Decision making during nuclear power plant incidents: a new approach to the evaluation of precursor events

Renewed interest in precursor analysis has shown that the evaluation of near misses is an interdisciplinary effort, fundamental within the life of an organization for reducing operational risks and enabling accident prevention. The practice of precursor analysis has been a part of nuclear power plant regulation in the United States for over 25 years. During this time, the models used in the analysis have evolved from simple risk equations to quite complex probabilistic risk assessments. But, one item that has remained constant over this time is that the focus of the analysis has been on modeling the scenario using the risk model (regardless of the model sophistication) and then using the results of the model to determine the severity of the precursor incident. We believe that evaluating precursors in this fashion could be a shortcoming since decision making during the incident is not formally investigated. Consequently, we present the idea for an evaluation procedure that enables one to integrate current practice with the evaluation of decisions made during the precursor event. The methodology borrows from technologies both in the risk analysis and the decision analysis realms. We demonstrate this new methodology via an evaluation of a U.S. precursor incident. Specifically, the course of the incident is represented by the integration of a probabilistic risk assessment model (i.e., the risk analysis tool) with an influence diagram and the corresponding decision tree (i.e., the decision analysis tools). The results and insights from the application of this new methodology are discussed.

Recent advances in equine abdominal surgery

Laparoscopy is a minimally invasive procedure that has applications as a diagnostic, therapeutic and prognostic technique. Specialized equipment is necessary to perform equine laparoscopy, and there is a large range of instruments, both disposable and non-disposable available. Laparoscopic procedures described include ovariectomy, cryptorchidectomy, adhesiolysis and herniorrhaphy. Laparoscopy can be performed in a standing or dorsally recumbent position, depending on surgeon preference, patient status and the procedure to be performed. Stapling equipment is frequently used in gastrointestinal surgery in horses. Advantages include decreased surgical time and a decrease in the risk of contamination. Stapling equipment is often used in creating anastomoses, both in the large and small intestines, as well as in vessel ligation. New surgical techniques intended to decrease adhesion formation include the use of carboxymethylcellulose and bioresorbable patches. Indwelling abdominal drains can be used for peritoneal lavage following surgery and also appear to decrease the risk of adhesion formation. Improvements in post-operative care, including the treatment of post-operative ileus and endotoxaemia can significantly improve the outcome of horses that have undergone surgery for abdominal disorders. Recommendations for the use of prokinetic agents in horses with ileus vary widely. Prokinetic agents include local anaesthetics, macrolide antimicrobials, cholinergic agonists and dopamine antagonists. Endotoxaemia is common in horses following surgery for gastrointestinal disorders. The antibiotic polymyxin B binds to the circulating endotoxin molecule, decreasing its half-life in the intra-vascular space and reducing associated inflammation. This drug appears to be an effective and affordable treatment option for horses with endotoxaemia. The use of specific cyclooxygenase inhibitors in veterinary medicine have been studied recently. Selective cyclooxygenase-2 inhibitors may provide comparable anti-inflammatory and analgesic properties to the non-selective non-steroidal anti-inflammatory drugs. These drugs appear to have similar clinical effectiveness and will hopefully minimize deleterious side effects. The optimal healing of ventral midline incisions in horses is related to many factors including appropriate suture patterns and bite size, in addition to appropriate post-operative exercise recommendations. Recent advances in surgical techniques and post-operative care should decrease the morbidity and mortality associated with abdominal surgery. This article provides an overview of some of these advances.

The Mouse Genome Database (MGD): from genes to mice--a community resource for mouse biology

The Mouse Genome Database (MGD) forms the core of the Mouse Genome Informatics (MGI) system (http://www.informatics.jax.org), a model organism database resource for the laboratory mouse. MGD provides essential integration of experimental knowledge for the mouse system with information annotated from both literature and online sources. MGD curates and presents consensus and experimental data representations of genotype (sequence) through phenotype information, including highly detailed reports about genes and gene products. Primary foci of integration are through representations of relationships among genes, sequences and phenotypes. MGD collaborates with other bioinformatics groups to curate a definitive set of information about the laboratory mouse and to build and implement the data and semantic standards that are essential for comparative genome analysis. Recent improvements in MGD discussed here include the enhancement of phenotype resources, the re-development of the International Mouse Strain Resource, IMSR, the update of mammalian orthology datasets and the electronic publication of classic books in mouse genetics.

Positron emission tomography scanning in the assessment of patients with lymphoma

BACKGROUND

The detection of lymphoma by computed tomography (CT) scanning is known to be improved by positron emission tomography (PET) and/or gallium scanning, although the direct comparative accuracy of these imaging modalities remains a subject of ongoing review.

AIMS

The aim of the present study was to compare PET scanning with conventional imaging (CT and/or gallium scanning) in patients with lymphoma.

METHODS

A retrospective study of 38 patients (25 men; 13 women; median age 39.5 years; range 18.0-81.0 years) who had had PET scans (24 scans at initial staging and 46 scans at restaging, including suspected disease relapse) was carried out. Thirty-one concurrent gallium scans had been performed. Disease was validated with clinical follow up or biopsy.

RESULTS

The sensitivities of PET and CT at initial staging were 96 and 71%, respectively. PET identified additional sites of disease compared with CT in 29% of patients. Of the 15 patients who had had all three imaging modalities, the sensitivities of PET, CT and gallium were 93, 67 and 87%, respectively. At treatment completion, the positive predictive values of PET, CT and gallium scans for relapse given a residual mass were 100, 33 and 0%, respectively (P = 0.006 for PET and CT comparison). The negative predictive values of PET, CT and gallium were 76, 0 and 70%, respectively (P-value not significant). In suspected disease relapse, PET results changed management in 50% of patients.

CONCLUSION

Compared with CT and gallium scans, PET has superior accuracy in staging and restaging, and its greatest value lies in its positive predictive value for relapse in patients with residual masses.

Estrogen receptor-alpha interaction with the CREB binding protein coactivator is regulated by the cellular environment

The p160 coactivators, steroid receptor coactivator-1 (SRC-1), transcriptional intermediary factor-2 (TIF2) and receptor-associated coactivator-3 (RAC3), as well as the coactivator/integrator CBP, mediate estrogen receptor-alpha (ERalpha)-dependent gene expression. Although these coactivators are widely expressed, ERalpha transcriptional activity is cell-type dependent. In this study, we investigated ERalpha interaction with p160 coactivators and CBP in HeLa and HepG2 cell lines. Basal and estradiol (E2)-dependent interactions between the ERalpha ligand-binding domain (LBD) and SRC-1, TIF2 or RAC3 were observed in HeLa and HepG2 cells. The extents of hormone-dependent interactions were similar and interactions between each of the p160 coactivators and the ERalpha LBD were not enhanced by 4-hydroxytamoxifen in either cell type. In contrast to the situation for p160 coactivators, E2-dependent interaction of the ERalpha LBD with CBP or p300 was detected in HeLa but not HepG2 cells by mammalian two-hybrid and coimmunoprecipitation assays, indicating that the cellular environment modulates ERalpha-CBP/p300 interaction. Furthermore, interactions between CBP and p160 coactivators are much more robust in HeLa than HepG2 cells suggesting that poor CBP-p160 interactions are insufficient to support ERalpha-CBP-p160 ternary complexes important for nuclear receptor-CBP interactions. Alterations in p160 coactivators or CBP expression between these two cell types did not account for differences in ERalpha-p160-CBP interactions. Taken together, these data revealed the influence of cellular environment on ERalpha-CBP/p300 interactions, as well as CBP-p160 coactivator binding, and suggest that these differences may contribute to the cell specificity of ERalpha-dependent gene expression.

The Mouse Genome Database (MGD): integrating biology with the genome

The Mouse Genome Database (MGD) is one component of the Mouse Genome Informatics (MGI) system (http://www.informatics.jax.org), a community database resource for the laboratory mouse. MGD strives to provide a comprehensive knowledgebase about the mouse with experiments and data annotated from both literature and online sources. MGD curates and presents consensus and experimental data representations of genetic, genotype (sequence) and phenotype information including highly detailed reports about genes and gene products. Primary foci of integration are through representations of relationships between genes, sequences and phenotypes. MGD collaborates with other bioinformatics groups to curate a definitive set of information about the laboratory mouse and to build and implement the data and semantic standards that are essential for comparative genome analysis. Recent developments in MGD discussed here include an extensive integration of the mouse sequence data and substantial revisions in the presentation, query and visualization of sequence data.

Vector-averaged gravity-induced changes in cell signaling and vitamin D receptor activity in MG-63 cells are reversed by a 1,25-(OH)2D3 analog, EB1089

Skeletal unloading in an animal hindlimb suspension model and microgravity experienced by astronauts or as a result of prolonged bed rest causes site-specific losses in bone mineral density of 1%-2% per month. This is accompanied by reductions in circulating levels of 1,25-(OH)(2)D(3), the active metabolite of vitamin D. 1,25-(OH)(2)D(3), the ligand for the vitamin D receptor (VDR), is important for calcium absorption and plays a role in differentiation of osteoblasts and osteoclasts. To examine the responses of cells to activators of the VDR in a simulated microgravity environment, we used slow-turning lateral vessels (STLVs) in a rotating cell culture system. We found that, similar to cells grown in microgravity, MG-63 cells grown in the STLVs produce less osteocalcin, alkaline phosphatase, and collagen Ialpha1 mRNA and are less responsive to 1,25-(OH)(2)D(3). In addition, expression of VDR was reduced. Moreover, growth in the STLV caused activation of the stress-activated protein kinase pathway (SAPK), a kinase that inhibits VDR activity. In contrast, the 1,25-(OH)(2)D(3) analog, EB1089, was able to compensate for some of the STLV-associated responses by reducing SAPK activity, elevating VDR levels, and increasing expression of osteocalcin and alkaline phosphatase. These studies suggest that, not only does simulated microgravity reduce differentiation of MG-63 cells, but the activity of the VDR, an important regulator of bone metabolism, is reduced. Use of potent, less calcemic analogs of 1,25-(OH)(2)D(3) may aid in overcoming this defect.

Structure of the type III secretion and substrate-binding domain of Yersinia YopH phosphatase

Pathogenic strains of Yersinia deploy a type III secretion system to inject the potent tyrosine phosphatase YopH into host cells, where it dephosphorylates focal adhesion-associated substrates. The amino-terminal, non-catalytic domain of YopH is bifunctional; it is essential for the secretion and binding of the specific chaperone SycH, but also targets the catalytic domain to substrates in the infected cell. We describe the 2.2 A resolution crystal structure of residues 1-129 of YopH from Yersinia pseudotuberculosis. The amino-terminal alpha-helix (2-17), comprising the secretion signal, and beta-strand (24-28) of one molecule exchange with another molecule to form a domain-swapped dimer. Nuclear magnetic resonance (NMR) and gel filtration experiments demonstrated that YopH(1-129) could exist as a monomer and/or a dimer in solution. The topology of the dimer and the dynamics of a monomeric form in solution observed by NMR imply that YopH has the propensity to unfold partially. The dimer is probably not important physiologically, but may mimic how SycH binds to the exposed non-polar surfaces of a partially unfolded YopH. Phosphopeptide-induced perturbations in NMR chemical shifts define a substrate-binding surface on YopH(1-129) that includes residues previously shown by mutagenesis to be essential for YopH function.

Intracellular signaling pathways: nongenomic actions of estrogens and ligand-independent activation of estrogen receptors

Recognition of the complexity of estrogen and estrogen receptor (ER) signaling has substantially increased in the last several years. In their genomic role, estrogens enter the cell and bind to ERs which are members of a superfamily of ligand-regulated transcription factors. However, estrogens also exert non-genomic effects that occur independently of gene transcription. Typically, these relatively rapid events are initiated at the plasma membrane, and result in the activation of intracellular signaling pathways. Regulation of ER transcriptional activity is also complex. Not only do ligands regulate ER-dependent gene expression, but this receptor in the apparent absence of its estrogenic ligand can also be transcriptionally activated by a variety of intracellular signaling pathways. Recent evidence also extends the effects of these signaling pathways to regulating the activity of coactivators, proteins which bind to the ER and amplify its transcriptional activity. Taken together, it is clear that estrogens, ERs and intracellular signaling pathways are intimately linked and this review will explore the relationship between these components of the estrogen-ER signal transduction process.

The role of dynamin-related protein 1, a mediator of mitochondrial fission, in apoptosis

In healthy cells, fusion and fission events participate in regulating mitochondrial morphology. Disintegration of the mitochondrial reticulum into multiple punctiform organelles during apoptosis led us to examine the role of Drp1, a dynamin-related protein that mediates outer mitochondrial membrane fission. Upon induction of apoptosis, Drp1 translocates from the cytosol to mitochondria, where it preferentially localizes to potential sites of organelle division. Inhibition of Drp1 by overexpression of a dominant-negative mutant counteracts the conversion to a punctiform mitochondrial phenotype, prevents the loss of the mitochondrial membrane potential and the release of cytochrome c, and reveals a reproducible swelling of the organelles. Remarkably, inhibition of Drp1 blocks cell death, implicating mitochondrial fission as an important step in apoptosis.

A-ring reduced metabolites of 19-nor synthetic progestins as subtype selective agonists for ER alpha

It has previously been demonstrated that 19-nor contraceptive progestins undergo in vivo and in vitro enzyme-mediated A-ring double bond hydrogenation. Bioconversion of 19-nor progestins to their corresponding tetrahydro derivatives results in the loss of progestational activity and acquisition of estrogenic activities and binding to the ER. Herein, we report subtype-selective differences in ligand binding and transcriptional potency of nonphenolic synthetic 19-nor derivatives between ER alpha and ER beta. In this study, we have examined both ER- and PR-mediated transcriptional activity of a number of A-ring chemically reduced derivatives of norethisterone and Gestodene. Double bond hydrogenation decreased the transcriptional potency of norethisterone and Gestodene through both PR isoforms with a 100- to 1,000-fold difference, respectively. In terms of the effects of norethisterone and Gestodene and their corresponding 5 alpha-dihydro (5 alpha-norethisterone and 5 alpha-Gestodene), or 3 alpha,5 alpha-tetrahydro or 3 beta,5 alpha-tetrahydro derivatives (3 alpha,5 alpha-norethisterone/3 alpha,5 alpha-Gestodene and 3 beta,5 alpha-norethisterone/3beta,5 alpha-Gestodene, respectively) on estrogen-mediated transcriptional regulation, the 3 beta,5 alpha-tetrahydro derivatives of both norethisterone and Gestodene showed the highest induction when HeLa cells were transiently transfected with an expression vector for ER alpha. This activity could be inhibited with tamoxifen. These compounds did not activate gene transcription via ER beta, and none of them showed antagonistic activities through either ER subtype. The 3 beta,5 alpha-tetrahydro derivatives of both norethisterone and Gestodene were active in other cells in addition to HeLa cells and activated reporter expression through the oxytocin promoter. In summary, two ER alpha selective agonists have been identified. These compounds, with ER alpha vs. ER beta selective agonist activity, may be useful in evaluating the distinct role of these receptors as well as in providing useful insights into ER action.

Steroid hormone receptor-mediated histone deacetylation and transcription at the mouse mammary tumor virus promoter

Acetylation of lysines in histones H3 and H4 N-terminal tails is associated with transcriptional activation and deacetylation with repression. Our studies with the mouse mammary tumor virus (MMTV) promoter in chromatin show significant levels of acetylation at promoter proximal and distal regions prior to transactivation. Upon activation with glucocorticoids or progestins, promoter proximal histones become deacetylated within the region of inducible nuclease hypersensitivity. The deacetylation lags behind the initiation of transcription, indicating a role in post-activation regulation. Our results indicate a novel mechanism by which target promoters are regulated by steroid receptors and chromatin modification machinery.

Estradiol-induced IP(3) mediates the estrogen receptor activity expressed in human cells

The recent findings that estradiol-induced IP(3)/PKC-alpha signalling pathway triggers DNA synthesis in HepG2 cells, containing estrogen receptor unable to stimulate gene transactivation, raises the hypothesis that this pathway represents an alternative signalling present when the amount of estrogen receptor (ER) is insufficient to mediate genomic effects. beta-estradiol-stimulated DNA synthesis and target gene expression have been studied in HepG2 and, ER-alpha or ER-beta negative, HeLa cells. We also examined whether either receptor is required for rapid effects of estrogen on DNA synthesis. Finally, the consequences of increased ER expression on estrogen-induced DNA synthesis and synthetic target gene expression have been evaluated. Our data indicate that the E2-induced IP(3) production is dependent on expression of either ER-alpha or ER-beta in both HepG2 and HeLa cells. Moreover, inhibition of the IP(3) second messenger pathway blocks E2-induced cellular actions suggesting that this second messenger is responsible for estrogen's rapid, non-genomic effects on both DNA synthesis and gene expression.

Ligand-mediated assembly and real-time cellular dynamics of estrogen receptor alpha-coactivator complexes in living cells

Studies with live cells demonstrate that agonist and antagonist rapidly (within minutes) modulate the subnuclear dynamics of estrogen receptor alpha (ER) and steroid receptor coactivator 1 (SRC-1). A functional cyan fluorescent protein (CFP)-tagged lac repressor-ER chimera (CFP-LacER) was used in live cells to discretely immobilize ER on stably integrated lac operator arrays to study recruitment of yellow fluorescent protein (YFP)-steroid receptor coactivators (YFP-SRC-1 and YFP-CREB binding protein [CBP]). In the absence of ligand, YFP-SRC-1 is found dispersed throughout the nucleoplasm, with a surprisingly high accumulation on the CFP-LacER arrays. Agonist addition results in the rapid (within minutes) recruitment of nucleoplasmic YFP-SRC-1, while antagonist additions diminish YFP-SRC-1-CFP-LacER associations. Less ligand-independent colocalization is observed with CFP-LacER and YFP-CBP, but agonist-induced recruitment occurs within minutes. The agonist-induced recruitment of coactivators requires helix 12 and critical residues in the ER-SRC-1 interaction surface, but not the F, AF-1, or DNA binding domains. Fluorescence recovery after photobleaching indicates that YFP-SRC-1, YFP-CBP, and CFP-LacER complexes undergo rapid (within seconds) molecular exchange even in the presence of an agonist. Taken together, these data suggest a dynamic view of receptor-coregulator interactions that is now amenable to real-time study in living cells.

Src, Fyn, and Yes are not required for neuromuscular synapse formation but are necessary for stabilization of agrin-induced clusters of acetylcholine receptors

Mice deficient in src and fyn or src and yes move and breathe poorly and die perinatally, consistent with defects in neuromuscular function. Src and Fyn are associated with acetylcholine receptors (AChRs) in muscle cells, and Src and Yes can act downstream of ErbB2, suggesting roles for Src family kinases in signaling pathways regulating neuromuscular synapse formation. We studied neuromuscular synapses in src(-/-); fyn(-/-) and src(-/-); yes(-/-) mutant mice and found that muscle development, motor axon pathfinding, clustering of postsynaptic proteins, and synapse-specific transcription are normal in these double mutants, showing that these pairs of kinases are not required for early steps in synapse formation. We generated muscle cell lines lacking src and fyn and found that neural agrin and laminin-1 induced normal clustering of AChRs and that agrin induced normal tyrosine phosphorylation of the AChR beta subunit in the absence of Src and Fyn. Another Src family member, most likely Yes, was associated with AChRs and phosphorylated by agrin in myotubes lacking Src and Fyn, indicating that Yes may compensate for the loss of Src and Fyn. Nevertheless, PP1 and PP2, inhibitors of Src-class kinases, did not inhibit agrin signaling, suggesting that Src class kinase activity is dispensable for agrin-induced clustering and tyrosine phosphorylation of AChRs. AChR clusters, however, were less stable in myotubes lacking Src and Fyn but not in PP1- or PP2-treated wild-type cells. These data show that the stabilization of agrin-induced AChR clusters requires Src and Fyn and suggest that the adaptor activities, rather than the kinase activities, of these kinases are essential for this stabilization.

Sleep disturbance in orofacial pain patients: pain-related or emotional distress?

Associations between pain, depression, and sleep disturbance have been documented in several chronic pain patient samples. The current study assessed the prevalence and magnitude of sleep disturbance in a sample of 128 orofacial pain patients referred for clinical evaluation and tested linkages between sleep, depression, anxiety, and pain using cross-sectional and longitudinal data. Seventy-seven percent of the patients reported reduced sleep quantity since pain onset. In cross-sectional analyses, reduced sleep quantity was associated with depression and pain. Reduced sleep quality was associated with negative affect. Longitudinally, initial depression and pain predicted sleep at time two and initial pain predicted negative affect. Sleep did not predict pain. Results support the hypothesis that pain, rather than sleep disturbance, increases negative affect across time, whereas negative affect is more a cause of concurrent reduced sleep quality than is pain. The results highlight the importance of assessing for sleep disturbance in orofacial pain patients.

Synthesis and study of the fluorescein conjugate of the nucleotide dPTP

The synthesis of a fluorescein conjugate on the non-natural base P is described. The ability of the newly synthesised fluorescein--dPTP and of a fluorescein-11-dUTP to compete with the natural nucleotide TTP was also studied. Overall the efficiency of labelling a nucleic acid with a fluorescein moiety was found to be approximately equal.

An evaluation of the physicochemical risk for renal stone disease during pregnancy

Seventeen subjects were studied during the third trimester of pregnancy (PG) and post partum (NPG) to evaluate the effect of pregnancy on the physicochemical risk of renal stone disease. Levels of urinary saturation for calcium oxalate (CaOx), brushite (Br), uric acid (UA), and monosodium urate (NaU) were determined as well as urinary excretions of stone-forming elements. In addition to urinary calcium excretion, assessment of calcium metabolism included serum calcium and parathyroid hormone. Urinary calcium excretion was 251 +/- 127 mg/day during pregnancy and 121 +/- 67 mg/day post partum (p < 0.001). This was associated with a higher intake of dietary calcium and altered renal handling of calcium with an increase in the filtered load and a decrease in renal tubular reabsorption. The increase in urinary calcium resulted in a higher level of saturation of the urine for calcium oxalate (NPG 2.1 +/- 1.0 vs PG 3.0 +/- 1.1, p < 0.02) and brushite (NPG 1.2 +/- 0.9 vs PG 1.9 +/- 1.1, p < 0.05) compatible with an increased risk of stone formation.

Hyperphosphatemia in a burn patient

Hypophosphatemia has been observed in severely burned patients and has been associated with increased mortality. Hyperphosphatemia has rarely been described in this population. We present a burn patient with hyperphosphatemia, hypercalciuria, and suppressed parathyroid hormone level 5 months after the initial burn. The patient's presentation is most consistent with the effect of immobilization on bone and calcium metabolism.