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PubMed1980

Regulatory effects of iodide and thiocyanate on tyrosine oxidation catalyzed by thyroid peroxidase.

the effects of iodide, thiocyanate and perchlorate, three anions with the same molecular size, on the oxidation of tyrosine to 3,3'-bityrosine by several peroxidases were evaluated at pH 8.8, i.e. in conditions in which iodide is not oxidized. The following results were obtained: 1. Iodide greatly stimulates the rate of bityrosine formation in the presence of thyroid peroxidase. No effect was seen with horseradish peroxidase or lactoperoxidase. Maximal iodide effects were obtained with about 0.5 mM iodide and Km for iodide was equal to about 0.028 mM. These results suggest that thyroid peroxidase contains a simple class of regulatory binding sites for iodide. 2. SCN- mimics iodide effects; maximal stimulatory effects were seen with about 0.5 mM thiocyanate and Km for SCN- was equal to 0.1 mM. The effects of SCN- and those of iodide were not additive. These results suggest that SCN- binds to the same regulatory site as iodide but with a slightly lower affinity. No effect of SCN- was seen with horseradish peroxidase or lactoperoxidase. 3. ClO-4, another anion with the same molecular size as iodide and SCN-, had neither an effect on the oxidation of tyrosine to bityrosine nor did it prevent the stimulatory effect of iodide on this reaction. Bromide was without effect on the same reaction.

Horseradish Peroxidase↗
PubMed1993

Concentrations of thiocyanate, hypothiocyanite, 'free' and 'total' lysozyme, lactoferrin and secretory IgA in resting and stimulated whole saliva of children aged 12-14 years and the relationship with plaque accumulation and gingivitis.

Resting and stimulated whole saliva was collected from 94 children aged 12-14 years and analyzed for thiocyanate, hypothiocyanite, 'free' and 'total' lysozyme, lactoferrin and secretory IgA. Clinical assessments of the amounts of plaque and gingival inflammation were made, and plaque was collected for determination of dry weight. An inverse relationship was observed between salivary thiocyanate concentrations in both resting and stimulated saliva and the amounts of plaque and gingival inflammation in these subjects (p < 0.05). Lactoferrin concentration in stimulated saliva was directly related to the amounts of plaque and gingivitis (p < 0.05). 'Total' lysozyme concentration in stimulated saliva was directly related to the amount of plaque (p < 0.05), and the 'free' lysozyme concentration in the same saliva was directly related to the amount of gingivitis (p < 0.05). The direct relationship observed between clinical measurements and both lysozyme and lactoferrin concentrations in saliva may have been due to contributions from gingival crevicular fluid. Cluster analysis identified three groups of subjects with different profiles in resting whole saliva, and in particular with different levels of secretory IgA. A statistically significant difference was observed in the quantity of plaque collected from subjects in two of these groups (p < 0.05). These results from cluster analysis using resting whole saliva from children confirmed the findings of a previous study with young adults.

Adolescent↗
PubMed1978

Susceptibility of Escherichia coli to bactericidal action of lactoperoxidase, peroxide, and iodide or thiocyanate.

The bactericidal action that results from lactoperoxidase-catalyzed oxidation of iodide or thiocyanate was studied, using Escherichia coli as the test organism. The susceptibility of intact cells to bactericidal action was compared with that of cells with altered cell envelopes. Exposure to ethylenediaminetetraacetic acid, to lysozyme and ethylenediaminetetraacetic acid, or to osmotic shock were used to alter the cell envelope. Bactericidal action was greatly increased when the cells were exposed to the lactoperoxidase-peroxide-iodide system at low temperatures, low cell density, or after alteration of the cell envelope. When thiocyanate was substituted for iodide, bactericidal activity was observed only at low cell density or after osmotic shock. Low temperature and low cell density lowered the rate of destruction of peroxide by the bacteria. Therefore, competition for peroxide between the bacteria and lactoperoxidase may influence the extent of bactericidal action. Alteration of the cell envelope had only a small effect on the rate of destruction of peroxide. Instead, the increased susceptibility of these altered cells suggested that bactericidal action required permeation of a reagent through the cell envelope. In addition to altering the cell envelope, these procedures partly depleted cells of oxidizable substrates and sulfhydryl components. Adding an oxidizable substrate did not decrease the susceptibility of the altered cells. On the other hand, mild reducing agents such as sulfhydryl compounds did partly reverse bactericidal action when added after exposure of cells to the peroxidase systems. These studies indicate that alteration of the metabolism, structure, or composition of bacterial cells can greatly increase their susceptibility to peroxidase bactericidal action.

Escherichia coli↗
PubMed1976

Effects of nutritional characteristics of Streptococcus agalactiae on inhibition of growth by lactoperoxidase-thiocyanate-hydrogen peroxide in chemically defined culture medium.

Five cultures of Streptococcus agalactiae have an absolute requirement for L-cystine to grow in a chemically defined medium. The L-cystine could be replaced with cysteine, glutathione, or the disulfide form of glutathione. Dithiothreitol could not substitute for the sulfur-containing amino acids of glutathione; hence, the growth requirement appears to be truly nutritional. Growth was maximum with 4 to 5 mug of L-cystine per ml. If the concentration of L-cystine was no greater than 4 to 5 mug/ml, complete growth inhibition could be obtained by the addition of lactoperoxidase, thiocyanate, and H2O2. The growth inhibition, however, was nullified by additions of L-cystine 10-fold or more in excess of the concentration needed for maximum growth. During the aerobic degradation of glucose by cell suspensions, H2O2 accumulation could be shown with cultures 317 and 11-13, the only cultures the growth of which was inhibited without addition of exogenous H2O2. All of the cultures had varying degrees of peroxidase activity. The balance between H2O2 generation and peroxidase activity of the culture evidently determined whether growth could be inhibited with lactoperoxidase and thiocyanate without H2O2 addition. The growth yeilds per 0.5 mol of the disulfide forms (cystine and oxidized glutathione) were 1.5 and 1.9 times greater than that per 1 mol of the sulfhydryl forms (cysteine and glutathione).

Culture Media↗
PubMed1984

Cystine antagonism of the antibacterial action of lactoperoxidase-thiocyanate-hydrogen peroxide on Streptococcus agalactiae.

Cystine reduction in Streptococcus agalactiae, resulting in sulfhydryl formation, may account for antagonism of the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide when cystine is present in excess of the amount needed for maximum growth. Accumulation of cystine by S. agalactiae and its reduction to form sulfhydryl compounds were demonstrated. The reduction of cystine appeared to occur by a couple reaction between glutathione reductase and glutathione-disulfide transhydrogenase activity, both of which were found in the supernatant fraction from cell homogenates. NADPH-specific glutathione reductase activity was found in the pellet and supernatant fractions from cell homogenates. Two sulfhydryls were formed for each mole of NADPH used during cystine reduction. The information presented offers a plausible explanation of how cystine, when present in excess of growth needs, may be reduced to generate sulfhydryl compounds which neutralize the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide on S. agalactiae.

Cystine↗
PubMed1973

Extraction of equine infectious anemia immunodiffusion antigen with the aid of the chaotropic agent, thiocyanate.

Immunodiffusion antigen from spleens of horses infected with equine infectious anemia virus was prepared by methods employing freeze-thaw cycles and thiocyanate treatment. Thiocyanate (0.5 M) permitted the recovery of the greatest amount of antigen. Furthermore, it was most effective for recovery of immunodiffusion antigen from spleens which yielded unsatisfactory concentrations of antigen by the conventional freeze-thaw or water-extraction methods. The reactivity of the antigen did not appear to be affected by this chemical treatment.

Animals↗
PubMed1983

Effect of growth phase and cell envelope structure on susceptibility of Salmonella typhimurium to the lactoperoxidase-thiocyanate-hydrogen peroxide system.

The lactoperoxidase-thiocyanate-hydrogen peroxide system was found to have both bacteriostatic and bactericidal activities against strains of Salmonella typhimurium. The bactericidal activity was clearly dependent on the permeability of the bacterial cell envelope. The deep rough mutant TA1535, with the most permeable cell envelope, was killed both at neutral and acid pH, whereas very little or no killing was observed with the intact cells of the parent strain hisG46. The delta gal mutant, TA1530, representing an intermediate in cell envelope permeability, was inhibited to a much lesser extent than TA1535. Bacteria in log phase of growth were more sensitive to the bactericidal effects than were those in stationary phase. Growth phase had little influence on the bacteriostatic effects. The hisG46 strain produced significant quantities of acid in the presence of glucose. This acid production was inhibited by the lactoperoxidase-thiocyanate-hydrogen peroxide system, and, in contrast to results obtained with several strains of streptococci, this inhibition was not reversed by addition of a reducing agent (2-mercaptoethanol).

Cell Membrane Permeability↗
PubMed1994

Antibacterial activity of hydrogen peroxide and the lactoperoxidase-hydrogen peroxide-thiocyanate system against oral streptococci.

In secreted fluids, the enzyme lactoperoxidase (LP) catalyzes the oxidation of thiocyanate ion (SCN-) by hydrogen peroxide (H2O2), producing the weak oxidizing agent hypothiocyanite (OSCN-), which has bacteriostatic activity. However, H2O2 has antibacterial activity in the absence of LP and thiocyanate (SCN-). Therefore, LP may increase antibacterial activity by using H2O2 to produce a more effective inhibitor of bacterial metabolism and growth, or LP may protect bacteria against the toxicity of H2O2 by converting H2O2 to a less-potent oxidizing agent. To clarify the role of LP, the antibacterial activities of H2O2 and the LP-H2O2-SCN- system were compared by measuring loss of viability and inhibition of bacterial metabolism and growth. The relative toxicity of H2O2 and the LP system to oral streptococci was found to depend on the length of time that the bacteria were exposed to the agents. During incubations of up to 4 h, the LP system was from 10 to 500 times more effective than H2O2 as an inhibitor of glucose metabolism, lactic acid production, and growth. However, if no more H2O2 was added, the concentration of the inhibitor OSCN- fell because of slow decomposition of OSCN-, and when OSCN- fell below 0.01 mM, the bacteria resumed metabolism and growth. In contrast, the activity of H2O2 increased with time. H2O2 persisted in the medium for long periods of time because H2O2 reacted slowly with the bacteria and streptococci lack the enzyme catalase, which converts H2O2 to oxygen and water. After 24 h of exposure, H2O2 was as effective as the LP system as an inhibitor of metabolism. H2O2 also caused a time-dependent loss of viability, whereas the LP system had little bactericidal activity. The concentration of H2O2 required to kill half the bacteria within 15 s was 1.8 M (6%) but fell to 0.3 M (1%) at 2 min, to 10 mM (0.03%) at 1 h, and to 0.2 mM (0.0007%) with a 24-h exposure. The results indicate that if high levels of H2O2 can be sustained for long periods of time, H2O2 is an effective bactericidal agent, and the presence of LP and SCN- protects streptococci against killing by H2O2. Nevertheless, the combination of LP, H2O2, and SCN- is much more effective than H2O2 alone as an inhibitor of bacterial metabolism and growth.

Colony Count, Microbial↗
PubMed1998

Induction of protective immunity in rabbits by coadministration of inactivated Pasteurella multocida toxin and potassium thiocyanate extract.

Pasteurella multocida is a bacterial pathogen that causes rhinitis (snuffles), pneumonia, otitis media, septicemia, metritis, and death in domestic rabbits. Currently, there are no effective vaccines to prevent infection by this organism. Subcutaneous (s.c.) immunization with either exotoxin or thiocyanate extracts of P. multocida induces partial protection in rabbits. Since disease begins at mucosal sites, induction of local immunity may be important in preventing systemic disease. Little is known concerning the efficacy of intranasal (i.n. ) administration of these antigens in inducing protective mucosal immunity to P. multocida in rabbits. The purpose of this study was twofold: (i) to investigate the effectiveness of vaccination with purified P. multocida toxin (PMT) and a potassium thiocyanate extract of P. multocida (CN) in combination and (ii) to evaluate the efficacy of administration of these antigens i.n. versus s.c. Forty-eight rabbits were randomly divided into eight different treatment groups. Rabbits received either one or both antigens by either s.c. or i.n. administration. Following vaccination, each group received an i.n. challenge of P. multocida. Rabbits vaccinated with both antigens i.n. or s.c. had a 100% survival rate, few or no bacteria in the liver and lungs, high serum immunoglobulin G (IgG) and IgM antibody titers, and significant numbers of IgG antibody-secreting cells (ASC) in the spleen and tracheobronchial lymph node. Rabbits vaccinated i.n. had significant nasal and bronchoalveolar lavage IgA antibody levels. Rabbits vaccinated with only one antigen, either PMT or CN, had lower antibody titers, moderate to severe liver and lung infections, and fewer ASC compared to rabbits receiving both antigens. Rabbits in the control groups had moderate to severe liver and lung infections. This study indicates that i.n. immunization with both PMT and CN induces an effective response against homologous P. multocida challenge.

Animals↗
PubMed1972

Thiocyanate metabolism in human vitamin B12 deficiency.

Patients with subacute combined degeneration who smoked had significantly lowered plasma thiocyanate levels than control smokers, but plasma thiocyanate levels in non-smoking patients with neurological disease due to vitamin B(12) deficiency were not significantly different from control values. The results provide no support for the hypothesis that chronic cyanide intoxication is responsible for the occurrence of neurological disease in a minority of patients with vitamin B(12) deficiency, although they do not conclusively exclude this possibility. The association between smoking and subacute combined degeneration of the cord has been confirmed in this study but it remains unexplained.

Anemia, Pernicious↗
PubMed1982

Use of objective measurement in the validation of self-reported smoking in children aged 10 and 11 years: saliva thiocyanate.

This study of objective measurement of smoking behaviour reports the findings from a sample of 421 children aged 10 and 11 years from Sheffield. Saliva thiocyanate determination did not provide a satisfactory objective method of validating the self-reported smoking of children in this age group. There was a trend (non-significant) for non-smoking children from homes in which a close relative smoked to have higher concentrations of saliva thiocyanate than non-smokers from "non-smoking" homes. Prior knowledge that a scientific test predicting smoking behaviour would be taken after completion of a questionnaire on smoking increased the self-reportage of experimental smoking.

Child↗
PubMed1983

Belgian heart disease prevention project: comparison of self-reported smoking behaviour with serum thiocyanate concentrations.

At the end of a multifactorial cardiovascular preventive trial serum thiocyanate was measured in random samples of 1035 cases and 1087 controls. A cut-off point 0.45 mg/dl (77.6/mumol/l) gave a sensitivity of 82.1% among the cigarette smokers in the control group and a specificity of 91.0% among the non-smokers. When the intervention and control groups are compared in terms of self-reported smoking behaviour non-significant differences in mean thiocyanate concentration are observed for those who never smoked, ex-cigarette smokers, actual cigarette smokers, and in four different cigarette smoking categories. Our results fail to confirm the reported pessimistic views concerning the validity of self-reported smoking behaviour in subjects taking part in intervention trials.

Adult↗
PubMed1978

Iodide and thiocyanate efflux from brain following injection into rat caudate nucleus.

Mechanisms and pathways of 125I and 35SCN efflux from the brain were investigated in anesthetized rats. Tracers were injected into the caudate nucleus through a guide cannula implanted 1 wk previously and concentrations of isotope in brain and cerebrospinal fluid (CSF) were determined at various times after injection. 125I clearance from the brain followed a single exponential curve. In control rats 36.2% of the 125I remained in the brain 30 min after injection and 60.4% in rats pretreated with perchlorate. Comparable values for 35SCN were 25.8% in control rats, 41.0% with perchlorate, and 39.7% with iodide loading. Estimates of 125I and 35SCN effluxes from the brain via the blood-brain barrier and CSF pathways suggest that greater than 95% of efflux crosses the blood-brain barrier. These results indicate that 1)iodide and thiocyanate are transported across the blood-brain barrier by a common mechanism, and 2) this efflux system is an important factor in the control of the distributions of iodide and thiocyanate in the central nervous system.

Animals↗
PubMed1988

Dietary thiocyanate and N-nitrosation in vivo in the Wistar rat.

The influence of dietary thiocyanate (SCN-) on N-nitrosation in vivo was investigated over 14 min following the administration, by stomach tube, of single doses of sodium nitrite and dimethylamine hydrochloride to male albino Wistar rats whose diet contained appreciable quantities of bound cyanide (cyanogenic glycosides) and free (nonglycosidic) cyanide. The rate of disappearance of the nitrosating agent (NO2-) from the stomach in control animals showed a high linear correlation (r = -0.84) with gastric N-nitrosation, as measured by metabolism (N-demethylation) of 'formed' nitrosamine in liver tissue isolated from these animals. This statistical relationship was significantly increased (r = 0.98), as well as the rate of NO2- utilization and the activity of the N-demethylase enzyme, in animals fed the test diet. Stomach SCN- content was well correlated with both stomach NO2- concentration (r = -0.95) and liver N-demethylase activity (r = +0.93). Interactions, in vivo, between thiocyanate ion and nitrosamine precursors ingested in food may enhance nitrosamine carcinogenesis.

Animals↗
PubMed1988

A simple method for determination of plasma thiocyanate.

We describe a method for the determination of thiocyanate in plasma from blood collected under field conditions in heparinised glass capillary tubes. After deproteinisation of plasma with perchloric acid, thiocyanate is directly determined colorimetrically by the König reaction with sodium hypochlorite as the chlorinating reagent and barbituric acid as the coupling agent. This simple method cannot be applied to urine as the latter contains interfering compounds.

Humans↗
PubMed1985

Thiocyanate feeding with low iodine diet causes chronic iodine retention in thyroids of mice.

Effects of KSCN on thyroidal iodine metabolism were studied in weanling mice fed a low iodide diet (LID) labeled continuously with 125I as iodide. The addition of KSCN (0.3 and 0.6 mg/g diet) resulted in the accumulation of an unusual iodinated protein within the follicles of the mouse thyroids. After 60 days, total thyroidal iodine was 4 times greater than in controls without thiocyanate. The iodinated protein was essentially insoluble at pH 8.0 and was very slowly released from the thyroids; it contained more MIT than DIT and little thyroid hormone. By use of three isotopes (125I, 127I, and 131I) and auto-radiographs, there were shown different iodinated proteins synthesized during high and low iodine intakes and coexistent but segregated in the colloid. Low doses of perchlorate or iodide inhibited or prevented accumulation of the essentially insoluble iodinated protein. It is suggested that when mouse thyroids are iodine depleted, thiocyanate increases the formation of an essentially insoluble iodinated thyroglobulin within the thyroid. Only a small fraction of the iodination may have occurred by this route, but the rate of formation exceeded the rate of release, so the product continuously accumulated.

Animals↗
PubMed1981

Saliva thiocyanate: a chemical indicator of cigarette smoking in adolescents.

Denial and minimization in self-reports of cigarette smoking are probable common among youth and other groups where smoking is discouraged. Chemical measures may obtain more accurate measurement of smoking habits in those groups. One such measure, saliva thiocyanate (SCN), was evaluated in 1,419 eighth grade students. In that group, 54.9% of students admitted to regular smoking of greater than one pack/week had thiocyanates greater than or equal to 100 m g/ml compared to 2.3% nonsmokers at those levels. Of students who smoked greater than or equal to 10 cigarettes in the prior 24 hours, 66.7% were at or above 100 microgram/ml. Elevated SCN in nonsmokers was uncommon. Saliva SCN is a safe, inexpensive, and acceptable prevalence measurement for cigarette smoking. It can be used in place of self-reports to document smoking of greater than on pack/week in populations of youth.

Adolescent↗