[Pharmacokinetics of triptolide in Beagle dogs]

The aim of this paper is to develop and validate a rapid and sensitive LC-APCI/MS method for the determination of triptolide (TP) in plasma and to study the pharmacokinetic properties of TP in Beagle dogs. Sample preparation consisted of liquid-liquid extraction of interests. with ethyl acetate from dog plasma. The analytes and internal standard prednisolone were well separated on a Zorbax Extend-C18 analytical column. Plasma TP was detected by selected-ion monitoring (SIM) of LC-APCI/MS as its deprotonated molecular ions [M - H] - at m/z 358.9. Pharmacokinetic studies were undertaken in dogs following an iv dose of 0.05 mg x kg(-1) of TP or an ig dose of 0.05, 0.08, 0.1 mg x kg(-1), separately. The pharmacokinetic parameters were calculated by DAS software. Calibration curves were linear over the concentration range of 1 - 200 ng x mL(-1) of TP with the within- and between-batch precisions less than 10%. The within and between-batch accuracy was 95.0% to 105.0%. Recovery of LC-MS method for TP in plasma was over 75%. The T1/2beta was (2.5 +/- 0.8) h after intravenous administration of TP at the dose of 0.05 mg x kg(-1). There were no significant differences in T(max), T1/2 alpha and T1/2 beta among the three ig dosage groups. AUC and C(max) increased proportionally with doses. The absolute bioavailability of TP after ig administration of 0.05 mg x kg(-1) was (75 +/- 17)%. The LC-MS method for determination of triptolide in dog plasma was sensitive and rapid. It was showed that the elimination of triptolide was rapid. The absolute bioavailability of triptolide given orally was high.

Developmental Toxicity by Exposure to Bisphenol A Diglycidyl Ether during Gestation and Lactation Period in Sprague-dawley Male Rats

OBJECTIVES

Bisphenol A diglycidyl ether (BADGE) is the major component in commercial liquid epoxy resins, which are manufactured by co-reacting bisphenol A with epichlorohydrin. This study was performed to show the developmental effects of prenatal and postnatal exposures to BADGE in male rat offspring.

METHODS

Mated female rats were divided into four groups, each containing 12 rats. The dosing solutions were prepared by thoroughly mixing BADGE in corn oil at the 0, 375, 1500 and 3000 mg/kg/day concentrations. Mated females were dosed once daily by oral gavage on gestation day (GD) 6 - 20 and postnatal day (PND) 0 - 21. Pregnant female dams were observed general symptoms and body weight. Also, male pups were observed the general symptoms, body weight, developmental parameters (e.g. anogenital distance, pina detachment, incisor eruption, nipple retention, eye opening, testis descent), organ pathologic changes and hormone levels of plasma.

RESULTS

Pregnant rats treated with BADGE died at a rate of about 70% in the 1500 mg/kg/day group and all rats treated with 3000 mg/kg/day died. Body weight, for male pups treated with doses of 375 mg/kg/day, was significantly lower than in the control group at PND 42, 56, and 63 (p<0.05). Evaluation of body characteristics including; separation of auricle, eruption of incisor, separation of eyelid, nipple retention, descent of testis, and separation of the prepuce in the BADGE treated group showed no difference in comparisons with the control group. AGD and adjusted AGD (mm/kg) for general developmental items in BADGE 375 mg/kg/day treated pups tended to be longer than in controls, however, these differences were not statistically significant. Relative weights of adrenal gland, lung (p<0.05), brain, epididymis, prostate, and testis (p<0.01) were heavier than in control in measures at PND 9 weeks. There were no significant changes in comparisons of histological findings of these organs. Loss of spermatids was observed in the seminiferous tubule at PND 9 weeks, but no weight changes were observed. The plasma estrogen levels were similar in the control and treatment groups at PND 3, 6 and 9 weeks. The plasma testosterone levels in the control group tended to increase with age. However, in the BADGE 375 mg/kg/day treated male pups it did not tend to increase.

CONCLUSIONS

These findings suggest that BADGE is a chemical that has developmental effects consistent with it being an endocrine disruptor.

Kinetic release of triptolide after injection of renal-targeting 14-succinyl triptolide-lysozyme in a rat kidney study by liquid chromatography/mass spectrometry

Triptolide (TP) is one of the most important biologically active components of the Chinese herb Tripterygium wilfordii Hook f (TWHf). A novel high-performance liquid chromatography/mass spectrometry (LC/MS) method was developed to study the kinetic release of TP after intravenous injection of the newly synthesized 14-succinyl triptolide-lysozyme (TPS-LZM). The method was validated in terms of selectivity, linearity, precision, accuracy, stability, limit of detection (LOD) and limit of quantification (LOQ). The calibration curve was linear over the concentration range 0.5-400.0 ng/g. The mean recovery of triptolide from spiked samples, in a concentration range of 0.5-400.0 ng/g, was 91.84% (RSD = 3.69%, n = 3). The intra- and inter-assay coefficients of variation were less than 6.38%. The method with simple sample pretreatment and being highly specific and precise, can be used for analysis of triptolide release in rat kidney after intravenous injection of renal-targeting TPS-LZM conjugate. The results showed that, as compared with free TP, TPS-LZM could significantly increase the concentration and prolong the action time of TP in the kidney.

Pharmacokinetic Study of Triptolide, a Constituent of Immunosuppressive Chinese Herb Medicine, in Rats

Triptolide is a potential anti-immune agent, and has shown multi-organic toxicity, however its toxic mechanism remained undiscovered. This paper aimed at characterizing the pharmacokinetic profiles of triptolide in rats to provide the clue to approach the toxic mechanism. The absorption, distribution, metabolism and excretion of triptolide were investigated in male Sprague-Dawley rats after single doses of oral and i.v. administration. After oral administration of 0.6, 1.2 and 2.4 mg/kg, the concentration of triptolide in plasma reached the maximum within 15 min, and declined rapidly with an elimination half-life from 16.81 to 21.70 min. The triptolide kinetics was fitted into one-compartment model after i.v. administration. Oral absolute bioavailability was 72.08% at the dose of 0.6 mg/kg. Triptolide was also rapidly distributed and eliminated in all selected tissues. Less than 1% triptolide of the dose was recovered from the bile, urine or feces as parent drug within 48 h. While triptolide could not be detected in tissues and plasma at 4 h post dose, rats in the group C (oral: 1.2 mg/kg) and D (oral: 2.4 mg/kg) showed obvious toxic response to triptolide and some of rats even died out. It was indicated that triptolide was metabolized extensively, eliminated rapidly, and also showed that the toxicity produced by the triptolide was lag behind the exposure concentration.

Triptolide suppresses IL-1beta-induced chemokine and stromelysin-1 gene expression in human colonic subepithelial myofibroblasts

AIM

To examine the inhibitive effects of triptolide on the expression of IL-8, monocyte chemotactic protein (MCP)-1, and matrix metalloproteinases (MMP)-3 in subepithelial myofibroblasts (SEMF) stimulated with IL-1beta.

METHODS

SEMF cultures were established from normal colons in patients who underwent gut resection for colorectal carcinoma. Chemokine and MMP-3 expressions were determined by ELISA and RT-PCR. The cytosolic amount of phosphorylation of I kappa B-alpha(p-I kappa B-alpha) was determined by Western blotting. The DNA binding capacity of NF-kappa B was evaluated by electrophoretic mobility shift assays.

RESULTS

IL-1beta stimulated protein and mRNA expression of IL-8, MCP-1, and MMP-3 in SEMF. Triptolide inhibited these effects of IL-1beta in a dose-dependent manner. Mechanistic studies revealed that triptolide markedly decreased IL-1beta -induced NF-kappa B DNA binding capacity and cytosolic amount of p-I kappa B-alpha. These results showed that triptolide inhibited IL-1beta -induced chemokine and MMP-3 expression in SEMF through the NF-kappa B pathway.

CONCLUSION

Triptolide inhibited IL-1beta -induced chemokine and MMP-3 expression in SEMF by preventing the phosphorylation of I kappa B-alpha.

Inhibitory effect of triptolide on lymph node metastasis in patients with non-Hodgkin lymphoma by regulating SDF-1/CXCR4 axis in vitro

AIM

To investigate the antiproliferative effect of triptolide on B-NHL cell line Raji cells, to study its effect on lymph node metastasis in patients with non-Hodgkin's lymphoma (NHL) in vitro, and to explore the underlying mechanism regulating SDF-1/CXCR4 axis.

METHODS

The effects of triptolide on the growth of Raji cells were studied by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. The effects of triptolide on SDF-1 mRNA expression in lymph node stromal cells from patients with NHL were determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The effects of triptolide on CXCR4 expression on lymphoma cells freshly isolated from the lymph nodes of these patients were studied by flow cytometric analysis. Chemotaxis assays were performed to observe the effects of triptolide on migration of primary lymphoma cells towards recombinant human SDF-1 alpha (rhSDF-1 alpha) or cultured lymph node stromal cells in vitro.

RESULTS

Triptolide inhibited the proliferation of B-NHL cell line Raji cells in a dose- and time-dependent manner with a 24-h IC50 value of 43.06 nmol/L and a 36-h IC50 value of 25.08 nmol/L. The expression of SDF-1alpha mRNA in lymph node stromal cells obtained from patients with NHL was decreased after treatment by triptolide at concentrations of 25 and 50 nmol/L for 24 h. Flow cytometry analysis showed that the CXCR4 expression on primary lymphoma cells were downregulated gradually in a dose-dependent manner following triptolide treatment. Chemotaxis assays revealed that the migration of freshly isolated lymphoma cells towards either rhSDF-1 or cultured lymph node stromal cells was markedly inhibited by the addition of triptolide in vitro, and the inhibition was dose-dependent.

CONCLUSION

Triptolide can inhibit the proliferation of B-NHL cell line Raji cells. Moreover, triptolide is able to inhibit the migration of lymphoma cells via lymph nodes in vitro. The potential antitumor mechanisms of triptolide are related to the antiproliferative effect and the blockage of SDF-1/CXCR4 axis.

Relationships between biomarkers of exposure and toxicokinetics in Fischer 344 rats and B6C3F1 mice administered single doses of acrylamide and glycidamide and multiple doses of acrylamide

Acrylamide (AA) is a widely studied industrial chemical that is neurotoxic, mutagenic to somatic and germ cells and carcinogenic in rodents. AA is also formed in many commonly consumed starchy foods during cooking. Our previous toxicokinetic investigations of AA and its important genotoxic metabolite, glycidamide (GA), in rodents showed that AA is highly bioavailable from oral routes of administration, is widely distributed to tissues and that the dietary route, in particular, favors metabolism to GA. Measurements of DNA adducts in many tissues supported the hypothesis that AA is carcinogenic in rodent bioassays through metabolism to GA. The current investigation describes the development and validation of methodology for measuring hemoglobin (Hb) adducts with AA and GA in the same rodents previously used for toxicokinetic and DNA adduct measurements. The goal was to investigate possible relationships between these circulating biomarkers of exposure and serum toxicokinetic parameters for AA and GA and tissue GA-DNA adducts in rodents from both single and repeated dosing with AA. Significant correlations were observed between GA-Hb and liver GA-DNA adducts for either single or multiple dosing regimens with AA. Using available GA-Hb adduct data, empirical and allometric relationships permitted estimation of liver DNA adducts in humans in the range of 0.06-0.3 adducts/10(8) nucleotides. This approach may prove useful in extrapolating human cancer risks from findings in rodent bioassays.

Cuticular uptake of xenobiotics into living plants. Part 2: influence of the xenobiotic dose on the uptake of bentazone, epoxiconazole and pyraclostrobin, applied in the presence of various surfactants, into Chenopodium album, Sinapis alba and Triticum aestivum leaves

This study has determined the uptake of three pesticides, applied as commercial or model formulations in the presence of a wide range of surfactants, into the leaves of three plant species (bentazone into Chenopodium album L. and Sinapis alba L., epoxiconazole and pyraclostrobin into Triticum aestivum L.). The results have confirmed previous findings that the initial dose (nmol mm(-2)) of xenobiotic applied to plant foliage is a strong, positive determinant of uptake. This held true for all the pesticide formulations studied, although surfactant concentration was found to have an effect. The lower surfactant concentrations studied showed an inferior relationship between the amount of xenobiotic applied and uptake. High molecular mass surfactants also produced much lower uptake than expected from the dose uptake equations in specific situations.

PPARγ agonist induced cardiac enlargement is associated with reduced fatty acid and increased glucose utilization in myocardium of Wistar rats

In toxicological studies, high doses of peroxisome proliferator-activated receptor-gamma (PPARgamma) agonists cause cardiac enlargement. To investigate whether this could be explained by a large shift from free fatty acid to glucose utilization by the heart, Wistar rats were treated for 2-3 weeks with a potent, selective PPARgamma agonist (X334, 3 micromol/kg/d), or vehicle. X334 treatment increased body-weight gain and ventricular mass. Treatment lowered plasma triglycerides by 61%, free fatty acid levels by 72%, insulin levels by 45%, and reduced total plasma protein concentration by 7% (indicating plasma volume expansion) compared to vehicle animals. Fasting plasma glucose levels were unaltered. To assess cardiac free fatty acid and glucose utilization in vivo we used simultaneous infusions of non-beta-oxidizable free fatty acid analogue, [9,10-(3)H](R)-2-bromopalmitate and [U-(14)C]2-deoxy-d-glucose tracers, which yield indices of local free fatty acid and glucose utilization. In anesthetized, 7 h fasted animals, left ventricular glucose utilization was increased to 182% while free fatty acid utilization was reduced by 28% (P<0.05) compared to vehicle. In separate studies we attempted to prevent the X334-induced hypolipidemia. Various dietary fat supplements were unsuccessful. By contrast, restricting the time during which the treated animals had access to food (promoting endogenous lipolysis), restored plasma free fatty acid from 27% to 72% of vehicle control levels and prevented the cardiac enlargement. Body-weight gain in these treated-food restricted rats was not different from vehicle controls. In conclusion, the cardiac enlargement caused by intense PPARgamma activation in normal animals is associated with marked changes in free fatty acid/glucose utilization and the enlargement can be prevented by restoring free fatty acid availability.

Nasal NPSH depletion and propylene oxide uptake in the upper respiratory tract of the mouse

Propylene oxide is a nasal toxicant and weak site-of-contact carcinogen in the mouse and rat. To aid in inhalation risk assessment of this vapor and to provide data for comparison to the rat, the current study was aimed at providing quantitative information on upper respiratory tract (URT) dosimetry of this vapor in the mouse. Toward this end, uptake efficiencies of propylene oxide were measured in the surgically isolated URT of the male B6C3F1 mouse under constant velocity inspiratory flow conditions at flow rates of 12 and 50 ml/min and exposure concentrations of 25, 50, 100, 300, or 500 ppm. URT uptake efficiencies were measured continuously during 1 h exposure; mice were terminated immediately after exposure and nasal respiratory and olfactory mucosal nonprotein sulfhydryl (NPSH) levels were determined. Propylene oxide was scrubbed with moderate efficiency in the URT, with uptake efficiencies of < or = 33 and < or = 16% at the low and high inspiratory flow rates, respectively. Uptake efficiencies were slightly (approximately 5%) higher at low (25 or 50 ppm) than high (300 or 500 ppm) exposure concentrations, suggesting that a saturable uptake pathway may exist. Nasal tissue NPSH levels were significantly depleted at exposure concentrations of 300 and 500 ppm but not at concentrations of 100 ppm or lower. Similar levels of NPSH depletion were observed in both nasal respiratory and olfactory mucosa. These data from mouse show some key differences when compared with those reported for the rat.

Inhibition of melanoma tumor growth by a pharmacological inhibitor of MetAP-2, PPI-2458

Over the past few decades, melanoma has shown the fastest growing incidence rate of all cancers. This malignancy is clinically defined by its potential to rapidly metastasize, and advanced metastatic melanomas are highly resistant to existing therapeutic regimens. Here, we report that PPI-2458, a novel, orally active agent of the fumagillin class of irreversible methionine aminopeptidase-2 (MetAP-2) inhibitors, potently inhibited the proliferation of B16F10 melanoma cells in vitro, with a growth inhibitory concentration 50% (GI50) of 0.2 nM. B16F10 growth inhibition was correlated with the inhibition of MetAP-2 enzyme, in a dose-dependent fashion, as determined by a pharmacodynamic assay, which measures the amount of uninhibited MetAP-2 following PPI-2458 treatment. Prolonged exposure of B16F10 cells to PPI-2458 at concentrations of up to 1 microM, 5,000-fold above the GI50, did not alter their sensitivity to PPI-2458 growth inhibition and no drug resistance was observed. Moreover, prolonged exposure to this agent induced melanogenesis, concomitant with the elevated expression of the melanocyte-specific enzymes tyrosinase and tyrosinase-related proteins (TRP) 1 and 2, a morphological feature associated with differentiated melanocytes. PPI-2458, when administered orally (p.o.), significantly inhibited B16F10 tumor growth in mice in a dose-dependent fashion, with a maximum inhibition of 62% at 100 mg/kg. This growth inhibition was directly correlated to the amount of irreversibly inhibited MetAP-2 (80% at 100 mg/kg PPI-2458) in tumor tissue. These data demonstrate that PPI-2458 has potent antiproliferative activity against B16F10 cells in vitro and in vivo, and that both activities are directly correlated with levels of MetAP-2 enzyme inhibition. This antiproliferative activity, coupled with additional observations from studies in vitro (absence of detectable resistance to PPI-2458 and induction of morphological features consistent with differentiated melanocytes), provides a rationale for assessing the therapeutic potential of PPI-2458 in the treatment of melanoma.

Liquid chromatographic/mass spectrometry assay of triptolide in dog plasma and its application to pharmacokinetic study

A rapid and sensitive method for the determination of triptolide in dog plasma was developed and validated, using high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI/MS). Sample preparation consisted of liquid-liquid extraction with ethyl acetate from dog plasma. The analytes and internal standard prednisolone were well separated on a Zorbax Extend-C18 analytical column. Detection was performed on a triple quadrupole mass spectrometer using selected-ion monitoring (SIM) mode on the deprotonated ions [M-H]- at m/z 359. Calibration curves were linear over the concentration range of 0.5-200 ng/mL of triptolide with the intra- and inter-day precision (the relative standard deviation values) were being less than 7%. Triptolide was stable under different conditions. The intra-day and inter-day accuracy were 99.3-105.2% and 101.3-107.0%, respectively. The lower limit of quantification was 0.5 ng/mL. The method was successfully applied to a pharmacokinetic study after an intragastric administration (i.g.) of triptolide to dogs with a dose of 0.05 mg/kg. The results confirm that the assay is suitable for the pharmacokinetic study of triptolide.

A novel, selective, and orally available antagonist for CC chemokine receptor 3

CC chemokine ligand 11 (CCL11/eotaxin) and other CC chemokine receptor 3 (CCR3) ligands (CCL24/eotaxin-2, CCL26/eotaxin-3, CCL13/monocyte chemotactic protein-4, etc.) play important roles in the chemotaxis and activation of eosinophils and other CCR3-expressing cells (basophils, mast cells, and CD4(+) T helper 2 cells) in allergic inflammation incidents, including asthma and rhinitis. A newly synthesized compound, N-{(3R)-1-[(6-fluoro-2-naphthyl)methyl]pyrrolidin-3-yl}-2-{1-[(5-hydroxy-3-methylpyridin-2-yl)carbonyl]piperidin-4-ylidene}-acetamide hemifumarate (YM-355179), inhibited the binding of CCL11 and CCL5/regulated on activation normal T cell expressed and secreted to CCR3-expressing B300-19 cells with IC(50) values of 7.6 and 24 nM, respectively. In contrast, YM-355179 did not affect the binding of CCL5 to CCR1 or CCR5. In functional assays, YM-355179 inhibited CCL11-induced, intracellular Ca(2+) influx, chemotaxis, and eosinophil degranulation with IC(50) values of 8.0, 24, and 29 nM, respectively. YM-355179 did not, however, affect any CC chemokine receptor (CCR1, CCR2, CCR4, or CCR5)-mediated Ca(2+) influx signals. Furthermore, oral administration of YM-355179 (1 mg/kg) inhibited CCL11-induced shape change of whole blood eosinophils in cynomolgus monkeys. Intravenous injection of YM-355179 (1 mg/kg) also inhibited eosinophil infiltration into airways of cynomolgus monkeys after segmental bronchoprovocation with CCL11. These results indicate that YM-355179 is a novel, selective, and orally available CCR3 antagonist with therapeutic potential for treating eosinophil-related allergic inflammatory diseases.

Peripherally mediated antinociception of the mu-opioid receptor agonist 2-[(4,5alpha-epoxy-3-hydroxy-14beta-methoxy-17-methylmorphinan-6beta-yl)amino]acetic acid (HS-731) after subcutaneous and oral administration in rats with carrageenan-induced hindpaw inflammation

Opioids induce analgesia by activating opioid receptors not only within the central nervous system but also on peripheral sensory neurons. This study investigated peripherally mediated antinociception produced by the mu-opioid receptor agonist 2-[(4,5alpha-epoxy-3-hydroxy-14beta-methoxy-17-methylmorphinan-6beta-yl)amino]acetic acid (HS-731) after s.c. and oral administration in rats with carrageenan-induced hindpaw inflammation. Antinociceptive effects after s.c. administration were assessed 3 h after intraplantar carrageenan injection and compared with those of centrally acting mu-opioid agonists 14-methoxymetopon and morphine. Opioid agonists caused dose-dependent increases in inflamed paw withdrawal latencies to mechanical and thermal stimulation. The time course of action was different, in that HS-731 (20 microg/kg s.c.) produced significant long-lasting effects up to 4 h after administration, whereas 14-methoxymetopon (20 microg/kg) and morphine (2 mg/kg) reached their peak of action at 10 to 30 min, and their effect declined rapidly thereafter. Subcutaneous administration of the peripherally selective opioid antagonist naloxone methiodide inhibited antinociception elicited by HS-731 (20 microg/kg s.c.), whereas it was ineffective against 14-methoxymetopon (20 microg/kg s.c.). Moreover, the antinociception produced by 100 microg/kg s.c. HS-731 was dose-dependently reversed by s.c. naloxone methiodide. This indicates that HS-731 preferentially activates peripheral opioid receptors, whereas 14-methoxymetopon mediates analgesia via central mechanisms. Orally administered HS-731 significantly reduced hyperalgesia in the inflamed paw induced by carrageenan, which was reversible by s.c. administered naloxone methiodide. These results show that systemic (s.c. and oral) treatment with the mu-opioid agonist HS-731 produces potent and long-lasting antinociception through peripheral mechanisms in rats with carrageenan-induced hindpaw inflammation.

Drug-induced expansion and differentiation of V gamma 9V delta 2 T cells in vivo: the role of exogenous IL-2

Human Vgamma9Vdelta2 T cells recognize nonpeptidic Ags generated by the 1-deoxy-d-xylulose 5-phosphate (many eubacteria, algae, plants, and Apicomplexa) and mevalonate (eukaryotes, archaebacteria, and certain eubacteria) pathways of isoprenoid synthesis. The potent Vgamma9Vdelta2 T cell reactivity 1) against certain cancer cells or 2) induced by infectious agents indicates that therapeutic augmentations of Vgamma9Vdelta2 T cell activities may be clinically beneficial. The functional characteristics of Vgamma9Vdelta2 T cells from Macaca fascicularis (cynomolgus monkey) are very similar to those from Homo sapiens. We have found that the i.v. administration of nitrogen-containing bisphosphonate or pyrophosphomonoester drugs into cynomolgus monkeys combined with s.c. low-dose (6 x 10(5) U/animal) IL-2 induces a large pool of CD27+ and CD27- effector/memory T cells in the peripheral blood of treated animals. The administration of these drugs in the absence of IL-2 is substantially less effective, indicating the importance of additional exogenous costimuli. Shortly after the costimulatory IL-2 treatment, only gammadelta (but not alphabeta) T cells expressed the CD69 activation marker, indicating that Vgamma9Vdelta2 T lymphocytes are more responsive to low-dose IL-2 than alphabeta T cells. Up to 100-fold increases in the numbers of peripheral blood Vgamma9Vdelta2 T cells were observed in animals receiving the gammadelta stimulatory drug plus IL-2. Moreover, the expanded Vgamma9Vdelta2 T cells were potent Th1 effectors capable of releasing large amounts of IFN-gamma. These results may be relevant for designing novel (or modifying current) immunotherapeutic trials with nitrogen-containing bisphosphonate or pyrophosphomonoester drugs.

PPARγ antagonists exacerbate neural antigen-specific Th1 response and experimental allergic encephalomyelitis

Peroxisome proliferator-activated receptor-gamma is a nuclear receptor transcription factor that regulates cell growth, differentiation and homeostasis. PPARgamma agonists have been used in the treatment of obesity, diabetes, cancer and inflammation. We and others have shown recently that PPARgamma agonists ameliorate experimental allergic encephalomyelitis (EAE), a Th1 cell-mediated autoimmune disease model of multiple sclerosis (MS). We have further shown that PPARgamma agonists inhibit EAE through blocking IL-12 signaling leading to Th1 differentiation and the PPARgamma-deficient heterozygous mice (PPARgamma(+/-)) develop an exacerbated EAE. In this study, we show that in vivo treatment (i.p.) with 100 mug PPARgamma antagonists, Bisphenol A diglycidyl ether (BADGE) or 2-Chloro-5-nitro-N-(4-pyridyl)benzamide (T0070907), on every other day from day 0 to 30, increased the severity and duration of EAE in C57BL/6 wild-type and PPARgamma(+/-) mice. The exacerbation of EAE by PPARgamma antagonists associates with an augmented neural antigen-induced T cell proliferation, IFNgamma production or Th1 differentiation. These results further suggest that PPARgamma is a critical physiological regulator of CNS inflammation and demyelination in EAE.

Treatment of hyperphosphatemia in patients with chronic kidney disease on maintenance hemodialysis

Treatment of hyperphosphatemia in patients with chronic kidney disease on maintenance hemodialysis. Hyperphosphatemia in patients with ESRD leads to secondary hyperparathyroidism, renal osteodystrophy, and is independently associated with mortality risk. The exact mechanism by which hyperphosphatemia increases mortality risk is unknown, but it may relate to enhanced cardiovascular calcification. National Kidney Foundation K/DOQI bone metabolism and disease guidelines recommend maintenance of serum phosphorus (P) below 5.5 mg/dL, and Ca x P product less than 55 mg(2)/dL(2). Although calcium-based phosphate binders (CBPB) are cost effective, long-term safety concerns relate to their postulated role in progression of cardiovascular calcification. Sevelamer hydrochloride has been recommended as an alternative noncalcium phosphate binder. Results from the Calcium Acetate Renagel Evaluation (CARE study) indicate that calcium acetate is more effective than sevelamer in controlling serum phosphorous and Ca x P product in hemodialysis patients. In the Treat-to-Goal study, dialysis patients treated with sevelamer had slower progression of coronary and aortic calcification than patients treated with CBPB. The mechanism underlying the beneficial effect of sevelamer is unknown, but may relate to decreased calcium loading or to dramatic reductions in LDL cholesterol in sevelamer-treated patients. At present, evidence incriminating CBPB in the progression of cardiovascular calcification in ESRD remains largely circumstantial. As calcium acetate is more efficacious and cost effective than sevelamer, it remains an accepted first-line phosphate binder. In this review, we will examine these issues and provide rational guidelines for the use of calcium-based phosphate binders in patients on maintenance hemodialysis.

Mercapturic acids of acrylamide and glycidamide as biomarkers of the internal exposure to acrylamide in the general population

Acrylamide (AA), a widely used industrial monomer which is categorised to be carcinogenic, was found to be generated in starch-containing foods during the heating process. This discovery has caused reasonable concern about possible health risks to humans due to dietary acrylamide uptake. In order to gain more information on human metabolism of acrylamide and to contribute to the assessment of the human carcinogenic risk due to AA uptake we measured the mercapturic acid of AA and its epoxide glycidamide (GA) i.e. N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA) and N-(R,S)-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA) in human urine. The relation between AAMA and GAMA is important in this context because GA is thought to be the ultimate carcinogenic metabolite of AA. The median levels in smokers (n=13) were found to be about four times higher than in non-smokers (n=16) with median levels of 127 microg/l versus 29 microg/l for AAMA and 19 microg/l versus 5 microg/l for GAMA. Therefore cigarette smoke proved to be an important source of acrylamide exposure. The level of AAMA in the occupationally non-exposed collective (n=29) ranged from 3 to 338 microg/l, the level of GAMA from <LOD to 45 microg/l. The ratio of GAMA:AAMA varied from 0.03 to 0.53, median was 0.16 which is in reasonable agreement with results of different studies on rats. Thus the metabolic conversion of acrylamide to its genotoxic epoxide glycidamide seems to occur to a comparable extent in rats and humans. Consequently, risk estimations by various authorities based on experimental data obtained in rats are supported by our findings. Besides we also measured the haemoglobin adducts of AA and GA in the blood of 26 participants. From these results compared to the mercapturic acids, we deduce a steady state for AA uptake, and we demonstrate a higher reactivity of GA in comparison to AA towards haemoglobin compared to glutathione in humans.

[Sevelamer:hydrochloride]

The recent global breakthrough in the field of renal osteodystrophy is the inhibitory effect of sevelamer hydrochloride on the progression of coronary artery calcification, which was revealed with EBCT (Electron beam computed tomography) 1) approximately 3). It has been found that the degree of coronary artery calcification assessed with EBCT is proportional to the mortality risk by the coronary artery stenosis and by myocardial infarction in non-hemodialysis patients 4) approximately 10). In 2004 in Japan Matsuoka and Iseki et al showed for the first time in the world that coronary artery calcification assessed by EBCT was correlated with mortality 11). In Japan, however, it is difficult to administer sevelamer hydrochloride to many patients because of constipation as its side effect. Its prescription rate is 26.8% and its single administration rate is only 15.4% 12). We explained fully to the patients that sevelamer hydrochloride seldom caused coronary artery calcification. And we used sorbitol, an osmotic purgatives, with sevelamer hydrochloride. Moreover, we gradually replaced calcium carbonate with sevelamer hydrochloride in supper at first. With protocol above, we succeeded in having 86.7% of the patients take sevelamer hydrochloride 12). We think that it is important to increase the intake rate of sevelamer hydrochloride in order to prevent coronary artery calcification and to aim at the long survival of the patients.

[New therapy strategies in secondary hyperparathyroidism on dialysis (I): new concepts, new treatments]

Secondary hyperparathyroidism (SHP) is still an early and frequent complication of chronic renal disease (CRD). Currently, CRD is an independent cardiovascular risk factor, and calcium-phosphorus metabolism is one of the modifiable related factors. In this first article, we summarize the recent SHP treatment paradigm shift in dialysis patients, derived from the better knowledge and understanding of vascular calcification. We analyze the most recent guidelines (K/DOQI), and describe the general implications of hyperphosphatemia, as well as our therapeutic approach with phosphorus-binders. Since sevelamer additionally presents some pleiotropic effects and it attenuates the progression of vascular calcification, we consider it in the first-line of treatment despite it is not yet demonstrated a survival benefit. We also minimize the use of elemental calcium to a maximum of 1000 to 1500 mg/day. Lanthanum carbonate may well be an important therapeutic agent in the near future, especially if security concerns related to metal accumulation are overcome. Ferric citrate, colestilan and nicotinamide may soon play a role. All these drugs, isolated or in combination, are important in the treatment of SHP since a great deal of its success and the avoidance of some dialysis-related complications depend on an efficient phosphorus control.

Dose-dependent transitions in mechanisms of toxicity: case studies

Experience with dose response and mechanisms of toxicity has shown that multiple mechanisms may exist for a single agent along the continuum of the full dose-response curve. It is highly likely that critical, limiting steps in any given mechanistic pathway may become overwhelmed with increasing exposures, signaling the emergence of new modalities of toxic tissue injury at these higher doses. Therefore, dose-dependent transitions in principal mechanisms of toxicity may occur, and could have significant impact on the interpretation of reference data sets for risk assessment. To illustrate the existence of dose-dependent transitions in mechanisms of toxicity, a group of academic, government, and industry scientists, formed under the leadership of the ILSI Health and Environmental Sciences Institute (HESI), developed a series of case studies. These case studies included acetaminophen, butadiene, ethylene glycol, formaldehyde, manganese, methylene chloride, peroxisome proliferator-activated receptor (PPAR), progesterone/hydroxyflutamide, propylene oxide, vinyl acetate, vinyl chloride, vinylidene chloride, and zinc. The case studies formed the basis for technical discourse at two scientific workshops in 2003.

Efficacy and side-effect profile of sevelamer hydrochloride used in combination with conventional phosphate binders

BACKGROUND

Poor phosphate control is common among patients with end-stage renal disease. Sevelamer hydrochloride has been demonstrated to be a safe and effective phosphate binder when used as a monotherapy. However, cost limits its usefulness in many countries. Data assessing its effectiveness and safety in combination with conventional phosphate binders are lacking.

METHODS

Dialysis patients meeting the following inclusion criteria participated in this study: (i) hyperphosphataemia >1.8 mmol/L (5.6 mg/dL); and (ii) an inability to tolerate currently available binders. The trial was conducted in three phases each lasting 3 months: (i) an observation phase (patients continued on their regular phosphate binders); (ii) a titration phase (sevelamer was added at a dose of 403 mg three times daily with meals, titrated to a maximum of 1209 mg three times daily); and (iii) a maintenance phase.

RESULTS

Twenty-five patients were recruited into the study. Eighteen patients completed all three trial phases. Mean serum phosphate dropped from 2.11 +/- 0.06 mmol/L (6.6 +/- 0.2 mg/dL) during the observation period to 1.91 +/- 0.01 mmol/L (5.9 +/- 0.003 mg/dL) during the maintenance phase (P=0.02). Calcium x phosphate product fell from 5.49 +/- 0.17 mmol2/L2 (68.64 +/- 2.11 mg2 dL2) to 4.89 +/- 0.27 mmol2/L2 (61.36 +/- 3.35 mg2 dL2) (P=0.02). There was no significant change in serum calcium or parathyroid hormone. Total serum cholesterol fell from 3.8 mmol/L (3.4-4.37) 147 mg/dL (131-169) to 3.55 mmol/L (2.97-4.2) 137 mg/dL (115-162) (P=0.02). Serum low-density lipoprotein cholesterol also fell significantly from 1.67 +/- 0.10 mmol/L (65 +/- 4 mg/dL) to 1.52 +/- 0.11 mmol/L (59 +/- 4 mg/dL) (P=0.04). The average prescribed dose of sevelamer was 2.4 g/day. Elemental calcium dropped from 3.4 g/day (1.4 to 4.6) to 1.2 g/day (0.6-2.4) (P=0.04). Seventy-two per cent of patients reported mild flatulence, nausea and indigestion. Three patients discontinued treatment because of adverse effects.

CONCLUSIONS

Sevelamer in combination with conventional phosphate binders is effective in lowering serum phosphate and calcium-phosphate product in patients with refractory hyperphosphataemia. Beneficial effects on lipid profile were also observed. Mild gastrointestinal upset is common.

[Evolution in vitamin D treatment after debut of sevelamer hydrochloride in chronic renal failure patients]

Newly developed sevelamer hydrochlorid (Sev-HCl) has been recognized to show the effective control of the hyperphosphatemia in chronic renal failure patients, without elevation of serum Ca, Mg, and Al as well. Then, Sev-HCl has been expected to evolute the vitamin D treatment, and to reduce the ectopic calcifications through lowering Ca x P products. Although, relatively high frequent abdominal adverse effects in Sev-HCl treatment were reported, including life-threatening bowel occlusions or bowel perforations. It is important to use the appropriate dose of Sev-HCl avoiding the abdominal adverse effects.