The International journal of artificial organs, 2007
To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium ... more To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium (Ti/SA) implants, the osteointegration of Ti/SA rods was studied in the cortical and trabecular bone of 5 young, 5 aged and 5 ovariectomized (OVX) sheep. The characterization of the host bone by transiliac biopsies of the iliac crest showed a progressive rarefaction of trabecular bone in aged and OVX animals when compared to young ones. A significant reduction, both in cortical and trabecular bone, of the osteointegration rate of Ti/SA rods in the presence of estrogen deficiency compared to young animals was observed, while only a minor reduction was observed in aged animals. These results were confirmed by the pushout test in cortical bone. Bone quality affected the biological response of bone to Ti/SA implants in both trabecular and cortical bone; consequently, strategies to maximize the bone osteogenic properties of osteoporotic patients should be adopted.
The International journal of artificial organs, 2003
A new austenitic stainless steel compound, P558, has been widely recognized to have good mechanic... more A new austenitic stainless steel compound, P558, has been widely recognized to have good mechanical properties, excellent potential for corrosion resistance and negligible nickel ion release, making it a promising substitute for more expensive metallic prostheses with limited machinable features. The effect of P558 was studied in vitro and human osteoblast- like cells (MG63) were cultured directly on P558, Ti6Al4V alloy (Ti), and polystyrene (Control) for 72 hours. Osteoblast functions were evaluated by assaying cell proliferation and synthetic activity after 1.25(OH)2D3 stimulation. Results demonstrated that growth of MG63 on P558 was not negatively affected when compared to the Ti and Control groups and showed no alteration in the production of ALP, NO and PICP. Moreover, IL-6 was lower, whereas OC and TGFbeta1 were significantly higher. SEM images revealed that cells proliferated and differentiated on P558 without any alteration in their morphology. The current findings have demo...
The International journal of artificial organs, 2003
The effects of two surfaces with different roughness (Low Roughness, LR: Ra: 5.6-5.9 microm; High... more The effects of two surfaces with different roughness (Low Roughness, LR: Ra: 5.6-5.9 microm; High Roughness, HR: Ra: 21.5-22.5 microm), uncoated and fluorohydroxyapatite(FHA)-coated, were investigated in MG-63 osteoblasts. At 72 hours, cells proliferated on biomaterials more slowly than in the control group (p < 0.0001), the proliferation rate was higher on FHA-coated LR than uncoated HR (p = 0.037). Collagen-I production was positively affected by the LR surface (p = 0.001) as compared to controls, while it was significantly lower (p = 0.0001) in the HR surfaces. Compared to controls, LR and HR surfaces led to enhanced production of TGF-beta1, further improved by FHA (FHA-coated LR: p = 0.007; FHA-coated HR p < 0.0001 respectively). ALP, OC, IL-6 and TNF-alpha levels were not significantly different from the controls. Results suggest that collagen-I production could be useful in predicting the in vivo osteointegration rate of biocompatible biomaterials observed in previous st...
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2005
The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (H... more The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (HA) coatings on Ti6Al4V, in view of their application on noncemented orthopedic implants. Two innovative vacuum plasma sprayed (VPS) coatings, the first of ultrahigh rough and dense Ti (PG60, Ra=74 microm) and the second of ultrahigh rough and dense Ti coated with HA (HPG60, Ra=52 microm), have been developed, and the response of osteoblast-like cells (MG-63) seeded on these new coatings was evaluated in comparison to: a low roughness and sandblasted (Ti/SA, Ra=4 microm) Ti6Al4V surface; Ti medium (TI01, Ra=18 microm), and high (TI60, Ra=40 microm) roughness VPS coatings; and the relative Ti plus HA duplex coatings (HT01, Ra=12 microm and HT60, Ra=36 microm respectively), also obtained by VPS. PG60 coating presented no open porosity, making it dense and potentially intrinsically stronger. Cell adhesion and proliferation on PG60 was similar to those of the smoothest one (Ti/SA) and adhesion on ultrahigh roughness was lower than the medium- and high-roughness coatings, whereas cell proliferation on PG60 was lower than TI60. The HA coating determined significant increases in cell proliferation at medium and high roughness levels when compared to the relative Ti coating, but not compared to the ultrahigh one; all HA-coated surfaces showed a decrease in alkaline phosphatase activity and collagen I production. Surface morphology and the HA coating strongly affected cell behavior. However, ultrahigh values of roughness are not correctly seen by cells, and the presence of HA has no improving effects.
About 20% of the total cells from primary breast tumors could generate palpable tumors in non-obe... more About 20% of the total cells from primary breast tumors could generate palpable tumors in non-obese diabetic severe combined immunodeficient (NOD/SCID) immunocompromised mice. All the tumorigenic cells originate from a normal mammary stem cell. Human mammary stem cells are sensitive to oncogenic mutations and in mouse models they share similarities with breast cancer stem cells (BrCSCs). Tumorigenicity, invasion, progression and metastasization are further BrCSCs properties likely depending on their CD44+/CD24- phenotype. Local invasion and tumor metastasization seem to be facilitated by the epithelial to mesenchymal transition (EMT) program. This program may be reactivated from stable genetic alterations or through exposure of cancer cells to factors present in the surrounding micro-environment, or by an up-regulation of EMT-inducing transcription factors. One main explanation for resistance to treatment by cancer cells is that a rare subpopulation of cells in residual tumors with tumorigenic potential is intrinsically resistant to therapy. Consistent with this hypothesis, in human breast tumors, the subpopulation of tumor-initiating cancer cells with CD44(high)/CD24(low) cell surface-marker profile was found more resistant to cancer therapies (chemo, hormone and radiotherapy) than is the major population of more differentiated breast cancer cells. The reasons for CSC resistance to chemotherapy, hormone therapy and radiotherapy also have been examined and they opened new scenarios for cancer therapy.
The aim of this study was to assess the capability of ultrasonography and densitometry to predict... more The aim of this study was to assess the capability of ultrasonography and densitometry to predict the mechanical competence of cortical bone in healthy and osteopenic rats, respectively. Thirty 10-month-old Sprague-Dawley retired breeder female rats were used and randomized into three groups of 10 animals each. A group underwent bilateral ovariectomy by dorsal approach (Ovx), another group underwent a simulated ovariectomy (Sham-Ovx), and the last group served as a sham-aged control group (Control). Sixteen weeks after surgery, the animals were euthanized and the femurs of each rat excised for ultrasonographic and densitometric measurements, and mechanical analyses. The Ovx Group had a significantly decreased amplitude dependent speed of sound (AD-SoS-about 7-8%) when compared to the other groups (p&lt;0.0005). For Ovx animals compared with Sham-Ovx and Control rats, significant decreases in densitometric data were observed (6-13%), as well as significant decreases in femoral Max. Load (about 18%) and flexural rigidity (about 30%). The best correlation (R2=0.55, p&lt;0.0005) found was between SoS and femoral shaft bone mineral density (SBMD). The regression coefficient R2 increased when power-law fits were used, particularly from 0.34 (p&lt;0.001) to 0.36 (p&lt;0.0005) in the correlation between SoS and Max. Load and from 0.21 (p&lt;0.05) to 0.25 (p&lt;0.01) in the correlation between SBMD and Max. Load. The ability of QUS or DXA to accurately predict the actual mechanical characteristics of bone, and in particular bone elasticity, remained relatively poor and the improvement of the power-law model did not describe exhaustively the relationships between the variables tested. The DXA and QUS capability to discriminate between ovariectomized and non-ovariectomized rats did not improve when tested together.
The International journal of artificial organs, 2007
To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium ... more To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium (Ti/SA) implants, the osteointegration of Ti/SA rods was studied in the cortical and trabecular bone of 5 young, 5 aged and 5 ovariectomized (OVX) sheep. The characterization of the host bone by transiliac biopsies of the iliac crest showed a progressive rarefaction of trabecular bone in aged and OVX animals when compared to young ones. A significant reduction, both in cortical and trabecular bone, of the osteointegration rate of Ti/SA rods in the presence of estrogen deficiency compared to young animals was observed, while only a minor reduction was observed in aged animals. These results were confirmed by the pushout test in cortical bone. Bone quality affected the biological response of bone to Ti/SA implants in both trabecular and cortical bone; consequently, strategies to maximize the bone osteogenic properties of osteoporotic patients should be adopted.
The International journal of artificial organs, 2003
A new austenitic stainless steel compound, P558, has been widely recognized to have good mechanic... more A new austenitic stainless steel compound, P558, has been widely recognized to have good mechanical properties, excellent potential for corrosion resistance and negligible nickel ion release, making it a promising substitute for more expensive metallic prostheses with limited machinable features. The effect of P558 was studied in vitro and human osteoblast- like cells (MG63) were cultured directly on P558, Ti6Al4V alloy (Ti), and polystyrene (Control) for 72 hours. Osteoblast functions were evaluated by assaying cell proliferation and synthetic activity after 1.25(OH)2D3 stimulation. Results demonstrated that growth of MG63 on P558 was not negatively affected when compared to the Ti and Control groups and showed no alteration in the production of ALP, NO and PICP. Moreover, IL-6 was lower, whereas OC and TGFbeta1 were significantly higher. SEM images revealed that cells proliferated and differentiated on P558 without any alteration in their morphology. The current findings have demo...
The International journal of artificial organs, 2003
The effects of two surfaces with different roughness (Low Roughness, LR: Ra: 5.6-5.9 microm; High... more The effects of two surfaces with different roughness (Low Roughness, LR: Ra: 5.6-5.9 microm; High Roughness, HR: Ra: 21.5-22.5 microm), uncoated and fluorohydroxyapatite(FHA)-coated, were investigated in MG-63 osteoblasts. At 72 hours, cells proliferated on biomaterials more slowly than in the control group (p < 0.0001), the proliferation rate was higher on FHA-coated LR than uncoated HR (p = 0.037). Collagen-I production was positively affected by the LR surface (p = 0.001) as compared to controls, while it was significantly lower (p = 0.0001) in the HR surfaces. Compared to controls, LR and HR surfaces led to enhanced production of TGF-beta1, further improved by FHA (FHA-coated LR: p = 0.007; FHA-coated HR p < 0.0001 respectively). ALP, OC, IL-6 and TNF-alpha levels were not significantly different from the controls. Results suggest that collagen-I production could be useful in predicting the in vivo osteointegration rate of biocompatible biomaterials observed in previous st...
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2005
The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (H... more The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (HA) coatings on Ti6Al4V, in view of their application on noncemented orthopedic implants. Two innovative vacuum plasma sprayed (VPS) coatings, the first of ultrahigh rough and dense Ti (PG60, Ra=74 microm) and the second of ultrahigh rough and dense Ti coated with HA (HPG60, Ra=52 microm), have been developed, and the response of osteoblast-like cells (MG-63) seeded on these new coatings was evaluated in comparison to: a low roughness and sandblasted (Ti/SA, Ra=4 microm) Ti6Al4V surface; Ti medium (TI01, Ra=18 microm), and high (TI60, Ra=40 microm) roughness VPS coatings; and the relative Ti plus HA duplex coatings (HT01, Ra=12 microm and HT60, Ra=36 microm respectively), also obtained by VPS. PG60 coating presented no open porosity, making it dense and potentially intrinsically stronger. Cell adhesion and proliferation on PG60 was similar to those of the smoothest one (Ti/SA) and adhesion on ultrahigh roughness was lower than the medium- and high-roughness coatings, whereas cell proliferation on PG60 was lower than TI60. The HA coating determined significant increases in cell proliferation at medium and high roughness levels when compared to the relative Ti coating, but not compared to the ultrahigh one; all HA-coated surfaces showed a decrease in alkaline phosphatase activity and collagen I production. Surface morphology and the HA coating strongly affected cell behavior. However, ultrahigh values of roughness are not correctly seen by cells, and the presence of HA has no improving effects.
About 20% of the total cells from primary breast tumors could generate palpable tumors in non-obe... more About 20% of the total cells from primary breast tumors could generate palpable tumors in non-obese diabetic severe combined immunodeficient (NOD/SCID) immunocompromised mice. All the tumorigenic cells originate from a normal mammary stem cell. Human mammary stem cells are sensitive to oncogenic mutations and in mouse models they share similarities with breast cancer stem cells (BrCSCs). Tumorigenicity, invasion, progression and metastasization are further BrCSCs properties likely depending on their CD44+/CD24- phenotype. Local invasion and tumor metastasization seem to be facilitated by the epithelial to mesenchymal transition (EMT) program. This program may be reactivated from stable genetic alterations or through exposure of cancer cells to factors present in the surrounding micro-environment, or by an up-regulation of EMT-inducing transcription factors. One main explanation for resistance to treatment by cancer cells is that a rare subpopulation of cells in residual tumors with tumorigenic potential is intrinsically resistant to therapy. Consistent with this hypothesis, in human breast tumors, the subpopulation of tumor-initiating cancer cells with CD44(high)/CD24(low) cell surface-marker profile was found more resistant to cancer therapies (chemo, hormone and radiotherapy) than is the major population of more differentiated breast cancer cells. The reasons for CSC resistance to chemotherapy, hormone therapy and radiotherapy also have been examined and they opened new scenarios for cancer therapy.
The aim of this study was to assess the capability of ultrasonography and densitometry to predict... more The aim of this study was to assess the capability of ultrasonography and densitometry to predict the mechanical competence of cortical bone in healthy and osteopenic rats, respectively. Thirty 10-month-old Sprague-Dawley retired breeder female rats were used and randomized into three groups of 10 animals each. A group underwent bilateral ovariectomy by dorsal approach (Ovx), another group underwent a simulated ovariectomy (Sham-Ovx), and the last group served as a sham-aged control group (Control). Sixteen weeks after surgery, the animals were euthanized and the femurs of each rat excised for ultrasonographic and densitometric measurements, and mechanical analyses. The Ovx Group had a significantly decreased amplitude dependent speed of sound (AD-SoS-about 7-8%) when compared to the other groups (p&lt;0.0005). For Ovx animals compared with Sham-Ovx and Control rats, significant decreases in densitometric data were observed (6-13%), as well as significant decreases in femoral Max. Load (about 18%) and flexural rigidity (about 30%). The best correlation (R2=0.55, p&lt;0.0005) found was between SoS and femoral shaft bone mineral density (SBMD). The regression coefficient R2 increased when power-law fits were used, particularly from 0.34 (p&lt;0.001) to 0.36 (p&lt;0.0005) in the correlation between SoS and Max. Load and from 0.21 (p&lt;0.05) to 0.25 (p&lt;0.01) in the correlation between SBMD and Max. Load. The ability of QUS or DXA to accurately predict the actual mechanical characteristics of bone, and in particular bone elasticity, remained relatively poor and the improvement of the power-law model did not describe exhaustively the relationships between the variables tested. The DXA and QUS capability to discriminate between ovariectomized and non-ovariectomized rats did not improve when tested together.
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