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PubMed1990

Free radical intermediates in the oxidation of N-methylhydroxylamine and N,N-dimethylhydroxylamine by oxyhemoglobin.

Nitroxide radicals have been detected in the methemoglobin formation reaction between oxyhemoglobin and the substituted hydroxylamine compounds, N-methylhydroxylamine and N,N-dimethylhydroxylamine, by ESR spectroscopy. The stability of these nitroxide radicals was considerably higher than that of the NH2O. radical derived from unsubstituted hydroxylamine. Only in the case of N-methylhydroxylamine the detection of the nitroxide radical required the use of a flow system, because the radical was found to undergo a rapid degradation with the concomitant formation of a secondary product, the beta-aminonitroxide CH3NO.CH2NH2. The nitroxide radical derived from N,N-dimethylhydroxylamine and oxyhemoglobin was stable for more than 1 hour. In addition, formation of low-spin iron-(III)-complexes from methemoglobin and excess substituted hydroxylamine was observed in both cases. Neither N-methylhydroxylamine nor N,N-dimethyldroxylamine formed the hemoglobin-nitric oxide complex found with unsubstituted hydroxylamine. Parallels and differences in the reaction path of un-, mono- and disubstituted hydroxylamines are discussed.

Animals↗
PubMed1992

Synergistic effects of Cu(II) and dimethylammonium 2,4-dichlorophenoxyacetate (U46 D fluid) on PM2 DNA and mechanism of DNA damage.

Dimethylammonium 2,4-dichlorophenoxyacetate (2,4-D . DMA) induced strand breaks in PM2 DNA when incubated with CuCl2, whereas 2,4-D . DMA alone or CuCl2 alone did not show any or only a negligible effect. The formation of single strand breaks increased linearly with time and concentration of 2,4-D . DMA. Neocuproine, a specific Cu(I) chelator totally prevented strand break formation. So did catalase (up to 100 mM 2,4-D . DMA), but DMSO had only a small protective effect. 2,4-Dichlorophenol, CO2 and formaldehyde were detected as reaction products of 2,4-D and CuCl2. From these results a redox reaction of Cu(II) and 2,4-D is proposed, which could explain the DNA damaging properties of CuCl2/2,4-D . DMA.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1975

Effects of insulin upon fatty acids synthesis from pyruvate, lactate, and glucose in rat mammary cells.

In isolated rat mammary secretory cells, insulin stimulated fatty acid synthesis from pyruvate three times, stimulated glucose conversion to fatty acids 1.2 to 1.5 times, and decreased lactate conversion to fatty acids 20 to 30%. Incubation of glucose and pyruvate together depressed fatty acid synthesis from glucose not attributable to isotope dilution. Glucose stimulated conversion of pyruvate-2-14 carbon to fatty acids without significantly affecting pyruvate-1-14 carbon conversion to 14-carbon dioxide. At differing concentrations, the electron acceptors phenazine methosulfate and N,N,N',N'-tetramethyl-p-phenylene-diamine alleviated the depression by insulin of lactate conversion to fatty acids. The data support concepts that: (1) insulin acts at important sites other than or in addition to glucose transport in regulating mammary secretory cell metabolism and, particularly, fatty acid synthesis; (2) insulin actions upon fatty acid synthesis can vary dependent upon cellular redox state (insulin increases fatty acid synthesis in cells with a low redox state and decreases fatty acid synthesis in cells in a very reduced state); and (3) pyruvate depresses glucose carbon flux through the Embden-Meyerhof pathway.

Animals↗
PubMed1979

Mastitis: I. In vitro antimicrobial activity of alkyl amines against mastitic bacteria.

The activities of branched and straight chain amines (10 to 18 carbons chain length) were compared in inhibiting the growth of five microorganisms that cause about 95% of bovine mastitis. Three gram-positive (Streptococcus agalactiae, Streptococcus uberis, Staphylococcus aureus) and two gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria were used in a trypticase soy broth tube culture growth assay. Sixty-two compounds were screened at concentrations of 200, 100, 50, 25, 10, 5, and 1 ppm in broth culture to determine the effective minimum inhibitory concentration. Alkyl secondary N-substituted monoethyl [CH3(CH2)nNHCH2CH3] and tertiary N,N-substituted dimethyl [CH3(CH2) nN(CH3)2] amines with chain lengths of 11 to 14 carbon atoms were active against both gram-positive and gram-negative organisms. Antimicrobial activity against gram-positive organisms increased with increasing chain length and carbon-14 to 18 amines were active at 1 to 5 ppm. The carbon-11 to 13 alkyl amines were most active against gram-positive organisms; longer chain amines (more than 14 carbons) were inactive. Branching of the alkyl chain caused a loss of activity against gram-negative but not against gram-positive bacteria. Antimicrobial testing of monoamines, polyamines, and the influence of order substituents were investigated to correlate structure-acitivity relationships.

Amines↗
PubMed2005

Development of self-etching primer adhesive in all-in-one bonding system.

The self-etching primer adhesives examined in the present study were aqueous mixtures of 5 wt% MDP, 35 wt% HEMA, 3 wt% 2-hydroxyl-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride (QTX), 0.5 wt% ethyl-p-(N,N-dimethylamino)benzoate (EDM), and 30 wt% water-soluble dimethacrylate (i.e., 2,2-bis(4-methacryloxy polyethoxypheny)propane (BPE), Glycerol dimethacrylate (GMR), or Glycerol methacrylate acrylate (GAM)). Self-etching primer adhesive was directly applied to polished bovine teeth. Tensile bond strength of composite resin to bovine teeth was measured after one-day immersion in water at 37 degrees C. Differences in water-soluble dimethacrylate monomer did not produce any significant differences in tensile bond strength to dentin or enamel. The use of N-phenyliminodiacetic acid (PIDAA) instead of EDM showed significantly higher bond strength to dentin and enamel. In conclusion, GMR and GAM were useful as water-soluble dimethacrylates while the combination of PIDAA and QTX was effective in improving the bond strength of composite resin to teeth in an all-in-one bonding system.

Acid Etching, Dental↗
PubMed1976

Studies on the effect of feeding nitrite and secondary amines to Wistar rats.

1. When 1 000 mg/l sodium nitrite are added to drinking-water, nitrosamines are formed in the stomachs of Wistar rats at levels greater than the background only if the concentrations of added DMA or pyrrolidine exceed 1 000 mg/kg. Once this concentration is exceeded there is a rapid increase in nitrosamine formation up to 2 000 mg/kg added amine; however, for pyrrolidine, the rate of increase of NPy decreases when the dietary level of amine exceeds 2 000 mg/kg. This threshold level of 1 000 mg/kg amine is one which is rarely reached in normal human dietary patterns. 2. Due to the presence of this threshold it is unrealistic to extrapolate from high experimental dietary concentrations of secondary amines to those found in practice when considering nitrosamine formation in vivo. 3.The concentration of dietary amine has a greater influence on nitrosamine formation in the stomachs of rats than does the concentration of nitrite in drinking-water (up to 1 000 mg/l). This finding is in contradiction to the current kinetic theory of nitrosamine formation, in which formation is predicted to be proportional to the square of the nitrite concentration.

Animals↗
PubMed1997

Blockade of Na+/H+ exchanger contracts the portal vein of spontaneously hypertensive and Wistar Kyoto rats.

It has been claimed that the activity of Na+/H+ exchanger (NHE) is altered in spontaneously hypertensive rats (SHR) suggesting a possible role for it in the pathophysiology of hypertension. The purpose of this study has been to investigate the effect of blockade of NHE on the noradrenaline (NA) and 26K+ induced tone and on the recovery of tone from acid induced contractions in the portan vein of spontaneously hypertensive rats (SHR) as compared to their controls of Wistar Kyoto rats (WKY). Blockade of NHE by 10(-4) dimethylamiloride (DMA) raised the tone of NA and 26K+ activated preparation of both strains, the contractions being higher with NA activation. Total blockade of NHE by replacement of Na in solution with N-methy-D-Glucamine (NMDG) raised the tone of the NA activated preparations by 45+/-10%, n=8, P<0.01 and 33+/-4%, n=12, P < 0.01 in SHR and WKY respectively. The time for 50% relaxation from NH4Cl washout contraction was significantly prolonged by 10(-5) and 10(-4) M DMA in both strains under NA or 26K+ activation. DMA effect was greater on NA than on 26K+ activated preparations, and was not significantly different when comparing SHR to WKY results. In conclusion the results reported in this study indicate that NHE has similar activity in WKY and SHR portal veins and that its blockade contracts both preparations. Therefore, it is unlikely that increased NHE activity, acting directly on vascular smooth muscle tone, could be a primary cause for hypertension.

Ammonium Chloride↗
PubMed1999

alpha3beta3gamma complex of F1-ATPase from thermophilic Bacillus PS3 can maintain steady-state ATP hydrolysis activity depending on the number of non-catalytic sites.

Homogeneous preparations of alpha(3)beta(3)gamma complexes with one, two or three non-competent non-catalytic site(s) were performed as described [Amano, Hisabori, Muneyuki, and Yoshida (1996) J. Biol. Chem. 271, 18128-18133] and their properties were compared with those of the wild-type complex. The ATPase activity of the complex with three non-competent non-catalytic sites decayed rapidly to an inactivated state, as reported previously [Matsui, Muneyuki, Honda, Allison, Dou, and Yoshida (1997) J. Biol. Chem. 272, 8215-8221]. In contrast, the complex with one or two non-competent non-catalytic sites displayed a substantial steady-state phase activity depending on the number of non-competent non-catalytic sites in the complex. This result indicates that one competent non-catalytic site can maintain the continuous catalytic turnover of the enzyme and can potentially relieve all three catalytic sites from inhibition by MgADP(-). Furthermore, the results suggest that the interaction between three non-catalytic sites might not be as strong as that between catalytic sites, which are all strictly required for a continuous catalytic turnover.

Adenosine Triphosphate↗
PubMed1975

Hexamethylmelamine-induced regression of human lung tumors growing in immune deprived mice.

Hexamethylmelamine is known to be effective in humans in the treatment of certain malignant tumors, especially bronchial carcinoma. It is, however, quite inactive against a number of animal tumors, making difficult a study of its mechanism of action in experimental systems. In a reexamination of the effects of hexamethylmelamine, two tumors were found to be very sensitive, namely, a mouse plasma cell tumor (PC6) and a human bronchial carcinoma (P246) growing in immune deprived mice. Both tumors undergo a significant and almost complete regression, even when well established, and hence may serve as model systems for the study of the mechanism of action of hexamethylmelamine.

Animals↗
PubMed1975

A rapid method for measuring miotic activity of drugs in the intact mouse eye.

A rapid and precise method for evaluating the miotic activity of cholinergic drugs has been developed based on Long's method for measuring the rate of mydriasis. The rate of reversal of mydriasis developed previously in the intact mouse eye by a mild mydriatic (phenycyclidine) is used to evaluate the miotic activity. The method provides a useful tool for measuring and comparing the miotic activity of acetylcholine agonists and cholinesterase inhibitors.

Amides↗
PubMed1975

Inhibition of the sympathetic nervous system by 5,6-dihydroxy-2-dimethylamino tetralin (M-7), apomorphine and dopamine.

M-7, in doses of 1 mug/kg, reduces the resting heart rate of anesthetized dogs and cats. In similar dose ranges, M-7 blocks reflex activation of the sympathetic nervous system. Experimental procedures included bilateral carotid occlusion in the dog and central stimulation of vagi and right sciatic nerves in the cat. M-7 inhibits the response to postganglionic stimulation of the right cardioaccelerator nerve if the frequency of stimulation is 2 Hz; no inhibition is observed with a frequency of 18Hz. The inhibitory action of M-7 is antagonized by haloperidol, 50 mug/kg, or chlorpromazine, 150 mug/kg. Similar inhibitory actions and frequency specificity were observed in vitro using the right atrium of the cat and nerve stimulation. In cats, nerve stimulation was inhibited by apomorphine. Dopamine, in the presence of cocaine, also inhibited low-frequency nerve stimulation. It is postulated that prejunctional sympathetic nerves innervating the heart have dopamine receptors that serve as inhibitory role in transmission.

Animals↗