GMDTC Chelating Agent Attenuates Cisplatin-Induced Systemic Toxicity without Affecting Antitumor Efficacy.

Cisplatin is a platinum-based chemotherapeutic drug widely used in the treatment of various cancers such as testicular, ovarian, lung, bladder, and cervical cancers. However, its use and the dosage range applied have been limited by severe side effects (e.g., nephrotoxicity and ototoxicity) and by the development of resistance to cisplatin in patients during treatment. Metal chelators have shown promising potential in overcoming these problems often associated with platinum drugs. Previously, a new chelating agent, sodium (S)-2-(dithiocarboxylato((2S,3R,4R,5R)-2,3,4,5,6-pentahydroxyhexyl)amino)-4(methylthio)butanoate (GMDTC), was developed. In this study, we examined the effect of GMDTC in modifying cisplatin-induced toxicities following in vitro and in vivo exposures. GMDTC treatment dramatically reduced cisplatin-induced apoptosis and cytotoxicity in HK2 cells by decreasing the amount of intracellular platinum. In the 4T1 breast cancer mouse model, GMDTC reduced cisplatin-induced nephrotoxicity by reducing cisplatin deposition in the kidney. GMDTC attenuated cisplatin-induced elevations in blood urea nitrogen and plasma creatinine, ameliorated renal tubular dilation and vacuolation, and prevented necrosis of glomeruli and renal tubular cells. GMDTC also inhibited cisplatin-induced ototoxicity as shown by improved hearing loss which was assessed using the auditory brainstem response test. Furthermore, GMDTC attenuated cisplatin-induced hematotoxicity and hepatotoxicity. Importantly, co-treatment of cisplatin with GMDTC did not affect cisplatin antitumor efficacy. Tumor growth, size, and metastasis were all comparable between the cisplatin only and cisplatin-GMDTC co-treatment groups. In conclusion, the current study suggests that GMDTC reduces cisplatin-induced systemic toxicity by preventing the accumulation and assisting in the removal of intracellular cisplatin, without compromising cisplatin therapeutic activity. These results support the development of GMDTC as a chemotherapy protector and rescue agent to overcome the toxicity of and resistance to platinum-based antineoplastic drugs.

Mapping dynamic histone modification patterns during arsenic-induced malignant transformation of human bladder cells.

Arsenic is a known potent risk factor for bladder cancer. Increasing evidence suggests that epigenetic alterations, e.g., DNA methylation and histones posttranslational modifications (PTMs), contribute to arsenic carcinogenesis. Our previous studies have demonstrated that exposure of human urothelial cells (UROtsa cells) to monomethylarsonous acid (MMAIII), one of arsenic active metabolites, changes the histone acetylation marks across the genome that are correlated with MMAIII-induced UROtsa cell malignant transformation. In the current study, we employed a high-resolution and high-throughput liquid chromatography tandem mass spectrometry (LC-MS/MS) to identify and quantitatively measure various PTM patterns during the MMAIII-induced malignant transformation. Our data showed that MMAIII exposure caused a time-dependent increase in histone H3 acetylation on lysine K4, K9, K14, K18, K23, and K27, but a decrease in acetylation on lysine K5, K8, K12, and K16 of histone H4. Consistent with this observation, H3K18ac was increased while H4K8ac was decreased in the leukocytes collected from people exposed to high concentrations of arsenic compared to those exposed to low concentrations. MMAIII was also able to alter histone methylation patterns: MMAIII transformed cells experienced a loss of H3K4me1, and an increase in H3K9me1 and H3K27me1. Collectively, our data shows that arsenic exposure causes dynamic changes in histone acetylation and methylation patterns during arsenic-induced cancer development. Exploring the genomic location of the altered histone marks and the resulting aberrant expression of genes will be of importance in deciphering the mechanism of arsenic-induced carcinogenesis.

Determination of Arbutin in Rat Plasma Using Liquid Chromatography-Tandem Mass Spectrometry: Application to a Pharmacokinetic Study After Oral Administration of the Extract of Vaccinium vitis-idaea.

A rapid and sensitive bioassay based on liquid chromatography-tandem mass spectrometry (LC-MS-MS) has been developed and validated to measure arbutin in rat plasma. Sample preparation of plasma after the addition of indapamide as internal standard (IS) involved solid-phase extraction (SPE) on C18 cartridges. Reversed-phase chromatography using acetonitrile and 0.5% formic acid solution (pH 2.56) was used for separation in a run time of 4.0 min. The analytes were detected in the negative ion mode using selective reaction monitoring (SRM) of the transitions at m/z 271.2 → 107.8 for arbutin and 364.3 → 189.0 for indapamide. The method has the following performance characteristics: a reliable response range of 7.5-5250.0 ng/mL with correlation coefficients (r) of >0.995. The lower limit of quantitation (LLOQ) was 7.5 ng/mL. The intra- and inter-day precision and accuracy of the quality control (QC) samples at low, medium and high concentration levels showed ≤8.79% relative standard deviation (RSD) and -1.15 to 1.49% relative error (RE). The method was successfully applied to a pharmacokinetic study to measure arbutin in rats after extracts of Vaccinium vitis-idaea was orally administered.

[Research on the influence of LED temperature shifts on differential optical absorption spectroscopy for measuring NO2].

Influences of LEDs (without etalon structure and center wavelengths are respectively 370 nm (near-UV), 452 nm (blue) and 660 nm(red)) temperature shifts on differential optical absorption spectroscopy(DOAS) for measuring NO2 were studied. NO2 absorption spectra were formed using LED emitting spectra at 10 degrees C. The measured LED spectra at other temperatures were used as reference spectra of DOAS. Thus, NO2 differential optical densities under different LED temperature shifts were acquired and then NO2 differential cross-sections were fitted to the acquired differential optical densities. From fitting results, the linear relations of 0.995, 0.945 and 0.989 correlation between delta of fitting residual and near-UV, blue and red LEDs temperature shifts were found and their slopes are respectively 1.12 x 10(-3), 5.25 x 10(-5) and 7.45 x 10(-4) degrees C(-1). The fitting results show that the influence of temperature shifts of blue LED on DOAS retrieval is negligible and the temperature shifts of near-UV and red LED are impressible to DOAS measurement resulting in degradation of detection sensitivity. The retrieval results of blue LED with and without etalon with similar temperature properties were compared and showed that etalon of LED will greatly increase the influence of temperature shifts of LED on DOAS retrieval.

[BTX monitoring nearby main road traffic in Guangzhou].

In order to study the levels of BTX (benzene, toluene, xylene, etc) nearby the main roads of Guangzhou from November 2010 to December 2010 during the Asian Games, BTX and conventional pollutants such as NO2, O3 in the air were monitored by the DOAS system nearby Huangsha Road, which is in the Liwan District of Guangzhou City. The results showed that, during the entire period, BTX showed a high concentration in the evening and the average concentrations of benzene, toluene, p-xylene, m-xylene and phenol were 15.9 microg x m(-3), 61.3 microg x m(-3), 6.5 microg x m(-3), 16.9 microg x m(-3), 0.88 microg x m(-3), respectively. The average concentrations of benzene and toluene were close to those in other cities, and the ratio of toluene to benzene was in range of 1.2-6.16. Throughout the monitoring period, the correlation coefficient of benzene and toluene was 0.86 and it rose to 0.985 during the high concentration period, indicating that they had the same source in this region. The correlation coefficient between toluene and CO was 0.78, indicating that traffic emissions was the major source of benzene and toluene. Based on the combination of wind speed, wind direction and other meteorological data, it was found that the weather condition was an important factor which affected the BTX concentration, and some possible point sources were suggested nearby the site.