Dynamic fluorescence microscopy of cellular uptake of intercalating model drugs by ultrasound-activated microbubbles

The combination of ultrasound and microbubbles can facilitate cellular uptake of (model) drugs via transient permeabilization of the cell membrane. By using fluorescent molecules, this process can be studied conveniently with confocal fluorescence microscopy. This study aimed to investigate the relation between cellular uptake and fluorescence intensity increase of intercalating model drugs. SYTOX Green, an intercalating fluorescent dye that displays > 500-fold fluorescence enhancement upon binding to nucleic acids, was used as a model drug for ultrasound-induced cellular uptake. SYTOX Green uptake was monitored in high spatiotemporal resolution to qualitatively assess the relation between uptake and fluorescence intensity in individual cells. In addition, the kinetics of fluorescence enhancement were studied as a function of experimental parameters, in particular, laser duty cycle (DC), SYTOX Green concentration and cell line. Ultrasound-induced intracellular SYTOX Green uptake resulted in local fluorescence enhancement, spreading throughout the cell and ultimately accumulating in the nucleus during the 9-min acquisition. The temporal evolution of SYTOX Green fluorescence was substantially influenced by laser duty cycle: continuous laser (100 % DC) induced a 6.4-fold higher photobleaching compared to pulsed laser (3.3 % DC), thus overestimating the fluorescence kinetics. A positive correlation of fluorescence kinetics and SYTOX Green concentration was found, increasing from 0.6 x 10(-3) to 2.2 x 10(-3) s(-1) for 1 and 20 mu M, respectively. Finally, C6 cells displayed a 2.4-fold higher fluorescence rate constant than FaDu cells. These data show that the temporal behavior of intracellular SYTOX Green fluorescence enhancement depends substantially on nuclear accumulation and not just on cellular uptake. In addition, it is strongly influenced by the experimental conditions, such as the laser duty cycle, SYTOX Green concentration, and cell line

First-Order Melting and Dynamics of Flux Lines in a Model for YBa2_2Cu3_3O7−δ_{7-\delta}

We have studied the statics and dynamics of flux lines in a model for YBCO, using both Monte Carlo simulations and Langevin dynamics. For a clean system, both approaches yield the same melting curve, which is found to be weakly first order with a heat of fusion of about $0.02 k_BT_m$ per vortex pancake at a field of $50 {\rm kG}.$ The time averaged magnetic field distribution experienced by a fixed spin is found to undergo a qualitative change at freezing, in agreement with NMR and $\mu {\rm SR}$ experiments. Melting in the clean system is accompanied by a proliferation of free disclinations which show a clear B-dependent 3D-2D crossover from long disclination lines parallel to the c-axis at low fields, to 2D ``pancake'' disclinations at higher fields. Strong point pins produce a logarithmical $\ln t$ relaxation which results from slow annealing out of disclinations in disordered samples.Comment: 31 pages, latex, revtex, 12 figures available upon request, No major changes to the original text, but some errors in the axes scale for Figures 6 and 7 were corrected(new figures available upon request), to be published in Physical Review B, July 199

Persistence of Plasmodium falciparum parasitemia after artemisinin combination therapy: evidence from a randomized trial in Uganda

Artemisinin resistance is rapidly spreading in Southeast Asia. The efficacy of artemisinin-combination therapy (ACT) continues to be excellent across Africa. We performed parasite transcriptional profiling and genotyping on samples from an antimalarial treatment trial in Uganda. We used qRT-PCR and genotyping to characterize residual circulating parasite populations after treatment with either ACT or ACT-primaquine. Transcripts suggestive of circulating ring stage parasites were present after treatment at a prevalence of >25% until at least 14 days post initiation of treatment. Greater than 98% of all ring stage parasites were cleared within the first 3 days, but subsequently persisted at low concentrations until day 14 after treatment. Genotyping demonstrated a significant decrease in multiplicity of infection within the first 2 days in both ACT and ACT-primaquine arms. However, multiple clone infections persisted until day 14 post treatment. Our data suggest the presence of genetically diverse persisting parasite populations after ACT treatment. Although we did not demonstrate clinical treatment failures after ACT and the viability and transmissibility of persisting ring stage parasites remain to be shown, these findings are of relevance for the interpretation of parasite clearance transmission dynamics and for monitoring drug effects in Plasmodium falciparum parasites

Eliminating Malaria Vectors.

Malaria vectors which predominantly feed indoors upon humans have been locally eliminated from several settings with insecticide treated nets (ITNs), indoor residual spraying or larval source management. Recent dramatic declines of An. gambiae in east Africa with imperfect ITN coverage suggest mosquito populations can rapidly collapse when forced below realistically achievable, non-zero thresholds of density and supporting resource availability. Here we explain why insecticide-based mosquito elimination strategies are feasible, desirable and can be extended to a wider variety of species by expanding the vector control arsenal to cover a broader spectrum of the resources they need to survive. The greatest advantage of eliminating mosquitoes, rather than merely controlling them, is that this precludes local selection for behavioural or physiological resistance traits. The greatest challenges are therefore to achieve high biological coverage of targeted resources rapidly enough to prevent local emergence of resistance and to then continually exclude, monitor for and respond to re-invasion from external populations

Polymorphisms in the cytochrome P450 genes CYP1A2, CYP1B1, CYP3A4, CYP3A5, CYP11A1, CYP17A1, CYP19A1 and colorectal cancer risk

BACKGROUND: Cytochrome P450 (CYP) enzymes have the potential to affect colorectal cancer (CRC) risk by determining the genotoxic impact of exogenous carcinogens and levels of sex hormones. METHODS: To investigate if common variants of CYP1A2, CYP1B1, CYP3A4, CYP3A5, CYP11A1, CYP17A1 and CYP19A1 influence CRC risk we genotyped 2,575 CRC cases and 2,707 controls for 20 single nucleotide polymorphisms (SNPs) that have not previously been shown to have functional consequence within these genes. RESULTS: There was a suggestion of increased risk, albeit insignificant after correction for multiple testing, of CRC for individuals homozygous for CYP1B1 rs162558 and heterozygous for CYP1A2 rs2069522 (odds ratio [OR] = 1.36, 95% confidence interval [CI]: 1.03-1.80 and OR = 1.34, 95% CI: 1.00-1.79 respectively). CONCLUSION: This study provides some support for polymorphic variation in CYP1A2 and CYP1B1 playing a role in CRC susceptibility

Hitting Hotspots: Spatial Targeting of Malaria for Control and Elimination

Teun Bousema and colleagues argue that targeting malaria “hotspots” is a highly efficient way to reduce malaria transmission at all levels of transmission intensity

Pentalogy of Cantrell: two patients and a review to determine prognostic factors for optimal approach

Two patients with incomplete pentalogy of Cantrell are described. The first was a girl with a large omphalocele with evisceration of the heart, liver and intestines with an intact sternum. Echocardiography showed profound intracardiac defects. The girl died 33 h after birth. The second patient was a female fetus with ectopia cordis (EC) without intracardiac anomalies; a large omphalocele with evisceration of the heart, stomach, spleen and liver; a hypoplastic sternum and rib cage; and a scoliosis. The pregnancy was terminated. A review of patients described in the literature is presented with the intention of finding prognostic factors for an optimal approach to patients with the pentalogy of Cantrell. In conclusion the prognosis seems to be poorer in patients with the complete form of pentalogy of Cantrell, EC, and patients with associated anomalies. Intracardial defects do not seem to be a prognostic factor

Image-guided focused ultrasound ablation of breast cancer: current status, challenges, and future directions

Image-guided focussed ultrasound (FUS) ablation is a non-invasive procedure that has been used for treatment of benign or malignant breast tumours. Image-guidance during ablation is achieved either by using real-time ultrasound (US) or magnetic resonance imaging (MRI). The past decade phase I studies have proven MRI-guided and US-guided FUS ablation of breast cancer to be technically feasible and safe. We provide an overview of studies assessing the efficacy of FUS for breast tumour ablation as measured by percentages of complete tumour necrosis. Successful ablation ranged from 20% to 100%, depending on FUS system type, imaging technique, ablation protocol, and patient selection. Specific issues related to FUS ablation of breast cancer, such as increased treatment time for larger tumours, size of ablation margins, methods used for margin assessment and residual tumour detection after FUS ablation, and impact of FUS ablation on sentinel node procedure are presented. Finally, potential future applications of FUS for breast cancer treatment such as FUS-induced anti-tumour immune response, FUS-mediated gene transfer, and enhanced drug delivery are discussed. Currently, breast-conserving surgery remains the gold standard for breast cancer treatment

The size of juxtaluminal hypoechoic area in ultrasound images of asymptomatic carotid plaques predicts the occurrence of stroke

Objective: To test the hypothesis that the size of a juxtaluminal black (hypoechoic) area (JBA) in ultrasound images of asymptomatic carotid artery plaques predicts future ipsilateral ischemic stroke. Methods: A JBA was defined as an area of pixels with a grayscale value <25 adjacent to the lumen without a visible echogenic cap after image normalization. The size of a JBA was measured in the carotid plaque images of 1121 patients with asymptomatic carotid stenosis 50% to 99% in relation to the bulb (Asymptomatic Carotid Stenosis and Risk of Stroke study); the patients were followed for up to 8 years. Results: The JBA had a linear association with future stroke rate. The area under the receiver-operating characteristic curve was 0.816. Using Kaplan-Meier curves, the mean annual stroke rate was 0.4% in 706 patients with a JBA <4 mm 2, 1.4% in 171 patients with a JBA 4 to 8 mm2, 3.2% in 46 patients with a JBA 8 to 10 mm2, and 5% in 198 patients with a JBA >10 mm2 (P <.001). In a Cox model with ipsilateral ischemic events (amaurosis fugax, transient ischemic attack [TIA], or stroke) as the dependent variable, the JBA (<4 mm2, 4-8 mm2, >8 mm2) was still significant after adjusting for other plaque features known to be associated with increased risk, including stenosis, grayscale median, presence of discrete white areas without acoustic shadowing indicating neovascularization, plaque area, and history of contralateral TIA or stroke. Plaque area and grayscale median were not significant. Using the significant variables (stenosis, discrete white areas without acoustic shadowing, JBA, and history of contralateral TIA or stroke), this model predicted the annual risk of stroke for each patient (range, 0.1%-10.0%). The average annual stroke risk was <1% in 734 patients, 1% to 1.9% in 94 patients, 2% to 3.9% in 134 patients, 4% to 5.9% in 125 patients, and 6% to 10% in 34 patients. Conclusions: The size of a JBA is linearly related to the risk of stroke and can be used in risk stratification models. These findings need to be confirmed in future prospective studies or in the medical arm of randomized controlled studies in the presence of optimal medical therapy. In the meantime, the JBA may be used to select asymptomatic patients at high stroke risk for carotid endarterectomy and spare patients at low risk from an unnecessary operation

Asymptomatic internal carotid artery stenosis and cerebrovascular risk stratification

Background The purpose of this study was to determine the cerebrovascular risk stratification potential of baseline degree of stenosis, clinical features, and ultrasonic plaque characteristics in patients with asymptomatic internal carotid artery (ICA) stenosis. Methods This was a prospective, multicenter, cohort study of patients undergoing medical intervention for vascular disease. Hazard ratios for ICA stenosis, clinical features, and plaque texture features associated with ipsilateral cerebrovascular or retinal ischemic (CORI) events were calculated using proportional hazards models. Results A total of 1121 patients with 50% to 99% asymptomatic ICA stenosis in relation to the bulb (European Carotid Surgery Trial [ECST] method) were followed-up for 6 to 96 months (mean, 48). A total of 130 ipsilateral CORI events occurred. Severity of stenosis, age, systolic blood pressure, increased serum creatinine, smoking history of more than 10 pack-years, history of contralateral transient ischemic attacks (TIAs) or stroke, low grayscale median (GSM), increased plaque area, plaque types 1, 2, and 3, and the presence of discrete white areas (DWAs) without acoustic shadowing were associated with increased risk. Receiver operating characteristic (ROC) curves were constructed for predicted risk versus observed CORI events as a measure of model validity. The areas under the ROC curves for a model of stenosis alone, a model of stenosis combined with clinical features and a model of stenosis combined with clinical, and plaque features were 0.59 (95% confidence interval [CI] 0.54-0.64), 0.66 (0.62-0.72), and 0.82 (0.78-0.86), respectively. In the last model, stenosis, history of contralateral TIAs or stroke, GSM, plaque area, and DWAs were independent predictors of ipsilateral CORI events. Combinations of these could stratify patients into different levels of risk for ipsilateral CORI and stroke, with predicted risk close to observed risk. Of the 923 patients with <70% stenosis, the predicted cumulative 5-year stroke rate was <5% in 495, 5% to 9.9% in 202, 10% to 19.9% in 142, and <20% in 84 patients. Conclusion Cerebrovascular risk stratification is possible using a combination of clinical and ultrasonic plaque features. These findings need to be validated in additional prospective studies of patients receiving optimal medical intervention alone. Copyright © 2010 by the Society for Vascular Surgery