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  • 1
    Publication Date: 2012-12-15
    Description: Although the gonad primarily functions in procreation, it also affects animal life span. Here, we show that removal of the Caenorhabditis elegans germ line triggers a switch in the regulatory state of the organism to promote longevity, co-opting components involved in larval developmental timing circuits. These components include the DAF-12 steroid receptor, which is involved in the larval stage two-to-stage three (L2-L3) transition and up-regulates members of the let-7 microRNA (miRNA) family. The miRNAs target an early larval nuclear factor lin-14 and akt-1/kinase, thereby stimulating DAF-16/FOXO signaling to extend life. Our studies suggest that metazoan life span is coupled to the gonad through elements of a developmental timer.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3909774/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3909774/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shen, Yidong -- Wollam, Joshua -- Magner, Daniel -- Karalay, Oezlem -- Antebi, Adam -- R01 AG027498/AG/NIA NIH HHS/ -- T32 GM008231/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2012 Dec 14;338(6113):1472-6. doi: 10.1126/science.1228967.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, D-50931 Cologne, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23239738" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Caenorhabditis elegans/genetics/growth & development/*physiology ; Caenorhabditis elegans Proteins/genetics/*physiology ; Forkhead Transcription Factors ; Gene Expression Regulation, Developmental ; Germ Cells/metabolism ; Gonads/*metabolism ; Larva/genetics/growth & development/physiology ; Longevity/genetics/*physiology ; MicroRNAs/genetics/*metabolism ; Nuclear Proteins/genetics/physiology ; Proto-Oncogene Proteins c-akt/genetics/physiology ; Receptors, Cytoplasmic and Nuclear/genetics/*physiology ; Receptors, Steroid/genetics/*physiology ; Signal Transduction ; Transcription Factors/genetics/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-07-20
    Description: Genotypic differences greatly influence susceptibility and resistance to disease. Understanding genotype-phenotype relationships requires that phenotypes be viewed as manifestations of network properties, rather than simply as the result of individual genomic variations. Genome sequencing efforts have identified numerous germline mutations, and large numbers of somatic genomic alterations, associated with a predisposition to cancer. However, it remains difficult to distinguish background, or 'passenger', cancer mutations from causal, or 'driver', mutations in these data sets. Human viruses intrinsically depend on their host cell during the course of infection and can elicit pathological phenotypes similar to those arising from mutations. Here we test the hypothesis that genomic variations and tumour viruses may cause cancer through related mechanisms, by systematically examining host interactome and transcriptome network perturbations caused by DNA tumour virus proteins. The resulting integrated viral perturbation data reflects rewiring of the host cell networks, and highlights pathways, such as Notch signalling and apoptosis, that go awry in cancer. We show that systematic analyses of host targets of viral proteins can identify cancer genes with a success rate on a par with their identification through functional genomics and large-scale cataloguing of tumour mutations. Together, these complementary approaches increase the specificity of cancer gene identification. Combining systems-level studies of pathogen-encoded gene products with genomic approaches will facilitate the prioritization of cancer-causing driver genes to advance the understanding of the genetic basis of human cancer.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408847/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408847/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rozenblatt-Rosen, Orit -- Deo, Rahul C -- Padi, Megha -- Adelmant, Guillaume -- Calderwood, Michael A -- Rolland, Thomas -- Grace, Miranda -- Dricot, Amelie -- Askenazi, Manor -- Tavares, Maria -- Pevzner, Samuel J -- Abderazzaq, Fieda -- Byrdsong, Danielle -- Carvunis, Anne-Ruxandra -- Chen, Alyce A -- Cheng, Jingwei -- Correll, Mick -- Duarte, Melissa -- Fan, Changyu -- Feltkamp, Mariet C -- Ficarro, Scott B -- Franchi, Rachel -- Garg, Brijesh K -- Gulbahce, Natali -- Hao, Tong -- Holthaus, Amy M -- James, Robert -- Korkhin, Anna -- Litovchick, Larisa -- Mar, Jessica C -- Pak, Theodore R -- Rabello, Sabrina -- Rubio, Renee -- Shen, Yun -- Singh, Saurav -- Spangle, Jennifer M -- Tasan, Murat -- Wanamaker, Shelly -- Webber, James T -- Roecklein-Canfield, Jennifer -- Johannsen, Eric -- Barabasi, Albert-Laszlo -- Beroukhim, Rameen -- Kieff, Elliott -- Cusick, Michael E -- Hill, David E -- Munger, Karl -- Marto, Jarrod A -- Quackenbush, John -- Roth, Frederick P -- DeCaprio, James A -- Vidal, Marc -- F32 GM095284/GM/NIGMS NIH HHS/ -- F32GM095284/GM/NIGMS NIH HHS/ -- K08 CA122833/CA/NCI NIH HHS/ -- K08 HL098361/HL/NHLBI NIH HHS/ -- K08HL098361/HL/NHLBI NIH HHS/ -- K25 HG006031/HG/NHGRI NIH HHS/ -- K25HG006031/HG/NHGRI NIH HHS/ -- P01 CA050661/CA/NCI NIH HHS/ -- P01CA050661/CA/NCI NIH HHS/ -- P50 HG004233/HG/NHGRI NIH HHS/ -- P50HG004233/HG/NHGRI NIH HHS/ -- R01 CA047006/CA/NCI NIH HHS/ -- R01 CA063113/CA/NCI NIH HHS/ -- R01 CA066980/CA/NCI NIH HHS/ -- R01 CA081135/CA/NCI NIH HHS/ -- R01 CA085180/CA/NCI NIH HHS/ -- R01 CA093804/CA/NCI NIH HHS/ -- R01 CA131354/CA/NCI NIH HHS/ -- R01 HG001715/HG/NHGRI NIH HHS/ -- R01CA047006/CA/NCI NIH HHS/ -- R01CA063113/CA/NCI NIH HHS/ -- R01CA066980/CA/NCI NIH HHS/ -- R01CA081135/CA/NCI NIH HHS/ -- R01CA085180/CA/NCI NIH HHS/ -- R01CA093804/CA/NCI NIH HHS/ -- R01CA131354/CA/NCI NIH HHS/ -- R01HG001715/HG/NHGRI NIH HHS/ -- T32 HL007208/HL/NHLBI NIH HHS/ -- T32HL007208/HL/NHLBI NIH HHS/ -- U01 CA141583/CA/NCI NIH HHS/ -- U01CA141583/CA/NCI NIH HHS/ -- England -- Nature. 2012 Jul 26;487(7408):491-5. doi: 10.1038/nature11288.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Genomic Analysis of Network Perturbations Center of Excellence in Genomic Science, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22810586" target="_blank"〉PubMed〈/a〉
    Keywords: Adenoviridae/genetics/metabolism/pathogenicity ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Genes, Neoplasm/*genetics ; Genome, Human/*genetics ; Herpesvirus 4, Human/genetics/metabolism/pathogenicity ; *Host-Pathogen Interactions/genetics ; Humans ; Neoplasms/*genetics/*metabolism/pathology ; Oncogenic Viruses/genetics/metabolism/*pathogenicity ; Open Reading Frames/genetics ; Papillomaviridae/genetics/metabolism/pathogenicity ; Polyomavirus/genetics/metabolism/pathogenicity ; Receptors, Notch/metabolism ; Signal Transduction ; Two-Hybrid System Techniques ; Viral Proteins/genetics/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2006-11-11
    Description: We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159423/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159423/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sea Urchin Genome Sequencing Consortium -- Sodergren, Erica -- Weinstock, George M -- Davidson, Eric H -- Cameron, R Andrew -- Gibbs, Richard A -- Angerer, Robert C -- Angerer, Lynne M -- Arnone, Maria Ina -- Burgess, David R -- Burke, Robert D -- Coffman, James A -- Dean, Michael -- Elphick, Maurice R -- Ettensohn, Charles A -- Foltz, Kathy R -- Hamdoun, Amro -- Hynes, Richard O -- Klein, William H -- Marzluff, William -- McClay, David R -- Morris, Robert L -- Mushegian, Arcady -- Rast, Jonathan P -- Smith, L Courtney -- Thorndyke, Michael C -- Vacquier, Victor D -- Wessel, Gary M -- Wray, Greg -- Zhang, Lan -- Elsik, Christine G -- Ermolaeva, Olga -- Hlavina, Wratko -- Hofmann, Gretchen -- Kitts, Paul -- Landrum, Melissa J -- Mackey, Aaron J -- Maglott, Donna -- Panopoulou, Georgia -- Poustka, Albert J -- Pruitt, Kim -- Sapojnikov, Victor -- Song, Xingzhi -- Souvorov, Alexandre -- Solovyev, Victor -- Wei, Zheng -- Whittaker, Charles A -- Worley, Kim -- Durbin, K James -- Shen, Yufeng -- Fedrigo, Olivier -- Garfield, David -- Haygood, Ralph -- Primus, Alexander -- Satija, Rahul -- Severson, Tonya -- Gonzalez-Garay, Manuel L -- Jackson, Andrew R -- Milosavljevic, Aleksandar -- Tong, Mark -- Killian, Christopher E -- Livingston, Brian T -- Wilt, Fred H -- Adams, Nikki -- Belle, Robert -- Carbonneau, Seth -- Cheung, Rocky -- Cormier, Patrick -- Cosson, Bertrand -- Croce, Jenifer -- Fernandez-Guerra, Antonio -- Geneviere, Anne-Marie -- Goel, Manisha -- Kelkar, Hemant -- Morales, Julia -- Mulner-Lorillon, Odile -- Robertson, Anthony J -- Goldstone, Jared V -- Cole, Bryan -- Epel, David -- Gold, Bert -- Hahn, Mark E -- Howard-Ashby, Meredith -- Scally, Mark -- Stegeman, John J -- Allgood, Erin L -- Cool, Jonah -- Judkins, Kyle M -- McCafferty, Shawn S -- Musante, Ashlan M -- Obar, Robert A -- Rawson, Amanda P -- Rossetti, Blair J -- Gibbons, Ian R -- Hoffman, Matthew P -- Leone, Andrew -- Istrail, Sorin -- Materna, Stefan C -- Samanta, Manoj P -- Stolc, Viktor -- Tongprasit, Waraporn -- Tu, Qiang -- Bergeron, Karl-Frederik -- Brandhorst, Bruce P -- Whittle, James -- Berney, Kevin -- Bottjer, David J -- Calestani, Cristina -- Peterson, Kevin -- Chow, Elly -- Yuan, Qiu Autumn -- Elhaik, Eran -- Graur, Dan -- Reese, Justin T -- Bosdet, Ian -- Heesun, Shin -- Marra, Marco A -- Schein, Jacqueline -- Anderson, Michele K -- Brockton, Virginia -- Buckley, Katherine M -- Cohen, Avis H -- Fugmann, Sebastian D -- Hibino, Taku -- Loza-Coll, Mariano -- Majeske, Audrey J -- Messier, Cynthia -- Nair, Sham V -- Pancer, Zeev -- Terwilliger, David P -- Agca, Cavit -- Arboleda, Enrique -- Chen, Nansheng -- Churcher, Allison M -- Hallbook, F -- Humphrey, Glen W -- Idris, Mohammed M -- Kiyama, Takae -- Liang, Shuguang -- Mellott, Dan -- Mu, Xiuqian -- Murray, Greg -- Olinski, Robert P -- Raible, Florian -- Rowe, Matthew -- Taylor, John S -- Tessmar-Raible, Kristin -- Wang, D -- Wilson, Karen H -- Yaguchi, Shunsuke -- Gaasterland, Terry -- Galindo, Blanca E -- Gunaratne, Herath J -- Juliano, Celina -- Kinukawa, Masashi -- Moy, Gary W -- Neill, Anna T -- Nomura, Mamoru -- Raisch, Michael -- Reade, Anna -- Roux, Michelle M -- Song, Jia L -- Su, Yi-Hsien -- Townley, Ian K -- Voronina, Ekaterina -- Wong, Julian L -- Amore, Gabriele -- Branno, Margherita -- Brown, Euan R -- Cavalieri, Vincenzo -- Duboc, Veronique -- Duloquin, Louise -- Flytzanis, Constantin -- Gache, Christian -- Lapraz, Francois -- Lepage, Thierry -- Locascio, Annamaria -- Martinez, Pedro -- Matassi, Giorgio -- Matranga, Valeria -- Range, Ryan -- Rizzo, Francesca -- Rottinger, Eric -- Beane, Wendy -- Bradham, Cynthia -- Byrum, Christine -- Glenn, Tom -- Hussain, Sofia -- Manning, Gerard -- Miranda, Esther -- Thomason, Rebecca -- Walton, Katherine -- Wikramanayke, Athula -- Wu, Shu-Yu -- Xu, Ronghui -- Brown, C Titus -- Chen, Lili -- Gray, Rachel F -- Lee, Pei Yun -- Nam, Jongmin -- Oliveri, Paola -- Smith, Joel -- Muzny, Donna -- Bell, Stephanie -- Chacko, Joseph -- Cree, Andrew -- Curry, Stacey -- Davis, Clay -- Dinh, Huyen -- Dugan-Rocha, Shannon -- Fowler, Jerry -- Gill, Rachel -- Hamilton, Cerrissa -- Hernandez, Judith -- Hines, Sandra -- Hume, Jennifer -- Jackson, Laronda -- Jolivet, Angela -- Kovar, Christie -- Lee, Sandra -- Lewis, Lora -- Miner, George -- Morgan, Margaret -- Nazareth, Lynne V -- Okwuonu, Geoffrey -- Parker, David -- Pu, Ling-Ling -- Thorn, Rachel -- Wright, Rita -- 2P42 ESO7381/PHS HHS/ -- 5 U54 HG003273/HG/NHGRI NIH HHS/ -- EY11930/EY/NEI NIH HHS/ -- F32 ESO12794/PHS HHS/ -- F32 HD047136/HD/NICHD NIH HHS/ -- F32 HD047136-02/HD/NICHD NIH HHS/ -- F32 HD047136-03/HD/NICHD NIH HHS/ -- F32-HD47136/HD/NICHD NIH HHS/ -- GM058231/GM/NIGMS NIH HHS/ -- GM070840/GM/NIGMS NIH HHS/ -- GM61005/GM/NIGMS NIH HHS/ -- GM61464/GM/NIGMS NIH HHS/ -- HD-37105/HD/NICHD NIH HHS/ -- HD039948/HD/NICHD NIH HHS/ -- HD14483/HD/NICHD NIH HHS/ -- HD66219/HD/NICHD NIH HHS/ -- P30-CA14051/CA/NCI NIH HHS/ -- R01 ES006272/ES/NIEHS NIH HHS/ -- R01 ES006272-13/ES/NIEHS NIH HHS/ -- R01 GM070840/GM/NIGMS NIH HHS/ -- R01 HD028152/HD/NICHD NIH HHS/ -- R01ES006272/ES/NIEHS NIH HHS/ -- R37-HD12896/HD/NICHD NIH HHS/ -- RR-15044/RR/NCRR NIH HHS/ -- S19916/Biotechnology and Biological Sciences Research Council/United Kingdom -- T32 GM007601/GM/NIGMS NIH HHS/ -- U54 HG003273/HG/NHGRI NIH HHS/ -- New York, N.Y. -- Science. 2006 Nov 10;314(5801):941-52.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17095691" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcification, Physiologic ; Cell Adhesion Molecules/genetics/physiology ; Complement Activation/genetics ; Computational Biology ; Embryonic Development/genetics ; Evolution, Molecular ; Gene Expression Regulation, Developmental ; Genes ; *Genome ; Immunity, Innate/genetics ; Immunologic Factors/genetics/physiology ; Male ; Nervous System Physiological Phenomena ; Proteins/genetics/physiology ; *Sequence Analysis, DNA ; Signal Transduction ; Strongylocentrotus purpuratus/embryology/*genetics/immunology/physiology ; Transcription Factors/genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2008-02-02
    Description: In the mammalian ovary, progressive activation of primordial follicles from the dormant pool serves as the source of fertilizable ova. Menopause, or the end of female reproductive life, occurs when the primordial follicle pool is exhausted. However, the molecular mechanisms underlying follicle activation are poorly understood. We provide genetic evidence that in mice lacking PTEN (phosphatase and tensin homolog deleted on chromosome 10) in oocytes, a major negative regulator of phosphatidylinositol 3-kinase (PI3K), the entire primordial follicle pool becomes activated. Subsequently, all primordial follicles become depleted in early adulthood, causing premature ovarian failure (POF). Our results show that the mammalian oocyte serves as the headquarters of programming of follicle activation and that the oocyte PTEN-PI3K pathway governs follicle activation through control of initiation of oocyte growth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reddy, Pradeep -- Liu, Lian -- Adhikari, Deepak -- Jagarlamudi, Krishna -- Rajareddy, Singareddy -- Shen, Yan -- Du, Chun -- Tang, Wenli -- Hamalainen, Tuula -- Peng, Stanford L -- Lan, Zi-Jian -- Cooney, Austin J -- Huhtaniemi, Ilpo -- Liu, Kui -- New York, N.Y. -- Science. 2008 Feb 1;319(5863):611-3. doi: 10.1126/science.1152257.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medical Biochemistry and Biophysics, Umea University, SE-901 87 Umea, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18239123" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Female ; Follicular Atresia ; Mice ; Mice, Transgenic ; Oocytes/cytology/growth & development/*physiology ; Organ Size ; Ovarian Follicle/cytology/*physiology ; Ovary/anatomy & histology/physiology ; Ovulation ; PTEN Phosphohydrolase/genetics/*physiology ; Phosphatidylinositol 3-Kinases/metabolism ; Phosphorylation ; Primary Ovarian Insufficiency/physiopathology ; Protein Kinases/metabolism ; Ribosomal Protein S6/metabolism ; Signal Transduction ; TOR Serine-Threonine Kinases
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical fluid chromatography ; Solvating gas chromatography ; Polybutadiene coated zirconia ; CO2 mobile phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper, practical considerations of column efficiency, separation speed, thermal stability, and column polarity of capillary columns packed with polybutadiene-coated zirconia were investigated under solvating gas chromatography (SGC) conditions using carbon dioxide as mobile phase. When compared with results obtained from conventional porous octadecyl obtained from conventional porous octadecyl bonded silica (ODS) particles, PBD-zirconia particles produced greater change in mobile phase linear velocity with pressure than conventional ODS particles under the same conditions. The maximum plate number per second (Nt) obtained with a 30 cm PBD-zirconia column was approximately 1.5 times higher than that obtained with an ODS column at 100 °C. Therefore, the PBD-zirconia phase is more suitable for fast separations than conventional ODS particles in SGC. Maximum plate numbers per meter of 76,900 and 63,300 were obtained using a 57 cm×250 μm i.d. fused silica capillary column packed with 3 μm PBD-zirconia at 50 °C and 100 °C, respectively. The PBD-zirconia phase was stable at temperatures up to 320 °C under SGC conditions using carbon dioxide as mobile phase. Polarizable aromatic compounds and low molecular weight ketones and aldehydes were eluted with symmetrical peaks from a 10 cm column packed with 3 μm PBD-zirconia. Zirconia phases with greater inertness are required for the analysis of more polar compounds by SGC.
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  • 6
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Packed capillary columns ; Liquid crystalline polysiloxane ; Polymer encapsulated particles ; Vitamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Liquid crystal polysiloxane stationary phases were prepared by coating two different polymers on deactivated porous silica particles (10 μm diameter, 80 Å pores). Deactivation of the silica particles before coating was necessary to prepare highly efficient and inert stationary phases for supercritical fluid chromatography (SFC). Fat-soluble vitamins E, A, K1, K2, D2, and D3 were separated on these columns using neat supercritical CO2 as mobile phase. The analyses were completed within 40 min at 70 °C. The results were compared to those obtained using a capillary column packed with less ordered liquid crystalm,m-cyanobiphenyl-substituted polysiloxane coated particles. Reduced shape selectivity was observed with this cyanobiphenyl phase. The response factors of vitamins A, E, K1, K2, D2, and D3 when using the flame ionization detector (FID) were determined to be very similar.
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  • 7
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Packed capillary columns ; Polyethylene oxide coated phases ; Polymer encapsulated particles ; Amines and acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyethylene oxide (PEO)-based polymers with hydroxy, methoxy, and aminopropoxy terminal groups were coated on diol functionalized and hexamethyldisilazane end-capped silica particles. Proton-donor and proton-acceptor test solutes, including carboxylic acids, hydroxy-containing compounds, arylamines, and alkylamines were used to evaluate the chromatographic performances of these polymer coated particles under SFC conditions with neat CO2 as mobile phase. It was found that the particles coated with hydroxy-terminated PEO were suitable for the separation of proton-donor compounds such as hydroxy-containing compounds and carboxylic acids, and the particles coated with aminopropoxy-terminated PEO could be used for the separation of amines. That is, the proton-accepting stationary phase is suitable for the separation of proton accepting solutes, including strong basic alkylamines (pKb≈4), using neat CO2 as mobile phase, while the protondonating stationary phase is suitable for the separation of proton-donating compounds such as carboxylic acids (pKa≈4). Hydrogen bond basicity was found to be a critical factor for the chromatography of basic amines. Low volatility acidic and basic drugs were chromatographed using the new stationary phases. The stability of the PEO coated particles was determined by measuring the loss of organic carbon under SFC conditions. It was found that approximately 18 % of the coating (average molecular weight of 15,000) was washed out of the particles by supercritical CO2 after 7 h at 350 atm and 50°C
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  • 8
    ISSN: 1612-1112
    Keywords: Solvating gas chromatography ; Supercritical fluid chromatography ; Packed capillary columns ; Solvating power
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The efficiency (plate number per unit time) and elution power (range ofn-alkanes) of packed capillary SFC and SGC using CO2 as the mobile phase were compared. A higher plate number per unit time was obtained in SGC than in SFC using the same column under the same applied conditions. SGC is more suitable for fast separations than SFC. The solvating ability of the mobile phase, at the column exit end, decreased remarkably after the restrictor was removed. However, the elution molecular weight range in SGC can be greatly extended by increasing the column temperature.n-Alkanes with carbon numbers as high as 80 were separated under SGC conditions using a 35 cm ×250 μm i.d. column packed with 10 μm polymer-encapsulated silica particles at 200 atm, with a temperature program of 100–380°C at 10°C min−1.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 49 (1999), S. 333-337 
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Gas chromatography ; Solvating gas chromatography ; Peak capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper, a general peak capacity expression was evaluated using columns containing various packing materials under solvating gas chromatography (SGC) conditions. Differing from column efficiency, peak capacity can describe both separation capability and speed when introducing the dead time into the peak capacity expression. Various factors that influence peak capacity in SGC are described, including particle pore size, chemical surface modification, particle size, column length, temperature, and pressure.
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  • 10
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Surface modification ; Deactivation ; Silica particles ; Stationary phases ; Packing materials ; Packed capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Spherical porous silica particles (10 μm diameter, 300 Å and 80 Å pores), spherical nonporous silica particles (10 μm diameter), and irregular porous silica particles (≈10 μm diameter, 80 Å pores) were deactivated with polymethylhydrosiloxane (PS). The surface activities of the deactivated silica particles were investigated using various polar compounds under supercritical fluid chromatography (SFC) conditions (neat CO2), and compared with a commercial C18-bonded phase. The small pore (80 Å) silica particles could be more completely deactivated than larger pore (300 Å) and nonporous silica particles. The success of the PS deactivation method is ascribed to the excellent match between the reactive groups on the polymer backbone and the silica surface, and the formation of a highly crosslinked polymeric layer over the surface. Physical processes, such as adsorption and desorption of the deactivation reagent on the surface and diffusion from the surface, were found to have important effects on the deactivation. Using capillary columns packed with PS deactivated silica particles, typical polar organic compounds, including hydroxyl-containing compounds, carbonyl-containing compounds, free amines, and free carboxylic acids, were separated by SFC and compared with results from a commercial C18-bonded phase. While the results clearly show that the PS deactivated particles were more inert than the C18-bonded phase, better deactivation methods are still needed for separation of free acids and alkylamines.
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