Development of a Silicone Rubber Mold with an Innovative Waterfall Cooling Channel

A conformal cooling channel (CCC) follows the mold core or cavity profile to carry out uniform cooling in the cooling stage. However, the significant pressure drop along the cooling channels is a distinct disadvantage of the CCC. In this study, an innovative waterfall cooling channel (WCC) was proposed and implemented. The WCC cools the injected products via surface contact, replacing the conventional line contact to cool the injected products. The WCC was optimized using numerical simulation software. Silicone rubber molds with two kinds of cooling channels were designed and implemented. The cooling time of the molded part was evaluated using a low-pressure wax injection molding machine. The experimental results of the cooling time of the molded part were compared with the simulation results from numerical simulation software. The results showed that the optimal mesh element count was about 1,550,000 with a mesh size of 1 mm. The simulation software predicted the filling time of the water cup injection-molded product to be approximately 2.008 s. The cooling efficiency for a silicone rubber mold with a WCC is better than that of the silicone rubber mold with a CCC since the core and cavity cooling efficiency is close to 50%. The pressure drop of the WCC is smaller than that of the CCC, which reduces the pressure drop by about 56%. Taking a water cup with a mouth diameter of 70 mm, a height of 60 mm, and a thickness of 2 mm as an example, the experimental results confirmed that the use of the WCC can save the cooling time of the product by about 265 s compared with the CCC. This shows how a WCC can increase cooling efficiency by approximately 17.47%.

Molecular Engineering to Boost the Photo-Oxidase Activity of Molecular Rotors in Colorimetric Sensing of Temperatures

Some organic dyes and photosensitizers with strong visible absorption can behave as photo-responsive oxidase mimics. However, the relationship between the photo-oxidase activity and molecular structure remains unclear to date. In this work, a new type of photosensitizer with the characteristics of molecular rotors, namely DPPy, served as the molecular scaffold for further investigation. To adjust the photocatalytic oxidation ability, DAPy and CBPy were designed and synthesized based on the enhancement and diminishment of the intramolecular charge transfer (ICT) process, respectively. Kinetic studies revealed that DAPy and CBPy both exhibited highly efficient photo-activated oxidase-like activity with 3,3',5,5'-tetramethylbenzidine (TMB) as the substrate, which were in good accordance with their molecular engineering to promote either type I or type II reactive oxygen species (ROS) generation. Impressively a colorimetric method based on the visible light induced oxidase-like activity of molecular rotors was developed to determine the environmental temperature for the first time. Both DAPy and CBPy showed distinct sensitivities toward temperature as compared with several molecular rotors based on the typical fluorimetric detection. This work provides a new strategy for the application of molecular rotors to overcome the non-emissive challenge in temperature sensing.

Noncovalent Association Thermodynamics of Turn-On Fluorescent Probes with Human Serum Albumin: Dual-Concentration Ratio Method

Efficient quantification of the affinity of a drug and the targeted protein is critical for strategic drug design. Among the various molecules, turn-on fluorescent probes are the most promising signal transducers to reveal the binding strength and site-specificity of designed drugs. However, the conventional method of measuring the binding ability of turn-on fluorescent probes by using the fractional occupancy under the law of mass action is time-consuming and a massive sample is required. Here, we report a new method, called dual-concentration ratio method, for quantifying the binding affinity of fluorescent probes and human serum albumin (HSA). Temperature-dependent fluorescence intensity ratios of a one-to-one complex (L ⋅ HSA) for a turn-on fluorescent probe (L), e. g., ThT (thioflavin T) or DG (dansylglycine), with HSA at two different values of [L]0 /[HSA]0 under the constraint [HSA]0 >[L]0 were collected. The van't Hoff analysis on these association constants further resulted in the thermodynamic properties. Since only two samples at different [L]0 /[HSA]0 are required without the need of [L]0 /[HSA]0 at a wide range, the dual-concentration ratio method is an easy way to greatly reduce the amounts of fluorescent probes and proteins, as well as the acquisition time.

Piperic acid derivative as a molecular modulator to accelerate the IAPP aggregation process and alter its antimicrobial activity

Piperic acid derivatives were found to affect the islet amyloid polypeptide (IAPP) aggregation process. Structure-activity relationship studies revealed that PAD-13 was an efficient molecular modulator to accelerate IAPP fibril formation by promoting primary and secondary nucleation and reducing its antimicrobial activity.

An environmentally sensitive molecular rotor as a NIR fluorescent probe for the detection of islet amyloid polypeptide

The deposits of human islet amyloid polypeptide (IAPP), also called amylin, in the pancreas have been postulated to be a factor of pancreatic β-cell dysfunction and is one of the common pathological hallmarks of type II diabetes mellitus (T2DM). Therefore, it is imperative to gain an in-depth understanding of the formation of these aggregates. In this study, we demonstrate a rationally-designed strategy of an environmentally sensitive near-infrared (NIR) molecular rotor utilizing thioflavin T (ThT) as a scaffold for IAPP deposits. We extended the π delocalized system not only to improve the viscosity sensitivity but also to prolong the emission wavelength to the NIR region. A naphthalene moiety was also introduced to adjust the sensitivity of our designed probes to differentiate the binding microenvironment polarity of different targeted proteins. As a result, a novel NIR fluorogenic probe toward IAPP aggregates, namely AmySP-4-Nap-Ene, was first developed. When attached to different protein aggregates, this probe exhibited distinct fluorescence emission profiles. In a comparison with ThT, the fluorescence emission of non-ionic AmySP-4-Nap-Ene exhibits a significant difference between the presence of non-fibrillar and fibrillar IAPP and displays a higher binding affinity toward IAPP fibrils. Further, the AmySP-4-Nap-Ene can be utilized to monitor IAPP accumulating process and image fibrils both in vitro and in living cells.

Fabrication of polylactic acid/paclitaxel nano fibers by electrospinning for cancer therapeutics

Polylactic acid (PLA) is a thermoplastic and biodegradable polyester, largely derived from renewable resources such as corn starch, cassava starch and sugarcane. However, PLA is only soluble in a narrow range of solvents such as tetrahydrofuran, dioxane, chlorinated solvents and heated benzene. The limited choices of solvent for PLA dissolution have imposed significant challenges in the development of specifically engineered PLA nanofibers with electrospinning techniques. Generally, the electrospun polymeric materials have been rendered with unique properties such as high porosity and complex geometry while maintaining its biodegradability and biocompatibility for emerging biomedical applications. In this study, a new anticancer drug delivery system composed of PLA nanofibers with encapsulated paclitaxel was developed by the electrospinning of the respective nanofibers on top of a spin-coated thin film with the same chemical compositions. Our unique approach is meant for promoting strong bonding between PLA-based nanofibers and their respective films in order to improve the prolonged release properties and composite film stability within a fluctuative physiochemical environment during cell culture. PLA/paclitaxel nanofiber supported on respective polymeric films were probed by scanning electronic microscope, Fourier transform infrared spectrometer and water contact measurement for determining their surface morphologies, fibers’ diameters, molecular vibrational modes, and wettability, respectively. Moreover, PLA/paclitaxel nanofibers supported on respective spin-coated films at different loadings of paclitaxel were evaluated for their abilities in killing human colorectal carcinoma cells (HCT-116). More importantly, MTT assays showed that regardless of the concentrations of paclitaxel, the growth of HCT-116 was effectively inhibited by the prolonged release of paclitaxel from PLA/paclitaxel nanofibers. An effective prolonged delivery system of paclitaxel based on PLA nanofiber-based film has demonstrated exciting potentials for emerging applications as implantable drug delivery patch in post-surgical cancer eradication.

Label-free detection of fibrillar collagen deposition associated with vascular elements in glioblastoma multiforme by using multiphoton microscopy

Glioblastoma multiforme (GBM-WHO grade IV) is the most common and the most aggressive form of brain tumors in adults with the median survival of 10-12 months. The diagnostic detection of extracellular matrix (ECM) component in the tumour microenvironment is of prognostic value. In this paper, the fibrillar collagen deposition associated with vascular elements in GBM were investigated in the fresh specimens and unstained histological slices by using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). Our study revealed the existence of fibrillar collagen deposition in the adventitia of remodelled large blood vessels and in glomeruloid vascular structures in GBM. The degree of fibrillar collagen deposition can be quantitatively evaluated by measuring the adventitial thickness of blood vessels or calculating the ratio of SHG pixel to the whole pixel of glomeruloid vascular structure in MPM images. These results indicated that MPM can not only be employed to perform a retrospective study in unstained histological slices but also has the potential to apply for in vivo brain imaging to understand correlations between malignancy of gliomas and fibrillar collagen deposition.

Biodegradable poly-lactic acid based-composite reinforced unidirectionally with high-strength magnesium alloy wires

Biodegradable poly-lactic acid (PLA)--based composites reinforced unidirectionally with high-strength magnesium alloy wires (MAWs) are fabricated by a heat-compressing process and the mechanical properties and degradation behavior are studied experimentally and theoretically. The composites possess improved strengthening and toughening properties. The bending strength and impact strength of the composites with 40 vol% MAWs are 190 MPa and 150 kJ/m(2), respectively, although PLA has a low viscosity and an average molecular weight of 60,000 g/mol. The mechanical properties of the composites can be further improved by internal structure modification and interface strengthening and a numerical model incorporating the equivalent section method (ESM) is proposed for the bending strength. Micro arc oxidization (MAO) of the MAWs is an effective interfacial strengthening method. The composites exhibit high strength retention during degradation and the PLA in the composite shows a smaller degradation rate than pure PLA. The novel biodegradable composites have large potential in bone fracture fixation under load-bearing conditions.

Latest recanalization techniques for complex superficial femoral artery occlusions

Complex, long segment lesions of the superficial femoral artery (SFA) are common, occurring in 40% of patients with peripheral vascular disease. In particular, chronic total occlusions (CTOs) continue to pose a challenge in the endovascular management of SFA disease. Several conventional wire and catheter based techniques have been described including subintimal recanalization and retrograde techniques. In addition, advances in endovascular technology have led to the development of a series of new devices aimed specifically at facilitating the crossing of long segment SFA occlusions or establishing re-entry of the true lumen. Here we present an overview of the minimally invasive techniques used to recanalize CTOs of the SFA and the latest specialized devices available for both recanalization and re-entry, as well as a summary of the literature supporting their application.

Surface nanomechanical behavior of ZrN and ZrCN films deposited on NiTi shape memory alloy by magnetron sputtering

Surface nanomechanical behavior under nanoindentation of ZrN and ZrCN film on NiTi substrate was studied. The surface hardness and modulus of the films increase initially with larger nanoindentation depths and then reach their maximum values. Afterwards, they diminish gradually and finally reaching plateau values which are the composite modulus and composite hardness derived from the ZrN/ZrCN film and NiTi substrate. They are higher than those of electropolished NiTi SMA due to the properties of ZrN and ZrCN. In comparison, the surface nanomechanical properties of electropolished NiTi exhibit a different change with depths.

Classical reflux symptoms, hiatus hernia and overweight independently predict pharyngeal acid exposure in patients with suspected reflux laryngitis

BACKGROUND

Gastro-oesophageal reflux disease (GERD) has been associated with reflux laryngitis.

AIMS

To investigate the risk factors and the predictors of pharyngeal acid reflux (PAR) in Taiwanese patients with suspected reflux laryngitis.

METHODS

With referral from ENT physicians, 104 patients with symptoms and signs suggestive of reflux laryngitis completed a validated symptom questionnaire, an upper endoscopy exam and ambulatory 24-h pH tests with three sensors located at the hypopharynx, proximal and distal oesophagus. Patients with one or more episodes of PAR were considered abnormal.

RESULTS

Pharyngeal acid reflux was identified in 17% (18/104) of patients. In multivariate logistic regression analysis, PAR was independently associated with classical reflux symptoms [adjusted odds ratio (aOR) = 3.5, 95% confidence interval (CI): 1.0-12.8], hiatus hernia (aOR = 6.7, 95% CI: 1.5-30.2) and overweight (aOR = 3.4, 95% CI: 1.0-11.0). In predicting PAR, classical reflux symptoms had a sensitivity of 78% and hiatus hernia had a specificity of 95%. With all three factors, the positive predictive value for PAR was 80%. Classical reflux symptoms included heartburn, chest pain, dyspepsia and acid regurgitation.

CONCLUSIONS

Classical reflux symptoms, hiatus hernia and overweight are independent risk factors that may predict pharyngeal acid reflux in patients with suspected reflux laryngitis.

Clinical outcomes of mesenteric artery stenting versus surgical revascularization in chronic mesenteric ischemia

AIM

Endovascular stenting of atherosclerotic lesions has become a common practice and widely accepted treatment strategy in the treatment of arterial occlusive disease. This study examines the clinical outcome of mesenteric stenting and open mesenteric revascularization for chronic mesenteric ischemia (CMI).

METHODS

Hospital records and clinical data of all patients undergoing surgical or endovascular interventions for CMI were reviewed during a recent 10-year period. Clinical outcomes were analyzed between the two groups.

RESULTS

Endovascular treatment was performed in 48 patients (58 vessels), and open repair was performed in 96 patients (157 vessels) during the study period. The mean age in the endovascular group was greater than the open group (74+/-9 vs 62+/-7 years, P<0.05). There was no difference in comorbidities, symptom duration, or treatment indications between the two groups. Among patients treated with surgical revascularization, operative strategies included bypass grafting (N.=72, 75%); transaortic endarterectomy (N.=19, 20%), or patch angioplasty (N.=5, 5%). In the open group, one-vessel and two-vessel revascularization was performed in 36% and 64% of patients, respectively. In the endovascular cohorts, one-vessel and two-vessel balloon angioplasty and/or stenting were performed in 79% and 21% of patients, respectively. The hospital length of stay was shorter in the endovascular group (3 vs 12 days, P<0.03). There was no difference in 30-day mortality, in-hospital complication, or three-year cumulative survival rate. Cumulative freedom from recurrent symptoms at three years were significantly greater in the open group (66%) compared to the endovascular group (27%, P<0.02).

CONCLUSIONS

Endovascular treatment offers a benefit of shorter hospitalization compared to the open revascularization, while both groups had similar morbidity and mortality rates. Patients treated with surgical reconstruction were more likely to experience long-term symptomatic relief compared to endovascular cohorts, possibly due to higher incidence of two-vessel surgical revascularization. Long term durability of endovascular intervention may be improved with two-vessel revascularization.

XPS and biocompatibility studies of titania film on anodized NiTi shape memory alloy

A dense titania film is fabricated in situ on NiTi shape memory alloy (SMA) by anodic oxidation in a Na(2)SO(4) electrolyte. The microstructure of the titania film and its influence on the biocompatibility of NiTi SMA are investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), hemolysis analysis, and platelet adhesion test. The results indicate that the titania film has a Ni-free zone near the surface and can effectively block the release of harmful Ni ions from the NiTi substrate in simulated body fluids. Moreover, the wettability, hemolysis resistance, and thromboresistance of the NiTi sample are improved by this anodic oxidation method.

Fertility after homologous prepubertal testis transplantation in the dog

Canine models of hereditary human diseases are widely used throughout the biomedical community, particularly when no suitable rodent model exists. In several models, the homozygote dogs die prior to puberty, or have substantially reduced fertility. Prepubertal transplantation of the testes was used to propagate the genotype of a mutant dog that would not otherwise have survived until puberty. The transplant recipient remained fertile 7 years postoperatively. To begin determining the factors necessary for successful function in testis transplants, prepubertal dogs that were dog leukocyte antigen (DLA) identical and disparate were examined for fertility and compared to the original transplant recipient as well as unoperated and sham-operated dogs. Immunosuppression was maintained with cyclosporine (CyA) and prednisone in the immediate postoperative period and CyA alone thereafter. The DLA-identical dogs demonstrated initial acceptance of the transplant, whereas one of two underwent chronic rejection. Both DLA-disparate dogs had subacute rejection prior to sexual maturity. These results demonstrate that homologous transplantation of prepubertal testes can be an effective method to preserve genotype in DLA-identical dogs. This model may also be useful for studying testis development and immunobiology.

The relationship between dietary protein intake and blood pressure: results from the PREMIER study

Observational and clinical studies suggest that high protein intake, particularly protein from plant sources, might reduce blood pressure (BP). To examine the association of dietary protein with BP, we analysed data from PREMIER, an 18-month clinical trial (n=810) that examined the effects of two multi-component lifestyle modifications on BP. We examined the association of protein intake with BP, and in particular the independent relationship of plant and animal protein with BP. Multivariable linear regression analyses were performed with both cross-sectional and longitudinal data. Dietary plant protein was inversely associated with both systolic and diastolic BP in cross-sectional analyses at the 6-month follow-up (P=0.0045 and 0.0096, respectively). Fruit and vegetable intake was also inversely associated with both systolic and diastolic BP cross-sectionally at 6 months (P=0.0003 and 0.0157, respectively). In longitudinal analyses, a high intake of plant protein at 6 months was marginally associated with a reduction of both systolic and diastolic BP from baseline to 6 months only (P=0.0797 and 0.0866, respectively), independent of change in body weight and waist circumference. Furthermore, increased intake of plant protein, and fruits and vegetables was significantly associated with a lower risk of hypertension at 6 but not at 18 months. Results of this study indicate that plant protein had a beneficial effect on BP and was associated with a lower risk of hypertension at 6 months. Our data, in conjunction with other research, suggest that an increased intake of plant protein may be useful as a means to prevent and treat hypertension.

Management of lower extremity arterial injuries

Past and current military experience has contributed considerably to the advances made in the treatment of extremity vascular injuries. However, the management of arterial injuries of the lower extremity is still associated with significant rates of limb loss and functional deficits. The incidence of civilian arterial limb injuries, including those related to iatrogenic vessel catheterization, has increased over time, but remains fortunately uncommon. Several related issues, such as the initial order of intervention for associated bony injuries, use of temporary intravascular shunt, repair of concomitant venous injuries, and prophylactic fasciotomy, have been debated extensively and remain controversial. The current treatment of extremity arterial injuries continues to evolve with the availability of superior imaging modalities and emerging endovascular technology. Additionally, the multi-disciplinary approach to the injured patients has produced improved limb-salvage and patient survival. In this review, we discuss the diagnostic evaluation, surgical and endovascular treatment of arterial injuries in the lower extremity.

c-Src and mitosis

The transforming potential and by inference the physiological function of the proto-oncoprotein pp60c-src closely correlate with the level of its protein tyrosine kinase activity. We have investigated the cell cycle-dependent regulation of this activity using mouse fibroblasts overexpressing chicken or mouse pp60c-src as a model system. During mitosis pp60c-src becomes phosphorylated at specific serine and threonine residues by p34cdc2. At the same time its tyrosine kinase activity, assayed in vitro, is increased approximately twofold and accessibility of its SH2 domain for binding relevant phosphotyrosine-containing ligands increases by about 15-fold. A kinase-defective mutant of pp60c-src exhibits a substantial (50-70%) decrease in phosphorylation at Tyr527 during mitosis. Phosphorylation of this residue negatively regulates kinase activity. Indirect evidence indicates a lesser decrease in wild-type pp60c-src Tyr527 phosphorylation during mitosis. Coordinate mutation of the mitosis-specific phosphorylation (MSP) sites in kinase-defective pp60c-src greatly reduces, though does not abolish, its mitosis-specific tyrosine dephosphorylation. Similarly, coordinate mutation of the three MSP sites in chicken pp60c-src or the corresponding two sites in mouse pp60c-src does not completely block mitotic stimulation of kinase activity. Thus, additional events beyond p34cdc2-mediated phosphorylation are involved in cell-cycle dependent regulation of pp60c-src activity. This is also suggested by the stimulation of pp60c-src kinase activity and decrease in phosphorylation of Tyr527 observed following treatment of fibroblasts with okadaic acid, a potent inhibitor of types 1 and 2A serine/threonine phosphatases. The potential role of cell cycle-dependent regulation of phosphatases and kinases acting on the regulatory tyrosine residue of pp60c-src is discussed.

Surface structure and properties of biomedical NiTi shape memory alloy after Fenton's oxidation

Fenton's oxidation is traditionally used to remove inorganic and organic pollutants from water in waster water treatment. It is an advanced oxidation process in which H2O2 is catalytically decomposed by ferrous irons into hydroxyl radicals (*OH) which have a higher oxidation potential (2.8V) than H2O2. In the work reported here, we for the first time use Fenton's oxidation to modify the surface of biomedical NiTi shape memory alloy (SMA). The influences of Fenton's oxidation on the surface microstructure, blood compatibility, leaching of harmful Ni ions and corrosion resistance in simulated body fluids is assessed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometry, electrochemical tests, hemolysis analysis and the blood platelet adhesion test. The mechanical stability of the surface titania film produced by Fenton's oxidation as well as their effects on the shape memory behavior of the SMA are studied by bending tests. Our results show that Fenton's oxidation produces a novel nanostructured titania gel film with a graded structure on the NiTi substrate without an intermediate Ni-rich layer that is typical of high-temperature oxidation. Moreover, there is a clear Ni-free zone near the top surface of the titania film. The surface structural changes introduced by Fenton's oxidation improve the electrochemical corrosion resistance and mitigate Ni release. The latter effects are comparable to those observed after oxygen plasma immersion ion implantation reported previously and better than those of high-temperature oxidation. Aging in boiling water improves the crystallinity of the titania film and further reduces Ni leaching. Blood platelet adhesion is remarkably reduced after Fenton's oxidation, suggesting that the treated SMA has improved thrombo resistance. Enhancement of blood compatibility is believed to stem from the improved hemolysis resistance, the surface wettability and the intrinsic electrical characteristics of the titania film. The titania film produced by Fenton's oxidation has good mechanical stability and does not adversely impact the shape memory behavior of NiTi. Our work suggests that Fenton's oxidation is a promising low-temperature, low-cost surface modification method for improving the surface properties of biomedical NiTi SMA.

Dopant rearrangement and superconductivity in Bi(2)Sr(2-x)La(x)CuO(6) thin films under annealing

By combining x-ray diffraction (XRD), x-ray photoemission spectroscopy (XPS) and AC susceptibility measurements we investigate the evolution of structural and superconducting properties of La-doped Bi-2201 thin films grown by pulsed laser deposition (PLD) under different annealing conditions. We find that the main effect of oxygen annealing is to improve the crystal coherence by enabling La cation migration to the Sr sites. This activates the desired hole doping. Short-time Ar annealing removes the interstitial oxygen between the BiO layers, fine adjusting the effective hole doping. The superconducting critical temperature is consequently enhanced. However, longer annealings result in phase separation and segregation of the homologous compound Bi-1201. We attribute this effect to the loss of Bi during the annealing.

Carotid artery stenting--current status and future directions

Carotid endarterectomy has been the standard of therapy for carotid occlusive disease in stroke prevention. More recently, carotid angioplasty and stenting became an important alternative in the treatment of carotid occlusive disease. The widespread use of cerebral protection devices has substantially decreased the morbidity of the procedure. As the experience with carotid stenting increases, so does the enthusiasm for the potential of this minimally invasive carotid intervention to become the main treatment option for the high risk patients, as well as for the average asymptomatic patient. Although current available data indicate that the results regarding success and complication rates are similar between carotid stenting and endarterectomy, several prospective clinical trials are currently in progress to evaluate the efficacy of carotid artery stenting in different patient populations and definitively establish its role in the treatment of carotid disease. This paper reviews the current status of carotid stenting, including results from clinical trials, technical aspects and controversial issues and strategies to provide cerebral protection from embolization.

Fabrication and characteristics of bioactive sodium titanate/titania graded film on NiTi shape memory alloy

A bioactive sodium titanate/titania graded film was formed in situ on NiTi shape memory alloy (SMA) by oxidizing in H(2)O(2) solution and subsequent NaOH treatment and characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). The bioactivity of the film was investigated using a simulated body fluid (SBF) soaking test. A titania (TiO(2)) layer was first found on NiTi substrate after oxidized in H(2)O(2) solution, and then a porous sodium titanate (Na(2)TiO(3))/titania film with many Ti--OH groups and a trace of Ni(2)O(3) was formed by the reaction of partial TiO(2) phase with NaOH solution. After immersion in SBF for 12 h, apatite was observed to nucleate and grow on the film. With longer soaking time, more apatite appeared on its surface but our control experiments didn't reveal any apatite formation on the chemically polished NiTi SMA, which indicates the bioactivity of NiTi implants could be improved by the formation of the bioactive film. Moreover, XPS depth profiles of O, Ni, Ti, and Na show the bioactive film possesses a smooth graded interface structure to NiTi substrate, which is in favor of sufficient mechanical stability of apatite layer by subsequent deposition in SBF.

Endovascular management of abdominal aortic aneurysms

An estimated 1.5 million people in the United States have abdominal aortic aneurysms (AAAs) with more than 200000 American diagnosed each year. The natural history of AAAs is to expand and rupture, accounting for an estimated 15000 deaths per year. Thus, the major impetus for AAA repair is for prophylaxis against aneurysm-related death. The standard open surgical repair of AAAs is a well-established and durable procedure. However, as with all other major abdominal surgical operations, associated significant morbidity and mortality exist, along with prolonged recovery and various late complications. Furthermore, both mortality and morbidity increase significantly with advanced patient age and associated co-morbid disease states. Endovascular AAA repair using covered stent-grafts offers a significantly less invasive alternative to conventional open-surgical repair. A considerable reduction in hospital stay has been demonstrated, with early return to preoperative levels of activity. Patients previously considered unsuitable for open repair can often receive treatment for aneurysms with endovascular techniques. Current estimates are that more than 1/2 all infrarenal AAAs will be repaired using endovascular approach in the future. Despite the minimally-invasiveness of this new treatment, there are unanswered questions as to the durability and efficacy of devices, which results in concerns about their ability to successfully protect the patient from subsequent rupture. Three devices are commercially available and have been extensively used for implantation in the United States with a 4th device recently receiving approval from the Food and Drug Administration (FDA). In this review article, endovascular management of AAAs with these devices is described, as are the design and deployment techniques of the currently available endografts.

Epidural analgesia in patients with chronic obstructive pulmonary disease undergoing transperitoneal abdominal aortic aneurysmorraphy--a multi-institutional analysis

INTRODUCTION

Patients with chronic obstructive pulmonary disease (COPD) are more likely to develop pulmonary morbidity following major abdominal surgery. The purpose of this study was to examine the utility of epidural analgesia in patients with COPD who underwent elective transperitoneal abdominal aortic aneurysm (AAA) repair.

METHODS

During a 7-year period, all patients diagnosed with COPD undergoing elective AAA repair (n=425) from three hospitals were reviewed. Inclusion criteria were an FEV(1)/FVC ratio <75% and/or a PaCO(2)>45 mmHg. Clinical outcomes were compared between those who received epidural analgesia (epidural group) and those who did not (control group). Primary endpoints measured were duration of intubation, ICU stay, hospital days, and pulmonary complications.

RESULTS

Strict inclusion criteria were met by 131 patients, which included 86 patients in the epidural group and 45 patients in the control group. When comparing the epidural vs. control group, the mean AAA size was 6.3+/-0.9 cm vs. 6.0+/-1.5 cm (NS), FEV(1) was 57.2+/-24.7% vs. 49.0+/-10.3% (NS), and the mean FEV(1)/FVC ratio was 52.0+/-11.4% vs. 50.6+/-6.7% (NS), respectively. The epidural group had a significantly lower incidence of post-operative ventilator dependency and ICU stay (p<0.05), as well as a decreased trend in pulmonary complications when compared to the control group. The overall hospital stay remained similar between the two groups. The relative risk of developing a pulmonary complication in the absence of epidural analgesia was 2.3.

CONCLUSIONS

Perioperative epidural analgesia is beneficial in patients with COPD undergoing AAA repair by reducing both the post-operative ventilator duration and ICU stay. Epidural analgesia should be considered in all COPD patients undergoing elective transperitoneal AAA repair.