Applied Biosystems

About: Applied Biosystems is a based out in . It is known for research contribution in the topics: Mass spectrometry & Nucleic acid. The organization has 1521 authors who have published 1579 publications receiving 285423 citations.

Tuning compounds for electrospray ionization/in-source collision-induced dissociation and mass spectra library searching

Abstract: Tuning compounds for positive and negative electrospray ionization (ESI) were tested for the tuning of in-source collision-induced dissociation (ESI/CID) with three types of SCIEX API instruments (API 365, 2000 and 3000) in the single-quadrupole mode. The vacuum interfaces of these instruments differ slightly in geometry, but the principles of ionization and solvent evaporation by nebulizer and curtain gases, orifice and skimmer are identical. For comparison of in-source CID, breakdown curves of haloperidol, paracetamol, metronidazole and metamizole were acquired by increasing the orifice voltages. The API 2000 and 3000 required higher orifice voltages than did the API 365 to induce a similar degree of fragmentation of the protonated or deprotonated molecules to characteristic fragment ions. This increase of orifice voltage could be demonstrated with each of the four compounds tested by a shift of the maxima of the breakdown curves to higher orifice voltages. A procedure with three collision energy (CE) levels for drug identification with a mass spectra library set up with an API 365 therefore required an adjustment of the orifice voltages to higher values when being transferred to an API 2000 or API 3000. The corresponding orifice voltages for the three instruments were 20/50/80 V (API 365), 30/90/130 V (API 2000) and 40/80/120 V (API 3000). However, a change in orifice voltage of +/-10 V (with the API 2000 and 3000) hardly influenced the fit values of a library search for each single CE level. For adjusting orifice voltages with different instruments, a tuning procedure with haloperidol and paracetamol is presented. With this tuning procedure an ESI/CID mass spectra library set up for API 365 and API 150 could also be used for drug identification with an API 2000 and an API 3000 with good library search results.

Time-delay integration in electrophoretic detection systems

Abstract: An apparatus for detecting analytes in a sample is provided. The apparatus includes: one or more channels (10) having a detection zone (14); one or more irradiation sources (16) disposed for irradiating the detection zone (14) with non-coherent radiation; a detector array (34) disposed for collecting light signals emitted from markers in the detection zone (14) excited by the radiation, the detector array (34) having an output; and a system coupled to the detector array (34) for effecting time delay integration of the charges on the detector array (34) corresponding to the light signals by accumulating the charges before reading the charges at the output of the detector array (34). Other apparatus and methods for detecting analytes in a sample are also provided.

High-viscosity polymer matrix and methods

Abstract: A supported, substantially uniform matrix for use in electric field-induced separation of molecular components in a sample. The matrix is prepared by forming a viscoelastic polymer matrix and pumping the matrix into a capillary or preparative-scale tube. The polymer type, concentration, and molecular weight are selected to optimize separation of protein or nucleic acid components. The matrix can be expelled from the tube, after fractionation, for analysis and/or recovery of fractionated components.

Absence of keratin 8 confers a paradoxical microflora-dependent resistance to apoptosis in the colon

Abstract: Keratin 8 (K8) is a major intermediate filament protein present in enterocytes and serves an antiapoptotic function in hepatocytes. K8-null mice develop colonic hyperplasia and colitis that are reversed after antibiotic treatment. To investigate the pathways that underlie the mechanism of colonocyte hyperplasia and the normalization of the colonic phenotype in response to antibiotics, we performed genome-wide microarray analysis. Functional annotation of genes that are differentially regulated in K8−/− and K8+/+ isolated colon crypts (colonocytes) identified apoptosis as a major altered pathway. Exposure of K8−/− colonocytes or colon organ (“organoid”) cultures, but not K8−/− small intestine organoid cultures, to apoptotic stimuli showed, surprisingly, that they are resistant to apoptosis compared with their wild-type counterparts. This resistance is not related to inflammation per se because T-cell receptor α-null (TCR-α−/−) and wild-type colon cultures respond similarly upon induction of apoptosis. Following antibiotic treatment, K8−/− colonocytes and organ cultures become less resistant to apoptosis and respond similarly to the wild-type colonocytes. Antibiotics also normalize most differentially up-regulated genes, including survivin and β4-integrin. Treatment of K8−/− mice with anti–β4-integrin antibody up-regulated survivin, and induced phosphorylation of focal adhesion kinase with decreased activation of caspases. Therefore, unlike the proapoptotic effect of K8 mutation or absence in hepatocytes, lack of K8 confers resistance to colonocyte apoptosis in a microflora-dependent manner.