Detection of Salmonella in Eggs and Egg Products With Fluorescent Antibody

Organisms of the genus Salmonella are detected in eggs and egg products within 24 hr in the presence of Pseudomonadaceae and other Enterobacteriaceae by combining selective cultural methods with fluorescent-antibody techniques. These techniques are specific for Salmonella when H antibodies are used. Absorption techniques are necessary before the O antibodies give specific reactions for Salmonella. No cross-reactions appear when H antiserum is used. Absorption and interference techniques indicate the test is specific for Salmonella.     

Pierced Lasso Bundles Are a New Class of Knot-like Motifs

A four-helix bundle is a well-characterized motif often used as a target for designed pharmaceutical therapeutics and nutritional supplements. Recently, we discovered a new structural complexity within this motif created by a disulphide bridge in the long-chain helical bundle cytokine leptin. When oxidized, leptin contains a disulphide bridge creating a covalent-loop through which part of the polypeptide chain is threaded (as seen in knotted proteins). We explored whether other proteins contain a similar intriguing knot-like structure as in leptin and discovered 11 structurally homologous proteins in the PDB. We call this new helical family class the Pierced Lasso Bundle (PLB) and the knot-like threaded structural motif a Pierced Lasso (PL). In the current study, we use structure-based simulation to investigate the threading/folding mechanisms for all the PLBs along with three unthreaded homologs as the covalent loop (or lasso) in leptin is important in folding dynamics and activity. We find that the presence of a small covalent loop leads to a mechanism where structural elements slipknot to thread through the covalent loop. Larger loops use a piercing mechanism where the free terminal plugs through the covalent loop. Remarkably, the position of the loop as well as its size influences the native state dynamics, which can impact receptor binding and biological activity. This previously unrecognized complexity of knot-like proteins within the helical bundle family comprises a completely new class within the knot family, and the hidden complexity we unraveled in the PLBs is expected to be found in other protein structures outside the four-helix bundles. The insights gained here provide critical new elements for future investigation of this emerging class of proteins, where function and the energetic landscape can be controlled by hidden topology, and should be take into account in ab initio predictions of newly identified protein targets.     

Anthropogenic nitrogen deposition in boreal forests has a minor impact on the global carbon cycle

It is proposed that increases in anthropogenic reactive nitrogen (N_r) deposition may cause temperate and boreal forests to sequester a globally significant quantity of carbon (C); however, long‐term data from boreal forests describing how C sequestration responds to realistic levels of chronic N_r deposition are scarce. Using a long‐term (14‐year) stand‐scale (0.1 ha) N addition experiment (three levels: 0, 12.5, and 50 kg N ha⁻¹ yr⁻¹) in the boreal zone of northern Sweden, we evaluated how chronic N additions altered N uptake and biomass of understory communities, and whether changes in understory communities explained N uptake and C sequestration by trees. We hypothesized that understory communities (i.e. mosses and shrubs) serve as important sinks for low‐level N additions, with the strength of these sinks weakening as chronic N addition rates increase, due to shifts in species composition. We further hypothesized that trees would exhibit nonlinear increases in N acquisition, and subsequent C sequestration as N addition rates increased, due to a weakening understory N sink. Our data showed that understory biomass was reduced by 50% in response to the high N addition treatment, mainly due to reduced moss biomass. A ¹⁵N labeling experiment showed that feather mosses acquired the largest fraction of applied label, with this fraction decreasing as the chronic N addition level increased. Contrary to our hypothesis, the proportion of label taken up by trees was equal (ca. 8%) across all three N addition treatments. The relationship between N addition and C sequestration in all vegetation pools combined was linear, and had a slope of 16 kg C kg⁻¹ N. While canopy retention of N_r deposition may cause C sequestration rates to be slightly different than this estimate, our data suggest that a minor quantity of annual anthropogenic CO₂ emissions are sequestered into boreal forests as a result of N_r deposition.     

Influence of habitat dynamics on the distribution and abundance of the federally threatened Santa Ana Sucker, <Emphasis Type="Italic">Catostomus santaanae</Emphasis>, in the Santa Ana River

Habitat degradation affects native stream fish populations worldwide. We examined the impact of fluctuation in environmental variables on the population dynamics of the federally threatened Santa Ana sucker, Catostomus santaanae, in the Santa Ana River, California through: 1) annual quantitative surveys of C. santaanae abundance and habitat at three 100-m sites between 2001 and 2008 and 2) annual surveys of habitat composition within a 30-km stretch of the Santa Ana River between 2006 and 2008. We used Akaike’s Information Criterion (AIC) to evaluate competing models that used environmental variables to explain variation in C. santaanae abundance among sites and years. The most plausible model identified a positive relationship between C. santaanae abundance and both the amount of coarse substrate (i.e., gravel and cobble) and rate of discharge among site-years. Surveys at the 30-km scale indicated that the prevalence of coarse substrate declined in a downstream direction in each year and that the total amount of this habitat type varied annually. Specifically, cobble/gravel habitat was mostly confined to the upstream 4 km, 9.6 km, and 5.1 km of the survey area in 2006, 2007, and 2008, respectively. Fine sediment comprised the bulk of downstream habitat every year. This large-scale flux in the distribution of coarse sediment likely has a large effect on the population dynamics of C. santaanae in the Santa Ana River. Our results underscore the need to maintain and enhance suitable C. santaanae habitat to ensure its long-term persistence in the Santa Ana River.     

Complex Polarization Response in Plasmonic Nanospirals

Archimedean nanospirals exhibit many far-field resonances that result from the lack of symmetry and strong intra-spiral plasmonic interactions. Here, we present a computational study, with corroborating experimental results, on the plasmonic response of the 4π Archimedean spiral as a function of incident polarization, for spirals in which the largest linear dimension is less than 550 nm. We discuss the modulation of the near-field structure for linearly and circularly polarized light in typical nanospiral configurations. Computational studies of the near-field distributions excited by circularly polarized light illustrate the effects of chirality on plasmonic mechanisms, while rotation of linearly polarized light provides a detailed view of the effects of broken symmetry on nanospiral fields in any given direction in the plane of the spiral. The rotational geometry exhibits a preference for circular polarization that increases near-field enhancement compared to excitation with linearly polarized light and exchanges near-field configurations and resonant modes. By analyzing the effects of polarization and wavelength on the near-field configurations, we also show how the nanospiral could be deployed in applications such as tunable near-field enhancement of nonlinear optical signals from chiral molecules.     

The Reversed Feto-Maternal Bile Acid Gradient in Intrahepatic Cholestasis of Pregnancy Is Corrected by Ursodeoxycholic Acid

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disorder associated with an increased risk of adverse fetal outcomes. It is characterised by raised maternal serum bile acids, which are believed to cause the adverse outcomes. ICP is commonly treated with ursodeoxycholic acid (UDCA). This study aimed to determine the fetal and maternal bile acid profiles in normal and ICP pregnancies, and to examine the effect of UDCA treatment. Matched maternal and umbilical cord serum samples were collected from untreated ICP (n = 18), UDCA-treated ICP (n = 46) and uncomplicated pregnancy (n = 15) cases at the time of delivery. Nineteen individual bile acids were measured using HPLC-MS/MS. Maternal and fetal serum bile acids are significantly raised in ICP compared with normal pregnancy (p = <0.0001 and <0.05, respectively), predominantly due to increased levels of conjugated cholic and chenodeoxycholic acid. There are no differences between the umbilical cord artery and cord vein levels of the major bile acid species. The feto-maternal gradient of bile acids is reversed in ICP. Treatment with UDCA significantly reduces serum bile acids in the maternal compartment (p = <0.0001), thereby reducing the feto-maternal transplacental gradient. UDCA-treatment does not cause a clinically important increase in lithocholic acid (LCA) concentrations. ICP is associated with significant quantitative and qualitative changes in the maternal and fetal bile acid pools. Treatment with UDCA reduces the level of bile acids in both compartments and reverses the qualitative changes. We have not found evidence to support the suggestion that UDCA treatment increases fetal LCA concentrations to deleterious levels.     

REG4 Independently Predicts Better Prognosis in Non-Mucinous Colorectal Cancer

Introduction

Colorectal cancer (CRC) is one of the world’s three most common cancers and its incidence is rising. To identify patients who benefit from adjuvant therapy requires novel biomarkers. The regenerating islet-derived gene (REG) 4 belongs to a group of small secretory proteins involved in cell proliferation and regeneration. Its up-regulated expression occurs in inflammatory bowel diseases also in gastrointestinal cancers. Reports on the association of REG4 expression with CRC prognosis have been mixed. Our aim was to investigate tumor REG4 expression in CRC patients and its coexpression with other intestinal markers.

Methods

Tumor expression of REG4 was evaluated by immunohistochemistry in 840 consecutive surgically treated CRC patients at Helsinki University Central Hospital. Expression of MUC1, MUC2, MUC5AC, synapthophysin, and chromogranin was evaluated in a subgroup of 220 consecutively operated CRC patients. REG4 expression with clinicopathological parameters, other intestinal markers, and the impact of REG4 expression on survival were assessed.

Results

REG4 expression associated with favorable clinicopathological parameters and with higher overall survival from non-mucinous CRC (p = 0.019). For such patients under 65, its expression was an independent marker of lower risk of death within 5 years that cancer; univariable hazard ratio (HR) = 0.57; 95% confidence interval (CI) (0.34–0.94); multivariable HR = 0.55; 95% CI (0.33–0.92). In non-mucinous CRC, REG4 associated with positive MUC2, MUC4, and MUC5AC expression.

Conclusion

We show, to our knowledge for the first time, that REG4 IHC expression to be an independent marker of favorable prognosis in non-mucinous CRC. Our results contradict those from studies based on quantification of REG4 mRNA levels, a discrepancy warranting further studies.     

A tumor-associated mutation of FYVE-CENT prevents its interaction with Beclin 1 and interferes with cytokinesis

The tumor suppressor activity of Beclin 1 (BECN1), a subunit of class III phosphatidylinositol 3-kinase complex, has been attributed to its regulation of apoptosis and autophagy. Here, we identify FYVE-CENT (ZFYVE26), a phosphatidylinositol 3-phosphate binding protein important for cytokinesis, as a novel interacting protein of Beclin 1. A mutation in FYVE-CENT (R1945Q) associated with breast cancer abolished the interaction between FYVE-CENT and Beclin 1, and reduced the localization of these proteins at the intercellular bridge during cytokinesis. Breast cancer cells containing the FYVE-CENT R1945Q mutation displayed a significant increase in cytokinetic profiles and bi-multinuclear phenotype. Both Beclin 1 and FYVE-CENT were found to be downregulated in advanced breast cancers. These findings suggest a positive feedback loop for recruitment of FYVE-CENT and Beclin 1 to the intercellular bridge during cytokinesis, and reveal a novel potential tumor suppressor mechanism for Beclin 1.     

Infliximab Induces Clonal Expansion of γδ-T Cells in Crohn's Disease: A Predictor of Lymphoma Risk?

Background

Concominant with the widespread use of combined immunotherapy in the management of Crohn''s disease (CD), the incidence of hepato-splenic gamma-delta (γδ)-T cell lymphoma has increased sharply in CD patients. Malignant transformation of lymphocytes is believed to be a multistep process resulting in the selection of malignant γδ-T cell clones. We hypothesised that repeated infusion of anti-TNF-α agents may induce clonal selection and that concurrent treatment with immunomodulators further predisposes patients to γδ-T cell expansion.

Methodology/Principal Findings

We investigated dynamic changes in the γδ-T cells of patient with CD following treatment with infliximab (Remicade®; n = 20) or adalimumab (Humira®; n = 26) using flow cytometry. In patients with a high γδ-T cell level, the γδ-T cells were assessed for clonality. Of these 46 CD patients, 35 had a γδ-T cells level (mean 1.6%) comparable to healthy individuals (mean 2.2%), and 11 CD patients (24%) exhibited an increased level of γδ-T cells (5–15%). In the 18 patients also receiving thiopurines or methotrexate, the average baseline γδ-T cell level was 4.4%. In three male CD patients with a high baseline value, the γδ-T cell population increased dramatically following infliximab therapy. A fourth male patient also on infliximab monotherapy presented with 20% γδ-T cells, which increased to 25% shortly after treatment and was 36% between infusions. Clonality studies revealed an oligoclonal γδ-T cell pattern with dominant γδ-T cell clones. In support of our clinical findings, in vitro experiments showed a dose-dependent proliferative effect of anti-TNF-α agents on γδ-T cells.

Conclusion/Significance

CD patients treated with immunomodulators had constitutively high levels of γδ-T cells. Infliximab exacerbated clonal γδ-T cell expansion in vivo and induced γδ-T cell proliferation in vitro. Overall, young, male CD patients with high baseline γδ-T cell levels may be at an increased risk of developing malignant γδ-T cell lymphomas following treatment with anti-TNF-α agents.