Demographic and clinical profile of patients undergoing colonoscopy at a tertiary care center in Nepal: a retrospective cross-sectional study.

Background: Colonoscopy is widely used as a tool for diagnosis, screening and treatment of various pathologies in the rectum, colon, and terminal ileum. The aim of this study is to evaluate the demographic, clinical, and histological parameters of the records of patients undergoing colonoscopy at a tertiary care hospital in Nepal. Materials and methods: This retrospective cross-sectional study included the hospital records of all patients who underwent colonoscopy from 2015 to 2019 in a tertiary care centre in Nepal. Results: A total of 1255 records were included in the study. The mean and standard deviation of age were 43.8 and 19 years, respectively. Among the total study population, 61.9% were males and 38.1% were females. Common indications for colonoscopy included lower gastrointestinal bleeding (27.7%), altered bowel habit (26.9%) and persistent or recurrent abdominal pain (17.3%). Only 3% of the patients who underwent colonoscopy had inadequate bowel preparation. The overall diagnostic yield of colonoscopy was 57.5%. Findings during colonoscopy included colorectal polyp (19.4%), internal haemorrhoids (8.2%) and colitis (6.5%). Having an age of 50 or more years was significantly associated with the presence of colorectal adenocarcinoma (P=0.017, χ2 test) with an odds ratio of 2.35 (95% CI: 1.14, 4.89). Furthermore, having a female sex was found to be significantly associated with the presence of colorectal adenocarcinoma (P=0.012, χ2 test) with an odds ratio of 2.43 (95% CI: 1.19, 4.97). Conclusion: In the authors' study, a smaller proportion of the colonoscopies was aimed at screening for colorectal carcinoma (CRC), when compared to studies in developed countries. The sex predisposition of CRC in the authors' study is in contrast to the global trend. The authors recommend conducting studies to determine the risk factors and need for CRC screening in the Nepalese population.

Impacts assessment of nitrification inhibitors on U.S. agricultural emissions of reactive nitrogen gases.

Fertilizer-intensive agriculture leads to emissions of reactive nitrogen (Nr), posing threats to climate via nitrous oxide (N2O) and to air quality and human health via nitric oxide (NO) and ammonia (NH3) that form ozone and particulate matter (PM) downwind. Adding nitrification inhibitors (NIs) to fertilizers can mitigate N2O and NO emissions but may stimulate NH3 emissions. Quantifying the net effects of these trade-offs requires spatially resolving changes in emissions and associated impacts. We introduce an assessment framework to quantify such trade-off effects. It deploys an agroecosystem model with enhanced capabilities to predict emissions of Nr with or without the use of NIs, and a social cost of greenhouse gas to monetize the impacts of N2O on climate. The framework also incorporates reduced-complexity air quality and health models to monetize associated impacts of NO and NH3 emissions on human health downwind via ozone and PM. Evaluation of our model against available field measurements showed that it captured the direction of emission changes but underestimated reductions in N2O and overestimated increases in NH3 emissions. The model estimated that, averaged over applicable U.S. agricultural soils, NIs could reduce N2O and NO emissions by an average of 11% and 16%, respectively, while stimulating NH3 emissions by 87%. Impacts are largest in regions with moderate soil temperatures and occur mostly within two to three months of N fertilizer and NI application. An alternative estimate of NI-induced emission changes was obtained by multiplying the baseline emissions from the agroecosystem model by the reported relative changes in Nr emissions suggested from a global meta-analysis: -44% for N2O, -24% for NO and +20% for NH3. Monetized assessments indicate that on an annual scale, NI-induced harms from increased NH3 emissions outweigh (8.5-33.8 times) the benefits of reducing NO and N2O emissions in all agricultural regions, according to model-based estimates. Even under meta-analysis-based estimates, NI-induced damages exceed benefits by a factor of 1.1-4. Our study highlights the importance of considering multiple pollutants when assessing NIs, and underscores the need to mitigate NH3 emissions. Further field studies are needed to evaluate the robustness of multi-pollutant assessments.

Modeling nitrous oxide mitigation potential of enhanced efficiency nitrogen fertilizers from agricultural systems.

Agriculture soils are responsible for a large proportion of global nitrous oxide (N2O) emissions-a potent greenhouse gas and ozone depleting substance. Enhanced-efficiency nitrogen (N) fertilizers (EENFs) can reduce N2O emission from N-fertilized soils, but their effect varies considerably due to a combination of factors, including climatic conditions, edaphic characteristics and management practices. In this study, we further developed the DayCent ecosystem model to simulate two EENFs: controlled-release N fertilizers (CRNFs) and nitrification inhibitors (NIs) and evaluated their N2O mitigation potentials. We implemented a Bayesian calibration method using the sampling importance resampling (SIR) algorithm to derive a joint posterior distribution of model parameters that was informed by N2O flux measurements from corn production systems a network of experimental sites within the GRACEnet program. The joint posterior distribution can be applied to estimate predictions of N2O reduction factors when EENFs are adopted in place of conventional urea-based N fertilizer. The resulting median reduction factors were - 11.9% for CRNFs (ranging from -51.7% and 0.58%) and - 26.7% for NIs (ranging from -61.8% to 3.1%), which is comparable to the measured reduction factors in the dataset. By incorporating EENFs, the DayCent ecosystem model is able to simulate a broader suite of options to identify best management practices for reducing N2O emissions.