◽  
Fibrous Tissue ◽  
Clinical Situation ◽  
Pulse Frequency ◽  
Periprosthetic Tissue ◽  
Ho:Yag Laser ◽  
Tissue Removal

An alternative to conventional revision surgery of loosened hip prostheses is a new minimally invasive refixation procedure. This procedure requires the removal of periprosthetic fibrous tissue. The aim of this preliminary study is to evaluate which technique is most suitable for minimally invasive periprosthetic tissue removal: a Ho:YAG laser or a VAPR-2 coblation system. The clinical situation of a loosened prosthesis was simulated by several cadaveric femora, each implanted with a hip prosthesis. Artificially created periprosthetic lesions were filled with a fibrous tissue substitute. Using this fibrous tissue substitute, we measured temperatures in vitro at different distances from the site of removal. Temperatures during removal were recorded both inside the fibrous tissue and in the surrounding bone. This study demonstrated that temperatures generated in the bone do not result in thermal damage. Temperatures inside the fibrous tissue are sufficiently high to remove the fibrous tissue. Using the laser instead of the coblation system for the removal of fibrous tissue resulted in higher temperatures, thus, a faster removal of fibrous tissue. Additionally, the laser takes less effort to be integrated with the new surgical instrument and, therefore, we consider it a promising tool. However, when translating the results to clinical practice, the limitations of this study should be kept in mind. The equipment was set to typical presets; different settings (pulse frequency, pulse energy, and activated time) might affect the procedure’s success and risks. Care must be taken with respect to generated temperatures at larger distances from the place of removal. The use of the Ho:YAG laser, as well as VAPR coblation, might form a small risk for thermal damage to healthy surrounding tissues. Further research on apparatus settings and removal strategy is necessary before this technique can be applied for the removal of fibrous tissue in the clinical setting.

scholarly journals Predicting implant stability: in vitro validation in artificial bone

2008 ◽  
Author(s):  
Thibaut Bardyn
Keyword(s):  
Finite Element ◽  
Mechanical Stability ◽  
A Priori ◽  
Primary Stability ◽  
Computer Assisted ◽  
Implant Stability ◽  
Element Analysis ◽  
Osseointegrated Implants ◽  
The Stability

Primary stability of osseointegrated implants is necessary for short and long-term success of the treatment. This paper presents a method to help clinicians preoperatively assess this primary implant stability. The method combines a planning software with a in-house finite element solver. Once the clinician has chosen a position for the implant on the planning tool, a finite element analysis is automatically started and calculates the mechanical stability of the implant at this position. The process is designed to be as simple and fast as possible for an efficient clinical use. Mechanical testing material was used to validate the stability measured by the software. The novel tool presented here leads the way to a new generation of intelligent computer-assisted tools able to give a priori indication on the life span of the implant.

Formation and Structure of Casein Micelles in Lactating Mammary Tissue

1970 ◽  
Vol 28 ◽  
pp. 150-151
Author(s):  
Robert J. Carroll ◽  
Marvin P. Thompson ◽  
Harold M. Farrell
Keyword(s):  
Size Distribution ◽  
G Protein ◽  
Milk Proteins ◽  
Mammary Tissue ◽  
Colloidal System ◽  
Casein Micelles ◽  
The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

Optimization of the time the chromatograph thermostats exit to a given temperature

2020 ◽  
pp. 40-45
Author(s):  
Nadezhda O. Vzduleva ◽  
Valery B. Gitlin
Keyword(s):  
Heating Rate ◽  
Entire Range ◽  
Gas Chromatograph ◽  
Heating And Cooling ◽  
Operating Temperatures ◽  
The Stability

The problems of ensuring the stability of the temperature of the chromatographic experiment carried out using a serial gas chromatograph LGH-3000 are considered. Limiting the permissible heating rate of the chromatograph thermostats does not allow a quick transition to the new conditions of the chromatographic experiment in accordance with the requirements of the technical conditions. The processes of heating and cooling the thermostat are analyzed. It is shown that the ratio of the duration of the interval equal to the sum of the durations of the heating and cooling intervals to the duration of the heating interval is inversely proportional to the temperature of the chromatographic experiment. Based on this situation, an empirical algorithm is proposed for heating the thermostat to a given temperature, which made it possible to reduce the time it takes to reach a given temperature in the entire range of operating temperatures.

Reverse torque values of abutment screws after dynamic loading: The effects of sealant agents and the taper of conical connections

2020 ◽  
Author(s):  
Arda Ozdiler ◽  
suleyman dayan ◽  
Burc Gencel ◽  
Gulbahar Isık-Ozkol
Keyword(s):  
Dynamic Loading ◽  
Antibacterial Agent ◽  
In Vitro Study ◽  
Control Group ◽  
Silicone Sealant ◽  
Reverse Torque ◽  
The Stability ◽  
Torque Values ◽  
Chlorhexidine Gel

This in vitro study evaluated the influence of taper angles on the internal conical connections of implant systems and of the application of chlorhexidine gel as an antibacterial agent or a polyvinyl siloxane (PVS) sealant on the reverse torque values of abutment screws after dynamic loading. The current study tested four implant systems with different taper angles (5.4°, 12°, 45°, and 60°). Specimens were divided into three groups: control (neither chlorhexidine gel filled nor silicone sealed), 2% chlorhexidine gel-filled or silicone-sealed group, and group subjected to a dynamic load of 50 N at 1 Hz for 500,000 cycles prior to reverse torque measurements. Quantitative positive correlation was observed between the taper angle degree and the percentage of tightening torque loss. However, this correlation was significant only for the 60° connection groups except in the group in which a sealant was applied ( p = 0.013 for the control group, p = 0.007 for the chlorhexidine group). Percentages of decrease in the torque values of the specimens with silicone sealant application were significantly higher compared with both the control and chlorhexidine groups ( p = 0.001, p = 0.002, p = 0.001, and p = 0.002, respectively, according to the increasing taper angles); the percentage of decrease in torque values due to chlorhexidine application was statistically insignificant when compared with the control group. The application of gel-form chlorhexidine as an antibacterial agent does not significantly affect the stability of the implant–abutment connection under dynamic loads. PVS sealants may cause screw loosening under functional loads.

Using FRET to Measure the Time it Takes for a Cell to Destroy a Virus

2019 ◽  
Author(s):  
Candace E. Benjamin ◽  
Zhuo Chen ◽  
Olivia Brohlin ◽  
Hamilton Lee ◽  
Stefanie Boyd ◽  
...  
Keyword(s):  
Cellular Uptake ◽  
Rhodamine B ◽  
Virus Like Particle ◽  
A Cell ◽  
Viral Nanoparticles ◽  
The Stability ◽  
Open Question ◽  
Viral Surface ◽  
Fret Pair

<div><div><div><p>The emergence of viral nanotechnology over the preceding two decades has created a number of intellectually captivating possible translational applications; however, the in vitro fate of the viral nanoparticles in cells remains an open question. Herein, we investigate the stability and lifetime of virus-like particle (VLP) Qβ - a representative and popular VLP for several applications - following cellular uptake. By exploiting the available functional handles on the viral surface, we have orthogonally installed the known FRET pair, FITC and Rhodamine B, to gain insight of the particle’s behavior in vitro. Based on these data, we believe VLPs undergo aggregation in addition to the anticipated proteolysis within a few hours of cellular uptake.</p></div></div></div>

Applicability of Instability Index for In vitro Protein Stability Prediction

2019 ◽  
Vol 26 (5) ◽  
pp. 339-347 ◽  
Author(s):  
Dilani G. Gamage ◽  
Ajith Gunaratne ◽  
Gopal R. Periyannan ◽  
Timothy G. Russell
Keyword(s):  
Protein Stability ◽  
Caulobacter Crescentus ◽  
Effect Of Temperature ◽  
Instability Index ◽  
Dipeptide Composition ◽  
Experimental Conditions ◽  
The Stability ◽  
Vitro Protein

Background: The dipeptide composition-based Instability Index (II) is one of the protein primary structure-dependent methods available for in vivo protein stability predictions. As per this method, proteins with II value below 40 are stable proteins. Intracellular protein stability principles guided the original development of the II method. However, the use of the II method for in vitro protein stability predictions raises questions about the validity of applying the II method under experimental conditions that are different from the in vivo setting. Objective: The aim of this study is to experimentally test the validity of the use of II as an in vitro protein stability predictor. Methods: A representative protein CCM (CCM - Caulobacter crescentus metalloprotein) that rapidly degrades under in vitro conditions was used to probe the dipeptide sequence-dependent degradation properties of CCM by generating CCM mutants to represent stable and unstable II values. A comparative degradation analysis was carried out under in vitro conditions using wildtype CCM, CCM mutants and two other candidate proteins: metallo-β-lactamase L1 and α -S1- casein representing stable, borderline stable/unstable, and unstable proteins as per the II predictions. The effect of temperature and a protein stabilizing agent on CCM degradation was also tested. Results: Data support the dipeptide composition-dependent protein stability/instability in wt-CCM and mutants as predicted by the II method under in vitro conditions. However, the II failed to accurately represent the stability of other tested proteins. Data indicate the influence of protein environmental factors on the autoproteolysis of proteins. Conclusion: Broader application of the II method for the prediction of protein stability under in vitro conditions is questionable as the stability of the protein may be dependent not only on the intrinsic nature of the protein but also on the conditions of the protein milieu.

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