Use of a Bile Salt Export Pump Knockdown Rat Susceptibility Model to Interrogate Mechanism of Drug-Induced Liver Toxicity.

Inhibition of the bile salt export pump (BSEP) may be associated with clinical drug-induced liver injury, but is poorly predicted by preclinical animal models. Here we present the development of a novel rat model using siRNA knockdown (KD) of Bsep that displayed differentially enhanced hepatotoxicity to 8 Bsep inhibitors and not to 3 Bsep noninhibitors when administered at maximally tolerated doses for 7 days. Bsep KD alone resulted in 3- and 4.5-fold increases in liver and plasma levels, respectively, of the sum of the 3 most prevalent taurine conjugated bile acids (T3-BA), approximately 90% decrease in plasma and liver glycocholic acid, and a distinct bile acid regulating gene expression pattern, without resulting in hepatotoxicity. Among the Bsep inhibitors, only asunaprevir and TAK-875 resulted in serum transaminase and total bilirubin increases associated with increases in plasma T3-BA that were enhanced by Bsep KD. Benzbromarone, lopinavir, and simeprevir caused smaller increases in plasma T3-BA, but did not result in hepatotoxicity in Bsep KD rats. Bosentan, cyclosporine A, and ritonavir, however, showed no enhancement of T3-BA in plasma in Bsep KD rats, as well as Bsep noninhibitors acetaminophen, MK-0974, or clarithromycin. T3-BA findings were further strengthened through monitoring TCA-d4 converted from cholic acid-d4 overcoming interanimal variability in endogenous bile acids. Bsep KD also altered liver and/or plasma levels of asunaprevir, TAK-875, TAK-875 acyl-glucuronide, benzbromarone, and bosentan. The Bsep KD rat model has revealed differences in the effects on bile acid homeostasis among Bsep inhibitors that can best be monitored using measures of T3-BA and TCA-d4 in plasma. However, the phenotype caused by Bsep inhibition is complex due to the involvement of several compensatory mechanisms.

Image-guided drainage of tuboovarian abscesses of gastrointestinal or genitourinary origin: a retrospective analysis.

PURPOSE: To analyze the authors' success with image-guided drainage of tuboovarian abscesses (TOAs). MATERIALS AND METHODS: Retrospective analysis of patients with image-guided TOA drainage from 1999 to 2008 was performed. Patient recovery without salpingo-oophorectomy was considered clinical success. A total of 57 TOAs were drained in 49 female patients (mean age, 43; range, 12 to > 89). RESULTS: Thirty-three (58%) TOAs were drained percutaneously using computed tomography guidance and 24 were ultrasound guided (21 transvaginally, three transabdominally). Fifty-three TOAs were drained with catheter placement, and four were drained with aspiration alone. Abscess etiologies include pelvic inflammatory disease (n = 21, 37%), gastrointestinal conditions related (n = 21, 37%), gynecologic surgery (n = 8, 14%), and other (12%). Image-guided drainage resolved TOAs without salpingo-oophorectomy in 74% of cases overall (42 of 57) and 88% (29 of 33) of gynecologic-related cases, including 95% (20 of 21) of pelvic inflammatory disease cases. Salpingo-oophorectomy was performed more often in gastrointestinal-related cases (10 of 21, 48%) than for all other causes (five of 36, 14%; P < .001), with concurrent bowel surgery performed in the majority of the gastrointestinal-related cases. Mean follow-up after image-guided drainage was 48 months (range, 1-113) in patients who did not have related surgery. In patients who underwent salpingo-oophorectomy, it was performed on average 2.2 months (range, 0.5-5) after initial drainage. Two minor complications occurred; both involved catheter transgression of the urinary bladder in patients with transvaginal ultrasound-guided drainages. The patients were successfully treated conservatively with Foley catheter bladder decompression, without prolonged hospitalization. CONCLUSIONS: TOAs, especially of gynecologic origin, can often be managed successfully with image-guided drainage. After image-guided drainage, patients with gynecologic-related TOA were less likely to undergo salpingo-oophorectomy than patients with gastrointestinal-related TOAs.

Intramolecular cross-linking experiments on cytochrome c and ribonuclease A using an isotope multiplet method.

Mass spectral analysis of tryptic digests of cross-linked proteins offers considerable promise as a simple technique to probe protein structure and study protein-protein interactions. We describe the use of a 1:1 mixture of isotopically labeled and unlabeled cross-linkers, disuccinimidyladipate (DSA) and dimethyladipimidate (DMA), to enhance visualization of cross-linked peptides in a tryptic digest. Optimized intramolecular reactions of cytochrome c and ribonuclease A (RNase A) with DSA yielded an average of two cross-links per protein molecule. After digestion of the cross-linked cytochrome c with trypsin and analysis by liquid chromatography/mass spectrometry (LC/MS) and matrix-assisted laser desorption/ionization (MALDI), eight modified peptides, five cross-linked and two end-capped, were detected by virtue of their doublet character. An eighth modified peptide's identity remained ambiguous because of its inability to fragment. The lysine-lysine distance constraints obtained are discussed in the context of the known NMR and X-ray structures of cytochrome c. Analysis of cross-linked RNase A by LC/MS and MALDI yielded nine modified peptides, four of which were modified twice, as indicated by the isotopic triplets. Although seven of these peptides contained cross-links, few distance constraints were gained due to the fact that the cross-linked products were variations of modification of the same three lysine residues.