Stability and magnetically induced heating behavior of lipid-coated Fe3O4 nanoparticles

Magnetic nanoparticles that are currently explored for various biomedical applications exhibit a high propensity to minimize total surface energy through aggregation. This study introduces a unique, thermoresponsive nanocomposite design demonstrating substantial colloidal stability of superparamagnetic Fe(3)O(4) nanoparticles (SPIONs) due to a surface-immobilized lipid layer. Lipid coating was accomplished in different buffer systems, pH 7.4, using an equimolar mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and l-α-dipalmitoylphosphatidyl glycerol (DPPG). Particle size and zeta potential were measured by dynamic laser light scattering. Heating behavior within an alternating magnetic field was compared between the commercial MFG-1000 magnetic field generator at 7 mT (1 MHz) and an experimental, laboratory-made magnetic hyperthermia system at 16.6 mT (13.7 MHz). The results revealed that product quality of lipid-coated SPIONs was significantly dependent on the colloidal stability of uncoated SPIONs during the coating process. Greatest stability was achieved at 0.02 mg/mL in citrate buffer (mean diameter = 80.0 ± 1.7 nm; zeta potential = -47.1 ± 2.6 mV). Surface immobilization of an equimolar DPPC/DPPG layer effectively reduced the impact of buffer components on particle aggregation. Most stable suspensions of lipid-coated nanoparticles were obtained at 0.02 mg/mL in citrate buffer (mean diameter = 179.3 ± 13.9 nm; zeta potential = -19.1 ± 2.3 mV). The configuration of the magnetic field generator significantly affected the heating properties of fabricated SPIONs. Heating rates of uncoated nanoparticles were substantially dependent on buffer composition but less influenced by particle concentration. In contrast, thermal behavior of lipid-coated nanoparticles within an alternating magnetic field was less influenced by suspension vehicle but dramatically more sensitive to particle concentration. These results underline the advantages of lipid-coated SPIONs on colloidal stability without compromising magnetically induced hyperthermia properties. Since phospholipids are biocompatible, these unique lipid-coated Fe(3)O(4) nanoparticles offer exciting opportunities as thermoresponsive drug delivery carriers for targeted, stimulus-induced therapeutic interventions. PACS: 7550Mw; 7575Cd; 8185Q

Antenatal Screening Strategies for Down Syndrome: Analysis of Existing Protocols and Implications in the Kingdom of Saudi Arabia

Background: Down Syndrome (DS) is the most frequent chromosomal abnormality in live births with an incidence of 1 to 1.7 per 1,000 births and a variable physical expression. Down syndrome screening has been an integral part of routine prenatal care in recent decades. Currently, there is no established DS screening program in the Kingdom of Saudi Arabia. Objective: The total number of DS pregnancies is increasing, probably due mainly to the increasing proportion of older mothers. Live birth with DS increased also so, there is an expected increase in long term survivors. There is a need for a well structured system for prenatal diagnosis and follow up program and an extra health care resource. Design: A systematic literature search for various prenatal screening tests for DS were explored regarding the time of screening during pregnancy, detection rate, false positive rate, advantages and disadvantages. Various search engines like Pub med, Medline, Index Medicus were used to review the published literature using the key words "Down syndrome", "antenatal screening", and “Chromosomal abnormalities". Results: Different screening strategies for DS are applied worldwide. In the United Kingdom, the combined test, the integrated test or the serum integrated test is offered for women who present in the first trimester, and the quadruple test for those who present in the second trimester. In the United States, Canada, and Australia the combined test is recommended for the first trimester and the quadruple test for the second trimester. Conclusion: The Quadruple test should be offered to all pregnant women in the second trimester, in addition all women should be offered a second –trimester ultrasound scan to identify major and minor fetal abnormalities. Extensive research is needed to establish accurate incidence of DS in the Kingdom of Saudi Arabia and its relation to maternal age and parity

Placental growth factor and soluble Fms-like tyrosine kinase 1 in diabetic pregnancy: A possible relation to distal villous immaturity

This study aimed to describe the prevalence of chorionic distal villous immaturity (DVI) in overt diabetic/gestational diabetic (OD/GD) women compared with normoglycemic ones and to analyze the relation of DVI index (DVII) to placental growth factor (PlGF) and soluble Fms-like tyrosine kinase 1 (sFlt-1). Three groups were studied; normoglycemics (n=21), OD (n=17) and GD (n=20). Maternal blood samples were evaluated regarding serum levels of PlGF and sFlt-1. Immunohistochemical methodologies were employed in term placentae of all subjects to assess DVII and area% of PlGF and sFlt-1 immunostaining. We found that mean Hemoglobin A1c (HbA1c) is 5.22±0.15 in normoglycemics, 6.2±0.3 in OD, and 5.70±0.23 in GD with significant differences between groups (p=0.012). DVII was significantly higher in OD (66.6±4.7) and GD (72.4±4.5) compared to controls (11.6±2.5; p=0.000). Healthy women have significantly lower levels of PlGF (86.6±14.5) compared to OD (166.6±22.4, p=0.000) and GD (150.3±23.97, p=0.000) and their placentae expressed a significantly lower area% of PlGF (6.5±0.8) compared to OD (14.8±1.0, p=0.000) and GD (18.8±1.3, p=0.000). Also, normoglycemic women have significantly lower levels of sFlt-1 (108.9±12.1) compared to OD (226.5±18.6, p=0.000) or GD (197.2±16.8, p=0.000) and their placentae expressed a significantly lower area% of sFlt-1 (3.2±0.3) compared to OD (15.4±1.7, p=0.000) and GD (16.9±1.2, p=0.000). There was significant correlation between DVII and both serum level and area% of PlGF and sFlt-1 expression in the 3 groups. This study provided a new score for evaluating DVI in normal and diabetic placentae and suggested a role for PlGF and sFlt-1 in regulation of DVI in diabetic pregnancies

Medical students' perception of test anxiety triggered by different assessment modalities

<p><b>Objectives:</b> Test anxiety is well known among medical students. However, little is known about test anxiety produced by different components of exam individually. This study aimed to stratify varying levels of test anxiety provoked by each exam modality and to explore the students perceptions about confounding factors.</p> <p><b>Methods:</b> A self-administered questionnaire was administered to medical students. The instrument contained four main themes; lifestyle, psychological and specific factors of information needs, learning styles, and perceived difficulty level of each assessment tool.</p> <p><b>Results:</b> A highest test anxiety score of 5 was ranked for “not scheduling available time” and “insufficient exercise” by 28.8 and 28.3% students, respectively. For “irrational thoughts about exam” and “fear to fail”, a highest test anxiety score of 5 was scored by 28.8 and 25.7% students, respectively. The highest total anxiety score of 1255 was recorded for long case exam, followed by 975 for examiner-based objective structured clinical examination. Excessive course load and course not well covered by faculty were thought to be the main confounding factors.</p> <p><b>Conclusions:</b> The examiner-based assessment modalities induced high test anxiety. Faculty is urged to cover core contents within stipulated time and to rigorously reform and update existing curricula to prepare relevant course material.</p