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Adult Organism (adult + organism)
Selected AbstractsDifferential cytokine activity and morphology during wound healing in the neonatal and adult rat skinJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 6 2007W. Wagner Abstract Wound-healing mechanisms change during transition from prenatal to postnatal stage. Cytokines are known to play a key role in this process. The current study investigated the differential cytokine activity and healing morphology during healing of incisional skin wounds in rats of the ages neonatal (p0), 3 days old (p3) and adult, after six different healing times (2 hrs to 30 days). All seven tested cytokines (Transforming Growth Factor (TGF) ,, TGF,1, ,,2 and ,,3, IGF 1, Platelet Derived Growth Factor A (PDGF A), basic Fibroblast Growth Factor (bFGF) exhibited higher expression in the adult wounds than at the ages p0 and p3. Expression typically peaked between 12 hrs and 3 days post-wounding, and was not detectable any more at days 10 and 30. The neonate specimen showed more rapid re-epithelialization, far less inflammation and scarring, and larger restitution of original tissue architecture than their adult counterparts, resembling a prenatal healing pattern. The results may encourage the use of neonatal rat skin as a wound-healing model for further studies, instead of the more complicated prenatal animal models. Secondly, the data may recommend inhibition of PDGF A, basic FGF or TGF-,1 as therapeutic targets in efforts to optimize wound healing in the adult organism. [source] Apoptosis: a basic biological phenomenon with wide-ranging implications in human diseaseJOURNAL OF INTERNAL MEDICINE, Issue 6 2005B. FADEEL Abstract. Apoptosis is a highly regulated process of cell deletion and plays a fundamental role in the maintenance of tissue homeostasis in the adult organism. Numerous studies in recent years have revealed that apoptosis is a constitutive suicide programme expressed in most, if not all cells, and can be triggered by a variety of extrinsic and intrinsic signals. Many human diseases can be attributed directly or indirectly to a derangement of apoptosis, resulting in either cell accumulation, in which cell eradication or cell turnover is impaired, or cell loss, in which the apoptotic programme is inadvertently triggered. In addition, defective macrophage engulfment and degradation of cell corpses may also contribute to a dysregulation of tissue homeostasis. An increased understanding of the signalling pathways that govern the execution of apoptosis and the subsequent clearance of dying cells may thus yield novel targets for therapeutic intervention in a wide range of human maladies. [source] Apoptosis, anoikis and their relevance to the pathobiology of colon cancerPATHOLOGY INTERNATIONAL, Issue 4 2000Minalini Shanmugathasan The maintenance of a constant number of cells in an adult organism is a tightly regulated process. This is particularly important in organs where cells are in a constant rate of renewal during the entire lifespan. In these organs, cell number homeostasis is the direct consequence of a bal-ance between cell proliferation and apoptosis. The colonic epithelium is an example of such a site and the high prevalence of colon cancer makes the understanding of cell number homeostasis more important to define. Normal colonic epithelium is organized in crypts where cell proliferation, migration, differentiation and apoptosis are topographically organized in a linear fashion along the crypt axis. Normal colonic crypts are composed of stem cells at the base, a proliferation and a differentiation zone in the lower third of the crypt, a migration zone in the upper two-thirds, and the surface epithelium where senescent cells are eliminated by apoptosis. Globally, apoptosis can be defined as a normal process of cell suicide, critical for development and tissue homeostasis. Colonic epithelial cells migrate from the base of the crypt to the surface epithelium in 6,7 days. The normal architecture of the crypt is maintained by a balance between cell proliferation at the base and apoptosis at the top of the crypt and surface epithelium. [source] Controlling the stem cell niche: right time, right place, right strengthBIOESSAYS, Issue 1 2006Catherin Niemann Wnt signalling through ,-catenin plays a pivotal role during embryonic pattern formation, cell fate determination and tissue homeostasis in the adult organism. In the skin, as in many other tissues, Wnt/,-catenin signalling can control lineage determination and differentiation. However, it was not known whether Wnt/,-catenin signalling is an immediate regulator of the stem cell niche in skin tissue. A recent publication now provides evidence that Wnt/,-catenin signalling exerts a direct effect on the stem cell compartment by inducing quiescent stem cells to enter the cell cycle during early stages of hair follicle regeneration. In addition, the authors demonstrate that ,-catenin is required for maintenance of the stem cell pool in the tissue.1 The data suggest that a gradient in Wnt/,-catenin activity levels can induce different responses within distinct cell populations reflected by activation of distinct transcriptional profiles. BioEssays 28:1,5, 2006. © 2005 Wiley Periodicals, Inc. [source] Glucose-responsive insulin-producing cells from stem cellsDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 6 2002David J. Kaczorowski Abstract Recent success with immunosuppression following islet cell transplantation offers hope that a cell transplantation treatment for type 1 (juvenile) diabetes may be possible if sufficient quantities of safe and effective cells can be produced. For the treatment of type 1 diabetes, the two therapeutically essential functions are the ability to monitor blood glucose levels and the production of corresponding and sufficient levels of mature insulin to maintain glycemic control. Stem cells can replicate themselves and produce cells that take on more specialized functions. If a source of stem cells capable of yielding glucose-responsive insulin-producing (GRIP) cells can be identified, then transplantation-based treatment for type 1 diabetes may become widely available. Currently, stem cells from embryonic and adult sources are being investigated for their ability to proliferate and differentiate into cells with GRIP function. Human embryonic pluripotent stem cells, commonly referred to as embryonic stem (ES) cells and embryonic germ (EG) cells, have received significant attention owing to their broad capacity to differentiate and ability to proliferate well in culture. Their application to diabetes research is of particular promise, as it has been demonstrated that mouse ES cells are capable of producing cells able to normalize glucose levels of diabetic mice, and human ES cells can differentiate into cells capable of insulin production. Cells with GRIP function have also been derived from stem cells residing in adult organisms, here referred to as endogenous stem cell sources. Independent of source, stem cells capable of producing cells with GRIP function may provide a widely available cell transplantation treatment for type 1 diabetes. Copyright © 2002 John Wiley & Sons, Ltd. [source] Phenotypic and genetic variation in emergence and development time of a trimorphic damselflyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2005J. ABBOTT Abstract Although colour polymorphisms in adult organisms of many taxa are often adaptive in the context of sexual selection or predation, genetic correlations between colour and other phenotypic traits expressed early in ontogeny could also play an important role in polymorphic systems. We studied phenotypic and genetic variation in development time among female colour morphs in the polymorphic damselfly Ischnura elegans in the field and by raising larvae in a common laboratory environment. In the field, the three different female morphs emerged at different times. Among laboratory-raised families, we found evidence of a significant correlation between maternal morph and larval development time in both sexes. This suggests that the phenotypic correlation between morph and emergence time in the field has a parallel in a genetic correlation between maternal colour and offspring development time. Maternal colour morph frequencies could thus potentially change as correlated responses to selection on larval emergence dates. The similar genetic correlation in male offspring suggests that sex-limitation in this system is incomplete, which may lead to an ontogenetic sexual conflict between selection for early male emergence (protandry) and emergence times associated with maternal morph. [source] | |||||||||||||