Diversity of the Intestinal Bacteria of Cattle Fed on Diets with Different Doses of Gelatinized Starch-Urea

Gelatinized starch-urea (Starea, SU) is an effective and economical source of urea for ruminants. Here we assessed the influence of dietary supplementation with gelatinized starch-urea on the diversity of intestinal bacteria in finishing cattle. Fifty steers were randomly allotted to five treatments with diets supplemented with different doses of Starea [0 % (SU0), 8 % (SU8), 16 % (SU16), 24 % (SU24), and 32 % (SU32) of urea-N in total nitrogen]. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes was used to examine the effect of dietary supplementation of Starea on intestinal bacterial flora. Shannon-Weaver and Simpson diversity indices consistently showed the lowest bacterial diversity in the SU0 treatment. Increasing doses of Starea increased the diversity up to SU24 after which, diversity decreased. Cluster analysis of 16S rRNA gene DGGE profiles indicates that the intestinal bacterial communities associated with cattle that were not supplemented with Starea in feed differed in composition and structure from those supplemented with Starea. The amount of Starea supplemented in cattle diets influenced the abundance of several key species affiliated with Lachnospiraceae, Ruminococcaceae, Peptostreptococcaceae, Comamonadaceae and Moraxellaceae. These results suggest that Starea influences the composition and structure of intestinal bacteria which may play a role in promoting ruminant health and production performance.

Effect of urea on growth and microcystins production of Microcystis aeruginosa

The effects of urea on the growth and toxin content of Microcystis aeruginosa isolated from Dianchi Lake in China were investigated. Experiments were carried out in lab using (15)N isotopic technique to characterize urea-N biosynthesis to microcystins. High urea concentration (3.6 mmol-N L(-1)) would restrict the growth of M.aeruginosa and the production of microcystin-LR, while low urea concentration (0.4-1.4 mmol-N L(-1)) would promote the growth of M.aeruginosa and the production of microcystin-LR. The (15)N labeling experiment further demonstrated that there existed selectivity when M.aeruginosa assimilated urea to form its structure. The majority of M.aeruginosa assimilated 1 urea molecule at first which was biosynthesized into the Ala or Leu residue. On day 18, The m/z=1004 parent ion assimilated 9 (15)N except that the Mdha residue did not assimilate any urea-(15)N. The results give deeper insight to the biosynthesis of urea into microcystins.

Impact of urea and guanidine hydrochloride

Urea and guanidine hydrochloride (GuHCl) have different influence on surface properties of lysozyme solutions. The increase of GuHCl concentration leads to noticeable changes of kinetic dependencies of the dynamic surface elasticity and ellipsometric angles while the main effect of urea reduces to a strong drop of the static surface tension. The difference between the effects of these two denaturants on the surface properties of other investigated globular proteins is significantly weaker and is mainly a consequence of a different extent of the globule unfolding in the surface layer at equal concentrations of the denaturants. The obtained results for lysozyme solutions are connected with the strongly different denaturation mechanisms under the influence of urea and GuHCl. In the former case the protein preserves its globular structure in the adsorption layer at high urea concentrations (up to 9M) but without tightly packed interior of the globule and with a dynamic tertiary structure (molten globule state). On the contrary, the increase of GuHCl concentration leads to partial destruction of the protein tertiary structure in the surface layer, although this effect is not as strong as in the case of previously studied bovine serum albumin and β-lactoglobulin.

Scalable and DiI-compatible optical clearance of the mammalian brain

Efficient optical clearance is fundamental for whole brain imaging. In particular, clearance of the brain without membrane damage is required for the imaging of lipophilic tracer-labeled neural tracts. Relying on an ascending gradient of fructose solutions, SeeDB can achieve sufficient transparency of the mouse brain while ensuring that the plasma membrane remains intact. However, it is challenging to extend this method to larger mammalian brains due to the extremely high viscosity of the saturated fructose solution. Here we report a SeeDB-derived optical clearing method, termed FRUIT, which utilizes a cocktail of fructose and urea. As demonstrated in the adult mouse brain, combination of these two highly water-soluble clearing agents exerts a synergistic effect on clearance. More importantly, the final FRUIT solution has low viscosity so as to produce transparency of the whole adult rabbit brain via arterial perfusion, which is impossible to achieve with a saturated fructose solution. In addition to good compatibility with enhanced yellow fluorescent protein, the cocktail also preserves the fluorescence of the lipophilic tracer DiI. This work provides a volume-independent optical clearing method which retains the advantages of SeeDB, particularly compatibility with lipophilic tracers.

Development of an avidity assay for detection of recent HIV infections

HIV avidity can measure the incidence of recent infections within the population. The aim of this study was to evaluate an HIV avidity assay, initially from a clinically defined group of patients and then apply the assay to a prospective study to determine the false recency rate and mean duration of recency for the assay. The assay is a commercial ELISA modified with 7 M urea. The validation of the assay used plasma from patients split into Group 1 (recently infected N=25) and group 2 (established infection N=301). The prospective study tested 178 newly diagnosed HIV patients for avidity. A total of 326 retrospective samples of known HIV status were collected and tested. The initial evaluation gave a sensitivity 100% (CI 86.16-100%) and specificity of 98.65% (95% CI 97.05-99.78%). The prospective study incorporating 178 newly diagnosed patients found 22 patients with low avidity. Follow-up samples obtained from low avidity patients determined the estimated mean duration of recency to be between 3 and 4 months with a false recency rate of 0.89% (CI: 0.24-2.3%). The assay described here compares well in sensitivity, specificity and false recency rate with that of other published avidity assays.

Na,K-ATPase structure/function relationships probed by the denaturant urea

Urea interacts with the Na,K-ATPase, leading to reversible as well as irreversible inhibition of the hydrolytic activity. The enzyme purified from shark rectal glands is more sensitive to urea than Na,K-ATPase purified from pig kidney. An immediate and reversible inhibition under steady-state conditions of hydrolytic activity at 37°C is demonstrated for the three reactions studied: the overall Na,K-ATPase activity, the Na-ATPase activity observed in the absence of K+ as well as the K+-dependent phosphatase reaction (K-pNPPase) seen in the absence of Na+. Half-maximal inhibition is seen with about 1M urea for shark enzyme and about 2M urea for pig enzyme. In the presence of substrates there is also an irreversible inhibition in addition to the reversible process, and we show that ATP protects against the irreversible inhibition for both the Na,K-ATPase and Na-ATPase reaction, whereas the substrate paranitrophenylphosphate leads to a slight increase in the rate of irreversible inhibition of the K-pNPPase. The rate of the irreversible inactivation in the absence of substrates is much more rapid for shark enzyme than for pig enzyme. The larger number of potentially urea-sensitive hydrogen bonds in shark enzyme compared to pig enzyme suggests that interference with the extensive hydrogen bonding network might account for the higher urea sensitivity of shark enzyme. The reversible inactivation is interpreted in terms of domain interactions and domain accessibilities using as templates the available crystal structures of Na,K-ATPase. It is suggested that a few interdomain hydrogen bonds are those mainly affected by urea during reversible inactivation.

Plasma Levels of Uric Acid, Urea and Creatinine in Diabetics Who Visit the Clinical Analysis Laboratory (CAn-Lab) at Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

INTRODUCTION

Diabetes mellitus is one of the most common metabolic diseases worldwide. This metabolic disorder contributes greatly to the significant proportion of the burden of renal damage and dysfunction. The aim of the study was to investigate the renal function of the diabetic patients who visit the Clinical Analysis Laboratory (CAn-Lab) at the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana.

MATERIALS AND METHODS

Demographic data as well as medical history were obtained through the administration of a questionnaire. Anthro-pometric measurements were taken and blood samples were analysed for glucose, uric acid, urea and creatinine. Data collected were analysed using SPSS version 16.0.

RESULTS

A total of 34 diabetic patients, aged from 40-77 y were recruited, 22 (64.7%) of them were males with mean age of 57.40 ± 11.8 y (±SD), while 12 (35.3%) were females with mean age of 58.17 ± 7.47 y. There was a statistically significant difference between the mean duration of the disease, as the females had longer duration, 12.50 ± 6.95 y, as compared to 7.32 ± 4.48 y in males (p=0.033). The mean plasma creatinine level in the females was 84.17 ± 54.73 μmol/l. In the diabetic population, there was a positive correlation between age and plasma creatinine level, (r=0.375, p=0.029). In the female diabetics, there was a positive correlation between fasting blood sugar (FBS) and the measured metabolic end products (r>0.5, p<0.05), a positive correlation between body mass index (BMI) and uric acid (r=0.576, p=0.005) and a positive correlation between BMI and FBS (r= 0.625, p= 0.030).

CONCLUSION

Our results on the parameters measured; show that the diabetic population was experiencing mild kidney dysfunction, compared to non-diabetic controls.

Urea-induced ROS cause endothelial dysfunction in chronic renal failure

OBJECTIVE

The pathogenic events responsible for accelerated atherosclerosis in patients with chronic renal failure (CRF) are poorly understood. Here we investigate the hypothesis that concentrations of urea associated with CRF and increased ROS production in adipocytes might also increase ROS production directly in arterial endothelial cells, causing the same pathophysiologic changes seen with hyperglycemia.

METHODS

Primary cultures of human aortic endothelial cells (HAEC) were exposed to 20mM urea for 48 h. C57BL/6J wild-type mice underwent 5/6 nephrectomy or a sham operation. Randomized groups of 5/6 nephrectomized mice and their controls were also injected i.p. with a SOD/catalase mimetic (MnTBAP) for 15 days starting immediately after the final surgical procedure.

RESULTS

Urea at concentrations seen in CRF induced mitochondrial ROS production in cultured HAEC. Urea-induced ROS caused the activation of endothelial pro-inflammatory pathways through the inhibition of GAPDH, including increased protein kinase C isoforms activity, increased hexosamine pathway activity, and accumulation of intracellular AGEs (advanced glycation end products). Urea-induced ROS directly inactivated the anti-atherosclerosis enzyme PGI2 synthase and also caused ER stress. Normalization of mitochondrial ROS production prevented each of these effects of urea. In uremic mice, treatment with MnTBAP prevented aortic oxidative stress, PGI2 synthase activity reduction and increased expression of the pro-inflammatory proteins TNFα, IL-6, VCAM1, Endoglin, and MCP-1.

CONCLUSIONS

Taken together, these data show that urea itself, at levels common in patients with CRF, causes endothelial dysfunction and activation of proatherogenic pathways.

'Dos and don'ts' in the management of hyponatremia

INTRODUCTION AND OBJECTIVE

The management of hyponatremia has evolved in recent years, particularly with the introduction of tolvaptan for hyponatremia secondary to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This commentary presents a summary of recent international recommendations in the form of a series of didactic 'dos and don'ts', in order to provide concise, practical guidance for practising clinicians focused on the investigation and management of euvolemic hyponatremia (SIADH).

RESEARCH METHODS

A multidisciplinary group of international experts reviewed existing guidelines and the evidence cited within to summarize the recommendations in a practical method for use in clinical practice.

RECOMMENDATIONS

The 'dos and don'ts' are presented under topic headings that include diagnosis and diagnostic tests, specific causes, correction of acute hyponatremia, correction rates for chronic hyponatremia, management of SIADH including fluid restriction, hypertonic saline and pharmacological strategies, and management of overcorrection. Within each topic, the authors summarize the published recommendations on managing hyponatremia and the use of specific agents for the treatment of SIADH.

CONCLUSION

Practising clinicians can use these 'dos and don'ts' to provide clear, up-to-date guidance on how to manage hyponatremia and the use of tolvaptan in SIADH.

Adaptations of a deep sea scavenger: high ammonia tolerance and active NH₄⁺ excretion by the Pacific hagfish (Eptatretus stoutii)

The Pacific hagfish (Eptatretus stoutii) has an exceptional ability to both withstand and recover from exposure to high external ammonia (HEA). This tolerance is likely due to the feeding behavior of this scavenger, which feeds on intermittent food falls of carrion (e.g. fish, large marine mammals) during which time it may be exposed to high concentrations of total ammonia (T(Amm)=NH3+NH4(+)) while burrowed inside the decomposing carcass. Here we exposed hagfish to 20 mmol L(-1) T(Amm) for periods of up to 48 h and then let animals recover in ammonia-free seawater. During the 48 h HEA exposure period, plasma T(Amm) increased 100-fold to over 5000 μmol L(-1) while ammonia excretion (J(amm)) was transiently inhibited. This increase in plasma T(Amm) resulted from NH3 influx down massive inwardly directed ΔP(NH3) gradients, which also led to a short-lived metabolic alkalosis. Plasma [T(Amm)] stabilized after 24-48 h, possibly through a reduction in NH3 permeability across the body surface, which lowered NH3 influx. Ammonia balance was subsequently maintained through the re-establishment of J(amm) against an inwardly directed ΔP(NH3). Calculations of the Nernst potential for ammonia strongly indicated that J(amm) was also taking place against a large inwardly directed NH4(+) electrochemical gradient. Recovery from HEA in ammonia-free water was characterized by a large ammonia washout, and the restoration of plasma TAmm concentrations to near control concentrations. Ammonia clearance was also accompanied by a residual metabolic acidosis, which likely offset the ammonia-induced metabolic alkalosis seen in the early stages of HEA exposure. We conclude that restoration of J(amm) by the Pacific hagfish during ammonia exposure likely involves secondary active transport of NH4(+), possibly mediated by Na(+)/NH4(+) (H(+)) exchange.

A self-polishing platinum ring voltammetric sensor and its application to complex media

A self-polishing voltammetric sensor was recently developed and has been applied to samples of urea, milk and sewage water. The polishing device continuously grinds a platinum ring electrode, offering a reproducible and clean electrode surface. Principal component analysis (PCA) and partial least squares (PLS) techniques were applied to interpret the data and to build prediction models. In an evaluation of samples with different urea concentrations, the grinding step allows for repeatable measurements, similar to those after electrochemical cleaning. Furthermore, for the determination of sewage water concentrations in drinking water and for the evaluation of different fat contents in milk samples, the polishing eliminates sensor drift produced by electrode fouling. The results show that the application of a self-polishing unit offers a promising tool for electrochemical studies of difficult analytes and complex media.

Guanidine hydrochloride and urea effects upon thermal stability of Glossoscolex paulistus hemoglobin (HbGp)

Glossoscolex paulistus hemoglobin (HbGp) has a molecular mass of 3600kDa. It belongs to the hexagonal bilayer hemoglobin class, which consists of highly cooperative respiratory macromolecules found in mollusks and annelids. The present work focusses on oxy-HbGp thermal stability, in the presence of urea and guanidine hydrochloride (GuHCl), monitored by several techniques. Initially, dynamic light scattering data show that the presence of GuHCl induces the protein oligomeric dissociation, followed by a significant 11-fold increase in the hydrodynamic diameter (DH) values, due to the formation of protein aggregates in solution. In contrast, urea promotes the HbGp oligomeric dissociation, followed by unfolding process at high temperatures, without aggregation. Circular dichroism data show that unfolding critical temperature (Tc) of oxy-HbGp decreases from 57°C, at 0.0 mol/L of the denaturant, to 45°C, in the presence of 3.5 mol/L of urea, suggesting the reduction of HbGp oligomeric stability. Moreover, differential scanning calorimetry results show that at lower GuHCl concentrations, some thermal stabilization of the hemoglobin is observed, whereas at higher concentrations, the reduction of stability takes place. Besides, HbGp is more stable in the presence of urea when compared with the guanidine effect, as deduced from the differences in the concentration range of denaturants.

Cystatin C as an early marker of acute kidney injury in septic shock

OBJECTIVE

To describe the utility of determining plasma cystatinC concentrations in the diagnosis of acute incident kidney injury in septic shock.

PATIENTS AND METHODS

Prospective series of 50 patients with septic shock and plasma creatinine levels <2mg/dL hospitalized in an intensive care unit. Clinical and laboratory follow-ups were conducted, with measurements of cystatinC, urea and plasma creatinine levels from the diagnosis of septic shock to 5days later. The severity of the septic shock was assessed with the RIFLE scale.

RESULTS

Twenty patients (40%) developed acute kidney injury: 8 (16%) were categorized as RIFLE-R, 5 (10%) as RIFLE-I and 7 (14%) as RIFLE-F. All patients categorized as RIFLE-F required extracorporeal renal clearance. Eighteen (36%) patients died, 8 (20%) of whom had developed acute kidney injury in their evolution. There was poor correlation between plasma creatinine and cystatin C levels (r=.501; P=.001), which disappeared upon reaching any degree of renal impairment on the RIFLE scale. CystatinC levels increased earlier and were better able to identify patients who would develop serious renal function impairment (RIFLE-F) than creatinine and urea levels. The initial cystatinC levels were related to mortality at 30days (OR=1.16; 95%CI: 03-.85).

CONCLUSIONS

For patients who developed acute septic kidney injury, the plasma cystatinC levels increased before the classical markers of renal function. CystatinC also constitutes a severity biomarker that correlates with progression to RIFLE-F, the need for extrarenal clearance and, ultimately, mortality. This precocity could be useful for starting measures that prevent the progression of renal dysfunction.

Effect of ammonium sulfate and urea on PCDD/F formation from active carbon and possible mechanism of inhibition

The effect of ammonium sulfate ((NH4)2SO4) and urea (CO(NH2)2) on polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) formation from active carbon was investigated in this study. Both additives could significantly inhibit PCDD/F formation, and PCDD/F (TEQ) generation was reduced to 98.5% (98%) or 64.5% (77.2%) after 5% (NH4)2SO4 or CO(NH2)2 was added into model ash, respectively. The inhibition efficiency of PCDDs was higher than the value of PCDFs, however, the reduction of PCDD/F yield was mainly from PCDFs decreasing. In addition, the solid-phase products were reduced more than the gas-phase compounds by inhibitors. By the measurement of chlorine emission in the phase of ion (Cl[Cl(-)]) and molecule gas (Cl[Cl2]), it was observed that both Cl[Cl(-)] and Cl[Cl2] were reduced after inhibitors were added into ash. Cl[Cl2] was reduced to 51.0% by urea addition, which was supposed as one possible mechanism of PCDD/F inhibition.

2-Aminopyrimidin-4(1H)-one as the novel bioisostere of urea: discovery of novel and potent CXCR2 antagonists

2-Aminopyrimidin-4(1H)-one was proposed as the novel bioisostere of urea. Bioisosteric replacement of the reported urea series of the CXCR2 antagonists with 2-aminopyrimidin-4(1H)-ones led to the discovery of the novel and potent CXCR2 antagonist 3e. 2-Aminopyrimidin-4(1H)-one derivative 3e demonstrated a good developability profile (reasonable solubility and high permeability) and superior chemical stability especially in simulated gastric fluid (SGF) compared with ureas.

Dissecting the effect of chemical additives on the enzymatic hydrolysis of pretreated wheat straw

Chemical additives were examined for ability to increase the enzymatic hydrolysis of thermo-acidically pretreated wheat straw by Trichoderma reesei cellulase at 50 °C. Semi-empirical descriptors derived from the hydrolysis time courses were applied to compare influence of these additives on lignocellulose bioconversion on a kinetic level, presenting a novel view on their mechanism of action. Focus was on rate retardation during hydrolysis, substrate conversion and enzyme adsorption. PEG 8000 enabled a reduction of enzyme loading by 50% while retaining the same conversion of 67% after 24h. For the first time, a beneficial effect of urea is reported, increasing the final substrate conversion after 48 h by 16%. The cationic surfactant cetyl-trimethylammonium bromide (CTAB) enhanced the hydrolysis rate at extended reaction time (rlim) by 34% and reduced reaction time by 28%. A combination of PEG 8000 and urea increased sugar release more than additives used individually.

Whey-reduced weight gain is associated with a temporary growth reduction in young mice fed a high-fat diet

Whey protein consumption reportedly alleviates parameters of the metabolic syndrome. Here, we investigated the effects of whey protein isolate (whey) in young mice fed a high-fat diet. We hypothesized that whey as the sole protein source reduced early weight gain associated with retarded growth and decreased concentration of insulin-like growth factor-1. Moreover, we hypothesized that these changes were explained by increased nitrogen loss via elevated urea production and/or increased energy expenditure. Male 5-week-old C57BL/6 mice were fed high-fat diets with the protein source being either whey, casein or a combination of both for 5 weeks. After 1, 3 or 5 weeks, respectively, the mice were subjected to a meal challenge with measurements of blood and urinary urea before and 1 and 3 h after eating a weighed meal of their respective diets. In a subset of mice, energy expenditure was measured by indirect calorimetry during the first week of dietary intervention. Observed exclusively during the first week of intervention, whey significantly reduced body length (P<.01) and weight gain (P<.001) correlating positively with plasma concentrations of insulin-like growth factor-1. The combination diet displayed intermediate results indicating an interactive effect. Urea production, urea cycle activity, food intake and energy expenditure were unaffected by protein source. In conclusion, whey decreased growth-related parameters exclusively during the first week of dietary intervention. The early effect of whey could not be explained by food intake, energy expenditure, urea production or urea cycle activity but was correlated with plasma levels of insulin-like growth factor-1.

Anthropogenic loads and biogeochemical role of urea in the Gulf of Trieste

In order to assess the role of urea in the Gulf of Trieste, oceanographic data collected from 2002 to 2011 were analyzed together with ancillary ambient information and compared to past studies. The recent levels of urea found in these coastal waters (median = 1.1 μM N, maximum value = 19.7 μM N) are often high and similar to those reported in the early 1980s. A preliminary estimate of the external inputs indicated that this enrichment in urea is mainly due to emissions from urban sewage systems, whereas the contributions of rivers and atmospheric deposition are scarce. As a consequence, urea appears to be a reliable tracer of the diffusion of wastewaters in the coastal marine environment, more specific and sensitive than other nutrients, with a behavior that also reflects the technology of the treatment plants. The stability of urea levels over the last three decades suggests that the upgrade of wastewater treatment technologies was probably balanced by the concomitant increase of the anthropogenic pressure in the area (477,000 to 1,300,000 inhabitant equivalent). Budget estimates on the gulf-wide scale indicate that urea (177-530 t N) is not negligible compared to dissolved inorganic nitrogen (409-919 t N) and that it can constitute up to 56% of the nitrogen available for plankton growth. A large accumulation of urea can occur during summer periods characterized by stable weather conditions and weak circulation, whereas a biologically mediated degradation to ammonium is observed in autumn in concomitance to a strong shift of the marine ecosystem toward heterotrophic conditions. These processes, together with a potential competition between phytoplankton and bacteria for the utilization of this nitrogen form, suggest that the biogeochemical role of urea should be better investigated in mid-latitude coastal zones subjected to highly variable ambient conditions and to overloads of this compound.

Influences of pH, urea and metal ions on the interaction of sinomenine with Lysozyme by steady state fluorescence spectroscopy

The interaction between sinomenine and Lysozyme (Lys) in aqueous solution has been systemically investigated by fluorescence spectroscopic techniques at pH 7.4. The quenching rate constants and binding constants calculated indicated the static quenching mechanism and medium binding force. The effect of sinomenine on the conformation of Lys was analyzed using synchronous fluorescence and three-dimensional (3D) fluorescence. In addition, influence of pH on the binding of sinomenine to Lys was investigated and the binding ability of the drug to Lys deceased under other pH conditions (pH 9.0, 3.5, and 1.9) as compared with that at pH 7.4. As compared with the binding ability of sinomenine to native Lys, that of sinomenine to denatured Lys deceases dramatically. Furthermore, the effect of many metal ions on the binding constant of sinomenine with Lys was investigated.

Effect of thyroid on lipid profile and renal function: an observational study from tertiary care centre of tribal region of bastar

Background:

Thyroid hormone is a key substance in normal homeostasis, having variable influence on cell metabolism on different organs. Very little is known about the prevalence of thyroid disorders from our region.

Aim:

This study was conducted with the aim of finding prevalence of thyroid disorder and relation of thyroid hormone with renal function and cholesterol metabolism.

Subjects and Methods:

A total of 96 ambulatory patients were taken for study. Serum samples were collected and evaluated for triiodothyronine, thyroxine, thyroid-stimulating hormone, urea, creatinine, total cholesterol, triglyceride (TG), low density lipoprotein (LDL), very low density lipoprotein and high density lipoprotein (HDL). Analysis of variance and t-test were used to find a significant difference among the groups.

Results:

Prevalance of thyroid disorder among suspected patients was 64/96 (66%), of which 36/64 (56.3%) were hypothyroid and 28/64 (43.8%) were hyperthyroid. No relation was found with renal function, but cholesterol was found high (>250 mg/dl) among hypothyroid patients and significant increase in TG, LDL levels and significant decrease was in HDL.

Conclusion:

Thyroid disorder is high among subjects with hypercholesterolemia. This underscores the need to evaluate for thyroid disorder in hypercholesterolemic patients and vice-versa.

The optimization of biomass and lipid yields of Chlorella sorokiniana when using wastewater supplemented with different nitrogen sources

The potential of nitrogen sources supplementing domestic wastewater for the cultivation of microalgae was assessed. Urea, potassium nitrate, sodium nitrate and ammonium nitrate were evaluated for their effect on cultivation and lipid production of Chlorella sorokiniana. Urea showed the highest biomass yield of 0.220 g L(-1) and was selected for further experimentation. Urea concentrations (0-10 g L(-1)) were assessed for their effect on growth and microalgal physiology using pulse amplitude modulated fluorometry. A concentration of 1.5 g L(-1) urea produced 0.218 g L(-1) biomass and 61.52% lipid by relative fluorescence. Physiological stress was evident by the decrease in relative Electron Transport Rate from 10.45 to 6.77 and quantum efficiency of photosystem II charge separation from 0.665 to 0.131. Gas chromatography analysis revealed that C16:0, C18:0, C18:1, C18:2 and C18:3 were the major fatty acids produced by C. sorokiniana. Urea proved to be an effective nitrogen supplement for cultivation of C. sorokiniana in wastewater.

Management of irrigation frequency and nitrogen fertilization to mitigate GHG and NO emissions from drip-fertigated crops

Drip irrigation combined with split application of fertilizer nitrogen (N) dissolved in the irrigation water (i.e. drip fertigation) is commonly considered best management practice for water and nutrient efficiency. As a consequence, its use is becoming widespread. Some of the main factors (water-filled pore space, NH4(+) and NO3(-)) regulating the emissions of greenhouse gases (i.e. N2O, CO2 and CH4) and NO from agroecosystems can easily be manipulated by drip fertigation without yield penalties. In this study, we tested management options to reduce these emissions in a field experiment with a melon (Cucumis melo L.) crop. Treatments included drip irrigation frequency (weekly/daily) and type of N fertilizer (urea/calcium nitrate) applied by fertigation. Crop yield, environmental parameters, soil mineral N concentrations and fluxes of N2O, NO, CH4 and CO2 were measured during 85 days. Fertigation with urea instead of calcium nitrate increased N2O and NO emissions by a factor of 2.4 and 2.9, respectively (P<0.005). Daily irrigation reduced NO emissions by 42% (P<0.005) but increased CO2 emissions by 21% (P<0.05) compared with weekly irrigation. We found no relation between irrigation frequency and N2O emissions. Based on yield-scaled Global Warming Potential as well as NO cumulative emissions, we conclude that weekly fertigation with a NO3(-)-based fertilizer is the best option to combine agronomic productivity with environmental sustainability. Our study shows that adequate management of drip fertigation, while contributing to the attainment of water and food security, may provide an opportunity for climate change mitigation.

New ureas containing glycosyl and diphenylphosphinyl scaffolds: synthesis and the first attempts to use them in asymmetric synthesis

Chiral ureas containing glycosyl and diphenylphosphinyl scaffolds were found to be an effective organocatalyst. They were synthesised in high yields by a one-pot tandem Staudinger/aza-Wittig coupling reaction. The first attempts of using them in asymmetric synthesis are presented. Yields of the Morita-Baylis-Hillman reaction were moderate with an enantiomeric excess of up to 80%.

A comparative study on the aggregating effects of guanidine thiocyanate, guanidine hydrochloride and urea on lysozyme aggregation

Protein aggregation and its subsequent deposition in different tissues culminate in a diverse range of diseases collectively known as amyloidoses. Aggregation of hen or human lysozyme depends on certain conditions, namely acidic pH or the presence of additives. In the present study, the effects on the aggregation of hen egg-white lysozyme via incubation in concentrated solutions of three different chaotropic agents namely guanidine thiocyanate, guanidine hydrochloride and urea were investigated. Here we used three different methods for the detection of the aggregates, thioflavin T fluorescence, circular dichroism spectroscopy and atomic force microscopy. Our results showed that upon incubation with different concentrations (0.5, 1.0, 2.0, 3.0, 4.0, 5.0M) of the chemical denaturants, lysozyme was aggregated at low concentrations of guanidine thiocyanate (1.0 and 2.0M) and at high concentrations of guanidine hydrochloride (4 and 5M), although no fibril formation was detected. In the case of urea, no aggregation was observed at any concentration.

A one-pot three-component synthesis of 4,6-diarylpyrimidin-2(1H)-ones (DAPMs) using atomized sodium in THF under sonic condition

A simple and an efficient procedure for the synthesis of 4,6-diarylpyrimidin-2(1H)-ones using atomized sodium/THF via a one-pot three-component Biginelli-like cyclocondensation of an aldehyde, a methyl ketone and urea under ultrasonic condition is developed. The method is mild and inexpensive; yields are high and the reactions go to completion within 10-15 min.

Long-Term Regulation of Renal Urea Transporters during Antidiuresis

To produce a concentrated urine, the renal medulla needs hypertonicity for the reabsorption of free water from collecting duct. The single effect that increases interstitial tonicity in the outer medulla is the active NaCl reabsorption in the thick ascending limb, while the single effect in the inner medulla is the passive efflux of NaCl through the thin ascending limb. The passive mechanism in the inner medulla requires high interstitial urea concentration. Two main groups of urea transporters (UT-A, UT-B) are present in the kidney, which maintains the high concentration of urea in the deepest portion of the inner medulla by intra-renal urea recycling. Recent studies suggest that UT-A1 in the terminal inner medullary collecting duct is up-regulated when urine or inner medullary interstitial urea is depleted in order to enhance the reabsorption of urea, while UT-A2 in the descending thin limb of loops of Henle and UT-B in the descending vasa recta are increased when outer medullary interstitial urea concentration is high, in order to prevent the loss of urea from the medulla to the systemic circulation, thereby increasing intra-renal urea recycling. This review will summarize the functions of the renal urea transporters in urine concentration mechanism and the recent knowledge about their long-term regulation.

The Saga of Two Centuries of Urea: Nontoxic Toxin or Vice Versa?

In the early 1700s, a substance ultimately identified as urea was reported for the first time in urine. About a century later, in 1828, synthesis of this organic compound was achieved, thus giving rise to modern organic chemistry. In parallel, physicians showed that urine comes from the kidneys and contains large amounts of urea, which is produced outside of the kidneys, establishing the humoral approach of renal physiology. Urea was the first uremic retention solute to be identified and it has been used as a marker of renal disease ever since. However, progress in the knowledge of urea metabolism has shown that it is susceptible to many extrarenal variations and, therefore, it cannot be a reliable marker of renal function. It reflects protein intake in the stable patient and has been used to assess nutrition and dialysis efficacy in renal patients. Although it has been studied for almost 200 years, its toxicity has been largely debated. An indirect toxicity occurring through carbamylation of lysine residues is now well established and some evidence from recent work also supports direct toxicity of urea, offering additional rationale for interventional prevention of uremic complications.

Time course of the acute response of the North Pacific spiny dogfish shark (Squalus suckleyi) to low salinity

Dogfish are considered stenohaline sharks but are known to briefly enter estuaries. The acute response of North Pacific spiny dogfish (Squalus suckleyi) to lowered salinity was tested by exposing sharks to 21‰ salinity for 48 h. Temporal trends in blood pH, plasma osmolality, CO2, HCO3(-), Na(+), Cl(-), K(+), and urea concentrations, and in the rates of urea efflux and O2 consumption, were quantified. The rate of O2 consumption exhibited cyclic variation and was significantly depressed by lowered salinity. After 9 h, plasma [Cl(-)] stabilized at 9% below initial levels, while plasma [Na(+)] decreased by more than 20% within the first 12 h. Plasma [urea] dropped by 15% between 4 and 6 h, and continued to decrease. The rate of urea efflux increased over time, peaking after 36 h at 72% above the initial rate. Free-swimming sharks subjected to the same salinity challenge survived over 96 h and differed from cannulated sharks with respect to patterns of Na(+) and urea homeostasis. This high-resolution study reveals that dogfish exposed to 21‰ salinity can maintain homeostasis of Cl(-) and pH, but Na(+) and urea continue to be lost, likely accounting for the inability of the dogfish to fully acclimate to reduced salinity.

Reinvestigation of growth of thiourea urea zinc sulfate crystal

Reinvestigation of the growth of thiourea urea zinc sulfate crystal is reported. Aqueous reaction of thiourea, urea and zinc sulfate in 1:1:1 mol ratio results in the formation of the well known [Zn(tu)3(SO4)] (1) (tu=thiourea) crystal and not the 'so called' novel semiorganic nonlinear optical thiourea urea zinc sulfate (2) crystal, as claimed by Redrothu Hanumantha Rao, S. Kalainathan, Spectroscopic investigation, nucleation, growth, optical, thermal and second harmonic studies of novel semi-organic nonlinear optical crystal - Thiourea urea zinc sulfate, Spectrochim. Acta A97 (2012) 456-463. In this work, we demonstrate the usefulness of elemental analytical data, infrared and NMR spectra and X-ray powder pattern, for accurate product characterization.

A Novel Approach using Hydrotropic Solubalization Technique for Quantitative Estimation of Entacapone in Bulk Drug and Dosage Form

PURPOSE

Analysis of drug utilized the organic solvent which are costlier, toxic and causing environment pollution. Hydrotropic solution may be a proper choice to preclude the use of organic solvents so that a simple, accurate, novel, safe and precise method has been developed for estimation of poorly water soluble drug Entacapone (Water Solubility-7.97e-(02) g/l).

METHODS

Solubility of entacapone is increased by using 8M Urea as hydrotropic agent. There was more than 67 fold solubility enhanced in hydrotropic solution as compare with distilled water. The entacapone (ENT) shows the maximum absorbance at 378 nm. At this wavelength hydrotropic agent and other tablet excipients do not shows any significant interference in the spectrophotometric assay.

RESULTS

The developed method was found to be linear in the range of 4-20 μg/ml with correlation coefficient (r(2)) of 0.9998. The mean percent label claims of tablets of ENT in tablet dosage form estimated by the proposed method were found to be 99.17±0.63. The developed methods were validated according to ICH guidelines and values of accuracy, precision and other statistical analysis were found to be in good accordance with the prescribed values.

CONCLUSION

As hydrotropic agent used in the proposed method so this method is Ecofriendly and it can be used in routine quantitative analysis of drug in bulk drug and dosage form in industries.

Formation of ethyl carbamate and changes during fermentation and storage of yellow rice wine

Ethyl carbamate (EC) was analyzed during yellow rice wine production and storage. EC increased slowly during fermentation and rapidly after frying and sterilization. Less amount of EC was formed when cooled rapidly to 30 °C than when cooled naturally. High temperature and long storage time increased EC formation. After 400 days storage, EC increased from 74.0 to 84.2, 131.8 and 509.4 μg/kg at 4 °C, room temperature and 37 °C, respectively, and there was significantly difference between the fried wine and the wine on sale from 2011 (p<0.01). Urea increased during yellow rice wine fermentation and was above 20 mg/kg after the wine was fried; urea contributed to EC formation when the fried wine was cooled slowly. These results indicate that it is necessary for industry to optimize the wine frying conditions, such as temperature, time and cooling process in order to decrease EC formation.

Rat hepatocyte culture model of macrosteatosis: effect of macrosteatosis induction and reversal on viability and liver-specific function

BACKGROUND & AIMS

A common cause of liver donor ineligibility is macrosteatosis. Recovery of such livers could enhance donor availability. Living donor studies have shown diet-induced reduction of macrosteatosis enables transplantation. However, cadaveric liver macrosteatotic reduction must be performed ex vivo within hours. Towards this goal, we investigated the effect of accelerated macrosteatosis reduction on hepatocyte viability and function using a novel system of macrosteatotic hepatocytes.

METHODS

Hepatocytes isolated from lean Zucker rats were cultured in a collagen sandwich, incubated for 6 days in fatty acid-supplemented medium to induce steatosis, and then switched for 2 days to medium supplemented with lipid metabolism promoting agents. Intracellular lipid droplet size distribution and triglyceride, viability, albumin and urea secretion, and bile canalicular function were measured.

RESULTS

Fatty acid-supplemented medium induced microsteatosis in 3 days and macrosteatosis in 6 days, the latter evidenced by large lipid droplets dislocating the nucleus to the cell periphery. Macrosteatosis significantly impaired all functions tested. Macrosteatosis decreased upon returning hepatocytes to standard medium, and the rate of decrease was 4-fold faster with supplemented agents, yielding 80% reduction in 2 days. Viability of macrosteatosis reduced hepatocytes was similar to control lean cells. Accelerated macrosteatotic reduction led to faster recovery of urea secretion and bile canalicular function, but not of albumin secretion.

CONCLUSIONS

Macrosteatosis reversibly decreases hepatocyte function and supplementary agents accelerate macrosteatosis reduction and some functional restoration with no effect on viability. This in vitro model may be useful to screen agents for macrosteatotic reduction in livers before transplantation.

Environmental analysis of sunflower production with different forms of mineral nitrogen fertilizers

Environmental profiles of mineral nitrogen fertilizers were used to evaluate the environmental disturbances related to their use in cultivation systems in Europe. Since the production of mineral fertilizers requires a large amount of energy, the present study of bioenergy systems is relevant in order to achieve crop yields less dependent on fossil fuels and to reduce the environmental impact due to fertilization. In this study, the suitability of the LCA methodology to analyze the environmental impact of sunflower cultivation systems with different forms of mineral nitrogen fertilizers urea and ammonium nitrate was investigated. Effects on climate change were estimated by the use of Ecoinvent 2.2 database default value for soil N2O emission factor (1%) and local emission data (0.8%) of mineral nitrogen applied to soils. LCA analysis showed a higher impact on environmental categories (human health and ecosystem quality) for the system in which urea was used as a nitrogen source. Use of urea fertilizer showed a higher impact on resource consumption due to fossil fuel consumption. Use of mineral nitrogen fertilizers showed a higher environmental burden than other inputs required for sunflower cultivation systems under study. Urea and ammonium nitrate showed, respectively, a 7.8% and 4.9% reduced impact of N2O as greenhouse gas by using direct field data of soil N2O emission factor compared to the default soil emission factor of 2006 IPCC Guidelines. Use of ammonium nitrate as mineral nitrogen fertilizer in sunflower cultivation would have a lower impact on environmental categories considered. Further environmental analysis of available technologies for fertilizer production might be also evaluated in order to reduce the environmental impacts of each fertilizer.

Impact of urease inhibitor on ammonia and nitrous oxide emissions from temperate pasture soil cores receiving urea fertilizer and cattle urine

New Zealand's intensively grazed pastures receive the majority of nitrogen (N) input in the form of urea, which is the major constituent of animal urine and the most common form of mineral N in inorganic N fertilizers. In soil, urea is rapidly hydrolyzed to ammonium (NH4(+)) ions, a part of which may be lost as ammonia (NH3) and subsequently as nitrous oxide (N2O), which is a greenhouse gas. Two glasshouse experiments were conducted to study the effect of a urease inhibitor (UI), N-(n-butyl) thiophosphoric triamide (NBPT), commercially named Agrotain, applied with urine and urea on urea hydrolysis and NH3 and N2O emissions. Treatments included the commercially available products Sustain Yellow (urea+Agrotain+4% sulfur coating), Sustain Green (urea+Agrotain) and urea, and cattle urine (476 kg N ha(-1)) with and without Agrotain applied to intact soil cores of a fine sandy loam soil. The addition of Agrotain to urine and urea (i.e. Sustain Green) reduced NH3 emission by 22% to 47%, respectively. Agrotain was also effective in reducing N2O emissions from urine and Sustain Green by 62% and 48%, respectively. The reduction in N2O emissions varied with the type and amount of N applied and plant N uptake. Plant N uptake was significantly higher in the soil cores receiving Agrotain with urea than urea alone, but the slight increase in dry matter yield was non-significant. Hence, urease inhibitor reduced N losses through NH3 and N2O emissions, thereby increasing plant uptake of N.

Effectiveness of urea in enhancing the extractability of 2,4,6-trinitrotoluene from chemically variant soils

One of the major challenges in developing an effective phytoremediation technology for 2,4,6-trinitrotoluene (TNT) contaminated soils is limited plant uptake resulting from low solubility of TNT. The effectiveness of urea as a solubilizing agent in increasing plant uptake of TNT in hydroponic systems has been documented. Our preliminary greenhouse experiments using urea were also very promising, but further characterization of the performance of urea in highly-complex soil-solution was necessary. The present study investigated the natural retention capacity of four chemically variant soils and optimized the factors influencing the effectiveness of urea in enhancing TNT solubility in the soil solutions. Results show that the extent of TNT sorption and desorption varies with the soil properties, and is mainly dependent on soil organic matter (SOM) content. Hysteretic desorption of TNT in all tested soils suggests irreversible sorption of TNT and indicates the need of using an extractant to increase the release of TNT in soil solutions. Urea significantly (p<0.0001) enhanced TNT extraction from all soils, by increasing its solubility at the solid/liquid interface. Soil organic matter content and urea application rates showed significant effects, whereas pH did not exert any significant effect on urea catalysis of TNT extraction from soil. The optimum urea application rates (125 or 350 mg kg(-1)) for maximizing TNT extraction were within the limits set by the agronomic fertilizer-N rates used for major agricultural crops. The data obtained from this batch study will facilitate the optimization of a chemically-catalyzed phytoremediation model for cleaning up TNT-contaminated soils.

Inhibition of protein carbamylation in urea solution using ammonium-containing buffers

Urea solution is one of the most commonly employed protein denaturants for protease digestion in proteomic studies. However, it has long been recognized that urea solution can cause carbamylation at the N termini of proteins/peptides and at the side chain amino groups of lysine and arginine residues. Protein/peptide carbamylation blocks protease digestion and affects protein identification and quantification in mass spectrometry analysis by blocking peptide amino groups from isotopic/isobaric labeling and changing peptide charge states, retention times, and masses. In addition, protein carbamylation during sample preparation makes it difficult to study in vivo protein carbamylation. In this study, we compared the peptide carbamylation in urea solutions of different buffers and found that ammonium-containing buffers were the most effective buffers to inhibit protein carbamylation in urea solution. The possible mechanism of carbamylation inhibition by ammonium-containing buffers is discussed, and a revised procedure for the protease digestion of proteins in urea and ammonium-containing buffers was developed to facilitate its application in proteomic research.

Effects of sucrose and urea on soy hull pectic polysaccharide gel induced by D-glucono-1,5-lactone

Gelation properties of pectic polysaccharide extracted with ammonium oxalate from soybean hulls assisted by microwave were seldom studied. Water mobility in soy hull pectic polysaccharide (SHPP) was firstly studied by low field NMR. D-Glucono-1,5-lactone (GDL) and sucrose both could decrease spin-spin relaxation times (T2) of SHPP solutions which indicated the SHPP network formed. Rheological analysis conformed that SHPP gel was formed induced by GDL and enhanced by sucrose. Urea can increase T2 and collapse the network of SHPP. TGA was used to draw the profiles of water desorption from SHPP solutions or gels, during heating at a controlled rate. It was found that sucrose increased the bound water content and urea acted a conversely role. Hydrogen bond is the main force to maintain SHPP gel network.

Employment of colorimetric enzyme assay for monitoring expression and solubility of GST fusion proteins targeted to inclusion bodies

High levels of recombinant protein expression can lead to the formation of insoluble inclusion bodies. These complex aggregates are commonly solubilized in strong denaturants, such as 6-8M urea, although, if possible, solubilization under milder conditions could facilitate subsequent refolding and purification of bioactive proteins. Commercially available GST-tag assays are designed for quantitative measurement of GST activity under native conditions. GST fusion proteins accumulated in inclusion bodies are considered to be undetectable by such assays. In this work, solubilization of recombinantly produced proteins was performed in 4M urea. The activity of rGST was assayed in 2M urea and it was shown that rGST preserves 85% of its activity under such denaturing conditions. A colorimetric GST activity assay with 1-chloro-2, 4-dinitrobenzene (CDNB) was examined for use in rapid detection of expression targeted to inclusion bodies and for the identification of inclusion body proteins which can be solubilized in low concentrations of chaotropic agents. Applicability of the assay was evaluated by tracking protein expression of two GST-fused allergens of biopharmaceutical value in E. coli, GST-Der p 2 and GST-Mus a 5, both targeted to inclusion bodies.

Recent developments in glycosyl urea synthesis

The area of sugar urea derivatives has received considerable attention in recent years because of the unique structural properties and activities that these compounds display. The urea-linkage at the anomeric center is a robust alternative to the naturally occurring O- and N-glycosidic linkages of oligosaccharides and glycoconjugates, and the natural products that have been identified to contain these structures show remarkable biological activity. While methods for installing the β-urea-linkage at the anomeric center have been around for decades, the first synthesis of α-urea glycosides has been much more recent. In either case, the selective synthesis of glycosyl ureas can be quite challenging, and a mixture of α- and β-isomers will often result. This paper will provide a comprehensive review of the synthetic approaches to α- and β-urea glycosides and examine the structure and activity of the natural products and their analogues that have been identified to contain them.

Airway drug pharmacokinetics via analysis of exhaled breath condensate

Although the airway surface is the anatomic target for many lung disease therapies, measuring drug concentrations and activities on these surfaces poses considerable challenges. We tested whether mass spectrometric analysis of exhaled breath condensate (EBC) could be utilized to non-invasively measure airway drug pharmacokinetics and predicted pharmacological activities. Mass spectrometric methods were developed to detect a novel epithelial sodium channel blocker (GS-9411/P-680), two metabolites, a chemically related internal standard, plus naturally occurring solutes including urea as a dilution marker. These methods were then applied to EBC and serum collected from four (Floridian) sheep before, during and after inhalation of nebulized GS-9411/P-680. Electrolyte content of EBC and serum was also assessed as a potential pharmacodynamic marker of drug activity. Airway surface concentrations of drug, metabolites, and electrolytes were calculated from EBC measures using EBC:serum urea based dilution factors. GS-9411/P-680 and its metabolites were quantifiable in the sheep EBC, with peak airway concentrations between 1.9 and 3.4 μM measured 1 h after inhalation. In serum, only Metabolite #1 was quantifiable, with peak concentrations ∼60-fold lower than those in the airway (45 nM at 1 h). EBC electrolyte concentrations suggested a pharmacological effect; but this effect was not statistical significant. Analysis of EBC collected during an inhalation drug study provided a method for quantification of airway drug and metabolites via mass spectrometry. Application of this methodology could provide an important tool in development and testing of drugs for airways diseases.

Is it possible to screen for milk or whey protein adulteration with melamine, urea and ammonium sulphate, combining Kjeldahl and classical spectrophotometric methods?

The Kjeldahl method and four classic spectrophotometric methods (Biuret, Lowry, Bradford and Markwell) were applied to evaluate the protein content of samples of UHT whole milk deliberately adulterated with melamine, ammonium sulphate or urea, which can be used to defraud milk protein and whey contents. Compared with the Kjeldahl method, the response of the spectrophotometric methods was unaffected by the addition of the nitrogen compounds to milk or whey. The methods of Bradford and Markwell were most robust and did not exhibit interference subject to composition. However, the simultaneous interpretation of results obtained using these methods with those obtained using the Kjeldahl method indicated the addition of nitrogen-rich compounds to milk and/or whey. Therefore, this work suggests a combination of results of Kjeldahl and spectrophotometric methods should be used to screen for milk adulteration by these compounds.

[Predictive variables for mortality in elderly patients hospitalized due to heart failure with preserved ejection fraction]

BACKGROUND AND OBJECTIVES

The prevalence of heart failure (HF) increases with age. Even though the mortality of patients ≥ 80 years of age with HF and preserved left ventricle ejection fraction (LVEF) is very high, the predictor variables are not well-known. The main goal of this study was to evaluate the mortality predictor factors in this subgroup of the elderly population.

PATIENTS AND METHODS

An observational and prospective study of patients hospitalized due to HF with preserved LVEF has been conducted. The demographic, clinical, functional and analytic factors were evaluated when the patients were admitted with special attention to the co-morbidities. The primary endpoint was the total mortality in the subgroup of patients ≥ 80 years of age after a year of follow-up. The predictor variables were studied by means of a multivariate Cox regression model.

RESULTS

From a total of 218 patients with an average age of 75.6 (±8.7) years of age, 75 patients (34.4%) were ≥ 80 years. The mortality rate of patients ≥ 80 years of age totaled 42.7%, in relation to 26.6% for the lower age group (log-rank<.001). After a multivariate analysis using the Cox regression model in patients ≥ 80, the serum urea levels above the average (hazard ratio [HR] 3.93; 95% confidence interval [95% CI] 1.58-9.75; P = .003), the age (HR 1.17; 95% CI 1.07-1.28; P<.001), the hyponatremia (HR 3.19; 95% CI 1.51-6.74; P = .002) and a lower score on the Barthel index (BI) (HR 1.016; 95% CI 1.002-1.031; P = .034) were independent mortality predictors after an one-year follow-up.

CONCLUSIONS

Serum urea levels, age, hyponatremia and a low BI score could be proposed as independent mortality predictors in patients ≥ 80 of age hospitalized for HF with preserved LVEF.

Analysis of the stability of urea in dried blood spots collected and stored on filter paper

The ability to use dry blood spots (DBSs) on filter paper for the analysis of urea levels could be an important diagnostic tool for areas that have limited access to laboratory facilities. We developed a method for the extraction and quantification of urea from DBSs that were stored on 3M Whatman filter paper and investigated the effect of long-term storage on the level of urea in DBSs. DBSs of 4.5 mm in diameter were used for our assay, and we determined the urea levels in blood using a commercially available enzymatic kit (UV GLDH-method; Randox laboratories Ltd., UK). The DBSs on filter discs were stored at 4℃ or at 37℃ for 120 days. The mean intra- and inter-assay coefficient of variance for our method of urea extraction from dried blood was 4.2% and 6.3%, respectively. We collected 75 fresh blood samples and compared the urea content of each fresh sample with the urea content of DBSs taken from corresponding fresh blood samples. Regression analysis reported a regression coefficient (r) value of 0.97 and a recovery of urea from dried spots was 102.2%. Urea concentrations in DBSs were stable for up to 120 and 90 days when stored at 4℃ and 37℃, respectively. Our results show that urea can be stored and quantitatively recovered from small volumes of blood that was collected on filter paper.

Diagnosis of premature rupture of membranes by assessment of urea and creatinine in vaginal washing fluid

BACKGROUND

Rupture of fetal membranes can occur at any gestational age. Premature rupture of membranes (PROM) means rupture of fetal membranes before the onset of labor.

OBJECTIVE

The purpose of this study was to evaluate and compare the reliability of the vaginal washing fluid urea and creatinine for the diagnosis of PROM and to determine cut-off values.

MATERIALS AND METHODS

A total of 179 pregnant women were recruited. All patients underwent different examinations. These included nitrazine paper test, fern test, amniotic fluid pooling, vaginal washing fluid urea and creatinine sampling. The one group consisted of 126 pregnant women between 14 and 41 weeks of gestation with the complaint of vaginal fluid leakage. Patients who had positive pooling, nitrazine paper test and fern test were considered as confirmed PROM group (group 1). On the other side, patients with pooling (-) and/or nitrazine paper test (-) and/or fern test (-) were taken as suspected unconfirmed PROM cases (group 2). The control group consisted of 53 pregnant women between 14 and 41 weeks of gestation without any complaint or complication. Weconducted one-way ANOVA test on the urea and creatinine measures and post-hoc comparison test. Cut-off value was determined by receiver operating characteristic (ROC) curve.

RESULTS

Vaginal fluid concentrations of urea and creatinine were significantly different between the three groups (p<0.001). The sensitivity, specificity, positive and negative predictive values and accuracy were all 100% in detecting premature rupture of membranes by evaluation of vaginal fluid creatinine concentration with a cut-off value of 0.45 mg/dl, respectively.

CONCLUSION

This study demonstrates that of two markers investigated creatinine has the higher diagnostic power.

Urea Output by L3 Teladorsagia circumcincta and some Properties of Two Urea Producing Enzymes

BACKGROUND

Like several other parasites, Teladorsagia circumcincta secretes or excretes urea, but neither the rate of efflux nor the possible metabolic sources of the urea has been considered.

METHODS

Parasites were maintained by passage through sheep. Urea efflux was measured using phenol/hypochlorite after treatment with urea aminohydrolase. The kinetics of creatine amidinohydrolase and arginine amidinohydrolase were characterised by coupling the reactions with urea aminohydrolase and glutamate dehydrogenase.

RESULTS

Infective L3 T. circumcincta secreted or excreted urea at 25% of the rate of NH3/NH4 (+). The rate of urea efflux was about 84 pmol h(-1) (10(3) larvae)(-1) over 4 hours, corresponding to about 11 nmol h(-1) mg(-1) protein. We could not detect urea aminohydrolase activity, but urea production by both creatine amidinohydrolase and arginine amidinohydrolase could be detected. The apparent K m and V max of creatine amidinohydrolase were 1.1 mM and 48 nmol h(-1) mg(-1) protein, respectively, and the activity was greatest at pH 8. The apparent K m and V max of arginine amidinohydrolase were 0.7 mM and 62 nmol h(-1) mg(-1) protein, respectively, and the activity was greatest at pH 7.9.

CONCLUSION

The activity of creatine amidinohydrolase and arginine amidinohydrolase was sufficient to account for the rate of urea secretion or excretion.

Comparative effect of olive oil and fish oil supplementation in combating gentamicin induced nephrotoxicity in rats

The present study is related to the comparative effects of fish oil and olive oil supplementation on gentamicin induced nephrotoxicity in rats. Three treatment groups (Pretrement, Co-treatment and post treatment) were chosen for the study. Nephrotoxicity in rats was induced by intraperitonial administration of gentamicin (80 mg/kg/d) for 3,5,7,10,& 12 consecutive days. The animals were sacrificed 12 hrs after last treatment in each group. The maximum nephrotoxicity was developed on 10 days treatment of gentamicin. For each group a control group was taken without any oil or gentamicin treatment. Beneficial effects of oils were evidenced by reduced serum urea and creatinine concentrations in the group receiving oils compared to the non oil treatment animals receiving gentamicin only. Further, the changed values of alkaline phosphatase and acid phosphatase activity retumed to normal in kidney and liver tissue homogenates after fish and olive oil treatment. In this study, it was found that co-treatment of fish and olive oil is more effective antagonist of gentamicin induced nephrotoxicity. However fish oil was found to be more effective. Hypercholesteromia associated with gentamicin induced nephrotoxicity is also lowered by oil supplementations. The beneficial effects of these oils are due to counteracting effect of the biochemical alterations induced by the drug.

A test strip for the estimation of urea in serum

We have developed a biostrip for determination of urea in serum. The test strip is based on enzymatic assay where urease has been immobilized on the chromatographic paper along with chromogen, phenol red. The chromogen is easily soluble in water and does not require other components for the color change. Serum urea reacts with urease and water to liberate ammonia and carbon dioxide. The liberated ammonia changes the pH of the reaction medium, which is monitored by the chromogen phenol red. A single step working reagent strip has been developed and the reaction is completed within 50 seconds at room temperature. With this test strip urea concentration is measured in serum as low as 0.15 g/L. The speed and convenience of determining urea in serum by this strip instantly makes it well suited for individuals, physicians and emergency centres.

Creatinine, urea, uric acid, water and electrolytes renal handling in the healthy oldest old

Renal physiology in the healthy oldest old has the following characteristics, in comparison with the renal physiology in the young: a reduced creatinine clearance, tubular pattern of creatinine back-filtration, preserved proximal tubule sodium reabsorption and uric acid secretion, reduced sodium reabsorption in the thick ascending loop of Henle, reduced free water clearance, increased urea excretion, presence of medulla hypotonicity, reduced urinary dilution and concentration capabilities, and finally a reduced collecting tubules response to furosemide which expresses a reduced potassium excretion in this segment due to a sort of aldosterone resistance. All physiological changes of the aged kidney are the same in both genders.

The role of different sugars, amino acids and few other substances in chemotaxis directed motility of helicobacter pylori

OBJECTIVES

Motility plays a major role in pathogenicity of Helicobacter pylori, yet there is scarce data regarding its chemotactic behaviour. The present study was designed to investigate the chemotactic responses of local isolates of H. pylori towards various sugars, amino acids, as well as some other chemical substances.

MATERIALS AND METHODS

Chemotaxis was assayed by a modified Adler's method. We used solutions of sugars, amino acids as well as urea, sodium chloride, sodium and potassium bicarbonate, sodium deoxycholate and keratin at 10 mM concentrations.

RESULTS

Despite some small differences, tested H. pylori isolates generally had a positive chemotaxis towards the tested sugars (P< 0.05). Among amino acids, phenylalanine, aspartic acid, glutamic acid, isoleucine and leucine showed a positive chemotaxis (P< 0.05) ; however, tyrosine showed negative chemotaxis (repellent) (P< 0.15). Urea, sodium chloride, sodium and potassium bicarbonate showed to be attractants (P< 0.05), but sodium deoxycholate was repellent (P< 0.05).

CONCLUSION

It seems that, sugars and many amino acids by their attraction for H.pylori, many amino acids, may enhance the activity of this bacterium and probably aggravate the symptoms of its infection. However, those like L-tyrosine, may possibly be employed as deterrents for H. pylori and thus can control its infections. However, we suggest that further investigations on chemotactic behaviour of many more strains of H. pylori should be carried out before a final conclusion.

Blood chemical changes and renal histological alterations induced by gentamicin in rats

Gentamicin is an effective widely used antibiotic, but the risk of nephrotoxicity and oxidative damage limit its long-term use. Hence, the current study aims to elucidate such hazardous effects. To achieve the study aim male Wistar albino rats (Rattus norvegicus) were exposed to gentamicin to investigate the resultant blood chemical changes and renal histological alterations. In comparison with control rats, gentamicin produced outstanding tubular, glomerular and interstitial alterations that included degeneration, necrosis, cytolysis and cortical tubular desquamation together with mesangial hypercellularity, endothelial cell proliferation and blood capillary congestion. Compared with control animals significant blood chemical changes (P < 0.05) including free radicals, ALT, AST, ALP, serum creatinine and serum urea were recorded in gentamicin-injected animals. The findings revealed that exposure to gentamicin can induce significant histological alterations in the kidney as well as remarkable blood chemical changes that might indicate marked renal failure.