Reproducible dissociation of cellular aggregates with a wide range of calibrated shear forces: Application to cytolytic lymphocyte-target cell conjugates

1983 ◽  
Vol 58 (1-2) ◽  
pp. 209-224 ◽  
Author(s):  
Pierre Bongrand ◽  
Pierre Golstein
Keyword(s):  
Target Cell ◽  
Shear Forces ◽  
Wide Range ◽  
Cellular Aggregates

scholarly journals Specificity of HLA class I antigen recognition by human NK clones: evidence for clonal heterogeneity, protection by self and non-self alleles, and influence of the target cell type.

1993 ◽  
Vol 178 (4) ◽  
pp. 1321-1336 ◽  
Author(s):  
V Litwin ◽  
J Gumperz ◽  
P Parham ◽  
J H Phillips ◽  
L L Lanier
Keyword(s):  
Nk Cells ◽  
Mhc Class I ◽  
Target Cell ◽  
Nk Cell ◽  
Hla Class I ◽  
Class I ◽  
Target Cells ◽  
Clonal Heterogeneity ◽  
Multiple Alleles ◽  
Wide Range

Prior studies using polyclonal populations of natural killer (NK) cells have revealed that expression of certain major histocompatibility complex (MHC) class I molecules on the membrane of normal and transformed hematopoietic target cells can prevent NK cell-mediated cytotoxicity. However, the extent of clonal heterogeneity within the NK cell population and the effect of self versus non-self MHC alleles has not been clearly established. In the present study, we have generated more than 200 independently derived human NK cell clones from four individuals of known human histocompatibility leukocyte antigens (HLA) type. NK clones were analyzed for cytolytic activity against MHC class I-deficient Epstein Barr virus (EBV) transformed B lymphoblastoid cell lines (B-LCL) stably transfected with several HLA-A, -B, or -C genes representing either self or non-self alleles. All NK clones killed the prototypic HLA-negative erythroleukemia K562 and most lysed the MHC class I-deficient C1R and 721.221 B-LCL. Analysis of the panel of HLA-A, -B, and -C transfectants supported the following general conclusions. (a) Whereas recent studies have suggested that HLA-C antigens may be preferentially recognized by NK cells, our findings indicate that 70% or more of all NK clones are able to recognize certain HLA-B alleles and many also recognize HLA-A alleles. Moreover, a single NK clone has the potential to recognize multiple alleles of HLA-A, HLA-B, and HLA-C antigens. Thus, HLA-C is not unique in conferring protection against NK lysis. (b) No simple patterns of HLA specificity emerged. Examination of a large number of NK clones from a single donor revealed overlapping, yet distinct, patterns of reactivity when a sufficiently broad panel of HLA transfectants was examined. (c) Both autologous and allogeneic HLA antigens were recognized by NK clones. There was neither evidence for deletion of NK clones reactive with self alleles nor any indication for an increased frequency of NK clones recognizing self alleles. (d) With only a few exceptions, protection conferred by transfection of HLA alleles into B-LCL was usually not absolute. Rather a continuum from essentially no protection for certain alleles (HLA-A*0201) to very striking protection for other alleles (HLA-B*5801), with a wide range of intermediate effects, was observed. (e) Whereas most NK clones retained a relatively stable HLA specificity, some NK clones demonstrated variable and heterogeneous activity over time. (f) NK cell recognition and specificity cannot be explained entirely by the presence or absence of HLA class I antigens on the target cell.(ABSTRACT TRUNCATED AT 400 WORDS)

The Deflexion of a Thick Plain Ring under a Uniformly Distributed Couple

1946 ◽  
Vol 155 (1) ◽  
pp. 101-115
Author(s):  
A. E. Johnson
Keyword(s):  
Load Distribution ◽  
Point Of View ◽  
Shear Forces ◽  
Theoretical Methods ◽  
Mathematical Point ◽  
Axial Shear ◽  
Wide Range

Several theoretical methods of estimating the deflexion of a thick plain ring under a uniformly distributed couple have been published, both in this country and in the U.S.A. Probably the best-known of these theories is that of Dr. R. W. Bailey.† In all cases the treatment has not been rigid from a mathematical point of view, the axial or shear forces in the ring notably being neglected, and the load being assumed concentrated on particular loading circles whereas in fact it is distributed over an appreciable area. The present paper attempts to treat the problem in a more rigid manner, with due consideration of the effect of load distribution. Expressions for the axial and radial deflexions, and the axial, shear, radial, and circumferential stresses in the ring are developed, and values of these functions are obtained for a wide range of ring dimensions, and are compared with the values of similar quantities obtained by the use of the theory of Dr. R. W. Bailey.

scholarly journals Effect of foundation compliance on earthquake stresses in multistory buildings*

1954 ◽  
Vol 44 (4) ◽  
pp. 551-569
Author(s):  
R. G. Merritt ◽  
G. W. Housner
Keyword(s):  
Tall Buildings ◽  
Strong Motion ◽  
Analog Computer ◽  
Fundamental Period ◽  
Base Shear ◽  
Shear Forces ◽  
Multistory Buildings ◽  
Building Models ◽  
Wide Range ◽  
Building Practice

Abstract This paper shows the quantitative effect that foundation compliance has on the maximum base shear force and the fundamental period of vibration in typical tall buildings subjected to strong-motion earthquakes. A study was made of five-, ten-, and fifteen-story building models on the Electric Analog Computer, subjecting them to the ground accelerations of actual earthquakes. The base shear forces were measured, the foundation compliance of the models being changed through a very wide range. The properties specified for the building models are shown to be similar to the properties found in real buildings. The experimental results imply that the maximum base shear forces in typical buildings of five stories and higher during strong-motion earthquakes will be essentially unaffected by any degree of foundation compliance that can be expected in normal building practice. The fundamental period of typical buildings will be increased by about 10 per cent if the foundation compliance is the maximum that can be expected in standard building practice.

scholarly journals Investigating expression of a human optimized cas9 transgene in Neurospora crassa

2020 ◽  
Author(s):  
Natalie Burrell ◽  
Nicholas A. Rhoades ◽  
Amy Boyd ◽  
Jim Mierendorf ◽  
Aykhan Yusifov ◽  
...  
Keyword(s):  
Molecular Biology ◽  
Heterologous Expression ◽  
Neurospora Crassa ◽  
Streptococcus Pyogenes ◽  
Target Cell ◽  
Filamentous Fungus ◽  
Transgene Expression ◽  
Synonymous Codon ◽  
Wide Range ◽  
Primary Obstacle

ABSTRACTThe CRISPR-associated Cas9 enzyme is used in molecular biology to engineer the genomes of a wide range of organisms. While Cas9 can be injected or transfected into a target cell to achieve the desired goal, there are situations where stable expression of Cas9 within a target organism is preferable. Here, we show that the model filamentous fungus Neurospora crassa is recalcitrant to heterologous expression of a human-optimized version of Streptococcus pyogenes cas9. Furthermore, partial optimization of cas9 by synonymous codon exchange failed to improve its expression in the fungus. Finally, we show that transgene expression can be detected when cas9Hs sequences are placed in the 3’ UTR regions of transgene-derived mRNAs, but not when the same sequences are in the translated part of the transgene-derived mRNA. This finding suggests that the primary obstacle to high cas9Hs expression levels in N. crassa is translational in nature.

scholarly journals Towards organoid culture without Matrigel

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mark T. Kozlowski ◽  
Christiana J. Crook ◽  
Hsun Teresa Ku
Keyword(s):  
Developmental Biology ◽  
Genetic Disorders ◽  
Organ Function ◽  
Organoid Culture ◽  
Decellularized Extracellular Matrix ◽  
Wide Range ◽  
Mouse Sarcoma ◽  
Specific Factors ◽  
Sarcoma Cells ◽  
Cellular Aggregates

AbstractOrganoids—cellular aggregates derived from stem or progenitor cells that recapitulate organ function in miniature—are of growing interest in developmental biology and medicine. Organoids have been developed for organs and tissues such as the liver, gut, brain, and pancreas; they are used as organ surrogates to study a wide range of questions in basic and developmental biology, genetic disorders, and therapies. However, many organoids reported to date have been cultured in Matrigel, which is prepared from the secretion of Engelbreth-Holm-Swarm mouse sarcoma cells; Matrigel is complex and poorly defined. This complexity makes it difficult to elucidate Matrigel-specific factors governing organoid development. In this review, we discuss promising Matrigel-free methods for the generation and maintenance of organoids that use decellularized extracellular matrix (ECM), synthetic hydrogels, or gel-forming recombinant proteins.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Observation of Atom Rows in Thorium Pyromellitate Using a Field Emission STEM

1977 ◽  
Vol 35 ◽  
pp. 80-81
Author(s):  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Field Emission ◽  
Amorphous Carbon ◽  
Carbon Film ◽  
Dark Field Image ◽  
Dark Field ◽  
Amorphous Carbon Film ◽  
Atomic Size ◽  
Wide Range ◽  
A Chain

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3 CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.

Development of a conical anode Fe-gun for low voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 978-979
Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Irradiation Damage ◽  
Cold Cathode ◽  
Virtual Source ◽  
Source Position ◽  
Electrostatic Lens ◽  
Electrostatic Lenses ◽  
Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

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