Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AMMONIUM COMPOUNDS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed2004

Resistance of spheroplasts and whole cells of Pseudomonas aeruginosa to bactericidal activity of various biocides: evidence of the membrane implication.

To emphasise the role of outer and inner membranes in the resistance of Pseudomonas aeruginosa to bactericidal activity of various disinfectants, spheroplasts and whole cells were compared. Spheroplasts are more sensitive than whole cells to quaternary ammonium compounds such as didecyl dimethyl ammonium bromide (DDAB) and C16-benzalkonium chloride. The outer membrane acts as a barrier to prevent these disinfectants from entering the cell. It seems to have no influence on activities of smaller molecules such as C12, C14-benzalkonium chlorides and sodium dichloroisocyanurate. For tri-sodium phosphate, the presence of outer membrane emphasized the action of the molecule. Moreover, resistance of DDAB-adapted spheroplasts to bactericidal activity of DDAB is higher than the resistance of non-adapted spheroplasts. This suggests that the inner membrane could also play a role in resistance to DDAB.

Anti-Infective Agents, Local↗
PubMed1982

Standard-suspension-test: influence of bovine albumin, saline and water of standard hardness on M.E.-values.

Notwithstanding considerable international agreement upon the principle of the quantitative suspension test differences still exist between the main variants of this test, in particular on the diluent to be used in the test mixture. For this reason the influence of the main variables - i.e. bovine albumin (0.03%), NaCl (physiol. saline) and divalent ions (water of standard hardness) - on the activity of the different classes of disinfectants have been investigated. Using so-called borderline concentrations only a small protein effect of 0.03% bovine albumin was found with a phenolic product, quaternary ammonium compounds and aldehydes. A substantial protein effect was observed only with chlorine compounds. The chlorine consumption in the present Dutch Standard Suspension Test is approx. 20 ppm. In tests without a protein load as well as in the presence of 0.03% bovine albumin M.E.-values using saline as the diluent were usually higher than in tests using water of standard hardness (WSH) or distilled water (DW). M.E.-values of quaternary ammonium compounds in WSH were significantly lower than those in DW, presumably due to the antagonizing effect of divalent cations (Mg++ and Ca++). The different views regarding the aim of quantitative suspension tests are discussed. In The Netherlands the opinion prevails that these tests should have at least some relationship with practical conditions. The use of water of standard hardness as a diluent and the incorporation of a slight protein challenge are in agreement with this standpoint.

Disinfectants↗
PubMed1998

Model tests for the efficacy of disinfectants on surfaces. IV. Communication: dependence of test results on the amount of contamination and the kind of active substance.

In the assessment of efficacy of surface disinfectants, many influencing factors have to be taken into account. One essential item is whether the surface to be disinfected is clean or soiled. Among the feasible soilings, the blood is of particular consequences because it ads impediments to many disinfecting agents. This paper shows to what extent the impairment of the efficacy of typical active agents depends on the blood burden of the surfaces. Therefore, test surfaces (varnished plywood) were contaminated with 0.01 to 0.08 ml of coagulating blood per test area (3 cm2). The blood contained cells of Staphylococcus aureus as test germs. The disinfection was effected by immersing the test objects in the disinfecting solution for 5 seconds and mingling the adhering disinfecting solution (about 0.02 ml) with the coagulated blood on the test surface with a glass spatula for about 20 seconds. Subsequently, the test objects remained in a horizontal position at room conditions for 4 hours and then the numbers of surviving test germs were determined. The graphical representation of the results shows that the efficacy curves of formaldehyde and phenol lie very closely together, i.e. their effect is hardly impaired by the different blood burdens of the test areas. The efficacy curves of glutaraldehyde, peracetic acid, chloramine T, and quaternary ammonium compounds lie very far apart from each other. To achieve the same microbicidal effect (log N/N0 = -5) when the contaminating amount is raised from 10 microliters/3 cm2 to 80 microliters/3 cm2, the concentration of chloramine T has to be raised by a factor of 5.4, peracetic acid by a factor of 9, glutaraldehyde by a factor of 24, quaternary ammonium compound even by a factor of 67. Ethanol and sodium hypochlorite showed a divergent behaviour. For ethanol, the efficacy diminution produced by increasing the contamination amount by a factor of 4 can be compensated by raising the concentration from 50% to about 70%. But again and again, there were test objects on which the number of germs able to reproduce had only been lowered by a factor of about 10(-3). At the highest contamination of 80 microliters/3 cm2, even 95% ethanol proved to be completely insufficient. With sodium hypochlorite even at the lowest contamination of 10 microliters/3 cm2, a microbicidal effect of only about 10(-5) was obtained. With increasing contamination, the highest achievable microbicidal effect clearly decreased. It is remarkable that the microbicidal effect of this active agent decreased with increasing concentrations. The results show how important it is in testing the efficacy of disinfecting agents to exactly lay down the amount of contaminating substances. To find out how safely an agent works under harder circumstances, the dependence of the microbicidal effect from the amount of contaminating substances per test area has to be determined.

Blood↗
PubMed1994

Choline derivatives and sodium fluoride protect acetylcholinesterase against irreversible inhibition and aging by DFP and paraoxon.

A light addressable potentiometric sensor was used to measure acetylcholinesterase (AChE) activity in order to evaluate the protective effects of quaternary compounds and NaF against enzyme phosphorylation and aging by two organophosphates. The use of the immobilized AChE made possible the quick removal of reagents (i.e., organophosphate, 2-pralidoxime, and protectant), thereby permitting accurate determination of AChE activity before and after phosphorylation and aging. Paraoxon was 15-fold more potent in inhibiting AChE than DFP, while the percent aging following phosphorylation by diisopropylfluorophosphate (DFP) was much higher. Sodium fluoride (NaF), the most effective protectant against phosphorylation and aging, and the quaternary ammonium compounds reduced significantly AChE inhibition by DFP and paraoxon, to similar degrees. Even though the percent AChE activity that was lost to aging was reduced by these agents, aging as a percent of phosphorylated AChE was not reduced. Thus, their major effect was in reducing the percent AChE phosphorylation, which consequently resulted in reduction of total aged AChE. The finding that quaternary ammonium compounds protect against phosphorylation is consonant with the proposed presence of the active site of AChE in an aromatic gorge.

Acetylcholinesterase↗
PubMed1995

Structure and interaction of inhibitors with the TEA/H+ exchanger of rabbit renal brush border membranes.

The renal secretion of organic cations (OCs) involves a carrier-mediated exchange of OC for H+ in the luminal membrane of proximal cells. To assess the influence of chemical structure on the interaction of potential substrates with this process we examined the effect of a series of quaternary ammonium compounds on the transport of the OC tetraethylammonium (TEA) in a preparation of isolated renal brush-border membrane vesicles. Apparent inhibitory potency varied over a factor of 10(4), as expressed in inhibitor coefficients (KiTEA) whose approximate values ranged from 0.5 microM to 5 mM. The poorest inhibitors of TEA/H+ exchange were those molecules with carboxyl or hydroxyl residues, whereas the addition of methylene groups to a parent molecule tended to increase inhibitory potency. A plot of apparent KiTEA versus calculated octanol:water partition coefficient (expressed in terms of a relative lipophilicity factor) showed a clear correlation between these two parameters, although there was considerable variability between apparent lipophilicity and KiTEA for molecules with very different parent structures. For select groups of molecules with similar parent structures (e.g., the n-tetraalkylammoniums or the 4-phenylpyridinium, 3-phenylpyridinium, and quinolinium compounds) the correlation between calculated lipophilicity and apparent KiTEA was more marked. However, even within these groups of closely related parent structures, there appeared to be subtle, but systematic, variations in inhibitory potency that may have been related to the influence of steric factors on the binding of inhibitors to the TEA/H+ exchanger. We conclude that the lipophilic nature of a quaternary ammonium compound represents the predominant factor in the binding to and subsequent inhibition of, luminal TEA/H+ exchange. Specific steric factors may influence the binding of substrate to the exchanger, but play a secondary role in this interaction.

Acridines↗
PubMed1999

The effect of hydrocarbon chain length, pH, and temperature on the binding and bactericidal effect of amphiphilic betaine esters on Salmonella typhimurium.

Amphiphilic betaine esters are quaternary ammonium compounds (QAC) with rapid microbicidal action. They are often labeled 'soft antimicrobial agents', since the compounds hydrolyze spontaneously into betaine and fatty alcohols, thus not only losing their surface active properties and toxicity but also becoming amenable to metabolic use. The present results show that the bactericidal effects of 1-decyl (B10), 1-dodecyl (B12), and 1-tetradecyl (B14) betaine esters on Salmonella typhimurium 395 MS decreased with decreasing hydrocarbon chain lengths, decreased at pH below neutral, and were lower at 0 degrees C that at 30 degrees C. At least part of the decreased effect at pH 4.0 as compared to pH 6.0 can be explained by reduced binding. However, reduced binding cannot explain the decrease in the microbicidal effect at 0 degrees C since the binding of B 14 was the same at 0 degrees C and 30 degrees C although 10-30 times higher concentrations were required at 0 degrees C to achieve the same microbicidal effect as at 30 degrees C. Neither can differences in binding explain the great differences seen in microbicidal effect between QAC with different chain lengths. It is proposed that the membrane deformation resulting in killing of S. typhimurium is more efficiently achieved with QAC with longer hydrocarbon chains and that reduced fluidity of the outer membrane of the bacteria at lower temperatures antagonizes the bactericidal effect. Charge interaction seems to be more important for the binding and bactericidal effect for the QAC with shorter hydrocarbon chains. The different effects of pH, temperature, and hydrocarbon chain length on binding, bactericidal effect, and hydrolysis have to be taken into account when optimizing disinfection and the subsequent elimination of disinfectants.

Betaine↗
PubMed1995

Long-chain alkanoylcholines, a new category of soft antimicrobial agents that are enzymatically degradable.

A new category of amphiphilic hydrolyzable quaternary ammonium compounds with rapid and high levels of antimicrobial activity was studied. The compounds, alkanoylcholines with hydrocarbon chains of 10 to 14 carbon atoms, are hydrolyzed by butyrylcholine esterase, which is present in human serum and mucosal membranes. The hydrolysis products are common components of human metabolism. Alkanoylcholines were tested and found to be active against gram-negative and gram-positive bacteria as well as yeasts. The microbicidal activities of the alkanoylcholines were comparable to the activities of the stable quaternary ammonium compounds of corresponding chain length and increased with an increasing number of carbon atoms. The compounds were also found to be hydrolyzed by enzymes present in certain microorganisms. The degradation was achieved after reaching the microbicidal effect.

Anti-Bacterial Agents↗
PubMed1984

Analysis of plasmids mediating gentamicin resistance in methicillin-resistant Staphylococcus aureus.

Gentamicin-resistance plasmids in methicillin-resistant Staphylococcus aureus isolated from four Australian hospitals have been studied. All the plasmids conferred resistance to gentamicin, tobramycin, kanamycin and all but one conferred resistance to quarternary ammonium compounds. Plasmids which only carried these resistance determinants were ca 15.3 megadaltons and were only found in isolates from one hospital. The most common plasmid was ca 18.0 megadaltons and in addition encoded trimethoprim resistance. Two plasmids, one of ca 19.6 megadaltons and one of ca 28.5 megadaltons were found to carry the penicillinase determinant. However only the larger of these encoded heavy metal ion resistance and was sensitive to quaternary ammonium compounds. EcoR1 analysis indicated that all but the ca 28.5 megadalton plasmid were closely related. The EcoR1 analysis of the ca 28.5 megadalton plasmid indicated that it could have resulted from recombination between a gentamicin resistance determinant and a penicillinase plasmid.

DNA Restriction Enzymes↗
PubMed2001

Capillary electrochromatography of hydrophobic amines on continuous beds.

The capillary electrochromatographic separation performance of hydrophobic amines and a related quaternary ammonium compound on continuous beds based on polymers of acrylamide has been studied. The chromatographic bed is polymerized in situ and the character of the polymers with regard to hydrophobicity and charge has been systematically changed by regulating its content of isopropyl and sulfonate ligands, respectively. The best performance was obtained for columns with a molar ratio of 1:80 for the sulfonate and isopropyl groups, and resulted in efficiencies up to 200000 plates per meter. The effects on retention, resolution and elution order by ionic strength, pH, and content of acetonitrile in the mobile phase have been investigated. The quaternary ammonium compound was always the least retained irrespective of pH. By increasing the pH, a reversal of the migration order between the tertiary and secondary amine was obtained. The results indicate a complex migration/retention mechanism where ion-exchange, adsorption and electrophoretic mobilities play a role. The concentration limit of detection could be lowered from 1.3 microg/mL to 50 pg/mL by using a high content of 2-propanol (96%) in the sample compared to dissolving the analytes in the mobile phase.

Amines↗
PubMed1981

Inhibition of human sperm motility by inhibitors of choline acetyltransferase.

Human spermatozoa contain choline acetyltransferase (ChA), acetylcholinesterase and acetylcholine (ACh). There is no storage pool for ACh in spermatozoa. Therefore, ChA inhibitors should exhibit dramatic effects in the alteration of levels and turnover of ACh and sperm motility. The effects of two groups of ChA inhibitors, 2-benzoylethyltrimethylammonium (BETA) and related compounds and halogenoacetylcholines (cholinesters of iodo-, bromo- and chloroacetic acids; XACh, where X = l, Br or Cl), on the motility index of human ejaculated sperm were studied. These investigations gave the following results: 1) BETA was a potent inhibitor of ChA from monkey brain (I50, 4.8 x 10(-6) M), homogenates of rat spermatozoa (I50, 6.5 x 10(-5) M) and homogenates of human spermatozoa (I50, 5.6 x 10(-5) M). It decreased the motility index of human spermatozoa (I50, 8.5 x 10(-8) M) at concentrations higher than 10(-8) M after a contact time of 5 to 60 min. It decreased the motility index of human spermatozoa by about 80% after 5 min and by 95% after 1 hr at a concentration of 10(-6) M. 2) There was a positive relationship between the inhibition of ChA and the depression of the motility index of human spermatozoa among these inhibitors. Both the number of motile cells and the graded motility were decreased. 3) All ChA inhibitors studied are quaternary ammonium compounds that do not significantly cross membrane barriers. 4) Both human sperm cells and human sperm cell homogenates had the same ChA activity. 5) Seventy-five percent of ChA activity could be washed away from human spermatozoa. 6) The same amount of ChA inhibition was observed when BETA was added to the homogenate of sperm cells or whole sperm cells. All of these observations indicate that sperm cell ChA is accessible to BETA and related quaternary ammonium compounds. These studies indicate that ACh is possibly synthesized by the tail and is a local hormone in the coordination of contraction and relaxation cycles of spermatozoan flagella.

Acetylcholine↗
PubMed1986

Effect of Betaine on Enzyme Activity and Subunit Interaction of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase from Aphanothece halophytica.

The presence of betaine, a quaternary ammonium compound, at a concentration (0.5 molar) reported to accumulate inside Aphanothece halophytica in response to increasing external salinity, slightly promoted ribulose-1,5-bisphosphate (RuBP) carboxylase activity. KCl at 0.25 molar inhibited RuBP carboxylase about 55%. Betaine relieved the inhibition by 0.25 m KCl and the original uninhibited activity was restored at 1 m betaine. Other osmoregulatory solutes such as sucrose and glycerol also reduced KCl inhibition, though to a lesser extent than betaine. Proline had no effect. The protective effect of betaine against KCl inhibition of RuBP carboxylase activity was also observed in other cyanobacteria, i.e. Synechococcus ACMM 323, Plectonema boryanum, and Anabaena variabilis, and in the photosynthetic bacterium Rhodospirillum rubrum but not in Chromatium vinosum. Apart from betaine, other quaternary ammonium compounds, i.e. sarcosine and trimethylamine-N-oxide (TMAO), but not glycine, also protected the enzyme against KCl inhibition and the effectiveness of such compounds appeared to correlate with the extent of N-methylation. Heat and cold inactivation of the enzyme could be protected by either betaine or KCl. However, best protection occurred when both betaine and KCl were present together. The K(m) (CO(2)) was not altered by either betaine or KCl, nor when they were present together. However, the K(m) (RuBP) was increased about 5-fold by KCl, but was unaffected by betaine. The presence of betaine together with KCl lowered the KCl-raised K(m) (RuBP) by about half. The extent of the dissociation of the enzyme molecule under the condition of low ionic strength was reduced by either betaine or KCl alone and more so when they were present together. Glycine, sarcosine, and TMAO were more effective than betaine or KCl in lowering the extent of the dissociation of the enzyme molecule.

Journal Article↗
PubMed1988

Ion Homeostasis in Chloroplasts under Salinity and Mineral Deficiency : I. Solute Concentrations in Leaves and Chloroplasts from Spinach Plants under NaCl or NaNO(3) Salinity.

Spinach (Spinacia oleracea var "Yates") plants in hydroponic culture were exposed to stepwise increased concentrations of NaCl or NaNO(3) up to a final concentration of 300 millimoles per liter, at constant Ca(2+)-concentration. Leaf cell sap and extracts from aqueously isolated spinach chloroplasts were analyzed for mineral cations, anions, amino acids, sugars, and quarternary ammonium compounds. Total osmolality of leaf sap and photosynthetic capacity of leaves were also measured. For comparison, leaf sap from salt-treated pea plants was also analyzed. Spinach plants under NaCl or NaNO(3) salinity took up large amounts of sodium (up to 400 millimoles per liter); nitrate as the accompanying anion was taken up less (up to 90 millimoles per liter) than chloride (up to 450 millimoles per liter). Under chloride salinity, nitrate content in leaves decreased drastically, but total amino acid concentrations remained constant. This response was much more pronounced (and occurred at lower salt concentrations) in leaves from the glycophyte (pea, Pisum sativum var "Kleine Rheinländerin") than from moderately salt-tolerant spinach. In spinach, sodium chloride or nitrate taken up into leaves was largely sequestered in the vacuoles; both salts induced synthesis of quarternary ammonium compounds, which were accumulated mainly in chloroplasts (and cytosol). This prevented impairment of metabolism, as indicated by an unchanged photosynthetic capacity of leaves.

Journal Article↗
PubMed1988

Transport characteristics of propantheline across rat intestinal brush border membrane.

The transport mechanism of propantheline, an anti-acetylcholine quaternary ammonium compound, has been studied using brush border membrane vesicles isolated from rat small intestine. The uptake of propantheline was facilitated by the transmembrane electrical potential difference (cell interior negative) induced by NaSCN, NaI or valinomycin. But this effect was a secondary action; in the initial phase of propantheline uptake (less than 5 min), there was no facilitating effect. When the transmembrane potential difference was induced after propantheline uptake had reached a steady state, there was an overshoot of the drug. Therefore, it is suggested that the transport of propantheline across the brush border membrane consists of at least two processes. In the first, propantheline rapidly binds to the brush border membrane, in the second it enters into epithelium driven by the negative transmembrane electrical potential difference. Cationic tertiary amines such as chlorpromazine, imipramine and promethazine markedly inhibited propantheline uptake. These results suggest that there is a common absorption process for tertiary amines and quaternary ammonium compounds.

Animals↗
PubMed1987

Intestinal permeation of nonquaternary amines: a study with telenzepine and pirenzepine in the isolated mucosa of guinea pig jejunum and colon.

Previous studies which demonstrated an intestinal secretion of quaternary ammonium compounds in the jejunum were extended to nonquaternary amines. Telenzepine and pirenzepine, two structurally similar compounds differing in lipid solubility, were administered either to the lumen or blood side of isolated mucosae of guinea pig jejunum and colon mounted in a flux chamber. Transepithelial permeation of both drugs from blood to lumen side was 3.2 to 18 times higher than in the reverse, absorptive direction. The indicated net secretion was highest with telenzepine in the colon. At 7 degrees C transepithelial permeation was restricted to paracellular shunt fluxes. In the colon, the highest cellular concentrations were observed after blood side administration of telenzepine and pirenzepine (500 and 150% of that of the incubation solution). At 7 degrees C these values were reduced to 1 of 5 and 1 of 8 of the values at 37 degrees C. At pH 6.6, 7.4 or 8.2, no differences in the colonic secretion of telenzepine were seen; cellular concentration increased with increasing pH only after luminal administration. Under all conditions, the colon acidified the luminal solution by roughly 0.4 pH units. Phenoxybenzamine, shown previously to inhibit the jejunal secretion of quaternary ammonium compounds, inhibited the secretion of pirenzepine and telenzepine in both gut segments, but did not affect blood-to-lumen permeation of N-methylscopolamine in the colon. In addition, phenoxybenzamine reduced the cellular content in the colon but had little or no effect on pirenzepine or telenzepine content in the jejunum. The results are consistent with a model in which the nonquaternary amines are secreted in the jejunum by two serial transport steps specific for the base cations; an additional diffusion of the free bases is of importance in the basolateral membrane. In the colon, carrier-mediated influx increases with lipophilicity of the base cations, whereas efflux across the brush border is limited to diffusion of the free bases; concomitant luminal acidification and formation of base cations maintains the diffusion gradient.

Animals↗
PubMed2001

Studies of the synthesis of SSZ-25 zeolite in a "mixed-template" system.

The synthesis of aluminosilicate zeolite, SSZ-25, is described using a two-component organic guest molecule strategy. This method has been recently described by us and is quite effective in crystallizing a variety of aluminosilicate zeolites with reduction in template cost. In this instance the original organic guest component used in the discovery of SSZ-25, N',N',N'-trimethyl-2-adamantammonium cation, is used in conjunction with a variety of smaller amines. The amine is the major organic component in the synthesis and the quaternary ammonium compound, while a minor component, is essential for structure direction to the desired zeolite product. Studies here show that the adamantyl component is preferentially taken up during crystal growth. Our studies showed that the use of the multi-organic component approach to synthesis resulted in a faster and cheaper route to crystallizing SSZ-25. The SSZ-25 has been described in the literature as having the MWW topology and as such has two different channel systems accessed by 10-ring openings; the channel systems do not intersect. One set of 10-rings open into large cavities. In this study we used NMR spectroscopy to examine the as-made materials and to see if the two organic components are used in different capacities in the synthesis, probing if the admantyl component is only found in these larger cavities. The crystalline products could be affected by solvent extraction with polar solvents like dimethylformamide: the X-ray powder patterns and elemental analyses changed with solvent treatment. The solvent-treated crystals were studied by NMR spectroscopy, elemental analysis, and argon adsorption. The two-component organic guest approach was also found to be quite flexible not only with regard to the amine, but also towards the quaternary ammonium compounds. Non-adamantyl polycyclic templates could be used, and polar but non-quaternized adamantyl derivatives also succeeded in directing towards SSZ-25 formation. On the other hand. in one instance it was shown that the two-component approach favors SSZ-25 as the kinetic product but at longer run times Ostwald ripening was observed, leading to the disappearance of SSZ-25 and formation of ferrierite zeolite and quartz.

Journal Article↗
PubMed1976

Microbial oxidation of methane and methanol: crystallization and properties of methanol dehydrogenase from Methylosinus sporium.

Obligate methylotrophs are divisible into two types on the basis of ultrastructural biochemical characteristics. Both groups possess a soluble phenazine methosulfate (PMS)-dependent methanol dehydrogenase. In addition, particulate PMS-dependent methanol dehydrogenase and PMS-independent methanol oxidase have been found in the type I membrane group. A procedure was developed for the crystallization of methanol dehydrogenase from the soluble fraction of the type II obligate methylotroph Methylosinus sporium. This is the first report of a crystalline methanol dehydrogenase from a methylotrophic bacterium. The crystallized enzyme is homogeneous as judged by ultracentrifugation and by acrylamide gel electrophoresis. In the presence of an electron acceptor (phenazine or phenazinium compound) and an activator (ammonium compound), the crystallized enzyme catalyzed the oxidation of primary alcohols and formaldehyde. Secondary, tertiary, and aromatic alcohols were not oxidized. The molecular weight of the enzyme as estimated by gel filtration is approximately 60,000, and as estimated by sedimentation equilibrium analysis it is 62,000. The sedimentation constant (S20,W) is 2.9. The subunit size determined by sodium dodecyl sulfate-gel electrophoresis is approximately 60,000. The amino acid composition and spectral properties of the enzyme are also presented. Antisera prepared against the crystalline enzyme are nonspecific, they cross-reacted and inhibited isofunctional enzymes from other obligate methylotrophic bacteria.

Alcohol Oxidoreductases↗
PubMed1988

Physiology of chemoreceptor cells in the legs of the freshwater prawn, Macrobrachium rosenbergii.

1. Chemoreceptor cells in the first pereiopods (legs) of the freshwater prawn, Macrobrachium rosenbergii, were investigated using single-unit, extracellular electrophysiological recording techniques on an isolated, perfused leg preparation. 2. The cells were responsive to aqueous extracts of food (shrimp, mullet, trout chow), a salt mixture (artificial sea-water), amino acids (L-arginine HCl, taurine), a quaternary ammonium compound (betaine HCl) and ammonium chloride. 3. The response specificity of individual cells ranged from narrow to broad, but on average was broad, being more similar to chemoreceptor cells of freshwater crayfish than of marine spiny or clawed lobsters. 4. Responses were generally excitatory. However, some responses were inhibitory, the first such demonstration in aquatic crustaceans. 5. These electrophysiological results highly correlate with results of feeding behavioral assays carried out on M. rosenbergii.

Animals↗
PubMed2006

[Inactivation of mycobacteria by disinfectants with a tuberculocidal label].

INTRODUCTION: Disinfectants available in Venezuela, registered as tuberculocidal, and used in clinical and laboratory settings were tested for their mycobactericidal activity. METHODS: The European Standard Quantitative Suspension test prEN14348 was used in simulated clean and dirty conditions. The disinfectants tested included Gerdex and K-ller (both containing the quaternary ammonium compound dimethyl benzyl lauryl ammonium bromide in concentrations of 10% and 0.16% respectively), Microplus-Action (5% polymethylene urea), Cidex (2% glutaraldehyde) and Cidex OPA (0.55% ortho-phthalaldehyde). The mycobactericidal activity was evaluated with M. smegmatis ATCC 19420 and in clinical isolates of M. fortuitum, M. chelonae and M. abscessus. The tuberculocidal activity was assessed with M. tuberculosis H37Rv. RESULTS: Cidex and Cidex OPA were effective against all the test organisms, showing a > 5-log 10 reduction in CFU after 5 minutes of exposure under both clean and dirty conditions. Gerdex and K-ller only achieved a 2-log reduction in M. tuberculosis, M. abscessus and M. chelonae CFU, even after 60 minutes of exposure. Micro Plus Action showed a 4-log reduction in M. tuberculosis viability but less than a 1-log reduction in M. abscessus and M. chelonae CFUs after 60 minutes of incubation. CONCLUSION: The tuberculocidal activity claimed by the manufacturers of several disinfectants sold in Venezuela, Gerdex, K-ller and Microplus-Action is inaccurate when tested by European norms. The use of these products for disinfecting material used in critical and semi-critical patients could result in iatrogenic infections.

Antitubercular Agents↗