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PubMed1981

Dietary modulation in cancer prevention with reference to social and cultural food habits.

Well-documented results of worldwide research on hazardous life-style factors pertaining to harmful food habits can be gainfully employed. They suggest that during pregnancy, lactation, childhood, and adolescence drastic control of oral intake of unessential hazardous food items be advocated for cancer control effective through adulthood. The sensitivity to carcinogenic initiators is shown to be great during growth periods in and out of the womb. During this dynamic developmental stage, criteria for safe levels of intake on an aggregate body weight basis remain indefinite. Unessential pleasure foods containing alcohol, tobacco, betel and related chews, fungal contaminants, nitrosatable ingredients, products of pyrolysis, and certain feed and food additives are cautioned against especially over the restricted growth period and discussed in terms of risk:benefit.

Areca↗
PubMed1995

Immunocytochemical study of the ontogeny of the marsupial Didelphis albiventris immune system.

Marsupials have considerable merits as models for studying the developmental dynamics of the mammalian immune system, but until recently there has been a conspicuous lack of specific immune probes to facilitate such studies. To begin a precise study of the ontogeny of the marsupial Didelphis albiventris we have used cross-reactive polyclonal antibodies raised against evolutionarily highly conserved peptides which form part of the antigen specific receptor complexes of human differentiated lymphocytes. Moreover, because of antigen receptor conservation, the antibodies also recognise specifically the immunocompetent T and B lymphocytes of other species including those in the organs of the opossum. Use of the antipeptide antibodies together with other cross-reacting antibodies has allowed us to study the cellular immunology of T and B cells and antigen presenting cells (APC) during the development of thymus, skin, lymph nodes and spleen in the Brazilian white-belly opossum. The molecular nature and identity of the T cell antigens detected in opossum tissues were confirmed by immunoblotting. These findings indicate that it is now possible to exploit these antibody probes for comparative mammalian studies, and indeed to investigate interesting features of the opossum, such as reaction of the immature immune system of the pouch young to antigenic stimulation.

Animals↗
PubMed1994

[Natural course of mild hip dysplasia from young childhood into adulthood].

For radiometric evaluation of hip development in children, Hilgenreiner's acetabular index is one of the most important parameters. In order to assess the prognostic value of the acetabular index to separate healthy from pathologic hip joints, follow-up studies of untreated mildly dysplastic hips were undertaken. When 48 hips classified as mildly dysplastic at the age of 1-4 years were followed up when the patients were adult, 90% had normal hip scores according to Tönnis, 81% a normal acetabular angle according to Ullmann and 71% a normal acetabular coverage according to Wiberg. From the data presented there is no clear-cut delineation between healthy and pathologic hips during childhood. Therefore, the developmental dynamics of the hip during longer time intervals have to be taken into consideration.

Adult↗
PubMed1993

Diagnosis and treatment of psychiatric and behavioural disorders in mentally retarded individuals: the state of the art.

It is now well known that a higher proportion of people with mental retardation show behavioural and psychiatric disorders compared to their non-mentally retarded counterparts. However, the exact relationship between psychiatric illness and behavioural disorder in this population is far from clear. There are problems of using the standard diagnostic and classification categories in this population, particularly in those who are severely and profoundly mentally retarded. Recently, there have been many novel approaches to this diagnostic dilemma, including 'developmental approach' and 'psychodynamic approach'. In the Netherlands, the so-called 'developmental-dynamic' approach has been used in the diagnosis and treatment of behavioural and psychiatric disorders in the mentally retarded. There have also been many treatment approaches, including drug therapy, behavioural treatment, psychotherapy, cognitive and social learning. Also the Dutch, Swiss and German traditions have extensive experience in the directive pedagogical treatment of the mentally retarded.

Combined Modality Therapy↗
PubMed1993

[Interactions of infants with adults in day care centers. Evolutive dependencies vs. counter-evolutive risks and characteristics of the mother-infant relationship].

As part of a broader research project on the construction of the self, six infants were observed longitudinally in day-care centers between the ages of five months and three years. Interviews were conducted with the six mothers in order to evaluate the intersubjective characteristics of the mother-infant relationship. For three of the six children, the mother was a caregiver in the center. This article deals with "propping" processes, defined as the affective-cognitive transformations by means of which infants develop networks of links with and between external and internal objects which are used for support during development and serve as a relay of the maternal object. The present analysis is limited to propping on the adults in the day-care center (caregivers, observer, and, for three of the children, mothers). Two factors were considered: the intersubjective quality of the mother-infant relation, and the presence or absence of the mother as a caregiver in the day-care center. The results showed that (1) even when very young, the infants under observation differentiated between the various functions of the adults, and adapted their behavior to them; (2) each child exhibited a unique and sometimes very creative way of using dependencies on an adult's psychic apparatus to construct his or her own modes of psychic functioning; and (3) the developmental dynamics and the richness of the observed transformations were found to depend on the quality of the contact and distancing in the mother-infant relationship and on the concrete conditions for its actualization, which can either promote or hinder, and sometimes even block, the construction of the mother's absence.

Adult↗
PubMed1996

Nutrient absorption in the preterm neonate.

The majority of what we know about the development of the absorptive process is derived from animal studies, studies in human fetal or stillborn tissues, and epidemiologic investigations derived from clinical experience. One can readily ascertain from this review that the absorption of nutrients in the intestine of the premature infant relates to a dynamic developmental process in which the consecutive stages are pre-programmed but can also be regulated by environmental factors. An understanding of these factors may lead to therapeutic intervention in premature infants, as has been the case for the developing lung and respiratory distress syndrome. Application of this knowledge to the critically ill premature infant in the intensive care unit will need to proceed cautiously, but it is likely to yield major benefits in terms of decreased short- and long-term morbidity in these highly vulnerable patients.

Animals↗
PubMed1996

[The histogenesis of embryonic neocortical allografts in rats under the action of cyclosporine A].

By means of morphological methods, a study was made of effects of cyclosporin A (Cs A) on developmental dynamics in 15 day old embryo neocortex transplanted into the rat brain. It is shown that Cs A exerts no cytotoxic or cytostatic effects on grafting cells. Differentiation of grafting neuroepithelial cells into neuroblasts, young neurons and neurons in transplants of Cs A-treated rats and control transplants took place at the same time. Mitotic activity of grafting neuroepithelial cells was lower than in developing neocortex in situ; pathological mitotic forms have been described.

Animals↗
PubMed2004

The dynamical consequences of developmental variability and demographic stochasticity for host-parasitoid interactions.

Few age-structured models of species dynamics incorporate variability and uncertainty in population processes. Motivated by laboratory data for an insect and its parasitoid, we investigate whether such assumptions are appropriate when considering the population dynamics of a single species and its interaction with a natural enemy. Specifically, we examine the effects of developmental variability and demographic stochasticity on different types of cyclic dynamics predicted by traditional models. We show that predictions based on the deterministic fixed-development approach are differentially sensitive to variability and noise in key life stages. In particular, we find that the demonstration of half-generation cycles in the single-species model and the multigeneration cycles in the host-parasitoid model are sensitive to the introduction of developmental variability and noise, whereas generation cycles are robust to the intrinsic variability and uncertainty that may be found in nature.

Animals↗
PubMed2000

Complexity of electrocortical dynamics in children: developmental aspects.

Dimensional complexity (DCx) is an EEG measure derived from nonlinear systems theory that can be indicative of the global dynamical complexity of electrocortical activity. This study examined developmental changes in DCx, as well as the effects of cognitive tasks, gender, and brain topography, and compared DCx with traditional spectral power measures. EEG was recorded in three groups of children at mean age of 7.5 (n = 37), 13.8 (n = 42), and 16.4 (n = 56) years at rest and during the performance of verbal and spatial cognitive tasks. DCx measured both at rest and during tasks increased with age. Specific effects of brain topography, condition, and gender became stronger with age, suggesting an increase in structural and functional differentiation of the cortex. Hemispheric asymmetry of DCx recorded during tasks also increased with age, with the task-induced DCx reduction being stronger in the left hemisphere. Gender differences in DCx suggested faster cerebral maturation in girls over late adolescence. Relationships between DCx and spectral power varied as a function of tasks and scalp locations, suggesting that these EEG measures can reflect different aspects of cortical functioning.

Adolescent↗
PubMed1994

The future of dynamic systems models in developmental psychology in the light of the past.

A compact glance at the history and impact of mathematical models in development provides background for predicting the fate of dynamical systems modeling in developmental psychology. Dynamic models are considered and the articles by Thelen and Ulrich (1991) and van Geert (1991) are summarized. Deterministic and probabilistic models are compared and some cautions are presented along with a consideration of forms that can be attained by linear models in comparison to those well known in logistic difference models. Reactions to the research by Rabinowitz, Grant, Howe, and Walsh; Kreindler and Lumsden; and Cooney and Troyer are given, with some concluding remarks on survival of dynamical systems modeling in developmental psychology.

Child↗
PubMed2005

Dynamic changes in developmental gene expression in the basal chordate Ciona intestinalis.

Large-scale expressed sequence tags (EST) analysis was used to demonstrate a number of dynamic changes in the global gene expression profile of the basal chordate Ciona intestinalis over the course of its development. The fertilized egg was found to store a great variety of maternal transcripts and, as development proceeds, the organism expresses a progressively smaller repertoire of genes. In addition, a significant portion of genes involved in embryogenesis were observed to be downregulated during metamorphosis, at which point the adult appears to utilize a different set of genes to form its body. At least 25% of the genes involved in development were found to be used multiple times. This kind of information is essential to form a comprehensive understanding of the overarching expression-control plan by which the basic chordate body is formed.

Age Factors↗
PubMed1999

Developmental transitions and dynamics of the cortical ER of Arabidopsis cells seen with green fluorescent protein.

Arabidopsis thaliana plants were stably transformed with DNA encoding green fluorescent protein and with sequences ensuring retention in the endoplasmic reticulum (ER). Confocal laser scanning microscopy shows fluorescent ER in many cells of seedlings so allowing developmental changes to be documented. The arrangement of the cortical ER changes as cells mature in the hypocotyl and root epidermis. In the root, cells that have completed expansion have reticulate cortical ER resembling the ER described in many previous studies. Expanding cells, however, show extensive perforated sheets of cortical ER which transform quite abruptly into a loose reticulum at the basipetal end of the elongation zone. The reticulum compacts in trichoblasts beginning at sites where root hairs are about to emerge. The compacted form is maintained throughout the hair until growth ceases and the open reticulate form returns. All forms of cortical ER are dynamic and we use a color overlay method to distinguish stable and moving structures in a single composite image. Reticulate ER continuously rearranges its polygonal layout and perforations move and change their shape in the ER sheets of younger cells. ER deeper in the cell (i.e. not close to the plasma membrane) moves more actively so that almost no tubules remain stable even over short periods of less than one minute. The function of the perforated sheets of cortical ER present in growing cells is unknown.

Arabidopsis↗
PubMed2002

Dynamics of a developmental switch: recursive intracellular and intranuclear redistribution of Caenorhabditis elegans POP-1 parallels Wnt-inhibited transcriptional repression.

POP-1, a Tcf/Lef factor, functions throughout Caenorhabditis elegans development as a Wnt-dependent reiterative switch to generate nonequivalent sister cells that are born by anterior-posterior cell divisions. We have observed the interaction between POP-1 and a target gene that it represses as it responds to Wnt signaling. Dynamic observations in living embryos reveal that POP-1 undergoes Wnt-dependent nucleocytoplasmic redistribution immediately following cytokinesis, explaining the differential nuclear POP-1 levels in nonequivalent sister cells. In unsignaled (anterior) but not Wnt-signaled (posterior) sister cells, POP-1 progressively coalesces into subnuclear domains during interphase, coincident with its action as a repressor. While the asymmetric distribution of POP-1 in nonequivalent sisters apparently requires a 124-amino-acid internal domain, neither the HMG box nor beta-catenin interaction domains are required. We find that a transcriptional activator, MED-1, associates in vivo with the end-1 and end-3 target genes in the mesoderm (anterior sister) and in the endoderm (posterior sister) following the asymmetric cell division that subdivides the mesendoderm. However, in the anterior sister, binding of POP-1 to the end-1 and end-3 genes blocks their expression. In vivo, binding of POP-1 to the end-1 and end-3 targets (in the posterior sister) is blocked by Wnt/MAPK signaling. Thus, a Tcf/Lef factor represses transactivation of genes in an unsignaled daughter cell by abrogating the function of a bound activator.

Animals↗
PubMed1986

Developmental potential and dynamic behavior of hematopoietic stem cells.

We have used retrovirus-mediated gene transfer to mark hematopoietic stem cells in vitro and have tracked the fate of these cells after their transplantation into lethally irradiated recipients. Several classes of stem cells are demonstrated, including cells whose progeny completely repopulate all hematopoietic lineages as well as cells that contribute predominantly to certain lineages or to specific anatomical locations. In a majority of recipients, we find that few (1 or 2) stem-cell clones account for the majority of the mature hematopoietic cells. These results coupled with retransplantation studies suggest an in vivo mechanism for the temporal control of stem-cell use. Further studies based on periodic sampling of primary recipients suggest that normal hematopoiesis results from the sequential activation of different stem-cell clones rather than from an averaged contribution of the entire stem-cell pool.

Animals↗
PubMed2007

The dynamic lift of developmental process.

What are the essential properties of human intelligence, currently unparalleled in its power relative to other biological forms and relative to artificial forms of intelligence? We suggest that answering this question depends critically on understanding developmental process. This paper considers three principles potentially essential to building human-like intelligence: the heterogeneity of the component processes, the embedding of development in a social world, and developmental processes that change the cognitive system as a function of the history of soft-assemblies of these heterogeneous processes in specific tasks. The paper uses examples from human development and from developmental robotics to show how these processes also may underlie biological intelligence and enable us to generate more advanced forms of artificial intelligence.

Brain↗
PubMed1996

Developmental changes in calcium dynamics, protein kinase C distribution and endoplasmic reticulum organization in human preimplantation embryos.

Developmental changes in the Ca2+ dynamics of human zygotes and preimplantation embryos were related to changes in the distribution of endoplasmic reticulum (ER) and protein kinase C (PKC). The fertilization-induced Ca2+ oscillations were typically observed over > 5 h, were ryanodine-sensitive and showed a periphery-to-centre propagation of Ca2+ waves. At the same time, ER and PKC were accumulated in the cell periphery. After the appearance of pronuclei, ryanodine-sensitive Ca2+ oscillations of lower amplitude and frequency were observed until the pronuclear breakdown. However, Ca2+ waves then began in the perinuclear region, in the area of ER and PKC accumulation and spread towards the cell periphery. During the second to fourth cell cycle, small sinusoidal Ca2+ fluctuations were observed; sparse higher-amplitude Ca2+ spikes, superimposed on these basal fluctuations, appeared shortly before cell division. The sinusoidal Ca2+ fluctuations were asynchronous in individual blastomeres and disappeared progressively in arrested embryos. The direction of Ca2+ wave propagation and the distribution of ER and PKC were similar to the situation observed in pronuclear zygotes. In contrast to the zygotes, ryanodine did not arrest the Ca2+ oscillations but augmented their amplitude and frequency. These data suggest that human pre-embryos use different mechanisms of Ca2+ signalling in the early post-fertilization period, during the pronuclear development and during cleavage.

Calcium↗
PubMed2003

Dynamic systems methods for models of developmental psychopathology.

A survey of dynamic systems (DS) methods appropriate for testing systems-based models in developmental psychopathology is provided. The rationale for developing new methods for the field is reviewed first. In line with other scholars, we highlight the fundamental incompatibility between developmentalists' organismic, open systems models and the mechanistic research methods with which these models are tested. Key DS principles are explained and their commensurability with developmental psychopathologists' core theoretical concerns are discussed. Next, a survey of research designs and methodological techniques currently being used and refined by developmental DS researchers is provided. The strengths and limitations of each approach are discussed throughout this review. Finally, we elaborate on one specific dynamic systems method, state space grids, which addresses many of the limitations of previous DS techniques and may prove most useful for the discipline. This approach was developed as a middle road between DS methods that are mathematically heavy on the one hand and purely descriptive on the other. Examples of developmental and clinical studies that have applied state space grids are reviewed and suggestions for future analyses are made. We conclude with some implications for the application of this new methodology for studying change processes in clinical research.

Child↗
PubMed2005

Developmental role of static, dynamic, and contextual cues in speech perception.

The purpose of the current study was to examine the role of syllable duration context as well as static and dynamic acoustic properties in child and adult speech perception. Ten adults and eleven 4-5-year-old children identified a syllable as [ba] or [wa] (stop-glide contrast) in 3 conditions differing in synthetic continua. The 1st condition tested the potential existence of the syllable duration effect in young children, whereas the 2nd and 3rd conditions examined the developmental role of static and dynamic cues, respectively, as related to syllable duration context effects. In the 1st condition, the 1st and 2nd formant transition duration of stimuli varied from those appropriate for [ba] to those appropriate for [wa]. For the 2nd condition, a static burst was added to Condition 1 stimuli. For the 3rd condition, the dynamic transition frequency and transition duration for the first 3 formants varied as appropriate for [ba] and [wa]. In each condition, 3 syllable context durations of 105 ms, 170 ms, and 315 ms were tested. The results indicated that syllable duration context effects were present across all conditions for both adults and children. However, the adults and children did differ in the 3rd condition, in which both the transition frequency and the transition duration were altered. Thus, children used the dynamic formant transitions differently than adults when transition frequency was varied along with transition duration. These findings show that children have a bias toward formant transitions and indicate that young children of 4-5 years of age attend differently than adults to changes in dynamic cues such as formant transitions, as predicted by the developmental cue weighting shift model.

Adult↗