The dynamic structure of the deep Earth: an interdisciplinary approach

The chromatin of eukaryotic cells is separated from the cytoplasm by a double membrane. One obvious structural specialization of the nuclear membrane is the presence of pores which have been implicated to facilitate the selective nucleocytoplasmic exchange of a variety of large molecules. Thus, the function of nuclear pores has mainly been regarded to be a passive one. Non-membranous diaphragms, radiating fibers, central rings, and other pore-associated structures were thought to play a role in the selective filter function of the nuclear pore complex. Evidence will be presented that suggests that the nuclear pore is a dynamic structure which is non-randomly distributed and can be formed during interphase, and that a close relationship exists between chromatin and the membranous part of the nuclear pore complex.Octagonality of the nuclear pore complex has been confirmed by a variety of techniques. Using the freeze-etching technique, it was possible to show that the membranous part of the pore complex has an eight-sided outline in human melanoma cells in vitro. Fibers which traverse the pore proper at its corners are continuous and indistinguishable from chromatin at the nucleoplasmic side, as seen in conventionally fixed and sectioned material. Chromatin can be seen in octagonal outline if serial sections are analyzed which are parallel but do not include nuclear membranes (Fig. 1). It is concluded that the shape of the pore rim is due to fibrous material traversing the pore, and may not have any functional significance. In many pores one can recognize a central ring with eight fibers radiating to the corners of the pore rim. Such a structural arrangement is also found to connect eight ribosomes at the nuclear membrane.

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Application of FRAP and digitized fluorescence microscopy to problems in cell membrane dynamics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102675 ◽

1988 ◽

Vol 46 ◽

pp. 118-119

Author(s):

K. Jacobson ◽

A. Ishihara ◽

B. Holifield ◽

F. Zhang

Keyword(s):

Fluorescence Microscopy ◽

Cell Biology ◽

Extended Period ◽

Dynamic Structure ◽

Living Cells ◽

Membrane Dynamics ◽

Molecular Cell Biology ◽

Image Averaging ◽

Single Living Cells ◽

Single Living

Our laboratory is concerned with understanding the dynamic structure of the plasma membrane with particular reference to the movement of membrane constituents during cell locomotion. In addition to the standard tools of molecular cell biology, we employ both fluorescence recovery after photo- bleaching (FRAP) and digitized fluorescence microscopy (DFM) to investigate individual cells. FRAP allows the measurement of translational mobility of membrane and cytoplasmic molecules in small regions of single, living cells. DFM is really a new form of light microscopy in that the distribution of individual classes of ions, molecules, and macromolecules can be followed in single, living cells. By employing fluorescent antibodies to defined antigens or fluorescent analogs of cellular constituents as well as ultrasensitive, electronic image detectors and video image averaging to improve signal to noise, fluorescent images of living cells can be acquired over an extended period without significant fading and loss of cell viability.

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Structure, assembly and interactions of the nuclear lamina and the nuclear pore complex

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012285x ◽

1992 ◽

Vol 50 (1) ◽

pp. 490-491

Author(s):

N. Panté ◽

M. Jarnik ◽

E. Heitlinger ◽

U. Aebi

Keyword(s):

Nuclear Pore Complex ◽

Divalent Cations ◽

Nuclear Lamina ◽

Dynamic Structure ◽

Nucleocytoplasmic Transport ◽

Nuclear Pore ◽

Cytoplasmic Filaments ◽

Radial Spokes ◽

Nuclear Ring ◽

Central Plug

The nuclear pore complex (NPC) is a ∼120 MD supramolecular machine implicated in nucleocytoplasmic transport, that is embedded in the double-membraned nuclear envelope (NE). The basic framework of the ∼120 nm diameter NPC consists of a 32 MD cytoplasmic ring, a 66 MD ‘plug-spoke’ assembly, and a 21 MD nuclear ring. The ‘central plug’ seen in en face views of the NPC reveals a rather variable appearance indicating that it is a dynamic structure. Projecting from the cytoplasmic ring are 8 short, twisted filaments (Fig. 1a), whereas the nuclear ring is topped with a ‘fishtrap’ made of 8 thin filaments that join distally to form a fragile, 30-50 nm distal diameter ring centered above the NPC proper (Fig. 1b). While the cytoplasmic filaments are sensitive to proteases, they as well as the nuclear fishtraps are resistant to RNase treatment. Removal of divalent cations destabilizes the distal rings and thereby opens the fishtraps, addition causes them to reform. Protruding from the tips of the radial spokes into perinuclear space are ‘knobs’ that might represent the large lumenal domain of gp210, a membrane-spanning glycoprotein (Fig. 1c) which, in turn, may play a topogenic role in membrane folding and/or act as a membrane-anchoring site for the NPC. The lectin wheat germ agglutinin (WGA) which is known to recognize the ‘nucleoporins’, a family of glycoproteins having O-linked N-acetyl-glucosamine, is found in two locations on the NPC (Fig. 1. d-f): (i) whereas the cytoplasmic filaments appear unlabelled (Fig. 1d&e), WGA-gold labels sites between the central plug and the cytoplasmic ring (Fig. le; i.e., at a radius of 25-35 nm), and (ii) it decorates the distal ring of the nuclear fishtraps (Fig. 1, d&f; arrowheads).

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Modulated polarization microscopy displays the dynamics of cytoskeletal structures in living, motile cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100140889 ◽

1995 ◽

Vol 53 ◽

pp. 902-903

Author(s):

J. R. Kuhn ◽

M. Poenie

Keyword(s):

Mitotic Spindle ◽

Actin Filaments ◽

Cell Shape ◽

Dynamic Structure ◽

Living Cells ◽

Cytoskeletal Proteins ◽

Polarization Microscopy ◽

Video Enhancement ◽

Ultrastructural Studies ◽

Motile Cells

Cell shape and movement are controlled by elements of the cytoskeleton including actin filaments an microtubules. Unfortunately, it is difficult to visualize the cytoskeleton in living cells and hence follow it dynamics. Immunofluorescence and ultrastructural studies of fixed cells while providing clear images of the cytoskeleton, give only a static picture of this dynamic structure. Microinjection of fluorescently Is beled cytoskeletal proteins has proved useful as a way to follow some cytoskeletal events, but long terry studies are generally limited by the bleaching of fluorophores and presence of unassembled monomers.Polarization microscopy has the potential for visualizing the cytoskeleton. Although at present, it ha mainly been used for visualizing the mitotic spindle. Polarization microscopy is attractive in that it pro vides a way to selectively image structures such as cytoskeletal filaments that are birefringent. By combing ing standard polarization microscopy with video enhancement techniques it has been possible to image single filaments. In this case, however, filament intensity depends on the orientation of the polarizer and analyzer with respect to the specimen.

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Passy-Muir Speaking Valve Use in a Children's Hospital: An Interdisciplinary Approach

Perspectives on Voice and Voice Disorders ◽

10.1044/vvd18.2.76 ◽

2008 ◽

Vol 18 (2) ◽

pp. 76-86 ◽

Cited By ~ 2

Author(s):

Lauren Hofmann ◽

Joseph Bolton ◽

Susan Ferry

Keyword(s):

Tracheostomy Tube ◽

Pediatric Population ◽

Interdisciplinary Approach ◽

Extended Period ◽

Speech Development ◽

Tube Placement ◽

Background Information ◽

Speaking Valve ◽

Children's Hospital ◽

Children’S Hospital

Abstract At The Children's Hospital of Philadelphia (CHOP) we treat many children requiring tracheostomy tube placement. With potential for a tracheostomy tube to be in place for an extended period of time, these children may be at risk for long-term disruption to normal speech development. As such, speaking valves that restore more normal phonation are often key tools in the effort to restore speech and promote more typical language development in this population. However, successful use of speaking valves is frequently more challenging with infant and pediatric patients than with adult patients. The purpose of this article is to review background information related to speaking valves, the indications for one-way valve use, criteria for candidacy, and the benefits of using speaking valves in the pediatric population. This review will emphasize the importance of interdisciplinary collaboration from the perspectives of speech-language pathology and respiratory therapy. Along with the background information, we will present current practices and a case study to illustrate a safe and systematic approach to speaking valve implementation based upon our experiences.

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Prophylactic Mastectomy - Evaluation and Treatment of High Risk Patients

Swiss Surgery ◽

10.1024/1023-9332.8.2.45 ◽

2002 ◽

Vol 8 (2) ◽

pp. 45-52 ◽

Cited By ~ 3

Author(s):

Remmel ◽

Harder

Keyword(s):

Breast Cancer ◽

Breast Cancer Risk ◽

Cancer Risk ◽

Risk Reduction ◽

Prophylactic Mastectomy ◽

Interdisciplinary Approach ◽

Reconstructive Procedures ◽

Medline Search ◽

Breast Cancer Risk Reduction ◽

Cancer Risk Reduction

Prophylactic mastectomy is an aggressive strategy for breast cancer risk reduction. The indications and efficiency of this procedures are not yet clearly defined. Randomized, prospective studies, comparing different surgical procedures with other modalities of breast cancer risk reduction are lacking. The report evaluates the existing controversy, based on Medline search in the following sequence: risk factors, possibilities of risk reduction, effectiveness of risk reduction, technical considerations and recommendations. Patient selection is difficult and needs an interdisciplinary approach. The women have to be well informed about all treatment alternatives and various reconstructive procedures. An appropriate risk reduction strategy should be selected individually for each patient. Up to now, there exist only recommendations from different institutions but no definitive guidelines.

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