Integratie van biorelevantie in de absorptie profilering van slecht in water oplosbare geneesmiddelen

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Relationship between bile salts, bacterial translocation, and duodenal mucosal integrity in functional dyspepsia

BACKGROUND: Functional dyspepsia (FD) is a complex disorder, in which multiple mechanisms underlie symptom generation, including impaired duodenal barrier function. Moreover, an altered duodenal bile salt pool was recently discovered in patients with FD. We aimed to evaluate the relationship between bile salts, bacterial translocation, and duodenal mucosal permeability in FD. METHODS: Duodenal biopsies from patients with FD and healthy volunteers (HV) were mounted in Ussing chambers to measure mucosal resistance and bacterial passage in the absence and presence of fluorescein-conjugated Escherichia coli and glyco-ursodeoxycholic acid (GUDCA) exposure. In parallel, duodenal fluid aspirates were collected from patients and bile salts were analyzed. KEY RESULTS: The transepithelial electrical resistance of duodenal biopsies from patients was lower compared with HV (21.4 ± 1.3 Ω.cm2 vs. 24.4 ± 1.2 Ω.cm2 ; P = .02; N = 21). The ratio of glyco-cholic and glyco-chenodeoxycholic acid (GCDCA) to tauro- and GUDCA correlated positively with transepithelial electrical resistance in patients. Glyco-ursodeoxycholic acid slightly altered the mucosal resistance, resulting in similar values between patient and healthy biopsies (22.1 ± 1.0 Ω.cm2 vs. 23.0 ± 1.0 Ω.cm2 ; P = .5). Bacterial passage after 120 minutes was lower for patient than for healthy biopsies (0.0 [0.0-681.8] vs. 1684.0 [0.0-4773.0] E coli units; P = .02). Glyco-ursodeoxycholic acid increased bacterial passage in patient biopsies (102.1 [0.0-733.0] vs. 638.9 [280.6-2124.0] E coli units; P = .009). No correlation was found between mucosal resistance and bacterial passage. CONCLUSIONS & INFERENCES: Patients with FD displayed decreased duodenal mucosal resistance associated with bile salts, however, not associated with bacterial passage in vitro. In addition, the hydrophilic bile salt glyco-ursodeoxycholic acid abolished differences in mucosal resistance and bacterial passage between patient and control group.status: publishe

Non-P-glycoprotein mediated mechanism for multidrug resistance precedes P-glycoprotein expression during in vitro selection for doxorubicin resistance in a human lung cancer cell line

Two different mechanisms that contribute to multidrug resistance (MDR) were found in derivatives of the human squamous lung cancer cell line SW-1573. The parental cell line has a low amount of mdr1 P-glycoprotein mRNA. In three independent selections for doxorubicin resistance, MDR variants arose in which mdr1 P-glycoprotein mRNA and protein was not detectable. Selection on higher doxorubicin concentrations gave rise to variants containing high levels of mdr1 mRNA, due to transcriptional activation of the mdr1 gene. Upon continued selection for higher levels of doxorubicin resistance, the mdr1 gene became amplified, resulting in an additional increase in the level of mdr1 mRNA. The cross-resistance pattern of the sublines that lack mdr1 P-glycoprotein expression is different from that seen in the mdr1 overexpressing cells. Both types of MDR cell lines are resistant to doxorubicin, daunorubicin, etoposide, colchicine, gramicidin D, and vincristine. However, in the non-P-glycoprotein-mediated MDR cell lines, resistance levels are lower and a preferential resistance for etoposide is see

LC-MS/MS Analysis of Bile Acids in In Vitro Samples

Over the last decade, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become the method of choice for the quantification of bile acids (BA) and their conjugates in different matrices, such as plasma, blood, urine, and cell lysates. Numerous reports have indeed been published describing methods for quantitative determination of bile acids in plasma samples obtained during in vivo studies. However, information on bioanalytical methods suitable for determination of bile acids in in vitro samples remained scarce. Therefore, we presently report a simple and accurate LC-MS/MS method for the quantification of BA in cells (e.g., cultured human hepatocytes) and corresponding cell culture medium, obtained during in vitro experiments.status: publishe