[Analysis of clinical features and the outcome of in-hospital mortality of myocardial infarction with non-obstructive coronary arteries]

Objective: To compare the clinical features and the outcome of in-hospital mortality between patients with myocardial infarction with non-obstructive coronary arteries(MINOCA)and myocardial infarction with obstructive coronary artery disease (MI-CAD). Methods: This is a retrospective study. The clinical data of acute myocardial infarction (AMI) patients admitted to Qilu Hospital of Shandong University from January 2017 to May 2021, who underwent coronary angiography, were collected. Patients were divided into MINOCA group and MI-CAD group according to the degree of coronary stenosis (<50% or ≥50%). Baseline clinical characteristics, electrocardiograph during hospitalization, myocardial bridge, length of stay in hospital, discharge medication and the outcome of in-hospital mortality were collected and compared between the two groups. Univariate and multivariate logistic regression analysis was used to screen the related factors of MINOCA and the factors predicting the nosocomial death outcome of patients with AMI. Results: A total of 3 048 AMI patients were enrolled, age was 62 (54, 69) years, 741 (24.3%) patients were women including 165 patients (5.4%) in the MINOCA group and 2 883 patients (94.6%) in the MI-CAD group. Compared with MI-CAD patients, MINOCA patients were younger, had a higher proportion of females and a higher incidence of NSTEMI, and had a lower history of smoking, diabetes, coronary heart disease and myocardial infarction. Baseline inflammatory markers such as neutrophil count, monocyte count, neutrophil count/lymphocyte count (NLR), and monocyte count/high-density lipoprotein count (MHR) were lower, creatinine, N-terminal pro-brain B-type Natriuretic peptides (NT-proBNP), creatine kinase-MB, hypersensitive troponin I, fibrinogen, baseline blood glucose levels were lower, high-density lipoprotein cholesterol was higher, and the incidence of myocardial bridge, arrhythmia, tachycardia and atrial fibrillation was higher (P<0.05). The application rates of calcium antagonists and non-vitamin K antagonists oral anticoagulants were higher in MINOCA group (P<0.05), and there was no statistical difference in hospitalization days and in-hospital death between the two groups (P>0.05). Multiple logistic regression analysis showed that young age, female, non-smoker, no history of coronary heart disease and low MHR were risk factors of MINOCA (P<0.05). MINCOA was not associated with higher in-hospital death (P>0.05). Patients with AMI and a history of coronary heart disease, chronic renal failure, higher baseline blood glucose, higher NLR, and higher D-dimer were risk factors of in-hospital death (P<0.05). Conclusions: Compared with MI-CAD patients, MINOCA patients are younger, more likely to be female and non-smokers and on history of coronary heart disease, and have lower baseline MHR. MINOCA is often associated with myocardial bridge and atrial fibrillation. The incidence of in-hospital death in MINCOA patients is similar as in MI-CAD patients.

Ordered stereom structure in sea urchin tubercles: High capability for energy dissipation

Tubercles in sea urchin shells serve as a base on the test plates connecting the spine; these undergo compressive or impact stress from the spines. As the volume fraction of the ordered stereom structure in a tubercle increases, the compressive load-displacement curves are gradually characterized by the typical behavior of ceramic foams. Although this ordered stereom structure only exhibits an average porosity of 50.6%, it also exhibits high fracture resistance and energy dissipation capacity. Such remarkable behavior of the ordered stereom structure is attributed to its unique hierarchical microstructure. Specifically, at the macroscale, the stereom structure is periodic. It has uniformly distributed pores that are typically round, which can effectively reduce the stress concentration around the pores, and the ordered arrangement of the trabeculae along the axial direction of the tubercle bears the most compressive stress. The trabeculae present a bottleneck shape with a specific dimension, ensuring the best fracture resistance with a relatively higher porosity. Furthermore, crack deflection in the trabeculae changes the local fracture mode of the mineral, thereby increasing the crack surface area. STATEMENT OF SIGNIFICANCE: The connecting bases of the spines in sea urchin shell, known as tubercle, effectively undergo the compressive stress or impact stress from the spines. An ordered stereom structure is found in the tubercle, and it shows an excellent fracture resistance and energy dissipation capacity. Such a fantastic behavior of the ordered stereom structure mainly takes advantage of its unique hierarchical microstructure. The stereom structure presents a periodic structure on macroscale, the trabeculae show a bottleneck shape with a specific dimension to guarantee the best fracture resistance with a relatively higher porosity, and the soft fillers among CaCO₃ nanoparticles in a trabecula cause consecutive crack deflections.

Kinking and cracking behavior in nacre under stepwise compressive loading

The damage evolution of nacre under compressive loading has not been well understood, despite numerous investigations on its compressive behavior. In the present work, quasi-in-situ loading-unloading-reloading stepwise compressive tests were performed on nacre in Pinctada maxima shell, which exhibits a distinctive gradient feature with the thickness of platelets decreasing from the external to internal parts. In the loading direction parallel to the platelets, multiple microcracks and kink bands can absorb much deformation energy, leading to a graceful failure. Kinking only occurs at the final stage of fracture process, and it thus has no obvious influence on the strength of nacre, but contributes to a much larger strain. In the loading direction perpendicular to the platelets, nacre exhibits concurrently much higher compressive strength and fracture strain, as the damage can be effectively restricted. This is attributed to the presence of gradient structure, which disperses the stress concentration in front of the crack tip, and arouses the toughening mechanisms including damage localization and crack deflection. The findings obtained in this study are expected to provide fundamental insights into the design of bio-inspired advanced engineering materials.

Deformation and fracture behavior of a natural shell ceramic: Coupled effects of shell shape and microstructure

Common seashells possess their most adaptive functions benefiting from the macro-geometry and unique microstructures. The Cymbiola nobilis shell exhibits a logarithmic spiral-like shape and it is hierarchically constructed by the fiber-like crossed-lamellar structure. Three-point bending tests are conducted on three groups of samples taken from different locations (G1 with two macro-layers, G2 with three macro-layers, and G3 containing three macro-layers but with an arch-like curved shape). A novel method was developed to evaluate the bending stress of the curved samples and understand the bending fracture resistance of such curved samples. Due to the presence of a horizontal force that can decrease or shield the bending moment at the bottom center of samples, the arch-like G3 samples demonstrate the highest bending fracture resistance, revealing the significance of the curved shape of shell in the protection against the external attacks. The number of macro-layers and the curved shape of shell play an important role in the mechanical properties of the shell. The orientation of building blocks in a single crossed-lamellar layer is critical to the fracture resistance, and five types of fracture modes based on interfacial debonding, inter- and trans-lamella fracture are identified. The results obtained in this study would help open a new pathway to the development of bio-inspired high-performance structural materials.

Combination of measures of handgrip strength and red cell distribution width can predict in-hospital complications better than the ASA grade after hip fracture surgery in the elderly

BACKGROUND

Early detection of a high-risk patient following hip fracture surgery is of paramount clinical importance. American Society of Anesthesiologists (ASA) grading is an easy and efficient index in predicting a worse outcome. The red cell distribution width (RDW) and handgrip strength, are gaining interest as a prediction tool as well. Accordingly, the objective of this study was to investigate the potential association between ASA, RDW and grip strength and detect the effects of combining RDW and grip strength for predicting early complication after hip fracture surgery in the elderly.

METHODS

Eighty-three consecutive patients operated with hip fracture surgeries were identified retrospectively. Age, gender, diagnosis, RDW, handgrip strength and ASA grade were recorded. Admission to the intensive care unit (ICU), length of ICU stay, transfer to other departments, in-hospital death, and readmission were investigated as early complications. Logistic regression analysis was applied to evaluate the estimates in predicting complications, and receiver operating characteristics curves were constructed to compare the estimates and decide which method is more accurate.

RESULTS

After the surgery, 52% of the patients were admitted to the ICU. From the analyses, RDW and grip strength had no significant relation with each other. However, the ICU stay was correlated with RDW and grip strength but not for the ASA grade. A higher ASA grade and grip strength could independently predict ICU admission. The combination of RDW with grip strength outweighed the ASA grade in predictive ability.

CONCLUSIONS

The current study indicated that combining RDW and grip strength measures can be efficient and clinically relevant in predicting early postoperative complications after fragility hip fracture in the elderly. Due to the objectivity and availability of those two approaches, patient care, and functional outcomes are expected to be improved by adopting these measures in the clinical setting.

Does femoral offset recover and affect the functional outcome of patients with displaced femoral neck fracture following hemiarthroplasty?

BACKGROUND

Restoring preoperative horizontal femoral offset (FO) promised good functional outcome in patients receiving total hip arthroplasty. However, relatively little was known regarding the clinical relevance of restoring the offset in patients with bipolar hemiarthroplasty to treat displaced femoral neck fracture. Therefore, the objective of this study was to evaluate postoperative FO accurately and verify its relation with functional outcome.

METHODS

One hundred elderly patients who received bipolar hemiarthroplasty to treat displaced femoral neck fracture were identified. Preoperative CT scanning of contralateral hip joint and reconstruction of images led to rotation-free FO. By referencing postoperative implant specification and comparing to measured values in Picture Archive and Communication System, rotation-free postoperative FO and the amount of change were acquired. Postoperative Harris Hip Score (HHS) and Modified Barthel Index (MBI) were evaluated to measure functional outcome at 12-month after the surgery. Patients with significant FO change were identified. Multiple regression analysis was conducted to determine if the FO change might independently affect the outcome regardless of confounding factors.

RESULTS

The mean preoperative offset was 37.4±2.5 increased by 12.7±9.6% after the surgery. Only 25.0% of postoperative offset after hemiarthroplasty was changed within ±5% of preoperative offset. A total of 45.0% of postoperative offset changed within ±10% while 77.0% of postoperative offset changed within ±20%. 23% of patients whose FO changed more than 20% showed significantly worse outcome score than the patients whose FO change remained within ±20% of initial value. Mean MBI and HHS were negatively correlated with FO change. After adjusting for confounding factors, significant correlation remained between modification of FO and MBI, but not between FO change and HHS (B=4.576; β=0.235; 95% confidence interval of B: 0.534 to 8.135).

CONCLUSIONS

FO was not properly restored in 23% of subjects receiving bipolar hemiarthroplasty due to femoral neck fracture. FO restoration independently predicted fair MBI after the surgery. Therefore, surgeons should pay attention to restoring FO with meticulous templating.

Mechanical properties of crossed-lamellar structures in biological shells: A review

The self-fabrication of materials in nature offers an alternate and powerful solution towards the grand challenge of designing advanced structural materials, where strength and toughness are always mutually exclusive. Crossed-lamellar structures are the most common microstructures in mollusks that are composed of aragonites and a small amount of organic materials. Such a distinctive composite structure has a fracture toughness being much higher than that of pure carbonate mineral. These structures exhibiting complex hierarchical microarchitectures that span several sub-level lamellae from microscale down to nanoscale, can be grouped into two types, i.e., platelet-like and fiber-like crossed-lamellar structures based on the shapes of basic building blocks. It has been demonstrated that these structures have a great potential to strengthen themselves during deformation. The observed underlying toughening mechanisms include microcracking, channel cracking, interlocking, uncracked-ligament bridging, aragonite fiber bridging, crack deflection and zig-zag, etc., which play vital roles in enhancing the fracture resistance of shells with the crossed-lamellar structures. The exploration and utilization of these important toughening mechanisms have attracted keen interests of materials scientists since they pave the way for the development of bio-inspired advanced composite materials for load-bearing structural applications. This article is aimed to review the characteristics of hierarchical structures and the mechanical properties of two kinds of crossed-lamellar structures, and further summarize the latest advances and biomimetic applications based on the unique crossed-lamellar structures.

Kinematically aligned TKA can align knee joint line to horizontal

PURPOSE

The joint line of the native knee is horizontal to the floor and perpendicular to the vertical weight-bearing axis of the patient in a bipedal stance. The purposes of this study were as follows: (1) to find out the distribution of the native joint line in a population of normal patients with normal knees; (2) to compare the native joint line orientation between patients receiving conventional mechanically aligned total knee arthroplasty (TKA), navigated mechanically aligned TKA, and kinematically aligned TKA; and (3) to determine which of the three TKA methods aligns the postoperative knee joint perpendicular to the weight-bearing axis of the limb in bipedal stance.

METHODS

To determine the joint line orientation of a native knee, 50 full-length standing hip-to-ankle digital radiographs were obtained in 50 young, healthy individuals. The angle between knee joint line and the line parallel to the floor was measured and defined as joint line orientation angle (JLOA). JLOA was also measured prior to and after conventional mechanically aligned TKA (65 knees), mechanically aligned TKA using imageless navigation (65 knees), and kinematically aligned TKA (65 knees). The proportion of the knees similar to the native joint line was calculated for each group.

RESULTS

The mean JLOA in healthy individuals was parallel to the floor (0.2° ± 1.1°). The pre-operative JLOA of all treatment groups slanted down to the lateral side. Postoperative JLOA slanted down to the lateral side in conventional mechanically aligned TKA (-3.3° ± 2.2°) and in navigation mechanically aligned TKA (-2.6° ± 1.8°), while it was horizontal to the floor in kinematically aligned TKA (0.6° ± 1.7°). Only 6.9 % of the conventional mechanically aligned TKA and 16.9 % of the navigation mechanically aligned TKA were within one SD of the mean JLOA of the native knee, while the proportion was significantly higher (50.8 %) in kinematically aligned TKA. The portion was statistically greater in mechanically aligned TKA group than the other two.

CONCLUSION

Postoperative joint line orientation after kinematically aligned TKA was more similar to that of native knees than that of mechanically aligned TKA and horizontal to the floor. Kinematically aligned TKA can restore pre-arthritic knee joint line orientation, while mechanically aligned TKA is inefficient in achieving the purpose even if navigation TKA is employed.

LEVEL OF EVIDENCE

III.

Sarcopenia and Sarcopenic Obesity in Patients Undergoing Orthopedic Surgery

Background

The purpose of this retrospective study was to determine the prevalence of sarcopenia and sarcopenic obesity among patients who underwent orthopedic surgery (OS).

Methods

A total of 222 patients were reviewed immediately after or prior to OS. In the control group, 364 patients from outpatient departments (OPDs) who did not have any OS were enrolled. Whole-body dual-energy X-ray absorptiometry was used to analyze body composition. Skeletal muscle mass was adjusted for height squared, total body weight, and height and fat mass (residuals). Obesity was defined as body mass index (BMI) > 25.0 kg/m².

Results

The prevalence of sarcopenia in the OS group was 25.7%, 44.1%, and 26.6%, respectively, according to the 3 different criteria. The prevalence was significantly lower in the OPD group (6.0%, 33.1%, and 14.8%, respectively). The highest rates of sarcopenia with height-adjusted definition were seen in patients with a femoral neck fracture. In the multivariate analysis, factors associated with sarcopenia were male gender, older age, and lower BMI (odds ratio [OR]: 28.38, 1.03, and 1.83, respectively) when muscle mass was adjusted for height, whereas male gender, older age, and higher BMI were associated with sarcopenia (OR: 1.04, 2.57, and 1.83, respectively) when adjusted for weight. When residuals were used as a cutoff, decreased BMI and total hip bone mineral density (0.1 g/cm²) were independent risk factors associated with sarcopenia (OR: 1.09 and 1.05). The prevalence of sarcopenic obesity ranged from 1.8% to 21.2%.

Conclusions

Our study demonstrated a high prevalence of sarcopenia among OS patients.

Comparison of alternate references for femoral rotation in female patients undergoing total knee arthroplasty

PURPOSE

Accurate rotational alignment of the femoral component is of vital importance for successful total knee arthroplasty (TKA). Two anatomical references located on the anterior femur were recently introduced. To determine which is more reliable reference axis for the femoral component rotation in female patients receiving TKA, the trochlear anterior line was compared with the femoral anterior tangent line.

MATERIALS AND METHODS

Preoperative computed tomography in 76 patients receiving TKA for varus deformity was performed, and the images were reconstructed into three-dimensional models. The trochlear anterior line was defined as the line connecting the most anterior portion of the lateral and medial femoral condyles and the femoral anterior tangent line as the line parallel to distal anterior femoral surface. The two angles between these reference axes and the surgical transepicondylar axis (TEA) in three-dimensional images (trochlear anterior line/TEA, femoral anterior tangent line/TEA) were measured. The correlation between these two angles was computed. We investigated to see whether a significant difference in variance existed.

RESULTS

The trochlear anterior line was internally rotated by 6.1° ± 2.5° with respect to TEA, whereas the femoral anterior tangent line by 9.5° ± 3.8°. The trochlear anterior line was externally rotated by 3.4° ± 3.3° with respect to the femoral anterior tangent line. There was a significant correlation between the trochlear anterior line/TEA and the femoral anterior tangent line/TEA.

CONCLUSIONS

The variance of the trochlear anterior line/TEA was significantly smaller than that of the femoral anterior tangent line/TEA demonstrating a more consistent distribution. When conventional reference axes such as the posterior condylar axis or the anteroposterior axis are unclear or differ, surgeons can rely on these alternative references. When trochlear anterior line and femoral anterior tangent line contradicts, the former might be more reliable for the rotational alignment of the femoral component in female patients.

LEVEL OF EVIDENCE

Case series with no comparison group, Level IV.

Broadband tunable InAs/InP quantum dot external-cavity laser emitting around 1.55 μm

We report a broadband tunable external-cavity laser based on InAs/InP quantum dots (QDs) grown by metal-organic vapor phase epitaxy. It is found that high AsH₃ flow during the interruption after QD deposition greatly promotes QD ripening, which improves the optical gain of QD active medium in lower energy states. Combined with anti-reflection/high-reflection facet coatings, a broadly tunable InAs/InP QD external-cavity laser was realized with a tuning range of 140.4 nm across wavelengths from 1436.6 nm to 1577 nm at a maximum output power of 6 mW.

Sarcopenia and Osteoporosis

Public health strategies designed to accomodate the ever-increasing human lifespan are urgently required. A good clinical understanding of frailty, as well as knowledge regarding how to prevent it, will therefore be required in order to overcome this challenge. Sarcopenia is an important component of the frailty syndrome, and its association with osteoporosis can lead to fractures and incident disability. Therefore, this review examined the literatuire pertaining to the association of sarcopenia with osteoporosis in order to assess preventive strategies.

High performance 2150 nm-emitting InAs/InGaAs/InP quantum well lasers grown by metalorganic vapor phase epitaxy

We demonstrate high performance 2150 nm InAs/InGaAs/InP quantum well (QW) lasers grown by metalorganic vapor phase epitaxy. The laser structure consists of two InAs/InGaAs QWs, with a 30 μm-wide ridge waveguide and two cleaved cavity facets. The continuous wave operation at room temperature (RT) is achieved, with an output power of larger than 160 mW per facet and with a low threshold current density of 90.4 A/cm(2) per QW derived for the infinite cavity length. Under pulse injection mode, the maximal peak power per facet is as high as 1.35 W. By varying the cavity length, the lasing wavelength can be tuned in a range from 2142 nm to 2154 nm. Moreover, the highest operating temperature reaches up to 100 °C, and characteristic temperatures are 50 K (T(0)) and 132 K (T(1)) in the temperature range of 20-70 °C, respectively.

Advantage of minimal anterior knee pain and long-term survivorship of cemented single radius posterior-stabilized total knee arthroplasty without patella resurfacing

BACKGROUND

The single radius total knee prosthesis was introduced with the advantage of reduced patellar symptoms; however, there is no long-term follow-up study of the same. The purpose of this study was to determine the survival rate of single radius posterior-stabilized total knee arthroplasty and patellofemoral complication rates in a consecutive series.

METHODS

Seventy-one patients (103 knees) who underwent arthroplasty without patellar resurfacing using a single radius posterior-stabilized total knee prosthesis were followed up for a minimum 10 years. Clinical evaluation using Knee Society knee and function scores and radiologic evaluation were performed at regular intervals. Anterior knee pain as well as patellofemoral complications were evaluated with a simple questionnaire. The Kaplan-Meier product-limit method was used to estimate survival.

RESULTS

Seventeen patients (23 knees) were excluded due to death (12 knees) or lost to follow-up (11 knees). Of the 80 knees enrolled, all femoral components and 78 tibial components were well fixed without loosening at final follow-up. Two revisions were performed because of tibial component loosening and periprosthetic joint infection. One patient with tibial component loosening refused to have revision surgery. No obvious tibial insert polyethylene wear was observed. The survivorships at 132 months were 96.7% using revision or pending revision as end points. Anterior knee pain was present in 6 patients (6 knees, 7.5%) at the latest follow-up. No patellofemoral complication requiring revision was encountered.

CONCLUSIONS

The single radius posterior-stabilized total knee prosthesis demonstrated an excellent minimum 10-year survivorship. The low rates of implant loosening and 7.5% of anterior knee pain as a patellofemoral complication are comparable with those reported for other modern total knee prosthesis.

Three dimensional CT-based virtual patellar resection in female patients undergoing total knee replacement: a comparison between tendon and subchondral method

Background

Due to its small size, variable shape, and lack of distinct anatomical landmarks, osteoarthritic knees make a precise patellar resection extremely difficult.

Methods

We performed virtual patellar resection with digital software using three dimensional computed tomography scans of knees from 49 patients who underwent primary total knee replacement at our hospital. We compared 2 commonly used resection methods, the tendon method (TM) and the subchondral method, to determine an ideal resection plane with respect to the symmetry and thickness of the patellar remnant.

Results

The TM gave a thicker resected patella, and a less oval cut surface shape, which gives better coverage for a domed prosthesis. Both methods, however, gave a symmetric resection both superior-inferiorly, as well as mediolaterally.

Conclusions

Although TM appears statistically better with respect to the thickness and cut surface shape, only further intraoperative studies with long-term clinical follow-up may provide us with the most appropriate patellar resection method.

Dislocation after total hip arthroplasty: a randomized clinical trial of a posterior approach and a modified lateral approach

We compared the dislocation rate of total hip arthroplasty between posterior approach and lateral approach in a prospective randomized trial. One hundred ninety-six hips were randomly chosen for a posterior approach with a posterior soft tissue repair (99 hips) or a lateral approach (97 hips). The average duration of follow-up was 37.9 months. Three hips (3%) dislocated in the lateral group, whereas none from the posterior group dislocated. At the final follow-up, the Harris hip score and limping were similar in the 2 groups. The joint stability obtained by the posterior soft tissue repair in the posterior approach group seemed to produce more favorable result when compared to the stability obtained from the lateral approach group.

Conflict of interest in the assessment of thromboprophylaxis after total joint arthroplasty: a systematic review

BACKGROUND

The choice of modalities for thromboprophylaxis after total joint arthroplasty is controversial. To address this issue, an evidence-based review of previous studies was performed. The characteristics of the studies selected for review can affect the final conclusion of an evidence-based review. One such characteristic, financial conflict of interest related to medical research, is a widespread concern. The purpose of the present study was to determine what proportion of studies on thromboprophylaxis after total joint arthroplasty were sponsored by industry and whether the assessments of thromboprophylaxis after total joint arthroplasty were associated with industry support.

METHODS

We searched PubMed for prospective, original, English-language studies, published from 2004 to 2010, on thromboprophylaxis after total joint arthroplasty. The funding sources of the articles were reviewed, and qualitative conclusions regarding the modality of interest for thromboprophylaxis after total joint arthroplasty were classified as being favorable, neutral, or unfavorable.

RESULTS

Seventy-one eligible articles were identified; fifty-two were funded by industry, and fourteen were not. The other five studies did not include information about the funding source. A significant association was observed between the funding source and qualitative conclusions (p = 0.033). Only two (3.8%) of the fifty-two industry-sponsored studies had unfavorable conclusions, whereas three (21.4%) of the fourteen non-industry-sponsored studies indicated that, depending on the clinical scenario, the modality examined was neither effective nor safe.

CONCLUSIONS

Most studies on thromboprophylaxis after total joint arthroplasty are sponsored by industry. Moreover, the qualitative conclusions in those studies are favorable to the use of the sponsored prophylactic agent.

Little impact of antiplatelet agents on venous thromboembolism after hip fracture surgery

Since the late 1980s, low dose aspirin has been used to prevent stroke and ischemic heart disease. However, prophylactic effect of antiplatelets against venous thromboembolism (VTE), in patients who undergo hip fracture surgery (HFS) is controversial. Our purpose was to determine the incidence of symptomatic VTE after HFS and to evaluate whether antiplatelets reduce the development of symptomatic VTE following HFS. We retrospectively reviewed 858 HFS in 824 consecutive patients which were performed from May 2003 to April 2010 at an East Asian institute. We compared the incidence of symptomatic VTE in antiplatelet users and non-users using multivariate logistic regression analyses. Overall incidences of symptomatic pulmonary embolism including fatal pulmonary embolism, and symptomatic deep vein thrombosis in this study were 2.4% (21/858), and 3.5% (30/858), respectively. The incidence of symptomatic VTE was 4.8% (12/250) in antiplatelet users and 4.3% (26/608) in non-users (P = 0.718). It is suggested that antiplatelet agents are not effective in prevention of symptomatic VTE after HFS.

A thin-layer electrochemical detector coated with nafion film for liquid chromatography

The selectivity and analytical application of a thin-layer electrochemical detector comprised of glassy carbon electrode coated with Nafion film were investigated. As a result of the ion-exchange characteristics of the Nafion polymer, the selectivity and stability were improved greatly. The coated electrode has a good response only for cations with the same sensitivity as an uncoated (bare) electrode, but not for anions, and the response for neutral molecules is decreased three-fold. The diffusion of electroactive compounds in Nafion film is discussed based on the results of flow injection experiments. The peak current at the coated electrode was independent of the flow-rate of the mobile phase. Electrode poisoning due to protein adsorption was minimized. The use of 30% methanol or 10% acetonitrile in the mobile phase did not affect the performance of the coated electrode. Various analytes having three kinds of charge state, i.e., anionic, cationic and neutral, were tested. Liquid chromatography with electrochemical detection of ascorbic acid, norepinephrine, epinephrine, dopamine and uric acid was demonstrated.