Trace metals in oral mucosa in relation to the lichen ruberplanus pathology. A preliminary study carried out by neutron activation analysis.

Lichen ruberplanus, contact allergy and hypersensitivity can be linked to oral exposure to metals released from metal alloys commonly used in dentistry. In this context neutron activation analysis was developed for the microdetermination of 36 elements in oral mucosa biopsies of two patients affected by lichen ruber planus and of five subjects as control group. In order to minimise metal contamination during sample collection, biopsies were taken by laser bistoury technique and then submitted to radiochemical neutron activation analysis (RNAA). Among the metals analysed, chromium showed obvious high concentration in gingival biopsies of the two pathological subjects compared to the corresponding tissues of control group. Cobalt and nickel were also determined in higher concentrations, but only in one of the oral mucosa of the two patients. The present findings way support the hypothesis concerning a potential link of lichen ruber planus condition with the exposure to Cr, Co and Ni as released into oral cavity from prosthodontic alloys.     

Tissue expression of proliferative antigens (PCNA and Ki-67) in oral lichen ruber related to clinical status

The aim of this study was to determine the expression intensity of PCNA and Ki-67 tissue antigens related to pathologically modified oral mucosa in OLR lesions, and to determine the reaction intensity of these antigens in individual clinical forms, i.e. lichen ruber planus (LRP) and lichen ruber erosivus (LRE) comparing the reaction intensity with the inflammation grade and the degree of hyperkeratosis in lesions of 30 patients. Control group included patients (n = 15) with oral leukoplakia simplex. Tissue antigens were observed by immunohistochemical analysis using APAAP and LSAB methods. The reaction on tested tissue antigens was focal positive and of mosaic type. The reaction of the PCNA antigen was intensely high in OLR lesions regardless on the clinical form of the lesion. The reaction intensity positively correlated with the inflammation grade and the degree of hyperkeratosis in lesions. The reaction on Ki-67 tissue antigen ranged from low to moderately high intensity. Intensely high reaction was observed in lesions of lichen ruber erosivus. The reaction positively correlated with the inflammation grade and the degree of hyperkeratosis in lesions. Observed modified reaction of analyzed tissue antigens related with individual clinical forms of OLR might be the indicator of transformed nature of these lesions.     

Candida biotypes in patients with oral leukoplakia and lichen planus

Prevalence of yeasts in 35 leukoplakia and 34 oral lichen planus patients was compared with that observed in persons without oral diseases. Serotype and morphotype were determined on Candida albicans isolates. Yeasts were isolated from the oral cavity specimens of 43.7% of the patients. C. albicans (serotype A) was the predominant species (76% in leukoplakia, 88.2% in lichen planus and 60.8% in healthy persons). Sixteen morphotypes were encountered on malt extract agar, being 732, 733, 734, 753 and 754 the most frequently found. Morphotypes SP1N and SP1Y were the most common on Sabouraud-trypheniltetrazolium agar (68.4% of the isolates from leukoplakia and 73.3% from lichen planus, but only 46.6% of the isolates from healthy oral mucosa showed SP1N morphotype). Presence of oral lesions was associated with a marked reduction in the yeast species and C. albicans biotypes, suggesting that C. albicans and particularly some of its biotypes, show a high potential of adaptation to the changes associated with the development of oral leukoplakia and lichen planus.     

Increased frequency of delayed type hypersensitivity to metals in patients with connective tissue disease

BackgroundConnective tissue disease (CTD) is a group of inflammatory disorders of unknown aetiology. Patients with CTD often report hypersensitivity to nickel. We examined the frequency of delayed type hypersensitivity (DTH) (Type IV allergy) to metals in patients with CTD.MethodsThirty-eight patients; 9 with systemic lupus erythematosus (SLE), 16 with rheumatoid arthritis (RA), and 13 with Sjögren's syndrome (SS) and a control group of 43 healthy age- and sex-matched subjects were included in the study. A detailed metal exposure history was collected by questionnaire. Metal hypersensitivity was evaluated using the optimised lymphocyte transformation test LTT-MELISA^® (Memory Lymphocyte Immuno Stimulation Assay).ResultsIn all subjects, the main source of metal exposure was dental metal restorations. The majority of patients (87%) had a positive lymphocyte reaction to at least one metal and 63% reacted to two or more metals tested. Within the control group, 43% of healthy subjects reacted to one metal and only 18% reacted to two or more metals. The increased metal reactivity in the patient group compared with the control group was statistically significant (P < 0.0001). The most frequent allergens were nickel, mercury, gold and palladium.ConclusionsPatients with SLE, RA and SS have an increased frequency of metal DTH. Metals such as nickel, mercury and gold are present in dental restorative materials, and many adults are therefore continually exposed to metal ions through corrosion of dental alloys. Metal-related DTH will cause inflammation. Since inflammation is a key process in CTDs, it is possible that metal-specific T cell reactivity is an etiological factor in their development. The role of metal-specific lymphocytes in autoimmunity remains an exciting challenge for future studies.     

Assessment of cytogenetic damage in lymphocytes and in exfoliated nasal cells of dental laboratory technicians exposed to chromium, cobalt, and nickel

Dental laboratory technicians may be exposed to metal alloys that are used in the production of crowns, bridges and removable partial dentures. These alloys consist of 35–65% cobalt, 20–30% chromium, 0–30% nickel, and small amounts of molybdenum, silica, beryllium, boron and carbon. The aim of this study was to assess whether dental technicians are occupationally exposed to chromium, cobalt and nickel, by analyzing urinary excretion levels of these metals and to investigate the genotoxic effects of occupational exposure associated with dental prostheses production operations by analyzing cytokinesis-blocked micronucleus (CB-MN) frequencies in peripheral lymphocytes and micronucleus (MN) frequencies in exfoliated nasal cells from 27 dental laboratory technicians and 15 control subjects. The differences in the urinary excretion of metals between technicians and controls were statistically significant. The mean (±S.D.) CB-MN frequencies (‰) in peripheral lymphocytes were 4.00 (±2.98) among the dental technicians and 1.40 (±1.30) among the controls, a statistically significant difference (P<0.005). The mean (±S.D.) MN frequencies (‰) in nasal cells were 3.50 (±1.80) among the dental technicians and 1.19 (±0.53) among the controls, which was also a statistically significant difference (P<0.005). There was a significant correlation between duration of exposure and MN frequencies in lymphocytes (r=0.642, P<0.01), but not in nasal cells of technicians. Our data reveal that in vivo exposure to chromium, nickel and cobalt metals is evident and that this occupational exposure may contribute to the observed genotoxic damage in two types of cells, e.g. lymphocytes and exfoliated nasal cells. However, it cannot be determined which compound(s) are responsible for the genotoxic damage observed in this study.     

Metallic ion content and damage to the DNA in oral mucosa cells of children with fixed orthodontic appliances

Although the metal devices used in orthodontic treatments are manufactured highly resistance to corrosion, they may still suffer some localized corrosion resulting from the oral cavity conditions. The corrosion causes the release of metals from the alloys used for their manufacture. In this report, we evaluated the in vivo metal ions release of three alloys (stainless steel, titanium and nickel-free) usually used in the orthodontics treatments and its genotoxicity. We applied to 15 patients, between 12 and 16 years, 4 tubes and 20 brackets. Samples from oral mucosa were taken before the treatment and 30 days later. The concentration of the titanium, chromium, manganese, cobalt, nickel, molybdenum and iron were detected using inductively coupled plasma mass spectrometry (ICP-MS). The genotoxicity was measured with a comet assay (Olive moment). The oral mucosa cells in contact with the stainless steel alloy displayed the greatest titanium and manganese concentrations and those in contact with the nickel-free alloy presented the greatest concentration of chromium and iron. Both alloys, stainless steel and nickel-free, induced a higher DNA damage in the oral mucosa cells than the titanium alloy, in which the Olive moment was similar to controls. Based on the results of our study, we can conclude that titanium brackets and tubes are the most biocompatible of the three alloys.     

Lichen substance concentrations in the lichen Hypogymnia physodes are correlated with heavy metal concentrations in the substratum

Lichen substances (i.e. lichen-specific carbon-based secondary compounds) are known to be involved in the uptake and immobilization of metal ions, though the biochemical mechanisms of this interaction are largely unexplained. Previous research on potential effects of lichen substances on heavy metal uptake and tolerance mostly focused on lichens in heavily polluted areas with exceptionally high metal concentrations. In the present study, we aimed at gathering information as to whether lichen substances might be involved in the fine-tuning of metal uptake even at not or low-polluted sites. Therefore, we studied lichen substance concentrations in the epiphytic lichen Hypogymnia physodes and metal concentrations in its substratum in a montane spruce forest of Germany. H. physodes produces two depsides and five depsidones, which had been shown to be involved in metal homeostasis, namely in Cu and Mn uptake, in previous laboratory experiments. The amount of lichen substances increased with increasing heavy metal concentration in the substratum, though the latter varied only in the range of a few μmol g⁻¹ between the sample trees. Variability of lichen substance concentrations in H. physodes within the individual trees was low. Among the different lichen substances of H. physodes, the amount of the depsidone physodalic acid relative to the total of lichen substances was most closely correlated to the concentrations of Cu and Mn in the substratum, whereas the amount of the depsidone 3-hydroxyphysodic acid decreased both with increasing concentrations of these two metals and physodalic acid. Thus, our data suggest that lichen substances contribute to metal homeostasis not only in heavy metal-rich habitats, but also at not or low-polluted sites where the lichen substances apparently help to maintain constant intracellular metal concentrations despite of spatially varying availabilities of metal ions.     

Zn/Pb-tolerant lichens with higher content of secondary metabolites produce less phytochelatins than specimens living in unpolluted habitats

Many lichens can cope with heavy-metal stress, however, the mechanisms of lichen tolerance are still not fully understood. Some lichen secondary metabolites (depsides and depsidones), produced in lichens by the fungal symbiont and accumulated on the outer surface of its hyphae, are supposed to play an important role in the extracellular immoblilization of heavy metals. Lichen photobionts (algal partners in the symbiosis), although surrounded by the mycobiont hyphae, may also accumulate high amounts of trace metals. This can lead to physiological disruptions and morphological damage in algal cells and hence affect the lichen physiological status. We hypothesized that lichen species/specimens living in heavily polluted sites and showing HM tolerance possess a higher content of secondary metabolites than those living in unpolluted sites. Hence, their photobionts can be better protected from the excess of metal ions and need to produce less metal-complexing phytochelatins (PCn) to combat metal toxicity. Specimens of Hypocenomyce scalaris, Cladonia furcata and Lepraria spp. sampled from Zn/Pb-polluted and control sites were compared for the accumulation of Zn/Pb and secondary metabolites, as well as for their production of phytochelatins and glutathione in response to experimental Zn or Pb exposure. Generally, the lichen specimens sampled from the HM-polluted site contained higher amounts of Zn and Pb as well as lichen substances (different depsides and depsidones) than those from the control site. A strong positive correlation was found between the accumulation of secondary metabolites and Zn/Pb accumulation (R² = 0.98 and 0.63, respectively). For the first time, production of phytochelatins (PC_2-3) in response to Zn and Pb (50-200 μM) exposure was found in H. scalaris, L. elobata, L. incana and C. furcata. In both species of Lepraria also cysteine, a substrate for GSH and PCs synthesis was detected. The lichens from the polluted site produced under the same exposure conditions, or in response to higher metal concentrations, lower amounts of PCn than those sampled from the control site. It strongly suggests that less Zn and Pb ions reached the photobiont cells of the lichens containing higher amounts of secondary metabolites (lecanoric, fumarprotocetraric, stictic, constictic acids, antranorin). The results obtained support the putative role of some metabolites in heavy-metal tolerance of the lichens inhabiting metal-polluted habitats.     

Ecophysiological adaptations of two Mediterranean red algae in relation to distribution

Effects of irradiance and temperature on the Mediterranean red algae Eupogodon spinellus and Eupogodon planus were tested. Growth of both species was saturated at an irradiance of 10–20?μmol?m^?2?s^?1, which is in accordance with their sublittoral habitat. Eupogodon spinellus and E. planus survived permanently at temperatures between 8 and 30?°C. The temperature optimum for growth was 25?°C with suboptimal growth occurring at (10?)15 and 30?°C in both species. At their collection locality (Corsica), potential monthly growth yields would be highest in summer and in winter would be only about 20% of the maximum. Reproductive requirements could be determined only in E. planus. Gametophytes reproduced both in long and in short days but only at 20?°C. Tetrasporophytes reproduced at 15–20?°C but only in short days. Geographic distribution boundaries are not set by growth or survival limits. However, the reproductive requirements of E. planus did account for its restricted distribution in the Mediterranean and on the Canary Islands.     

Reactions in the oral mucous membrane after exposure to CarisolvTM ‐ combined results from a clinical screening test in humans and an experimental study in rats

Objective: To evaluate reactions in the oral mucosa after direct contact with Carisolv^TM Setting: The Faculty of Odontology in Göteborg, Sweden. Subjects: 34 healthy persons for a clinical screening test and 35 Sprague Dawley rats for a histological study. Desing: Mixed Carisolv^TM or 0.5 % NaOCl were soaked in paper and applied to either side of the medial frenula of the lower lip of 34 persons. The solutions were left on the oral mucosa for three minutes. Inspection was made and photographs were taken immediately after exposure and also after 1 hour, 24 hours, and 72 hours. Mixed Carisolv^TM was applied in a similar manner as described above to 35 adult Sprague Dawley rats. The animals were killed and biopsies were taken immediately after Carisolv^TM exposure and also after 1 hour, 24 hours, and 48 hours. The biopsies were sectioned and prepared for histomorphometrical evaluation in light microscopy where cells were counted on regions from the epithelium layer deeper into the mucous membrane. Results: Some adverse reactions were detected on the oral mucosa of humans up to 24 hours after Carisolv^TM exposure for 3 minutes. The detected inflammatory reactions were slight and no patient felt any discomfort. The results of the histological study on rat did not show any statistically significant increase of the number of cells at any time after Carisolv^TM exposure. Conclusions: If the oral mucosa gets in direct contact with Carisolv^TM for 3 minutes no or only a weak inflammatory response may be expected.     

Image cytometric evaluation of nuclear texture features and DNA content of the reticular form of oral lichen planus

OBJECTIVE: To analyze image cytometric chromatin changes reflected in nuclear texture features and DNA ploidy of oral lichen planus in relation to the normal buccal mucosa and buccal mucosa expressing malignancy-associated changes in cancer patients. STUDY DESIGN: Twenty-eight patients with the reticular form of oral lichen planus, with a follow-up period of 25 years, 50 healthy controls and 50 lung cancer patients were included in the study. Scrapings of buccal mucosa were suspended in transport medium. Monolayer filter preparations were Feulgen-thionin stained. Image cytometric analysis was performed by Cyto-Savant. RESULTS: All oral lichen planus specimens in our study were diploid. In univariate analysis, differences between the normal buccal mucosa and oral lichen planus were found in several nuclear texture features, which gave an 80% correct classification rate in multivariate analysis. In the second part of the study, the classifier that recognizes malignancy-associated changes on the buccal mucosa of patients with lung cancer correctly recognized > 80% of oral lichen planus samples as normal buccal mucosa. CONCLUSION: Our results indicate that chromatin changes in oral lichen planus exist compared to normal cells; however, the chromatin structure of the reticular form of oral lichen planus does not express malignancy-associated changes and is more similar to normal squamous cells.     

Smoking increases oral mucosa susceptibility to Candida albicans infection via the Nrf2 pathway: In vitro and animal studies

Smoking and Candida albicans (C. albicans) infection are risk factors for many oral diseases. Several studies have reported a close relationship between smoking and the occurrence of C. albicans infection. However, the exact underlying mechanism of this relationship remains unclear. We established a rat infection model and a C. albicans-Leuk1 epithelial cell co-culture model with and without smoke exposure to investigate the mechanism by which smoking contributes to C. albicans infection. Oral mucosa samples from healthy individuals and patients with oral leucoplakia were also analysed according to their smoking status. Our results indicated that smoking induced oxidative stress and redox dysfunction in the oral mucosa. Smoking-induced Nrf2 negatively regulated the NLRP3 inflammasome, impaired the oral mucosal defence response and increased the oral mucosa susceptibility to C. albicans. The results suggest that the Nrf2 pathway could be involved in the pathogenesis of oral diseases by mediating an antioxidative response to cigarette smoke exposure and suppressing host immunity against C. albicans.     

Metallic dental material biocompatibility in osteoblastlike cells

Ions released from metallic dental materials used in orthodontic appliances could induce undesirable effects on cells and tissues. This study evaluates the biocompatibility of two of the most labile components of metallic dental alloys on osteoblastlike cells. The influence of protein and ions on metal dissolution properties is also investigated using different electrolyte solutions. Morphological alterations, cell growth, and differentiation of osteoblasts were assessed after exposure to pure metals (Ag, Cu, Pd, Au) and Ni−Ti alloy and correlated with the kinetics of elements released into the culture media. Results showed that Cu and Ag were the most cytotoxic elements and the other metals were biocompatible with the osteoblasts. The parameters of biocompatibility were correlated with the levels of ions detected into the culture media. Metal ions induced cell death through early mitosis arrest, apoptotic phenomena, and necrotic processes. Voltammograms showed that anions and proteins interfered in the corrosion process. Fetal bovine serum (FBS) strongly affected the electrochemical process, decreasing the oxidation rate of the metals. In conclusion, copper and silver ions showed a time-dependent low biocompatibility, which correlated with the concentration of released ions. The dissolution of the metallic materials was dependent on the composition of the simulated biological media.     

DNA-cytometric detection of euploid polyploidization in oral lichen ruber planus

The DNA distribution was analyzed in 29 cases of oral lichen ruber planus that were negative for human papillomavirus and not suspected of being precancerous. Monolayer smears prepared from formalin-fixed, paraffin-embedded tissues were automatically Feulgen stained and used for rapid interactive DNA cytometry via a TV-based image analysis system combined with an automated microscope. Nuclei with DNA contents greater than 4c were found in 25 cases (86%). DNA contents greater than 8c were seen in five cases (17%), and small peaks at 8c were found in three cases. These increased DNA values in nonprecancerous lesions must be interpreted as euploid polyploidization and have to be taken into account if DNA measurements are performed for diagnostic purposes in lichen ruber planus lesions that are suspected of having malignant transformation.     

Lead Exposure: A Contributing Cause of the Current Breast Cancer Epidemic in Nigerian Women

The paper discusses various approaches used to investigate biocompatibility by the analysis of metals release by the materials of which orthodontic appliances are made. Analysis of various biomarkers of exposure: saliva, serum, mucosa cells, or urine is used in in vivo tests. In this work, the techniques, results, and conclusions of original papers were compared by the implementation of the concept of a systematic review. The aim of the present work was to report the state-of-the-art in the research on methods used to assess exposure to trace metals from orthodontic appliances. The PubMed search identified 35 studies, among which nine met the selection criteria. The general conclusion in the studies was that metal ions were released mostly in the initial stage of the treatment. However, the majority of studies included 1–2 months long period and did not reflect long-term changes nor the impact of the complete treatment, the duration of which is several years, on the whole organism and the overall accumulation of metals from orthodontic appliances. In studies which evaluated nickel concentrations in blood and urine, long-term metal release was detected and significant differences were found. It leads to the conclusion that nickel ions are released from orthodontic appliances in measurable amounts to human organism.     

Similar ecology,different morphology: Three new species of oral-mollusc shellers from Lake Edward

Lake Edward, East Africa, harbours a largely understudied assemblage of haplochromine cichlids that displays a range of adaptions to various specialised trophic niches. In this system, we discovered specimens of Haplochromis with morphologies similar to those of oral-mollusc shellers from Lake Victoria. These morphologies are characterised by short oral jaws with stout teeth that are used either to crush molluscs or to grab the soft bodies of snails and wrench them out of their shells. A morphometric study on 47 specimens from Lake Edward revealed the presence of three new species with an oral-shelling morphology: Haplochromis concilians sp. nov., H. erutus sp. nov. and H. planus sp. nov. All three species are formally described. Stomach-content observations confirmed an opportunistic oral-shelling ecology for H. concilians sp. nov. and H. erutus sp. nov. Within H. planus sp. nov., only large specimens displayed a specialised oral-shelling morphology, but their stomachs were nearly empty, while small specimens consumed mainly Ostracoda and Hydrachnidia. Remarkably, the three species differed considerably in morphology from each other, but they each resembled oral-sheller species from Lake Victoria.     

Estimates of environmental loading from copper alloy materials

Abstract

Metal release rates were measured from four different copper alloy-based materials used by the aquaculture industry: copper sheet machined into a diamond mesh, copper alloy mesh (CAM), silicon bronze welded wire mesh, and copper sheeting, and compared with conventional nylon aquaculture net treated with a cuprous oxide antifouling (AF) coating. Release rates were measured in situ in San Diego Bay using a Navy-developed Dome enclosure system at nine different time points over one year. As expected, copper was the predominant metal released, followed by zinc and nickel, which were fractional components of the materials tested. Release rates followed a temporal trend similar to those observed with copper AF coatings applied to vessel hulls: an initial spike in copper release was followed by a decline to an asymptotic low. Leachate toxicity was consistent with prior studies and was directly related to the metal concentrations, indicating the alloys tested had no additional toxicity above pure metals.     

Detection and identification of non-Candida albicans species in human oral lichen planus

Candida species were detected and identified in samples from the buccal mucosa, dorsal surface of the tongue and supragingival plaque of subjects with oral lichen planus (OLP). The Candida in the samples were cultured on selection agars, and identified by sequence analyses of 18S, 5.8S and 25/28S rRNA. The isolation frequency of Candida was higher in subjects with OLP than in those with healthy oral mucosa. Non-C. albicans were only isolated from people with OLP. These results support the notion that subjects with OLP are more likely to have oral colonization with Candida, and that non-C. albicans are specifically present in subjects with this condition.     

Prenatal exposure to neurotoxic metals is associated with increased placental glucocorticoid receptor DNA methylation

Epigenetic alterations related to prenatal neurotoxic metals exposure may be key in understanding the origins of cognitive and neurobehavioral problems in children. Placental glucocorticoid receptor (NR3C1) methylation has been linked to neurobehavioral risk in early life, but has not been examined in response to neurotoxic metals exposure despite parallel lines of research showing metals exposure and NR3C1 methylation each contribute to a similar set of neurobehavioral phenotypes. Thus, we conducted a study of prenatal neurotoxic metals exposure and placental NR3C1 methylation in a cohort of healthy term singleton pregnancies from Rhode Island, USA (n = 222). Concentrations of arsenic (As; median 0.02 ug/g), cadmium (Cd; median 0.03 μg/g), lead (Pb; median 0.40 μg/g), manganese (Mn; median 0.56 μg/g), mercury (Hg; median 0.02 μg/g), and zinc (Zn; 145.18 μg/g) measured in infant toenails were categorized as tertiles. Multivariable linear regression models tested the independent associations for each metal with NR3C1 methylation, as well as the cumulative risk of exposure to multiple metals simultaneously. Compared to the lowest exposure tertiles, higher levels of As, Cd, Pb, Mn, and Hg were each associated with increased placental NR3C1 methylation (all P<0.02). Coefficients for these associations corresponded with a 0.71–1.41 percent increase in NR3C1 methylation per tertile increase in metals concentrations. For Zn, the lowest exposure tertile compared with the highest tertile was associated with 1.26 percent increase in NR3C1 methylation (P=0.01). Higher cumulative metal risk scores were marginally associated with greater NR3C1 methylation. Taken together, these results indicate that prenatal exposure to neurotoxic metals may affect the offspring's NR3C1 activity, which may help explain cognitive and neurodevelopmental risk later in life.