Urea

Conversion and characterization of activated carbon fiber derived from palm empty fruit bunch waste and its kinetic study on urea adsorption.[Pubmed:28384613]

J Environ Manage. 2017 Jul 15;197:199-205.

Urea removal is an important process in household wastewater purification and hemodialysis treatment. The efficiency of the Urea removal can be improved by utilizing activated carbon fiber (ACF) for effective Urea adsorption. In this study, ACF was prepared from oil palm empty fruit bunch (EFB) fiber via physicochemical activation using sulfuric acid as an activating reagent. Based on the FESEM result, ACF obtained after the carbonization and activation processes demonstrated uniform macropores with thick channel wall. ACF was found better prepared in 1.5:1 acid-to-EFB fiber ratio; where the pore size of ACF was analyzed as 1.2 nm in diameter with a predominant micropore volume of 0.39 cm(3) g(-1) and a BET surface area of 869 m(2) g(-1). The reaction kinetics of Urea adsorption by the ACF was found to follow a pseudo-second order kinetic model. The equilibrium amount of Urea adsorbed on ACF decreased from 877.907 to 134.098 mg g(-1) as the acid-to-fiber ratio increased from 0.75 to 4. During the adsorption process, the hydroxyl (OH) groups on ACF surface were ionized and became electronegatively charged due to the weak alkalinity of Urea solution, causing ionic repulsion towards partially anionic Urea. The ionic repulsion force between the electronegatively charged ACF surface and Urea molecules became stronger when more OH functional groups appeared on ACF prepared at higher acid impregnation ratio. The results implied that EFB fiber based ACF can be used as an efficient adsorbent for the Urea removal process.

Can salivary creatinine and urea levels be used to diagnose chronic kidney disease in children as accurately as serum creatinine and urea levels? A case-control study.[Pubmed:28372505]

Ren Fail. 2017 Nov;39(1):452-457.

BACKGROUND AND AIM: Children with chronic kidney disease (CKD) develop many metabolic changes in blood that often necessitate frequent biochemical analysis. Serum analysis is an invasive and painful procedure. It would be highly beneficial if a noninvasive alternative process to serum analysis in children were identified. Saliva can be collected noninvasively, repeatedly, and without the use of healthcare personnel. The aims of this study were to compare serum and salivary Urea and creatinine levels in children with CKD and healthy controls, and to determine if salivary creatinine and Urea levels can be used to diagnose CKD in children as accurately as serum creatinine and Urea levels. MATERIALS AND METHODS: This case-control study included 35 children with CKD and 28 healthy children as controls. Saliva and blood samples were collected for measurement of Urea and creatinine levels. The Urea and creatinine levels in serum and saliva in the CKD and control groups were compared using the independent samples Mann-Whitney U test. Correlations between the serum and salivary Urea and creatinine levels were determined using Pearson's correlation coefficient. Receiver operating characteristic analysis was used to assess the diagnostic performance of salivary creatinine and cutoff values were identified. RESULTS: In the CKD group, the mean salivary creatinine level was 0.45 mg/dL and the mean salivary Urea level was 0.11 mg/dL, versus 28.83 mg/dL and 21.78 mg/dL, respectively, in the control group. Stage 4 and 5 CKD patients had a mean salivary Urea level of 31.35 mg/dL, as compared to 17.78 mg/dL in the control group. Serum Urea and creatinine, and salivary creatinine were significantly higher in the CKD patients (regardless of disease stage) than in the controls (p < .05). The salivary Urea level was significantly higher in the stage 4 and 5 CKD patients than in the controls (p < .05). There was a positive correlation between serum and salivary creatinine. The area under the curve for salivary creatinine was 0.805. The cutoff value for salivary creatinine was 0.125 mg/dL, with a sensitivity of 82.9% and specificity of 78.6%. CONCLUSIONS: Based on the positive correlation between the serum and saliva creatinine levels observed in the present study, we think saliva analysis could be used as a noninvasive alternative to blood analysis for diagnosing CKD in children.

Urea Release by Intermittently Saturated Sediments from a Coastal Agricultural Landscape.[Pubmed:28380555]

J Environ Qual. 2017 Mar;46(2):302-310.

Urea-N is linked to harmful algal blooms in lakes and estuaries, and Urea-N-based fertilizers have been implicated as a source. However, the export of Urea-N-based fertilizers appears unlikely, as high concentrations of Urea-N are most commonly found in surface waters outside periods of fertilization. To evaluate possible autochthonous production of Urea-N, we monitored Urea-N released from drainage ditch sediments using mesocosms. Sediments from a cleaned (recently dredged) drainage ditch, uncleaned ditch, forested ditch, riparian wetland, and an autoclaved sand control were isolated in mesocosms and flooded for 72 h to quantify Urea-N, NH-N, and NO-N in the floodwater. Sediments were flooded with different N-amended solutions (distilled HO, 1.5 mg L NH-N, 3.0 mg L NH-N, 2.6 mg L NO-N, or 5.1 mg L NO-N) and incubated at three water temperatures (16, 21, and 27 degrees C). Urea-N concentrations in mesocosms representing uncleaned and cleaned drainage ditches were significantly greater than nonagricultural sediments and controls. While flooding sediments with N-enriched solution had no clear effect on Urea-N, warmer (27 degrees C) temperatures resulted in significantly higher Urea-N. Data collected from field ditches that were flooded by a summer rainstorm showed increases in Urea-N that mirrored the mesocosm experiment. We postulate that concentrations of Urea-N in ditches that greatly exceed environmental thresholds are mediated by biological production in sediments and release to stagnant surface water. Storm-driven Urea-N export from ditches could elevate the risk of harmful algal blooms downstream in receiving waters despite the dilution effect.

Association between an increase in blood urea nitrogen at 24 hours and worse outcomes in acute nonvariceal upper GI bleeding.[Pubmed:28377105]

Gastrointest Endosc. 2017 Dec;86(6):1022-1027.e1.

BACKGROUND AND AIMS: An increase in blood Urea nitrogen (BUN) at 24 hours is a solitary and significant predictor of mortality in patients with acute pancreatitis, which may predict worse outcomes in the similarly resuscitation-requiring condition of acute nonvariceal upper GI bleeding (UGIB). The aim of our study was to assess whether an increase in BUN at 24 hours is predictive of worse clinical outcomes in acute nonvariceal UGIB. METHODS: A retrospective cohort study including patients admitted to an academic hospital from 2004 to 2014 was conducted. An increase in BUN was defined as an increase in BUN at 24 hours of hospitalization compared with BUN at presentation. The primary outcome was a composite of inpatient death, inpatient rebleeding, need for surgical or radiologic intervention, or endoscopic reintervention. Associations between BUN change and outcomes were assessed via the Pearson chi(2) test and the Fisher exact test and via logistic regression for adjusted analyses. RESULTS: There were 357 patients included in the analysis with a mean age of 64 years; 54% were men. The mean change in BUN was -10.1 mg/dL (standard deviation, 12.7 mg/dL). Patients with an increased BUN (n = 37 [10%]) were significantly more likely to experience the composite outcome (22% vs 9%, P = .014), including an increased risk of inpatient death (8% vs 1%, P = .004), compared with patients with a decreased or unchanged BUN (n = 320 [90%]). In a logistic regression model adjusting for the AIMS65 score, an increase in BUN was independently associated with an increased risk for the composite outcome (odds ratio, 2.75; P = .026). CONCLUSION: Increasing BUN at 24 hours likely reflects under resuscitation and is a predictor of worse outcomes in patients with acute nonvariceal UGIB.

Urea is a powerful protein denaturant via both direct and indirect mechanisms. A potent emollient and keratolytic agent. Used as a diuretic agent. Blood urea nitrogen (BUN) has been utilized to evaluate renal function. Widely used in fertilizers as a source of nitrogen and is an important raw material for the chemical industry.

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