Electronic Raman Scattering in Twistronic Few-Layer Graphene.

We study electronic contribution to the Raman scattering signals of two-, three- and four-layer graphene with layers at one of the interfaces twisted by a small angle with respect to each other. We find that the Raman spectra of these systems feature two peaks produced by van Hove singularities in moiré minibands of twistronic graphene, one related to direct hybridization of the Dirac states, and the other resulting from band folding caused by moiré superlattice. The positions of both peaks strongly depend on the twist angle, so that their detection can be used for noninvasive characterization of the twist, even in hBN-encapsulated structures.

Determination of interatomic coupling between two-dimensional crystals using angle-resolved photoemission spectroscopy.

Lack of directional bonding between two-dimensional crystals like graphene or monolayer transition metal dichalcogenides provides unusual freedom in the selection of components for vertical van der Waals heterostructures. However, even for identical layers, their stacking, in particular the relative angle between their crystallographic directions, modifies properties of the structure. We demonstrate that the interatomic coupling between two two-dimensional crystals can be determined from angle-resolved photoemission spectra of a trilayer structure with one aligned and one twisted interface. Each of the interfaces provides complementary information and together they enable self-consistent determination of the coupling. We parametrise interatomic coupling for carbon atoms by studying twisted trilayer graphene and show that the result can be applied to structures with different twists and number of layers. Our approach demonstrates how to extract fundamental information about interlayer coupling in a stack of two-dimensional crystals and can be applied to many other van der Waals interfaces.

Right on track? Performance of satellite telemetry in terrestrial wildlife research.

Satellite telemetry is an increasingly utilized technology in wildlife research, and current devices can track individual animal movements at unprecedented spatial and temporal resolutions. However, as we enter the golden age of satellite telemetry, we need an in-depth understanding of the main technological, species-specific and environmental factors that determine the success and failure of satellite tracking devices across species and habitats. Here, we assess the relative influence of such factors on the ability of satellite telemetry units to provide the expected amount and quality of data by analyzing data from over 3,000 devices deployed on 62 terrestrial species in 167 projects worldwide. We evaluate the success rate in obtaining GPS fixes as well as in transferring these fixes to the user and we evaluate failure rates. Average fix success and data transfer rates were high and were generally better predicted by species and unit characteristics, while environmental characteristics influenced the variability of performance. However, 48% of the unit deployments ended prematurely, half of them due to technical failure. Nonetheless, this study shows that the performance of satellite telemetry applications has shown improvements over time, and based on our findings, we provide further recommendations for both users and manufacturers.

Myeloid translocation genes differentially regulate colorectal cancer programs.

Myeloid translocation genes (MTGs), originally identified as chromosomal translocations in acute myelogenous leukemia, are transcriptional corepressors that regulate hematopoietic stem cell programs. Analysis of The Cancer Genome Atlas (TCGA) database revealed that MTGs were mutated in epithelial malignancy and suggested that loss of function might promote tumorigenesis. Genetic deletion of MTGR1 and MTG16 in the mouse has revealed unexpected and unique roles within the intestinal epithelium. Mtgr1-/- mice have progressive depletion of all intestinal secretory cells, and Mtg16-/- mice have a decrease in goblet cells. Furthermore, both Mtgr1-/- and Mtg16-/- mice have increased intestinal epithelial cell proliferation. We thus hypothesized that loss of MTGR1 or MTG16 would modify Apc1638/+-dependent intestinal tumorigenesis. Mtgr1-/- mice, but not Mtg16-/- mice, had a 10-fold increase in tumor multiplicity. This was associated with more advanced dysplasia, including progression to invasive adenocarcinoma, and augmented intratumoral proliferation. Analysis of chromatin immunoprecipitation sequencing data sets for MTGR1 and MTG16 targets indicated that MTGR1 can regulate Wnt and Notch signaling. In support of this, immunohistochemistry and gene expression analysis revealed that both Wnt and Notch signaling pathways were hyperactive in Mtgr1-/- tumors. Furthermore, in human colorectal cancer (CRC) samples MTGR1 was downregulated at both the transcript and protein level. Overall our data indicates that MTGR1 has a context-dependent effect on intestinal tumorigenesis.

Receptor Tyrosine Kinase Expression Profiles in Canine Cutaneous and Subcutaneous Mast Cell Tumors.

The receptor tyrosine kinase (RTK) KIT is a major focus of current research into canine mast cell tumors (MCTs). Little is known about the role of other RTKs, such as vascular endothelial growth factor receptors (VEGFRs) and platelet-derived growth factor receptors (PDGFRs). These RTKs are dysregulated in many human and animal cancers and are key regulators of tumor angiogenesis. The aims of this study were to assess the expression and activation (phosphorylation) status of KIT, VEGFR2, and PDGFR (α and ß) in canine MCTs and to examine associations with various clinical outcomes. c-KITmutational status and KIT cellular localization pattern were also evaluated for these tumors. Twenty-seven MCTs, consisting of 5 subcutaneous and 22 cutaneous tumors, from 25 dogs were evaluated. MCT biopsies, cultured mast cells, and skin from the surgical margin were analyzed through Western blotting. MCT biopsies were also used for KIT immunohistochemical labeling and polymerase chain reaction for c-KITmutational analysis. MCT had heterogeneous expression profiles for all 3 RTKs, which varied in intensity and activation status. Statistical analyses showed phosphorylated KIT, VEGFR2, and KIT cellular localization to be predictive of decreased survival time, disease-free interval, and increased metastatic rate. Expression of VEGFR2 and KIT diffuse cytoplasmic labeling were also significantly associated with increased rate of local recurrence. The results of the study show that phosphorylated KIT, KIT, VEGFR2, and PDGFRß, in addition to KIT localization, may be valuable prognostic determinants in MCTs and should be further studied to improve diagnostic and therapeutic modalities.

Dynamics of critical source areas: does connectivity explain chemistry?

Critical source area approaches to catchment management are increasingly being recognised as effective tools to mitigate sediment and nutrient transfers. These approaches often assume hydrological connectivity as a driver for environmental risk, however this assumption has rarely been tested. Using high resolution monitoring, 14 rainfall events of contrasting intensity were examined in detail for spatial and temporal dynamics of overland flow generation at a hydrologically isolated grassland hillslope in Co. Down, Northern Ireland. Interactions between overland flow connectivity and nutrient transfers were studied to test the critical source area hypothesis. While total and soluble phosphorus loads were found to be representative of the size of the overland flow contributing area (P=<0.05), the dynamics of concentrations throughout storm hydrographs were found to be complex and storm dependant. Near linear relationships were observed between the contributing area and total overland flow volumes (R(2)=0.86). Export coefficients (kg ha(-1)) calculated using plot size were found to under estimate annual losses of total phosphorus by a factor of 17, when compared to those calculated using the contributing area. This study shows that current critical source area definitions for implementing mitigation measures may be overlooking the importance of storm characteristics in determining nutrient transfers and hence may be insufficient in determining catchment scale risk.

Canine subcutaneous mast cell tumors: cellular proliferation and KIT expression as prognostic indices.

Molecular assays are widely used to prognosticate canine cutaneous mast cell tumors (MCT). There is limited information about these prognostic assays used on MCT that arise in the subcutis. The aims of this study were to evaluate the utility of KIT immunohistochemical labeling pattern, c-KIT mutational status (presence of internal tandem duplications in exon 11), and proliferation markers--including mitotic index, Ki67, and argyrophilic nucleolar organizing regions (AgNOR)--as independent prognostic markers for local recurrence and/or metastasis in canine subcutaneous MCT. A case-control design was used to analyze 60 subcutaneous MCT from 60 dogs, consisting of 24 dogs with subsequent local recurrence and 12 dogs with metastasis, as compared to dogs matched by breed, age, and sex with subcutaneous MCT that did not experience these events. Mitotic index, Ki67, the combination of Ki67 and AgNOR, and KIT cellular localization pattern were significantly associated with local recurrence and metastasis, thereby demonstrating their prognostic value for subcutaneous MCT. No internal tandem duplication mutations were detected in exon 11 of c-KIT in any tumors. Because c-KIT mutations have been demonstrated in only 20 to 30% of cutaneous MCT and primarily in tumors of higher grade, the number of subcutaneous MCT analyzed in this study may be insufficient to draw conclusions on the role c-KIT mutations in these tumors.

Canine subcutaneous mast cell tumor: characterization and prognostic indices.

Histologic grading schemes for canine cutaneous mast cell tumors (MCTs) were not developed for subcutaneous MCTs. Despite this, subcutaneous MCTs are currently categorized by many as grade II or higher. The aim of this investigation was to assess the pathology and clinical outcome for subcutaneous MCTs to provide a more accurate prognosis. Information on clinical outcome for 306 dogs was obtained from veterinarians and correlated with histologic features. Mean and median follow-up was 842 and 891 days, respectively (range, 3-2,305 days). Only 27 (9%) were confirmed as mast cell-related deaths. Metastasis occurred in 13 (4%), and 24 (8%) had local reoccurrence, even though 171 (56%) cases had incomplete surgical margins. Median survival time was not reached, and the estimated 6-month, 1-, 2-, and 5-year survival probabilities were 95%, 93%, 92%, and 86%, respectively. Dogs were euthanized or died as a result of local tumor reoccurrence, additional MCT development distant to the surgical site, or metastasis. Decreased survival time was linked to mitotic index (number of mitotic figures per 10 high-power fields), infiltrative growth pattern, and presence of multinucleation. Both univariable and multivariable analysis showed mitotic index to be strongly predictive of survival, local reoccurrence, and metastasis. The results of the study indicate that the majority of subcutaneous MCTs have a favorable prognosis, with extended survival times and low rates of reoccurrence and metastasis.

Examining costs of induced and constitutive immune investment in Tenebrio molitor.

Central to the conceptual basis of ecological immunity is the notion that immune effector systems are costly to produce, run, and/or maintain. Using the mealworm beetle, Tenebrio molitor, as a model we investigated two aspects of the costs of innate immunity. We conducted an experiment designed to identify the cost of an induced immune response, and the cost of constitutive investment in immunity, as well as potential interactions. The immune traits under consideration were the encapsulation response and prophylactic cuticular melanization, which are mechanistically linked by the melanin-producing phenoloxidase cascade. If immunity is costly, we predicted reduced longevity and/or fecundity as a consequence of investment in either immune trait. We found a measurable longevity cost associated with producing an inducible immune response (encapsulation). In contrast to other studies, this cost was expressed under ad libitum feeding conditions. We found no measurable costs for constitutive investment in immunity (prophylactic investment in cuticular colour).

The LionHeart LVD-2000: a completely implanted left ventricular assist device for chronic circulatory support.

Management of patients with end-stage cardiac disease remains a vexing problem. Limitations in medical management and a fixed supply of donor organs for cardiac transplant have a continued impact on this growing population of patients. Mechanical circulatory support has proved very successful as a means of bridging patients to cardiac transplant when all medical options have been exhausted. The development of a chronic system of circulatory support has been underway at the Pennsylvania State University for nearly 30 years. These efforts have been recently merged with the industrial partnership with Arrow International toward the development of the LionHeart LVD-2000 (Arrow International, Reading, PA) completely implanted left ventricular support system. We present an overview of the system, details of implantation, a review of preclinical studies, and a synopsis of the first European implants. Early results have demonstrated the system to be safe, effective, and reliable. Transcutaneous energy transmission and the compliance chamber have been validated.

Viral induction, transmission and apoptosis among cells infected by a Human Intracisternal A-type retrovirus.

Sjogren's Syndrome, a systemic autoimmune disease, is characterized by lymphocytic infiltration of the salivary or lacrimal glands, producing xerostomia or xerophthalmia. Although definitive proof of viral etiology has not been established, a cell line containing viral particles termed Human Intracisternal A-type Particles (HIAP) resulted from co-culture with patient lip biopsies. We stimulated these chronically infected cells with phorbol myristate acetate (PMA) in an effort to enhance production of viral particles for further characterization. We report that the virus present in the HIAP cell line can be induced to become lytic when subjected to PMA and that there is a difference in the effects of PMA on H9 and HIAP cell groups, with apparent protection from apoptosis due to PMA being exerted by viral presence. Delayed apoptosis may prolong exposure of the foreign/self complex, thus enhancing an autoimmune response. Polyacrylamide gel electrophoresis (PAGE) revealed the presence of new peptides in pellets of supernatants of PMA-stimulated HIAP cells, with prominent bands at 55 and 43 kDa, and several fainter ones. HIAP infection was transferred by cell-free filtered supernatants from stimulated cells to H9 cells, which became identical to parent HIAP cells by PAGE and fluorescence activated cell sorter.

Reactivity of sera from systemic lupus erythematosus and Sjögren's syndrome patients with peptides derived from human immunodeficiency virus p24 capsid antigen.

We have previously demonstrated that about one-third of patients with either Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE) react to human immunodeficiency virus (HIV) p24 core protein antigen without any evidence of exposure to, or infection with, HIV itself. Herein, we further characterize the specificity of this reaction using enzyme-linked immunosorbent assay to peptides representing fragments of p24. Characteristic epitope-specific profiles were seen for SS and SLE patients. SS patients had significantly increased responses to peptides F (p24 amino acids 69 to 86) and H (amino acids 101 to 111) and diminished reactivity to peptides A (amino acids 1 to 16) and P (amino acids 214 to 228). SLE patients had increased reactivity to peptides E (amino acids 61 to 76), H, and P. Utilization of peptide P hyporeactivity as the criterion to select for SS patients results in a screen that is moderately sensitive (64%) and specific (79.3%). Adding hyperreactivity to one other peptide (F or H) as an additional criterion yields an expected decrease in sensitivity (to 41%) while increasing specificity (to 93.1%). All sera-reactive peptides from regions of known structure of HIV p24 were located in the apex of the p24 molecule. Thus, the specificity of the peptide reactivities described here indicates a specific pattern of a nonrandom cross-reactivity between HIV type 1 p24 and autoimmune sera which may be partially syndrome specific. The future focus of our work will be to optimize assays of the peptide as diagnostic tools.

Identification of cryptic peanut agglutinin-reactive sites in human lipoprotein(a).

After treatment of human lipoprotein(a) (Lp(a)) with neuraminidase, formerly cryptic sites became available for binding to peanut agglutinin (PNA) lectin and a Thomsen-Friedenreich antigen (T-antigen)-specific monoclonal antibody. The PNA-reactive sites were localized to the apo(a) moiety of Lp(a) and O-specific carbohydrate side chains. Lp(a) with larger isoforms of apo(a) contained more potential PNA reactivity per molecule of Lp(a) apoB than did smaller isoforms. Very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) did not contain comparable amounts of the cryptic PNA-reactive sites.

Delayed hypersensitivity skin tests and subsequent renal transplant outcome.

BACKGROUND: Some studies in the literature have supported, while others have denied, the relationship between results of delayed hypersensitivity skin tests (DHST), renal allograft and patient survival rates. Several factors contribute to the unreliability of these studies. For example, most of these studies were performed in the precyclosporine era, furthermore, other variables which influence renal allografts and patient survival rates were not controlled in those studies. OBJECTIVE: The purpose of this study was to investigate the relationship between results of DHST performed in the pretransplant period with the subsequent renal transplant outcome in the cyclosporine era. METHODS: The study included 103 first cadaveric renal transplant recipients. DHST were performed during pretransplant evaluation by intradermal injections of a battery of recall antigens. Based on skin-test results, the patients were assigned to two groups--those with a positive skin test (STP+) and those with a negative (anergic) skin test. These two groups were compared with each other regarding allograft survival, patient survival, and other variables known to influence survival rates. RESULTS: The mean age, sex and racial distribution, degree of HLA matches between recipients and donors, number of acute rejection episodes, and number of patients with acute tubular necrosis were similar between the two groups. Renal allograft survival rates in the anergic group at 6 months, 1 year, 2 years, and 3 years were 97%, 90%, 84%, and 57%, respectively. The survival rate for renal allografts in the STP+ group for the same time points was 90%, 86%, 80%, and 72%, respectively. Patient survival rates for the anergic group at 6 months, 1 year, 2 years, and 3 years were 95%, 94%, 89%, and 85%, respectively, while those for the STP+ group were 98%, 98%, 98%, and 97% respectively. Differences between the STP+ and anergic groups, with regard to patient and allograft survival rates, were not significant. CONCLUSION: We conclude that DHST is not helpful in predicting outcome of patient or renal allograft survival rates over a 3-year time period.

Identifying and comparing competencies for social work management: a practice driven approach.

The study explicates a competency-based model of contemporary social work management practice and compares this model with frameworks derived from earlier studies. Using a purposive sample of 184 social work managers throughout the country, an exploratory factor analysis yielded twelve sets of competencies required of today's social work manager. A comparison of the present model to earlier management frameworks reveals that substantive changes in the nature, scope, complexity, and priorities assigned to management competencies and skills have transformed the role of the social work manager over the last decade. Implications for social work manager education are reviewed and future research directions are proposed.

Determination of ultratrace levels of lead in infant formula by isotope dilution inductively coupled plasma mass spectrometry.

A simple method was developed for the accurate and precise determination of low- and sub-ppb (ng/g) concentrations of lead in infant formula by isotope dilution inductively coupled plasma mass spectrometry using ultrasonic nebulization. After addition of a known amount of 207Pb, samples were microwave digested and the ratio 207Pb/208Pb was measured in the digests. Agreement with certified values for lead in milk powder standard reference materials was good, and isotope dilution analysis using 206Pb yielded identical results for the standard reference materials. Lead concentrations determined for several infant nutritional products were verified by an independent method. Typically, relative standard deviations of < 4% were obtained with this method for lead concentrations above 2 ppb. The recovery of 2 ng of lead from an aqueous standard carried through the microwave digestion was 104 +/- 4%. Infant formula (containing 0.6 ppb lead) to which 0.4 ng of natural-abundance lead had been added, to simulate a formula containing 0.9 ppb lead, was analyzed by isotope dilution, and the result was 96 +/- 18% of the theoretical value. Thus, differences of 0.3 ppb lead could be clearly distinguished, and the detection limit was estimated to be 0.1 ng lead per gram of infant formula. The keys to accuracy for this method are minimizing contamination and accurately determining the concentration of lead in the isotopically enriched standard.

Analysis of apolipoprotein size distribution by electroimmunoblotting from non-denaturing composite gels.

An exponential gradient gel with 0-35% acrylamide and 0.5% agarose was developed for electrophoresis of intact lipoproteins with subsequent electroimmunoblotting. The system resolved in a single gel lipoprotein-associated proteins of sizes from 'free' apoproteins to VLDL. Reproducibility between gels was good (coefficient of variation < 8%). Examination of the effect of mild glutaraldehyde fixation on immunodetection showed variable results (lack of effect on apos (a), AII, and AIV; inhibition of apoB; enhancement of apos AI and E). The composite gel system described here will simplify analysis of apolipoprotein distributions in both health and disease and therefore will likely be useful in future clinical applications.

Optimization and characterization of capture ELISA methodology for Lp(a) lipoprotein quantification.

In order to better characterize and optimize a typical capture ELISA system for Lp(a) lipoprotein, we have analysed kinetic details of the reaction. Plate coating with polyclonal antibody, recognition of captured analyte with monoclonal antibody, and detection of monoclonal antibody with alkaline phosphatase-labeled antiglobulin were essentially complete after one hour, probably being driven forward by a relative excess of reagent. However, complete capture of the Lp(a) analyte required about 6 h at low input concentrations. Shorter time periods for capture might therefore result in decreased sensitivity and reproducibility. Deviations from linearity in the assay dose response were associated with incomplete capture of Lp(a) and significant depletion of the monoclonal recognition antibody. With the final reaction conditions described, no significant differences in immunochemical reactivity between samples were found by analysis of dose response slopes. Finally, interferences from plasminogen, -20 degrees C storage, anticoagulants, LDL, haemolysis, and bilirubin were minimal.

Characterization of "modified-self"-induced specific antibody hyporesponsiveness to herpes simplex virus.

Pretreatment of mice iv with syngeneic spleen cells modified with soluble HSV envelope antigens induced an anti-HSV antibody hyporesponsiveness following challenge with infectious virus. The epitope density on the HSV-modified spleen cells was quantitated using a photon-counting spectrofluorimeter so that observed immunological results could be correlated with the HSV antigen dose on the splenocytes. The degree of anti-HSV antibody hyporesponsiveness was found to be related to the epitope density on the HSV-modified spleen cells, but not the number of modified cells used in the pretreatment over the 16-fold range tested. Anti-HSV antibody hyporesponsiveness was induced if 7, but not 3, days had elapsed between pretreatment and challenge. This antibody hyporesponsiveness could be adoptively transferred with T cells. Only mice that had induced an anti-HSV antibody hyporesponsiveness following pretreatment with HSV-modified splenocytes were able to survive an LD50 challenge with infectious virus.

Human lipoprotein(a) quantified by 'capture' ELISA.

Plasma lipoprotein(a), Lp(a), is the most important known genetically controlled independent risk factor for the prediction of early atherosclerosis (AS) and coronary artery disease (CAD) in a significant subpopulation of Caucasians. A sensitive, specific 'capture' enzyme linked immunosorbent assay (ELISA) is reported for the assay of human plasma Lp(a). There is no interference from low density lipoprotein (LDL), plasminogen, or from endogenous lipids, hemoglobin, or bilirubin. An immobilized polyclonal rabbit antibody 'captures' the Lp(a) ligand, and then a monoclonal murine antibody 'recognizes' it. Alkaline phosphatase conjugated rabbit antimouse IgG and para-nitrophenyl phosphate substrate 'detect' and 'indicate' colorimetrically the amount of Lp(a) bound. Quantitation is relative to a commercially available secondary clinical standard. The frequency distribution for a predominantly Caucasian reference population is highly skewed toward the higher concentrations. The median plasma Lp(a) concentration for healthy Caucasians is 80 mg per 1. Relative risk for early myocardial infarction (MI) increases as plasma Lp(a) levels increase above 300 mg per 1. Approximately 20 percent of Caucasians have plasma Lp(a) values above 300 mg per 1. The frequency distributions of plasma Lp(a) in Blacks and Caucasian type II diabetics are different from the healthy Caucasian reference population. The percentiles of Lp(a) values greater than 300 mg per 1 in these latter groups is three times higher. Thorough epidemiologic and clinical studies where groups are segregated by race and ethnic origin are needed for accurate clinical interpretation of plasma Lp(a) results. Only neomycin and niacin are shown to lower plasma Lp(a) levels therapeutically, although anabolic steroid medication causes lower plasma Lp(a) concentrations. Endocrine malfunction also may influence plasma Lp(a) levels.