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At least 757 records · Page 42Linked to original sources
PubMed2002

Prediction of adsorption from multicomponent solutions by activated carbon using single-solute parameters. Part II--Proposed equation.

Prediction of multicomponent adsorption is still one of the most challenging problems in the adsorption field. Many models have been proposed and employed to obtain multicomponent isotherms from single-component equilibrium data. However, most of these models were based on either unrealistic assumptions or on empirical equations with no apparent definition. The purpose of this investigation was to develop a multicomponent adsorption model based on a thermodynamically consistent equation, and to validate that model using experimental data. Three barbiturates--phenobarbital, mephobarbital, and primidone--were combined to form a ternary system. The adsorption of these barbiturates from simulated intestinal fluid (without pancreatin) by activated carbon was studied using the rotating bottle method. The concentrations, both before and after the attainment of equilibrium, were determined with a high-performance liquid chromatography system employing a reversed-phase column. The proposed equation and the competitive Langmuir-like equation were both fit to the data. A very good correlation was obtained between the experimental data and the calculated data using the proposed equation. The results obtained from the original competitive Langmuir-like model were less satisfactory. These results suggest that the proposed equation can successfully predict the trisolute isotherms of the barbituric acid derivatives employed in this study.

Adsorption↗
PubMed2003

Synthesis of pyrimidine derivatives possessing an antioxidative property and their inhibitory effects on picryl chloride-induced contact hypersensitivity reaction.

We conducted a preliminary structure-activity relationship (SAR) study of some barbituric acid and uracil derivatives against the picryl chloride-induced contact hypersensitivity reaction. The introduction of an antioxidative moiety to the side chain of the C(6)-position of uracil was effective against this model. The introduction of dimethoxyphenol (8b) or dimethylphenol (8c) instead of di-t-butylphenol (8a) as an antioxidative moiety gave diminished activities, so, the reactive oxygen would contribute to the inflammation of this model, and an antioxidative activity was required for exhibiting the inhibitory activity. The inhibitory activity was significantly affected by the substituent at the N(1)-phenyl moiety.

Animals↗
PubMed1986

Intestinal accumulation of urea in germ-free animals--a factor in caecal enlargement.

To examine the connection between caecal size and urea concentration in the caecal contents urease inhibition was tested in conventional animals and urea and urease were administered to germ-free rats and mice. Administration of alloxan and barbituric acid and immunization with urease led to slightly larger caeca in conventional animals. Neomycin treatment caused a clear enlargement of the caecum. In germ-free animals urease administration led to a reduction in the caecal size, whereas urea in the drinking water caused enlargement. The urea concentration and the urease activity in the caecal contents correlated well with the caecal weights.

Animals↗
PubMed1981

[Epilepsy and chronic Chagas disease].

The epileptic syndrome in chronic Chagas' disease is rarely reported in neurological literature. At the present time many papers have demonstrated that histopathological basis of Chagas' disease is a neuronal destruction. The authors studied 167 epileptic patients; 44 out of them had a chronic form of the disease. It was made a comparison of semiologic data between the two groups, and also the evaluation of the therapeutic results with anticonvulsant drugs. The chagasic patients had the onset of epileptic seizures later than the control group, with great predominance of partial seizures of autonomic type. The neurologic examination and cerebrospinal fluid test revealed moderate rates of disturbances, but not sufficient to characterize a neurologic syndrome. The EEG study was performed in 15 of the 44 cases and revealed a suggestive pattern of a diffuse cerebral damage in half of patients. Anticonvulsant therapy based on use of phenylhydantoin, barbituric acid derivates, primidone and benzodiazepines, showed that control of epileptic seizures in Chagas' diseases is more difficult and requires greater quantities of drugs than in the control group.

Adolescent↗
PubMed2005

A new objective method to compare different color reactions for the detection of cyclic ureides.

Modifications of the Zwikker- and Parri color detection tests were examined and compared according to their ability to distinguish between nine different barbituric acids and hydantoins. These tests comprised the formation of complexes with cobalt(II) and copper(II) salts and organic amines. Using the color palette introduced herein, the evaluation of the tests could be reduced to a simple yes/no decision on the basis of only seven defined colors. Suitable components for the color tests could be selected from the thirty six modifications.

Journal Article↗
PubMed2004

Assessment of smoking status among workers using an improved colorimetric method.

To monitor smoking status among workers, we improved the colorimetric method to detect cotinine and other nicotine metabolites in urine. In adding ethanol in the reaction mixture, the quantitative measurable time defined as the duration with more than 95% of the peak absorbance, extended to 80 min in contrast to 16 min in the original method. As the analytical condition, a aliquot of urine sample (0.5 ml) was mixed with 0.5 ml of ethanol, with 0.2 ml of 4 M acetate buffer (pH: 4.7), with 0.1 ml of 150 mM KCN, with 0.1 ml of 0.44 M chloramin and then with 0.5 ml of 78 mM barbituric acid. A linear relationship was observed between cotinine concentration up to 80 microM and absorbance at 508 nm (r=0.998, p<0.01). Mean levels of nicotine metabolites among non smokers and smokers were 4.9 and 47.4 microM cotinine equivalent, respectively. Sensitivity and specificity were 96.1% and 96.7%, respectively for nicotine metabolites concentration among workers (n=385) when adopting 6.9 microM cotinine equivalent as a cut off value and the area under the ROC curve was 0.982. This method can be applicable to quantitative detection of smoking status.

Colorimetry↗
PubMed1990

Circadian distribution of proteins in urine from healthy young men.

Urine samples were collected at 3-hr intervals over a single 24-hr period from each of seven clinically healthy men who ranged in age from 21-25 years. Urines at each collection time were subsequently pooled using 20% of each volume and serially dialyzed against ammonium-barbituric acid buffer (pH 7.35 +/- 0.02), using a cellulose membrane permeable to compounds of less than 12,000-14,000 molecular weight (mw). When the dialyzed portions were then analyzed for total proteins, the sum of proteins in eight pools amounted to 74 mg. A 1 ml aliquot of each pool, representing approximately 50 micrograms of proteins, was concentrated and reconstituted. Approximately 20 micrograms of reconstituted proteins were then subjected to polyacrylamide gel electrophoresis. The stained gel was then scanned by laser densitometry and planimetry. Each aliquot revealed eight segments as identified by Coomassie and silver staining. Their molecular weights, estimated by extrapolation from concurrently run protein standards, and their total protein amounts were: 116,000 mw (9.44 mg), 91,000 mw (3.3 mg), 68,000 mw (11.58 mg), 53,000 mw (2.58 mg), 43,000 mw (9.12 mg), 32,000 mw (7.13 mg), 24,000 mw (4.52 mg) and 20,000 mw (5.27 mg). A statistically significant rhythm (P = 0.022 from ANOVA and 0.011 from Single Cosinor) was found for the excretion of total proteins, with an acrophase in the afternoon (1537) for these diurnally-active subjects.

Adult↗
PubMed1999

Synthesis and biological screening of new 1,3-diphenylpyrazoles with different heterocyclic moieties at position-4.

1,3-Diphenyl-1 H-pyrazole-4-carboxaldehyde (1) was reacted with barbituric acid, thiobarbituric acid, some activated nitriles and/or acetophenone to give the condensation products 2a, b, 3a-c and 4, respectively. The reaction of 1 with hydrazine hydrate, semicarbazide or thiosemicarbazide afforded the corresponding azomethines 5a-c. The compounds 3a, b, 4 and 5a, c were subjected for different sequence reactions to produce the title compounds. The antibacterial and antifungal activity of some selected derivatives were evaluated.

Anti-Bacterial Agents↗
PubMed1999

Lipid peroxidation in leukaemia.

OBJECTIVE: Free radicals have been implicated in the pathogenesis of leukaemias, so the degree of lipid peroxidation was studied as a marker of disease activity in patients of leukaemia. METHODS: Lipid peroxidation product malonyldialdehyde (MDA) was estimated in serum from 30 patients of leukaemia by thio-barbituric acid reaction before and after chemotherapy. There were 10 patients of acute myeloid leukaemia (AML), 5 with acute lymphocytic leukaemia (ALL), 15 with chronic myeloid leukaemia (CML) of which 10 were in chronic stable phase and 5 in blast crisis. Twenty healthy age and sex matched individuals served as control. RESULTS: There was a significant increase in MDA levels in AML and ALL patients and serum MDA levels were higher in the active phase of disease than in remission. We observed a direct correlation between peripheral leucocyte counts and MDA levels. In CML, MDA levels were higher, more so in the patients who were in blast crisis. Patients of CML blast crisis who achieved remission showed a significant decrease in MDA levels as compared to those without remission. CONCLUSION: We observed a significant increase in MDA levels in active phase of acute as well as chronic leukaemia than those in remission. The proposed mechanism for high MDA is that myeloid cells are a major source of superoxide and other oxygen metabolites which lead to lipid peroxidation. MDA estimation in leukaemia can be of help in detecting type of leukaemia, response of therapy, and to predict the chances of relapse.

Case-Control Studies↗
PubMed1998

[The correlative study on nitric oxide and cotinine nicotine metabolite in smokers' urine].

OBJECTIVE: In order to observe the changes of nitric oxide (NO) affected by smoking and their relationship in vivo. METHOD: 60 male nonsmoker as the control group, 192 male smoked as the study group which was divided into 4 subgroups (1-10, 11-20, 21-30 and > 30) according to the number of cigarettes smoked per day. The metabolite of nicotine-cotinine in urine was assayed by means of barbituric acid. Cotinine was used as an objective indicator to reflect the smoking quantity. The urinary NO (NO2.-) was determined with colorimetric estimation. RESULT: The urinary cotinine level in the 4 subgroups were 6.6 +/- 1.6, 25.1 +/- 6.2, 37.8 +/- 8.5, 53.6 +/- 8.3 (mumol/L) respectively. The urinary NO of nonsmokers were 4.43 +/- 0.97 (mumol/L), in the 4 subgroups it was 3.04 +/- 0.07, 2.75 +/- 0.05, 2.18 +/- 0.01, 1.60 +/- 0.01 (mumol/L) respectively. The results of statistical analysis between the 4 subgroups were t = 4.2894, P < 0.01; t = 2.7446, P < 0.01; t = 2.7667, P < 0.01 accordingly. As compared between the 4 subgroups of smokers and the nonsmokers, the statistical results were t = 2.7118, P < 0.01; t = 3.1826, P < 0.01; t = 3.2100, P < 0.01; t = 4.6600, P < 0.01; respectively. The statistical differences between the 4 subgroups were t = 2.9286, P < 0.01; t = 3.0357, P < 0.01; t = 3.8181, P < 0.01; t = 2.2160, P < 0.05 respectively. There was a good positive correlation between the number of cigarette smoked and urinary cotinine content (r = 0.8626, P < 0.01), also a significant negative correlation between it and urinary NO level (r = -0.6596, P < 0.05). A negative correlation could be observed between urinary cotinine and NO (r = -0.6026, P < 0.05). CONCLUSION: With the increase of quantity and duration of smoking, the NO content in vivo will decrease, suggested that the vascular endothelial cells could be damaged severely.

Adult↗
PubMed1975

[When cholangiocholecystography should and should not be performed].

Little-know contraindications for i.v. cholangiocholecystography with water-soluble hexaiodated contrast media are presented. Particular reference is made to suspected cholecystic lithiasis and dysprotidaemic patients or those undergoing treatment with sulphamides, salicylic acid, barbiturates, etc. Lastly, reference is made to the suitability of cholegraphy in suspected acute cholecystitis. Here, in fact, this method is preferable to oral cholecystography.

Biliary Tract Diseases↗
PubMed2001

Urine test for the assessment of smoking status.

A simple, quick and inexpensive test for smoking status would be useful in a variety of settings. The non-polar barbituric acid derivative 1,3-dibutyl-2-thiobarbituric acid (DBTB) is described as a novel derivatisation reagent for nicotine and its metabolites in the König reaction to assess smoking status. The relative performance of qualitative methods for assessing smoking status using DBTB and the previously employed derivatisation reagent 1,3-diethyl-2-thiobarbituric acid (DETB), as well as quantitatively-based methods for determining 'total nicotine metabolites' (TNMs) using these two reagents, were evaluated against a cotinine-based radioimmunoassay (RIA) as the 'gold standard'. Clinical sensitivity and specificity for all the approaches studied were in excess of 94%. Simple qualitative assessment by eye was superior to quantitatively-based measures of smoking status. Correlation between estimation of nicotine metabolites using DBTB, DETB and RIA were good. The most efficient and convenient method to distinguish between smokers and non-smokers was the simple qualitative method using the more lipophilic reagent DBTB.

Biomarkers↗
PubMed1976

Ultramicro gas-chromatographic analysis for anticonvulsants, with use of a nitrogen-selective detector.

We describe a procedure for determining phenobarbital, primidone, and diphenylhydantoin simultaneously in 50-mul volumes of serum by use of gas chromatography and a detector with heightened sensitivity and selectivity for nitrogenous compounds. The drugs, together with an internal standard, 5-allyl-5-phenyl barbituric acid, are extracted from serum by the procedure of MacGee [Anal. Chem. 42, 421 (1970)]. The drugs are converted to their methyl derivatives by a modification of the procedure of Greeley [Clin. Chem. 20, 192 (1974)] and then analyzed on a column containing 3% OV-1, with a temperature program, and detected by a nitrogen-selective detector. The method is reproducible to about 7%. Sensitivities of 0.5 mg/liter for 50-mul serum samples are attained routinely. Mephobarbital interferes with the analysis because methylation yields the same product as methylated phenobarbital. Total analysis time for a single sample is 15 min.

Chromatography, Gas↗
PubMedDate not supplied

[Analytical problems in examination of small amounts of blood samples taken from law offenders].

In the paper there have presented results of the analysis of small blood samples taken routinely from 3 cases after car accidents and 1 rapist. Fluorescence polarisation immunoassay (FPIA, Abott) was used for screening examinations of narcotics from the group of both opium and cocaine alkaloids, barbituric acid and benzodiazepine and also drugs from the group of tricyclic antidepressants. Confirmation of the obtained results and full identification of the substances analysed were carried out by liquid chromatography with mass spectrometry (LC-MS). In the causes of car accidents components of "compote" were found (poppy straw extract) morphine and codeine (1 case), cocaine (1 case) and also tramadol and diazepam (1 case) were also found. In the rapist methylenedioxymethamphetamine (MDMA) was determined.

Accidents, Traffic↗
PubMedDate not supplied

[Effect of psychotropic and anticonvulsant preparations on the conformational transitions in transport ATPase].

The effect of neuroleptics, antidepressants, somnifacients and antiepileptic drugs on Na+- and K+-dependent transitions in the preparation of the transport ATP-ase from renal tubules of the guinea pig were looked into by using the spinal probes procedures. Neuroleptics inhibit most strongly (by 100--67 per cent) the conformant transition in the Na+- K+-dependent ATP-ase, their action manifesting itself to a greater extent with respect to the K+-dependent conformant transitions. The influence of antidepressants is close to that of the neuroleptics, although it is noticeably less intensive (78--46 per cent). The action of hypnotics (barbituric acid derivatives) and of antiepileptic drugs of a different chemical structure closely approaches, but is different from the effect of neuroleptics and antidepressants, both as concerns its intensity and the lack of any essential differences in the action upon the Na+- and K+-dependant conformant transitions.

Adenosine Triphosphatases↗
PubMed1991

[A photometric method of analysis of cyanides].

The contributors propose a selective photometric technique for detection of sodium and potassium cyanides in different washings, sewage, overalls extraction. The technique was based on the formation of a polymetyne dye, and barbituric acid and pyridine reactions. It proved efficient in detecting the cyanides within 0.01-0.054 mg/dm3, 1-100 mg/l, 0.08-1.24 mg/dm3 with deviations not exceeding 23%. Duration of the test was limited to 25-30 min.

Hand Disinfection↗
PubMed1991

[Urinary cotinine as a marker for passive tobacco smoking].

To provide an objective measure of the hazard smoking parents represent to their children's health, continue concentration in urine was measured by the colorimetric method using barbituric acid (DBA). A total of 205 children, aged 10-12, were examined. The results of laboratory tests were correlated with the data collected by interview. A significant difference in the average value of cotinine concentration was demonstrated between the children whose parents did not smoke (3.2 mumol/L) and those whose one parent smoked (5.8 mumol/L). An even larger concentration was recorded when both parents smoked (7.8 mumol/L). The largest cotinine concentration was determined in the urine of children--passive smokers whose both parents smoked and who did not have a room of their own (9.2 mumol/L). The difference in cotinine concentration between girls and boys was not statistically significant.

Child↗
PubMed1991

Purification and characterization of yeast orotidine 5'-monophosphate decarboxylase overexpressed from plasmid PGU2.

Orotidine 5'-monophosphate decarboxylase (ODCase) has been overexpressed in yeast 15C cells transformed with a plasmid carrying the URA3 gene that encodes ODCase. Twenty g of cells having ODCase activity equal to 30 mg of pure enzyme per liter of cell culture were obtained after 9 h of galactose induction. To remove yeast proteases, a 60-90% ammonium sulfate fractionation step plus the addition of EDTA as an inhibitor of metallopeptidases was necessary. The purification protocol yielded ODCase that was protease-free and stable to storage at 4 degrees C for 16 months. The pure enzyme had a specific activity of 40 units/mg in 50 mM phosphate buffer, pH 6, and could be stored at -20 degrees C in 20% glycerol with retention of full activity for more than 2 years. The enzyme had a Km for orotidine 5'-monophosphate of 0.7 microM at pH 6 and 25 degrees C. The molecular weight of the plasmid-derived ODCase monomer determined by electrophoresis on denaturing polyacrylamide gels was 29,500. ODCase sedimented through sucrose density gradients as a monomer of about 30 kDa at low protein concentration and in the absence of ligands that bind at the catalytic site. An increase in the sedimentation rate could be induced by increasing the ODCase concentration or by adding ligands that are competitive inhibitors. ODCase sedimented in a single band typical of a protein of 46 kDa at the highest protein concentration studied or in the presence of 50 mM phosphate or 933 microM substrate (orotidine 5'-monophosphate) or product (UMP). A dimer sedimenting as a protein of about 64 kDa occurred in the presence of 50 microM 6-azauridine 5'-monophosphate or 2 microM 1-(5'-phospho-beta-D-ribofuranosyl) barbituric acid, competitive inhibitors of ODCase. These results resemble the ligand-induced subunit association of the ODCase domain of bifunctional UMP synthase and support the use of yeast ODCase as a model for ODCases from other species.

Binding, Competitive↗