Oral peroxidases: From antimicrobial agents to ecological actors (Review).

Sialoperoxidase and myeloperoxidase are the two main peroxidase enzymes found in the oral cavity. Sialoperoxidase is present in salivary secretions and in the biofilms that line the oral surfaces, while myeloperoxidase is abundant in the dento‑gingival sulcus area. In the presence of hydrogen peroxide (HO), oral peroxidases catalyze the oxidation of the pseudohalide anion thiocyanate (SCN) to hypothiocyanite (OSCN), a strong oxidant that serves an antimicrobial role.

Effects of tyrosol and farnesol on Candida albicans biofilm.

The present in vitro study examined the effects of the quorum‑sensing molecules farnesol and tyrosol on the development of Candida albicans biofilm in order to elucidate their role as novel adjuvants in oral hygiene. The investigation was conducted in C. albicans ATCC 10231 and C.

Ex vivo decontamination of yeast-colonized dentures by iodine-thiocyanate complexes.

Introduction: Under well-defined experimental conditions, and in the presence of hydrogen peroxide, lactoperoxidase produces stable iodine-thiocyanate complexes that have antimicrobial properties. A novel process was developed to short circuit the consumption of hydrogen peroxide by microbial catalases by producing iodine-thiocyanate complexes prior to contact with microorganisms, with the aim of being able to decontaminate the ex vivo dentures colonized by yeasts.

Materials And Methods: Teabags containing lactoperoxidase adsorbed on inert clay beads were immersed for 1 minute in phosphate buffer solution (0.

Dose‑dependent effect of lysozyme upon Candida albicans biofilm.

The present study investigated the in vitro effect of lysozyme (0-1,000 µg/ml) on Candida albicans (C. albicans) biofilm development. Investigations were conducted on C.

Candida albicans susceptibility to lactoperoxidase-generated hypoiodite.

In vivo, lactoperoxidase produces hypothiocyanite (OSCN(-)) from thiocyanate (SCN(-)) in the presence of hydrogen peroxide (H2O2); in vitro, iodide (I(-)) can be oxidized into hypoiodite (OI(-)) by this enzyme. The aim of this study was to compare in vitro the anti-Candida effect of iodide versus thiocyanate used as lactoperoxidase substrate to prevent Candida biofilms development. Candida albicans ATCC 10231 susceptibility upon both peroxidase systems was tested in three different experimental designs: (i) in a liquid culture medium, (ii) in an interface model between solid culture medium and gel containing the enzymic systems, (iii) in a biofilm model onto titanium and acrylic resin.

Candida albicans biofilm on titanium: effect of peroxidase precoating.

The present study aimed to document Candida albicans biofilm development on titanium and its modulation by a peroxidase-precoated material which can generate antimicrobials, such as hypoiodite or hypothiocyanite, from hydrogen peroxide, iodide, or thiocyanate. For this purpose, titanium (powder or foil) was suspended in Sabouraud liquid medium inoculated with C. albicans ATCC10231.

Denture contamination by yeasts in the elderly.

Objectives: The aim of this study was to investigate yeast carriage in healthy denture wearers by swabbing and to evaluate the effect of denture hygiene habits.

Materials And Methods: Denture wearers (n = 87) without evidence of denture stomatitis or any other oral disease were investigated by separately swabbing the fitting surface of the upper denture and the corresponding palatal mucosa in contact with the appliance. In a group of volunteers, a gel without any active compound was spread on the palatal side of the denture once in every morning for 2 weeks.

Effects of plasma membrane Ca(2+)-ATPase overexpression upon D-glucose metabolism in insulin-producing BRIN-BD11 cells.

In order to investigate the possible link between PMCA (plasma-membrane Ca(2+)-ATPase) activity and D-glucose catabolism in insulin-producing cells, BRIN-BD11 cells were transfected with two isoforms of PMCA2. Transfection of insulin-producing BRIN-BD11 cells with PMCA2yb and PMCA2wb was documented by RT-PCR (reverse transcription-PCR), Western blot analysis, indirect immunofluorescence microscopy and (45)Ca(2+) uptake by microsomes. In the transfected cells, the overexpression of PMCA coincided with three major anomalies of D-glucose metabolism, namely a lower rate of D-[5-(3)H]glucose utilization prevailing at a low extracellular concentration of D-glucose (1.

Altered K+ fluxes and insulin release in pancreatic islets from omega3 fatty acid-depleted rats.

A low intake of long-chain polyunsaturated omega3 fatty acid often prevails in Western populations. Its consequences in terms of the control of fuel homeostasis led us to explore functional events in pancreatic islets isolated from either normal or omega3-depleted rats (second generation). In the latter rats, the inflow of K+ by both ouabain-sensitive and ouabain-resistant modalities was decreased, this coinciding with an impaired insulin secretory response to ouabain.

Possible role of carbonic anhydrase in rat pancreatic islets: enzymatic, secretory, metabolic, ionic, and electrical aspects.

The presence of carbonic anhydrase (type V) was recently documented in rat and mouse pancreatic islet beta-cells by immunostaining and Western blotting. In the present study, the activity of carbonic anhydrase was measured in rat islet homogenates and shown to be about four times lower than in rat parotid cells. The pattern for the inhibitory action of acetazolamide on carbonic anhydrase activity also differed in islet and parotid cell homogenates, suggesting the presence of different isoenzymes.

Fatty acid content and pattern of epididymal and parametrial adipose tissue lipids in streptozotocin (type 1) and Goto-Kakizaki (type 2) diabetic rats.

Attention was recently drawn to differences in the fatty acid pattern of liver phospholipids and triglycerides in animal models of type 1 and type 2 diabetes. The present study extends this knowledge to epididymal or parametrial adipose tissue lipids. The fatty acid pattern of such lipids was established in four fed female normal rats, four overnight fasted female normal rats, six fed female rats rendered diabetic by an injection of streptozotocin 3 days before sacrifice (STZ rats), and four female and four male Goto-Kakizaki rats (GK rats) also examined in the fed or fasted state.

Pancreatic islet function in omega3 fatty acid-depleted rats: Glucose metabolism and nutrient-stimulated insulin release.

In order to gain information on the determinism of the perturbation of fuel homeostasis in situations characterized by a depletion in long-chain polyunsaturated omega3 fatty acids (omega3), the metabolic and hormonal status of omega3-depleted rats (second generation) was examined. When required, these rats were injected intravenously 120 min before sacrifice with a novel medium-chain triglyceride-fish oil emulsion able to provoke a rapid and sustained increase of the omega3 content in cell phospholipids. The measurement of plasma glucose, insulin, phospholipid, triglyceride, and unesterified fatty acid concentration indicated modest insulin resistance in the omega3-depleted rats.

Opposite effects of D-fructose on total versus cytosolic ATP/ADP ratio in pancreatic islet cells.

D-fructose (10 mM) augments, in rat pancreatic islets, insulin release evoked by 10 mM D-glucose. Even in the absence of D-glucose, D-fructose (100 mM) displays a positive insulinotropic action. It was now examined whether the insulinotropic action of D-fructose could be attributed to an increase in the ATP content of islet cells.

Fructokinase activity in rat liver, ileum, parotid gland, pancreas, pancreatic islet, B and non-B islet cell homogenates.

The presence of fructokinase (ketohexokinase) in rat pancreatic islet homogenates was previously documented. However, no information was so far available on the activity of this enzyme in islets relative to that in other tissues and on the respective contribution of insulin-producing B cells and non-B islet cells. The present study provides such an information.

Effects of a medium-chain triglyceride:fish oil emulsion administered intravenously to omega3 fatty acid-depleted rats on cationic fluxes in aortic rings.

The handling of 45Ca and 86Rb by aortic rings obtained from rats depleted in long-chain polyunsaturated omega3 fatty acids (second generation) was examined in vitro over 10 to 60 min incubation at either increasing concentrations of extracellular K+ (5, 3 and 60 mM) in the case of 45Ca net uptake or in the absence and presence of ouabain (50 microM) in the case of 86Rb uptake. The omega3-depleted rats were injected intravenously 120 min before sacrifice with 1.0 ml of either an omega3 fatty acid-rich medium-chain triglyceride:fish oil emulsion (MCT:FO) or a control medium-chain triglyceride:olive oil emulsion (MCT:OO).

Gut permeability and intestinal mucins, invertase, and peroxidase in control and diabetes-prone BB rats fed either a protective or a diabetogenic diet.

This study deals with the enteropathy recently identified in diabetes-prone BB rats (BBdp). Diabetes-resistant BB rats (BBc) and BBdp rats were fed from days 32-39 onward either a protective diabetes-retardant hydrolyzed casein diet (HC) or a plant-based diabetogenic (NTP) diet. The NTP diet decreased body weight and plasma insulin in BBc and BBdp rats.

Anomeric specificity of D-[U-14C]glucose incorporation into glycogen in rat hemidiaphragms.

The anomeric specificity of D-[U-14C]glucose incorporation into glycogen in rat hemidiaphragms was investigated. For this purpose, the hemidiaphragms were preincubated for 30 min at 37 degrees C and then incubated for 5 min at the same temperature in the presence of alpha- or beta-D-[U-14C]glucose. The concentrations of D-glucose (5.

Quantitative and qualitative alterations of intestinal mucins in BioBreeding rats.

In diabetes-prone BioBreeding rats, an enteropathy often precedes the onset of auto-immune insulitis. The present study draws attention to quantitative and qualitative alterations of intestinal mucins in this animal model of type 1 diabetes mellitus. Male and female diabetes-resistant (BBc) and diabetes-prone (BBdp) BioBreeding rats fed, from one to two weeks after weaning onwards, either a plant-based diabetes-promoting diet (NTP) or a hydrolysed casein diabetes-protective diet (HC), were sacrificed at 11-14 weeks of age.

Impaired enzyme-to-enzyme channelling between hexokinase isoenzyme(s) and phosphoglucoisomerase in rat pancreatic islets incubated at a low concentration of D-glucose.

It was recently proposed that in rat pancreatic islets exposed to 8.3 mM D-glucose, alpha-D-glucose-6-phosphate undergoes enzyme-to-enzyme channelling between hexokinase isoenzyme(s) and phosphoglucoisomerase. To explore the identity of the hexokinase isoenzyme(s) involved in such a tunnelling process, the generation of 3HOH from the alpha- and beta-anomers of either D-[2-3H]glucose or D-[5-3H]glucose was now measured over 60 min incubation at 4 degrees C in pancreatic islets exposed only to 2.

Peroxidase activity in the intestinal tract of Wistar-Furth, BBc and BBdp rats.

Background: The development of immune-mediated diabetes in BB rats may involve an inflammatory lesion of the intestinal tract.

Methods: In order to further explore this issue, the activity of peroxidase was measured, in the absence and presence of either bromide or dapsone, at day 10, 30, 45, 70, 95 and 120 in three segments (top, mid and bottom) of the intestinal tract from Wistar-Furth rats and both diabetes-resistant and diabetes-prone BB rats fed after weaning either diabetes-promoting diets or a protective diet, which decreases the incidence of diabetes in the BB rats.

Results: In the present study, from day 30 onwards, an age-related increase in peroxidase activity was found in the intestine of diabetes-prone BB rats (BBdp rats) fed diabetogenic diets, when compared with either Wistar-Furth or diabetes-resistant BB rats (BBc rats).

Dissimilar effects of D-mannoheptulose on the phosphorylation of alpha- versus beta-D-glucose by either hexokinase or glucokinase.

D-mannoheptulose inhibits D-glucose phosphorylation by hexokinase isoenzymes. The present study aims at investigating whether the pattern of such an inhibition differs in the case of alpha- versus beta-D-glucose. The phosphorylation of alpha- and beta-D-[U-14C]glucose was measured over 60-min incubation at 4 degrees C in the presence of bovine heart hexokinase and over 10 min at 24 degrees C in the presence of human liver glucokinase.

Bioactive GLP-1 in gut, receptor expression in pancreas, and insulin response to GLP-1 in diabetes-prone rats.

Glucagon-like peptide-1 (GLP-1) is the most insulinogenic of the glucagon-like peptides secreted mainly by L cells in the small and large intestine in response to the ingestion of nutrients. It binds to a specific GLP-1 receptor (GLP-1R) on beta-cells and can increase islet neogenesis and beta-cell mass. It is not clear whether the transmission of information from the gut to islet beta-cells by messengers such as GLP-1 is different in individuals who develop autoimmune diabetes.

Disaccharidase activity in the intestinal tract of Wistar-Furth, diabetes-resistant and diabetes-prone BioBreeding rats.

Diabetes-prone BioBreeding (BBdp) rats often present an enteropathy that may precede the onset of autoimmune insulitis. The aim of the present study was to assess the influence of sex, the time course, the strain specificity, the distribution along the intestinal tract and the effect of diet for the changes in the activity of gut invertase, maltase and lactase found in BBdp rats, as compared with both Wistar-Furth (WF) and diabetes-resistant BioBreeding (BBc) rats. These hydrolases were measured, therefore, at day 10, 30, 45, 70, 95 and 120 in three intestinal segments of WF, BBc and BBdp rats fed, after weaning, either a protective hydrolysed casein diet, which decreases the incidence of diabetes in the BBdp rats, or one of two diabetogenic diets (National Toxicology Program; NTP or wheat-gluten-based; WG) [corrected].

Alteration of alpha-amylase secretion from rat parotid cells in the absence of extracellular bicarbonate.

A sufficient availability of the bicarbonate anion is required to allow a normal process of glucose-stimulated insulin release. Thus, both the removal of extracellular bicarbonate and the inhibition of carbonic anhydrase by acetazolamide suppress the insulinotropic action of glucose. In the present study, a comparable situation is documented in rat parotid cells.

Invertase, maltase, lactase, and peroxidase activities in duodenum of BB rats.

The development of immune-mediated diabetes in BB rats may involve a defect of the gastrointestinal tract (GI), as suggested by increased gut permeability. This study aimed at measuring invertase, maltase, lactase, and peroxidase activities in the duodenum of diabetesprone BioBreeding (BBdp) rats and control BioBreeding rats (BBc) given free access to NIH-07 diet up to the time of killing at 60 66 d of age. After washing the entire small intestine, the duodenal mucosa was scraped off in the first 5-cm segment from the pylorus and frozen in distilled water.