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PubMedDate not supplied

Biochemistry of renal failure.

The term uremia is used clinically to describe that state associated principally with the retention of nitrogenous metabolic products and is characterized by a raised blood urea concentration. The increase in the blood urea concentration is perhaps the most striking abnormality of the body fluids in renal failure, although it is not the most important functionally. The clinical syndrome of uremia involves all the systems of the body as a result of biochemical alterations in the constitution of the internal environment. The alterations in the latter compartment are due not only to the retained metabolic products but also to associated changes in water, electrolyte, and acid-base homeostasis. There are also features of the clinical syndrome of uremia which are attributable to variations in the rates of secretion and metabolism of a number of hormones in which the kidney is recognized to play a role, either directly or indirectly. This brief review deals with the retained uremic metabolites and their biochemical significance in the clinical syndrome of uremia. The metabolites discussed include urea, creatinine, guanidines and related compounds, uric acid, dimethylamine, and the middle molecule hypothesis. The potential role of some of these metabolites is discussed with regard to their potential toxic role as enzyme inhibitors. The biochemical aspects of uremic neuropathy are reviewed to highlight the biochemical complexity of the investigation of the uremic syndrome.

Creatinine↗
PubMed1982

Induction of preneoplastic and neoplastic lesions in rats treated N-nitroso compounds.

Dose-related changes of incidences of pre-neoplastic and neoplastic lesions in the liver or urinary bladder were examined with N-nitroso-dimethylamine (NDMA) or N-nitrosobutyl-4-hydroxybutylamine (NBHA) respectively. The incidences of lesions by the two carcinogens were compared in short-term and long-term experiments. In a short-term experiment, rats were given a basal diet containing NDMA at concentrations of 10.0, 1.0 and 0.1 mg/kg for 6 weeks, after initiation by a single i.p. injection of N-nitrosodiethylamine (NDEA). Similar, long-term experiments (96 weeks) were also performed, but without NDEA pretreatment. A clear dose-related effect was found in the induction of pre-neoplastic lesions when the groups given 10.0 and 1.0 mg/kg NDMA were compared. This coincided with the results of a long-term experiment on the induction of hyperplastic nodules and hepatocellular carcinomas. Various concentrations of 0.05 to 0.005% of NBHA in the drinking water were given for different periods up to 12 weeks, in a short-term, and up to 40 weeks in a long-term experiment. Incidences of early preneoplastic lesions of the cell surface observed by scanning electron microscopy showed a tendency to increase with longer duration and higher dose (0.01 to 0.05%). A clear dose-dependent effect was found for the incidence of papilloma and carcinoma in the groups subjected to longer treatments.

Animals↗
PubMed1982

[Human pharmacokinetics of different i.v. doses of azapropazone (HPLC-determination) (author's transl)].

The pharmacokinetic profile of azapropazone (Prolixan), sodium salt of 5-dimethylamino-9,5-dimethylamine-9-methyl-5-propyl-1H-pyrazolol[1,2-a][1,2,4]benzotriazine-1,3(2H)-dione, was established. Six healthy, adult volunteers received a single dose of either 600 mg or 1200 mg azapropazone as sodium salt intravenously. The drug was selectively separated from its metabolites and other plasmatic compounds and it was quantified by measurement of extinction at 254 nm. The kinetic parameters of azapropazone were independent of the applied dose (600 mg and 1200 mg): Biological half-life (t0.5): 16.8 +/- 2.95 h and 17.2 +/- 3.0 h; Total clearance (Cltot): 10.2 +/- 2.1 ml min-1 (both doses); Central volume of distribution (Vc): 3.7 +/- 0.71 and 3.9 +/- 0.91; Apparent volume of distribution (Vd): 12.5 +/- 2.91 and 14.4 +/- 2.41. Initial serum concentrations were 170 +/- 41.5 micrograms ml-1 and 326.3 +/- 84.5 micrograms ml-1, determined by extrapolation (C0 at time t0). The areas under the plasma concentration curves (AUC0 infinity) were calculated to amount 1052.5 +/- 217.4 micrograms ml-1h-1 and 2078.4 +/- 515.9 micrograms ml-1h-1. Three rate constants associated with the elimination of the drug could be calculated.

Adult↗
PubMed1980

Kinetics of nitrosamine formation in mice following oral administration of trace-level precursors.

Groups of 3-5 Swiss CD1 mice were gavaged with aqueous solutions of sodium nitrite (250 micrograms), followed immediately by morpholine (5 micrograms) or dimethylamine (250 micrograms). At subsequent intervals, up to 30-60 min, mice were frozen, pulverized in liquid nitrogen and extracted with methylene chloride. Volatile nitrosamines were then quantitatively determined using a Thermal Energy Analyzer, interfaced to GC or HPLC. Biosynthesis of both N-nitrosodimethylamine (NDMA) and N-nitrosomorpholine (NMOR) showed a time-dependent increase for 3 and 9 min, respectively, followed by a steady decline. Levels of NDMA and NMOR were generally less than 0.1 ng/g in control mice gavaged with amine or nitrite alone. Zero-time recovery of NDMA and NMOR ranged from 50-70% and 70-90%, respectively. Biosynthesis of NDMA and NMOR was inhibited by prior administration of ascorbic acid, sodium ascorbate or ammonium sulfamate.

Administration, Oral↗
PubMed1980

Analytical survey of N-nitroso contaminants in pesticide products.

1. Levels of N-nitroso dialkylamines in dinitroaniline derivatives were high (up to 153 mg/kg) in the past, but have been decreased considerably in current production, due to process changes. 2. Butralin and pendimethalin contain significant amounts of N-nitroso parent compounds. 3. Most dimethylamine salts of phenoxyalkanoic acids presently contain low or non-detectable levels of NDMA. 4. Quaternary ammonium compounds contain NDMA levels up to 16.8 mg/kg. 5. Two morpholine derivatives appear to contain N-nitrosomorpholine. 6. The triethanolamine salt of dinoseb contains over 200 mg/kg N-nitrosodiethanolamine. 7. A large number of amides, carbamates, organophosphates, triazines, urea derivatives and miscellaneous nitrogen-containing pesticides do not contain N-nitrosamines above 1 mg/kg. 8. Most N-nitroso contaminants in pesticides can be avoided by simple process changes and the elimination of nitrite salts in the formulation.

Chromatography, Gas↗
PubMed1980

Occurrence and formation of nitrosamines in animal feeds.

A total of 465 samples of ingredients of animal feeds (fish meal, antarctic krill meal, experimental silage containing 40% dried animal wastes) and complete mixed feeds and protein concentrates were analysed for nitrate and nitrite content in the period 1973-78. Over 62% of the samples contained nitrates in concentrations ranging from 1 to 1020 mg/kg, and 6% contained 1-15 mg/kg of nitrites. After a preliminary survey, the samples having the highest levels of nitrate, nitrite and amines were selected and analysed for volatile N-nitrosamines. Of 171 selected samples, 40% were found to contain N-nitrosodimethylamine in the range of 0.003 to 0.417 mg/kg. No statistically confirmed correlation between concentrations of nitrates or nitrites and nitrosamines could be demonstrated. Large amounts of dimethylamine, ranging from 110 to 1765 mg/kg, were found in all samples of krill meal. Incubation of krill meal and fish meal with nitrite, under conditions similar to those existing in the animal stomach, resulted in the formation of substantial amounts of NDMA. The occurrence of N-nitrosamines in feeds and their possible formation in vivo from precursors present in feeds seems to be an important problem from the hygienic standpoint, because of possible "carry-over" to tissues, milk and eggs.

Animal Feed↗
PubMed1981

Absence of volatile nitrosamines in human feces.

Using a method for nitrosamine analysis that gives high recovery values and that is free from artifactual synthesis of nitrosamines, we have shown that human feces do not contain volatile nitrosamines (detection limit, 0.1 to 0.5 microgram/kg). We also showed that nitrosation reactions are not catalyzed by fecal organisms. Following a 2-day anaerobic incubation of feces with either a secondary amine (dimethylamine, dipropylamine, or morpholine) or nitrite, no nitrosamine was formed. When the amine and nitrite were added together, nitrosamine was formed, but at a level of 2 to 20% of that formed in autoclaved feces under the same conditions. Nitrosamines were stable following anaerobic incubation with feces for up to 4 days. These results suggest that fecal organisms inhibit the chemical formation of nitrosamines instead of catalyzing it. When morphine and nitrate were added together, nitrosomorpholine was formed. Morpholine nitrosates so rapidly that it intercepts nitrite formed by the action of nitrate reductase before the nitrite can be further reduced. However, very high concentrations of morphine and nitrate, which are far from the conditions in normal feces, were required to form measurable nitrosomorpholine. We may conclude that N-nitroso compounds are unlikely to be formed in any significant amounts in the human colon.

Feces↗
PubMed1994

Synthesis and muscarinic receptors affinity of a series of antagonist bivalent ligands.

A series of bivalent ligands (2-8) derived from 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine methiodide 1 has been synthesized and tested to evaluate affinity and selectivity for M1, M2 and M3 muscarinic receptor subtypes. In order to study the contribution of the spacer and of a second cationic head to the binding process, unsymmetrical ligands (9,10) have also been prepared. The results, expressed in terms of pA2 values, show that, although the spacer negatively affects the interaction of the bivalent ligands with the three receptor subtypes, affinity and selectivity are modulated by its length; this indicates that the pharmacophore binding sites are organized differently with respect to their mutual proximity and orientation, in each receptor subtype.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1994

Isolation of plant cytochrome P-450 and NADPH: cytochrome P-450 reductase from tulip bulbs (Tulipa fosteriana L.) oxidizing xenobiotics.

Cytochrome P-450 and NADPH: cytochrome P-450 reductase were solubilized by detergents from microsomal fraction of tulip bulbs Tulipa fosteriana L. and purified to electrophoretic homogeneity. The purification was achieved by anion-exchange column chromatography, hydroxyapatite-column chromatography and affinity chromatography. The two enzyme showed relative molecular weights of about 54,200 and 77,600 for cytochrome P-450 and NADPH: cytochrome P-450 reductase, respectively. The purified enzymes were characterized by their absorption spectra and by kinetic characteristics. The interaction with endogeneous as well as exogenous substrates was studied by differential spectroscopy. Both enzymes in the presence of dilauroyl phosphatidylcholine and NADPH were able to oxidize xenobiotics (N-nitroso-N-methylaniline and N-nitroso-N-dimethylamine) in the reconstitution experiments.

Cytochrome P-450 Enzyme System↗
PubMed1994

Effect of suppository bases on the release properties of a potent antimicrobial agent (C31G).

C31G is a specific formulation which contains equal molar concentrations of alkyl N-betaine and alkyl N,N-dimethylamine oxide. Vaginal suppositories containing 500 mg of C31G, this potent antimicrobial substance, were prepared by the fusion method in a variety of Suppocire and Witepsol bases with different melting points and hydroxyl values. In vitro release and diffusion characteristics of C31G from different suppository bases were investigated using two different systems. The release from suppositories was determined by using a system without a membrane and the diffusion rate of the released agent was determined through a semipermeable dialyzing tubing. Diffusion kinetics from suppositories were evaluated in terms of the apparent dialytic rate constants using the equation developed by Davis et al. From the results of in vitro studies, Witepsol H15 and Suppocire CM bases were selected as the most suitable ones for the formulations of C31G vaginal suppositories, since it is imperative for topical formulations to release the active substance in high proportions which are not absorbable by the mucosal membranes.

Alkalies↗
PubMedDate not supplied

[Isolation and selection of methylamines and dimethyl formamide degrading microorganisms].

From an activated sludge sample, microorganisms capable to degrade monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA), and dimethylformamide (DMF) were isolated. These compounds are present in the wastewaters from a petrochemical plant. Microbial communities were cultivated, in aerobic conditions in a 2-liter bioreactor fed with the wastewater. Only four different kinds of microorganisms were obtained, but they could maintain their degradative capacity after several transfers. This microbial biomass was able to reduce 90% of the dissolved pollutants in a sample of industrial wastewater, mainly MMA, DMA, TMA, and DMF, measured as dissolved organic carbon, in approximately 5 days.

Biodegradation, Environmental↗
PubMed1977

[The aminopyrine respiratory test under the acute effect of ethanol. Evaluation of a new method for the measurement of microsomal functions of the liver].

Microsomal demethylation, a partial function of the liver, can be estimated by the aminopyrine breath test. Both the determination of specific activity and the disappearance rate constant for 14CO2 in breath demand the assumption of rapid formaldehyde oxidation to CO2. Conversely, the disappearance of aminopyrine from plasma reflects microsomal aminopyrine metabolism only. Ethanol is known to affect both microsomal demethylation and formaldehyde metabolism. If in the presence of ethanol the latter process should become rate-limiting, a discrepancy between the data obtained in breath and in plasma could be expected. In order to investigate this possibility 10 fasting healthy male volunteers received 9 mg/kg (dimethylamine-14C)-aminopyrine (2 muCi) orally and, 3 hs later, 0.7 g/kg ethanol. Immediately following ethanol the specific activity of 14CO2 in breath decreased by 25% (p less than 0.005) and the disappearance of 14CO2 from breath was 31% lower than in 17 matched controls (p less than 0.005). The aminopyrine plasma disappearance rate, determined by GLC, decreased by 30% after ethanol (p less than 0.05). Since the decrease in aminopyrine plasma disappearance rate seems to account for the proportional decreases obtained by breath analysis, it is concluded that the aminopyrine breath test expresses the rate of microsomal demethylation even during altered formaldehyde metabolism, e.g. in acute ethanol intoxication.

Aminopyrine↗
PubMed1993

Calcium mobilization-associated and independent cytosolic acidification elicited in tandem with Na+/H+ exchanger activation in target cell-adherent human NK cells.

Flow cytometry was used to identify mechanisms by which human NK cells regulate intracellular pH (pHi) and to investigate the relationship between NK cell pHi and cytolytic function. Temporally resolved determinations of pHi were simultaneously made in NK cells that formed conjugates with target cells (NKC) and unconjugated NK cells (NKU) on the basis of the red/orange fluorescence emission ratio of the pH indicator seminapthylrhodafluor-1. Two pHi regulatory mechanisms were identified in NK cells: 1) a HCO3-/Cl- antiport that promoted pHi changes in response to variation of extracellular HCO3- and Cl- but not Na+ ion concentrations, was sensitive to stilbene derivatives 4,4'-diisothiocyanatostilbene sulfonic acid and 4-acetamido-4'-isothyocyanotostilbene-2-2'-disulfonic acid, and exhibited similar activity in NKC and NKU, and 2) a Na+/H+ exchanger that promoted pHi changes in response to extracellular Na+ ion concentration changes and was sensitive to dimethylamiloride (DMA), permeable to Na+ and Li+ but not K+ or N-methyl-D-glucamine, and quiescent in NKU but activated in target cell-adherent NKC. When Na+/H+ exchange was blocked with 10 microM DMA, the pHi of NKC bound to NK-sensitive K562 target cells progressively decreased for 3 to 4 min, then stabilized at 0.1 to 0.15 pH units below the pHi of NKU. A significant temporal decline in NKC pHi also occurred in the nominal absence of extracellular Ca2+ (0.07 +/- 0.02 pH units) and when NKC formed conjugates with NK-resistant B lymphoblastoid target cells that failed to mobilize NK cell Ca2+ (0.07 +/- 0.01 pH units) (mean +/- SD). However, the magnitude of the NKC cytosolic acidification response was consistently reduced (42 +/- 4 and 44 +/- 6%, respectively) under these Ca2+ flux response-limiting conditions. Thus, adhesion to target cells triggered two pHi-related responses in NK cells: 1) a decline in pHi which exhibited both Ca2+ mobilization-dependent and -independent components, and 2) Na+/H+ exchanger activation by which acid production was neutralized. Manipulations of HCO3- and DMA that clamped NKC pHi at values ranging from 6.8 to 7.2 failed to significantly influence NK cell cytolytic function. By contrast, isosmotic replacement of extracellular Na+ with NMDG resulted in a 57 +/- 22% inhibition of NK cell-mediated cytolysis (n = 8, p < 0.01). NKC pHi declined to 6.8 to 6.9 under these conditions, but this was not the apparent basis of impaired cytolysis because sustained elevation of NKC pHi by addition of dimethylamine failed to significantly reverse inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Amiloride↗
PubMed1993

Cellular localization of cytochrome c550. Its specific association with cyanobacterial photosystem II.

Cellular localization of cytochrome (cyt) c550, a low potential, c-type monoheme cytochrome, in a thermophilic cyanobacterium Synechococcus vulcanus was investigated by systematic fractionation of the cells followed by its enzymatic and immunological detection. While cyt c-553, a soluble cyt that donates an electron to P700, was detected in the supernatant of osmotic disruption of lysozyme-treated cells, cyt c550 was detected only in the thylakoid membrane fraction, being tightly bound to thylakoids, and its removal required sonication in the presence of 1 M CaCl2. Upon further fractionation of the thylakoids into photosystem (PS) I and PSII by lauryl dimethylamine N-oxide solubilization, cyt c550 was exclusively concentrated in the crude PSII fraction together with cyt f, with no significant amount being detected in any of the soluble and PSI fractions. Upon further fractionation of the crude PSII by n-dodecyl beta-D-maltoside solubilization followed by column chromatography, cyt c550 was detected exclusively in the purified PSII core complex fraction but not in any other fractions. A 12-kDa protein, one of the extrinsic components of cyanobacterial PSII, exhibited completely the same behavior as that of cyt c550 during these fractionation procedures. These results, coupled with our previous results that cyt c550 binds stoichiometrically to the cyanobacterial PSII core complex and enhances O2 evolution (Shen, J.-R., and Inoue, Y. (1993) Biochemistry 32, 1825-1832), indicate that there is only one species of cyt c550 in cyanobacterial cells and that this cyt is exclusively associated with PSII as a functional component for O2 evolution.

Blotting, Western↗
PubMed1996

Effect of insect-growth-disrupting amines and amides on Schistosoma mansoni in vitro.

A series of nonsteroidal alkylamines and alkylamides, which apparently inhibit phytosterol dealkylation in insects and free-living nematodes, as well as steps in the ecdysteroid biosynthetic pathway of insects, are also known to affect growth and development of animal-parasitic nematodes. The effect of these compounds on the motility, pairing, and viability of the trematode, Schistosoma mansoni, maintained in vitro was examined by incorporating the potential inhibitors into the medium employed for parasite culture. The alkylamines were more active than their amide counterparts, killing all parasites within 18 hr when tested at 25 parts per million. At lower concentrations, reductions in schistosome pairing and motility were observed. The functional group of the amine compounds influenced the schistosomicidal activity, with N-ethylamines being more effective than N,N-dimethylamines of identical carbon chain-length. Of all the compounds tested, N-ethyldodecanamine appeared to be the most promising schistosomicidal agent, killing all parasites within 22 hr at 10 parts per million and preventing parasite pairing at 3 parts per million.

Amides↗
PubMed1996

Bicyclic dioxolanes as potential antimuscarinic agents.

A series of rigid compounds--derivatives of 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine methiodide (1b)--has been synthesized and tested to evaluate affinity and selectivity for M1, M2, and M3 muscarinic receptors. The stereochemistry of the annulation does not influence the activity; the optimal distance between nitrogen and the benzhydryl group seems to be that with the nitrogen in the rigid ring (2b) or the nitrogen directly bound at the cyclopentane nucleus (9b, 11b). The different structure-activity relationships between tertiary amines (a series) and the corresponding quartnerary salts (b series) suggest a different binding to the receptor sites.

Animals↗
PubMed1996

Assessment of the anti-microbial agent C31G as a spermicide: comparison with nonoxynol-9.

The broad-spectrum anti-microbial agent, C31G, containing an equimolar mixture of n-dodecyl-dimethylamine-N-oxide (C12-N-O) and N-(n-dodecyl), N-dimethyl-glycine (C12-betaine), was tested for spermicidal activity in comparison with the currently used spermicide, nonoxynol-9 (N-9). The rate of sperm cell permeabilization by the spermicides, as assayed with the fluorescent probe, TO-PRO-1, increased as the cube of the C31G concentration, while the rate increase was linear with N-9 concentration. At 0.04%, the rate of sperm cell permeabilization with both spermicides is at the limit of rapid measurement. C31G diffuses through cervical mucus at a more rapid rate than does N-9. C31G has long been known to aid wound healing and reduce inflammation, whereas N-9 has been reported to induce vaginal irritation. C31G would, thus, seem to have the spermicidal efficacy, the broad range of anti-microbial activity, and the lack of inflammatory activity that is sought in the ideal vaginal spermicide.

Adult↗
PubMed1996

Effects of amphiphilic compounds on metabolic and biological activities of Salmonella typhimurium.

The effect of two quaternary ammonium salts, (1-methyldodecyl)trimethylammonium bromide (ATDBr) and tetramethylammonium bromide (TMABr), as well as that of two amine oxides, (1-methyldodecyl)dimethylamine oxide (ATDNO) and trimethylamine oxid (TMANO), on both metabolic and biological activities of a S. typhimurium strain isolated from nosocomial infection were studied. The compounds with long alkyl chain in the molecule (ATDBr, ATDNO) affected the growth, synthesis of biomacromolecules (DNA, RNA, proteins) and respiration. The compounds lacking the alkyl chain (TMABr, TMANO) were ineffective with exception of the endogenous respiration that they inhibited in a less degree in the highest concentrations tested. The highest inhibition of respiration was evoked by ATDBr and ATDNO in the presence of pyruvate as an exogenous carbon substrate. The sub-MICs of quaternary ammonium salts induced a prophage of the lysogenic S. typhimurium strain, amine oxides were ineffective. The tested compounds decreased at one-fourth of the MICs the permeability reaction. The results showed that both physiologic and metabolic processes were inhibited in dependence on the length of the alkyl chain, however, amine oxides were less effective in biological activities.

Amines↗