13-week dietary toxicity study of ammonium perfluorooctanoate (APFO) in male rats

Ammonium perfluorooctanoate is a perfluorinated carboxylate that is used commercially as a processing aid in the production of fluorinated polymers. Perfluorooctanoate (PFOA) has been found in human blood of the general population from exogenous sources. This report presents the results of a 13-week dietary toxicity study in male rats and was designed to identify potential target organ(s), dose response, and to explore possible relationships of PPARalpha activation to potential liver effects and hormonal changes. Rats were fed dietary levels of 0, 1, 10, 30, and 100 ppm (equivalent to 0, 0.06, 0.64, 1.94, and 6.5 mg/kg/day) for 13 weeks. A control group pair-fed adjusted to the 100 ppm level and groups allowed to recover for 8 weeks were included. Sacrifices were conducted after 4, 7, and 13 weeks of feeding and after 8 weeks of recovery. At each sacrifice, gross and histopathology was conducted on selected tissues and measurements of hepatic palmitoyl CoA oxidase (PCoAO), as well as serum estradiol, luteinizing hormone, testosterone, and PFOA were determined. There were no clinical signs or mortality. Body weight gains were reduced in the 100 ppm dose group. Liver weights (absolute and relative), PCoAO activity, and hepatocyte hypertrophy (minimal to mild) were increased in the 10 ppm dose group and above and were reversible in recovery. Under the study conditions, hormone levels appeared unchanged. PFOA serum concentrations increased in a dose-related fashion, appeared to reach steady-state by test week 5, and declined rapidly through the recovery period. Serum PFOA concentrations at the end of the treatment period were 7.1, 41, 70, and 138 microg/mL in the 1, 10, 30 and 100 ppm dose groups. The study no effect level was 1 ppm (0.06 microg/mg) with doses of 10 ppm (0.64 microg/mg) and higher producing adaptive and reversible liver changes.     

Immune thrombocytopenic purpura - current management practices

The treatment of patients with immune thrombocytopenic purpura (ITP) is changing rapidly, as new agents demonstrate the capability of improving outcomes and decreasing toxicity. Prior to 1981, the only effective treatment options available to increase platelet counts in persons with ITP were corticosteroids and splenectomy. In recent years, intravenous immunoglobulin (IVIg) and intravenous Rh immunoglobulin (IV RhIg) have demonstrated efficacy comparable to that of corticosteroids for increasing platelet counts in ITP. In addition, IVIg and IV RhIg have demonstrated efficacy for maintaining corticosteroid-induced increased platelet counts by periodic infusion, causing a transient impairment of reticuloendothelial clearance function (medical splenectomy). Thus, the time-proven efficacy of corticosteroids for initial treatment of ITP (induction) may now be supplemented with IVIg or IV RhIg infusions for patients requiring ongoing treatment to support a timely and complete steroid taper, while sustaining the increased platelet count (maintenance) with less toxicity. Several investigators have reported that rituximab (anti-CD20) induced sustained remissions with minimal toxicity, in patients with chronic ITP. These reports are promising and, if confirmed, will provide another effective (spleen-sparing) option for managing acute ITP and a long-awaited option for patients who have had a splenectomy and are refractory to conventional agents. Other treatments, including danazol, azathioprine, cyclophosphamide, vinca alkaloids and cyclosporin A, have advocates, but evidence of their efficacy is limited to relatively small and mostly uncontrolled clinical trials. In our opinion, these agents should be reserved for symptomatic thrombocytopenia after refractoriness to corticosteroids, IVIg, IV RhIg, splenectomy and rituximab has been clearly established.     

Use of a modified microplate bioassay method to investigate antibacterial activity in the Peruvian medicinal plant Peperomia galioides

A versatile microplate bioassay for quick and sensitive determination of antibacterial activity was developed for use in screening medicinal plants and identification of their active principles. This assay can be used to determine minimum inhibitory concentrations for small quantities of organic or water-soluble plant extracts. Bioassay-guided fractionation of the stem and leaves of Peperomia galioides using this method found fractions containing grifolin and grifolic acid, which inhibited growth of Staphylococcus aureus and Staphylococcus epidermidis.     

Isolation, structure, absolute stereochemistry, and HIV-1 integrase inhibitory activity of integrasone, a novel fungal polyketide

HIV-1 integrase is a critical enzyme for replication of HIV, and its inhibition is one of the most promising new drug targets for anti-retroviral therapy with potentially significant advantages over existing therapies. In this Note, the isolation, structure elucidation, and absolute stereochemistry of integrasone, a novel polyketide, derived from an unidentified sterile mycelium have been described. This bicyclic dihydroxy epoxide lactone inhibited the strand transfer reaction of HIV-1 integrase with an IC(50) of 41 microM.     

Redirected T-cell cytotoxicity to epithelial cell adhesion molecule-overexpressing adenocarcinomas by a novel recombinant antibody, E3Bi, in vitro and in an animal model

BACKGROUND: To redirect cytotoxic T cells to target a broad range of adenocarcinomas, the authors constructed a novel, recombinant, bispecific antibody, E3Bi, directed at the tumor-associated antigen, epithelial cell adhesion molecule (EpCAM), and the CD3 receptor on T cells. METHODS: T cells were prepared from healthy blood donors. The cytotoxicity of activated T cells (ATC) redirected to tumor cells by E3Bi was measured with in vitro (51)Cr release assays. In vivo studies were performed in a severe combined immunodeficient (SCID)/Beige mouse xenograft model. Tumor-bearing mice were treated with low doses (1 mg/kg) or high doses (10 mg/kg) of E3Bi along with ATC (2 x 10(9) cells/kg), and treatment efficacy was evaluated both by ex vivo tumor cell survival assay after in vivo treatments and by in vivo tumor growth delay studies. RESULTS: In vitro, targeting the EpCAM-overexpressing human tumor cell lines with E3Bi increased specific cytotoxicity of ATC by > 70% at an effector-to-target ratio of 2.5 (P < 0.001); this cytotoxicity was abolished competitively in the presence of an anti-EpCAM monoclonal antibody. In contrast, E3Bi did not enhance ATC cytotoxicity toward the low EpCAM-expressing tumor cell line. In ex vivo tumor cytotoxicity assays, a significant reduction in tumor cell survival (40% with low-dose E3Bi; 90% with high-dose E3Bi) was observed in E3Bi/ATC-treated mice compared with control mice that were treated with ATC only. In addition, SCID/Beige mice xenografted with LS174T tumors demonstrated a significant tumor growth delay (P = 0.0139) after receiving E3Bi/ATC/interleukin 2 (IL-2) compared with mice that received ATC/IL-2 alone. CONCLUSIONS: E3Bi specifically and very efficiently redirected T cells to destroy EpCAM-overexpressing tumors both in vitro and in an animal model. These results suggest a therapeutic utility for E3Bi in the treatment of adenocarcinomas.     

Hepatic artery infusion chemotherapy for metastatic colorectal cancer to the liver at the lahey clinic: comparison between two methods of treatment, surgical versus percutaneous catheter placement

This study updates our experience with hepatic artery infusion chemotherapy for colorectal liver metastases at the Lahey Clinic. It compares surgical versus percutaneous catheter methods, employing an external pump. The surgical series (SS) consisted of 58 patients (1970-1995) treated with floxuridine (FUDR), 20 mg/d for 4 to 5 weeks (modified in 1985; 2-week cycles). Percutaneous series (PS) consisted of 42 patients (1976-1995) treated with fluorouracil (5-FU), 20 mg/d for 10 days followed by a floxuridine (FUDR) schedule as with SS. Analysis consisted of tumor response, survival, and toxicity data between the two methods. Response rates showed no significant difference, SS (34%) and PS (48%) (P = 0.22). There were no significant differences in survival from treatment until death in SS (n = 58) of 13 months versus PS (n = 42) of 10.6 months (P = 0.39), from diagnosis until death, SS being 28.4 months versus PS of 26.4 months (P = 0.71) and from metastases until death, SS being 17.4 months versus PS of 22.2 months (P = 0.35). Hepatic toxicity was similar, but there was increased bone marrow toxicity, mucositis, and diarrhea for the PS. Response rates are similar for both our SS and PS and to that reported in recently randomized surgical trials. Hepatic artery infusion chemotherapy with FUDR by percutaneous catheter placement may be as effective as surgical catheter placement for colorectal liver metastases, but further study is needed.     

SU11752 inhibits the DNA-dependent protein kinase and DNA double-strand break repair resulting in ionizing radiation sensitization

Loss of the DNA-dependent protein kinase (DNA-PK) results in increased sensitivity to ionizing radiation due to inefficient repair of DNA double-strand breaks. Overexpression of DNA-PK in tumor cells conversely results in resistance to ionizing radiation. It is therefore possible that inhibition of DNA-PK will enhance the preferential killing of tumor cells by radiotherapy. Available inhibitors of DNA-PK, like wortmannin, are cytotoxic and stop the cell cycle because they inhibit phoshatidylinositol-3-kinases at 100-fold lower concentrations required to inhibit DNA-PK. In an effort to develop a specific DNA-PK inhibitor, we have characterized SU11752, from a three-substituted indolin-2-ones library. SU11752 and wortmannin were equally potent inhibitors of DNA-PK. In contrast, inhibition of the phoshatidylinositol-3-kinase p110gamma required 500-fold higher concentration of SU11752. Thus, SU11752 was a more selective inhibitor of DNA-PK than wortmannin. Inhibition kinetics and a direct assay for ATP binding showed that SU11752 inhibited DNA-PK by competing with ATP. SU11752 inhibited DNA double-strand break repair in cells and gave rise to a five-fold sensitization to ionizing radiation. At concentrations of SU11752 that inhibited DNA repair, cell cycle progression was still normal and ATM kinase activity was not inhibited. We conclude that SU11752 defines a new class of drugs that may serve as a starting point for the development of specific DNA-PK inhibitors.