The Delivery Model of Perceived Medical Service Quality Based on Donabedian's Framework.

ABSTRACT: The implementation of the National Health Insurance has transformed the medical care landscape in Taiwan, rendering perceived medical service quality (PMSQ) and patient satisfaction significant focal points in medical care management. Past studies mostly focused on the technical aspects of medical care services, while overlooking the patients' perception of services and the delivery process of PMSQ in the medical care experience. This study integrated the theoretical framework of the Donabedian SPO model and the SERVQUAL questionnaire. The survey was conducted among the outpatients of three types of medical institutions in northern Taiwan: academic medical centers, metropolitan hospitals, and local community hospitals. A total of 400 questionnaires were collected, and 315 valid questionnaires remained after eliminating the incomplete ones. This study established a PMSQ delivery model to explore patients' perceptions of medical service quality. It was found that the variable, Assurance, could deliver the PMSQ and enhance the Medical outcome (MO), while improving the variable, Tangible, in medical institutions could not significantly enhance the MO. These findings emphasize the importance of healthcare institutions prioritizing the professional background, demeanor of their healthcare staff, treatment methods, and processes over tangible elements.

Synergistic Effect of Thermoresponsive and Photocuring Methacrylated Chitosan-Based Hybrid Hydrogels for Medical Applications.

The thermoresponsive drug-loaded hydrogels have attracted widespread interest in the field of medical applications due to their ease of delivery to structurally complex tissue defects. However, drug-resistant infections remain a challenge, which has prompted the development of new non-antibiotic hydrogels. To this end, we prepared chitosan-methacrylate (CTSMA)/gelatin (GEL) thermoresponsive hydrogels and added natural phenolic compounds, including tannic acid, gallic acid, and pyrogallol, to improve the efficacy of hydrogels. This hybrid hydrogel imparted initial crosslinking at physiological temperature, followed by photocuring to further provide a mechanically robust structure. Rheological analysis, tensile strength, antibacterial activity against E. coli, S. aureus, P. gingivalis, and S. mutans, and L929 cytotoxicity were evaluated. The experimental results showed that the hybrid hydrogel with CTSMA/GEL ratio of 5/1 and tannic acid additive had a promising gelation temperature of about 37 °C. The presence of phenolic compounds not only significantly (p < 0.05) enhanced cell viability, but also increased the tensile strength of CTSMA/GEL hybrid hydrogels. Moreover, the hydrogel containing tannic acid revealed potent antibacterial efficacy against four microorganisms. It was concluded that the hybrid hydrogel containing tannic acid could be a potential composite material for medical applications.

Antibacterial ability and osteogenic activity of polyphenol-tailored calcium silicate bone cement.

Calcium silicate-based cement (CSC) has attracted much interest because of its favourable osteogenic effect that supports its clinical use. Although CSC has antibacterial activity, this activity still needs to be improved when used in an infected bone defect. Natural polyphenols have been considered antimicrobial reagents. To this end, three different types of polyphenols (gallic acid (GA), pyrogallol (PG) and tannic acid (TA)) with different concentrations as a liquid phase were mixed with bioactive calcium silicate to enhance the antibacterial activity of CSC. The setting time, antibacterial activity, and osteogenic activity of CSC were studied. Evaluation of antibacterial ability and reactive oxygen species (ROS) was performed using Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria, while a human osteoblast-like cell line (MG63) was used to examine osteogenic activity. The experimental results showed that the addition of polyphenols did not remarkably affect the phase composition and morphology of CSC, but changed the setting time and diametral tensile strength. At the same concentration of 1 wt%, the setting time of TA (21 min) was significantly shorter than that of PG (26 min) and GA (68 min), and was indistinguishable from the control cement (20 min). GA had a significantly higher antioxidant activity than PG and TA. As expected, higher concentrations of polyphenols had a more positive impact on ROS generation. More importantly, the incorporation of polyphenols greatly enhanced the antibacterial activity of CSC against E. coli and S. aureus, but had little effect on the in vitro osteogenic activity of MG63 cells and the cytotoxicity of L929 cells. It was concluded that among the three phenolic compounds, the optimal concentration of the liquid phase in the hybrid cement was 5 wt% TA in terms of setting time, strength, antibacterial activity and in vitro osteogenic activity.

Patient and surgeon factors contributing to bailout cholecystectomies: a single-institutional retrospective analysis.

BACKGROUND: Laparoscopic cholecystectomies continue to pose trouble for surgeons in the face of severe inflammation. In the advent of inability to perform an adequate dissection, a "bailout cholecystectomy" is advocated. Conversion to open or subtotal cholecystectomy is among the standard bailout procedures in such instances. METHODS: We performed a retrospective single institution review from January 2016 to August 2019. All patients who underwent a cholecystectomy were included, while those with a concurrent operation, malignancy, planned as an open cholecystectomy, or performed by a low volume surgeon were excluded. Patient characteristics, operative reports, and outcomes were collected, as were surgeon characteristics such as years of experience, case volume, and bailout rate. Univariable and multivariable analysis were performed. RESULTS: 2458 (92.6%) underwent laparoscopic total cholecystectomy (LTC) and 196 (7.4%) underwent a bailout cholecystectomy (BOC). BOC patients tended to be older (p < 0.001), male (p < 0.001), have a longer duration of symptoms (p < 0.001), and higher ASA class (p < 0.001). They also had more signs of biliary inflammation, as evidenced by increased leukocytosis (p < 0.001), tachycardia (p < 0.001), bilirubinemia (p = 0.003), common bile duct dilation (p < 0.001), and gallbladder wall thickening (p < 0.001). The BOC cohort also had increased rates of complications, including bile leak (16%, p < 0.001), retained stone (5.1%, p = 0.005), operative time (114 min vs 79 min, p < 0.001), and secondary interventions (22.7%, p < 0.001). Male gender (aOR = 2.8, p < 0.001), preoperative diagnosis of acute cholecystitis (aOR = 2.2, p = 0.032), right upper quadrant tenderness (aOR = 3.0, p = 0.008), Asian race (aOR = 2.7, p = 0.014), and intraoperative adhesions (aOR = 13.0, p < 0.001) were found to carry independent risk for BOC. Surgeon bailout rate ≥ 7% was also found to be an independent risk factor for conversion to BOC. CONCLUSIONS: Male gender, signs of biliary inflammation (tachycardia, leukocytosis, dilated CBD, and diagnosis of acute cholecystitis), as well as surgeon bailout rate of 7% were independent risk factors for BOC.

In vitro comparisons of microscale and nanoscale calcium silicate particles.

Calcium silicate (CaSi) materials have been used for bone repair and generation due to their osteogenic properties. Tailoring the surface chemistry and structure of CaSi can enhance its clinical performance. There is no direct comparison between microscale and nanoscale CaSi particles. Therefore, this article aimed to compare and evaluate the surface chemistry, structure, and in vitro properties of microscale CaSi (µCaSi) and nanoscale CaSi (nCaSi) particles synthesized by the sol-gel method and precipitation method, respectively. As a result, the semi-crystalline µCaSi powders were assemblies of irregular microparticles containing a major ß-dicalcium silicate phase, while the amorphous nCaSi powders consisted of spherical particles with a size of 100 nm. After soaking in a Tris-HCl solution, the amount of Si ions released from nCaSi was higher than that released from µCaSi, but there was no significant difference in Ca ion release between the two CaSi particles. Compared to microscale CaSi (µCaSi), nanoscale CaSi (nCaSi) significantly enhanced the growth and differentiation of human mesenchymal stem cells (hMSC) and inhibited the function of RAW 264.7 macrophages. In the case of antibacterial activity against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), nanoscale nCaSi displayed a higher bacteriostatic ratio, a greater growth inhibition zone and more reactive oxygen species (ROS) production than microscale µCaSi. The conclusion is that nanoscale CaSi had greater antibacterial and osteogenic activity compared to microscale CaSi. Next generation CaSi-based materials with unique properties are emerging to meet specific clinical needs.

Metagenomic analysis of DNA viruses from posttransplant lymphoproliferative disorders.

Posttransplant lymphoproliferative disorders (PTLDs), 50%-80% of which are strongly associated with Epstein-Barr virus (EBV), carry a high morbidity and mortality. Most clinical/epidemiological/tumor characteristics do not consistently associate with worse patient survival, so our aim was to identify if other viral genomic characteristics associated better with survival. We extracted DNA from stored paraffin-embedded PTLD tissues at our center, identified viral sequences by metagenomic shotgun sequencing (MSS), and analyzed the data in relation to clinical outcomes. Our study population comprised 69 PTLD tissue samples collected between 1991 and 2015 from 60 subjects. Nucleotide sequences from at least one virus were detected by MSS in 86% (59/69) of the tissues (EBV in 61%, anelloviruses 52%, gammapapillomaviruses 14%, CMV 7%, and HSV in 3%). No viruses were present in higher proportion in EBV-negative PTLD (compared to EBV-positive PTLD). In univariable analysis, death within 5 years of PTLD diagnosis was associated with anellovirus (P = 0.037) and gammapapillomavirus (P = 0.036) detection by MSS, higher tissue qPCR levels of the predominant human anellovirus species torque teno virus (TTV; P = 0.016), T cell type PTLD, liver, brain or bone marrow location. In multivariable analyses, T cell PTLD (P = 0.006) and TTV PCR level (P = 0.012) remained significant. In EBV-positive PTLD, EBNA-LP, EBNA1 and EBNA3C had significantly higher levels of nonsynonymous gene variants compared to the other EBV genes. Multiple viruses are detectable in PTLD tissues by MSS. Anellovirus positivity, not EBV positivity,was associated with worse patient survival in our series. Confirmation and extension of this work in larger multicenter studies is desirable.

Dopant-dependent tailoring of physicochemical and biological properties of calcium silicate bone cements.

BACKGROUND: To enhance calcium silicate cements (CSCs) towards a specific clinical application of endodontics and vertebroplasty, the addition of oxide dopants (Bi2O3, SrO, ZnO, ZrO2) as radiopacifiers allows for tailoring of material properties. OBJECTIVE: Effects of oxide dopants on the in vitro physicochemical properties and osetogenic activity of CSCs were investigated. METHODS: The setting time, compressive strength, radiopacity, and osteogenic ability of the cements were evaluated. The ability of cement samples to support MG63 attachment, proliferation, differentiation, and mineralization was assessed. RESULTS: The greater the oxide amount, the higher the setting time and radiopacity were in the cement. The effect of the oxide dopants on radiopacity followed the order Bi2O3 > ZrO2 > SrO > ZnO, which were greater than 3 mm of Al recommended by ISO 6876: 2001 standards. ZrO2 could reinforce compressive strength of the control cement, while ZnO remarkably reduced the strength. The adverse effect of Bi2O3 and ZrO2 was found on cell number, alkaline phosphatase (ALP) activity and mineralization of MG63 cells. SrO supported cell attachment, proliferation and differentiation, and significantly increased cellular mineralization compared to the control. CONCLUSIONS: The 20 wt% SrO-containing CSCs may be applied to endodontic treatment and vertebroplasty surgery.

[Association between Severity of Scrub Typhus and Serum Procalcitonin Level].

Objective To explore the association between the severity of scrub typhus (ST) and the serum procalcitonin (PCT) level. Methods The clinical data of 58 ST patients who were treated in the First Affiliated Hospital of Xiamen University and confirmed by Xiamen Municipal Center for Disease Prevention and Control (CDC) from January 2016 to October 2017,were retrospectively analyzed. According to clinical manifestations and related laboratory tests,these patients were divided into four grades:Ⅰ,Ⅱ,Ⅲ,and Ⅳ. These four grade groups were compared in terms of age,interval from symptom onset to hospital presentation,hospitalization days,and serum PCT level. Results These 58 patients were divided into four grade groups:grade Ⅰ group (n=17),grade Ⅱ group (n=17),grade Ⅲ group (n=11),and grade Ⅳ group (n=13). No significant difference was found among these four groups in terms of age (F=0.618,P=0.606),interval from symptom onset to hospital presentation (F=1.744,P=0.169),and hospitalization days (F=0.398,P=0.755).However,the median serum PCT level in the grade Ⅳ patients[2.60(1.33,61.08)ng/ml] was significantly higher than those in grade I[0.24(0.10,0.33)ng/ml;Z=-4.63,P=0.000], grade Ⅱ[0.29(0.21,0.51)ng/ml;Z=-4.63,P=0.000], and grade Ⅲ[1.33(0.89,2.41)ng/ml;Z=-2.09,P=0.040].The median serum PCT level in the grade Ⅲ patients was also significantly higher than grade Ⅰ (Z=-4.16,P=0.000)and grade Ⅱ(Z=-3.83,P=0.000).There was no significant difference between the grade Ⅰ patients and grade Ⅱ patients(Z=-1.37,P=0.170).There was significantly positive correlation between PCT level and the severity of ST (r=0.804,P=0.000).Conclusion There is positive correlation between serum PCT level and the severity of ST,and serum PCT level may be a biomarker in assessing the severity of ST.

Effects of Surface Conditions of Titanium Dental Implants on Bacterial Adhesion.

OBJECTIVE: The study is to evaluate the effect of surface roughness of titanium implants on bacterial adhesion and then to investigate the efficacy of the three cleaning treatments for bacterial removal in titanium surfaces. BACKGROUND DATA: Although surface debridement is the basic element for treatment of peri-implantitis to reduce bacterial adhesion, adjunctive therapies such as antiseptics and laser debridement have been proposed to improve the nonsurgical treatment options of the peri-implant infection. METHODS: Titanium specimens were divided into five groups: No. 1200 grit sandpaper polishing (Grit), 50 µm (SB50), 100 µm (SB100), and 250 µm Al2O3 sandblasting (SB250), and sandblasting, large-grit, and acid-etching (SLA). Surface roughness (Ra), contact angle, and surface morphology were examined. The subsequent adhesion of Escherichia coli on the different substrates was assayed. After 8 h of bacterial culture, three different cleaning treatments, including plastic curettage, air-powder abrasive system, and Er:YAG laser debridement, were applied on the specimens. RESULTS: The Ra value changed from the lower value of 0.2 µm for the Grit group to the significantly higher value of 2.7 µm for the SB250 group, indicating a significant difference from the SLA group (2.0 µm). The average contact angle of SLA (101°) was significantly higher than the other groups. No significant difference in E. coli bacterial adhesion was found among the all roughened groups, except the SB50 and SB250 groups at 12 h of culture. The use of three cleaning treatments did not induce significant surface alterations. However, the E. coli adhesion was significantly reduced in the air-powder abrasive system and laser debridement in comparison with that treated with the plastic curettage. CONCLUSIONS: Laser debridement could be a useful cleaning method for peri-implantitis therapy.

CD47 blockade reduces ischemia-reperfusion injury and improves outcomes in a rat kidney transplant model.

BACKGROUND: Ischemia-reperfusion injury (IRI) significantly contributes to delayed graft function and inflammation, leading to graft loss. Ischemia-reperfusion injury is exacerbated by the thrombospondin-1-CD47 system through inhibition of nitric oxide signaling. We postulate that CD47 blockade and prevention of nitric oxide inhibition reduce IRI in organ transplantation. METHODS: We used a syngeneic rat renal transplantation model of IRI with bilaterally nephrectomized recipients to evaluate the effect of a CD47 monoclonal antibody (CD47mAb) on IRI. Donor kidneys were flushed with CD47mAb OX101 or an isotype-matched control immunoglobulin and stored at 4°C in University of Wisconsin solution for 6 hr before transplantation. RESULTS: CD47mAb perfusion of donor kidneys resulted in marked improvement in posttransplant survival, lower levels of serum creatinine, blood urea nitrogen, phosphorus and magnesium, and less histological evidence of injury. In contrast, control groups did not survive more than 5 days, had increased biochemical indicators of renal injury, and exhibited severe pathological injury with tubular atrophy and necrosis. Recipients of CD47mAb-treated kidneys showed decreased levels of plasma biomarkers of renal injury including Cystatin C, Osteopontin, Tissue Inhibitor of Metalloproteinases-1 (TIMP1), ß2-Microglobulin, Vascular Endothelial Growth Factor A (VEGF-A), and clusterin compared to the control group. Furthermore, laser Doppler assessment showed higher renal blood flow in the CD47mAb-treated kidneys. CONCLUSION: These results provide strong evidence for the use of CD47 antibody-mediated blockade to reduce IRI and improve organ preservation for renal transplantation.

Heterozygous knockout of transforming growth factor-ß1 protects Dahl S rats against high salt-induced renal injury.

The present study employed a zinc-finger nuclease strategy to create heterozygous knockout (KO) rats for the transforming growth factor-ß1 (Tgfb1) gene on the Dahl SS/Jr genetic background (TGF-ß1(+/-) Dahl S). Intercrossing TGF-ß1(+/-) rats did not produce any homozygous KO rats (66.4% +/-, 33.6% +/+), indicating that the mutation is embryonic lethal. Six-week-old wild-type (WT) littermates and TGF-ß1(+/-) Dahl S rats were fed a 0.4% (low salt, LS) or 8% NaCl (high salt, HS) diet for 5 wk. Renal cortical expression of TGF-ß1, urinary TGF-ß1 excretion, proteinuria, glomerular injury and tubulointerstitial fibrosis, and systolic blood pressure were similar in WT and TGF-ß1(+/-) Dahl S rats maintained on the LS diet. The expression and urinary excretion of TGF-ß1 increased to a greater extent in WT than in TGF-ß1(+/-)Dahl S rats fed an HS diet for 1 wk. Systolic blood pressure rose by the same extent to 235 ± 2 mmHg in WT and 239 ± 4 mmHg in TGF-ß1(+/-) Dahl S rats fed a HS diet for 5 wk. However, urinary protein excretion was significantly lower in TGF-ß1(+/-) Dahl S than in the WT animals. The degree of glomerular injury and renal cortical and outer medullary fibrosis was markedly less in TGF-ß1(+/-) than in WT rats. These findings suggest that the loss of one copy of the TGF-ß1 gene blunts the increase in renal TGF-ß1 protein expression and slows the progression of proteinuria, glomerulosclerosis, and renal interstitial fibrosis in Dahl S rats fed an HS diet independently of changes in blood pressure.

Dentin surface modification using the Er,Cr:YSGG laser and a meshwork mask: light and SEM microscopic observations.

OBJECTIVE: We have developed a novel technique of utilizing a stainless steel meshwork mask during treatment of dentin with the Er,Cr:YSGG laser. It is the purpose of this study to observe the surface modifications produced by this method. BACKGROUND DATA: Many techniques have been developed to facilitate bonding of various materials to dentin. However, an optimal bond has not yet been achieved. METHODS: Four teeth ground to dentin were randomly assigned to two groups. Group 1: Er,Cr:YSGG laser treatment; and Group 2: laser treatment while a 100 µm aperture stainless steel mesh was situated over the dentinal surface. RESULTS: Group 1 samples appeared rugged but relatively flat. Group 2 samples presented a surface with uniformly aligned craters ∼100 µm wide, 150 µm deep. CONCLUSIONS: Masking the dentinal surface with a stainless steel mesh during laser irradiation produces a surface texture that appears to facilitate mechanical retention.

TNFR1-deficient mice display altered blood pressure and renal responses to ANG II infusion.

The hypothesis that TNF receptor 1-deficient (TNFR1(-/-)) mice display blood pressure (BP) and renal functional responses that differ from wild-type (WT) mice was tested in an angiotensin II (ANG II)-dependent model of hypertension. Basal systolic BP (SBP), mean arterial pressure, diastolic BP, heart rate (HR), and pulse pressure were similar in WT and TNFR1(-/-) mice. Infusion of ANG II for 7 days elevated SBP to a greater extent in TNFR1(-/-) compared with WT mice; pulse pressure was also elevated in TNFR1(-/-). HR decreased in TNFR1(-/-) mice infused with ANG II, an effect prominent on day 1. Basal urinary albumin excretion was similar in WT and TNFR1(-/-) mice but was higher in TNFR1(-/-) in response to ANG II infusion. Water intake and urine volume were increased by ANG II infusion; this increase was higher in TNFR1(-/-) vs. WT mice, whereas body weight and food intake were unaffected. Baseline creatinine clearance (Ccr), urinary sodium excretion, and fractional excretion of sodium (FE(Na)%) were similar in vehicle-treated WT and TNFR1(-/-) mice. ANG II infusion for 7 days increased Ccr and filtered load of sodium in TNFR1(-/-) but not WT mice, whereas it elicited an increase in FE(Na)% and urinary sodium excretion in WT but not TNFR1(-/-) mice. ANG II also inhibited renal TNFR1 mRNA accumulation while increasing that of TNFR2. These findings indicate deletion of TNFR1 is associated with an exacerbated SBP response, decrease in HR, and altered renal function in ANG II-dependent hypertension.

Preparation and properties of gold nanoparticle-electrodeposited titanium substrates with Arg-Gly-Asp-Cys peptides.

Titanium metal has good biocompatibility, superior mechanical properties and excellent corrosion resistance. Like most metals, however, it exhibits poor bioactive properties and fails to bond to bone tissue. To improve its bioactivity, bioactive molecules, such as peptides, can be grafted onto titanium surfaces. In order to do this, the first step may be to establish a stable and compatible linking layer on the titanium surface. In this study, we used electrochemical methods to deposit gold (Au) nanoparticles onto titanium substrates, to which we then grafted arginine-glycine-asparagine-cysteine (RGDC) peptides by thiolate covalent coupling. Properties of electrodeposited Au nanoparticles were evaluated using a variety of techniques, including microstructural, chemical and electrochemical measurements. The biological responses of the RGDC-grafted Ti substrates were evaluated using MG3 human osteoblast-like cells. The results of thin-film X-ray diffraction (TFXRD) and scanning electron microscopy (SEM) indicated the polycrystalline orientation of Au nanoparticles deposited on the titanium surfaces with high density and controllable particle size. The RGDC peptide could be covalently bonded to Au-deposited Ti substrates via Au-thiolate species, as expected. Cell morphology showed that, on RGDC-immobilized titanium with Au particles, MG63 cells attached and spread more rapidly than on Ti substrates either without peptide or with direct loading of the peptide. Immunostaining for focal adhesion kinase (FAK) demonstrated that RGDC enhanced cell attachment. The present method for the formation of Au nanoparticles may serve as an alternative route for bioactive molecule immobilization on Ti implants.

Effect of Er,Cr:YSGG laser parameters on shear bond strength and microstructure of dentine.

OBJECTIVE: The objective of this study was to investigate the effect of different Er,Cr:YSGG laser parameters on the morphology of irradiated dentine and the shear bond strength between resin composites and irradiated dentine. MATERIALS AND METHODS: Dentine specimens prepared from extracted human third molars were randomly assigned to six groups, including one receiving phosphoric acid etching, and five others with different laser parameters: 5 W for 30 sec, 2.5 W for 30 sec, 2.5 W for 60 sec, 1.5 W for 30 sec, and 1.5 W for 100 sec. Surface morphology was examined using a scanning electron microscope (SEM). Average roughness (Ra) was determined with a profilometer. Bonding of resin composites to the dentine specimens was tested in shear mode. RESULTS: The dentine surfaces irradiated by the Er,Cr:YSGG laser showed a scaly and rugged appearance and open dentinal tubules without smear layer production. The 5-W-irradiated group had the highest roughness value (p < 0.05). One-way ANOVA revealed that the shear bond strength of resin composites to the laser-irradiated dentine ranged from 12.35-15.61 MPa, and was not significantly (p > 0.05) different from the bond strength seen in the acid-etched dentine of 19.06 MPa. However, the surface roughness of the laser-irradiated dentine was significantly (p < 0.05) higher than that of the acid-etched dentine. CONCLUSIONS: The 5-W power setting may be suitable for dental restoration applications in terms of shear bond strength and activation area.

Optimizing electrode placement using finite-element models in radiofrequency ablation treatment planning.

Conventional radiofrequency ablation (RFA) planning methods for identifying suitable electrode placements typically use geometric shapes to model ablation outcomes. A method is presented for searching electrode placements that couples finite-element models (FEMs) of RFA together with a novel optimization strategy. The method was designed to reduce the need for model solutions per local search step. The optimization strategy was tested against scenarios requiring single and multiple ablations. In particular, for a scenario requiring multiple ablations, a domain decomposition strategy was described to minimize the complexity of simultaneously searching multiple electrode placements. The effects of nearby vasculature on optimal electrode placement were also studied. Compared with geometric planning approaches, FEMs could potentially deliver electrode placement plans that provide more physically meaningful predictions of therapeutic outcomes.

Characterization of tracked radiofrequency ablation in phantom.

In radiofrequency ablation (RFA), successful therapy requires accurate, image-guided placement of the ablation device in a location selected by a predictive treatment plan. Current planning methods rely on geometric models of ablations that are not sensitive to underlying physical processes in RFA. Implementing plans based on computational models of RFA with image-guided techniques, however, has not been well characterized. To study the use of computational models of RFA in planning needle placement, this work compared ablations performed with an optically tracked RFA device with corresponding models of the ablations. The calibration of the tracked device allowed the positions of distal features of the device, particularly the tips of the needle electrodes, to be determined to within 1.4 +/- 0.6 mm of uncertainty. Ablations were then performed using the tracked device in a phantom system based on an agarose-albumin mixture. Images of the sliced phantom obtained from the ablation experiments were then compared with the predictions of a bioheat transfer model of RFA, which used the positional data of the tracked device obtained during ablation. The model was demonstrated to predict 90% of imaged pixels classified as being ablated. The discrepancies between model predictions and observations were analyzed and attributed to needle tracking inaccuracy as well as to uncertainties in model parameters. The results suggest the feasibility of using finite element modeling to plan ablations with predictable outcomes when implemented using tracked RFA.

Improving the initial biocompatibility of a titanium surface using an Er,Cr:YSGG laser-powered hydrokinetic system.

OBJECTIVES: This study was designed to improve the initial biocompatibility of titanium (Ti) using an Er,Cr:YSGG-powered hydrokinetic system. METHODS: The Er,Cr:YSGG-powered hydrokinetic system with different laser energy densities, 125 and 190 J/cm(2), were applied to the Ti substrate. Human osteosarcoma U2-OS cells were used. The difference in the attached cell number between 3- and 1-days cell culture was calculated and defined as the initial cell proliferation index (CPI). The initial CPI was statistically analyzed using one-way analysis of variance with the factor of applied laser energy density. The surface spreading morphology of the attached cells after 1 day incubation was observed using a field-emission scanning electron microscope. RESULTS: The Er,Cr:YSGG laser-treated Ti had a higher (1.2-1.3 times) initial CPI (P<0.001) and better cell spreading morphology than the untreated Ti. Treating the Ti with higher Er,Cr:YSGG laser energy did not significantly improve the CPI and cell spreading morphology. SIGNIFICANCE: The initial biocompatibility of the Ti surface could be improved using an Er,Cr:YSGG laser-powered hydrokinetic system.