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Conformational destabilization of Bacillus licheniformis α-amylase induced by lysine modification and calcium depletion

Tan CY, Rahman RN, Kadir HA, Tayyab S

Acta Biochim. Pol., 2011;58(3):405-12.
PMID: 21887412

Bacillus licheniformis α-amylase (BLA) was chemically modified using 100-fold molar excess of succinic anhydride over protein or 0.66 M potassium cyanate to obtain 42 % succinylated and 81 % carbamylated BLAs. Size and charge homogeneity of modified preparations was established by Sephacryl S-200 HR gel chromatography and polyacrylamide gel electrophoresis. Conformational alteration in these preparations was evident by the larger Stokes radii (3.40 nm for carbamylated and 3.34 nm for succinylated BLAs) compared to 2.43 nm obtained for native BLA. Urea denaturation results using mean residue ellipticity (MRE) as a probe also showed conformational destabilization based on the early start of transition as well as ΔG(D)(H(2)O) values obtained for both modified derivatives and Ca-depleted BLA. Decrease in ΔG(D)(H(2)O) value from 5,930 cal/mol (for native BLA) to 3,957 cal/mol (for succinylated BLA), 3,336 cal/mol (for carbamylated BLA) and 3,430 cal/mol for Ca-depleted BLA suggested reduced conformational stability upon modification of amino groups of BLA or depletion of calcium. Since both succinylation and carbamylation reactions abolish the positive charge on amino groups (both α- and ε- amino), the decrease in conformational stability can be ascribed to the disruption of salt bridges present in the protein which might have released the intrinsic calcium from its binding site.

Matched MeSH terms: Urea/chemistry
Bromophenol blue binding as a probe to study urea and guanidine hydrochloride denaturation of bovine serum albumin

Halim AA, Kadir HA, Tayyab S

J. Biochem., 2008 Jul;144(1):33-8.
PMID: 18344543 DOI: 10.1093/jb/mvn036

Urea and guanidine hydrochloride (GdnHCl) denaturation of bovine serum albumin (BSA) were investigated using bromophenol blue (BPB) binding as a probe. Addition of BPB to BSA produced an absorption difference spectrum in the wavelength range, 525-675 nm with a minimum at 587 nm and a maximum at 619 nm. The magnitude of absorption difference (DeltaAbs.) at 619 nm decreased on increasing urea/GdnHCl concentration and followed the denaturation curve. The denaturation was found to be a two-state, single-step transition. The transitions started at 1.75 and 0.875 M and completed at 6.5 and 3.25 M with the mid point occurring around 4.0 and 1.5 M urea and GdnHCl concentrations, respectively. The value of free energy of stabilization, DeltaGDH2O as determined from urea and GdnHCl denaturation curves was found to be 4041 and 4602 cal/mol, respectively. Taken together, these results suggest that BPB binding can be used as a probe to study urea and GdnHCl denaturation of BSA.

Matched MeSH terms: Urea*
Fulltext Enhancing the urea-N use efficiency in maize (Zea mays) cultivation on acid soils amended with zeolite and TSP

Ahmed OH, Hussin A, Ahmad HM, Rahim AA, Majid NM

ScientificWorldJournal, 2008 Apr 20;8:394-9.
PMID: 18454247 DOI: 10.1100/tsw.2008.68

Ammonia loss significantly reduces the urea-N use efficiency in crop production. Efforts to reduce this problem are mostly laboratory oriented. This paper reports the effects of urea amended with triple superphosphate (TSP) and zeolite (Clinoptilolite) on soil pH, nitrate, exchangeable ammonium, dry matter production, N uptake, fresh cob production, and urea-N uptake efficiency in maize (Zea mays) cultivation on an acid soil in actual field conditions. Urea-amended TSP and zeolite treatments and urea only (urea without additives) did not have long-term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf) production of Swan (test crop). All the treatments had no significant effect on urea-N concentration in the leaf and stem of the test crop. In terms of urea-N uptake in the leaf and stem tissues of Swan, only the treatment with the highest amount of TSP and zeolite significantly increased urea-N uptake in the leaf of the test crop. Irrespective of treatment, fresh cob production was statistically not different. However, all the treatments with additives improved urea-N uptake efficiency compared to urea without additives or amendment. This suggests that urea amended with TSP and zeolite has a potential of reducing ammonia loss from surface-applied urea.

Matched MeSH terms: Urea/pharmacokinetics*
Fulltext A Study of Dielectric Properties of Proteinuria between 0.2 GHz and 50 GHz

Mun PS, Ting HN, Ong TA, Wong CM, Ng KH, Chong YB

PLoS One, 2015;10(6):e0130011.
PMID: 26066351 DOI: 10.1371/journal.pone.0130011

This paper investigates the dielectric properties of urine in normal subjects and subjects with chronic kidney disease (CKD) at microwave frequency of between 0.2 GHz and 50 GHz. The measurements were conducted using an open-ended coaxial probe at room temperature (25°C), at 30°C and at human body temperature (37°C). There were statistically significant differences in the dielectric properties of the CKD subjects compared to those of the normal subjects. Statistically significant differences in dielectric properties were observed across the temperatures for normal subjects and CKD subjects. Pearson correlation test showed the significant correlation between proteinuria and dielectric properties. The experimental data closely matched the single-pole Debye model. The relaxation dispersion and relaxation time increased with the proteinuria level, while decreasing with the temperature. As for static conductivity, it increased with proteinuria level and temperature.

Matched MeSH terms: Urea/chemistry*
Fulltext 14C-urea breath test: a useful non-invasive test in the diagnosis of Helicobacter pylori infection

Goh KL, Parasakthi N, Peh SC, Ong KK

Med J Malaysia, 1995 Sep;50(3):208-11.
PMID: 8926896

Sixty-three breath samples were collected from patients who underwent a 14C-urea breath test. Following ingestion of a radiolabelled 14C-labelled urea solution, breath samples containing 14C-labelled carbon dioxide were trapped in a solution containing hyamine hydroxide. Samples were then counted in a liquid scintillation counter. Breath samples were collected at 2, 15, 20, 25 and 30 minutes following ingestion of the urea solution. The presence or absence of Helicobacter pylori (HP) infection was determined on the basis of endoscopic biopsy tests which included culture, histological examination, rapid urease test and a gram stain of a fresh tissue smear. Thirty-two HP positive and 31 HP negative samples were collected. The mean counts at 15, 20, 12 and 30 minutes time points were: 4413, 4458, 4109 and 3795 dpm respectively for the positive samples and 1275, 877, 690 and 565 dpm respectively for the negative samples. Based on a cutoff value (mean of the negative samples + 3 standard deviations) for every time point, HP positive and negative samples could be clearly differentiated giving a sensitivity and specificity of 100%. The 14C-urea breath test is a reliable and convenient diagnostic test for H. pylori.

Matched MeSH terms: Urea*
Fulltext Continuous ambulatory peritoneal dialysis--a preliminary report on 7 patients

Chua CT, Wang F

Med J Malaysia, 1983 Sep;38(3):244-50.
PMID: 6672569

Study site: CAPD, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia

Matched MeSH terms: Urea/blood
Co-Adsorptive Removal of Creatinine and Urea by a Three-Component Dual-Layer Hollow Fiber Membrane

Zainol Abidin MN, Goh PS, Said N, Ismail AF, Othman MHD, Hasbullah H, et al.

ACS Appl Mater Interfaces, 2020 Jul 22;12(29):33276-33287.
PMID: 32589391 DOI: 10.1021/acsami.0c08947

The development of wearable artificial kidney demands an efficient dialysate recovery, which relies upon the adsorption process. This study proposes a solution to solve the problem of competitive adsorption between the uremic toxins by employing two adsorptive components in a membrane separation process. Dual-layer hollow fiber (DLHF) membranes, which are composed of a polysulfone (PSf)/activated carbon (AC) inner layer and a PSf/poly(methyl methacrylate) (PMMA) outer layer, were prepared for co-adsorptive removal of creatinine and urea from aqueous solution. The DLHF membranes were characterized in terms of morphological, physicochemical, water transport, and creatinine adsorption properties. The membrane was then subjected to an ultrafiltration adsorption study for performance evaluation. The incorporation of AC in membrane, as confirmed by microscopic and surface analyses, has improved the pure water flux up to 25.2 L/(m2 h). A membrane with optimum AC loading (9 wt %) demonstrated the highest maximum creatinine adsorption capacity (86.2 mg/g) based on the Langmuir adsorption isotherm model. In the ultrafiltration adsorption experiment, the membrane removed creatinine and urea with a combined average percent removal of 29.3%. Moreover, the membrane exhibited creatinine and urea uptake recoveries of 98.8 and 81.2%, respectively. The combined action of PMMA and AC in the PSf DLHF membrane has made the adsorption of multiple uremic toxins possible during dialysate recovery.

Matched MeSH terms: Urea/chemistry*
Chemically crosslinked hydrogel and its driving force towards superabsorbent behaviour

Salleh KM, Zakaria S, Sajab MS, Gan S, Chia CH, Jaafar SNS, et al.

Int J Biol Macromol, 2018 Oct 15;118(Pt B):1422-1430.
PMID: 29964115 DOI: 10.1016/j.ijbiomac.2018.06.159

Dissolved oil palm empty fruit bunch (EFB) cellulose in NaOH/urea solvent was mixed with sodium carboxymethylcellulose (NaCMC) to form a green regenerated superabsorbent hydrogel. The effect of concentration of epichlorohydrin (ECH) as the crosslinker on the formation, physical, and chemical properties of hydrogel was studied. Rapid formation and higher gel content of hydrogel were observed at 10% concentration of ECH. The superabsorbent hydrogel was successfully fabricated in this study with the swelling ability >100,000%. Hydrogel with higher concentration of ECH showed opposite trend by having higher superabsorbent property than that of lower concentration. The covalent bond of COC was observed with Attenuated total reflectance fourier transform infrared (ATR-FT-IR) spectroscopy to confirm the occurrence of crosslinking. The physical and chemical properties of hydrogel were affected by swelling phenomenon. Hydrogel with higher degree of swelling exhibited lower moisture retention and higher transparency. Moreover, the weight of the superabsorbent hydrogel increased with the decrement of pH value of external media (distilled water). This study provided substantial information on the effect of different percentage of ECH as crosslinker on hydrogel basic properties. Furthermore, this study affords correlation of many essential driving forces that affected hydrogel superabsorbent property.

Matched MeSH terms: Urea/chemistry
13C-Urea Breath Test Accuracy for Helicobacter pylori Infection in the Asian Population: A Meta-Analysis

Abd Rahim MA, Johani FH, Shah SA, Hassan MR, Abdul Manaf MR

Ann Glob Health, 2019 Jul 24;85(1).
PMID: 31348624

BACKGROUND: Helicobacter pylori (H. pylori) infection is known to be associated with peptic ulcer and gastric cancer. Detection of H. pylori infection is a significant part of peptic ulcer and gastric cancer prevention and management. 13C-urea breath test (UBT) provides a good option for the pathogen detection due to its accuracy and safety.
OBJECTIVE: This review aims to evaluate the 13C-UBT diagnostic accuracy studies conducted among Asian population and validate its use for the Asian population.
METHODS: Original articles were systematically searched in PubMed, Scopus, and Google Scholar using the PICOS strategy by applying relevant keywords. Only studies published in English and conducted in Asia were included. Our search returned 276 articles. After assessment, 11 articles which answered our research question and met the criteria set for systematic review and meta-analysis were accepted. A total of 15 study protocols were extracted from the 11 accepted articles.
FINDINGS: Majority of the studies were conducted in Hong Kong (six), followed by Taiwan (five), Japan (two), and one each in Singapore and Israel. All studies had used histology as part of its gold standard of reference. All but one study was performed on adult populations. The summary estimate for sensitivity was 97% (95% CI: 96, 98%), and specificity was 96% (95% CI: 95, 97%), with significant heterogeneity between studies. Adjusting for the dose (50 mg) and breath sample collection time (20 minutes) had improved both accuracy estimates and significantly reduced heterogeneity.
CONCLUSION: This review supports the test-and-treat strategy for H. pylori infection management. Prevalence and cost-effectiveness studies are mandatory for health authorities to adopt this strategy into national policy.

Matched MeSH terms: Urea/analysis*
Cellulose hydrogel development from unbleached oil palm biomass pulps for dermal drug delivery

Wong LC, Poh JH, Tan WT, Khor BK, Murugaiyah V, Leh CP, et al.

Int J Biol Macromol, 2023 Jan 01;224:483-495.
PMID: 36273545 DOI: 10.1016/j.ijbiomac.2022.10.138

Hydrogels are an attractive platform for drug delivery to the skin. Current cellulose hydrogel developments commonly focus on readily available bleached woody cellulose. Considering the detrimental environmental impacts of bleaching reagents, unbleached non-woody biomass was proposed as an alternative. Herein, this study aims to develop hydrogel from native cellulose extracted from oil palm empty fruit bunches for dermal drug delivery with an emphasis on evaluating the effect of alkali solvent compositions on hydrogel formation. Unbleached dissolving pulps were solubilized in alkali solvents containing sodium hydroxide (NaOH) (6-8%w/v) and urea (4-6%w/v) before crosslinking. Hydrogels were loaded with ibuprofen for skin permeation studies. Light brownish hydrogels formed are aesthetically acceptable and biodegradable with low cytotoxicity. NaOH content has a dominant role over urea where thinner and deformable crosslinked network walls in a porous hydrogel structure are associated with high NaOH content. Synergistic effects (cellulose solubility: 94 %; swelling ratio: ~2800 %) were observed at 7%w/v NaOH and 4%w/v urea with low toxicity. Most hydrogels showed >80 % of ibuprofen permeated into the skin and this increased with the swelling ratio of hydrogels. Unbleached cellulose pulps have excellent potential for hydrogel fabrication with outstanding physicomechanical properties for dermal drug delivery.

Matched MeSH terms: Urea/chemistry
Association between serum uric acid levels with essential hypertension and its metabolic variables in Hospital Universiti Sains Malaysia

Zulkarnain M, Wan Zain WMS, Najib MY, Aniza MJ

Med J Malaysia, 2024 Jul;79(4):457-463.
PMID: 39086344

INTRODUCTION: Hyperuricaemia is common in essential hypertension with varying results in different populations. This study sought to ascertain the association between serum uric acid levels and essential hypertension in Hospital Universiti Sains Malaysia (HUSM).
MATERIALS AND METHODS: A case-control study design involving 132 subjects (88 subjects of hypertension patients for case group and 44 subjects for control group) aged 18 to 40 years old of both genders was conducted at HUSM primary care clinic and physician clinic from May 2020 to May 2021. Blood samples were collected from each of the case and control subjects and analysed for serum uric acid, urea, creatinine, total cholesterol, triglycerides, LDL and HDL on chemical analyser Architect c8000. The data were analysed by using SPSS Statistics 26.0 version.
RESULTS: The proportion of subjects with hyperuricaemia in the case group was 48.9%. A significant difference in the uric acid levels between the case group (390.64±92.65μmol/L) and control group (352.09±86.07μmol/L), (p<0.05) was observed. There was no significant difference in the serum uric acid mean ± SD based on the duration of hypertension (<5 years and ≥5 years), (p=0.331) and stages of hypertension (p>0.05). In case group, significant correlations were established between uric acid and triglycerides (r=0.255, p<0.05), uric acid and HDL (r= -0.223, p<0.05), uric acid and urea (r=0.299, p<0.05), uric acid and creatinine (r=0.486, p<0.01). No correlation among uric acid and total cholesterol levels (p>0.05), uric acid and LDL (p>0.05). Serum uric acid was a vital variable in developing hypertension (p<0.05) but not when adapted for age and body mass index (BMI) (p>0.05).
CONCLUSION: Serum uric acid was significantly elevated in essential hypertension. The significant associations were established between uric acid and triglycerides, HDL, urea and creatinine in essential hypertension. Serum uric acid was a vital variable to develop hypertension, but the association was weakened by other co-founders as age and BMI. A large-scale population-based study is required to truly conclude the association between serum uric acid levels and essential hypertension in our population.

Matched MeSH terms: Urea/blood
Surface modification of cellulose nanomaterial for urea biosensor application

Wan Elina Faradilla Wan Khalid, Lee YH, Mohamad Nasir Mat Arip

Sains Malaysiana, 2018;47:941-949.

Cellulose nanomaterial with rod-like structure and highly crystalline order, usually formed by elimination of the amorphous region from cellulose during acid hydrolysis. Cellulose nanomaterial with the property of biocompatibility and nontoxicity can be used for enzyme immobilization. In this work, urease enzyme was used as a model enzyme to study the surface modification of cellulose nanomaterial and its potential for biosensor application. The cellulose nanocrystal (CNC) surface was modified using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation to introduce the carboxyl group at C6 primary alcohol. The success of enzyme immobilization and surface modification was confirmed using chemical tests and measured using UV-Visible spectrophotometer. The immobilization strategy was then applied for biosensor application for urea detection. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used for electroanalytical characterization of the urea biosensor.

Matched MeSH terms: Urea; Urease
Fulltext Controlled Release Fertilizers: A Review on Coating Materials and Mechanism of Release

Lawrencia D, Wong SK, Low DYS, Goh BH, Goh JK, Ruktanonchai UR, et al.

Plants (Basel), 2021 Jan 26;10(2).
PMID: 33530608 DOI: 10.3390/plants10020238

Rising world population is expected to increase the demand for nitrogen fertilizers to improve crop yield and ensure food security. With existing challenges on low nutrient use efficiency (NUE) of urea and its environmental concerns, controlled release fertilizers (CRFs) have become a potential solution by formulating them to synchronize nutrient release according to the requirement of plants. However, the most significant challenge that persists is the "tailing" effect, which reduces the economic benefits in terms of maximum fertilizer utilization. High materials cost is also a significant obstacle restraining the widespread application of CRF in agriculture. The first part of this review covers issues related to the application of conventional fertilizer and CRFs in general. In the subsequent sections, different raw materials utilized to form CRFs, focusing on inorganic and organic materials and synthetic and natural polymers alongside their physical and chemical preparation methods, are compared. Important factors affecting rate of release, mechanism of release and mathematical modelling approaches to predict nutrient release are also discussed. This review aims to provide a better overview of the developments regarding CRFs in the past ten years, and trends are identified and analyzed to provide an insight for future works in the field of agriculture.

Matched MeSH terms: Urea
Fulltext Effect of home bleaching agents on the hardness and surface roughness of resin composites

Farahiyah Mohamad Taib, Zuryati Ab Ghani, Dasmawati Mohamad

Archives of Orofacial Sciences, 2013;8(1):34-40.
MyJurnal

Ten percent carbamide peroxide is an effective, safe home bleaching agent. Higher concentrations
are more effective, but there are mixed reports on their hardness and surface roughness effects on resin composites. To evaluate the effect of home bleaching agents; Opalescence Now 10% carbamide peroxide (Ultradent Products, USA) and Perfect Bleach 17% carbamide peroxide (Voco,
Germany) on the surface hardness of microhybrid resin composites; Filtek Z250 (3M ESPE, USA) and Point 4 (Kerr, USA) and their surface roughness of selected treatment. Thirty specimens were prepared using acrylic moulds (4mm diameter x2mm thick). N=5 controls placed in distilled water for 14 days.N=5 treated with Opalescence, and n=5 treated with Perfect Bleach for 2 hours every day for 14 days. Surface hardness was tested using Vickers hardness tester FV-7 (Future Tech Corp, Japan). Data analyzed with Mann-Whitney test with (P

Matched MeSH terms: Urea
Synthesis, antioxidant activity and bioinformatics studies of L-3-hydroxytyrosine templated N-alkyl/aryl substituted urea/thioureas

Kollu U, Avula VKR, Vallela S, Pasupuleti VR, Zyryanov GV, Neelam YS, et al.

Bioorg Chem, 2021 06;111:104837.
PMID: 33812281 DOI: 10.1016/j.bioorg.2021.104837

A new series of urea/thiourea derivatives have been efficiently synthesized from the reaction of L-3-hydroxytyrosine with selective isocyanates/isothiocyanates and characterized by Infra-red, proton & carbon-13 nuclear magnetic resonance spectral and mass spectrometry studies. All the synthesized compounds have been screened for their antioxidant activity by 1,1-diphenyl1-2-picrylhydrazyl radical assay, ferric reducing antioxidant power assay and also studied their molecular docking interaction profiles against 1N8Q and 3NRZ enzymatic proteins. The in vitro antioxidant activity has further supported by quantitative structure activity relationship, absorption, distribution, metabolism, and excretion & toxicity studies, bioactivity studies & enzyme inhibition assay and identified that they were potentially bound to ASP490 & ASP361 aminoacid residue in chain A of 1N8Q protein and GLN1194 aminoacid residue in chain L of 3NRZ protein and are responsible for potential antioxidant activity. It is proved that urea derivatives linked with 4-fluoro & 4-nitro and thiourea derivatives linked with 3-chloro & 4-fluoro have exhibited promising antioxidant activity. In eventual synthesized compounds have been identified as potential blood-brain barrier penetrable compounds and proficient central nervous system active neuro-protective antioxidant agents as they have envisaged as easily penetrable to blood-brain barrier thresholds, a neuroprotective property.

Matched MeSH terms: Urea/analogs & derivatives; Urea/pharmacology*; Urea/chemistry
Nutrient balancing for phytoremediation enhancement of urea manufacturing raw wastewater

Yavari S, Malakahmad A, Sapari NB, Yavari S, Khan E

J Environ Manage, 2017 Nov 01;202(Pt 1):225-231.
PMID: 28735207 DOI: 10.1016/j.jenvman.2017.07.030

Application of urea manufacturing wastewater to teak (Tectona grandis) trees, a fast growing tropical timber plants, is an environmentally-friendly and cost-effective alternative for treatment of nitrogen-rich wastewater. However, the plant growth is strongly limited by lack of phosphorus (P) and potassium (K) elements when the plants are irrigated with wastewater containing high concentration of nitrogen (N). A greenhouse experiment was conducted to optimize the efficiency of teak-based remediation systems in terms of nutrient balance. Twelve test solutions consisted of 4 levels of P (95, 190, 570, 1140 mgL-1) and 3 levels of K (95, 190, 570 mgL-1) with a constant level of N (190 mgL-1) were applied to teak seedlings every four days during the study period. Evapotranspiration rate, nutrient removal percentage, leaf surface area, dry weight and nutrient contents of experimental plants were determined and compared with those grown in control solution containing only N (N:P:K = 1:0:0). Teak seedlings grown in units with 1:0.5:1 N:P:K ratio were highly effective at nutrient removal upto 47%, 48% and 49% for N, P and K, respectively. Removal efficiency of teak plants grown in other experimental units decreased with increasing P and K concentrations in test solutions. The lowest nutrient removal and plant growth were recorded in units with 1:6:0.5 N:P:K ratio which received the highest ratio of P to K. The findings indicated that teak seedlings functioned effectively as phytoremediation plants for N-rich wastewater treatment when they were being supplied with proper concentrations of P and K.

Matched MeSH terms: Urea
Fulltext Exploring pineapple peel hydrolysate as a sustainable carbon source for xylitol production

Nasoha NZ, Luthfi AAI, Roslan MF, Hariz HB, Bukhari NA, Manaf SFA

Sci Rep, 2023 Nov 07;13(1):19284.
PMID: 37935748 DOI: 10.1038/s41598-023-46061-8

This study explores utilizing pineapple peel (PP) hydrolysate as a promising carbon source for xylitol production, covering scopes from the pre-treatment to the fermentation process. The highest xylose concentration achieved was around 20 g/L via mild acid hydrolysis (5% nitric acid, 105 °C, 20-min residence time) with a solid loading of 10%. Two sets fermentability experiments were carried out of varying pH levels in synthetic media that includes acetic acid as the main inhibitors and hydrolysate supplemented with diverse nitrogen source. The results revealed that pH 7 exhibited the highest xylitol production, yielding 0.35 g/g. Furthermore, urea was found to be a highly promising and cost-effective substitute for yeast extract, as it yielded a comparable xylitol production of 0.31 g/g with marginal difference of only 0.01 g/g compared to yeast extract further highlights the viability of urea as the preferred option for reducing xylitol production cost. The absence of a significant difference between the synthetic media and hydrolysate, with only a marginal variance of 0.35 to 0.32 g/g, implies that acetic acid is indeed the primary constraint in xylitol production using PP hydrolysate. The study sheds light on PP biomass's potential for xylitol production, aligning economic benefits with environmental sustainability and waste management.

Matched MeSH terms: Urea
Improving protein production of indigenous microalga Chlorella vulgaris FSP-E by photobioreactor design and cultivation strategies

Chen CY, Lee PJ, Tan CH, Lo YC, Huang CC, Show PL, et al.

Biotechnol J, 2015 Jun;10(6):905-14.
PMID: 25865941 DOI: 10.1002/biot.201400594

Fish meal is currently the major protein source for commercial aquaculture feed. Due to its unstable supply and increasing price, fish meal is becoming more expensive and its availability is expected to face significant challenges in the near future. Therefore, feasible alternatives to fish meal are urgently required. Microalgae have been recognized as the most promising candidates to replace fish meal because the protein composition of microalgae is similar to fish meal and the supply of microalgae-based proteins is sustainable. In this study, an indigenous microalga (Chlorella vulgaris FSP-E) with high protein content was selected, and its feasibility as an aquaculture protein source was explored. An innovative photobioreactor (PBR) utilizing cold cathode fluorescent lamps as an internal light source was designed to cultivate the FSP-E strain for protein production. This PBR could achieve a maximum biomass and protein productivity of 699 and 365 mg/L/day, respectively, under an optimum urea and iron concentration of 12.4 mM and 90 μM, respectively. In addition, amino acid analysis of the microalgal protein showed that up to 70% of the proteins in this microalgal strain consist of indispensable amino acids. Thus, C. vulgaris FSP-E appears to be a viable alternative protein source for the aquaculture industry.

Matched MeSH terms: Urea/metabolism; Urea/chemistry
Fulltext Dielectric response of nitrogen in soil amended with chicken litter biochar and urea under Oryza sativa L. cultivation

Maru A, Ahmed OH, Primus WC, Jeffary AV

Sci Rep, 2021 06 15;11(1):12545.
PMID: 34131184 DOI: 10.1038/s41598-021-91426-6

Unbalanced utilization of nitrogen (N) rice not economically viable neither is this practice environmental friendly. Co-application of biochar and urea could reduce the unbalanced use of this N fertilizer in rice cultivation. Thus, a field study was carried out to: (i) determine the effects of chicken litter biochar and urea fertilization on N concentration in soil solution of a cultivated rice (MR219) using dielectric measurement at a low frequency and (ii) correlate soil dielectric conductivity with rice grain yield at maturity. Dielectric response of the soil samples at 20, 40, 55, and 75 days after transplanting were determined using an inductance-capacitance-resistance meter HIOKI 3522-50 LCR HiTESTER. Selected soil chemical properties and yield were determined using standard procedures. The dielectric conductivity and permittivity of the soil samples measured before transplanting the rice seedlings were higher than those for the soil samples after transplanting. This was due to the inherent nitrogen of the chicken litter biochar and the low nitrogen uptake at the transplanting stage. The soil N response increased with increasing measurement frequency and N concentration. The permittivity of the soil samples was inversely proportional to frequency but directly proportional to N concentration in the soil solution. The estimated contents of N in the soil using the dielectric conductivity approach at 1000 Hz decreased with increasing days of fertilization and the results were similar to those of soil NH4+ determined using chemical analysis. The conductivity measured within 1000 Hz and 100,000 Hz correlated positively with the rice grain yield suggesting that nitrogen concentration of the soil can be used to estimate grain yield of the cultivated rice plants.

Matched MeSH terms: Urea/pharmacology; Urea/chemistry
Hunig's base catalyzed synthesis of new 1-(2,3-dihydro-1H-inden-1-yl)-3-aryl urea/thiourea derivatives as potent antioxidants and 2HCK enzyme growth inhibitors

Lachhi Reddy V, Avula VKR, Zyryanov GV, Vallela S, Anireddy JS, Pasupuleti VR, et al.

Bioorg Chem, 2020 01;95:103558.
PMID: 31911311 DOI: 10.1016/j.bioorg.2019.103558

A series of 1-(2,3-dihydro-1H-indan-1-yl)-3-aryl urea/thiourea derivatives (4a-j) have been synthesized from the reaction of 2,3-dihydro-1H-inden-1-amine (2) with various aryl isocyanates/isothiocyanates (3a-j) by using N,N-DIPEA base (Hunig's base) catalyst in THF at reflux conditions. All of them are structurally confirmed by spectral (IR, 1H &13C NMR and MASS) and elemental analysis and screened for their in-vitro antioxidant activity against DPPH and NO free radicals and found that compounds 4b, 4i, 4h &4g are potential antioxidants. The obtained in vitro results were compared with the molecular docking, ADMET, QSAR and bioactivity study results performed for them and identified that the recorded in silico binding affinities were observed in good correlation with the in vitro antioxidant results. The Molecular docking analysis had unveiled the strong hydrogen bonding interactions of synthesized ligands with ARG 160 residue of protein tyrosine kinase (2HCK) enzyme and plays an effective role in its inhibition. Toxicology studies have assessed the potential risks of 4a-j and inferred that all of them were in the limits of potential drugs. The conformational analysis of 4a-j inferred that the urea/thiourea spacer linking 2,3-dihydro-1H-inden-1-amino and substituted aryl units has facilitated all these molecules to effectively bind with ARG 160 amino acid residue present on the α-helix of the protein tyrosine kinase (2HCK) enzyme specifically on chain A of hemopoetic cell kinase. Collectively this study has established a relationship between the antioxidant potentiality and ligands binding with ARG 160 amino acid residue of chain A of 2HCK enzyme to inhibit its growth as well as proliferation of reactive oxygen species in vivo.

Matched MeSH terms: Thiourea/pharmacology; Thiourea/chemistry*; Urea/pharmacology; Urea/chemistry*

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