Novel Pure αVβ3 Integrin Antagonists That Do Not Induce Receptor Extension, Prime the Receptor, or Enhance Angiogenesis at Low Concentrations

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

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The CM120 Biotwin: a high-contrast objective lens, optimum cryo-vacuum and improved EDX performance

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100139299 ◽

1995 ◽

Vol 53 ◽

pp. 584-585

Author(s):

Uwe Lücken ◽

Michael Felsmann ◽

Wim M. Busing ◽

Frank de Jong

Keyword(s):

Life Science ◽

Focal Length ◽

Objective Lens ◽

High Contrast ◽

Contrast Imaging ◽

X Ray ◽

Forming Mechanism ◽

Similar Image ◽

High Contrast Imaging ◽

Low Concentrations

A new microscope for the study of life science specimen has been developed. Special attention has been given to the problems of unstained samples, cryo-specimens and x-ray analysis at low concentrations.A new objective lens with a Cs of 6.2 mm and a focal length of 5.9 mm for high-contrast imaging has been developed. The contrast of a TWIN lens (f = 2.8 mm, Cs = 2 mm) and the BioTWTN are compared at the level of mean and SD of slow scan CCD images. Figure 1a shows 500 +/- 150 and Fig. 1b only 500 +/- 40 counts/pixel. The contrast-forming mechanism for amplitude contrast is dependent on the wavelength, the objective aperture and the focal length. For similar image conditions (same voltage, same objective aperture) the BioTWIN shows more than double the contrast of the TWIN lens. For phasecontrast specimens (like thin frozen-hydrated films) the contrast at Scherzer focus is approximately proportional to the √ Cs.

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Immunogold labeling of CMP-KDO synthetase produced by recombinant E. Coli cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100128900 ◽

1987 ◽

Vol 45 ◽

pp. 924-925

Author(s):

F. A. Durum ◽

R. G. Goldman ◽

T. J. Bolling ◽

M. F. Miller

Keyword(s):

Inclusion Bodies ◽

Large Scale ◽

Recombinant Dna ◽

Test System ◽

Cell Protein ◽

Gram Negative Bacteria ◽

Cytoplasmic Inclusions ◽

Isolation And Purification ◽

E Coli ◽

Low Concentrations

CMP-KDO synthetase (CKS) is an enzyme which plays a key role in the synthesis of LPS, an outer membrane component unique to gram negative bacteria. CKS activates KDO to CMP-KDO for incorporation into LPS. The enzyme is normally present in low concentrations (0.02% of total cell protein) which makes it difficult to perform large scale isolation and purification. Recently, the gene for CKS from E. coli was cloned and various recombinant DNA constructs overproducing CKS several thousandfold (unpublished data) were derived. Interestingly, no cytoplasmic inclusions of overproduced CKS were observed by EM (Fig. 1) which is in contrast to other reports of large proteinaceous inclusion bodies in various overproducing recombinant strains. The present immunocytochemical study was undertaken to localize CKS in these cells.Immune labeling conditions were first optimized using a previously described cell-free test system. Briefly, this involves soaking small blocks of polymerized bovine serum albumin in purified CKS antigen and subjecting them to various fixation, embedding and immunochemical conditions.

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Phase behavior of cationic and anionic surfactants at low concentrations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123878 ◽

1992 ◽

Vol 50 (1) ◽

pp. 694-695

Author(s):

E. Naranjo

Keyword(s):

Phase Behavior ◽

Structural Characterization ◽

Dynamic Systems ◽

Anionic Surfactants ◽

Intermolecular Forces ◽

Stable Form ◽

Surfactant Mixtures ◽

Low Concentrations ◽

Cationic And Anionic Surfactants ◽

General Method

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.

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Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

Nuklearmedizin ◽

10.1055/s-0037-1620623 ◽

1977 ◽

Vol 16 (04) ◽

pp. 157-162 ◽

Cited By ~ 1

Author(s):

C. Schümichen ◽

B. Mackenbrock ◽

G. Hoffmann

Keyword(s):

Normal Saline ◽

Half Life ◽

Compound A ◽

Short Half Life ◽

Low Concentrations ◽

The Stability ◽

Kinetics Of ◽

In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

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