Brenda Lorena Fina

Physical exercise ameliorates the toxic effect of fluoride on the insulin–glucose system

Daily intake of water with fluoride concentrations >1.5 mg/l produces insulin resistance (IR). On the other hand, physical activity increases insulin sensitivity in the muscle. Therefore, the aim of this study was to evaluate the effect of physical activity on IR in rats treated with sodium fluoride (NaF) in drinking water. Sprague-Dawley rats were divided into three groups (n=10/group): Control (drinking water without NaF), NaF (drinking water with NaF 15 mg/l for 30 days), and Exercise (daily running on a treadmill for 60 min at 2.25 m/min and drinking water with NaF 15 mg/l for 30 days). IR was evaluated with the homeostasis model assessment-IR (HOMA-IR) index using fasting plasma levels of glucose and insulin. IR increased in rats treated with 15 mg/l NaF in drinking water. A decrease in IR was observed in rats that performed physical activity and drank water with 15 mg/l NaF; the Exercise group also showed an increase in the amounts of bone fluoride. The variation in the HOMA-IR values could be the consequence of variation in the sensitivity of tissues to insulin or decrease in plasma fluoride levels due to bone fluoride intake. These findings indicate that the performance of daily physical activity could reduce the negative effects of the chronic ingestion of NaF on glucose homeostasis.

Fluoride increases superoxide production and impairs the respiratory chain in ROS 17/2.8 osteoblastic cells.

It is known that fluoride produces oxidative stress. Inflammation in bone tissue and an impairment of the respiratory chain of liver have been described in treatments with fluoride. Whether the impairment of the respiratory chain and oxidative stress are related is not known. The aim of this work was to study the effects of fluoride on the production of superoxide radical, the function of the respiratory chain and the increase in oxidative stress in ROS 17/2.8 osteoblastic cells. We measured the effect of fluoride (100 µM) on superoxide production, oxygen consumption, lipid peroxidation and antioxidant enzymes activities of cultured cells following the treatment with fluoride. Fluoride decreased oxygen consumption and increased superoxide production immediately after its addition. Furthermore, chronic treatment with fluoride increased oxidative stress status in osteoblastic cells. These results indicate that fluoride could damage bone tissue by inhibiting the respiratory chain, increasing the production of superoxide radicals and thus of the others reactive oxygen species.

Computational Model for Studying the Analogies Between Endocrine Systems of Humans and Rats with Diabetes Mellitus. Experimental and Simulated Results.

Abstract As a common laboratory practice, rats are studied as biological models for understanding human endocrine behavior. However, up to now there is not a computational model of these mammals because adjusting a physiological model of the endocrine system is not an easy task. Thus, in this work the first mathematical model of the interaction between insulin and glucose in diabetic rats available to the scientific community is presented. It is based on the diabetic patient model accepted by the FDA in 2008. However, it has a large number of parameters, being most of them very difficult to determine in real patients. The main idea is to obtain a proper in silico diabetic rat which would be able to compare well with the experimental data. It will provide interesting insight about the analogies with humans and, in future, analyze the possibility of doing a realistic scale-up between both, humans and rats. Therefore, the list of model equations and the corresponding parameters, obtained by specific experiments, are described and tested with the simulated results.

Comparison of fluoride effects on germination and growth of Zea mays, Glycine max and Sorghum vulgare.

BACKGROUND Fluorosis is a disease caused by over-exposure to fluoride (F). Argentinas rural lands have higher fluorine content than urban lands. Evidence confirms that plants grown in fluoridated areas could have higher F content. We compared F uptake and growth of crops grown in different F concentrations. The effect of 0-8 ppm F concentrations on maize, soybeans and sorghum germination and growth was compared. After 6 days seeding, the germination was determined, the roots and aerial parts lengths were measured, and vigor index was calculated. F content was measured in each part of the plants. Controls with equal concentrations of NaCl were carried out. RESULTS Significant decrease in roots and aerial parts lengths, and in vigor index of maize and soybeans plants was observed with F concentrations greater than 2 ppm. This was not observed in sorghum seedlings. Also, the amount of F in all crops augmented as F increases, being higher in roots and ungerminated seeds. Sorghum was the crop with the highest F content. CONCLUSION Fluoride decreased the germination and growth of maize and soybeans and therefore could influence on their production. Conversely, sorghum seems to be resistant to the action of F.

Increase of calcium and reduction of lactose concentration in milk by treatment with kefir grains and eggshell

Abstract Dairy products are the main source of calcium (Ca), but the loss of the consumption habit contributes to low consumption in adulthood, which leads to osteoporosis and increased fracture risk. Domestic use of kefir is straightforward and the eggshell is a natural discarded source of Ca. This paper proposes the development of an enriched Ca reduced lactose milk using eggshell and kefir. During the in vitro preparation, the pH, Ca and lactose contents were measured. Ca intestinal absorption of untreated milk and milk with kefir was compared. Finally, human volunteers consumed this dairy product and 24-h urine Ca was measured. Results showed that the beverage has lower lactose and higher Ca than untreated milk and milk with kefir. Intestinal Ca absorption was not different between both milks and an increase in urinary Ca excretion was observed in humans. This study provides a methodology to prepare at home a dairy product that could contribute to improve the Ca intake in adults.

CHAPTER 12:Effect of Fluoride on Bone Metabolism, Structure and Remodeling

The effects of fluoride on bone tissue are varied and depend on the dose, the experimental exposure time and the chemical compound of fluoride used. The ingestion of fluoride in drinking water for long periods of time has been shown to produce an increase in bone mineral density and a decrease in fracture risk. However, the administration of fluoride tablets has not been shown to have the same effects. Fluoride administration as tablets produces a peak in plasma fluoride concentration that would be responsible for the adverse effects brought by a decrease in the function of the respiratory chain, an increase in superoxide production and finally an increase in oxidative stress. The bone formed in treatments with fluoride tablets resulted in a decrease in bone fracture load, with signs of inflammation and apoptosis. By contrast, the administration of monofluorophosphate did not have the same effects and resulted in an increase in the rate of repair of bone defects in rats.

CHAPTER 3:The Chemistry of Fluorine

Fluoride is an abundant element in the Earths crust that is incorporated into the body through food and water, or as a therapeutic resource or by other uses in medicine. In nature it is found as fluoride and it is deposited in the body forming fluorapatite both in teeth and bones. Fluoride is one of several compounds related to human health. The chlorofluorocarbons are compounds used as refrigerants, which once discarded can affect the ozone layer of the atmosphere and indirectly human health. Several anesthetics contain fluorine and their metabolism after administration to human beings can release fluoride that causes serious problems to the functioning of various organs. The fluorine isotope of atomic weight 18 is used in medicine for image diagnostic in positron emission tomography. In acidic conditions, fluoride may generate hydrofluoric acid that reacts with the glass, generating compounds that can affect the storage of biological samples and the process of measurement.

Methodology developed for the simultaneous measurement of bone formation and bone resorption in rats based on the pharmacokinetics of fluoride

This paper describes a novel methodology for the simultaneous estimation of bone formation (BF) and resorption (BR) in rats using fluoride as a nonradioactive bone-seeker ion. The pharmacokinetics of flouride have been extensively studied in rats; its constants have all been characterized. This knowledge was the cornerstone for the underlying mathematical model that we used to measure bone fluoride uptake and elimination rate after a dose of fluoride. Bone resorption and formation were estimated by bone fluoride uptake and elimination rate, respectively. ROC analysis showed that sensitivity, specificity and area under the ROC curve were not different from deoxypiridinoline and bone alkaline phosphatase, well-known bone markers. Sprague–Dawley rats with modified bone remodelling (ovariectomy, hyper, and hypocalcic diet, antiresorptive treatment) were used to validate the values obtained with this methodology. The results of BF and BR obtained with this technique were as expected for each biological model. Although the method should be performed under general anesthesia, it has several advantages: simultaneous measurement of BR and BF, low cost, and the use of compounds with no expiration date.