Complex Impedance and Modulus Analysis on Porous and Non-Porous Scaffold Composites Due to Effect of Hydroxyapatite/Starch Proportion.

This study aims to investigate the electric responses (complex modulus and complex impedance analysis) of hydroxyapatite/starch bone scaffold as a function of hydroxyapatite/starch proportion and the microstructural features. Hence, the non-porous and porous hydroxyapatite/starch composites were fabricated with various hydroxyapatite/starch proportions (70/30, 60/40, 50/50, 40/60, 30/70, 20/80, and 10/90 wt/wt%). Microstructural analysis of the porous hydroxyapatite/starch composites was carried out by using scanning electron microscopy. It shows that the formation of hierarchical porous microstructures with high porosity is more significant at a high starch proportion. The complex modulus and complex impedance analysis were conducted to investigate the electrical conduction mechanism of the hydroxyapatite/starch composites via dielectric spectroscopy within a frequency range from 5 MHz to 12 GHz. The electrical responses of the hydroxyapatite/starch composites are highly dependent on the frequency, material proportion, and microstructures. High starch proportion and highly porous hierarchical microstructures enhance the electrical responses of the hydroxyapatite/starch composite. The material proportion and microstructure features of the hydroxyapatite/starch composites can be indirectly reflected by the simulated electrical parameters of the equivalent electrical circuit models.

Lumped-Element Circuit Modeling for Composite Scaffold with Nano-Hydroxyapatite and Wangi Rice Starch.

Mechanistic studies of the interaction of electromagnetic (EM) fields with biomaterials has motivated a growing need for accurate models to describe the EM behavior of biomaterials exposed to these fields. In this paper, biodegradable bone scaffolds were fabricated using Wangi rice starch and nano-hydroxyapatite (nHA). The effects of porosity and composition on the fabricated scaffold were discussed via electrical impedance spectroscopy analysis. The fabricated scaffold was subjected to an electromagnetic field within the X-band and Ku-band (microwave spectrum) during impedance/dielectric measurement. The impedance spectra were analyzed with lumped-element models. The impedance spectra of the scaffold can be embodied in equivalent circuit models composed of passive components of the circuit, i.e., resistors, inductors and capacitors. It represents the morphological, structural and chemical characteristics of the bone scaffold. The developed models describe the impedance characteristics of plant tissue. In this study, it was found that the ε' and ε″ of scaffold composites exhibited up and down trends over frequencies for both X-band and Ku-band. The circuit models presented the lowest mean percentage errors of Z' and Z″, i.e., 3.60% and 13.80%, respectively.

Regression Analysis of the Dielectric and Morphological Properties for Porous Nanohydroxyapatite/Starch Composites: A Correlative Study.

This paper aims to investigate the dielectric properties, i.e., dielectric constant (ε'), dielectric loss factor (ε″), dielectric tangent loss (tan δ), electrical conductivity (σ), and penetration depth (Dp), of the porous nanohydroxyapatite/starch composites in the function of starch proportion, pore size, and porosity over a broad band frequency range of 5 MHz−12 GHz. The porous nanohydroxyapatite/starch composites were fabricated using different starch proportions ranging from 30 to 90 wt%. The results reveal that the dielectric properties and the microstructural features of the porous nanohydroxyapatite/starch composites can be enhanced by the increment in the starch proportion. Nevertheless, the composite with 80 wt% of starch proportion exhibit low dielectric properties (ε', ε″, tan δ, and σ) and a high penetration depth because of its highly interconnected porous microstructures. The dielectric properties of the porous nanohydroxyapatite/starch composites are highly dependent on starch proportion, average pore size, and porosity. The regression models are developed to express the dielectric properties of the porous nanohydroxyapatite/starch composites (R2 > 0.96) in the function of starch proportion, pore size, and porosity from 1 to 11 GHz. This dielectric study can facilitate the assessment of bone scaffold design in bone tissue engineering applications.

Compact organic liquid dielectric resonator antenna for air pressure sensing using soft material.

For the first time, a flexible and deformable liquid dielectric resonator antenna (LDRA) is proposed for air pressure sensing. The proposed LDRA can be made very compact as it has employed liquidized organic dielectric with high dielectric constant (~ 33) with low loss tangent (~ 0.05). Here, a soft elastomer container has been fabricated using soft-lithography method for holding the liquid, and an air cavity is tactfully embedded into the central part of a cylindrical DRA to form an annular structure that can be used for sensing air pressure. It will be shown that the inclusion of the air cavity is essential for making the antenna structure sensitive to pressure changes. Simulations and experiments have been conducted to verify the functionalities of the proposed organic LDRA as microwave radiator and as air pressure sensor. It has been proven to have higher antenna gain than the water LDRA in the frequency range of 1.8-2.8 GHz, while achieving a good air pressure sensitivity of 270 MHz/bar.

An East-West comparison of self-care barriers in heart failure.

BACKGROUND: Barriers in heart failure self-care contribute to heart failure hospitalizations, but geographic differences have not been well-studied. We aimed to compare self-care barriers in heart failure patients managed at tertiary centers in an Eastern (Singapore) versus a Western (USA) nation. METHODS: Acute heart failure patients were prospectively assessed with a standardized instrument comprising of 47 distinct self-care barriers. The multi-equation generalized structural equation model was used to evaluate for geographic differences in barriers experienced, and association of barriers with outcomes. RESULTS: Patient-related factors accounted for six out of 10 most prevalent self-care barriers among the 90 patients, with a median number of 11 barriers reported per patient. The Western patients reported a higher level of barriers when compared with their Eastern counterparts (median (interquartile range) 15 (9-24) versus 9 (4-16), p=0.001), after adjusting for demographics and co-morbidities. Many of these differences could be explained by geographic differences between the countries. There was no significant difference identified in all-cause mortality (19.4% versus 10.2%) and heart failure re-hospitalization (41.9% versus 45.8%) at six months between the groups. CONCLUSIONS: Self-care barriers are highly prevalent among acute heart failure patients, and differ substantially between East and West, but were not associated with geographic differences in outcomes.

The women's heart health programme: a pilot trial of sex-specific cardiovascular management.

BACKGROUND: There is increasing knowledge of sex-specific differences in cardiovascular disease and recognition of sex disparities in management. In our study, we investigated whether a cardiovascular programme tailored to the specific needs of women could lead to improved outcomes. METHODS: We randomised 100 female patients to receive cardiology follow-up with the conventional sex-neutral cardiac programme (control), or the sex-tailored Women's Heart Health Programme (intervention). The intervention group was managed by an all-women multidisciplinary team and received culture-centred health intervention workshops, designed through in-depth interviews with the participants. The primary outcome was cardiovascular risk factor improvement at 1 year. Secondary outcomes include cardiovascular event rates, quality of life scores, and self-reported improvement in knowledge, attitudes, intentions and practices. Generalised structural equation model analysis was used to determine if the intervention group had better outcomes at alpha level 0.1. RESULTS: The mean age was 67.3 ± 12.7 years, with an ethnic distribution of 70% Chinese, 18% Malays, and 12% Indians. The majority of these patients had no formal or primary level of education (63%), and were mostly unemployed (78%). Patients in intervention group had better control of diabetes mellitus (lower HbA1c of 0.63% [CI 0.21-1.04], p = 0.015) and lower body-mass-index (0.74 kg/m2 [CI 0.02-1.46], p = 0.092) at 1 year, but there was no significant difference in blood pressure or lipid control. Overall, there was a trend towards better risk factor control, 31.6% of intervention group versus 26.5% of control group achieved improvement in at least 1 CV risk factor control to target range. There was no significant difference in incidence of cardiovascular events, quality of life, or domains in knowledge, attitudes, intention and practices. CONCLUSION: This pilot study is the first of its kind evaluating a new model of care for women with heart disease. The potential to improve outcomes needs to be studied in a larger trial with longer follow up. TRIAL REGISTRATION: This trial was prospectively registered clinicaltrials.gov on 6 May 2013. Trial Number: 2013/00088. Identifier: NCT02017470.

Single-dose intravenous iron in Southeast Asian heart failure patients: A pilot randomized placebo-controlled study (PRACTICE-ASIA-HF).

AIMS: Iron deficiency is highly prevalent in Southeast Asians with heart failure (HF) and associated with worse outcomes. This trial aimed to assess the effect of intravenous iron in Southeast Asians hospitalized with decompensated HF. METHODS AND RESULTS: Fifty patients hospitalized for acute decompensated HF, regardless of ejection fraction, with iron deficiency (defined as serum ferritin <300 ng/mL if transferrin saturation is <20%) were randomized to receive either one dose of intravenous ferric carboxymaltose (FCM) 1000 mg or placebo (0.9% saline) following HF stabilization and before discharge in two Singapore tertiary centres. The primary endpoint was difference in 6-min walk test (6MWT) distance over 12 weeks, while secondary endpoints were quality of life assessed using validated Kansas City Cardiomyopathy Questionnaire (KCCQ) and Visual Analogue Scale (VAS). Improvement in 6MWT distance at Week 12 was observed in both FCM and placebo groups (from 252 ± 123 to 334 ± 128 m and from 243 ± 67 to 301 ± 83 m, respectively). Unadjusted analysis showed 6MWT distance for FCM exceeded that for placebo, but adjustment for baseline covariates and time attenuated this effect {adjusted mean difference between groups: 0.88 m [95% confidence interval (CI) -30.2 to 32.0, P = 0.956]}. KCCQ overall summary and VAS were similar in both groups [adjusted mean difference: KCCQ -1.48 (95% CI -8.27 to 5.31, P = 0.670) and VAS 0.26 (95% CI -0.33 to 0.86, P = 0.386)]. FCM was well tolerated with no serious treatment-related adverse events. CONCLUSIONS: Intravenous FCM administered pre-discharge in Southeast Asians hospitalized with decompensated HF is clinically feasible. Changes in 6MWT distance should be measured beyond Week 12 to account for background therapy effects.

Rationale and design of a pilot randomized controlled trial to assess the role of intravenous ferric carboxymaltose in Asian patients with heart failure (PRACTICE-ASIA-HF).

AIMS: Iron deficiency (ID) is highly prevalent in patients with heart failure (HF) worldwide regardless of haemoglobin levels. Results from therapeutic trials of intermittently dosed intravenous (i.v.) iron are promising in the ambulatory Caucasian population with HF with reduced left ventricular ejection fraction, although evidence is scarce in Asia. The Pilot Randomized Controlled Trial to Assess the Role of Intravenous Ferric Carboxymaltose in Asian Patients with Heart Failure aims to assess the effect of single-dose i.v. ferric carboxymaltose (FCM) in a multi-ethnic Asian population with HF and ID. METHODS AND RESULTS: This is an open-label, randomized, placebo-controlled trial recruiting stabilized inpatients with decompensated HF (regardless of left ventricular ejection fraction), ID [defined as serum ferritin <300 ng/mL if transferrin saturation <20%] and haemoglobin ≤14 g/dL. Patients from two tertiary institutions were randomized in a 1:1 ratio to receive a single dose of either i.v. FCM (Ferinject®) 1000 mg or i.v. normal saline. The primary endpoint is the change in 6-min walk distance at Weeks 4 and 12, and secondary endpoints are changes at Weeks 4 and 12 in (i) quality of life as measured by the Kansas City Cardiomyopathy Questionnaire and Visual Analogue Scale scores and (ii) New York Heart Association functional class. CONCLUSIONS: Preliminary efficacy data on i.v. FCM therapy in Asian HF are expected from this pilot study to support larger-scale multicentre therapeutic i.v. FCM trials within Asia.

Targeting CCL21-folic acid-upconversion nanoparticles conjugates to folate receptor-α expressing tumor cells in an endothelial-tumor cell bilayer model.

The ability of some malignant cells to evade immunosurveillance has been a major contribution to the inability of the host's immune system to eradicate the neoplastic cells. This has led to the development of various immunological strategies to augment the host immune response as part of cancer treatment. In this study, we developed folic acid (FA)/secondary lymphoid tissue chemokine (CCL21)/upconversion fluorescent nanoparticles (UCNs) conjugates as a targeting and delivery system to attract immune cells to folate receptor (FR) expressing tumor cells. Our data show that FA-conjugated UCNs@mesoporous silica specifically target FR expressing ovarian carcinoma cell line, OVCAR-3, compared to the unconjugated mesoporous silica coated UCNs. Furthermore, the FA-UCNs@mesoporous silica can efficiently cross the endothelial cell monolayer and accumulate in the clusters of OVCAR-3 cells in our endothelial-tumor cell bilayer model. Our migration assay data suggest that the CCL21 loaded into the mesoporous layer is biologically active and can efficiently induce T cells migration in-vitro. No significant cytotoxic effect was observed throughout the study indicating good biocompatibility of the nanoconjugates. As proof-of-concept, we have shown that it is feasible to load biologically active chemokines onto UCNs to modulate T cell migration.