scholarly journals Polymethyl methacrylate cure time in simulated in vivo total knee arthroplasty versus in vitro conditions

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Daniel A. Funk ◽  
Quang-Viet Nguyen ◽  
Michael Swank
Keyword(s):  
Polymethyl Methacrylate ◽  
Curing Time ◽  
Level Of Evidence ◽  
Tibial Tray ◽  
Circulating Water ◽  
Cure Time ◽  
The Moment ◽  
Precise Moment

Abstract Background The present means of confirming the cure of intra-operative polymethyl methacrylate (PMMA) cement are to wait for the remainder cement to harden. To our knowledge, there is no available technique to determine the precise moment of cure for in-vivo cement beneath the tibial tray. This study uses a novel means to determine cement curing time in two environments. One environment represents the operating theater, and the other environment attempts to model cement conditions under the tibial tray during surgery. Materials and methods We determined the temperature-versus-time plot of cement curing using the following two temperature sensors: one in a simulated implanted tibial tray and another in the remainder cement. We performed 55 tests using dental methyl methacrylate cement mixed in the same ratio as the orthopedic cement. To simulate in vivo conditions, a simulated stainless-steel tibial tray was implanted on a cancellous bone substitute (Sawbones, Vashon Island, WA, USA) using standard cement technique and subsequently placed in a 90°F (32.2 °C) circulating water bath. We positioned a temperature sensor in the cement mantel and positioned a second sensor in a portion of the remaining cement. The temperature from both sensors was measured simultaneously, beginning at 5 min after mixing and continuing for 20 min. The first derivative of the temperature provided the precise curing time for each condition. We analyzed the results of 55 repeated experiments with an independent samples t-test. Results With the described technique, we were able to accurately determine the moment of cure of the cement beneath the simulated tray. There was a mean difference between cure time of 5 min and 26 s (p value < 0.001) between the two conditions. Conclusions We validated that our technique was successful in determining the precise time to cure in two different environments. Level of evidence This was not a clinical trial and did not involve patients as such the level of evidence was Grade A: Consistent 1 and 2.

scholarly journals Polymethyl Methacrylate Cure Time in Simulated In Vivo Total Knee Arthroplasty Versus In Vitro Conditions

2021 ◽  
Author(s):  
Daniel Funk ◽  
Viet Nguyen ◽  
Michael Swank
Keyword(s):  
Polymethyl Methacrylate ◽  
P Value ◽  
Curing Time ◽  
Level Of Evidence ◽  
Tibial Tray ◽  
Circulating Water ◽  
Cure Time ◽  
Precise Moment

Abstract Background: The present means of confirming the cure of intra-operative polymethyl methacrylate (PMMA) cement is to wait for the remainder cement to harden. To our knowledge, there is no available technique to determine the precise moment of cure for in-vivo cement beneath the tibial tray. This study uses a novel means to determine cement curing time in two environments. One environment represents the operating theater, and the other environment attempts to model cement conditions under the tibial tray during surgery.Materials and Methods: We determined the temperature-versus-time plot of cement curing using the following two temperature sensors: one in a simulated implanted tibial tray and another in the remainder cement. We performed 55 tests using dental methyl methacrylate cement mixed in the same ratio as the orthopedic cement. To simulate in vivo conditions, a simulated stainless-steel tibial tray was implanted on a cancellous bone substitute (Sawbones, Vashon Island, WA, USA) using standard cement technique and subsequently placed in a 90°F (32.2 °C) circulating water bath. We positioned a temperature sensor in the cement mantel and positioned a second sensor in a portion of the remaining cement. The temperature from both sensors was measured simultaneously, beginning at 5 mins after mixing and continuing for 20 mins. The first derivative of the temperature provided the precise curing time for each condition. We analyzed the results of 55 repeated experiments with an independent samples t-test. Results: With the described technique, we were able to accurately determine the moment of cure of the cement beneath the simulated tray. There was a mean difference between cure time of 5 mins and 26 s (p-value<0.001) between the two conditions. Conclusions: We validated that our technique was successful in determining the precise time to cure in two different environments.Level of Evidence: This was not a clinical trial and did not involve patients as such the level of evidence was Grade A: Consistent 1 and 2

scholarly journals Injectable non-leaching tissue-mimetic bottlebrush elastomers as an advanced platform for reconstructive surgery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erfan Dashtimoghadam ◽  
Farahnaz Fahimipour ◽  
Andrew N. Keith ◽  
Foad Vashahi ◽  
Pavel Popryadukhin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reconstructive Surgery ◽  
Biomedical Applications ◽  
The Body ◽  
Surrounding Tissue ◽  
Curing Time ◽  
Materials Used ◽  
Significant Health

AbstractCurrent materials used in biomedical devices do not match tissue’s mechanical properties and leach various chemicals into the body. These deficiencies pose significant health risks that are further exacerbated by invasive implantation procedures. Herein, we leverage the brush-like polymer architecture to design and administer minimally invasive injectable elastomers that cure in vivo into leachable-free implants with mechanical properties matching the surrounding tissue. This strategy allows tuning curing time from minutes to hours, which empowers a broad range of biomedical applications from rapid wound sealing to time-intensive reconstructive surgery. These injectable elastomers support in vitro cell proliferation, while also demonstrating in vivo implant integrity with a mild inflammatory response and minimal fibrotic encapsulation.

Development of nanomedicines and nano-similars: recent advances in regulatory landscape

2021 ◽  
Vol 27 ◽  
Author(s):  
Rishi Paliwal ◽  
Pramod Kumar ◽  
Akash Chaurasiya ◽  
Rameshroo Kenwat ◽  
Sumeet Katke ◽  
...  
Keyword(s):  
Drug Release ◽  
Pharmaceutical Products ◽  
Regulatory Agencies ◽  
Next Generation ◽  
Similar Drug ◽  
Regulatory Guidelines ◽  
The Moment ◽  
Regulatory Landscape

Background: Nanopharmaceuticals serve as emerging forms of modern medicines which include nanomedicines, nanosimilars, nanotheranostics, nanodevices and many more. In last two decades, a large number of nano-based products has reached to the market and are being used clinically. Objectives: Unlike, conventional pharmaceutical products, nanopharmaceuticals behave differently both in vitro and in vivo and therefore, development of their generic versions needs special attention to replicate the similar drug release pattern leading to the identical therapeutic outcome. Further, drug-device combinations and 3D products are latest advancements in precise medicine delivery and development. Methods: The regulatory guidelines for these products are being framed at many stages by various regulatory agencies like USFDA/EMA and still are in infancy at the moment if we look at wider prospective and applications of nanomedicine. Results: For a formulation scientist, it is much needed that well-explained and directive guidelines should be available before leading to the development of the generic versions of these nano-cargos. Conclusion: Here, in this review, we have summarized the silent features of the regulatory perspectives related to the nanotechnology based next generation therapeutics and diagnostics.

scholarly journals Injectable Non-leaching Tissue-mimetic Bottlebrush Elastomers: A New Platform for Advancing Reconstructive Surgery

2020 ◽  
Author(s):  
Erfan Dashtimoghadam ◽  
Farahnaz Fahimipour ◽  
Andrew Keith ◽  
Foad Vashahi ◽  
Pavel Popryadukhin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reconstructive Surgery ◽  
Biomedical Applications ◽  
The Body ◽  
Surrounding Tissue ◽  
Curing Time ◽  
Materials Used ◽  
Significant Health

Abstract Current materials used in biomedical devices do not match tissue’s mechanical properties and leach various chemicals into the body. These deficiencies pose significant health risks that are further exacerbated by invasive implantation procedures. Herein, we leverage the brush-like polymer architecture to design and administer minimally invasive injectable elastomers that cure in vivo into leachable-free implants with mechanical properties matching the surrounding tissue. This strategy allows tuning curing time from minutes to hours, which empowers a broad range of biomedical applications from rapid wound sealing to time-intensive reconstructive surgery. These injectable elastomers support in vitro cell proliferation, while also demonstrating in vivo implant integrity with a mild inflammatory response and minimal fibrotic encapsulation.

scholarly journals Development of AOSpine BOnE (Bone Osteobiologics and Evidence) Classification

2019 ◽  
Vol 10 (7) ◽  
pp. 871-874 ◽  
Author(s):  
Jeffrey C. Wang ◽  
S. Tim Yoon ◽  
Darrel S. Brodke ◽  
Jong-Beom Park ◽  
Patrick Hsieh ◽  
...  
Keyword(s):  
Small Sample Size ◽  
Small Sample ◽  
In Vitro Studies ◽  
Level Of Evidence ◽  
Knowledge Forum ◽  
Levels Of Evidence ◽  
Published Evidence ◽  
Patient Reported

Study Design: Classification development. Objectives: The aim of our study was to develop a 3-tier classification for the levels of evidence for osteobiologics and provide a description of the principles by which osteobiologics can be evaluated. BOnE (Bone Osteobiologics and Evidence) classification evaluates each osteobiologic based on the available evidence, and if the published evidence is based on clinical, in vivo or in vitro studies. Methods: The process of establishing the BOnE classification included 5 face-to-face meetings and 2 web calls among members of the AOSpine Knowledge Forum Degenerative. Results: The 3 levels of evidence were determined based on the type of data on osteobiologics: level A for human studies, level B for animal studies, and level C for in vitro studies, with level A being the highest level of evidence. Each level was organized into 4 subgroups (eg, A1, A2, A3, and A4). Conclusions: The use and the variety of osteobiologics for spine fusion has dramatically increased over the past few decades; however, literature on their effectiveness is inconclusive. Several prior systematic reviews developed by AOSpine Knowledge Forum Degenerative reported low level of evidence primarily due to the high risk of bias, small sample size, lack of control groups, and limited patient-reported outcomes. BOnE classification will provide a universal platform for research studies and journal publications to classify a new or an existing product and will allow for creating decision-making algorithms for surgical planning.

scholarly journals EFFECTS OF BACTERIAL ENDOTOXINS ON METABOLISM

1962 ◽  
Vol 116 (6) ◽  
pp. 897-911 ◽  
Author(s):  
L. Joe Berry ◽  
Dorothy S. Smythe ◽  
Susannah McC. Kolbye
Keyword(s):  
Nitrogen Excretion ◽  
Protein Nitrogen ◽  
Bacterial Endotoxins ◽  
Small Change ◽  
The Moment ◽  
Lower Ratio ◽  
Urinary Nitrogen Excretion ◽  
Urinary Nitrogen

The greater susceptibility to the lethal effects of bacterial endotoxin (heat-killed Salmonella typhimurium or Escherichia coli lipopolysaccharide, in mice infected with an attenuated strain of Mycobacterium tuberculosis (BCG) was confirmed. It reached a maximum at 2 weeks postinfection and gradually diminished for an additional 6 weeks. At the time of maximum susceptibility several metabolic and physiological differences became apparent. BCG-infected mice die sooner (4 to 12 hours) and without the diarrhea, conjunctivitis, and general symptomatology associated with endotoxin deaths of normal animals. Reticuloendothelial blockade results in only a small change in reactivity to endotoxin, in contrast to normal mice. Subcutaneous injection of 2 units of ACTH is followed by no significant increase in urinary nitrogen excretion while in control animals it more than doubles. Plasma clearance of intravenously administered inulin is approximately normal in BCG-infected mice 17 hours after an LD50 dose of endotoxin but control mice similarly treated show renal impairment. In line with this result is the absence of elevated carcass non-protein nitrogen (NPN) following endotoxin poisoning or at the moment of death from endotoxemia in the hyperreactive animals in contrast to the two- to threefold increase in carcass NPN in normal mice under similar conditions. Body carbohydrate is at a minimum and becomes depleted to a level approximating that found at death more rapidly in BCG-infected mice given endotoxin than in controls. There is also a lower ratio of carbohydrate anabolized to protein catabolized following cortisone administration to BCG-infected mice than in control mice. This is found in adrenalectomized mice and in stressed animals and is reported elsewhere. Some of the differences just described can be attributed to a refractory adrenal cortex. There is less depletion of adrenal cholesterol in vivo and lower corticoid synthesis in vitro than in normal mice yet this is not fundamentally responsible for the greater susceptibility of BCG-infected animals to endotoxin since adrenalectomized mice, which are even more susceptible, are metabolically and physiologically more comparable to normal mice than to BCG-infected mice. One can conclude, therefore, that the hyperreactivity of BCG-infected mice is more than an intensification of the normal response to endotoxin.

scholarly journals Hydroxyl Ethyl Cellulose HHX and Polymethyl Methacrylate Based Site Specific Floating Delivery of Prochlorperazine Maleate

2016 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Swati C. Jagdale ◽  
Aleesha B. Randhave
Keyword(s):  
Polymethyl Methacrylate ◽  
Release Kinetics ◽  
Hydroxyethyl Cellulose ◽  
Absolute Bioavailability ◽  
Drug Bioavailability ◽  
Compression Technique ◽  
Site Specific ◽  
Floating Drug Delivery

Background:Prochlorperazine maleate is a phenothiazine antipsychotic used principally in the treatment of nausea, vomiting and vertigo. Biological half- life of the drug is about 6 to 8 hrs and oral dose is 5 or 10 mg thrice or four times a day. The mean absolute bioavailability for drug is 12.5%. Due to the solubility of drug in acidic pH, it is mainly absorbed from stomach.Objective:Site specific oral floating delivery of prochlorperazine maleate will prolong the gastric retention time, increases the drug bioavailability, reduces frequency of administration and can result in better patient compliance.Method:The tablets were prepared by direct compression technique. Floating drug delivery was developed using gas forming agent and release retarding agenti.e.hydroxyethyl cellulose HHX (Natrosol HHX) and polymethyl methacrylate (PMMA). 32full factorial design was used for optimization. Prepared tablets were evaluated for pre and post compression parameters.Results:From the factorial batches it was observed that formulation containing 68.5% of hydroxyethyl cellulose HHX and 15% of polymethyl methacrylate had shown a drug release of 91.56 ± 2.7% with floating upto 10 hrs following Korsmeyer Peppas release kinetics.Conclusion:In- vivoplacebo X-ray study for optimized batch F6 had shown good gastroretention ability for 6 ± 0.5 hrs.In- vitroandin- vivostudy confirmed the site specific floating delivery for drug.

Fuzzy Image Matching for Pose Recognition of Occluded Knee Implants Using Fluoroscopy Images

2005 ◽  
Vol 9 (2) ◽  
pp. 181-195 ◽  
Author(s):  
Syoji Kobashi ◽  
◽  
Toshihiko Tomosada ◽  
Nao Shibanuma ◽  
Motoi Yamaguchi ◽  
...  
Keyword(s):  
Femoral Component ◽  
Image Matching ◽  
Tibial Tray ◽  
Cad System ◽  
Projection Image ◽  
Tibial Insert ◽  
Total Knee ◽  
Fuzzy Image

Fluoroscopy images have been widely used for evaluating kinematics of the knee implant in vivo after the total knee Arthroplasty, TKA in short. The knee implant mainly consists of tibial tray, tibial insert and femoral component. Because a fluoroscopy image is a 2-D projection image of the 3-D knee implant, the tibial tray often overlaps with the femoral component on the projection image, or a part of the knee implant is outside of the field of view (FOV). In order to analyze such occluded images, this article introduces fuzzy logic into image matching of the given 2-D fluoroscopy image and 3-D geometric models of the knee implant. Based on the proposed fuzzy image matching algorithm, we present a novel computer-aided diagnosis (CAD) system for estimating 3-D kinematics of the knee implant with 2-D fluoroscopy dynamic images. To quantitatively evaluate our system, it was applied to computer-simulated images and phantom images that took the knee implant in vitro fixed with arbitrary pose by a jig. The experimental results denoted that this system could estimate the pose of the knee implant within the error of 0.86° with non-occluded images, and within the error of 1.28° with 15% occluded images. Also, the proposed system was applied to two patients after TKA to demonstrate the clinical application.

scholarly journals Ionizing Radiation Protein Biomarkers in Normal Tissue and Their Correlation to Radiosensitivity: Protocol for a Systematic Review

2020 ◽  
Vol 11 (1) ◽  
pp. 3
Author(s):  
Anne Dietz ◽  
Maria Gomolka ◽  
Simone Moertl ◽  
Prabal Subedi
Keyword(s):  
Systematic Review ◽  
Ionizing Radiation ◽  
Normal Tissue ◽  
Health Assessment ◽  
Risk Of Bias ◽  
Level Of Evidence ◽  
Human Normal Tissue

Background: Radiosensitivity is a significantly enhanced reaction of cells, tissues, organs or organisms to ionizing radiation (IR). During radiotherapy, surrounding normal tissue radiosensitivity often limits the radiation dose that can be applied to the tumour, resulting in suboptimal tumour control or adverse effects on the life quality of survivors. Predicting radiosensitivity is a component of personalized medicine, which will help medical professionals allocate radiation therapy decisions for effective tumour treatment. So far, there are no reviews of the current literature that explore the relationship between proteomic changes after IR exposure and normal tissue radiosensitivity systematically. Objectives: The main objective of this protocol is to specify the search and evaluation strategy for a forthcoming systematic review (SR) dealing with the effects of in vivo and in vitro IR exposure on the proteome of human normal tissue with focus on radiosensitivity. Methods: The SR framework has been developed following the guidelines established in the National Toxicology Program/Office of Health Assessment and Translation (NTP/OHAT) Handbook for Conducting a Literature-Based Health Assessment, which provides a standardised methodology to implement the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to environmental health assessments. The protocol will be registered in PROSPERO, an open source protocol registration system, to guarantee transparency. Eligibility criteria: Only experimental studies, in vivo and in vitro, investigating effects of ionizing radiation on the proteome of human normal tissue correlated with radio sensitivity will be included. Eligible studies will include English peer reviewed articles with publication dates from 2011–2020 which are sources of primary data. Information sources: The search strings will be applied to the scientific literature databases PubMed and Web of Science. The reference lists of included studies will also be manually searched. Data extraction and results: Data will be extracted according to a pre-defined modality and compiled in a narrative report following guidelines presented as a “Synthesis without Meta-analyses” method. Risk of bias: The risk of bias will be assessed based on the NTP/OHAT risk of bias rating tool for human and animal studies (OHAT 2019). Level of evidence rating: A comprehensive assessment of the quality of evidence for both in vivo and in vitro studies will be followed, by assigning a confidence rating to the literature. This is followed by translation into a rating on the level of evidence (high, moderate, low, or inadequate) regarding the research question. Registration: PROSPERO Submission ID 220064.

Sign in / Sign up

Export Citation Format

Share Document