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PubMed2001

Complete mineralization of dodecyldimethylamine using a two-membered bacterial culture.

Complete degradation of dodecyldimethylamine was achieved using a two-membered bacterial culture isolated from activated sludge. One member, identified as Burkholderia cepacia, was capable of degrading the alkyl chain of the molecule. The other member, identified as Stenotrophomonas maltophilia, was able to degrade dimethylamine, the product of the former. Batch culture experiments revealed that the two-membered culture consisting of B. cepacia and S. maltophilia was based on a commensalistic relationship under carbon-limited conditions. Under nitrogen-limited conditions, the relationship of this culture was transformed from a commensalistic to a mutualistic one. A two-membered culture was therefore imperative for growth on dodecyldimethylamine under nitrogen-limited conditions, whereas a pure culture of B. cepacia was capable of growth on dodecyldimethylamine under carbon-limited conditions.

Amines↗
PubMed1980

A convenient preparation of tetrahydropteridines and tetrahydrofolate analogs. Synthesis of tetrahydro-3',5'-dichloromethotrexate.

Tetrahydropteridine enzymatic cofactors and inhibitors may be conveniently prepared by reduction of the aromatic precursors with dimethylamine--borane in glacial acetic acid. A short reaction time at 20-60 degrees C affords tetrahydrofolate analogs in high yield and purity under anhydrous conditions and without protection from air. 3',5'-Dichloromethotrexate is reduced without hydrogenolysis of chlorine.

Boranes↗
PubMed2006

The influence of human neutrophils on N-nitrosodimethylamine (NDMA) synthesis.

N-nitrozodimethyloamine (NDMA) is a carcinogenic compound that can be formed in vivo. NDMA is synthesized from precursors-amines and nitrosating agents. Nitrosating agents are formed through the reaction of oxide, reactive oxygen species and nitric oxide (NO). Human neutrophils (PMN) are an important source of the most reactive oxygen species as well as of the nitric oxide. The increase in oxygen metabolism of PMN can lead to the increase nitrosating agent and nitroso-forms. Inflammatory process is associated with locally decreased pH that may favor nitrosation reaction. In the present study, we estimated the NDMA synthesis by LPS-stimulated PMN in the presence of the iNOS inhibitor--N-nitro-L-arginine methyl ester (L-NAME). In the nitrosation reaction dimethylamine (DMA) was used as substrat. The viability of the cells was measured by cytometric method. NDMA concentrations the culture media was measured by GCMS method. NO production was estimated by Griess's method. Expression of iNOS was determined by western blotting. Results obtained showed that DMA nitrosation is most effective in pH between 3-4.5. Nonstimulated PMN produced lower concentrations of NO than LPS-stimulated cells (1.27 microg/cm3 and 1.57 microg/cm3, respectively). In the culture of nonstimulated PMN supplemented with DMA, there was NDMA (mean--0.99 ng/cm3). In the culture of LPS-stimulated PMN in the presence of DMA, the concentration of NDMA was higher than in the culture of nonstimulated PMN (median--1.45 ng/cm3). In the supernatants of cells incubated without DMA and with DMA, LPS and L-NAME, no NDMA was detected. These results indicate that PMN can be one of sources of nitrosating agents and can play a role in endogenous NDMA synthesis. Stimulation of PMN can lead to the increase of NDMA concentration following the increase of NO production. Different pathological conditions associated with PMN activation as well as the decreased pH may favor endogenous NDMA synthesis.

Cell Survival↗
PubMed1990

Dermal absorption of the phenoxy herbicides 2,4-D, 2,4-D amine, 2,4-D isooctyl, and 2,4,5-T in rabbits, rats, rhesus monkeys, and humans: a cross-species comparison.

Dermal absorption of the 14C-ring-labeled phenoxy herbicides 2,4-D [(2,4-dichlorophenoxy)acetic acid], 2,4-D amine (2,4-dichlorophenoxyacetic acid dimethylamine), 2,4-D isooctyl (2,4-dichlorophenoxyacetic acid isooctyl ester), and 2,4,5-T amine (2,4,5-trichlorophenoxyacetic acid trimethylamine) was examined following topical applications of the herbicides to the back of rabbits, the back and tail of rats, the forearm and forehead of rhesus monkeys, and the forehead of human volunteers. The effect of three pesticide vehicles (water, acetone, and Esteron LV96) was also investigated. The total percent dermal absorption was calculated from the mean percent urinary recoveries from the animal tests and corrected for nonurinary excretion of the radiolabel using data from intramuscular (im) injections. The human data are reported without im correction. The reliability of animal data for modelling human dermal absorption of pesticides is highlighted.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1991

Developmental toxicity of methylamines in mice.

Monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) are endogenous substances as well as metabolites of methyl isocyanate, the chemical involved in the 1984 accident at Bhopal, India. Although methylamines exert several toxic effects including inhibition of protein turnover and oocyte RNA synthesis, their reproductive toxicity has not been investigated. We therefore studied the possible developmental toxicity of these amines using pregnant CD-1 mice and mouse embryo culture as experimental models. Intraperitoneal injections (daily from d 1 to 17 of gestation) of TMA at 2.5 and 5 mmol/kg/d significantly (p less than .001) decreased fetal body weight but not the placental weight or maternal body weight gain; however, 5 of 11 mice treated with 5 mmol/kg TMA died. Similar treatment with DMA and MMA did not exert any obvious maternal or fetal effects. All three methylamines, when added to embryos in culture, caused dose-dependent decreases in size, DNA, RNA, and protein content as well as embryo survival; the order of toxicity was TMA greater than DMA greater than MMA. The ability of methylamines to adversely affect fetal development suggests that these amines, especially trimethylamine, may act as endogenous teratogens under certain conditions.

Animals↗
PubMed1994

Urinary excretion of methylamines in men with varying intake of fish from the Baltic Sea.

Fish contain methylamines, especially trimethylamine N-oxide (TMAO), trimethylamine (TMA), and dimethylamine (DMA). Further, DMA may be formed TMA and TMAO. DMA is a precursor of nitrosodimethylamine (NDMA), which is a potent carcinogen. Levels of DMA, TMA, and TMAO in urine were used as indicators of the dietary exposure and in vivo formation of these amines in 44 men, representing 3 groups with different fish consumption habits. The levels of TMA (median 0.24 mmol/mol creatinine; range 0-2.7) and TMAO (median 38 mmol/mol creatinine; range 8-290) were significantly associated with the weekly intake of fish (r = .47, p = .001, and r = .53, p = .0002, respectively), while no such relation was found for DMA (median 24 mmol/mol creatinine; range 5-46). Further, urinary levels of TMA and TMAO were dependent on recent intake of fish.

Adult↗
PubMed1982

In vivo stability of nitrite and nitrosamine formation in the dog stomach: effect of nitrite and amine concentration and of ascorbic acid.

Formation of N-nitrosodimethylamine (NDMA) from the precursors nitrate and dimethylamine has been studied in the chronically fistulated dog stomach. Measurements have also been made as a function of time for nitrite stability and gastric pH, and a nonabsorbable marker has been used to correct for gastric emptying and dilution. In the fasting animal NDMA forms within minutes after addition of the reactants if the pH is below 5. The presence of food in the stomach slows the reaction, and the additional presence of ascorbic acid greatly depresses the amount of NDMA formed. The concentration of nitrite in gastric juice declines rapidly after its introduction, but the concentration of NDMA declines even more rapidly than nitrite. This suggests that NDMA is probably rapidly absorbed directly from the dog stomach, in contrast to earlier results in rodent experiments.

Absorption↗
PubMed1988

Mono-, di- and trimethylamine in human gastric fluid: potential substrates for nitrosodimethylamine formation.

Nitrosodimethylamine (NDMA) is a potent carcinogen in a wide variety of animal species. In experimental animals, dimethylamine and nitrite, precursors of NDMA, are found in gastric fluid where the acidic conditions are suitable for formation of nitrosamines. In this study we measured the concentrations of mono-, di- and trimethylamine (MMA, DMA and TMA) in gastric fluid from humans, rats, dogs and ferrets, as well as in saliva, blood and urine from humans. Human gastric fluid contained 3.7 +/- 0.4 (SEM) nmol/ml MMA, 12.6 +/- 1.4 nmol/ml DMA and 2.0 +/- 0.4 nmol/ml TMA. MMA, DMA and TMA concentrations in human gastric fluid were similar to those present in human saliva and blood, but were much lower than those present in human urine. The concentrations of these amines in human gastric fluid were lower than those measured in gastric fluid from experimental animals. When we added sodium nitrite to human gastric fluid, NDMA was formed. We have shown that DMA is normally present in human gastric fluid, and that it can be nitrosated to form NDMA.

Animals↗
PubMed1973

Induction of mitotic crossing over in Saccharomyces cerevisiae by breakdown products of dimethylnitrosamine, diethylnitrosamine, 1-naphthylamine and 2-naphthylamine formed by an in vitro hydroxylation system.

Dimethylnitrosamine and diethylnitrosamine, two potent carcinogens, are nonmutagenic when tested directly in microorganisms. Likewise 1-naphthylamine and 2-naphthylamine are also nonmutagenic but the N-hydroxy derivatives are mutagenic in microorganisms. Apparently these compounds require metabolism to breakdown products which are then the proximately active agents, and microorganisms lack the enzymes necessary to effect this conversion. These compounds are mutagenic in Saccharomyces after conversion to breakdown products in an in vitro hydroxylation medium. The induction of mitotic crossing over in Saccharomyces cerevisiae by breakdown products of dimethylnitrosamine, diethylnitrosamine, 1-naphthylamine and 2-naphthylamine formed in the Udenfriend hydroxylation medium is reported in this communication. Mitotic crossing over was detected as red sectored colonies resulting from induced homozygosity of the ade2 marker. Dimethylamine and diethylamine, which lack the nitroso group of the nitrosamines, did not induce mitotic crossing over under any of the test conditions. To further confirm that the induced sectored colonies were the result of mitotic crossing over they were tested for the presence of reciprocal products. The expected reciprocal products were found in over 67% of the isolates tested. The significance and practicality of using mitotic recombination as an indicator of genetic damage potential of chemicals is discussed.

Amines↗
PubMed1984

Polymer support oligonucleotide synthesis XVIII: use of beta-cyanoethyl-N,N-dialkylamino-/N-morpholino phosphoramidite of deoxynucleosides for the synthesis of DNA fragments simplifying deprotection and isolation of the final product.

Various 5'O-N-protected deoxynucleoside-3'-O-beta-cyanoethyl-N,N-dialkylamino-/N- morpholinophosphoramidites were prepared from beta-cyanoethyl monochlorophosphoramidites of N,N-dimethylamine, N,N-diisopropylamine and N-morpholine. These active deoxynucleoside phosphates have successfully been used for oligodeoxynucleotide synthesis on controlled pore glass as polymer support and are very suitable for automated DNA-synthesis due to their stability in solution. The intermediate dichloro-beta- cyanoethoxyphosphine can easily be prepared free from any PC1(3) contamination. The active monomers obtained from beta-cyanoethyl monochloro N,N- diisopropylaminophosphoramidites are favoured. Cleavage of the oligonucleotide chain from the polymer support, N-deacylation and deprotection of beta-cyanoethyl group from the phosphate triester moiety can be performed in one step with concentrated aqueous ammonia. Mixed oligodeoxynucleotides are characterized by the sequencing method of Maxam and Gilbert.

DNA↗
PubMed1976

The importance of prolonged incubation for the synthesis of dimethylnitrosamine by enterobacteria.

Tests with 140 strains representing Escherichia coli, Klebsiella aerogenes, K. ozaenae, Proteus mirabilis, P. vulgaris, P. rettgeri and P. morganii in a defined medium supplemented with 0-09M dimethylamine (DMA) and 0-1M potassium nitrate showed that at least 89% of the 136 strains able to reduce nitrates produced up to 9mM dimethylnitrosamine (DMN) in 70h at 37 degrees C. Four nitratase-negative strains produced DMN from DMA in the presence of sodium nitrate. Prolonged incubation was the most important factor in determining DMN production. Stasis and persistent infection in the urinary tract, by simulating prolonged incubation of a culture, may be of importance in determining whether the potential carcinogen, DMN, could be produced in vivo by bacterial action on DMA and nitrate in urine.

Dimethylamines↗
PubMed1984

Purification and characterization of the rotenone-insensitive NADH dehydrogenase of mitochondria from Arum maculatum.

The non-ionic detergent lauryl dimethylamine N-oxide (LDAO) has been used to extract the NADH dehydrogenases of Arum maculatum mitochondria. Affinity chromatography on 5'-ADP-Sepharose 4B was used to separate the rotenone-sensitive (complex I) NADH dehydrogenase from the rotenone-insensitive NADH dehydrogenase. An 18-fold purification of the rotenone-insensitive NADH dehydrogenase was achieved. The enzyme is specific for NADH with optimal activity around pH 7.2. The apparent Km for NADH is 28 microM, with dichloroindophenol as acceptor at pH 7.2. The rotenone-insensitive NADH dehydrogenase appears to be a flavoprotein and no iron-sulphur centres were detected by electron spin resonance spectroscopy.

Chromatography, Affinity↗
PubMed1987

Photochemical electron transfer reactions in the acceptor complex of reaction centers of Rhodopseudomonas spheroides treated with sodium dodecyl sulfate.

We have compared some photochemical properties of the reaction-center complex of Rhodopseudomonas spheroides (wild-type) treated with various amounts of either sodium dodecyl sulfate (SDS) or dodecyl dimethylamine N-oxide. In the presence of the latter, the native structure and activity of the reaction center are preserved even at high concentrations of detergent. In contrast, SDS denatures the protein. It does this by a cooperative process, as shown by the sigmoidal relationship between primary photochemical activity and SDS concentration. SDS binds to the reaction center at up to about 6 g SDS/g protein. The most notable modifications brought about by low SDS concentrations are: a slowing down of rereduction of P+ by Q-B from 1 s-1 to 0.25 s-1 and, to a lesser extent, of P+ by Q-A; the reoxidation of Q-A and Q-B by N,N,N',N'-tetramethyl-1,4-phenylenediamine is accelerated as an exponential function of SDS concentration. In this case Q-A become more accessible to external acceptors but not Q-B. It is thought that these changes are mainly due to progressive binding of SDS resulting in the unfolding of the protein, probably accompanied by the loss of the metal. Herbicides partly protect the reaction center against SDS denaturation, but their efficiency to block electron transfer between QA and QB is greatly reduced in the altered reaction centers present in the transition region of the denaturation curve. It is concluded that in the early region of the SDS denaturation curve, no dissociation of the reaction center in subunits occurs. In the transition region, it appears that the reaction center reaches the critical state in which mainly dissociation of polypeptide H from the complex of chains L and M and loss of QA take place.

Bacterial Proteins↗
PubMed1976

N-Nitrosamine formation by cultures of several microorganisms.

Of 38 pure cultures of microorganisms tested, only one, Pseudomonas stutzeri, was capable of forming dimethylnitrosamine from dimethylamine and nitrite during growth. Resting cells of P. stutzeri, Cryptococcus terreus, Escherichia coli, and Xanthomonas campestris formed dimethylnitrosamine, although no nitrosamine was found in growing cultures of the latter three organisms. No nitrosamine was produced by either growing cultures or resting-cell suspensions of Pseudomonas fragi or Proteus mirabilis. Boiled cells of P. stutzeri, but not those of C. terreus, E. coli, and X. campestris, formed dimethylnitrosamine, and this nitrosamine was also produced by extracts of E. coli cells at pH 5.0.

Bacteria↗
PubMed2006

Differential regulation of the three methanol methyltransferase isozymes in Methanosarcina acetivorans C2A.

Genetic analysis of the three methanol-specific methyltransferase 1 operons (mtaCB1, mtaCB2, and mtaCB3) in Methanosarcina acetivorans led to the suggestion that each of them has a discrete function during growth on methanol, which might be reflected in differential gene regulation (Pritchett and Metcalf, Mol. Microbiol. 56:1183-1194, 2005). To test this suggestion, reporter gene fusions were constructed for each of the three operons, and their expression was examined under various growth conditions. Expression of the mtaCB1 and mtaCB2 fusions was 100-fold and 575-fold higher, respectively, in methanol-grown cells than in trimethylamine (TMA)-grown cells. The mtaCB3 fusion was expressed at low levels on methanol, TMA, and dimethylamine but was significantly upregulated on monomethylamine and acetate. When TMA- or acetate-grown cultures were shifted to methanol, the mtaCB1 fusion was expressed most highly during exponential phase, whereas the mtaCB2 fusion, although strongly induced prior to mtaCB1 expression, did not reach full expression levels until stationary phase. The mtaCB3 fusion was transiently expressed prior to entry into exponential phase during a TMA-to-methanol substrate shift experiment. When acetate-grown cells were shifted to medium containing both TMA and methanol, TMA utilization commenced prior to utilization of methanol; however, these two substrates were consumed simultaneously later in growth. Under these conditions expression of the mtaCB2 and mtaCB3 fusions was delayed, suggesting that methylamines may repress their expression.

Dimethylamines↗
PubMed1986

Mechanism of induction of mucosal ornithine decarboxylase by food.

Refeeding fasted rats dramatically increases ornithine decarboxylase (ODC) activity in the mucosa of the small intestine and colon. The agents responsible for that activation and pathways leading to activation, however, have not been identified. The current work examines whether stimulation of ODC activity is mediated humorally or directly and whether dietary amines might be in part responsible for activation. Male Sprague-Dawley rats were used 1 wk after they were surgically prepared with Thiry-Vella jejunal loops. Two hours after refeeding rats fasted for 48 h, ODC activity increased 40-fold in mucosa from the intact jejunum and 4-fold in the mucosa of the bypassed segments. The injection of intestinal contents (obtained from additional fed rats) into the bypassed loop caused a 10-fold increase in ODC activity in the loop measured 2 h later. Injection of gut contents, lyophilized to remove dietary amines, produced no change in enzyme activity. The addition of 400 mol dimethylamine to lyophilized gut contents restored enzyme activation to 80% of the previous level. These data allow the following conclusions: following a meal mucosal ODC is activated by both humoral and direct mechanisms, direct stimulation by dietary constituents appears to be the predominant mechanism involved, and dietary amines may be one of the agents involved in directly increasing enzyme activity.

Animals↗
PubMedDate not supplied

Additive impairment of the barrier function and irritation by biogenic amines and sodium lauryl sulphate: a controlled in vivo tandem irritation study.

Biogenic amines are potential irritants e.g. in fish-, meat-, milk- and egg-processing professions like cooks, butchers and bakers. The aim of this study was to test the irritative and barrier-disrupting properties of the biogenic amines ammonium hydroxide (AM), dimethylamine (DMA) and trimethylamine (TMA). A repeated sequential irritation of 30 min twice per day was performed over a total of 4 days (tandem repeated irritation test) on the back of 20 healthy volunteers of both sexes with AM, DMA, TMA and sodium lauryl sulphate (SLS). The epidermal barrier function was assessed with a Tewameter TM 210, stratum corneum surface pH was measured with a Skin-pH-Meter 900, inflammation was assessed with a Chromameter CR-300 on the a* axis for redness and a visual score was recorded. All tested biogenic amines (AM, DMA and TMA) induced a barrier disruption and a pH increase paralleled with a 1-day-delayed onset of inflammatory signs. These effects were further enhanced and accelerated by a sequential application of SLS together with the biogenic amines, and inflammation occurred earlier than with the single compounds. Acetic acid (AA) in contrast did only show mild barrier disruption and no significant inflammatory signs. Our system allowed a ranking of the different compounds in their irritative potential in the tandem irritation with SLS: SLS > NaOH > TMA > AA > AM > DMA. The results are suggestive that in the food-processing industry the simultaneous contact with biogenic amines and harmful detergents like SLS should be minimized.

Administration, Cutaneous↗