Processing of Refractory Metal Alloys for JOYO Irradiations

This is a summary of the refractory metal processing experienced by candidate Prometheus materiats as they were fabricated into specimens destined for testing within the JOYO test reactor, ex-reactor testing at Oak Ridge National Laboratory (ORNL), or testing within the NRPCT. The processing is described for each alloy from the point of inception to the point where processing was terminated due to the cancellation of Naval Reactor's involvement in the Prometheus Project. The alloys included three tantalum-base alloys (T-111, Ta-10W, and ASTAR-811C), a niobium-base alloy, (FS-85), and two molybdenum-rhenium alloys, one containing 44.5 w/o rhenium, and the other 47.5 w/o rhenium. Each of these alloys was either a primary candidate or back-up candidate for cladding and structural applications within the space reactor. Their production was intended to serve as a forerunner for large scale production ingots that were to be procured from commercial refractory metal vendors such as Wah Chang

Axial distribution of myosin binding protein-C is unaffected by mutations in human cardiac and skeletal muscle

Myosin binding protein-C (MyBP-C), a major thick filament associated sarcomeric protein, plays an important functional and structural role in regulating sarcomere assembly and crossbridge formation. Missing or aberrant MyBP-C proteins (both cardiac and skeletal) have been shown to cause both cardiac and skeletal myopathies, thereby emphasising its importance for the normal functioning of the sarcomere. Mutations in cardiac MyBP-C are a major cause of hypertrophic cardiomyopathy (HCM), while mutations in skeletal MyBP-C have been implicated in a disease of skeletal muscle—distal arthrogryposis type 1 (DA-1). Here we report the first detailed electron microscopy studies on human cardiac and skeletal tissues carrying MyBP-C gene mutations, using samples obtained from HCM and DA-1 patients. We have used established image averaging methods to identify and study the axial distribution of MyBP-C on the thick filament by averaging profile plots of the A-band of the sarcomere from electron micrographs of human cardiac and skeletal myopathy specimens. Due to the difficulty of obtaining normal human tissue, we compared the distribution to the A-band structure in normal frog skeletal, rat cardiac muscle and in cardiac muscle of MyBP-C-deficient mice. Very similar overall profile averages were obtained from the C-zones in cardiac HCM samples and skeletal DA-1 samples with MyBP-C gene mutations, suggesting that mutations in MyBP-C do not alter its mean axial distribution along the thick filament

Interferon regulatory factor 8-deficiency determines massive neutrophil recruitment but T cell defect in fast growing granulomas during tuberculosis

Following Mycobacterium tuberculosis (Mtb) infection, immune cell recruitment in lungs is pivotal in establishing protective immunity through granuloma formation and neogenesis of lymphoid structures (LS). Interferon regulatory factor-8 (IRF-8) plays an important role in host defense against Mtb, although the mechanisms driving anti-mycobacterial immunity remain unclear. In this study, IRF-8 deficient mice (IRF-8−/−) were aerogenously infected with a low-dose Mtb Erdman virulent strain and the course of infection was compared with that induced in wild-type (WT-B6) counterparts. Tuberculosis (TB) progression was examined in both groups using pathological, microbiological and immunological parameters. Following Mtb exposure, the bacterial load in lungs and spleens progressed comparably in the two groups for two weeks, after which IRF-8−/− mice developed a fatal acute TB whereas in WT-B6 the disease reached a chronic stage. In lungs of IRF-8−/−, uncontrolled growth of pulmonary granulomas and impaired development of LS were observed, associated with unbalanced homeostatic chemokines, progressive loss of infiltrating T lymphocytes and massive prevalence of neutrophils at late infection stages. Our data define IRF-8 as an essential factor for the maintenance of proper immune cell recruitment in granulomas and LS required to restrain Mtb infection. Moreover, IRF-8−/− mice, relying on a common human and mouse genetic mutation linked to susceptibility/severity of mycobacterial diseases, represent a valuable model of acute TB for comparative studies with chronically-infected congenic WT-B6 for dissecting protective and pathological immune reactions

Combinatorial Guidance by CCR7 Ligands for T Lymphocytes Migration in Co-Existing Chemokine Fields

Chemokines mediate the trafficking and positioning of lymphocytes in lymphoid tissues that is crucial for immune surveillance and immune responses. In particular, a CCR7 ligand, CCL21, plays important roles in recruiting T cells to secondary lymphoid tissues (SLT). Furthermore, CCL21 together with another CCR7 ligand, CCL19, direct the navigation and compartmentation of T cells within SLT. However, the distinct roles of these two chemokines for regulating cell trafficking and positioning are not clear. In this study, we explore the effect of co-existing CCL19 and CCL21 concentration fields on guiding T cell migration. Using microfluidic devices that can configure single and superimposed chemokine fields we show that under physiological gradient conditions, human peripheral blood T cells chemotax to CCL21 but not CCL19. Furthermore, T cells migrate away from the CCL19 gradient in a uniform background of CCL21. This repulsive migratory response is predicted by mathematical modeling based on the competition of CCL19 and CCL21 for CCR7 signaling and the differential ability of the two chemokines for desensitizing CCR7. These results suggest a new combinatorial guiding mechanism by CCL19 and CCL21 for the migration and trafficking of CCR7 expressing leukocytes

The effect of tidal forcing on biogeochemical processes in intertidal salt marsh sediments

<p>Abstract</p> <p>Background</p> <p>Early diagenetic processes involved in natural organic matter (NOM) oxidation in marine sediments have been for the most part characterized after collecting sediment cores and extracting porewaters. These techniques have proven useful for deep-sea sediments where biogeochemical processes are limited to aerobic respiration, denitrification, and manganese reduction and span over several centimeters. In coastal marine sediments, however, the concentration of NOM is so high that the spatial resolution needed to characterize these processes cannot be achieved with conventional sampling techniques. In addition, coastal sediments are influenced by tidal forcing that likely affects the processes involved in carbon oxidation.</p> <p>Results</p> <p>In this study, we used in situ voltammetry to determine the role of tidal forcing on early diagenetic processes in intertidal salt marsh sediments. We compare ex situ measurements collected seasonally, in situ profiling measurements, and in situ time series collected at several depths in the sediment during tidal cycles at two distinct stations, a small perennial creek and a mud flat. Our results indicate that the tides coupled to the salt marsh topography drastically influence the distribution of redox geochemical species and may be responsible for local differences noted year-round in the same sediments. Monitoring wells deployed to observe the effects of the tides on the vertical component of porewater transport reveal that creek sediments, because of their confinements, are exposed to much higher hydrostatic pressure gradients than mud flats.</p> <p>Conclusion</p> <p>Our study indicates that iron reduction can be sustained in intertidal creek sediments by a combination of physical forcing and chemical oxidation, while intertidal mud flat sediments are mainly subject to sulfate reduction. These processes likely allow microbial iron reduction to be an important terminal electron accepting process in intertidal coastal sediments.</p

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

Low CCR7-Mediated Migration of Human Monocyte Derived Dendritic Cells in Response to Human Respiratory Syncytial Virus and Human Metapneumovirus

Human respiratory syncytial virus (HRSV) and, to a lesser extent, human metapneumovirus (HMPV) and human parainfluenza virus type 3 (HPIV3), can re-infect symptomatically throughout life without significant antigenic change, suggestive of incomplete or short-lived immunity. In contrast, re-infection by influenza A virus (IAV) largely depends on antigenic change, suggestive of more complete immunity. Antigen presentation by dendritic cells (DC) is critical in initiating the adaptive immune response. Antigen uptake by DC induces maturational changes that include decreased expression of the chemokine receptors CCR1, CCR2, and CCR5 that maintain DC residence in peripheral tissues, and increased expression of CCR7 that mediates the migration of antigen-bearing DC to lymphatic tissue. We stimulated human monocyte-derived DC (MDDC) with virus and found that, in contrast to HPIV3 and IAV, HMPV and HRSV did not efficiently decrease CCR1, 2, and 5 expression, and did not efficiently increase CCR7 expression. Consistent with the differences in CCR7 mRNA and protein expression, MDDC stimulated with HRSV or HMPV migrated less efficiently to the CCR7 ligand CCL19 than did IAV-stimulated MDDC. Using GFP-expressing recombinant virus, we showed that the subpopulation of MDDC that was robustly infected with HRSV was particularly inefficient in chemokine receptor modulation. HMPV- or HRSV-stimulated MDDC responded to secondary stimulation with bacterial lipopolysaccharide or with a cocktail of proinflammatory cytokines by increasing CCR7 and decreasing CCR1, 2 and 5 expression, and by more efficient migration to CCL19, suggesting that HMPV and HRSV suboptimally stimulate rather than irreversibly inhibit MDDC migration. This also suggests that the low concentration of proinflammatory cytokines released from HRSV- and HMPV-stimulated MDDC is partly responsible for the low CCR7-mediated migration. We propose that inefficient migration of HRSV- and HMPV-stimulated DC to lymphatic tissue contributes to reduced adaptive responses to these viruses

Hepatitis C Virus Induced a Novel Apoptosis-Like Death of Pancreatic Beta Cells through a Caspase 3-Dependent Pathway

Epidemiological and experimental studies have suggested that Hepatitis C virus (HCV) infection is associated with the development of type 2 diabetes. Pancreatic beta cell failure is central to the progression of type 2 diabetes. Using virus infection system, we investigate the influence of HCV infection on the fate of the insulinoma cell line, MIN6. Our experiments demonstrate that the HCV virion itself is indispensable and has a dose- and time-dependent cytopathic effect on the cells. HCV infection inhibits cell proliferation and induces death of MIN6 cells with apoptotic characteristics, including cell surface exposure of phosphatidylserine, decreased mitochondrial membrane potential, activation of caspase 3 and poly (ADP-ribose) polymerase, and DNA fragmentation in the nucleus. However, the fact that HCV-infected cells exhibit a dilated, low-density nucleus with intact plasma and nuclear membrane indicates that a novel apoptosis-like death occurs. HCV infection also causes endoplasmic reticulum (ER) stress. Further, HCV RNA replication was detected in MIN6 cells, although the infection efficiency is very low and no progeny virus particle generates. Taken together, our data suggest that HCV infection induces death of pancreatic beta cells through an ER stress-involved, caspase 3-dependent, special pathway

The IL-1-Like Cytokine IL-33 Is Constitutively Expressed in the Nucleus of Endothelial Cells and Epithelial Cells In Vivo: A Novel ‘Alarmin’?

BACKGROUND: Interleukin-33 (IL-33) is an IL-1-like cytokine ligand for the IL-1 receptor-related protein ST2, that activates mast cells and Th2 lymphocytes, and induces production of Th2-associated cytokines in vivo. We initially discovered IL-33 as a nuclear factor (NF-HEV) abundantly expressed in high endothelial venules from lymphoid organs, that associates with chromatin and exhibits transcriptional regulatory properties. This suggested that, similarly to IL-1alpha and chromatin-associated cytokine HMGB1, IL-33 may act as both a cytokine and a nuclear factor. Although the activity of recombinant IL-33 has been well characterized, little is known yet about the expression pattern of endogenous IL-33 in vivo. METHODOLOGY/PRINCIPAL FINDINGS: Here, we show that IL-33 is constitutively and abundantly expressed in normal human tissues. Using a combination of human tissue microarrays and IL-33 monoclonal and polyclonal antibodies, we found that IL-33 is a novel nuclear marker of the endothelium widely expressed along the vascular tree. We observed abundant nuclear expression of IL-33 in endothelial cells from both large and small blood vessels in most normal human tissues, as well as in human tumors. In addition to endothelium, we also found constitutive nuclear expression of IL-33 in fibroblastic reticular cells of lymphoid tissues, and epithelial cells of tissues exposed to the environment, including skin keratinocytes and epithelial cells of the stomach, tonsillar crypts and salivary glands. CONCLUSIONS/SIGNIFICANCE: Together, our results indicate that, unlike inducible cytokines, IL-33 is constitutively expressed in normal human tissues. In addition, they reveal that endothelial cells and epithelial cells constitute major sources of IL-33 in vivo. Based on these findings, we speculate that IL-33 may function, similarly to the prototype 'alarmin' HMGB1, as an endogenous 'danger' signal to alert the immune system after endothelial or epithelial cell damage during trauma or infection

Seasonal variations in pore water and sediment geochemistry of littoral lake sediments (Asylum Lake, MI, USA)

BACKGROUND: Seasonal changes in pore water and sediment redox geochemistry have been observed in many near-surface sediments. Such changes have the potential to strongly influence trace metal distribution and thus create seasonal fluctuations in metal mobility and bioavailability. RESULTS: Seasonal trends in pore water and sediment geochemistry are assessed in the upper 50 cm of littoral kettle lake sediments. Pore waters are always redox stratified, with the least compressed redox stratification observed during fall and the most compressed redox stratification observed during summer. A 2-step sequential sediment extraction yields much more Fe in the first step, targeted at amorphous Fe(III) (hydr)oxides (AEF), then in the second step, which targets Fe(II) monosulfides. Fe extracted in the second step is relatively invariant with depth or season. In contrast, AEF decreases with sediment depth, and is seasonally variable, in agreement with changes in redox stratification inferred from pore water profiles. A 5-step Tessier extraction scheme was used to assess metal association with operationally-defined exchangeable, carbonate, iron and manganese oxide (FMO), organic/sulfide and microwave-digestible residual fractions in cores collected during winter and spring. Distribution of metals in these two seasons is similar. Co, As, Cd, and U concentrations approach detection limits. Fe, Cu and Pb are mostly associated with the organics/sulfides fraction. Cr and Zn are mostly associated with FMO. Mn is primarily associated with carbonates, and Co is nearly equally distributed between the FMO and organics/sulfide fractions. CONCLUSION: This study clearly demonstrates that near-surface lake sediment pore water redox stratification and associated solid phase geochemistry vary significantly with season. This has important ramifications for seasonal changes in the bioavailability and mobility of trace elements. Without rate measurements, it is not possible to quantify the contribution of various processes to natural organic matter degradation. However, the pore water and solid phase data suggest that iron reduction and sulfate reduction are the dominant pathways in the upper 50 cm of these sediments