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J Tenovuo

Publications and source records attributed to J Tenovuo.

At least 109 records · Page 6Linked to original sources
PubMed1986

Products of thiocyanate peroxidation: properties and reaction mechanisms.

The lactoperoxidase-catalyzed oxidation of thiocyanate (SCN-) was studied in the pH range 3-8. The ultraviolet spectra of the oxidation products, the hypothiocyanite ion, OSCN- (at pH 8) and hypothiocyanous acid, HOSCN (at pH 3), were recorded. The absorbance maxima for OSCN- and HOSCN were observed at 220 and 240 nm, respectively. The extinction coefficients for OSCN- and HOSCN were determined to be 3870 (at 220 nM) and 95 M-1 X cm-1 (at 240 nM), respectively. Pure solutions of OSCN- (at pH 8) and HOSCN (at pH 3) were stable, but the mixtures of these two species at intermediate pH values were unstable. The decomposition could be divided into two periods, an initial period of rapid increase in oxidizing equivalents and a second period of decomposition. Decomposition during the second period followed first-order kinetics, and the pH-dependence of the apparent first-order rate constant was consistent with a decomposition mechanism which involved HOSCN. The first-order rate constant for this step was estimated to be 6 X 10(-3) s-1 at 37 degrees C.

Humans↗
PubMed1986

Is thiocyanate peroxidation at equilibrium in vivo?

The peroxidase-catalyzed oxidation of SCN- by H2O2 is an important in vivo reaction because it limits the accumulation of toxic H2O2 and provides significant concentrations of the antimicrobial agents, HOSCN and OSCN-. Data presented in this report suggest that the reaction: (Formula: see text) is in a state of dynamic equilibrium in vivo. Since OSCN- can form the weak acid HOSCN (pKa = 5.3), the equilibrium constant expression (Kox) for thiocyanate peroxidation is dependent on the concentration of hydrogen ions as well as the concentrations of H2O2, SCN-, HOSCN, OSCN- and water, and on the HOSCN ionization constant, Ka: (Formula: see text). The concentration of water is assumed to be constant and unaffected by the other components and is omitted from the Kox equation. The value of Kox was estimated from in vitro data to be 3.7 X 10(3) M-1 (S.D. = 0.8 X 10(3) M-1, n = 8). Using this value for Kox and observations of salivary concentrations of SCN- and HOSCN + OSCN- from several previous reports, the equilibrium concentrations of H2O2 in whole saliva were calculated to range from 8 to 13 microM. This range is consistent with reported estimates of 10 microM as the hydrogen peroxide tolerance limit for human cells.

Animals↗
PubMed1986

Changes in the protein composition of whole saliva during radiotherapy in patients with oral or pharyngeal cancer.

We analyzed the radiation-induced changes in the flow rate and protein composition of stimulated whole saliva in eleven patients treated for malignant conditions of the head and neck. In all patients the radiation field covered all major salivary glands and a large area of the oral mucosa. Paraffin-stimulated whole saliva samples were collected once 2 to 21 days before therapy and then after 20, 40, and 60 gray (Gy) cumulative dose of irradiation. Five patients also provided samples 6 months after the therapy. Hyposalivation or xerostomia occurred in all patients, although the pretreatment secretion rates were already relatively low. Salivary amylase activities decreased with increasing dose of radiation, especially when expressed as the amount of enzyme secreted per minute. Unusually high salivary concentrations of albumin, lactoferrin, lysozyme, salivary peroxidase, myeloperoxidase, and total protein were observed during the therapy, but most values slowly returned to pretreatment levels after cessation of radiation. It is concluded that the observed qualitative changes in whole saliva components are net effects caused by the cancer itself, radiation therapy given, systemic diseases, or medications, as well as mucosal inflammations.

Adult↗
PubMed1986

The biochemistry of nitrates, nitrites, nitrosamines and other potential carcinogens in human saliva.

Human whole saliva protects the oral environment in many different ways from invading pathogenic microorganisms. Human saliva is also capable of inactivating mutagenic and carcinogenic agents by various mechanisms. The peroxidation of these agents is likely to be one of the degrading reactions. However, under certain circumstances some potentially carcinogenic compounds, such as N-nitrosamines, may be generated in whole saliva or--even more likely--in the saliva-gastric juice mixture after swallowing. The formation of N-nitroso compounds requires relatively high intake of nitrate e.g. from vegetable juices. Nitrate is partly reduced to nitrite by oral bacterial enzymes. The nitrosation of various secondary amines is favoured by high salivary (or gastric) concentration of thiocyanate and by low pH. The endogenous generation of N-nitroso compounds may be causally related to the development of oral or gastric cancer.

Carcinogens↗
PubMed1986

Oral health of patients with insulin-dependent diabetes mellitus.

Oral health, the amount of salivary Streptococcus mutans and lactobacilli, and the flow rate, pH and buffer capacity of paraffin-stimulated whole saliva were analyzed in 35 adult diabetic patients and their age- and sex-matched non-diabetic, clinically healthy controls. All patients had insulin-dependent diabetes (IDDM) with a mean (+/- SD) duration of 14.0 +/- 9.1 yr. The prevalence of dental caries was as high in the diabetic group as in the controls but the past caries experience was remarkably lower in those individuals whose diabetes had started at a very early age (less than or equal to 7 yr). In agreement with the clinical data, the salivary levels of cariogenic microorganisms were of the same order of magnitude in both study groups. However, the relative proportion of S. mutans from the total cultivable aerobic microflora was significantly higher (P less than 0.01) in diabetics compared to the controls. The other studied salivary parameters did not differ between the groups. Remarkable individual differences were observed in the correlation between glucose levels of blood and whole saliva among diabetics. In spite of the noncariogenic dietary habits, the adult diabetic patients seem to be at least as susceptible to dental caries as non-diabetics, probably due to the leakage of glucose from blood into the oral cavity.

Adolescent↗
PubMed1986

Antimicrobial factors in whole saliva of human infants.

Antimicrobial factors were analyzed in samples of whole saliva from 31 children, aged 0.8 to 3.8 years. When compared with the adult reference group, the children displayed similar levels of lysozyme, salivary peroxidase, and hypothiocyanite (OSCN-), whereas the amounts of immunoglobulins (isotypes A, G, and M), lactoferrin, myeloperoxidase, thiocyanate (SCN-), amylase, and protein were significantly lower than the adult values. The child's behavior during the collection period noticeably influenced the composition of the saliva. Children who were restless and crying during the collection had significantly more immunoglobulins, lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, and protein in their saliva samples, obviously due to the contamination of saliva mixed with nasal or lacrimal secretions. Therefore, the normal values for saliva could be determined for the noncrying children only. These salivary defense systems did not show any relation to the length of breast-feeding or to the previous history of antibiotic treatment. Thus, with the exception of lactoferrin and myeloperoxidase, the nonimmunoglobulin antimicrobial saliva systems studied here seem to be already at the adult level during early childhood, when the protective antibody systems are still immature.

Adult↗
PubMed1986

Immunoglobulins and innate antimicrobial factors in whole saliva of patients with insulin-dependent diabetes mellitus.

We analyzed the flow rate and composition of paraffin-stimulated whole saliva samples from 35 adult diabetic patients and their age- and sex-matched, non-diabetic, clinically healthy controls. All patients had insulin-dependent diabetes (IDDM) with a mean (+/- S.D.) duration of 14.0 +/- 9.1 years. The saliva analysis included the quantitation of total protein, amylase, immunoglobulins (isotypes A, G, and M), and the non-antibody, innate antimicrobial factors (lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, thiocyanate, and hypothiocyanite). The whole saliva samples from diabetic patients had significantly higher amounts of IgA (p less than 0.001) and IgG (p less than 0.05) than did the controls. No differences between the study groups were observed in flow rate, protein content, amylase activity, or IgM. The levels of innate defense factors were similar in both study groups except for salivary peroxidase, which was higher (p less than 0.02) among diabetics than among controls. Our results indicate that the antimicrobial defense capacity of whole saliva is not impaired in diabetic patients.

Adolescent↗
PubMed1985

Serum antibodies against oral Streptococcus mutans in young children in relation to dental caries and maternal close-contacts.

Thirty-six children aged 2.6-4.9 years were studied with respect to dental caries, Streptococcus mutans counts in dental plaque, and the estimates of total amount and avidity of serum IgG, IgM and IgA antibodies against Strep. mutans 10449, serotype c. A significant positive correlation (r = 0.49, p less than 0.01) was found between the number of Strep. mutans and caries-index in children. Two children with dental caries had no oral Strep. mutans. In median tests, high antibody titre and avidity of serum IgG antibodies against Strep. mutans were associated (p less than 0.05) with low counts of Strep. mutans. No such relationship was found with IgM or IgA antibodies. Children who had had frequent maternal close-contacts in their first year had significantly more (p less than 0.05) IgG antibodies against Strep. mutans than children with rare close-contacts.

Antibodies, Bacterial↗
PubMed1985

Changes in composition of whole saliva in patients with fissured tongue.

Both resting and paraffin-stimulated whole saliva were studied in 25 patients with fissured tongue and in their age and sex-matched healthy controls. The groups did not differ in dental or periodontal health. No significant differences were found between the groups in the salivary secretion rate, pH and buffer capacity, or in the frequency of lactobacilli and yeasts in saliva samples and scrapings from tongue surface. In patients with fissured tongue, unstimulated whole saliva displayed significantly elevated levels of sodium, lysozyme, myeloperoxidase and all immunoglobulins (isotypes A, G and M) when compared with the controls. These changes most likely reflect the inflammation frequently seen in the biopsies of fissured tongue. No differences between the groups existed in the amounts of salivary potassium, calcium, inorganic phosphate, amylase and total protein. Our study shows that in patients with fissured tongue the salivary secretion and composition are normal. However, components from plasma and inflammatory cells are diagnostically elevated in the whole saliva samples of patients with fissured tongue when compared with the healthy controls.

Adult↗
PubMed1985

Antibacterial effect of lactoperoxidase and myeloperoxidase against Bacillus cereus.

An oral periodontopathic bacterium, Bacillus cereus, was inhibited both by lactoperoxidase (LP) and myeloperoxidase (MP) antimicrobial systems. With the LP-SCN--H2O2 system, the growth inhibition was directly proportional to the amount of OSCN- ions present. The OSCN-, which is the principal oxidation product of the LP (or MP)-SCN--H2O2 system at neutral pH, is a normal component of human saliva. The oxidation products of both peroxidase systems inhibited the growth of the bacteria. This inhibition was associated with reduced extracellular release of collagenase activity from the cells. With LP, the antimicrobial efficiency of the oxidizable substrates was SCN- greater than I-, and with MP, the efficiency was I- greater than Cl- greater than SCN-, respectively. LP did not oxidize Cl-.

Anti-Bacterial Agents↗
PubMed1984

The protective effect of peroxidase and thiocyanate against hydrogen peroxide toxicity assessed by the uptake of [3H]-thymidine by human gingival fibroblasts cultured in vitro.

The hypothiocyanite ion (OSCN-) is the principal oxidation product of the salivary peroxidase-thiocyanate (SCN-)-hydrogen peroxide antimicrobial system. Supplementation of human saliva in vitro and in vivo with low amounts (less than 1.0 mM) of hydrogen peroxide increase the concentration of salivary OSCN- (in vivo up to 0.3 mM). Elevated concentrations of OSCN- are strongly antimicrobial and may therefore be protective against dental caries. However, as OSCN- is a highly-reactive oxidizing agent, its possible toxic effect on human cells was studied using gingival fibroblasts as target cells. Concentrations of OSCN- (up to 300 microM) had no effect on [3H]-thymidine incorporation into the cells. However, fibroblasts were sensitive to peroxide so that 100 microM of H2O2 caused over 80 per cent reduction in [3H]-thymidine incorporation. The toxicity of H2O2 could be entirely prevented by adding lactoperoxidase and SCN- to the cell culture before the addition of peroxide. Thus, conversion of toxic H2O2 to non-toxic OSCN- in fibroblast culture by lactoperoxidase and SCN- suggests a dual role for the salivary peroxidase system: protection of human cells from H2O2 toxicity and antimicrobial action against oral pathogens. Furthermore, the elevated concentrations of OSCN- which produce inhibition of bacterial metabolism did not damage human cells.

Adult↗
PubMed1984

Relationship of the human salivary peroxidase system to oral health.

The human salivary peroxidase system (SPS) contributes in several ways to the maintenance of good oral health. The SPS is one of the non-immunoglobulin defense factors which regulate the quantity and species distribution of oral micro-organisms. The SPS also prevents toxic accumulations of hydrogen peroxide (H2O2) and it inactivates many carcinogenic and mutagenic compounds. The salivary glands secrete a peroxidase enzyme (salivary peroxidase) as well as the thiocyanate ion (SCN-, derived from diet). The enzyme catalyzes the oxidation of SCN- by hydrogen peroxide (H2O2). The H2O2 is excreted by oral bacteria and by host cells in amounts which vary with the state of cellular metabolism, the diet and other factors. Oxidized forms of SCN- temporarily inhibit the growth, respiration and metabolism of most species of oral bacteria. The major oxidized form generated in the mouth is the hypothiocyanite ion (OSCN-) which must reach a minimum threshold concentration before bacterial inhibition occurs. This threshold concentration varies from species to species. The concentration of OSCN- in the mouth rises and falls with the availability of H2O2. This natural rise and fall, together with bacterial variation in sensitivity to OSCN- inhibition, suggests a role for the SPS in the regulation of the oral microflora. As a result of the rapid consumption of H2O2 by the SPS, host cells are protected from a toxic build up of this potent oxidizing agent. The major product of the reaction, OSCN-, does not harm human cells. Many carcinogenic and mutagenic compounds may serve as substrates for the SPS and be oxidized to less harmful compounds.

Antibodies↗
PubMed1983

Effect on peroxidase activity and specific binding of the hormone 17 beta-oestradiol and rat salivary glands.

The effect was studied on immature and adult female rats. Oestradiol, given either once (10 micrograms) or three times (3 X 10 micrograms) subcutaneously significantly retarded the total weight gain of immature rats whereas, at the same time, the weight of the uteri increased several fold. The weights of neither salivary nor lacrimal glands were dependent on oestradiol. The activity of the peroxidase enzyme, a marker of oestrogen-responsive tissues, increased significantly in the rat uteri but had no effect on lacrimal peroxidase. The levels of rat salivary peroxidase increased during oestradiol administration with considerable differences between various glands. The increase in peroxidase activities could not be explained by changes in the total protein content but seemed to be specific for this enzyme. Experiments using [3H]-oestradiol indicated specific binding to uterus, parotid and submandibular glands. It is concluded that rat salivary glands are oestrogen-responsive.

Animals↗
PubMed1983

Detection of the hypothiocyanite (OSCN-) ion in human parotid saliva and the effect of pH on OSCN- generation in the salivary peroxidase antimicrobial system.

Human whole saliva contains the hypothiocyanite ion (OSCN-) which is the principal antimicrobial product of the salivary peroxidase system. The peroxidase system requires a source of peroxide in order to produce OSCN- and in the human mouth this source has been assumed to be primarily the peroxidogenic oral bacteria. However, we report here studies which show that samples of stimulated human parotid saliva collected directly from Stenson's duct have concentrations of OSCN- which are similar to those found in human whole saliva. Thus, the peroxidogenic bacteria are not an absolute requirement for the generation of significant levels of OSCN- in the human mouth. Supplementation of human whole saliva with components [thiocyanite (SCN-), hydrogen peroxide (H2O2)] of the peroxidase system produces a 10-fold or greater increase in OSCN- concentration. However, the magnitude of this increase is critically dependent upon pH and upon the relative and absolute concentrations of SCN- and H2O2. The pH dependence of OSCN- generation is similar for human whole saliva and for the lactoperoxidase/SCN-/H2O2 system. The optimum is in the range 6.5-7.0. Samples of parotid saliva adjusted to pH 6.5 and supplemented with appropriate amounts of SCN- and H2O2 show increases in OSCN- concentrations which are similar to those observed with whole saliva. The results show that there is a significant source of H2O2 within the parotid gland, that the OSCN- generating potential of parotid saliva is similar to that of whole saliva and that the enhancement of OSCN- levels in saliva by addition of SCN- and H2O2 is critically dependent upon pH and upon the relative and absolute concentrations of H2O2 and SCN-.

Adult↗