Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chloramines”

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 847 records · Page 47Linked to original sources
PubMed1984

Preparation of 125I-protein A usable for up to 10 months in immunoassays.

Chloramine-T iodination of protein A from Staphylococcus aureus and gel electrophoretic purification of the iodination mixture results in a stable tracer of high specific and functional activity. Following repeated gel electrophoresis of the tracer only a single component was observed. The specific activity of the 125I-protein A was between 30 and 55 muCi/micrograms. The binding of 125I-protein A to rabbit immunoglobulin exceeded 90% and the tracer competed effectively with unlabelled protein A in binding to cells incubated with sera containing surface antibodies. Storage of the tracer for up to 46 weeks resulted in a moderate decrease in maximal binding to immunoglobulin (from 91% to 64%), in TCA precipitable radioactivity (from 97% to 80%) and an approx. 30% decrease in the ability to detect cell bound immunoglobulin. It is concluded that gel electrophoretic purification of 125I-protein A produces a tracer with a very long shelf life.

Chloramines↗
PubMed1985

A new method of iodinating ovalbumin, a protein which lacks accessible tyrosine groups, by conjugation to a highly fluorescent coumarin active ester, CASE.

A simple and efficient method is described to overcome the difficulty in radiolabelling ovalbumin and is applicable to any protein. Coumarin-3-acetic acid-N-OH-succinimidyl ester (CASE) binds directly to ovalbumin in aqueous solution to form covalent bonds with free amino groups. The attached CASE residues can then be radiolabelled by the chloramine-T method. This offers an inexpensive alternative to the Bolton and Hunter reagent with the advantage that CASE is fluorescent. This property, apart from direct use as a fluorescent tag, allows one to monitor the conjugate before radiolabelling. Below a conjugation ratio of 9:1, CASE-ovalbumin retained full antigenic identity with ovalbumin.

Animals↗
PubMed1985

Effect of antimicrobial mouth rinses on the incidence of localized alveolitis and infection following mandibular third molar oral surgery.

Mandibular third molars were removed from 400 patients who were divided into four different preoperative and postoperative rinsing groups using either normal saline solution, chloramine-T, povidone iodine, or sodium bicarbonate. The overall incidence of localized alveolitis and infection was 4.5% and 1.7%, respectfully. The incidence of the two postoperative problems proved not to be statistically significant when the four groups were compared with each other. There seems to be no apparent advantage to the preoperative and postoperative use of an antimicrobial mouth rinse in place of normal saline solution in reducing the incidence of either localized alveolitis or postoperative infections.

Adolescent↗
PubMed1992

Preparation of the N-(4'-hydroxy-[3'-125I]iodophenethyl)-6-(4-O-diethylstilbestryl)hexanam ide for diethylstilbestrol radioimmunoassays.

The synthesis of a radioiodinated diethylstilbestrol (DES) derivative is described. This derivative was prepared by coupling the previously synthesized active ester of 6-(4-O-diethylstilbestryl)hexanoic acid with mono-[125I]iodotyramine in dry tetrahydrofuran (20 to 22 C, 16 hours). The mono-[125I]iodotyramine was prepared using a chloramine-T method and purified by paper electrophoresis. The final product, N-(4'-hydroxy-[3'-125I]iodophenethyl)-6-(4-O- diethylstilbestryl)hexanamide, was separated by thin-layer chromatography (cyclohexane/ethanol/NH4OH 2.5 N/acetone; 40:50:5:20, v/v/v/v); it was stable for 2 months in ethanol at 4 C and had a specific activity higher than 540 Ci/mmol. The [125I]DES amide synthesized was found to retain the immunoreactivity of DES, since it competed with [3H]DES or DES in an in vitro radioimmunoassay system for the binding sites of a rabbit anti-DES antibody; thus, it seems to be capable of replacing the tritiated tracer used so far in DES radioimmunoassays.

Binding, Competitive↗
PubMed1993

7 alpha-Methyl-17 alpha-(E-2'-[125I]iodovinyl)-19-nortestosterone: a new radioligand for the detection of androgen receptor.

We have synthesized two gamma-emitting, 125I-labeled steroids, E- and Z-7 alpha-methyl-17 alpha-(2'-[125I]iodovinyl)-19-nortestosterone [125I](E- and Z-MIVNT) for specific labeling of androgen receptors. [125I]E- and [125I]Z-MIVNT were synthesized stereospecifically from E- and Z-7 alpha-methyl-17 alpha-(2'-tri-n-butylstannyl-vinyl)-19-nortestosterone. The tin adducts were prepared by addition of tri-n-butyltin hydride to 7 alpha-methyl-17 alpha-ethynyl-19-nortestosterone, and after purification they were converted in high yield to the [125I]MIVNT isomers by reaction with 125I (generated in situ by oxidation of [125I]iodide with chloramine T). The 125I-labeled products were purified by high-performance liquid chromatography, and their mass determined with an ultraviolet detector (specific activity of both, approximately 2,200 Ci/mmol). In rat prostate cytosol, [125I]E-MIVNT bound with high affinity to a single class of binding sites. Nonspecific binding in the presence of 5 alpha-dihydrotestosterone was relatively low, and compared favorably with that obtained in parallel studies with [3H]methyltrienolone (R1881). The E-isomer bound prostate cytosol with at least twice the affinity of the Z-isomer; therefore, the interaction of the E-isomer with the androgen receptor as well as other steroid receptors was studied in greater detail. Complexes of the androgen receptor with [125I]E-MIVNT as well as [3H]R1881 dissociate very slowly at 4C (kdiss for both = 0.04 h-1). Displacement studies showed that the interaction of [125I]E-MIVNT with the androgen receptor is highly specific. Competition studies showed that unlabeled E-MIVNT binds poorly to other steroid receptors in rat tissue cytosols. These binding properties make [125I]E-MIVNT a promising ligand for study of the androgen receptor, and [123I]E-MIVNT a potential imaging agent for the detection of androgen-dependent tumors, such as prostate cancer.

Animals↗
PubMed1985

Alternative methods for chlorination.

Existing disinfectants are oxidative agents which all present negative effects on subsequent treatment processes. None of them has decisive advantages over chlorine, although chlorine-dioxide and chloramines might at times be preferable. Optimum treatment practices will improve the removal of organic precursors before final disinfection which could then consist in a light chlorine addition. A philosophy of radical change in water treatment technology encompassing physical treatment without chemicals such as membrane filtration, solid disinfectants is presented.

Animals↗
PubMed1988

Determination of plasminogen activator inhibitor (PAI) capacity of human plasma in presence of oxidants: a novel principle.

A new functional assay of PAI-activity in human plasma is described. Hitherto known assays for fast acting PAI have some disadvantages: predilution and/or acidification steps of the sample to afford the required inactivation of alpha-2-antiplasmin (A2-PI). This approach in contrast implicates test performance in presence of chloramine T (CT), an oxidant that destroys plasma antiplasmin activity without impairing significantly the activity of urokinase (u-PA) or plasmin. The following reaction conditions were found optimal: 50 microliter of undiluted plasma, anticoagulated with citrate or EDTA, were first incubated with 1 IU u-PA in a Tris-buffer, pH 8.4 and then with Glu-plasminogen (0.85 mumol/l final), CT (2.5 mmol/l final), tranexamic acid (0.9 mmol/l final) for 5 min. at 37 degrees C. After addition of 0.3 mmol/l of the chromogenic plasmin substrate H-D-Nva-CHA-Lys-pNA (pNA = para nitroanilide) and of NaCl (250 mmol/l final) a linear kinetic with delta A405/t in the range of 0.2/min for normal plasma was recorded. In an endpoint version of the test the chromogenic substrate can be added together with plasminogen resulting an A/t2-kinetic. Dilution studies showed a linear calibration curve from 0 to 14 arbitrary u-PA inhibiting units (AU)/ml plasma. By means of PAI-standard plasmas PAI-capacity values of 20 healthy volunteers (10 males/10 females) (x = 26 years, sigma = 4.2) were determined. They ranged from 0.4 - 6.9 (x = 1.3, sigma = 0.9) AU/ml plasma. Plasma samples containing more than 14 AU/ml were prediluted with PAI-deficient plasma. Intra- and inter-assay coefficients of variation (CV) were determined to be 1.3 +/- 0.6 and 4.3 +/- 0.5%, respectively. The values of this assay correlate well with those obtained by acidification of the samples. However, the possibility of measuring plasma PAI (and PA) activities by means of a simple and direct approach can be considered as an important progress with regard to routine hospital practice. The presented oxidative inactivation of A2-PI mimics the leukocyte attack phase, suggesting that activated leukocytes create a microenvironment of uncontrolled plasmin activity.

Adult↗
PubMed1989

A direct approach in fibrinolysis diagnostic: mimicry of the leukocyte by attack by oxidants.

Activated leukocytes release large amounts of chloramine like oxidizing agents (see Weiss et al. Science 222, 625-628, 1983) which inactivate protease inhibitors, creating microenvironments of uncontrolled protease activity. The biological result is an increased proteo- and fibrino- lysis. Functional determination of tissue type (t-PA) or urinary type (u-PA) plasminogen activator, the key enzymes of fibrinolysis, is of clinical importance. Assay techniques have been developed but are troublesome due to predilution, acidification or separation steps in order to eliminate the PA and plasmin inhibiting effect of plasmatic inhibitors of anti-PA and of anti-plasmin type, respectively. In this study, evidence is presented that performance of fibrinolytic assays using N-chloroamines offers great advantage: plasmatic plasminogen activator activity both of urinary and of tissue type can be measured precisely within minutes in untreated (direct) plasma samples. Therefore, mimicking the oxidative inflammatory response, for the first time it gets feasible to analyze blood factors involved in the physiological course of fibrinolysis by means of a functional, sensitive, and rapid assay procedure.

Chloramines↗
PubMed1992

The inhibition of thrombin and chymotrypsin by heparin-cofactor II.

Heparin cofactor II (HC II) is known as a bifunctional inhibitor inactivating trypsin- and chymotrypsin type proteases. Its inhibitory activity increases in the presence of heparin, dermatan sulfate and chondroitin E. In the present study the inhibitory activity of HC II was investigated as function of various dermatan sulfate fractions and its stability was tested against oxidation reagents similar to thus secreted by activated leucocytes. High affinity dermatan sulfate (DS) increased the antithrombin inhibition activity of HC II about 1000-fold in contrast to about 100-fold in the case of low affinity DS. Oxidation of HC II carbohydrate side chains with sodium periodate showed less inactivation effects than oxidation by chloramine T or ammonium peroxodisulfate.

Chloramines↗
PubMed1992

Activation of the fifth component of human complement, C5, without cleavage, by methionine oxidizing agents.

Purified human C5 was incubated with chloramine T (Cl-T) or N-chloro-succinimide (N-Cl-S) in barbital buffer, pH 7.2. The treatment led to C5 activation: Cl-T- and N-Cl-S-treated C5 acquired a binding site for C6; upon incubation with C6 and subsequent addition of C7, C8 and C9 a membrane attack complex formed which lysed non-sensitized guinea pig red cells (reactive lysis). While the physiological activation of C5 follows its specific cleavage, the resulting fragment C5b representing the activated C5 and expressing the C6 binding site, the treatment with the mentioned chemicals does not lead to fragmentation of the C5 protein. So, functionally, the product of the chemical treatment is C5b-like, but chemically, it comprises the whole protein; no C5a is released. Cl-T and N-Cl-S are known to more or less selectively oxidize methionine residues in proteins, dependent on the conditions. Other sensitive amino acid residues are tryptophan and cysteine. Conditions were chosen for treatment of C5 with Cl-T which exclude attack on tryptophan, and we have ensured that human C5 does not contain free cysteine residues. Further, oxidation of about 60% of the methionine residues of C5 by Cl-T was demonstrated by amino acid analysis. So, all evidence points to methionine residue(s) as the site of attack of Cl-T and probably also of N-Cl-S. The oxidation product of methionine, its sulphoxide, may cause a change in structural conformation of C5 which involves expression of the C6 binding site. Earlier it was found that oxidation of C5 by hydroxyl radicals leads to its activation without cleavage. Since the properties of this C5b-like product resemble those of the product of treatment with Cl-T and N-Cl-S, it is suggested that the formerly found activation of human C5 by hydroxyl radicals is also mediated by oxidation of methionine residue(s) in the C5 protein.

Chloramines↗
PubMed1983

A microradioiodination method for detection of nanogram amounts of proteins resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

A procedure is described for the rapid analysis of nanogram quantities of protein resolved by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). Proteins are first radioiodinated by the chloramine T method, acid precipitated after addition of a visible marker protein and collected on a nitrocellulose filter. The region of the filter containing protein is excised and the proteins are then extracted from the filter into electrophoresis sample buffer.

Autoradiography↗
PubMed1981

Schistosoma mansoni: modulation of schistosomular lipid composition by serum.

Human serum and foetal calf serum have been compared in terms of their ability to modify the biochemical and immunological properties of the schistosomular surface. Artificially transformed schistosomula were incubated in the presence of serum for 24 h and then radioiodinated using the chloramine T method. With this method only lipids are labelled. Foetal calf serum produces a net loss of lipids from the schistosomula, particularly of mono- and diglycerides. Human serum however, promotes not only a loss of mono- and diglycerides, but also a substantial uptake of cholesterol and triglycerides. Schistosomula recovered from the lungs of mice could also be labelled and contained besides triglycerides, an increased amount of cholesterol esters. The modulation of surface lipids in worms cultured with human serum correlates with the observation that such schistosomula develop significantly greater protection against eosinophil-mediated cytotoxicity in vitro than do individuals incubated with foetal calf serum. On the other hand, schistosomula cultured in the presence of either human serum or foetal calf serum develop the same degree of protection against complement-dependent lethal antibody; this result indicates that resistance against complement-mediated damage may be independent of the uptake of cholesterol and/or triglycerides, and might involve only limited alterations in the surface configuration of the schistosomulum.

Animals↗
PubMed1986

Iodinated derivatives of the vasoactive intestinal polypeptide (VIP) are agonists at the cat pancreas and the rat submandibular salivary gland.

Porcine VIP was iodinated by the chloramine-T method. The reaction products, which were separated by high pressure liquid chromatography, included residual native VIP, oxidized VIP and at least two iodinated VIP species. The iodo-VIP derivatives were recognized by antibodies raised against VIP and by VIP receptors. Furthermore, they appear to be approximately equipotent agonists to VIP in activating the adenylate cyclase in membranes from the rat submandibular salivary gland and in the stimulation of pancreatic secretion in vivo.

Adenylyl Cyclases↗
PubMed1994

Identification of a PAI-1 binding site in vitronectin.

Active PAI-1 (plasminogen activator inhibitor 1) is bound to vitronectin in plasma and in the extracellular matrix. In this study we aimed at identifying the PAI-1 binding site in vitronectin, which at present is a matter of dispute. Vitronectin was cleaved with trypsin and the fragments were tested for inhibitory effect on the PAI-1/vitronectin interaction using vitronectin-coated microtiter plates. Intact vitronectin and the tryptic digest of vitronectin both caused a 50% reduction in PAI-1 binding at a concentration of about 2 nmol/I. Gel-filtration on Sephadex G-50 superfine of the tryptic peptides resulted in one main peak of inhibitory activity. The elution volume, Kav, was 0.55 indicating (a) medium-size peptide(s). The peptide was further purified by reverse-phase HPLC. Structural analysis revealed that it constituted the 45 NH2-terminal amino-acid residues in vitronectin. The NH2-terminal vitronectin peptide caused a 50% decrease in PAI-1 binding to the vitronectin-coated microtiter plates at a concentration of about 13 nmol/l. Thus, the peptide is a little less effective in this respect than intact vitronectin. Reduced and S-carboxymethylated peptide had no effect on the interaction. The NH2-terminal vitronectin fragment increased the stability of active PAI-1 by about 60%, which is a little less than with intact vitronectin. The peptide also prevented PAI-1 from oxidation with chloramine T. The half-life was prolonged about 4-fold as compared to about 30-fold with intact vitronectin.

Amino Acid Sequence↗
PubMed1995

A radioactive assay for the degradation of neuropeptide Y.

Neuropeptide Y (NPY) is one of the most abundant neuropeptides in the mammalian central nervous system. Like other neuropeptides, NPY is inactivated by specialized neuropeptidases. To trace the degradation of NPY, an assay was established using biotinylated NPY. Biotinyl-NPY was radiolabeled with Na125l by the chloramine-T method and bound to a streptavidin-agarose matrix. The amount of radiolabeling was analyzed by reverse-phase HPLC. The assay was carried out with five peptidases and inhibitors to demonstrate different specific activity. Measurable amounts of radioactivity were released by treatment with endopeptidase-24.18, plasmin, and trypsin, whereas dipeptidylpeptidase IV (DPPIV) and angiotensin-converting enzyme (ACE) showed no activity in this assay. In the case of DPPIV this is due to a resistance of the assay to aminopeptidase attack. The assay is useful to study the specific degradation of NPY particularly by endopeptidases in all kinds of biological samples.

Amino Acid Sequence↗
PubMed1993

Caprine plasma proteinase inhibitors--I. Partial characterization.

1. Using two-dimensional electrophoresis (IEF, pH 3.5-6.0 and PAGE, 11.5% T, pH 7.9) the caprine plasma proteinase inhibitors were classified into six distinct classes, designated PIA, PIB, PIC, PID, PIE and PIF. Differentiation of the six inhibitors was based on electrophoretic criteria, their abilities to inhibit bovine trypsin and chymotrypsin and their crossreactions with antisera to human alpha 1-antitrypsin and alpha 1-antichymotrypsin. 2. Polymorphic variants were identified for five of the protein systems (PIA, PIB, PIC, PID and PIE) and the electrophoretic data indicated that the variants were controlled by allelic genes. PIF proteins were poorly resolved and invariant. 3. Treatment of selected plasmas with neuraminidase demonstrated that the microheterogeneity observed in the PIA, PIB, PIC and PID proteins was attributable to sialic acid additions. 4. The inhibitory activities of all six caprine proteinase inhibitors were unaffected by chemical oxidation with chloramine-T.

Animals↗
PubMed1996

Labeling of insulin with non-radioactive 127I and application to incorporation of radioactive 125I for use in receptor-binding experiments by high-performance liquid chromatography.

Conditions for the labeling of insulin with radioactive iodine isotopes were investigated by means of incorporation of non-radioactive 127I into the peptide. Either the chloramine-T (CT) or lactoperoxidase-hydrogen peroxide (LPO) technique was applied and reversed-phase high-performance liquid chromatography (RP-HPLC) was used for analysis of the reaction products. The LPO method provided the 127I-labeled peptide within 15-30 min, whereas the CT alternative yielded the labeled substrate even within 15 s. However, the latter reaction can only be controlled in a reproducible manner with difficulty and undesired side-reactions became increasingly prominent when the reaction time of 15 s was exceeded for only a few seconds. In another experiment, the LPO technique was applied for radiolabeling insulin with 125I. The product was first purified by size-exclusion chromatography (SEC) and then subjected to RP-HPLC. SEC yielded two peaks. The smaller one, which eluted at a slightly higher Kd value (accounting for about 14% of total radioactivity) predominantly consisted of material eluting at the column's void volume under the conditions of RP-HPLC, whereas the main SEC fraction (accounting for about 86% of total radioactivity) yielded a single peak, as shown by HPLC. The radioactive material attributable to the main SEC fraction revealed the expected receptor-binding properties, as evidenced by displacement experiments with non-radioactive insulin, as well as the action of tetradecanoyl phorbol acetate on the binding characteristics and thus indicating formation of a labeled hormone retaining biological activity.

Binding, Competitive↗
PubMed1993

Cholera toxin: radio-iodination and uptake by the intestine of sucking rats.

1. The chloramine-T procedure was employed to radio-iodinate cholera toxin using Na125I. The procedure was found to be efficient and reproducible. 2. Intragastric injections of both the labelled and the unlabelled toxin produced (a) significant increases in intestinal fluid accumulation as measured by the fluid accumulation ratio; (b) significant increases in cAMP levels; and (c) significant decreases in cAMP-phosphodiesterase activities when compared with the controls suggesting that radio-iodination did not impair the biological activity of the toxin. 3. In vivo uptake studies of the labelled toxin by different parts of the intestine indicated that the uptake by the duodenum and jejunum was high and rapid when compared with the ileum implying that there are more binding sites (or receptor proteins) for cholera toxin in the duodenum and jejunum than in the ileum.

3',5'-Cyclic-AMP Phosphodiesterases↗