Subcutaneous implantable cardioverter-defibrillator and defibrillation testing: A propensity-matched pilot study.

BACKGROUND: To date, only a few comparisons between subcutaneous implantable cardioverter-defibrillator (S-ICD) patients undergoing and those not undergoing defibrillation testing (DT) at implantation (DT+ vs DT-) have been reported. OBJECTIVE: The purpose of this study was to compare long-term clinical outcomes of 2 propensity-matched cohorts of DT+ and DT- patients. METHODS: Among consecutive S-ICD patients implanted across 17 centers from January 2015 to October 2020, DT- patients were 1:1 propensity-matched for baseline characteristics with DT+ patients. The primary outcome was a composite of ineffective shocks and cardiovascular mortality. Appropriate and inappropriate shock rates were deemed secondary outcomes. RESULTS: Among 1290 patients, a total of 566 propensity-matched patients (283 DT+; 283 DT-) served as study population. Over median follow-up of 25.3 months, no significant differences in primary outcome event rates were found (10 DT+ vs 14 DT-; P = .404) as well as for ineffective shocks (5 DT- vs 3 DT+; P = .725). At multivariable Cox regression analysis, DT performance was associated with a reduction of neither the primary combined outcome nor ineffective shocks at follow-up. A high PRAETORIAN score was positively associated with both the primary outcome (hazard ratio 3.976; confidence interval 1.339-11.802; P = .013) and ineffective shocks alone at follow-up (hazard ratio 19.030; confidence interval 4.752-76.203; P = .003). CONCLUSION: In 2 cohorts of strictly propensity-matched patients, DT performance was not associated with significant differences in cardiovascular mortality and ineffective shocks. The PRAETORIAN score is capable of correctly identifying a large percentage of patients at risk for ineffective shock conversion in both cohorts.

Retrospective multicenter cohort analysis of 621 cases of BellaGel silicone breast implants with study of physicochemical properties and surface topography.

This study aimed to assess the effectiveness and safety of BellaGel implants after implantation in Asian women and inform surgeons of another option for use in breast augmentation and reconstruction. This study was conducted in eight hospitals from November 27, 2015 to April 30, 2018. All patients underwent augmentation mammoplasty or implant-based breast reconstruction with BellaGel implants. Complication rates were compared between groups, and the cumulative hazard function was compared using the Kaplan-Meier survival analysis. Implants were grouped by surface type, and the cumulative hazard functions of total complication cases were compared. The biomechanical properties of the BellaGel implant and other company representative implants were tested using a mechanical testing machine, and surface topography was analyzed using a 3D laser scanning confocal microscope. There was a significant difference in the incidence of complications between the reconstruction (17.1%) and augmentation (4.7%) groups, but no significant difference in the complication rates of each group. There was no difference in the reoperation or revision rates between the groups. The log rank test showed a statistically significant difference in cumulative hazard function between the groups. Among the three types of implants (smooth, textured, and microtextured), the microtextured type had the lowest complication rate. The BellaGel microtexture implant had the highest maximal tensile load and displacement value. The BellaGel and Silksurface implants had the highest stored energy, although there was no significant difference. BellaGel implants can serve as a criterion for the selection of safe and effective implants among currently available implants.

Safety code blue! Assessing the use of blue surgical sterilization wrap for homemade respirator masks during the COVID-19 crisis.

The use of surgical sterilization wrap for respirator masks during the COVID-19 crisis has become a popularized personal protective equipment alternative option due to claims supporting its ability to meet N95 standards. This study sought to assess these claims using standardized filter testing. The tested material failed to meet N95 standards and suggests its use may place medical personnel at increased risk of harm when managing COVID-19 patients.

Compliance of Textile Vascular Prostheses Is a Fleeting Reality.

OBJECTIVE: Compliance is considered to be a major property influencing the long term performances of synthetic vascular substitutes that could play a role in anastomotic false aneurysm and intimal hyperplasia stenosis onset. Over the last decades, manufacturers have tried to develop substitutes that mechanically mimic arterial properties and avoid a compliance mismatch at the anastomoses in particular. However, data are missing about how initial compliance properties could change with time. The goal of this study was to evaluate how the compliance of vascular grafts evolves under cyclic loading conditions in vitro. METHODS: The compliance of three different models of commercially available textile polyethylene terephthalate (PET) grafts was evaluated. Tests were performed with and without their original coating. Compliance was assessed with a specific device dedicated to measure the deformations undergone by a graft under cyclic pressure loading conditions, using image analysis software. In each experiment, image analysis was performed under 60 and 140 mmHg pressure loading conditions at loading start (H0) and after three, six, and 24 h (H3, H6, H24) loading time. Average radial, longitudinal, and volumetric compliance was calculated from the obtained images. RESULTS: Twenty-four samples were tested. Results demonstrate that all values decreased significantly within only a few hours. On average, the loss of compliance after 3 h of cyclic loading ranged on average from 35% for longitudinal compliance to 39% for radial compliance and 37% (p < .050) for volume compliance. After 24 h, the loss of radial, longitudinal and volume compliance was respectively 63 ± 3%, 60.5 ± 2% and 61 ± 7%. CONCLUSION: In this in vitro model, PET graft compliance has already decreased significantly within 3 h. The rapid loss of compliance identified in this experimental study helps explain the mismatch mentioned in clinical observations.

The implant density does not change the correction rate of the main and the accompanying curves: A comparison between consecutive and intermittent pedicle screw constructs.

OBJECTIVE: The aim of this study was to evaluate the clinical outcomes and the coronal correction rate of the main and accompanying curves of adolescent idiopathic scoliosis (AIS) corrected with pedicle screws inserted consecutively or intermittently. METHODS: The prospectively collected data of 60 patients (8 men and 52 women; mean age: 14.6±2.5 years) who underwent corrective surgery for AIS between January 2010 and December 2015 were reviewed retrospectively. Two groups were constituted according to the pedicle screw construct type: consecutive pedicle screw construct (CPSC) and intermittent pedicle screw construct (IPSC) groups. The preoperative, early postoperative, and 24-month follow-up radiographs and the Scoliosis Research Society-22 (SRS-22) scores were reevaluated. The Cobb angle of the main and accompanying curves, the correction rate, and the flexibility of the curves were calculated. RESULTS: The mean preoperative Cobb angles were 57.03° and 57.46°, the mean postoperative Cobb angles were 14.93° and 14.4°, and the mean correction rates were 76.22% and 75.31% in IPSC and CPSC groups, respectively (p>0.05). The preoperative and postoperative accompanying curve magnitudes and correction rates were similar (p>0.05). These radiographic outcomes were also consistent with the SRS-22 scores. CONCLUSION: Both the pedicle screw constructs had satisfactory outcomes following the surgery, which were confirmed by both the SRS-22 scores and radiographs taken perioperatively and at follow-ups. The IPSC and CPSC groups did not demonstrate a significant change in the correction rate of the main and minor or major accompanying structural and nonstructural curves, and also in the SRS-22 scores. LEVEL OF EVIDENCE: Level III, Retrospective comparative study.

Hemocompatibility-related Adverse Events Following HeartMate II Left Ventricular Assist Device Implantation between Japan and United States.

Background: Left ventricular assist device (LVAD) therapy has improved the clinical outcomes in advanced heart failure patients, however, this may differ between countries. We aimed to compare outcomes between Japanese and US LVAD cohorts. Methods: For 416 consecutive LVAD patients who received HeartMate II LVAD implantation and completed a one-year follow-up, age-matched Japanese patients (the Japanese registry for mechanically assisted circulatory support (J-MACS) group) and the US patients were compared for their clinical outcomes. Results: 154 J-MACS patients and 77 US patients were compared. Survival, free from hemocompatibility-related adverse events (HRAEs) in the J-MACS was statistically comparable with the US (75% vs. 63%, p = 0.79). J-MACS had more disabling strokes than the US (0.221 vs. 0.052/patient-year, p = 0.005), whereas there was less nonsurgical bleeding (0.045 vs. 0.117/patient-year, p = 0.024). The net hemocompatibility score was statistically comparable between the groups (1.54 vs. 1.19 points/patient, p = 0.99). Post-LVAD prothrombin time with international normalized ratio (INR) <1.5 (odds ratio 4.07) was a risk factor for HRAEs in J-MACS, whereas INR >3.0 (odds ratio 5.71) was a risk factor in the US (p < 0.05 for both). Conclusion: In the age-matched cohorts, the J-MACS group experienced more strokes, while the US group had more bleedings. "Tailor-made" therapeutic strategy might be required for each country, given the unique variation of HRAE incidence among each country.

A bioceramic scaffold composed of strontium-doped three-dimensional hydroxyapatite whiskers for enhanced bone regeneration in osteoporotic defects.

Reconstruction of osteoporotic bone defects is a clinical problem that continues to inspire the design of new materials. Methods: In this work, bioceramics composed of strontium (Sr)-doped hydroxyapatite (HA) whiskers or pure HA whiskers were successfully fabricated by hydrothermal treatment and respectively named SrWCP and WCP. Both bioceramics had similar three-dimensional (3D) porous structures and mechanical strengths, but the SrWCP bioceramic was capable of releasing Sr under physiological conditions. In an osteoporotic rat metaphyseal femoral bone defect model, both bioceramic scaffolds were implanted, and another group that received WCP plus strontium ranelate drug administration (Sr-Ran+WCP) was studied for comparison. Results: At week 1 post-implantation, osteogenesis coupled blood vessels were found to be more common in the SrWCP and Sr-Ran+WCP groups, with substantial vascular-like structures. After 12 weeks of implantation, comparable to the Sr-Ran+WCP group, the SrWCP group showed induction of more new bone formation within the defect as well as at the implant-bone gap region than that of the WCP group. Both the SrWCP and Sr-Ran+WCP groups yielded a beneficial effect on the surrounding trabecular bone microstructure to resist osteoporosis-induced progressive bone loss. While an abnormally high blood Sr ion concentration was found in the Sr-Ran+WCP group, SrWCP showed little adverse effect. Conclusion: Our results collectively suggest that the SrWCP bioceramic can be a safe bone substitute for the treatment of osteoporotic bone defects, as it promotes local bone regeneration and implant osseointegration to a level that strontium ranelate can achieve.

Electrode impedance changes over time in MED El cochlear implant children recipients: Relation to stimulation levels and behavioral measures.

Objective: Electrode impedance measures resistance encountered by electric current passing through wires, electrodes and biological tissue. This study was designed mainly to evaluate changes in electrode impedance values and psycho-electric parameters changes (i.e. threshold levels, comfortable levels, and dynamic range) in cochlear implant patients over time. Methods: It was a prospective study encompassing 20 patients implanted by MED-EL device programd using behavioral programs. Electrical stimulation levels and electrode impedance values were examined at 0, 1, 3 and 6 months after the first fitting session. Results: Electrode impedance values were reduced from the time of activation to the 6 months visit. Most comfortable levels increased and dynamic range widened until the 6 months visit. There was an inverse correlation between impedance values and most comfortable level as well as dynamic range, over time. Conclusion: Frequent monitoring of electrode impedance (for device and electrodes problems) and electric stimulation levels (for better performance, mapping and habituation) during the first 6 months of implant use is recommended.

Audiologists' preferences in programming cochlear implants: A preliminary report.

Background: There is little data available addressing how clinical audiologists handle cochlear implant (CI) programming between device manufacturers and make decisions on related services, particularly in the United States. Objectives: This study sought to understand the techniques and settings professionals use with their patients, how they approach bimodal fitting, which tests they use to evaluate patient and device performance, and their overall preferences of (re)habilitative options. Methods: A questionnaire was developed and distributed to CI audiologists throughout the United States electronically. Results: All respondents reported either always or almost always using Cochlear's default signal processing strategy in contrast to the 64% reported for Med-El and 40% for Advanced Bionics. A trend of less use of electrically evoked stapedial reflex threshold (eSRT) than electrically evoked compound action potentials (eCAP) for objective measures was revealed. Higher likelihood of performing speech recognition tests in quiet than in noise was revealed. Preferences for bimodal fitting trend toward using a partner company's hearing aid, although preferences were comparable in adopting four types of hearing aid formulas surveyed in the questionnaire. Conclusions: These data confirm high variability among audiologists' CI programming practices, and documenting these differences is an important step to understanding how to best treat patients.

Impact of defibrillation threshold testing on burden of heart failure hospitalizations.

Background: Defibrillation threshold testing (DT) following implantable cardioverter defibrillator (ICD) implantation has not shown to improve mortality. However, the impact of DT on burden of heart failure (HF) hospitalisations has not been well defined.Methods: We studied retrospectively consecutive patients who underwent ICD implantation or generator change between 2008 and 2014. Primary outcome was burden of HF hospitalisations within 30 days following implantation. Secondary outcomes were mortality, stroke, and ICD shock within 30 days and one-year mortality.Results: Three hundred and eleven of 501 patients (62%) were in DT+ group versus 190 (38%) were in DT- group. The percentage of new implantations was higher in DT+ group than in DT- group (69% vs 39%, p < .001) but the distributions of NYHA function classes were similar between two groups. The burden of HF hospitalisations at 30-days was significantly higher in DT+ group than in DT- group (17.4% vs 4.7%, HR 0.842, 95% CI 0.774-0.915, p < .0001). No difference in mortality, stroke or ICD shocks was found between two groups at 30 days and mortality at 1 year.Conclusions: DT after new ICD or generator replacement was associated with increased HF hospitalisation rates at 30 days after ICD implant in a non-trial HF population. However, there was no association between DT and mortality, stroke and ICD shocks at 30 days or mortality at 1 year. The increased burden of HF hospitalisation in this observational study requires validation by randomised studies.

The pCONUS HPC: 30-Day and 180-Day In Vivo Biocompatibility Results.

BACKGROUND: Endovascular stents are commonly used during neurointerventional procedures; however, the concomitant use of dual anti-platelet treatment (DAPT) can limit their use. There is a need to develop stent coatings that mitigate requirement for DAPT. METHODS: The hydrophilic polymer coating is a novel glycan-based multilayer polymer that inhibits platelet adhesion. After Institutional Animal Care and Use Committee approval, 18 New Zealand white rabbits (mean weight 4.02 ± 0.51 kg) were commenced on DAPT (ASA 10 mg/kg/day and clopidogrel 10 mg/kg/day). A bare nitinol pCONUS and coated pCONUS HPC were implanted into the common carotid arteries of each rabbit. Histological examinations were performed at 30 days (n = 9) and 180 days (n = 8) to assess the acute and chronic inflammatory reactions to the pCONUS HPC. Wilcoxon/Kruskal-Wallis and ANOVA were used with p value < 0.05 considered as significant. RESULTS: There is no statistically significant difference in inflammation within the intima/media or adventitia at 30 days (p = 0.3901 and p = 1, respectively) or at 180 days (p = 0.144 and p = 1, respectively) between pCONUS and pCONUS HPC cohorts. There is no significant difference in the presence of granulomas or giant cells between the cohorts at either 30 days (p = 1 and p = 0.8363) or 180 days (p = 1.00 and p = 0.149). At 30 days and 180 days, there was near-complete endothelialisation of the stent struts and no significant difference between the pCONUS or pCONUS HPC (p = 0.7832 and p = 0.334, respectively). CONCLUSION: pCONUS HPC stents do not elicit an acute or chronic inflammatory response in vivo with no significant difference in the tissue response to bare nitinol pCONUS stents or pCONUS HPC stents.

Effects of two instrument-generation changes on adenoma detection rate during screening colonoscopy: results from a prospective randomized comparative study.

BACKGROUND: Previous studies have shown that multiple colonoscope features have to be changed before an improvement in adenoma detection rate (ADR) becomes obvious, such as with changing from one instrument generation to the next but one. We wanted to evaluate whether such an effect can also be observed in a private-practice screening setting. METHODS: In a randomized study, we compared the latest generation colonoscopes from one company (Olympus Exera III, 190) with the next to last one (Olympus 165), including only patients presenting for screening colonoscopy. The primary outcome was ADR achieved with 190 colonoscopes (190-C) in comparison with 165 colonoscopes (165-C). RESULTS: 1221 patients (46.1 % men; mean age 62.2 years, standard deviation 6.6) were included (599 screened with the Olympus Exera III, 190). The ADR difference in favor of the 190-C instrument (32 % [95 % confidence interval (CI) 26 % to 39 %] vs. 28 % [95 %CI 22 % to 34 %] in the 165-C group) failed to reach statistical significance (P = 0.10); only the rate of small (< 5 mm) adenomas was significantly increased at 22.5 % (95 %CI 19 % to 26 %) vs. 15.6 % (95 %CI 13 % to 18 %; P = 0.002). Furthermore, significantly more adenomas were found in the 190-C group, with an adenoma rate (all adenomas/all patients) of 0.57 (95 %CI 0.53 to 0.61) vs. 0.47 (95 %CI 0.43 to 0.51; P < 0.001). CONCLUSIONS: This randomized comparative trial in a private-practice screening setting only partially confirmed the results of prior studies that, with multiple imaging improvements achieved over two instrument generations, an increase in overall adenoma number becomes measurable.

In vitro biomechanical testing of the 3.5 mm LCP in torsion: a comparison of unicortical locking to bicortical nonlocking screws placed nearest the fracture gap.

OBJECTIVE: This biomechanical study compared the torsional strength and stiffness of a locking compression plate with all locking versus nonlocking screws and examined the effect of placing a locking unicortical or nonlocking bicortical screw nearest the fracture gap in a synthetic bone model. RESULTS: Synthetic bone models simulating a diaphyseal fracture without anatomic reduction were tested using four screw configurations: all bicortical locking (ABL), all bicortical nonlocking (ABN), a hybrid construct with a bicortical nonlocking screw nearest the fracture gap (BN), and a unicortical locking screw placed nearest the fracture gap (UL). Torsional stiffness, rotation and torque at failure were compared via ANOVA and post hoc pairwise comparisons (p < 0.05). ABN and BN had the highest stiffness (p < 0.01) with ABL greater than UL (p < 0.01). Rotation at failure was greatest for ABL (p < 0.01) with UL greater than ABN (p < 0.05). Unicortical locking screws nearest the fracture gap decreased stiffness, without significantly affecting torque or rotation at failure. Construct stiffness was found to exist in a very narrow range of 0.9-1.2 N m/deg with standard deviations of 0.1 N m/deg in all cases. The results of this study support the use of nonlocking screws in a hybrid construct to increase torsional stiffness.

Evaluation of the effect of four final irrigation protocols on root canal dentin components by polarized light microscopy and scanning electron microscopy.

The present study aimed to evaluate the effects of four endodontic chelating agents, followed by 2.5% sodium hypochlorite (NaOCl), as final irrigation regimens on organic and inorganic components of human root dentin. Sixty mandibular incisors were prepared and randomly divided into six groups (n = 10): QMiX, 1% peracetic acid (PA), 17% EDTA, 10% citric acid (CA), 2.5% NaOCl (solution control) and distilled water (DW-negative control). After irrigation with the chelating agents, a final flush was performed with 2.5% NaOCl. The specimens were split longitudinally in halves; one was designated for organic component analysis by polarized light microscopy (PLM) and the other for inorganic structure analysis by scanning electron microscopy (SEM). Scores data obtained in the PLM analysis were submitted to Kruskal-Wallis' test, followed by Dunn's test (p < .05). SEM findings were presented descriptively. NaOCl and DW groups showed uniformity in the fibrillar network and smear layer obliterating the dentinal tubules, while CA group presented alteration in organic and inorganic components of dentin. EDTA group did not show differences from others in the organic component, but altered the inorganic structure. QMiX and PA groups did not cause a significant morphological alteration in collagen and removed the smear layer without inorganic structure modification. As final irrigation, QMiX and PA solutions, followed by 2.5% NaOCl, showed better behavior than the other chelating agents tested, preserving organic and inorganic components of human root dentin.

Does 6 Hours of Contact With Alginate Impression Material Affect Dental Cast Properties?

Alginate impression (irreversible hydrocolloid) material is commonly used in dental practice because it is easy to mix, low in cost, and well tolerated by patients. The material is not dimensionally stable, however; thus, it is necessary to pour the impression immediately after the molding is accomplished, or within 60 minutes if the impression is kept in 100% humidity. Excessive contact of the alginate impression with the cast model over time may affect the model's properties. In this study, the authors tested the effect of contact time between an alginate impression and type III dental stone on cast model properties. Sixty-seven cast models were obtained from a stainless steel cylinder by using irreversible hydrocolloid impression material and type III dental stone. Thirty-seven cast models were separated from the impression after 1 hour (control group) and 30 cast models were separated after 6 hours (study group). The samples were evaluated under light microscope for surface details and measured by digital caliper for dimensional stability. An indentation on the cast was made and the depth of the indentation was then measured with a digital caliper to measure hardness. The dimensional stability of the cast models was not affected when contact time was increased from 1 hour to 6 hours (P = .507). Surface details did not deteriorate when contact time was increased, as all of the samples could reproduce all details after the 1-hour and 6-hour interval periods. However, hardness was greater after 1 hour of contact time (P = .001) than after 6 hours of contact time. In conclusion, contact between alginate impression material and type III dental stone up to 6 hours did not affect the dimensional stability and richness of the surface; hardness, though, was significantly affected.

Material Failure of Silicone Catheter Lines: A Retrospective Review of Partial and Complete Ruptures in 553 Patients.

OBJECTIVE: This present study reports the frequency and outcome of material failure of the silicone catheter lines of a port device implanted in the upper arm during a 5-year period. MATERIALS AND METHODS: From 2006 to 2011, a total of 553 patients had a port device implanted percutaneously in the upper arm. In the spring of 2013, several instances of material failure led to device withdrawal. At that time, 39 patients (7.1%) with the specific device in situ were still alive, and 36 of these patients agreed to removal. Linear mixed-effects models were used to analyze the log-transformed device dwell time. Random effects were modeled using group variables. The mean estimated values and their corresponding 95% CIs were reported. Nominal p values were reported, and two-sided p < 0.05 was considered to denote statistical significance. RESULTS: Among the 553 patients, material failure was noticed in 19 patients (3.4%), with a mean estimated dwell time of 243 days (95% CI, 104-570 days). Specifically, complete rupture occurred in 10 patients (1.8%) after a mean of 322 days (95% CI, 95-1089 days), partial rupture occurred in eight patients (1.4%) after a mean of 190 days (95% CI, 61-596 days), and disconnection occurred in one patient (0.2%) 8 days after device placement. CONCLUSION: The frequency of catheter line rupture was 3.4%. The mean estimated interval to rupture was less than a year, with an increasing probability of rupture noted in association with a longer dwell time. The exact cause of material failure remains unexplained, and further investigation of the mechanical properties contributing to rupture is required. Insight into the safety profile of these devices is needed to avoid potentially severe injury and improve the management of affected patients.

Cardiovascular implantable electronic device function and longevity at autopsy: an underestimated resource.

BACKGROUND: The feasibility and safety of postmortem cardiovascular implantable electronic device (CIED; pacemaker or defibrillator) retrieval for reuse has been shown. To date, studies indicate a low yield of reusable postmortem CIEDs (17%-30%). OBJECTIVE: The purpose of this study was to test the hypothesis that a higher rate of reusable CIEDs would be identified upon postmortem retrieval when an institutional protocol for systematic and routine acquisition, interrogation, reprogramming, and manufacturer analysis was used. METHODS: Over a 6-year period, all subjects referred for autopsy underwent concomitant CIED pulse generator retrieval and enrollment in the Johns Hopkins Post-Mortem CIED Registry. CIEDs were interrogated, reprogrammed, and submitted for manufacturer analysis. RESULTS: In total, 84 autopsies had CIEDs (37 pacemakers, 47 implantable cardioverter-defibrillators). CIEDs were implanted 2.84 ± 2.32 years before death, with 30% implanted <1 year before death. Overall, CIED postmortem longevity was 4.79 ± 3.41 years, with 56% demonstrating longevity ≥4 years (this group had an estimated mean longevity of 7.37 ± 2.44 years). Manufacturer analyses uncovered 2 falsely triggered elective replacement indication alerts, confirmed 5 correctly triggered elective replacement indication alerts, identified a recalled pacemaker, and verified that a defibrillator had undergone nonprogrammable hard reset. CONCLUSION: When a protocol for systematic and routine postmortem CIED retrieval, interrogation, reprogramming, and analysis was used, we noted that >60% of pacemakers and >50% of defibrillators demonstrated normal functional status with projected longevities >7 years on average. Formation of a national hospital-based "CIED donor network" would facilitate larger scale charitable efforts in underserved countries.

A comparison of drug eluting stent biocompatibility between third generation NOBORI biolimus A9-eluting stent and second generation XIENCE V everolimus-eluting stent in a porcine coronary artery model.

BACKGROUND AND PURPOSE: NOBORI biolimus A9-eluting stent (BES) is the third generation drug eluting stent (DES) with only abluminal biodegradable polymer. Recent clinical trials have indicated that the BES is non-inferior to the XIENCE V everolimus-eluting stent (EES). Meanwhile, potential superiority of biodegradable polymer BES over current generation DES has not been addressed. The aim of this preclinical study was to assess and compare the biocompatibility of both BES and EES in porcine coronary arteries. METHODS AND MATERIALS: BES with length of 24-mm (n=9) and EES with length of 23-mm (n=9) were both implanted in porcine coronary arteries. At 28 days endothelium-dependent vasomotion was assessed by acetylcholine (Ach) and subsequently measurements of endothelial superoxide production, histological evaluations and microarray gene analyses were performed. RESULTS: Angiographic and histological in-stent stenoses were significantly suppressed in BES compared with EES. Histopathological assessment showed lower inflammatory score as well as fibrin and injury scores in BES as compared with EES. On the contrary, paradoxical vasoconstriction to Ach was frequently observed in EES-treated vessels compared with BES-treated vessels. Additionally, gene expressions of inflammatory cytokines and chemokines were upregulated in vessels treated with EES compared with BES in microarray pathway specific analyses. CONCLUSIONS: Implantation of BES revealed less inflammation and foreign-body immunoreaction than EES, suggesting more enhanced biocompatibility of BES compared with EES at 28 days in porcine coronary arteries.

Estimating the concrete compressive strength using hard clustering and fuzzy clustering based regression techniques.

Understanding of the compressive strength of concrete is important for activities like construction arrangement, prestressing operations, and proportioning new mixtures and for the quality assurance. Regression techniques are most widely used for prediction tasks where relationship between the independent variables and dependent (prediction) variable is identified. The accuracy of the regression techniques for prediction can be improved if clustering can be used along with regression. Clustering along with regression will ensure the more accurate curve fitting between the dependent and independent variables. In this work cluster regression technique is applied for estimating the compressive strength of the concrete and a novel state of the art is proposed for predicting the concrete compressive strength. The objective of this work is to demonstrate that clustering along with regression ensures less prediction errors for estimating the concrete compressive strength. The proposed technique consists of two major stages: in the first stage, clustering is used to group the similar characteristics concrete data and then in the second stage regression techniques are applied over these clusters (groups) to predict the compressive strength from individual clusters. It is found from experiments that clustering along with regression techniques gives minimum errors for predicting compressive strength of concrete; also fuzzy clustering algorithm C-means performs better than K-means algorithm.