Home About us Contact
|
Home About us Contact | ||
|
|
||
Minor Peak (minor + peak)
Selected AbstractsIsomerization of delta-9-THC to delta-8-THC when tested as trifluoroacetyl-, pentafluoropropionyl-, or heptafluorobutyryl- derivatives,,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2008Justin M. Holler Abstract For GC,MS analysis of delta-9-tetrahydrocannabinol (delta-9-THC), perfluoroacid anhydrides in combination with perfluoroalcohols are commonly used for derivatization. This reagent mixture is preferred because it allows simultaneous derivatization of delta-9-THC and its acid metabolite, 11-nor-delta-9-THC-9-carboxylic acid present in biological samples. When delta-9-THC was derivatized by trifluoroacetic anhydride/hexafluoroisopropanol (TFAA/HFIPOH) and analyzed by GC,MS using full scan mode (50,550 amu), two peaks (P1 and P2) with an identical molecular mass of 410 amu were observed. On the basis of the total ion chromatogram (TIC), P1 with a shorter retention time (RT) was the major peak (TIC 84%). To identify the peaks, delta-8-THC was also tested under the same conditions. The RT and spectra of the major peak (TIC 95%) were identical with that of P1 for delta-9-THC. A minor peak (5%) present also correlated well with the latter peak (P2) for the delta-9-THC derivative. The fragmentation pathway of P1 was primarily demethylation followed by retro Diels-Alder fragmentation (M , 15,68, base peak 100%) indicating P1 as a delta-8-THC-trifluoroacetyl compound. This indicated that delta-9-THC isomerized to delta-8-THC during derivatization with TFAA/HFIPOH. Similar results were also observed when delta-9-THC was derivatized with pentafluoropropionic anhydride/pentafluoropropanol or heptafluorobutyric anhydride/heptafluorobutanol. No isomerization was observed when chloroform was used in derivatization with TFAA. In this reaction, the peaks of delta-8-THC-TFA and delta-9-THC-TFA had retention times and mass spectra matching with P1 and P2, respectively. Because of isomerization, perfluoroacid anhydrides/perfluoroalcohols are not suitable derivatizing agents for analysis of delta-9-THC; whereas the TFAA in chloroform is suitable for the analysis. Published in 2008 by John Wiley & Sons, Ltd. [source] Biclonal low grade B-cell lymphoma confirmed by both flow cytometry and karyotypic analysis, in spite of a normal kappa/lambda Ig light chain ratioAMERICAN JOURNAL OF HEMATOLOGY, Issue 6 2007J.P. Delville Abstract Composite low grade lymphoma with two subpopulations in a same site is uncommon. We herewith report the case of an 80-year-old woman who presented with isolated bilateral dacryoadenomegaly. Pathological examination of an incisional biopsy of her right lacrimal gland was consistent with a marginal zone lymphoma. Flow cytometry immunophenotyping showed two distinct clonal B-cell populations expressing sIg D lambda or sIg M kappa restriction in the lacrimal gland, blood, and bone marrow. Both B-cells populations were sorted from peripheral blood for molecular biology investigations and comparison with molecular data performed on tumor and bone marrow cells. IgH PCR performed on purified blood populations disclosed two monoclonal peaks: 98 bp-sized peak in the sIg M kappa and a 107 bp in the sIg D lambda clones, respectively. The lacrimal gland tumor expressed mainly sIg M kappa population, and showed a major 98 bp-sized peak coexisting with a very minor 107 bp peak. Cytogenetic studies showed a 46, XX,del (7) (q22q32) karyotype. Bone marrow examination at diagnosis revealed the same B-cell clones distribution than the one observed in blood with a dominant sIg D lambda population, a Genescan profile showing a major peak of 107 bp and a minor peak of 98 bp. Chromosomal analysis disclosed a 46,XX,del (10) (?p14) karyotype without detectable 7q deletion. To our knowledge, this observation represents the first reported case of biclonal low grade lymphoma hidden behind a normal classical kappa/lambda Ig light chain ratio in blood, but clearly demonstrated by the combination of three ancillary techniques (flow cytometry both analytical and cell sorting, molecular biology, and cytogenetics) and analysis of different tissues (i.e., in this case, lacrimal gland biopsy, blood, and bone marrow. Am. J. Hematol., 2007. © 2007 Wiley-Liss, Inc. [source] Three pheromone-binding proteins in olfactory sensilla of the two silkmoth species Antheraea polyphemus and Antheraea pernyiFEBS JOURNAL, Issue 10 2000Rosario Maida Females of the sibling silkmoth species Antheraea polyphemus and A. pernyi use the same three sex pheromone components in different ratios to attract conspecific males. Accordingly, the sensory hairs on the antennae of males contain three receptor cells sensitive to each of the pheromone components. In agreement with the number of pheromones used, three different pheromone-binding proteins (PBPs) could be identified in pheromone-sensitive hairs of both species by combining biochemical and molecular cloning techniques. MALDI-TOF MS of sensillum lymph droplets from pheromone-sensitive sensilla trichodea of male A. polyphemus revealed the presence of three major peaks with m/z of 15702, 15752 and 15780 and two minor peaks of m/z 15963 and 15983. In Western blots with four antisera raised against different silkmoth odorant-binding proteins, immunoreactivity was found only with an anti-(Apol PBP) serum. Free-flow IEF, ion-exchange chromatography and Western blot analyses revealed at least three anti-(Apol PBP) immunoreactive proteins with pI values between 4.4 and 4.7. N-Terminal sequencing of these three proteins revealed two proteins (Apol PBP1a and Apol PBP1b) identical in the first 49 amino acids to the already known PBP (Apol PBP1) [Raming, K., Krieger, J. & Breer, H. (1989) FEBS Lett.256, 2215,2218] and a new PBP having only 57% identity with this amino-acid region. Screening of antennal cDNA libraries with an oligonucleotide probe corresponding to the N-terminal end of the new A. polyphemus PBP, led to the discovery of full length clones encoding this protein in A. polyphemus (Apol PBP3) and in A. pernyi (Aper PBP3). By screening the antennal cDNA library of A. polyphemus with a digoxigenin-labelled A. pernyi PBP2 cDNA [Krieger, J., Raming, K. & Breer, H. (1991) Biochim. Biophys. Acta1088, 277,284] a homologous PBP (Apol PBP2) was cloned. Binding studies with the two main pheromone components of A. polyphemus and A. pernyi, the (E,Z)-6,11-hexadecadienyl acetate (AC1) and the (E,Z)-6,11-hexadecadienal (ALD), revealed that in A. polyphemus both Apol PBP1a and the new Apol PBP3 bound the 3H-labelled acetate, whereas no binding of the 3H-labelled aldehyde was found. In A. pernyi two PBPs from sensory hair homogenates showed binding affinity for the AC1 (Aper PBP1) and the ALD (Aper PBP2), respectively. [source] Changes in the pectic fraction of bush butter (Dacryodes edulis (G Don) HJ Lam) fruit pulp during ripeningJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001Crépin Ella Missang Abstract CDTA-soluble polysaccharides were extracted from cell wall material (prepared as alcohol-insoluble solids) of bush butter fruit endocarp tissue at three stages of ripeness. The amount of soluble pectins remained constant but they underwent a gradual depolymerisation during ripening. The CDTA extracts were fractionated by anion exchange and the subfractions were analysed for their sugar composition and molecular weight distribution. For all degrees of ripeness the extracts were composed of three minor peaks and two major peaks. The minor peaks appeared to be composed of xyloglucan and mannan-type polymers for the first peak and arabinogalactan-type polymers for the other two peaks. The two main peaks were retained on the column. The first was exclusively composed of homogalacturonan polymers and the second contained principally highly branched rhamnogalacturonan polymers. During ripening, both homogalacturonan and rhamnogalacturonan populations were modified. Modifications in the rhamnogalacturonan fraction were principally marked by the accumulation of low-molecular-weight rhamnoglacturonan polymers in the course of ripening. © 2001 Society of Chemical Industry [source] | ||||||||||