Usefulness of whole blood aggregometry and its comparison with thromboxane generation assay in monitoring acetylsalicylic acid effectiveness--a multiparametric study in rats.

BACKGROUND: There is a need for consensus concerning universal methodological criteria for detection of suboptimal response to acetylsalicylic acid (ASA) therapy. Therefore, animal models to test for ASA effectiveness remain of interest. Our objective was to verify the usefulness of multiparametric whole-blood impedance aggregometry and thromboxane A(2) generation, which are the most popular techniques used for monitoring of ASA treatment effectiveness. METHODS: Using multiparametric analysis of whole-blood impedance aggregometry, we examined which parameters of platelet aggregation or disaggregation allow for the best discrimination between ASA-treated (4 or 40 mg/kg for 60 days) and non-treated male rats. The effectiveness of ASA-mediated inhibition of platelet cyclooxygenase-1 was verified by determination of plasma thromboxane B(2) and urine 11-dehydro-thromboxane B(2), accepted as reference assays for monitoring of ASA-mediated platelet cyclooxygenase-1 inhibition. RESULTS: Two of the platelet agonists used, collagen (1 mg/L) and arachidonic acid (0.5 mmol/L), allowed discrimination of control and ASA-treated animals, whereas adenosine diphosphate (5 micromol/L) was not effective. It is noteworthy that only ASA-mediated changes in duration of the rising phase for platelet aggregation and the area under the curve for collagen-induced aggregation allowed significant discrimination between low and high ASA dose and remained correlated with the reference parameter, plasma thromboxane B(2). CONCLUSIONS: Analysis of aggregation curves, routinely based only on the amplitude and rate of platelet aggregation, may not be enough discriminative to distinguish between varying ASA doses and treatment schedules.     

Thermal,Mechanical, and Acoustic Properties of Polydimethylsiloxane Filled with Hollow Glass Microspheres

Polydimethylsiloxane (PDMS) is the most widely used silicon-based polymer due to its versatility and its various attractive properties. The fabrication of PDMS involves liquid phase cross-linking to obtain hydrophobic and mechanically flexible material in the final solid form. This allows to add various fillers to affect the properties of the resulting material. PDMS has a relatively low Thermal Conductivity (TC), in the order of 0.2 W/mK, which makes it attractive for thermal insulation applications such as sealing in construction. Although a further decrease in the TC of PDMS can be highly beneficial for such applications, most research on the thermal properties of PDMS composites have focused on fillers that increase the TC rather than decrease it. In the present work, we propose a simple and reliable method for making a PDMS-based composite material with significantly improved thermal insulation properties, by adding hollow glass microspheres (HGMs) to the mixture of the liquid base and the cross-linker (10:1 ratio), followed by degassing and heat-assisted crosslinking. We obtained a 31% reduction of thermal conductivity and a 60% increase in the elastic modulus of samples with HGM content of 17% by weight. At the same time, the sound insulation capacity of the PDMS-HGM composite is slightly decreased in comparison to pure PDMS, as a result of its lower density. Finally, the wettability of the samples had no dependence on HGM content.     

Unequal representation of cardinal vs. oblique orientations in the middle temporal visual area

A possible neurobiological basis for the "oblique effect" is linked to the finding that more neural machinery is devoted to processing cardinal vs. oblique orientations in primary visual cortex (V1). We used optical imaging to determine whether more territory is devoted to processing horizontal and vertical orientations than oblique orientations in owl monkey middle temporal visual area (MT), a visual area highly sensitive to moving stimuli. We found that more of MT was devoted to representing cardinal than oblique orientations, and that the anisotropy was more prominent in parts of MT representing central vision (< or =10 degrees). Neural responses to orientations of 0 degrees and 90 degrees were also greater than those to 45 degrees and 135 degrees . In comparison, an overrepresentation of cardinal orientations in the representation of central vision in owl monkey V1 was relatively small and inconsistent. Our data could explain the greater sensitivity to motion discrimination when stimuli are moved along cardinal meridians and suggest that the neural machinery necessary to explain the motion oblique effect either originates in MT or is enhanced at this level.     

Comparison of survival among patients with connective tissue disease and cardiomyopathy (systemic sclerosis, systemic lupus erythematosus, and undifferentiated disease)

Connective tissue disease (CTD) encompasses several disease or abnormal states characterized by inflammatory or degenerative changes in connective tissue. These disorders affect many organs, including the heart. However, the long-term survival of patients with cardiomyopathy and CTD is not known. The prognostic implications of different categories of CTD were studied in patients with cardiomyopathy. One thousand seven hundred patients with initially unexplained cardiomyopathy who underwent endomyocardial biopsy from 1983 to 2003 at The Johns Hopkins Hospital were evaluated. Seventy-one subjects were diagnosed with CTD. This cohort was followed for an average of 5.1 years. Among the different disorder categories within CTD, there was a significantly lower survival rate for subjects with undifferentiated CTD (adjusted hazard ratio for death 2.39, 95% confidence interval 1.27 to 4.48, p = 0.007) and a trend toward decreased survival in patients with systemic sclerosis (adjusted hazard ratio for death 1.75, 95% confidence interval 0.93 to 3.29, p = 0.081) compared with those with idiopathic dilated cardiomyopathy (DCM). No significant survival difference was observed between systemic lupus erythematosus and idiopathic DCM (p = 0.41). The long-term outcomes of subjects with CTD and myocarditis were not statistically different from the outcomes of those with CTD and no myocarditis (p = 0.71). In conclusion, the diagnosis of cardiomyopathy and either undifferentiated CTD or systemic sclerosis appears to be a poor prognostic indicator compared with the diagnosis of idiopathic DCM. Patients with systemic lupus erythematosus and cardiomyopathy have a similar prognosis to those with idiopathic DCM. Finally, the presence of myocarditis does not alter the survival of patients with CTD and cardiomyopathy.     

Enhanced transduction of malignant glioma with a double targeted Ad5/3-RGD fiber-modified adenovirus

Malignant brain tumors remain refractory to adenovirus type 5 (Ad5)-based gene therapy, mostly due to the lack of the primary Ad5 receptor, the coxsackie and adenovirus receptor, on brain tumor cells. To bypass the dependence on coxsackie and adenovirus receptor for adenoviral entry and infectivity, we used a novel, double targeted Ad5 backbone-based vector carrying a chimeric Ad5/3 fiber with integrin-binding RGD motif incorporated in its Ad3 knob domain. We then tested the new virus in vitro and in vivo in the setting of malignant glioma. Ad5/3-RGD showed a 10-fold increase in gene expression in passaged cell lines and up to 75-fold increase in primary tumors obtained from patients relative to the control. These results were further corroborated in our in vivo human glioma xenograft model, where the Ad5/3-RGD vector showed a 1,000-fold increase in infectivity as compared with the control. Taken together, our findings indicate that Ad5/3-RGD may be a superior vector for applications in glioma gene therapy and therefore warrants further attention in the field of neuro-oncology.     

Palmitoylation regulates raft affinity for the majority of integral raft proteins

The physical basis for protein partitioning into lipid rafts remains an outstanding question in membrane biology that has previously been addressed only through indirect techniques involving differential solubilization by nonionic detergents. We have used giant plasma membrane vesicles, a plasma membrane model system that phase separates to include an ordered phase enriching for raft constituents, to measure the partitioning of the transmembrane linker for activation of T cells (LAT). LAT enrichment in the raft phase was dependent on palmitoylation at two juxtamembrane cysteines and could be enhanced by oligomerization. This palmitoylation requirement was also shown to regulate raft phase association for the majority of integral raft proteins. Because cysteine palmitoylation is the only lipid modification that has been shown to be reversibly regulated, our data suggest a role for palmitoylation as a dynamic raft targeting mechanism for transmembrane proteins.     

Auxin transport inhibitors impair vesicle motility and actin cytoskeleton dynamics in diverse eukaryotes

Many aspects of plant development, including patterning and tropisms, are largely dependent on the asymmetric distribution of the plant signaling molecule auxin. Auxin transport inhibitors (ATIs), which interfere with directional auxin transport, have been essential tools in formulating this concept. However, despite the use of ATIs in plant research for many decades, the mechanism of ATI action has remained largely elusive. Using real-time live-cell microscopy, we show here that prominent ATIs such as 2,3,5-triiodobenzoic acid (TIBA) and 2-(1-pyrenoyl) benzoic acid (PBA) inhibit vesicle trafficking in plant, yeast, and mammalian cells. Effects on micropinocytosis, rab5-labeled endosomal motility at the periphery of HeLa cells and on fibroblast mobility indicate that ATIs influence actin cytoskeleton. Visualization of actin cytoskeleton dynamics in plants, yeast, and mammalian cells show that ATIs stabilize actin. Conversely, stabilizing actin by chemical or genetic means interferes with endocytosis, vesicle motility, auxin transport, and plant development, including auxin transport-dependent processes. Our results show that a class of ATIs act as actin stabilizers and advocate that actin-dependent trafficking of auxin transport components participates in the mechanism of auxin transport. These studies also provide an example of how the common eukaryotic process of actin-based vesicle motility can fulfill a plant-specific physiological role.