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  • Life Sciences (General)  (10)
  • Astrophysics  (9)
  • Polymer and Materials Science  (5)
  • Humans
  • 1995-1999  (26)
  • 1
    ISSN: 0006-3525
    Keywords: AIDS ; DNA structure ; polymerase structure ; protein - DNA interaction ; x-ray crystallography ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformation of the DNA and the interactions of the nucleic acid with the protein in a complex of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and a 19-mer/18-mer double-stranded DNA template-primer (dsDNA) are described. The structure of this HIV-1 RT complex with dsDNA serves as a useful paradigm for studying aspects of nucleotide polymerases such as catalysis, fidelity, drug inhibition, and drug resistance. The bound dsDNA has a bend of approximately 41° at the junction of an A-form region (first five base pairs near the polymerase active site) and a B-form region (the last nine base pairs toward the RNase H active site). The 41° bend occurs smoothly over the four base pairs between the A-form portion and the B-form portion in the vicinity of helices αH and αI of the p66 thumb subdomain. The interactions between the dsDNA and protein primarily involve the sugar - phosphate backbone of the nucleic acid and structural elements of the palm, thumb, and RNase H of p66, and are not sequence specific. Amino acid residues from the polymerase active site region, including amino acid residues of the conserved Tyr-Met-Asp-Asp (YMDD) motif and the “primer grip,” interact with 3′-terminal nucleotides of the primer strand and are involved in positioning the primer terminal nucleotide and its 3′-OH group at the polymerase active site. Amino acid residues of the “template grip” have close contacts with the template strand and aid in positioning the template strand near the polymerase active site. Helix αH of the p66 thumb is partly inserted into the minor groove of the dsDNA and helix αI is directly adjacent to the backbone of the template strand. Amino acid residues of Β1′, αA′, αB′, and the loop containing His539 of the RNase H domain interact with the primer strand of the dsDNA. © 1997 John Wiley & Sons, Inc. Biopoly 44: 125-138, 1997
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 999-1004 
    ISSN: 0887-6266
    Keywords: latex ; polystyrene ; luminescence ; particle ; micron-diameter ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A technique for rapid determination of the presence of polystyrene in individual micron-diameter polymer particles of mixed composition is presented. This technique is based upon observation of visible emission from conjugated regions of the polymer backbone, generated photochemically, while the particle is held in an optical trap. Particle emission characteristics are dependent upon particle size and suspending solvent. Emission spectra are provided for single component polystyrene particles and mixed polymer particles containing poly(methyl methacrylate), poly(N-vinyl pyrrolidone), and polystyrene. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 999-1004, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 540-550 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Cerium-rich conversion coatings have been deposited onto aluminium 2024-T351 alloy by immersion into a solution containing 10 g L-1 CeCl3 and 1% H2O2 in a process described as ‘cerating’. Prior to deposition the alloy had been prepared either by using a standard chemical pretreatment used for aerospace alloys before conversion coating or by polishing. X-ray photoelectron spectroscopy and scanning electron microscopy have been used to characterize these cerium-containing conversion coatings. It was found that, during deposition, hydrated cerium oxide initially covered the intermetallics present in the alloy surface and then covered the surface generally. Deposition continued over the intermetallics throughout the conversion coating process, resulting in thick, heavily-cracked regions considerably greater than the average thickness of the film (〉0.3 μm). Elsewhere the coating was generally up to 0.2 μm thick, and appeared to comprised of deposited particles around 100 nm in size.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 634-640 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: X-ray photoelectron spectroscopy has been used to study 20, 100 and 1000 nm evaporated cerium oxide films on Si(100) single-crystal wafers. Upon exposure to the x-ray source there was loss of oxygen and generation of Ce3+. Furthermore, for the 20 nm coating, there was evidence of a shift to higher binding energies of the C 1s peak and a high binding energy O 1s component relative to the oxygen anion peak at 529.7±0.1 eV with increased exposure time to the x-ray source. No similar shift was observed in the O KLL Auger lines, suggesting that the effect was not due to differential charging of the surface with respect to the bulk of the coating. Hence the relative shift is explained in terms of electronic effects resulting from the formation of anion vacancies in the surface. These include a shift of the Fermi level due to defect states in the bandgap as well as band bending due to the positive charge set up from the anion vacancies.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 25 (1997), S. 223-234 
    ISSN: 0142-2421
    Keywords: conversion coating ; aluminium ; alloy ; x-ray photoelectron spectroscopy ; scanning electron microscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and potentiodynamic measurements have been made on chromate conversion-coated Al 2024-T3 alloy. X-ray photoelectron spectroscopy measurements indicated that the conversion coating had a surface of CrOOH and Cr(VI), enriched in ferricyanide. The bulk of the coating was an equal mixture of CrOOH and Cr2O3 with significant levels of F- and Fe, the latter implying the presence of ferricyanide throughout the coating. Copper(II) ion was present at the interface between the conversion coating and the alloy, as well as Al3+. During ageing experiments, potentiodynamic measurements indicated that the corrosion current (icorr) decreased from ∽0.4 to ∽0.04 μA cm-2 during the first 40 h after preparation but thereafter slowly increased. No significant changes were observed in the chemistry of the coating by XPS for ageing times longer than 40 h, although morphological changes were observed with SEM. As the coating aged, a network of microcracks developed across the surface. It is believed that Cr6+ is consumed in the process in which plugs of hydrated chromium oxide form at the base of these cracks. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 1999-05-21
    Description: Infectious diseases are the third leading cause of death in the United States and the leading cause worldwide. As the new millennium approaches, the public health community must replenish capacity depleted during years of inadequate funding while simultaneously incorporating new technologies and planning for the longer term. Among the challenges facing the public health community is the need for coordinated, global, multisectoral approaches to preventing and controlling complex infectious disease problems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Binder, S -- Levitt, A M -- Sacks, J J -- Hughes, J M -- New York, N.Y. -- Science. 1999 May 21;284(5418):1311-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Parasitic Diseases, National Center for Infectious Diseases (NCID), Centers for Disease Control and Prevention (CDC), F-22, 4770 Buford Highway, NE, Atlanta, GA 30341, USA. scb1@cdc.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10334978" target="_blank"〉PubMed〈/a〉
    Keywords: *Communicable Disease Control/trends ; *Communicable Diseases/diagnosis/epidemiology/mortality ; Drug Resistance, Microbial ; Environmental Health ; Global Health ; Humans ; Population Surveillance ; *Public Health Practice ; Socioeconomic Factors ; United States/epidemiology ; Vaccination
    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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  • 7
    Publication Date: 1995-06-30
    Description: DNA mismatch recognition and binding in human cells has been thought to be mediated by the hMSH2 protein. Here it is shown that the mismatch-binding factor consists of two distinct proteins, the 100-kilodalton hMSH2 and a 160-kilodalton polypeptide, GTBP (for G/T binding protein). Sequence analysis identified GTBP as a new member of the MutS homolog family. Both proteins are required for mismatch-specific binding, a result consistent with the finding that tumor-derived cell lines devoid of either protein are also devoid of mismatch-binding activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palombo, F -- Gallinari, P -- Iaccarino, I -- Lettieri, T -- Hughes, M -- D'Arrigo, A -- Truong, O -- Hsuan, J J -- Jiricny, J -- New York, N.Y. -- Science. 1995 Jun 30;268(5219):1912-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Istituto di Ricerche di Biologia Molecolare P. Angeletti, Pomezia, Italy.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7604265" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Composition ; Base Sequence ; Cloning, Molecular ; Colorectal Neoplasms ; *DNA Repair/genetics ; DNA, Neoplasm/*metabolism ; DNA-Binding Proteins/chemistry/genetics/*metabolism ; HeLa Cells ; Humans ; Molecular Sequence Data ; Molecular Weight ; Nucleic Acid Heteroduplexes/*metabolism ; Sequence Analysis ; Tumor Cells, Cultured
    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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  • 8
    Publication Date: 2011-08-24
    Description: Many colorectal cancers have high levels of cyclo-oxygenase 2 (COX-2), an enzyme that metabolizes the essential fatty acids into prostaglandins. Since the low-density lipoprotein receptor (LDLr) is involved in the uptake of essential fatty acids, we studied the effect of LDL on growth and gene regulation in colorectal cancer cells. DiFi cells grown in lipoprotein-deficient sera (LPDS) grew more slowly than cells with LDL. LDLr antibody caused significant inhibition of tumor cell growth but did not affect controls. In addition, LDL uptake did not change in the presence of excess LDL, suggesting that ldlr mRNA lacks normal feedback regulation in some colorectal cancers. Analysis of the ldlr mRNA showed that excess LDL in the medium did not cause down-regulation of the message even after 24 hr. The second portion of the study examined the mRNA expression of ldlr and its co-regulation with cox-2 in normal and tumor specimens from patients with colorectal adenocarcinomas. The ratio of tumor:paired normal mucosa of mRNA expression of ldlr and of cox-2 was measured in specimens taken during colonoscopy. ldlr and cox-2 transcripts were apparent in 11 of 11 carcinomas. There was significant coordinate up-regulation both of ldlr and of cox-2 in 6 of 11 (55%) tumors compared with normal colonic mucosa. There was no up-regulation of cox-2 without concomitant up-regulation of ldlr. These data suggest that the LDLr is abnormally regulated in some colorectal tumors and may play a role in the up-regulation of cox-2. Copyright 1999 Wiley-Liss, Inc.
    Keywords: Life Sciences (General)
    Type: International journal of cancer. Journal international du cancer (ISSN 0020-7136); Volume 83; 2; 162-6
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  • 9
    Publication Date: 2011-08-24
    Description: Epidermal expression of the two isoforms of the prostaglandin H-generating cyclooxygenase (COX-1 and COX-2) was evaluated both by immunohistochemistry performed on human and mouse skin biopsy sections and by Western blotting of protein extracts from cultured human neonatal foreskin keratinocytes. In normal human skin, COX-1 immunostaining is observed throughout the epidermis whereas COX-2 immunostaining increases in the more differentiated, suprabasilar keratinocytes. Basal cell carcinomas express little if any COX-1 or COX-2 immunostaining whereas both isozymes are strongly expressed in squamous cell carcinomas deriving from a more differentiated layer of the epidermis. In human keratinocyte cultures, raising the extracellular calcium concentration, a recognized stimulus for keratinocyte differentiation, leads to an increased expression of both COX-2 protein and mRNA; expression of COX-1 protein, however, shows no significant alteration in response to calcium. Because of a recent report that failed to show COX-2 in normal mouse epidermis, we also looked for COX-1 and COX-2 immunostaining in sections of normal and acetone-treated mouse skin. In agreement with a previous report, some COX-1, but no COX-2, immunostaining is seen in normal murine epidermis. However, following acetone treatment, there is a marked increase in COX-1 expression as well as the appearance of significant COX-2 immunostaining in the basal layer. These data suggest that in human epidermis as well as in human keratinocyte cultures, the expression of COX-2 occurs as a part of normal keratinocyte differentiation whereas in murine epidermis, its constitutive expression is absent, but inducible as previously published.
    Keywords: Life Sciences (General)
    Type: Experimental cell research (ISSN 0014-4827); Volume 224; 1; 79-87
    Format: text
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  • 10
    Publication Date: 2011-08-24
    Description: Space flight is an environmental condition where astronauts can lose up to 19% of weight-bearing bone during long duration missions. We used the MC3T3-E1 osteoblast to investigate bone cell growth in microgravity (10(-6) to 10(-9)g). Osteoblasts were launched on the STS-56 shuttle flight in a quiescent state with 0.5% fetal calf serum (FCS) medium and growth activation was initiated by adding fresh medium with 10% FCS during microgravity exposure. Four days after serum activation, the cells were fixed before return to normal Earth gravity. Ground controls were treated in parallel with the flight samples in identical equipment. On landing, cell number, cell cytoskeleton, glucose utilization, and prostaglandin synthesis in flight (n = 4) and ground controls (n = 4) were examined. The flown osteoblasts grew slowly in microgravity with total cell number significantly reduced (55 +/- 6 vs 141 +/- 8 cells per microscopic field). The cytoskeleton of the flight osteoblasts had a reduced number of stress fibers and a unique abnormal morphology. Nuclei in the ground controls were large and round with punctate Hoechst staining of the DNA nucleosomes. The flight nuclei were 30% smaller than the controls (P 〈 0.0001) and oblong in shape, with fewer punctate areas. Due to their reduced numbers, the cells activated in microgravity used significantly less glucose than ground controls (80.2 +/- 0.7 vs 50.3 +/- 3.7 mg of glucose/dl remaining in the medium) and had reduced prostaglandin E2 (PGE2) synthesis when compared to controls (57.3 +/- 17 vs 138.3 +/- 41 pmol/ml). Cell viability was normal since, on a per-cell basis, glucose use and prostaglandin synthesis were comparable for flight and ground samples. Taken together, these data suggest that growth activation in microgravity results in reduced growth, causing reduced glucose utilization and reduced prostaglandin synthesis, with significantly altered actin cytoskeleton in osteoblasts.
    Keywords: Life Sciences (General)
    Type: Experimental cell research (ISSN 0014-4827); Volume 224; 1; 103-9
    Format: text
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