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At least 91 records · Page 5Linked to original sources

PubMed2006

Dynamic light scattering studies of additive effects on the microstructure of aqueous gemini micelles.

Dynamic light scattering (DLS) measurements have been performed at 30 degrees C to see the effects of additives on the microstructure of gemini alkanediyl-alpha,omega-bis(dimethylcetylammonium bromide) surfactants, (Br-, n-C16H33N+Me2-(CH2)s-Me2- N+n-C16H33, Br-, 16-s-16, where s = 4, 5, 6). In pure aqueous solutions, the hydrodynamic diameter, Dh, was found to increase rapidly with geminis in comparison to their monomeric counterpart cetyltrimethylammonium bromide (n-C16H33N+Me3, Br-, CTAB) on increasing surfactant concentration. The additives considered in the present study are n-alcohols (C4-C6OH) and n-hexylamine (C6NH2) on the micellar growth of 0.03 M 16-4-16 in the presence and absence of 0.001 M KBr. The presence of 0.001 M KBr or organic additives at lower concentrations singly or jointly has little effect on the micellar size. As the chain length of the additive increases, the size increases with the increase of additive concentration, the magnitude being substantial in the presence of 0.001 M KBr. However, for equal chain length additives (C6OH, C6NH2), the effect was greater for C6OH. In case of C6NH2, the value of Dh reaches to almost constancy when the concentration of the additive was increased. Increased effectiveness of additives in the presence of added salt (KBr) is discussed in light of electrostatic and hydrophobic forces operating in the solution, which are always responsible for growth processes.

Journal Article↗

PubMed2000

Inactivation of mitochondrial permeability transition pore by octylguanidine and octylamine.

Mitochondrial permeability transition occurs through a Ca2+-dependent opening of a transmembrane pore, whose identity has been attributed to that of the adenine nucleotide translocase (ANT). In this work, we induced permeability transition by adding 0.5 microM carboxyatractyloside. The process was evaluated analyzing Ca2+ efflux, a drop in transmembrane electric gradient, and swelling. We found that the amphiphyllic cations octylguanidine and octylamine, at the concentration of 100 microM, inhibited, almost completely, nonspecific membrane permeability. Hexylguanidine, hexylamine, as well as guanidine chloride and hydroxylamine failed to do so. The inhibition was reversed after the addition of 40 mM Li+, Na+ K+, Rb+, or Cs+; K+ was the most effective. We propose that the positive charge of the amines interact with negative charges of membrane proteins, more likely the ADP/ATP carrier, while the alkyl chain penetrates into the hydrophobic milieu of the inner membrane, fixing the reagent.

Adenosine Diphosphate↗

PubMed1999

One step isolation of bovine asialoglycoprotein receptor and its characterization by sequence analysis and MALDI mass spectrometry.

The asialoglycoprotein receptor (ASGP-R), which is responsible for the uptake of partially deglycosylated serum glycoproteins was isolated from bovine liver. The receptor was purified in one step from solubilized plasma membranes by affinity chromatography on 6-(beta-D-lactosyl)-n-hexylamine coupled to N-hydroxysuccinimide activated Sepharose with a coupling degree of 7.6 micromol/ml gel. The preparation yielded two distinct polypeptides with apparent molecular weights of 48 and 43 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A polyclonal antibody raised against the human ASGP-R recognized the bovine 43 kDa protein in Western blot analysis. The 48 and 43 kDa polypeptides were digested by trypsin and the digests were subsequently analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Sequence analysis of four tryptic fragments, two each of the 48 kDa and of the 43 kDa polypeptides revealed that these were highly homologous to ASGP-R subunits from man, mouse and rat.

Amino Acid Sequence↗

PubMed1968

The displacement of calcium ions from phospholipid monolayers by pharmacologically active and other organic bases.

1. The binding of (45)Ca(2+) to a monolayer of phosphatidylinositol at the air-water interface was maximal when the separation of the phospholipid head groups approximated to the diameter of a hydrated Ca(2+) ion. 2. The displacement of Ca(2+) adsorbed on monomolecular films of phosphatidylinositol by a series of drugs (both narcotic and excitatory) and other organic bases was related to the ability of the bases to penetrate into the film. 3. With films of phosphatidylinositol at constant area, and at an initial surface pressure of 10dynes/cm., the displacement of Ca(2+) by increasing concentrations of the local anaesthetic, tetracaine, was linearly related to the change in surface pressure (Deltapi) caused by the penetration of the drug. 4. Deltapi and the displacement of Ca(2+) showed a related fall when the initial surface pressure of the phosphatidylinositol film was increased from 4 to 40dynes/cm. both at a constant bulk tetracaine concentration and when this latter concentration was adjusted to keep it at a constant ratio to the surface density of phosphatidylinositol molecules. 5. The displacement of Ca(2+) from phosphatidylinositol films by cetyltri-methylammonium ions was directly compared with the surface concentration of the base in the film, measured by using labelled base and a surface-radioactivity technique. 6. The ability of a series of straight-chain aliphatic amines to displace Ca(2+) from phosphatidylinositol films increased with the number of carbon atoms up to C(12). However, there was a marked jump in the displacing activity after hexylamine, and this could probably be correlated with the carbon chain's being of sufficient length to just reach the hydrophobic fatty acid chains of the orientated phospholipid molecules with the charges on both substances in juxtaposition.

Adsorption↗

PubMedDate not supplied

On the mechanism of drug-induced acceleration of phospholipid translocation in the human erythrocyte membrane.

Small amphiphilic compounds (M(r)<200 Da) such as anaesthetics and hexane derivatives with different polar groups produced a concentration-dependent acceleration of the slow passive transbilayer movement of NBD-labelled phosphatidylcholine in the human erythrocyte membrane. Above a threshold concentration characteristic for each compound, the flip rate gradually increased at increasing concentrations in the medium. For compound concentrations required to produce a defined flip acceleration, corresponding membrane concentrations were estimated using reported octanol/water partition coefficients. The effective threshold membrane concentrations (50-150 mmol l(-1)) varied in the order: hexylamine>isoflurane=hexanoic acid>hexanol=chloroform>hexanethiol=1,1,2,2-tetrachloroethane>chlorohexane. Apolar hexane, which mainly distributes in the apolar membrane core, was much less effective and supersaturating concentrations were required to enhance flip. Localization of the drug at the lipid-water interface seems to be required for flip acceleration. Such a localization may increase the lateral pressure in this region and the bilayer curvature stress with concomitant decrease of order and rigidity at the interface. This unspecific bilayer perturbation is proposed to enhance the probability of formation of hydrophobic defects in the bilayer, facilitating penetration of the polar head group of the phospholipid into the apolar membrane core.

4-Chloro-7-nitrobenzofurazan↗

PubMed1997

The fungus Gibberella fujikuroi produces copper/topaquinone-containing amine oxidase when induced by N-butylamine.

Crude extract of Gibberella fujikuroi AKU 3802 mycelium induced with n-butylamine showed a single amine oxidase activity band in a non-denaturing gel that cross-reacted with the antibody against copper/topaquinone-containing amine oxidase from Aspergillus niger. The enzyme was purified by a procedure involving four chromatographic steps. Purified enzyme was pink with an absorption maximum at 490 nm. Molecular mass of 135 kDa estimated by gel chromatography and 70 kDa found by SDS-PAGE confirmed the dimeric structure of the enzyme. The enzyme readily oxidized n-hexylamine, n-butylamine, benzylamine and histamine, but not spermine or spermidine. Inactivation by carbonyl reagents and copper chelators suggested the presence of a copper/topaquinone cofactor. Spectrophotometric titration by p-nitrophenylhydrazine showed one reactive carbonyl group per subunit and redox-cyclic quinone staining confirmed the presence of a quinone cofactor. pH-dependent shift of the absorption spectrum of the enzyme p-nitrophenylhydrazone (465 nm at neutral to 580 nm at alkaline pH) supports the identity of the cofactor, with topaquinone. The N-terminal amino acid sequence of the enzyme showed high similarity to other microbial copper/topaquinone-containing amine oxidases.

Amine Oxidase (Copper-Containing)↗

PubMed1983

Homogeneous substrate-labeled fluorescent immunoassay for human serum albumin.

A homogeneous substrate-labeled fluorescent immunoassay for human serum albumin (HSA) has been developed, similar to previously described immunoassays for Immunoglobulin G and Immunoglobulin M. HSA was covalently linked to 6-(7-beta-galactosylcoumarin-3-carboxamide) hexylamine. The resulting conjugate had minimal fluorescence at 450 nm (with excitation at 400 nm). However, when the acetal linkage of the galactosyl moiety was hydrolyzed by beta-galactosidase, a substantial increase in the fluorescence was obtained. This increase was specifically inhibited by antibody to HSA. A competitive binding immunoassay was established by letting the conjugate compete with HSA in the serum for the limited number of antibody-binding sites. The level of fluorescence resulting from the addition of enzyme was proportional to the amount of HSA in the serum. Precision, analytical recovery and serum dilution studies were carried out on the assay. The immunoassay was compared to an albumin assay using the dye-binding method.

Coumarins↗

PubMed2003

Extraction of heavy metals by amines adsorbed onto silica gel.

Previous work has established the possibility of using known coordinating agents supported on silica gel in the removal of heavy metals such as lead, copper, cadmium, and nickel from aqueous media. Functionalized silica gel has been used in the removal of heavy metals with notable success. Silica gel is currently being used as a support for various monofunctional aliphatic amines as coordinating ligands. The current study reports the results of an investigation involving the use of saturated, straight chain primary amines as coordinating ligands in the removal of copper(II), cadmium(II), lead(II), nickel(II), and silver(I) ions from aqueous solutions of known concentration. Primary amines used in this investigation were n-butylamine, n-hexylamine, n-octylamine, n-decylamine, and n-hexadecylamine.

Adsorption↗

PubMed1974

Intestinal transport of weak electrolytes. Evidence in favor of a three-compartment system.

A study has been made of the transmural fluxes of benzoic, phenylacetic, and pentanoic acids, benzylamine, hexylamine, and D-amphetamine across rat jejunum incubated in vitro. The M to S fluxes of the weak acids were greater than their corresponding S to M fluxes, and the S to M fluxes of the weak bases were larger than their M to S fluxes. These patterns of asymmetric movements were observed when the transmural electrical potential difference was clamped at 0 mV, and when the pH values of the mucosal and serosal fluids were identical. The effects of a weak acid on the fluxes of other weak electrolytes were qualitatively similar when the effector weak acid was added to the mucosal fluid, and when it was added to the serosal fluid. But the effects of a weak base on the fluxes of other weak electrolytes were dependent upon its location, and the interactions observed when the effector weak base was added to the mucosal fluid were qualitatively different than those seen when it was added to the serosal fluid. The interactions between weak electrolytes could readily be explained in terms of the function of a system of three compartments in series, in which the pH of the intermediate compartment is greater than that of the bulk phases. But these observations could not be explained in terms of an analogous system involving an intermediate compartment of low pH, or in terms of a carrier mediated system. The transport function of the three-compartment system can be described in the form of an equation, and it is found that a pH difference of less than 0.5 unit may explain our observations on weak electrolyte transport.

Amines↗

PubMed1997

The effect of different amines added to eluents as silanol masking agents on the chromatographic behavior of some diuretics in reversed-phase high-performance liquid chromatography using C18 packings.

A preliminary gradient separation in reversed-phase liquid chromatography of a mixture of 25 solutes (diuretics, probenecide, and atenolol) is carried out using several C18 columns and an aqueous phosphoric acid solution (pH 3.2)-acetonitrile mobile phase as a control. Using this separation, the chromatographic behavior of these solutes is studied using 11 water-soluble primary, secondary, and tertiary amine modifiers in the range of 0.7-7.5 mM and a Spherisorb C18 column. This study reveals the presence in the complex sample of two groups of solutes with positive (five typical solutes showed improvements in peak symmetry and retention) or negative responses using these amines as mobile phase modifiers. After experimentation in the presence of amines, these differences are related to solute structure. Hexylamine is found to be an effective masking agent of silanols because of its structure and small required concentration. On these bases, the silanophilic and hydrophobic character of typical solutes and several C18 packings are evaluated under isocratic elution and a relative effectiveness index for amines, and a method for their assessment is proposed. The role of the amine structure on solute retention and the importance of selecting amines of suitable hydrophobic character, molecular geometry, and concentration is discussed. A model of the formation and stabilization of the silanol-amine complex based on hydrophobic and ionic interactions is also proposed.

Amines↗

PubMed1980

Mode of inactivation of putrescine oxidase by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide or metal ions.

1. Putrescine oxidase [EC 1.4.3.10] was partially inactivated by reaction with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), rapidly. The activity of the modified enzyme toward putrescine was 5.6% of that of the native enzyme. Moreover, the optimal pH and Km value of the modified enzyme for putrescine changed from 9.0 to 10.5 and from 0.23 to 3.4 mM, respectively. This modified enzyme showed activity toward monoamines such as n-butylamine, n-hexylamine, and n-octylamine, which are not substrates of the native enzyme. 2. Heavy metal ions inactivated putrescine oxidase completely. Hg2+ had the stronger ability to inactivate it. This inactivation was due to the dissociation of FAD from the enzyme molecule. The Fad-free enzyme had no ability to reassociate FAD, in contrast to the apoenzyme. The enzyme treated with Hg2+ showed characteristic behavior on SDS-polyacrylamide gel electrophoresis. 3. From the results of chemical modification it was deduced that a carboxyl group plays an important role in binding the substrate.

Apoenzymes↗

PubMed1982

Purification of RNA associated and unassociated forms of 1,4-alpha-glucan branching enzyme from rat liver.

Two molecular forms (BE-I and -II) of 1,4-alpha-glucan branching enzyme were purified from rat liver by affinity chromatography on glycogen-adipoyldihydrazide-Sepharose 4B and glycogen-ethylenediamine-Sepharose 4B, respectively, after hydrophobic chromatography on hexylamine-Sepharose 4B, as single proteins with the same molecular weight of 82,000 on SDS-polyacrylamide gel electrophoresis. By comparing their UV spectra and by RNA detection on polyacrylamide gels after electrophoresis, BE-I and -II were identified to be RNA associated and unassociated forms, respectively. The molecular weights of BE-I and -II estimated by Sephadex G-200 gel filtration were 91,000 and 98,000, respectively, indicating that both forms consist of a monomer. As Be-II had about half the specific activity of BE-I, the RNA component was not essential for the activity of the rat liver branching enzyme, and it was also dissociable from the protein component (BE-II) on polyacrylamide gel electrophoresis at pH 7.3, whereby BE-II showed a heterogeneity of at least three microspecies as revealed by protein staining as well as by activity staining of the gels. Using the antibody against BE-I, BE-I and -II were indistinguishable on immunodiffusion, and the activity inhibition rate of BE-II by the antibody was almost the same as that of BE-I if their specific activities are considered, indicating that the RNA component may have no effect on the enzyme-antibody reaction. Immunochemically no isoenzyme was detected for this enzyme in rat tissues.

1,4-alpha-Glucan Branching Enzyme↗

PubMed1998

Concurrent high-performance liquid chromatographic measurement of loxapine and amoxapine and of their hydroxylated metabolites in plasma.

The dibenzoxazepine neuroleptic loxapine, its N-demethylated metabolite amoxapine, and their 7- and 8-hydroxymetabolites were measured simultaneously in plasma by reversed-phase high-performance chromatographic method. An original liquid-liquid extraction procedure was performed, consisting in coextraction of the substances together with a water-miscible solvent (acetonitrile) by a non-water-miscible solvent (toluene). The substances were separated on a 5-microm CN 25-cm column, and eluted with a mobile phase consisting of acetonitrile-acetic acid 0.5 N (30:70) and hexylamine (0.05%). They were detected by ultraviolet spectrophotometry at 310 nm. Clozapine was used as internal standard. Linearity was demonstrated in the range of 10 to 250 microg/l, and detection limits were found to be 3.5 to 6.3 microg/l according to the substance. Within-day repeatability ranged from 2.7% to 6.5%, and between-day reproducibility ranged from 0.9% to 20.2%. The extraction procedure provided a mean absolute recovery of 51.1% (range, 40.7% to 58.6%) with a mean coefficient of variation of 4.2%. This technique was applied to the concurrent determination of plasma concentrations of the compounds in 10 patients administered loxapine 75 to 600 mg daily. Steady state plasma levels of loxapine were significantly correlated with oral doses (n = 10, r = 0.858, p < 0.002). In conclusion, the method proved to be a convenient and reproducible procedure allowing the simultaneous measurement of loxapine, amoxapine, and their metabolites in patients.

Amoxapine↗

PubMed1991

Local and systemic carcinogenic effects of alkylating carcinogens in rats treated by intravesicular administration.

Several nitrosamines and an azoxyalkane have been administered intravesically to groups of 12 female F344 rats, twice a week for 20 or 30 weeks. Many of the nitrosamines were as efficacious in giving rise to the same tumors of internal organs as when similar doses were administered orally, showing that absorption from the bladder was as rapid as from other sites. The tumors produced included lung and kidney tumors by nitrosodimethylamine, colon and Zymbal gland tumors by azoxymethane, liver tumors by methylnitrosoethylamine (but not by nitrosodimethylamine), liver and esophagus tumors by nitrosodiethylamine, liver and lung tumors by methylnitrosamino-3-pyridylbutanone, liver tumors by nitrosomorpholine, and tumors of the esophagus by methylnitroso-n-butylamine, 2,6-dimethyl-nitrosomorpholine and methylnitrosamino-N,N-dimethylethylamine. Bladder tumors were induced by intravesicular administration of only low doses of nitrosobis-(2-oxopropyl)amine and to a lesser extent by methylnitroso-n-hexylamine and nitroso-(2-hydroxypropyl)(2-oxopropyl)amine, which all induced tumors systemically in addition. The bladder mucosa seemed to lack enzymes necessary to activate most nitrosamines to locally acting proximate carcinogens, but was quite transparent to the passage of carcinogenic nitrosamines present in the urine into the body to induce tumors in distant organs.

Administration, Intravesical↗

PubMed2005

In vivo accumulation of different hypericin ion pairs in the urothelium of the rat bladder.

OBJECTIVE: To optimise the diagnostic and phototherapeutic efficacy of hypericin in superficial bladder cancer, by developing a bladder instillation fluid that does not depend on the presence of plasma proteins for an appropriate and reliable urothelial uptake of hypericin. MATERIALS AND METHODS: Sodium hypericinate (in distilled water, in sodium phosphate buffer, or in polyethylene glycol) and several other hypericinate salts (potassium, lysine, TRIS or hexylamine) were instilled with no plasma constituents into the rat bladder. The accumulation of hypericin was assessed with fluorescence microscopy. RESULTS: The diagnostic and phototherapeutic efficacy of hypericin depends on its ability to penetrate the tumour lesions sufficiently to show a fluorescent signal or elicit a photodynamic response. Several instillation fluids meet the purpose, as the urothelial accumulation of hypericin was similar to that obtained with the instillation fluid supplemented with plasma proteins, used in clinical practice. The highest concentrations of hypericin in the urothelium of the rat bladder were obtained with hypericin instillation solutions prepared with distilled water or 20% polyethylene glycol 400 in distilled water. Fluorescence microscopy showed that hypericin was selectively localized in the urothelium. Furthermore, all variables investigated (hydrophilic/lipophilic balance, pH, saline, presence of organic solvent) can dramatically influence the in vivo accumulation of hypericin. CONCLUSION: An appropriate and reliable urothelial uptake of hypericin does not depend on the presence of plasma protein supplements in the bladder instillation fluid.

Administration, Intravesical↗

PubMed1988

Sensory irritation and pulmonary irritation of C3-C7 n-alkylamines: mechanisms of receptor activation.

Sensory irritation due to inhalation of a series of alkylamines was estimated from the decrease in respiratory rate in normal (non-cannulated) mice (American standard method E 981-84, 1984). The irritation effects rapidly reached stable levels. The concentration-response relationships followed Michaëlis-Menten equations. The maximum response decreased with increasing chain length. The concentrations depressing the respiratory rate by 50% (RD-50) were 184, 121, 97, 51, and 27 p.p.m. for n-propylamine, n-butylamine, n-pentylamine, n-hexylamine, and n-heptylamine, respectively. It is suggested that the receptor is activated partly by the amines and partly by hydroxide ions. The nose has a scrubbing effect, which partly protects the lungs against water soluble irritants. Pulmonary irritation was estimated from the decrease in respiratory rate in tracheally cannulated mice. The plateau-level of the response was reached slowly. The respective concentrations depressing the respiratory rate by 50% (tRD-50) were 416, 300, 128, 66, and 36 p.p.m. for the C3-C7 n-amines. It is suggested that the pulmonary receptor environment is lipophilic and the receptor, probably the J-receptor, is activated chemically by the amines. The sensory and pulmonary irritation data were used to estimate workplace exposure limits (TLV's) which protect against these effects.

Amines↗

PubMed1989

Deamination of aliphatic amines of different chain lengths by rat liver monoamine oxidase A and B.

Monoamines with from 1 to 18 straight chain carbon atoms have been analysed as rat liver monoamine oxidase substrates. Methylamine and ethylamine are clearly not substrates of monoamine oxidase (MAO). n-Propylamine, n-butylamine, n-dodecylamine and n-octadecylamine are relatively poor substrates, i.e. with high Km and low Vmax values for the enzyme. n-Pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine and n-decylamine are all very good MAO substrates. All these aliphatic amines are found to be typical type B substrates according to the sensitivities of the enzyme towards the selective MAO-B inhibitor selegiline and the MAO-A inhibitor, clorgyline. The sensitivity towards selegiline with respect to these amines is even higher, i.e. Ki = 1 x 10(-9) M for butylamine, than that of the typical type B substrate beta-phenylethylamine (Ki = 1 x 10(-8) M). The sensitivity towards selegiline decreases slightly with increasing chain length of these aliphatic amines.

Amines↗

PubMed1984

Role of a low-pH environment in adenovirus enhancement of the toxicity of a Pseudomonas exotoxin-epidermal growth factor conjugate.

A conjugate of Pseudomonas exotoxin and epidermal growth factor (PE-EGF) inhibits proteins synthesis in KB cells, and this inhibition is increased by adenovirus. Protein synthesis inhibition is dependent on the amount of adenovirus and PE-EGF used and the time of incubation of cells with these agents. With 1 microgram of adenovirus and 0.5 micrograms of PE-EGF per ml, protein synthesis is inhibited about 80% in a 60-min experiment. Under these conditions neither adenovirus nor PE-EGF alone has any effect. In the presence of several weak bases or monensin, the enhancement of toxicity was substantially inhibited; half-maximal inhibition was achieved with 40 microM chloroquine, 10 mM ammonium chloride, 5 mM methylamine, 0.1 mM N-hexylamine and 1 microM monensin. At the concentrations employed, none of the inhibitors affected the amount of virus taken up or bound to the cell surface, and chloroquine had no effect on the amount of EGF taken up in 60 min. Chloroquine did not prevent the toxicity of the PE-EGF (5 micrograms/ml) alone. Because these compounds are known to elevate the pH in receptosomes, it seems likely that the acidification of the receptosome either enhances the lysis of the membrane by adenovirus or enhances some other step in the release of PE-EGF.

Adenoviruses, Human↗