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PubMed1991

Assessment of the automated colorimetric and the high-performance liquid chromatographic methods for nicotine intake by urine samples of smokers' smoking low- and medium-yield cigarettes.

We have compared the high-performance liquid chromatographic method with the direct barbituric acid test in an assessment of nicotine exposure. The effect of the endogenous colour in urine on the direct barbituric acid method was also studied. The applicability of methods was evaluated with urine samples from 15 smokers who smoked 5, 10 and 20 low- and medium-nicotine cigarettes per day. Assessments of nicotine intake with the methods were well correlated, although the high-performance liquid chromatographic method detects only cotinine and the direct barbituric method most of the nicotine metabolites. Before endogenous colour subtraction in the DBA method the correlation coefficient was 0.558 and after that 0.784. Both methods indicated similar changes in nicotine exposure with the change of brand and also a dose dependent relationship to the number of cigarettes smoked. The coefficients of variation for both of the methods were 3.4%. The endogenous colour determination lessened the capacity of direct barbituric acid method to one half being about 150 samples per day. With the high-performance liquid chromatographic method the capacity was about 50 samples per working day.

Acetanilides↗
PubMed2001

Barbiturase, a novel zinc-containing amidohydrolase involved in oxidative pyrimidine metabolism.

Barbiturase, which catalyzes the reversible amidohydrolysis of barbituric acid to ureidomalonic acid in the second step of oxidative pyrimidine degradation, was purified to homogeneity from Rhodococcus erythropolis JCM 3132. The characteristics and gene organization of barbiturase suggested that it is a novel zinc-containing amidohydrolase that should be grouped into a new family of the amidohydrolases superfamily. The amino acid sequence of barbiturase exhibited 48% identity with that of herbicide atrazine-decomposing cyanuric acid amidohydrolase but exhibited no significant homology to other proteins, indicating that cyanuric acid amidohydrolase may have evolved from barbiturase. A putative uracil phosphoribosyltransferase gene was found upstream of the barbiturase gene, suggesting mutual interaction between pyrimidine biosynthesis and oxidative degradation. Metal analysis with an inductively coupled radiofrequency plasma spectrophotometer revealed that barbiturase contains approximately 4.4 mol of zinc per mol of enzyme. The homotetrameric enzyme had K(m) and V(max) values of 1.0 mm and 2.5 micromol/min/mg of protein, respectively, for barbituric acid. The enzyme specifically acted on barbituric acid, and dihydro-l-orotate, alloxan, and cyanuric acid competitively inhibited its activity. The full-length gene encoding the barbiturase (bar) was cloned and overexpressed in Escherichia coli. The kinetic parameters and physicochemical properties of the cloned enzyme were apparently similar to those of the wild-type.

Amidohydrolases↗
PubMed1964

NUTRITIONAL REQUIREMENTS OF BACILLUS POPILLIAE.

Sylvester, Charles J. (Michigan State University, East Lansing), and Ralph N. Costilow. Nutritional requirements of Bacillus popilliae. J. Bacteriol. 87:114-119. 1964.-Bacillus popilliae grew consistently well in a semisynthetic medium containing a "vitamin-free," salt-free, acid hydrolysate of casein supplemented with dextrose, dl-tryptophan, and thiamine. However, when the casein hydrolysate was replaced with a complete array of amino acids, no growth occurred. The addition of barbituric acid to this synthetic medium resulted in consistent growth. A number of purines, pyrimidines, and other nitrogen-containing compounds were tested, but none was found that would replace barbituric acid. In synthetic media, B. popilliae was found to require biotin, thiamine, and 11 amino acids for growth. Three additional amino acids were stimulatory. Preliminary studies indicated that the nutritional requirements of B. lentimorbus, another species known to be pathogenic for Japanese beetle (Popillia japonica) larvae, were similar to those for B. popilliae.

Amino Acids↗
PubMedDate not supplied

[Fatal poisoning due to narcotic abuse in the analytic-toxicological practice of Forensic Medicine Department Silesian Medical Academy in Katowice in years 1996-202].

147 cases of fatal poisonings in people due to narcotic abuse examined in the Forensic Medicine Department Silesian School of Medicine, Katowice in the years 1996-2002 have been presented in the paper. In the group examined there were 126 males and 21 females at the age of 16-44. Opium narcotics were found in 139 out of 147 cases and amphetamine derivatives in 18. Opiates were indicated in 58 individuals and amphetamine only in 8. In 35 poisoned people opiates with barbituric acid derivatives were found. In 3 cases death resulted after taking opiates and amphetamine derivatives. 1 individual died after taking opiates and substances of the phenothiazine group. In the organic fluids of 18 people opiates and medicines being derivatives of 1,4-benzodiazepine and barbituric acid were found. Amphetamine and derivatives of 1,4-benzodiazepine were found in 6 individuals and opiates, barbiturates, benzodiazepines and amphetamine in 1 individual. Concentrations of all the substances indicated ranged widely and were as follows: < 0.10-17.40 > microgram/ml for opiates; < 0.24-30.00 > microgram/ml for amphetamine; < 0.12-1.90 > microgram/ml for 1.4-benzodiazepine derivatives and < 0.18-15.24 > microgram/ml for barbituric acid derivatives. Ethanol was found in 18 individuals and its concentration was < 0.2-2.5 >@1000.

Adolescent↗
PubMed1983

Structure-pharmacokinetic relationships among the barbiturates in the rat.

The pharmacokinetics of a congeneric series of barbituric acids were determined after i.v. administration of individual barbiturates or multicomponent barbiturate mixtures to chronically cannulated male rats. The concentration of barbiturate in plasma and urine was determined using reversed-phase high-performance liquid chromatography. A biexponential equation adequately fitted the plasma-concentration time data. The volume of distribution remained relatively constant within the series. Binding to plasma proteins varied enormously, increasing with lipophilicity. Accordingly, the volume of distribution based on unbound drug also increased with lipophilicity, reflecting a corresponding greater tissue affinity. Total clearance formed a relatively complex nonlinear relationship with lipophilicity. Although the affinity of the barbiturates for erythrocytes increased with lipophilicity, the relationship between total blood clearance and lipophilicity offered no simplification. Renal clearance, the minor route of elimination for the majority of the homologs, decreased with increasing lipophilicity, due to increased tubular reabsorption, whereas nonrenal (hepatic) clearance produced a nonlinear relationship with lipophilicity similar in form to that of total clearance. The nonlinearity of the hepatic clearance within the series was explained by a hepatic blood flow limitation, for the highest homologs, and by the stereochemistry of position 5 on the barbituric acid ring, for the lowest homologs.

Animals↗
PubMed1986

A simple, inexpensive urine test of smoking.

Three novel colorimetric methods of detecting urinary nicotine metabolites called the barbituric acid, diethylthiobarbituric acid (DETB) and DETB-extraction methods were evaluated for use as a simple cheap objective test of smoking. Urine samples were collected from 103 male smokers and 78 male nonsmokers working at two London factories. The smokers recorded the number of cigarettes smoked over the previous 36 hours. All three methods correctly classified the smokers. The DETB-extraction method had a lower false-positive rate (averaging 3% on morning and afternoon urine samples) than either the DETB or barbituric acid methods (12% and 6% respectively) and was the best procedure for classifying subjects as 'smokers' or 'non-smokers'. Using a quantitative variant of the barbituric acid method, there was a significant correlation (r = 0.85, p less than 0.001) between the urinary nicotine metabolites/creatinine ratios and number of cigarettes smoked. However, the ratios for smokers of 6-15, 16-25, and 26 or more cigarettes overlapped considerably. The methods can be performed very rapidly and reagent costs are equivalent to less than one penny per test.

Barbiturates↗
PubMed1985

A simple, inexpensive urine test of smoking.

Three novel colorimetric methods of detecting urinary nicotine metabolites called the barbituric acid, diethylthiobarbituric acid (DETB), and DETB extraction methods were evaluated for use as a simple, cheap, objective test of smoking. Urine samples were collected from 103 male smokers and 78 male non-smokers working at two London factories. The smokers recorded the number of cigarettes smoked over the previous 36 hours. All three methods correctly classified the smokers. The DETB extraction method had a lower false positive rate (averaging 3% on morning and afternoon urine samples) than either the DETB or the barbituric acid method (12% and 6% respectively) and was the best procedure for classifying subjects as "smokers" or "non-smokers." When a quantitative variant of the barbituric acid method was used there was a significant correlation (r = 0.85, p less than 0.001) between the ratios of urinary nicotine metabolites to creatinine and the number of cigarettes smoked. The ratios for smokers of 6-15, 16-25, and 26 or more cigarettes, however, overlapped considerably. The methods can be performed very rapidly and the reagent cost is equivalent to less than 1p per test.

Barbiturates↗
PubMed2005

The role of nonsurface-active species at interfacial molecular recognition by melamine-type monolayers.

The main characteristics of Langmuir monolayers are radically changed by molecular recognition of hydrogen bond nonsurface-active species. The change in the thermodynamic, phase, and structural features by molecular recognition of dissolved uracil or barbituric acid by 2,4-di(n-undecylamino)-6-amino-1,3,5-triazine (2C11H23-melamine) monolayers is characterized by combination of surface pressure studies with Brewster angle microscopy (BAM) imaging and Grazing incidence X-ray diffraction (GIXD) measurements. Phase behavior of the 2C11H23-melamine monolayer and morphology of the condensed phase domains are changed drastically, but in a specific way, by molecular recognition of uracil or barbituric acid. The main characteristics of the interfacial system can be essentially affected by the kinetics of the recognition process. Pure 2C11H23-melamine monolayers show only small compact, but nontextured domains. The monolayers of 2C11H23-melamine-uracil assemblies develop well-shaped circular condensed-phase domains having an inner texture with alkyl chains essentially oriented parallel to the periphery and having a striking tendency to two-dimensional (2D) Ostwald ripening. The 2C11H23-melamine-barbituric acid monolayers form large homogeneous areas of condensed phase that transfer at smaller areas per molecule to a homogeneous condensed monolayer. BAM imaging of corresponding assemblies with ((CH3(CH2)11O(CH2)3)2-melamine having modified alkyl chains demonstrates the specific effect of the monolayer component. GIXD results reveal that molecular recognition of pyrimidine derivatives gives rise only to quantitative changes in the two-dimensional lattice structure. The striking differences in the main characteristics between the supramolecular species are related to their different chemical structures. Quantum chemical calculations using the semiempirical PM3 method provide information about the different nature of the hydrogen-bonding-based supramolecular structures.

Journal Article↗
PubMed2005

Effect of interfacial molecular recognition of non-surface-active species on the main characteristics of monolayers.

Recent progress in studies of the main characteristics of supramolecular assemblies formed by interfacial molecular recognition between an amphiphilic monolayer and a non-surface-active species, which is dissolved in the aqueous subphase, by complementary hydrogen bonding and/or electrostatic interaction at the air-water interface is reviewed. Systems consisting of an amphiphilic melamine-type monolayer and an pyrimidine derivative dissolved in the aqueous subphase are representative model systems for molecular recognition on the basis of complementary hydrogen bonding. Most of the studies have been performed with 2,4-di(n-undecylamino)-6-amino-1,3,5-triazine (2C11H23-melamine) monolayers as host component and thymine, uracil or barbituric acid as dissolved non-surface-active pyrimidine derivatives. The combination of surface pressure studies with Brewster angle microscopy (BAM) imaging and Grazing incidence X-ray diffraction (GIXD) measurements is optimal for the characterization of the change in structure and phase behavior at the interfacial recognition process. The molecular recognition of all pyrimidine derivatives dissolved in the aqueous subphase changes drastically and in a specific way the characteristic features (pi-A isotherms, morphology of the condensed phase domains) of the 2C11H23-melamine monolayer. The small condensed phase domains of the pure 2C11H23-melamine monolayer are compact without an inner texture. The monolayers of the supramolecular 2C11H23-melamine entities with thymine or uracil form specifically well-shaped condensed phase domains with an inner alkyl chain texture essentially oriented parallel to the periphery. The completely different morphology of the 2C11H23-melamine-barbituric acid monolayers is characterized by the formation of large homogeneous areas of condensed phase that transfer at smaller areas per molecule to a homogeneous condensed monolayer. The striking differences in the main characteristics between the supramolecular entities are related to their different chemical structures: complementary hydrogen bonding of two thymine or uracil molecules by one 2C11H23-melamine molecule and a linearly extended hydrogen bonding network between 2C11H23-melamine and barbituric acid. The high values of hydrogen bonding energy obtained by quantum chemical calculations on the basis of the semi-empirical PM3 method state the high stability of the supramolecular entities. The GIXD results reveal that the formation of hydrogen-bond based superstructures between the polar head groups of the amphiphilic 2C11H23-melamine monolayer and the non-surface-active pyrimidine derivatives gives rise only to quantitative changes in the two-dimensional lattice structure of the alkyl chains. The alternative possibility to construct interfacial molecular recognition systems on the basis of acid-base interaction is demonstrated by the experimental results obtained by molecular recognition of the heptadecyl-benzamidinium chloride monolayers with dissolved non-surface-active phenylacetate ions. The formation of supramolecular assemblies causes also drastical changes of the surface features in these systems. Here, the development of a substructure in the condensed phase domains consisting of long filigree strings and the favoured formation of bilayers overgrowing the strings indicates a linearly extended amidinium-carboxylate interfacial structure of the base and acid component in alternating sequence.

Hydrogen Bonding↗
PubMed2003

Electrostatic interaction of pi-acidic amides with hydrogen-bond acceptors.

Interactions between N-methylacetamide (NMA) and N-methylated derivatives of uracil, isocyanurate and barbituric acid have been studied using ab initio methods at the local MP2/6-31G** level of theory. The results were compared to similar interactions between the oxygen atom of NMA and the pi-clouds of perfluorobenzene, quinone and trimethyltriazine. The pi-acidic amides of isocyanurate and barbituric acid were found to interact with a hydrogen bond acceptor primarily through electrostatic attractions. These groups may be used as alternatives of a hydrogen bond donor to complement a hydrogen bond acceptor or an anion in molecular recognition and drug design. Examples of such interactions were identified through a search of the CSD database.

Amides↗
PubMed1982

[Stereoselectively different cardiovascular effects of the enantiomers of 2 N-methylated barbiturates in the rat].

The (-)-enantiomers of 1-methyl-5-phenyl-5-propyl barbituric acid (MPPB) and 1-methyl-5-phenyl-5-butyl barbituric acid (MPBB) injected i.v. depress blood pressure and heart rate of rats to a fourfold higher degree than the (+)-enantiomers. These stereoselectively different actions on blood pressure and heart rate are abolished after pretreatment with reserpine. Stereoselective differences are not existent with regard of the negative inotropic action (isolated left atrium and papillary muscle), the negative chronotropic action (isolated right atrium) and the blockade of tension development induced by noradrenaline at the isolated ductus deferens. The enantiomers of MPPB and MPBB exhibit stereoselectively different influence on the sympathetic outflow of intact rats during barbiturate-induced hypotension and bradycardia: 1 min after injection the efferent activity of neck sympathetic nerve is increased only if the (+)-enantiomers are given (twofold of the control). 5 min after application only in the presence of the (-)-enantiomers a slight increase of the efferent activity is observed.

Animals↗
PubMed2005

Polymorphism in an unexpected caesium complex of 5-hydroxyhydurilic acid.

Vigorous reaction of barbituric acid with caesium hydroxide in water resulted in an unexpected coupling product, 5-hydroxyhydurilic acid, complexed to caesium, giving poly[[caesium-mu5-5-hydroxyhydurilato] hemihydrate], {[Cs(C8H5N4O7)].0.5H2O}n. This was obtained in two different polymorphic forms, depending on the method of crystal growth. Slow solvent evaporation yielded an orthorhombic polymorph, (I), which crystallized in the space group Pnab (non-standard setting of Pbcn), with the uncoordinated water molecule lying on a crystallographic twofold axis. The water molecule is sandwiched into cavities within the structure and is securely held in place by N-HO and O-HO hydrogen bonding. Polymorph (II) is monoclinic, although the unit-cell parameters are similar to those of polymorph (I), and it crystallizes in the space group C2/c, with the uncoordinated water molecule again lying on the twofold axis and secured by hydrogen bonding. The differences between the two polymorphs, both of which have nine-coordinate caesium and a similar first-shell environment of all structural components, are in the overall arrangement of the cations, anions and water molecules, and in the shape of the cavities, revealed by inspecting and comparing crystal-packing diagrams.

Journal Article↗