557 research outputs found
Endangered right whales enhance primary productivity in the bay of fundy
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Marine mammals have recently been documented as important facilitators of rapid and efficient nutrient recycling in coastal and offshore waters. Whales enhance phytoplankton nutrition by releasing fecal plumes near the surface after feeding and by migrating from highly productive, high-latitude feeding areas to low-latitude nutrient-poor calving areas. In this study, we measured NH4 + and PO4 3- release rates from the feces of North Atlantic right whales (Eubalaena glacialis), a highly endangered baleen whale. Samples for this species were primarily collected by locating aggregations of whales in surface- Active groups (SAGs), which typically consist of a central female surrounded by males competing for sexual activity. When freshly collected feces were incubated in seawater, high initial rates of N release were generally observed, which decreased to near zero within 24 hours of sampling, a pattern that is consistent with the active role of gut microflora on fecal particles. We estimate that at least 10% of particulate N in whale feces becomes available as NH4 + within 24 hours of defecation. Phosphorous was also abundant in fecal samples: Initial release rates of PO4 3- were higher than for NH4 +, yielding low N/P nutrient ratios over the course of our experiments. The rate of PO4 3- release was thus more than sufficient to preclude the possibility that nitrogenous nutrients supplied by whales would lead to phytoplankton production limited by P availability. Phytoplankton growth experiments indicated that NH4 + released from whale feces enhance productivity, as would be expected, with no evidence that fecal metabolites suppress growth. Although North Atlantic right whales are currently rare (approximately 450 individuals), they once numbered about 14,000 and likely played a substantial role in recycling nutrients in areas where they gathered to feed and mate. Even though the NH4 + released from fresh whale fecal material is a small fraction of total whale fecal nitrogen, and recognizing the fact that the additional nitrogen released in whale urine would be difficult to measure in a field study, the results of this study support the idea that the distinctive isotopic signature of the released NH4 + could be used to provide a conservative estimate of the contribution of the whale pump to primary productivity in coastal regions where whales congregate
Improved detection of diffuse glioma infiltration with imaging combinations: a diagnostic accuracy study
Background
Surgical resection and irradiation of diffuse glioma are guided by standard MRI: T2/FLAIR-weighted MRI for non-enhancing and T1-weighted gadolinium-enhanced (T1G) MRI for enhancing gliomas. Amino acid PET has been suggested as new standard. Imaging combinations may improve standard MRI and amino acid PET. The aim of the study was to determine the accuracy of imaging combinations to detect glioma infiltration.
Methods
We included 20 consecutive adults with newly-diagnosed non-enhancing (seven diffuse astrocytomas, IDH-mutant; one oligodendroglioma, IDH-mutant and1p/19q-codeleted; one glioblastoma IDH-wildtype) or enhancing glioma (glioblastoma, nine IDH-wildtype and two IDH-mutant). Standardized pre-operative imaging (T1-, T2-, FLAIR-weighted and T1G MRI, perfusion and diffusion MRI, MR spectroscopy and O-(2-[18F]-fluoroethyl)-L-tyrosine ([18F]FET) PET) was co-localized with multi-region stereotactic biopsies preceding resection. Tumor presence in the biopsies was assessed by two neuropathologists. Diagnostic accuracy was determined using receiver operating characteristic analysis.
Results
A total of 174 biopsies were obtained (63 from nine non-enhancing and 111 from 11 enhancing gliomas), of which 129 contained tumor (50 from non-enhancing and 79 from enhancing gliomas). In enhancing gliomas, the combination of Apparent Diffusion Coefficient (ADC) with [18F]FET PET (AUC, 95%CI: 0.89,0.79-0.99) detected tumor better than T1G MRI (0.56,0.39-0.72;P<.001) and [18F]FET PET (0.76,0.66-0.86;P=0.001). In non-enhancing gliomas, no imaging combination detected tumor significantly better than standard MRI. FLAIR-weighted MRI had an AUC of 0.81 (0.65-0.98) compared to 0.69 (0.56-0.81;P=0.019) for [18F]FET PET.
Conclusion and relevance
Combining ADC and [18F]FET PET detects glioma infiltration better than standard MRI and [18F]FET PET in enhancing gliomas, potentially enabling better guidance of local therapy
Norovirus infections in children under 5 years of age hospitalized due to the acute viral gastroenteritis in northeastern Poland
The primary aim of this study was to evaluate the frequency and seasonality of norovirus infection in hospitalized Polish children under 5 years of age, and a secondary aim was to compare the clinical severity of norovirus and rotavirus disease. The prospective surveillance study was carried out from July 2009 through June 2010. Stool samples from 242 children hospitalized due to acute viral gastroenteritis were tested for rotavirus group A and adenovirus with commercial immunochromatographic test and for norovirus with EIA assay. Single norovirus infection was found in 35/242 (14.5%) patients and in a further 5 (2.1%) children as co-infection with rotavirus. Overall, norovirus was detected in 16.5% of stool specimens. Norovirus infections tended to peak from October to November and again from February to March. In autumn months and in February, the proportion of norovirus gastroenteritis cases was equal or even surpassed those of rotavirus origin. Both norovirus and rotavirus infections most commonly affected children between 12 and 23 months of age. The low-grade or no fever was significantly more common in children infected with norovirus (94.3%) compared to rotavirus cases (52.9%). Overall, norovirus gastroenteritis was less severe than rotavirus disease with regard to 20-point severity scale (p < 0.05). Noroviruses have emerged as a relevant cause of acute gastroenteritis in Polish children. There is a great need for introducing routine norovirus testing of hospitalized children with gastroenteritis
Molecular Phylogenetics of the Genus Neoconocephalus (Orthoptera, Tettigoniidae) and the Evolution of Temperate Life Histories
BACKGROUND:The katydid genus Neoconocephalus (25+ species) has a prominent acoustic communication system and occurs in large parts of the Neotropics and Nearctic. This group has been subject of numerous behavioral, physiological, and evolutionary studies of its acoustic communication system. Two distinct life histories occur in this group: The tropical life history incorporates multiple generations/year and direct egg development without environmental triggers. Temperate life history is characterized by overwintering in the egg stage, cold trigger of egg development, and one generation/year. This study reconstructs the phylogenetic relationships within the genus to (1) determine the evolutionary history of the temperate life history, and (2) to support comparative studies of evolutionary and physiological problems in this genus. METHODOLOGY/PRINCIPAL FINDINGS:We used Amplified Fragment Length Polymorphisms (AFLP), and sequences of two nuclear loci and one mitochondrial locus to reconstruct phylogenetic relationships. The analysis included 17 ingroup and two outgroup species. AFLP and mitochondrial data provided resolution at the species level while the two nuclear loci revealed only deeper nodes. The data sets were combined in a super-matrix to estimate a total evidence tree. Seven of the temperate species form a monophyletic group; however, three more temperate species were placed as siblings of tropical species. CONCLUSIONS/SIGNIFICANCE:Our analyses support the reliability of the current taxonomic treatment of the Neoconocephalus fauna of Caribbean, Central, and North America. Ancestral state reconstruction of life history traits was not conclusive, however at least four transitions between life histories occurred among our sample of species. The proposed phylogeny will strengthen conclusions from comparative work in this group
Loss of Ep-CAM (CO17-1A) expression predicts survival in patients with gastric cancer
Preoperative staging of gastric cancer is difficult and not optimal. The TNM stage is an important prognostic factor, but it can only be assessed reliably after surgery. Therefore, there is need for additional, reliable prognostic factors that can be determined preoperatively in order to select patients who might benefit from (neo) adjuvant treatment. Expression of immunohistochemical markers was demonstrated to be associated with tumour progression and metastasis. The expression of p53, CD44 (splice variants v5, v6 and v9), E-cadherin, Ep-CAM (CO17-1A antigen) and c-erB2/neu were investigated in tumour tissues of 300 patients from the Dutch Gastric Cancer Trial, investigating the value of extended lymphadenectomy compared to that of limited lymphadenectomy). The expression of tumour markers was analysed with respect to patient survival. Patients without loss of Ep-CAM-expression of tumour cells (19%) had a significantly better 10-year survival (P<0.0001) compared to patients with any loss: 42% (s.e.=7%) vs 22% (s.e.=3%). Patients with CD44v6 (VFF18) expression in more than 25% of the tumour cells (69% of the patients) also had a significantly better survival (P=0.01) compared to patients with expression in less than 25% of the tumour cells: 10 year survival rate of 29% (s.e.=3%) vs 19% (s.e.=4%). The prognostic value of both markers was stronger in stages I and II, and independent of the TNM stage. Ep-CAM and CD44v6-expression provides prognostic information additional to the TNM stage. Loss of Ep-CAM-expression identifies aggressive tumours especially in patients with stage I and II disease. This information may be helpful in selecting patients suitable for surgery or for additional treatment pre- or postoperatively
Direct comparison of [11C] choline and [18F] FET PET to detect glioma infiltration: a diagnostic accuracy study in eight patients
Background
Positron emission tomography (PET) is increasingly used to guide local treatment in glioma. The purpose of this study was a direct comparison of two potential tracers for detecting glioma infiltration, O-(2-[18F]-fluoroethyl)-l-tyrosine ([18F] FET) and [11C] choline.
Methods
Eight consecutive patients with newly diagnosed diffuse glioma underwent dynamic [11C] choline and [18F] FET PET scans. Preceding craniotomy, multiple stereotactic biopsies were obtained from regions inside and outside PET abnormalities. Biopsies were assessed independently for tumour presence by two neuropathologists. Imaging measurements were derived at the biopsy locations from 10 to 40 min [11C] choline and 20–40, 40–60 and 60–90 min [18F] FET intervals, as standardized uptake value (SUV) and tumour-to-brain ratio (TBR). Diagnostic accuracies of both tracers were compared using receiver operating characteristic analysis and generalized linear mixed modelling with consensus histopathological assessment as reference.
Results
Of the 74 biopsies, 54 (73%) contained tumour. [11C] choline SUV and [18F] FET SUV and TBR at all intervals were higher in tumour than in normal samples. For [18F] FET, the diagnostic accuracy of TBR was higher than that of SUV for intervals 40–60 min (area under the curve: 0.88 versus 0.81, p = 0.026) and 60–90 min (0.90 versus 0.81, p = 0.047). The diagnostic accuracy of [18F] FET TBR 60–90 min was higher than that of [11C] choline SUV 20–40 min (0.87 versus 0.67, p = 0.005).
Conclusions
[18F] FET was more accurate than [11C] choline for detecting glioma infiltration. Highest accuracy was found for [18F] FET TBR for the interval 60–90 min post-injection
Microbial degradation of furanic compounds: biochemistry, genetics, and impact
Microbial metabolism of furanic compounds, especially furfural and 5-hydroxymethylfurfural (HMF), is rapidly gaining interest in the scientific community. This interest can largely be attributed to the occurrence of toxic furanic aldehydes in lignocellulosic hydrolysates. However, these compounds are also widespread in nature and in human processed foods, and are produced in industry. Although several microorganisms are known to degrade furanic compounds, the variety of species is limited mostly to Gram-negative aerobic bacteria, with a few notable exceptions. Furanic aldehydes are highly toxic to microorganisms, which have evolved a wide variety of defense mechanisms, such as the oxidation and/or reduction to the furanic alcohol and acid forms. These oxidation/reduction reactions constitute the initial steps of the biological pathways for furfural and HMF degradation. Furfural degradation proceeds via 2-furoic acid, which is metabolized to the primary intermediate 2-oxoglutarate. HMF is converted, via 2,5-furandicarboxylic acid, into 2-furoic acid. The enzymes in these HMF/furfural degradation pathways are encoded by eight hmf genes, organized in two distinct clusters in Cupriavidus basilensis HMF14. The organization of the five genes of the furfural degradation cluster is highly conserved among microorganisms capable of degrading furfural, while the three genes constituting the initial HMF degradation route are organized in a highly diverse manner. The genetic and biochemical characterization of the microbial metabolism of furanic compounds holds great promises for industrial applications such as the biodetoxifcation of lignocellulosic hydrolysates and the production of value-added compounds such as 2,5-furandicarboxylic acid
Search for CP violation in D+→ϕπ+ and D+s→K0Sπ+ decays
A search for CP violation in D + → ϕπ + decays is performed using data collected in 2011 by the LHCb experiment corresponding to an integrated luminosity of 1.0 fb−1 at a centre of mass energy of 7 TeV. The CP -violating asymmetry is measured to be (−0.04 ± 0.14 ± 0.14)% for candidates with K − K + mass within 20 MeV/c 2 of the ϕ meson mass. A search for a CP -violating asymmetry that varies across the ϕ mass region of the D + → K − K + π + Dalitz plot is also performed, and no evidence for CP violation is found. In addition, the CP asymmetry in the D+s→K0Sπ+ decay is measured to be (0.61 ± 0.83 ± 0.14)%
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