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Dive into the research topics where Roger F. Brown is active.

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Featured researches published by Roger F. Brown.


Acta Biomaterialia | 2008

Mechanical and in vitro performance of 13–93 bioactive glass scaffolds prepared by a polymer foam replication technique

Qiang Fu; Mohamed N. Rahaman; B. Sonny Bal; Roger F. Brown; Delbert E. Day

A polymer foam replication technique was used to prepare porous scaffolds of 13-93 bioactive glass with a microstructure similar to that of human trabecular bone. The scaffolds, with a porosity of 85+/-2% and pore size of 100-500 microm, had a compressive strength of 11+/-1 MPa, and an elastic modulus of 3.0+/-0.5 GPa, approximately equal to the highest values reported for human trabecular bone. The strength was also considerably higher than the values reported for polymeric, bioactive glass-ceramic and hydroxyapatite constructs prepared by the same technique and with the equivalent level of porosity. The in vitro bioactivity of the scaffolds was observed by the conversion of the glass surface to a nanostructured hydroxyapatite layer within 7 days in simulated body fluid at 37 degrees C. Protein and MTT assays of in vitro cell cultures showed an excellent ability of the scaffolds to support the proliferation of MC3T3-E1 preosteoblastic cells, both on the surface and in the interior of the porous constructs. Scanning electron microscopy showed cells with a closely adhering, well-spread morphology and a continuous increase in cell density on the scaffolds during 6 days of culture. The results indicate that the 13-93 bioactive glass scaffolds could be applied to bone repair and regeneration.


Journal of Biomedical Materials Research Part A | 2010

Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. II. In vitro and in vivo biological evaluation

Qiang Fu; Mohamed N. Rahaman; B. Sonny Bal; Lynda F. Bonewald; Keiichi Kuroki; Roger F. Brown

In Part I, the in vitro degradation of bioactivAR52115e glass scaffolds with a microstructure similar to that of human trabecular bone, but with three different compositions, was investigated as a function of immersion time in a simulated body fluid. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. This work is an extension of Part I, to investigate the effect of the glass composition on the in vitro response of osteogenic MLO-A5 cells to these scaffolds, and on the ability of the scaffolds to support tissue infiltration in a rat subcutaneous implantation model. The results of assays for cell viability and alkaline phosphatase activity showed that the slower degrading silicate 13-93 and borosilicate 13-93B1 scaffolds were far better than the borate 13-93B3 scaffolds in supporting cell proliferation and function. However, all three groups of scaffolds showed the ability to support tissue infiltration in vivo after implantation for 6 weeks. The results indicate that the required bioactivity and degradation rate may be achieved by substituting an appropriate amount of SiO2 in 13-93 glass with B2O3, and that these trabecular glass scaffolds could serve as substrates for the repair and regeneration of contained bone defects.


Journal of Biomedical Materials Research Part A | 2009

Effect of borate glass composition on its conversion to hydroxyapatite and on the proliferation of MC3T3‐E1 cells

Roger F. Brown; Mohamed N. Rahaman; Agatha B. Dwilewicz; Wenhai Huang; Delbert E. Day; Yadong Li; B. Sonny Bal

Glasses containing varying amounts of B(2)O(3) were prepared by partially or fully replacing the SiO(2) in silicate 45S5 bioactive glass with B(2)O(3). The effects of the B(2)O(3) content of the glass on its conversion to hydroxyapatite (HA) and on the proliferation of MC3T3-E1 cells were investigated in vitro. Conversion of the glasses to HA in dilute (20 mM) K(2)HPO(4) solution was monitored using weight loss and pH measurements. Proliferation of MC3T3-E1 cells was determined qualitatively by assay of cell density at the glass interface after incubation for 1 day and 3 days, and quantitatively by fluorescent measurements of total DNA in cultures incubated for 4 days. Higher B(2)O(3) content of the glass increased the conversion rate to HA, but also resulted in a greater inhibition of cell proliferation under static culture conditions. For a given mass of glass in the culture medium, the inhibition of cell proliferation was alleviated by using glasses with lower B(2)O(3) content, by incubating the cell cultures under dynamic rather than static conditions, or by partially converting the glass to HA prior to cell culture.


Biofabrication | 2011

Fabrication of 13-93 bioactive glass scaffolds for bone tissue engineering using indirect selective laser sintering.

Krishna C. R. Kolan; Ming C. Leu; Gregory E. Hilmas; Roger F. Brown; Mariano Velez

Bioactive glasses are promising materials for bone scaffolds due to their ability to assist in tissue regeneration. When implanted in vivo, bioactive glasses can convert into hydroxyapatite, the main mineral constituent of human bone, and form a strong bond with the surrounding tissues, thus providing an advantage over polymer scaffold materials. Bone scaffold fabrication using additive manufacturing techniques can provide control over pore interconnectivity during fabrication of the scaffold, which helps in mimicking human trabecular bone. 13-93 glass, a third-generation bioactive material designed to accelerate the bodys natural ability to heal itself, was used in the research described herein to fabricate bone scaffolds using the selective laser sintering (SLS) process. 13-93 glass mixed with stearic acid (as the polymer binder) by ball milling was used as the powder feedstock for the SLS machine. The fabricated green scaffolds underwent binder burnout to remove the stearic acid binder and were then sintered at temperatures between 675 °C and 695 °C. The sintered scaffolds had pore sizes ranging from 300 to 800 µm with 50% apparent porosity and an average compressive strength of 20.4 MPa, which is excellent for non-load bearing applications and among the highest reported for an interconnected porous scaffold fabricated with bioactive glasses using the SLS process. The MTT labeling experiment and measurements of MTT formazan formation are evidence that the rough surface of SLS scaffolds provides a cell-friendly surface capable of supporting robust cell growth.


Acta Biomaterialia | 2013

Evaluation of bone regeneration in implants composed of hollow HA microspheres loaded with transforming growth factor β1 in a rat calvarial defect model.

Hailuo Fu; Mohamed N. Rahaman; Roger F. Brown; Delbert E. Day

Implants that serve simultaneously as an osteoconductive matrix and as a device for local growth factor delivery may be required for optimal bone regeneration in some applications. In the present study, hollow hydroxyapatite (HA) microspheres (106-150μm) in the form of three-dimensional (3-D) scaffolds or individual (loose) microspheres were created using a glass conversion process. The capacity of the implants, with or without transforming growth factor β1 (TGF-β1), to regenerate bone in a rat calvarial defect model was compared. The 3-D scaffolds supported the proliferation and alkaline phosphatase activity of osteogenic MLO-A5 cells in vitro, showing their cytocompatibility. Release of TGF-β1 from the 3-D scaffolds into phosphate-buffered saline ceased after 2-3 days when ∼30% of the growth factor was released. Bone regeneration in the 3-D scaffolds and the individual microspheres increased with time from 6 to 12 weeks, but it was significantly higher (23%) in the individual microspheres than in the 3-D scaffolds (15%) after 12 weeks. Loading with TGF-β1 (5μg per defect) enhanced bone regeneration in the 3-D scaffolds and individual microspheres after 6 weeks, but had little effect after 12 weeks. 3-D scaffolds and individual microspheres with larger HA diameter (150-250μm) showed better ability to regenerate bone. Based on these results, implants composed of hollow HA microspheres show promising potential as an osteoconductive matrix for local growth factor delivery in bone regeneration.


Journal of Biomedical Materials Research Part A | 2014

Angiogenic effects of borate glass microfibers in a rodent model

Yinan Lin; Roger F. Brown; Steven B. Jung; Delbert E. Day

The primary objective of this research was to evaluate the use of bioactive borate-based glass microfibers for angiogenesis in soft tissue repair applications. The effect of these fibers on growth of capillaries and small blood vessels was compared to that of 45S5 silica glass microfibers and sham implant controls. Compressed mats of three types of glass microfibers were implanted subcutaneously in rats and tissues surrounding the implant sites histologically evaluated 2-4 weeks post surgery. Bioactive borate glass 13-93B3 supplemented with 0.4 wt % copper promoted extensive angiogenesis as compared to silica glass microfibers and sham control tissues. The angiogenic responses suggest the copper-containing 13-93B3 microfibers may be effective for treating chronic soft tissue wounds. A second objective was to assess the possible systemic cytotoxicity of dissolved borate ions and other materials released from implanted borate glass microfibers. Cytotoxicity was assessed via histological evaluation of kidney tissue collected from animals 4 weeks after subcutaneously implanting high amounts of the borate glass microfibers. The evaluation of the kidney tissue from these animals showed no evidence of chronic histopathological changes in the kidney. The overall results indicate the borate glass microfibers are safe and effective for soft tissue applications.


Mutation Research\/genetic Toxicology | 1980

Chlorpropamide inhibition of excision repair and postreplication repair of ultraviolet damage in Chinese hamster ovary cells

Roger F. Brown

Chlorpropamide, an oral hypoglycemic agent, was tested for effects on excision repair and postreplication repair of ultraviolet (UV) damage of DNA in CHO-K1 cells. The technique used to measure excision repair involved isopycnic centrifugation of density- and isotopically-labeled DNA. Alkaline sucrose gradient sedimentation was used to monitor postreplication repair. Administration of chlorpropamide at 250 and 1000 microgram/ml after exposure of cultures to 254-nm UV reduced excision repair to 79 and 67%, resp., of control. Post-irradiation treatment with the drug at 1000 microgram/ml inhibited the postreplication gap-filling mechanism almost as effectively as did 2 mM caffeine. The hypoglycemic agent was also found to reduce UV cell survival but did not appear to alter the rate of semiconservative replication. These results suggest that chlorpropamide inhibition of repair processes may potentiate the effects of known mutagenic hazards and may also be responsible for the increased incidence of chromosome aberrations in patients treated with the drug.


Materials Science and Engineering: C | 2013

Evaluation of BSA protein release from hollow hydroxyapatite microspheres into PEG hydrogel

Hailuo Fu; Mohamed N. Rahaman; Roger F. Brown; Delbert E. Day

Implants that simultaneously function as an osteoconductive matrix and as a device for local drug or growth factor delivery could provide an attractive system for bone regeneration. In our previous work, we prepared hollow hydroxyapatite (abbreviated HA) microspheres with a high surface area and mesoporous shell wall and studied the release of a model protein, bovine serum albumin (BSA), from the microspheres into phosphate-buffered saline (PBS). The present work is an extension of our previous work to study the release of BSA from similar HA microspheres into a biocompatible hydrogel, poly(ethylene glycol) (PEG). BSA-loaded HA microspheres were placed in a PEG solution which was rapidly gelled using ultraviolet radiation. The BSA release rate into the PEG hydrogel, measured using a spectrophotometric method, was slower than into PBS, and it was dependent on the initial BSA loading and on the microstructure of the microsphere shell wall. A total of 35-40% of the BSA initially loaded into the microspheres was released into PEG over ~14 days. The results indicate that these hollow HA microspheres have promising potential as an osteoconductive device for local drug or growth factor delivery in bone regeneration and in the treatment of bone diseases.


Journal of Biomedical Materials Research Part A | 2012

In vitro performance of 13‐93 bioactive glass fiber and trabecular scaffolds with MLO‐A5 osteogenic cells

Vernon C. Modglin; Roger F. Brown; Qiang Fu; Mohamed N. Rahaman; Steven B. Jung; Delbert E. Day

This in vitro study was performed to evaluate the ability of two types of porous bioactive glass scaffolds to support the growth and differentiation of an established osteogenic cell line. The two scaffold types tested included 13-93 glass fiber and trabecular-like scaffolds seeded with murine MLO-A5 cells and cultured for intervals of 2 to 12 days. Culture in MTT-containing medium showed metabolically active cells both on the surface and within the interior of the scaffolds. Scanning electron microscopy revealed well-attached cells on both types of scaffolds with a continual increase in cell density over a 6-day period. Protein measurements also showed a linear increase in cell density during the incubation. Activity of alkaline phosphatase, a key indicator of osteoblast differentiation, increased about 10-fold during the 6-day incubation with both scaffold types. The addition of mineralization media to MLO-A5 seeded scaffolds triggered extensive formation of alizarin red-positive mineralized extracellular material, additional evidence of cell differentiation and completion of the final step of bone formation on the constructs. Collectively, the results indicate that the 13-93 glass fiber and trabecular scaffolds promote the attachment, growth, and differentiation of MLO-A5 osteogenic cells and could potentially be used for bone tissue engineering applications.


International Journal of Radiation Applications and Instrumentation. Part B. Nuclear Medicine and Biology | 1991

166Holmium-containing glass for internal radiotherapy of tumors

Roger F. Brown; Lisa C. Lindesmith; Delbert E. Day

Aluminosilicate glass containing the beta-emitter 166Ho was tested for tumor cell killing effectiveness with the BT-20 human mammary carcinoma cell line as a model. Incubation of BT-20 cells with 166Ho glass partially inhibited DNA replication and completely blocked growth in cells located within 1.0 mm of the radioactive fiber. Growth of BT-20 tumor xenografts in nude mice was dramatically inhibited by injection of 2-5 microns fragments of 166Ho glass (200 microCi/tumor). The results suggest that 166Ho glass would be an effective modality for deposition of intense beta- radiation for localized internal radiotherapy of tumors.

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Delbert E. Day

Missouri University of Science and Technology

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Mohamed N. Rahaman

Missouri University of Science and Technology

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Qiang Fu

Missouri University of Science and Technology

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Steven B. Jung

Missouri University of Science and Technology

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Vernon C. Modglin

Missouri University of Science and Technology

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Hailuo Fu

Missouri University of Science and Technology

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Krishna C. R. Kolan

Missouri University of Science and Technology

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Samuel D. Conzone

Missouri University of Science and Technology

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Stanley V. Marshall

Missouri University of Science and Technology

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