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Abstract
A new ear in cell biology is at hand with the development of tools for imaging molecular functions in living cells and tissues. Specific chemical and molecular events can now be measured and manipulated in cells in order to explore the mechanisms of cell functions. In particular, cytoskeletal processes are being dissected temporally and spatially in single cells from lower eukaryotes, plants, and animals using light-based reagents and electronic light microscopy.
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Clayman GL, el-Naggar AK, Roth JA, Zhang WW, Goepfert H, Taylor DL, Liu TJ. In vivo molecular therapy with p53 adenovirus for microscopic residual head and neck squamous carcinoma. Cancer Res 1995; 55:1-6. [PMID: 7805018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Developing gene therapy strategies may allow contemporary medicine to reassess its management of solid malignancies. We have demonstrated previously that the wild-type p53 adenovirus (Ad5CMV-p53) suppressed the growth of established tumors of the head and neck. In this paper we develop a microscopic residual model which mimics the postsurgical environment of head and neck cancer patients with advanced disease. Using this squamous cell carcinoma of the head and neck model, we prevented the establishment of tumors in nude mice in which tumor cells had been s.c. implanted by transiently introducing exogenous wild-type p53 via an adenoviral vector 2 days following tumor cell implantation. These effects were vector dose dependent but independent on the endogenous wild-type or mutated p53 status of the cells. Importantly, karyotypically normal and nontumorigenic fibroblast cell lines are inert to the p53 adenovirus treatment. These results pave the ground work for further development of molecular therapy for head and neck cancer and other solid malignancies.
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78
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Bridges CG, Brennan TM, Taylor DL, McPherson M, Tyms AS. The prevention of cell adhesion and the cell-to-cell spread of HIV-1 in vitro by the alpha-glucosidase 1 inhibitor, 6-O-butanoyl castanospermine (MDL 28574). Antiviral Res 1994; 25:169-75. [PMID: 7847878 DOI: 10.1016/0166-3542(94)90105-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The intercellular adhesion molecule (ICAM-1, CD54) and its counter receptor, the integrin leukocyte function associated antigen 1 (LFA-1, CD11a/CD18), have important roles in the immune response. These include guiding leukocytes to sites of inflammation (Issekutz and Issekutz, 1992), enhancement of antigen presentation (Moy and Brian, 1992) and potentiation of cytotoxic cell function (Umehara et al., 1992; Sanchez-Madrid et al., 1982). In addition to these activities LFA-1 and ICAM-1 are implicated in the cell-to-cell transmission of human immunodeficiency virus (HIV-1) since antibodies to CD18, CD54 or synthetic peptide analogs of ICAM-1 antagonise the formation of virus-induced syncytia (Fecondo et al., 1993; Gruber et al., 1991; Hildreth and Orentas, 1989; Valentin et al., 1990). The alpha-glucosidase 1 inhibitor 6-O-butanoyl castanospermine (MDL 28574) has antiviral activity for HIV which is manifested by a decrease in syncytia as well as the production of virus with altered gp120 and a reduced infectivity (Taylor et al., 1991). Previously, it has been shown that the alpha-glucose 1 inhibitor (MDL 28574) treatment of human leukocytes in vitro or mouse lymphocytes in vivo affects the detection of LFA-1 but not domain 1 of CD4 nor several other CD markers (Bridges et al., submitted for publication). Here, we demonstrate that pre-treatment of HIV-permissive CD4+ cells with MDL 28574 substantially reduces their capacity to bind with cells chronically infected with HIV-1 which results in reduced virus production.(ABSTRACT TRUNCATED AT 250 WORDS)
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79
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Janson LW, Taylor DL. Actin-crosslinking protein regulation of filament movement in motility assays: a theoretical model. Biophys J 1994; 67:973-82. [PMID: 7811954 PMCID: PMC1225450 DOI: 10.1016/s0006-3495(94)80563-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The interaction of single actin filaments on a myosin-coated coverslip has been modeled by several authors. One model adds a component of "frictional drag" by myosin heads that oppose movement of the actin filaments. We have extended this concept by including the resistive drag from actin crosslinking proteins to understand better the relationship among crosslinking number, actin-myosin force generation, and motility. The validity of this model is supported by agreement with the experimental results from a previous study in which crosslinking proteins were added with myosin molecules under otherwise standard motility assay conditions. The theoretical relationship provides a means to determine many physical parameters that characterize the interaction between a single actin filament and a single actin-crosslinking molecule (various types). In particular, the force constant of a single filamin molecule is calculated as 1.105 pN, approximately 3 times less than a driving myosin head (3.4 pN). Knowledge of this parameter and others derived from this model allows a better understanding of the interaction between myosin and the actin/actin-binding protein cytoskeleton and the role of actin-binding proteins in the regulation and modulation of motility.
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80
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Taylor DL, Kang MS, Brennan TM, Bridges CG, Sunkara PS, Tyms AS. Inhibition of alpha-glucosidase I of the glycoprotein-processing enzymes by 6-O-butanoyl castanospermine (MDL 28,574) and its consequences in human immunodeficiency virus-infected T cells. Antimicrob Agents Chemother 1994; 38:1780-7. [PMID: 7986008 PMCID: PMC284636 DOI: 10.1128/aac.38.8.1780] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The 6-O-butanoyl derivative of castanospermine (MDL 28,574) was previously shown to be approximately 30-fold more potent than the naturally occurring molecule at inhibiting the replication of human immunodeficiency virus (HIV) (D. L. Taylor, P. S. Sunkara, P. S. Liu, M. S. Kang, T. L. Bowlin, and A. S. Tyms, AIDS 5:693-698, 1991). We now report that consistent with its improved anti-HIV activity, MDL 28,574 is more effective (50% inhibitory concentration [IC50], 20 microM) than the parent molecule (IC50, 254 microM) at causing the accumulation of glucosylated oligosaccharides in HIV-infected cells by inhibition of glycoprotein processing. These were predominantly of the glucose 3 type, as determined by P4 Bio-Gel analysis after digestion with purified alpha-glucosidase I, indicating that, intracellularly, this enzyme is the major target for inhibition. MDL 28,574, however, was less active (IC50, 1.27 microM) than castanospermine (IC50, 0.12 microM) against the mutual target enzyme, cellular alpha-glucosidase I, in a cell-free assay system. The increased effects of MDL 28,574 against alpha-glucosidase I in cell culture were attributed to the improved cellular uptake of the more lipophilic derivative. Inhibition of this enzyme activity in HIV-infected H9 cells impaired viral glycoprotein processing and resulted in the expression of abnormally configured gp120. This did not affect virus production, but the virions had decreased infectivity which was partially related to a reduced ability to bind to CD4+ T cells.
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81
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Liu TJ, Zhang WW, Taylor DL, Roth JA, Goepfert H, Clayman GL. Growth suppression of human head and neck cancer cells by the introduction of a wild-type p53 gene via a recombinant adenovirus. Cancer Res 1994; 54:3662-7. [PMID: 8033080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mutations of the p53 gene constitute one of the most frequent genetic alterations in squamous cell carcinoma of the head and neck (SCCHN). In this study, we introduced wild-type p53 into two separate SCCHN cell lines via a recombinant adenoviral vector, Ad5CMV-p53. Northern blotting showed that following infection by the wild-type p53 adenovirus (Ad5CMV-p53), cells produced up to 10-fold higher levels of exogenous p53 mRNA than cells treated with vector only (without p53). Western blotting showed that the increased levels of p53 protein produced in the Ad5CMV-p53-infected cells were a reflection of p53 mRNA expression. In vitro growth assays revealed growth arrest following Ad5CMV-p53 infection as well as cell morphological changes consistent with apoptosis. In vivo studies in nude mice with established s.c. squamous carcinoma nodules showed that tumor volumes were significantly reduced in mice that received peritumoral infiltration of Ad5CMV-p53. These data suggest that Ad5CMV-p53 may be further developed as a potential novel therapeutic agent for SCCHN since introduction of wild-type p53 into SCCHN cell lines attenuates their replication and tumor growth.
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82
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Echeverri EA, Wang MM, Chavaria C, Taylor DL. Multiple dens evaginatus: diagnosis, management, and complications: case report. Pediatr Dent 1994; 16:314-7. [PMID: 7937267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Dens evaginatus is a disturbance in tooth formation that appears clinically as an accessory occlusal tuberculated cusp composed of enamel and dentin, usually enclosing pulp tissue. The tubercle often fractures or is worn away, with subsequent pulp exposure leading to pulpal inflammation, necrosis, and periapical inflammation. When this happens to an immature tooth, diagnosis may be complicated by the similarity in radiographic appearance of the periapical lesion and the dental follicle. The management of such teeth may be complicated because of their immaturity. A case report of multiple abraded dens evaginatus with pulp necrosis is presented that illustrates 1) the difficulty of diagnosing otherwise apparently healthy teeth associated with periapical lesions and sinus tracts, and 2) their management and treatment complications including recurrent infections and root fractures.
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83
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Lee KA, Lentz MJ, Taylor DL, Mitchell ES, Woods NF. Fatigue as a response to environmental demands in women's lives. IMAGE--THE JOURNAL OF NURSING SCHOLARSHIP 1994; 26:149-54. [PMID: 8063323 DOI: 10.1111/j.1547-5069.1994.tb00935.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Fatigue is a significant health care problem of interest to professionals in many disciplines. Yet, it is poorly understood. Fatigue, as an indicator of adaptation, is examined in relationship to internal and external environmental demands in women's lives. From a secondary analysis of data collected from a large group of women in a Northwest urban community in the U.S., it was found that internal demands such as depression or anxiety are more significantly related to fatigue and vitality than external demands such as negative life events or employment status.
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84
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Taylor DL, Davies SE, Obrenovitch TP, Urenjak J, Richards DA, Clark JB, Symon L. Extracellular N-acetylaspartate in the rat brain: in vivo determination of basal levels and changes evoked by high K+. J Neurochem 1994; 62:2349-55. [PMID: 8189239 DOI: 10.1046/j.1471-4159.1994.62062349.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The purpose of this study was to determine the extracellular concentrations of N-acetylaspartate (NAA) in the rat cerebral cortex, striatum, and hippocampus of halothane-anaesthetised rats by intracerebral microdialysis, and to examine the effects of high K(+)-induced local depolarisation, which provokes synchronous neurotransmitter release, cell swelling, and acid-base changes. Basal levels of NAA in the extracellular fluid (ECF) were determined by the zero net flux method. Tissue levels of NAA in the cortex, striatum, and hippocampus were 8.4, 5.7, and 7.2 mmol/kg, respectively. The corresponding extracellular concentrations of NAA were much lower (35.1, 83.7, and 23.0 microM). High tissue/ECF concentration ratios may suggest little release or leakage of NAA under basal conditions, and potent reuptake mechanisms for NAA in the cellular membrane of CNS cells. There was no change in ECF NAA during K(+)-induced local depolarising stimuli produced in the striatum, but NAA levels consistently increased after the K+ stimuli, irrespective of whether or not Ca2+ was present in the perfusion medium. These data confirm that NAA is not a neurotransmitter and suggest strongly that NAA is not directly involved in the release and reuptake or metabolism of neuroactive compounds. The increase of NAA in the ECF immediately after K+ stimulation may reflect an involvement in brain osmoregulation and/or acid-base homeostasis.
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85
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Taylor DL, Richards DA, Obrenovitch TP, Symon L. Time course of changes in extracellular lactate evoked by transient K(+)-induced depolarisation in the rat striatum. J Neurochem 1994; 62:2368-74. [PMID: 8189242 DOI: 10.1046/j.1471-4159.1994.62062368.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The purpose of this study was to establish whether excessive lactate production associated with local application of K+ is reflected at the extracellular level during or after the K+ challenge. Changes in extracellular lactate were continuously monitored by microdialysis coupled to on-line fluorimetric analysis. K(+)-induced changes in dialysate lactate were closely related to those of the direct current potential. High K+ evoked a large and sustained negative shift of direct current potential onto which were superimposed a variable number of transient peaks of further depolarisation. The initial negative shift in direct current potential was associated with a decrease in dialysate lactate, but after each transient depolarisation, the positive shift in direct current potential indicating cell repolarisation was associated with a marked increase in extracellular lactate. When repetitive transient depolarisations occurred during a stimulus, only a small increase after each depolarisation was observed. However, recordings consistently revealed a marked and rapid increase in extracellular lactate after the K+ stimulus. These data indicate that extracellular lactate mostly increased during periods of repolarisation. This suggests strongly that lactic acid transport out of brain cells may be impaired when their transmembrane ionic gradients are disrupted.
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86
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Hahn K, DeBiasio R, Tishon A, Lewicki H, Gairin JE, LaRocca G, Taylor DL, Oldstone M. Antigen presentation and cytotoxic T lymphocyte killing studied in individual, living cells. Virology 1994; 201:330-40. [PMID: 8184542 DOI: 10.1006/viro.1994.1298] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Interactions between individual, living fibroblasts and cytotoxic T lymphocyte (CTL) clones were analyzed by using video-enhanced differential interference contrast and fluorescence microscopy in a multimode configuration. Fibroblasts expressing known major histocompatibility complex I alleles (MC57: H-2b; Balb: H-2d) were sensitized for killing by incubating or microinjecting them with peptide fragments of lymphocytic choriomeningitis virus. Previous determination of the CTL clones' specificity for these peptides and MHC-I alleles enabled us to study CTL killing of fibroblasts, and nonlethal CTL interaction with targets due to "mismatches" of the CTL, target, and/or peptide. During viral peptide-specific MHC-restricted CTL killing, distinct morphological alterations were observed (CTL shape changes, movements of granules in CTL cytoplasm, and target cell contraction and blebbing). When no killing occurred, CTL engaged in prolonged, nonrandom movement on the target cells. Alloreactive and virus-specific CTL displayed the same morphology during killing. To study antigen presentation further within individual, living cells, a LCMV glycoprotein peptide (aa 272-286, LSDSSGVENPGGYCL) was covalently labeled with tetramethylrhodamine. In 51Cr release assays, the labeled peptide specifically induced potent CTL killing, but neither labeled nor unlabeled peptide proved toxic for unsensitized targets. Microinjection of the labeled peptide into the cytoplasm of fibroblast cells led to CTL killing of those cells, yet nearby uninjected cells contacted by CTL were not killed, indicating that killing was due to presentation of microinjected peptide rather than binding of extracellular peptide to cell surface MHC. Peptide-injected target cells were killed only when combined with CTL specific for the peptide and for the MHC allele of the injected cell.
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87
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Post PL, Trybus KM, Taylor DL. A genetically engineered, protein-based optical biosensor of myosin II regulatory light chain phosphorylation. J Biol Chem 1994; 269:12880-7. [PMID: 8175704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Myosin II is an important motor in the contraction of smooth and striated muscle as well as in a variety of non-muscle cell motile events including cytokinesis, cortical contractions during migration of fibroblasts, and capping of receptors. Phosphorylation of the 20-kDa light chain by myosin light chain kinase is part of the regulation of smooth muscle and mammalian nonmuscle myosin II. We designed, characterized, and tested the use of a protein-based optical biosensor to monitor this phosphorylation "switch." A regulatory light chain was genetically engineered to contain a single cysteine at amino acid position 18. The mutant light chain (Cys18.LC20), reacted with the fluorophore acrylodan, responded to phosphorylation of serine 19 with a fluorescence emission quenching of 60% and a 28-nm red-shift. When the acrylodan-labeled mutant light chain (AC-Cys18.LC20) was exchanged into turkey gizzard myosin II, it exhibited a 25% fluorescence emission quenching and a 10-nm red-shift upon phosphorylation of serine 19. The myosin II optical biosensor exhibited nearly control levels of the rate of phosphorylation, K+ATPase activity, and in vitro motility. The acrylodan-labeled light chain was exchanged into the A-bands of chicken pectoralis myofibrils in situ to demonstrate the localization and activity of the biosensor in a highly ordered contractile system. Fluorometry and quantitative fluorescence microscopic imaging experiments demonstrated that AC-Cys18.LC20 exchanged myofibrils expressed a phosphorylation-dependent fluorescence change. Labeled light chains were also incorporated into stress fibers of living fibroblasts and smooth muscle cells. This general approach of combining molecular biology and fluorescence spectroscopy to create novel protein-based optical biosensors should provide valuable tools for investigations with model systems and solution studies and ultimately yield important information about temporal-spatial chemical and molecular changes in live cells.
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88
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Giuliano KA, Taylor DL. Fluorescent actin analogs with a high affinity for profilin in vitro exhibit an enhanced gradient of assembly in living cells. J Cell Biol 1994; 124:971-83. [PMID: 8132718 PMCID: PMC2119972 DOI: 10.1083/jcb.124.6.971] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Constitutive centripetal transport of the actin-based cytoskeleton has been detected in cells spreading on a substrate, locomoting fibroblasts and keratocytes, and non-locomoting serum-deprived fibroblasts. These results suggest a gradient of actin assembly, highest in the cortex at the cytoplasm-membrane interface and lowest in the non-cortical perinuclear cytoplasm. We predicted that such a gradient would be maintained in part by phosphoinositide-regulated actin binding proteins because the intracellular free Ca2+ and pH are low and spatially constant in serum-deprived cells. The cytoplasm-membrane interface presents one surface where the assembly of actin is differentially regulated relative to the non-cortical cytoplasm. Several models, based on in vitro biochemistry, propose that phosphoinositide-regulated actin binding proteins are involved in local actin assembly. To test these models in living cells using imaging techniques, we prepared a new fluorescent analog of actin that bound profilin, a protein that interacts with phosphoinositides and actin-monomers in a mutually exclusive manner, with an order of magnitude greater affinity (Kd = 3.6 microM) than cys-374-labeled actin (Kd > 30 microM), yet retained the ability to inhibit DNase I. Hence, we were able to directly compare the distribution and activity of a biochemical mutant of actin with an analog possessing closer to wild-type activity. Three-dimensional fluorescence microscopy of the fluorescent analog of actin with a high affinity for profilin revealed that it incorporated into cortical cytoplasmic fibers and was also distributed diffusely in the non-cortical cytoplasm consistent with a bias of actin assembly near the surface of the cell. Fluorescence ratio imaging revealed that serum-deprived and migrating fibroblasts concentrated the new actin analog into fibers up to four-fold in the periphery and leading edge of these cells, respectively, relative to a soluble fluorescent dextran volume marker, consistent with the formation of a gradient of actin filament density relative to cell volume. Comparison of these gradients in the same living cell using analogs of actin with high and low affinities for profilin demonstrated that increased profilin binding enhanced the gradient. Profilin and related proteins may therefore function in part to bias the assembly of actin at the membrane-cytoplasm interface.
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89
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Taylor DL. Evaluating therapeutic change in symptom severity at the level of the individual woman experiencing severe PMS. IMAGE--THE JOURNAL OF NURSING SCHOLARSHIP 1994; 26:25-33. [PMID: 8200676 DOI: 10.1111/j.1547-5069.1994.tb00290.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Treatment effectiveness of an intervention designed for women experiencing severe Premenstrual Syndrome (PMS) was assessed at the level of the individual woman since patterns of individual response are of most relevance to practitioners. Symptom severity was evaluated daily in five women across seven menstrual cycles using a time-series methodology. Three symptom severity patterns emerged from the baseline data analysis: a "classic" PMS pattern, a premenstrual magnification pattern and a social week pattern. Patterns of therapeutic response emerged from the time-series analysis of post-treatment data compared with baseline symptom severity patterns: a "normalized" response pattern where symptom severity declined to a mild, cyclic process and an "unstable" response pattern that remained reactive. Treatment effects for menstrual cycle phenomena may be evaluated using the "normalizing" or "unstable" patterns as clinical indicators.
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90
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Taylor DL, DeBiasio R, LaRocca G, Pane D, Post P, Kolega J, Giuliano K, Burton K, Gough B, Dow A. Potential of machine-vision light microscopy in toxicologic pathology. Toxicol Pathol 1994; 22:145-59. [PMID: 7973362 DOI: 10.1177/019262339402200208] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Major developments in machine-vision light microscopy and in reagent chemistry have led to a renaissance and revolution in the use of the light microscope in biology, biotechnology, and medicine. The potential use of this technology in the field of toxicologic pathology is discussed. It is suggested that a combination of investigating living cells and tissues and fixed samples using the new technologies will lead to understanding mechanisms of toxicity. Examples of the use of the methods in basic cell biology and medicine are presented.
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91
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Abstract
Myelodysplasia or myelodysplastic syndromes represent a heterogeneous group of bone marrow disorders characterized by dysmaturation, cytopenias, and a propensity for leukemic transformation. Although universally adopted, the French-American-British classification still has several limitations and an inability to categorize all patients. Refinements in morphologic and histologic interpretation in addition to the use of scoring systems may improve diagnostic and prognostic capability. Cytogenetics and molecular genetic abnormalities are providing clues to the fundamental pathogenesis of myelodysplastic syndromes. However, the lesions responsible for initiation or disease progression are as yet unresolved. Although chemotherapy and allogeneic transplantation may be used in selected patients, the mainstay of therapy remains supportive care, with differentiating therapy being largely disappointing so far and the role of hematopoietic growth factors remaining unresolved.
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92
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Bailey B, Farkas DL, Taylor DL, Lanni F. Enhancement of axial resolution in fluorescence microscopy by standing-wave excitation. Nature 1993; 366:44-8. [PMID: 8232536 DOI: 10.1038/366044a0] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The use of fluorescence microscopy for investigating the three-dimensional structure of cells and tissue is of growing importance in cell biology, biophysics and biomedicine. Three-dimensional data are obtained by recording a series of images of the specimen as it is stepped through the focal plane of the microscope. Whether by direct imaging or by confocal scanning, diffraction effects and noise generally limit axial resolution to about 0.5 microns. Here we describe a fluorescence microscope in which axial resolution is increased to better than 0.05 microns by using the principle of standing-wave excitation of fluorescence. Standing waves formed by interference in laser illumination create an excitation field with closely spaced nodes and antinodes, allowing optical sectioning of the specimen at very high resolution. We use this technique to obtain images of actin fibres and filaments in fixed cells, actin single filaments in vitro and myosin II in a living cell.
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93
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Taylor KM, Rodwell RL, Elliott SL, Taylor DL. Use of X-linked clonal analysis in acute promyelocytic leukemia. Leuk Lymphoma 1993; 11:339-43. [PMID: 8124205 DOI: 10.3109/10428199309067924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
X-linked clonal analysis (XLCA) either using Glucose-6-phosphate dehydrogenase (G-6-P-D) polymorphisms or restriction fragment length polymorphisms (RFLP) and methylation analysis has provided considerable understanding of haematologic malignancy. Acute Promyelocytic Leukemia (APL) is characterized by a unique cytogenetic translocation t(15;17), frequent achievement of remission without a preceding phase of marrow hypocellularity after induction chemotherapy and a high rate of clinical response to all-trans retinoic acid (ATRA). In limited studies XLCA has provided insight into the pathogenesis and mechanism of drug action in this disease.
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94
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Janson LW, Taylor DL. In vitro models of tail contraction and cytoplasmic streaming in amoeboid cells. J Biophys Biochem Cytol 1993; 123:345-56. [PMID: 8408218 PMCID: PMC2119832 DOI: 10.1083/jcb.123.2.345] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We have developed a reconstituted gel-sol and contractile model system that mimics the structure and dynamics found at the ectoplasm/endoplasm interface in the tails of many amoeboid cells. We tested the role of gel-sol transformations of the actin-based cytoskeleton in the regulation of contraction and in the generation of endoplasm from ectoplasm. In a model system with fully phosphorylated myosin II, we demonstrated that either decreasing the actin filament length distribution or decreasing the extent of actin filament cross-linking initiated both a weakening of the gel strength and contraction. However, streaming of the solated gel components occurred only under conditions where the length distribution of actin was decreased, causing a self-destruct process of continued solation and contraction of the gel. These results offer significant support that gel strength plays an important role in the regulation of actin/myosin II-based contractions of the tail cortex in many amoeboid cells as defined by the solation-contraction coupling hypothesis (Taylor, D. L., and M. Fechheimer. 1982. Phil. Trans. Soc. Lond. B. 299:185-197). The competing processes of solation and contraction of the gel would appear to be mutually exclusive. However, it is the temporal-spatial balance of the rate and extent of two stages of solation, coupled to contraction, that can explain the conversion of gelled ectoplasm in the tail to a solated endoplasm within the same small volume, generation of a force for the retraction of tails, maintenance of cell polarity, and creation of a positive hydrostatic pressure to push against the newly formed endoplasm. The mechanism of solation-contraction of cortical cytoplasm may be a general component of the normal movement of a variety of amoeboid cells and may also be a component of other contractile events such as cytokinesis.
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95
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Taylor DL, Kerwick AM, Elliott SL, Rodwell RL, Wright SJ, Marlton PV, Veleba AR, Taylor KM. Discordant neutrophil alkaline phosphatase activity and cytogenetic response in chronic myeloid leukemia treated with alpha-interferon. Pathology 1993; 25:363-6. [PMID: 8165000 DOI: 10.3109/00313029309090860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Decreased neutrophil alkaline phosphatase (NAP) synthesis is a classical feature of Philadelphia (Ph) positive chronic phase chronic myeloid leukemia (CML). Whether this aberration is an integral leukemic property of the cell or results from mediation by other factors is unclear. During alpha-interferon (alpha-IFN) based therapy the relationship between Ph chromosome suppression and NAP synthesis was examined. Four categories of response were observed in 19 patients studied sequentially. Significantly, persistent low NAP activity was observed in one patient in complete cytogenetic remission, while a second group of 7 patients demonstrated normal NAP activity in spite of persistence of the Ph chromosome in 100% of metaphases. In the absence of various clinical influences that can modulate NAP activity in chronic phase CML, the results reinforce the observation that the BCR/ABL fusion gene product is not a key factor influencing NAP activity in CML.
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MESH Headings
- Adult
- Alkaline Phosphatase/blood
- Chromosome Aberrations
- Female
- Gene Rearrangement
- Genes, abl
- Humans
- Hydroxyurea/therapeutic use
- Interferon alpha-2
- Interferon-alpha/therapeutic use
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/enzymology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Male
- Middle Aged
- Neutrophils/enzymology
- Recombinant Proteins
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96
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Farkas DL, Baxter G, DeBiasio RL, Gough A, Nederlof MA, Pane D, Pane J, Patek DR, Ryan KW, Taylor DL. Multimode light microscopy and the dynamics of molecules, cells, and tissues. Annu Rev Physiol 1993; 55:785-817. [PMID: 8466193 DOI: 10.1146/annurev.ph.55.030193.004033] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Kolega J, Nederlof MA, Taylor DL. Quantitation of cytoskeletal fibers in fluorescence images: Stress fiber disassembly accompanies dephosphorylation of the regulatory light chains of myosin II. ACTA ACUST UNITED AC 1993. [DOI: 10.1002/1361-6374(199309)1:3<136::aid-bio2>3.3.co;2-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kolega J, Taylor DL. Gradients in the concentration and assembly of myosin II in living fibroblasts during locomotion and fiber transport. Mol Biol Cell 1993; 4:819-36. [PMID: 8241568 PMCID: PMC300995 DOI: 10.1091/mbc.4.8.819] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Assembly and motor activity of myosin II affect shape, contractility, and locomotion of nonmuscle cells. We used fluorescent analogues and imaging techniques to elucidate the state of assembly and three-dimensional distribution of myosin II in living Swiss 3T3 fibroblasts. An analogue of myosin II that was covalently cross-linked in the 10S conformation and unable to assemble served as an indicator of the cytoplasmic volume accessible to 10S myosin II. Ratio-imaging of an analogue that can undergo 10S-->6S conversion versus the volume indicator revealed localized concentration of assembly-competent myosin II. In stationary serum-deprived cells and in cells locomoting at the edge of a wound, it was most concentrated in the peripheral cytoplasm, where fibers containing myosin II assemble, and least concentrated in the perinuclear cytoplasm, where they disassemble. Furthermore, fluorescence photobleaching recovery showed myosin II to be less mobile in the periphery than in perinuclear cytoplasm. These results indicate a gradient in the assembly of myosin II. Three-dimensional microscopy of living cells revealed that fibers containing myosin II were localized in the cortical cytoplasm, whereas myosin II was diffusely distributed in the deeper cytoplasm, suggesting that myosin II is assembled preferentially near the cell surface. Localized protein phosphorylation may play a role, because a kinase inhibitor, staurosporine, abolished the gradient of myosin II assembly.
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Gough AH, Taylor DL. Fluorescence anisotropy imaging microscopy maps calmodulin binding during cellular contraction and locomotion. J Cell Biol 1993; 121:1095-107. [PMID: 8501117 PMCID: PMC2119692 DOI: 10.1083/jcb.121.5.1095] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Calmodulin is a calcium transducer that activates key regulatory and structural proteins through calcium-induced binding to the target proteins. A fluorescent analog of calmodulin in conjunction with ratio imaging, relative to a volume indicator, has demonstrated that calmodulin is uniformly distributed in serum-deprived fibroblasts and there is no immediate change in the distribution upon stimulation with complete serum. The same fluorescent analog of calmodulin together with steady state fluorescence anisotropy imaging microscopy has been used to define the temporal and spatial changes in calmodulin binding to cellular targets during stimulation of serum-deprived fibroblasts and in polarized fibroblasts during wound healing. In serum-deprived fibroblasts, which exhibit a low free calcium ion concentration, a majority of the fluorescent analog of calmodulin remained unbound (fraction bound, fB < 10%). However, upon stimulation of the serum-deprived cells with complete serum, calmodulin binding (maximum fB approximately 95%) was directly correlated with the time course of the elevation and decline of the free calcium ion concentration, while the contraction of stress fibers continued for an hour or more. Calmodulin binding was also elevated in the leading lamellae of fibroblasts (maximum FB approximately 50%) during the lamellar contraction phase of wound healing and was spatially correlated with the contraction of transverse fibers containing myosin II. Highly polarized and motile fibroblasts exhibited the highest anisotropy (calmodulin binding) in the retracting tails and in association with contracting transverse fibers in the cortex of the cell. These results suggest that local activation of myosin II-based contractions involves the local binding of calmodulin to target proteins. The results also demonstrate a powerful yet simple mode of light microscopy that will be valuable for mapping molecular binding of suitably labeled macromolecules in living cells.
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Hahn KM, Conrad PA, Chao JC, Taylor DL, Waggoner AS. A photocross-linking fluorescent indicator of mitochondrial membrane potential. J Histochem Cytochem 1993; 41:631-4. [PMID: 8450203 DOI: 10.1177/41.4.8450203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Ionic dyes that distribute across membranes according to electrical potential have proven valuable as fluorescent indicators of mitochondrial energetics in living cells. Applications have been limited, however, as potential-dependent staining is lost during cell fixation. We have produced a membrane potential indicator whose potential-dependent distribution can be made permanent, to enable correlation of membrane potential with cytochemical information from immunofluorescence. A carbocyanine dye was derivatized with a photoreactive nitrophenylazide moiety so that irradiation would induce nonspecific, covalent attachment to nearby molecules. Photo-induced cross-linking was observed in paper chromatography, when irradiation caused immobilization of the dye. The new dye, named PhoCy (photofixable cyanine), showed specific staining of mitochondria in living Swiss 3T3 fibroblasts. When living cells were stained, irradiated, and fixed with formaldehyde, mitochondrial staining was retained owing to cross-linking with mitochondrial components. Omission of irradiation eliminated mitochondrial staining in fixed cells. Labeling, irradiation, and fixation procedures were optimized to produce bright specific staining with minimal background. The indicator's sensitivity to mitochondrial potential was demonstrated by treating cells with 2,4-dinitrophenol, an uncoupler of mitochondrial electron transport, which decreased mitochondrial staining in living cells and in the corresponding fixed specimens.
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