Urea

The synthesis of a limited series of non-racemic atropisomeric 1-(2-(4methyl-2-thioxothiazol-3(2H)-yl)phenyl)-3-(hetero)aryl-(thio)ureas is described. Using NMR titration experiments monitoring the shift of the two NH of the (thio)urea and the C-5 hydrogen of the heterocycle, the binding constants for some optically pure (thio)ureas with the enantiomers of N-protected amino acid tetrabutylammonium salts were determined in CD 3 CN. The obtained enantioselectivities were modest. Contrary to what was expected on the basis of the NH acidity in thiourea versus urea group, the association constants were smaller with the thiourea than with the corresponding urea. X-ray data, DFT calculations, and NMR provided the explanation of that unexpected behavior: the urea presents a pre-organized (Z,Z) conformation suitable for a double hydrogen bond with the carboxylate anion, the thiourea presents a (Z,E) conformation, which must be reorganized in a constrained (Z,Z) conformation in the complex. An intramolecular hydrogen bond between one NH and the thiocarbonyl group of the heterocycle, which is present in the thiourea and absent in the urea, might also contribute to the smaller K ass for the thiourea. The possible implication of these observations in the field of bifunctional organocatalysis is briefly discussed.

Two experiments were conducted with growing male rats to determine the effects of 120 ppm of dietary sarsaponin (S) on nitrogen (N) metabolism when urea or protein are added to the diet. Growth, feed efficiency, N digestibility and balance, urinary N and ammonia-N (NH3-N), and cecal urease and NH3-N were measured. Growth and feed utilization were unaffected by dietary S. Adding urea or protein to the diet increased apparent N digestibility and increased urinary-N excretion. Urea did not affect N balance, whereas growth, feed utilization and N balance were maximized with 22% compared with either 16 or 28% dietary protein. Urinary NH3-N excretion was decreased by S when urea was added to the diet but was not affected when fed with increasing dietary protein. Cecal urease was decreased by S when urea was added or when the protein level was increased in the diet; effects on cecal NH3-N varied between the two experiments. Plasma urea-N was decreased by S. It is concluded that S has minor...

Objective: To evaluate the effect of enteral nutrition (EN) supplemented with L-glutamine on glycolytic parameters, inflammation, immune function, and oxidative stress in moderately ill intensive care patients with sepsis. Methods: Thirty patients received EN. Fifteen patients received EN supplemented with glutamine (30 g; GLN group) for 2 d followed by EN supplemented with calcium caseinate (30 g, CAS group), also over 2 d. The other 15 patients received EN with calcium caseinate (30 g; CAS group) for 2 d followed by EN with glutamine (30 g; GLN group), also over 2 days. One washout day with only EN was provided between every 2-d period of EN plus supplementation to all patients. Blood samples were taken before and after supplementation. Results: There were no changes in glycolytic parameters in either group. Leukocytes decreased in the two groups (from 13 650 to 11 500 in the CAS group, P ¼ 0.019; from 12.850 to 11.000 in the GLN group, P ¼ 0.046). Lymphocytes increased in the GLN group (from 954 to 1916, P < 0.0001) and were more numerous after glutamine supplementation (from 1916 to 1085, P < 0.0001, GLN versus CAS). No significant changes were observed in interleukin levels, but urea levels were higher in the GLN compared with the CAS group (50.0-47.0, P ¼ 0.030). Glutathione plasma concentrations did not differ significantly between the groups. No significant changes were observed in the plasma glutamine and glutamate concentrations. Conclusions: The EN supplemented with glutamine increased the lymphocyte count and helped to decrease lipid peroxidation but presented no effect on the antioxidant glutathione capacity and on cytokine concentrations or glycolytic parameters. .br (A. A. M. Cavalcante). 0899-9007/$ -see front matter Ó

The National Kidney Foundation and the European Renal Association recommend routine measurement of hemodialysis (HD) dose and have set standards for adequacy of treatment. We compare the results of five methods for HD dose estimation, classifying each result as adequate or inadequate on the basis of equilibrated (eq) Urea Reduction Ratio (URR eq ) ≥ 65% or Kt/V eq ≥ 1.2, to assess the accuracy of each method as a diagnostic tool. Data from 113 patients from two different dialysis units were analyzed. Equilibrated postdialysis blood urea was measured 60 min after each hemodialysis session to calculate URR eq and Kt/V eq , considered as gold standard indexes (GSI). URR and Kt/V were estimated by using the Smye formula, an artificial neural network (ANN), modified URR, the second generation Kt/V Daugirdas formula, and standard indexes based on postdialysis urea, then compared to the GSI. For URR, best estimator was ANN (error rate: ER% = 12.70), followed by modified URR (ER% = 17.46%), the Smye (ER% = 22.22), and standard URR (ER% = 23.81). For Kt/V, the Daugirdas equation and the ANN were similar (ER% = 9.52 and 11.11). The single-pool Kt/V (Kt/V sp ) ≥ 1.4 (ERA recommended) produced an ER% = 7.94 and a false positive rate (FPR%) equal to that shown by the ANN (FPR% = 3.17). According to the current threshold limits for HD dose adequacy, the ANN was a reliable and accurate tool for URR monitoring, better than the Smye and the modified URR methods. The use of the ANN urea estimation yields accurate results when used to calculate Kt/V. The Kt/V sp with an adequacy threshold of 1.4 is a superior approach for HD adequacy monitoring, suggesting that the current adequacy limits should be reviewed for both URR and Kt/V.

A total of 60 samples were collected from 35 swimming pools in Beijing, China, and the presence of Cryptosporidium and Giardia were investigated. The results showed that 16.7% and 15.0% of samples were positive for Cryptosporidium oocyst and Giardia cysts, respectively, with a mean concentration of 0.30 oocysts/10 L and 0.27 cysts/10 L. The oocysts and cysts were found to have higher rates of occurrence in August than in May. Genotyping confirmed the presence of Cryptosporidium hominis, C. parvum, and Giardia assemblages A and B, all of which were associated with human infections. The predominant species/assemblages were C. hominis and Giardia assemblage A. Analyses of the relationships between parasite oocysts/cysts, indicator bacteria, and physical-chemical parameters revealed that there was no correlation between 2 parasites and fecal bacterial indicators, whilst there was a significant correlation between protozoa and urea concentration, which indicates that urea concentration rather than fecal bacterial indicators might be an appropriate index for chlorine-resistant protozoa in swimming pools. This study provides useful information to improve the safety of swimming pool water and deduce the risk of protozoan infections.

The effects on performance, digestibility, N utilization and plasma amino acid concentrations of dietary chickpea (Cicer arietinum, var. Kabuli) seed meal, globulin proteins or buffer-insoluble residue (starch / non-starch polysaccharides (NSP)/ lignin) were studied in growing rats. Chickpea meal, defatted soybean meal, chickpea globulins and lactalbumin were each incorporated into diets as the sole source of dietary protein (100 g/kg).

Ethnopharmacological relevance: Nervilia plicata (Orchidaceae) has long been used in the antidiabetic medicinal preparations of traditional healers of Wayanad (Kerala), but recuperative potential of the plant was remained undefined. We demonstrated the regenerative potential of the plant extract on kidney affected by type 2 diabetes besides lowering blood glucose. Aim of the study: The aim of the current study was to investigate the recuperative and regenerative potential of alcoholic stem extract of Nervilia plicata on streptozotocin-nicotinamide induced type 2 diabetic models. Materials and methods: Non insulin dependent diabetes mellitus (NIDDM) was induced in overnight fasted rats by intramuscular injection (IMI) of 60 mg/kg STZ and 120 mg/kg of nicotinamide after 5 min interval. Blood glucose was assessed by a glucometer, serum urea and creatinine levels were determined by diacetylmonooxime method and Jaffe reaction respectively. Kidney sections were taken and stained with Masson's tri-dye and Periodic Acid Schiff (PAS) and examined for structural changes. Also lipid peroxidation product (LPP) levels were determined as thio barbituric acid reactive substance levels (TBARS) method. Results: On administration of 5 mg/kg of plant extract, blood glucose levels of the NIDDM rats showed 62.00 and 76.29% decrease in the blood glucose levels on day 0 and day 30 respectively. Damages caused to the kidney tissue were negligible or not seen. Serum urea and creatinine levels showed 61.49 and 70.96% decrease on day 30. LPP levels of kidney and pancreas showed 70.58 and 77.41% decrease respectively. Conclusion: These results demonstrate significant antidiabetic and regenerative potential of the Nervilia plicata, justifying the use of plant in the indigenous system of medicine. Isolation and characterisation of the compound(s) playing pivotal role in the cure would open new vistas in the therapy of type 2 diabetes.

Previous studies have shown that harp seals may drink considerable amounts of seawater. The current study was Ž undertaken to study the physiological responses to bolus administration of seawater. Adult harp seals Phoca. groenlandica were fasted without access to water for 48 h and then given 1000 or 1500 ml of seawater by a stomach tube. Changes in urine and plasma parameters were thereafter monitored for another 12᎐20 h. Urine production and urine excretion rate of Na q and Cl y increased soon after administration and reached a maximum 3᎐4 h later. Urine Ž y1. osmolality was kept rather stable and high ; 1500 mOsm kg following seawater administration, due to a drop in urine concentration of urea that was proportional to the simultaneous increase in urine concentration of NaCl. Plasma osmolality remained at approximately 340 mOsm kg y1 , while plasma concentration of urea decreased some 20᎐25% due to increased excretion of urea when seawater was ingested. Despite bolus administrations of seawater of up to ; 2% of body mass, homeostasis was maintained and no ill effects observed. It is concluded that the concentrating abilities of the kidneys of harp seals are sufficient to prevent net loss of body water following seawater ingestion. Seawater ingestion may, moreover, increase urinary osmotic space and thus serve as a mechanism to excrete additional urea produced during phase I of fasting.

Effect of the dialysis membrane on mortality of chronic hemodialysis patients. Mortality of prevalent chronic hemodialysis patients remains high. The potential effect of the dialysis membrane on this mortality has not been previously investigated in a large population of chronic hemodialysis patients. Using data from the United States Renal Data System (USRDS), we analyzed a random sample of 6,536 patients receiving hemodialysis on December 31, 1990. The study design was a historical prospective study. By limiting the study to patients dialyzed for at least one year with bicarbonate dialysate, in whom the dose of dialysis could be calculated, and in whom dialysis membrane and co-existing morbidities were defined, the sample size was reduced to 2,410 patients. A Cox proportional hazards model was used to estimate relative mortality risk. The types of dialysis membranes used were broadly classified into three categories: unsubstituted cellulose, modified cellulose (generally cellulose membranes that have been modified by substitutions of some or most of their hydroxyl moieties) and synthetic membranes that are not cellulosebased. The results of the study suggest that after adjusting for the dose of dialysis and the presence of co-morbid factors, the relative risk of mortality of patients dialyzed with modified cellulose or synthetic membranes was at least 25% less than that of patients treated with unsubstitoted cellulose membranes (P < 0.001). To account for the possibility that these differences were due to regional practice patterns, we further stratified the data for nine different regions. There was still a 20% difference in relative risk of mortality between membrane groups with the mortality statistically significantly less in patients treated with synthetic membranes (P < 0.045) compared to patients dialyzed with unsubstituted cellulose membranes. The results of this study suggest that the dialysis membrane plays an important role in the outcome of chronic hemodialysis patients. However, more definitive studies are needed before a cause and effect relationship can be proven.

Urea KtlV is an accurate tool to estimate the adequacy of hemodialysis (HD) therapy; however, the current methods of calculating KtlV are too complex for routine clinical use and require great care in order to avoid major inaccuracies. As percent reduction in blood urea concentration during dialysis (PRU) is a function of dialyzer urea clearance, length of dialysis, and urea distribution volume of the patient, it might correlate with KtIV. Thus, analyzing retrospectively data of 78 studies, we found that the following linear regression equation existed between KtlV values calculated by means of direct dialysis quantification (DDQ) and PRU values: KtIV = 0.023 x PRU -0.284 (r = 0.92). Furthermore, a good correlation existed between KtlV values measured both by means of DDQ and of the classical algorithm (CA) of the urea kinetic model (UKM) (r = 0.98). Then, a prospective study was started in which 145 KtN values calculated by means of the above equation were correlated with the corresponding ones computed by means of a modified algorithm (MA) of UKM, perfectly fitting those generated by CA of UKM. Although the relationship was exponential, it was linear in the clinically important range of PRU between 40% and 70%, corresponding to a KtN between 0.64 and 1.33. Furthermore, an excellent correlation (r = 0.96) and no statistically significant difference existed in this range between the two series. Finally, our equation was found to be more reliable than two other ones recently suggested for the calculation of KtIV. In conclusion, our equation with only one variable (PRU) enables nephrologists to apply UKM principles in clinical practice by handling an inexpensive, readily available, simple and accurate method of estimating KtN of urea.

We report the successful use of oral urea in the management of children with chronic syndrome of inappropriate antidiuretic hormone secretion (SIAD). We performed a retrospective review of four children with chronic SIAD. After initial attempts at management with fluid restriction, each was started on a 30% to 50% oral urea solution, and the dose was titrated until normal serum sodium was achieved. Fluid intake was liberalized after serum sodium normalization. All four children normalized their serum sodium. No side effects or toxicities were experienced. Oral urea is a safe, effective treatment for chronic SIAD in children. (J Pediatr 2006;148:128-31)

A microchip-based cell culture system was developed and a primary culture of rat hepatocytes was realized in the system. The microchip was made of glass plates and had a microchannel and a microculture flask inside. The flask inner surface was coated using collagen solution; then FBS and DMEM were added successively. Rat hepatocytes suspended in a medium was introduced into the microchip and incubated at 37 • C in a humidified atmosphere with 5% CO 2 . Because of the shortage of dissolved oxygen, the cultured cells in the microchip resulted in a significant decrease in viability. To overcome this, a continuous medium flow oxygen and nutrition supplying system was designed and constructed. The system realized good cell growth for at least 4 days. Liver-specific functions, such as the synthesis of albumin and urea from hepatocytes were confirmed.

Clomipramine hydrochloride (CLP) is an antidepressant drug which shows temperature dependent phase separation, also known as the cloud point (CP). Increase in pH decreases the CP of the drug solution. Addition of ureas/thioureas at a fixed pH (6.25) decreases/increases the CP. In ureas, presence of >C O bond causes a decrease in repulsions among positively charged drug molecules. However, >C S bond (of thioureas) behaves oppositely and hence CP increases. Cationic and non-ionic surfactants form mixed micelles and hence increase the CP. Anionic surfactants, at low concentrations, retard micellization and increase the CP. At higher concentrations, these surfactants also form mixed micelles and, due to charge opposite to the drug molecules, reduce the repulsion among micelles and act as CP suppressors. Increase in solution pH/drug concentration at different fixed concentrations of CTAB causes the CP to decrease/increase. Dye solubilization results with the drug have provided proof to the above explanation.

The aim of this study was to evaluate the accuracy of a new, continuous real time (13)C-urea breath test, BreathID, for the diagnosis of Helicobacter pylori in patients taking proton pump inhibitors (PPIs). Fifty-two consecutive patients, positive for H. pylori by BreathID, were prospectively evaluated. Patients were randomized to receive either omeprazole 20 mg/day or pantoprazole 40 mg/day for 14 days. A repeat breath test was performed on day 14 while patients received their last PPI pill. Patients were given a test drink containing 75 mg (13)C-urea and 4.0 g citric acid. Real time, continuously sampled expired (13)CO(2), obtained within 6-20 min, was compared with measurement of expired (13)CO(2) by isotope ratio mass spectrometry (IRMS). A full set of test data was available for 43 patients. After 14 days of treatment with PPIs, false negative detection of H. pylori occurred in only 1/43 (2.3%) patients examined by continuous real time (13)C-urea breath test compared with 2/43 ...

To evaluate compatibility of commonly used colorimetric protein assays for 2-DE experiments, we investigated the interfering mechanisms of major 2-DE component(s) in the Lowry-based assay, the Bradford assay and the bicinchoninic acid (BCA) assay. It was found that some 2-DE components did not directly interfere with the assays' color development reaction, but possibly influenced the quantitation results by interacting with proteins. Generally, simultaneous presence of 2-DE components in the samples demonstrated a cooperative rather than additive interference. Interference by reductants in the Lowry-based assay and the BCA assay were too prominent and could not be completely eliminated by either the reported alkylation procedure or the water dilution procedure. The Bradford assay however, presented a more suitable method for quantitating 2-DE samples because it was less interfered by most 2-DE components. Furthermore, despite slightly compromising protein solubility, utilization of reductant free 2-DE sample buffers conferred application of the Lowry-based and BCA assays in the 2-DE experiments.

The long-term biokinetics and dosimetry of carbon-14 were studied in nine adults and eight children undergoing carbon-14 urea breath test for Helicobacter pylori (HP) infection. The elimination of 14 C via exhaled air and urine was measured with the liquid scintillation counting technique and with accelerator mass spectrometry. After the subjects had been given 110 kBq 14 C-urea (children: 55 kBq) orally, samples of exhaled air were taken up to 180 days after administration and samples of urine were collected up to 40 days. Sixteen of the subjects were found to be HP-negative. In these subjects a total of 91.1%±3.9% (mean of adults and children ± standard error of the mean) of the administered 14 C activity was recovered. The majority of the administered activity, 88.3%±6.2% in adults and 87.7%±5.0% in children, was excreted via the urine within 72 h after administration. A smaller fraction was exhaled. In adults 4.6%±0.6% of the activity was exhaled within 20 days and in children 2.6%±0.3%. Uncertainties in the biokinetic results are mainly due to assumptions concerning endogenous CO 2 production and urinary excretion rate and are estimated to be less than 30%. The absorbed dose to various organs and the effective dose were calculated using the ICRP model for urea and CO 2 . The urinary bladder received the highest absorbed dose: in adults, 0.15±0.01 mGy/MBq and in children of various ages (7-14 years), 0.14-0.36 mGy/MBq. The findings indicate that an investigation with 14 C-urea gives an effective dose to adults of 2.1±0.1 µSv (for 110 kBq) and to children of 0.9-2.5 µSv (for 55 kBq). From a radiation protection point of view, there is thus no reason for restrictions on even repeated screening investigations with 14 C-urea in whole families, including children.

Background Many patients with heart failure remain symptomatic and have a poor prognosis despite existing treatments. Decreases in myocardial contractility and shortening of ventricular systole are characteristic of systolic heart failure and might be improved by a new therapeutic class, cardiac myosin activators. We report the fi rst study of the cardiac myosin activator, omecamtiv mecarbil, in patients with systolic heart failure. Methods We undertook a double-blind, placebo-controlled, crossover, dose-ranging, phase 2 trial investigating the eff ects of omecamtiv mecarbil (formerly CK-1827452), given intravenously for 2, 24, or 72 h to patients with stable heart failure and left ventricular systolic dysfunction receiving guideline-indicated treatment. Clinical assessment (including vital signs, echocardiograms, and electrocardiographs) and testing of plasma drug concentrations took place during and after completion of each infusion. The primary aim was to assess safety and tolerability of omecamtiv mecarbil. This study is registered at ClinicalTrials.gov, NCT00624442. Findings 45 patients received 151 infusions of active drug or placebo. Placebo-corrected, concentration-dependent increases in left ventricular ejection time (up to an 80 ms increase from baseline) and stroke volume (up to 9•7 mL) were recorded, associated with a small reduction in heart rate (up to 2•7 beats per min; p<0•0001 for all three measures). Higher plasma concentrations were also associated with reductions in end-systolic (decrease of 15 mL at >500 ng/mL, p=0•0026) and end-diastolic volumes (16 mL, p=0•0096) that might have been more pronounced with increased duration of infusion. Cardiac ischaemia emerged at high plasma concentrations (two patients, plasma concentrations roughly 1750 ng/mL and 1350 ng/mL). For patients tolerant of all study drug infusions, no consistent pattern of adverse events with either dose or duration emerged. Interpretation Omecamtiv mecarbil improved cardiac function in patients with heart failure caused by left ventricular dysfunction and could be the fi rst in class of a new therapeutic agent. Funding Cytokinetics Inc. (S M Wasserman MD); ICON Development Solutions (a division of ICON plc), UK

In the search for environmentally benign solvent media, a new class of solvents composed of mixtures of carbohydrates with urea or methylated urea has been noted to be effective in enhancing the reaction rates of a bimolecular organic reaction like the Diels-Alder reaction of cyclopentadiene with methyl acrylate. The viscosity of these media appears to be an important parameter in controlling the second order kinetics.

Invertase and urease are enzyme entities highly associated with the cells of the astaxanthin-producer yeast Xanthophyllomyces dendrorhous (Phaffia rhodozyma) during any stage of its cell growth cycle. In this study cellobiose was a more efficient carbon source ...

Vacuum ultraviolet (VUV) irradiation at wavelengths of λ > 160 nm of urea-h 4 (NH 2 CONH 2) and urea-d 4 (ND 2 COND 2) has been monitored by Fourier transform infrared spectroscopy in argon and xenon matrixes. Several primary photoproducts, such as HNCO:NH 3 (isocyanic acid:ammonia), CO:N 2 H 4 (carbon monoxide: hydrazine) molecular complexes, and isourea (H 2 N(OH)CdNH), which is reported for the first time, were characterized. The assignment of complexes was achieved by co-depositing the pairs of respective species, whereas the isourea identification was based on the comparison between the experimental and theoretical (B3LYP) infrared spectra. Isourea is found in the argon matrix in its most stable (s-Z)-(E) configuration. It is an intermediate in the VUV decomposition process; its dehydration leads to the NH 2 CN:H 2 O complex. In the xenon matrix, the photochemistry of urea yields the HNCO:NH 3 complex as a major product, whereas the CO:N 2 H 4 complex is observed in trace amounts. The observed differences between the argon and xenon matrixes suggest the crossing between S 1 and T 1 potential surfaces of urea to be responsible for the formation of the HNCO:NH 3 complex. A comparison is also performed with other carboxamides, such as formamide (HCONH 2) or acetamide (CH 3 CONH 2).

The present work is aimed at the study of number-size distribution of particles, volatile organic compounds (VOCs), and carbonyl compounds (CC) or carbonyls emitted from a 4-cylinder turbocharged diesel engine equipped with a vanadium-based urea selective catalytic reduction catalyst. The engine was run on an electric dynamometer in accordance with the European steady-state cycle. Pollutants were analyzed using an electric low pressure impactor, a gas chromatograph/mass spectrometer, and a high performance liquid chromatography system for the number-size distribution of particles, VOCs, and CC emissions, respectively. Experimental results revealed that total number of particles were decreased, and their number-size distributions were moved from smaller sizes to larger sizes in the presence of the catalyst. The VOCs were greatly reduced downstream of the catalyst. There was a strong correlation between the conversion of styrene and ethyl benzene. The conversion rate of benzene increased with increase of catalyst temperature. Formaldehyde, acetaldehyde, acrolein and acetone were significantly reduced, resulting in a remarkable abatement in carbonyls with the use of the vanadium-based urea-SCR system.

This proof-of-concept study demonstrated the potential of Raman microspectroscopy for nondestructive identification of traces of sweat for forensic purposes. Advanced statistical analysis of Raman spectra revealed that dry sweat was intrinsically heterogeneous, and its biochemical composition varies significantly with the donor. As a result, no single Raman spectrum could adequately represent sweat traces. Instead, a multidimensional spectroscopic signature of sweat was built that allowed for the presentation of any single experimental spectrum as a linear combination of two fluorescent backgrounds and three Raman spectral components dominated by the contribution from lactate, lactic acid, urea and single amino acids.

Cyanide binding to cytochrome c was monitored by absorption spectroscopy from neutral to acidic pH in the presence of urea. These results were compared with acid-induced unfolding at corresponding urea concentration monitored by absorption spectroscopy and circular dichroism. The association rate constant k a increased 20-fold when the concentration of urea was raised from 0 M to 6 M at neutral pH. However, the secondary structure of the protein was not affected, i.e. there was no striking conformational change in these urea concentrations at neutral pH. At the pH that was very close to the pK of acid-induced unfolding, the k a value reached its maximum (k a,max ) in all urea concentrations. Interestingly, the k a,max value increased exponentially with increasing urea concentrations. These results are interpreted in terms of a change in the flexibility of the least stable part of the cyt c structure that is responsible for the Fe-S(Met80) bond disruption and for ligand binding to heme iron.

Monomer detergent concentrations of Triton X-100, Chaps (3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate), and sodium dodecyl sulfate in guanidine hydrochloride, formamide, and urea solutions were measured by an ultrafiltration procedure. This simple and rapid procedure effectively separated the monomer forms of these detergents from their respective micelle forms. Critical micellar concentrations of these detergents in water measured by this procedure agreed well with previously reported values. Both ionic and nonionic chaotropic agents, e.g., guanidine hydrochloride, formamide, and urea, are demonstrated to significantly shift the equilibrium between the monomer and the micellar form of various detergents toward the direction of monomer in a concentration-dependent manner. Thus, monomer/micelle ratio of detergents in solution can be manipulated over a wide range by the concomitant use of chaotropic solvents. This has direct applications in experiments involving destruction of biomembranes and solubilization of hydrophobic molecules in aqueous solutions.

Hyperlipidic diets limit glucose oxidation and favor amino acid preservation, hampering the elimination of excess dietary nitrogen and the catabolic utilization of amino acids. We analyzed whether reduced urea excretion was a consequence of higher NO x ; (nitrite, nitrate, and other derivatives) availability caused by increased nitric oxide production in metabolic syndrome. Rats fed a cafeteria diet for 30 days had a higher intake and accumulation of amino acid nitrogen and lower urea excretion. There were no differences in plasma nitrate or nitrite. NO(x) and creatinine excretion accounted for only a small part of total nitrogen excretion. Rats fed a cafeteria diet had higher plasma levels of glutamine, serine, threonine, glycine, and ornithine when compared with controls, whereas arginine was lower. Liver carbamoyl-phosphate synthetase I activity was higher in cafeteria diet-fed rats, but arginase I was lower. The high carbamoyl-phosphate synthetase activity and ornithine levels s...

The objective of the present study was to investigate the iontophoretic transport behavior across multiple membranes of different barrier properties. Spectra/ Por 1 (SP) and Ionac membranes were the synthetic membranes and sclera was the biomembrane in this model study. The barrier properties of SP membranes were determined individually in passive and iontophoresis transport experiments with tetraethylammonium ion (TEA), chloride ion (Cl), and mannitol as the model permeants. Passive and iontophoretic transport experiments were then conducted with an assembly of SP membranes. The contribution of electroosmosis to iontophoresis was assessed using the mannitol data. Model analysis was performed to study the contribution of diffusion and electromigration to electrotransport across the multiple membrane system. The effects of membrane barrier thickness upon ion-exchange membrane-enhanced iontophoresis were examined with Ionac, SP, and sclera. The present study shows that iontophoretic transport of TEA across the membrane system was related to the thicknesses and permeability coefficients of the membranes and the electromobilities of the permeant across the individual membranes in the assembly. Model analysis suggests significant contribution of diffusion within the membranes across the membrane system, and this mechanism is relatively independent of the current density applied across the system in iontophoresis dominant transport. ß Ã Mean AE SD, n ! 3. a Number of membranes in parentheses. b Calculated using Eq. (3).

or baiting of Mycobacterium avium-intracellulare (MAI) complex organisms and other 'atypical mycobacteria' and the inability of Mycobacterium tuberculosis to utilise paraffin are known and useful if forgotten facts. Strains of possible AIDSrelated MAI have been introduced into Czapek broth devoid of any carbon source other than paraffin-wax coated slides. Replicate slides showing 'in situ' growth were subjected to the following battery of tests: acid alcohol fast staining and microscopic examination of 'in situ' growth, tellurite reduction in 3 days, absence of urea hydrolysis, inability to reduce nitrates and inability to hydrolyse Tween 80. The system has been utilised to isolate and identify MAI organisms in blood from AIDS patients. The simplicity, low cost, and reduced risk of contamination make the system especially suitable for small rural laboratories and field stations as well as laboratories in developing countries.

Proteins are marginally stable, and the folding/unfolding equilibrium of proteins in aqueous solution can easily be altered by the addition of small organic molecules known as cosolvents. Cosolvents that shift the equilibrium toward the unfolded ensemble are termed denaturants, whereas those that favor the folded ensemble are known as protecting osmolytes. Urea is a widely used denaturant in protein folding studies, and the molecular mechanism of its action has been vigorously debated in the literature. Here we review recent experimental as well as computational studies that show an emerging consensus in this problem. Urea has been shown to denature proteins through a direct mechanism, by interacting favorably with the peptide backbone as well as the amino acid side chains. In contrast, the molecular mechanism by which the naturally occurring protecting osmolyte trimethylamine N-oxide (TMAO) stabilizes proteins is not clear. Recent studies have established the strong interaction of TMAO with water. Detailed molecular simulations, when used with force fields that incorporate these interactions, can provide insight into this problem. We present the development of a model for TMAO that is consistent with experimental observations and that provides physical insight into the role of cosolvent-cosolvent interaction in determining its preferential interaction with proteins. 273 Annu. Rev. Phys. Chem. 2013.64:273-293. Downloaded from www.annualreviews.org by RENSSELAER POLYTECHNIC INSTITUTE on 04/05/13. For personal use only. Click here for quick links to Annual Reviews content online, including: • Other articles in this volume • Top cited articles • Top downloaded articles • Our comprehensive search Further ANNUAL REVIEWS 274 Canchi · García Annu. Rev. Phys. Chem. 2013.64:273-293. Downloaded from www.annualreviews.org by RENSSELAER POLYTECHNIC INSTITUTE on 04/05/13. For personal use only. Cosolvent: small, neutral organic molecules that can modulate protein stability van't Hoff enthalpy: enthalpy obtained by analysis of the temperature dependence of the equilibrium constant TMAO: trimethylamine N-oxide Molecular dynamics (MD): computational technique to study the microscopic motions of atoms and molecules; molecular trajectories are obtained by numerically integrating Newton's equations of motion Linear extrapolation model (LEM): used to model the dependence of protein stability on cosolvent concentration

A series of structurally novel benzothiazole based small molecule inhibitors of p56 lck were prepared to elucidate their structure-activity relationships (SARs), selectivity and cell activity in the T-cell proliferation assay. BMS-243117 (compound 2) is identified as a potent, and selective Lck inhibitor with good cellular activity (IC 50 =1.1 mM) against T-cell proliferation. #

The aim of this study was to describe and evaluate physiological parameters as a control tool for the monitoring of training in a group of elite cyclists during one season of training. The study is divided into two periods (winter or &#39;&#39;volume&#39;&#39; mesocycle and spring or &#39;&#39;intensity&#39;&#39; mesocycle) between the tests that they carried out in the laboratory, consisting of a ramp test to exhaustion (work load increases 25 W X min(-1)) and a maximal lactate steady state (MLSS) test on a cycle ergometer. Macronutrients and hematological variables were recorded during the test periods as were the volume and the intensity of training sessions during the whole period of the study. The physiological data were similar to those previously reported for professional cyclists (approximately 450 Watts, approximately 78 mL x kg(-1) x min(-1)) and the values for the MLSS also agree with previous studies (approximately 250 Watts). Subjects improved the first ventilatory thre...

Gadolinium vibronic side band luminescent spectroscopy (GVSBLS) is used to probe osmolyteinduced changes in the hydrogen bond strength between first and second shell waters on the surface of free Gd 3+ and Gd 3+ coordinated to EDTA and to structured calcium binding peptides in solution. In parallel, Raman is used to probe the corresponding impact of the same set of osmolytes on hydrogen bonding among waters in the bulk phase. Increasing concentration of added urea is observed to progressively weaken the hydrogen bonding within the hydration layer but has minimal observed impact on bulk water. In contrast polyols are observed to enhance hydrogen bonding in both the hydration layer and the bulk with the amplitude being polyol dependent with trehalose being more effective than sucrose, glucose or glycerol. The observed patterns indicate that size and properties of the osmolyte as well as the local architecture of the specific surface site of hydration impacts preferential exclusion effects and local hydrogen bond strength. Correlation of the vibronic spectra with CD measurements on the peptides as a function of added osmolytes shows an increase in secondary structure with added polyols and that the progressive weakening of the hydrogen bonding upon addition of urea first increases water occupancy within the peptide and only subsequently does the peptide unfold. The results support models in which the initial steps in the unfolding process involves osmolyte induced enhancement of water occupancy within the interior of the protein.

Multiple-day food records or 24-hour dietary recalls (24HRs) are commonly used as "reference" instruments to calibrate food frequency questionnaires (FFQs) and to adjust findings from nutritional epidemiologic studies for measurement error. Correct adjustment requires that the errors in the adopted reference instrument be independent of those in the FFQ and of true intake. The authors report data from the Observing Protein and Energy Nutrition (OPEN) Study, conducted from September 1999 to March 2000, in which valid reference biomarkers for energy (doubly labeled water) and protein (urinary nitrogen), together with a FFQ and 24HR, were observed in 484 healthy volunteers from Montgomery County, Maryland. Accounting for the reference biomarkers, the data suggest that the FFQ leads to severe attenuation in estimated disease relative risks for absolute protein or energy intake (a true relative risk of 2 would appear as 1.1 or smaller). For protein adjusted for energy intake by using either nutrient density or nutrient residuals, the attenuation is less severe (a relative risk of 2 would appear as approximately 1.3), lending weight to the use of energy adjustment. Using the 24HR as a reference instrument can seriously underestimate true attenuation (up to 60% for energy-adjusted protein). Results suggest that the interpretation of findings from FFQ-based epidemiologic studies of diet-disease associations needs to be reevaluated. bias (epidemiology); biological markers; diet; energy intake; epidemiologic methods; nutrition assessment; questionnaires; reference values Abbreviations: DLW, doubly labeled water; FFQ, food frequency questionnaire; OPEN, Observing Protein and Energy Nutrition; 24HR, 24-hour dietary recall.

We conducted this study to determine what receptor mediates the effect of oxytocin to increase osmotic water permeability (Pf) in the rat inner medullary collecting duct (IMCD). Reverse transcription-polymerase chain reaction (RT-PCR) experiments demonstrated that mRNA for both the oxytocin receptor and the V2 receptor is present in the rat terminal IMCD. In isolated perfused IMCD segments, we found that the V2 vasopressin receptor antagonist [d(CH2)5(1),D-Ile2,Ile4,Arg8]vasopressin, but not oxytocin receptor antagonists, blocked the hydrosmotic response to 200 pM oxytocin. The selective oxytocin receptor agonist [Thr4,Gly7]oxytocin did not increase water permeability. Oxytocin also increased urea permeability in IMCD segments. Studies in IMCD suspensions showed that oxytocin increases adenosine 3&#39;,5&#39;-cyclic monophosphate production in a dose-dependent fashion with a half-maximal (EC50) response at 5.2 nM. The dose-response curves were virtually identical for IMCD suspension...

This article reviews the efficacy of a new 6.5% hydrogen peroxide tooth-whitening gel strip for bleaching teeth that have been intrinsically stained from tetracycline. Given the severity of staining in the cases presented during a recently conducted clinical trial, the resulting efficacy is dramatic. Additionally, the continuous use of these strips for 30 minutes per day, twice daily for 2 months with no meaningful adverse effects is noteworthy.

The present study was undertaken to study the effects of application of natural wood smoke on ripening of Cheddar cheese, and to determine the effects of smoking before or after ripening on cheese quality. A 20-kg block of Cheddar cheese obtained immediately after pressing was divided into six approximately 3-kg blocks and ripened at 8 degrees C for up to 270 d. One 3-kg block was taken after 1 d, 1, 3, 6, or 9 mo and smoked for 20 min, then returned to the ripening room for further ripening. Cheeses were sampled at intervals for lactobacilli counts, moisture, pH, and proteolysis. Sensory analysis was conducted on 6 and 9-mo-old cheeses by a trained sensory panel (n = 7). Results show that application of natural wood smoke did not significantly affect cheese pH or primary proteolysis during ripening. However, secondary proteolysis as assessed by the concentrations of free amino acids was generally higher in smoked cheeses than in control cheeses after 6 mo of ripening. Cheese smoked...

This study investigated the effect of 3 staining solutions and 3 over-the-counter tooth-bleaching systems on the microhardness of 2 dental resin composites. Forty-five specimens of Filtek Supreme and Esthet-X were randomly assigned to 3 groups. Over a 40-day test period, the specimens in each group (n=15) were immersed in 1 of the 2 staining solutions (coffee and red wine) or distilled water as the control for 3 hours a day at room temperature. The 15 specimens in each staining group were further randomly divided into 3 subgroups, and the specimens in each subgroup (n=5) were bleached using one of the bleaching agents (Night Effects, Simply White Night and Opalescence Quick). Surface hardness was measured at 24 hours after polymerization (baseline), after staining and after bleaching. Means and standard deviations were calculated, and the data were analyzed using repeatedmeasures analysis of variance and Duncan's Test. The microhardness of Esthet-X was significantly higher than Filtek Supreme at baseline (p<0.01). All specimens of both materials immersed in coffee and wine revealed a significant hardness decrease compared to baseline values (p<0.05). In the control group, microhardness was increased, and this increase was statistically significant for Filtek Supreme (p<0.05). After bleaching, there was a significant decrease in mean microhard-Beverages, such as wine or coffee, and bleaching agents result in decreases in composite surface microhardness from baseline values.

The gastric bacterial flora and its influence on the IQ C-urea breath test (UBT) for detection of Helicobacter pylori infection was studied in a pig model. Seven SPF minipigs were used. H. pylori or a mix of other urease positive bacteria were administered orally. UBT, serum and biopsies for histology and culture were collected. Our results show that UBT is not specific for H. pylori in pigs as the gastric bacterial flora is responsible for the high UBT values observed. Furthermore, the Ellegaard Go ë ttingen SPF minipigs are not useful in an animal model for H. pylori studies. z

The fast separation of oligonucleotide (oligos) sizing marker by CE using OliGreen  and including effects due to the concentration of separation medium and urea denaturant is presented. OliGreen dye is found to be more sensitive than ethidium bromide (by a factor of about 6 based on S/N considerations) for the oligos' separations. Higher concentration of F127 in 16Tris-boricacid-EDTA (TBE) up to 30% w/v leads to better resolution of oligos separations. The addition of urea into the separation medium decreases the sensitivity. With an optimized running condition, the oligos sizing marker could be successfully separated with 1-base resolution within 1.3 min by using 30% w/v F127/16TBE solution as the separation medium at an applied electric field of 800 V/cm in a 3 cm long capillary, the fastest capillary gel electrophoresis separation with high resolution reported to date for oligos in the similar size range.