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  • Life and Medical Sciences  (1,981)
  • FLUID MECHANICS AND HEAT TRANSFER
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  • 1
    Electronic Resource
    Electronic Resource
    Preparation of biological tissue sections for correlative ion, electron, and light microscopy (1984)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 1 (1984), S. 299-309 
    Details
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Ion microscopy ; Correlative microscopy ; Electron probe microanalysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In order to correctly interpret the chemical images obtained using ion microscopy (IM), it is useful to correlate them with the information provided by conventional light microscopy (LM), secondary electron imaging (SEI), backscattered electron imaging (BEI), and electron probe microanalysis (EPMA). Accordingly, we have devised a technique of specimen preparation which allows for the application of several different microanalytical techniques to a single histologic section mounted on the same substrate. Sections are cut onto polyester plastic coverslips (devoid of peaks for any element with atomic number 〉 9 using EPMA) and studied by LM. After a light rotary coating with carbon (to prevent charging), the section can then be examined by SEI, BEI, and EPMA. Specific areas can be marked for IM study either with an objective-mounted pin tissue microlocater, or by placing small pieces of metal foil, cut in specific geometric shapes, over features of interest. After sputter-coating the sample with platinum, metal-free shadows are visible using a low-power reflected light microscope available on a typical IM sample chamber as a guide for ion beam placement. The conductive coatings also minimize specimen charging during IM. Post-IM light microscopy, SEI, and BEI are used to confirm the location of specific areas probed in the IM experiments and to provide information on differential ion-sputtering artifacts and tissue contaminants. This new correlative technique should permit better understanding of the images obtained with these diverse instruments.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060010309
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  • 2
    Electronic Resource
    Electronic Resource
    Modulatory function of protein kinase C in the activation of ornithine decarboxylase and in cAMP production in rat osteoblasts (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 138 (1989), S. 548-554 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of activation of protein kinase C on stimulation of ornithine decar-boxylase (ODC) activity and cAMP production was studied in fetal rat osteoblasts. Both phorbol 12-myristate, 13-acetate (PMA), an activator of protein kinase C, and 4α-phorbol, ineffective in activating protein kinase C, failed to stimulate ODC activity and cAMP production. We tested the effect of protein kinase C on stimulation of ODC activity by parathyroid hormone (PTH) and forskolin. In contrast to PTH-stimulated ODC activity, which was not affected by PMA, forskolin-stimulated (1 and 10 μM) ODC activity was dose dependently reduced. PMA (400 nM) reduced both 1 and 10 μM forskolin-stimulated ODC activity to the same level, ∼ 3 nmol CO2/mg protein, which suggests a controlling role of protein kinase C in forskolin-stimulated ODC activity. The study of the effect of protein kinase C on PTH- and forskolin-stimulated cAMP production also revealed differences between PTH and forskolin. When PMA was added simultaneously with PTH (4 and 20 nM) or forskolin (1 and 10 μM) the PTH-stimulated cAMP production was dose-dependently potentiated by PMA, whereas forskolin-stimulated cAMP production was not affected. However, both PTH- and forskolin-stimulated cAMP production was dose-dependently augmented when PMA was added 3 min prior to PTH or forskolin. With increasing preincubation periods (up to 24 h) with PMA instead of a potentiation an inhibition was observed. This inhibition is not due to PTH receptor desensitization, although, on basis of the present results desensitization can not completely be excluded. In all cases 4α-phorbol was without effect. The present results show that protein kinase C modulates stimulation of ODC activity and cAMP production in fetal rat osteoblasts. The modulation of both ODC activity and cAMP production appears to be dependent on the nature of the stimulator. The present data suggest a role for protein kinase C in limiting the cAMP-mediated stimulation of ODC activity in these cells. Furthermore, it is suggested that protein kinase C can interfere at more than one site in the cAMP-generating system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041380315
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  • 3
    Electronic Resource
    Electronic Resource
    Pharmacological profile of the substituted beta-lactam L-659,286: A member of a new class of human PMN elastase inhibitors (1989)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 39 (1989), S. 47-53 
    Details
    ISSN: 0730-2312
    Keywords: elastase inhibitors ; β-lactams ; lung damage ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human polymorphonuclear leukocyte elastase (PMN elastase) is inhibited by L-659, 286 (7α-methoxy-8-oxo-3-[[(1,2,5,6-tetrahydro-2-methyl-5,6-dioxo-1,2,4-triaz-in-3-yl)thio]methyl]-5-thia-1-aza-6R-bicyclo [4.2.O]oct-2-ene-2-pyrrolidine carboxamide-5,-dioxide) with a Ki of 0.4 μM. This inhibition is time-dependent, rapid, and only slowly reversible, with a t1/2 of 〉 3 days at 25°C. L-659, 286 is also highly selective for PMN elastase, as it does not inhibit thrombin, trypsin, papain, plasmin, chymotrypsin, or cathepsin G. L-659, 286 administered intratracheally inhibits lung damage caused by administration via the same route of human PMN elastase into hamsters. In marmosets, L-659, 286 is cleared from blood very rapidly after an intravenous injection but is recovered in bronchoalveolar lavage fluid for several hours after intratracheal administration.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240390106
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  • 4
    Electronic Resource
    Electronic Resource
    In vitro fertilization, development, and implantation after exposure of mature mouse oocytes to visible light (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 297-302 
    Details
    ISSN: 1040-452X
    Keywords: Light exposure ; Implantation rate ; IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mature mouse oocytes were exposed prior to in vitro fertilization to visible light during 1, 2, or 4 hr at an intensity of 4,000 lux. Compared to controls cultured under identical conditions but protected from light, exposed eggs did not show any significant modification of cleavage speed are rate. After transfer of blastocysts obtained in vitro in uteri of pseudopregnant females, the implantation rate and the proportion of normal fetuses were not found to be different in relation to preliminary light exposure of oocytes fertilized and cultured in vitro. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080330310
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  • 5
    Electronic Resource
    Electronic Resource
    Flow cytometric detection of bicarbonate-induced changes in lectin binding in boar and ram sperm populations (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 164-176 
    Details
    ISSN: 1040-452X
    Keywords: Capacitation ; FITC-lectins ; Spermatozoa ; Cell surface ; Glycoconjugates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Boar and ram spermatozoa were incubated in Tyrode's medium in the presence or absence of bicarbonate/CO2, a component believed essential for capacitation. At intervals, samples were stained with a range of FITC-lectins to detect changes in surface glycoconjugates, using a rapid staining technique to avoid problems of lectin toxicity. The samples were then analysed directly by flow cytometry, using propidium iodide to distinguish dead cells. In the presence of bicarbonate, a live subpopulation of spermatozoa developed, which in both animal species showed higher binding affinities towards Phaseolus Vulgaris Agglutinin (PHA-E), Sophora Japonica Agglutinin (SJA), and Soybean Agglutinin (SBA), and lower binding affinity towards Erythrina Cristagalli Lectin (ECL). In boar samples, the modified subpopulation reached a maximum after 3 hr incubation, whereas in ram samples it maximized after 1.5 hr. No changes were seen when spermatozoa were incubated in bicarbonate-free medium. The bicarbonate-induced changes in lectin binding were not due to the onset of acrosome reactions, because spermatozoa induced to undergo acrosome reactions with the ionophore A23187 displayed very different lectin-binding patterns. Tested on boar spermatozoa, seminal plasma not only inhibited but reversed the bicarbonate-induced development of the modified subpopulation. EGTA also inhibited development of boar sperm subpopulations; excess Ca2+ was unable to overcome this inhibition, suggesting that multivalent metal ions might be involved in bicarbonate's action. We conclude that bicarbonate causes a loss of surface coating material with affinity for ECL and an unmasking of binding sites for SBA, SJA and PHA-E. A modified subpopulation of live spermatozoa is thereby established, which appears to maximize at a rate in accord with reported capacitation times. © 1995 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080400205
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  • 6
    Electronic Resource
    Electronic Resource
    Microscopy in solid state science (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 24 (1993), S. 299-315 
    Details
    ISSN: 1059-910X
    Keywords: STEM ; PEELS ; HAADFI ; Nanolithography ; Super-resolution ; STM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The Microstructural Physics group at the Cavendish Laboratory is actively involved in a considerable number of research projects which cover a broad range of materials science. In this paper, we describe briefly several such projects, with particular emphasis given to the application of parallel-detection electron energy loss spectroscopy (PEELS) on a scanning transmission electron microscope (STEM) to the analysis of materials such as stainless steels, catalysts, and high temperature superconductors. In addition, we describe a number of related projects that are currently being carried out in the group, particularly those which utilise and develop novel STEM imaging and analytical techniques. © 1993 Wiley-Liss, Inc.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070240404
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of follicle size on bovine oocyte quality and developmental competence following maturation, fertilization, and culture in vitro (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 37 (1994), S. 48-53 
    Details
    ISSN: 1040-452X
    Keywords: Cattle ; IVM ; IVC ; IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The aim of the present series of experiments was to investigate the effect of the size of follicle from which the oocytes originate on their subsequent in vitro developmental ability. Ovarian follicles were isolated and grouped according to size (2-6 mm, 〉6 mm). Primary oocytes were carefully liberated and grouped according to morphology into one of five categories: denuded; expanded; with two or three layers of cumulus; with four or five layers; and with many (six or more) layers. Following in vitro maturation (IVM), fertilization (IVF), and culture (IVC), more oocytes with many layers of cumulus (P 〈 0.01, 70.2%, 73/104 vs. 46.8%, 87/186, respectively) and a higher proportion of blastocysts were obtained from follicles 〉 6 mm compared to 2-6 mm follicles (P 〈 0.01, 65.9%, 60/91 from 〉6 mm follicles vs. 34.3%, 34/99 from 2-6 mm follicles, respectively). Use of follicular fluid (BFF) from follicles of different sizes in the IVM medium did not significantly increase the cleavage rate or blastocyst yield compared to controls. Administration of procine folliclestimulating hormone (pFSH) to donors prior to slaughter was investigated as a possible means of increasing the number of larger sized follicles in the ovaries and, thereby, the quality of the recovered oocytes. It was found that administration of six injections of pFSH beginning 3 days prior to slaughter resulted in a significant increase (P 〈 0.001) in the proportion of follicles 〉6 mm in diameter (31.6%) compared to that in nontreated controls (6.6%) and to animals that received only four injection groups (9.4%). The blastocyst yield from oocytes originating from 〉6 mm follicles, whether from unstimulated or from pFSH-treated animals, was approximately double that of oocytes from 2-6 mm follicles (P 〈 0.01; 42.9%, 24/56 for 〉6 mm follicles vs. 22.8%, 21/92 for 2-6 mm follicles, respectively, for the 6 pFSH group; P 〉 0.05; 62.5%, 5/8 for 〉6 mm follicles vs. 32.8%, 22/67 for 2-6 mm follicles, respectively, for the control). © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080370107
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  • 8
    Electronic Resource
    Electronic Resource
    Polyadenylate-deficient analogues of poly(A)-containing mRNA sequences in cultured AKR mouse embryo cells (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 103 (1980), S. 417-428 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Five to six percent (by mass) of AKR-2B mouse embryo cell polysomal RNA consists of messenger RNA sequences which may exist in polyadenylated form. In the steady state, however, only 30-40% of these molecules are retained by extensive passage over oligo(dT)-cellulose, the remainder being present in the form of poly(A)-deficient analogues. Within experimental limits, these poly(A)-deficient analogues contain representatives of all poly(A)-containing mRNA sequences in these cells. An analysis of the kinetics of hybridization of cDNA probes enriched for either abundant or rare poly(A)-containing mRNA sequences suggests that the frequency distributions of poly(A)-containing and poly(A)-deficient analogues are dissimilar, and that a relationship exists between the intracellular frequency of a given mRNA sequence and the number of poly(A)-deficient analogues of that sequence. High frequency sequences appear to be enriched in the poly(A)-containing fraction, while low frequency sequences are predominately associated with the poly(A)-deficient fraction, thus, poly(A) may play a role in the regulation of mRNA frequency in the cytoplasm.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041030307
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  • 9
    Electronic Resource
    Electronic Resource
    Development of calcium and secretory responses in the human promyelocytic leukemia cell line HL60 (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 119 (1984), S. 241-246 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have begun to characterize the development of the excitation - response coupling sequence in the human promyelocytic leukemia cell line HL60. Using the recently developed fluorescent calcium probe quin-2, it was found that DMSO induced myeloid differentiation of the HL60 cells is accompanied by the development of a calcium response to the addition of the chemotactic factors fMet-Leu-Phe and leukotriene B4. The characteristics (time course, concentration dependence, stereospecificity, and metabolic dependence) of the calcium response are extremely similar to those previously described in human neutrophils. These results imply that functional receptors for leukotriene B4 appear in HL60 cells upon the induction of differentiation and also lend strong support to the use of these HL60 cells as a model of human myeloid differentiation. We have also characterized the emergence of a secretory response to fMet-Leu-Phe and leukotriene B4 in cytochalasin B treated HL60 cells. In addition, it is found that differentiation was required for the calcium ionophore A23187 to express its secretory activity toward the HL60 cells. This last set of results implies that differentiation is accompanied by the coordinated appearance of surface receptors and cytoplasmic factors required for the expression of cellular responsiveness.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041190215
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  • 10
    Electronic Resource
    Electronic Resource
    Intracellular calcium redistribution and its relationship to fMet-Leu-Phe, leukotriene B4, and phorbol ester induced rabbit neutrophil degranulation (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 122 (1985), S. 273-280 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The addition of low concentrations (〈10-7 M) of the calcium ionophore A23187 to rabbit neutrophils re'eases the intracellular pool of calcium previously shown in radioactive steady-state and chlortetracycline fluorescence studies to be mobilized by chemotactic factors. A23187 at these concentrations elicits no functional responses from these cells. However, A23187, added before chemotactic factors such as fMet-Leu-Phe and leukotriene B4, inhibits the ability of the latter stimuli to induce, in the presence of cytochalasin B, an exocytotic release of the neutrophil's cytoplasmic granules. These results imply that the chemotactic-factor-induced release of intracellular calcium is a necessary event for the optimal activation of the neutrophils. Phorbol esterinduced neutrophil degranulation on the other hand is unaffected by exposure to A23187, thereby completely dissociating its mechanism of action from rises in cytoplasmic free calcium.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041220217
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