Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “developmental dynamics”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed2004

Stage-dependent dynamics and modulation of spontaneous waves in the developing rabbit retina.

We report here a systematic investigation of the dynamics, regulation and distribution of spontaneous waves in the rabbit retina during the course of wave development prior to eye opening. Three major findings were obtained in this longitudinal study. (1) Spontaneous retinal waves underwent three developmental stages, each of which displayed distinct wave dynamics, pharmacology and mechanism of generation and regulation. Stage I waves emerged prior to synaptogenesis and appeared as frequent, fast propagating waves that did not form spatial boundaries between waves. These waves could be inhibited by blockers of gap junctions and adenosine receptors, but not by nicotinic antagonists. Stage I waves lasted about one day (around embryonic day 22) and then switched rapidly to stage II, resulting in slower and less frequent waves that could be blocked by nicotinic antagonists and had a characteristic postwave refractory period and spatial boundaries between adjacent waves. Immediately after the transition from stage I to stage II, the waves could be reverted back to stage I by blocking nicotinic receptors, indicating the presence of mutually compensatory mechanisms for wave generation. Stage III waves emerged around postnatal day 3-4 (P3-4), and they were mediated by glutamtergic and muscarinic interactions. With age, these waves became weaker, more localized and less frequent. Spontaneous waves were rarely detected after P7. (2) GABA strongly modulated the wave dynamics in a stage- and receptor type-dependent manner. At stage I, endogenous GABAB activation downregulated the waves. The GABAB modulation disappeared during stage II and was replaced by a strong GABA(A/C)-mediated inhibition at stage III. Blocking GABA(A/C) receptors not only dramatically enhanced spontaneous stage III waves, but also induced propagating waves in >P7 retinas that did not show spontaneous waves, indicating a role of GABA inhibition in the disappearance of spontaneous waves. (3) Spontaneous retinal waves were found in both the inner and outer retina at all three stages. The waves in the outer retina (ventricular zone) also showed stage-dependent pharmacology and dynamics. Together, the results revealed a multistaged developmental sequence and stage-dependent dynamics, pharmacology and regulation of spontaneous retinal waves in the mammalian retina. The presence of retinal waves during multiple developmental stages and in multiple retinal layers suggests that the waves are a general developmental phenomenon with diverse functions.

Aging↗
PubMedDate not supplied

Child development and public policy: toward a dynamic systems perspective.

Little theoretical work exists that proposes general mechanisms for how public policies may influence child development. This article argues that dynamic systems theories may be useful in illuminating such processes, as well as highlighting gaps in current research at the intersection of public policy analysis and developmental science. A brief review of dynamic systems theories as they are currently utilized in other areas of developmental science is provided, as well as a statement of why they may help advance research in public policy and child development. Five principles of dynamic systems theories are presented and discussed using examples from research that address the question, "How do current antipoverty and welfare reform policies affect children?" Also presented are examples of hypotheses and research questions that each principle may generate for future work. The concluding section presents challenges that each principle poses for research methodology, and potential uses of the dynamic systems approach for developing and integrating policy and program initiatives.

Child↗
PubMed2004

The next step in systems biology: simulating the temporospatial dynamics of molecular network.

As a result of the time- and context-dependency of gene expression, gene regulatory and signaling pathways undergo dynamic changes during development. Creating a model of the dynamics of molecular interaction networks offers enormous potential for understanding how a genome orchestrates the developmental processes of an organism. The dynamic nature of pathway topology calls for new modeling strategies that can capture transient molecular links at the runtime. The aim of this paper is to present a brief and informative, but not all-inclusive, viewpoint on the computational aspects of modeling and simulation of a non-static molecular network.

Algorithms↗
PubMed2001

A developmental-psychobiological approach to developmental neuropsychology.

Although both developmental psychobiology and developmental neuropsychology examine the interface between biological and psychological processes, they differ in conceptual framework. This article argues for the incorporation into developmental neuropsychology of certain aspects of the conceptual framework of developmental psychobiology. Three principles of dynamic psychobiological interaction are described and applied to four issues in neuropsychology (handedness, sex differences in behavior, critical periods, and modularity of structure-function relations). Then, it is proposed that developmental psychobiology can make four direct contributions to developmental neuropsychology. Finally, it is argued that the value of the conceptual framework provided by developmental psychobiology depends, in part, on how well it translates into procedures that can be applied in the clinical settings of the developmental neuropsychologist.

Animals↗
PubMed1988

The preschool child: developmental themes and clinical issues.

The preschool years are a remarkable period of dramatic growth in the areas of physical, affective, and cognitive development. Physical development is characterized by a slow but steady rate of somatic growth and the mastery of motor skills that facilitate the child's achievement of autonomy and independence. Major themes in affective development include the achievement of autonomy and independence from family, a lessening of attachment to parents and the alleviation of separation anxiety, and the acquisition of impulse control and socialization skills. Cognitive development during the so-called preoperational period is best characterized by the mastery of language. The remarkable developmental gains achieved during this dynamic period culminate in a child who can function independently and competently and begin the major occupation of childhood--attending school. Health maintenance issues during the preschool years directly reflect the child's developmental stage. For example, nutritional issues reflect not only physical growth and motor skills, but also negativism and the child's struggle to achieve autonomy. Similarly, safety and injury prevention related to the "motor-minded" behavior so characteristic of children at this age, as well as the illogical, egocentric thought that predominates during this period of cognitive development. Examples of other stage-related issues addressed during health maintenance visits include discipline and behavior problems, sleep problems and night awakening, and toilet training. The unique aspects of development during the preschool years also have implications for other components of child health maintenance, including developmental screening, procedures and immunizations, and physical assessment. A number of clinical issues are of special significance during the preschool years. For example, the most common causes of children's short stature, constitutional delay in growth and familial short stature, may result in major parental concerns at this time. Recurrent otitis media is an important problem during this period of language acquisition. Among preschool children with urinary tract infections, the risk of an underlying structural anomaly of the urinary tract and the danger of irreversible renal damage is greater than for older children.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed2006

Remodelling epithelial tubes through cell rearrangements: from cells to molecules.

Epithelial cell movements, such as those that occur during cell intercalation, largely contribute to the formation of epithelial structures during the morphogenesis of multicellular organisms. As the architecture of epithelial tissues relies on strong adhesion between cells at adherens junctions (AJs), the intercalation or rearrangements of epithelial cells might be controlled by modulating the adhesion dynamics of the AJs by internal or external forces. In this review, we describe recent progress in understanding cell rearrangements during epithelial tube remodelling and discuss several models that might account for the developmental control of the spatial dynamics of AJs.

Adherens Junctions↗
PubMed2000

Developmental systems and psychopathology.

Efforts to understand the etiology of adult mental disorders by studying children has produced unanticipated changes in our understanding of pathology, individual development, and the role of social context. Among these are the blurring of the division between mental illness and mental health, the need to attend to patterns of adaptation rather than personality traits, and the powerful influences of the social world on individual development. Current developmental views place deviancy in the dynamic relation between individuals and their contexts. At another level, when we view the history of developmental psychopathology, dialectical developmental processes are evident as we trace how patterns of adaptation of researchers, expressed in theoretical models and empirical paradigms. increasingly have come to match the complexities of human mental health and illness.

Adaptation, Psychological↗
PubMed1987

[Etiologic factors of cervical spondylotic myelopathy in aged patients--clinical and radiological studies].

Thirty-seven aged patients with cervical spondylotic myelopathy were investigated clinically and radiologically, and their findings were compared with those of younger patients. Dynamic canal stenosis in addition to developmental canal stenosis had a significant role in the occurrence of myelopathy in the aged patients. This dynamic canal stenosis was commonly encountered in the upper disc levels of C3-4 and C4-5. Myelography and CT-metrizamide myelography represented multisegmental lesions which resulted in variable clinical features. Spinal cord compression was correlated with severity of symptoms (p less than 0.05) and was more extensive in the elderly than in the younger patients. Furthermore, morphological changes of spinal cord were classified into four types: central, lateral, diffuse and additionally atrophic types. The high prevalence of diffuse type (51.4%) and atrophic type (21.6%) in the aged patients suggested that the prognosis despite treatment might be poor.

Aged↗
PubMed2006

Population dynamics of sporogony for Plasmodium vivax parasites from western Thailand developing within three species of colonized Anopheles mosquitoes.

BACKGROUND: The population dynamics of Plasmodium sporogony within mosquitoes consists of an early phase where parasite abundance decreases during the transition from gametocyte to oocyst, an intermediate phase where parasite abundance remains static as oocysts, and a later phase where parasite abundance increases during the release of progeny sporozoites from oocysts. Sporogonic development is complete when sporozoites invade the mosquito salivary glands. The dynamics and efficiency of this developmental sequence were determined in laboratory strains of Anopheles dirus, Anopheles minimus and Anopheles sawadwongporni mosquitoes for Plasmodium vivax parasites circulating naturally in western Thailand. METHODS: Mosquitoes were fed blood from 20 symptomatic Thai adults via membrane feeders. Absolute densities were estimated for macrogametocytes, round stages (= female gametes/zygotes), ookinetes, oocysts, haemolymph sporozoites and salivary gland sporozoites. From these census data, five aspects of population dynamics were analysed; 1) changes in life-stage prevalence during early sporogony, 2) kinetics of life-stage formation, 3) efficiency of life-stage transitions, 4) density relationships between successive life-stages, and 5) parasite aggregation patterns. RESULTS: There was no difference among the three mosquito species tested in total losses incurred by P. vivax populations during early sporogony. Averaged across all infections, parasite populations incurred a 68-fold loss in abundance, with losses of ca. 19-fold, 2-fold and 2-fold at the first (= gametogenesis/fertilization), second (= round stage transformation), and third (= ookinete migration) life-stage transitions, respectively. However, total losses varied widely among infections, ranging from 6-fold to over 2,000-fold loss. Losses during gametogenesis/fertilization accounted for most of this variability, indicating that gametocytes originating from some volunteers were more fertile than those from other volunteers. Although reasons for such variability were not determined, gametocyte fertility was not correlated with blood haematocrit, asexual parasitaemia, gametocyte density or gametocyte sex ratio. Round stages and ookinetes were present in mosquito midguts for up to 48 hours and development was asynchronous. Parasite losses during fertilization and round stage differentiation were more influenced by factors intrinsic to the parasite and/or factors in the blood, whereas ookinete losses were more strongly influenced by mosquito factors. Oocysts released sporozoites on days 12 to 14, but even by day 22 many oocysts were still present on the midgut. The per capita production was estimated to be approximately 500 sporozoites per oocyst and approximately 75% of the sporozoites released into the haemocoel successfully invaded the salivary glands. CONCLUSION: The major developmental bottleneck in early sporogony occurred during the transition from macrogametocyte to round stage. Sporozoite invasion into the salivary glands was very efficient. Information on the natural population dynamics of sporogony within malaria-endemic areas may benefit intervention strategies that target early sporogony (e.g., transmission blocking vaccines, transgenic mosquitoes).

Adult↗
PubMed2000

Non-structural carbohydrate status in Norway spruce buds in the context of annual bud structural development as affected by acidic pollution.

The present study focused on changes in the annual dynamics of the contents of non-structural saccharides (NSS) of Norway spruce vegetative buds related to their structural development under the effect of acidic pollution during the year 1995. Two types of material were analysed: (1) 4-year-old trees treated for 2 years by simulated acid rain (SAR; pH 2.9 and 3.9), and (2) 40-60-year-old trees growing in natural mountain stands exhibiting different degrees of macroscopic damage. Our study revealed that the dynamics of the NSS content reflected the major morphogenetic and developmental changes occurring during the annual bud developmental cycle. No systematic changes in the annual dynamics of NSS content were observed in buds from both mountain sites, or as a consequence of the SAR. The total sugar content of bud tissues was composed of a combination of five main sugar components: sucrose, glucose, fructose, raffinose family oligosaccharides (RFO; combination of raffinose and stachyose), and a pinitol fraction (PF) probably of cyclitols with pinitol as a main member. The dynamics of individual sugar components also reflected possible carbohydrate mediated bud frost protection. Interesting results were obtained from buds in dormant state. In dormant buds of the SAR experiment the higher value of the ratio PF:RFO of the pinitol fraction and raffinose family oligosaccharides followed the higher dose of SAR treatment. When evaluating the ratio from both types of material we assumed that changes in PF:RFO ratio corresponded to early stages of damage or acute metabolic reaction. Thus, we suggest the ratio PF:RFO as a possible non-specific metabolic marker of early bud stress reaction which is, among other stress factors, sensitive to increasing load of acidic pollutants.

Journal Article↗
PubMed1999

A rapid and dynamic regulation of GDNF-family ligands and receptors correlate with the developmental dependency of cutaneous sensory innervation.

Glial cell line-derived neurotrophic factor (GDNF) and neurturin (NTN) are members of the transforming growth factor-beta family and have been shown to elicit neurotrophic effects upon several classes of neurons including dopaminergic neurons, motoneurons, parasympathetic, sympathetic as well as primary sensory neurons. However, there is little information available on their roles in cutaneous innervation. Herein, we have studied the regulation of gdnf, ntn and the GDNF family receptors and examined their role in the development of facial cutaneous innervation in GDNF mutant mice. A dynamic spatial and temporal regulation of gdnf, ntn and their ligand binding receptors within the follicle-sinus complex correlate with development of distinct subclasses of sensory nerve endings. Furthermore, development of NGF-dependent myelinated mechanoreceptors, i.e. reticular and transverse lanceolate endings also require GDNF during ending formation and maintenance. In addition, ligand and receptor association seems to be intricately linked to a local Schwann cell-axon interaction essential for sensory terminal formation. Our results suggests that functionally specified nerve endings depend on different GDNF family members and that in contrast to neurotrophins, this family of neurotrophic factors may be acting at local sites of terminal Schwann cell-axon growth cone interactions and that they collaborate with neurotrophins by supporting the same populations of neurons but at different times in development.

Animals↗
PubMed2004

Using developmental, cognitive, and neuroscience approaches to understand executive control in young children.

The 7 articles in this special issue address the nature of executive control in young children. Executive control is framed in a developmental context, where the unique aspects of cognition in this age range are considered. The set of articles demonstrates the multidisciplinary approaches to study cognition in young children that includes application of cognitive, neuroscience, and developmental paradigms in typically developing youngsters, as well as those affected by clinical conditions, such as traumatic brain injury, exposure to low levels of lead in the environment, and prematurity. Although much work remains to be done, these study results are illustrative of the dynamic work in this exciting developmental period.

Age Factors↗
PubMed2005

Nuclear and cytoplasmic maturation of sow oocytes are not synchronized by specific meiotic inhibition with roscovitine during in vitro maturation.

The effect of roscovitine exposure prior to IVM was studied on cumulus expansion, on changes of cumulus-oocyte contacts and on nuclear and cytoplasmic maturation of sow oocytes. It was hypothesized that delayed nuclear maturation and prolonged contact with cumulus cells allows prolonged cytoplasmic differentiation and therefore improves oocyte developmental potential. Cumulus-oocyte complexes (COCs) were exposed for 22 h or 44 h to 0, 25 or 50 microM of roscovitine and subsequently cultured for 22, 29 or 44 h without roscovitine. COCs were examined for cumulus expansion and oocytes for nuclear status and dynamics of transzonal microfilaments. Oocyte developmental potential was assessed by blastocyst formation after IVF. Fifty muM of roscovitine inhibited cumulus expansion for the first 22 h of culture, and maintained oocytes in meiotic arrest for 44 h. Roscovitine treatment during 22 h prior to culture for 44 h without roscovitine did not increase embryo development, but oocytes cultured for 66 h without roscovitine had reduced blastocyst formation. Oocytes cultured for 29 h after roscovitine exposure showed reduced blastocyst rates compared with their counterparts cultured for 44 h. Roscovitine treatment during 44 h prior to culture for 22 h or 44 h without roscovitine reduced embryo development. Transzonal microfilaments were reduced after culture with roscovitine, and disappeared during culture without roscovitine. It is concluded that prolonged contact with cumulus cells does not improve oocyte developmental potential. Furthermore, it is suggested that nuclear and cytoplasmic maturation in vitro cannot be seen as two independent processes.

Animals↗
PubMed2006

Dynamic of the genetic structure of bacterial and fungal communities at different developmental stages of Medicago truncatula Gaertn. cv. Jemalong line J5.

The genetic structure of bacterial and fungal communities was characterized in the rhizosphere of Medicago truncatula Gaertn. cv. Jemalong line J5 at five developmental stages (three vegetative and two reproductive stages), and in three compartments (bulk soil, rhizosphere soil and root tissues). The genetic structure of microbial communities was determined by cultivation-independent methods using directly extracted DNA that was characterized by automated ribosomal intergenic spacer analysis (ARISA). Principal component analyses (PCA) indicate that, for all developmental stages, the genetic structure of microbial communities differed significantly by compartment, with a major shift in the community in root tissues corresponding to the most intimate compartment with the plant. Differences were also recorded during plant development, the most significant being observed during the transition between vegetative and reproductive stages. Throughout this period, plants were shown to establish the highest level of symbiotic association (mycorrhization, nodulation) with arbuscular mycorrhizal fungi and Rhizobia. During the reproductive stages, the dynamics of the genetic structure differed between bacterial and fungal communities. At the last reproductive stage, the genetic structure of bacterial communities became close to that recorded during the first vegetative stages, suggesting a resilience phenomenon, whereas the genetic structure of fungal communities remained different from the vegetative stages and also from the early reproductive stages, suggesting a persistence of the rhizosphere effect.

Bacteria↗
PubMed2006

Gene regulatory network models for plant development.

Accumulated genetic data are stimulating the use of mathematical and computational tools for studying the concerted action of genes during cell differentiation and morphogenetic processes. At the same time, network theory has flourished, enabling analyses of complex systems that have multiple elements and interactions. Reverse engineering methods that use genomic data or detailed experiments on gene interactions have been used to propose gene network architectures. Experiments on gene interactions incorporate enough detail for relatively small developmental modules and thus allow dynamical analyses that have direct functional interpretations. Generalities are beginning to emerge. For example, biological genetic networks are robust to environmental and genetic perturbations. Such dynamical studies also enable novel predictions that can lead to further experimental tests, which might then feedback to the theoretical analyses. This interplay is proving productive for understanding plant development. Finally, both experiments on gene interactions and theoretical analyses allow the identification of frequent or fixed evolutionary solutions to developmental problems, and thus are contributing to an understanding of the genetic basis of the evolution of development and body plan.

Biological Evolution↗
PubMed2005

Ribosomal DNA heterochromatin in plants.

The aim of this review is to integrate earlier results and recent findings to present the current state-of-the-art vision concerning the dynamic behavior of the ribosomal DNA (rDNA) fraction in plants. The global organization and behavioral features of rDNA make it a most useful system to analyse the relationship between chromatin topology and gene expression patterns. Correlations between several heterochromatin fractions and rDNA arrays demonstrate the heterochromatic nature of the rDNA and reveal the importance of the genomic environment and of developmental controls in modulating its dynamics.

DNA, Plant↗
PubMed1997

Abstract genetic representation of dynamical neural networks using Kauffman networks.

Abstract (developmental) genetic representations are schemes where each genotype encodes a program for the construction of a phenotype. A new method for contriving abstract genetic representations is presented, based upon Kauffman's ideas regarding biological development [13-16]. Phenogenesis is controlled by genotype via cell replication and differentiation. Comparison is made with the earlier published methods of Gruau [9] and Kitano [18]. It is argued that greater expressive power is obtained using Kauffman networks. The new method was tested in the artificial evolution of morphology and finally successfully applied to the synthesis of structure in dynamical neural networks.

Evolution, Molecular↗