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At least 1,621 records · Page 90Linked to original sources
PubMed2002

Molecular cloning of porcine estrogen receptor-beta complementary DNAs and developmental expression in periimplantation embryos.

In the pig, estrogens transiently produced by embryos and progestins of maternal origin target the uterine endometrium, causing alterations in gene expression and secretory activity, both of which are important for the initiation of embryo attachment. The potential direct embryotrophic roles of estrogens and progestins are, however, unknown. Here we report the cloning of porcine embryonic estrogen receptor-beta (ER-beta) mRNA by reverse transcription-polymerase chain reaction (RT-PCR) using specific primer sets designed initially within conserved regions of human and bovine ER-beta mRNAs, and subsequently within regions of identified porcine ER-beta cDNA sequences. The ER-beta mRNA has an open reading frame of 1578 nucleotides and encodes a 526 amino acid polypeptide that displays greater than 90% identity with other mammalian ER-beta proteins. Northern and Western blot analyses using porcine filamentous embryos from Day 12 of pregnancy demonstrated the presence of multiple ER-beta mRNA transcripts of approximately 9.5, 4.9, and 3.5 kilobases, and a similar 64-kDa protein corresponding in size to human ovarian granulosa cell ER-beta, respectively. In Day 12 filamentous embryos, ER-beta expression was immunolocalized to trophoblastic cell nuclei, coincident with that of proliferative cell nuclear antigen (PCNA). The developmental ontogeny of ER-beta mRNA was evaluated in embryos of different morphologies (spherical, tubular, and filamentous) by semiquantitative RT-PCR, along with those for other steroid hormone receptors (ER-alpha and progesterone receptor) and known embryonic genes associated with cell differentiation (cytochrome P450 aromatase type III) and growth (cyclin D1). ER-beta mRNA levels varied with embryo morphology (filamentous maximum at Day 12), coincident with that of cyclin D1. Progesterone receptor mRNA levels were maximal in tubular embryos, similar to that of P450 aromatase, whereas the expression of the ER-alpha gene was barely detectable and appeared constitutive for all developmental stages examined. Estradiol-17 beta treatment of Day 12 filamentous embryos in culture up-regulated ER-beta and P450 aromatase (type III) mRNA levels, respectively, but decreased those of PCNA, and had no effect on cyclin D1 mRNA levels. These studies taken together suggest that embryonic ER-beta likely mediates the autocrine functions of estrogens in the dynamic regulation of embryonic growth and development at periimplantation.

Amino Acid Sequence↗
PubMed2006

Bacterial artificial chromosome transgenic analysis of dynamic expression patterns of regulator of G-protein signaling 4 during development. I. Cerebral cortex.

Signaling through G-protein-coupled receptors is modulated by a family of regulator of G protein signaling (RGS) proteins that have been implicated in several neurological and psychiatric disorders. Defining the detailed expression patterns and developmental regulation of RGS proteins has been hampered by an absence of antibodies useful for mapping. We have utilized bacterial artificial chromosome (BAC) methods to create transgenic mice that express GFP under the control of endogenous regulator of G-protein signaling 4 (RGS4) enhancer elements. This report focuses on expression patterns in the developing and mature cerebral cortex. Based on reporter distribution, RGS4 is expressed by birth in neurons across all cortical domains, but in different patterns that suggest region- and layer-specific regulation. Peak expression typically occurs before puberty, with complex down-regulation by adulthood. Deep and superficial neurons, in particular, vary in their patterns across developmental age and region and, in primary sensory cortices, layer IV neurons exhibit low or no expression of the GFP reporter. These data suggest that altering RGS4 function will produce a complex neuronal phenotype with cell- and subdomain-specificity in the cerebral cortex.

Aging↗
PubMedDate not supplied

Feeding dynamics: helping children to eat well.

Pediatric nurse practitioners are in a key position to help parents learn to effectively feed their children. Classic research studies, current research and clinical observations on feeding have identified children's capabilities, behaviors, and potential competencies with their eating. An appropriate feeding relationship supports children's developmental tasks at every age and allows them to eat the right amount of the proper food to achieve their genetically determined growth endowment. Children must, in turn, attain developmental tasks. In defining and managing feeding problems, the pediatric nurse practitioner may emphasize prevention by building positive feeding interactions, and promoting early detection and management as well as providing treatment for established problems.

Adolescent↗
PubMed2005

Dynamic regulation of integrin activation by intracellular and extracellular signals controls oligodendrocyte morphology.

BACKGROUND: Myelination requires precise control of oligodendrocyte morphology and myelin generation at each of the axons contacted by an individual cell. This control must involve the integration of extracellular cues, such as those on the axon surface, with intrinsic developmental programmes. We asked whether integrins represent one class of oligodendrocyte cell-surface receptors able to provide this integration. RESULTS: Integrins signal via a process of activation, a conformational change that can be induced either by "outside-in" signals comprising physiological extracellular matrix ligands (mimicked by the pharmacological use of the divalent cation manganese) or "inside-out" signalling molecules such as R-Ras. Increasing levels of outside-in signalling via the laminin receptor alpha6beta1 integrin were found to promote oligodendrocyte processing and myelin sheet formation in culture. Similar results were obtained when inside-out signalling was increased by the expression of a constitutively-active R-Ras. Inhibiting inside-out signalling by using dominant-negative R-Ras reduces processes and myelin sheets; importantly, this can be partially rescued by the co-stimulation of outside-in signalling using manganese. CONCLUSION: The balance of the equilibrium between active and inactive integrins regulates oligodendrocyte morphology, which is itself regulated by extrinsic and intrinsic cues so providing a mechanism of signal integration. As laminins capable of providing outside-in signals are present on axons at the time of myelination, a mechanism exists by which morphology and myelin generation might be regulated independently in each oligodendrocyte process.

Animals↗
PubMed1999

Dynamic changes in mouse hematopoietic stem cell numbers during aging.

To address the fundamental question of whether or not stem cell populations age, we performed quantitative measurements of the cycling status and frequency of hematopoietic stem cells in long-lived C57BL/6 (B6) and short-lived DBA/2 (DBA) mice at different developmental and aging stages. The frequency of cobblestone area-forming cells (CAFC) day-35 in DBA fetal liver was twofold to threefold higher than in B6 mice, and by late gestation, the total stem cell number was nearly as large as that of young DBA adults. Following a further approximately 50% increase in stem cells between 6 weeks and 1 year of age, numbers in old DBA mice dropped precipitously between 12 and 20 months of age. In marked contrast, this stem cell population in B6 mice increased at a constant rate from late gestation to 20 months of age with no signs of abatement. Throughout development an inverse correlation was observed between stem cell numbers and the percentage of cells in S-phase. Because a strong genetic component contributed to the changes in stem cell numbers during aging, we quantified stem cells of 20-month old BXD recombinant inbred (RI) mice, derived from B6 and DBA progenitor strains, thus permitting detailed interstrain genetic analysis. For each BXD strain we calculated the stem cell increase or decrease as mice aged from 2 to 20 months. Net changes in CAFC-day 35 numbers among BXD strains ranged from an approximately 10-fold decrease to an approximately 10-fold increase. A genome-wide search for loci associated with this quantitative trait was performed. Several loci contribute to the trait-putative loci map to chromosomes X, 2, and 14. We conclude that stem cell numbers fluctuate widely during aging and that this has a strong genetic basis.

Aging↗
PubMed2006

Cloning and developmental expression of WSTF during Xenopus laevis embryogenesis.

The gene WSTF is deleted in the autosomal dominant hereditary disorder Williams-Beuren syndrome. This disorder is caused by a 1.3 megabase deletion in human chromosome 7, encompassing at least 17 genes. The WSTF protein contains a bromodomain, found predominantly in chromatin-associated proteins. Reported association of WSTF with chromatin remodeling factors and functional data support a role for WSTF during chromatin remodeling. Here, we report the cloning and developmental expression pattern of Xenopus laevis WSTF. Xenopus laevis WSTF is a protein with a predicted amino acid sequence of 1441 amino acids. Three discrete domains can be identified in the Xenopus laevis WSTF protein, a PHD finger, a DDT domain and a bromodomain. Alignment of Xenopus WSTF with the corresponding orthologues from Homo sapiens, Gallus gallus, Mus musculus and Danio rerio demonstrates an evolutionary conservation of WSTF amino acid sequence and domain organization. In situ hybridization reveals a dynamic expression profile during embryonic development. WSTF is expressed differentially in neural tissue, especially during neurulae stages in the eye, in neural crest cells and the brain.

Amino Acid Sequence↗
PubMed1997

Dynamics of filamentous actin organization in the sea urchin egg cortex during early cleavage divisions: implications for the mechanism of cytokinesis.

We have used confocal laser scanning microscopy in conjunction with BODIPY-phallacidin staining of filamentous actin to investigate changes in the quantity and organization of cortical actin during the first two cell cycles following fertilization in eggs of the sea urchin Strongylocentrotus purpuratus. Quantification of fluorescent phallacidin staining reveals that the amount of filamentous actin (F-actin) in the cortex undergoes cyclical increases and decreases during early cleavage divisions, peaking near the beginning of the cell cycle and decreasing to a minimum at cytokinesis. Changes in the content of cortical F-actin are accompanied by the growth and disappearance of rootlet-like bundles of actin filaments which extend from the bases of microvilli that cover the surface of the egg. Actin rootlets reach their maximum degree of development by 20 min postfertilization, and then gradually decrease in number and length over the next 40 min. Small actin rootlets persist until cleavage, disappear during cytokinesis, and reform following division. The formation of actin rootlets requires cytoplasmic alkalization and is inhibited by cytochalasin D. Cytochalasin D washout experiments demonstrate that assembly of the cortical actin cytoskeleton can be blocked until 5 min before the onset of cleavage and still allow normal cytokinesis. These results illustrate the dynamic nature of cortical actin organization during early development and demonstrate that cytokinesis occurs at the point of minimum cortical F-actin content. They further demonstrate that cytokinesis can occur in embryos in which the normal developmental sequence of changes in cortical actin organization has been blocked by treatment with cytochalasin D, suggesting that these changes do not function in the establishment of the contractile apparatus for cytokinesis, but rather serve other developmental functions. Cell Motil. Cytoskeleton 36:30-42, 1997.

Actins↗
PubMed2004

Cytokinesis monitoring during development; rapid pole-to-pole shuttling of a signaling protein by localized kinase and phosphatase in Caulobacter.

For successful generation of different cell types by asymmetric cell division, cell differentiation should be initiated only after completion of division. Here, we describe a control mechanism by which Caulobacter couples the initiation of a developmental program to the completion of cytokinesis. Genetic evidence indicates that localization of the signaling protein DivK at the flagellated pole prevents premature initiation of development. Photobleaching and FRET experiments show that polar localization of DivK is dynamic with rapid pole-to-pole shuttling of diffusible DivK generated by the localized activities of PleC phosphatase and DivJ kinase at opposite poles. This shuttling is interrupted upon completion of cytokinesis by the segregation of PleC and DivJ to different daughter cells, resulting in disruption of DivK localization at the flagellated pole and subsequent initiation of development in the flagellated progeny. Thus, dynamic polar localization of a diffusible protein provides a control mechanism that monitors cytokinesis to regulate development.

Bacterial Proteins↗
PubMed2002

Phox2 genes - from patterning to connectivity.

In the developing brain, many transcription factors are expressed in complex patterns and dynamics, and drive the differentiation of many classes of neurons. How does the spatio-temporal landscape of transcription factor expression map onto the bewildering variety of neuronal types, and, for each of them, the variety of developmental stages they go through? In other words, what is the logic in the transcriptional control of neuronal differentiation? Here, we review what recent work on the two neuronal-type-specific transcription factors Phox2a and Phox2b has contributed to our understanding of this broad question.

Animals↗
PubMed1995

HIV-positive people, HIV-negative partners.

More relationships exist today between HIV-positive and HIV-negative partners. This article explores the underlying dynamics that might account for this phenomenon. Codependency theories may explain these relationships for some couples. For other couples, it is suggested that positive-negative homosexual relationships may be influenced by both unhealthy and healthy gay developmental experiences as well as by a sense of compassion. The article addresses both HIV-positive people choosing HIV-negative partners and vice versa. Treatment issues for the various theories are discussed and recommendations are made.

Choice Behavior↗
PubMed2000

TCRalpha enhancer activation occurs via a conformational change of a pre-assembled nucleo-protein complex.

The TCR alpha enhancer (Ealpha) has served as a paradigm for studying how enhancers organize trans-activators into nucleo-protein complexes thought to recruit and synergistically stimulate the transcriptional machinery. Little is known, however, of either the extent or dynamics of Ealpha occupancy by nuclear factors during T cell development. Using dimethyl sulfate (DMS) in vivo footprinting, we demonstrate extensive Ealpha occupancy, encompassing both previously identified and novel sites, not only in T cells representing a developmental stage where Ealpha is known to be active (CD4(+)CD8(+)-DP cells), but surprisingly, also in cells at an earlier developmental stage where Ealpha is not active (CD4(-)CD8(-)-DN cells). Partial occupancy was also established in B-lymphoid but not non-lymphoid cells. In vivo DNase I footprinting, however, implied developmentally induced changes in nucleo-protein complex topography. Stage-specific differences in factor composition at Ealpha sequences were also suggested by EMSA analysis. These results, which indicate that alterations in the structure of a pre-assembled nucleo-protein complex correlate with the onset of Ealpha activity, may exemplify one mechanism by which enhancers can rapidly respond to incoming stimuli.

Animals↗
PubMed1986

The concept of character: moral and therapeutic considerations.

This paper discusses the relationship between the psychoanalytic concept of character and the moral considerations of 'character'. Both psychoanalysis (and dynamic psychotherapy) as well as moral philosophy are concerned with judgements of right and wrong. Though psychotherapists take a non-judgemental attitude toward those in treatment, there are implicit judgements based on the expectation of a developmental progression toward 'maturity' and the ability to value actions which go beyond the self. The history of the term character in the psychoanalytic literature is reviewed to show how character is dealt with in psychodynamic psychotherapy as well as the similarity of the concerns of the psychotherapist and the moral philosopher.

Adult↗
PubMed2006

Calcium at fertilization and in early development.

Fertilization calcium waves are introduced, and the evidence from which we can infer general mechanisms of these waves is presented. The two main classes of hypotheses put forward to explain the generation of the fertilization calcium wave are set out, and it is concluded that initiation of the fertilization calcium wave can be most generally explained in invertebrates by a mechanism in which an activating substance enters the egg from the sperm on sperm-egg fusion, activating the egg by stimulating phospholipase C activation through a src family kinase pathway and in mammals by the diffusion of a sperm-specific phospholipase C from sperm to egg on sperm-egg fusion. The fertilization calcium wave is then set into the context of cell cycle control, and the mechanism of repetitive calcium spiking in mammalian eggs is investigated. Evidence that calcium signals control cell division in early embryos is reviewed, and it is concluded that calcium signals are essential at all three stages of cell division in early embryos. Evidence that phosphoinositide signaling pathways control the resumption of meiosis during oocyte maturation is considered. It is concluded on balance that the evidence points to a need for phosphoinositide/calcium signaling during resumption of meiosis. Changes to the calcium signaling machinery occur during meiosis to enable the production of a calcium wave in the mature oocyte when it is fertilized; evidence that the shape and structure of the endoplasmic reticulum alters dynamically during maturation and after fertilization is reviewed, and the link between ER dynamics and the cytoskeleton is discussed. There is evidence that calcium signaling plays a key part in the development of patterning in early embryos. Morphogenesis in ascidian, frog, and zebrafish embryos is briefly described to provide the developmental context in which calcium signals act. Intracellular calcium waves that may play a role in axis formation in ascidian are discussed. Evidence that the Wingless/calcium signaling pathway is a strong ventralizing signal in Xenopus, mediated by phosphoinositide signaling, is adumbrated. The central role that calcium channels play in morphogenetic movements during gastrulation and in ectodermal and mesodermal gene expression during late gastrulation is demonstrated. Experiments in zebrafish provide a strong indication that calcium signals are essential for pattern formation and organogenesis.

Animals↗
PubMed1997

Adolescent sexual offenders: a self-psychological perspective.

Following a request for assistance in formulating a treatment philosophy for adolescent sexual offenders, a qualitative study of seven adolescent offenders was designed with a view to elaborating pre-offense, and post-offense dynamics. The point of departure was the hypothesis that sexual offending had relation to object relations. It was further hypothesized that offenders' object relations and self-development had been disfigured in childhood and adolescent development. The developmental theories of Mahler, Stern, Winnicott, and Kohut were reviewed in order to shed light on the connection between disfigured self-development and sexual offending. Mahler's work suggested that anomalies during the separation-individuation process were heavily implicated. Winnicott's thinking on transitional functioning in potential space and his employment of the concepts of the true self and false self were especially useful. These bodies of work were assimilated to Kohut's theory of self development in which three nuclear sectors of the self, namely, the grandiose-exhibitionistic sector, the idealizing-voyeuristic sector, and the twinship-alterego sector, gradually coalesce and cohere through the moderating influence of parental empathy with the child's developmental tasks. Where such empathy is unforthcoming, or when the normal parental functions are obliterated by traumatic experiences of abuse, unmoderated needs for exhibitionism and voyeurism continue through childhood, adolescence, and adulthood. Victims of sexual offending were hypothesized to perform functions of restoration and preservation of a chronically weak and threatened self. The sample's interview transcripts were qualitatively analyzed and aggregated. Analysis suggested that, indeed, offenses appeared to have been motivated to preserve a weakened sense of self and that the thoughts and perceptions surrounding the offenses resonated with expressions of problematic separation from parental objects. In addition, it was noted that in the post-offense period, offenders had become subject to close supervision, or proctoring, from both formal and informal systems. In close supervision, offenders tended to rapidly crystallize a foreclosed, negative, deviant sexual identity in defense of unmoderated narcissism. Other observations were that intrafamilial offending was consistent with enmeshment in the family, adjudication and apparent treatment readiness, while extrafamilial offending was consistent with exclusion from the family, no adjudication and resistance to treatment.

Adolescent↗
PubMed2002

Locus control regions.

Locus control regions (LCRs) are operationally defined by their ability to enhance the expression of linked genes to physiological levels in a tissue-specific and copy number-dependent manner at ectopic chromatin sites. Although their composition and locations relative to their cognate genes are different, LCRs have been described in a broad spectrum of mammalian gene systems, suggesting that they play an important role in the control of eukaryotic gene expression. The discovery of the LCR in the beta-globin locus and the characterization of LCRs in other loci reinforces the concept that developmental and cell lineage-specific regulation of gene expression relies not on gene-proximal elements such as promoters, enhancers, and silencers exclusively, but also on long-range interactions of various cis regulatory elements and dynamic chromatin alterations.

Acetylation↗
PubMed2006

Magnetic source imaging studies of dyslexia interventions.

Rapidly accumulating evidence from functional brain imaging studies indicates that developmental reading disability is associated with a functional disruption of the brain circuits that normally develop to support reading-related processes. This article briefly overviews recent advances in methods that capture the anatomical outline and temporal (dynamic) features of regional brain activation during performance of reading tasks. One of these methods, magnetoencephalography (MEG) or magnetic sources imaging (MSI) is described in more detail in the context of investigations of changes in spatiotemporal patterns of brain activity associated with improvement in reading skills in response to various types of educational interventions.

Brain Mapping↗
PubMed1993

Clinical pharmacology of Taxol.

Taxol is the first novel antimicrotubule agent approved for clinical use since the vinca alkaloids in the 1960s and may be one of the most important antineoplastic agents to emerge over the last two decades. Significant antitumor activity has been noted in ovarian, breast, lung, and head and neck cancers. This report reviews the clinical pharmacology of Taxol based on early developmental trials of the agent administered on various intravenous schedules as a single agent and in combination with other antineoplastic agents, as well as via the intraperitoneal route. In addition, available information pertaining to the pharmaco-dynamic and metabolic profiles of Taxol are discussed. Such information may be useful in designing rational treatment approaches with Taxol either as monotherapy or in chemotherapy combinations, potentially resulting in the optimal use of this important agent in cancer chemotherapeutics.

Animals↗
PubMed1993

[The effect of recombinant somatotropin hormone on the secretion of ovarian hormones in sexually mature swine in vivo and in vitro].

The development of recombinant somatotropic hormone (STH) creates a prerequisite for a wide application of exogenous stimulation of meat and milk performance of cows and pigs. Reproduction effect and its mechanism is till now restricted by a lack of complex information though there are several studies of principal character and basic effects of STH on reproduction process are also known. The result of some experimental studies, quoted in scientific literature, was a hypothesis that STH effect is accompanied by increased production of so-called insulin-like growth factors. Moreover, it is known that these factors have a steroidogenic effect. A hypothesis of STH action, just by means of insulin-like growth factors, was expressed on the basis of the above mentioned fact. Our study was aimed at the analysis of the effect of recombinant porcine somatotropic hormone (rpSTH, Research and Development, Pittman-Moore, Inc.; Terre Haute, Indiana, the U.S.A., LG-COMP-1776/93) on the dynamics of progesterone, cAMP, cGMP concentrations in the blood plasma of sexually mature gilts with surgically introduced permanent canula in v. jugularis. Gilts of early and medium follicular stages of the oestrous cycle (found laparoscopically) without any developmental or any other anomalies in reproductive organs. Blood samples were collected each 15 minutes in the period of 30 minutes before and 150 minutes after rpSTH application (5 mg per gilt). The control of gilts was administered 0.9% NaCl solution under the same conditions. Blood plasma samples collected and processed were stored not earlier than after radioimmunoassay of substances. A part of the study was to analyze different rpSTH doses (1-100,000 ng/ml) on granulosis cells on gilts' ovaries obtained after slaughtering of sexually mature gilts without any visible changes in the reproductive system. Granulosis cells were separated after aspiration of follicles of the size 2 to 5 mm without marked paleness, after thrice resuspending in essential cultivation medium TCM 199 and centrifugigng (g = 200). Followed the last straining of supernatant the cells were resuspended in the cultivation enriched medium TCM 199. 2 ml of cell suspension in the cultivation medium with known counts and viability of cells (10(6) in 1 ml and 75-95% vitality) were cultivated in defined conditions as a basic unit of the experiment. Resulting concentrations of analyzed hormones were determined on the basis of production activity of cells and statistically assessed by ANOVA test.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗