Pronuclear Migration: No Attachment? No Union,but a Futile Cycle!

How do pronuclei migrate towards each other? The zebrafish futile cycle gene is shown to encode a maternally expressed membrane protein required for nuclear attachment and migration along the sperm aster.     

Contractility assessment in enzymatically isolated cardiomyocytes

The use of enzymatically isolated cardiac myocytes is ubiquitous in modern cardiovascular research. Parallels established between cardiomyocyte shortening responses and those of intact tissue make the cardiomyocyte an invaluable experimental model of cardiac function. Much of our understanding regarding the fundamental processes underlying heart function is owed to our increasing capabilities in single-cell stimulation and direct or indirect observation, as well as quantitative analysis of such cells. Of the many important mechanisms and functions that can be readily assessed in cardiomyocytes at all stages of development, contractility is the most representative and one of the most revealing. The purpose of this review is to provide a survey of various methodological approaches in the literature used to assess adult and neonatal cardiomyocyte contractility. The various methods employed to evaluate the contractile behavior of enzymatically isolated mammalian cardiac myocytes can be conveniently divided into two general categories??those employing optical (image)-based systems and those that use transducer-based technologies. This survey is by no means complete, but we have made an effort to include the most popular methods in terms of reliability and accessibility. These techniques are in constant evolution and hold great promise for the next generation of breakthrough studies in cell biology for the prevention, treatment, and cure of cardiovascular diseases.     

The importance of an exponential prostate-specific antigen decline after external beam radiotherapy for intermediate risk prostate cancer

Background: To study the influence of an exponential prostate-specific antigen (PSA) decline on biochemical failure after external-beam radiotherapy (EBRT). Methods: We analyzed 114 patients with intermediate risk prostate cancer (Gleason ≤ 6 and PSA 10–20 or Gleason 7 and PSA <10). Patients were randomized between EBRT doses of either 70.2 Gy or 79.2 Gy (1.8 Gy per day). All patients had a follow up of at least six PSA measurements post-EBRT. Exponential decline and PSA half life were included in a Cox regression analysis for factors associated with biochemical failure. Results: A total of 80/114 (70.2%) patterns were classified as having an exponential PSA decline. Both exponential decline (HR 0.115, 95%CI 0.03–0.44, p = 0.0016) and PSA half life ratio were statistically significant predictors (HR 1.03 (95% CI 1.01–1.06)) of biochemical failure. In the model predicting for exponential decline, none of the factors were significant. Conclusion: Patients with an exponential PSA decline show a better biochemical outcome in the long term.     

Automatic detection of AutoPEEP during controlled mechanical ventilation

ABSTRACT: BACKGROUND: Dynamic hyperinflation, hereafter called AutoPEEP (auto-positive end expiratory pressure)with some slight language abuse, is a frequent deleterious phenomenon in patients undergoingmechanical ventilation. Although not readily quantifiable, AutoPEEP can be recognized onthe expiratory portion of the flow waveform. If expiratory flow does not return to zero beforethe next inspiration, AutoPEEP is present. This simple detection however requires the eye ofan expert clinician at the patient's bedside. An automatic detection of AutoPEEP should behelpful to optimize care. METHODS: In this paper, a platform for automatic detection of AutoPEEP based on the flow signalavailable on most of recent mechanical ventilators is introduced. The detection algorithms aredeveloped on the basis of robust non-parametric hypothesis testings that require no priorinformation on the signal distribution. In particular, two detectors are proposed: one is basedon SNT (Signal Norm Testing) and the other is an extension of SNT in the sequentialframework. The performance assessment was carried out on a respiratory system analog andex-vivo on various retrospectively acquired patient curves. RESULTS: The experiment results have shown that the proposed algorithm provides relevant AutoPEEPdetection on both simulated and real data. The analysis of clinical data has shown that theproposed detectors can be used to automatically detect AutoPEEP with an accuracy of 93%and a recall (sensitivity) of 90%. CONCLUSIONS: The proposed platform provides an automatic early detection of AutoPEEP. Such functionalitycan be integrated in the currently used mechanical ventilator for continuous monitoring of thepatient-ventilator interface and, therefore, alleviate the clinician task.     

Oligonucleotide and polymer functionalized nanoparticles for amplification-free detection of DNA

Sensitive and quantitative nucleic acid testing from complex biological samples is now an important component of clinical diagnostics. Whereas nucleic acid amplification represents the gold standard, its utility in resource-limited and point-of-care settings can be problematic due to assay interferants, assay time, engineering constraints, and costs associated with both wetware and hardware. In contrast, amplification-free nucleic acid testing can circumvent these limitations by enabling direct target hybridization within complex sample matrices. In this work, we grew random copolymer brushes from the surface of silica-coated magnetic nanoparticles using azide-modified and hydroxyl oligo ethylene glycol methacrylate (OEGMA) monomers. The azide-functionalized polymer brush was first conjugated, via copper-catalyzed azide/alkyne cycloaddition (CuAAC), with herpes simplex virus (HSV)-specific oligonucleotides and then with alkyne-substituted polyethylene glycol to eliminate all residual azide groups. Our methodology enabled control over brush thickness and probe density and enabled multiple consecutive coupling reactions on the particle grafted brush. Brush- and probe-modified particles were then combined in a 20 min hybridization with fluorescent polystyrene nanoparticles modified with HSV-specific reporter probes. Following magnetic capture and washing, the particles were analyzed with an aggregate fluorescence measurement, which yielded a limit of detection of 6 pM in buffer and 60 pM in 50% fetal bovine serum. Adoption of brush- and probe-modified particles into a particle counting assay will result in the development of diagnostic assays with significant improvements in sensitivity.     

Mutant plant viruses with cell binding motifs provide differential adhesion strengths and morphologies

The ability of Tobacco mosaic virus (TMV) to tolerate various amino acid insertions near its carboxy terminus is well-known. Typically these inserts are based on antigenic sequences for vaccine development with plant viruses as carriers. However, we determined that the structural symmetries and the size range of the viruses could also be modeled to mimic the extracellular matrix proteins by inserting cell-binding sequences to the virus coat protein. The extracellular matrix proteins play important roles in guiding cell adhesion, migration, proliferation, and stem cell differentiation. Previous studies with TMV demonstrated that the native and phosphate-modified virus particles enhanced stem cell differentiation toward bone-like tissues. Based on these studies, we sought to design and screen multiple genetically modified TMV mutants with reported cell adhesion sequences to expand the virus-based tools for cell studies. Here, we report the design of these mutants with cell binding amino acid motifs derived from several proteins, the stabilities of the mutants against proteases during purification and storage, and a simple and rapid functional assay to quantitatively determine adhesion strengths by centrifugal adhesion assay. Among the mutants, we found that cells on TMV expressing RGD motifs formed filopodial extensions with weaker attachment profiles, whereas the cells on TMV expressing collagen I mimetic sequence displayed little spreading but higher attachment strengths.     

Organically modified silica nanoparticles are biocompatible and can be targeted to neurons in vivo

The application of nanotechnology in biological research is beginning to have a major impact leading to the development of new types of tools for human health. One focus of nanobiotechnology is the development of nanoparticle-based formulations for use in drug or gene delivery systems. However most of the nano probes currently in use have varying levels of toxicity in cells or whole organisms and therefore are not suitable for in vivo application or long-term use. Here we test the potential of a novel silica based nanoparticle (organically modified silica, ORMOSIL) in living neurons within a whole organism. We show that feeding ORMOSIL nanoparticles to Drosophila has no effect on viability. ORMOSIL nanoparticles penetrate into living brains, neuronal cell bodies and axonal projections. In the neuronal cell body, nanoparticles are present in the cytoplasm, but not in the nucleus. Strikingly, incorporation of ORMOSIL nanoparticles into the brain did not induce aberrant neuronal death or interfered with normal neuronal processes. Our results in Drosophila indicate that these novel silica based nanoparticles are biocompatible and not toxic to whole organisms, and has potential for the development of long-term applications.