Neutrophils degrade subendothelial matrices in the presence of alpha-1-proteinase inhibitor. Cooperative use of lysosomal proteinases and oxygen metabolites

Triggered neutrophils rapidly degraded labeled matrices secreted by cultured, venous endothelial cells via a process dependent on elastase but not oxygen metabolites. In the presence of high concentrations of alpha-1-proteinase inhibitor, the ability of the stimulated neutrophil to solubilize the matrix was impaired. However, at lower concentrations of alpha-1-proteinase inhibitor the neutrophil could enhance the degradative potential of its released elastase by a H2O2-dependent process. Coincident with this increase in matrix damage, the stimulated neutrophil destroyed the elastase inhibitory activity of the alpha-1-proteinase inhibitor via a catalase-inhibitable process. The ability of the triggered neutrophil to solubilize the matrix in the presence of alpha-1-proteinase inhibitor was unaffected by superoxide dismutase or hydroxyl radical scavengers but was markedly impaired by catalase, azide, or hypochlorous acid scavengers. We conclude that neutrophils can cooperatively use an oxidant with characteristics similar, if not identical, to hypochlorous acid and the lysosomal proteinase elastase to negate the protective effects of alpha-1-proteinase inhibitor in order to attack the subendothelial matrix.

Evaluation of disinfectants in the domestic environment under 'in use' conditions

An 'in use' test was developed to investigate effectiveness of disinfectant application and of detergent of hot water cleaning at kitchen, bathroom and toilet sites in the domestic environment. Detergent and hot water cleaning produced no observable reduction in microbial contamination. Single and daily application tests demonstrated that hypochlorite and phenolic disinfectants can be used to produce substantial reductions in bacterial contamination in the home. Results indicate that maximum protection afforded by disinfection is relatively brief; 3-6 h after disinfection, contamination levels were only marginally less than those observed at pretreatment. Some suggestions are made for improvements in home hygiene.

Hypochlorite effects on spores and spore forms of Bacillus subtilis and on a spore lytic enzyme

Spores of Bacillus subtilis NCTC 10073 were converted to ion-exchange (Ca, H) forms and coat-defective (urea-mercaptoethanol, urea-dithiothreitol-sodium lauryl sulphate) forms. The resistance of these to sodium hypochlorite (1000 parts/10(6) free chlorine) was compared and related to uptake from which the assumed monolayer capacities were calculated. Hypochlorite effects on spore protoplasts and cortical fragments were also examined in relation to DPA and hexosamine release. A spore lytic enzyme was extracted and examined in respect of hypochlorite activity. The results are discussed in terms of the mechanism and site of action of hypochlorite on the bacterial spore.

A wild and an attenuated strain of Francisella tularensis differ in susceptibility to hypochlorous acid: a possible explanation of their different handling by polymorphonuclear leukocytes

We have previously reported that a wild strain of Francisella tularensis is much less efficiently killed by human polymorphonuclear leukocytes than is an attenuated strain. In the present study, the killing of the attenuated strain was found to be strictly oxygen dependent. The wild and the attenuated strains both induced a respiratory burst in the leukocytes. The difference between the strains in susceptibility to agents produced at the burst could be explained by a difference in susceptibility to hypochlorous acid.

Inactivation of Naegleria gruberi cysts by chlorinated cyanurates

The resistance of Naegleria gruberi cysts to chlorine in the presence of cyanuric acid was compared at pH 5 and 7. An amperometric membrane electrode was used to measure HOCl concentrations independently of the chlorinated cyanurate species, thus permitting an analysis of the role of free chlorine versus chlorinated cyanurates in cyst inactivation. In the presence of cyanuric acid, the products of the HOCl residual and the contact time required for 99% cyst inactivation were 8.5 mg . min/liter and 13.9 mg . min/liter at pH 5 and 7, respectively. The Watson's Law coefficients of dilution (n) were 1.3 and 1.6 at pH 5 and 7, respectively. The results strongly suggest that HOCl is the predominant cysticide with no measurable cysticidal effect of the chlorinated cyanurate species.

Disinfection studies with two strains of mouse-passaged scrapie agent. Guidelines for Creutzfeldt-Jakob and related agents

A variety of disinfection procedures were tested on two strains of scrapie agent, treated either as brain macerates (autoclaving) or as 10% homogenates (chemical treatments). It is suggested that a given treatment should produce a titre loss, of both strains of scrapie, of at least 10(4) units before it be regarded as useful for the disinfection of the agents of scrapie and Creutzfeldt-Jakob disease (CJD). By this criterion, treatment at room temperature with about 4% Hycolin (0.6% chlorinated phenols), 0.2% permanganate, 5% Tego (dodecyl-di(aminoethyl)-glycine) or 5% sodium dodecyl sulphate (SDS) are unsuitable. However, data indicate that SDS might be used to reduce the heat stability of scrapie agent. Hypochlorite (Sterilex) was the only satisfactory chemical reagent tested. At least 10(4)-10(5) units of infectivity were lost by treatment with hypochlorite containing 1,000 ppm available chlorine after a 4-16 h exposure, or containing 10,000 ppm available chlorine after a half-hour exposure. The latter result points to the use of concentrated hypochlorite (about 2% available chlorine; approximately 20% Sterilex) to decontaminate surfaces. We suggest that the cleaning action of SDS, or other strong detergents, might also help to decontaminate surfaces, but studies on this are needed. Autoclaving at 126 degrees C for 1-2 h reduced titres by 10(3)-10(7) units, depending on the strain of agent. However, total disinfection of brain containing high titres of infectivity was approached only at 136 degrees C when titre losses of about 10(6) units were obtained by autoclaving for 4-32 min. Further studies are needed before we can make simple, general recommendations for the disinfection of CJD agents in hospital practice.

Regeneration of hemofiltrate by anodic oxidation of urea

Urea can be oxidized electrochemically in a chloride solution to carbon dioxide, water, and nitrogen. The microkinetics of this hypochlorite-mediated urea oxidation are elucidated. Based on this kinetic information, the optimal conditions and construction principles for an electrochemical reactor are deduced. The construction of a cheap, disposable oxidation cell and necessary auxiliary equipment are described. In vitro data are reported for urea removal. A 36-L volume was used to simulate a 60-kg patient; 18 L was recirculated through a 0.12-m2 oxidation cell. Within 3 h, 35 g urea could be removed from the system. The technical and economic possibilities as well as safety requirements for hemofiltrate regeneration to a reinfusable substitution solution by anodic urea oxidation are discussed critically. Although the process does not appear to be economically practical for discontinuous hemofiltration, it might be desirable for continuous (24 h/day) treatment.

Proposed mechanism for sensitization by hypochlorite treatment of Clostridium botulinum spores

Hypochlorite-treated Clostridium botulinum 12885A spores, but not buffer-treated spores, could be germinated with lysozyme, indicating that their coats are made permeable to lysozyme by hypochlorite treatment so that the cortex is accessible. Hypochlorite-treated spores and spores extracted with 8 M urea-2-mercaptoethanol (pH 3.0) were sensitive to certain components of recovery media, but spores sensitized to lysozyme by other treatments were not. These data indicate that hypochlorite does more than increase coat permeability to lysozyme. Scanning electron microscopy revealed a more open-appearing surface of hypochlorite-treated spores, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that a greater amount of protein was removed from hypochlorite-treated and other lysozyme-sensitized spores than from buffer-treated spores. The data suggest that spore coat proteins may be removed by hypochlorite treatment, and this may be responsible for the sensitivity of spores and for their observed ability to germinate in lysozyme.

Hypochlorite injury of Clostridium botulinum spores alters germination responses

Clostridium botulinum spores were sublethally damaged by exposure to 12 or 28 micrograms of available chlorine per ml for 2 min at 25 degrees C and pH 7.0. The damaging dose was 2.7 x 10(-6) to 3.1 x 10(-6) micrograms of available chlorine per spore. Damage was manifested by a consistent 1.6 to 2.4 log difference between the most probable number enumeration of spores (modified peptone colloid medium) and the colony count (modified peptone yeast extract glucose agar); this did not occur with control spores. Damaged spores could be enumerated by the colony count procedure. Germination responses were measured in several defined and nondefined media. Hypochlorite treatment altered the rate and extent of germination in some of the media. Calcium lactate (9 mM) permitted L-alanine (4.5 mM) germination of hypochlorite-treated spores in a medium containing 12 or 55 mM sodium bicarbonate, 0.8 mM sodium thiosulfate, and 100 mM Tris-hydrochloride (pH 7.0) buffer. Tryptose inhibited L-alanine germination of the spores. Treatments with hypochlorite and with hydrogen peroxide (7%, 25 degrees C, 2 min) caused similar enumeration and germination responses, indicating that the effect was due to a general oxidation phenomenon.

Differing L-alanine germination requirements of hypochlorite-treated Clostridium botulinum spores from two crops

Similar populations of hypochlorite-treated spores were enumerated from two crops of Clostridium botulinum 12885A produced by the same procedure; however, germination required different L-alanine concentrations. Lactate permitted the germination of spores from both crops with suboptimal L-alanine concentrations. The data suggest that the spores differ slightly in chemical or structural composition.

Proposed role of lactate in germination of hypochlorite-treated Clostridium botulinum spores

Clostridium botulinum 12885A spores treated with hypochlorite required added DL-calcium lactate for L-alanine germination. Lactate was the active component of calcium lactate. Equimolar concentrations of L-malate, but not of DL-propionate, could replace lactate, suggesting that the alpha-hydroxy acid structure is important. Neither lactate nor malate was an effective germinant for buffer-treated or hypochlorite-treated spores. If the L-alanine concentration was increased 100-fold (to 450 mM), the lactate germination requirement was overcome. The data suggest that the L-alanine germination sites were modified by hypochlorite so that a higher concentration of alanine was required for activity. Lactate appeared to be an activator of modified or non-hypochlorite-modified L-alanine germination sites.

Effects of disinfectants on Campylobacter jejuni

Because of the increasing recognition that Campylobacter jejuni is an important enteric pathogen of humans, we studied the effects of widely used disinfectants on the viability of this organism. At an inoculum size of 10(3) to 10(4) CFU/ml, 1.25 mg of hypochlorite per liter killed three strains within 1 min. At an inoculum size of 10(6) to 10(7) CFU/ml, 5 mg of hypochlorite per liter killed three strains within 15 min. Killing of similar concentrations of C. jejuni and Escherichia coli by hypochlorite was approximately the same. At the high inoculum, 0.15% phenolic compound, 10 mg of iodophor per liter, 1:50,000 quaternary ammonium compound, 70% ethyl alcohol, and 0.125% glutaraldehyde killed all three strains within 1 min. These studies demonstrate that, under the conditions we tested (pH 7.0; 24 to 26 degrees C), the recommended standard concentrations of disinfecting agents are adequate to destroy C. jejuni.

Death, injury and revival of chemically treated Bacillus subtilis spores

The resistance of spores of Bacillus subtilis NCTC 10073 to glutaraldehyde, sodium hypochlorite and povidone-iodine was compared. Revival of treated spores was examined by use of defined germination media and conditions, protein denaturing agents, ultrasonics and heat. Revival, obtained after treatment with each of the three chemical agents, originated under different sets of conditions and was of two recognizably distinct types. The results, including the evidence of electron microscopy, are discussed in terms of chemical-spore reactivity and the implications on their use and suitability as chemical sterilizers.

Effect of chlorine treatment on infectivity of hepatitis A virus

This study examined the effect of chlorine treatment on the infectivity of hepatitis A virus (HAV). Prodromal chimpanzee feces, shown to induce hepatitis in marmosets (Saguinus sp.), was clarified, and the virus was precipitated with 7% polyethylene glycol 6000, harvested, and resuspended. The suspension was layered onto 5 to 30% linear sucrose gradients and centrifuged; the fractions containing HAV were dialyzed, and a 1:500,000 dilution of this preparation induced hepatitis and seroconversion in 2 of 4 marmosets. A 1:50 dilution of this preparation served as inoculum. Untreated inoculum induced overt hepatitis and seroconversion in 100% (5 of 5) of marmosets inoculated intramuscularly. Inoculum treated for various periods (15, 30, or 60 min) with 0.5, 1.0, or 1.5 mg of free residual chlorine per liter induced hepatitis in 14% (2 of 14), 8% (1 of 12), and 10% (1 of 10) of marmosets, respectively, and induced seroconversion in 29, 33, and 10% of the animals. Inoculum treated with 2.0 or 2.5 mg of free residual chlorine per liter was not infectious in marmosets as determined by absence of hepatitis and seroconversion in the 13 animals tested. Thus, treatment levels of 0.5 to 1.5 mg of free residual chlorine per liter inactivated most but not all HAV in the preparation, whereas concentrations of 2.0 and 2.5 mg of free residual chlorine per liter destroyed the infectivity completely. These results suggest that HAV is somewhat more resistant to chlorine than are other enteroviruses.

Myeloperoxidase-mediated oxidation of methionine

The myeloperoxidase-mediated oxidation of methionine was studied using a purified canine myeloperoxidase preparation. The system required the simultaneous presence of myeloperoxidase, H2O2, and a halide anion. When 0.1 mM H2O2 was used, the system has a Ph optimum of approximately pH 5-5.5. Bromide and iodide were much more effective than chloride in the myeloperoxidase-mediated oxidation of methionine. Horseradish peroxidase was unable to oxidize methionine whether chloride or iodide was used. In contrast, lactoperoxidase oxidized methionine in the presence of iodide but not chloride. Based on studies of 1) the effect of various inhibitors and singlet oxygen quenchers, as well as 2) the effect of D2O on the oxidation of methionine, by the myeloperoxidase system, OCI-, or methylene blue, it was shown that the oxidation of methionine by the myeloperoxidase system was not mediated by OCI- or 1O2. The mechanism of the myeloperoxidase-mediated oxidation of methionine remains unclear. However, it may be one mechanism by which the myeloperoxidase system damage microorganisms.

Monocyte and granulocyte-mediated tumor cell destruction. A role for the hydrogen peroxide-myeloperoxidase-chloride system

Human monocytes stimulated with phorbol myristate acetate were able to destroy a T lymphoblast cell target (CEM). Stimulated human granulocytes were also capable of mediating CEM cytotoxicity to a comparable degree as the monocyte. CEM destruction was dependent on the pH and the effector cell number. Both monocyte or granulocyte mediated cytotoxicity were inhibited by the addition of catalase, whereas superoxide dismutase had no inhibitory effect. In addition, CEM were protected from cytolysis by the effector cells by the myeloperoxidase inhibitors, azide and cyanide, or by performing the experiment under halide-free conditions. Glucose oxidase, an enzyme system capable of generating hydrogen peroxide, did not mediate CEM cytotoxicity, while the addition of purified myeloperoxidase dramatically enhanced cytolysis. Hypochlorous acid scavengers prevented CEM destruction by the glucose oxidase-myeloperoxidase-chloride system but neither hydroxyl radical nor singlet oxygen scavengers had any protective effect. These hypochlorous acid scavengers were also successful in inhibiting monocyte or granulocyte-mediated CEM cytotoxicity. Based on these observations we propose that human monocytes or granulocytes can utilize the hydrogen peroxide-myeloperoxidase-chloride system to generate hypochlorous acid or species of similar reactivity as a potential mediator of CEM destruction.

The killing of newborn larvae of Trichinella spiralis by eosinophil peroxidase in vitro

Helminth infections in mammals are characterized by a high level of eosinophils in parasitized tissues and blood, and it has recently been suggested that these cells have a direct parasiticidal effect. Newborn larvae of Trichinella spiralis can be killed within 20 min by incubation at room temperature in a cell-free system, including purified human eosinophil peroxidase (EPO), H2O2 and chloride at pH 5.5. Killing was measured by microscopic observation of the larvae. The larvicidal effect was dependent on each component of the EPO/H2O2/Cl- system and could be prevented by using SO4(2-) instead of Cl-. Killing was totally inhibited by sodium azide and catalase, and substantially by bovine serum albumin, a protein that is an effective scavenger for HOCl. Since larvae could also be killed directly by HOCl under these conditions and EPO is able to oxidize Cl- to hypochlorous acid, it is very likely that the larvicidal effect of the EPO system is due to formation of hypochlorous acid. It is proposed that in vivo, the combination of EPO, which is exocytosed onto the surface of the parasite, and H2O2, which is generated by stimulated eosinophils, is responsible for the larvicidal effect.

Mechanism of the bactericidal action of myeloperoxidase: increased permeability of the Escherichia coli cell envelope

The killing of Escherichia coli by isolated human myeloperoxidase plus hydrogen peroxide plus chloride ions was shown to proceed via an increased permeability of the bacterial cell wall. A correlation between the extent of the increased permeability and the number of surviving colony-forming units was found (P less than 0.0005). The same phenomenon was observed with isolated human neutrophils. The permeability increase was shown to be limited, because low-molecular-weight substrate became freely permeant, but the bacteria retained their permeability barrier for protein. Furthermore, disruption of the permeability barrier was followed by destruction of cytoplasmic protein. The active antibacterial agent was probably hypochlorous acid, the direct product of the system, rather than singlet oxygen, the nonenzymic product of hypochlorous acid and hydrogen peroxide. This is concluded from the fact that the myeloperoxidase system could be mimicked by hypochlorous acid, whereas conditions that favor formation of singlet oxygen did not enhance this effect. The relevance of the system for killing of bacteria at neutral pH is discussed.

Biological reactivity of hypochlorous acid: implications for microbicidal mechanisms of leukocyte myeloperoxidase

Oxidative degradation of biological substrates by hypochlorous acid has been examined under reaction conditions similar to those found in active phagosomes. Iron sulfur proteins are bleached extremely rapidly, followed in decreasing order by beta-carotene, nucleotides, porphyrins, and heme proteins. Enzymes containing essential cysteine molecules are inactivated with an effectiveness that roughly parallels the nucleophilic reactivities of their sulfhydryl groups. Other compounds, including glucosamines, quinones, riboflavin, and, except for N-chlorination, phospholipids, are unreactive. Rapid irreversible oxidation of cytochromes, adenine nucleotides, and carotene pigments occurs when bacterial cells are exposed to exogenous hypochlorous acid; with Escherichia coli, titrimetric oxidation of cytochrome was found to coincide with loss of aerobic respiration. The occurrence of these cellular reactions implicates hypochlorous acid as a primary microbicide in myeloperoxidase-containing leukocytes; the reactivity patterns observed are consistent with the view that bactericidal action results primarily from loss of energy-linked respiration due to destruction of cellular electron transport chains and the adenine nucleotide pool.