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At least 379 records · Page 21Linked to original sources
PubMed2002

Effects of formulation on the run-off of imidacloprid from turf.

Imidacloprid is a pesticide often used to control insect pests on residential lawns and golf courses. To investigate its potential to be transported into non-target aquatic systems by rainfall events, imidacloprid was applied as 5.0 g kg-1 GR and 750 g kg-1 WP to 12 plots planted with bermuda grass set on a 5% slope. The dimethylamine salt of the herbicide 2,4-D was applied simultaneously to the plots in order to normalize the results to prior trials conducted with other pesticides. At a rate of 2.5 cm h-1, 5-cm rainfall events were simulated at 24 and 48 h after application and 2.5-cm events were simulated at 96 and 192 h. After each event water was collected from each plot and analyzed by HPLC for residual insecticide or herbicide. Approximately 1.4% of the insecticide formulated as WP and 1.9% of that formulated as GR was lost from the plots after four run-off events. Of the total mass lost, 64% and 30% respectively occurred in the first and second run-off events for the WP formulation versus 75% and 20% for the GR formulation. These values compare with a total mass export of 2.6% for 2,4-D, of which 95% and 4% of the loss occurred respectively in the first and second run-off events. The maximum concentration of imidacloprid detected in run-off water was 0.49 mg litre-1 and occurred during the first run-off event.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1989

Fast-atom bombardment and thermospray mass spectrometry for the characterization of two glucuronide metabolites of methapyrilene.

Two conjugated metabolites of methapyrilene hydrochloride isolated from mouse-hepatocytes were examined by mass spectrometry using fast-atom bombardment (FAB) and thermospray ionization. The major metabolite, methapyrilene glucuronide, was identified based on a prominent peak due to the protonated molecule as well as the loss of the dimethylamine and sugar moieties. Identification of the second metabolite was complicated by large signals associated with the biological sample matrix. The complementary nature of the fragmentation observed in the mass spectra using FAB and thermospray ionization allowed this metabolite to be identified as the desmethylmethapyrilene glucuronide. The fragmentation observed using FAB ionization was not greatly affected by the presence of the glucuronide moiety. While loss of the sugar moiety indicated a glucuronide, additional fragmentation confirmed the presence of the underlying ethylenediamine substructure which is characteristic of this class of antihistamines.

Animals↗
PubMed2004

A mass spectrometry based method for distinguishing between symmetrically and asymmetrically dimethylated arginine residues.

The arginine methylation of proteins is involved in several important cellular activities, most notably transcriptional control. Arginine dimethylation can take two distinct forms, symmetric and asymmetric, catalyzed by different classes of enzymes. To establish a method for the mass spectrometric identification and characterization of this post-translational modification, we analyzed synthetic peptides with symmetrically or asymmetrically methylated arginine residues by electrospray ionization tandem mass spectrometry. We observed abundant characteristic ions at [M+nH-31](n+) and [M+nH-70](n+) in spectra of symmetrically methylated peptides and at [M+nH-45](n+) in spectra of asymmetrically methylated peptides. We speculate these ions arise from neutral loss of monomethylamine, dimethylcarbodiimide, and dimethylamine, respectively. These characteristic ions allowed the rapid identification of a symmetrically arginine-dimethylated peptide from myelin basic protein and a symmetrically arginine-dimethylated peptide from SmD3 co-immunoprecipitated with the methyltransferase-associated protein pICln, suggesting that this method may provide a rapid means to screen for and characterize dimethylarginine sites.

Amino Acid Sequence↗
PubMed2005

Mass spectrometric studies of the formation and reactivity of trans-[PtCl2(Am)(piperidinopiperidine)] x HCl complexes with ubiquitin.

trans-[PtCl2(Am)(pip-pip)] x HCl complexes, where Am = ammine, methylamine and dimethylamine, react with ubiquitin to form 1:1 covalent adducts. The platinum complexes bind exclusively to Met1 of ubiquitin forming trans-[PtCl(S-Met1-Ub)(Am)(pip-pip)] adducts. These adducts are reactive towards nucleophiles and react with deoxyguanosine (dGMP) to form the ternary trans-[Pt(dGMP)(S-Met1-Ub) (Am)(pip-pip)] complex which is stable in water and even in the presence of excess glutathione (GSH). Reaction of trans-[PtCl(S-Met1-Ub)(Am)(pip-pip)] with GSH resulted in the rapid formation of the ternary complex trans-[Pt(GS)(S-Met1-Ub)(Am)(pip-pip)] which was not stable and slowly lost the platinum moiety; after 7 days the platinum moiety was completely removed and the native ubiquitin was regenerated.

Binding Sites↗
PubMed2006

Investigation of several unique tandem mass spectrometric fragmentation patterns of NFDEIDR, an orcokinin analog, and its N-terminal dimethylated form.

Orcokinins are a family of myotropic neuropeptides widely present in various decapod crustaceans and insect species. The majority of the orcokinins identified to date share a conserved sequence of NFDEIDR at their N-termini. Electrospray ionization quadrupole time-of-flight tandem mass spectrometric (ESI-QTOF-MS/MS) analysis of doubly charged orcokinin precursor ions reveals the presence of a y(n - 1) + 10 peak, which is more intense than that for the y(n - 1) ion. To elucidate the identity of this novel fragment ion and understand the mechanism underlying this fragmentation, we employed a combined approach involving the use of isotopic N-terminal dimethylation, methyl esterification, and isotope-encoded NFDEIDR. Comparison of the fragmentation patterns of these chemically modified orcokinin analogs allowed the determination of the structure of the y(n - 1) + 10 ion as y(n - 1) + CO--H2O. The yx + CO--H2O ions, along with the yx + CO and yx + CO--NH3 ions, are also present in the MS/MS spectra of NFDEIDR and several other peptides. Additionally, we report two other unusual fragmentation ions in the MS/MS spectra of N-terminal dimethyl NFDEIDR (2+), which yields the novel fragment ions of the y(n - 1) + 38 ion and the [M+2H-59]2+ ion. These two ion series involve the neutral loss of the asparagine side chain. The same sets of ions are also present in other peptides with dimethyl-modified asparagines at the N-terminus. The competition between the side-chain loss and loss of dimethylamine is described. The loss of the side chain of N-terminal dimethyl Asp1 is reported as well. We also report for the first time the neutral loss of ammonia from the N-terminal amino group of Asn1 and the loss of CO2 from the side chain of aspartic acid.

Formaldehyde↗
PubMed2000

Microscale synthesis of dextran-based multivalent N-linked oligosaccharide probes.

We developed a convenient method for the synthesis of dextran-based multivalent probes containing N-linked oligosaccharides which is efficient even in a small scale. Oligosaccharides were derivatized with succinic dihydrazide and dimethylamine borane under a mild acidic condition. The derivatized oligosaccharides were then conjugated in a good yield to periodate-oxidized dextran (500 kDa). Thus, the conjugates containing 120 to 140 oligosaccharide chains per dextran molecule were successfully synthesized. Their practical advantage was shown by the example that the asialofetuin oligosaccharide-dextran conjugate has much higher affinity to Ricinus communis agglutinin (RCA-I) than asialofetuin oligosaccharide itself or asialofetuin. The conjugates were further labeled with fluorescent reagent or biotinylation reagent containing a hydrazino group by the use of the unreacted aldehyde groups of the oxidized dextran, yielding probes with similar densities of fluorophores or biotin groups. Direct binding of the biotinylated asialofetuin oligosaccharide-dextran probe to RCA-I coated on the titer plate at a concentration of 50 ng/50 microl was easily detected using 50 fmol (as oligosaccharides) of the probe. The method for the synthesis of dextran-based oligosaccharide probes will facilitate the investigation of carbohydrate-mediated molecular interactions based on the native oligosaccharide structures.

Asialoglycoproteins↗
PubMed2002

1H NMR analysis for metabolites in serum and urine from rats administrated chronically with La(NO3)3.

1H NMR spectroscopy has been used to assess long-term toxicological effects of a rare earth. Male Wistar rats were administrated orally with La(NO3)3 at doses of 0.1, 0.2, 2.0, 10, and 20 mg/kg body wt, resp., for 3-6 months. Urine was collected at 1, 2, and 3 months and serum samples were taken after 6 months. Numerous low-M(r) metabolites in rats serum and rats urine, including creatinine, citrate, glucose, ketone bodies, trimethylamine N-oxide (TMAO), and various amino acids, were identified on 400- and 500-MHz 1H NMR spectra. La3+-induced renal and liver damage is characterized by an increase in the amounts of the excreted ketone bodies, amino acids, lactate, ethanol, succinate, TMAO, dimethylamine, and taurine and a decrease in citrate, glucose, urea, and allantoin. Information on the molecular basis of the long-term toxicity of La(NO>3)3 was derived from the abnormal patterns of metabolite excretions. An assay of some biochemical indexes and analysis of some enzymes in plasma supported NMR results.

Amino Acids↗
PubMed1996

Comparative subchronic and chronic dietary toxicity studies on 2,4-dichlorophenoxyacetic acid, amine, and ester in the dog.

Forms of 2,4-dichlorophenoxyacetic acid (2,4-D) are herbicides used in the control of a wide variety of broadleaf and woody plants. Subchronic toxicity studies in dogs were conducted on three forms of 2,4-D: the parent form, 2,4-D acid (ACID); 2,4-D dimethylamine salt (DMA); and 2,4-D 2-ethylhexyl ester (2-EHE). The three studies were designed to allow for comparison of the toxicity of the three forms. Doses in the subchronic studies, on an acid equivalent basis, were 0, 0.5 (ACID only), 1.0, 3.75, and 7.5 mg/kg/day. Treatment related findings in the three studies included reductions in body weight gain, and food consumption, and minor increases in blood urea nitrogen, creatinine, and alanine aminotransferase. The data from the three subchronic studies demonstrated the comparable toxicity of ACID, DMA, and 2-EHE and support a subchronic no observed adverse effect level (NOAEL) of 1.0 mg/kg/day for all three forms. Due to the similarity in toxicity of the three forms of 2,4-D, a 1-year chronic toxicity study was performed on the parent ACID to fully characterize the potential toxicity of 2,4-D in the dog. ACID was well tolerated at doses of 0, 1.0, 5.0, and 7.5 mg/kg/day. The clinical pathology alterations were similar to those seen in the subchronic studies and were not progressive. The histopathology alterations observed were not severe in nature and the no observed effect level in the chronic study was determined to be 1.0 mg/kg/day. There was no indication of any immunotoxic or oncogenic response in the studies. In conclusion, the findings of these studies indicate comparable toxicity among representative forms of 2,4-D and their generally low toxicity following subchronic and chronic dietary exposure in the dog.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1994

Metabolism of dodecyldimethylamine by Pseudomonas MA3.

Pseudomonas MA3 was isolated from activated sludge on the basis of its capacity to use dodecyldimethylamine as a sole carbon (C) and energy source. Dodecylamine, dodecanal, dodecanoic acid and acetic acid also supported growth of Pseudomonas MA3. Dodecyldimethylamine-grown cells oxidized a wide range of alkylamine derivatives, dodecanal, dodecanoic acid and acetic acid. Degradation of the alkyl chain of dodecyldimethylamine by Pseudomonas MA3 appeared from the stoichiometric liberation of dimethylamine. A dehydrogenase catalysed the cleavage of the Calkyl-N bond. The first intermediate of the proposed degradation pathway, dodecanal, accumulated in the presence of decanal used as a competitive inhibitor. The second intermediate, dodecanoic acid, was formed in the presence of acrylic acid during the degradation of dodecyldimethylamine. Dodecanal was converted into dodecanoic acid by a dehydrogenase and dodecanoic acid was then degraded via the beta oxidation pathway.

Amines↗
PubMed1978

Kinetic studies on the formation of nitrosamines I. Formation of dimethylnitrosamine in aqeous solution of perchloric acid.

The kinetics of nitrosation of dimethylamine (DMA) in aqueous perchloric acid solution have been studied using a differential spectrophotometric technique. The rate law is Initial rate = e[DMA]0 [nitrite]2 0 [H+]/(f + [H+])2 where [DMA]0 and [nitrite]0 represent initial stoichiometric concentrations. At 310.0 K and mu = 2.0 M, e = (2.2 +/- 0.2) X 10(-5) M-1 s-1 and f = (1.28 +/- 0.02) X 10(-3) M. The associated activation energy is 56 +/- 3 kJ mol-1. A clear inhibition of the nitrosation rate by ionic strength has been observed in which only the kinetic parameter (f) has an effective change. It is concluded that under the experimental conditions of this work only the dinitrogen trioxid is the effective carrier for the nitrosation.

Dimethylnitrosamine↗
PubMed1991

Biological monitoring of 2,4-dichlorophenoxyacetic acid-exposed workers in agriculture and forestry.

This is a report on the application of a radioimmunoassay (RIA) for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in biological monitoring of occupationally exposed sprayers. Urinalysis was conducted on two workers involved in spraying 2,4-D sodium salt solution with car mounted ground rigs in agriculture and on the pilot and the mixer-loader of a helicopter crew applying 2,4-D dimethylamine salt for brush control in forestry. All sprayers showed detectable quantities of 2,4-D in morning urine samples voided over 4 or 6 days in the post-spraying period. The highest 2,4-D urinary concentrations of about 2.5 ppm could be measured in a car driver on the 3 day after exposure. The 2,4-D level in urine was much lower in forestry workers, with 0.365 ppm for the mixer-loader and 0.052 ppm for the pilot on the 1 day after spraying. Urinary 2,4-D concentrations in the agricultural study were adjusted for endogenous creatinine and, when normalized for body weight, resulted in a total 2,4-D uptake of about 5.7 or 84.9 micrograms/kg body wt. for a single spraying operation. Thus, the calculated absorbed dose was less than the NOAEL (no observed adverse effect level) of 10 mg/kg body weight per day by a large margin of safety. Further, the calculated amounts excreted seemed to be sufficiently reliable to be used for assessing the risk of human exposure to 2,4-D. However, more studies are desirable for confirmation of the association of urinary 2,4-D and creatinine excretion. Clearance occurs with a 12-h to 22-h half-life.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1981

Utilization of amines by yeasts.

461 Strains of the yeast collection of the Centraalbureau voor Schimmelcultures (CBS) were screened for their ability to utilize 9 different amines as a sole carbon and energy source and/or as nitrogen source. A miniaturized technique with microtiter plates was used. None of the primary and methylated amines tested (i.e. methylamine, dimethylamine, trimethylamine, tetramethylammonium chloride, choline, ethylamine, propylamine, butylamine and benzylamine) were utilized as a carbon and energy source, although the majority of yeasts (86%) were able to utilize one or more of these compounds as a nitrogen source. The ability to utilize ethylamine and higher homologues occurred more frequently than the ability to utilize methylated amines. In almost all genera the utilization of primary and methylated amines was found, with utilization among yeasts and the inability of these organisms to utilize amines as a carbon and energy source is discussed.

Amines↗
PubMed1982

Plasma levels of parent drug and metabolites in the intravenous aminopyrine breath test.

[Dimethylamine-14C]-aminopyrine was given i.v. to 5 healthy volunteers and 5 medical patients in a dose of 1.67 mg/kg, containing 0.02 micro Ci/kg 14C. In 4 volunteers the experiment was repeated using oral administration of aminopyrine. Exhalation of 14CO2 was followed for 6-10 h and plasma levels of the drug and of its metabolites 4-methylamino-antipyrine, 4-amino-antipyrine, 4-acetylamino-antipyrine, 4-formylamino-antipyrine, were measured by thin-layer chromatography. The concentration-time profiles of the metabolites mostly failed to conform to a Bateman function. Areas under the curves from 1 to 6 h after dosing indicated distinct interindividual differences in metabolite patterns even in the absence of disturbed liver function, whereas the intraindividual data were closely reproducible. In most subjects, the area of formylamino-antipyrine exceeded that of the acetyl analogue. The metabolite patterns did not exhibit a consistent relationship to the ratios between 14CO2 half-life in breath and aminopyrine half-life in plasma, which varied from 1.4 to 3.2.

Adult↗
PubMed1984

Assessment of drug metabolism in hepatic disease: comparison of plasma kinetics of oral cyclobarbital and the intravenous aminopyrine breath test.

The exhalation of 14CO2 derived from an i.v. tracer dose of [dimethylamine-14-C]aminopyrine has been investigated in normal controls and patients. They subsequently ingested 200 mg cyclobarbital calcium in the evening and the decline in the plasma drug level over the following 2 days was measured by thin-layer chromatography. The peak specific activity of exhaled 14CO2 occurred 0.5-2 h after 14C-aminopyrine injection in the absence of liver disease and in non-cirrhotic liver disorders. It was delayed in certain patients with cirrhosis. Compared to 8 medically healthy subjects, 10 patients with acute viral hepatitis, 8 with cirrhosis and 10 with fatty liver exhibited a significantly increased half-life of 14CO2 exhalation. Normal mean values were found in 12 patients with non-cirrhotic alcoholic liver disease and in 14 patients with non-hepatic diseases. The cyclobarbital (CB) half-life was prolonged and the clearance reduced in patients with viral hepatitis, cirrhosis or alcoholic liver damage as compared to data from 17 control subjects. Due to a larger apparent volume of distribution, patients with fatty liver disease had an increased CB half-life, although its clearance was normal. A close negative correlation was detected between the clearance and the logarithm of the CB level measured 36 h after drug ingestion. The oral CB test evaluated from a single blood sample taken about 36 h after drug administration appears to be a useful indicator of human drug metabolising capacity. Discrimination between patients with and without disordered liver function was similar in the two drug elimination tests.

Adolescent↗
PubMedDate not supplied

Behavioral indicators of sublethal toxicity in rainbow trout.

Four measures of behavior--spontaneous swimming activity, swimming capacity, feeding behavior, and vulnerability to predation--were assessed as indicators of sublethal toxicity in rainbow trout (Oncorhynchus mykiss) in 96-hr exposures to sublethal concentrations of six agricultural chemicals: carbaryl, chlordane, dimethylamine salt of 2,4-dichlorophenoxyacetic acid (2,4-DMA), tributyl phosphorotrithioate (DEF), methyl parathion, and pentachlorophenol. After exposures, behavioral changes consistently demonstrated sublethal toxicity, but effects on specific behaviors varied with contaminants and their concentrations were altered by the water quality criterion concentration for chlordane (2 micrograms/L), and at a concentration of DEF (5 micrograms/L) that had previously been shown to inhibit growth and survival after a 90-day exposure. Feeding behavior was inhibited most by exposure to DEF, 2,4-DMA, and methyl parathion. Vulnerability to predation was heightened most by exposure to carbaryl and pentachlorophenol. Although all chemicals inhibited spontaneous swimming activity, only carbaryl, DEF, and 2,4-DMA influenced swimming capacity.

Animals↗
PubMed1995

Denaturation of fish proteins during frozen storage: role of formaldehyde.

Proteins of fish muscle undergo chemical and physical changes during frozen storage which may result in, under certain conditions (i.e. long periods of storage, poor freezing practices, temperature fluctuations, etc), loss of quality, reflected mainly by an unacceptable texture as well as an undesirable flavour, odour and colour. In frozen gadoid fish species, most of these changes are caused by the production of formaldehyde in the muscle. Formaldehyde is produced, along with dimethylamine, by the enzymatic reduction of trimethylamine oxide (TMAO). Many aspects of formaldehyde production by TMAO demethylase (TMAOase) have been studied throughout the last decade. In addition, different approaches have been used to investigate the effect of formaldehyde production on protein denaturation and the associated muscle textural changes. Some insight into the reaction between protein and formaldehyde has clarified the possible mechanism of formaldehyde-mediated denaturation. However, evidence of covalent bonding between proteins and formaldehyde, to form crosslinks, has not explained fully the changes observed in fish proteins during frozen storage. The study of cold-induced denaturation of proteins might give new clues for further investigation of the problem. The implications of formaldehyde in toxicological and nutritional issues is also reviewed, as general concern about the safety of food products is a growing field in food science. Finally, different approaches have been proposed to avoid the detrimental action of formaldehyde during frozen storage of gadoid fish; they are some of the practical applications of the knowledge acquired after years of study of different workers in the field.

Animals↗
PubMed1979

Liver function in physically trained subjects: galactose elimination capacity, plasma disappearance of indocyanine green, and aminopyrine metabolism in long-distance runners.

Physical exercise and physical training are known to affect several aspects of hepatic metabolism. To assess whether adaptation to long-lasting exercise modifies microsomal drug metabolism, 8 long-distance runners were compared with a group of medical students having significantly lower maximal rates of oxygen consumption. At rest the hepatic galactose elimination capacity and the indocyanine green plasma disappearance rate used as reference methods were the same in both groups. The plasma clearance of ([14C]dimethylamine) aminopyrine and the kinetics of 14CO2 in breath did not differ either. It is concluded that adaptation to long-lasting exercise can occur without evidence for changes in hepatic galactokinase activity, liver blood flow, or microsomal metabolism of aminopyrine.

Adaptation, Physiological↗
PubMed2001

Re-evaluation of the effect of smoking on the methylation of N-terminal valine in haemoglobin.

In view of the established extrapulmonary cancer sites targeted by smoking a multiplicity of compounds and mechanisms might be involved. It has been debated that smoking caused increased incidence of N-methylvaline at the N-terminus of haemoglobin. Because this could indicate a relevance of methylating nitrosamines in tobacco smoke, data are presented from an industrial cohort of 35 smokers and 21 non-smokers repeatedly monitored between 1994 and 1999. In general, N-methylvaline adduct levels in haemoglobin of smokers were approximately 50% higher than those of non-smokers. The smoking-induced methylation of haemoglobin is likely to be caused by dimethylnitrosamine (N-nitroso-dimethylamine), a major nitrosamine in side-stream tobacco smoke. The biomonitoring data emphasise the potential value of N-methylvaline as a smoking-related biomarker and call for intensified research on tobacco smoke compounds that lead to macromolecular methylation processes.

Cohort Studies↗