共查询到20条相似文献,搜索用时 31 毫秒
1.
Transforming growth factors and control of neoplastic cell growth 总被引:18,自引:0,他引:18
J Keski-Oja E B Leof R M Lyons R J Coffey H L Moses 《Journal of cellular biochemistry》1987,33(2):95-107
Transforming growth factors (TGFs) are peptides that affect the growth and phenotype of cultured cells and bring about in nonmalignant fibroblastic cells phenotypic properties that resemble those of malignant cells. Two types of TGFs have been well characterized. One of these, TGF alpha, is related to epidermal growth factor (EGF) and binds to the EGF receptor, whereas the other, TGF beta, is not structurally or functionally related to TGF alpha or EGF and mediates its effects via distinct receptors. TGF beta is produced by a variety of normal and malignant cells. Depending upon the assay system employed, TGF beta has both growth-inhibitory and growth-stimulating properties. Many of the mitogenic effects of TGF beta are probably an indirect result of the activation of certain growth factor genes in the target cell. The ubiquitous nature of the TGF beta receptor and the production of TGF beta in a latent form by most cultured cells suggests that the differing cellular responses to TGF beta are regulated either by events involved in the activation of the factor or by postreceptor mechanisms. The combined effects of TGF beta with other growth factors or inhibitors evidently play a central role in the control of normal and malignant cellular growth as well as in cell differentiation and morphogenesis. Since transforming growth factor as a concept has partially proven misleading and insufficient, there is a need to find a new nomenclature for these regulators of cellular growth and differentiation. 相似文献
2.
Sixteen Large White × Landrace castrated male pigs were allotted into treatment and control group. The treatment group was
injected intramuscularly with recombinant porcine growth hormone (rpGH, 4 mg d−1) and the control group with vehicle for 28 days. Animals were slaughtered 4 h after final injection for liver, longissimus
dorsi (LD) muscle and blood sampling. Serum concentration of insulin-like growth factor 1 (IGF-I) and leptin were determined
by RIA. The total RNA was extracted from tissues to measure the abundance of growth hormone receptor (GHR), IGF-I mRNA by
RT-PCR with 18S rRNA internal standard. Results showed that rpGH enhanced the average daily weight gain by 26.1% (P < 0.05), the serum IGF-I concentration by 70.94% (P < 0.01), decreased serum leptin by 34.8% (P < 0.01). The relative abundance of GHR and IGF-I mRNA in liver were increased by 24.45% (P < 0.05) and 45.30% (P < 0.01), respectively, but no difference of GHR (P > 0.05) and IGF-I mRNA (P > 0.05) in LD between GH treated and control group was found. These results suggest that rpGH can up-regulate hepatic GHR
and IGF-I gene expression and improve animal growth. However the effect of rpGH on GHR and IGF-I gene expression are tissue-specific. 相似文献
3.
Growth hormone (GH) plays an important role in regulation of animal growth, metabolism and lactation[1]. Numerous studies have shown that exogenous somatotropin (ST) can increase average daily weight gain, improve feed efficiency, stimulate protein deposition and muscle growth and decrease lipid accretion rate[1]. The original somatomedin hypothesis suggested that the effect of GH on postnatal growth was mediated by insulin-like growth hormone factor 1 (IGF-I) which was thought to be deriv… 相似文献
4.
Samer Adeeb Walter Herzog 《Computer methods in biomechanics and biomedical engineering》2013,16(6):617-626
Researchers concerned with the growth of biological tissue often use models that predict the growth as a function of a mechanical stimulus such as stress, strain or elastic energy. However, a general theory for bulk growth should consider that the mechanical stimulus may only be one of many factors contributing to growth. Another important factor could be time, as living tissues can be assumed to have a pre-programmed directional biological growth that is independent of mechanical stimuli. This paper has two objectives: the first is to introduce the concept of directional biological growth within a well developed growth theory, the second is to present the computational methods by which three-dimensional growth that encompasses time and stress effects can be simulated using commercially available finite element analysis software. 相似文献
5.
6.
Micropattern-immobilization of heparin to regulate cell growth with fibroblast growth factor 总被引:1,自引:0,他引:1
Heparin was immobilized on a polystyrene plate in a specificpattern by photolithography. Heparin was coupled with azidoaniline. Thederivatized heparin was cast on the polystyrene plate from aqueoussolution. After drying, the plate was photo-irradiated in the presence of aphotomask. The micropatterning was confirmed by staining with a dye,ethydium bromide. Since heparin has negative charges, the cationic dyewas adsorbed on the regions where heparin was immobilized. In thepresence fibroblast growth factor (FGF), the growth of mouse fibroblastSTO cells was enhanced only on the heparin-immobilized regions. Thisresult indicated that micropattern-immobilized heparin activated FGF forcell growth activity. 相似文献
7.
David A. Belford Mary-Louise Rogers Geoffrey O. Regester Geoffrey L. Francis Geoffrey W. Smithers Ingrid J. Liepe Ilka K. Priebe F. John Ballard 《In vitro cellular & developmental biology. Animal》1995,31(10):752-760
Summary We have investigated the response of several epithelial and fibroblastic cells to a mitogenic extract of bovine milk. Cation
exchange chromatography was used to produce a mitogen-rich fraction from an industrial whey source that, although comprising
only 0.5% of total whey protein, contained the bulk of the growth factor activity. This fraction was a source of potent growth
promoting activity for all mesodermal-derived cells tested, including human skin and embryonic lung fibroblasts, Balb/c 3T3
fibroblasts, and rat L6 myoblasts. Maximal growth of all these cell types exceeded that observed in 10% fetal bovine serum.
Feline kidney and baby hamster fibroblasts and Chinese hamster ovary cells were less responsive, achieving a maximal growth
response of 50–75% that observed in 10% fetal bovine serum. Maximal growth achieved in whey-extract-supplemented cultures
of Balb/c 3T3 and human skin fibroblasts, and L6 myoblast cultures exceeded that seen in response to recombinant acidic or
basic fibroblast growth factor, platelet-derived growth factor, insulin-like growth factor, or epidermal growth factor. Importantly,
addition of low concentrations of fetal bovine serum to the whey-derived mitogenic fraction produced an additive response.
However, concentrated milk-derived factors were found to be inhibitory to the growth of all epithelial lines tested, including
rat intestinal epithelial cells, canine kidney epithelial cells, and mink lung cells. It is concluded that industrial whey
extracted in this form constitutes an important source of potent growth-promoting agents for the supplementation of mesodermal-derived
cell cultures. 相似文献
8.
Since the introduction of the cell cycle concept two approaches to study growth regulation of cells have been proposed. One claims that cells are naturally quiescent, requiring a stimulatory encouter with growth factors for induction of cell division. The other considers cellular multiplication as the natural steady-state; cessation of multiplication is thus a restriction imposed on the system. In the latter case emphasis is mainly on the signals involved in arrest of multiplication. This Prospect focuses on specific events occurring in mammalian cells at growth arrest, senescence, and terminal differentiation, specifically emphasizing the growth inhibitory factors, tumor suppressor genes, and other signals for growth suppression. 相似文献
9.
Summary Recent studies have determined that fibroblast growth factor (FGF) potentiates the soft agar growth responses of NRK-49F cells
to several combinations of transforming growth factors (TGFs). In the current study, two other non-transformed cell lines,
NR-6 and AKR-2B, which do not spontaneously form colonies in soft agar, were examined for their soft agar growth responses
to FGF. Both the acidic form and basic form of FGF were found to induce the soft agar growth of these cells. In the case of
NR-6 cells, the effects of TGF-β were also examined. TFG-β potentiated the soft agar growth response of NR-6 cells to FGF,
but on its own did not induce soft agar growth. Attempts to identify other factors capable of modulating the response of these
cells to FGF, led to the finding that both 12-0-tetra-decanoylphorbol-13-acetate and retinoic acid suppress FGF-induced soft
agar growth of NR-6 cells and AKRR-2B cells. The finding that FGF induces the soft agar growth of both non-transformed cell
lines, together with the findings of others that both forms of FGF are angiogenic, lends further support to the suggestion
that FGF plays a significant role in the in vivo growth of some, and possibly many, tumors.
This work was supported by grants from the Nebraska Department of Health (86-11R, 87-38), the National Institute of Child
Health and Human Development (HD 19837, HD 21568) and the National Cancer Institute (Laboratory Cancer Research Center Support
Grant CA 36727).
Editor's Statement The last several years have seen extraordinary advances in the understanding of the biochemistry and physiology
of heparin-binding growth factors. Among the activities of these peptides that may be of significance for neoplasia and wound
healingin vivo is ability to promote anchorage independent growth of some cell types. In this study the interactions among several stimulatory
and inhibitory factors are examined in a soft agar growth assay. An appreciation of these interactions is critical in attempts
to relatein vitro effects to those in the intact organism. 相似文献
10.
11.
Delayed costs of growth and compensatory growth rates 总被引:4,自引:1,他引:3
12.
Roger Buis 《Acta biotheoretica》1991,39(3-4):185-195
This communication presents a discussion of some extensions of the formalism of Verhulst's simple logistics, which may constitute an autonomous growth model of a more general scope.For that purpose, the basis concept of growth diagram or trajectory is called upon, as it affords the graphic representation of the change in the growth variable y, using two relevant kinetic parameters: the instantaneous rate and the instantaneous acceleration. The two possible kinds of trajectories are in relation to the use of absolute (V = dyldt; = dV/dt) or relative (or specific) values (R = (1/y)(dy/dt);
R
= dR/dt).In the case of simple logistics, the trajectory (V, ) allows 4 growth phases or states to be distinguished. The diagram (R,
R
) shows that the deceleration of the specific rate is not monotonous.In the case of Richards - Nelder's generalized logistics, the qualitative variation of the growth trajectory depends on the value of the dissymmetry parameter (occurrence of a critical value which determines the number of growth states).Blumberg's model is characterized by an analogous property and, moreover, can account for a non monotonous variation of the specific growth rate. 相似文献
13.
Osteopontin contributes to hepatocyte growth factor-induced tumor growth and metastasis formation 总被引:12,自引:0,他引:12
Ariztia EV Subbarao V Solt DB Rademaker AW Iyer AP Oltvai ZN 《Experimental cell research》2003,288(2):257-267
The cytokine hepatocyte growth factor (HGF)/scatter factor-1 and its cognate receptor, Met, are involved in the etiology and progression of many types of cancer. Despite recent advances in understanding the signal transduction pathways activated by HGF, the mechanism by which HGF exerts its tumorigenic effect is not well understood. To identify proteins that may be involved in mediating HGF-induced cell motility, invasiveness, and tumorigenesis, we used two separate differential display screening methods to identify changes in gene expression that are initiated by HGF in an epithelial cell culture system. Among several known and unknown genes whose expression was modified, osteopontin (OPN), a protein previously associated with tumorigenesis, was found to be upregulated within 6 h following HGF stimulation. OPN expression was dependent on activation of the PI-3 kinase pathway. Autocrine secretion of HGF resulted in sustained expression of OPN. Downregulation of opn expression by stable antisense transfection attenuated OPN expression and repressed HGF-induced invasiveness in vitro and decreased HGF-mediated tumor growth and metastasis formation in vivo. Constitutive expression of OPN in itself exerted partial invasiveness in vitro, but its expression itself was not sufficient to initiate tumor growth or metastasis formation in vivo. Thus, together with other molecules, OPN activity contributes to HGF-induced tumor growth and invasiveness. 相似文献
14.
Otolith and somatic mass of two Gadidae ( Merlangius merlangus and Trisopterus minutus ) were compared in order to analyse the sex-specific relationship between otolith and somatic growth at age. In the present study, otolith mass appeared a reliable indicator of age in both species. Otolith growth reflected somatic growth, but the relationship between these characters varied and differed between species and sexes. 相似文献
15.
Ana?lle Dambreville Pierre-éric Lauri Frédéric Normand Yann Guédon 《Annals of botany》2015,115(1):93-105
Background and Aims Plant growth, the increase of organ dimensions over time, and development, the change in plant structure, are often studied as two separate processes. However, there is structural and functional evidence that these two processes are strongly related. The aim of this study was to investigate the co-ordination between growth and development using mango trees, which have well-defined developmental stages.Methods Developmental stages, determined in an expert way, and organ sizes, determined from objective measurements, were collected during the vegetative growth and flowering phases of two cultivars of mango, Mangifera indica. For a given cultivar and growth unit type (either vegetative or flowering), a multistage model based on absolute growth rate sequences deduced from the measurements was first built, and then growth stages deduced from the model were compared with developmental stages.Key Results Strong matches were obtained between growth stages and developmental stages, leading to a consistent definition of integrative developmental growth stages. The growth stages highlighted growth asynchronisms between two topologically connected organs, namely the vegetative axis and its leaves.Conclusions Integrative developmental growth stages emphasize that developmental stages are closely related to organ growth rates. The results are discussed in terms of the possible physiological processes underlying these stages, including plant hydraulics, biomechanics and carbohydrate partitioning. 相似文献
16.
Angie Rizzino 《In vitro cellular & developmental biology. Plant》1984,20(10):815-822
Summary Transforming growth factors (TGFs) are a relatively new category of factors that induce the anchorage-independent growth of
non-transformed cells. These factors are usually detected by their ability to induce normal rat kidney (NRK) fibroblasts to
grow in soft agar. Until now, this assay has been performed in serum-containing medium (SCM). Unfortunately, the background
activity of this assay is variable and dependent on several factors, including passage number of the cells and the serum lot
used. Furthermore, the addition of either EGF or TGF-β alone results in the appearance of additional colonies, which decreases
the sensitivity of the assay. To circumvent these problems, serum-free media have been developed that support the growth of
the NRK cells at low density in both monolayer culture and soft agar. Long-term growth in monolayer cultures occurs in serum-free
medium supplemented with laminin, insulin, transferrin, epidermal growth factor (EGF), fibroblast growth factor (FGF) and
high density lipoprotein (HDL). Growth in soft agar occurs when TGFs are added to a serum-free medium, AIG medium, that contains
insulin, transferrin, FGF and HDL. In contrast to the background activity observed when the assay is performed in SCM, no
colonies form in the AIG medium unless TGFs are added and few, if any, colonies form if EGF or TGF-β are added alone. Thus,
the AIG medium provides an improved assay for TGFs. In addition, the AIG medium should prove useful for examining other factors,
including serum factors, for TGF activity.
Editor's Statement This communication describes a modification of the standard assay for transforming growth factors. The
techniques employed make use of advantages provided by recent advances in serum-free cell culture to provide a well-defined
detection system that is more sensitive than conventional procedures. Experimental approaches described in this article also
should be helpful in unraveling differences in cellular behavior encountered under anchorage-dependent vs. anchorage-independent
conditions. D. W. Barnes 相似文献
17.
Coral growth and reef growth: a brief review 总被引:2,自引:1,他引:1
Wolf-Christian Dullo 《Facies》2005,51(1-4):33-48
The growth potential of modern zooxanthellate corals from the major reef provinces is reviewed with respect to Holocene reef growth. Both coral growth and reef growth is enhanced globally at the beginning of the Holocene and is maintained regionally in the Caribbean Sea up to the present in contrast to reefs of the Indo-Pacific Ocean. This regional difference is mainly caused by the siphoning effect of the tropical Atlantic, which is characterised still by a rising sea level in contrast to global ocean. Hence, Indo-Pacific reefs exhibit a well-cemented reef crest and reef roof barren of living corals. The evaluation of reef growth rates throughout the Phanerozoic shows reduced growth rates of more than one order of magnitude in comparison to their modern counterparts. This is a result of compaction and diagenesis but also strongly biased by uncertainties in absolute dating. Point counting of individual framebuilders with known growth rate may result in more comparative figures for growth rates of fossil reefs with respect to modern ones. 相似文献
18.
19.
Almost all of the previous studies with growth hormone (GH) have been done with exogenously supplied GH and, therefore, involve actions of the hormone through its receptor. However, the actions of endogenous or lymphocyte GH are still unclear. In a previous study, we showed that overexpression of GH (GHo) in a lymphoid cell line resulted in protection of the cells to apoptosis mediated by nitric oxide (NO). In the present study, we show that the protection from apoptosis could be transferred to control cells with culture fluids obtained from GHo cells and blocked by antibodies to the insulin-like growth factor-1 (IGF-1) or antibodies to the IGF-1-receptor (IGF-1R). Northern and Western blot analysis detected significantly higher levels of IGF-1 in cells overexpressing GH. An increase in the expression of the IGF-1R in GHo cells was also detected by Western blot analysis, (125)I-IGF-1 binding and analysis of IGF-1R promoter luciferase constructs. Transfection of GHo cells with a dominant negative IGF-1R mutant construct blocked the generation of NO and activation of Akt seen in GHo cells compared to vector alone control EL4 cells. The results suggest that one of the consequences of the overexpression of GH, in cells lacking the GH receptor, is an increase in the expression of IGF-1 and the IGF-1R which mediate the protection of EL4 lymphoma cells from apoptosis. 相似文献
20.
Relationships between otolith microstructure, otolith growth, somatic growth and ontogenetic transitions in two cohorts of windowpane 总被引:1,自引:0,他引:1
Otolith increments in larval and juvenile windowpane Scophthalmus aquosus can provide an estimate of daily age for spring-spawned individuals held under summer conditions. Otolith increments for spring- and autumn-spawned individuals occurred at intervals >1 day under winter conditions. A significant decrease in the slope of the linear relationship between otolith size and somatic size at 40 mm LS coincided with significant habitat, morphological and behavioural transitions. In smaller, field-captured windowpane belonging to spring- and autumn-spawned cohorts, the formation of accessory growth centres coincided with a transitional settlement period and the completion of eye migration (c. 8–20 mm LS ). Back-calculated growth rate estimates for spring-spawned windowpane were significantly faster than those for autumn-spawned windowpane and these differences could produce differential rates of survival for the two cohorts during the first year of life. 相似文献