PubMed · 6570578
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P Benoit, A Peutillot. 1984. [Rivotril].. https://pubmed.ncbi.nlm.nih.gov/6570578/
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A gas chromatography-tandem mass spectrometry method for detection of diazepam, nordazepam and oxazepam is presented. The method associates electron capture ionization and multiple reaction monitoring (MRM). No derivatization is performed; oxazepam undergoes thermal degradation during chromatographic injection and is thus quantified via its decomposition product. The negative molecular ions are so stable that they do not dissociate when collision is performed under "classical" conditions (i.e. with argon as collision gas). With xenon as collision gas, the energy transfer is sufficient to provide two product ions for diazepam and nordazepam and one product ion for the decomposition product of oxazepam. The sample preparation part involves liquid/liquid extraction with TOXI-TUBES A extraction tubes; it provides recovery yields between 68 and 95%, depending of the benzodiazepine considered, with coefficients of variation below 6% for 10 samples. The applicability of the method was demonstrated on urine extracts. From 1 mL of urine, the method provides quantitation limits of 0.15 ng/mL for diazepam, 1.0 ng/mL for nordazepam and 1.5 ng/mL for oxazepam. Mechanisms of dissociation of M*(-) ions of benzodiazepines are suggested.
Focal adhesion kinase (FAK) is suggested to be intimately involved in the progression of malignancies. Our previous research has demonstrated that activation of cholecystokinin-2 receptor (CCK2R) by gastrin stimulates a rapid activation of FAK pathway in human colon cancer cells. The purpose of this study is to determine the role of CCK2R and FAK in the progression of colon cancer. In this study, matched tissue samples of primary colon cancer and adjacent normal colon mucosa from the same patient were collected from 45 patients with colon cancer undergoing surgical resection. The gastrin expression was detected using reverse transcription polymerase chain reaction (RT-PCR). The CCK2R expression was examined by in situ hybridization and RT-PCR. The expression of FAK and phosphorylated FAK at tyrosine 397 (phospho-FAK) were detected using immunohistochemistry and immunoblotting. Colo320 and SW787, 2 colon cancer cell lines with or without CCK2R expression, were recruited in this study. Antisense oligonucleotide of FAK was used to block the expression of FAK. Invasiveness and motility of colon cancer cells were detected by Boyden chamber. In this series, enhanced expression of gastrin, CCK2R, FAK and phospho-FAK were observed in colon cancer tissues. CCK2R expression correlated with expression of phospho-FAK. Coexpression of CCK2R and phospho-FAK associated with invasion and lymph node metastasis. Increased invasion and motility was induced by gastrin in Colo320 cells. Overexpression of CCK2R by stable transfection of CCK2R plasmid amplified this increase and incubation with 1 microM L-365,260, a specific CCK2R antagonist, completely inhibited the effect of gastrin. FAK antisense largely blocked the increase of invasion and motility in Colo320 cells. Our data represent the evidence for the CCK2R regulating invasion and motility of colon cancer cells, and support a role of CCK2R in the progression of colon cancer. FAK play a critical role in this CCK2R-mediated effect.
SJG-136 is a new pyrrolobenzodiazepine dimer inducing time-dependent cytotoxicity. HCT 116 cells were exposed to 50 nmol/L of SJG-136 for 1 hour or 1 nmol/L of SJG-136 for 24 hours to achieve similar levels of interstrand cross-links (ICL). The short exposure led to a rapid formation of ICLs (1 hour), early H2AX foci formation (4 hours), prominent S phase arrest, and greater phosphorylation of Nbs1 (on serine 343) and Chk1 (on serine 317) than a 24-hour exposure. The prolonged exposure at low concentrations of SJG-136 induced a gradual formation of ICLs (up to 24 hours) which was associated with a limited S phase arrest and delayed Nbs1 phosphorylation. Prolonged exposure was also associated with a reduced phosphorylation of p53 on serines 15 and 20, a limited and delayed phosphorylation on serine 392, and a less prominent increase in p21 levels. These data suggest that the 24-hour exposure to a low concentration of SJG-136 led to delayed and reduced DNA damage signaling compared with a higher concentration of SJG-136 for 1 hour, resulting in greater cytotoxicity and contributing to the time-dependent cytotoxic effect of SJG-136.