Abstract
Chronic exposure to fluoride continues to be a public health problem worldwide, affecting thousands of people. Fluoride can cause abnormal proliferation and activation of osteoblast and osteoclast, leading to skeletal fluorosis that can cause pain and harm to joints and bones and even lead to permanent disability. Nevertheless, there is no recognized mechanism to explain the bone lesions of fluorosis. In this work, we performed a population study and in vitro experiments to investigate the pathogenic mechanism of skeletal fluorosis in relation to methylation of the promoter of p16. The protein coded by the p16 gene inhibits cdk (cyclin-dependent kinase) 4/cdk6-mediated phosphorylation4 of retinoblastoma gene product and induces cell cycle arrest. The results showed that hypermethylation of p16 and reduced gene expression was evident in peripheral blood mononuclear cells of patients with fluorosis and correlated with the level of fluoride exposure. Studies with cell cultures of osteoblasts revealed in response to sodium fluoride (NaF) treatment, there was an induction of p16 hypermethylation and decreased expression, leading to increased cell proliferation, a longer S-phase of the cell cycle, and development of skeletal fluorosis. Further, the methylation inhibitor, 5-aza-2-deoxycytidine, reversed the p16 hypermethylation and expression in response to NaF. These results reveal a regulatory role of p16 gene methylation on osteoblasts activation during the development of skeletal fluorosis.
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Fluoride-induced oxidative stress in three-dimensional culture of OS732 cells and rats.
Exposure to excessive fluoride poses a threat to human health, including increased susceptibility to developing the skeletal fluorosis. Despite its recognized importance as an endemic disease, little is known about how fluoride directly impacts on osteoblasts. We previously reported that fluoride-stimulating monolayer-cultured osteoblast proliferation or inhibiting cell viability depended on
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Fluoride induces hypomethylation of BMP2 and activates osteoblasts through the Wnt/B-catenin signaling pathway.
Background: Skeletal fluorosis has become a public health issue in recent years as its serious impact on patients' life expectancy. Bone morphogenetic protein 2 (BMP2) plays a key role in promoting osteogenesis. However, the mechanism of BMP2-Wnt/B-catenin axis in skeletal fluorosis needs further exploration. Methods: The RT-qPCR
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Is the severity of osteosclerosis of fluorosis proportional to the dose of fluoride intake?
Histomorphometric study was made on a series of sections of undecalcified epiphyseal femoral specimens from rats with experimental fluorosis. The results revealed osteosclerosis in Group A (5 ppm) being more severe than that in Group B (25 ppm). With the increase of fluoride dose, the parameters fell down instead of
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The pathogenesis of endemic fluorosis: Research progress in the last 5 years.
Fluorine is one of the trace elements necessary for health. It has many physiological functions, and participates in normal metabolism. However, fluorine has paradoxical effects on the body. Many studies have shown that tissues and organs of humans and animals appear to suffer different degrees of damage after long-term direct
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Effects of fluoride on the proliferation and activation of osteoblasts by regulating methylation of the DNA repair genes MGMT and MLH1.
Introduction Fluoride can induce the proliferation and activation of osteoblasts, resulting in skeletal fluorosis progression; however, the specific mechanism is unclear. Methods Cell proliferation was examined using the MTT assay. Flow cytometry was performed to detect the cell cycle distribution. Alkaline phosphatase (ALP) was calculated to evaluate bone formation and turnover. Gene methylation
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Skeletal Fluorosis: The Misdiagnosis Problem
It is a virtual certainty that there are individuals in the general population unknowingly suffering from some form of skeletal fluorosis as a result of a doctor's failure to consider fluoride as a cause of their symptoms. Proof that this is the case can be found in the following case reports of skeletal fluorosis written by doctors in the U.S. and other western countries. As can be seen, a consistent feature of these reports is that fluorosis patients--even those with crippling skeletal fluorosis--are misdiagnosed for years by multiple teams of doctors who routinely fail to consider fluoride as a possible cause of their disease.
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Fluoride & Osteoarthritis
While the osteoarthritic effects that occurred from fluoride exposure were once considered to be limited to those with skeletal fluorosis, recent research shows that fluoride can cause osteoarthritis in the absence of traditionally defined fluorosis. Conventional methods used for detecting skeletal fluorosis, therefore, will fail to detect the full range of people suffering from fluoride-induced osteoarthritis.
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"Pre-Skeletal" Fluorosis
As demonstrated by the studies below, skeletal fluorosis may produce adverse symptoms, including arthritic pains, clinical osteoarthritis, gastrointestinal disturbances, and bone fragility, before the classic bone change of fluorosis (i.e., osteosclerosis in the spine and pelvis) is detectable by x-ray. Relying on x-rays, therefore, to diagnosis skeletal fluorosis will invariably fail to protect those individuals who are suffering from the pre-skeletal phase of the disease. Moreover, some individuals with clinical skeletal fluorosis will not develop an increase in bone density, let alone osteosclerosis, of the spine. Thus, relying on unusual increases in spinal bone density will under-detect the rate of skeletal fluoride poisoning in a population.
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Fluoride's Effect on Osteoblasts (Bone-Forming Cells)
As noted by the National Research Council, "[p]erhaps the single clearest effect of fluoride on the skeleton is its stimulation of osteoblast proliferation." (NRC 2006). Osteoblasts are bone-forming cells. "Stimulatory effects of fluoride on osteoblasts result in formation of osteoid, which subsequently undergoes mineralization." (Fisher RL, et al. 1989). If the new
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Exposure Pathways Linked to Skeletal Fluorosis
Excessive fluoride exposure from any source -- and from all sources combined -- can cause skeletal fluorosis. Some exposure pathways , however, have been specifically identified as placing individuals at risk of skeletal fluorosis. These exposure pathways include: Fluoridated Water for Kidney Patients Excessive Tea Consumption High-Fluoride Well Water Industrial Fluoride Exposure Fluorinated Pharmaceuticals (Voriconazole
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