scholarly journals Studies on the Growth of Tissues in vitro

1936 ◽  
Vol 13 (2) ◽  
pp. 237-248
Author(s):  
E. N. WILLMER ◽  
F. JACOBY
Keyword(s):  
Cell Division ◽  
Latent Period ◽  
Tyrode Solution ◽  
Cell Degeneration ◽  
Fluid Medium ◽  
Embryo Extract ◽  
Low Concentrations ◽  
Growth Promoting ◽  
Migration Of Cells

1. A method is described for testing the growth-promoting properties of various substances on tissues in vitro. 2. When growth of cells (chick fibroblasts) has ceased in a medium of plasma and Tyrode solution, it may be restarted again by the addition of embryo extract. 3. There is a latent period of from 2 to 3 hours before a greatly increased migration of cells occurs. 4. There is a latent period of from 10 to 12 hours before cell division starts again. After that time the percentage of cells dividing increases for the next 12 hours and then declines. 5. For low concentrations of extract the growth is proportional to the concentration. 6. Cell division of neither heart fibroblasts nor of periosteal fibroblasts is inhibited by concentrations of extract higher than 15 per cent in Tyrode solution, but cultures of periosteal fibroblasts in such concentrations cause a "liquefaction" of the plasma medium. With heart fibroblasts, "liquefaction" of the medium does not readily occur, within the duration of these experiments, until the concentration of extract reaches 60 per cent. 7. The growth of two cultures in embryo extract, and embryo extract and serum respectively, has been followed for 10 consecutive days. The rate of cell division in the medium containing serum was less rapid. Cell degeneration commenced in both cultures after about 6 days, so that after about 8 or 10 days there was no further increase in the number of cells on the field. The addition of fresh fluid medium to the cultures was clearly reflected in corresponding increases in the values of the mitotic indices.

scholarly journals Studies on the Growth of Tissues In Vitro

1937 ◽  
Vol 14 (3) ◽  
pp. 255-266
Author(s):  
F. JACOBY ◽  
O. A. TROWELL ◽  
E. N. WILLMER
Keyword(s):  
Cell Division ◽  
Latent Period ◽  
Effective Dose ◽  
Appreciable Amount ◽  
Minimum Effective Dose ◽  
Tyrode Solution ◽  
Daughter Cells ◽  
Duration Of Mitosis ◽  
Division Process

1. Embryo juice initiates in cells growing in plasma alone a process which after a latent period of some 10-12 hours culminates in cell division, and it is not necessary for the embryo juice to be present in any appreciable amount during the actual division process. 2. The approximate minimum effective dose is 5 per cent embryo juice in Tyrode solution acting for 3 hours. 15 and 40 per cent juice produce marked effects when applied for only 1 hour. 3. The concentration of embryo juice is a more important factor in determining the number of mitoses produced than is the time for which it acts. 4. Unless the embryo juice remain in contact with the culture for more than 10 hours, only one crop of mitoses occurs; but if it is present in the medium during or after the occurrence of the first divisions, then a second crop of divisions takes place. Evidence is adduced that it is the daughter cells produced during the first crop of mitoses which divide to produce the second crop. 5. The duration of mitosis is correlated with the concentration of the embryo juice. It approaches a minimum of about 40 min. 6. The duration of mitosis, particularly that of the ana- and telophases, is correlated with the rate of migration of the cells. 7. When a second crop of mitoses occurs in these cultures which have passed through a period in plasma alone, there is evidence that the size of the cells in metaphase of mitosis is significantly less than that of the cells of the first crop.

Low concentrations of caffeine induce asymmetric cell division as observed in vitro by means of the CBMN-assay and iFISH

2015 ◽  
Vol 793 ◽  
pp. 71-78 ◽  
Author(s):  
Vasiliki I. Hatzi ◽  
Maria Karakosta ◽  
Katarzyna Barszczewska ◽  
Ioanna Karachristou ◽  
Gabriel Pantelias ◽  
...  
Keyword(s):  
Cell Division ◽  
Asymmetric Cell Division ◽  
Low Concentrations ◽  
Cbmn Assay

scholarly journals MATURATION OF HEMOLYSIN-PRODUCING CELL CLONES

1969 ◽  
Vol 130 (3) ◽  
pp. 543-556 ◽  
Author(s):  
George C. Saunders
Keyword(s):  
Cell Division ◽  
Latent Period ◽  
Induction Period ◽  
Generation Time ◽  
Sheep Erythrocyte ◽  
Precursor Cells ◽  
Cell Clones ◽  
Synchronous Cell ◽  
Erythrocyte Antigen

Investigations of the induction period of an in vitro hemolysin response to sheep erythrocyte antigen revealed the following: 1. After antigen stimulation precursors of plaque-forming cells rapidly maturate to the point of hemolysin production. 2. Initial maturation probably occurs in the absence of cell division. 3. After initial maturation, a latent period of about 12 hr occurs before the first doubling of PFC. 4. At least the first three cell doublings are synchronous, with a generation time of 7–8 hr. 5. Synchronous cell division implies that all precursor cells are at the same point in the cell cyde when they are initially stimulated.

THE IMPORTANCE OF INSULIN, CORTISOL, PROGESTERONE AND PROLACTIN FOR THE MAMMOTROPHIC EFFECT OF PREGNANT RAT SERUM

1977 ◽  
Vol 85 (3) ◽  
pp. 548-558
Author(s):  
J. M. Peters
Keyword(s):  
Culture Medium ◽  
Indirect Evidence ◽  
High Concentration ◽  
Promoting Effect ◽  
Rat Serum ◽  
Pregnant Rat ◽  
Low Concentrations ◽  
Prolactin Content ◽  
Growth Promoting

ABSTRACT In order to explain the increased mammotrophic activity of pregnant rat serum, some hormones known to have an in vitro effect on the mammary gland were added to non-pregnant rat serum and their effect compared with that of pregnant rat serum. The addition of insulin to the culture medium increased the mammotrophic effect of pregnant rat serum, but a difference between non-pregnant and pregnant rat serum could be demonstrated either in the presence or absence of a high concentration of insulin. While pregnant rat serum had a mammogenic (i. e. growth-promoting) effect, cortisol had no such effect and antagonized the mitotic activity induced by the pregnant serum. Pregnant rat serum was active at such low concentrations, that the progesterone content of pregnant rat serum could not explain the mammogenic activity of the latter. Moreover, the combination of progesterone with non-pregnant rat serum did not produce other changes produced by pregnant rat serum alone such as cytoplasmic opalescence and the localized development of vacuolization and secretion. Prolactin with non-pregnant rat serum produced a mammotrophic effect which was in all respects similar to that of pregnant rat serum. An effect could be demonstrated at 0.08 μg prolactin/ml medium. However, again pregnant rat serum was active at such low concentrations that the prolactin content of pregnant rat serum could not explain the mammotrophic effect of pregnant rat serum. Moreover, the effect of pregnant rat serum could not be blocked with rabbit anti-rat prolactin serum, but the anti-serum blocked the effect of rat prolactin added to non-pregnant rat serum. The results exclude the possibility that insulin, cortisol, progesterone or prolactin can account for the mammotrophic activity in pregnant rat serum. They provide indirect evidence for the importance of rat chorionic mammotrophin.

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

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
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.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

Aggregation of Cat Platelets in Vitro

1970 ◽  
Vol 23 (03) ◽  
pp. 601-620 ◽  
Author(s):  
Th. B Tschopp
Keyword(s):  
Adenosine Monophosphate ◽  
Blood Collection ◽  
Base Line ◽  
Reversible Aggregation ◽  
Low Concentrations ◽  
Irreversible Aggregation ◽  
High Concentrations ◽  
Two Phases ◽  
Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

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