Low discharge intensifies nitrogen retention in rivers - A case study in the Elbe River.

Eutrophication due to excessive nutrient inputs is a major threat to coastal ecosystems worldwide, causing harmful algae blooms, seagrass loss and hypoxia. Decisions to combat eutrophication in the North Sea were made in the 1980s. Despite significant improvements during recent decades, high nitrogen loads and resulting eutrophication problems remain. In this study, long-term changes in nitrogen inputs to the Elbe Estuary (Germany) were characterized based on nitrogen data provided by the Elbe River Basin Community from 1985 to 2019. Additionally, surface water samples were taken at the weir separating the river from the estuary from 2011 to 2021 to characterize dissolved inorganic nitrogen concentrations and nitrate stable isotope composition. The findings suggest a close coupling of river discharge with the riverine nitrogen cycle. Nitrogen loads decreased disproportionately with decreasing discharge. This decrease is due to intensified nitrogen retention in the Elbe catchment, which can double nitrogen retention compared to average discharge conditions. Phytoplankton growth was enhanced by long residence times and high light availability at low water levels. This suggests that the recent decreases in nitrogen loads in the Elbe River were not only a result of management measures in the catchment but were also amplified by a recent long-lasting drought in the catchment. Based on projections from the Intergovernmental Panel on Climate Change, more frequent and extensive droughts are anticipated, which may lead to future seasonal shifts to nitrate limitation in the lower Elbe River.

Peroxisome proliferator-activated receptor gamma is highly expressed in pancreatic cancer and is associated with shorter overall survival times.

PURPOSE: Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-activated transcription factor that has been implicated in carcinogenesis and progression of various solid tumors, including pancreatic carcinoma. We aimed to clarify the expression patterns of PPARgamma in pancreatic ductal carcinomas and to correlate these to clinicopathologic variables, including patient survival. EXPERIMENTAL DESIGN: Array-based expression profiling of 19 microdissected carcinomas and 14 normal ductal epithelia was conducted. Additionally, Western blots of pancreatic cancer cell lines and paraffinized tissue of 129 pancreatic carcinomas were immunostained for PPARgamma. For statistical analysis, Fisher's exact test, chi2 test for trends, correlation analysis, Kaplan-Meier analysis, and Cox's regression were applied. RESULTS: Expression profiles showed a strong overexpression of PPARgamma mRNA (change fold, 6.9; P=0.04). Immunohistochemically, PPARgamma expression was seen in 71.3% of pancreatic cancer cases. PPARgamma expression correlated positively to higher pT stages and higher tumor grade. Survival analysis showed a significant prognostic value for PPARgamma, which was found to be independent in the clinically important subgroup of node-negative tumors. CONCLUSIONS: PPARgamma is commonly up-regulated in pancreatic ductal adenocarcinoma and might be a prognostic marker in this disease. Both findings corroborate the importance of PPARgamma in tumor progression of pancreatic cancer.

Overexpression of Polo-like kinase 1 is a common and early event in pancreatic cancer.

BACKGROUND: There is abundant evidence from in vivo and in vitro studies that Polo-like kinase 1 (PLK1) plays a crucial role in the regulation of proliferative activity of normal and malignant cells. Therefore, PLK1 has been proposed as a new target for antineoplastic treatment strategies. METHODS: We conducted an immunohistochemical expression study for PLK1 on 86 cases of pancreatic adenocarcinoma as well as on 5 cases of chronic pancreatitis. Additionally, we investigated the correlation of PLK1 expression levels with clinicopathological data and patient survival. RESULTS: PLK1 was found overexpressed in pancreatic neoplasia as early as in pancreatic intraepithelial neoplasia III lesions, whereas benign acinar pancreatic parenchyma and ductal epithelia showed only focal PLK1 positivity. Invasive pancreatic adenocarcinomas were PLK1 positive in 47.7% of cases. No correlation of PLK1 positivity and the extent of tumour spread was evident, nor did PLK1 expression correlate with tumour grade or patient prognosis. Prognostic factors in our study cohort were nodal status and tumour grade. CONCLUSIONS: The fact that half of the invasive pancreatic carcinomas strongly overexpressed PLK1 indicates that inhibition of this mitotic key regulator might represent a rewarding approach in the treatment of early and late pancreatic carcinoma.

Expression of CD24 in adenocarcinomas of the pancreas correlates with higher tumor grades.

BACKGROUND/AIMS: CD24 is expressed in hematological malignancies as well as in a large variety of solid tumors and is often associated with a more aggressive course of the disease. We aimed to evaluate CD24 protein expression in pancreatic adenocarcinomas and to correlate it to clinicopathological data including patient survival. METHODS: 95 primary adenocarcinomas of the pancreas were immunostained using a monoclonal CD24 antibody (Ab-2, clone 24C02). Staining was evaluated as negative versus positive for statistical analysis. RESULTS: CD24 expression was observed in 71.6% of cases with a heterogeneous distribution, and a significantly higher rate of positivity in high grade (G3) tumors. In univariate survival analyses, no association of CD24 expression with shortened overall survival of the patients could be demonstrated. CONCLUSION: CD24 is commonly expressed in adenocarcinomas of the pancreas, preferentially high-grade tumors and thus might be a marker of disease progression.