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At least 811 records · Page 45Linked to original sources
PubMed1995

Efficacy of a variety of disinfectants against Actinobacillus pleuropneumoniae serotype 1.

The efficacy of 23 disinfectants (including the most commonly used chemical groups) and 6 quaternary ammonium compound based commercial formulations against Actinobacillus pleuropneumoniae serotype 1 (ATCC 4074) was studied. The organisms were tested in suspension and carrier tests with serum as the organic matter. Chloramine-T, hydrogen peroxide, glutaraldehyde, and mercurochrome alone, and a quaternary ammonium compound formulation containing 10% benzalkonium chloride, 2.5% glutaraldehyde, 6.8% glyoxal, and 6% formaldehyde were effective in all tests, regardless of the presence or absence of organic load. All but 2 of the nonformulated disinfectants (sodium hypochlorite and an iodophor) caused at least a 3-log10 reduction in colony-forming units in the suspension test. However, most of the disinfectants were not as effective in the carrier test as in the suspension test; this difference ranged from a 1- to 5-log10 reduction in colony-forming units. In addition, the presence of serum considerably reduced the disinfectant capacities of most of the compounds tested, particularly in the carrier test. These results indicate the importance of selecting suitable disinfectants for routine use on surfaces contaminated with this organism, especially in the presence of organic matter. Chloramine-T and the aforementioned commercial formulation were also tested directly under field conditions in pig nurseries, confirming their high effectiveness.

Actinobacillus pleuropneumoniae↗
PubMed1977

[Study of the feasibility and conditions for disinfecting materials made of chemical fibers by immersion in solutions of several disinfectants].

The authors studied the disinfection regimens of materials made of lavsan, capron, acetate, triacetate, viscose by the method of immersion into the disinfecting solutions of dichlor-I, chloramine calcium hypochlorite salt, potassium and sodium salt of dichlorisocianuric acid, sulfochloranthin, dichlordimethylhydantoin, catapin, amphocept, sodium metasilicate, hydrogen, peroxide, formalin, phenol, benzylphenol. As revealed, solutions of the following preparations could be recommended for the disinfection of linen made of chemical fibers at the foci of intestinal and droplet infection, except tuberculosis: sulfochloranthin (0.2%), amphocept and chloramine B (1%), sodium metasilicate, formalin, catapin, hydrogen peroxide with a 0.5% of washing solution (2%); these solutions gave a reliable effect in 60 minutes at room temperature, and in 20 to 30 minutes at a temperature of 40--45 degrees C.

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↗
PubMed1997

Chemical modification of amino acid residues in glycerinated Vorticella stalk and Ca(2+)-induced contractility.

The glycerinated stalk of the peritrich ciliate Vorticella, was treated with various reagents to chemically modify the amino acid residues. The influences of these modifcations on spasmoneme contractility were investigated. First, it was confirmed that the spasmoneme contraction is not inhibited by alteration of SH groups. It was also demonstrated that chemical modification of methionine and tryptophan residues abolishes spasmoneme contractility. The reagents used for chemical modification were N-bromosuccinimide (NBS), chloramine T, and 2-hydroxy-5-nitrobenzyl bromide (HNBB), which abolished spasmoneme contractility at concentrations of 40-50 microM, 200-300 microM, and 4 mM, respectively. These results suggest that, along with Ca2+ binding proteins, there are other as yet to be identified proteins involved in contractility.

2-Hydroxy-5-nitrobenzyl Bromide↗
PubMed1989

Application of an affinity electrophoretic and in situ oxidation method to the study of the equine protease inhibitory proteins.

An affinity method was developed to investigate the interaction between protease and protease inhibitor by incorporating a protease incubation step into a two-dimensional electrophoretic separation of the plasma protease inhibitory proteins. This involved the application of the isoelectric focusing gel to filter paper saturated in the protease of choice before being placed on the second-dimensional polyacrylamide electrophoresis gel. General protein staining or immunoblotting was used to detect the protein or ligand in the complex. An in situ oxidation method was developed using the reagent chloramine T to investigate the effect of this reagent on the complexing abilities and inhibitory activities of the protease inhibitory proteins. Oxidation was performed either after electrophoresis prior to staining for enzyme inhibition or during two-dimensional electrophoresis prior to the aforementioned protease incubation. The latter allowed the effect of oxidation on complex formation to be examined. Whole plasmas were utilized as the sources of protease inhibitory proteins with the human and mouse being used as models. The equine protease inhibitory system was examined by the two methods and shown to consist of three classes of inhibitory proteins based on their susceptibilities to oxidation and abilities to form complexes with various proteases.

Animals↗
PubMed2000

Monochloramine enhances Fas (APO-1/CD95)-induced apoptosis in Jurkat T cells.

Monochloramine derivatives are physiological oxidants produced by activated neutrophils. We report the effects of chemically prepared monochloramine (NH2Cl) on Fas-induced apoptosis in Jurkat T cells. When the cells were pretreated with NH2Cl (20-70 microM), subsequent addition of apoptosis-inducing anti-Fas antibody resulted in a synergistic enhancement of apoptosis. Treatment of NH2Cl (50-70 microM) alone resulted in a slight but definite apoptosis. Caspase activities, as measured by DEVD and IETD cleavage activities, were also elevated synergistically by NH2Cl + anti-Fas antibody stimulation. Moreover, a broad caspase inhibitor, Z-VAD-fmk, almost completely inhibited the apoptosis induced by NH2Cl and/or anti-Fas antibody. Fas expression on the Jurkat cell surface was not affected by the NH2Cl treatment. After 3 h of NH2Cl treatment, when the apoptosis was beginning to increase, the cells showed cytochrome c release from mitochondria, proteolytic activation of caspase 9, and poly (ADP-ribose) polymerase cleavage, regardless of Fas stimulation. Z-VAD-fmk almost completely inhibited this poly (ADP-ribose) polymerase cleavage, but not cytochrome c release. By contrast, Fas stimulation alone resulted in neither cytochrome c release nor caspase 9 activation at 3 h, and the increase in the DEVD cleavage activity and apoptosis became evident at later time points. These results suggested that NH2Cl enhanced Fas-induced apoptosis through the cytochrome c release and caspase 9 activation at the early stage of apoptosis. Chloramines derived from acute inflammation may modify immune reactions, such as cell-mediated cytotoxicity and some autoimmune diseases, by the enhancement of Fas-induced apoptosis.

Apoptosis↗
PubMed1994

Selective oxidation of methionyl residues in the human recombinant secretory leukocyte proteinase inhibitor. Effect on the inhibitor binding properties.

Binding of the human recombinant secretory leukocyte proteinase inhibitor (SLPI) [native and with the methionyl residues at positions 73, 82, 94 and 96 of domain 2 oxidized to the sulfoxide derivative (Met(O) SLPI)] to bovine alpha-chymotrypsin (alpha-chymotrypsin) [native and with the Met192 residue converted to the sulfoxide derivative (Met(O) alpha-chymotrypsin)] as well as to native bovine beta-trypsin (beta-trypsin), which does not contain methionyl residues, has been investigated between pH 4.0 and 8.0, and between 10.0 degrees C and 30.0 degrees C, from thermodynamic and/or kinetic viewpoints. By increasing the number of oxidized methionyl residues present at the proteinase:inhibitor contact interface (from 0 to 3), the adducts investigated are increasingly destabilized and the relaxation time of the complexes into conformers less stable is enhanced. On the other hand, the selective oxidation of methionyl residues of SLPI and alpha-chymotrypsin, by reaction with chloramine T, does not affect the proteinase inhibition recognition mechanism. Therefore, even though conformational changes may occur in the conversion of native SLPI and native alpha-chymotrypsin to their Met(O) derivatives, a localized steric hindrance can be considered as the main structural determinant accounting for the reported results.

Amino Acid Sequence↗
PubMed1997

Cysteine-specific radioiodination of proteins with fluorescein maleimide.

A protocol is described for coupling of carrier-free iodine to protein sulfhydryl groups via fluorescein maleimide. 125I is first coupled to fluorescein maleimide in the presence of chloramine T. Iodination is stopped with sodium thiosulfate, and the iodine-substituted fluorescein maleimide is reacted with free cysteines of the protein. Excess label is then removed by gel-permeation chromatography. The procedure avoids exposition of the protein to oxidative conditions and does not require purification of the labeled carrier reagent. Suitability of the method for a given protein can be evaluated spectrophotometrically without employing radioactivity. It can be applied under denaturing conditions and may be particularly useful with mutant proteins carrying engineered single cysteine residues at sites that are not functionally critical.

Bacterial Proteins↗
PubMed1999

Reduction of lipid hydroperoxides by apolipoprotein B-100.

We have previously isolated two proteins which can reduce phosphatidylcholine hydroperoxide (PC-OOH) from human blood plasma and identified one of the proteins as apolipoprotein A-I (Mashima, R. , et al. (1998) J. Lipid Res. 39, 1133-1140). In the present study we have identified the other protein as apolipoprotein B-100 (apo B-100) by amino acid sequence analysis of its tryptic peptides. The reactivity of lipid hydroperoxides with apo B-100 decreased in the order of PC-OOH > linoleic acid hydroperoxide > cholesteryl ester hydroperoxide under our experimental conditions. Pretreatment of apo B-100 with chloramine T, an oxidant of methionine, diminished the PC-OOH-reducing activity, indicating that some of 78 methionines are responsible for the reduction of PC-OOH. Despite the presence of 6 methionines in albumin, albumin was inactive to reduce PC-OOH. Free methionine was also inactive. These data suggest that the accessibility and binding of lipid hydroperoxides to the protein methionine residues are crucial for reduction of lipid hydroperoxides.

Apolipoprotein B-100↗
PubMed2000

Single-step purification of recombinant human growth hormone (hGH) directly from bacterial osmotic shock fluids, for the purpose of (125)I-hGH preparation.

A good quality tracer, to be used in the radioimmunoassay of human growth hormone, was prepared by applying the chloramine-T iodination technique to the recombinant product obtained after a single-step high-performance size-exclusion chromatography purification of a bacterial osmotic shock fluid. The labeling reaction presented a yield of about 65% and the purified tracer exhibited an antibody binding of approximately 50% (NIDDK reference antiserum diluted 1:600,000). These values are very similar to those obtained by radioiodinating highly purified clinical-grade recombinant human growth hormone obtained from the same periplasmic extract after the regular six-step purification process. Both tracers provided the same accuracy, when evaluated with the use of commercial-quality control samples in a classical radioimmunoassay methodology, their stability being practically identical: about 18% decrease in antibody binding after 2 months of storage at -20 degrees C. The novel approach permits the utilization of transformed Escherichia coli strains as a source of freshly prepared, radioiodination-grade recombinant proteins, capable of providing better reproducibility and reagent continuity.

Chloramines↗
PubMed1991

Inactivation modifiers of Na+ currents and the gating of rat brain Na+ channels in planar lipid membranes.

Rat brain Na+ channels whose inactivation process had been removed either by batrachotoxin (BTX) or veratridine (VT) were reconstituted into planar lipid membranes. The voltage dependence of the open probability (Po) of the channel, of the opening and closing rate constants, and the conductance and relative permeability for Na+ and K+ were studied in voltage-clamp conditions in the presence of agents known to modify the inactivation of Na+ currents. In relation to alkaloids (BTX, VT, and aconitine), it was found that once a Na+ channel was modified by BTX or VT, the addition of another alkaloid did not change further the gating and permeation properties of the channel over a period of about 1 h. Once the inactivation process of the channels is removed by BTX, the addition of a proteolytic enzyme (trypsin) or an halogenated compound (chloramine-T, CT) induced profound and specific modifications on the opening and closing events of Na+ channels: (1) the voltage dependence of the channel Po shifted to more hyperpolarized potentials; (2) this voltage shift can be explained by equal hyperpolarizing voltage shifts of the opening and closing rate constants of the channel; (3) although the gating properties of the channel were modified by these compounds, the permeation properties of the channel, as evaluated by the conductance and the selectivity to Na+ and K+ ions, were unaltered; (4) trypsin and CT were active only in the intracellular side of the channel and were irreversible within the time course of the experiments, suggesting covalent modifications of the channel. Inactivation modifiers also affected the gating of toxin-activated single Na+ channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed1986

Kinetics of sodium current and gating current in the frog node of Ranvier.

The experiments were done on voltage-clamped nodes of Ranvier of the frog. The aim was to study the kinetics of sodium current INa and gating current Igat over a large potential range (-92 to -12 mV) and to compare the time constants for the turning-on of INa or Igat with those for the turning-off measured at the same potential. Sodium tail currents were recorded at different postpulse potentials. Inactivation was inhibited by a few min treatment with 0.5 mM chloramine-T (Wang 1984). The sodium permeability was activated by a 0.4 ms pulse from holding potential (-92 mV) to about 0 mV. At the peak of INa the membrane was repolarized to postpulse potentials between -92 and -12 mV. At E greater than -60 mV the tail currents decayed with two time constants, tau 1 and tau 2, reflecting presumably the turning-off and the inactivation of the sodium permeability. The relation between tau 1 and postpulse potential was bellshaped with a maximum at -32 mV. The tail currents could also be fitted by the Hodgkin-Huxley equation with the sodium activation variable m raised to the second or third power. At E less than -50 mV tau m off was equal to 2 tau 1 or 3 tau 1, respectively, whereas at E greater than -25 mV tau m off was equal to tau 1. In addition, the time constant of the turning-on of sodium activation m (tau m on) was determined, assuming INa approximately m2 (with a small initial delay) or INa approximately m3 (without an initial delay). At -22 mV and -12 mV the ratio tau m off/tau m on was close to 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Voltage and temperature dependence of normal and chemically modified inactivation of sodium channels. Quantitative description by a cyclic three-state model.

(1) Voltage clamp experiments were done on single myelinated nerve fibres of the frog, Rana esculenta, with 10 mM TEA in the external solution to block potassium channels. (2) The potential dependence of normal sodium current inactivation was studied over a potential range of V = -50 mV to 80 mV. At depolarizations (V greater than or equal to 30 mV) inactivation is diphasic. The relative contribution of the fast phase increases from 0.4 at V = 30 mV to 0.96 at V = 80 mV. At resting potential (V = 0 mV) recovery from inactivation shows a sigmoidal time course. At strong hyperpolarization (V = -50 mV) recovery is diphasic with a predominant fast phase. (3) For a quantitative description of these findings a cyclic three-state model of inactivation, with one open and two closed states, is formulated. The potential dependence of the rate constants is determined and calculations from this model are compared with the experimental data. (4) To test the availability of the proposed model, normal inactivation was modified by treatment with 0.6 mM chloramine-T. This substance causes inactivation to become slow and incomplete; the potential dependence of steady-state inactivation becomes non-monotonic. All these effects are explained as quantitative changes of the rate constants in the cyclic inactivation model. (5) The influence of temperature on normal inactivation was studied at a range of 8-20 C. Both time constants as well as the two inactivation components are temperature-dependent. For a quantitative description of temperature effects by the cyclic model, the activation enthalpies of the rate constants are evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The mechanisms of sodium current inhibition by benzocaine in the squid giant axon.

(1) The effects of benzocaine on the ionic currents in the voltage-clamped squid giant axon have been examined under various conditions; intact axons, axons internally perfused with CsF and axons dialysed with tetraethylammonium ions were used. (2) Both the steady state outward (potassium) current and the early transient (sodium) current were reduced by ca. 50% by benzocaine (1 mM). (3) Plots of the changes produced by benzocaine (1 mM) in the Hodgkin-Huxley parameters for the steady state activation (m infinity), the steady state inactivation (h infinity) and the time constants (tau m and tau h) for activation and inactivation of the sodium current are shown. The m infinity and h infinity curves are shifted in positive and negative directions respectively on the voltage axis. The time constants are not greatly affected. (4) In axons in which the sodium current inactivation had been largely removed by treatment with chloramine T, the sodium current was still reduced by ca. 50% by 1 mM benzocaine and the positive shift in activation remained unchanged. (5) The dependence on benzocaine concentration (for less than or equal to 2 mM) of the peak sodium current reduction and the shift in steady state inactivation have been determined. (6) It is concluded that in the squid axon the effects on inactivation are not the main reason for the reduction of the sodium current by benzocaine and that, in common with many other neutral anaesthetics, there are at least two sites at which benzocaine acts.

Animals↗
PubMed1988

The existence of a highly tetrodotoxin sensitive Na channel in freshly dispersed smooth muscle cells of the rabbit main pulmonary artery.

To characterize the inward current recorded from single smooth muscle cells of the rabbit main pulmonary artery, a voltage clamp procedure using patch pipettes filled with high Cs solution to inhibit K currents was employed. Under superfusion with normal physiological salt solution, application of a command potential to -10 mV from the holding potential of -80 mV elicited an inward current comprising fast and slow components. In Ca-free solution containing 2.5 mM Mn and 134 mM Na, the major part of the slow inwart current (Islow) ceased, but a transient fast inward current (Ifast) remained. A reduction in the Na concentration in the bath solution inhibited the amplitude of Ifast. Both nicardipine (30 nM) and diltiazem (1-10 microM) inhibited Islow but had no effect on Ifast. Application of tetrodotoxin (greater than 1 nM) in Ca free solution inhibited the amplitude of Ifast in a dose-dependent manner with a dissociation constant of 8.7 nM. Chloramine-T (0.3 mM) increased the peak amplitude and reduced the rate of decay of Ifast and completely inhibited Islow. These results suggest that the inward curent generated in the smooth muscle cells of the rabbit main pulmonary artery is associated with activation of a voltage-dependent Ca channel and a tetrodotoxin-sensitive Na channel.

Animals↗
PubMed1984

Iodination of myofibrils and myosin.

The relative reactivity of the tyrosine side chains in the proteins of skeletal muscle myofibrils was determined using iodination techniques. The destruction of ATPase activity of myofibrils and myosin by lactoperoxidase and chloramine-T iodination could be prevented by the attachment of cysteamine to the sulphydryl groups prior to the iodination reaction and subsequent regeneration with thioglycolate or dithiothreitol. Iodination using 1,3,4,6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril did not require cysteamine treatment for retention of full enzymatic activity. The specific activity of the different proteins varied markedly with desmin, troponin-T, and tropomyosin having the highest labelling with all three iodination procedures. In contrast the myosin light chains had low specific activity when labelled in myofibrils or intact myosin. The isolated light chains, however, were much more highly iodinated. It appears that iodination may be a useful technique for examining protein-protein interactions in the myofibril.

Adenosine Triphosphatases↗
PubMed1989

ATP-sensitive potassium channels in adult mouse skeletal muscle: characterization of the ATP-binding site.

Single K+-selective channels were studied in excised inside-out membrane patches from dissociated mouse toe muscle fibers. Channels of 74 pS conductance in symmetrical 160 mM KCl solutions were blocked reversibly by 10 microM internal ATP and thus identified as ATP-sensitive K+ channels. The channels were also blocked reversibly by mM concentrations of internal adenosine, adenine and thymine, but not by cytosine and uracil. The efficacy of the reversible channel blockers was higher when they were present in internal NaCl instead of KCl solutions. An irreversible inhibition of ATP-sensitive K+ channels was observed after application of several sulphydryl-modifying substances in the internal solution: 0.5 mM chloramine-T, 50 mM hydrogen peroxide or 2 mM N-ethylmaleimide (NEM). Large-conductance Ca-activated K+ channels were not affected by these reagents. The presence of 1 mM internal ATP prevents the irreversible inhibition of ATP-sensitive K+ channels by NEM. The results suggest that internal Na+ ions increase the affinity of the ATP-sensitive K+ channel to ATP and to other reversible channel blockers and that a functionally important SH-group is located at or near the ATP-binding site.

Adenosine↗
PubMed1986

Influence of the cultivation, devitalization and preservation of Staphylococcus aureus ATCC 12598 on the activity of cell-bound protein A.

Different culture conditions, devitalizing treatments, and preservation procedures were tested for the production of protein A-bearing cells of Staphylococcus aureus ATCC 12598. Native cells with the highest IgG-binding activity were obtained after cultivation at 37 degrees C for 24-48 h in enriched media. Devitalization by ethanol, 1-propanol, formaldehyde, glutardialdehyde, chloramine T, and by heat, reduced the protein A activity depending on the duration of treatment. The protein A content of devitalized cells were best preserved by storage at -20 degrees C or by lyophilization. Staphylococcal preparations with a stable IgG-binding activity of 20 mg/g bacteria, which are very suitable for coagglutination tests, were produced by culture in TSB medium, followed by devitalization with 1-propanol and lyophilization.

1-Propanol↗