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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    ISSN: 0261-5606
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    ISSN: 0261-5606
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract.  It is hypothesized that metabolic and mechanical changes in human locomotion associated with changes in speed v are constrained by two attractive strategies: Q metab=1 and ΔQ metab/Δv=a positive definite constant. Q metab=ΔE k s-1/ml O2 s-1 where ΔE k s-1 is the summed increments and decrements per unit time in the translational and rotational kinetic energies of the body’s segments and ml O2 s-1 is the rate at which chemical energy is dissipated. The expected constancy of ΔQ metab/Δv was derived from an extension of Ehrenfest’s adiabatic hypothesis by which transformations (increases, decreases) in locomotion v can be considered as adiabatic, even though the biological conditions are nonconservative and non-rate-limited. The expected significance of Q metab=1 was derived from stability considerations of the symmetry per stride of stored and dissipated energy. An experimental evaluation was provided by collecting metabolic and mechanical measures on walking (10 subjects) and running (9 subjects) at progressively greater treadmill speeds but within the aerobic limit. Results revealed that walking was restricted to Q metab?1, with a nonlinear trajectory in v×Q metab coordinates shaped by Q metab=1 (primarily) and the constancy of ΔQ metab/Δv. Running satisfied Q metab〉1, with a linear trajectory in v×Q metab coordinates conforming to ΔQ metab/Δv=a constant, with the constant predicted from invariants in the mechanical space v×ΔE k s-1. Results also suggested that the metabolic costs of running might be predictable from measures made in the v×ΔE k s-1 space.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A new electron carrier, Meldola Blue (8-dimethylamino-2,3-benzophenoxazine; Boehringer Mannheim GmbH, Deutsche Patentschrift P 1959410) was tested for its usefulness in the histochemical demonstration of dehydrogenase activity in adrenal cortex, liver, heart muscle of guinea pig and human oviduct and compared with PMS. For demonstrating SDH activity Meldola Blue (MB) is as efficient as PMS. A decisive advantage of MB as compared with PMS is its low sensitivity to light exposure, facilitating direct visualisation of histochemical reaction processes. Generally, a high diffusion rate of reduced electron carriers (PMS and MB) from the section into the incubation medium (PVA) leads to a loss of reduction equivalents, particularly in the demonstration of NAD- or NADP-dependent dehydrogenases (LDH, G-6-PDH) with lower TNBT concentrations. However, no inhibition of SDH-, LDH- and G-6-PDH activities was observed with incubation media containing the tested concentrations of PMS and MB.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A gel-sandwich technique for the histochemical demonstration of dehydrogenases is introduced with LDH set up as an example. Especially suitable, of the gels examined, for this technique is 1.5% W/V agar-agar low gel strength. In it several reaction ingredients for the histochemical reaction are dissolved. Considering LDH the following gel composition showed good results: 1.5% W/V agar-agar low gel strength, 5 mM TNBT in 150 μl DMF, 120 mM L-lactate, 3–5 mM NAD+, 10 mM amytal, 22,4–32×10−5 M Meldola Blue, 160 mM soldium phosphate buffer pH 7.6 (total solution of 1 ml). After the solidification of the gel, gel-bars were frozen with CO2-snow. The 40–80 μm thick gel slices were gained in the cryostat. Of the three different arrangement possibilities of the gel slices and the tissue-sections a sandwich arrangement (cover-gel slice — tissue section — ground-gel slice) produced the best results. The enzyme reaction is started by thawing of the gel slices (together with the tissue sections) and by putting them between the hotplate and the evaporator-head-piece, especially developed for this technique. The gel slices also remain in combination with the tissue sections after the reaction. The influence of the gel in combination with the electron carrier Meldola Blue on the spontaneous reduction rates of ditetrazolium salts in day light, were examined as well as the diffusion rates of TNBT and NADH out of gel slices and the influence of DMF and DMSO on the LDH activity. This technique prevents both, the loss of enzymes and the loss of reduction equivalents. There are given presuppositions for qualitative and quantitative histochemical investigations as well. The advantages of the new gel technique are discussed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An instrumental setup is described for the measurement of enzyme kinetics and morphometry in tissue sections. It consists of a Vickers M85 microdensitometer and computer-assisted Kontron Videoplan system. The Videoplan system consists of a minicomputer with two mini-floppy disks, a keyboard, a graphic tablet, a TV monitor and a printer/plotter. The measuring component of the M85 is linked to the minicomputer via a BCD interface, and the optical system of the M85 is coupled to a TV camera for display on the monitor screen. The enzyme-kinetic data obtained with the M85 in a specified area of the tissue section (density values as a function of reaction time) are stored in the minicomputer. The measurement process is controlled by a corresponding measuring program. Through correlation analysis (a component of the commercial software) between density values and reaction time, the initial and thus maximum enzyme activity is determined. Upon completion of the kinetic measurements, the measured area of tissue is transferred by the TV camera to the monitor, and the reaction area is described and measured with the graphic tablet in video dialogue and related to the initial enzyme activity. With the setup described, it is possible to make microdensitometric measurements of enzyme activities in a specified tissue area while morphometrically analyzing the associated reaction area. To illustrate the use of the system, enzyme-kinetic (succinate dehydrogenase) and morphometric measurements are performed in tissue sections from the proximal tubule of the rat nephron. Additional applications of the system are discussed.
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  • 7
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Aminopeptidase A (E.C.3.4.11.7; APA) can be demonstrated histochemically in the rat and mouse kidney by light microscopy (simultaneous azo coupling with α-Glu-MNA as substrate and high-purity FBB as coupling agent) mainly in the brush borders, glomeruli and portions of the juxtaglomerular apparatus. Sex and species differences are found with regard to enzyme activity and localization. The relation of aminopeptidase A to angiotensinase A was established by inhibition experiments with angiotensin II and III. The following significant differences exist with respect to other aminopeptidases (aminopeptidase M and γ-glutamyl transferase), which were also demonstrated: APM shows no dependence on calcium ions; APM and γ-GT are not demonstrable in the glomerulus or juxtaglomerular apparatus.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Glucose-6-phosphate dehydrogenase (G6PD) was localized in rat spinal cord by catalytic enzyme histochemistry and immunocytochemistry. G6PD detected by either method was shown to be strongly enriched in cell bodies and processes of oligodendrocytes, whereas in the compact myelin G6PD was not detected. The enzyme histochemical procedure for the demonstration of G6PD was also adapted for microphotometric measurements of G6PD activity in the spinal cord white matter. There was a linear relationship between G6PD activity and section thickness up to 14 μm and between G6PD activity and reaction time up to 5–6 min as demonstrated by kinetic and end-point measurements. Significantly lower activities were measured in endpoint measurements than in kinetic measurements because of formazan loss during rinsing. Methoxyphenazine methosulphate as an exogenous electron carrier and sodium azide as a blocker of the respiratory chain significantly increased the demonstrable G6PD activity. The K m was 0.62 mM and the V max 3 μmol glucose-6-phosphate/cm3 wet tissue and per min at 25°C. It is concluded that G6PD in oligodendrocytes may be important for the generation of NADPH required for lipid biosynthesis related to myelogenesis, and reduction of glutathione required for protection of membrane sulphydryl groups.
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  • 9
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present investigation was undertaken in order to establish an optimal tissue pretreatment and an optimal incubation medium for the histochemical demonstration of succinate dehydrogenase (E.C. 1.3.99.1). The investigations were performed on steroid producing (testicle, adrenal gland) and steroid dependent (Fallopian tube) tissues. We studied the influences of formalin fixation, acetone, magnesium ions, cyanides, electron carriers (phenazine methosulfate, menadione, coenzyme Q10), osmolarity, substrate concentration and inhibitors (oxalacetate, oxalate, malonate, 4-chloromercuribenzoic acid). The following procedure yields blameless morphological integrity and enzyme localization as well as optimal SDH-activity: Freezing of tissue cubes (diameter less than 5 mm) in propane cooled with liquid nitrogen or in melting freon. Incubation of 5 μm cryostat sections in narrow jars in the following medium (38.5 ml): - 10 ml of 0.2 M sodium phosphate buffer pH 7.6 (52 mM). - 18 mg tetranitro-BT in 0.5 ml dimethylformamide and aqua bidest. ad 10 ml (0.5 mM). - 2.6 mg KCN in 16 ml aqua bidest. (1 mM). - 540 mg succinate (disodium salt, hexahydrate) in 2 ml aqua bidest. (52 mM). - 3 mg PMS (phenazine methosulfate) in 0.5 ml aqua bidest. (0.25 mM). The incubation medium has an osmolarity of 440 mosm. The incubation is carried out for 10 min at 37° C in darkness. To avoid non specific formazan deposits in lipid containing tissues a preincubation of the cryostat sections in 100% acetone at −22° C or −40° C for 7–10 min and an incubation time of 20–30 min is recommended. Control incubations adduced proof at the specificity of the SDH demonstration. Parallel incubation without PMS in order to determine indirectly the content of endogenous CoQ10 is further recommended.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 75 (1982), S. 215-218 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fluorescence demonstration of cathepsin B (E.C. 3.4.22.1) activity was performed in the yolk sac of rats near term (18th day of gestation). The enzyme demonstration was performed on freeze-dried and celloidin mounted yolk-sac sections using different substituted β-naphthylamide derivatives as substrates and nitrosalicylaldehyde as coupling agent. The discrete reaction products are localized preferentially in the apical part of the visceral yolk-sac epithelium. There is little doubt that cathepsin B is contained here in the well developed lysosomal apparatus of the yolk-sac epithelium.
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