Search

People are exposed to a number of environmental, occupational, and therapeutic toxic agents which may be natural or man made. These hazardous substances may manifest as direct side effects on the function of organs or indirectly induced alteration of gene expression, cancer-associated metabolic pathways, and/or alter homeostasis. Lycopene, as a one of the most potent antioxidant, is found in fruits and vegetables. High-intake of lycopene has been shown to be effective in decreasing the risk of both natural toxins including mycotoxins, bacterial toxins, and chemical toxins including heavy metals, pesticides as well as herbicides. Recently, there is growing attention in understanding the mechanisms of the phytochemicals and carotenoids as antioxidative, antiapoptotic, radical scavenging, and chelating agents and their roles in the modulation of inflammatory pathways. This review summarizes available data from several recent studies about lycopene and its role against chemical and natural toxicants. © 2018 BioFactors, 45(1):5-23, 2019., (© 2018 International Union of Biochemistry and Molecular Biology.)

Fluoride (F - ) is becoming an ineluctable environmental pollutant causing deleterious effects in humans. In the present study, we examined whether tamarind seed coat extract (TSCE) is beneficial against the F - -induced systemic toxicity and hematological changes. Wistar rats were randomly grouped as follows: group I served as control; group II intoxicated with sodium fluoride (NaF, 300 ppm) in drinking water; group III was administered through oral intubation with TSCE (100 mg/kg bw); group IV was treated with NaF (300 ppm) in association with TSCE (100 mg/kg bw) for 30 days. The results indicated that F - exposure induced oxidative stress as evidenced by elevated levels of reactive oxygen species and lipid peroxidation in the brain, liver, and kidney. F - administration modulates hematological indices-WBC, RBC, and mean corpuscular volume. Moreover, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, acetylcholinesterase, and monoamine oxidase significantly increased on F - exposure. Conversely, δ-aminolevulinic acid dehydratase and glutathione/reduced glutathione ratio were decreased. Activity of antioxidants-superoxide dismutase, catalase, glutathione peroxidase, and vitamin C-was also significantly decreased due to F - administration. Treatment with TSCE effectively mitigated the alterations through its antioxidant potential. The data suggested that the TSCE had beneficial effects in alleviating the F - -induced toxicity and hence can serve as a promising neutraceutical agent.

Excessive consumption of fluoride (F) through drinking, eating, and/or environmental contaminants induces chronic toxicity known as fluorosis. Our previous research has shown that fluorosis was associated with male reproductive disorders. The current study is designed to explain the protective effect of vitamin E (VE), insulin-like growth factor-I (IGF-I), and human chorionic gonadotropin (hCG) against natrium fluoride (NaF)-induced alterations in isolated Leydig cells (LCs). These NaF-induced alterations include decreased cell proliferation, steroidogenesis, and relative gene expression. Isolated LCs were incubated with NaF (0, 5, 20 mg/L) and/or 10 μg/ml VE, 100 ng/ml IGF-I, and 100 IU/ml hCG. NaF-treated cells' ability to secrete testosterone (T) was significantly less than other treated groups (P < 0.05). Additionally, in NaF-treated cells, there was a significant upregulation of certain relative mRNA expressions such as Star and Cyp11a, as well as significantly less cell proliferation in a dose-dependent manner (P < 0.05). These data clearly show that VE, IGF-1, and hCG have a protective effect in the LCs functions. Taken together, the final results of this study shown herein are consistent with the assumption that VE, IGF-I, and hCG volunteered ameliorative effects against the deleterious effects of NaF through their protective activity. Although it is hypothesized that ameliorative effects might have been involved, the fundamental pathway(s) remain(s) to be illuminated. Graphical Abstract ᅟ.

Fluoride intoxication and dexamethasone treatment produce deleterious effects in bone and brain. The aim of this study was to evaluate the effect of fluoride (F) and dexamethasone (Dex) co-exposure on oxidative stress and apoptosis in osteoblast-like MC3T3-E1 and hippocampal HT22 cell lines. Co-exposure to F and Dex resulted in a concentration-dependent decrease in cell viability, induction of apoptosis and increased generation of reactive oxygen species (ROS) and nitric oxide (NO) following 72 h of incubation. Fluoride-induced apoptosis in MC3T3-E1 and HT22 cells was attenuated by catalase and L-NNMA, indicating a role for H2O2 and NO as mediators of cytotoxicity. Dexamethasone-induced apoptosis was associated with H2O2 generation in both cell lines and it was attenuated during co-incubation with catalase. These data indicate that co-exposure to F and Dex amplifies their respective cytotoxicity in H2O2- and NO-dependent manner. As flavonoid fisetin prevented F- and Dex-induced cytotoxicity the potential role of this product in pharmacology and diet may be considered., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Oxidative damage to cellular components such as lipids and cell membranes by free radicals and other reactive oxygen species is believed to be associated with the development of degenerative diseases. Fluoride intoxication is associated with oxidative stress and altered anti-oxidant defense mechanism. So the present study was extended to investigate black berry anti-oxidant capacity towards superoxide anion radicals, hydroxyl radicals and nitrite in different organs of fluoride-intoxicated rats. The data indicated that sodium fluoride (10.3mg/kg bw) administration induced oxidative stress as evidenced by elevated levels of lipid peroxidation and nitric oxide in red blood cells, kidney, testis and brain tissues. Moreover, significantly decreased glutathione level, total anti-oxidant capacity and superoxide dismutase activity were observed in the examined tissues. On the other hand, the induced oxidative stress and the alterations in anti-oxidant system were normalized by the oral administration of black berry juice (1.6g/kg bw). Therefore it can be concluded that black berry administration could minimize the toxic effects of fluoride indicating its free radical-scavenging and potent anti-oxidant activities., (Published by Elsevier Ltd.)

Fluoride (F) becomes toxic at higher doses and induces some adverse effects on various organs, including brain. The mechanisms underlying the neurotoxicity caused by excess fluoride still remain unknown. The aims of this study were to examine F-induced oxidative stress (OS) and role of melatonin (MEL) and buffalo pineal proteins (PP) against possible F-induced OS in brain of rats. The 24 rats were taken in present study and were divided into four groups: control, F, F + PP, and F + MEL. The F group was given 150 mg/L orally for 28 days. Combined 150 ppm F and 100 microg/kg BW (i.p.) PP and F (150 ppm) + MEL (10 mg/kg BW, i.p.) were also administered. The activities of enzymatic, viz., superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione reductase (GR), and non-enzymatic, viz., reduced glutathione (GSH) concentration, and the levels of malondialdehyde (MDA) in the brain tissue were measured to assess the OS. Fluoride administration significantly increased brain MDA compared with control group, while GSH levels were decreased in fluoride-treated groups, accompanied by the markedly reduced SOD, GPx, GR, and SOD activity. Buffalo PP and MEL administration caused brain MDA to decrease but caused SOD, GPx, GR, GSH, and CAT activities to increase to significant levels in F-treated animals. Together, our data provide direct evidence that buffalo PP and MEL may protect fluoride-induced OS in brain of rats through mechanisms involving enhancement of enzymatic and non-enzymatic antioxidant defense system. Therefore, this study suggested that PP and MEL can be useful in control of neurotoxicity induced by fluoride.

We report on the fluorinated form of Cpd 5 as a cell growth inhibitor. This compound is 3-fold more potent than the parent Cpd 5 and is predicted, using the semi-empirical AM1 method to be only an arylator of cysteine-containing proteins, without generating reactive oxygen species.

Purpose: High-fluoride drinking water represents a health hazard to millions of people, not least in the East African Rift Valley. The aim of the present project was to establish a simple method for removing excessive fluoride from water., Material and Methods: Based on geological maps and previous experience, 22 soil samples were selected in mountainous areas in central Ethiopia. Two experiments were performed: 1. After sieving and drying, two portions of 50 g were prepared from each soil and subsequently mixed with solutions of NaF (500 mL). Aliquots (5 mL) of the solutions were taken at pre-set intervals of 1 hour to 30 days for fluoride analysis--using an F-selective electrode. 2. After the termination of the 30-days test, liquids were decanted and the two soil samples that had most effectively removed fluoride from the NaF solutions were dried, and subsequently exposed to 500 mL aqua destillata. The possible F-release into the distilled water was assessed regularly., Results: Great variations in fluoride binding patterns were observed in the different soils. The percent change in F-concentration in the solutions, as compared to the original absolute value(F-), varied: at 1 hour from a decrease of 58% to an actual increase of 7.7%, while--at 30 days--all soil samples had caused a decrease in the F-concentration, varying from 0.5% to 98.5%. Only minute amounts of fluoride would leach from the fluoride-enriched soils., Conclusion: Lateritic soils may remove excessive fluoride from drinking water. Methods for practical application of this principle should be tested at household level.

The objective of the present communication is to address the issues concerning reversal of fluoride induced cell injury and disease (i.e. fluorosis) through the elimination of fluoride and consumption of a diet containing essential nutrients and antioxidants. Humans afflicted with fluorosis, as a result of consuming fluoride contaminated water or food, have been investigated. Hospital based diagnostic procedure for early detection of fluorosis, through retrieval of history, clinical complaints, testing of blood, urine and drinking water for fluoride using ion selective electrode technology, along with X-ray of the forearm have been carried out. Confirmed cases of fluorosis were introduced to an intervention protocol consisting of (1) provision of safe drinking water with fluoride levels less than 1 mg/L and (2) counselling on nutritional supplementation with focus on adequate intake of calcium, vitamins C, E and antioxidants. The patients were monitored at frequent intervals up to one year and the results are reported. With a standardized early diagnosis, elimination of fluoride intake and supplementation of a diet rich in essential nutrients and antioxidants, we have shown that the fluorosis can be reversed.

In order to study the metabolism of preventive anti-fluorine agent, 30 rats are randomly divided into high-dose, low-dose and a control groups. The high dose (400 mg/kg.d) and low dose (16 mg/kg.d) are orally administrated respectively, and the content of boron and/or zinc in urine, dung, serum, bone, liver, muscles, brain tissues is determined. The results showed that during the administration of this agent, the content of boron in urine and the content of zinc in dung increases obviously in both high-dose and low-dose groups and their discharge rate is consistent with the dose given. The content of boron and zinc in bone, liver, and zinc in serum, muscles, brain tissues increases evidently compared to that in control group but decreases rapidly after administration of the agent. The findings revealed that there is a rapid metabolism of boron and zinc in the body of rats. The highest content of the agent is observed in bones. The content ranks second in liver and muscles but no accumulative effects are observed.

Hydroxyapatite as a defluoridator for drinking water is characterized by a large capacity of defluoridation, and easy and simple operation in application. The quality of drinking water is not changed, the sorbent is easy to be regenerated, and the second pollution does not occur after the treatment of drinking water with the sorbent. Hydroxyapatite method has advantage over the methods such as actived alumina, bone char and electrodialysis commonly used in defluorination of drinking water. It is for this reason that the components, structural feature, synthesis and application of hydroxyapatite and its mechanism of defluoridation are summarized in this paper.

We have evaluated the ameliorative effect of vitamin D on fluoride-induced embryotoxicity in pregnant rats. Oral administration of sodium fluoride (NaF; 40 mg/kg body weight) from days 6 to 19 of gestation caused, as compared with control, significantly lowered body weight, feed consumption, absolute uterine weight and number of implantations. As compared with the control, higher incidence of skeletal (presence of wavy ribs, 14th rib, dumbbell-shaped 5th sternebrae, incomplete ossification of skull) and visceral (subcutaneous haemorrhage) abnormalities was recorded in the foetuses of fluoride-treated pregnant rat. Vitamin D (2 ng/0.2 ml olive oil/animal/day po) treatment significantly ameliorated the fluoride-induced reductions in body weight, feed consumption and absolute uterine weight. As compared with fluoride-treated alone, the total percentage of skeletal and visceral abnormalities observed in foetuses was significantly lowered in fluoride plus vitamin D-treated animals. These findings suggest that vitamin D treatment significantly reduced the severity and incidence of fluoride-induced embryotoxicity. The ameliorative effect of vitamin D against skeletal and visceral abnormalities could be due to stimulation of intestinal absorption of calcium and phosphate, thus raising the plasma calcium and phosphate concentrations.

Objectives: Acute systemic fluoride poisoning can result in systemic hypocalcemia, cardiac dysrhythmias, and cardiovascular collapse. Topical and intraarterial therapy with calcium or magnesium salts reduces dermal injury from fluoride burns. The mechanism of these therapies is to bind and inactivate the fluoride ion. The purpose of this study is to evaluate the effect of calcium and magnesium to decrease the bioavailability of fluoride in a lethal model of fluoride poisoning., Methods: In preliminary studies, we determined that fluoride 3.6 mM/kg intraperitoneally in the form of sodium fluoride was uniformly and rapidly fatal in a mouse model. Using this fluoride dose, we performed a controlled, randomized, blinded study of low- and high-dose calcium chloride (1.8 and 3.6 mM/kg intraperitoneally, respectively) and magnesium sulfate (3.6 mM/kg intraperitoneally) to decrease the bioavailability of the fluoride ion. After injection with sodium fluoride, animals were immediately treated with injections of sodium chloride (control), calcium chloride (low- or high-dose), or magnesium sulfate. The major outcome was 6-hour survival using a Cox Proportional Hazard model., Results: All untreated animals died within 60 minutes. Using a Cox Proportional Hazard model, each 1.8 mM/kg dose of calcium chloride administered reduced the risk of death by 33%. Magnesium sulfate treatment was not associated with a hazard reduction., Conclusion: Calcium chloride administered simultaneously with sodium fluoride reduces the bioavailability of fluoride poisoning in a mouse model. The equivalent dose of magnesium sulfate does not significantly decrease fluoride bioavailability.

Objective: Results from previous studies have shown that pre- and perinatal exposure to lead enhances susceptibility of rats to development of dental caries. A possible explanation for this phenomenon may be that lead complexes with fluoride and renders F insoluble and unable to exert its cariostatic effects., Materials and Methods: Thus, to explore this hypothesis, 48 desalivated Sprague-Dawley rats were placed in a König-Höfer programmed feeder and received 17 meals of powdered sucrose daily, and water ad libitum as follows: group (1) plain sucrose and sterile distilled water (SDW); (2) sucrose containing 15 ppm F and SDW; (3) sucrose containing 15 ppm F and 10 ppm Pb water; (4) sucrose containing 15 ppm F and 25 ppm Pb water., Results: The highest smooth-surface, sulcal surface caries and severity scores were observed in group I. Animals that were exposed to fluoride showed reduced smooth-surface caries and severity scores. S. sobrinus counts did not differ among the groups., Conclusion: Lead did not interfere with the protective effect of fluoride in the conditions of the present study.

In papillary muscles, carbachol reduced the positive inotropic effects of isoprenaline (10 nmol/l). The negative inotropic effects of carbachol in isoprenaline-stimulated guinea pig papillary muscles were attenuated by additionally applied sodium fluoride (3 mmol/l). These effects of sodium fluoride were blocked by deferoxamine (200 micromol/l). In guinea pig left atria, sodium fluoride alone greatly reduced force of contraction. These effects in atria were blocked by 200 micromol/l deferoxamine, and positive inotropic effects of sodium fluoride were observed. It is suggested that the cardiac effects of muscarinic M2 receptor agonists in the ventricle involve, at least in part, the activation of phosphatases which are blocked by fluoride and reactivated by deferoxamine.

Five groups of SD male rats were provided with deionized drinking water containing 0 and 150 mg/L NaF, and containing both 150 mg/L NaF and 0.5, 2.0 or 4.0 mg/L Na2SeO3 respectively for 10 weeks, in order to find out the optimal level of selenite in drinking water against fluoride toxicity. The results showed that fluoride could cause significant increase of lipid peroxides (LPO) and metabolic disorder of trace elements in the serum and kidney of rats. The antagonistic effect of 2.0 mg/L Na2SeO3 drinking water on the lipid peroxidation induced by 150 mg/LNaF was the most evident, whereas those of 0.5 and 4.0 mg/L Na2SeO3 were not obvious. It is concluded that selenite possesses significant antagonistic effects on renal damages induced by fluoride and 2.0 mg/L Na2SeO3 is the optimal concentration for the antagonistic effect on renal impairments induced by 150 mg/L NaF in drinking water.

2 groups of Wistar rats with chronic fluorosis were duplicated with 30 and 50 mg/L fluorine (F) in drinking water. 2. 0 mg/kg selenium (Se) in fodder was supplemented in the other 2 groups of rats with fluorosis. The amount of drinking water and diet, the excretion of urine and the contents of urine F were tendentiously surveyed every month in one year and then, intake and excretion of F were calculated per day. The contents of Se in urine, liver and serum and F in bone, liver, kidney and serum were measured in the 4th, 8th, and 14th month. The results showed that F absorption increased and F excretion/F absorption rate decreased in 2 groups of rats with fluorosis compared with control group and there were positive correlations between concentration of urine F and water F, as well as concentration of F urine and time of drinking F water. The accumulation of F in bone and liver occurred in the middle period of fluorosis and then, the increase of serum F was observed in the late period of fluorosis in 2 groups of rats with fluorosis. After supplement of Se, urine, liver and serum Se ascended. At the same time, state of eating and drinking improved, the weight rose and the amount of urine excretion heightened, as well as there was an increase of urine F and excretion F/absorption F rate and there was a decrease of bone, live, kidney and serum F in rat of Se supplementation with fluorosis compared with non-Se groups.

Although an excess intake of fluoride has been reported to cause skeletal fluorosis, very little is known about the mechanism of adverse effects of fluoride on bone. In the present study cytotoxic effects of fluoride were studied using the osteosarcoma cell line, UMR 106. The DNA ladder formation upon agarose electrophoresis and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) staining revealed that UMR 106 underwent apoptosis following exposure to 5 mM fluoride for 8 h. On the other hand exposure to A23187, a calcium ionophore, caused necrosis while co-exposure to fluoride and A23187 inhibited fluoride-mediated apoptosis in UMR 106. The proliferation of UMR 106 cells cultured for 6 days in the presence of 0.5 mM fluoride was significantly decreased compared to the control culture. The cytotoxic effects of fluoride were modulated by both the cell density and the pH of the culture medium. The fluoride-induced viability loss in UMR 106 was enhanced in culture of high cell-density and inversely correlated with pH of the culture medium. Enhancement of fluoride cytotoxicity at acidic pH was also observed in rat alveolar macrophages and RAW 264, a macrophage cell line. The results suggest that fluoride-mediated apoptosis and culture conditions, including pH of the medium, should be taken into consideration to evaluate toxicity of fluoride in vitro.

These studies sought to determine the effects of neomycin, a phospholipase C inhibitor, on hormone-stimulated myometrial contractions. For these studies, computer digitalized in vitro isometric contraction data were analyzed for changes in contractile activity in response to oxytocin and aluminum fluoride with and without neomycin. Neomycin (1-5 mM) produced dose-related inhibition of oxytocin and aluminum fluoride-stimulated myometrial contractions. This neomycin effect was apparent within 2-3 minutes of addition and was completely reversible, with resolution of its inhibitory effects within 6-8 minutes of washout. This study is the first to demonstrate the functional effect of neomycin inhibition of the phosphatidylinositol signaling pathway in myometrial smooth muscle tissue.

We investigated the mechanism by which the G-protein activators aluminium fluoride and vanadate stimulate arachidonic acid release in pig aortic endothelial cells. Our previous study demonstrated a novel Ca(2+)-independent pathway of phospholipase A2 (PLA2) activation stimulated by aluminium fluoride in this model. In the present study, we found that sodium metavanadate stimulated a rapid concentration-dependent release of [3H]arachidonic acid from prelabelled cells. A more than 3-fold enhancement of arachidonic acid release was achieved in cells treated with 1 mM vanadate for 20 min. Synthesis of prostaglandin products was similarly enhanced. The release of arachidonic acid was not dependent on the presence of extracellular Ca2+, but did require protein synthesis de novo. Both cycloheximide and actinomycin D completely blocked aluminium fluoride- and vanadate-stimulated arachidonic acid release. Because fluoride and vanadate are known protein tyrosine phosphatase inhibitors, it is possible that PLA2 activation occurred secondarily to changes in protein tyrosine phosphorylation. Both aluminium fluoride and vanadate stimulated the rapid phosphorylation of 58, 93 and 120 kDa tyrosine-containing protein substrates. However, in contrast with arachidonic acid release, this response was found to be sensitive to the presence of extracellular Ca2+ and insensitive to blockers of protein synthesis de novo. Furthermore H2O2 treatment resulted in rapid tyrosine phosphorylation of the same substrates without a concomitant increase in arachidonic acid release. These results suggest that the effects of aluminium fluoride and vanadate on PLA2 are not due to changes in protein tyrosine phosphorylation, but do require rapid protein synthesis de novo.

This in vitro study evaluated the effect of Plax prebrushing rinse on fluoride uptake by enamel from sodium fluoride (NaF) and sodium monofluorophosphate (MFP) solutions in the presence and in the absence of saliva. Human enamel powder (particle size between 0.074 and 0.149 mm), pretreated or not with Plax, was exposed to aqueous solution of 250 ppm F as either NaF or MFP. The exposure time was 1 minute followed by washing in deionized water and methanol. The amounts of alkali-soluble fluoride (CaF2) and firmly bound fluoride (FBF) on enamel were determined with a specific electrode and statistically analyzed with ANOVA. Plax reduced the formation of both CaF2 and FBF on enamel whether the F was supplied as NaF or MFP. The percentage inhibition of uptake from NaF was increased and that from MFP was decreased by the presence of saliva. The commercial prebrushing rinse formulation tested inhibits in vitro the reactivity of the fluoride with enamel.

Objective: The mechanisms underlying phasic myometrial contractions are unknown at this time. Phasic contractions, however, are characterized by repetitive cycles of elevated intracellular calcium (i.e., calcium oscillations). These studies were performed to test the hypothesis that mechanisms underlying phasic myometrial contractions are similar to those producing classic cytosolic calcium oscillations., Study Design: Uterine tissue was obtained from pregnant Sprague-Dawley rats (i.e., day 18 to 22 of gestation). In vitro isometric contraction studies were performed with longitudinal strips of myometrial tissue; computer-digitized data were analyzed for contraction area and normalized for tissue cross-section area. Dose-response studies were performed with aluminum fluoride and various inhibitors of cytosolic calcium oscillations., Results: Aluminum fluoride stimulated a significant increase in phasic contractions. In contrast, the addition of 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (an inhibitor of phosphoinositide-specific phospholipase C), adenine (an inhibitor of calcium-induced calcium release), and phorbol 12,13-dibutyrate (an activator of protein kinase C) resulted in significant suppression of aluminum fluoride-stimulated contractions. Similarly, nifedipine (an L-type calcium channel blocker) and removal of extracellular calcium significantly inhibited phasic myometrial contractions., Conclusions: These studies have confirmed that phosphoinositide-specific phospholipase C, calcium-induced calcium release, protein kinase C, and transmembrane calcium influx are important components of the intracellular calcium oscillator that generates agonist-stimulated phasic contractions of pregnant myometrial tissue.

Quercitin and Cernitin are not in themselves toxic to rats. When administered at the time of intoxication of the animals with ammonium fluoride, they reduced the noxious effects of the toxic agent in the liver and lungs. It is suggested that Quercitin and Cernitin might play a protective role during prolonged exposure to ammonium fluoride. Neither ammonium fluoride nor Quercitin or Cernitin seem to exert any effect on the stomach.

We demonstrate here the correlation between protection afforded by pretreatment alone with parathion hydrolase purified from Pseudomonas sp. against tabun toxicity in mice and the kinetic parameters which are assumed to determine the in vivo detoxification of tabun by the same enzyme. Results show that 15 and 22 micrograms of parathion hydrolase per animal conferred a protective ratio of 3.94 and 5.65 respectively, against tabun toxicity, without post-exposure treatment.

The joint actions were assessed by four methods after male Wistar rats had been acutely intoxicated with nine proportional mixtures of Al and F. Strong antagonistic effects of Al on F were observed in the mixtures, in which the ratio of Al to F ranged from 0.8:0.2 to 0.1:0.9. The optimum ratio of Al to F for antagonism ranged from 0.3:0.7 to 0.1:0.9 without periorbital bleeding that was a regular finding in Al acute toxicity on the rat to be seen. When the amount of Al in the mixture was below 5% or above 90%, no antagonistic effect was shown. The kinetics on the absorption under the condition of Al and F existing simultaneously is still unknown, and warrants further investigation.

We examined the effect of fluoride (F) on intracellular ionic calcium [Ca2+]i in normal human osteoblasts maintained in culture. Cells were grown on glass coverslips to near-confluency and loaded with the Ca-sensitive dye, fura-2AM. Fluorescence changes were monitored in single cells using an inverted microscope coupled by fiberoptic to a microspectrofluorometer. The addition of F (100 ng/mL) to the medium promoted a rapid and significant increase in free [Ca2+]i from a resting level of 245 +/- 36 SE nM to a peak concentration of 440 +/- 51 nM (p less than 0.04). This increase in [Ca2+]i began at 10-20 s after addition of F and was maximal by 30 s. Intracellular [Ca2+]i levels then returned to near resting values by 60-80 s after F addition. This response was evident with as little as 25 ng/ml of fluoride and was dose dependent up to 500 ng/ml. At concentrations greater than 500 ng/ml, there appeared to be an attenuation of the rise in [Ca2+]i. The observed rise in [Ca2+]i was dependent on extracellular calcium since lowering extracellular calcium concentration or incubation with calcium channel blockers abolished the response. This observation supports a role of increased [Ca2+]i as one of the initial events of fluoride on action osteoblasts.

The presence of adenylate cyclase (AC) in liver Golgi and microsomal fractions from ethanol-treated rats was tested cytochemically using 5'-adenylyl imidodiphosphate (AMP-PNP) lead phosphate method. Parallel biochemical assays showed that rat liver Golgi AC was only partially inhibited by lead: in the presence of 1 mM Pb++ 80% of the enzyme was preserved, while when 2 mM Pb++ was used 25% remained. No cAMP was formed when the AMP-PNP medium was incubated in the presence of 1 or 2 mM Pb++ but in the absence of cell fractions, indicating that at these concentrations Pb++ does not cause the nonenzymatic hydrolysis of AMP-PNP. Therefore, the reaction product observed by cytochemical localization is not due to the nonenzymatic hydrolysis of AMP-PNP by Pb++. In Golgi subfractions, lead phosphate reaction product was widely distributed among Golgi elements: it was seen in association with the majority of the very low density lipoprotein-filled secretory droplets which predominated in the two lightest Golgi fractions (GF1 and GF2) as well as within the majority of the cisternae found in the heaviest Golgi fraction (GF3). In the latter, reaction product was heaviest along the dilated peripheral rims of the cisternae. In all cases, the reaction product was localized to the outside or cytoplasmic face of the Golgi membranes. When microsomes were incubated cytochemically for AC, deposits were found on the cytoplasmic surface of smooth endoplasmic reticulum (ER) membranes, but none were observed on rough ER membranes. The results confirm the biochemical data reported previously indicating the presence of AC in Golgi and smooth microsomal fractions from rat liver and further demonstrate that the activity is indeed indigenous to Golgi elements and not due to plasma membrane contaminants. They also indicate that AC is widely distributed among Golgi and smooth ER elements. Thus, AC is not restricted in its distribution to plasma membranes as usually assumed.

Uptake of cadmium into molar enamel and dentin from rats receiving cadmium in their drinking water was markedly elevated and proportional to the amount of cadmium in the drinking water. Post-developmental cadmium did not influence caries development or alter the cariostatic effectiveness of fluoridated drinking water. The data indicate that the absolute concentration of cadmium in teeth is not predictive or cadmium-induced caries and that the critical period for caries promotion by cadmium may be during the developmental rather than the post-developmental period of tooth formation.

Although muscle cell fusion was shown to be an energy-requiring process, release of myoblasts from an EGTA fusion block could be accomplished with Earle's balanced salt solution (containing 1.8 mM Ca++) free of glucose or any other energy-produced metabolite. The effect of concanavalin A, abrin, and the lectins from wheat germ, soybean, and Lens culinaris on myoblast fusion was examined with synchronized myoblast cultures upon release from fusion block. At a concentration of 15 mug/ml, these lectins were found to inhibit the fusion process to the extent of 62%, 41%, 32%, 8%, and 19%, respectively. Concanavalin A inhibition could be prevented by alpha-methyl-D-mannoside. The inhibitory effect of all the lectins except abrin could be reversed by changing to the normal, serum-containing medium. The number of binding sites was 3.4 X 10(7), 6.1 X 10(7), and 1.7 X 10(6), respectively. Although myoblasts were found to have about twice as many binding sites for wheat germ agglutinin as for concanavalin A, concanavalin A was determined to be twice as effective as wheat germ agglutinin as an inhibitor of myoblast fusion. These findngs raise the possibility that specific cell surface glycoproteins may be an important factor in this process.

Injection of PGF2 alpha (250 microgram/rat) 15 min prior to isolation of corpora lutea (CL) from PMSG treated immature rats significantly reduced the LH stimulation of adenylate cyclase in CL membranes. The LH stimulation did not return to normal even 24 h after PGF2 alpha injection. A transient decrease in epinephrine and fluoride stimulation of AC was also observed, the response returning to normal 6-12 h after PGF2 alpha treatment. In vitro incubation of whole isolated CL with 0.005 micrometer or higher concentrations of PGF2 alpha markedly reduced the LH and fluoride stimulation of AC in the CL membranes. Exposure of CL to PGF2 alpha for 15 min in vitro reduced the LH and fluoride response. The results are discussed in relation to the suppressive action of PGF2 alpha on LH receptors in CL, and a mechanism is proposed to explain the discrepancy in time relation between our results and the LH receptor studies. The proposed mechanism might also explain the transient decrease in epinephrine and fluoride stimulation of AC.

Exogenous sialic acid at 3 mM and higher concentrations inhibits the basal adenylate cyclase activity and the activity stimulated by thyrotropin (TSH) and fluoride in the human thyroid membrane fraction; 30 mM-sialic acid acts as an inhibitor of TSH binding. The decrease of these activities at high sialic acid concentrations might be ascribed to changes in membrane conformation caused by acidic character of this sugar.

Increased sensitivity to succylcholine may be due to inherited variants of serum cholinesterase (acylcholine-acylhydrolase, E.C.3.1.1.8). Four different allelic genes at locus E1 controlling human serum cholinesterase have been identified: the normal gene Eu1, the atypical gene Ea1, the fluoride-resistant gene Ef1, and the silent gene Es1. These 4 genes give rise to 10 possible genotype combinations. The sensitivity of some of these genotypes to succinylcholine, as, for instance, homozygotes for the atypical enzyme Ea1 Ea1, is well documented. However, the relation between some of the rarer genotypes and the sensitivity to succinylcholine is less well clarified. The present report represents the 1st case in which a peripheral nerve stimulator has been used to substantiate the increased succinylcholine sensitivity of a patient heterozygous for the silent and the fluoride-resistant gene, and the 2nd published case of prolonged apnea following succinylcholine in a patient carrying the Ef1 Es1 genotype for abnormal serum cholinesterase.

On isolated coronary arteries of cattle, nitroprusside-sodium, nitroglycerol, prenylamine, and verapamil were studied for their spasmolytic effects on a contracture induced by fluoride ions. With this contracture model, which is independent of extracellular calcium, nitroprosside-sodium and nitroglycerol showed strong spasmolytic action. Verapamil proved ineffective, and the effectiveness of prenylamine was strongly reduced. The results lend support to earlier findings suggesting that nitroglycerol and nitroprusside-sodium are endowed with a relaxation mechanism different from that of verapamil and analogously acting compounds.

Whether the interference by fluoride (F-) with secretory amelogenesis in vitro could be modulated by altering the levels of calcium (Ca) and inorganic phosphate (P) in the medium was investigated. Hamster first upper molar tooth germs in the secretory phase of amelogenesis were exposed to 10 microM-1.31 mM (0.2-25 parts/10(6)) of F- in vitro for 2 days in the presence of either low (1.2 mM), moderate (2.1 mM) or high (4.1 mM) levels of Ca, or moderate (1.6 mM) and high (3.6 mM) levels of P. The biosynthesis and secretion of enamel matrix proteins under each of the experimental conditions were examined by labelling with [3H]-proline during the last 24 h of culture, and mineralization by labelling with 45Ca and [32P]-orthophosphate. With moderate levels of Ca and P (control medium), F- increased the uptake of 45Ca and 32P in a dose-dependent manner; F- did not inhibit the synthesis of matrix proteins but to a moderate extent impaired their secretion. In explants grown in the presence of 52 microM of F- the superficial layers of enamel matrix deposited in vitro (fluorotic matrix) failed to mineralize. Increasing P levels in the medium had no clear histological effect, whereas lowering Ca levels sometimes seemed to aggravate the F- effect. Raising Ca levels improved the histological pattern: in spite of the presence of F-, high Ca levels allowed a limited mineralization of the superficial layer of fluorotic matrix along with a strong rise in mineralization of the deeper layers of pre-exposure enamel. High Ca levels also considerably reduced the cellular changes in secretory ameloblasts induced by 52 microM of F- and slightly counteracted the inhibition of matrix secretion, as measured biochemically. Some of the effects of F- on secretory amelogenesis in vitro can thus be reversed by raising Ca levels in the medium. Therefore, the effect of F- on secretory amelogenesis in vitro seems to be primarily interference with the enamel mineralization process per se and, secondarily, an impairment of matrix secretion.

Platelet activation (cytosolic [Ca2+] increase, aggregation and ATP secretion) was induced with A1F-4. This agent presumably interacts with a G protein which appears to mediate the coupling of the receptors for Ca mobilizing hormones and phospholipase C. All the A1F-4 evoked responses were inhibited by treatment with forskolin or prostacyclin, agents known to increase cellular cAMP. Thus the G protein-phospholipase C system appears to be the site of cAMP inhibition. Unexpectedly forskolin and prostacyclin also inhibited secretion and aggregation induced by the activators of protein kinase C, diglyceride and phorbol ester, suggesting that cAMP can also inhibit directly the protein kinase C dependent responses.

Manganese stimulated the utilization of glucose by Streptococcus mutans, Streptococcus sanguis, Streptococcus mitior and Streptococcus milleri. S. mutans serotype c strains formed larger amounts of intracellular polysaccharide, lactic acid and produced a lower terminal pH in glucose broth when grown in the presence of 0.5 mM Mn. Manganese stimulated the utilization of glucose by resting cell suspensions of each of the four oral streptococcal species examined. Fluoride inhibited the utilization of glucose by the streptococci and Mn, but not calcium or magnesium, was found to counteract the inhibitory effect of fluoride.

The effect of chloroquine and hydroxychloroquine on human neutrophil polymorph superoxide (O2-) production stimulated either by opsonized zymosan, phorbol myristate acetate or fluoride was examined in vitro. Both drugs inhibited the response to all 3 stimuli in a dose and time dependent fashion. Inhibition of zymosan stimulated O2- release was only attributable in a minor degree to inhibition of expression of surface receptors (MO-1), and appeared to be mainly due to inhibitory effects on more distal components of the activation pathway. Possible mechanisms for the inhibition of fluoride and phorbol ester stimulated O2- release are discussed in the light of current understanding of metabolic pathways of neutrophil polymorph activation.

The secondary hyperparathyroidism in uremic patients is due to the modification plasma electrolyte concentrations accompanied by a renal resistance to PTH action. We postulate that the retention of a uremic toxin could be at least partly responsible for this resistance. We have tested this hypothesis "in vitro" by measuring the action of Middle Molecules on the adenylate cyclase activity stimulated by NaF, PTH and isoproterenol.

The paper described the results of experiment performed on animals concerning the effect of fluoride tooth-pastes on a calcium-phosphate and sodium-phophate basis in the field of caries prevention. The caries infection is ascertained for varying test durations on the basis of serial grindings. It turns out that the anti-carieseffect of fluoride is greatly diminished if soluble calcium salts are present in the paste.

1. Renal tubular membranes from rat kidneys were prepared, and adenylate cyclase activity was measured under basal conditions, after stimulation by NaF or salmon calcitonin. Apparent Km value of the enzyme for hormone-linked receptor was close to 1 x 10(-8) M. 2. The system was sensitive to temperature and pH. pH was found to act both on affinity for salmon calcitonin-linked receptor and maximum stimulation, suggesting an effect of pH on hormone-receptor binding and on a subsequent step. 3. KCl was without effect areas whereas CoCl and CaCl2 above 100 muM and MnCl2 above 1 muM inhibited F- -and salmon calcitonin-sensitive adenylate cyclase activities. The Ca2+ inhibition of the response reflected a fall in maximum stimulation and not a loss of affinity of salmon calcitonin-linked receptor for the enzyme. 4. The measurement of salmon calcitonin-sensitive adenylate cyclase activity as a function of ATP concentration showed that the hormone increases the maximum velocity of the adenylate cyclase. GTP, ITP and XTP at 200 muM did not modify basal, salmon calcitonin- and parathyroid hormone-sensitive adenylate cyclase activities. 5. Basal, salmon calcitonin- and F- -sensitive adenylate cyclase activities decreased at Mg2+ concentrations below 10 mM. High concentrations of Mg2+ (100 mM) led to an inhibition of the F- -stimulated enzyme. 6. Salmon calcitonin-linked receptor had a greater affinity for adenylate cyclase than human or porcine calcitonin-linked receptors. There was no additive effect of these three calcitonin peptides whereas parathyroid hormone added to salmon calcitonin increased adenylate cyclase activity, thus showing that both hormones bound to different membrane receptors. Human calcitonin fragments had no effect on adenylate cyclase activity. 7. Salmon calcitonin-stimulated adenylate cyclase activity decreased with the preincubation time. This was due to progressive degradation of the hormone and not to the rate of binding to membrane receptors.