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About Hybenova M, Hrda P, Prochazkova J, Stejskal V, Sterzl I. T

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So far Hybenova M, Hrda P, Prochazkova J, Stejskal V, Sterzl I. T has created 991 blog entries.

The role of environmental factors in autoimmune thyroiditis.

Environmental factors can play an important role in the development of autoimmune thyroiditis (AT) and other autoimmune diseases. This article reviews the role of heavy metals and infectious agents in AT. Currently, the genes responsible for a metal-induced pathology are known in experimental animals but similar knowledge is lacking in man. Metals such as nickel or mercury induce delayed type T cell hypersensitivity (allergy) which is relatively common, especially in women. T-cell allergy can be studied with the lymphocyte transformation test, LTT-MELISA. It has been found that patients with AT and other autoimmune diseases, such as multiple sclerosis, psoriasis, systemic lupus erythematosus and atopic eczema, show increased lymphocyte reactivity in vitro to inorganic mercury, nickel and other metals compared to healthy controls. The important source of mercury is dental amalgam. Replacement of amalgam in mercury-allergic subjects resulted in improvement of health in about 70% of patients. Several laboratory parameters such as mercury-specific lymphocyte responses in vitro and anti-thyroid autoantibodies were normalized as well. In contrast, no changes in health and laboratory results were observed in mercury-allergic patients who did not have their amalgams replaced. The same was true for non-allergic patients who underwent amalgam replacement. Infectious agents such as Helicobacter pylori (Hp) may cause chronic inflammation and autoimmune reactivity in susceptible subjects. The results of in vitro experiments performed with lymphocytes from Hp infected patients indicate that Hp can cause immunosuppression which might be eliminated by successful eradication therapy. In conclusion, heavy metals and Hp infection may play an important role in AT. Laboratory tests, such as LTT-MELISA, can help to determine the specific etiological agents causing inflammation in individual patients. The treatment of AT and other autoimmune diseases might be improved if such agents are eliminated and any future exposure restricted.

Toxicology of autoimmune diseases.

Susceptibility to most autoimmune diseases is dependent on polygenic inheritance, environmental factors, and poorly defined stochastic events. One of the significant challenges facing autoimmune disease research is in identifying the specific events that trigger loss of tolerance and autoimmunity. Although many intrinsic factors, including age, sex, and genetics, contribute to autoimmunity, extrinsic factors such as drugs, chemicals, microbes, or other environmental factors can also act as important initiators. This review explores how certain extrinsic factors, namely, drugs and chemicals, can promote the development of autoimmunity, focusing on a few better characterized agents that, in most instances, have been shown to produce autoimmune manifestations in human populations. Mechanisms of autoimmune disease induction are discussed in terms of research obtained using specific animal models. Although a number of different pathways have been delineated for drug/chemical-induced autoimmunity, some similarities do exist, and a working model is proposed.

By |2018-07-29T17:57:28+00:00January 1st, 2010|Other|

Mercury exposure and children’s health.

Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic
(methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children’s health.

By |2018-07-19T16:58:40+00:00January 1st, 2010|Mercury|

Predictors of treatment outcomes after removal of amalgam fillings: associations between subjective symptoms, psychometric variables and mercury levels.

OBJECTIVE:
This analysis aimed to study predictors of different treatment outcomes and associations between subjective symptoms, psychometric variables and mercury levels in patients who subjectively attributed their health problems to dental amalgam.

MATERIAL AND METHODS:
A secondary and retrospective analysis of data of a recently published randomized clinical trial was performed. Seventy-eight patients [44% female, mean (SD) age 35 (6) years, randomly assigned to either amalgam removal or a health promotion program] were included into statistical analysis. Prior to intervention and 12 months later, questionnaires for assessing symptoms, psychological distress and health status were presented, and mercury levels in blood and urine were determined.

RESULTS:
The patients’ personality profile at study onset was characterized by slightly reduced extraversion and slightly elevated emotional instability. Overall, subjective symptoms decreased slightly and there were no statistically significant differences in the decrease of symptoms after intervention between both groups. Decrease of mercury levels after intervention was closely associated with removal of amalgam fillings (r(mult) = 0.64 in regression analysis). Statistically significant correlations could be found between mercury levels and subjective symptoms with respect to baseline (r = 0.29-0.39) and to changes after intervention (r = 0.24-0.42), but not for psychological distress (r = 0.05-0.25) and health related quality of life (r = -0.03-0.18). Prediction of symptom improvement after intervention was poor (r(mult) = 0.44).

CONCLUSIONS:
Results contribute some new aspects to the inconsistent findings in the literature with respect to associations between symptoms and subtoxic mercury levels. More emphasis should be placed on exploring individual vulnerability for amalgam sensitivity.

Periodontitis and atherosclerotic vascular disease

Recent scientific statement by the American Heart Association (AHA) titled “Periodontal Disease and Atherosclerotic Vascular Disease: Does the Evidence Support an Independent Association?”1 has stimulated a wave of media attention on this important subject. Unfortunately, a misleading press release that has since been corrected and re-issued resulted in dissemination of inaccurate information in the print and electronic media and has generated more confusion about a topic that needed clarity. For this reason, it is a good time to take a closer look at what we have learned from a wide body of literature in which researchers have examined the association between periodontitis and atherosclerotic vascular disease (AVD); what gaps in knowledge must be addressed in further research; what we, as health care professionals, can and should tell our patients today about this important topic.

By |2019-06-03T02:13:42+00:00January 1st, 2010|Periodontal Disease|

Penetration of sodium hypochlorite into dentin

INTRODUCTION:

Sodium hypochlorite (NaOCl) is the most commonly used root canal irrigant. The aim of this study was to evaluate the effect of concentration, time of exposure, and temperature on the penetration of NaOCl into dentinal tubules.

METHODS:

Thirty extracted human permanent maxillary anterior teeth with single canals were instrumented by using ProTaper rotary files. The teeth were then sectioned perpendicular to the long axis. The crowns and apical thirds of all the teeth were removed. The remaining roots were processed into 4-mm-long blocks and stained overnight in crystal violet. One hundred eight stained blocks were treated by 1%, 2%, 4%, and 6% NaOCl for 2, 5, and 20 minutes at 20 degrees C, 37 degrees C, and 45 degrees C, respectively. The depth of penetration of NaOCl was determined by bleaching of the stain and measured by light microscopy at magnifications of 20x and 40x. Statistical comparisons were made by using one-way analysis of variance, and Dunnett T3 tests were made for multiple comparisons.

RESULTS:

The shortest penetration (77 mum) was measured after incubation with 1% NaOCl for 2 minutes at room temperature. The highest penetration (300 mum) was obtained with 6% NaOCl for 20 minutes at 45 degrees C. After the initial penetration during the first 2 minutes, the depth of penetration doubled during the next 18 minutes of exposure. Temperature had a modest effect within each group on the depth of penetration and in most cases was not statistically significant (P > .05). Depth of penetration increased with increasing hypochlorite concentration, but the differences were small. Within each time group, depth of penetration with 1% NaOCl was about 50%-80% of the values with the 6% solution.

CONCLUSIONS:

Temperature, time, and concentration all contribute to the penetration of sodium hypochlorite into dentinal tubules.

By |2019-06-03T01:47:11+00:00January 1st, 2010|Other|

Bacterial and human peptidylarginine deiminases: targets for inhibiting the autoimmune response in rheumatoid arthritis

Peptidylarginine deiminases (PADs) convert arginine within a peptide (peptidylarginine) into peptidylcitrulline. Citrullination by human PADs is important in normal physiology and inflammation. Porphyromonas gingivalis, a major pathogen in periodontitis, is the only prokaryote described to possess PAD. P. gingivalis infection may generate citrullinated peptides, which trigger anti-citrullinated peptide antibodies. In susceptible individuals, host protein citrullination by human PADs in the joint probably perpetuates antibody formation, paving the way for the development of chronic arthritis. Blockades of bacterial and human PADs may act as powerful novel therapies by inhibiting the generation of the antigens that trigger and sustain autoimmunity in rheumatoid arthritis.

By |2019-06-17T00:23:40+00:00January 1st, 2010|Other|

Cytotoxicity of dental adhesives in vitro.

OBJECTIVES:
The purpose of this study was to evaluate the cytotoxic effect of six dental adhesives (Admira Bond, Clearfil Liner Bond 2V, ED Primer II, Fuji Bond LC, Gluma Comfort Bond, and NanoBond) applied to cell cultures.

METHODS:
The experiments were performed on two cell lines, rat pulp cells (RPC-C2A) and human lung fibroblasts (MRC5). Samples of the adhesives were light-cured and placed in culture medium for 24 hours. The extraction media was applied on the RPC-C2A and the MRC5 cells. Complete medium was used as a control. Cytotoxicity was evaluated with a modified sulforhodamine B (SRB) assay after 24 hours of exposure.

RESULTS:
The cell survival of RPC-C2A cells exposed to Fuji Bond LC, NanoBond, Clearfil Liner Bond 2V, ED Primer II, Admira Bond and Gluma Comfort Bond was 73%, 67%, 50%, 20%, 18% and 5% respectively, relative to the cell survival with the control medium. In the MRC5 cell line, the relative survival was 98%, 80%, 72%, 41%, 19% and 7% after exposure to NanoBond, Fuji Bond LC, Clearfil Liner Bond 2V, ED Primer II, Admira Bond and Gluma Comfort Bond, respectively.

CONCLUSIONS:
Different types of dental adhesives showed different cytotoxic effects on cells in vitro. The self-etch adhesives were superior in terms of cytotoxicity. The different cytotoxic effects of dental adhesives should be considered when selecting an appropriate adhesive for operative restorations.

Effect of magnetic resonance imaging on microleakage of amalgam restorations: an in vitro study.

OBJECTIVES:
The technique of MRI, using powerful magnets, plays an important role in the diagnosis of diseases of the head and neck without any ionizing radiation. Because of the potential hazard imposed by the presence of ferromagnetic metals, patients with implanted metallic objects are excluded from MRI. However, amalgam restorations seem to be safe. The purpose of this study was to evaluate microleakage of amalgam restorations following MRI.

METHODS:
63 human freshly extracted premolars were divided into 3 groups based on 3 high-copper amalgams used to restore standard class V preparations on both buccal and lingual surfaces. Three different amalgam materials were used: Cinalux, GS-80 and Vivacap. The teeth were transferred into saline solution for 2 months at room temperature and then sectioned mesiodistally. MRI was randomly applied to one half of each section, and the other half was kept as a control. Following MRI, all specimens were immersed in a dye solution, sectioned and scored for any microleakage using a stereomicroscope.

RESULTS:
Differences in microleakage within each group following MRI were significant in the GS-80 and Vivacap groups but not in the Cinalux group. However, there was no significant difference between the three groups regarding the microleakage score.

CONCLUSIONS:
The results of this study suggest that MRI is not a completely safe technique in patients with amalgam restorations. It was shown that the main effect of fields led to the appearance of thermoelectromagnetic convection, which is responsible for the enhancement of the diffusion process, grain boundary migration and vacancy formation resulting in microleakage.

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