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Biomedical Engineering and Bioengineering Commons™
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- Bone (3)
- Mechanical properties (3)
- Bioprostheses (2)
- Bone density (2)
- Fluoride (2)
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- Animal models (1)
- Biomechanics (1)
- Bioprosthetic heart valves (1)
- Bone collagen (1)
- Collagen (1)
- Dentin (1)
- Dual energy x-ray absorptiometry (DXA) (1)
- Enamel (1)
- Epoxides (1)
- Estrogen (1)
- Femur/physiology (1)
- Fluorosis (1)
- Glutaraldehyde (1)
- Heart valves (1)
- Hormone replacement therapy (1)
- IGF-1 (1)
- Lumbar Vertebrae/physiology (1)
- Mechanical (1)
- Mechanical response tissue analyzer (MRTA) (1)
- Mechanical testing (1)
- Mineral (1)
- Mineralization (1)
- Osteoporosis (1)
- Osteoporosis/physiopathology (1)
Articles 1 - 8 of 8
Full-Text Articles in Biomedical Engineering and Bioengineering
Effect Of Applied Uniaxial Stress On Rate And Mechanical Effects Of Cross-Linking In Tissue-Derived Biomaterials, Debbie Chachra, Paul Gratzer, Christopher Pereira, J. Lee
Effect Of Applied Uniaxial Stress On Rate And Mechanical Effects Of Cross-Linking In Tissue-Derived Biomaterials, Debbie Chachra, Paul Gratzer, Christopher Pereira, J. Lee
Debbie Chachra
Conformational changes in collagen fibrils, and indeed the triple helix, can be produced by application of mechanical stress or strain. We have demonstrated that the rate of cross-linking in glutaraldehyde and epoxide homobifunctional reagents can be modulated by uniaxial stress (strain). Two poly(glycidyl ether) epoxides were used: Denacol® EX-810 (a small bifunctional reagent), and Denacol EX-512 (a large polyfunctional reagent). To prevent any possible effect from being masked by saturation of cross-linking sites, bovine pericardium was cross-linked to such an extent that the increase in collagen denaturation temperature, Td, was one-half of the maximal rise achievable with …
Shelf-Life Of Bioprosthetic Heart Valves: A Structural And Mechanical Study, Maryse Julien, Dany Letouneau, Yves Marois, Alain Cardou, Martin King, Robert Guidoin, Debbie Chachra, J. Lee
Shelf-Life Of Bioprosthetic Heart Valves: A Structural And Mechanical Study, Maryse Julien, Dany Letouneau, Yves Marois, Alain Cardou, Martin King, Robert Guidoin, Debbie Chachra, J. Lee
Debbie Chachra
This study was undertaken to evaluate the influence of storage conditions on the shelf-life of porcine bioprosthetic valves. Fifty-five unimplanted porcine bioprostheses have been evaluated. The valves were stored in 0.5% buffered glutaraldehyde solution for different periods of time (7, 23 and 32 months). Twenty-eight valves were refrigerated while the remaining valves were stored at room temperature. The pH of the glutaraldehyde solution at room temperature decreased with time of storage, while that kept in the refrigerator remained stable over the course of the study. Macroscopic observations showed that the valve tissues kept at room temperature, especially for the periods …
Fluoride Treatment Increased Serum Igf-1, Bone Turnover, And Bone Mass, But Not Bone Strength, In Rabbits, C. Turner, L. Garetto, A. Dunipace, W. Zhang, M. Wilson, Marc Grynpas, Debbie Chachra, R. Mcclintock, M. Peacock, G. Stookey
Fluoride Treatment Increased Serum Igf-1, Bone Turnover, And Bone Mass, But Not Bone Strength, In Rabbits, C. Turner, L. Garetto, A. Dunipace, W. Zhang, M. Wilson, Marc Grynpas, Debbie Chachra, R. Mcclintock, M. Peacock, G. Stookey
Debbie Chachra
We hypothesized that fluoride partly acts by changing the levels of circulating calcium-regulating hormones and skeletal growth factors. The effects of oral fluoride on 24 female, Dutch-Belted, young adult rabbits were studied. The rabbits were divided into two study groups, one control and the other receiving about 16 mg fluoride/rabbit/day in their drinking water. After 6 months of fluoride dosing, all rabbits were euthanized and bone and blood samples were taken for analyses. Fluoride treatment increased serum and bone fluoride levels by over an order of magnitude (P < 0.001), but did not affect body weight or the following serum biochemical variables: urea, creatinine, phosphorus, total protein, albumin, bilirubin, SGOT, or total alkaline phosphatase. No skeletal fluorosis or osteomalacia was observed histologically, nor did fluoride affect serum PTH or Vitamin D metabolites (P > 0.4). BAP was increased 37% (P < 0.05) by fluoride; serum TRAP was increased 42% (P < 0.05); serum IGF-1 was increased 40% (P < 0.05). Fluoride increased the vertebral BV/TV by 35% (P …
The Effect Of Different Hormone Replacement Therapy Regimens On The Mechanical Properties Of Rat Vertebrae, Debbie Chachra, M. Kasra, Carla Vanin, N. Maclusky, R. Casper, Marc Grynpas
The Effect Of Different Hormone Replacement Therapy Regimens On The Mechanical Properties Of Rat Vertebrae, Debbie Chachra, M. Kasra, Carla Vanin, N. Maclusky, R. Casper, Marc Grynpas
Debbie Chachra
The purpose of this study was to examine the effects of estrogen replacement, in concert with three different progestin regimens, on the mechanical properties of rat lumbar vertebrae. Ninety-two Sprague-Dawley rats (11 months old) were divided into six groups for treatment. The first group was an intact control, the second group (OVX) was ovariectomized only, and the third group (estrogen-only) was ovariectomized and received continuous estrogen through a 17-estradiol implant. The remaining groups were ovariectomized and received estrogen and progestin (norethindrone, NET) therapy; 3 g of NET was injected daily (estrogen plus continuous NET), or 6 g of NET was …
Differential Effects Of Ovariectomy On The Mechanical Properties Of Cortical And Cancellous Bone In Rat Femora And Vertebrae, Debbie Chachra, J.M. Lee, M. Kasra, Marc Grynpas
Differential Effects Of Ovariectomy On The Mechanical Properties Of Cortical And Cancellous Bone In Rat Femora And Vertebrae, Debbie Chachra, J.M. Lee, M. Kasra, Marc Grynpas
Debbie Chachra
The purpose of this study was to evaluate the effects of ovariectomy on the mechanical properties of bone in the aged Sprague-Dawley rat model of osteoporosis. Eight female rats were sacrificed at the start of the study, at the age of four months. Twenty-four remaining rats were then bilaterally ovariectomized (OVX), and another twenty-four served as controls. Eight rats from each group were sacrificed at five, ten or fifteen weeks. The mean density of L1 vertebral bodies from OVX rats was lower than in their control counterparts, as was the compressive modulus, the ultimate compressive stress and the toughness. The …
Bone Quality In Animal Models Of Osteoporosis, Marc Grynpas, Debbie Chachra, Kathleen Lundon
Bone Quality In Animal Models Of Osteoporosis, Marc Grynpas, Debbie Chachra, Kathleen Lundon
Debbie Chachra
The use of animal models is a very powerful tool for the preclinical assessment of potential therapies for osteoporosis. However, the effective use of animal models has two prerequisites. The first is the use of appropriate techniques to assess the overall effects of therapy on bone. As spontaneous fractures do not occur in any species other than humans, the efficacy of a therapy cannot be assessed by its impact on fracture incidence. Instead, a suite of parameters (collectively referred to as ‘bone quality’), including bone architecture, mineralization and mechanical properties, is examined. While techniques such as histomorphometry and dual-energy x-ray …
Fluoride And Mineralized Tissues, Debbie Chachra, Anya Vieira, Marc Grynpas
Fluoride And Mineralized Tissues, Debbie Chachra, Anya Vieira, Marc Grynpas
Debbie Chachra
This review focuses on the interaction of fluoride with the material properties of bone and teeth, which is of clinical, scientific, and public health interest. These tissues are composed primarily of collagen (protein) and hydroxyapatite (mineral), and their mechanical function depends on the properties of the constituents, their proportions, the interface, and the three-dimensional structure. Changing any of these may have clinical consequences. Fluoride interacts with mineralized tissues in a number of ways. At low doses, the fluoride may be passively incorporated into the mineral, stabilizing it against dissolution; this is one of the mechanisms by which municipally fluoridated water …
A New Tool To Assess The Mechanical Properties Of Bone Due To Collagen Degradation, C. Wynnyckyj, S. Omelon, K. Savage, M. Damani, Debbie Chachra, Marc Grynpas
A New Tool To Assess The Mechanical Properties Of Bone Due To Collagen Degradation, C. Wynnyckyj, S. Omelon, K. Savage, M. Damani, Debbie Chachra, Marc Grynpas
Debbie Chachra
Current clinical tools for evaluating fracture risk focus only on the mineral phase of bone. However, changes in the collagen matrix may affect bone mechanical properties, increasing fracture risk while remaining undetected by conventional screening methods such as dual energy x-ray absorptiometry (DXA) and quantitative ultrasound (QUS). The mechanical response tissue analyzer (MRTA) is a non-invasive, radiation-free potential clinical tool for evaluating fracture risk. The objectives of this study were two-fold: to investigate the ability of the MRTA to detect changes in mechanical properties of bone as a result of treatment with 1 M potassium hydroxide (KOH) and to evaluate …