The combined treatment of insulin and naringin improves bone properties in rats with type 1 diabetes mellitus.

We have studied the effects of individual and combined treatment of insulin (I) and naringin (NAR) on the bone structure and biomechanical properties of femurs from streptozotocin (STZ)-induced diabetic rats. Male Wistar rats were divided into five groups: (1) controls, (2) STZ-induced diabetic rats, (3) STZ-induced diabetic rats treated with I, (4) STZ-induced diabetic rats treated with NAR, and (5) STZ-induced diabetic rats treated with I + NAR. Bone mineral density (BMD), bone histomorphometry, biomechanical testing, and bone biomarker expressions were accomplished in femur of all animals, as well as serum biochemical analyses. The combined treatment of I + NAR increased the body weight and the femur BMD from STZ-induced diabetic rats. The bone biomechanical properties and the bone morphology of the femurs from STZ-induced diabetic rats were also improved by the combined treatment. The increased number of osteoclasts in STZ-induced diabetic rats was partially prevented by I, NAR, or I + NAR. NAR or I + NAR completely blocked the decrease in the number of osteocalcin (+) cells in the femur from STZ-induced diabetic rats. RUNX family transcription factor 2 immunostaining was much lower in STZ-induced diabetic rats than in control animals; the combination of I + NAR totally blocked this effect. The combined treatment not only ameliorated bone quality and function, but also normalized the variables related to glucose metabolism. Therefore, the combination of I + NAR might be a better therapeutic strategy than the individual I or NAR administration to reduce bone complications in diabetic patients.

Comparación del contenido de sodio de alimentos del mercado argentino con el valor del rotulo / Comparation of sodium of foods from argentine market with the nutritional label value

Introducción: el sodio (Na) es un elemento abundante en la naturaleza y presente en el agua y en los alimentos que consumimos. El consumo excesivo de Na que, mayormente, proviene de alimentos procesados, es un factor de riesgo para el desarrollo de hipertensión arterial y de enfermedad cardiovascular. En Argentina, el consumo de Na duplica el consumo máximo recomendado de 2000 mg/día. Objetivo: evaluar el contenido de Na de alimentos del mercado argentino y comparar dichos valores con los declarados en los rótulos nutricionales. Materiales y métodos: se seleccionaron 97 productos de diversas categorías (fiambres, quesos, bebidas analcohólicas, galletitas). La concentración de Na se midió por espectroscopía de emisión y se expresó en mg Na/100 g/mL. Resultados: el contenido declarado de Na para los alimentos analizados fue de 630 [10-1833] (mediana [rango]), mientras que el Na medido fue de 645 [6.9-3278]; para las bebidas analcohólicas el Na declarado fue 14 [0-46] y el Na medido 3.7 [0.8-36]. Se halló diferencia significativa entre los valores de Na declarados y medidos en fiambres y bebidas analcohólicas (test de Wilcoxon, p<0.05). Un 41% del valor medido de Na en los alimentos analizados está dentro de la tolerancia ± 20% que exige el Código Alimentario Argentino y un 92% de las bebidas analcohólicas tienen un valor medido menor a dicho intervalo. Conclusiones: los valores declarados y medidos son diferentes para las categorías de fiambres y bebidas analcohólicas, lo que impediría una correcta estimación de la ingesta de Na a partir de estos alimentos

Introduction: sodium (Na) is an element abundant in nature and present in the water and food. The excessive consumption of Na, which mainly comes from processed foods, is a risk factor for the development of high blood pressure and cardiovascular disease. In Argentina, Na consumption doubles the maximum recommended consumption of 2000 mg/day. Objective: to evaluate the Na content of foods in the Argentine market and to compare the values of these with those declared in the nutritional labels. Materials and Methods: 97 products were selected from various categories (cold cuts, cheeses, sweetened beverages, cookies). The Na concentration was measured by emission spectroscopy and was expressed in mg Na/100 g/mL. Results: The median and range of the declared Na was for the foods analyzed was 630 [10-1833] (median [range]), while the measured Na was 645 [6.9-3278]; for non-alcoholic beverages, declared Na was 14 [0-46] and measured Na was 3.7 [0.8-36]. A significant difference was found between the Na values declared and measured in cold cuts and sweetened beverages (Wilcoxon test, p<0.05). Forty one percent of the measured value of Na in the foods analyzed are within the tolerance ± 20% required by The Argentine Food Code and 92% of the non-alcoholic beverages have a measured value lower than said interval. Conclusions: the declared and measured values are different for the categories of cold cuts and non-alcoholic beverages, which would prevent a correct estimation of the Na intake from these foods

Naringin prevents bone damage in the experimental metabolic syndrome induced by a fructose-rich diet.

We analyzed the effect of naringin (NAR), a flavonoid from citric fruits, on bone quality and biomechanical properties, as well as the redox state of bone marrow in rats fed a fructose-rich diet (FRD), an experimental model to mimic human metabolic syndrome. NAR blocked the increase in the number of osteoclasts and adipocytes and the decrease in the number of osteocytes and osteocalcin (+) cells caused by FRD. Trabecular number was significantly higher in the FRD+NAR group. FRD induced a decrease in the femoral trabecular and cortical bone mineral density, which was blocked by NAR. The fracture and ultimate loads were also decreased in the FRD and FRD+NAR groups. NAR increased the number of nodes to terminal trabecula, the number of nodes to node trabecula, the number of nodes, and the number of nodes with 2 terminals and decreased the Dist (mean size of branches) value. FRD decreased bone marrow catalase activity, an effect that was prevented by NAR. In conclusion, FRD has detrimental effects on the long bones, which are associated with oxidative stress in the bone marrow. Most of these changes are prevented by NAR through its antioxidant properties and promotion of bone formation. Novelty: Fructose-rich diets have detrimental effects on long bones, which are associated with oxidative stress in the bone marrow. Most of these changes are prevented by naringin through its antioxidant properties and promotion of bone formation.

Levels and predictors of depression, anxiety, and suicidal risk during COVID-19 pandemic in Argentina: the impacts of quarantine extensions on mental health state.

This research is aimed to: analyze differences in mental health state (MHS) indicators (depression, state-anxiety, trait-anxiety, and suicidal risk), during three quarantine sub-periods (starting since the first quarantine extension); assess multiple relationships between each MHS indicator and potentially affecting factors. We used a cross-sectional design with a convenience sample including 1100 participants. Data were collected online. Depression revealed a worsening pattern as quarantine sub-periods went by. Anxiety (both state and trait), just like suicidal risk, partially follow such a pattern, with mean scores increasing from the first to the second/third quarantine extensions, but then maintaining to the fourth extension. Predictors having protective effects on almost all the MHS indicators were: availability of current economic income (except for state-anxiety, without significant effect) and absence of suicide attempt history. Conversely, sex (woman), younger age, and mental disorder history had an increasing risk effect on all the MHS indicators. Overall, our findings indicate that quarantine have negative mental health impacts and that quarantine duration is a relevant aspect to be taken into account when measuring such an impact. More attention needs to be paid to vulnerable groups such as the young, women, and people with history of mental disorder.

Effect of fluoride on bone and growth plate cartilage.

The use of fluoride (F) for therapeutic purposes is controversial and its toxicity is a health problem. The aim of this study was to evaluate the effect of F on endochondral ossification in growing rats. Twenty-four rats of 21 days were divided into 4 groups which received 0, 20, 40 or 80 µmol F/100 g body weight/day for 30 days, through an orogastric tube. Histological evaluation of growth plate cartilage (GPC) and primary and secondary bone were analyzed on sections of the metaphysis of tibias. Total thickness of the GPC (GPC.Th), thickness of resting zone (RZ.Th), proliferative zone (PZ.Th) and hypertrophic zone (HZ.Th); bone volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), and apoptosis by the TUNEL were measured. A hyperplasia of the proliferative zone and a significant increase in PZ.Th with 40 and 80 µmol F without changes in GPC.Th were found. In the secondary trabecular bone, presence of immature trabeculae, peritrabecular inflammatory foci and sinusoidal dilatation were observed. A significant decrease in BV/TV was also found due to a decrease in Tb.Th and a progressive increase was observed in the number of apoptotic nuclei as the dose of F increased. In conclusion, results suggest that prolonged administration (30 days) of F negatively affect the endochondral ossification with increased chondrocyte proliferation and delayed maturity of new bone, causing inflammatory damage, edema, and increased apoptotic bone cells.

Estimación de la ingesta de calcio y fosfato a partir de bebidas analcohólicas / Calcium and phosphate intake from analcoholic beverages

El calcio (Ca) es un nutriente crítico para la salud, especialmente en los períodos de crecimiento. Sin embargo, la mayoría de los individuos argentinos no alcanzan la ingesta diaria recomendada. Por su parte, el fósforo (P) es un nutriente cuya ingesta suele estar por encima de la recomendada. Este tipo de desequilibrio en la ingesta de ambos nutrientes conlleva a una pérdida de masa ósea. El consumo de bebidas analcohólicas (BA) se ha incrementado en los últimos años, sobre todo en la población infantil, desplazando el consumo de agua y lácteos. El objetivo de este trabajo fue estimar el aporte de Ca y P a partir de BA diferentes de agua. Se evaluaron 59 muestras, cuya mediana y rango de Ca fue de 7,74 [0,00 a 111,29] mg/l y de P 55,17 [0,16 a 957,00] mg/l. Los jugos en polvo son los que mayor contenido de Ca presentaron y las bebidas deportivas aquellas donde se halló el mayor contenido de P. Considerando un consumo de 500 ml/día de BA se estarían incorporando 3,87 mg Ca y 27,59 mg P. El creciente consumo de BA, su bajo contenido de Ca y la concomitante reducción del consumo de lácteos contribuyen a una inadecuada ingesta de Ca. (AU)

Calcium (Ca) is a critical nutrient, especially during periods of growth. However, the majority of Argentine individuals do not reach the recommended daily intake. On the other hand, phosphorus (P) is a nutrient with an intake usually above the recommended values. This type of imbalance between the intake of the nutrients leads to loss of bone mass. Soft drinks consumption (BA) has increased in recent years, especially in children, displacing the consumption of water and dairy products. The aim of this work was to estimate the Ca and P content in BA other than water. 59 samples were evaluated, with a median and range of Ca of 7.74 [0.00 to 111.29] mg/l and of P of 55.17 [0.16 to 957.00] mg/l. Powdered juices are the ones with the highest Ca content, and sports drinks are the beverages in which the highest P content was found. Based on a BA consumption of 500 ml/day, 3.87 mg Ca and 27.59 mg P would be incorporated. Therefore, the increased consumption of BA, their low Ca content, and the concomitant reduction in dairy consumption contribute to an inadequate intake of Ca. (AU)

Contribution of calcium in drinking water from a South American country to dietary calcium intake.

OBJECTIVE: To describe the calcium concentration of tap and bottled waters from Argentina and to estimate the contribution of drinking water to calcium recommendations. RESULTS: Calcium concentrations provided by water authorities ranged from 6 to 105 mg/L. The mean calcium level of samples analysed at the Laboratorio de Ingeniería Sanitaria, National University of La Plata was 15.8 (SD ± 13.2) mg/L and at the Bone Biology Laboratory of the National University of Rosario was 13.1 (± 10.0) mg/L. Calcium values of samples from supply systems and private wells was similar. Most bottled waters had calcium levels well below 50 mg/L. The intake of one litre of drinking water from Argentina could represent in average between 1.2 and 8.0% of the calcium daily values for an adult.

Effect of fermented milk with kefir grains on the in vitro demineralization of bovine tooth enamel / Efecto de la leche fermentada con granos de kéfir sobre la desmineralización in vitro del esmalte dental bovino

The dental caries is a progressive destruction of the teeth tissue due to the disbalance in the normal molecule interactions between the enamel and the bio!lm, which alters the demineralization-remineralization process. Milk fermentation produces caseinphosphopeptides with proved remineralizing capacity of the enamel. The presence of these peptides in fermented milk with ke!r grains has been described. The purpose of this work was to evaluate in vitro the capacity of milk ke!r to prevent the demineralization of dental enamel. Bovine incisors (n=68, 17 per group) were treated for 72 h with different solutions: I: artificial saliva at pH 7.2 , II: demineralizing solution at pH 4.5, III: supernatant of kefir fermented milk at pH 4.5, IV: milk supernatant at pH 4.5. The effects of treatments were evaluated by the change in the weight of the specimens, calcium concentration in the solution and by scanning electron microscopy (SEM) of the enamel. Kefir milk supernatant prevented the demineralization process, that was evidenced by a change in weight and calcium concentration that were not different from group I, although the pH was 4.5. In contrast, group IV showed a decrease in weight and an increase in calcium concentration, compared with group I (one way ANOVA, p<0.05). Images of SEM agree with the values of weight and calcium concentration. These results indicate that kefir milk supernatant has a protective effect on enamel demineralization in vitro. (AU)

La caries dental es una patología debido a un desequilibrio en las interacciones moleculares normales entre el esmalte y la biopelícula, que altera el proceso de desmineralización remineralización. La fermentación de la leche produce fosfopéptidos de caseína con probada capacidad remineralizante del esmalte, y se ha descripto la presencia de estos péptidos en la leche fermentada con granos de kéfir. El propósito de este trabajo fue evaluar in vitro la capacidad del kéfir de leche para prevenir la desmineralización del esmalte dental. Sesenta y ocho incisivos bovinos (17 por grupo) fueron tratados durante 72 h con diferentes soluciones: I: saliva artificial, pH 7.2, II: solución desmineralizante, pH 4.5, III: sobrenadante de leche fermentada con kefir, pH 4.5, IV: sobrenadante de leche, pH 4.5. El proceso de desmineralización se evaluó mediante el cambio en el peso de las muestras, la concentración de calcio en la solución y microscopía electrónica de barrido (SEM) del esmalte. El sobrenadante de leche fermentada con kéfir impidió el proceso de desmineralización, que se evidenció por un cambio en el peso y la concentración de calcio que no discreparon del grupo I, a pesar de haber tenido un pH de 4.5. En contraste, el grupo IV mostró una disminución en el peso y un aumento en la concentración de calcio, en comparación con el grupo I (ANOVA a un criterio, p<0.05). Las imágenes SEM concuerdan con los cambios en el peso y la concentración de calcio en los grupos estudiados. Los datos obtenidos demuestran que el sobrenadante de la leche tratada con kéfir tiene un efecto protector sobre la desmineralización del esmalte in vitro, inducida por el pH ácido. (AU)

Bone Strength in Growing Rats Treated with Fluoride: a Multi-dose Histomorphometric, Biomechanical and Densitometric Study.

Bone deformation and fragility are common signs of skeletal fluorosis. Disorganisation of bone tissue and presence of inflammatory foci were observed after fluoride (F-) administration. Most information about F- effects on bone has been obtained in adult individuals. However, in fluorosis areas, children are a population very exposed to F- and prone to develop not only dental but also skeletal fluoroses. The aim of this work was to evaluate the bone parameters responsible for the effect of different doses of F- on fracture load of the trabecular and cortical bones using multivariate analysis in growing rats. Twenty-four 21-day-old Sprague-Dawley rats were divided into four groups: F0, F20, F40 and F80, which received orally 0, 20, 40 or 80 µmol F-/100 g bw/day, respectively, for 30 days. After treatment, tibiae were used for measuring bone histomorphometric and connectivity parameters, bone mineral density (BMD) and bone cortical parameters. The femurs were used for biomechanical tests and bone F- content. Trabecular bone volume was significantly decreased by F-. Consistently, we observed a significant decrease in fracture load and Young's modulus (YM) of the trabecular bone in F--treated groups. However, cortical bone parameters were not significantly affected by F-. Moreover, there were no significant differences in cortical nor trabecular BMD. Multivariate analysis revealed a significant correlation between the trabecular fracture load and YM but not with bone volume or BMD. It is concluded that when F- is administered as a single daily dose, it produces significant decrease in trabecular bone strength by changing the elasticity of the trabecular bone.

In vivo measurement of the rate constant of liver handling of glucose and glucose uptake by insulin-dependent tissues, using a mathematical model for glucose homeostasis in diabetic rats.

Diabetes mellitus is a disease that affects glucose homeostasis. The World Health Organization informs that there are over 347 million people in the world with diabetes. The diagnosis and characterization of glucose homeostasis in different metabolic conditions are subjects of great importance with high clinical impact. There are many mathematical models that describe the glucoregulatory system in detail. However, the use of these models is limited because they have a large number of mathematical equations and parameters and they require complex methodologies to estimate of them. This forced to work with average values that decrease the validity of results and the applicability of the models. In this study two mathematical models for rats with diabetes mellitus were developed. The difference between these models and others lies in the possibility of obtaining all parameters for each animal from simple measurements (glucose and insulin plasma levels). Moreover, the models allow to measure in vivo the different physiological processes involved in glucose homeostasis in animals: insulin secretion and its plasma clearance, absorption of insulin from a subcutaneous injection, the liver handling of glucose, intestine absorption of glucose, glucose uptake rate of insulin-independent tissues, glucose uptake rate of insulin-dependent tissues, and renal glucose excretion.

Assessment of the SWAT model to simulate a watershed with limited available data in the Pampas region, Argentina.

Argentina has been among the world leaders in the production and export of agricultural products since the 1990s. The Carcarañá River Lower Basin (CRLB), a cropland of the Pampas region supplied by extensive rainfall, is located in an area with few streamgauging and other hydrologic/water-quality stations. Therefore, limited hydrologic data are available resulting in limited water-resources assessment. This work explores the application of Soil and Water Assessment Tool (SWAT) model to the CRLB in the Santa Fe province of the Pampas region. The analysis of field and remote-sensing data characterizing hydrology, water quality, soil types, land use/land cover, management practices, and crop yield, guarantee a comprehensive SWAT modeling approach. A combined manual and automated calibration and validation process incorporating sensitivity and uncertainty analysis is performed using information concerning interior watershed processes. Eleven N/P fertilizer rates are selected to simulate the impact of N fertilizer on crop yield, plant uptake, as well as runoff and leaching losses. Different indices (partial factor productivity, agronomic efficiency, apparent crop recovery efficiency of applied nutrient, internal utilization efficiency, and physiological efficiency) are considered to assess nitrogen-use efficiency. The overall quality of the fit is satisfactory considering the input data limitations. This work provides, for the first time in Argentina, a reliable tool to simulate yield response to soil quality and water availability capable to meet defined environmental targets to support decision making on planning public policies and private activities on the Pampas region.

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

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.

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). Argentina's 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. © 2015 Society of Chemical Industry.

Efecto de la yerba mate (ilex paraguariensis) sobre el hueso de ratas ovariectomizadas / Effect of yerba mate (ilex paraguariensis) on bone in ovariectomized rats

El consumo de yerba mate (Ilex paraguariensis) es habitual en la Argentina y otros países de América del Sur. La yerba mate, al igual que el café y el té, contiene xantinas y polifenoles. El consumo de café ha mostrado tener impacto negativo sobre la densidad mineral ósea (DMO), mientras que el té ha mostrado tener efecto protector. En mujeres posmenopáusicas tomadoras de mate se halló mayor DMO de columna lumbar y cuello femoral en comparación con controles que no bebían mate. La DMO también fue mayor en ratas que recibieron una infusión de yerba mate y dieta baja en calcio; sin embargo, este incremento no fue capaz de revertir el efecto negativo del bajo contenido de calcio sobre las propiedades biomecánicas y la conectividad trabecular. El objetivo de este trabajo fue estudiar el tejido óseo de ratas ovariectomizadas (OVX) luego de recibir una infusión de yerba mate por 90 días en reemplazo del agua de bebida. Se utilizaron ratas Sprague Dawley (n=16) hembras divididas en 2 grupos: OVX+agua y OVX+yerba. Otro grupo de ratas (n=6) fue sometido a una cirugía simulada (Sham). El estudio mostró claramente el efecto deletéreo de la ovariectomía sobre todos los parámetros estudiados (DMO, histomorfometría ósea, conectividad trabecular y biomecánica) respecto del grupo Sham. El grupo OVX+yerba no mostró diferencias con el grupo OVX+agua en ninguno de los parámetros analizados, por lo que la yerba mate no produciría efecto alguno sobre el hueso de ratas adultas ovariectomizadas. (AU)

Yerba mate (Ilex paraguariensis) consumption is common in Argentina and other South American countries. Like coffee and tea, yerba mate contains xanthines and polyphenols. It has been reported that caffeine consumption has a negative impact on bone mineral density (BMD) while tea has been shown to have a protective effect. On the other hand, in postmenopausal women that usually consumed yerba mate, lumbar spine and femoral neck BMDs were higher than in non-consumers. BMD was also higher in rats that received a yerba mate infusion and low calcium diet. However, this increase was not sufficient to reverse the negative effect of a low calcium diet on bone biomechanical properties and trabecular connectivity. The aim of this work was to study bone tissue in ovariectomized (OVX) rats receiving an infusion of yerba mate instead of drinking water for 90 days. Female Sprague Dawley rats (n=16) were divided into 2 groups: OVX+water and OVX+yerba. A third group of rats (n=6) was submitted to sham surgery (Sham). Results clearly showed the deleterious effect of ovariectomy on all studied parameters (BMD, bone histomorphometry, trabecular connectivity and biomechanical properties) compared to Sham group. The OVX+yerba group showed no difference with OVX+water group in all analyzed parameters. It is concluded that yerba mate does not produce any effect on the bone of ovariectomized adult rats. (AU)

Effects of Yerba Mate (IIex paraguariensis) on Histomorphometry, Biomechanics, and Densitometry on Bones in the Rat.

Yerba mate (Ilex paraguariensis) is a xanthine-containing beverage, which is also rich in caffeine. Because caffeine has a negative impact on bone mineral density (BMD) mainly associated with low calcium (Ca) diets, there would be expected a negative effect of yerba mate on bone. In this study, Sprague-Dawley rats were used and randomly assigned into four groups (n = 6/group): Control + Ca 0.2 g %; Control + Ca 0.9 g %; Yerba + Ca 0.2 g %; Yerba + Ca 0.9 g %. At the end of the experiment, tibias and femurs were obtained for BMD, morphometric, histomorphometric, and biomechanical analyses. While there was no difference in bone parameters between rats with and without yerba mate consumption, a negative effect of low Ca diet was observed in BMD, morphometric, histomorphometric, and biomechanical results. Interaction between Ca content in the diet and yerba mate was only found in trabecular bone volume, which would indicate that the negative effect of low Ca intake on bone volume is reversed in part by yerba mate infusion. However, yerba mate was not able to reverse the negative effect of low Ca content on biomechanical properties and trabecular connectivity. In summary, at least in our study, yerba mate would not have a negative effect on bone and would be safe for the bone health of consumers.

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.

Proteomic analysis of gastrocnemius muscle in rats with streptozotocin-induced diabetes and chronically exposed to fluoride.

Administration of high doses of fluoride (F) can alter glucose homeostasis and lead to insulin resistance (IR). This study determined the profile of protein expression in the gastrocnemius muscle of rats with streptozotocin-induced diabetes that were chronically exposed to F. Male Wistar rats (60 days old) were randomly distributed into two groups of 18 animals. In one group, diabetes was induced through the administration of streptozotocin. Each group (D-diabetic and ND-non-diabetic) was further divided into 3 subgroups each of which was exposed to a different F concentration via drinking water (0 ppm, 10 ppm or 50 ppm F, as NaF). After 22 days of treatment, the gastrocnemius muscle was collected and submitted to proteomic analysis (2D-PAGE followed by LC-MS/MS). Protein functions were classified by the GO biological process (ClueGO v2.0.7+Clupedia v1.0.8) and protein-protein interaction networks were constructed (PSICQUIC, Cytoscape). Quantitative intensity analysis of the proteomic data revealed differential expression of 75 spots for ND0 vs. D0, 76 for ND10 vs.D10, 58 spots for ND50 vs. D50, 52 spots for D0 vs. D10 and 38 spots for D0 vs. D50. The GO annotations with the most significant terms in the comparisons of ND0 vs. D0, ND10 vs. D10, ND50 vs. D50, D0 vs. D10 and D0 vs. D50, were muscle contraction, carbohydrate catabolic processes, generation of precursor metabolites and energy, NAD metabolic processes and gluconeogenesis, respectively. Analysis of subnetworks revealed that, in all comparisons, proteins with fold changes interacted with GLUT4. GLUT4 interacting proteins, such as MDH and the stress proteins HSPB8 and GRP78, exhibited decreased expression when D animals were exposed to F. The presence of the two stress proteins indicates an increase in IR, which might worsen diabetes. Future studies should evaluate whether diabetic animals treated with F have increased IR, as well as which molecular mechanisms are involved.

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.

Regulation of intestinal calcium absorption by luminal calcium content: role of intestinal alkaline phosphatase.

SCOPE: Intestinal alkaline phosphatase is a brush border enzyme that is stimulated by calcium. Inhibition of intestinal alkaline phosphatase increases intestinal calcium absorption. We hypothesized that intestinal alkaline phosphatase acts as a minute-to-minute regulatory mechanism of calcium entry. The aim of this study was to evaluate the mechanism by which intestinal luminal calcium controls intestinal calcium absorption. METHODS AND RESULTS: We performed kinetic studies with purified intestinal alkaline phosphatase and everted duodenal sacs and showed that intestinal alkaline phosphatase modifies the luminal pH as a function of enzyme concentration and calcium luminal content. A decrease in pH occurred simultaneously with a decrease in calcium absorption. The inhibition of intestinal alkaline phosphatase by l-phenylalanine caused an increase in calcium absorption. This effect was also confirmed in calcium uptake experiments with isolated duodenal cells. CONCLUSION: Changes in luminal pH arising from intestinal alkaline phosphatase activity induced by luminal calcium concentration modulate intestinal calcium absorption.

Mathematical model of glucose-insulin homeostasis in healthy rats.

According to the World Health Organization there are over 220 million people in the world with diabetes and 3.4 million people died in 2004 as a consequence of this pathology. Development of an artificial pancreas would allow to restore control of blood glucose by coupling an infusion pump to a continuous glucose sensor in the blood. The design of such a device requires the development and application of mathematical models which represent the gluco-regulatory system. Models developed by other research groups describe very well the gluco-regulatory system but have a large number of mathematical equations and require complex methodologies for the estimation of its parameters. In this work we propose a mathematical model to study the homeostasis of glucose and insulin in healthy rats. The proposed model consists of three differential equations and 8 parameters that describe the variation of: blood glucose concentration, blood insulin concentration and amount of glucose in the intestine. All parameters were obtained by setting functions to the values of glucose and insulin in blood obtained after oral glucose administration. In vivo and in silico validations were performed. Additionally, a qualitative analysis has been done to verify the aforementioned model. We have shown that this model has a single, biologically consistent equilibrium point. This model is a first step in the development of a mathematical model for the type I diabetic rat.