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PubMed1986

Oxidation of chloride and thiocyanate by isolated leukocytes.

Peroxidase-catalyzed oxidation of chloride (Cl-) and thiocyanate (SCN-) was studied using neutrophils from human blood and eosinophils and macrophages from rat peritoneal exudates. The aims were to determine whether Cl- or SCN- is preferentially oxidized and whether leukocytes oxidize SCN- to the antimicrobial oxidizing agent hypothiocyanite (OSCN-). Stimulated neutrophils produced H2O2 and secreted myeloperoxidase. Under conditions similar to those in plasma (0.14 M Cl-, 0.02-0.12 mM SCN-), myeloperoxidase catalyzed the oxidation of Cl- to hypochlorous acid (HOCl), which reacted with ammonia and amines to yield chloramines. HOCl and chloramines reacted with SCN- to yield products without oxidizing activity, so that high SCN- blocked accumulation of chloramines in the extracellular medium. Under conditions similar to those in saliva and the surface of the oral mucosa (20 mM Cl-, 0.1-3 mM SCN-), myeloperoxidase catalyzed the oxidation of SCN- to OSCN-, which accumulated in the medium to concentrations of up to 40-70 microM. Sulfonamide compounds increased the yield of stable oxidants to 0.2-0.3 mM by reacting with OSCN- to yield derivatives analogous to chloramines. Stimulated eosinophils produced H2O2 and secreted eosinophil peroxidase, which catalyzed the oxidation of SCN- to OSCN- regardless of Cl- concentration. Stimulated macrophages produced H2O2 but had low peroxidase activity. OSCN- was produced when SCN- was 0.1 mM or higher and myeloperoxidase, eosinophil peroxidase, or lactoperoxidase was added. The results indicate that SCN- rather than Cl- may be the physiologic substrate (electron donor) for eosinophil peroxidase and that OSCN- may contribute to leukocyte antimicrobial activity under conditions that favor oxidation of SCN- rather than Cl-.

Amitrole↗
PubMed1975

[Tests on the bactericidal effectiveness of iodophor A in the halls of a pig-fattening station].

In the halls of the pig fattening house the bactericidal effectiveness of cold water solutions of Czechoslovakia-made Jodofor A and the product of the Ciba-Geigy company Iosan was tested and compared with the effectiveness of Chloramin B used in a water solution at the temperature of 50 to 60 degrees C. The solutions were applied by fine spraying at the rate of 0.5 lt. per 1 m2 of area. After one hour the spray was applied again at the same rate. One hour after the last Jodofor spray and two hours after the last Chloramin B spray, smears were collected from the disinfected surfaces. The examination included the detection of coliform germs, germs of the Micrococcaceae family, and the determination of the total number of germs. On the whole, 384 smears were examined in four separate trials. The application of Jodofor A in 2% concentrations, after mechanical average-quality purification, did not give acceptable results, in comparison with the solution of Cloramin B. Only when solutions of Jodofor A and Iosan were used in 3% concentration after perfect mechanical purification, satisfactory results were obtained (with the exception of plaster and painted wood), in comparison with the Chloramin B solution. Better disinfectibility was found in aluminium sheet, terracotta, concrete, and metal, as distinct from plaster and painted wood. The comparison of Jodofor A with abroad-male Iosan indicates that Jodofor has the same or a better bactericidal effect than Iosan in all indices. Due to its bactericidal effect, Jodofor A is a suitable disinfectant for preventive disinfection of farm animal houses. In order to achieve results corresponding to those provided by 2% solutions of Chloramin B it is necessary to use at least 3% concentration of Jodofor A. Good mechanical purification is a basic prerequisite for its effectiveness.

Animal Husbandry↗
PubMed2000

Initiation of rapid, P53-dependent growth arrest in cultured human skin fibroblasts by reactive chlorine species.

Oxidants produced by neutrophils have been implicated in causing cancers associated with chronic inflammation. Hypochlorous acid is the most potent oxidant produced by these cells in appreciable amounts. It reacts with amines to form chloramines, which are weaker oxidants but are mutagenic. Recently, we showed that sublethal doses of hypochlorous acid increased levels of the transcription factor protein 53 (p53) and the wild-type activating fragment-1/cyclin-dependent kinase inhibitory protein-1 (WAF1/CIP1) in cultured human skin fibroblasts. WAF1/CIP1 is an important intermediate in the pathway leading to growth arrest. We now show that low doses of hypochlorous acid and physiological chloramines lead to an inhibition of both DNA synthesis and division of cultured human skin fibroblasts. Inhibition of DNA synthesis occurred within 1 h of hypochlorous acid treatment, was maintained for 24 h, and returned to a normal rate after 48 h. Cell division was inhibited by hypochlorous acid and chloramines for 48 h and returned to normal 72 h after treatment. Growth arrest was dependent on p53 because it was blocked when cells were transfected with a p53-binding oligonucleotide. We propose that reactive chlorine species will initiate WAF1/CIP1-dependent growth arrest that will counteract their mutagenic effects and minimize the possibility of the malignant transformation of cells surrounding sites of inflammation.

Cell Division↗
PubMed1987

Removal of rapid sensory adaptation from an insect mechanoreceptor neuron by oxidizing agents which affect sodium channel inactivation.

1. The femoral tactile spine of the cockroach is a mechanoreceptor with a single sensory neuron. The response to a step movement is a burst of action potentials which decays to zero in about 1 s. This rapid adaptation is a property of the action potential initiating region of the neuron. 2. The oxidizing agents chloramine-T and N-chlorosuccinimide selectively and irreversibly remove sodium channel inactivation from neurons in several preparations and are believed to act by oxidation of methionine or cysteine residues in the proteins of the sodium channel. 3. Chloramine-T and N-chlorosuccinimide, applied for a controlled time period, eliminated the rapid adaptation of the tactile spine neuron to an electrical depolarization. After treatment it fired tonically in response to a steady current stimulus. Longer applications of the agents eventually raised the threshold for action potential initiation. 4. Threshold behavior in the tactile spine neuron was characterized by measuring strength-duration relationships for stimulation with extracellular current pulses at the action potential initiating region. The two oxidizing agents caused a voltage-dependent modification of the dynamic threshold properties which led to the change from rapidly adapting to tonic behavior. 5. Two stronger oxidizing agents, N-bromoacetamide and N-bromosuccinimide, raised the threshold of the neuron without removing rapid adaptation. These two agents act similarly to chloramine-T and N-chlorosuccinimide on sodium inactivation in other neurons but are believed to oxidize the tryptophan, tyrosine and histidine residues of proteins in addition to cysteine and methionine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of oxidants on proteases of the fibrinolytic system: possible role for methionine residues in the interaction between tissue type plasminogen activator and fibrin.

Evidence has recently been presented that activated macrophages (M phi) express both urinary (u-PA) and tissue type (t-PA) plasminogen activator. Major cell products of M phi and polymorphonuclear neutrophils (PMN) are reactive oxidants of the HOCl/chloramine type. Since PMN and M phi are involved in inflammatory and fibrinolytic processes, we were interested in the interaction of u-PA, t-PA, and plasmin with oxidants of the leukocyte type. The enzymes were treated with chloramine-T, which at pH 8.5 is a selective oxidant for methionine residues. Oxidation by chloramine-T of t-PA abolishes about 40% of both stimulation susceptibility of t-PA by fibrinogen degradation products (FDP) and affinity of t-PA to FDP. However, the plasminogenolytic and amidolytic activity of unstimulated t-PA as well as the plasminogenolytic activity of u-PA and the amidolytic activity of plasmin are not impaired. Identification of the amino acid residues in the t-PA responsible for the interaction with fibrin might be of great importance in order to understand the mechanism of the clot- selectivity of t-PA. The present study gives evidence that fibrin specificity of t-PA partly depends on chloramine oxidizable amino acids, presumably methionine residues. Hence, experimental data on the interaction between t-PA and fibrin, using oxidized and labelled t-PA should be interpreted with caution. It may be suggested that oxidants of the leukocyte type might regulate t-PA activity and selectivity for fibrin.

Chloramines↗
PubMed1993

Effect of storage media on microleakage of five dentin bonding agents.

The objective of this study was to investigate the effect of different storage media on microleakage at the gingival margin of mixed Class V composite restorations. Human molars were either used immediately after extraction (control group) or after a 3-4 wk storage period in 1% chloramine, 70% ethanol, 10% formalin, or 0.1% thymol. Class V cavities with cervical margins in cementum or dentin were prepared and restored with a microfill composite using five different dentin bonding agents. After thermocycling (1440 x from 5 degrees C to 55 degrees C) and basic fuchsin staining, the depth of dye penetration at the gingival margins was determined and ranked on a scale of 0 to 4. Class V restorations in teeth stored in formalin showed significantly less microleakage (mean leakage score, MLS = 1.7) than restorations in freshly extracted teeth (control group; MLS = 3.1). Microleakage scores in teeth stored in chloramine (MLS = 2.7), ethanol (MLS = 3.0) or thymol (MLS = 3.2) were not significantly different from the microleakage scores in the control group. The improvement of in vitro efficacy of dentin bonding agents when using extracted teeth stored in formalin is probably a result of collagen cross-linking by formaldehyde. Since such an alteration of the dentin does not reflect the condition of the substrate in vivo, extracted teeth assigned for in vitro evaluation of dentin bonding agents should not be stored in formalin. In teeth stored in 1% chloramine, the sums of ranks and the rank orders of the dentin bonding agents were comparable to those in freshly extracted teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1990

Inhibition of hypochlorous acid-mediated reactions by desferrioxamine. Implications for the mechanism of cellular injury by neutrophils.

Inhibition of free radical mechanisms by desferrioxamine, an iron chelator, is often thought to be a good indicator of iron-catalyzed hydroxyl radical (OH.) production. The specificity of desferrioxamine is critical for such identification. This study was undertaken to determine whether desferrioxamine could prevent the in vitro cytotoxic reactions of hypochlorous acid (HOCl), a major neutrophil-derived oxidant. Red blood cells were used as a target for HOCl, and cell lysis and haemoglobin oxidation were measured. Desferrioxamine, and its iron-chelated form, ferrioxamine, were shown to prevent both effects of HOCl. However, desferrioxamine was 6 to 8 times more efficient than either ferrioxamine or taurine, another amine which prevents HOCl-mediated cell lysis, in preventing both lysis and Hb oxidation. After reaction with HOCl, ferrioxamine and taurine retained almost all the oxidizing equivalents as long-lived chloramine. However, with desferrioxamine less than half the oxidizing equivalents were recovered as chloramines indicating that sites other than the terminal amine reacted with HOCl. The chloramines formed were able to oxidize molecules in solution, but being hydrophilic they were confined to the extracellular medium and cell lysis did not occur. The results indicate that scavenging of HOCl could be a factor in the inhibition by desferrioxamine of neutrophil-mediated cell lysis in vitro.

Chloramines↗
PubMed1993

Synthesis of the 123I- and 125I-labeled cholinergic nerve marker (-)-5-iodobenzovesamicol.

The highly toxic curraremimetic and cholinergic neuron marker (-)-5-iodobenzovesamicol (IBVM) has been labeled with iodine-125 and iodine-123. [125I]IBVM, suitable for animal distribution and ex vivo autoradiographic studies, was synthesized by solid-state exchange; isolated yields were 65-89% with specific activities in the range of 130-200 Ci/mmol. The synthesis of no-carrier-added (-)-5-[125I]IBVM from the corresponding chiral (-)-5-(tri-n-butyltin) derivative using Na125I was evaluated using the oxidants H2O2, peracetic acid and chloramine-T. Both peracetic acid and chloramine-T gave good yields (70-95%). However, when Na123I was utilized, acceptable yields of [123I]IBVM were obtained only with chloramine-T. Use of the latter oxidant did produce 5-chlorobenzovesamicol which was eliminated during HPLC purification. After optimization of the reaction parameters, [123I]IBVM in batch sizes of 10-27 mCi, is routinely obtained with a specific activity of 30-70,000 Ci/mmol, radiochemical purity (> 97%) and chiral purity (> 98%). Isolated radiochemical yields have averaged 71% (N = 40). Distribution analyses of [125I]IBVM and [123I]IBVM in mice 4 h following intravenous administration show essentially equivalent concentrations of the two tracers in the four brain regions sampled. The exceptionally high specific activity of [123I]IBVM has made possible the evaluation of this radiotracer in humans.

Animals↗
PubMed2001

Monochloramine decay in model and distribution system waters.

Chloramines have long been used to provide a disinfecting residual in distribution systems where it is difficult to maintain a free chlorine residual or where disinfection by-product (DBP) formation is of concern. While chloramines are generally considered less reactive than free chlorine, they are inherently unstable even in the absence of reactive substances. These reactions, often referred to as "auto-decomposition", always occur and hence define the maximum stability of monochloramine in water. The effect of additional reactive material must be measured relative to this basic loss process. A thorough understanding of the auto-decomposition reactions is fundamental to the development of mechanisms that account for reactions with additional substances and to the ultimate formation of DBPs. A kinetic model describing auto-decomposition was recently developed. This model is based on studies of isolated individual reactions and on observations of the reactive ammonia-chlorine system as a whole. The work presented here validates and extends this model for use in waters typical of those encountered in distribution systems and under realistic chloramination conditions. The effect of carbonate and temperature on auto-decomposition is discussed. The influence of bromide and nitrite at representative monochloramine concentrations is also examined, and additional reactions to account for their influence on monochloramine decay are presented to demonstrate the ability of the model to incorporate inorganic demand pathways that occur parallel to auto-decomposition.

Chloramines↗
PubMed2000

Singlet oxygen ((1)O2) inactivates plasmatic free and complexed alpha2-macroglobulin.

alpha2-macroglobulin (alpha2M) is a broad-spectrum proteinase inhibitor and one of the major plasma proteins in humans. Activated phagocytes (especially granulocytes) generate large amounts of oxidants of the HOCI- and chloramine-type that release the mild nonradical, excited (light-emitting) oxidant singlet oxygen ((1)O2). These oxidants have been shown to inactivate several specific serine protease inhibitors in human blood [e.g., alpha1-antitrypsin or alpha2-antiplasmin (plasmin inhibitor)]. The studies reported here demonstrate that nonradical oxidants also inactivate plasmatic alpha2M. The effective dose for 50% inactivation (ED50) of plasmatic alpha2M is similar to that for plasmatic alpha2-antiplasmin. Chloramines are about 1,000-fold more effective than hydrogen peroxide (ED50)=0.75 micromol chloramine T/50 microl plasma). Serine protease-serine protease inhibitor complexes are resistant to oxidants. In contrast, here it is shown that alpha2-macroglobulin, even after binding to serine proteases is sensitive to oxidation, the captured protease is released from the protease/alpha2M complex. This is the first time that oxidative inactivation of a complexed (i.e., bound to a target protease) human protease inhibitor has be shown. The (1)O2 inhibitors methionine, cysteine, cystine, or ascorbate-in contrast to the oxy-radical scavengers mannitol, superoxide dismutase, or catalase-antagonize the chloramine/NaOCl-mediated inactivation of both uncomplexed and complexed alpha2M. Thus, the oxidant involved here is of nonradicalic nature and has reaction characteristics of (1)O2. For the inhibitory function, critical oxidizable methionines or the internal thiol-ester might be targets for (1)O2. Consequently, alpha2M can also be considered a carrier for proteases, since the alpha2M-complexed proteases regain full activity in an oxidative environment. In local areas of inflammation or thrombolysis, activated phagocytes could create microenvironments of uncontrolled protease activity by generation of (1)O2.

Chloramines↗
PubMed1991

Erythrocytes protect alpha-1-proteinase inhibitor from oxidative inactivation induced by chemicals, the myeloperoxidase-H2O2-halide system and stimulated polymorphonuclear leukocytes.

The oxidative inactivation of the alpha-1-proteinase inhibitor (alpha 1PI) is one of the mechanisms responsible for creating the elastase/antielastase imbalance during inflammation in the lower respiratory tract. Chronic supremacy of elastase may cause degradation of elastin fibers leading to the pulmonary emphysema. In this study we have investigated the effect of erythrocytes (RBC, concentrations 0.125 to 1.5%) on the oxidative inactivation of alpha 1PI by the phorbol myristate acetate-stimulated polymorphonuclear leukocytes (PMNL) and PMNL myeloperoxidase-H2O2-halide system. During exposure of alpha 1PI to both systems in the presence of RBC the significant protection (p less than 0.001) of alpha 1PI was found for all RBC concentrations, e.g. at RBC concentration of 1% the elastase inhibitory capacity (EIC) of alpha 1PI increased from 0 to 60 +/- 6 and 88 +/- 9% of the control value (untreated alpha 1PI), n = 5, respectively. The preincubation of RBC with chloramine-T (1 mM), inhibition of RBC catalase or depletion of RBC reduced glutathione alone did not diminish the capacity of RBC to protect alpha 1PI. However, these treatments together completely deprived RBC of their protective properties. Moreover, we have compared the decrease in the EIC of human blood and its plasma after incubation with H2O2 (0.1 mM to 0.1 M) or chloramine-T (1 microM to 1 mM). For the incubation with H2O2 no decrease in blood EIC was found whereas in plasma the loss of EIC was already visible at a H2O2 concentration of 0.1 mM. Also for the incubation with chloramine-T the EIC of blood was more resistant to oxidant damage than EIC of plasma. It is suggested that RBC contaminations present in the phagocyte inflammatory infiltration in the lower airways may protect alpha 1PI from oxidative inactivation and thus indirectly diminish proteolytic lung injury related to inflammation.

Chloramines↗
PubMed1986

Inactivation of plasminogen activator inhibitor by oxidants.

The rapidly acting plasminogen activator inhibitor (PAI) purified from cultured bovine aortic endothelial cells (BAEs) was inactivated during iodination with chloramine T and other oxidizing iodination systems. Inactivation was observed in the absence of iodine, suggesting that the loss of activity resulted from the oxidizing conditions employed. In an attempt to further study the nature of this inactivation, the PAI was treated with chloramine T under conditions that specifically oxidize methionine and cysteine residues. Both PAI inhibitory activity and the ability of the PAI to form complexes with tissue-type PA were decreased in a dose-dependent manner by such treatment. The PAI was more sensitive to oxidative inactivation than urokinase, elastase, and alpha 1-protease inhibitor. Incubation of the chloramine T inactivated PAI with methionine sulfoxide peptide reductase in the presence of dithiothreitol (DTT) restored more than 90% of the PAI activity. The reductase is a DTT-dependent enzyme that specifically converts methionine sulfoxide to methionine. Little activity was restored by either the reductase or DTT alone. These results indicate that the oxidation of at least one critical methionine residue is responsible for the loss of PAI activity upon iodination. In this respect, the BAE PAI resembles alpha 1-protease inhibitor, a well-characterized elastase inhibitor that also is inactivated by oxidants. Both inhibitors are members of the serine protease inhibitor superfamily (Serpins), and both have a methionine residue in their reactive center.

Animals↗
PubMed2006

Modeling the formation of N-nitrosodimethylamine (NDMA) from the reaction of natural organic matter (NOM) with monochloramine.

This paper presents mechanistic studies on the formation of NDMA, a newly identified chloramination disinfection byproduct, from reactions of monochloramine with natural organic matter. A kinetic model was developed to validate proposed reactions and to predict NDMA formation in chloraminated water during the time frame of 1-5 days. This involved incorporating NDMA formation reactions into an established comprehensive model describing the oxidation of humic-type natural organic matter by monochloramine. A rate-limiting step involving the oxidation of NOM is theorized to control the rate of NDMA formation which is assumed to be proportional to the rate of NOM oxidized by monochloramine. The applicability of the model to describe NDMA formation in the presence of three NOM sources over a wide range in water quality (i.e., pH, DOC, and ammonia concentrations) was evaluated. Results show that with accurate measurement of monochloramine demand for a specific supply, NDMA formation could be modeled over an extended range of experimental conditions by considering a single NOM source-specific value of thetaNDMA, a stoichiometric coefficient relating the amount of NDMA produced to the amount of NOM oxidized, and several kinetic parameters describing NOM oxidation. Furthermore, the oxidation of NOM is the rate-limiting step governing NDMA formation. This suggests that NDMA formation over a 1-5 day time frame may be estimated from information on the chloramine or free chlorine demand of the NOM and the source-specific linear relationship between this demand and NDMA formation. Although the proposed model has not yet been validated for shorter time periods that may better characterize the residence time in some distribution systems, the improved understanding of the important reactions governing NDMA formation and the resulting model should benefit the water treatment industry as a tool in developing strategies that minimize NDMA formation.

Ammonia↗
PubMed2003

Characterization of non-covalent oligomers of proteins treated with hypochlorous acid.

Hypochlorous acid (HOCl) is a potent oxidant produced by myeloperoxidase that causes aggregation of many proteins. Treatment of apohaemoglobin and apomyoglobin with HOCl produced a regular series of oligomer bands when the proteins were separated by SDS/PAGE under reducing conditions. Aggregation was detectable at a HOCl/protein molar ratio of 0.5:1 and was maximal at ratios of 10:1-20:1. Dimers formed within 1 min of adding HOCl, and further aggregation occurred over the next 30 min. No convincing evidence for covalent cross-linking was obtained by amino acid analysis, peptide analysis or electrospray ionization-MS of HOCl-modified apomyoglobin. The latter showed an increase in mass consistent with conversion of the two methionine residues into sulphoxides. A 5-fold excess of HOCl generated approximately three chloramines on the apomyoglobin. These underwent slow decay. Protein carbonyls were formed and were almost entirely located only on the polymer bands. Conversion of positively into negatively charged groups on the protein by succinylation caused preformed aggregates to dissociate. Treatment of apomyoglobin with taurine chloramine generated methionine sulphoxides but few protein carbonyls, and did not result in aggregation. We conclude that aggregation was due to strong, non-covalent interactions between protein chains. We propose that formation of protein carbonyls and possibly chloramines, along with methionine oxidation, alters protein folding to expose hydrophobic areas on neighbouring molecules that associate to form dimers and higher-molecular-mass aggregates. This process could lead to the formation of aggregated proteins at sites of myeloperoxidase activity and contribute to inflammatory tissue injury.

Amino Acids↗
PubMed1993

Met-8 of the beta 1-bungarotoxin phospholipase A2 subunit is essential for the phospholipase A2-independent neurotoxic effect.

beta 1-Bungarotoxin consists of a phospholipase A2 subunit and a non-phospholipase A2 subunit. The toxin was oxidized with a 100-fold molar excess of chloramine T with respect to the methionine content of the protein in 0.1 M Tris/HCl at pH 8.5 and at room temperature. Reactivities of the two methionine (Met-6 and Met-8 of the phospholipase A2 subunit), five histidine, 14 tyrosine and one tryptophan residues of one toxin molecule with chloramine T were assessed from the change in intrinsic fluorescence and amino acid composition of the protein. Met-8 and one tyrosine on the phospholipase A2 subunit and less than one histidine were oxidized, while Met-6 remained intact after 30 min of reaction. One histidine and approx. two tyrosine residues were oxidized when both methionine residues were oxidized after 90 min of reaction. The sole tryptophan was oxidized slightly throughout the reaction. The chloramine T oxidation did not destroy the two Ca(2+)-binding domains, though it modified the toxin to become less effective at binding Ca2+. The modified toxin obtained after 30 or 90 min reaction time retained 65% or 40% of the phospholipase A2 activity of the parent toxin, but both were not lethal to mice and showed a very weak ability to induce the indirectly evoked contraction of chick biventer cervicis muscle. It is suggested that Met-8 may play an important role in the phospholipase A2-independent interaction with the nerve terminal membrane during the neurotoxic effect of beta 1-bungarotoxin.

Animals↗
PubMed1986

123I radiolabeling of monoclonal antibodies for in vivo procedures.

When labeled to monoclonal antibodies (MAbs) or their fragments, 123I can be used for imaging or for predicting the treatment potential and radiation dosimetry of 131I labeled to the same molecular species. Because 123I (p,5n) from the Crocker Nuclear Laboratory is in dilute solution, when compared with commercial 125I of labeling grade, we have evaluated labeling parameters using Chloramine-T as the oxidant and derived an optimum set of labeling conditions that provide a 60-80% radiochemical yield of highly immunoreactive antibody. When Lym-1, an IgG-2a murine antibody against human lymphoma, was used, yields of labeled immunoglobulin were decreased by protein or Chloramine-T concentrations less than 0.4 microgram/microliter and 0.8 microgram/microliter, respectively; denaturation of the immunoglobulin occurred when the Chloramine-T concentration was greater than 1.0 microgram/microliter. Optimum labeling occurred at pH 7-8 with deleterious effects when the pH was below 5 or above 10. An optimum method for labeling antibodies with multimillicurie amounts of 123I (less than one iodine atom per 100 antibody molecules) is described. Some of the observations derived from this study are also applicable to the preparation of treatment doses of 131I-labeled antibodies, wherein the amount of antibody can be a restrictive factor.

Antibodies, Monoclonal↗
PubMed1992

Detoxification of endotoxin-contaminated titanium and hydroxyapatite-coated surfaces utilizing various chemotherapeutic and mechanical modalities.

The surgical repair of the ailing implant may be complicated by the surface effects of pathogenic bacteria and their products. This study evaluated the ability of various chemotherapeutic modalities to detoxify endotoxin-contaminated titanium alloy and hydroxyapatite-coated test strips. Grit-blasted titanium alloy and hydroxyapatite-coated test strips were contaminated with purified outer membranes of Escherichia coli labeled with radioactive 14C. The titanium alloy strips were treated with citric acid, stannous fluoride, tetracycline HCl, chlorhexidine gluconate, hydrogen peroxide, chloramine T, sterile water, a plastic sonic scaler tip, and an air-powder abrasive unit. Hydroxyapatite-coated strips were treated with chloramine T, citric acid, or burnished with sterile water on cotton pellets. Residual lipopolysaccharide levels were measured by liquid scintillation spectrometry. The air-powder abrasive unit removed significantly greater amounts of lipopolysaccharide than all other treatment modalities on titanium samples (P < 0.05). A 60-second burnish with sterile water was able to remove significant amounts of lipopolysaccharide when compared with untreated controls (P < 0.05). Citric acid was superior in the removal of lipopolysaccharide from hydroxyapatite-coated surfaces when compared with the controls or chloramine T (P < 0.01). Detoxification of an implant infected surface may be beneficial when surgical repair of the ailing implant is indicated.

Air Pressure↗
PubMed2007

Thrombin generation by hemolysis.

Hemolysis is the fragmentation of erythrocytes into microparticles (Hb-MP). Clinical hemolysis can result in a severe procoagulant state. The influence of Hb-MP on thrombin generation was quantified. Unfrozen citrated normal plasma (five donors) was supplemented with 0 or 1 g/l Hb-MP obtained through erythrocyte destruction by hypotonic lysis, freezing/thawing, or blood oxidation with 1 or 2 mmol/l chloramine-T. Pooled normal plasma was supplemented with 0-10 g/l Hb-MP and with 0-1 IU/ml low-molecular-weight heparin (dalteparin). Samples (50 microl) were tested in the recalcified coagulation activity assay. At 10 min coagulation reaction time the hypotonic lysis of erythrocytes appears to be the most procoagulant condition, followed by twice freezing/thawing, three times freezing/thawing, and once freezing/thawing. Oxidation of whole blood with 1 or 2 mmol/l chloramine-T decreases thrombin generation by about 20 or 50%, respectively. The thrombin generation in 1 mmol/l chloramine-T or 2 mmol/l oxidized plasma decreases by about 70 or 85%, respectively. The 50% inhibitory concentrations of low-molecular-weight heparin against recalcified thrombin generation are 0.01, 0.025, or 0.035 IU/ml for plasma supplemented with 0, 0.1, or 1 g/l Hb-MP, respectively. The recalcified coagulation activity assay allows one to quantify thrombin generation in critical hemolytic samples. It is suggested to find the appropriate pharmacologic dose of low-molecular-weight heparin.

Blood Coagulation↗