Developmental Prediction of Poststroke Patients in Activities of Daily Living by Using Tree-Structured Parzen Estimator-Optimized Stacking Ensemble Approaches

Poststroke injuries limit the daily activities of patients and cause considerable inconvenience. Therefore, predicting the activities of daily living (ADL) results of patients with stroke before hospital discharge can assist clinical workers in formulating more personalized and effective strategies for therapeutic intervention, and prepare hospital discharge plans that suit the patients needs. This study used the leave-one-out cross-validation procedure to evaluate the performance of the machine learning models. In addition, testing methods were used to identify the optimal weak learners, which were then combined to form a stacking model. Subsequently, a hyperparameter optimization algorithm was used to optimize the model hyperparameters. Finally, optimization algorithms were used to analyze each feature, and features of high importance were identified by limiting the number of features to be included in the machine learning models. After various features were fed into the learning models to predict the Barthel index (BI) at discharge, the results indicated that random forest (RF), adaptive boosting (AdaBoost), and multilayer perceptron (MLP) produced suitable results. The most critical prediction factor of this study was the BI at admission. Machine learning models can be used to assist clinical workers in predicting the ADL of patients with stroke at hospital discharge.

Ensemble learning based functional independence ability estimator for pediatric brain tumor survivors

A history of brain tumor strongly affects children’s cognitive abilities, performance of daily activities, quality of life, and functional outcomes. In light of the difficulties in cognition, communication, physical skills, and behavior that these patients may encounter, occupational therapists should perform a comprehensive needs-led assessment of their global functioning after recovery. Such an assessment would ensure that the patients receive adequate support and services at school, at home, and in the community. By predicting the functional activity performance of children with a history of brain tumor, clinical workers can determine the progress of their ability recovery and the optimal treatment plan. We selected several features for testing and employed common machine learning models to predict Functional Independence Measure (WeeFIM) scores. The ensemble learning models exhibited stronger predictive performance than did the individual machine learning models. The ensemble learning models effectively predicted WeeFIM scores. Machine learning models can help clinical workers predict the functional assessment scores of patients with childhood brain tumors. This study used machine learning models to predict the WeeFIM scores of patients with childhood brain tumors and to demonstrate that ensemble machine learning models are more suitable for this task than are individual machine learning models.

Protective Effects of Epigallocatechin Gallate for Male Sexual Dysfunction in Streptozotocin-Induced Diabetic Rats

Sexual dysfunction is a common problem for men with diabetes. Epigallocatechin gallate (EGCG) is known to ameliorate erectile function in aging rats. However, there has not yet been a report to evaluate its effects on diabetic male rat sexual behavior in the literature. In this study, we investigated the effects of EGCG on male sexual behavior in diabetic rats. Diabetic rats were induced by a single intraperitoneal injection of 65 mg/kg of streptozotocin. After streptozotocin injection for one week, animals were then orally treated with 40 mg/kg of EGCG or vehicle. Copulatory behavior and fasting blood glucose levels were recorded before treatment, as well as 7 and 14 days after treatment. Serum LH, testosterone, and PDE5a levels were measured by EIA assay after the last behavioral test. Data showed that diabetic rats who had diminished sexual functions demonstrated significantly increased latencies in mount, intromission, and ejaculation, as well as significant decreases in frequencies of intromission and ejaculation, compared to non-diabetic controls, indicating sexual function recovery. Lower blood glucose levels were also found in diabetic rats after EGCG treatment. Additionally, the lower LH and higher PDE5a levels in diabetic rats than controls were also noted. The findings declared that EGCG had a protective effect on male sexual behavior in diabetic rats.

Distinguishing features of a novel humanized anti-EGFR monoclonal antibody based on cetuximab with superior antitumor efficacy

BACKGROUND

Cetuximab, the first approved EGFR targeting therapeutic antibody, is currently used to treat colorectal cancer and head and neck cancer. While effective, cetuximab is associated with a higher rate of skin rash, infusion reactions, and gastrointestinal toxicity, which was suggested to be linked to the presence of heterogeneous glycan contents on the Fab of the SP2/0-produced cetuximab.

OBJECTIVE AND METHODS

To improve efficacy and minimize toxicity of EGFR inhibition treatment, we re-engineered cetuximab by humanizing its Fab regions and minimizing its glycan contents to generate HLX07.

RESULTS

HLX07 binds to EGFR with similar affinity as cetuximab and shows better bioactivity compared to cetuximab in vitro. In vivo studies demonstrated that HLX07 significantly inhibited the growth of A431, FaDu, NCI-H292, and WiDr tumor cells and synergized them with chemotherapeutics and immune simulator agents such as anti-PD-1. In cynomolgus monkeys, 13-week repeat-dose GLP toxicokinetic studies showed minimal-to-mild toxicities in the dose range of up to 60 mg/kg/wk. In the preliminary phase 1 dose-escalation study, HLX07 had showed lower incidence of skin rashes with grade >2 severities.

CONCLUSION

HLX07 is currently under phase 1/2 clinical development. We believe HLX07 would potentially be an alternative for patients who have been suffering from cetuximab-mediated toxicity.

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.

A Comparative Study of Prothrombinase and Thrombin Inhibitors in a Novel Rabbit Model of Non-Occlusive Deep Vein Thrombosis

A quantitative and non-occlusive deep vein thrombosis model was developed in rabbits. We used this model to test the antithrombotic activity of the prothrombinase complex inhibitors factor rXai and its chemical analog glutamyl-glycyl-arginyl chloromethyl ketone inactivated human factor Xa (EGR-Xai), along with the thrombin inhibitors D-phenylalanyl-prolyl-arginyl chloromethyl ketone (PPACK) and heparin. Dose dependent effects of the inhibitors during constant infusion were monitored. Measurements included thrombus weights, hemostatic parameters and both cuticle and ear bleeding times. In this model, factor rXai and EGR-Xai had comparable in-vivo efficacy, and showed 80%-93% inhibition at plasma levels of 6.5 nM (rXai) and 8 nM (EGR-Xai). Effects on ex-vivo clotting times varied among the inhibitors. At 80-100% thrombus inhibition, factor rXai and EGR-Xai had no statistically significant effect, while PPACK extended thrombin clotting time (TCT) times 2.3-fold, and heparin prolonged both activated partial thromboplastin time (APTT), prothrombin time (PT) and TCT ex-vivo clotting times 6.9-, 1.2-, and 7-fold respectively. At these dosages, cuticle and ear bleeding times were prolonged for all inhibitors and showed increases of 177%-389% (cuticle) and 45%-129% (ear). Our results demonstrate that direct inhibition of prothrombinase complex assembly is effective in arresting venous thrombosis.

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.

Induction of c-Cbl contributes to anti-cancer effects of HDAC inhibitor in lung cancer

Here we found loss of c-Cbl, an E3 ligase, expression in non-small cell lung cancer (NSCLC) compared with its adjacent normal tissue in patient specimens. HDAC inhibition by WJ or knockdown of HDAC 1, HDAC2, HDAC3 or HDAC6 all induced c-Cbl. Ectopic expression of c-Cbl induced decreased EGFR, inhibited growth in NSCLC cells. Knockdown of EGFR inhibited NSCLC growth. Mutation of EGFR at Y1045 decreased WJ-induced growth inhibition as well as in vivo anti-cancer effect and EGFR degradation mediated by WJ. Time-lapse confocal analysis showed co-localization of c-Cbl and EGFR after WJ treatment. Furthermore, WJ inhibited lung tumor growth through c-Cbl induction in orthotopic and tail vein injected models. C-Cbl up-regulation induced by HDACi is a potential strategy for NSCLC treatment.

OFF/ON galvanic replacement reaction for preparing divergent AuAg nano-hollows as a SERS-visualized drug delivery system in targeted photodynamic therapy

3-D AuAg nano-hollows were fabricated by an anti-galvanic replacement reaction (off), followed by a proton exchange reaction (on). They exhibited superior Raman detection sensitivity for potentially imaging-guided and folic acid-targeted photodynamic therapy of cancer cells.

Abstract LB-250: Induction of c-Cbl is a novel mechanism for the anti-cancer effect of HDAC inhibitor in lung cancer

Here we found loss of c-Cbl, an E3 ligase, expression in Non-small cell lung cancer (NSCLC) compared with its adjacent normal tissue in patient specimens. HDAC inhibition by WJ or knockdown of HDAC 1, HDAC2, HDAC3 or HDAC6 all induced c-Cbl. Ectopic expression of c-Cbl induced decreased EGFR, inhibited growth in NSCLC cells. Knockdown of EGFR inhibited NSCLC growth. Mutation of EGFR at Y1045 decreased WJ-induced growth inhibition as well as in vivo anti-cancer effect and EGFR degradation mediated by WJ. Time-lapse confocal analysis showed co-localization of c-Cbl and EGFR after WJ treatment. Furthermore, WJ inhibited lung tumor growth through c-Cbl induction in orthotopic and tail vein injected models. C-Cbl up-regulation induced by HDACi is a potential strategy for NSCLC treatment.

Citation Format: Chen Ching-Chow, Tzu-Tang Wei, Yu-Chin Lin, Pei-Hua Lin, Jin-Yuan Shih, Chia-Wei Chou. Induction of c-Cbl is a novel mechanism for the anti-cancer effect of HDAC inhibitor in lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-250. doi:10.1158/1538-7445.AM2015-LB-250

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.

Colonic necrosis subsequent to catheter-directed thrombin embolization of the inferior mesenteric artery via the superior mesenteric artery: a complication in the management of a type II endoleak

The optimal management of endoleaks after endovascular repair of abdominal aortic aneurysms remains to be established. In this report, we describe a persistent side-branch, or type II, endoleak 1 year after endograft implantation treated with catheter-directed embolization of the aneurysm sac and the inferior mesenteric artery via the superior mesenteric artery, with embolization agents including thrombin, lipiodol, and gelfoam powder. Shortly after the embolization procedure, colonic necrosis developed in the patient, manifested by peritonitis, which necessitated a partial colectomy. This case underscores the devastating complication of colonic ischemia as a result of catheter-directed embolization of the inferior mesenteric artery in the management of an endoleak.

Surgical intervention for complications caused by femoral artery catheterization in pediatric patients

PURPOSE

This study evaluated the risk factors and surgical management of complications caused by femoral artery catheterization in pediatric patients.

METHODS

From January 1986 to March 2001, the hospital records of all children who underwent operative repairs for complications caused by femoral artery catheterization were reviewed. A prospective cardiac data bank containing 1674 catheterization procedures during the study period was used as a means of determining risk factors associated with iatrogenic femoral artery injury.

RESULTS

Thirty-six operations were performed in 34 patients (age range, 1 week-17.4 years) in whom iatrogenic complications developed after either diagnostic or therapeutic femoral artery catheterizations during the study period. Non-ischemic complications included femoral artery pseudoaneurysms (n = 4), arteriovenous fistulae (n = 5), uncontrollable bleeding, and expanding hematoma (n = 4). Operative repairs were performed successfully in all patients with non-ischemic iatrogenic femoral artery injuries. In contrast, ischemic complications occurred in 21 patients. Among them, 14 patients had acute femoral ischemia and underwent surgical interventions including femoral artery thrombectomy with primary closure (n = 6), saphenous vein patch angioplasty (n = 6), and resection with primary anastomosis (n = 2). Chronic femoral artery occlusion (> 30 days) occurred in seven patients, with symptoms including either severe claudication (n = 4) or gait disturbance or limb growth impairment (n = 3). Operative treatments in these patients included ileofemoral bypass grafting (n = 5), femorofemoral bypass grafting (n = 1), and femoral artery patch angioplasty (n = 1). During a mean follow-up period of 38 months, no instances of limb loss occurred, and 84% of children with ischemic complications eventually gained normal circulation. Factors that correlated with an increased risk of iatrogenic groin complications that necessitated surgical intervention included age younger than 3 years, therapeutic intervention, number of catheterizations (>or= 3), and use of 6F or larger guiding catheter.

CONCLUSION

Although excellent operative results can be achieved in cases of non-ischemic complications, acute femoral occlusion in children younger than 2 years often leads to less satisfactory outcomes. Operative intervention can provide successful outcome in children with claudication caused by chronic limb ischemia. Variables that correlated with significant iatrogenic groin complications included a young age, therapeutic intervention, earlier catheterization, and the use of a large guiding catheter.

Intra-arterial thrombin injection of an ascending aortic pseudoaneurysm complicated by transient ischemic attack and rescued with systemic abciximab

Thrombin injection as a means of inducing thrombus formation has recently received wide attention as an alternative treatment for pseudoaneurysm. We present a case of a 67-year-old man in whom a large mycotic pseudoaneurysm developed in the ascending aorta because of sternal osteomyelitis and mediastinitis after coronary artery bypass grafting. Transcatheter intra-arterial thrombin injection was performed, and it successfully induced pseudoaneurysm thrombosis. However, the procedure was complicated by a sudden transient ischemic attack caused by thrombus propagation into the cerebral circulation. Complete thrombus dissolution in the cerebral circulation with the resolution of neurologic symptoms was achieved by means of intravenous abciximab.

Sloughing of the scrotal skin and impotence subsequent to bilateral hypogastric artery embolization for endovascular aortoiliac aneurysm repair

Sloughing of the scrotal skin is an extremely rare event due to pelvic ischemia. We report herein one case of scrotal skin sloughing and impotence after bilateral hypogastric artery embolization for endoluminal aortoiliac aneurysm repair. Postoperative penile plethysmography demonstrated a 75% reduction in the penile brachial index, suggesting that pelvic ischemia is the main culprit for this complication. The devastating morbidity in our patient underscores the importance of maintaining pelvic collateral circulation when planning for endovascular aortoiliac aneurysm repair.

Early experience with the bifurcated Excluder endoprosthesis for treatment of the abdominal aortic aneurysm

PURPOSE

This report describes our initial experience with the modular, bifurcated Excluder endoprosthesis and its safety and efficacy in the primary endovascular repair of infrarenal abdominal aortic aneurysms (AAAs).

METHODS

AAAs (mean diameter, 58.2 +/- 14.3 mm) were repaired in 19 patients with this device between March 1999 and January 2000. The mean age of patients was 71.8 +/- 8.4 years (range, 57-86 years). This modular device was inserted through an 18F introducer sheath placed in one femoral artery, and the contralateral artery was cannulated with a 12F introducer sheath. All procedures were performed in a standard operating room with angiographic capabilities.

RESULTS

Endograft deployment was successful in all patients. The average surgical time was 135 +/- 37 minutes, with a mean blood loss of 229 +/- 138 mL. In eight patients, the use of either aortic or iliac extenders was required for enhanced sealing or additional length. An external iliac artery dissection occurring at the time of endograft insertion was successfully treated with a Wallstent. Type II leaks initially found to be present by means of intraoperative completion angiography had spontaneously thrombosed by the 1-month follow-up computed tomography scan. There was one perioperative death (5.3%). Complications included superficial wound infections (n = 3) and a nonfatal myocardial infarction (n = 1). The mean length of hospital stay was 2.9 +/- 1.2 days, and only six patients required intensive care. Endoleaks were seen in four patients (21%) by means of the 30-day computed tomography scan; three of these endoleaks had spontaneously sealed at the time of the 6-month follow-up examination (5.5% 6-month endoleak rate). Aneurysm size did not increase in the patients with leaks.

CONCLUSION

The Excluder endoprosthesis was an effective means of excluding an infrarenal AAA from the systemic circulation in this selected group of patients. The smaller sheath sizes may increase the pool of potential candidates. Further study of this device is warranted, and continued assessment of the long-term durability of the device will be necessary.

Detection of isolated hook fractures 36 months after implantation of the Ancure endograft: a cautionary note

Two cases of delayed (36-month) Ancure hook fracture are reported in patients who experienced a decrease in aneurysm size and no evidence of endoleak. Both devices used redesigned hooks and are otherwise identical to those devices currently used in clinical practice. Notably, hook fractures were not visualized on all abdominal radiographic views, nor were they noted on the final "institutional" report by the reviewing radiologist. Careful clinical follow-up with multiple-view abdominal radiographs remains essential for all patients treated with an endovascular graft, with particular attention directed to the integrity of the metal components. The broader clinical significance of this observation with respect to the Ancure endograft remains to be defined.

Effects on blood lipids of a blood pressure-lowering diet: the Dietary Approaches to Stop Hypertension (DASH) Trial

BACKGROUND

Effects of diet on blood lipids are best known in white men, and effects of type of carbohydrate on triacylglycerol concentrations are not well defined.

OBJECTIVE

Our goal was to determine the effects of diet on plasma lipids, focusing on subgroups by sex, race, and baseline lipid concentrations.

DESIGN

This was a randomized controlled outpatient feeding trial conducted in 4 field centers. The subjects were 436 participants of the Dietary Approaches to Stop Hypertension (DASH) Trial [mean age: 44.6 y; 60% African American; baseline total cholesterol: < or = 6.7 mmol/L (< or = 260 mg/dL)]. The intervention consisted of 8 wk of a control diet, a diet increased in fruit and vegetables, or a diet increased in fruit, vegetables, and low-fat dairy products and reduced in saturated fat, total fat, and cholesterol (DASH diet), during which time subjects remained weight stable. The main outcome measures were fasting total cholesterol, LDL cholesterol, HDL cholesterol, and triacylglycerol.

RESULTS

Relative to the control diet, the DASH diet resulted in lower total (-0.35 mmol/L, or -13.7 mg/dL), LDL- (-0.28 mmol/L, or -10.7 mg/dL), and HDL- (-0.09 mmol/L, or -3.7 mg/dL) cholesterol concentrations (all P < 0.0001), without significant effects on triacylglycerol. The net reductions in total and LDL cholesterol in men were greater than those in women by 0.27 mmol/L, or 10.3 mg/dL (P = 0.052), and by 0.29 mmol/L, or 11.2 mg/dL (P < 0.02), respectively. Changes in lipids did not differ significantly by race or baseline lipid concentrations, except for HDL, which decreased more in participants with higher baseline HDL-cholesterol concentrations than in those with lower baseline HDL-cholesterol concentrations. The fruit and vegetable diet produced few significant lipid changes.

CONCLUSIONS

The DASH diet is likely to reduce coronary heart disease risk. The possible opposing effect on coronary heart disease risk of HDL reduction needs further study.

Endovascular revascularization of renal artery stenosis: technical and clinical results

PURPOSE

The natural history of renal artery stenosis is progression with subsequent deterioration of kidney function and development of renovascular hypertension. Percutaneous transluminal renal angioplasty is effective in the treatment of nonostial lesions but less effective for ostial stenoses. Because of the poor technical success experienced with percutaneous transluminal renal angioplasty, stenting of ostial stenoses is becoming the standard of endovascular care. In this retrospective study we analyzed the technical and clinical outcomes after renal artery stenting in 73 consecutive patients.

PATIENTS AND METHODS

From July 1992 to January 1999, 88 Palmaz stents were deployed in 85 renal artery stenoses in 73 patients, with a mean age of 67.9 +/- 9.4 years. Twelve patients (16%) underwent bilateral stent placement. Atheromatous lesions were the most prevalent (99%: 82% ostial, 16% nonostial). Most stents were implanted for suboptimal balloon dilation (52%) or dissection (24%). Mean percent stenosis was 86% +/- 12%. Renal insufficiency (creatinine level > or = 1.5 mg/dL) was present in 50 (68%) patients, and uncontrolled hypertension (systolic > or = 160 mm Hg or diastolic > or = 90 mm Hg with more than two medications) was present in 57 (78%).

RESULTS

Primary technical success was achieved in 89%. At the initial procedure, three additional stents were placed for residual stenoses, and urokinase was used to treat one intraprocedural stent thrombosis, resulting in an assisted primary technical success rate of 94%. Major complications occurred in 9.1% of stents placed: access artery thrombosis (n = 4), renal artery extravasation (n = 1), renal artery thrombosis (n = 1), and hematoma requiring operation (n = 2). Long-term clinical data were available on 69 (95%) patients at 20 +/- 17 months. Overall, a significant decrease in systolic and diastolic pressures (P <.001) and reduction of medication (P <.01) were noted without a change in renal function (P = NS). Angiography was performed on 22 patients at 11.3 +/- 10.3 months for persistent or worsening renal function or hypertension or for other reasons; 10 patients had significant restenoses in 14 renal arteries.

CONCLUSION

Our retrospective analysis demonstrates that endovascular stenting of renal artery stenosis in patients with poorly controlled hypertension or deteriorating renal function is a safe and effective alternative treatment to surgical management.

Induction of direct adducts, apurinic/apyrimidinic sites and oxidized bases in nuclear DNA of human HeLa S3 tumor cells by tetrachlorohydroquinone

DNA damage induced by tetrachlorohydroquinone (Cl(4)HQ), the quinonoid metabolite of pentachlorophenol (PCP), was investigated in human HeLa S3 tumor cells. Formation of one major and two minor DNA adducts in cells treated with Cl(4)HQ (50-300 microM) was detected by (32)P-post-labeling assay and the adducts accumulated over the course of the experiment (0.5-2 h), with total adduct levels estimated to be 3-6 per 10(8) nucleotides. These adducts did not correspond to those derived from calf thymus DNA treated with tetrachloro-1,4-benzoquinone. Results from the apurinic/apyrimidinic (AP) sites assay indicated that the number of AP sites was 2-fold greater in cells exposed to Cl(4)HQ (300 microM) than the corresponding control. Further characterization of the AP sites confirmed that Cl(4)HQ induced predominantly (75%) putrescine-excisable AP sites in HeLa S3 cells. In parallel, the concentration of 8-hydroxy-2'-deoxyguanosine (8-HO-dG) in cells treated with Cl(4)HQ for 0.5 and 2 h was increased 2- and 5-fold, respectively, compared with the control. The extent of oxidative DNA damage induced by Cl(4)HQ was approximately two orders of magnitude greater than those of direct DNA adducts. Overall, it appears that reactive oxygen species mediate the parallel formation of AP sites and 8-HO-dG in HeLa S3 cells following treatment with Cl(4)HQ and that the contribution of depurination/depyrimidination of direct DNA adducts is relatively insignificant compared with the formation of oxidized AP sites. We conclude that putrescine-excisable AP sites represent a major type of ROS-mediated oxidative DNA damage in cellular DNA induced by Cl(4)HQ and may play a role in PCP-induced clastogenicity in mammalian cells.

Oxidative damage and direct adducts in calf thymus DNA induced by the pentachlorophenol metabolites, tetrachlorohydroquinone and tetrachloro-1,4-benzoquinone

DNA damage induced by quinoid metabolites of pentachlorophenol (PCP), i.e. tetrachloro-1,4-benzoquinone (Cl(4)BQ) and tetrachlorohydroquinone (Cl(4)HQ), was investigated in calf thymus DNA. The (32)P-post-labeling assay revealed four major and several minor adducts (3.5 adducts per 10(5) total nucleotides) that were produced in calf thymus DNA treated with Cl(4)BQ (5 mM). These DNA adducts were chemically stable even after conditions that induce thermal depurination and are unlikely to undergo depurination/depyrimidination to form apurinic/apyrimidinic (AP) sites. In addition, increases in 8-hydroxy-deoxyguanosine (8-HO-dG) (5 8-HO-dG per 10(5) nucleotides) and AP sites (0.5 AP sites per 10(5) nucleotides) were observed in Cl(4)BQ-modified calf thymus DNA. Further investigation indicated that in the presence of Cu(II) and NADPH, low concentrations of Cl(4)BQ (1 microM) induced a doubling of 8-HO-dG (10 8-HO-dG per 10(5) nucleotides) and dramatic increases in AP sites (20 AP sites per 10(5) nucleotides) and DNA single-strand breaks. The types of DNA damage induced by Cl(4)HQ plus Cu(II) were similar to those by Cl(4)BQ plus Cu(II) and NADPH, whereas catalase inhibited the formation of DNA damage. These data suggest that oxidative damage is causally involved in the formation of AP sites. Concentration-dependent increases in 8-HO-dG induced by Cl(4)HQ plus Cu(II) and Cl(4)BQ plus Cu(II) and NADPH were correlated with the formation of AP sites (r(2) = 0.977) with a ratio of 8-HO-dG to AP sites at 1:1.6. The AP site-cleavage assay confirmed that approximately 85% of the AP sites induced by Cl(4)HQ and Cu(II) were detected as 5'-cleaved AP sites. Since hydrogen peroxide alone causes similar DNA damage, these results suggest the involvement of Cu(II) and hydrogen peroxide in the induction of oxidative DNA damage by Cl(4)HQ/Cl(4)BQ. The data demonstrate that PCP quinone and hydroquinone induce direct and oxidative base modifications as well as the formation of 5'-cleaved AP sites in genomic DNA. These lesions may have important implications for PCP clastogenicity and carcinogenicity.

Characterization of metabolic activation of pentachlorophenol to quinones and semiquinones in rodent liver

Pentachlorophenol (PCP), a widely used biocide, induces liver tumors in mice but not in rats. Metabolic activation of PCP to chlorinated quinones and semiquinones in liver cytosol from Sprague-Dawley rats and B6C3F1 mice was investigated in vitro (1) with microsomes in the presence of either beta-nicotinamide adenine dinucleotide phosphate (NADPH) or cumene hydroperoxide (CHP), (2) with CHP in the absence of microsomes, and (3) with horseradish peroxidase (HRP) and H2O2. Mono-S- and multi-S-substituted adducts of tetrachloro-1,4-benzoquinone (Cl4-1,4-BQ) and Cl4-1,2-BQ and their corresponding semiquinones [i.e. tetrachloro-1,4-benzosemiquinone (Cl4-1,4-SQ) and tetrachloro-1,2-benzosemiquinone (Cl4-1,2-SQ)] were measured by gas chromatography-mass spectrometry (GC-MS). Qualitatively, the metabolites of PCP were the same in both rats and mice for all activation systems. Induction of PCP metabolism by either 3MC or PB-treated microsomes was observed in NADPH- but not in CHP-supported systems. In rats, the amount of induction was comparable with either 3MC or PB. 3MC was a stronger inducer than PB in mice and also induced a greater amount of metabolism than in rats. This suggests that induction of specific P450 isozymes may play a role in the toxicity of PCP to mice. Both HRP/H2O2 and CHP led to production of the full spectrum of chlorinated quinones and semiquinones, confirming the direct oxidation of PCP. CHP (with or without microsomes) converted PCP into much greater quantities of quinones and semiquinones than did microsomal P450/NADPH or HRP/H2O2 in both species. This implies that, under conditions of oxidative stress, endogenous lipid hydroperoxides may increase PCP metabolism sufficiently to enhance the toxicity and carcinogenicity of PCP.

Evaluation of thrombolysis in a porcine model of chronic deep venous thrombosis: an endovascular model

PURPOSE

The advancement of catheter-based interventions for vascular recanalization has underscored the need for an experimental animal model of vascular thrombosis that can be used for the evaluation of interventional therapies. In this model, a porcine model of deep venous thrombosis with a novel endovascular technique was described, and the efficacy of thrombolytic therapy with urokinase was evaluated.

METHODS

An endovascular device that consisted of a tapered polytetrafluoroethylene graft attached within a self-expanding nitinol stent was delivered to bilateral common iliac veins in 20 pigs. Venous thrombosis occurred as a result of flow stasis created by the intrastent stenosis. Catheter-directed pulse-spray thrombolysis with urokinase (250,000 units) and heparin (5000 IU) was performed on one limb while the contralateral limb received control saline solution. Thrombolysis was performed in 1 hour (n = 4), 8 hours (n = 4), 3 days (n = 4), 7 days (n = 4), and 14 days (n = 4) after the stent-graft deployment. Venography and intravascular ultrasound were used to evaluate the efficacy of thrombolysis. Light microscopy was used for histologic analysis of the thrombus.

RESULTS

Complete thrombolysis was achieved in groups with deep vein thrombosis that were younger than 1 day. Angioplasty of the tapered stent-grafts in the completely thrombolysed iliac vein was successful in restoring venous flow. The efficacy of thrombolysis in 3-day, 7-day, and 14-day groups was 86% +/- 7%, 73% +/- 13%, and 42% +/- 23%, respectively. The thrombolytic efficacy was enhanced to 92% +/- 16% and 86% +/- 18% (P <.05) in 3-day and 7-day groups, respectively, when doses of the pulse-spray thrombolysis were doubled. Increased dosages of the thrombolytic agent, however, did not significantly enhance the thrombus dissolution in the 14-day group.

CONCLUSION

The thrombolytic efficacy of urokinase correlated with the chronicity of deep venous thrombosis in our model. An increased dose of urokinase may be used to enhance the efficacy of thrombolysis in a 1-week-old thrombus.

Endoluminal stent placement and coil embolization for the management of carotid artery pseudoaneurysms

PURPOSE

To present a series of carotid artery pseudoaneurysms treated successfully using an endovascular approach.

METHODS

From April 1995 to November 1999, 5 patients with neurological symptoms not explained by computed tomography of the head were identified by carotid angiography as having internal carotid artery (ICA) pseudoaneurysms. Three patients had sustained blunt trauma, and 2 had previous elective carotid endarterectomies for atherosclerotic disease. The time between injury and treatment ranged from 3 days to 10 years. The patients were treated with endovascular stent placement for exclusion of the pseudoaneurysm, followed by filling of the cavity with multiple detachable coils. Patients were maintained on oral antiplatelet agents or anticoagulant therapy after the procedure.

RESULTS

Primary technical success was 100%. No patient suffered permanent neurological sequelae. Postprocedure angiography demonstrated a patent ICA in all cases, with complete obliteration of the pseudoaneurysm. At a mean 8.4-month follow-up (range 2-21), all patients remained symptom free; angiograms in 3 patients at a mean 11.7 months demonstrated continued ICA patency. One patient had a 60% focal narrowing of the distal common carotid artery, which was treated successfully with balloon dilation and stenting.

CONCLUSIONS

Endovascular treatment of carotid artery pseudoaneurysms is a useful alternative to standard surgical repair. This modality avoids the necessity for surgical exposure at the skull base with its inherent morbidity.

Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group

BACKGROUND

The effect of dietary composition on blood pressure is a subject of public health importance. We studied the effect of different levels of dietary sodium, in conjunction with the Dietary Approaches to Stop Hypertension (DASH) diet, which is rich in vegetables, fruits, and low-fat dairy products, in persons with and in those without hypertension.

METHODS

A total of 412 participants were randomly assigned to eat either a control diet typical of intake in the United States or the DASH diet. Within the assigned diet, participants ate foods with high, intermediate, and low levels of sodium for 30 consecutive days each, in random order.

RESULTS

Reducing the sodium intake from the high to the intermediate level reduced the systolic blood pressure by 2.1 mm Hg (P<0.001) during the control diet and by 1.3 mm Hg (P=0.03) during the DASH diet. Reducing the sodium intake from the intermediate to the low level caused additional reductions of 4.6 mm Hg during the control diet (P<0.001) and 1.7 mm Hg during the DASH diet (P<0.01). The effects of sodium were observed in participants with and in those without hypertension, blacks and those of other races, and women and men. The DASH diet was associated with a significantly lower systolic blood pressure at each sodium level; and the difference was greater with high sodium levels than with low ones. As compared with the control diet with a high sodium level, the DASH diet with a low sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension, and 11.5 mm Hg lower in participants with hypertension.

CONCLUSIONS

The reduction of sodium intake to levels below the current recommendation of 100 mmol per day and the DASH diet both lower blood pressure substantially, with greater effects in combination than singly. Long-term health benefits will depend on the ability of people to make long-lasting dietary changes and the increased availability of lower-sodium foods.

Endovascular revascularization of renal artery stenosis in the solitary functioning kidney

The treatment of renal artery stenosis by angioplasty and stenting is an effective and accepted alternative to surgery for the treatment of renovascular hypertension and preservation of renal function. We report the technical and clinical outcomes of renal artery stenting in patients with a solitary functioning kidney and renal artery stenosis. From October 1993 to November 1999, 30 stents were placed in the renal arteries of 27 patients (mean age 72+/-8 years) with a solitary functioning kidney and azotemia. The mean diameter renal artery stenosis was 86+/-14%. The mean preprocedure serum creatinine (Cr) level was 3.0+/-1.5 mg/dL (range 1.5-7.5 mg/dL), arterial blood pressure was 171+/-29/85+/-13 mmHg, and the number of antihypertensive drugs was 2.9+/-1.1. Indications for stenting were suboptimal balloon dilation (n = 16), intimal dissection (n = 6), and restenosis following angioplasty (n = 5). Atherosclerotic ostial lesions were present in 25 (93%) of 27 renal arteries. This represents the largest series of renal artery stenting in patients with a solitary functioning kidney, and demonstrates this treatment modality to be a relatively safe alternative to conventional surgery in this high-risk patient group. Most (74%) of the patients in this series had improved or stabilized renal function. Further efforts to define preprocedural indicators of success are necessary to identify the patients who may benefit from revascularization of their solitary kidney.

An endovascular model of carotid stenosis for the evaluation of thrombolysis and angioplasty

PURPOSE

To develop a porcine carotid artery thrombosis model using a novel stent-graft device to evaluate the efficacy of thrombolytic therapy and angioplasty procedures.

METHODS

An endovascular device made from a tapered polytetrafluoroethylene graft inverted in a self-expanding nitinol stent was delivered to bilateral carotid arteries via a right femoral approach in 16 pigs. Carotid thrombotic occlusion ensued from flow stasis created by the intrastent stenosis. Via selective carotid catheterization from a femoral approach, urokinase (250,000 IU) was pulse-sprayed in one carotid artery while a control saline solution was infused in the contralateral vessel; delivery times were 1 hour, 8 hours, 3 days, or 6 days after carotid occlusion (4 animals per time period). After thrombolysis, balloon angioplasty was performed to maintain carotid patency. Arteriography and intravascular ultrasound were used to evaluate the efficacy of thrombolysis. Light microscopy was used for histological analysis of the thrombus.

RESULTS

Carotid artery occlusion occurred in 15+/-8 minutes after stent-graft placement in all animals. Urokinase was effective in recanalizing all occluded arteries in the 1-hour, 4-hour, and 3-day groups (100%) but was effective in only 2 of 4 animals in the 6-day group (p < 0.05). Overall thrombolytic efficacy was 78%+/-7%. Control saline solution showed no thrombolytic effect (p < 0.001). Angioplasty successfully restored normal luminal diameter in all fully lysed arteries (100%). Histological analysis showed fibrin-predominant thrombus with a varying degree of platelet deposition.

CONCLUSIONS

This endovascular approach, which creates a carotid stenosis using this novel stent-graft device, is reliable in producing carotid thrombosis. In our model, thrombolytic therapy was effective in restoring luminal patency, and the intraluminal stenosis is amenable to balloon angioplasty. The model is useful for the evaluation of antithrombotic therapy and adjunctive endovascular interventions.

Subclavian artery disruption resulting from endovascular intervention: treatment options

Endovascular intervention is a commonly accepted form of treatment in patients with subclavian artery stenosis. Complications will undoubtedly occur as the utility of catheter-based intervention continues to rise. We report two cases of subclavian artery disruption as a result of endovascular intervention. One patient had contrast extravasation after the deployment of a balloon-expandable stent in a stenotic subclavian artery, and the arterial injury was successfully treated with balloon tamponade. A second patient had a large subclavian pseudoaneurysm 4 months after a balloon-expandable stent placement. Successful repair was achieved in this patient by means of arterial reconstruction with a prosthetic bypass graft. These cases illustrate different therapeutic methods of treating subclavian artery rupture due to endovascular intervention.