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Screening Step (screening + step)
Selected AbstractsUsing serum pepsinogens wisely in a clinical practiceJOURNAL OF DIGESTIVE DISEASES, Issue 1 2007Kazumasa MIKI Serum pepsinogen (PG) has been used as biomarkers of gastric inflammation and mucosal status, including atrophic change, before the discovery of Helicobacter pylori (H. pylori). Serum pepsinogen I (PG I) and pepsinogen II (PG II) levels are known to increase in the presence of H. pylori -related nonatrophic chronic gastritis. The measurement of serum PG provides much information on the presence of intestinal metaplasia as well as atrophic gastritis. The eradication of H. pylori provokes a significant change in serum PG values: it reduces both PG I and PG II and elevates the PG I to PG II ratio. Recently, the serum PG test method has been the first screening step in Japan, as well as photofluorography. Serum PG tests are used to screen for high risk subjects with atrophic gastritis, rather than as a test for cancer itself. Unlike photofluorography or endoscopy, serum PG screening can identify non-ulcerated differentiated asymptomatic cancer, irrespective of the size and location of the lesion. Most cases detected by the PG method are asymptomatic early gastric cancers and are limited to the mucosa, which are particularly well suited for endoscopic treatment. The PG method can contribute greatly to the patients' quality of life. [source] High-throughput determination of the free fraction of drugs strongly bound to plasma proteinsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2004Joachim Schuhmacher Abstract Quantification of protein binding of new chemical entities is an important early screening step during drug discovery and is of fundamental interest for the estimation of safety margins during drug development. In this publication, we describe the development of a new high-throughput assay for the determination of the free drug fraction in plasma (fu). The new technique is an enhancement of the previously published erythrocytes partition method. It is based on the distribution of drugs between plasma water, plasma proteins, and solid-supported lipid membranes (Transil®). The execution of protein binding studies by partitioning is dramatically simplified by substituting erythrocytes with commercially available Transil® beads, and makes the method particularly suitable for high-throughput studies. Eight Bayer compounds from different compound classes covering a wide range of lipophilicities (log P,=,1.9,5.6) and fu values (0.018,35%) were selected for validation of the assay. The results obtained by the new method and by either the erythrocytes partitioning technique or more conventional methods (ultrafiltration and equilibrium dialysis) are identical, confirming that the new method produces valid results even for drugs that are strongly bound to plasma proteins. Precision and accuracy of the data in the cases of very low and high fu values are comparable, indicating that the method is especially suited for highly lipophilic drugs that tend to adsorb to surfaces compared with other methods, like ultrafiltration or equilibrium dialysis, that may produce biased data. The method is also useful for the determination of binding parameters and the pH dependence of fu. In summary, this assay is well suited for high-throughput determination of protein binding during drug discovery and for extended protein binding studies during drug development. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93: 816,830, 2004 [source] Construction and evaluation of a porcine bacterial artificial chromosome libraryANIMAL GENETICS, Issue 1 2000K Suzuki Summary A porcine bacterial artificial chromosome (BAC) library consisting of 103 488 clones has been constructed. The average insert size in the BAC vector was calculated to be 133 kb based on the examination of 189 randomly selected clones, indicating that the library contained 4.4 genome equivalents. The library can be screened by two-step PCR. The first screening step is performed on 22 superpools, each containing 4704 clones (49×96 well plates). In the second screening step, 49 plates comprising a superpool are arrayed in a 7×7 matrix and 4D-PCR is performed. Screening of the library superpools by PCR for 125 marker sequences selected from different regions of swine genome revealed 123 sequences, indicating that the library is not biased. Subsequent screenings (4D-PCR) were successfully applied for identification of clones containing each marker sequence. This porcine BAC library and the PCR screening system are useful for isolation of genomic DNA fragments containing desired sequences. [source] Pharmacological and pharmacokinetic evaluation of celecoxib prodrugs in ratsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2002Rao N.V.S. Mamidi Abstract This study demonstrates the utility of an in vitro , in vivo correlative approach in the selection and optimization of a prodrug candidate of celecoxib (CBX), a COX2 inhibitor. As an initial screening step, a comparative single oral dose pharmacokinetic study was conducted in rats for CBX and its three aliphatic acyl water-soluble prodrugs viz., CBX-acetyl (CBX-AC), CBX-propionyl (CBX-PR) and CBX-butyryl (CBX-BU) at high equimolar dose, 100 mg/kg. Only CBX-BU and CBX-PR converted rapidly to CBX and yielded approximately five-fold greater systemic exposure of CBX than CBX alone or CBX-AC. Rank order of systemic exposure of prodrugs in its intact form was CBX-AC >CBX-PR >CBX-BU. Further in vitro hydrolysis studies of CBX prodrugs in intestinal mucosal suspensions and liver homogenates indicated that CBX-BU is rapidly and completely converted to CBX, whereas CBX-PR and CBX-AC require longer incubation period for complete conversion to CBX. There was a very good correlation of the in vitro and in vivo data supporting CBX-BU as the prodrug of choice. Further in vitro pharmacological studies showed that COX2 selective inhibition is improved for CBX-BU as compared to CBX-AC and CBX-PR. Dose proportionality in pharmacokinetic studies of CBX-BU and CBX at equimolar oral doses confirmed that relative oral bioavailability of CBX was improved following CBX-BU administration and there was linearity in pharmacokinetics of CBX over a wide dose range (10,100 mg/kg), whereas CBX in its conventional form showed poor bioavailability and lack of dose linearity in pharmacokinetics. The oral bioavailability of CBX from CBX-BU was dose independent and was in the range 78,96%. At a 50% reduced molar dose, CBX-BU showed an equivalent efficacy to that of CBX in the in vivo carrageenan model. Based on the study, water-soluble CBX-BU prodrug can be considered for clinical development in view of its potential advantages.Copyright © 2002 John Wiley & Sons, Ltd. [source] Optimization of medium composition for the production of antimicrobial activity by Bacillus subtilis B38BIOTECHNOLOGY PROGRESS, Issue 5 2009Olfa Tabbene Abstract An antimicrobial activity produced by Bacillus subtilis B38 was found to be effective against several bacteria, including pathogenic and spoilage microorganisms such as, Listeria monocytogenes, Salmonella enteridis, and clinical isolates of methicillin-resistant Staphylococcus species. Nutrients such as carbon, nitrogen sources, and inorganic salts enhanced the production level of the antibacterial activity by B. subtilis B38. A first screening step showed that lactose, ammonium succinate, and manganese most influenced both cell growth and antibacterial activity production. These three factors varied at two levels in eight experiments using full factorial design. Results indicated that maximum cell growth (OD = 10.2) and maximum production of antibacterial activity (360 AU/mL) were obtained in a modified medium containing 1.5% (w/v) lactose, 0.15% (w/v) ammonium succinate, and 0.3 mg/L manganese. Depending on the indicator strain used, the antibacterial activity was 2- to 4-fold higher in the modified culture medium than in TSB medium under the same conditions. Thin layer chromatography-bioautography assay showed the presence of three active spots with Rf values of 0.47, 0.7, and 0.82 in TSB medium. However, the inhibition zone of two spots (Rf values of 0.7 and 0.82) was slightly larger in the modified medium. Moreover, a large zone of inhibition with an Rf value of 0.3, was observed in this modified medium, instead of the spot having an Rf value of 0.47. These results suggest that the nutrients act as environmental factors, quantitatively and qualitatively affecting the production of antibacterial compounds by B. subtilis B38. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | |||||||||||||