Effects of sevoflurane anesthesia on plasma inorganic fluoride concentrations during and after cardiac surgery

Purpose. Sevoflurane metabolism results in the production of inorganic fluoride, which is known to be nephrotoxic. Since marked changes in body temperature and hemodynamics in cardiac surgery affect sevoflurane metabolism, plasma inorganic fluoride concentrations may differ in this situation compared with other types of surgery. We therefore measured plasma inorganic fluoride concentrations during and after sevoflurane anesthesia in patients undergoing cardiac surgery. Methods. Sixteen patients undergoing coronary artery bypass grafting or valve replacement were premedicated with 5–10 mg midazolam and 0.5 mg scopolamine injected intramuscularly. Anesthesia was induced with 5–10 mg midazolam, 0.5–1 mg fentanyl, and 0.12–0.15 mg·kg⁻¹ vecuronium. Following tracheal intubation, anesthesia was maintained with oxygen, sevoflurane, and fentanyl. At the onset of cardiopulmonary bypass (CPB), sevoflurane was discontinued, and additional fentanyl, midazolam, and pancuronium were administered. Plasma inorganic fluoride concentrations were measured before anesthesia, immediately before and after CPB, and at 0, 2, 6, 12, 24, and 48 h after anesthesia. Results. The individual maximum plasma inorganic fluoride concentration was 19.2 ± 7.2 μmol·l⁻¹ (mean ± SD; range, 9.2–36.7). The mean plasma inorganic fluoride concentrations increased during anesthesia, but the rate of increase decreased after the initiation of CPB. Concentrations peaked at 2 h after anesthesia and decreased thereafter. The concentrations in three cases continued to increase 2 h after anesthesia. Conclusion. The plasma inorganic fluoride concentrations observed in patients undergoing cardiac surgery were below nephrotoxic levels. However, the decrease in mean fluoride concentration after anesthesia was slower than that in the previous study in general surgical patients. Received for publication on December 4, 1998; accepted on April 25, 1999     

A comparison of some effects of fluoride on apatite formationin vitro andin vivo

Summary In a liquid (22°C) saturated with and in contact with powdered bone apatite, the fluoride ion activity was adjusted to 1–10 parts/10⁶. Due to the fluorapatite (FAP) supersaturation produced hereby, a rapid formation of this salt occurred leading to a decrease of the concentration of the ions involved. When no more fluoride was available in the liquid, the concentrations of calcium and phosphate increased again, due to dissolution of presumeably hydroxyapatite (HAP). Fifty four rats were given either 10, 20, or 40 mg NaF per kg body weight intraperitoneally. The animals were sacrificed from 5 min to 96 h after the injection. The fluoride concentration in plasma increased to a peak, after which it decreased. Plasma calcium decreased and remained low until the fluoride had attained normal levels. The intensity of mineralization of the growing dental hard tissue was monitored on microradiographs. Corresponding to the plasma fluoride peak and the decrease of plasma calcium, a hypermineralized layer was formed while a hypomineralized zone was formed during plasma calcium increase after disappearance of fluoride. Similarities and dissimilarities between thein vitro and thein vivo experiments are discussed.     

Increased fluoride uptake in human dental specimens treated with diode laser

The hypothesis of this study was the fact that diode lasers can increase the fluoride uptake in dental structures. The main objectives were: (1) to evaluate the effect of diode laser–NaF varnish combination on binding fluoride to dental enamel in an in vitro model and (2) to analyse outer enamel surface changes produced by the laser energy. After NaF enamel varnish and laser irradiation at different levels of energy, specimen surfaces were examined by environmental scanning electron microscopy. The incorporation of F⁻ ion into the dental structure was quantitatively determined by using a fluoride ion-selective electrode. Results showed that the laser treatment significantly increased the binding of fluoride to the enamel surface without damaging it. The amount of F⁻ estimated was 37 ± 7 mg/l to the power of 5 W and 58 ± 12 mg/l to the power of 7 W. These increases were significantly greater than the ones achieved by conventional topical fluoridation. The results were analysed and compared by Kruskal–Wallis and Dunn’s multiple comparison tests, and significant statistical differences were found. These suggest that the NaF varnish–diode laser combination may be a useful option for the effective fluoridation of teeth.     

Effects of biogenic amines and intravenous anesthetics on the activity of rat locus coeruleus neurons in vitro

To examine the effects of biogenic amines and clinically relevant concentrations of intravenous anesthetics on neuronal activities, the authors analyzed both spontaneous and evoked activities of neurons in the nucleus locus coeruleus (LC)in vitro using a single unit recording technique. Spontaneous firing was observed in 37% (14/38) of LC neurons, andN-methyl-d-aspartate (NMDA, 50 μM), glutamate (250 μM), and carbachol (1–2 mM) elicited firing in 100% (38/38), 63% (12/19), and 58% (7/12) of silent LC neurons respectively. Noradrenaline (50 μM) and serotonin (5-HT) (1–5 μM) suppressed spontaneous and drug-induced activities in 47% (15/32) and 23% (8/35) of LC neurons, respectively. Pentobarbital (100 μM) inhibited 50% (5/10) of LC neurons. All neurons activated by NMDA (n=8) and glutamate (n−3) were suppressed by ketamine (40 μM), but fentanyl (1 μM) only suppressed 60% (3/5) of spontaneously active and 75% (3/4) of glutamate-activated neurons. Identical LC neurons were inhibited by various combinations of noradrenaline, 5-HT, pentobarbital, ketamine, and fentanyl. The results suggest that clinically relevant concentrations of anesthetics and opioids modulate the activity of LC neurons induced by biogenic amines, excitatory amino acids, and acetylcholine.     

Optical fibre delivery and tissue ablation studies using a pulsed hydrogen fluoride laser

We describe an experimental study of the transmission of pulsed, multiline (2.67–2.95 μm) hydrogen fluoride (HF) laser radiation in a fluoride glass fibre. For a 400 ns full-width at half-maximum (fwhm) duration laser pulse transmission measurements and photoacoustic techniques show that non-linear loss at the fibre input surface appears to set a maximum useful input fluence of ∼15 J cm⁻² for the 500 μm core diameter fibre used. However, with modest length fibres, exit fluence levels adequate for the ablation of soft tissue can be obtained with the fibre operating well below this limiting value. Removal rate measurements and scanning electron microscope evaluation of the irradiated site for bovine cornea ablated using the fibre-delivered HF laser pulses are reported.     

Effect of intraperitoneally injected fluoride on plasma calcium in suckling and adult rats

Summary Sodium fluoride 10, 20, or 40 mg/kg body weight was given intraperitoneally to rats (6–11 days old and 90–95 days old). Blood analyses showed an initial increase in plasma fluoride concentration. The subsequent decrease in fluoride was paralleled by a decrease in total plasma calcium. These plasma concentrations were normal at blood collection 4 days after fluoride injection. The baby rats differed from the older rats in that their initial plasma calcium was higher and that the drop in plasma calcium concentration was less pronounced than in the old rats. A diet low in calcium and phosphate enhanced the effects of fluoride on total plasma calcium. The data indicate that the effect of large doses of fluoride on lowering the plasma calcium level is modified by the calcium intake.     

Dexamethasone enhances the osteogenic effects of fluoride in human TE85 osteosarcoma cellsin vitro

Thein vitro osteogenic effects of fluoride have not always been consistently observed in human bone cells. The present study sought to test if dexamethasone (Dex)_ could potentiate the action of fluoride to increase the detectability of the stimulatory effects of fluoride on [³H]thymidine incorporation, alkaline phosphatase (ALP) specific activity, collagen synthesis, and osteocalcin secretion in human TE85 osteosarcoma cells. Neither Dex at 10⁻¹⁰–10⁻⁶ M or fluoride at a mitogenic dose (100 μM) had any consistent stimulatory effects on thymidine incorporation. When the cells were treated with both agents simultaneously, significant and highly reproducible stimulations were observed. The mitogenic effects of the two agents were confirmed with cell number counting. Analysis of variance (ANOVA) revealed a significant interaction (P<0.001) between fluoride and Dex on cell proliferation. The enhancing effect of Dex on [³H]thymidine incorporation was not due to a shift of the optimal dose response of fluoride. Though fluoride alone or Dex alone also had no consistent effect on ALP specific activity, the co-treatment with fluoride and Dex for 24 hours produced significant (P<0.001, ANOVA) stimulation in ALP specific activity. Fluoride alone had no consistent effect on collagen synthesis and on 1,25(OH)₂D₃-dependent osteocalcin secretion, whereas Dex treatment consistently inhibited these two osteoblastic parameters in a dose-dependent manner. However, both the collagen synthesis and osteocalcin secretion rates were significantly higher (P<0.001 ANOVA for each) when the cells were co-treated with Dex and fluoride (100 μM) than when they were treated with Dex alone. Thus, these data indicate that the response in collagen synthesis and osteocalcin secretion to fluoride stimulation was more readily observed in the presence of Dex than in its absence. ANOVA analysis revealed that the interaction between fluoride and Dex on collagen synthesis, but not the 1,25(OH)₂D₃-dependent osteocalcin secretion, was significant (P<0.02). In summary, we have demonstrated for the first time that in TE85 cells (1) Dex potentiated the effects of fluoride on cell proliferation, ALP specific activity, and collagen synthesis; (2) while Dex at 10⁻⁷–10⁻⁶ M alone inhibited the collagen synthesis and at 10⁻⁹–10⁻⁶ M reduced osteocalcin secretion, Dex at 10⁻⁸–10⁻⁶ M significantly stimulated the proliferation of TE85 cells; and (3) Dex interacted with fluoride to increase the percentage of experiments showing an osteogenic action of fluoride. In conclusion, thein vitro osteogenic actions of fluoride in human TE85 cells are more consistently observed in the presence than in the absence of Dex.     

In vitro functional responses of isolated human vaginal tissue to selective phosphodiesterase inhibitors

Only little is known as to the significance of the cyclic nucleotide-mediated signal transduction in the control of the function of human vaginal smooth musculature. Recently, the presence of the phosphodiesterase (PDE) isoenzymes 4 (cAMP-PDE) and 5 (cGMP-PDE) in the human vagina was reported. Thus, it was the aim of the study to elucidate the effects of some PDE inhibitors on the tension induced by endothelin 1 (ET-1), as well as on levels of cGMP and cAMP in isolated human vaginal wall tissue. Using the organ bath technique, the ability of norepinephrine (NE), carbachol, serotonin (5-HT), oxytocin and ET-1 to contract isolated vaginal wall muscle strips was evaluated. In another set-up, the effects of the PDE4 inhibitor rolipram and PDE5 inhibitors sildenafil and vardenafil (1 nM–10 μM) on the tension induced by 0.1 μM ET-1 of human vaginal wall tissue strips were investigated. In order to measure drug effects on tissue levels of cGMP and cAMP, vaginal tissue was exposed to different concentrations (0.1, 1 and 10 μM) of the compounds and the accumulation of cyclic nucleotides was determined. The adenylyl cyclase stimulating agents forskolin and nitric oxide donor sodium nitroprusside (SNP) (0.01, 0.1 and 1 μM) were used as reference compounds. While NE, carbachol and oxytocin failed to contract the vaginal tissue, ET-1 and, to a certain degree, 5-HT elicited contractile responses of the isolated strip preparations. The tension induced by 0.1 μM ET-1 was dose-dependently reversed by the drugs. The rank order of efficacy was sildenafil > forskolin > rolipram ≥ vardenafil > SNP. R _max values ranged from 24% (SNP) to 50% (sildenafil). With sildenafil being the only exception, none of the compounds reached an EC₅₀ value. The relaxing effects of the drugs were paralleled by a fourfold to tenfold increase in tissue levels of cGMP and/or cAMP. Our results demonstrate that PDE inhibitors can relax human vaginal tissue and increase levels of cyclic nucleoside monophosphates. The findings with regard to the PDE5 inhibitors may indicate that the NO–cGMP pathway is, to a certain degree, involved in the control of vaginal smooth muscle tone. This might be of significance with regard to the pharmacological treatment of disorders connected with female sexual arousal and the ability to achieve orgasm.     

Alterations in Proinsulin and Insulin Dynamics, HDL Cholesterol and ALT After Gastric Bypass Surgery. A 42-Months Follow-up Study

Background  Roux-en-Y gastric bypass (RYGBP) powerfully reduces type 2 diabetes (T2DM) incidence. Proinsulin predicts development of T2DM. Adjustable gastric banding is associated with lowered proinsulin but after RYGBP information is scant. Methods  Twenty-one non-diabetic morbidly obese patients who underwent RYGBP surgery were evaluated before (baseline), at 12 months (first follow-up), and at 42 months, range 36–50 (second follow-up), after surgery and compared to a control group, matched at baseline regarding fasting glucose, insulin, proinsulin, alanine aminotransferase (ALT), high-density lipoprotein (HDL) cholesterol, and body mass index (BMI). Results  In the RYGBP group, fasting serum proinsulin concentrations were markedly lowered from 13.5 to 3.5 pmol/l at first follow-up and to 4.9 pmol/l at second follow-up (p < 0.001, respectively). Fasting insulin concentrations were reduced from 83.4 to 24.6 pmol/l at first follow-up (p < 0.001) and to 36.4 pmol/l at second follow-up (p < 0.01). ALT was lowered from 0.62 to 0.34 μkatal/l at first follow-up and continued to lower to 0.24 μkatal/l at second follow-up (p < 0.001, respectively). The further decrease between first and second follow-up was also significant (p = 0.002). HDL cholesterol increased from 1.16 to 1.45 mmol/l at the first follow-up and continued to increase at second follow-up to 1.58 mmol/l (p < 0.001, respectively). The further increase between first and second follow-up was also significant (p = 0.006). The differences between groups at first follow-up were significant for BMI, proinsulin, insulin, ALT, and HDL cholesterol (p = 0.04–0.001). Conclusion  RYGBP surgery in morbidly obese patients is not only characterized by markedly and sustained lowered BMI but also lowered concentrations of proinsulin, insulin, and ALT and increased HDL cholesterol. An erratum to this article can be found at     

A Randomized Trial of Sodium Fluoride (60 mg) ± Estrogen in Postmenopausal Osteoporotic Vertebral Fractures: Increased Vertebral Fractures and Peripheral Bone Loss with Sodium Fluoride; Concurrent Estrogen Prevents Peripheral Loss, But Not Vertebral Fractures

Postmenopausal Caucasian women aged less than 80 years (n= 99) with one or more atraumatic vertebral fracture and no hip fractures, were treated by cyclical administration of enteric coated sodium fluoride (NaF) or no NaF for 27 months, with precautions to prevent excessive stimulation of bone turnover. In the first study 65 women, unexposed to estrogen (–E study), age 70.8 ± 0.8 years (mean ± SEM) were all treated with calcium (Ca) 1.0–1.2 g daily and ergocalciferol (D) 0.25 mg per 25 kg once weekly and were randomly assigned to cyclical NaF (6 months on, 3 months off, initial dose 60 mg/day; group F CaD, n= 34) or no NaF (group CaD, n= 31). In the second study 34 patients, age 65.5 ± 1.2 years, on hormone replacement therapy (E) at baseline, had this standardized, and were all treated with Ca and D and similarly randomized (FE CaD, n= 17; E CaD, n= 17) (+E study). The patients were stratified according to E status and subsequently assigned randomly to ± NaF. Seventy-five patients completed the trial. Both groups treated with NaF showed an increase in lumbar spinal density (by DXA) above baseline by 27 months: FE CaD + 16.2% and F CaD +9.3% (both p= 0.0001). In neither group CaD nor E CaD did lumbar spinal density increase. Peripheral bone loss occurred at most sites in the F CaD group at 27 months: tibia/fibula shaft –7.3% (p= 0.005); femoral shaft –7.1% (p= 0.004); distal forearm –4.0% (p = 0.004); total hip –4.1% (p = 0.003); and femoral neck –3.5% (p= 0.006). No significant loss occurred in group FE CaD. Differences between the two NaF groups were greatest at the total hip at 27 months but were not significant [p<0.05; in view of the multiple bone mineral density (BMD) sites, an alpha of 0.01 was employed to denote significance in BMD changes throughout this paper]. Using Cox’s proportional hazards model, in the –E study there were significantly more patients with first fresh vertebral fractures in those treated with NaF than in those not so treated (RR = 24.2, p= 0.008, 95% CI 2.3–255). Patients developing first fresh fractures in the first 9 months were markedly different between groups: –23% of F CaD, 0 of CaD, 29% of FE CaD and 0 of E CaD. The incidence of incomplete (stress) fractures was similar in the two NaF-treated groups. Complete nonvertebral fractures did not occur in the two +E groups; there were no differences between groups F CaD and CaD. Baseline BMD (spine and femoral neck) was related to incident vertebral fractures in the control groups (no NaF), but not in the two NaF groups. Our results and a literature review indicate that fluoride salts, if used, should be at low dosage, with pretreatment and co-treatment with a bone resorption inhibitor. Received: 22 August 2000 / Accepted: 23 July 2001     

The Serial Changes of Ghrelin and Leptin Levels and Their Relations to Weight Loss After Laparoscopic Minigastric Bypass Surgery

Background The ghrelin and leptin levels have been reported to be correlated with weight loss after bariatric surgery. However, the serial changes of ghrelin and leptin levels after laparoscopic minigastric bypass surgery (LMGBP) have not been reported yet. Therefore, we aimed to evaluate their serial changes and to analyze their relations to weight reduction after LMGBP. Methods Serial fasting serum leptin and ghrelin concentrations were measured in 68 morbidly obese patients before (M0) and 1 (M1), 3 (M3), 6 (M6), and 12 (M12) months after LMGBP surgery. The correlations between ghrelin, insulin, and leptin concentrations and weight reduction were analyzed. Results Leptin levels were significantly reduced at 1, 3, 6, and 12 months after surgery, respectively (vs M0, p < 0.001), whereas the ghrelin concentrations were not significantly changed after surgery. The percent of excess BMI lost (%EBL) 12 months after surgery was negatively correlated with higher preoperative ghrelin concentrations (p = 0.004) and larger preoperative BMI (p = 0.002) in the multivariate analysis. Conclusion Higher preoperative ghrelin concentrations and larger BMI are predictive of less %EBL at 12 months after LMGBP surgery.     

Effects of nerve stimulation on spontaneously active preparations of the guinea pig ureter

The effects of intrinsic nerve stimulation on the spontaneous electrical activity of the smooth muscle cells of the guinea pig ureter still attached to its renal pelvis were investigated using standard intracellular microelectrode techniques. Action potentials discharged spontaneously at a frequency of 3.3 ± 0.2 min⁻¹ (n = 67) and consisted of an initial rapidly rising spike, followed by a variable period (0.2–5 s) of membrane potential oscillation and a quiescent plateau phase which was terminated by an abrupt repolarisation and after-hyperpolarisation to −66 mV. Transmural electrical stimulation (20–50 Hz for 2 s) transiently decreased the frequency of action potential discharge; the half-amplitude duration of the following action potentials, however, was transiently increased to 156 ± 12% of control. Substance P (1 μM applied for 2 min) or neurokinin A (100 nM for 2 min) transiently increased the frequency of action potential discharge to 155 ± 19% and 142 ± 21%, respectively, of control. The excitatory actions of nerve stimulation or agonist application were reduced by the tachykinin antagonist, MEN 10,627 (1–3 μM), while the inhibitory actions of nerve stimulation were enhanced by MEN 10,627 (1 μM) or thiorphan (1 μM). Capsaicin (10 μM for 10–15 min) also evoked a transient increase in the frequency and half-amplitude duration of the ureteric action potentials, in a manner blocked by MEN 10,627 (3 μM), which was followed by a long period of membrane potential quiescence. Human calcitonin gene related peptide (hCGRP) (100 nM applied for 2–5 min) induced a time-dependent decrease in the frequency amplitude and duration of the spontaneous action potentials, in a manner blocked by glibenclamide (1 μM). It was concluded that the nerve-evoked excitatory and inhibitory changes in the parameters of the spontaneous ureteric action potentials arise from the release of the sensory neuropeptides, tachykinins and CGRP, respectively. Received: 22 December 1998 / Accepted: 14 April 1999     

Hyperuricemia and gout following pediatric renal transplantation

Hyperuricemia and gout are common complications in adult renal transplant recipients. In pediatric recipients, however, hyperuricemia seems to be rare, but data are scarce. Thirty-two children (21 males, 11 females) were investigated for a median time of 4.8 years (range: 0.4–11.2 years) following renal transplantation. The median age of this pediatric study group was 13.9 years (range: 5.7–20.3 years), and the calculated glomerular filtration rate (GFR) was 61 ml/min per 1.73 m² (range:12–88 ml/min per 1.73 m²). All patients were given calcineurin inhibitors, with 22 and ten children receiving cyclosporine A (CSA) and tacrolimus (TAC), respectively. The median plasma uric acid was 385 μmol/l (range: 62–929 μmol/l); 15 children (47%) were above the age-related normal range. Only one patient experienced gouty arthritis. There was a significant correlation between plasma uric acid concentration and both time span after transplantation and plasma creatinine, and an inverse correlation to GFR (p<0.05). No significant correlation was found between plasma uric acid and body mass index (BMI). Plasma uric acid concentrations were neither different among CSA- and TAC-treated children, nor did they correlate with drug exposure or blood trough levels of CSA or TAC. Plasma uric acid concentration was not different when compared to children with chronic renal failure (CRF) of a similar degree in native kidneys. We conclude that hyperuricemia is common among pediatric renal transplant recipients and rather a consequence of chronic renal transplant dysfunction than the use of calcineurin inhibitors. Gout, however, is rare.     

Parathyroid glands,calcium, and vitamin D in experimental fluorosis in pigs

Summary The purpose of this study was to determine whether total serum calcium, parathyroid gland structure, and/or levels of parathyroid hormone, 1,25 and 24,25 DHCC, are altered in pigs with dental and skeletal fluorosis. Eight experimental animals receiving 2 mg F⁻/kg b.w. per day from age 8–14 months were compared with eight controls. Concentrations of plasma fluoride and total plasma calcium were assessed at intervals throughout the experiment and during a 48 hour period at day 110–111 of the experiment. At the same time, concentrations of immunoreactive parathyroid hormone were measured using a homologous labeled antibody for porcine hormone, and a radioimmunoassay was used to assess concentrations of 1,25 DHCC and 24,25 DHCC. Parathyroid tissue volumes were assessed at the end of the experiment by quantitative histology using volumetry and point counting. Plasma fluoride increased from 0.0007±0.0001 mmol/liter to 0.0127±0.002 mmol/liter in pigs receiving fluoride. In spite of this increase, total plasma calcium remained the same throughout the experiment. Volumes of parathyroid tissue, and levels of circulating parathyroid hormone 1,25 DHCC and 24,25 DHCC, were not significantly changed. It was therefore concluded that disturbance of calcium homeostasis is not an obligatory finding in dental and skeletal fluorosis and consequently does not play an essential role in the pathogenesis of these hard tissue lesions.     

Inhibition of parathyroid hormone-stimulated resorption in cultured fetal rat long bones by the main metabolites of ipriflavone

Ipriflavone is an isoflavone derivative used in the prevention and treatment of postmenopausal and senile osteoporosis in humans. To assess the potential contribution of the mainin vivo ipriflavone metabolites (M1, M2, M3, and M5) on the pharmacological properties of the drug, we investigated their effect on osteoclastic resorption induced by the well-known stimulator of bone resorption bovine parathyroid hormone fragment 1–34 (bPTH 1–34). The study was carried out using fetal rat long bones in stationary cultures. The amount of osteoclastic resorption was determined by assaying for 5 days the release from bones in the media of previously incorporated⁴⁵Ca. All metabolites were effective at inhibiting osteoclastic resorption. Maximal potency was shown by M3, characterized by a significant effect at 10 μM (P<0.01) and by an IC₅₀ value of 17 μM. M2 was about threefold less potent than M3 (IC₅₀=46 μM). M1 and m5 were the least active compounds with an IC₅₀ value of 117 and 200 μM, respectively. The present evidence indicates that metabolites of ipriflavone, in particular M3 and M2, inhibit bPTH 1–34-induced bone resorption in fetal rat long bones. Accordingly, they may play an important role in the pharmacological effects of the drug.     

Plasma fluoride and enamel fluorosis

It is postulated that tissue fluid F concentrations are the primary determinants of fluoride effects on bones and developing teeth and that these concentrations are dependent on, or mirrored by, blood plasma F. It has earlier been shown that the plasma F levels are dependent on the dietary F supply as well as on skeletal F concentration. Fasting and post-ingestion or postinjection plasma F levels have been determined in rats on F doses that cause different degrees of enamel fluorosis. The results indicate that temporary peak values rather than elevated fasting values are responsible for the occurrence of enamel fluorosis and that the peak values must approach about 10 M in order to block enamel formation by the ameloblasts. The diagnostic and prognostic importance of plasma F determinations is discussed.     

The effect of intravenous sodium fluoride and synthetic salmon calcitonin on plasma total calcium,inorganic phosphate,and ionic fluoride

Summary Various doses of sodium fluoride (NaF), salmon calcitonin (CT) and NaF combined with CT were given intravenously to rats (236±2 g). Blood plasma samples were collected at various times up to 24 hours and measured for total calcium (adjusted for variation in plasma albumin), inorganic phosphate, ionic fluoride, urea, and creatinine. Following injection of NaF alone, significant hypocalcemia and hyperphosphatemia was observed. In contrast, CT injections resulted in hypocalcemia and hypophosphatemia. NaF and CT given in combination generally resulted in the hypocalcemia being equal to or greater than that calculated from the simple addition of their individual effects. Significant increases in both plasma creatinine and plasma urea were observed following treatment with NaF alone or with CT and NaF together, whereas CT alone had negligible effect. These results suggest that NaF does not mimic the effects of CT; rather that NaF and CT interact to modify their individual effects. The influence of NaF probably occurs via an effect on kidney function.     

Cytotoxic effect of clodronate and zoledronate on the chondrosarcoma cell lines HTB-94 and CAL-78

The wide surgical tumour resection is the only effective treatment in chondrosarcoma. However, a major problem remains the high rate of local recurrences and metastases due to the lack of adjuvant therapies. In this study the cytotoxic effect of the bisphosphonate clodronate (0.1–1000 μM) and zoledronate (0.1–1000 μM) in different concentrations on two chondrosarcoma cell lines (HTB-94 and CAL-78) has been investigated. After an incubation period of 48, 72 and 96 hours the chondrosarcoma cell viability was measured as the MTT-proliferation rate. In concentrations of >1 μm zoledronate the cell activity was reduced by up to 95% for the CAL-78 cells. Further, zoledronate has been more effective in lower concentrations than clodronate in the reduction of cell viability for both cell lines. However, clodronate showed significant cytotoxic effects in high concentrations and after longer incubation periods. Further research is necessary, but in the light of these results bisphosphonates may also play a role in the treatment of chondrosarcomas.     

Development of a synthetic peptide-based tartrate-resistant acid phosphatase radioimmunoassay for the measurement of bone resorption in rat serum

Selective markers of bone turnover provide a convenient and reproducible alternative to the complex and expensive histochemical techniques used commonly to study the effect of pharmacological agents and the pathogenesis of bone disease in the ovariectomized (OVX) rat model. One marker, which has been specifically linked to terminally differentiated osteoclasts and, thus, provides useful insight at cellular levels, is type-5 tartrate-resistant acid phosphatase (TRACP). We describe the development of a TRACP radioimmunoassay (RIA), which requires synthetic peptide for antibody development. To develop the RIA, polyclonal antibodies were generated in goats against a synthetic peptide, DPSVRHQRKCY, corresponding to amino acid residues 267–275 of the rat type-5 TRACP sequence. In the RIA, 50 μl of rat serum, 100 μl of goat anti-TRACP antibodies, and 100 μl of tracer were incubated overnight. The antibody-bound fraction was separated, counted, and unknown values were calculated by comparison with the peptide calibrator. Rat serum shows parallelism with the synthetic peptide calibrator used in the RIA. The sensitivity of the RIA was 24.7 μg/l, and the measuring range was 19–2476 μg/l. The average intra-assay coefficients of variation for (CV) two controls were less than 7%. The average dilution and spike recoveries were 107% and 87%, respectively. We applied our peptide-based RIA to study bone resorption in an OVX rat model. TRACP concentrations in serum in 12-week-old OVX Sprague Dawley rats were 14%–22% (P < 0.05) higher than those in the sham-operated rats, and TRACP concentrations in OVX rats treated with estradiol were 24%–32% lower (P < 0.01) than those in the vehicle-treated OVX group. Similarly, as compared with those in OVX rats, TRACP concentrations decreased to those of sham levels in OVX rats receiving 10 μg/kg per day of alendronate for 10 days. In addition, the TRACP levels determined by RIA showed a significant correlation with serum C-telopeptide (type-I collagen) concentrations (r = 0.56; P < 0.001) measured by an enzyme-linked immunosorbent assay (ELISA) developed earlier for the rat model. In conclusion, we have developed a TRACP RIA that could be used to monitor the rate of bone resorption in the rat model. Received: June 18, 2001 / Accepted: October 26, 2001     

Phenytoin and fluoride act in concert to stimulate bone formation and to increase bone volume in adult male rats

We have recently demonstrated that phenytoin is an osteogenic agent at low doses. The present paper describes observations that a mitogenic dose (i.e., 20 M in BGJ_b medium) of fluoride significantly augments the phenytoin-dependent stimulation of normal human bone cell proliferation and alkaline phosphatase (ALP) activity in cell culture. Additionally, the present study was designed to investigate whether fluoride and phenytoin would interact to increase bone formation in rats in vivo. Four groups of weight-matched adult male rats received daily I.P. injection of (1) vehicle (10% DMSO), (2) 5 mg/kg/day phenytoin, (3) 5 mg/kg/day phenytoin and 50 ppm NaF, and (4) 50 ppm NaF and vehicle, respectively, for 36 days. Sodium fluoride (NaF) was delivered in drinking water. Blood samples were drawn weekly and analyzed for serum osteocalcin, ALP, calcium, phosphorus, and 25 (OH)D₃. Rats were labeled with fetracycline at day 21 and 30 and histomorphometric analysis was carried out on the tibia at the end of the experiment. Neither agent by itself or together affected the serum calcium, phosphorus, or 25 (OH)D₃ levels. All measures of bone formation, i.e., serum osteocalcin level and ALP activity, bone ALP specific activity, mineral apposition rate, bone formation rate, and % bone formation surface, were increased by each agent. Fluoride and phenytoin together produced bigger increases in each parameter than did each agent alone. Trabecular bone volume was increased in the bibial metaphysis by fluoride or phenytoin alone; and when administered together, the two agents produced a greater increase. The combined effect of fluoride and phenytoin on each serum and bone formation parameter appeared to be less than additive. Phenytoin or fluoride alone did not significantly reduce the metaphyseal % resorptive surface. However, treatments with both agents together caused a highly significant reduction in the metaphyseal % resorptive surface. Phenytoin and fluoride together also significantly reduced (by 36%) the mineralization lag time, indicating that these agents did not promote osteomalacia. In summary, fluoride and phenytoin act in concert to stimulate bone formation and increase trabecular bone volume without causing mineralization defects in vivo and thus, may be a potential combination therapy for low bone mass in osteoporosis.