Young Wook Lim

Enhanced Cell Integration to Titanium Alloy by Surface Treatment with Microarc Oxidation: A Pilot Study

Microarc oxidation (MAO) is a surface treatment that provides nanoporous pits, and thick oxide layers, and incorporates calcium and phosphorus into the coating layer of titanium alloy. We presumed such modification on the surface of titanium alloy by MAO would improve the ability of cementless stems to osseointegrate. We therefore compared the in vitro ability of cells to adhere to MAOed titanium alloy to that of two different types of surface modifications: machined and grit-blasted. We performed energy-dispersive x-ray spectroscopy and scanned electron microscopy investigations to assess the structure and morphology of the surfaces. Biologic and morphologic responses to osteoblast cell lines (SaOS-2) were then examined by measuring cell proliferation, cell differentiation (alkaline phosphatase activity), and αvβ3 integrin. The cell proliferation rate, alkaline phosphatase activity, and cell adhesion in the MAO group increased in comparison to those in the machined and grit-blasted groups. The osteoblast cell lines of the MAO group were also homogeneously spread on the surface, strongly adhered, and well differentiated when compared to the other groups. This method could be a reasonable option for treating the surfaces of titanium alloy for better osseointegration.

Comparative Genomic Hybridization Array Analysis and Real-Time PCR Reveals Genomic Copy Number Alteration for Lung Adenocarcinomas

Genomic alterations in lung cancer tissues have been observed in various studies. To analyze the aberrations in the genome of lung cancer patients, we used array comparative genomic hybridization (array CGH) in 15 lung adenocarcinoma (AdC) tissues. Copy number gains and losses in chromosomal regions were detected and corresponding genes were confirmed by real-time polymerase chain reaction (PCR). As for the results, several frequently altered loci, including gain of 16p (46% of samples), were found, and the most common losses were found in 14q32.33 (26% of samples). High-level DNA amplifications (> 0.8 log2 ratio) were detected at 1p, 5p, 7p, 9p, 11p, 11q, 12q, 14q, 16p, 17q, 19q, 20p, 21q, and 22q. A subset of genes, gained or lost, was checked for over- or underrepresentation by means of real-time PCR. The degree of fold change was highest in ECGF1 (22q13.33), HOXA9 (7p15.2), MAFG (17q25.3), TSC2 (16p13.3), and ICAM1 (19p13.2) genes and the 16p chromosome terminal region (16p13.3pter). Taken together, these results show that array CGH could be used as a powerful tool for identification of genomic alteration for lung cancer, and the above-mentioned genes may represent potential candidate genes in the study of lung cancer pathogenesis and diagnosis.

The Otto Aufranc Award: Enhanced Biocompatibility of Stainless Steel Implants by Titanium Coating and Microarc Oxidation

BackgroundStainless steel is one of the most widely used biomaterials for internal fixation devices, but is not used in cementless arthroplasty implants because a stable oxide layer essential for biocompatibility cannot be formed on the surface. We applied a Ti electron beam coating, to form oxide layer on the stainless steel surface. To form a thicker oxide layer, we used a microarc oxidation process on the surface of Ti coated stainless steel. Modification of the surface using Ti electron beam coating and microarc oxidation could improve the ability of stainless steel implants to osseointegrate.Questions/purposesThe ability of cells to adhere to grit-blasted, titanium-coated, microarc-oxidated stainless steel inxa0vitro was compared with that of two different types of surface modifications, machined and titanium-coated, and microarc-oxidated.MethodsWe performed energy-dispersive x-ray spectroscopy and scanning electron microscopy investigations to assess the chemical composition and structure of the stainless steel surfaces and cell morphology. The biologic responses of an osteoblastlike cell line (SaOS-2) were examined by measuring proliferation (cell proliferation assay), differentiation (alkaline phosphatase activity), and attraction ability (cell migration assay).ResultsCell proliferation, alkaline phosphatase activity, migration, and adhesion were increased in the grit-blasted, titanium-coated, microarc-oxidated group compared to the two other groups. Osteoblastlike cells on the grit-blasted, titanium-coated, microarc-oxidated surface were strongly adhered, and proliferated well compared to those on the other surfaces.ConclusionsThe surface modifications we used (grit blasting, titanium coating, microarc oxidation) enhanced the biocompatibility (proliferation and migration of osteoblastlike cells) of stainless steel.Clinical RelevanceThis process is not unique to stainless steel; it can be applied to many metals to improve their biocompatibility, thus allowing a broad range of materials to be used for cementless implants.

Postoperative Mortality and Factors Related to Mortality After Bipolar Hemiarthroplasty in Patients With Femoral Neck Fractures

The purpose of this study was to determine the mortality rate and factors related to mortality in elderly patients with acute and monotraumatic femoral neck fractures. This study included 241 patients with femoral neck fractures after bipolar hemiarthroplasty. We analyzed the mortality rate and the relationship between postoperative mortality and risk factors, such as age, sex, body mass index, the time to surgery, and the Society of Anesthesiologists score. The postoperative mortality rate 1 and 3 years after surgery was 11.2% and 19.5%, respectively. There proved to be a relationship between postoperative mortality and age, the time to surgery, and the Society of Anesthesiologists score. We recommend that surgery should not be delayed, and caution should be exercised for the high-risk group patients.

Single-nucleotide polymorphisms (SNPs) and haplotype analysis in vascular endothelial growth factor (VEGF) gene in the patients with Parkinson disease and lung cancer

The epidemiologic data on smoking in association with Parkinson disease (PD) is puzzling. A lower incidence of smoking-related malignancies, especially lung cancer, has been reported by several studies in the patients with PD. In this study, we investigated polymorphic variations in the vascular endothelial growth factor (VEGF) gene, which has been proposed having a pivotal role in progressive damage of nigral dopaminergic neurons, between Korean patients with 188 PD and 321 lung cancer patients. There were no significant differences in the tested single-nucleotide polymorphisms (SNPs) between patients with PD and lung cancer; however, one haplotype was significantly different in comparisons between the two diseases. These results suggest that VEGF genetic polymorphisms might help understand the low incidence of lung cancer in the patients with PD.

Array CGH Reveals Genomic Aberrations in Human Emphysema

Emphysema is the major component of chronic obstructive pulmonary disease (COPD), which is the fourth leading cause of death in the world. Several epidemiologic studies suggest that genetic factors may have an important role in the pathogenesis of emphysema. We analyzed the gene expression profiles of chromosomal aberrations using array comparative genomic hybridization (array CGH) in 32 patients with emphysema to identify the candidate genes that might be causally involved in the pathogenesis of emphysema. Copy number gains and losses were detected in chromosomal regions, and the corresponding genes were confirmed by real-time polymerase chain reaction. Several frequently altered loci were found, including a gain at 5p15.33 (60% of the study subjects), and a loss at 7q22.1 (31% of the study subjects). DNA gains were identified at a high frequency at 1p, 5p, 11p, 12p, 15q, 17p, 18q, 21q, and 22q, whereas DNA losses were frequently found at 7q and 22q. We found that the fold change levels were highest at the CYP4B1 (1p33), JUN (1p32.1), NOTCH2 (1p12-p11.2), SDHA (5p15.33), KCNQ1 (11p15.5-p15.4), NINJ2 (12p13.33), PCSK6 (15q26.3), ABR (17p13.3), CTDP1 (18q23), RUNX1 (21q22.12) and HDAC10 (22q13.33) gene loci. We also observed losses in the MUC17 (7q22.1), COMT (22q11.21) and GSTT1 (22q11.2) genes. These studies show that array CGH is a useful tool for the identification of gene alterations in cases of emphysema and that the aforementioned genes might represent potential candidate genes involved in the pathogenesis of emphysema.

In vitro effects of mussel-inspired polydopamine coating on Ti6Al4V alloy

Mussel adhesion phenomena in nature have inspired the integration of inorganic hydroxyapatite (HA) crystals within versatile materials. One example is the simple, aqueous, two-step functionalization approach, called polydopamine-assisted hydroxyapatite formation (pHAF), which consists of the chemical activation of material surfaces via polydopamine coating and the growth of hydroxyapatite in a simulated body fluid (SBF). For this study, we anticipated that such a polydopamine coating on the surface of titanium (Ti) alloy would improve the ability of cementless stems to osseointegrate. We compared the in vitro ability of cells to adhere to polydopamine-coated Ti alloy and machined Ti alloy. We performed energy-dispersive x-ray spectroscopy (EDS) and scanning electron microscopy (SEM) investigations to assess the structure and morphology of the surfaces. Biological and morphological responses to osteoblast cell lines (MC3T-E1) were then examined by measuring cell proliferation, cell differentiation (alkaline phosphatase (ALP) activity), and actin filament formation. Real-time polymerase chain reaction (PCR) was used to analyze gene expression for osteocalcin, osteonectin, and osteoprotegerin. Cell proliferation and ALP activity in the polydopamine-coated Ti alloy did not differ statistically compared to the other group. The polydopamine-coated Ti alloy exhibited better apatite formation ability than the untreated alloy, as evidenced by apatite formation after SBF immersion for 10 days. Molecular biological analysis did not differ statistically between the groups. The surface modification of the Ti alloy by coating with polydopamine did not change the biological properties of the Ti alloy. This may make some difficulties for osteogenesis signaling for the cells.