Organophosphate Flame-Retardants Alter Adult Mouse Homeostasis and Gene Expression in a Sex-Dependent Manner Potentially Through Interactions With ERα.

Flame retardants (FRs) such as polybrominated diphenyl ethers and organophosphate FR (OPFR) persist in the environment and interact with multiple nuclear receptors involved in homeostasis, including estrogen receptors (ERs). However, little is known about the effects of FR, especially OPFR, on mammalian neuroendocrine functions. Therefore, we investigated if exposure to FR alters hypothalamic gene expression and whole-animal physiology in adult wild-type (WT) and ERα KO mice. Intact WT and KO males and ovariectomized WT and KO females were orally dosed daily with vehicle (oil), 17α-ethynylestradiol (2.5 µg/kg), 2,2', 4,4-tetrabromodiphenyl ether (BDE-47, 1 or 10 mg/kg), or an OPFR mixture {1 or 10 mg/kg of tris(1, 3-dichloro-2-propyl)phosphate, triphenyl phosphate, and tricresyl phosphate each} for 28 days. Body weight, food intake, body composition, glucose and insulin tolerance, plasma hormone levels, and hypothalamic and liver gene expression were measured. Expression of neuropeptides, receptors, and cation channels was differentially altered between WT males and females. OPFR suppressed body weight and energy intake in males. FR increased fasting glucose levels in males, and BDE-47 augmented glucose clearance in females. Liver gene expression indicated FXR activation by BDE-47 and PXR and CAR activation by OPFR. In males, OPFR increased ghrelin but decreased leptin and insulin independent of body weight. The loss of ERα reduced the effects of both FR on hypothalamic and liver gene expression and plasma hormone levels. The physiological implications are that males are more sensitive than ovariectomized females to OPFR exposure and that these effects are mediated, in part, by ERα.

Local enema treatment to inhibit FOLH1/GCPII as a novel therapy for inflammatory bowel disease.

Here we evaluate the potential for local administration of a small molecule FOLH1/GCPII inhibitor 2-phosphonomethyl pentanedioic acid (2-PMPA) as a novel treatment for inflammatory bowel disease (IBD). We found that FOLH1/GCPII enzyme activity was increased in the colorectal tissues of mice with TNBS-induced colitis, and confirmed that 2-PMPA inhibited FOLH1/GCPII enzyme activity ex vivo. In order to maximize local enema delivery of 2-PMPA, we studied the effect of vehicle tonicity on the absorption of 2-PMPA in the colon. Local administration of 2-PMPA in a hypotonic enema vehicle resulted in increased colorectal tissue absorption at 30min compared to 2-PMPA administered in an isotonic enema vehicle. Furthermore, local delivery of 2-PMPA in hypotonic enema vehicle resulted in prolonged drug concentrations for at least 24h with minimal systemic exposure. Finally, daily treatment with the hypotonic 2-PMPA enema ameliorated macroscopic and microscopic symptoms of IBD in the TNBS-induced colitis mouse model, indicating the potential of FOLH1/GCPII inhibitors for the local treatment of IBD.

Effect of astaxanthin supplementation on paraoxonase 1 activities and oxidative stress status in young soccer players.

The purpose of the study was to examine the effects of astaxanthin (Asx) on paraoxonase (PON1) activities and oxidative stress status in soccer players. Forty soccer players were randomly assigned in a double-blind fashion to Asx and placebo (P) group. Blood samples were obtained before, 45 and 90 days after supplementation. PON1 activity was assessed by using two substrates: paraoxon and diazoxon. The oxidative stress biomarkers were also examined: total sulphydryl group content (-SH groups), thiobarbituric acid-reactive substances (TBARS), advanced oxidation protein products and redox balance. The significant interaction effect of supplementation and training (p < 0.05) on PON1 activity toward paraoxon was observed. The PON1 activity toward diazoxon increased in Asx group after 90 days (p < 0.01), while there was no significant difference in P group. SH groups content rose from pre- to post-supplementation period only in Asx group (supplementation and training, p < 0.05; training, p < 0.01). TBARS levels decreased after 45 days and increased after 90 days of regular soccer training in both groups (training, p < 0.001). Redox balance decreased significantly in response to the regular training, regardless of treatment group (training, p < 0.001). Asx supplementation might increase total SH groups content and improve PON1 activity through protection of free thiol groups against oxidative modification.

Assessment of toxicokinetics and toxicodynamics following intravenous administration of etoposide phosphate in beagle dogs.

The toxicokinetics and toxicodynamics of etoposide phosphate (BMY-40481), a water soluble phosphate ester derivative of etoposide, were investigated in beagle dogs (N = 4) following 5 min i.v. infusion doses equivalent to 57, 114 and 461 mg/m2 of etoposide. The doses were administered in sequence starting with the low dose. There was a 28 day wash-out period between the doses. Serial blood samples were collected over 32 hr and the levels of intact BMY-40481 and etoposide in plasma were measured using validated HPLC assays. Hematology profiles were obtained at pre-dose, and twice a week post-dose for 28 days to correlate systemic exposure to etoposide and hematologic toxicity. Following i.v. administration, plasma concentrations of BMY-40481 declined rapidly. For the 3 doses, mean t 1/2 of BMY-40481 ranged from 0.11-0.17 hr (6.6-11 min). The mean Cmax and AUC values of BMY-40481 ranged from 1.72-40.5 micrograms/ml and 0.16-4.14 hr.micrograms/ml, respectively. Both systemic clearance and steady state volume of distribution of BMY-40481 decreased significantly at the high dose. In contrast, the mean Cmax and AUC values of etoposide ranged from 5.46-39.4 micrograms/ml and 2.28-22.6 hr.micrograms/ml, respectively. Cmax occurred at the end of infusion (5 min) at all dose levels, indicating that etoposide was rapidly formed from BMY-40481. The apparent systemic clearance (range: 342-435 ml/min/m2) and apparent steady state volume of distribution (range: 21.5-26.6 l/m2) of etoposide were dose-independent. The AUC of etoposide was significantly correlated with hematologic toxicity, i.e., percent decreases in white blood count (WBC), absolute neutrophil count (ANC) and platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

IHP entrapment into human erythrocytes: comparison between hypotonic dialysis and DMSO osmotic pulse.

Three different blood units were treated separately by the hypotonic dialysis (HD) and the dimethylsulphoxide osmotic pulse (DMSO) method, in order to load the erythrocytes with inositol hexaphosphate. A detailed comparison between the two loading techniques was performed by monitoring the red cell distribution patterns on discontinuous Percoll density gradients, the RBC oxygen affinity and the amount of the main intracellular organic phosphates with the 31P-NMR. The results obtained showed that: (1) The HD loading produces a redistribution of the RBC fractions with a concomitant smoothing of the relative differences among distinct fractions (2) only a minor portion of erythrocytes (from 8.5 to 24.9% of total RBCs) are loaded with IHP after the DMSO treatment. All of these cells move to the lightest fraction (d = 1.080 g/ml). (3) Both HD and DMSO IHP-loaded cells show an increase in P50 (basal vs. after loading, means +/- SD: 25.8 +/- 3.0 vs. 52.5 +/- 3.2 mm Hg) correlated to the IHP incorporation (mean intracellular IHP concentration: 4.2 mmol/l RBC). (4) probably the IHP incorporation efficiency could be probably improved at least by increasing the IHP concentration during the treatment.

The contribution of magnetic susceptibility effects to transmembrane chemical shift differences in the 31P NMR spectra of oxygenated erythrocyte suspensions.

Triethyl phosphate, dimethyl methylphosphonate, and the hypophosphite ion all contain the phosphoryl functional group. When added to an oxygenated erythrocyte suspension, the former compound gives rise to a single 31P NMR resonance, whereas the latter compounds give rise to separate intra- and extracellular 31P NMR resonances. On the basis of experiments with intact oxygenated cell suspensions (in which the hematocrit was varied) and with oxygenated cell lysates (in which the lysate concentration was varied), it was concluded that the chemical shifts of the intra- and extracellular populations of triethyl phosphate differ as a consequence of the diamagnetic susceptibility of intracellular oxyhemoglobin but that this difference is averaged by the rapid exchange of the compound across the cell membrane. The difference in the magnetic susceptibility of the intra- and extracellular compartments contributes to the observed separation of the intra- and extracellular resonances of dimethyl methylphosphonate and hypophosphite. The magnitude of this contribution is, however, substantially less than that calculated using a simple two-compartment model and varies with the hematocrit of the suspension. Furthermore, it is insufficient to fully account for the transmembrane chemical shift differences observed for dimethyl methylphosphonate and hypophosphite. An additional effect is operating to move the intracellular resonances of these compounds to a lower chemical shift. The effect is mediated by an intracellular component, and the magnitude of the resultant chemical shift variations depends upon the chemical structure of the phosphoryl compound involved.

Interaction of the antitumor Au(I) complex [Au(Ph2P(CH2)2PPh2)2]Cl with human blood plasma, red cells, and lipoproteins: 31P and 1H NMR studies.

The bis-chelated tetrahedral gold(I) complex [Au(dppe)2]Cl, where dppe is Ph2P(CH2)2PPh2, is active in several animal tumor models. When added to human blood plasma in vitro it appears to bind to lipoproteins, giving a slightly broadened 31P NMR signal, and 1H NMR resonances which are too broad to detect. Some lipoprotein is denatured. 31P NMR studies suggest that some [Au(dppe)2]+ is transferred from plasma to red cells with a half-life of ca. 2 hr. The complex binds within red cell membranes and the 1H resonances of intracellular glutathione are unaffected. The 31P NMR resonance from [Au(dppe)2]+ in red cell membranes is observable only when the complex is mobilized by addition of sodium dodecyl sulphate, which also mobilizes membrane phospholipids.

Plasma content of B6 vitamers and its relationship to hepatic vitamin B6 metabolism.

The plasma content of B6 vitamers is governed by, among other factors, dietary supply and metabolic interconversion. This study examines the effect of pyridoxine supplementation on the plasma content of B6 vitamers and pyridoxic acid in man, and the metabolic conversion and release of B6 compounds in isolated rat hepatocytes. Six healthy human subjects were given 100 mg pyridoxine-HCl/d orally for 1--3 wk. Before pyridoxine supplementation, the mean total plasma level of B6 vitamers was 114 +/- 9 nM; and pyridoxal-P, pyridoxamine-P, pyridoxal, pyridoxine, and pyridoxamine accounted for 54, 3, 11, 27, and 5%, respectively. Plasma level of pyridoxic acid was 40 +/- 7 nM. Thus, pyridoxal-P is the principal B6 vitamer in plasma. During pyridoxine supplementation, mean plasma levels of the B6 vitamers and pyridoxic acid increased to 655 +/- 122 and 222 +/- 55 nM, respectively. The plasma content of pyridoxal-P and pyridoxic acid increased 6--7-fold and that of pyridoxal, 12-fold, but the pyridoxine level did not increase. Isolated hepatocytes, 1 g/15 ml, were incubated for 2 h with 3.33 microM [14C]pyridoxine (6 microCi/mumol). At zero time, the cells contained about 35 nmol pyridoxal-P and 25 nmol pyridoxamine-P. After 2 h incubation, the cellular content of pyridoxal-P and pyridoxamine-P did not change significantly, but the medium contained 5.9 nmol pyridoxal-P, 0.3 nmol pyridoxamine-P, 7.2 nmol pyridoxal, 26.6 nmol pyridoxine, 0.3 nmol pyridoxamine, and 7.5 nmol pyridoxic acid. Whereas the specific radioactivity of pyridoxal-P, pyridoxal, and pyridoxic acid in the medium approached that of [14C]pyridoxine, the specific radioactivity of cellular pyridoxal-P and pyridoxamine-P was only 20% of that of pyridoxine. Thus, newly synthesized pyridoxal-P is not freely exchangeable with endogenous pyridoxal-P, but is preferentially released or degraded to pyridoxal and pyridoxic acid. The latter B6 compounds are also released. These results suggest that orally ingested pyridoxine is rapidly metabolized in liver and its products are released into the circulation in the form of pyridoxal-P, pyridoxal, and pyridoxic acid.

Effect of hemodialysis on red cell organic and inorganic phosphates.

Red cell 2,3 diphosphoglyceric acid (DPG), total nucleotide phosphate, inorganic phosphate, and plasma inorganic phosphate were measured at the onset and termination of 22 hemodialyses performed for chronic renal failure in 19 patients. Plasma inorganic phosphate decreased from a mean of 2.05 mM/liter +/- 0.14 to 1.26 mM/liter +/- 0.09 (p less than 0.005) while intracellular inorganic phosphate fell from 1.76 mM/liter +/- 0.12 RBC water to 1.21+/-mM/liter (p less than 0.005). Mean DPG was 6.37 mM/liter RBC +/- 0.23 at the start of the dialysis and 6.08 mM/liter +/- 0.24 at the termination (p=n.s.). Mean nucleotide concentration was 5.90 mM phosphorous content/liter RBC+/-0.26 at the start and 5.95 mM/liter 0.21 at the end (p=n.s.). Although there were significant decreases in intracellular and plasma inorganic phosphate concentrations immediately following dialysis, neither the DPG nor nucleotide phosphate concentrations were significantly altered by this short-term procedure. Red cell water inorganic phosphorous rapidly attained identical concentration with plasma water inorganic phosphorous.