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Porous ceramic scaffolds with complex architectures

Description: This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional (3-D) geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.
Date: March 15, 2008
Creator: Saiz, Eduardo; Munch, Etienne; Franco, Jaime; Deville, Sylvain; Hunger, Phillip; Saiz, Eduardo et al.
Partner: UNT Libraries Government Documents Department

Sintering and robocasting of beta-tricalcium phosphate scaffoldsfor orthopaedic applications

Description: {beta}-tricalcium phosphate ({beta}-TCP) scaffolds with designed, three-dimensional (3-D) geometry and mesoscale porosity have been fabricated by direct-write assembly (robocasting) techniques. Concentrated {beta}-TCP inks with suitable viscoelastic properties were developed to enable the fabrication of the complex 3-D structures. A comprehensive study of the sintering behavior of TCP as a function of the calcium content in the starting powder was also carried out, and the optimal heat treatment for fabricating scaffolds with dense {beta}-TCP rods has been determined. Such analysis provides clues to controlling the microstructure of the fabricated structures and, therefore, enabling the fabrication by robocasting of TCP scaffolds with tailored performance for bone tissue engineering applications.
Date: November 1, 2005
Creator: Miranda, Pedro; Saiz, Eduardo; Karol, Gryn & Tomsia, Antoni P.
Partner: UNT Libraries Government Documents Department

Experimental assessment of absorbed dose to mineralized bone tissue from internal emitters: An electron paramagnetic resonance study

Description: EPR resonances attributable to radiation-induced centers in hydroxyapatite were not detectable in bone samples supplied by the USTUR. These centers are the basis for imaging and dose assessment. Presumable, the short range of the alpha particles emitted precluded the formation of appreciable amounts of hydroxyapatite centers. However, one bone sample did offer a suggestion of hydroxyapatite centers and newly-developed methods to extract this information will be pursued.
Date: December 31, 1994
Creator: Desrosiers, M.F.
Partner: UNT Libraries Government Documents Department

International conference on bone mineral measurement, October 12--13, 1973, Chicago, Illinois

Description: From international conference on bone mineral measurement; Chicago, Illinois, USA (12 Oct 1973). Abstracts of papers presented at the international conference on bone mineral measurement are presented. The papers were grouped into two sessions: a physical session including papers on measuring techniques, errors, interpretation and correlations, dual photon techniques, and data handling and exchange; a biomedical session including papers on bone disease, osteoporosis, normative data, non-disease influences, renal, and activity and inactivity. (ERB)
Date: December 31, 1973
Partner: UNT Libraries Government Documents Department

Biomimetic lithography and deposition kinetics of iron oxyhydroxide thin films

Description: Heterogeneous nucleation and crystal growth on functionalized organic substrates is a critical step in biological hard tissue formation. Self assembled monolayers can be derivatized with various organic functional groups to mimic the ``nucleation proteins`` for induction of mineral growth. Studies of nucleation and growth on SAMs can provide a better understanding of biomineralization and can also form the basis of a superior thin film deposition process. We demonstrate that micron-scale, electron and ion beam, lithographic techniques can be used to pattern SAMs with functional organic groups that either inhibit or promote mineral deposition. Patterned films of iron oxyhydroxide were deposited on the areas patterned with nucleation sites. Studies of the deposition kinetic of these films show that indeed the surface induces heterogeneous nucleation and that film formation does not occur via absorption of polymers or colloidal material formed homogeneously in solution. The nucleus interfacial free energy was calculated to be 24 mJ/m2 on a SAM surface composed entirely of sulfonate groups.
Date: December 1, 1993
Creator: Rieke, P. C.; Wood, L. L.; Marsh, B. M.; Fryxell, G. E.; Engelhard, M. H.; Baer, D. R. et al.
Partner: UNT Libraries Government Documents Department


Description: Breast cancer frequently metastasizes to the bone. Upon colonizing bone tissue, the cancer cells stimulate osteoclasts (cells that break bone down), resulting in large lesions in the bone. The breast cancer cells also affect osteoblasts (cells that build new bone). Conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. Under these conditions the osteoblasts acquired a changed morphology and appeared to adherer in a different way to the substrate and to each other. To characterize cell adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for two days, and then assayed with a mechanical scanning acoustic reflection microscope (SAM). The SAM indicated that in normal medium the MC3T3-E1 osteoblasts were firmly attached to their plastic substrate. However, MC3T3-E1 cells cultured with MDA-MB-231 conditioned medium displayed both an abnormal shape and poor adhesion at the substrate interface. The cells were fixed and stained to visualize cytoskeletal components using optical microscopic techniques. We were not able to observe these differences until the cells were quite confluent after 7 days of culture. However, using the SAM, we were able to detect these changes within 2 days of culture with MDA-MB-231 conditioned medium
Date: March 1, 2005
Creator: Miyasaka, Chiaki; Mercer, Robyn R.; Mastro, Andrea M. & Telschow, Ken L.
Partner: UNT Libraries Government Documents Department

Radionuclide Concentrations in Deer and Elk from Los Alamos National Laboratory: 1991-1998

Description: Mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) forage in many areas at Los Alamos National Laboratory (LANL) that may contain radioactivity above natural and/or worldwide fallout levels. This paper summarizes radionuclide concentrations 3H, 90Sr, 137Cs, 238Pu, 239,240Pu, 241Am, and total uranium in muscle and bone tissue of deer and elk collected from LANL lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer and elk collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer and elk collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDES (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (51 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.220, deer bone = 3.762, elk muscle = 0.117, and elk bone = 1.67 mrendy. AU CEDES were far below the International Commission on Radiological Protection guideline of 100 mrem/y, and the highest muscle plus bone CEDE (4.0 mrendy) corresponded to a RECF of 2E-06 which is far below the Environmental ...
Date: December 1, 1998
Creator: Kraig, D. H.; Ferenbaugh, J. K.; Biggs, J. R.; Bennett, K. D.; Mullen, M. A. & Fresquez, P. R.
Partner: UNT Libraries Government Documents Department

Medium-Sized Mammals around a Radioactive Liquid Waste Lagoon at Los Alamos National Laboratory: Uptake of Contaminants and Evaluation of Radio-Frequency Identification Technology

Description: Use of a radioactive liquid waste lagoon by medium-sized mammals and levels of tritium, other selected radionuclides, and metals in biological tissues of the animals were documented at Technical Area 53 (TA-53) of Los Alamos National Laboratory during 1997 and 1998. Rock squirrel (Spermophilus variegates), raccoon (Procyon lotor), striped skunk (Mephitis mephitis), and bobcat (Lynx rufus) were captured at TA-53 and at a control site on the Santa Fe National Forest. Captured animals were anesthetized and marked with radio-frequency identification (RFD) tags and/or ear tags. We collected urine and hair samples for tritium and metals (aluminum, antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and thallium) analyses, respectively. In addition, muscle and bone samples from two rock squirrels collected from each of TA-53, perimeter, and regional background sites were tested for tritium, {sup 137}Cs, {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu, {sup 241}Am, and total uranium. Animals at TA-53 were monitored entering and leaving the lagoon area using a RFID monitor to read identification numbers from the RFID tags of marked animals and a separate camera system to photograph all animals passing through the monitor. Cottontail rabbit (Sylvilagus spp.), rock squirrel, and raccoon were the species most frequently photographed going through the RFID monitor. Less than half of all marked animals in the lagoon area were detected using the lagoon. Male and female rock squirrels from the lagoon area had significantly higher tritium concentrations compared to rock squirrels from the control area. Metals tested were not significantly higher in rock squirrels from TA-53, although there was a trend toward increased levels of lead in some individuals at TA-53. Muscle and bone samples from squirrels in the lagoon area appeared to have higher levels of tritium, total uranium, and {sup 137}Cs than samples collected from perimeter and background ...
Date: November 1, 1999
Creator: Hansen, Leslie A.; Fresquez, Phil R.; Robinson, Rhonda J.; Huchton, John D. & Foxx, Teralene S.
Partner: UNT Libraries Government Documents Department

Transmission scanning II

Description: From nuclear science symposium; San Francisco, California, USA (14 Nov 1973). Work has been continued on the development of techniques for imaging spatial elemental distributions by means of differential absorption about the K- absorption edge of the particular element Z. A method to correct for spurious effects due to differential absorption in overlying absorber is described. Initial clinical studies of thyroid iodine images on patierts are presented. Application of absorption edge transmission scanning to measurements of Ca cortent in thin in-vitro samples of rat bone is also discussed. An x-ray source with a broad energy spectrum was used. (CH)
Date: January 1, 1973
Creator: Alberi, J.L.; Kraner, H.W.; Bradley-Moore, P. & Atkins, H.L.
Partner: UNT Libraries Government Documents Department

Correlation of radial bone mineral content with total-body calcium in various metabolic disorders

Description: From international conference on bone mineral measurement; Chicago, Illinois, USA (12 Oct 1973). Loss of bone mineral content of the skeleton in osteoporosis and in other metabolic disorders can be measured directly by totalbody neutron activation analysis (TBNAA). The densitometric technique (using monochromatic photons from /sup 125/I) applied to the appendicular skeleton (radius) also reflects the loss of bone mineral in osteoporosis. In the present study the results of these two techniques are compared in 80 patients with various metabolic disorders and in 9 normal contrast subjects. It is apparent that there is good correlation between total body calcium (TBCa) and bone mineral content (BMC) in all groups studied. The correlation was highest in the normal contrast group (0.97) and alcoholics(0.98) and lowest in osteoporotic patients (0.83) and in renal patients on dialysis (0.84). In order to measure the relative deficit in TBCa in individual patients from the absolute calcium measurement, it is necessary to normalize the data for sex, age, and skeletal size. For this purpose an algorithm was used to predict the normal skeletal Ca in each subject bascd on weight, height, sex and age. In similar manner, BMC data were normalized using the same algorithm. These normalization procedures allow both the TBCa and BMC measurement of the radius to be used to compare the Ca deficit in individuals with different metabolic disorders. (auth)
Date: January 1, 1973
Creator: Cohn, S.H.; Ellis, K.J.; Zanzi, I.; Letteri, J.M. & Aloia, J.
Partner: UNT Libraries Government Documents Department

Comparison of heavy charged particles and x-rays for axial tomograpic scanning

Description: Heavy charged particles are applicable to the problem of 3- dimensional reconstruction of electron density distributions of biological samples. The transverse uncertainty in the path of a heavy charged particle due to multiple scattering can be reduced by measuring the entrance and exit positions and angles of the particle. Patient doses for He ions and 80 keV x rays are compared under conditions suitable for imaging the human head. (auth)
Date: September 1, 1975
Creator: Huesman, R.H.; Rosenfeld, A.H. & Solmitz, F.T.
Partner: UNT Libraries Government Documents Department

Final Report for completed IPP Project:"Development of Plasma Ablation for Soft Tissue and Bone Surgery"

Description: ArthroCare is a medical device company that develops, manufactures, and markets an advanced surgical tool, a plasma electro-surgical system for cutting and removing tissue. The hand-held electrical discharge device produces plasma in a biocompatible conductive fluid and tissue to which it is applied during surgery. Its products allow surgeons to operate with increased precision and accuracy, limiting damage to surrounding tissue thereby reducing pain and speeding recovery for the patient. In the past, the design of ArthfoCare's plasma wands has been an empirical undertaking. One goal of this R&amp;D program was to put the phenomena involved on a sound scientific footing, allowing optimization of existing plasma based electro-surgery system technology, and the design and manufacture of new and improved kinds of scalpels, in particular for the surgical cutting of bone. Another important related goal of the program was to develop, through an experimental approach, new plasma wand approaches to the cutting ('shaving') of hard bone tissue. The goals of the CRADA were accomplished - computer models were used to predict important parameters of the plasma discharge and the bone environment, and several different approaches to bone-shaving were developed and demonstrated. The primary goal of the project was to develop and demonstrate an atmospheric-pressure plasma tool that is suitable for surgical use for shaving bone in humans. This goal was accomplished, in fact with several different alternative plasma approaches. High bone ablation speeds were measured. The use of probes ('plasma wand' - the surgical tool) with moving active electrodes was also explored, and there are advantages to this method. Another important feature is that the newly-exposed bone surface have only a very thin necrosis layer; this feature was demonstrated. This CRADA has greatly advanced our understanding of bone removal by atmospheric pressure plasmas in liquid, and puts ArthroCare in a good ...
Date: September 1, 2009
Creator: Brown, Ian
Partner: UNT Libraries Government Documents Department

Age changes in human bone: an overview

Description: The human skeleton steadily changes structure and mass during life because of a variety of internal and external factors. Extracellular substance and bone cells get old, characteristic structural remodeling occurs with age and these age-related changes are important in the discrimination between pathological and physiological changes. Perhaps 20 percent of the bone mass is lost between the fourth and the ninth decades, osteoblasts function less efficiently and gradual loss of bone substance is enhanced by delayed mineralization of an increased surface area of thin and relatively less active osteoid seams. After the fifth decade, osteoclasia and the number of Howship's lacunae increase, and with age, the number of large osteolytic osteocytes increases as the number of small osteocytes declines and empty osteocyte lacunae become more common. The result is greater liability to fracture and diminished healing or replacement of injured bone.
Date: December 3, 1977
Creator: Sharpe, W.D.
Partner: UNT Libraries Government Documents Department