A deoxyribonuclease which requires nucleoside triphosphate from Micrococcus lysodeikticus. I. Purification and characterization of the deoxyribonuclease activity.
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Adenosine Triphosphate↗
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Evaluation of neutrophil labeling techniques using the chemotaxis radioassay.
Neutrophils isolated from human blood were labeled by various methods and exposed to a chemotactic gradient. The chemotactically functional cells that migrated into the gradient were isolated. The portion of radioactivity of the original cell suspension carried with the chemotactically responsive cells was related to the relative number of migrating cells as determined microscopically. Of the radionuclides used, P-32 diisopropylfluorophosphate (DFP), In-111 oxine, and Tc-99m sulfur colloid provided cell preparations with the highest relative portion of radioactivity confined to functionally intact (chemotactic) neutrophils. Results with Na2(51)CrO4 and with SnCl2-reduced 99mTcO4- were less than optimal. Neutrophils exposed to Ga-67 citrate apparently took up the label and retained chemotactic responsiveness. However, little or no radioactivity was detected in the neutrophils that migrated from the suspensions of Ga-67-labeled cells. The results indicate that the chemotaxis radioassay can yield unique information pertaining to the extent to which a radiotracer is specifically associated with viable neutrophils in a suspension of labeled cells.
Chemotaxis, Leukocyte↗
High-pressure ion source combined with an in-axis ion trap mass spectrometer. 2. Application of selective low-pressure negative ion chemical ionization
Negative ion chemical ionization was carried out using a quadrupole ion trap mass spectrometer with selected reactant negative ions, primarily injected from a homemade dual EI/CI external ion source. Hence, selective ion/molecule reactions were provided according to the reaction time, which induce a greater control over bimolecular ionization mechanisms than in conventional a high-pressure ion source combined with beam instruments, where several competitive ionization processes take place mainly due to source conditions (e.g., temperature, pressure, and repeller). By selecting the reactant ions, ion/molecule reactions were specifically produced (i.e., charge exchange, proton transfer, nucleophilic substitution, and/or alpha-beta elimination) with several organic target compounds. Gas-phase reactivity of phosphorus- and nitrogen-containing compounds (such as phosphonates as representative for chemical warfare agents and phosphorothionates, phosphorodithionates, and triazines for pesticides) as well as dinitro aromatic compounds (for pesticides) has been explored, in the present work, to ensure further unambiguous detection.
Journal Article↗
River water quality and pollution sources in the Pearl River Delta, China.
Some physicochemical parameters were determined for thirty field water samples collected from different water channels in the Pearl River Delta Economic Zone river system. The analytical results were compared with the environmental quality standards for surface water. Using the SPSS software, statistical analyses were performed to determine the main pollutants of the river water. The main purpose of the present research is to investigate the river water quality and to determine the main pollutants and pollution sources. Furthermore, the research provides some approaches for protecting and improving river water quality. The results indicate that the predominant pollutants are ammonium, phosphorus, and organic compounds. The wastewater discharged from households in urban and rural areas, industrial facilities, and non-point sources from agricultural areas are the main sources of pollution in river water in the Pearl River Delta Economic Zone.
Agriculture↗
Effect of some organic phosphorus and carbamate pesticides on Streptomyces scabies.
Of all the organic phosphorus and carbamate pesticides, tested on Streptomyces scabies, Thimet, Chlorothion, Dithane M-45, and Karathane, were effective at relatively low concentrations (1, 20, 16, and 115 ppm). Minimal inhibitory concentrations of these pesticides were the same in vitro as well as in vivo. The other organic phosphorus and carbamate compounds tested were less effective under the laboratory conditions of these tests.
Carbamates↗
[Effect of salt supplements on lipid growth and synthesis by yeast cultivated on peat oxidates].
The accumulation of biomass and lipids and their fatty acid composition were investigated during cultivation of the yeast Candida tropicalis and Lipomyces lipoferus on peat oxidates supplemented with inorganic compounds containing nitrogen, phosphorus, potassium and magnesium. The absence of additional sources of the above elements from the nutrient substrate inhibited the culture growth. In order to optimize cultivation of lipid synthesizing yeast on peat oxidates, the above compounds should be added in certain concentrations.
Ascomycota↗
Analysis of the antiepileptic phenyltriazine compound lamotrigine using gas chromatography with nitrogen phosphorus detection.
A method is described for the determination of lamotrigine in serum or plasma, based on gas chromatography with nitrogen-phosphorus detection. The method requires minimal sample preparation. The drug is extracted from 1.0 ml of serum at pH 11 into butylacetate containing prazepam as internal standard. An aliquot of the organic phase is then injected onto an HP-5 fused silica capillary column and analyzed with temperature programming from 90 degrees to 250 degrees C. Lamotrigine is characterized by a relative retention time of 0.832 (+/-0.03) compared with prazepam. The method is competitive with the reported high-performance liquid chromatography procedures in terms of precision and sensitivity. Coefficients of variation, calculated from the results of between-run reproducibility tests, were 6.7%, 4.6%, 4.8%, and 6.2% for samples spiked with 0.20, 1.21, 2.42 and 10.84 micrograms/ml lamotrigine, respectively. The lower limit of quantitation of the method is 0.15 microgram/ml. The proposed procedure can be integrated easily in a comprehensive toxicology screening.
Anticonvulsants↗
[The role of nitrogen and phosphorus in pollution of animal origin].
Despite some variability in the data, the author has been able to establish the average characteristics of animal wastes, and to formulate an overall view of nitrogen and phosphorus wastes originating from livestock, in order to compare them with other wastes. Nitrogen is originally present mainly in the form of dissolved ammonia, whereas phosphorus is present in inorganic particles. Ammonium nitrogen is toxic for the aquatic fauna and, in favourable conditions, can be oxidised into nitrates and nitrites, which are undesirable constituents, capable of affecting the health of consumers. Phosphorus and nitrogen compounds in excess of the requirements for soil fertilisation are responsible, among other things, for degrading the quality of surface water, leading to eutrophication.
Animals↗
Does a sterically bulky group occupy the equatorial site in trigonal bipyramidal phosphorus?
[structure: see text] The sterically bulky tert-butyl group occupies an apical position in trigonal bipyramidal phosphorus in the compound [CH2(6-t-Bu-4-Me-C6H2O)2]P(t-Bu)(1,2-O2C6Cl4) in contrast to the occupation of an equatorial position by the small methyl group in [CH2(6-t-Bu-4-Me-C6H2O)2]P(Me)(1,2-O2C6Cl4); this observation contradicts the familiar "apicophilicity rules" for trigonal bipyramidal phosphorus. Low-temperature solution 31P NMR spectra of [CH2(6-t-Bu-4-Me-C6H2O)2]P(R)(1,2-O2C6Cl4) (R = Me, Et, and n-Bu) show the presence of more than two isomers.
Journal Article↗
ATP synthesis in sarcoplasmic reticulum.
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Acetates↗
[The pathogenesis of toxic liver lesions in workers in phosphorus production].
Data of an examination of 600 workers of the phosphorus industry and experimental findings indicate that of major importance in the pathogenesis of toxic lesions of the liver in chronic intoxication with yellow phosphorus and its compounds are disorders of the fatty metabolism developing due to inhibition of oxidation-reduction processes.
Animals↗
Post-mortem glycolysis in ox skeletal muscle. Effect of temperature on the concentrations of glycolytic intermediates and cofactors.
1. Post-mortem changes in the concentrations of the following compounds in ox sternomandibularis muscles stored in nitrogen at 1 degrees , 5 degrees and 15 degrees are reported: P(i) creatine phosphate, hexose monophosphates, fructose diphosphate, triose phosphates, alpha-glycerophosphate, phosphoglycerates, lactate, ATP, ADP, AMP, NAD(+) and total nucleotides. Some results obtained with muscles stored at 37 degrees are included. 2. At the time the muscles were placed at controlled temperatures (about 1.5hr. post mortem) the phosphorus in the compounds measured accounted for 91+/-6% (s.d.) of the total acid-soluble phosphate. 3. The results indicated that at all temperatures the activities of the phosphorylase and phosphofructokinase steps limited the rate and the extent of post-mortem glycolysis. 4. The large variations in hexose monophosphate concentrations during storage indicated that the ratio of phosphorylase to phosphofructokinase activity varied considerably with time and temperature. 5. Between 3.5 and 7hr. post mortem the rates of glycolysis and of ATP turnover were not slower at 5 degrees that at 15 degrees , and were probably faster at 1 degrees . The significance of this finding is discussed.
Animals↗
The most potent organophosphorus inhibitors of leucine aminopeptidase. Structure-based design, chemistry, and activity.
A new class of very potent inhibitors of cytosol leucine aminopeptidase (LAP), a member of the metalloprotease family, is described. The X-ray structure of bovine lens leucine aminopeptidase complexed with the phosphonic acid analogue of leucine (LeuP) was used for structure-based design of novel LAP inhibitors and for the analysis of their interactions with the enzyme binding site. The inhibitors were designed by modification of phosphonic group in the LeuP structure toward finding the substituents bound at the S' side of the enzyme. This resulted in two classes of compounds, the phosphonamidate and phosphinate dipeptide analogues, which were synthesized and evaluated as inhibitors of the enzyme. The in vitro kinetic studies for the phosphinate dipeptide analogues revealed that these compounds belong to the group of the most effective LAP inhibitors found so far. Their further modification at the P1 position resulted in more active inhibitors, hPheP[CH(2)]Phe and hPheP[CH(2)]Tyr (K(i) values 66 nM and 67 nM, respectively, for the mixture of four diastereomers). The binding affinities of these inhibitors toward the enzyme are the highest, if considering all compounds containing a phosphorus atom that mimic the transition state of the reaction catalyzed by LAP. To evaluate selectivity of the designed LAP inhibitors, additional tests toward aminopeptidase N (APN) were performed. The key feature, which determines their selectivity, is structure at the P1' position. Aromatic and aliphatic substituents placed at this position strongly interact with the LAP S1' binding pocket, while a significant increase in binding affinity toward APN was observed for compounds containing aromatic versus leucine side chains at the P1' position. The most selective inhibitor, hPheP[CH(2)]Leu, binds to LAP with 15 times higher affinity than to APN. One of the studied compounds, hPheP[CH(2)]Tyr, appeared to be very potent inhibitor of APN (K(i) = 36 nM for the mixture of four diastereomers). The most promising LAP inhibitors designed by computer-aided approach, the phosphonamidate dipeptide analogues, were unstable at pH below 12, because of the P-N bond decomposition, which excluded the possibility of determination of their binding affinities toward LAP.
Animals↗
Nutrient balance in a paddy field with a recycling irrigation system.
We studied nutrient balance in a paddy field that had a recycling irrigation system and evaluated the effect of the irrigation system on nutrient balance during the irrigation period, from April to August 2002. Chemical fertilizer was the main input of phosphorus; the soil absorbed about 56% of it. The amount of nitrogen supplied by the irrigation system was higher than in a representative paddy field, and the amount of nitrogen fertilizer used was decreased because the irrigation water was partly reused. About 20% of applied nitrogen was lost by denitrification. The net outflows of phosphorus and nitrogen were -0.37 and -3.98 kg ha(-1), respectively. These results indicate that our study paddy field performed well in removing phosphorus and nitrogen compounds from runoff water. A recycling irrigation system can be considered an effective way of reducing the amounts of water and fertilizer used and reducing the outflow nutrients.
Conservation of Natural Resources↗
The reaction of N-nitroso compounds with 2,4-bis (4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide. New aspects of the destruction of the N-nitroso function.
In connection with work on 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (I), used for thiation of carbonyl compounds, different kinds of compounds with semipolar bondings have been reacted with I, especially C- and N-nitroso compounds. C-Nitroso compounds give azoxy and azo compounds. N-Nitroso compounds give new phosphorus ring systems, depending on the starting material, and the N-nitroso function is destroyed. An elimination of HNO has been observed where there was resonance stabilization in the imine formed.
Chemical Phenomena↗
Synthesis of 5-methylaminomethyl-2-selenouridine in tRNAs: 31P NMR studies show the labile selenium donor synthesized by the selD gene product contains selenium bonded to phosphorus.
An enzyme preparation from Salmonella typhimurium catalyzes the conversion of 5-methylaminomethyl-2-thiouridine in tRNAs to 5-methylaminomethyl-2-selenouridine when supplemented with selenide and ATP. Similar preparations from a Salmonella mutant strain carrying a defective selD gene fail to catalyze this selenium substitution reaction. However, supplementation of the deficient enzyme preparation with the purified selD gene product (SELD protein) restored synthesis of seleno-tRNAs. In the absence of the complementary enzyme(s), the SELD protein catalyzes the synthesis of a labile selenium donor compound from selenide and ATP. 31P NMR studies show that among the products of this reaction are AMP and a compound containing selenium bonded to phosphorus. The reaction is completely dependent on the addition of both selenide and magnesium. The dependence of reaction velocity on ATP concentration shows sigmoidal kinetics, whereas dependence on selenide concentration obeys Michaelis-Menten kinetics indicating a Km value of 46 microM for selenide.
Adenosine Monophosphate↗
SYNTHESIS OF N-PHOSPHORYLATED DERIVATIVES OF NITROGEN MUSTARDS WITH LATENT CYTOTOXICITY.
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Animals↗
A pH 7 buffer devoid of nitrogen, sulfur, and phosphorus for use in bacteriological systems.
Apparent pK values were determined for a series of commercially available carboxylic acids in a search for a buffer suitable for bacterial studies at pH 7 in media free from nitrogen, sulfur, and phosphorus. Of the compounds possessing pK' values near pH 7,3,6-endomethylene-1,2,3,6-tetrahydrophthalic acid (EMTA) was chosen as possessing suitable physical properties, cost, and purity for biological use. Aerobacter aerogenes and Escherichia coli grew normally in its presence but did not utilize it as a sole source and energy. Although good turbidimetric data could not be obtained, Pseudomonas aeruginosa responded in the same qualitative way. Therefore, EMTA promises to be useful in work on endogenous metabolism and in nutritional studies.
Acids↗