cssi/SciSciGPT-SciSciNet huggingface dataset:
Msh2 Blocks an Alternative Mechanism for Non-Homologous Tail Removal during Single-Strand Annealing in Saccharomyces cerevisiae

Chromosomal translocations are frequently observed in cells exposed to agents that cause DNA double-strand breaks (DSBs), such as ionizing radiation and chemotherapeutic drugs, and are often associated with tumors in mammals. Recently, translocation formation in the budding yeast, Saccharomyces cerevisiae, has been found to occur at high frequencies following the creation of multiple DSBs adjacent to repetitive sequences on non-homologous chromosomes. The genetic control of translocation formation and the chromosome complements of the clones that contain translocations suggest that translocation formation occurs by single-strand annealing (SSA). Among the factors important for translocation formation by SSA is the central mismatch repair (MMR) and homologous recombination (HR) factor, Msh2. Here we describe the effects of several msh2 missense mutations on translocation formation that suggest that Msh2 has separable functions in stabilizing annealed single strands, and removing non-homologous sequences from their ends. Additionally, interactions between the msh2 alleles and a null allele of RAD1, which encodes a subunit of a nuclease critical for the removal of non-homologous tails suggest that Msh2 blocks an alternative mechanism for removing these sequences. These results suggest that Msh2 plays multiple roles in the formation of chromosomal translocations following acute levels of DNA damage.
HIV gp41-Antibody Interaction at the Viral Membrane Interface Defined by EPR Spectroscopy

HIV enters human T cells through the fusion of viral and host-cell membranes. This fusion process is mediated by a surface protein, gp41, and the platform provided by the cholesterol-rich viral membrane. The membrane proximal ectodomain region (MPER) of gp41 plays a critical role in this fusion process and is a major target of anti-gp41 antibodies and vaccine design. Here, EPR and NMR techniques were used to define MPER structure on the membrane, and how neutralizing anti-gp41 antibodies recognize their membrane-immersed epitopes and disrupt a hinge-related function of the MPER. The analyses of several HIV-1 clade B and clade C MPERs revealed a structurally conserved pair of helices immersed in the viral membrane separated by a flexible hinge, which include critical helix capping residues. Double alanine mutations of the capping residues result in an altered hinge structure with a deeper lipid-buried MPER middle region, as well as reduced viral fusion and infectivity. Furthermore, neutralizing anti-gp41 antibodies disrupt the MPER hinge function by perturbing MPER hinge orientation, and/or extracting part of the MPER from the membrane. The interaction can be a stepwise rearrangement through an apparent scoop-like movement of the antibodies’ long and unique CDRH3 segments. Mutations of the CDRH3 segments reduced the ability of the antibodies to extract MPER residues from the membrane, without affecting peptide binding in solution. In addition, MPER-membrane interaction and antibody binding are modulated by lipid composition and cholesterol content. These findings have revealed important features of gp41-antibody interaction at the viral membrane interface.
Specific Impulse and Other Characteristics of Elementary Propellants for Ablative Laser Propulsion

This work was performed as a continuation of ablative laser propulsion (ALP) research recently revived by the authors. An ALP-based space vehicle would be driven by high-energy, short-duration (10 -10 s and less) laser pulses, focused on a solid propellant. Under such irradiation conditions, plasma and laser pulses are temporally separated, and the direct ablation of solid propellant dominates other possible momentum transfer mechanisms. The studies were performed for various elemental targets, ablated at irradiances up to ∼3 × 10 13 W/cm 2 delivered by 100-ps laser pulses at a wavelength of 532 nm. The data, collected predominantly from time-of-flight technique, include ion velocities, number densities, ion density angular distributions, and mass-removal rates. From these data, specific impulses and net momenta exerted on targets by ablation were calculated. For the irradiation conditions used, the highest I sp and lowest mass-removal rates were achieved for low-Z targets, whereas high-Z elements provided higher momenta. The upper limits for I sp derived from ion velocity reached 2 x 10 4 s with carbon (graphite). Ion energies varied from element to element in the range of ∼0.4-2.0 keV, with ion fractions of ∼0.8-3.8% and mass-removal rates in the range of 0.1-3.0 μg per laser pulse. Ion velocities exhibit Maxwellian distributions, whereas ion number densities in the plasma plume were fitted to a cosine function. All studied characteristics indicate that high-I sp ALP must be based on solid low-Z propellants such as a carbon or aluminum.
A RAPID SIMPLE TECHNIQUE UTILIZING CALCOFLUOR WHITE M2R FOR THE VISUALIZATION OF DINOFLAGELLATE THECAL PLATES

The fluorescent stain Calcofluor White M2R readily binds to cellulose and other β-linked glucans (Hughs and McCully 1975). We have found the stain to readily bind to the thecal plates of armored dinoflagellates. Considerable detail is revealed about plate structure in both living and preserved specimens at the light microscopic level. This simple rapid technique should prove useful for the tabulation and study of dinoflagellate thecae.
Implementation of an Appropriate Household Water Purification System in Tourou, Cameroon

The two goals of this project were to develop a household water purification method and to provide a framework for sustaining this technology in a low-income community. According to the World Health Organization, waterborne diseases are a leading cause of illness and death in developing countries. Over 1.1 billion people across the world lack access to an improved water supply, leading to diseases that disproportionately affect children. Water purification methods used in high-income nations are neither economically nor technically feasible in low-income countries. As a result, there is a critical need for inexpensive, appropriate water purification technologies. The system developed was tested in Tourou, Cameroon.
The effect of calcium spray on leaf and bract distortion, bound:unbound calcium ratio, and calcium distribution in two poinsettia cultivars

Abstract To determine if direct Ca sprays could affect the distribution and binding of Ca in the leaves and the severity of leaf/bract distortion in two varieties of poinsettia (Euphorbia pulcherimma Willd.), we applied either 100 mg.l‐1 or 400 mg.1‐1 of Ca either one time or weekly to leaves of distortion‐ susceptible ('V‐14 Glory') and nonsusceptible ('Annette Hegg Dark Red,’ AHDR) cultivars. Only weekly spraying with 400 mg.l‐1 Ca reduced distortion in V‐14 plants, compared to controls or AHDR plants. Both bound and unbound Ca concentrations were higher in AHDR leaves than in V‐14 leaves, but these differences were not correlated with distortion severity. EDX analysis demonstrated that distorted regions of V‐14 leaves and bracts had lower Ca concentrations than did undistorted regions or AHDR leaves; weekly spraying with 400 mg.l‐1 Ca produced relatively uniform leaf Ca distribution in V‐14 leaves. Localized Ca deficiencies appear to produce the bract/leaf distortion in ‘V‐14 Glory’ plants, and these d...
Prevention and treatment of diabetic foot wounds

The diabetic foot ulcer is one of the most common and devastating complications of diabetes mellitus. These ulcers account for most of the hospital admissions for patients with diabetes, and they represent a common precursor for amputation. When a diabetic foot ulcer becomes infected, gangrene and amputation can follow in rapid succession. Recent reviews concerning diabetic foot lesions and amputations have stressed the magnitude and importance of aggressive management. This management is complicated, and typically requires radical debridement, appropriate antibiotics, non-weight-bearing, and vascular surgery when indicated. A variety of adjunctive therapy can be helpful, including hyperbaric oxygen and topical growth factors. The most important step in preventing ulceration of the foot is patient education in foot care.
Pericarditis due to Anaerobic Bacteria

This review describes the microbiology, diagnosis and management of pericarditis due to anaerobic bacteria. The predominant anaerobes recovered from patients with pericarditis were: gram-negative bacilli (mostly of the Bacteroides fragilis group), anaerobic streptococci, Clostridium spp., Fusobacterium spp., and Bifidobacterium spp. Anaerobic bacteria can be isolated in pericarditis resulting from the following mechanisms: (1) spread from a contiguous focus of infection, either de novo or after surgery or trauma (pleuropulmonary, esophageal fistula or perforation, and odontogenic); (2) spread from a focus of infection within the heart, most commonly from endocarditis; (3) hematogenous infection, and (4) direct inoculation as a result of a penetrating injury or cardiothoracic surgery. No differences were found in the clinical diagnostic features between cases of pericarditis due to anaerobic bacteria and those due to aerobic and facultative bacteria. Anaerobic gram-negative bacilli have increased their resistance to penicillins and other antimicrobials in the last decade. Complete identification and testing for antimicrobial susceptibility and lactamase production are therefore essential for the management of infections caused by these bacteria. Treatment of pericarditis involving anaerobic bacteria includes the use of antibiotic therapy effective against these organisms.
Nucleation products of ligated nanoclusters unaffected by temperature and reducing agent

Atomically uniform nucleation products of ligated metal nanoclusters are observed irrespective of reduction conditions for metal–bidentate ligand systems. Monodentate ligands are not reported to wield similar control, indicating steric contributions of complexing ligands may be as important as their electronic structure for synthesizing small nanoclusters.
Margins for ASME Code Fatigue Design Curve: Effects of Surface Finish and Material Variability

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. This Code specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life (e-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of the existing fatigue e-N data for carbon and low-alloy steels and wrought and cast austenitic SSs to define the effects of key material, loading, and environmental parameters on the fatigue lives of the steels. Experimental data are presented on the effects of surface roughness on the fatigue life of these steels in air and LWR environments. Statistical models are presented for estimating the fatigue e-N curves as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue evaluations. A critical review of the margins for the ASME Code fatigue design curve is presented.Copyright © 2003 by ASME
Virtual medication therapy management: The cornerstone to a pharmacy renaissance

Abstract Objectives To introduce an innovative clinical service that can be used to reduce medication errors and improve quality of care in the rural environment, in order to assist in eliminating or alleviating disparities in health based on geographical location. Summary Virtual medication therapy management (MTM) will be a tool to assist underserved populations, specifically residents of rural communities. It will use videoconferencing software to provide MTM services to populations that lack access to care. For virtual MTM to be effective, specific measures must be implemented to comply with the Health Insurance Portability and Accountability Act, and state regulations must be established to standardize the practice. Conclusion The virtual MTM model is a feasible and promising model for advancing MTM services. With commitment and cooperation from various health care fields, virtual MTM could be the cornerstone of a health care renaissance.
Variable Air Volume System Application in Museums

Relative humidity and temperature control is key in museums, galleries, libraries and archives. Normally constant volume (CV) air handling units (AHUs) with reheat coils are applied in these buildings. Setting a low supply air temperature limits the highest humidity level; however, reheat coils have to be used to maintain space temperature due to constant supply airflow. As a result, simultaneous heating and cooling exists with excessive energy consumption. It is well known that variable air volume (VAV) technologies can reduce simultaneous heating and cooling as well as fan power. This paper presents the detail VAV system retrofit for the existing CV system, control sequence development and system performance evaluation in a museum facility at Omaha, Nebraska. Variable Frequency Drives (VFDs) were installed for the supply fan on the AHUs. Space humidity and temperature, heating and cooling energy consumption, and fan power were measured. The measurements showed that the space humidity and temperature was maintained within the required range under VAV operation while the reheat consumption was reduced by up to 85% and the fan power consumption was reduced by 90% under partial cooling loads.Copyright © 2007 by ASME
Future directions in the treatment of pancreatic cancer

Fewer than 20% of patients with pancreatic cancer present with disease macroscopically confined to the pancreas, and approximately 40% already have locally advanced disease. Based on data from the Gastrointestinal Tumor Study Group, adjuvant therapy with radiation and 5-fluorouracil has become standard practice in the United States; however, in other countries, adjuvant treatment has not been as widely accepted. Other issues include the potential of neoadjuvant therapy and optimal systemic management. The issue of second-line therapy has also been raised in the treatment of pancreatic carcinoma, after the establishment of gemcitabine as a first-line standard treatment approach, in which it achieves a significant clinical benefit response. Other combination partners with gemcitabine under investigation include the antimetabolite 5-fluorouracil, the topoisomerase-I inhibitor irinotecan, the taxane docetaxel, the platinum oxaliplatin, the multitargeted antifolate pemetrexed, the farnesyl transferase inhibitor R-115777, the anti-HER2/neu antibody trastuzumab, and the epidermal growth factor inhibitor cetuximab. Combined-modality approaches with gemcitabine and radiation are also under active investigation. Semin Oncol 29 (suppl 20):31-39. Copyright 2002, Elsevier Science (USA). All rights reserved.
Roles of urea and TMAO on the interaction between extended non-polar peptides

In this study, we investigate the role played by urea and trimethylamine n-oxide (TMAO) in the stability of extended poly-alanine and poly-leucine dimers using all-atom molecular dynamics simulations and the explicit TIP3P water model. An umbrella sampling protocol is used to compute the potential of mean force (PMF) describing the interaction between these dimers at different concentrations of urea and TMAO. We show that while urea has a destabilizing effect on the interaction between poly-leucine chains, TMAO has an opposite effect. This is consistent with the use of urea as a denaturant and TMAO as an osmolyte stabilizing native structures of proteins. However, both cosolvents have no significant effect on the interaction between poly-alanine chains. To unravel the molecular mechanisms of TMAO and urea, we study enthalpic components of the energy, i.e., Lennard-Jones and electrostatic energies. No clear correlation is observed between changes in the enthalpy and the PMF, suggesting that an indirect mechanism mediated by water molecules could be responsible for the role of urea and TMAO. To provide insights into the interaction of urea and TMAO with the peptide dimer, we compute preferential interaction coefficients and spatial distributions of cosolvent and water around poly-alanine and poly-leucine. Urea and TMAO have a distinct distribution around the peptide with urea preferring to be located in its vicinity.
The Photoreceptor G-Protein Transducin (Gt) Is a Substrate for Ubiquitin-Dependent Proteolysis

Abstract Bovine photoreceptor (rod outer segment) proteins were selectively degraded by an ATP- and ubiquitin-dependent mechanism in rabbit reticulocyte lysate and human retinal pigment epithelial cell supernatant. Proteolysis of 37, 40, 58, 68 and ≍100 kDa proteins was accompanied by the formation of high mass (>150 kDa) species (putative ubiquitin-protein conjugates. To identity degraded substrates, the photoreceptor GTP-binding protein, transducin (Gtαβγ), was purified by GTP elution. Degradation of transducin (≥50% loss of each subunit) by retinal pigment epithelial cell supernatant was ubiquitin-dependent (EC50 = 1.2 μM). Formation of high mass transducin species was coincident with degradation. These data identify a selective proteolytic mechanism that may regulate the photoreceptor GTP-binding protein.
Cryosphere: Bottom-up restructuring of ice

Water at the base of ice sheets can lead to faster ice flow. Radar sounding of the Greenland ice sheet reveals that refreezing of this water can also induce large changes in ice flow and structure.
A Quantum Mechanical and Molecular Mechanical Method Based on CM1A Charges: Applications to Solvent Effects on Organic Equilibria and Reactions

A combined quantum mechanical and molecular mechanical method is presented and tested through Monte Carlo statistical mechanics simulations. The method is general and computationally efficient for obtaining energetic and structural results for organic processes in the liquid phase. The solutes are represented quantum mechanically through AM1 calculations, and the solvent is treated explicitly with classical OPLS potential functions. The interaction between the quantum and classical parts of the systems is computed classically using scaled partial charges for the solute atoms that are derived from the AM1 wave function via the CM1A procedure of Cramer and Truhlar. The new methodology is tested through computation of free energies of hydration of thirteen diverse organic molecules, the medium dependence of the conformational equilibria for 1,2-dichloroethane and furfural, the acceleration of the Claisen rearrangement of allyl vinyl ether in water, and the medium dependence of the tautomeric equilibrium for ...
Is a bird in the hand worth more than two in the bush? Limitations of priority cognizance in conflict resolution for firm real-time database systems

After a "boom" period from the late 80s to the early 90s, there appears to have been a reduction in the amount of work published on Concurrency Control (CC) in real-time database systems (RTDBS) in general and firm RTDBS in particular. This may be because existing paradigms (e.g., Optimistic CC) have been pushed to their limits and it is difficult to extract additional meaningful performance. One of the last unresolved bastions of real-time CC is the successful incorporation of priority cognizance. Researchers have speculated that priority cognizant optimistic concurrency control (OCC) algorithms, if designed well, could outperform priority insensitive ones in real-time database systems. So far, however, there is a distinct lack of conclusive proof available on this topic and the priority cognizant OCC algorithms that have appeared so far in the literature cannot claim unilateral superiority over their priority insensitive relatives. We thus surmise that successful incorporation of priority cognizance may lead to an increase in the performance of OCC protocols in firm RTDBSs. Based on this premise, we analyze the issue of priority cognizance and identify a critical condition that must hold for priority cognizant conflict resolution to work. The condition is that, on the average, the conflict sets of validating transactions should have a "large" number of transactions: We call this a bird in hand more than two in the bush phenomenon. Subsequently, we design a smart priority cognizant OCC variant, which we call OCC-APR, and analyze its performance, as well as that of several other concurrency control algorithms across a wide range of resource contention and system loading parameters. Surprisingly, it turns out that it is very difficult for priority cognizance to work as the above mentioned condition does not, usually,hold. We explain why this occurs and conclude that priority cognizance does not appear to be a promising technique to increase real-time CC performance. The contribution of this paper, thus, is to have laid to rest the "priority cognizance" issue with regard to real-time CCMs.
Genome Structure and Evolution of Naegleria and its Relatives

In the 4 yr since the molecular biology of DNA in Naegleria was last reviewed several major advances have been made, and these are reviewed here: isolation and characterization of mitochondrial and ribosomal DNAs; enumeration of chromosomal DNAs by pulsed field gel electrophoresis; sequence analysis of differentially expressed genes; phylogenetic placement of the genus Naegleria among the eukarayotes and Naegleria species within the genus.
How Schizophrenia Develops: Cognitive and Brain Mechanisms Underlying Onset of Psychosis

Identifying cognitive and neural mechanisms involved in the development of schizophrenia requires longitudinal observation of individuals prior to onset. Here recent studies of prodromal individuals who progress to full psychosis are briefly reviewed in relation to models of schizophrenia pathophysiology. Together, this body of work suggests that disruption in brain connectivity, driven primarily by a progressive reduction in dendritic spines on cortical pyramidal neurons, may represent a key triggering mechanism. The earliest disruptions appear to be in circuits involved in referencing experiences according to time, place, and agency, which may result in a failure to recognize particular cognitions as self-generated or to constrain interpretations of the meaning of events based on prior experiences, providing the scaffolding for faulty reality testing.
Undetected Errors in Quasi-Cyclic LDPC Codes Caused by Receiver Symbol Slips

Low-density parity-check (LDPC) codes are capacity-approaching forward error correction codes that operate at signal-to-noise ratio (SNR) decoding thresholds very near to the capacity limits. Receivers designed for less optimal codes might not function smoothly at the lower values of SNR where LDPC codes can operate. In particular, an artifact of low-SNR receiver operation is the increased probability of symbol slips. Receiver synchronization errors resulting from symbol insertions or deletions can cause unexpected decoder problems, especially for an LDPC code with a quasi-cyclic construction. In this paper we analyze the theoretical basis for symbol slips to cause undetected errors with quasi-cyclic codes, and we demonstrate these effects via simulations. We also examine several no-cost to low-cost solutions that can mitigate these effects.
A fully digital frequency shift keying demodulator chip for wireless biomedical implants

A fully digital frequency shift keying (D-FSK) data transfer protocol and demodulator circuit has been developed with the data-rate to carrier-frequency ratio of up to 67%. Its primary application is in the magnetically coupled wireless systems such as biomedical implants and RFID-tags with high data rates above 1 Mbps. The demodulator circuit extracts the serial data bit stream and a constant-frequency clock from an FSK carrier signal in the 4/spl sim/20 MHz range, which can power the wireless system as well. The circuit occupies 0.29 mm/sup 2/ in the AMI 1.5 /spl mu/m 2M/2P standard CMOS process and has a simulated data-rate of up to 2 Mbps and a measured rate of 200 Kbps while consuming less than 0.4 mW.
Transducer for Mechanical Impedance Testing over a Wide Frequency Range

We describe a feedback-controlled active mechanical probe which can achieve a very low mechanical impedance, uniformly over a wide frequency range. The feedback produces a state of quasi-resonance which transforms the probe into a source of force used to excite an unknown load, resulting in a precise measurement of the real and imaginary components of the load impedance at any frequency. The instrument is applied to the determination of the mechanical impedance of a fingertip.
Surface modification of inorganic oxide particles with silane coupling agent and organic dyes

The silane coupling agent 3-glycidoxypropyl trimethoxylsilane (GPS) was grafted onto the surface of silica gel, P2 glass beads and TiO2 oxide particles. FT-IR, thermogravimetric and elemental analysis were used to characterize the modified particles. The effects of various factors on the GPS grafting efficiency such as catalyst, GPS concentration, reaction temperature and time were studied. After modification with GPS, the xanthene dye rhodamine B and azo dyes 4-phenylazophenol and 4-phenylazoaniline, respectively, were grafted on to the particles, which were then used as pigment fillers. The colors of the pigments were adjusted by changing the kind of dyes, the concentration, the pH and the reaction solvents. Copyright © 2001 John Wiley & Sons, Ltd.
New photonic crystal system for integrated optics

We describe a new photonic-crystal structure with a complete three-dimensional photonic band gap (PBG) and its potential application to integrated optics. The structure not only has a large band gap and is amenable to layer-by-layer litho-fabrication, but also introduces the feature of high-symmetry planar layers resembling two-dimensional photonic crystals. This feature enables integrated optical devices to be constructed by modification of only a single layer, and supports waveguide and resonant-cavity modes that strongly resemble the corresponding modes in the simpler and well-understood 2d systems. In contrast to previous attempts to realize 2d crystals in 3d via finite-height “slabs,” however, the complete PBG of the new system eliminates the possibility of radiation losses. Thus, it provides a robust infrastructure within which to embed complex optical networks, combining elements such as compact filters, channel-drops, and waveguide bends/junctions that have previously been proposed in 2d photonic crystals.
Archaeological Textile Evidence for Historic Costume Study: Louisiana Tiger Rifles 1861

The purpose of this research was to analyze fabric remains from the grave of an American Civil War confederate soldier of the Louisiana Tiger Rifles who was executed by military firing squad in December 1861 near Manassas, Virginia. No confirmed visual examples of this uniform exist.A small layered mass of fabric wasfound in this grave. Fourteen fabric samples in nine layers, none larger than 10.2 cm2, were analyzed by compound light microscope, stereomicroscope, and scanning electron microscopefor fiber content, color, and fabric construction. Garment silhouettes were not obtainable through this research nor were details on lower body garments. Upper body garments were identified as a dark silk cravat located in the top layer above a porcelain shirt button. The next layer was a blue wool, twill weave jacket with red, plain weave wool binding on the edge. The only other garment was a cream colored, plain weave wool shirt with interface stiffening in the front placket region. The data were used to help rec...
Stabilization with disturbance attenuation over a Gaussian channel

We propose a linear control and communication scheme for the purposes of stabilization and disturbance attenuation when a discrete Gaussian channel is present in the feedback loop. Specifically, the channel input is amplified by a constant gain before transmission and the channel output is processed through a linear time invariant filter to produce the control signal. We show how the gain and filter may be chosen to minimize the variance of the plant output. For an order one plant, our scheme achieves the theoretical minimum taken over a much broader class of compensators.
Expression of transferrin receptors during differentiation of human placental trophoblast cells in vitro

Abstract In most cell types, transferrin receptor expression is correlated with the proliferation rate, being increased by growth stimulation, or decreased by induction of terminal differentiation. In the human placenta the multinucleated syncytiotrophoblast, in direct contact with maternal blood, is derived by differentiation from mononucleated cytotrophoblast. In this study we examined changes in transferrin receptor expression during in vitro differentiation of trophoblast. Cells cultured in Ham 's/Waymouth's medium (HWM) remained primarily mononuclear throughout the study, whereas incubation in keratinocyte growth medium (KGM) led to formation of multinucleate masses within 2–3 days of culture. Cell surface binding of 125 I- labelled transferrin increased fivefold between days 1–5 of culture in both media and surface receptors were saturated at 7–14 μg/ml (90–200 fM). At saturation, the amount of transferrin bound to syncytiotrophoblast was 37 per cent lower than in cytotrophoblast. Scatchard analysis revealed a reduction in the number of surface transferrin receptors in syncytiotrophoblast compared to cytotrophoblast. A corresponding 29 per cent reduction in the binding of transferrin to intracellular sites was observed in syncytiotrophoblast. Distribution of receptors between surface and intracellular sites was therefore similar in both cytotrophoblast and syncytiotrophoblast. The affinity of transferrin for transferrin receptors was 3.7 fold higher in syncytiotrophoblast when compared to cytotrophoblast. Observed differences between the two cell types were not due to the presence of growth factors or higher iron levels in KGM. Expression of a high number of surface transferrin receptors in syncytiotrophoblast (1.5 × 10 12 /mg protein), along with a high affinity of these receptors for iron-saturated transferrin, could help explain the efficient transport of large amounts of iron from mother to fetus.
Curvature and the evolution of fronts

The evolution of a front propagating along its normal vector field with speedF dependent on curvatureK is considered. The change in total variation of the propagating front is shown to depend only ondF/dK only whereK changes sign. Analysis of the caseF(K)=1−eK, where e is a constant, shows that curvature plays a role similar to that of viscosity in Burgers equation. For e=0 and non-convex initial data, the curvature blows up, corners develop, and an entropy condition can be formulated to provide an explicit construction for a weak solution beyond the singularity. We then numerically show that the solution as e goes to zero converges to the constructed weak solution. Numerical methods based on finite difference schemes for marker particles along the front are shown to be unstable in regions where the curvature builds. As a remedy, we show that front tracking based on volume of fluid techniques can be used together with the entropy condition to provide transition from the classical to weak solution.
Frequency analysis of the wavefront-coding odd-symmetric quadratic phase mask

A mathematical analysis of the frequency response of the wavefront-coding odd-symmetric quadratic phase mask is presented. An exact solution for the optical transfer function of a wavefront-coding imager using this type of mask is derived from first principles, whose result applies over all misfocus values. The misfocus-dependent spatial filtering property of this imager is described. The available spatial frequency bandwidth for a given misfocus condition is quantified. A special imaging condition that yields an increased dynamic range is identified.
Electronic cigarettes as a harm reduction strategy for tobacco control: A step forward or a repeat of past mistakes?

The issue of harm reduction has long been controversial in the public health practice of tobacco control. Health advocates have been reluctant to endorse a harm reduction approach out of fear that tobacco companies cannot be trusted to produce and market products that will reduce the risks associated with tobacco use. Recently, companies independent of the tobacco industry introduced electronic cigarettes, devices that deliver vaporized nicotine without combusting tobacco. We review the existing evidence on the safety and efficacy of electronic cigarettes. We then revisit the tobacco harm reduction debate, with a focus on these novel products. We conclude that electronic cigarettes show tremendous promise in the fight against tobacco-related morbidity and mortality. By dramatically expanding the potential for harm reduction strategies to achieve substantial health gains, they may fundamentally alter the tobacco harm reduction debate.
Intestinal intraepithelial lymphocyte derived angiotensin converting enzyme modulates epithelial cell apoptosis.

Background & Aims: Intestinal adaptation in short bowel syndrome (SBS) consists of increased epithelial cell (EC) proliferation as well as apoptosis. Previous microarray analyses of intraepithelial lymphocytes (IEL) gene expression after SBS showed an increased expression of angiotensin converting enzyme (ACE). Because ACE has been shown to promote alveolar EC apoptosis, we examined if IEL-derived ACE plays a role in intestinal EC apoptosis. Methods: Mice underwent either a 70% mid-intestinal resection (SBS group) or a transection (Sham group) and were studied at 7 days. ACE expression was measured, and ACE inhibition (ACE-I, enalaprilat) was used to assess ACE function. Results: IEL-derived ACE was significantly elevated in SBS mice. The addition of an ACE-I to SBS mice resulted in a significant decline in EC apoptosis. To address a possible mechanism, tumor necrosis factor alpha (TNF-α) mRNA expression was measured. TNF-α was significantly increased in SBS mice, and decreased with ACE-I. Interestingly, ACE-I was not able to decrease EC apoptosis in TNF-α knockout mice. Conclusions: This study shows a previously undescribed expression of ACE by IEL. SBS was associated with an increase in IEL-derived ACE. ACE appears to be associated with an up-regulation of intestinal EC apoptosis. ACE-I significantly decreased EC apoptosis.
Employment Chances in the Academic Job Market in Sociology: Do Race and Gender Matter?

Do employment chances for academics differ based on the gender or race/ethnicity of the job seeker? We use data from a sample of positions in sociology filled during the 1991–92 school year to determine whether European-American women, minority women, and minority men are advantaged, disadvantaged, or similarly placed in relation to European-American men. We find no evidence suggesting that European-American men are significantly disadvantaged, or disadvantaged in systematic or serious ways, vis-a-vis these groups. Among our most interesting findings is the discovery that minority men and women tend to be hired in positions newly created by the university while European-American women are significantly more likely to be hired in positions created when someone has been denied tenure. We conclude that disadvantages are beginning to level off, but they still exist for European-American women, minority men, and most especially minority women.
Ribosomal Protein L11 Recruits miR-24/miRISC To Repress c-Myc Expression in Response to Ribosomal Stress

c-Myc promotes cell growth by enhancing ribosomal biogenesis and translation. Deregulated expression of c-Myc and aberrant ribosomal biogenesis and translation contribute to tumorigenesis. Thus, a fine coordination between c-Myc and ribosomal biogenesis is vital for normal cell homeostasis. Here, we show that ribosomal protein L11 regulates c-myc mRNA turnover. L11 binds to c-myc mRNA at its 3' untranslated region (3'-UTR), the core component of microRNA-induced silencing complex (miRISC) argonaute 2 (Ago2), as well as miR-24, leading to c-myc mRNA reduction. Knockdown of L11 drastically increases the levels and stability of c-myc mRNA. Ablation of Ago2 abrogated the L11-mediated reduction of c-myc mRNA, whereas knockdown of L11 rescued miR-24-mediated c-myc mRNA decay. Interestingly, treatment of cells with the ribosomal stress-inducing agent actinomycin D or 5-fluorouracil significantly decreased the c-myc mRNA levels in an L11- and Ago2-dependent manner. Both treatments enhanced the association of L11 with Ago2, miR-24, and c-myc mRNA. We further show that ribosome-free L11 binds to c-myc mRNA in the cytoplasm and that this binding is enhanced by actinomycin D treatment. Together, our results identify a novel regulatory paradigm wherein L11 plays a critical role in controlling c-myc mRNA turnover via recruiting miRISC in response to ribosomal stress.
Using unnatural amino acids to probe the energetics of oxyanion hole hydrogen bonds in the ketosteroid isomerase active site.

Hydrogen bonds are ubiquitous in enzyme active sites, providing binding interactions and stabilizing charge rearrangements on substrate groups over the course of a reaction. But understanding the origin and magnitude of their catalytic contributions relative to hydrogen bonds made in aqueous solution remains difficult, in part because of complexities encountered in energetic interpretation of traditional site-directed mutagenesis experiments. It has been proposed for ketosteroid isomerase and other enzymes that active site hydrogen bonding groups provide energetic stabilization via “short, strong” or “low-barrier” hydrogen bonds that are formed due to matching of their pKa or proton affinity to that of the transition state. It has also been proposed that the ketosteroid isomerase and other enzyme active sites provide electrostatic environments that result in larger energetic responses (i.e., greater “sensitivity”) to ground-state to transition-state charge rearrangement, relative to aqueous solution, ther...
C K-emission Band Spectra of Carbons and Related Substances

C K-emission spectra were measured by an electron probe microanalyzer in which a lead stearate pseudocrystal was used as an analyzing element for the 2nd order spectrum of the C K band. Strong polarized emission spectra were obtained from single crystal surfaces of graphite when excited by electron beams perpendicular and parallel to the basal plane. A single crystal of diamond did not give any polarized spectra, which indicated no strong orientation of electronic orbitals in diamond. It was found that the spectrum of carbon black could be synthesized graphically by averaging the spectra of single crystals of graphite at perpendicular and parallel orientations. Thus, carbons with a graphitic arrangement however slight can be expected to give only one type of spectrum. The spectrum of carbon precursor was quite different from those of any other allotropes of carbon.
Learned helplessness in Drosophila melanogaster

Drosophila (n = 11) exposed to inescapable mechanical shaking in a black-white Y-maze escape task had reliably longer escape latencies 12 hr. later in a black-white shuttlebox escape task than grou...
Species-Recognition Program: A Computer-Assisted Approach to Recognizing Species.

Species recognition is a crucial component for many types of biological studies. To that end, broadly trained students must be able to accurately identify many different types of organisms. Courses that focus on learning the names of different species traditionally rely on preserved specimens viewed during class or laboratory time. Unfortunately, reliance on preserved specimens comes with many challenges in providing students with an optimal learning experience. The curriculum activity described here uses a modified PowerPoint file (species-recognition program—SRP) as a means of helping students learn to recognize and identify fishes based on subtle visual cues. Our results indicate that students were better able to identify fish species when using the SRP as a learning approach than when using preserved specimens. We suggest that the SRP approach to species recognition is an effective, viable alternative or supplement to preserved specimens that can be easily implemented in any course that emphasizes species identification. Information and materials are provided to enable instructors to create their own species-recognition programs. Journal of Microbiology & Biology Education
Evaluation of hemolysis following replacement of atrioventricular valves with porcine xenograft (Hancock) valves

Twenty-two patients who had undergone valve replacement with the porcine xenograft were studied 6 to 62 months postoperatively (mean 30.5 months) for evidence of intravascular hemolysis. Hemolysis was not detected in any patient and postoperative red cell indices and iron studies were normal for the majority of patients. Five patients had significantly elevated serum lactic dehydrogenase (LDH) values preoperatively which returned to normal following operation. Our evidence suggests that the glutaraldehyde-fixed porcine xenograft valve does not cause detectable hemolysis.
A Potential Epigenetic Bookmarking Function for the Hematopoietic Transcription Factor GATA-1.

Abstract 2601 Hematopoietic lineage choice decisions are stably maintained through many cell divisions. For example, erythroid precursor cells undergo several rounds of cell division during their maturation. During each mitosis, most transcription factors separate from chromatin causing transcription to cease globally. Mitosis therefore poses a challenge for transcription factors to re-associate with the appropriate target sites in chromatin of newborn cells. The epigenetic mechanisms that cement lineage stability and resist cell reprogramming during mitosis are poorly understood, although recent evidence supports the idea that “bookmarking” factors that remain associated with mitotic chromatin may play a role in this process. We therefore investigated whether the hematopoietic transcription factor GATA-1 might be retained at specific sites during mitosis. GATA-1 controls the expression of essentially all erythroid-specific genes and might therefore play a role in maintaining erythroid gene expression programs throughout the cell cycle. Surprisingly, we found that while a substantial fraction of GATA-1 dissociates from chromatin in mitosis, foci of high GATA-1 density are present within mitotic chromatin. To determine the exact locations of GATA-1 binding during mitosis, we developed a method to highly purify mitotic erythroid cells in sufficient quantities for chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq). These experiments revealed that a subset of sites bound by GATA-1 during interphase is occupied continuously throughout mitosis. Importantly, continuously GATA-1-occupied sites are enriched at promoters and cis-regulatory elements of genes coding for key developmental regulators of hematopoiesis (e.g., Fog1/Zfpm1, Gata2, Lyl1) but are notably absent at erythroid physiological and structural genes (e.g., Hba, Hbb, Epb4.9). To examine the importance of mitotic chromatin binding by GATA-1, we engineered a version of GATA-1 bearing a mitosis-specific degron that targets GATA-1 for degradation during mitosis but not interphase. Preliminary results show that mitotically degraded GATA-1 fails to induce differentiation when expressed in GATA-1-null erythroblasts. This suggests an important mitotic function for GATA-1. Current work focuses on delineating the mechanism by which continuous chromatin occupancy of GATA-1 throughout mitosis ensures proper erythroid differentiation. The results will be presented and discussed at the meeting. Disclosures: No relevant conflicts of interest to declare.
Stressful Life Events Around the Time of Unplanned Pregnancy and Women's Health: Exploratory Findings from a National Sample.

Objective Little is known about how women’s social context of unintended pregnancy, particularly adverse social circumstances, relates to their general health and wellbeing. We explored associations between stressful life events around the time of unintended pregnancy and physical and mental health. Methods Data are drawn from a national probability study of 1078 U.S. women aged 18–55. Our internet-based survey measured 14 different stressful life events occurring at the time of unintended pregnancy (operationalized as an additive index score), chronic disease and mental health conditions, and current health and wellbeing symptoms (standardized perceived health, depression, stress, and discrimination scales). Multivariable regression modeled relationships between stressful life events and health conditions/symptoms while controlling for sociodemographic and reproductive covariates. Results Among ever-pregnant women (N = 695), stressful life events were associated with all adverse health outcomes/symptoms in unadjusted analyses. In multivariable models, higher stressful life event scores were positively associated with chronic disease (aOR 1.21, CI 1.03–1.41) and mental health (aOR 1.42, CI 1.23–1.64) conditions, higher depression (B 0.37, CI 0.19–0.55), stress (B 0.32, CI 0.22–0.42), and discrimination (B 0.74, CI 0.45–1.04) scores, and negatively associated with ≥ very good perceived health (aOR 0.84, CI 0.73–0.97). Stressful life event effects were strongest for emotional and partner-related sub-scores. Conclusion Women with adverse social circumstances surrounding their unintended pregnancy experienced poorer health. Findings suggest that reproductive health should be considered in the broader context of women’s health and wellbeing and have implications for integrated models of care that address women’s family planning needs, mental and physical health, and social environments.
Classification of Traumatic Brain Injury Severity: A Neuropsychological Approach

Classification of traumatic brain injury (TBI) severity is of great interest because it may assist in guiding treatment as well as predicting course of recovery and outcome. However, classification of TBI severity has presented a number of unique challenges owing largely to the heterogeneity in neuropathology that can result from the injury and associated heterogeneity in clinical, cognitive, and behavioral disturbances. Clinicians and researchers have proposed classification systems based on lesion location and causative processes, physical mechanisms that cause TBI, distinctions between primary vs. secondary injuries, and clinical signs such as coma duration or post-traumatic amnesia, among others. Neuropsychological approaches to classifying brain injury severity have also been proposed, some that are based on a general index of impairment derived across multiple neuropsychological test scores. Cluster analysis of neuropsychology test scores has been accomplished and identified subgroups of individuals with TBI who are to some extent distinguished by severity of neuropsychological impairment. This chapter reviews issues relevant to TBI severity classification and cluster analysis of neuropsychological test scores and then goes on to present results of a study of children with TBI wherein the Trail Making Test (TMT) is subjected to cluster analysis in order to derive brain injury severity groups. These groups are compared on a number of relevant outcome variables, and the TMT classifications are compared to injury severity classifications based on the Glasgow Coma Scale (GCS). Results indicate that three TMT clusters best fit the data, with clusters corresponding to mild, moderate, and severe impairment. Differences between the TMT clusters were present on a number of relevant outcome variables. There was little correspondence between CGS and TMT severity classifications. These results are discussed in the context of current classification methods, limitations of the current findings are discussed, and directions for future research are suggested.