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Results for “developmental dynamics”

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At least 1,603 records · Page 89Linked to original sources
PubMed2005

Dexamethasone regulation of cFos mRNA in osteoprogenitors.

The glucocorticoid, dexamethasone (Dex), has a beneficial effect on osteogenesis by increasing the activation and differentiation of osteoblastic cells. We investigated the effect of Dex on osteoblasts and detected changes in pattern of expression of cFos mRNA. cFos is an early response gene that is expressed as unspliced and spliced mRNAs. We analyzed the regulation of cFos mRNA in correlation with the cell proliferation status and following the induction by Dex. Treatment of osteoblastic cells with Dex for 30 min resulted in elevated levels of spliced form of cFos mRNA, which was maintained with extended treatment of cultured cells for 24 h. In addition, we demonstrated interaction between glucocorticoid receptor (GR) and cFos mRNA. This study provides evidence for the action of Dex on osteoblasts through dynamic cell responses involving with cFos.

Animals↗
PubMed1997

Geometric analysis of macronutrient selection in the rat.

A conceptual framework is introduced which has been derived from work on insects. The scheme is intended to integrate studies of diet selection, regulation of amounts eaten, nutrient utilization, body composition and animal performance. Aspects of framework are illustrated with published data on macronutrient selection in the rat. An animal is viewed as moving through a multidimensional nutrient space, which is bounded by axes representing each required nutrient and within which lie optimal points of intake and nutrient allocation ("targets"). The aim is first to estimate the location of these functional optima experimentally, and then to interpret the responses of animals which are constrained from reaching them ("decisions of best compromise"). The framework can then be used to interpret data from animals reared under differing environmental conditions and to compare animals of differing developmental stage, genotype or nutritional state.

Animals↗
PubMed1998

Cell fate regulation in the shoot meristem.

The shoot meristem is a proliferative centre containing pluripotent stem cells that are the ultimate source of all cells and organs continuously added to the growing shoot. The progeny of the stem cells have two developmental options, either to renew the stem cell population or to leave the meristem and to differentiate, possibly according to signals from more mature tissue. The destiny of each cell depends on its position within the dynamic shoot meristem. Genetic data suggest a simple model in which graded positional information is provided by antagonistic gene functions and is interpreted by genes which regulate cell fate.

Body Patterning↗
PubMed2002

[Generative potential in advanced age. Sociological intergenerational considerations of an old topic].

The concept of generativity--at first related to middle age--is increasingly used to describe developmental processes at higher ages. In previous discussions, however, the concept of generativity has been used without clear references either to stages in later life (independent retirement versus dependent old age) or to different concepts of generations. A stage-oriented approach--based on ideas developed by Margret Baltes--indicates that the dimensions of generativity change with aging (more active generativity for younger retired people, more passive and compensating generativity among fragile and dependent persons). A generational approach--looking at different concepts of generations (family generations, societal generations, welfare generations)--shows that generativity within family generations is underlined by social norms, whereas generativity concerning welfare generations or societal generations remains an unstructured or even anomic developmental task.

Activities of Daily Living↗
PubMed2003

Development of human brain functions.

Aspects of postnatal human brain development are reviewed. The development of brain function has commonly been characterized in terms of the unfolding of a maturational sequence. In contrast, we argue that postnatal functional brain development occurs through a dynamic process of emerging patterns of interactions between different brain regions. Some of these processes may also be characteristic of perceptual and motor skill learning in adults. Possible implications of these views for our understanding of developmental disorders are raised.

Brain↗
PubMed2001

Is a quantitative approach useful in the comparison of spontaneous movements in fullterm and preterm infants?

Spontaneous motility in the first six months of infancy has been examined over the last few decades using both qualitative and quantitative techniques. The major focus of the quantitative research has been to investigate a dynamic systems approach to understanding motor development, and has primarily examined normal development in fullterm infants. Recently, there have been several papers comparing spontaneous kicking in fullterm and preterm infants. These studies were designed to identify developmental differences that may indicate a risk of later motor disability. There has, however, been criticism that the quantitative approach fails to detect developmental differences that are useful in early identification of disability, unlike qualitative approaches which use the principles of Gestalt perception to examine the quality of the total movement pattern in young infants. The current paper describes both qualitative and quantitative techniques and reviews recent studies using motion analysis to compare early motor development in fullterm and preterm infants. New evidence is provided to suggest that the quantitative approach may not only be useful in detecting infants at risk of motor disability, but may also be useful in identifying the underlying processes that determine normal and abnormal motor outcomes.

Functional Laterality↗
PubMedDate not supplied

Inbreeding and developmental stability in a small human population.

Inbreeding coefficients are reported for all members of the isolated Havasupai tribe of northern Arizona (USA), based upon pedigrees which are as deep as eight generations. Because inbreeding has been repeatedly shown to reduce developmental homeostasis in a large number of species, we ask if the degree of inbreeding in the Havasupai is associated with reduced developmental stability. Fluctuating asymmetry in two dermatoglyphic traits suggests that inbreeding significantly compromises developmental homeostasis in this population.

Analysis of Variance↗
PubMed2003

Developing a virtual interdisciplinary research community in higher education.

As multidisciplinary collaboration in both clinical and research settings is becoming a key aspect of contemporary health care, strategies to enhance interprofessional interaction in postgraduate research programmes can offer important experiences to facilitate ongoing interprofessional relationships. This paper provides a retrospective appraisal of a strategy which used computer-mediated communication to develop a virtual community network, known as'health_voice' accessed through a web page. The rationale for developing the network is presented, and the process of designing and establishing the web-site through an action research approach is described The outcome of the strategy is reviewed with regard to the relationships between the real' and 'virtual' community. Reflections on the developmental process contextualise the initiative within a concept of a community-of-practice. It is acknowledged that the use of a virtual arena for communication within a research community involves a cultural change in the dynamics of higher degree teaching and learning. Future plans to further embed the virtual environment within a postgraduate research culture are given.

Cooperative Behavior↗
PubMed2002

Tropomyosin inhibits ADF/cofilin-dependent actin filament dynamics.

Tropomyosin binds to actin filaments and is implicated in stabilization of actin cytoskeleton. We examined biochemical and cell biological properties of Caenorhabditis elegans tropomyosin (CeTM) and obtained evidence that CeTM is antagonistic to ADF/cofilin-dependent actin filament dynamics. We purified CeTM, actin, and UNC-60B (a muscle-specific ADF/cofilin isoform), all of which are derived from C. elegans, and showed that CeTM and UNC-60B bound to F-actin in a mutually exclusive manner. CeTM inhibited UNC-60B-induced actin depolymerization and enhancement of actin polymerization. Within isolated native thin filaments, actin and CeTM were detected as major components, whereas UNC-60B was present at a trace amount. Purified UNC-60B was unable to interact with the native thin filaments unless CeTM and other associated proteins were removed by high-salt extraction. Purified CeTM was sufficient to restore the resistance of the salt-extracted filaments from UNC-60B. In muscle cells, CeTM and UNC-60B were localized in different patterns. Suppression of CeTM by RNA interference resulted in disorganized actin filaments and paralyzed worms in wild-type background. However, in an ADF/cofilin mutant background, suppression of CeTM did not worsen actin organization and worm motility. These results suggest that tropomyosin is a physiological inhibitor of ADF/cofilin-dependent actin dynamics.

Actin Cytoskeleton↗
PubMed2003

The AP-1 clathrin-adaptor is required for lysosomal enzymes sorting and biogenesis of the contractile vacuole complex in Dictyostelium cells.

Adaptor protein complexes (AP) are major components of the cytoplasmic coat found on clathrin-coated vesicles. Here, we report the molecular and functional characterization of Dictyostelium clathrin-associated AP-1 complex, which in mammalian cells, participates mainly in budding of clathrin-coated vesicles from the trans-Golgi network (TGN). The gamma-adaptin AP-1 subunit was cloned and shown to belong to a Golgi-localized 300-kDa protein complex. Time-lapse analysis of cells expressing gamma-adaptin tagged with the green-fluorescent protein demonstrates the dynamics of AP-1-coated structures leaving the Golgi apparatus and rarely moving toward the TGN. Targeted disruption of the AP-1 medium chain results in viable cells displaying a severe growth defect and a delayed developmental cycle compared with parental cells. Lysosomal enzymes are constitutively secreted as precursors, suggesting that protein transport between the TGN and lysosomes is defective. Although endocytic protein markers are correctly localized to endosomal compartments, morphological and ultrastructural studies reveal the absence of large endosomal vacuoles and an increased number of small vacuoles. In addition, the function of the contractile vacuole complex (CV), an osmoregulatory organelle is impaired and some CV components are not correctly targeted.

Adaptor Protein Complex 1↗
PubMed2005

Imprinted X inactivation and reprogramming in the preimplantation mouse embryo.

X chromosome inactivation is a developmentally regulated process that causes one of the two X chromosomes in normal female mammals to become transcriptionally silenced, thus equalizing the expression of X-linked genes between the sexes. Such dosage compensation depends upon dynamic genetic and epigenetic events occurring very early in development. X inactivation is controlled by an X inactivation centre that is associated with the expression of non-coding RNAs required for the silencing. Also associated with the inactive X are repressive histone modifications and polycomb protein-mediated states, which are progressively acquired during the inactivation process. In mouse, two forms of X inactivation have been described. Random X inactivation happens in the derivatives of the inner cell mass (ICM) giving rise to embryos where the maternally inherited X(Xm) is inactive in some cells and the paternally derived X (Xp) is inactive in others. Random X inactivation occurs around the time of implantation. Imprinted X inactivation, the preferential inactivation of the Xp chromosome, occurs earlier and, although there has been some debate as to the precise timing of initiation of this event, is apparent in all cells early in preimplantation development, then is subsequently confined to the cells of the extraembryonic lineages. A picture is emerging whereby initial epigenetic asymmetry between the two parental X chromosomes is reprogrammed in a lineage specific manner resulting in a switch from imprinted to random inactivation in embryonic derivatives. Neither the underlying reason nor the full extent of these early lineage specific epigenetic changes is known, but they may be correlated with more genome-wide reprogramming events essential for normal development.

Alleles↗
PubMed2006

Chronic cocaine exposure impairs progenitor proliferation but spares survival and maturation of neural precursors in adult rat dentate gyrus.

Recent observations indicate that drugs of abuse, including alcohol and opiates, impair adult neurogenesis in the hippocampus. We have studied in rats the impact of cocaine treatment (20 mg/kg, daily, i.p.) on cell proliferation, survival and maturation following short-term (8-day) and long-term (24-day) exposure. Using 5'-bromo-2-deoxyuridine (BrdU) and Ki-67 as mitotic markers at the end of the drug treatments, we found that both short- and long-term cocaine exposures significantly reduced cell proliferation in the dentate gyrus (DG) of the hippocampus. By labelling mitotic cells with BrdU pulses before or during the early stages of the drug treatment, we determined that long-term cocaine exposure did not affect the survival of newly generated cells. In register with this finding, cocaine chronic exposure did not increase the number of apoptotic cells labelled by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling). Using doublecortin (DCX) immunocytochemistry and electron microscopy, we next examined the effects of cocaine exposure on the maturation of the neural precursors and on synaptic output to CA3. DCX immunocytochemistry showed that immature hippocampal cells of rats exposed to cocaine displayed normal arborization patterns and similar degrees of colocalization with BrdU at two different developmental stages. Moreover, cocaine did not produce significant morphological alterations of the mossy fibre projection system to stratum lucidum in the CA3 area of the hippocampus. The results presented demonstrate that chronic cocaine exposure impairs proliferation dynamics in the DG without significantly altering either the survival and growth of immature cells or the structural features of terminal projections to CA3.

Animals↗
PubMed2002

A pea seed mutant affected in the differentiation of the embryonic epidermis is impaired in embryo growth and seed maturation.

During legume seed development the epidermis of the embryos differentiates into a transfer cell layer which mediates nutrient uptake during the storage phase. This specific function of the epidermal cells is acquired at the onset of embryo maturation. We investigated this process in the pea seed mutant E2748. The epidermal cells of the mutant embryo, instead of turning into transfer cells, enlarge considerably and become vacuolated and tightly associated with adjacent seed tissues. Expression of a sucrose transporter gene that is upregulated in wild-type transfer cells decreases in the mutant and changes its spatial pattern. This indicates that the outermost cell layer of mutant cotyledons cannot acquire transfer cell morphology but loses epidermal cell identity and does not function as a sucrose uptake system. Seed coat growth as well as composition, concentration and dynamics of sugars within the endospermal vacuole are unchanged. The loss of epidermal identity has severe consequences for further embryo development and is followed by disruption of the symplast within the parenchyma, the breach of the developmental gradient, lower sucrose and starch levels and initiation of callus-like growth. It is concluded that the E2748 gene controls differentiation of the cotyledonary epidermis into transfer cells and thus is required for the regional specialisation with a function in embryo nutrition.

Cell Differentiation↗
PubMed2002

Drosophila syntaxin 16 is a Q-SNARE implicated in Golgi dynamics.

SNARE isoforms appear to regulate specific intracellular membrane trafficking steps. To identify new SNARE proteins in Drosophila melanogaster we used a yeast two-hybrid screen to search for proteins that interact with SNAP. Here we report the identification of the Drosophila homologue of syntaxin 16. dsyntaxin 16 binds SNAP in a concentration-dependent fashion and genetically interacts with NSF2. Like its mammalian homologue, dsyntaxin 16 is ubiquitously expressed and appears to be localized to the Golgi apparatus. In addition, membranes containing dsyntaxin 16 become aggregated upon Brefeldin A treatment and are dispersed during meiosis. Inhibition of dsyntaxin 16 function by overexpression of truncated forms in cultured Schneider cells indicates that dsyntaxin 16 may selectively regulate Golgi dynamics.

Amino Acid Sequence↗
PubMed2006

Effective interviewing and counseling of the adolescent patient.

A vast number of successful recommendations are available to physicians who want to learn how to strengthen their interactions with adolescent patients. Understanding that the physician-patient relationship is dynamic is the first step toward building a strong repertoire within this patient sample. Therefore, physicians may assume that adolescent perceptions of the physician-patient relationship and the services provided will change as they change developmentally or as the situation is modified. Finding a balance between family and patient concerns while gaining increased experience with skills less-practiced (eg, communication about sensitive topics) will improve adolescent perceptions of your expertise, knowledge, and abilities. Finally, following up on changes across time in adolescents' concerns, perceptions, abilities, and the physician-patient relationship itself, will help to ensure continued satisfaction and service use by adolescents and their families.

Adolescent↗
PubMed1989

Psychologic morbidity of children subjected to Munchausen syndrome by proxy.

Munchausen syndrome by proxy is being recognized and reported with increasing frequency, which suggests that it is more common and occurs with a wider spectrum of severity than was previously suspected. In past reports, the difficulties of detecting and documenting the syndrome have been emphasized, as well as its physical morbidity and mortality. The psychologic morbidity of Munchausen syndrome by proxy in six children is described. The children reacted with developmentally appropriate behavior problems ranging from feeding disorders in infants, withdrawal and hyperactivity in preschool-aged children, to hysterical disorders and personal adoption of Munchausen syndrome behavior in adolescents. Parental psychologic and behavioral styles, family dynamics, and responses from legal and children's protective services systems make protection of the child within the home difficult, if not impossible. Even with protection from further physical injury, severe psychologic trauma remains likely. Extreme caution is suggested in allowing these children to remain in the family.

Adolescent↗
PubMed1985

Abortion in adolescence.

This article reviews the difficult but complex subject of abortion in adolescents. Methods of abortion are outlined and additional aspects are presented: psychological effects, counseling issues, and legal parameters. It is our conclusion that intense efforts should be aimed at education of youth about sexuality and prevention of pregnancy, utilizing appropriate contraceptive services. When confronted with a youth having an unwanted pregnancy, all legal options need to be carefully explored: delivery, adoption, or abortion. The decision belongs to the youth and important individuals in her environment. Understanding developmental aspects of adolescence will help the clinician deal with the pregnant teenagers. If abortion is selected, a first trimester procedure is best. Finally, physicians are urged to be aware of the specific, ever changing legal dynamics concerning this subject which are present in their states. Abortion is a phenomenon which has become an emotional but undeniably important aspect of adolescent sexuality and adolescent health care, in this country and around the world.

Abortion, Induced↗
PubMed2002

Developmental expression and biochemical characterization of Emu family members.

Kidney development has often served as a model for epithelial-mesenchymal cell interaction where the branching epithelium of the ureteric bud induces the metanephrogenic mesenchyme to form epithelial nephrons. In a screen for genes differentially expressed during kidney development, we have identified a novel gene that is dynamically expressed in the branching ureter and the developing nephrons. It was designated Emu1 since it shares an N-terminal cysteine-rich domain with Emilin1/2 and Multimerin. This highly conserved EMI domain is also found in another novel protein (Emu2) of similar protein structure: an N-terminal signal peptide followed by the EMI domain, an interrupted collagen stretch, and a conserved C-terminal domain of unknown function. We identified two further secreted EMI domain proteins, prompting us to compare their gene and protein structures, the EMI domain phylogeny, as well as the embryonic expression pattern of known (Emilin1/2, Multimerin) and novel (Emu1/2, Emilin3, Multimerin2) Emu gene family members. Emu1 and Emu2 not only show a similar structural organization, but furthermore a striking complementary expression in organs developing through epithelial-mesenchymal interactions. In these tissues, Emu1 is restricted to epithelial and Emu2 to mesenchymal cells. Preliminary biochemical analysis of Emu1/2 confirmed that they are secreted glycoproteins which are attached to the extracellular matrix and capable of forming homo- and heteromers via disulfide bonding. The widespread, but individually distinct expression patterns of all Emu gene family members suggest multiple functions during mouse embryogenesis. Their multidomain protein structure may indicate that Emu proteins interact with several different extracellular matrix components and serve to connect and integrate the function of multiple partner molecules.

3T3 Cells↗