Proliferation phase

The authors obtained an RNA ligase ribozyme using the method of in vitro evolution . Here, macromolecules are allowed to go through a series of synthetic cycles, which are followed by a proliferation phase, mutation and selection. As in Darwinian evolution, the goal is to carry out laboratory selection of molecules with certain required properties. 

Figure 10.4 Stages in the differentiation of haemopoietic stem cells, yielding mature erythrocytes. The EPO-sensitive cells are indicated. Each cell undergoes proliferation as well as differentiation thus, greater numbers of the more highly differentiated daughter cells are produced. The proliferation phase ends at the reticulocyte stage each reticulocyte matures over a 2-day period, yielding a single mature erythrocyte...

The index declines to about 40% concomitantly with the developmental transition from the embryonic to fetal stage [27,247]. In newborn rats this index is about 2% [80] and becomes. 5% and. 06% by 1 and 3-4 months after birth, respectively [246,247]. In the pulmonary artery, however, it is about 30% from day 19 in utero up to day 7 after birth [29]. Though it seems that during development proliferation and differentiation are mutually exclusive, recent data from Lee et al. [228] point to different picture. In aortic media from day 2.5-19 chick embryo, the kinetics of replication is temporally distributed in two waves a rapid (15-17% from days 4-12) and a slow (lessthan 5% from day 16 to hatching) proliferation phase. Interestingly, es5)ression of the precocious muscle lineage marker SM a-actin occurs independetly from the level of proliferation [228]. 

Uterine cervical secret was examined by the Brdidka filtrate reaction in the course of the menstrual cycle it exhibits regular fluctuation with a minimum at the culmination of the proliferation phase, and a maximum during the secreting phase. This examination was influenced by the administration of hormonal preparations a decrease was observed after an estrogen (diethylstilbestrol), and an increase after a gestagen (ethisterone) (243). 

Fig. 16.7a,b. Normal TVUS. Clear demarcation of the relatively thick and hyperechoic endometrium (arrowheads) during the secretory phase (a), minimal fluid retention during the proliferation phase of the cycle (b)... 

The second phase, the proliferation phase, starts when the wound is clean and the inflammation phase is almost completed. The purpose of this phase is to rebuild the... 

Among secondary products, ketonic function compounds (pyruvic acid, a-ketoglutaric acid) and acetaldehyde predominantly combine with sulfur dioxide in wines made from healthy grapes. Their excretion is significant during the yeast proliferation phase and decreases towards the end of fermentation. Additional acetaldehyde is liberated in the presence of excessive quantities of sulfur dioxide in must. An elevated pH and fermentation temperature, anaerobic conditions, and a deficiency in thiamine and pantothenic acid increase production of ketonic acids. Thiamine supplementing of must limits the accumulation of ketonic compounds in wine (Figure 2.10). 

IL-4" IL-5 primate primate, rodent T, B, mast cell haematopoietic precursor proliferation activated B cell proliferation Phase Il/m NSLC, cancer... 

The hypophysis influences mainly the ovaries, Tvhereas the processes of the uterus are regulated by the gonadal hormones. The estrogen effects production of new mucosa (proliferation phase) which ceases shortly before ovulation. Estrone simultaneously exerts an influence back on the hypophysis by inhibiting the elaboration of FSH and enhancing production of prolactin and the interstitial cell-... 

Wound healing is a complex phenomenon where angiogenesis, ie formation of new blood vessels plays an essential role (Bates and Jones, 2003). The wound healing process can be divided into three main phases inflammatory phase, proliferation phase, and maturation and remodeling phase (Witte and Barbul, 1997), as discussed in the following text (Eig. 10.1). 

Fig. 10.1 Main stages of wound healing. (A) Inflammatory phase. (B) Proliferation phase. (C) Maturation and remodeling phase.

Proliferation phase. The primary cells proliferating in this phase ( 4-15 days post-wounding) are fibroblasts and endothelial cells. Endothelial cells form new capillaries through a process called angiogenesis. Fibroblasts require activation to start proliferation and factors such as PDGF and epidermal growth factor (EGF) are involved in fibroblast activation. One important part of the proliferation phase is the reepitheliali-zation and wound closure (Witte and Barbul, 1997). 

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