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PubMedDate not supplied

Effect of position on pulmonary mechanics in healthy preterm newborn infants.

Preterm infants are often placed in the supine position to facilitate care and observation. Prone positioning may positively affect later neurodevelopmental outcome, but it may also affect pulmonary function. Using a computerized system, we examined the effect of positioning on pulmonary mechanics in spontaneously breathing healthy preterm infants. Eleven infants with a mean birth weight (+/- SD) of 1523 +/- 171 gm and a mean gestational age (+/- SD) of 31.7 +/- 1.5 weeks were studied during the first 2 weeks of life. Pulmonary mechanic measurements were obtained in both supine and prone positions by mask pneumotachography and esophageal balloon technique. Respiratory rate and oxygen saturation were unaffected by positioning. There was a statistically, but not clinically, significant increase in heart rate in the prone position. However, there were no significant differences in tidal volume, minute ventilation, pulmonary resistance, or dynamic compliance between positions. The contribution of intrasubject variability of serial measurements was assessed in a separate group of four infants studied three times in the same position. There was no significant difference in respiratory rate, tidal volume, dynamic compliance per kilogram, or total pulmonary resistance in the same infant when studied in the same position over time (p > or = 0.24). The maximum variability (95% confidence limit) was 25.5% for tidal volume, 21% for dynamic compliance, and 44.3% for resistance. Because prone positioning did not adversely affect pulmonary mechanics or oxygen saturation in these healthy preterm infants, we suggest that prone position be used to facilitate the developmental needs of these infants.

Birth Weight↗
PubMed1997

Ion channels in neuroglial cells.

With the advent of the patch clamp technique, many different types of ion channels have been found in neuroglial cells, including voltage-sensitive ion channels (Na+, Ca2+, K+, and CI- channels), ligand-gated ion channels (glutamate receptor and GABAA receptor), and mechanosensitive ion channels. Most of these ion channels have also been found in excitable cells, and thus excitable and non-excitable cells in the nervous system share a similar repertoire of ion channel gene expression. Various factors, such as different developmental stage or different regions in the brain, are known to influence glial ion channel expression. In addition, glial ion channel expression is influenced by the presence of neurons, suggesting the existence of dynamic mechanism(s) for regulating ion channel expression via cell-to-cell signaling between neurons and glia. In this review, the current understanding of various types of ion channels found in neuroglial cells (i.e., astrocytes, oligodendrocytes, and Schwann cells) is summarized.

Animals↗
PubMedDate not supplied

[Epilepsy of the developmental age and control of seizure-releasing factors].

On the basis of an analysis of a paediatric material the author discusses the most important elements influencing the pattern of developmental age epilepsy calling attention to the significance of early aetiological diagnosis since in this early period of life many processes can be treated causatively before epilepsy develops into a chronic disease. The dynamic course of epilepsy and classification difficulties resulting from clinical and electroencephalographic variability of childhood epilepsy are discussed explaining these facts by differences in structural maturity and functional organization at the age of development. It is indispensable to know the classification of seizure circuits for selection of possibly effective symptomatic treatment for prevention of seizures and their sequelae in the neuropsychiatric and social aspects. In the clinical course of a given case there are also individual differences between the seizure-releasing factors and their knowledge helps to avoid the critical threshold of seizure readiness releasing seizures in a given child. Acceptance of certain rules for observation in the everyday life of patients permits an individual prophylaxis of seizures. This shows that prevention of epileptic seizures includes not only causative and symptomatic treatment but also the knowledge of individual seizure-releasing factors which cannot be controlled pharmacologically.

Adolescent↗
PubMed2006

Heterogeneous interspecific interactions in a host-parasite system.

Macroparasites of vertebrates usually occur in multi-species communities, producing infections whose outcome in individual hosts or host populations may depend on the dynamics of interactions amongst the different component species. Within a single co-infection, competition can occur between conspecific and heterospecific parasite individuals, either directly or via the host's physiological and immune responses. We studied a natural single-host, multi-parasite model infection system (polystomes in the anuran Xenopus laevis victorianus) in which the parasite species show total interspecific competitive exclusion as adults in host individuals. Multi-species infection experiments indicated that competitive outcomes were dependent on infection species composition and strongly influenced by the intraspecific genetic identity of the interacting organisms. Our results also demonstrate the special importance of temporal heterogeneity (the sequence of infection by different species) in competition and co-existence between parasite species and predict that developmental plasticity in inferior competitors, and the induction of species-specific host resistance, will partition the within-host-individual habitat over time. We emphasise that such local (within-host) context-dependent processes are likely to be a fundamental determinant of population dynamics in multi-species parasite assemblages.

Animals↗
PubMed1997

Stochastic processes in postural center-of-pressure profiles.

The stochastic processes of postural center-of-pressure profiles were examined in 3- and 5-year-old children, young adult students (mean 20 years), and an elderly age group (mean 67 years). Subjects stood still in an upright bipedal stance on a force platform under vision and nonvision conditions. The time evolutionary properties of the center-of-pressure dynamic were examined using basic stochastic process models. The amount of motion of the center of pressure decreased with increments of age from 3 to 5 years to young adult but increased again in the elderly age group. The availability of vision decreased the amount of motion of the center of pressure in all groups except the 3-year-old group, where there was less motion of the center of pressure with no vision. The stochastic properties of the center-of-pressure dynamic were assessed using both a two-process, random-walk model of Collins and De Luca and an Ornstein-Uhlenbeck model that is linear and has displacement governed only by a single stiffness term in the random walk. The two-process open- and closed-loop model accounted for about 96% and the Ornstein-Uhlenbeck model 92% of the variance of the diffusion term. Diffusion parameters in both models showed that the data were correlated and that they varied with age in a fashion consistent with developmental accounts of the changing regulation of the degrees of freedom in action. The findings suggest that it is premature to consider the trajectory of the center-of-pressure as a two-process, open- and closed-loop random-walk model given that: (a) the linear Ornstein-Uhlenbeck dynamic equation with only two parameters accommodates almost as much of the variance of the random walk; and (b) the linkage of a discontinuity in the diffusion process with the transition of open- to closed-loop processes is poorly founded. It appears that the nature of the stochastic properties of the random walk of the center-of-pressure trajectory in quiet, upright standing remains to be elucidated.

Adult↗
PubMed1998

Computer-generated three-dimensional reconstructions of serially sectioned mouse embryos.

We have been involved with a group of computer scientists and anatomists in the development of computer-based methodologies that not only combine the advantages of scanning electron microscopy and conventional histology, but provide the additional dimension of tissue recognition. The latter is achieved by the appropriate labelling of tissues and structures by delineation or 'painting'. Individually segmented anatomically defined tissues can be highlighted in a particular colour and viewed either in isolation or in combination with other appropriately labelled tissues and organs. Tissues can be shown in any orientation either as a transparent overlay on computer-generated histological sections or as 3-D images without the histological background. An additional feature of the system is that computer graphics technology combined with 3-D glasses now also allows the viewer to see the object under analysis in stereo. This facility has been found to be particularly helpful in drawing attention to topological relationships that had not previously been readily noted. As the mouse is now the mammalian model of choice in many areas of developmental research, it is of critical importance that a basic level of skill is available in the research community in the interpretation of serially sectioned material, for example, for the rapidly expanding field in which gene expression studies play a significant role. It is equally important that there is an understanding of the dynamic changes that occur in relation to the differentiation of the various organ systems seen in these early stages of development. What we emphasise here is the additional information that it is possible to gain from the use of this tool which, in our view, could not readily have been gained from the analysis of scanning electron micrographs or by studying conventional serial histological sections of similar stages of mouse embryonic development. The methodology has been developed as part of a large project to prepare a database of mouse developmental anatomy covering all stages from fertilisation to birth in order to allow the accurate spatial mapping of gene expression and cell lineage data onto the digital Atlas of normal mouse development. In this paper we show how this digital anatomical Atlas also represents a valuable teaching aid and research tool in anatomy.

Anatomy, Cross-Sectional↗
PubMed1999

Expression pattern of the Tbr2 (Eomesodermin) gene during mouse and chick brain development.

The members of the T-box gene family share a highly conserved DNA binding domain named the T-domain, and important developmental functions. Here we report the cloning of chicken Tbr1 and of murine and chicken Tbr2 (orthologs of the Xenopus eomesodermin gene), the mapping of the murine Tbr2 to chromosome 9, and their pattern of expression during mouse and chick embryogenesis. Both Tbr 1 and 2 have a restricted and conserved domain of expression in the telencephalic pallium of the two species. Chick Tbr2 has a specific and dynamic expression in the gastrulating embryo.

Amino Acid Sequence↗
PubMedDate not supplied

[Controversial or arguable therapies in neurodevelopmental disorders].

OBJECTIVE: To analyze the therapies and methods not scientifically documented that more frequently are offer and used for the treatment of neurodevelopmental disorders. DEVELOPMENT: These therapies are divided into three main groups: a) Therapies directed upon brain functioning; b) Therapies directed upon nutritional needs, and c) Others. Parents and close relatives of children with developmental disorders are vulnerable to any person, institution or method that offers a quick and easy solution to their problem. It is a priority that all health professionals are familiar with the unproven therapies, that are offered for the therapy of developmental disorders, so that they can inform, educate and advise correctly to parents and close relatives of their patients. To deal with unproven treatments involves more than analyzing the available scientific data. It is required a comprehension and understanding of the personal and family dynamics in front of a threat of illness or disfunction. CONCLUSION: Responsible and well informed parents in relation to an unproven therapy should be free and have the right to decide whether or not to use a controversial procedure prior to a scientific determination of its validity; they also must keep in mind that at least some procedures, beside of not been useful, could be harmful for the physical, emotional and economical well-being of the patient and/or his family.

Brain↗
PubMed2004

Distinct dynamics and distribution of histone methyl-lysine derivatives in mouse development.

Histone methylation acts as an epigenetic regulator of chromatin activity through the modification of arginine and lysine residues on histones H3 and H4. In the case of lysine, this includes the formation of mono-, di-, or trimethyl groups, each of which is presumed to represent a distinct functional state at the cellular level. To examine the potential developmental roles of these modifications, we determined the global patterns of lysine methylation involving K9 on histone H3 and K20 on histone H4 in midgestation mouse embryos. For each lysine target site, we observed distinct subnuclear distributions of the mono- and trimethyl versions in 10T1/2 cells that were conserved within primary cultures and within the 3D-tissue architecture of the embryo. Interestingly, three of these modifications, histone H3 trimethyl K9, histone H4 monomethyl K20, and histone H4 trimethyl K20 exhibited marked differences in their distribution within the neuroepithelium. Specifically, both histone H3 trimethyl K9 and H4 monomethyl K20 were elevated in proliferating cells of the neural tube, which in the case of the K9 modification was limited to mitotic cells on the luminal surface. In contrast, histone H4 trimethyl K20 was progressively lost from these medial regions and became enriched in differentiating neurons in the ventrolateral neural tube. The inverse relationship of histone H4 K20 methyl derivatives is even more striking during skeletal and cardiac myogenesis where the accumulation of the trimethyl modification in pericentromeric heterochromatin suggests a role in gene silencing in postmitotic muscle cells. Importantly, our results establish that histone lysine methylation occurs in a highly dynamic manner that is consistent with their function in an epigenetic program for cell division and differentiation.

Animals↗
PubMed1993

[Neuropsychological development in children with focal brain injury].

The study of children with focal brain injury has important implications from a clinical and theoretical perspective. Clinical data on children with congenital or early acquired lesions indicates that the cognitive sequelae are different from those resulting from similar damage sustained in adulthood. These differences depend in part on the differential effect that damage has on ongoing developmental process and in part on the different recovery capacity of the Central Nervous System of the child. From a theoretical perspective, focal lesion data is important for analyzing the issues of early neuropsychological functioning (especially in terms of early hemispheric specialization) and of plasticity and recovery of function of the CNS. This review analyzes the possible causes of this heterogeneity, that seems in part dependent on the interindividual variability of early neuropsychological organization and in part related to methodological factors such subject inclusion criteria and nature of neuropsychological measures. The review also discusses the role during development of the principal inter and intrahemispheric recovery mechanisms (special attention is given to intrahemispheric mechanisms which have been considered in the past as less determinant with respect to interhemispheric mechanisms). Furthermore, the role of lesion side as a prognostic parameter is discussed, specifically in terms of the evidence of a differential recovery capacity of left hemisphere with respect to the right. Various hypotheses have been put forward as possible interpretations of these data (maturational gradient, different neuropsychological organization of the two hemispheres), yet evidence is still controversial. If one considers the prognostic parameter--age of lesion onset--recent evidence does not confirm the hypothesis that the earlier the lesion, the greatest the recovery of function. Rather, it seems that relating age of lesion onset to other parameters, such as lesion side or size, has a greater and more reliable prognostic value. Another aim of the review is to analyze the effect that focal damage has on the dynamics of development. The fact that the effects of early damage might manifest themselves later in development, when the function in question is reaching a higher level of organization, underlines the importance of a longitudinal approach that assesses the developmental patterns of specific functions. Another issue discussed is the role of lesion side in determining specific cognitive impairment.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed2002

Visuoperceptual and visuomotor deficits in developmental stutterers: an exploratory study.

Although the cause of stuttering is unknown, there is strong evidence for it being a neuromotor disorder characterised by an abnormality of higher control encompassing not only speech but other motor systems. The aim of this exploratory study was to look for the presence of non-speech/language deficits--in particular, visuomotor and visuoperceptual deficits--in persons who stutter. Twelve moderate to severe developmental stutterers were compared with a group of fluent speakers, matched for age and sex, on a range of computerized sensory-motor tasks. These tasks covered various aspects of visuomotor function--ballistic movement, dynamic steadiness, and several types of tracking--and visuoperceptual function--acuity, static perception, and dynamic perception. A novel technique was used to remove the visuospatial component from tracking performance. Stutterers had slower reaction times, less accurate random tracking, and impaired dynamic visual perception. Severity of stuttering correlated with reaction time and dynamic perception. Removal of the visuoperceptual component from tracking performance indicated that the impaired tracking in the stutterers was predominantly due to reduced dynamic perception. This is the first study to provide preliminary evidence for the presence of non-linguistic visuoperceptual and upper-limb visuomotor tracking deficits in people with moderate to severe stuttering. These findings support a neurogenic aetiology for stuttering and are compatible with evidence of an overactive dopamine system in stutterers.

Adult↗
PubMed1997

Convergence Suppression and Divergence Facilitation: Minimum and Joint Use of Hidden Units by Multiple Outputs.

Pruning of multi-layer neural network structure is not a simple problem if two or more output units are present; unlike the single-output case, removing a hidden-output synaptic link does not necessarily mean elimination of a hidden unit. A new pruning algorithm called CSDF is presented. Its aim is to minimize the total number of active hidden units, thereby making some hidden units utilized jointly by more than one output unit. In addition to the backpropagation (BP) term, two antagonistic actions are introduced for controlling the synaptic development of hidden-output links; the incoming pathways to each output unit try to prevent each other from growing, whereas those outgoing from each hidden unit help each other for growing. CSDF works by dynamically balancing these two lateral interaction effects in the presence of the BP action, and hidden units not indispensable for any output unit will disappear. The process has some parallel with recent findings in developmental neurobiology. The CSDF pruning is applied to some multi-task problems, including one that exemplifies the importance of "structural compatibility" and demonstrates easy discovery of the optimum modular architecture which is difficult to deduce from separate structural optimization for each task alone. In most cases examined here, CSDF outperformed other pruning algorithms such as "weight decay" and "optimum brain damage." In particular, no existing algorithm other than CSDF can deal with pruning of auto-encoders. Some examples are also given for such paradigm of input-output identy mapping. Copyright 1997 Elsevier Science Ltd. All Rights Reserved.

Journal Article↗
PubMed1997

Development-dependent inheritance of 5-azacytidine-induced epimutations in triticale: analysis of rDNA expression patterns.

Genomic imprinting of rye origin rDNA sequences in triticale is modulated by DNA methylation responsible for ontogenic expression patterns of those sequences. Considering the dynamic nature of these phenomena, we evaluated the influence of plant development on the inheritance of modified rye rDNA expression patterns. DNA hypomethylation was induced in triticale by 5-azacytidine (5AC) treatments at distinct developmental stages of M1 plants, and expression patterns were analysed in M2. The activity of rye origin rRNA genes in progeny of untreated and 5AC-treated plants was evaluated by silver staining in meristematic root tip cells and in meiocytes at diplotene. In the progeny of 5AC-treated plants, a significant increase in rye rDNA expression was observed, contrasting with the residual activity in untreated plants. Significant differential effects of 5AC treatments were observed in M2 plants and correlated with the M1 plant developmental stage in which DNA hypomethylation was induced. Hypotheses to explain the origin of those differences are discussed here.

Antimetabolites, Antineoplastic↗
PubMed2006

In silico simulations suggest that Th-cell development is regulated by both selective and instructive mechanisms.

Th-cell differentiation is highly influenced by the local cytokine environment. Although cytokines such as IL-12 and IL-4 are known to polarize the Th-cell response towards Th1 or Th2, respectively, it is not known whether these cytokines instruct the developmental fate of uncommitted Th cells or select cells that have already been committed through a stochastic process. We present an individual based model that accommodates both stochastic and deterministic processes to simulate the dynamic behaviour of selective versus instructive Th-cell development. The predictions made by each model show distinct behaviours, which are compared with experimental observations. The simulations show that the instructive model generates an exclusive Th1 or Th2 response in the absence of an external cytokine source, whereas the selective model favours coexistence of the phenotypes. A hybrid model, including both instructive and selective development, shows behaviour similar to either the selective or the instructive model dependent on the strength of activation. The hybrid model shows the closest qualitative agreement with a number of well-established experimental observations. The predictions by each model suggest that neither pure selective nor instructive Th development is likely to be functional as exclusive mechanisms in Th1/Th2 development.

Animals↗
PubMed2003

Axon guidance by growth cones and branches: common cytoskeletal and signaling mechanisms.

Growing axons are guided to appropriate targets by responses of their motile growth cones to environmental cues. Interstitial axon branching is also an important form of axon guidance in the mammalian CNS. Visualization of growing axons in cortical slices and in dissociated cortical cultures showed that growth cone pausing behaviors demarcate sites of future axon branching. Studies of vertebrate and invertebrate growth cones suggest common mechanisms that regulate growth cone behaviors and axon branching. These include reorganization of the actin and microtubule cytoskeleton, dynamic interactions between microtubules and actin filaments, effects of axon guidance molecules, actions of actin regulatory proteins, and dynamic changes in intracellular calcium signaling. Future challenges will be to extend high-resolution imaging of single neurons to studies of intracellular events in the intact nervous system and to apply knowledge of developmental mechanisms to the promotion of axon sprouting after injury in the adult CNS.

Animals↗
PubMed1978

The case of Ann: a sleep disturbance in a 3-year-old child.

Ann, a 3 1/2-year-old girl, was brought to a pediatric clinic for a chronic, severe sleep disturbance which had precipitated a serious family crisis. A developmental interactional approach was used by the pediatrician and a social worker who evaluated her case; the problem formulation included a reciprocal separation issue between Ann and her mother. Over a 2-month period, dynamic casework around the behavior problem revealed an unresolved grief reaction. Intervention resulted in resolution of the sleep disturbance and an untangling of the relationship between Ann and each of her parents.

Child Behavior↗
PubMed1998

Development of oculomotor functioning in preadolescence, adolescence, and adulthood.

We examined developmental differences in smooth pursuit eye tracking proficiency in a large sample of preadolescent, adolescent, and adult males. Smooth pursuit was quantified using general measures of oculomotor functioning and by examining the frequency and dynamic characteristics of specific saccadic events. Examination of age effects using general measures indicated that, by late adolescence, the smooth pursuit system reached adult levels of functioning. No significant differences were found between the adolescent and adult groups on most global measures. However, both groups had better eye tracking than the preadolescent group, suggesting that during preadolescence the oculomotor system is still developing and is not yet capable of optimal performance. Examination of the frequency and dynamic characteristics of the saccadic events yielded additional information regarding the nature of the smooth pursuit eye tracking differences of the three age groups.

Adolescent↗