Controlled slow release of chemotherapeutic drugs for cancer from matrices prepared by radiation polymerization at low temperatures

1980 ◽  
Vol 14 (3) ◽  
pp. 185-197 ◽  
Author(s):  
Isao Kaetsu ◽  
Masaru Yoshida ◽  
Akio Yamada
Keyword(s):  
Low Temperatures ◽  
Slow Release ◽  
Chemotherapeutic Drugs ◽  
Radiation Polymerization

Effect of the hydrophilicity of the polymer matrix on immobilized α-chymotrypsin

1984 ◽  
Vol 49 (6) ◽  
pp. 1552-1556
Author(s):  
Minoru Kumakura ◽  
Isso Kaetsu
Keyword(s):  
Thermal Stability ◽  
Enzyme Activity ◽  
Pore Size ◽  
Polymer Matrix ◽  
Low Temperatures ◽  
Radiation Polymerization ◽  
Thermal Stability Of

α-Chymotrypsin was immobilized by radiation polymerization at low temperatures and the effect of the hydrophilicity of the polymer matrix on the enzyme activity and thermal stability was studied. The activity and thermal stability of immobilized chymotrypsin increased with the increasing hydrophilicity of the polymer matrix or monomer. The thermal stability was affected by the form and pore size of the polymer matrix; chymotrypsin immobilized on a soft-gel polymer matrix exhibited an enhanced thermal stability.

Radiation polymerization of 2-hydroxyethyl methacrylate-vinyl pyrrolidone-water system

1988 ◽  
Vol 53 (6) ◽  
pp. 1242-1246
Author(s):  
Minoru Kumakura ◽  
Isao Kaetsu
Keyword(s):  
Glass Transition ◽  
Low Temperatures ◽  
Water System ◽  
Monomer Concentration ◽  
Temperature Curve ◽  
Irradiation Temperature ◽  
Polymerization Rate ◽  
Vinyl Pyrrolidone ◽  
Hydroxyethyl Methacrylate ◽  
Radiation Polymerization

Radiation polymerization of 2-hydroxyethyl methacrylate-vinyl pyrrolidone-water system at low temperature was studied. The polymerization rate-irradiation temperature curve had a maximum peak at near glass transition temperaure, and it was shifted to the site of high temperature with increasing monomer concentration. The polymerization rate in vinyl pyrrolidone at low temperatures was accelerated by the addition of water. The polymers obtained by radiation polymerization of 2-hydroxyethyl methacrylate-vinyl pyrrolidone-water system at low temperatures were a high hydrophilicity and had porous structure.

Immobilization of E. coli Cell as an Antigen by Radiation Polymerization Method

1983 ◽  
Vol 38 (9-10) ◽  
pp. 812-814 ◽  
Author(s):  
lsao Kaetsu ◽  
Minoru Kumakura ◽  
Shintaro Kikuchi ◽  
Shoichi Adachi ◽  
Mieko Suzuki
Keyword(s):  
Low Temperatures ◽  
Cross Reactivity ◽  
Coli Cell ◽  
Gram Negative Bacteria ◽  
Hydroxyethyl Methacrylate ◽  
Gram Negative ◽  
E Coli ◽  
Radiation Polymerization ◽  
Specific Affinity ◽  
Polymerization Method

E. coli NIJ cells were immobilized by radiation polymerization of 2-hydroxyethyl methacrylate at low temperatures. The immobilized E. coli cells as an antigen were reacted with peroxidase labeled anti-E. coli in competition with the free E. coli cells. It was found that E. coli cells can be assayed quantitatively with the immobilized E. coli cells in disc form. Microorganisms such as gram negative bacteria had no specific affinity to anti-E. coli. Cross reactivity of the immobilized E. coli cells with the E. coli cells from various strains was examined.

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Radiation Damage of Support Films

1981 ◽  
Vol 39 ◽  
pp. 28-29
Author(s):  
H.A. Cohen ◽  
W. Chiu
Keyword(s):  
Transfer Function ◽  
Low Temperatures ◽  
Carbon Support ◽  
Contrast Transfer Function ◽  
Electron Dose ◽  
Imaging Parameters ◽  
Negative Stain ◽  
Phase Corrections ◽  
Two Parameters ◽  
Medium Dose

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

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