New α-lipoic acid derivative, DHL-HisZn, ameliorates renal ischemia-reperfusion injury in rats.

BACKGROUND: Ischemia-reperfusion (I/R) occurs frequently in a variety of clinical settings, such as renal transplantation. In addition, I/R is a major cause of acute kidney injury (AKI). A recent study has reported that reactive oxygen species (ROS) are important mediators of AKI, suggesting that reducing ROS generation may prevent renal injury. The present study evaluated the ability of DHL-HisZn, a new α-lipoic acid derivative, to inhibit ROS generation and prevent renal I/R injury in rats. MATERIALS AND METHODS: Rats received an intravenous infusion of DHL-HisZn or saline, and then underwent experimentally induced renal I/R injury or sham treatment. Rats were sacrificed after 60 min of ischemia and 24 h of reperfusion. To evaluate the renal protective effects of DHL-HisZn, serum blood urea nitrogen (BUN) and creatinine (Cre) concentrations were determined, kidneys were histologically assessed, and malondialdehyde (MDA), a biomarker of oxidative stress, was evaluated. In addition, antimycin A (AMA)-stimulated RAW264.7 cells were treated with DHL-HisZn to assess its antioxidant effects in vitro. RESULTS: DHL-HisZn treatment attenuated I/R-induced histologic alterations, reduced serum levels of serum BUN and Cre, and decreased MDA levels in the kidneys of rats with renal I/R injury. Furthermore, DHL-HisZn decreased ROS levels in AMA-stimulated RAW264.7 cells. CONCLUSIONS: Our in vitro and in vivo findings suggest that DHL-HisZn may have therapeutic potential against various human I/R conditions.

Development and validation of sensitive and selective quantification of total and free daptomycin in human plasma using ultra-performance liquid chromatography coupled to tandem mass spectrometry.

Recently, several studies on pharmacokinetics parameters of daptomycin reported that plasma trough concentration was linked to efficacy and adverse effects, suggesting the usefulness of therapeutic drug monitoring. Although some methods for determining total daptomycin concentration using liquid chromatography coupled to tandem mass spectrometry were established previously, no sensitive quantification method for free drug concentration was established. In this study, we aimed to develop a quantitative method of measuring both total and free daptomycin concentrations using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS), by which both trough and maximum concentrations can be measured. Plasma samples were prepared by solid phase extraction. Free fractions were obtained by ultrafiltration. The assay fulfilled the requirements of US Food and Drug Administration and the European Medicines Agency for assay validation. The methods for total and free drug showed good fit over wide ranges of 0.5-200 and 0.04-40 µg/mL, with lower limits of quantitation of 0.5 and 0.04 µg/mL, respectively. Recovery rate of free daptomycin from ultrafiltration was approximately 100%. Extraction recovery rates of total and free drug measurements ranged from 57.1 to 67.4% and 54.6 to 62.3%, while matrix effect varied between 111.9 and 118.7% and 104.0 and 127.1%, respectively. The maximum and trough concentrations of total and free daptomycin in plasma from two patients in intensive care unit were successfully determined, demonstrating the feasibility of clinical application of the novel methods for determining plasma total and free daptomycin concentrations. In conclusion, we succeeded to develop a sensitive and selective method using UPLC-MS/MS for quantitative measurement of total and free daptomycin concentrations in plasma.

Clinical impact of thymidine phosphorylase expression in gastric cancer.

Thymidine phosphorylase (dThdPase) is an enzyme that is involved in pyrimidine nucleoside metabolism and DNA synthesis and converts 5'-deoxy-5-fluorouridine (5'-DFUR) to 5-fluorouracil (5-FU). The aim of this study was to elucidate the relationship between dThdPase expression and biological malignancy, prognosis, and sensitivity to postoperative chemotherapy, using immunohistochemical staining. We studied 148 patients with gastric cancer who underwent surgery at Department of Surgery II in Oita Medical University between 1990 and 1999. Immunohistochemical expression of dThdPase was correlated to clinicopathological factors and postoperative survival. Tumor tissue was dThdPase-positive in 112 patients. The results suggested a relationship between the degree of histological differentiation and dThdPase expression (p=0.0697). Examination of dThdPase expression based on the site of the tumor revealed that the groups with upper or lower gastric cancer included a significantly greater number of dThdPase-positive patients (p=0.0011). Analysis of the patients as a whole showed no significant difference between the survival. In the chemotherapy group, the dThdPase-positive patients tended to have a more favorable prognosis than the dThdPase-negative patients (p=0.0578). The results suggest that postoperative adjuvant chemotherapy that makes use of FU metabolic pathways may improve prognosis in patients with dThdPase-positive gastric cancer.

The new vitamin E derivative, ETS-GS, protects against cecal ligation and puncture-induced systemic inflammation in rats.

Sepsis-related systemic inflammation frequently occurs in the critical care setting. Systemic inflammation is implicated in the progression of organ injury, which is associated with a high mortality rate. Recently, vitamin E and glutamic acid have been reported to attenuate inflammation. We therefore investigated whether the vitamin E derivative, ETS-GS, could inhibit the secretion of cytokines and high-mobility group box 1 (HMGB1), and thereby reduce organ damage in a rat model of cecal ligation and puncture (CLP)-induced sepsis. Male Wistar rats weighing 250-300 g were used. Rats received water or ETS-GS (10 mg/kg) by oral administration for 3 weeks, and then sepsis was induced by CLP under sevoflurane anesthesia. Serum levels of interleukin-6, tumor necrosis factor-α, and HMGB1 were determined at 3, 6, and 12 h after CLP; lung histology was assessed at 12 h. Histology results showed markedly reduced interstitial edema and leukocytic infiltration in lung tissue harvested at 12 h in ETS-GS-treated mice compared with untreated controls. ETS-GS treatment also attenuated the CLP-induced increase in serum levels of cytokines and HMGB1. To investigate the mechanisms by which ETS-GS exerts its anti-inflammatory effects, the phosphorylation of Akt, IκBα, and mitogen-activated protein kinase (MAPK) was assessed in mouse macrophage RAW264.7 cells stimulated with LPS, with and without ETS-GS. In these in vitro studies, ETS-GS-induced phosphoinositide 3-kinase (PI3K)-Akt phosphorylation and inhibited IκBα and MAPK phosphorylation. ETS-GS blocked the CLP-induced septic shock response and protected against acute lung injury. This mechanism appeared to be mediated by the induction of PI3K-Akt and the inhibition of IκBα and MAPK phosphorylation. Given these results, ETS-GS shows promise as a potential therapeutic agent for sepsis.