Modulating Nonlinear Acoustic Response of Phospholipid-Coated Microbubbles with pH for Ultrasound Imaging.

Activatable microbubble contrast agents for contrast-enhanced ultrasound have a potential role for measuring physiologic and pathologic states in deep tissues, including tumor acidosis. In this study, we describe a novel observation of increased harmonic oscillation of phosphatidylcholine microbubbles (PC-MBs) in response to lower ambient pH using a clinical ultrasound scanner. MB echogenicity and nonlinear echoes were monitored at neutral and acidic pH using B-mode and Cadence contrast pulse sequencing (CPS), a harmonic imaging technique at 7.0 and 1.5 MHz. A 3-fold increase in harmonic signal intensity was observed when the pH of PC-MB suspensions was decreased from 7.4 to 5.5 to mimic normal and pathophysiological levels that can be encountered in vivo. This pH-mediated activation is tunable based on the chemical structure and length of phospholipids composing the MB shell. It is also reliant on the presence of phosphate groups, as the use of lipids without phosphate instead of phospholipids completely abrogated this phenomenon. The increased harmonic signal likely is the result of increased MB oscillation caused by a decrease of the interfacial tension induced at a lower pH, altering the lipid conformation. While relative signal changes are interpreted clinically as mostly related to blood flow, pH effects could be significant contributors, particularly when imaging tumors. While our observation can be used clinically, it requires further research to isolate the effect of pH from other variables. These findings could pave the way toward for the development of new smart ultrasound contrast agents that expand the clinical utility of contrast-enhanced ultrasound.

Formulation effects on paclitaxel transfer and uptake in the human placenta.

Diagnosis and treatment of breast cancer in pregnancy can result in morbidity and mortality for the mother and fetus. Many new paclitaxel nanoformulations commercially available worldwide for breast cancer treatment are being adopted due to favorable dosing regimens and side effect profiles, but their transplacental transport and resultant fetal exposure remain unknown. Here, we examine three formulations: Taxol (paclitaxel dissolved in Kolliphor EL and ethanol); Abraxane (albumin nanoparticle); and Genexol-PM (polymeric micelle). In the ex vivo dually perfused human placental cotyledon, placental accumulation of Genexol-PM is higher than Taxol, and both nanoformulations have lower maternal concentrations of paclitaxel over time. In vitro studies of these formulations and fluorescent nanoparticle analogs demonstrate that Genexol-PM allows paclitaxel to overcome P-glycoprotein efflux, but Abraxane behaves as a free drug formulation. We anticipate that these findings will impact future development of rational and safe treatment strategies for pregnancy-associated breast cancer and other diseases.

Significant gaps in awareness of familial hypercholesterolemia among physicians in selected Asia-Pacific countries: a pilot study.

BACKGROUND: Familial hypercholesterolemia (FH) is a dominantly inherited disorder characterized by high plasma cholesterol levels and a very high risk of early heart disease. The prevalence of FH is estimated to be at least 1:500, with at least 3.6 million individuals in the Asia-Pacific region. OBJECTIVE: To assess awareness, knowledge, and perception of FH among practicing physicians in Japan, South Korea, and Taiwan. METHODS: Physicians from 3 economically developed Asian countries were requested to anonymously complete a structured Internet-based survey regarding FH. This survey sought responses on the clinical description, inheritance, prevalence, cardiovascular disease risk, practices, and opinions on screening. RESULTS: Of 230 physicians surveyed, 47% were aware of the heritability, 27% of the prevalence, and 13% of the risk of cardiovascular disease relating to FH. The majority (70%) perceived themselves to have an above-moderate familiarity with FH. Primary care physicians (59%) and lipid specialists (41%) were perceived as the best providers for caring for FH, including cascade screening services, with a lesser role perceived for cardiologists, endocrinologists, and no significant role for nursing staff. Only 35% of physicians were aware of specialist clinical services for lipid disorders in their geographic area. CONCLUSION: Extensive education and training programs are required to complement the implementation of region-specific models of care for FH in Asia. Further enhancement of existing lipid services and facilities are also warranted to optimise service models.

Influences of nanomaterials on the barrier function of epithelial cells.

Recent advances in nanotechnology have led to exciting opportunities in medicine, energy, manufacturing, and other fields. Nevertheless, it is important to adequately assess the potential impacts of nanomaterial exposure. This chapter focuses on the interactions of nanomaterials with epithelial barriers in the lungs, intestine, kidneys, skin, and placenta. Methods for determining transepithelial electrical resistance and paracellular permeability are described. Effects on cell viability and barrier integrity depend on the chemical nature of the nanomaterial, nanoparticle size, surface coatings, and concentration. Disruption of tight junctions can affect permeability and interfere with normal regulatory processes of the epithelial barrier. Future research is needed to better understand the possibilities and the limits of novel approaches in nanotechnology.

Mipomersen, an apolipoprotein B synthesis inhibitor, reduces atherogenic lipoproteins in patients with severe hypercholesterolemia at high cardiovascular risk: a randomized, double-blind, placebo-controlled trial.

OBJECTIVES: This study sought to examine the efficacy and safety of mipomersen for reducing atherogenic lipids and lipoproteins in patients with hypercholesterolemia. BACKGROUND: Many patients on lipid-lowering therapies remain unable to achieve target low-density lipoprotein (LDL) cholesterol levels. Mipomersen, an antisense oligonucleotide inhibitor of apolipoprotein B, reduces LDL cholesterol and atherogenic lipoproteins. METHODS: This randomized, double-blind, multicenter study enrolled 158 patients with baseline LDL cholesterol levels ≥100 mg/dl with, or at high risk for, coronary heart disease who were receiving maximally tolerated lipid-lowering therapy. Patients received weekly subcutaneous mipomersen 200 mg (n = 105) or placebo (n = 52) for 26 weeks, with a 24-week follow-up period. Randomization was stratified by type 2 diabetes status. RESULTS: Sixty mipomersen and 44 placebo patients completed treatment. Mean baseline LDL cholesterol levels were 122.7 and 122.6 mg/dl in the placebo and mipomersen patients, respectively. Mipomersen reduced LDL cholesterol by -36.9% compared with placebo at -4.5% (p < 0.001). Target LDL cholesterol <100 mg/dl was attained in 76% of mipomersen and 38% of placebo patients. Mipomersen also significantly reduced apolipoprotein B (-38%) and lipoprotein(a) (-24%) (p < 0.001). Common adverse events included injection site reactions (78% with mipomersen, 31% with placebo) and flu-like symptoms (34% with mipomersen, 21% with placebo). Elevations in transaminases and liver fat also occurred in some patients, and these levels returned toward baseline after treatment cessation. CONCLUSIONS: Mipomersen significantly reduced LDL cholesterol, apolipoprotein B, and lipoprotein(a) in patients with hypercholesterolemia with, or at risk for, coronary heart disease not controlled by existing therapies. (Safety and Efficacy of Mipomersen [ISIS 301012] as Add-On Therapy in High Risk Hypercholesterolemic Patients; NCT00770146).

Training of medical and paramedical personnel in burn care and prevention.

This paper discusses the requirements for training in burn care within a resource limited environment, what is currently practiced and goes on to suggest a strategy for effective delivery of education and training.

A novel, cost effective escharotomy simulator and trainee assessment.

Over the last two decades, virtual reality, haptics, simulators, robotics, and other "advanced technologies" have emerged as important innovations in medical learning and practice. In the 21st century, however, it is important to continue to develop simple teaching aids which are available to large audiences in low and middle-income countries. We present a simple 'escharotomy simulator' which has been well received, resulting in an increase in knowledge, and an increase in confidence to carry out the procedure.

Csk, a critical link of g protein signals to actin cytoskeletal reorganization.

Heterotrimeric G proteins can signal to reorganize the actin cytoskeleton, but the mechanism is unclear. Here we report that, in tyrosine kinase Csk-deficient mouse embryonic fibroblast cells, G protein (Gbetagamma, Galpha(12), Galpha(13), and Galpha(q))-induced, and G protein-coupled receptor-induced, actin stress fiber formation was completely blocked. Reintroduction of Csk into Csk-deficent cells restored the G protein-induced actin stress fiber formation. Chemical rescue experiments with catalytic mutants of Csk demonstrated that the catalytic activity of Csk was required for this process. Furthermore, we uncovered that Gbetagamma can both translocate Csk to the plasma membrane and directly increase Csk kinase activity. Our genetic and biochemical studies demonstrate that Csk plays a critical role in mediating G protein signals to actin cytoskeletal reorganization.