Neurotrophic and X-ray blocks in the blastemal cell cycle

Development ◽  
1979 ◽  
Vol 50 (1) ◽  
pp. 169-173
Author(s):  
M. Maden
Keyword(s):  
Cell Cycle ◽  
Recent Theory ◽  
Neurotrophic Control ◽  
X Ray ◽  
Blastemal Cell ◽  
X Irradiation

Using microdensitometry techniques the points in the cycle where blastemal cells become blocked after X-irradiation or denervation of the regenerating amphibian limb have been identified. X-irradiation blocks the cells in both G1 and G2 and those cells that were in S at the time of irradiation presumably proceed to G1. After denervation, however, cells accumulate only in G1 and those that were in S or G1 continue through the cycle to the next G1. The latter results are clearly contradictory to a recent theory proposing a G1 neurotrophic control of blastemal cells and a solution to the contradiction is presented in the light of recent results.

Eds Of Radioactive Particles By Self-Induced Fluorescence

1990 ◽  
Vol 48 (2) ◽  
pp. 238-239
Author(s):  
Gregory L. Finch ◽  
Richard G. Cuddihy
Keyword(s):  
Electron Beam Irradiation ◽  
Nuclear Reactor ◽  
X Rays ◽  
Reactor Accident ◽  
Internal Radiation ◽  
X Ray ◽  
External Sources ◽  
X Irradiation ◽  
Available Information ◽  
Individual Particles

The elemental composition of individual particles is commonly measured by using energydispersive spectroscopic microanalysis (EDS) of samples excited with electron beam irradiation. Similarly, several investigators have characterized particles by using external monochromatic X-irradiation rather than electrons. However, there is little available information describing measurements of particulate characteristic X rays produced not from external sources of radiation, but rather from internal radiation contained within the particle itself. Here, we describe the low-energy (< 20 KeV) characteristic X-ray spectra produced by internal radiation self-excitation of two general types of particulate samples; individual radioactive particles produced during the Chernobyl nuclear reactor accident and radioactive fused aluminosilicate particles (FAP). In addition, we compare these spectra with those generated by conventional EDS.Approximately thirty radioactive particle samples from the Chernobyl accident were on a sample of wood that was near the reactor when the accident occurred. Individual particles still on the wood were microdissected from the bulk matrix after bulk autoradiography.

A Small-Angle X-Ray Scattering Study on Pre-Irradiated Malate Synthase. The Influence of Formate, Superoxide Dismutase, and Catalase on the X-Ray Induced Aggregation of the Enzyme

1985 ◽  
Vol 40 (5-6) ◽  
pp. 364-372 ◽  
Author(s):  
P. Zipper ◽  
R. Wilfing ◽  
M. Kriechbaum ◽  
H. Durchschlag
Keyword(s):  
Aqueous Solution ◽  
Superoxide Dismutase ◽  
Small Angle ◽  
Malate Synthase ◽  
X Ray ◽  
X Ray Scattering ◽  
X Irradiation ◽  
The Mean ◽  
Induced Aggregation ◽  
Ray Scattering

Abstract The sulfhydryl enzyme malate synthase from baker’s yeast was X-irradiated with 6 kGy in air-saturated aqueous solution (enzyme concentration: ≃ 10 mg/ml; volume: 120 μl), in the absence or presence of the specific scavengers formate, superoxide dismutase, and catalase. After X-irradiation, a small aliquot of the irradiated solutions was tested for enzymic activity while the main portion was investigated by means of small-angle X-ray scattering. Additionally, an unir­radiated sample without additives was investigated as a reference. Experiments yielded the fol­lowing results: 1. X-irradiation in the absence of the mentioned scavengers caused considerable aggregation, fragmentation, and inactivation of the enzyme. The dose Dt37 for total (= repairable + non­-repayable) inactivation resulted as 4.4 kGy. The mean radius of gyration was found to be about 13 nm. The mean degree of aggregation was obtained as 5.7, without correction for fragmenta­tion. An estimation based on the thickness factor revealed that about 19% of material might be strongly fragmented. When this amount of fragments was accordingly taken into account, a value of 7.1 was obtained as an upper limit for the mean degree of aggregation. The observed retention of the thickness factor and the finding of two different cross-section factors are in full accord with the two-dimensional aggregation model established previously (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99 - 121 (1980)). 2. The presence of catalytic amounts of superoxide dismutase and/or catalase, in the absence of formate, during X-irradiation reduced both aggregation and inactivation significantly. 3. The presence of formate (10 or 100 mᴍ) during X-irradiation led to a strong decrease of aggregation and inactivation. This effect was more pronounced with the higher formate concen­tration or when superoxide dismutase and/or catalase were simultaneously present during X-irradiation. The presence of formate also reduced the amount of fragments significantly. 4. The results clearly show that the aggregation and inactivation of malate synthase upon X-irradiation in aqueous solution are mainly caused by OH·; to a minor extent O·̄2 and H2O2 are additionally involved in the damaging processes.

scholarly journals The p21WAF1/CIP1 Promoter Is Methylated in Rat-1 Cells: Stable Restoration of p53-Dependent p21WAF1/CIP1 Expression after Transfection of a Genomic Clone Containing the p21WAF1/CIP1 Gene

2000 ◽  
Vol 20 (4) ◽  
pp. 1291-1298 ◽  
Author(s):  
Lindsey A. Allan ◽  
Trevor Duhig ◽  
Moira Read ◽  
Mike Fried
Keyword(s):  
Cell Cycle ◽  
Promoter Region ◽  
P53 Protein ◽  
Artificial Chromosome ◽  
Uv Treatment ◽  
X Ray ◽  
Cpg Dinucleotides ◽  
A Cell ◽  
Cell Cycle Block ◽  
Inducible Gene

ABSTRACT Rat-1 cells are used in many studies on transformation, cell cycle, and apoptosis. Whereas UV treatment of Rat-1 cells results in apoptosis, X-ray treatment does not induce either apoptosis or a cell cycle block. X-ray treatment of Rat-1 cells results in both an increase of p53 protein and expression of the p53-inducible geneMDM2 but not the protein or mRNA of the p53-inducible p21WAF1/CIP1 gene, which in other cells plays an important role in p53-mediated cell cycle block. The lack of p21WAF1/CIP1 expression appears to be the result of hypermethylation of the p21WAF1/CIP1 promoter region, as p21WAF1/CIP1 protein expression could be induced by growth of Rat-1 cells in the presence of 5-aza-2-deoxycytidine. Furthermore, sequence analysis of bisulfite-treated DNA demonstrated extensive methylation of cytosine residues in CpG dinucleotides in a CpG-rich island in the promoter region of the p21WAF1/CIP1 gene. Stable X-ray-induced p53-dependent p21WAF1/CIP1 expression and cell cycle block were restored to a Rat-1 clone after transfection with a P1 artificial chromosome (PAC) DNA clone containing a rat genomic copy of the p21WAF1/CIP1 gene. The absence of expression of the p21WAF1/CIP1 gene may contribute to the suitability of Rat-1 cells for transformation, cell cycle, and apoptosis studies.

N-(3'-acetyl-8-nitro-2,3-dihydro-1H,3'H-spiro[quinoline-4,2'-[1,3,4]thiadiazol]-5'-yl) acetamides Induced Cell death in MCF-7 cells via G2/M Phase Cell Cycle Arrest

2022 ◽  
Author(s):  
Selvaraj Shyamsivappan ◽  
Raju Vivek ◽  
Thangaraj Suresh ◽  
Palanivel Naveen ◽  
Kaviyarasu Adhigaman ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cell Cycle Arrest ◽  
Spectroscopic Studies ◽  
Phase Cell ◽  
X Ray ◽  
Cycle Arrest ◽  
M Phase ◽  
Mcf 7

A progression of new N-(3'-acetyl-8-nitro-2,3-dihydro-1H,3'H-spiro[quinoline-4,2'-[1,3,4]thiadiazol]-5'-yl) acetamide derivatives were synthesized from potent 8-nitro quinoline-thiosemicarbazones. The synthesized compounds were characterized by different spectroscopic studies and single X-ray crystallographic studies. The compounds were...

Physiological effects of extremely high X-ray intensities and dosages on mice

1960 ◽  
Vol 199 (6) ◽  
pp. 1101-1104 ◽  
Author(s):  
W. S. Moos ◽  
H. C. Mason ◽  
M. Counelis
Keyword(s):  
Serum Potassium ◽  
High Intensity ◽  
Considerable Increase ◽  
Physiological Effects ◽  
Brain Hemorrhage ◽  
X Ray ◽  
X Irradiation ◽  
Leukocyte Counts ◽  
Electrocardiographic Recordings ◽  
Abdominal Irradiation

The physiological effects of high-intensity x-irradiation (2 x 105 r/min.) and dosages of 1 x 106 r on mice (head and abdomen) were investigated. An increase in pulmonary and heart rates were observed. Electrocardiographic recordings after irradiation demonstrated reversal of wave components and increase of amplitudes. Blood counts present no changes except for a drop in leukocyte counts. Hemoglobin remained unchanged. A considerable increase in serum potassium was noted and some indications of methemoglobin production. Head-irradiated animals yielded a higher incidence of auricular congestion and brain hemorrhage in contrast to animals receiving abdominal irradiation.

scholarly journals Nuclear incorporation of iron during the eukaryotic cell cycle

2016 ◽  
Vol 23 (6) ◽  
pp. 1490-1497 ◽  
Author(s):  
Ian Robinson ◽  
Yang Yang ◽  
Fucai Zhang ◽  
Christophe Lynch ◽  
Mohammed Yusuf ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Fluorescence Microscopy ◽  
Phase Contrast ◽  
Eukaryotic Cell ◽  
Inhomogeneous Distribution ◽  
Cell Nuclei ◽  
X Ray ◽  
Microscopy Images ◽  
Different Levels

Scanning X-ray fluorescence microscopy has been used to probe the distribution of S, P and Fe within cell nuclei. Nuclei, which may have originated at different phases of the cell cycle, are found to show very different levels of Fe present with a strongly inhomogeneous distribution. P and S signals, presumably from DNA and associated nucleosomes, are high and relatively uniform across all the nuclei; these agree with X-ray phase contrast projection microscopy images of the same samples. Possible reasons for the Fe incorporation are discussed.

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