“Meth Mouth”: Rampant Caries in methamphetamine abusers

Rampant dental caries is a characteristic finding in methamphetamine abusers. The popularity of methamphetamine, particularly among the gay community where it is linked to the spread of HIV, its ready availability, and rapid spread across the nation have placed methamphetamine use in an epidemic status in many communities unaccustomed to dealing with drug abuse. We present a case of a 25-year-old male “meth” abuser of unknown HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) status to promote recognition by the health care team of the association of rampant dental caries with methamphetamine abuse for appropriate intervention to ensure successful treatment and prevention of disease progression

Melting curve and Hugoniot of molybdenum up to 400 GPa by ab initio simulations

We report ab initio calculations of the melting curve and Hugoniot of molybdenum for the pressure range 0-400 GPa, using density functional theory (DFT) in the projector augmented wave (PAW) implementation. We use the ``reference coexistence'' technique to overcome uncertainties inherent in earlier DFT calculations of the melting curve of Mo. Our calculated melting curve agrees well with experiment at ambient pressure and is consistent with shock data at high pressure, but does not agree with the high pressure melting curve from static compression experiments. Our calculated P(V) and T(P) Hugoniot relations agree well with shock measurements. We use calculations of phonon dispersion relations as a function of pressure to eliminate some possible interpretations of the solid-solid phase transition observed in shock experiments on Mo.Comment: 8 pages, 6 figure

Alignment between PIN1 Polarity and Microtubule Orientation in the Shoot Apical Meristem Reveals a Tight Coupling between Morphogenesis and Auxin Transport

Morphogenesis during multicellular development is regulated by intercellular signaling molecules as well as by the mechanical properties of individual cells. In particular, normal patterns of organogenesis in plants require coordination between growth direction and growth magnitude. How this is achieved remains unclear. Here we show that in Arabidopsis thaliana, auxin patterning and cellular growth are linked through a correlated pattern of auxin efflux carrier localization and cortical microtubule orientation. Our experiments reveal that both PIN1 localization and microtubule array orientation are likely to respond to a shared upstream regulator that appears to be biomechanical in nature. Lastly, through mathematical modeling we show that such a biophysical coupling could mediate the feedback loop between auxin and its transport that underlies plant phyllotaxis

Advanced optical imaging in living embryos

Developmental biology investigations have evolved from static studies of embryo anatomy and into dynamic studies of the genetic and cellular mechanisms responsible for shaping the embryo anatomy. With the advancement of fluorescent protein fusions, the ability to visualize and comprehend how thousands to millions of cells interact with one another to form tissues and organs in three dimensions (xyz) over time (t) is just beginning to be realized and exploited. In this review, we explore recent advances utilizing confocal and multi-photon time-lapse microscopy to capture gene expression, cell behavior, and embryo development. From choosing the appropriate fluorophore, to labeling strategy, to experimental set-up, and data pipeline handling, this review covers the various aspects related to acquiring and analyzing multi-dimensional data sets. These innovative techniques in multi-dimensional imaging and analysis can be applied across a number of fields in time and space including protein dynamics to cell biology to morphogenesis

Potent Delivery of Functional Proteins into Mammalian Cells in Vitro and in Vivo Using a Supercharged Protein

The inability of proteins to potently penetrate mammalian cells limits their usefulness as tools and therapeutics. When fused to superpositively charged GFP, proteins rapidly (within minutes) entered five different types of mammalian cells with potency up to ∼100-fold greater than that of corresponding fusions with known protein transduction domains (PTDs) including Tat, oligoarginine, and penetratin. Ubiquitin-fused supercharged GFP when incubated with human cells was partially deubiquitinated, suggesting that proteins delivered with supercharged GFP can access the cytosol. Likewise, supercharged GFP delivered functional, nonendosomal recombinase enzyme with greater efficiencies than PTDs in vitro and also delivered functional recombinase enzyme to the retinae of mice when injected in vivo.Chemistry and Chemical Biolog

Bridging fluorescence microscopy and electron microscopy

Development of new fluorescent probes and fluorescence microscopes has led to new ways to study cell biology. With the emergence of specialized microscopy units at most universities and research centers, the use of these techniques is well within reach for a broad research community. A major breakthrough in fluorescence microscopy in biology is the ability to follow specific targets on or in living cells, revealing dynamic localization and/or function of target molecules. One of the inherent limitations of fluorescence microscopy is the resolution. Several efforts are undertaken to overcome this limit. The traditional and most well-known way to achieve higher resolution imaging is by electron microscopy. Moreover, electron microscopy reveals organelles, membranes, macromolecules, and thus aids in the understanding of cellular complexity and localization of molecules of interest in relation to other structures. With the new probe development, a solid bridge between fluorescence microscopy and electron microscopy is being built, even leading to correlative imaging. This connection provides several benefits, both scientifically as well as practically. Here, I summarize recent developments in bridging microscopy

Phenotypic Variation and Bistable Switching in Bacteria

Microbial research generally focuses on clonal populations. However, bacterial cells with identical genotypes frequently display different phenotypes under identical conditions. This microbial cell individuality is receiving increasing attention in the literature because of its impact on cellular differentiation, survival under selective conditions, and the interaction of pathogens with their hosts. It is becoming clear that stochasticity in gene expression in conjunction with the architecture of the gene network that underlies the cellular processes can generate phenotypic variation. An important regulatory mechanism is the so-called positive feedback, in which a system reinforces its own response, for instance by stimulating the production of an activator. Bistability is an interesting and relevant phenomenon, in which two distinct subpopulations of cells showing discrete levels of gene expression coexist in a single culture. In this chapter, we address techniques and approaches used to establish phenotypic variation, and relate three well-characterized examples of bistability to the molecular mechanisms that govern these processes, with a focus on positive feedback.

Bayesian Model Selection Applied to the Analysis of Fluorescence Correlation Spectroscopy Data of Fluorescent Proteins in Vitro and in Vivo

Fluorescence correlation spectroscopy (FCS) is a powerful technique to investigate molecular dynamics with single molecule sensitivity. In particular, in the life sciences it has found widespread application using fluorescent proteins as molecularly specific labels. However, FCS data analysis and interpretation using fluorescent proteins remains challenging due to typically low signal-to-noise ratio of FCS data and correlated noise in autocorrelated data sets. As a result, naive fitting procedures that ignore these important issues typically provide similarly good fits for multiple competing models without clear distinction of which model is preferred given the signal-to-noise ratio present in the data. Recently, we introduced a Bayesian model selection procedure to overcome this issue with FCS data analysis. The method accounts for the highly correlated noise that is present in FCS data sets and additionally penalizes model complexity to prevent over interpretation of FCS data. Here, we apply this procedure to evaluate FCS data from fluorescent proteins assayed in vitro and in vivo. Consistent with previous work, we demonstrate that model selection is strongly dependent on the signal-to-noise ratio of the measurement, namely, excitation intensity and measurement time, and is sensitive to saturation artifacts. Under fixed, low intensity excitation conditions, physical transport models can unambiguously be identified. However, at excitation intensities that are considered moderate in many studies, unwanted artifacts are introduced that result in nonphysical models to be preferred. We also determined the appropriate fitting models of a GFP tagged secreted signaling protein, Wnt3, in live zebrafish embryos, which is necessary for the investigation of Wnt3 expression and secretion in development. Bayes model selection therefore provides a robust procedure to determine appropriate transport and photophysical models for fluorescent proteins when appropriate models are provided, to help detect and eliminate experimental artifacts in solution, cells, and in living organisms.National Science Foundation (U.S.). Physics of Living Systems ProgramNational Institute of Mental Health (U.S.) (Award U01MH106011