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  • National Institutes of Health (U.S.)  (81)
  • Female  (72)
  • Cell & Developmental Biology  (54)
  • Analytical Chemistry and Spectroscopy  (45)
  • 1
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The female black scale possesses a pair of lateral ocelli. Each develops as a small disc of enlarged hypodermal cells which increases in size and invaginates. The disc finally becomes cut off from the hypodermis to form a vesicle lying between the regular hypodermis and the lateral margin of the brain. The vesicle becomes differentiated into two parts. The outer group of cells forms the vitreous body, the inner group gives rise to the retina. The vitreous body soon begins to secrete the lens which, during embryonic life, becomes biconvex. Pigment granules form only in the retinal cells; at first yellow, later black. The ocellus of the first instar is similar to that of the embryo. During first and second ecdyses the old lens is cast off and a new one secreted by the vitreous body. A large, irregularly shaped crystalline body forms between the vitreous body and the retina. The ocellus is of four parts: lens, vitreous body, crystallin body and retina. Retinal cells are at first nucleated but the nuclei probably pass to the nerve fibers each one of which is connected to a retinal cell. The ocellus does not change in structure throughout the life of the insect but finally disintegrates. The disintegration begins on the inner surface of the lens. Ocelli developed in the embryo remain unchanged throughout the insect's life.
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  • 2
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of digoxin and digitoxin (the most widely prescribed drugs for treatment of congestive heart failure) and a complete set of their 14 dihydro- and sugar-hydrolyzed metabolites have been obtained via laser desorption/ionization with a Fourier transform ion cyclotron resonance (LD/FT/ICR) mass spectrometer. The most intense peak is typically the pseudomolecular [M + K]+ ion, but fragment ions corresponding to loss of 1--3 sugars and hydroxyls are also observed. LD/FT/ICR mass spectra for all 16 compounds were produced with a single set of sample and spectrometer parameters. No matrix peaks are present. Finally, LD/FT/ICR provides dynamic mass accuracy within ≈5 ppm throughout a mass range of 404 〈 m/z 〈 819.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 333-343 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient algorithm is described for sequencing peptides from sequence ions appearing in fast atom bombardment (FAB) and FAB tandem mass spectra. The following features are incorporated in the algorithm. The members of the set of sequence ions are represented by all possible combinations of N- and C-terminal fragment ions. From the known N- and C-terminating groups and molecular weight (MW) of the peptide, the sequence ions are mathematically re-expressed as N-terminal residue ions and arranged in ascending order. The peptide sequence is computed, in a stepwise iterative procedure, from the mass differences between the mathematically re-expressed N-terminal residue ions and the predicted peptide subsequences for the neighboring ions of lower mass. These mass differences correspond to combinations of known amino acid residues which have previously been computed and tabulated, based upon the FAB fragmentation rules for peptides. The algorithm was successfully applied to sequence the following peptides from their respective FAB or FAB tandem mass spectrum: decapeptyl (MW 1310), angiotensin II (MW 1045), and two ‘unknown’ peptides (MW 1227 and 1485, respectively). Two criteria used to predict the correct peptide sequence from among many possibilities are the minimum number of amino acid residues and the maximum fragmentation probability per amino acid residue.
    Additional Material: 5 Ill.
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  • 4
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment mass spectrometry (FAB MS) and fast atom bombardment mass spectrometry-mass spectrometry (FAB MS/MS) were used to study the monovalent glycoside polyether antibiotics maduramicin α, β and δ and the maduramicin α salts, their derivatives and degradation products. Also, representative compounds from three major classes of polyether antibiotics were studied: the monovalent polyethers, nigericin and monensin A, the divalent polyether lasalocid A and the monovalent glycoside polyethers septamycin, BL580 δ, etheromycin and carriomycin. The respective FAB fragment and decomposition ions were correlated with the known structures. The FAB spectra of all the polyethers contained metal-adduct molecular ions. Protonated molecular ions were absent. All the polyethers having a β-hemiketal carboxylic acid group produced an abundant ion, often the base peak of the spectra, 62 daltons less than the corresponding metal-adduct molecular ion. The gas phase mechanism proposed for the formation of this fragment ion is an unusual unimolecular reaction which is initiated by an intramolecular proton transfer from the carboxylic acid to the hydroxy group of the β-hemiketal, and, then followed by the concerted losses of water and carbon dioxide to produce the corresponding polyether olefin.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 22 (1992), S. 281-295 
    ISSN: 0886-1544
    Keywords: nonmuscle myosin ; antibodies ; neurons ; blood vessels ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of nonmuscle myosin isoforms in brain and aorta was studied by using polyclonal antibodies against two synthetic peptides selected from a region near the carboxyl terminus of bovine brain (peptide IIB) and human macrophage (peptide IIA) myosin. Immunoblots of brain homogenates and purified myosin showed two major bands stained by anti-peptide IIB (MIIB1 and MIIB2) and a minor band stained by anti-peptide IIA (MIIA2). Polyclonal anti-human platelet myosin antibodies did not react with MIIB isoforms. In cryosections from bovine, rat, and mouse brains, anti-peptide IIB stained most neuronal cells. In bovine cryosections, glial staining was also observed. In contrast, anti-peptide IIA and anti-platelet myosin antibodies primarily stained blood vessels. In bovine aorta, the anti-peptide antibodies recognized four bands, MIIB3, MIIB4, MIIA1, and MIIA2. Only MIIA2 was recognized by anti-human platelet myosin antibodies. In bovine aorta cryosections, anti-peptide IIB stained smooth muscle cells in tunica intima and tunica media but did not stain endothelial cells. Anti-peptide IIA stained smooth muscle cells in the tunica media, and endothelial cells of vaso vasorum but not of aorta. Only polyclonal anti-platelet myosin antibodies stained the endothelial cells of aorta tunica intima. These results indicate that multiple isoforms of cellular myosins exist in mammals, that these isoforms are expressed in a cell specific manner, and that the major myosin isoforms isolated from whole brain originate from neurons and, at least in bovine brain, from glia, but not from blood vessels. © 1992 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 33-39 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sn-1,2-diacylglycerols (DAG) and ionized-free calcium can act as intracellular second messengers for cell activation. Traditionally, T-lymphocyte activation is assessed by measurements of DNA synthesis or lymphokine production, but these responses require several days to occur and involve multiple intermediary regulatory steps. In contrast, we have found that T-lymphocytes demonstrate rapid enhancement of A-(alanine-favoring) system amino acid uptake when treated with DAG or ionomycin. A 30-40% increase in the initial velocity of uptake (vi) of the synthetic A-system specific amino acid, methylamino-isobutyric acid (MeAIB), was measured following 5 min of exposure to DAG or ionomycin. The vi was enhanced 60% from 12 to 19 μmol/liter cell water per min after 30 min exposure of T-cells to optimal concentrations of dioctanoylglycerol (30 μM), oleoylacetylglycerol (30 μM), or ionomycin (5 μM) (P 〈 .01 for each agent). A 50-fold excess of non-radioactive MeAIB inhibited 80% of [14C]MeAIB uptake in both unstimulated and stimulated cells, indicating that uptake remained largely carrier-mediated on treatment with these agents. Cycloheximide, 100 μg/ml, inhibited protein synthesis but did not block the A-system amino acid transport enhancement induced by DAG or ionomycin. The DAG-induced increase in the vi was blocked 40% with 100 μM H-7, an inhibitor of protein kinase C. H-7 treatment did not inhibit the ionomycin-induced A-system enhancement. A marked increase in cytoplasmic free calcium was measured when T-lymphocytes were exposed to ionomycin but not on DAG exposure, and the A-system effect of ionomycin but not DAG was blocked by extracellular EGTA. These data are compatible with two pathways for rapid enhancement of A-system amino acid uptake in T-lymphocytes. DAG stimulation is mediated via protein kinase C whereas ionomycin produces an A-system effect of similar magnitude independent of protein kinase C by an increase in cytoplasmic calcium.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 1003-1007 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The partitioning of reaction exothermicity into relative translational energy of the products of gas-phase SN2 (F- + CH3Cl) and nucleophilic aromatic substitution (F- + C6H5Cl) reactions has been investigated using kinetic energy release Fourier transform ion cyclotron resonance spectroscopy. The chloride product ion is observed to be highly translationally excited for the SN2 reaction, indicating a cold internal energy distribution for the products. For the chlorobenzene reaction the products are not generated with large translational energies. The results are compared with a statistical model. Ion-intensity profiles for the CH3Cl reaction deviate significantly from the statistical model whereas the chlorobenzene results are consistent with this model. The kinetic energy release for the CH3C1 reaction is compared with energy-disposal results for the photodissociation and dissociative electron-attachment processes of halomethanes. In all three cases a node in the molecular orbital between the carbon atom and the departing halogen results in a repulsive energy release. Ion-retention curves for the nucleophilic aromatic substitution reaction are consistent with the existence of a long-lived ion-dipole complex on the exit channel for this reaction.
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  • 8
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of a series of monocyclic and bicyclic arenes with early transition metal ions (Sc+, Y+, Nb+ and Ta+) and their oxides and dioxides were studied in a Fourier transform ion cyclotron resonance mass spectrometer. Ring cleavage of the nitrogen-containing heterocycles results in loss of HCN as the dominant pathway. Thermochemical considerations, secondary reactions and correlations with solution cyclotrimerization reactions indicate that the MC4H4+ product is a metallacyclopentadiene. Based on correspondence between the reactivities of a series of early metals with their valence electron counts, the reactivities of quinoline and isoquinoline and the decomposition behavior of the products, a metallacycloheptatriene intermediate is proposed for the heteroaromatic ring cleavage reaction. These results are compared to metal complexes in solution which catalyze the [2 + 2 + 2] cyclotrimerization of alkynes and nitriles.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 40 (1989), S. 147-155 
    ISSN: 0730-2312
    Keywords: platelet-activating factor ; prostaglandins ; D-49 snake venom PLA2 ; inflammation ; leukotrienes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Phospholipase A2 (PLA2) is a key component of the inflammatory process because of its role in the generation of eicosanoids and platelet-activating factor (PAF). Manipulation of PLA2 activity offers a novel therapeutic approach for the development of antiinflammatory agents; however, there is a need for a suitable in vivo model. Injection of 1 μg of snake venom PLA2 (A. piscivorus piscivorus, D-49) into the mouse hind footpad produced a significant three- to four-fold rise in paw edema within 10 min, compared to the saline control. Edema formation depended on enzyme concentration and appeared specific for PLA2 since edema was negated by enzyme pretreatment with p-bromophenacyl bromide, a nonspecific PLA2 inhibitor. Moreover, injection of a protein such as bovine serum albumin did not result in significant edema. Coinjection of phenidone (lipoxygenase inhibitor, 50 μg), indomethacin (cyclooxygenase inhibitor, 50 μg), cyproheptadine (antihistamine/antiserotonin, 50 μg), aristolochic acid (putative PLA2 inhibitor, 100 μg), or kadsurenone (PAF antagonist, 50μg) with PLA2 (1 μg/paw) resulted in partial reduction (44.5, 34.2, 54.7, 64, and 50% inhibition, respectively) of edema formation. Oral administration of cyproheptadine (10 mg/kg), indomethacin (10 mg/kg), BW 755c (100 mg/kg), or dexamethasone (1 mg/kg) 1-3 h before challenge also decreased PLA2-induced edema (63.0, 30.1, 47.8, or 62.5% inhibition, respectively). The data suggest that mouse paw edema resulting from PLA2 injection is a multicomponent event, influenced by both autacoids and lipid mediators of inflammation.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 1 (1987), S. 33-37 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 4 Ill.
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