Berthelot Method Research Articles

A Sensitive Determination of Ammonia and Nitrite in Exhaled Breath Condensate of Healthy Humans by Using Berthelot Reaction

Background: Exhaled breath has recently been identified as an alternative matrix for the detection of drugs and chemical compounds. By keeping in mind that different chemical and biological compounds have already been determined in the exhaled air, the Exhaled Breath Condensate (EBC) was found to be a suitable sample for non-invasive assessment of the respiratory system. Thus, the aim of this work is determination of ammonia and nitrite in EBC samples. Methods: The determination of the analytes is based on the derivatization of ammonia using Berthelot method. The absorbance of colored compound was determined at 655 ± 3 nm. Nitrite ion was determined after its reduction to ammonia by using Zn/HCl reagent. Results: Good calibration curves were obtained for ammonia with linearity in the range of 10– 620 ng mL -1 , and correlation coefficients (r2) of more than 0.999. The Limit of Detection and Quantification (LOD, LOQ) and Lower Limit of Quantification (LLOQ) were found to be 1.5, 4.5 and 10 ng mL -1 , respectively. The recoveries of the method were calculated to be 94 to 102.5% and the intra- and interday precisions were lower than 1.4 and 3.4%, respectively. Conclusion: The results presented here demonstrate that the concentrations of ammonia and nitrite in samples of healthy humans can be determined with good accuracy, high sensitivity, and simple operation. The proposed EBC methodology possessed several advantages like simplicity and low cost, especially if more sophisticated techniques such as HPLC are not available. Keywords: Ammonia, Berthelot reaction, Exhaled Breath Condensate (EBC), nitrite, spectrophotometry, absorbance.

LED-Based Portable Optical Biosensor for Measurement of Serum Urea Levels Using Urease Immobilized Agarose-Guar Gum Composite Film

A simple, reliable, low cost, and portable biosensor has been developed for direct measurement of urea levels in serum samples. It is based on hydrolysis of urea by immobilized urease, generating ammonia that is estimated by modified Berthelot method using simple optical detection system. The immobilization of urease was achieved in agarose guar-gum composite film for the first time which offered an excellent retention of enzyme activity (90%–95%) with negligible leaching and good operational stability. The optical detection system involving LED light, optical fiber, and phototransistor provides simple and portable measurement system. The sensor shows linear response in the wide range of urea concentration from 0.025 to 10 mM with reusability for 10 cycles and superior storage stability of 180 days. The fabricated biosensor was successfully employed for measurement of normal and abnormal urea levels in serum samples with accuracy of 96% using very small sample volume ( $15~\mu \text{l}$ ). It showed an excellent correlation ( $r^{2}=0.99$ ) for determination of urea levels with that of using Siemens autoanalyzer.

Negative Pressure Regimes in Ionic Liquids: Structure and Interactions in Stretched Liquids as Probed by NMR

Condensed matter - solids or liquids, but not gases - might be deeply, homogeneously stretched to absolute negative pressures (metastable regimes of isotropic tension). For instance, we were able to stretch macroscopically-sized liquid solutions down to p ~ - 35 MPa,[1] a value which still constitutes a world record for large volume liquid samples. Up to now, the absolute record for neat liquids is hold for liquid water in microscopic porous crevices of natural rocks, p ~ -140 MPa. There are several strategies to force a liquid entering into negative pressure regimes. The most common one is the Berthelot method.[2] Negative pressures can be either directly measured - via a highly elaborated Bourdon-Berthelot combination methodology[3,4] or safely, though approximately, estimated through the liquid’s isochoric thermal-pressure coefficient, g v = a p/k T. In this work, a broad pallete of macroscopically sized samples of ionic liquids was used, in which tensions of about -100 MPa were obtained before cavitation would occur. This value constitutes a new record for large samples. The underlying success for achieving such great absolute negative pressures in ionic liquids as compared to other liquids seems to be the best combination of (i) their negligible vapour pressure and (ii) their generally high viscosity. Good adhesion (wettability) to the container’s walls (in this case Pyrex glass) is a paramount, minimum requirement. For the first time, NMR studies have been performed on ionic liquids under homogeneous tension. Due to potential hazard issues related to the protection/safety of the NMR instrumentation, negative pressures beyond the value of – 20 MPa were avoided. Upon entering into these metastable regimes of negative pressure, it was possible to observe a sharp increase in the ions self-diffusion coefficients as compared to the equilibrium saturated liquid conditions at the same temperatures. MD simulations have been performed to gain insights into the ILs structure and interactions under these deep metastable conditions.

NEPHROPROTECTIVE ACTIVITY OF THE ETHNOMEDICINAL PLANTS CAESALPINIA BONDUC AND MOMORDICA DIOICA FROM NE INDIA AGAINST CISPLATIN INDUCED CHEMOTHERAPEUTIC TOXICITY

Objective: Cisplatin a potent anticancer drug is used for treatment against different forms of cancer. However a major limitation of cisplatin is its nephrotoxicity and severe side effects. The main objective of the present study was to investigate the nephroprotective activity of the medicinal plants Caesalpinia bonduc and Momordica dioica against cisplatin-induced nephrotoxicity. Methods: In the present study wistar rat models were intraperitoneally injected with cisplatin for eight consecutive days Plant extracts of different compositions were administered for eight days after injection of cisplatin. The polyphenolic content of the crude extracts was investigated using the Folin Ciocalteau method while the flavonoid estimation was carried out using the aluminium chloride method. The antioxidant activities of the extracts were assayed using the DPPH radical scavenging method. Plant extracts were tested for their nephroprotective ability using modified Berthelot method, uricase method, alkaline picrate method.Results: In the present study it was found that the level of creatinine, urea, uric acid and blood urea nitrogen was lowered by the crude hexane extract of Momordica dioica and ethyl acetate extract of Caesalpinia bonduc as compared to the control group. The total phenolic content and the total flavonoid content was found to be highest in the hexane extract of Momordica dioica with 110.51±1.0 μg/GAE and 1.92±0.15 μg/QE. The methanol extract of Caesalpinia bonduc was found to be the highest in inhibition of the DPPH free radicals with nearly 80% inhibition.Conclusion: The present study revealed the nephroprotective ability of the hexane extract of Momordica dioica and ethyl acetate extract Caeselpinia bonduc. The extracts were also found to have higher antioxidant activity and therefore their nephroprotective activity might be due to attenuation of oxidative stress.

Short-term aerobic exercise does not change kidney function in students of Nnamdi Azikiwe University, Nigeria

BackgroundExercise has been known to have beneficial effects on human health. The kidneys play an important role in regulating acid-base and water-electrolyte balance disturbances induced by exercise. The objective of this study was to investigate the effect of short term aerobic exercise (volleyball training) on the kidney function of apparently healthy individuals. MethodsAn experimental study of pre-post test design was conducted involving 41 amateur volleyball players, comprising 22 males and 19 females. They were randomly divided into seven different teams. Each team trained for at least 45 minutes for four consecutive days for two weeks. Both pre-and post-exercise blood pressure (BP) was measured using an automatic blood pressure measuring device OMRON 907 (OMRON, Hoofddorp, Netherlands). Likewise, both pre- and post-exercise blood samples were collected into lithium heparin tubes and centrifuged at 3000 rpm for 10 minutes and the plasma separated into plain tubes. Electrolytes were analysed using ion selective electrode machine (SFRI 4000, Germany), urea using modified Berthelot method, creatinine using Jaffe-Slot method and uric acid using the uricase method and estimated glomerular filtration state (eGFR) was calculated using the Modification of Diet in Renal Disease (MDRD) formula. ResultsThe mean levels of pre- and post-exercise systolic blood pressure, creatinine, urea, sodium, potassium, chloride, bicarbonate and eGFR did not differ significantly (p>0.05). However, serum uric acid was significantly increased (p<0.05), while diastolic BP significantly decreased after exercise (p<0.05).ConclusionThe study showed that short-term moderate intensity aerobic exercise does not have any significant effect on the renal functions.

Nephroprotective Effect of Pterocarpus indicus Willd. Leaves: Observation From Plasma Urea and Creatinine Levels Against Gentamicin-Induced Nephrotoxicity in Sprague-Dawley Rats

Introduction: Pterocarpus indicus Willd. has been widely used empirically for treating canker sore, antibacterial and kidney disease. Objective: This study aimed to evaluate nephroprotective effect water-boiled P. indicus leaves against gentamicin-induced nephrotoxicity in rats observed from plasma urea and creatinine levels. Materials and Methods: In this study, thirty (30) male rats divided into five treatment groups. The treatment groups consisted of the normal group, induction group received gentamicin (80 mg/kg body weight per day i.p.) and a group which received water-boiled P. indicus leaves with a dose of 28.8 mg/kg, 57.6 mg/kg, and 115.2 mg/kg body weight per day p.o. All groups received treatment for 21 days. At the 15th day, the animals received gentamicin i.p. for 7 days. At the 22nd day, the blood was collected from orbital sinus. The plasma urea and creatinine levels were measured by Berthelot method for plasma urea and colorimetric method for plasma creatinine. Results: The highest dose of 115.2 mg/kg water-boiled P. indicus was decreased plasma urea and creatinine levels also significantly different (p Conclusions: Water-boiled P. indicus leaves have a potential to prevent gentamicin-induced nephrotoxicity might be due to its antioxidant and free radical scavenging activity. Key words: Gentamicin, Nephroprotective, Plasma creatinine, Plasma urea, Pterocarpus indicus Willd.

Mechanism of anti-Helicobacter pylori urease activity of patchouli alcohol

To investigate the effect of patchouli alcohol on inhibiting Helicobater pylori urease activity, and its effect on expression levels of related genes, and lay the foundation for further research on the effect of patchouli alcohol on H. pylori colonization and infection. H. pyloriwas cultured and identified by gram staining, rapid urease test (RUT) and PCR method. Then agar dilution method was used to detect the bacterial survival after 1 h intervention by different concentrations of patchouli alcoholin the acidic (pH 5.3) and neutral (pH 7.0) conditions; berthelot method was used to detect urease activity and RT-qPCR method was used to detect the expression changes of ureA, ureB, ureE, ureH, ureI, and nixA related urease genes. The results showed that the survival rate of H. pyloriwas not significantly changed but the urease activity was obviously decreased after intervention by different concentrations of patchouli alcohol; meanwhile, the expression levels of ureA, ureB, ureE, ureH, ureI, and nixA were decreased to different degrees. Therefore, patchouli alcohol could inhibit H. pylori urease activity in both acidic and neutral conditions, and the mechanism may be related to down-regulation of urease gene expression.

Andrographolide sodium bisulphite-induced inactivation of urease: inhibitory potency, kinetics and mechanism.

BackgroundThe inhibitory effect of andrographolide sodium bisulphite (ASB) on jack bean urease (JBU) and Helicobacter pylori urease (HPU) was performed to elucidate the inhibitory potency, kinetics and mechanism of inhibition in 20 mM phosphate buffer, pH 7.0, 2 mM EDTA, 25 °C.MethodsThe ammonia formations, indicator of urease activity, were examined using modified spectrophotometric Berthelot (phenol-hypochlorite) method. The inhibitory effect of ASB was characterized with IC50 values. Lineweaver-Burk and Dixon plots for JBU inhibition of ASB was constructed from the kinetic data. SH-blocking reagents and competitive active site Ni2+ binding inhibitors were employed for mechanism study. Molecular docking technique was used to provide some information on binding conformations as well as confirm the inhibition mode.ResultsThe IC50 of ASB against JBU and HPU was 3.28 ± 0.13 mM and 3.17 ± 0.34 mM, respectively. The inhibition proved to be competitive and concentration- dependent in a slow-binding progress. The rapid formation of initial ASB-JBU complex with an inhibition constant of Ki = 2.86 × 10−3 mM was followed by a slow isomerization into the final complex with an overall inhibition constant of Ki* = 1.33 × 10−4 mM. The protective experiment proved that the urease active site is involved in the binding of ASB. Thiol reagents (L-cysteine and dithiothreithol) strongly protect the enzyme from the loss of enzymatic activity, while boric acid and fluoride show weaker protection, indicating that the active-site sulfhydryl group of JBU was potentially involved in the blocking process. Moreover, inhibition of ASB proved to be reversible since ASB-inactivated JBU could be reactivated by dithiothreitol application. Molecular docking assay suggested that ASB made contacts with the important sulfhydryl group Cys-592 residue and restricted the mobility of the active-site flap.ConclusionsASB was a competitive inhibitor targeting thiol groups of urease in a slow-binding manner both reversibly and concentration-dependently, serving as a promising urease inhibitor for the treatment of urease-related diseases.

Kinetic-spectrophotometric determination of neomycin

A new kinetically-based spectrophotometric method for the determination of micro quantities of neomycin is described in this paper. It is an adaptation of the modified Berthelot method which is a widely used colorimetric procedure for urea determination. The method was developed due to neomycin effect on 2,2′-dicarboxyindophenol formation. The experimental conditions for successful determination of neomycin were optimized. The relative standard deviation (RSD) for the neomycin concentration interval of 77–154 μg/mL, ranges from 0.7 to 1%. The method was directly applied to determining neomycin in ophthalmic drops. The obtained results in analyzed pharmaceutical samples were in accordance with disc-diffusion microbiological method results.

Biological evaluation and molecular docking of baicalin and scutellarin as Helicobacter pylori urease inhibitors

Ethnopharmacological relevanceBaicalin and scutellarin are the principal bioactive components of Scutellaria baicalensis Georgi which has extensively been incorporated into heat-clearing and detoxification formulas for the treatment of Helicobacter pylori-related gastrointestinal disorders in traditional Chinese medicine. However, the mechanism of action remained to be defined. Aim of the studyTo explore the inhibitory effect, kinetics and mechanism of Helicobacter pylori urease (the vital pathogenetic factor for Helicobacter pylori infection) inhibition by baicalin and scutellarin, for their therapeutic potential. Materials and methodsThe ammonia formations, indicator of urease activity, were examined using modified spectrophotometric Berthelot (phenol–hypochlorite) method. The inhibitory effect of baicalin and scutellarin was characterized with IC50 values, compared to acetohydroxamic acid (AHA), a well known Helicobacter pylori urease inhibitor. Lineweaver–Burk and Dixon plots for the Helicobacter pylori urease inhibition of baicalin and scutellarin was constructed from the kinetic data. SH-blocking reagents and competitive active site Ni2+ binding inhibitors were employed for mechanism study. Molecular docking technique was used to provide some information on binding conformations as well as confirm the inhibition mode. Moreover, cytotoxicity experiment using Gastric Epithelial Cells (GES-1) was evaluated. ResultsBaicalin and scutellarin effectively suppressed Helicobacter pylori urease in dose-dependent and time-independent manner with IC50 of 0.82±0.07mM and 0.47±0.04mM, respectively, compared to AHA (IC50=0.14±0.05mM). Structure-activity relationship disclosed 4′-hydroxyl gave flavones an advantage to binding with Helicobacter pylori urease. Kinetic analysis revealed that the types of inhibition were non-competitive and reversible with inhibition constant Ki of 0.14±0.01mM and 0.18±0.02mM for baicalin and scutellarin, respectively. The mechanism of urease inhibition was considered to be blockage of the SH groups of Helicobacter pylori urease, since thiol reagents (l,d-dithiothreitol, l-cysteine and glutathione) abolished the inhibitory action and competitive active site Ni2+ binding inhibitors (boric acid and sodium fluoride) carried invalid effect. Molecular docking study further supported the structure-activity analysis and indicated that baicalin and scutellarin interacted with the key residues Cys321 located on the mobile flap through SH·π interaction, but did not interact with active site Ni2+. Moreover, Baicalin (at 0.59–1.05mM concentrations) and scutellarin (at 0.23–0.71mM concentrations) did not exhibit significant cytotoxicity to GES-1. ConclusionsBaicalin and scutellarin were non-competitive inhibitors targeting sulfhydryl groups especially Cys321 around the active site of Helicobacter pylori urease, representing potential to be good candidate for future research as urease inhibitor for treatment of Helicobacter pylori infection. Furthermore, our work gave additional scientific support to the use of Scutellaria baicalensis in traditional Chinese medicine (TCM) to treat gastrointestinal disorders.

The development of an autonomous sensing platform for the monitoring of ammonia in water using a simplified Berthelot method

This study has demonstrated a direct reagent-based analyser for ammonia, incorporating a modified version of the Berthelot method resulting in an inexpensive and simple procedure to measure ammonia in water.

Assessment of Serum Cholesterol and Urea Levels of Smokers and Non Smokers

The wide spread and distressing heart disease related to smoking resulting from increased level in plasma total cholesterol was the focus of this work. The effect of smoking on serum cholesterol and urea levels of 160 subjects consisting of 80 smokers and 80 nonsmokers (control) was investigated. Total cholesterol and urea levels were determined by enzymatic colorimetric end point (CHOD-PAP) increasing reaction (diagnostic reagent for quantitative invitro determination of cholesterol in serum or plasma on photometric system) and modified Berthelot methods respectively. The mean cholesterol levels were 7.35+0.27mmol/l and 3.34+1.99mmol/l for the smokers and nonsmokers respectively while the mean serum urea level were 9.30+1.14mmol/l and 3.85+0.04mmol/l for the smokers and nonsmokers respectively. There was statistical significant difference in the mean cholesterol and urea levels between smokers and nonsmokers (control) using the student dtests. The work showed that the mean serum total cholesterol and urea concentrations were higher for smokers than nonsmokers indicating that smokers are predisposed to cardiovascular disease and possible renal problem.

Anti-malarial property of steroidal alkaloid conessine isolated from the bark of Holarrhena antidysenterica

BackgroundIn the face of chronic and emerging resistance of parasites to currently available drugs and constant need for new anti-malarials, natural plant products have been the bastion of anti-malarials for thousands of years. Moreover natural plant products and their derivatives have traditionally been a common source of drugs, and represent more than 30% of the current pharmaceutical market. The present study shows evaluation of anti-malarial effects of compound conessine isolated from plant Holarrhena antidysenterica frequently used against malaria in the Garhwal region of north-west Himalaya.MethodsIn vitro anti-plasmodial activity of compound was assessed using schizont maturation and parasite lactate dehydrogenase (pLDH) assay. Cytotoxic activities of the examined compound were determined on L-6 cells of rat skeletal muscle myoblast. The four-day test for anti-malarial activity against a chloroquine-sensitive Plasmodium berghei NK65 strain in BALB/c mice was used for monitoring in vivo activity of compound. In liver and kidney function test, the activity of alkaline phosphatase (ALP) was examined by p-NPP method, bilirubin by Jendrassik and Grof method. The urea percentage was determined by modified Berthelot method and creatinine by alkaline picrate method in serum of mice using ENZOPAK/CHEMPAK reagent kits.ResultsCompound conessine showed in vitro anti-plasmodial activity with its IC50 value 1.9 μg/ml and 1.3 μg/ml using schizont maturation and pLDH assay respectively. The compound showed cytotoxity IC50= 14 μg/ml against L6 cells of rat skeletal muscle myoblast. The isolated compound from plant H. antidysenterica significantly reduced parasitaemia (at 10 mg/kg exhibited 88.95% parasite inhibition) in P. berghei-infected mice. Due to slightly toxic nature (cytotoxicity = 14), biochemical analysis (liver and kidney function test) of the serum from mice after administration of conessine were also observed.ConclusionThe present investigation demonstrates that the compound conessine exhibited substantial anti-malarial property. The isolated compound could be chemically modified to obtain a more potent chemical entity with improved characteristics against malaria.

Temperatures of maximum density in a pressure range from 15 MPa to −15 MPa generated for water in a metal Berthelot tube

Water exhibits anomalous thermodynamic properties. For example, the specific heat capacity of water is at minimum at 36°C under atmospheric pressure. In order to investigate phase diagrams including thermodynamic meta-stable states, which are important to elucidate the anomalies, the temperatures of maximum density (TMDs) were estimated in a pressure range from +15 MPa to −15 MPa on the basis of data of temperatures and pressures measured for various densities of water in a metal Berthelot tube. The TMDs in the negative pressure region were not on an extrapolation of an equation of state for water. The trend was similar to that not observed by a Berthelot method of glass spiral capillaries but calculated from molecular dynamics computer simulations.

Quick determination of ammonia ions in water environment based on thymol color creating reaction

In this article, the thymol, one of phenolic derivative as color creative reagent and nitropruside as reaction catalyst were investigated for photometric and visual quick-test determination of ammonia in fresh and drinking water based on Berthelot (phenate) method. For this purpose, one test set should have maximum 2 to 3 mixed components solution. So the different solution preparation modes and reagents combination were studied. The investigation results showed that the 2 mixed solution mode was impossibly prepared because nitropruside was decomposed in strong oxidative solution such as hypochlorite and increased color intensity when mixed with thymol in strong alkaline solution by ageing. The 3 mixed solution mode was proposed and optimal components mixing was fount i. e. solution 1 is nitropruside in ammonia free water; solution 2 is hypochlorite in carbonate buffer at pH 10 and solution 3 is thymol and EDTA in 2M of sodium hydroxide. This 3 solution test set was used for ammonia quick determination. Following proposed test procedure, the full color creation takes less than 5 minutes and total time for one test is approximately 7 – 8 minutes. The ammonia concentration in different samples determined by photometric and visual method using 3 solution test set were compared with conventional spectrophotometric method. The measured values showed that analytical results were agreed each with other and the proposed test set could be used as test-kit for field measurement or common monitoring ammonia in fresh and drinking water. The maximum relative error is less than 25%.

P072 Arginine metabolism and IL-17 pathway in Behçet disease: A study in Algerian patients

IntroductionBehçet disease (BD) is an inflammatory, chronic, systemic affection with uncertain etiology. In previous works, we showed that BD is characterized by a Th1/Th2 cytokines profile. However, recent works showed the presence of Th17/Treg responses. In this study, we measured the IL-6, IL-17 and TGF-β levels in vivo during BD and their effect on in vitro production of two inflammatory metabolic products: NO and urea. MethodsPBMC were separated from peripheral blood samples of 43 patients with BD and 23 controls. Then, cells were cultured in RPMI 1640 complemented with 5% FBS, 20% patient’s plasma, 2mM of glutamine and antibiotics during 24h in presence or absence of either anti-IL-6, anti-TGF-β (1/20) or IL-17 (20pg/ml). IL-6, TGF-β and IL-17 were measure by ELISA sandwich; NO was measured by a modified Griess method and urea was measured by a modified Berthelot method. Statistical analysis was performed using ANOVA method. ResultsWe observed a significant increase in IL-6 and TGF-β concentrations in patients’ plasma when compared to controls (p<0.01). In contrast, only few patients in early phase showed a slight but significant increase of IL-17 production (p<0.05). In vitro IL-6 and/or TGF-β neutralization also showed different results depending on the clinical manifestations. Furthermore, IL-17 addition induced two major responses. It reduced significantly NO and urea production in ocular and vascular impairments while it increase their production during nervous and rheumatoid manifestations (p<0.01). ConclusionIn conclusion, our results showed heterogeneous presence of IL-17/Th17 responses during BD. Th1 responses seems to be the main physiopathological mechanism implicated in the disease’s acute phases.

新型假单胞菌对羟基苯乙腈水解酶及其性质研究

腈水解酶催化的腈水解具有反应高效、条件温和、环境污染小和成本低等优点，在有机合成、材料合成、医药、食品、农业、畜牧业及环境等污染方面有着重要的应用前景。本研究利用初步活化和分步胁迫富集，通过Berthelot法高通量筛选与高压液相精细筛选获得一株底物对4-羟基苯乙腈具有较好的催化活性的菌株；经过培养基初步优化，产酶量达到28.47 U/ml；铜离子对该酶具有较强的抑制作用，酶学性质研究表明该菌株能够在pH 6.2~pH 7.3之间酶活性能够保持在最高酶活性的80%以上，在35℃~45℃范围内催化活性大于最大酶活性的80%，反应18 h后离心菌体二次催化几乎不丧失活性；该菌株在开发对羟基苯乙腈合成对羟基苯乙酸具有较高的开发价值。 Nitrilases can hydrolyze nitrile efficiently under mild conditions. The enzymatic methods have the advantages of less pollution, low cost compared with the chemical methods. Nitrilases are potentially applied in agriculture, industry, environment, and biomedicine. In this study, Berthelot method and high performance liquid chromatography were used to screen new stains for nitrilases. A nitrilase with high substrate specificity for 4-hydroxyphenylcyanide was found from Pseudomonas sp. 6-1. The stain produced 28.47 U/ml nitrilase after optimization of the culture conditions. The enzyme remained 80% activities at pH 6.6 to pH 7.6, temperature 35˚C to 45˚C, and it was stable after 18 h incubation. The stain can be potentially used in biosynthesis 4-Hydroxyphenylacetic acid using 4-hydroxyphenylcyanide as substrate.

Phase Diagram of Thermotropic Liquid Crystal Including Negative Pressure Region Generated in Metal Berthelot Tube

Phase diagrams including absolute negative pressure regions of thermotropic liquid crystals give useful information on science and technology. A phase diagram was depicted for ca. 40mg of a thermotropic liquid crystal in a pressure vs. temperature (P-T) plane by the Berthelot method using a metal tube. N-I phase transitions occurred even under-10MPa, and a polymorphism of the crystalline phase was observed.

Assessment of some renal indices in people occupationally exposed to lead

Exposure to lead has been reported to have adverse health implications. An assessment of renal function in people occupationally exposed to lead was carried out using the following biochemical markers urea, creatinine, sodium, potassium, chloride and bicarbonate. A total of 53 test subjects (mean age 30.9 ± 7.7) were randomly selected among some workers occupationally exposed to lead in Osogbo city and 42 apparently healthy subjects (mean age 30.1 ± 1.2) were used as controls. The plasma urea, creatinine, chloride and bicarbonate concentration were determined using modified Berthelot method, Jaffe's reaction, Schales and Schales method and back titration methods, respectively. The plasma sodium and potassium concentrations were determined using flame emission spectrophotometry while blood lead level was also determined using atomic absorption spectrophotometry. The result showed significant increases in mean plasma concentration of creatinine (84.9 ± 13.6-97.4 ± 28.7 μmol/L), sodium (131.9 ± 3.9-134.8 ± 3.7 mmol/L) and chloride (98.2 ± 4.0-100.4 ± 3.9 mmol/L) in test subjects when compared with controls (p < 0.05). Furthermore, significant increases (p < 0.01) were observed in mean plasma concentration of urea (4.7 ± 1.2-5.7 ± 1.3 mmol/L) and blood lead levels (18.5 ± 3.5-69.7 ± 13.2 mg/L) in test subjects in comparison with controls. In contrast, there were no significant differences observed when mean plasma potassium and bicarbonate levels in test subjects were compared with controls (p > 0.05). These results indicate that occupational exposure to lead may compromise renal function.

Eliminating amino acid interference during spectrophotometric NH4+ analysis

Abstract Amino acids can interfere with NH4+ in spectrophotometric NH4+ determination hampering accurate quantification of the fate of NH4+ and dissolved organic N in soils. Serious interference has been reported for soils rich in organic matter, and for soils that have been fumigated, oven-dried or fertilized where between 5 and 60% of the NH4+ detected could be attributed to amino acid interference. We investigated whether a combination of gas diffusion and the classical Berthelot method can eliminate this interference, increasing the selectivity of the NH4+ analysis. We tested this approach using synthetic amino acid solutions and a large set of terrestrial samples (n = 353), including pore water samples, (fumigated or dried) soil extracts, and extracts of manures, composts and crop residues. The evaluated method produced accurate (recovery > 99.7%) and reproducible (standard error = 2.2%) NH4+ concentrations, eliminating any interference between amino acids and NH4+ (interference