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PubMed1984

Identification of an antigen of Onchocerca volvulus of possible diagnostic use.

Adult Onchocerca volvulus worms obtained by enzyme digestion from nodules of infected Mexicans were radio-isotope labelled by the chloramine-T or Bolton-Hunter methods. No antigenic determinants were detected in extracts of worms labelled by the chloramine-T method but 3 antigens were detected in extracts of the Bolton-Hunter labelled worms. Two were present in such small amounts that it was impractical to investigate them further, but a major component of mol. wt 20 kDa was purified by gel filtration and used in a serological survey of inhabitants of villages in Southern Mexico. Using the 20 kDa antigen, which is superficially located on both sexes of O. volvulus, sera from both non-endemic and endemic regions were analysed by radio-immunoprecipitation of this antigen. In Southern Mexico, the average sensitivity of the test was 92%, and the specificity 98%. Whilst the 20 kDa antigen did not detect antibodies in the sera of Trinidadians infected with Wuncheria bancrofti or Mansonella ozzardi, this antigen detected high levels of antibodies in Indians exposed to W. bancrofti.

Animals↗
PubMed2006

Hypochlorous acid-derived modification of phospholipids: characterization of aminophospholipids as regulatory molecules for lipid peroxidation.

Hypochlorous acid (HOCl), an inflammatory oxidant derived from neutrophil myeloperoxidase, can chlorinate cytosolic proteins and nuclear DNA bases of target cells by passing through the cell membrane. However, little is known about the consequences of HOCl-derived modification of cell membrane components, including phospholipids. In this study, we characterize the reaction of HOCl with phospholipid molecules and found that aminophospholipids are the key molecules that chemically regulate lipid peroxidation. Upon incubation with HOCl, the peroxidation of egg yolk phosphatidylcholine was significantly enhanced in the presence of phosphatidylethanolamine (PE). In contrast, the peroxidation was significantly inhibited in the presence of phosphatidylserine (PS). On the basis of mass spectrometric and electron paramagnetic resonance characterization, the initiator of the peroxidation was identified as the nitrogen-centered radical originating from PE-derived chloramines, especially N,N-dichlorinated PE, a major product in the HOCl-modified PE. Although PS was also chlorinated upon reaction with HOCl, the formed chloramine rapidly decomposed to phosphatidylglycolaldehyde, a novel class of lipid aldehyde. Formation of phosphatidylglycolaldehyde was also confirmed in the porcine brain PS and erythrocyte cell membrane ghost exposed to HOCl. These results provide a novel mechanism for the HOCl-induced oxidative damage and its endogenous protection in the cell membrane at the site of inflammation.

Chromatography, High Pressure Liquid↗
PubMed2003

Tribromopyrrole, brominated acids, and other disinfection byproducts produced by disinfection of drinking water rich in bromide.

Using gas chromatography/mass spectrometry (GC/MS), we investigated the formation of disinfection byproducts (DBPs) from high bromide waters (2 mg/L) treated with chlorine or chlorine dioxide used in combination with chlorine and chloramines. This study represents the first comprehensive investigation of DBPs formed by chlorine dioxide under high bromide conditions. Drinking water from full-scale treatment plants in Israel was studied, along with source water (Sea of Galilee) treated under carefully controlled laboratory conditions. Select DBPs (trihalomethanes, haloacetic acids, aldehydes, chlorite, chlorate, and bromate) were quantified. Many of the DBPs identified have not been previously reported, and several of the identifications were confirmed through the analysis of authentic standards. Elevated bromide levels in the source water caused a significant shift in speciation to bromine-containing DBPs; bromoform and dibromoacetic acid were the dominant DBPs observed, with very few chlorine-containing compounds found. Iodo-trihalomethanes were also identified, as well as a number of new brominated carboxylic acids and 2,3,5-tribromopyrrole, which represents the first time a halogenated pyrrole has been reported as a DBP. Most of the bromine-containing DBPs were formed during pre-chlorination at the initial reservoir, and were not formed by chlorine dioxide itself. An exception wasthe iodo-THMs, which appeared to be formed by a combination of chlorine dioxide with chloramines or chlorine (either added deliberately or as an impurity in the chlorine dioxide). A separate laboratory study was also conducted to quantitatively determine the contribution of fulvic acids and humic acids (from isolated natural organic matter in the Sea of Galilee) as precursor material to several of the DBPs identified. Results showed that fulvic acid plays a greater role in the formation of THMs, haloacetic acids, and aldehydes, but 2,3,5-tribromopyrrole was produced primarily from humic acid. Because this was the first time a halopyrrole has been identified as a DBP, 2,3,5-tribromopyrrole was tested for mammalian cell cytotoxicity and genotoxicity. In comparison to other DBPs, 2,3,5-tribromopyrrole was 8x, 4.5x, and 16x more cytotoxic than dibromoacetic acid, 3-chloro-4-(dichloromethyl)-5-hydroxy-2-[5H]-furanone [MX], and potassium bromate, respectively. 2,3,5-Tribromopyrrole also induced acute genomic damage, with a genotoxic potency (299 microM) similar to that of MX.

Bromides↗
PubMed2004

Transformation of aromatic ether- and amine-containing pharmaceuticals during chlorine disinfection.

Many of the human pharmaceuticals detected in municipal wastewater effluent, surface water, and groundwater contain functional groups that could undergo transformation reactions during chlorine disinfection. To assess the potential importance of these reactions to the environmental fate of pharmaceuticals, the rate of transformation of a group of compounds was measured over a pH range of 5-10. Several of the pharmaceuticals reacted rapidly with free chlorine (i.e., HOCl/OCl-) and would be expected to undergo transformation under the conditions typically encountered in many chlorine disinfection systems. For compounds containing aromatic ether functional groups, the rate of transformation was strongly affected bythe other substituents on the ring. The amine-containing pharmaceuticals underwent a rapid reaction with hypochlorous acid to form chlorinated amines, which could be converted back into the parent compound by reaction with thiosulfate. In the absence of thiosulfate, the chlorinated amines slowly decomposed to form species that could not be converted back into the parent compound. The reaction rates of the pharmaceuticals with combined chlorine (i.e., chloramines) were significantly slower, and transformation of the compounds would not be expected under the conditions encountered during chloramination.

Amines↗
PubMed2006

Cyanogen bromide formation from the reactions of monobromamine and dibromamine with cyanide ion.

Cyanide ion (CN-) was found to reactwith monobromamine (NH2Br) and dibromamine (NHBr2) according to the reactions NH2Br + CN- + H20 --> NH3 + BrCN + OH- and NHBr2 + CN- + H20 --> NH2Br + BrCN + OH- with respective reaction rate constants of 2.63 x 10(4) M9-10 s(-1) and 1.31 x 10(8) M(-1) s(-1). These values were found to be 10(5)-10(6) times greater than those for the corresponding reactions between chloramine species and CN-. As a result, bromamines, even if present at relatively low concentrations, would tend to outcompete chloramines in reacting with CN-, and thus, the formation of BrCN would predominate that of ClCN through these reaction mechanisms. The NH2Br reaction was found to be general-acid-catalyzed. The third-order catalysis rate constants for H+, H2PO4-, HPO4(2-), H3BO3, and NH4+ correlated linearly with their corresponding acid dissociation constants, consistent with the Brønsted-Pedersen relationship. The NHBr2 reaction did not undergo catalysis. A model was developed to predict the concentrations of bromamines over time on the basis ofthe above two reactions with CN- and bromamine formation/decomposition reactions previously reported.

Bromides↗
PubMed1990

Synthesis and in vivo antitumor activity of 2-amino-9H-purine-6-sulfenamide, -sulfinamide, and -sulfonamide and related purine ribonucleosides.

A number of 6-sulfenamide, 6-sulfinamide, and 6-sulfonamide derivatives of 2-aminopurine and certain related purine ribonucleosides have been synthesized and evaluated for antileukemic activity in mice. Amination of 6-mercaptopurine ribonucleoside (7a) and 6-thioguanosine (7b) with chloramine solution gave 9-beta-D-ribofuranosylpurine-6-sulfenamide (8a) and 2-amino-9-beta-D-ribofuranosylpurine-6-sulfenamide (sulfenosine, 8b), respectively. Selective oxidation of 8a and 8b with 3-chloroperoxybenzoic acid (MCPBA) gave (R,S)-9-beta-D-ribofuranosylpurine-6-sulfinamide (9a) and (R,S)-2-amino-9-beta-D-ribofuranosylpurine-6-sulfinamide (sulfinosine, 9b), respectively. However, oxidation of 8a and 8b with excess of MCPBA gave 9-beta-D-ribofuranosylpurine-6-sulfonamide (10a) and 2-amino-9-beta-D-ribofuranosylpurine-6-sulfonamide (sulfonosine, 10b), respectively. Similarly, amination of 5'-deoxy-6-thioguanosine (7c) afforded the 6-sulfenamide derivative (8c), which on controlled oxidation gave (R,S)-2-amino-9-(5-deoxy-beta-D-ribofuranosyl)purine-6-sulfinamide (9c) and the corresponding 6-sulfonamide derivative (10c). Treatment of 6-thioguanine (12) with aqueous chloramine solution gave 2-amino-9H-purine-6-sulfenamide (13). Oxidation of 13 with 1 molar equiv of MCPBA afforded (R,S)-2-amino-9H-purine-6-sulfinamide (14), whereas the use of 4 molar equiv of MCPBA furnished 2-amino-9H-purine-6-sulfonamide (15). The resolution of R and S diastereomers of sulfinosine (9b) was accomplished by HPLC techniques. The structures of (R)-9b and 10b were assigned by single-crystal X-ray diffraction studies. (R)-9b exists in the crystal structure in four crystallographically independent conformations. Of the 18 compounds evaluated, 13 exhibited very significant anti-L1210 activity in mice. Sulfenosine (8b) at 22 mg/kg per day X 1 showed a T/C of 170, whereas sulfinosine (9b) at 173 mg/kg per day X 1 showed a T/C of 167 against L1210 leukemia. The 5'-deoxy analogue of sulfinosine (9c) at 104 mg/kg per day also showed a T/C of 172. A single treatment with 8b, 9b, and 9c reduced body burdens of viable L1210 cells by more than 99.8%.

2-Aminopurine↗
PubMed1990

Synthesis and antitumor evaluation in mice of certain 7-deazapurine (pyrrolo[2,3-d]pyrimidine) and 3-deazapurine (imidazo[4,5-c]pyridine) nucleosides structurally related to sulfenosine, sulfinosine, and sulfonosine.

7-Deaza (pyrrolo[2,3-d]pyrimidine) and 3-deaza (imidazo[4,5-c]pyridine) congeners of sulfenosine (5a and 9), sulfinosine (6a and 10), and sulfonosine (7a) have been prepared and evaluated for their antileukemic activity in mice. Amination of 2-amino-7-beta-D-ribofuranosylpyrrolo[2,3-d]pyrimidine-4(3H)-th ion e (4a) and its 2'-deoxy analogue (4c) with a chloramine solution gave the corresponding 4-sulfenamides (5a and 5c, respectively), which on selective oxidation with m-chloroperoxybenzoic acid (MCPBA) gave the respective diastereomeric 2-amino-7-beta-D-ribofuranosyl-pyrrolo[2,3-d]pyrimidine-4-sulfinamide (7-deazasulfinosine, 6a) and its 2'-deoxy derivative (6c). A similar amination of 7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d]pyrimidine-4(3H)- thione (4b) gave the corresponding 4-sulfenamide derivative (5b). Oxidation of 5b with 1 molar equiv of MCPBA furnished (R,S)-7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d]pyrimidine- 4- sulfinamide (6b), whereas use of excess of MCPBA afforded the corresponding sulfonamide derivative (7b). Treatment of 3-deaza-6-thioguanosine (8) with a chloramine solution gave 3-deazasulfenosine (6-amino-1-beta-D- ribofuranosylimidazo[4,5-c]pyridine-4-sulfenamide, 9). Controlled oxidation of 9 with MCPBA afforded 3-deazasulfinosine (10). As gauged by increases in the mean postinoculation life spans of L1210 inoculated mice, none of these nucleosides exhibited biologically significant activity (T/C greater than or equal to 125). Even so, antileukemic activity appeared to be influenced, albeit not uniformly, by structural modifications in the base and carbohydrate moieties of sulfenosine and sulfinosine. Thus, while several of the compounds were lacking in cytotoxic activity, eight others (4c, 5a, 5c, 6a, 6b, 7b, 9, and 10) were estimated to have reduced body burdens of viable L1210 cells by 16-77%.

Animals↗
PubMed2001

Myeloperoxidase-dependent generation of hypochlorite-modified proteins in human placental tissues during normal pregnancy.

Myeloperoxidase (MPO), which is released from cytoplasmic granules of activated phagocytes by a degranulation process, reacts with H(2)O(2) (generated during the oxidative burst) and chloride ions to generate hypochlorous acid/hypochlorite (HOCl/OCl(-)). HOCl, a strong oxidant, in turn reacts with proteins to form HOCl-modified proteins. The presence of these cytotoxic chloramines during inflammatory conditions, eg, atherosclerosis and glomerular and tubulointerstitial injury, suggested that chloramines are powerful oxidants that can have profound biologic effects. In the present study, immunoreactive MPO was identified in fetal membranes and the basal plate and in maternal and fetal blood cells of human placental tissues. Monocytes/macrophages represent the major cell source for MPO in human placental tissues. Immunohistochemical findings revealed that HOCl-modified proteins are present in normal human term placenta but not during the first trimester of pregnancy (Weeks 7 to 12). HOCl-modified proteins were localized in areas formed by fetally derived cells as well as maternal decidual tissues, ie, areas where fetal extravillous trophoblast cells invade the maternal tissue and stimulate the maternal immune system. HOCl-modified proteins, products of the MPO-H(2)O(2)-chloride system in vivo, were not present intracellularly, but immunoreactivity for HOCl-modified proteins was cell-associated and/or present in the extracellular matrix. Extravillous trophoblast cells, which may also exert phagocytic activities, showed no intracellular immunoreactivity for MPO or HOCl-modified proteins. The present findings indicate that the generation of HOCl-modified proteins during normal pregnancy is a physiologic rather than a pathophysiologic process.

Chorionic Villi↗
PubMed2002

Mechanistic studies of N-nitrosodimethylamine (NDMA) formation in chlorinated drinking water.

Studies were conducted to investigate the hypothesis that N-nitrosodimethylamine (NDMA) is a potential disinfection by-product specifically produced during chlorination or chloramination. Experiments were conducted using dimethylamine (DMA) as a model precursor. NDMA was formed by the reaction of DMA with free chlorine in the presence of ammonia and also with monochloramine. We proposed a mechanism for NDMA formation in chlorinated or chloraminated water, which does not require nitrite as in N-nitrosation. The critical NDMA formation reactions consist of (i) the formation of monochloramine by combination of free chlorine with ammonia, (ii) the formation of 1,1-dimethylhydrazine (UDMH) intermediate from the reaction of DMA with monochloramine followed by, (iii) the oxidation of UDMH by monochloramine to NDMA, and (iv) the reversible chlorine transfer reaction between free chlorine/monochloramine and DMA which is parallel with (i) and (ii). A kinetic model was also developed to validate the proposed mechanism.

Carcinogens↗
PubMed1979

Insulin receptor: covalent labeling and identification of subunits.

Two methods were used to label insulin receptors covalently with 125I. In the first, an aryl azide derivative of insulin, 125I-labeled 4-azido-2-nitrophenyl-insulin, was synthesized and used to photolabel the binding region of the insulin receptor in rat liver membranes and human placenta membranes. In the second, insulin receptors were purified from rat liver membranes and labeled with 125I by use of chloramine-T; this method presumably has no specificity for the binding region of the receptor. The proteins labeled by both methods were analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis after or without reduction by dithiothreitol. The photoaffinity label specifically labeled a single band in both liver and placenta that had an apparent molecular weight of 135,000 after reduction. A band with similar mobility was present in the chloramine-T-labeled preparation, which also contained a second major band with an apparent molecular weight of 45,000. Without reduction, both methods resulted in a single labeled band with an apparent molecular weight of about 310,000. These results indicate that the insulin receptor of both liver and placenta has a subunit of molecular weight 135,000 that binds insulin and that the receptor may be composed of at least two different subunits that are linked together or greatly stabilized by disulfide bonds.

Affinity Labels↗
PubMed1995

Chlorination of tyrosyl residues in peptides by myeloperoxidase and human neutrophils.

Hypochlorous acid is the major strong oxidant generated by human neutrophils, and it has the potential to cause much of the tissue damage that these inflammatory cells promote. It is produced from hydrogen peroxide and chloride by the heme enzyme myeloperoxidase. To unequivocally establish that hypochlorous acid contributes to inflammation, a stable and unique marker for its reaction with biomolecules needs to be identified. In this investigation we have found that reagent hypochlorous acid reacts with tyrosyl residues in small peptides and converts them to chlorotyrosine. Purified myeloperoxidase in combination with hydrogen peroxide and chloride, as well as stimulated human neutrophils, chlorinated tyrosine in the peptide Gly-Gly-Tyr-Arg. Rather than reacting directly with the aromatic ring of tyrosine, hypochlorous acid initially reacted with an amine group of the peptide to form a chloramine. The chloramine then underwent an intramolecular reaction with the tyrosyl residue to convert it to chlorotyrosine. This indicates that tyrosyl residues in proteins that are close to amine groups will be susceptible to chlorination. Peroxidases are the only enzymes capable of chlorinating an aromatic ring. Furthermore, myeloperoxidase is the only human enzyme that produces hypochlorous acid under physiological conditions. Therefore, chlorotyrosine will be a specific marker for the production of hypochlorous acid in vivo and for the involvement of myeloperoxidase in inflammatory tissue damage.

Amino Acid Sequence↗
PubMed1998

Oxidation of high density lipoproteins. II. Evidence for direct reduction of lipid hydroperoxides by methionine residues of apolipoproteins AI and AII.

Human high density lipoproteins (HDL) can reduce cholesteryl ester hydroperoxides to the corresponding hydroxides (Sattler W., Christison J. K., and Stocker, R. (1995) Free Radical Biol. & Med. 18, 421-429). Here we demonstrate that this reducing activity extended to hydroperoxides of phosphatidylcholine, was similar in HDL2 and HDL3, was independent of arylesterase and lecithin:cholesteryl acyltransferase activity, was unaffected by sulfhydryl reagents, and was expressed by reconstituted particles containing apoAI or apoAII only, as well as isolated human apoAI. Concomitant with the reduction of lipid hydroperoxides specific oxidized forms of apoAI and apoAII formed in blood-derived and reconstituted HDL. Similarly, specific oxidized forms of apoAI accumulated upon treatment of isolated apoAI with authentic cholesteryl linoleate hydroperoxide. These specific oxidized forms of apoAI and apoAII have been shown previously to contain Met sulfoxide (Met(O)) at Met residues and are also formed when HDL is exposed to Cu2+ or soybean lipoxygenase. Lipid hydroperoxide reduction and the associated formation of specific oxidized forms of apoAI and apoAII were inhibited by solubilizing HDL with SDS or by pretreatment of HDL with chloramine T. The inhibitory effect of chloramine T was dose-dependent and accompanied by the conversion of specific Met residues of apoAI and apoAII into Met(O). Canine HDL, which contains apoAI as the predominant apolipoprotein and which lacks the oxidation-sensitive Met residues Met112 and Met148, showed much weaker lipid hydroperoxide reducing activity and lower extents of formation of oxidized forms of apoAI than human HDL. We conclude that the oxidation of specific Met residues of apoAI and apoAII to Met(O) plays a significant role in the 2-electron reduction of hydroperoxides of cholesteryl esters and phosphatidylcholine associated with human HDL.

Acyltransferases↗
PubMed1983

Preparation of 125I-(Tyr 3)- and 125I-(Tyr 11)- neurotensin for radioimmunoassay.

The chloramine-T method for radioiodination of neurotensin for radioimmunoassay was studied. As conventional procedures produced heterogeneous preparations, labelling was performed with a low amount of chloramine-T (1.8 nmol) in the presence of excess of peptide (6 nmol). Purification and complete separation of labelled from unlabelled peptide was obtained by ion-exchange chromatography on SP Sephadex C-25. Four labelled components were identified by isoelectric focusing, enzymatic cleavage and studies of immunoreactivity. The two components representing monoiodinated preparations labelled at Tyr 3 or Tyr 11 could be isolated. Depending on the binding site of the particular antiserum the appropriate tracer could be selected for use in the radioimmunoassay. The specific radioactivities were high (2303 (2137-2407) microCi/nmol and 1927 (1608-2307) microCi/nmol (median and range] and the stability of the label and the reproducibility of the procedure was good.

Iodine Radioisotopes↗
PubMed2006

Comparison of UV C light and chemicals for disinfection of surfaces in hospital isolation units.

OBJECTIVE: To determine the bactericidal effect on surfaces of ceiling- and wall-mounted UV C (UVC) light (wavelength, 254 nm) in isolation units, compared with standard hospital environmental cleaning and chemical disinfection during final disinfection after patients are treated for infections. DESIGN: Microbial samples were obtained from surfaces in isolation units (patient room, anteroom, and bathroom) before and after irradiation with UVC, chloramine disinfection, and standard hospital environmental cleaning. Samples were tested using standard contact plates. SETTING: Four identical, negative air-pressure isolation units (patient room, anteroom, and bathroom) with a defined number of ceiling- and wall-mounted UVC light units. The UVC distribution was monitored in one isolation unit after irradiation for approximately 40 minutes, corresponding to doses ranging from 160 J/m2 in a shadowed area to 19,230 J/m2 at the mostly highly exposed site (which is high enough to inactivate most bacterial organisms, including spores). RESULTS: UVC disinfection significantly reduced the number of bacteria on surfaces directly or indirectly exposed to UVC to a very low number, as did 5% chloramine disinfection alone (P<.001 for both). Completely shadowed areas in the isolation unit (eg, the bed rail, lockers, and mattresses) still required disinfection by chemicals. CONCLUSION: Disinfection with UVC light may significantly reduce environmental bacterial contamination and thereby protect the next patient housed in an isolation room. UVC disinfection may not be used alone but is a good addition to chemical disinfection.

Bacteria↗
PubMed2002

Role of reactive oxygen and nitrogen species in acute respiratory distress syndrome.

Reactive oxygen species are reactive, partially reduced derivatives of molecular oxygen (O 2 ). Important reactive oxygen species in biologic systems include superoxide radical anion, hydrogen peroxide, and hydroxyl radical. Closely related species include the hypohalous acids, particularly hypochlorous acid; chloramine and substituted chloramines; and singlet oxygen. Reactive nitrogen species are derived from the simple diatomic gas, nitric oxide. Peroxynitrite and its protonated form, peroxynitrous acid, are the most significant reactive nitrogen species in biologic systems. A variety of enzymatic and nonenzymatic processes can generate reactive oxygen species and reactive nitrogen species in mammalian cells. An extensive body of experimental evidence from studies using animal models supports the view that reactive oxygen species and reactive nitrogen species are important in the pathogenesis of acute respiratory distress syndrome. This view is further supported by data from clinical studies that correlate biochemical evidence of reactive oxygen species-mediated or reactive nitrogen species-mediated stress with the development of acute respiratory distress syndrome. Despite these data, pharmacologic strategies directed at minimizing reactive oxygen species-mediated or reactive nitrogen species-mediated damage have yet to be successfully introduced into clinical practice. The most extensively studied compound in this regard is N -acetylcysteine; unfortunately, clinical trials with this compound in patients with acute respiratory distress syndrome have yielded disappointing results.

Animals↗
PubMed2004

Phylogenetic diversity of drinking water bacteria in a distribution system simulator.

AIMS: To characterize the composition of microbial populations in a distribution system simulator (DSS) by direct sequence analysis of 16S rDNA clone libraries. METHODS AND RESULTS: Bacterial populations were examined in chlorinated distribution water and chloraminated DSS feed and discharge water. Bacterial strains isolated from DSS discharge water on R2A medium were identified using 16S rDNA sequence analysis. The majority of the bacteria identified were alpha-proteobacteria, ranging from approx. 34% in the DSS discharge water to 94% of the DSS isolates. Species richness estimators Chao1 and ACE (abundance-based coverage estimators) indicated that the chlorinated distribution water sample was representative of the total population diversity, while the chloraminated DSS feed water sample was dominated by Hyphomicrobium sp. sequences. The DSS discharge water contained the greatest diversity of alpha-, beta-, gamma-proteobacteria, with 36% of the sequences being operational taxonomic units (OTUs, sequences with >97.0% homology). CONCLUSIONS: This work demonstrated the dominance of alpha-proteobacteria in distribution system water under two different disinfectant residuals. The shift from chlorine to monochloramine residual may have played a role in bacterial population dynamics. SIGNIFICANCE AND IMPACT OF THE STUDY: Accurate identification of bacteria present in treated drinking water is needed in order to better determine the risk of regrowth of potentially pathogenic organisms within distribution systems.

Base Sequence↗
PubMed1992

[Relationship between hand-washing activity of disinfectants and in vitro bactericidal activity in the presence of peptone].

A study was made on the relation between in vitro bactericidal activity against Staphylococcus epidermidis which is the main bacterial flora of skin and the disinfecting activity of hand-washing with povidone-iodine, sodium hydrochloride, chloramin-T, chlorhexidine gluconate and benzalkonium-chloride. Although the bactericidal activity of povidone-iodine and sodium hydrochloride was significantly high as compared with those of the other three disinfectants, both povidone-iodine and sodium hydrochloride showed no or a little hand-washing effects. In vitro the bactericidal activity of both povidone-iodine and sodium chloride were significantly retarded by the addition of peptone in the reaction mixture. On the other hand, chloramin-T, chlorhexidine gluconate and benzalkonium chloride showed a high disinfecting activity in hand washing in spite of low in vitro bactericidal activity. Moreover, the bactericidal activity of these three disinfectants were not suppressed by the addition of peptone in the reaction mixture. These results strongly suggested that hand washing effect of disinfectant is affected by the protein on the hand and that hand-washing activity of disinfectant should be determined by in vitro bactericidal activity in the presence of peptone.

Chlorhexidine↗
PubMed1977

Proteins of hepatitis B surface antigen.

Purified 22-nm forms of hepatitis B surface antigen (Hbsag) representing the three major antigenic subtypes (adw, ayw, and adr) were analyzed for their constituent polypeptides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. No consistent difference in either the number or relative distributions of the polypeptides was observed for the various subtypes. Seven polypeptides were designated as P-1 through P-7 in order of their decreasing mobilities. By comparison with protein standards, their molecular weights were estimated as 23, 29.5, 36, 41.5, 53.5, 72, and 97 thousand. The P-1 and P-2 components represented the major polypeptides; P-2 and P-5 might by glycoproteins, based on their reaction with periodic acid-Shiff reagent. Each polypeptide contains cysteine residues. HBSAg was radiolabeled with 3H or 14C by reductive methylation or iodinated with 125I by the chloramine-T or lactoperoxidase procedures. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of labeled HBSAg yielded patterns identical to those obtained with protein stain. Comparison of HBSAg labeled by the chloramine-T and lactoperoxide procedures indicated that there was no distinction between internal or external components within the 22-nm structure.

Cysteine↗