Faculty Bibliography

The aim of this collaborative public health study was to engage families, agencies, and programs in reducing secondhand smoke exposure in Central Harlem, New York City. Baseline interviews (n=657) and focus groups (n=4) were conducted with adult members of households with children who had asthma and asthma-like symptoms in the Harlem Children's Zone Asthma Initiative. The interviews concerned the prevalence and determinants of exposure of enrolled children to secondhand smoke. Key findings were that participants: (1) were generally aware of the hazards of secondhand smoke; (2) used strategies to reduce exposure to secondhand smoke in their homes; (3) believed that outdoor pollutants are sometimes just as bad for the health of their children as secondhand smoke; and (4) used smoking to provide stress relief and help diffuse otherwise volatile situations in their homes. The Harlem Smoke-Free Home Campaign was launched in October 2007 based in part on these findings.

This article presents details of processing, characterization and in vitro as well as in vivo evaluations of powder metallurgy processed Ti-13Nb-13Zr samples with different levels of porosity. Sintered samples were characterized for density, crystalline phases (XRD), and microstructure (SEM and EDX). Samples sintered at 1000 degrees C showed the highest porosity level ( approximately 30%), featuring open and interconnected pores ranging from 50 to 100 mum in diameter but incomplete densification. In contrast, samples sintered at 1300 and 1500 degrees C demonstrated high densification with 10% porosity level distributed in a homogeneous microstructure. The different sintering conditions used in this study demonstrated a coherent trend that is increase in temperature lead to higher sample densification, even though densification represents a drawback for bone ingrowth. Cytotoxicity tests did not reveal any toxic effects of the starting and processed materials on surviving cell percentage. After an 8-week healing period in rabbit tibias, the implants were retrieved, processed for nondecalcified histological evaluation, and then assessed by backscattered electron images (BSEI-SEM) and EDX. Bone growth into the microstructure was observed only in samples sintered at 1000 degrees C. Overall, a close relation between newly formed bone and all processed samples was observed.

The aim of this study was to evaluate the biomechanical fixation, bone-to-implant contact, and bone morphology of an ion beam assisted deposition of a 300-500 nm thick Ca- and P-based bioceramic surface on a previously alumina-blasted/acid-etched Ti-6Al-4V implant surface in a dog model. MATERIALS AND METHODS: Thirty-six 4.5 x 11 mm plateau root form implants, control (alumina-blasted/acid-etched-AB/AE) and test groups (AB/AE+300-500 nm bioceramic coating, Nanotite) were placed along a proximal tibia of six beagle dogs remaining for 2 and 4 weeks (n = 3 animals per implantation time). Following euthanization, the implants were torqued to interface fracture at approximately 0.196 radians/sec until a 10% maximum load drop was detected. The implants in bone were nondecalcified processed to approximately 30 microm thickness slides for histomorphologic and bone-to-implant contact (BIC) assessment. Statistical analyses for torque to interface fracture were performed using a mixed model ANOVA, and BIC was evaluated by the chi2 test at 95% level of significance. RESULTS: At 4 weeks, significantly higher torque to interface fracture was observed for the Test implant surface. Histomorphologic analysis showed higher degrees of bone organization for test implants compared to control at 2 and 4 weeks. Significantly higher BIC was observed at 4 weeks compared to 2 weeks (no statistical differences between control and test implants). CONCLUSION: The higher torque to interface fracture and increased bone maturity obtained in this study support that the surface modification comprising a 300-500 nm Ca- and P-based bioceramic coating positively influenced healing around pleateau root form implants.

Thick bioceramic coatings like plasma sprayed hydroxyapatite have been shown to increase the overall tissue response and biomechanical fixation of dental implants. However, the presence and potential fracture of a bone-coating-metallic substrate interface at long times after implantation led these implants to fall from favor in clinical practice. The purpose of this study was to evaluate the biomechanical fixation and biological response of Ca- and P-based, 20-50 nm thickness bioceramic deposition on a previously alumina-blasted/acid-etched Ti-6Al-4V implant surface in a dog model. Cylindrical alumina-blasted/acid-etched (AB/AE) (Control, n = 16), and Nanothickness bioceramic coated AB/AE(Nano, n = 16) implant surfaces were surgically placed in dogs proximal tibia and remained for 2 and 4 weeks in vivo. Following euthanization, the implants-in-bone were mounted in epoxy and pullout at a 0.5 mm/min rate. Following mechanical testing, the specimens were decalcified and processed (Hematoxylin and Eosin) for standard transmitted light microscopy evaluation. Percent bone-to-implant contact (BIC) to the pulled out implant surface was determined through computer software. Statistical analyses were performed by one-way ANOVA at 95% level of significance and Tukey's post-hoc multiple comparisons. No significant differences in pullout force were observed (p > 0.88): 2W Control (212.08 +/- 42.96 N), 2W Nano (224.35 +/- 42.97 N), 4W Control (207.07 +/- 42.97 N), and 4W Nano (190.15 +/- 45.94 N). No significant differences in %BIC were observed (p > 0.94): 2W Control (72.66 +/- 8.51), 2W Nano (69.44 +/- 8.51), 4W Control (70.44 +/- 8.51), and 4W Nano (69.11 +/- 9.09). It is shown that 20-50 nm thickness bioceramic depositions onto previously alumina-blasted/acid-etched substrates did not improve the biomechanical fixation and the BIC at early implantation times, and studies concerning shorter and longer implantation times are recommended for confirmation or before a conclusion can be made.

The objective of this study was to evaluate the morphology and integration status of 30 human retrieved plateau root form implants. Thirty plateau design root form implants that were in function from 8 to 13 years were retrieved from patients due to prosthetic reasons. Following surgical removal, the samples remained in 10% buffered formaline for 7 days. Bone morphology was evaluated by transmitted and polarized light microscopy, and bone-to-implant contact (BIC) histomorphometric assessment was determined through computer software. Irrespective of time in vivo, lamellar bone was observed in close contact with the implant surface and between plateaus. BIC ranged from approximately 20 to approximately 80%. Polarized light microscopy showed a highly directional osteonic morphology between plateaus for most implants. A haversian-like microstructure running perpendicular to and along with the implants' long axis (between plateaus) was observed in regions of cortical and trabecular bone, revealing a unique bone microstructural evolution over time around functionally loaded plateau root form implants.

PURPOSE: The objective of this study was to evaluate the bone response to a nanothickness bioceramic ion beam-assisted deposition (IBAD) on endosteal implants in a canine model. MATERIALS AND METHODS: Alumina-blasted/acid-etched (control) and IBAD-modified (test) implants were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy + ion beam milling, thin-film mode X-ray diffraction, and atomic force microscope. The implants were surgically placed in four dogs' proximal tibiae and remained for 2 and 4 weeks in vivo. Oxytetracycline (10 mg/kg) was administered for bone labeling 48 hours prior to euthanization. Following euthanization, nondecalcified thin sections were prepared for UV and transmitted light microscopy. The amount of bone labeling was evaluated along the length and away from the implant surface by means of a computer software. The % bone-to-implant contact (BIC) was determined for each specimen. One-way analysis of variance at 95% level of significance along with Tukey's post hoc multiple comparisons were utilized for statistical evaluation. The characterization showed Ca- and P-based amorphous coatings with a 20- to 50-nm thickness. RESULTS: In vivo results showed a significant increase in general and site-specific (to 0.5 mm from the implant surface) bone activity for the 4-week test implants compared with the control implants. Bone activity levels decreased as a function of distance from the implant surface for all groups. No significant differences in BIC were observed between groups. CONCLUSIONS: This study showed that both surfaces were biocompatible and osteoconductive and that a time-dependent increase in osteoactivity occurred around the test implants.

BACKGROUND: Lymphedema is a common debilitating sequela of lymph node dissection. Although numerous clinical studies suggest that factors that lead to fibrosis are associated with the development of lymphedema, this relationship has not been proven. The purpose of these experiments was therefore to evaluate lymphatic regeneration in the setting of variable soft-tissue fibrosis. METHODS: A section of mouse tail skin including the capillary and collecting lymphatics was excised. Experimental animals (n = 20) were treated with topical collagen type I gel and a moist dressing, whereas control animals (n = 20) underwent excision followed by moist dressing alone. Fibrosis, acute lymphedema, lymphatic function, gene expression, lymphatic endothelial cell proliferation, and lymphatic fibrosis were evaluated at various time points. RESULTS: Collagen gel treatment significantly decreased fibrosis, with an attendant decrease in acute lymphedema and improved lymphatic function. Tails treated with collagen gel demonstrated greater numbers of lymphatic vessels, more normal lymphatic architecture, and more proliferating lymphatic endothelial cells. These findings appeared to be independent of vascular endothelial growth factor C expression. Decreased fibrosis was associated with a significant decrease in the expression of extracellular matrix components. Finally, decreased soft-tissue fibrosis was associated with a significant decrease in lymphatic fibrosis as evidenced by the number of lymphatic endothelial cells that coexpressed lymphatic and fibroblast markers. CONCLUSIONS: Soft-tissue fibrosis is associated with impairment in lymphatic regeneration and lymphatic function. These defects occur as a consequence of impaired lymphatic endothelial cell proliferation, abnormal lymphatic microarchitecture, and lymphatic fibrosis. Inhibition of fibrosis using a simple topical dressing can markedly accelerate lymphatic repair and promote regeneration of normal capillary lymphatics.

BACKGROUND: Radioprotective modalities such as dose fractionation and pharmacologic agents such as amifostine have been used to protect bone and other types of normal tissue from the damaging effects of ionizing radiation without significantly impacting tumor kill. To better understand the cellular mechanism of radioprotection of osseous tissue, the authors sought to determine the effect of dose fractionation and amifostine on isolated osteoblasts. METHODS: Isolated primary rat calvarial osteoblasts were exposed to single or fractionated doses of ionizing radiation both with and without amifostine pretreatment. Endpoints included cell growth (n = 4), vascular endothelial growth factor production as measured by enzyme-linked immunosorbent assay (n = 3), and early osteodifferentiation as measured by a quantitative alkaline phosphatase assay (n = 3). RESULTS: Both dose fractionation and amifostine protect osteoblasts from the growth inhibitory effects of ionizing radiation. Fractionation but not amifostine was protective for hypoxia-induced vascular endothelial growth factor production (used as a surrogate marker of normal osteoblast function). Neither fractionation nor amifostine could prevent the inhibitory effect of ionizing radiation on normal osteoblast osteodifferentiation as measured by alkaline phosphatase production. CONCLUSIONS: Both dose fractionation and amifostine have valid roles as radioprotectants for osteoblasts and can act in an additive fashion. Radioprotection of cell growth and viability does not necessarily correlate with preservation of normal cellular function. Combination protocols involving dose fractionation and amifostine may be effective in radioprotection of osteoblasts and normal osseous tissue.