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Effects of 2,3,7,8-tetrachloro-dibenzo-p-dioxin on the extracellular matrix of the thymus in juvenile marmosets (Callithrix jacchus).

2,3,7,8-Tetrachloro-dibenzo-p-dioxin (TCDD) is an ubiquitously distributed xenobiotic. It has been postulated that the effects of TCDD on T-lymphocytes are mediated by modulation of the thymic microenvironment. There is growing evidence of a modified interplay between thymocytes and thymic epithelium related to changes in extracellular matrix (ECM) proteins. Eighteen male marmosets (Callithrix jacchus) were treated with single subcutaneous TCDD doses (1, 10, 100 ng/kg body weight) or vehicle and sacrificed 2 or 4 weeks thereafter. Thymus samples were stained with fluorescein isothiocyanate-conjugated antibodies for ECM proteins and examined immunohistochemically by semi-quantitative image analysis. Thymus samples of animals treated with 1 and 10 ng/kg were additionally analysed by Western blotting for ECM proteins, transforming growth factor-beta(1) (TGF-beta(1)) and integrin chain content (CD49a, CD49e, CD49f and CD29). Monkeys showed no overt signs of toxicity after TCDD treatment. Immunohistochemistry revealed an increase of ECM proteins at 100 ng/kg after 2 and 4 weeks. Western blotting confirmed immunohistochemistry showing a dose-dependent increase of several ECM proteins in animals treated with the lower TCDD doses of 1 and 10 ng/kg. Additionally, dose-dependent increases were observed in integrin chain and TGF-beta(1) contents. We demonstrated changes of thymic ECM in marmosets following low single TCDD doses. Combined with altered integrin expression and enhanced TGF-beta(1) stimulation our findings suggest a modified interplay between thymic epithelium and thymocytes. The extracellular matrix may play a more central role in mediating adverse effects of TCDD in organs than yet acknowledged.

Animals↗

Scalable screening of ternary-code DNA methylation dynamics associated with human traits.

Epigenome-wide association studies (EWASs) are transforming our understanding of the interplay between epigenetics and complex human traits. We introduce the methylation screening array (MSA) to enable scalable and quantitative screening of trait-associated DNA cytosine modifications in large human populations. The MSA integrates EWASs and cell-type-linked methylation signatures, covering diverse traits and diseases. Using the MSA to profile the ternary-code DNA methylations-dissecting 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), and unmodified cytosine-revealed a previously unappreciated role of 5hmC in mediating human trait associations and epigenetic clocks. We demonstrated that 5hmCs complement 5mCs in defining epigenetic cell identities. In-depth analyses highlighted the cell-type context of EWAS and genome-wide association study (GWAS) hits. Targeting aging, we uncovered shared and tissue-specific 5hmC aging dynamics and tissue-specific rates of mitotic hyper- and hypomethylation. These findings chart a landscape of the complex interplay of the two forms of cytosine modifications in diverse human tissues and their roles in health and disease.

Humans↗

Sex and myocardial infarction: an epidemiologic perspective.

The relation between sexual activity and acute myocardial infarction (MI) risk is one of great interest to people at risk for MI and their physicians. However, understanding this relation requires an appreciation of the complex interplay among relative, attributable, and absolute risk. Because there is an underlying risk of MI in the population, the risk of MI after sexual activity must be compared with this underlying baseline risk. The estimated relative risk of MI after sexual activity is approximately 2.5 during the 2-hour period after sex, indicating a 2.5-fold increase in risk over baseline. However, because the baseline risk during any 2-hour period is very low, the absolute increase in risk (the risk from sexual activity minus the baseline risk), is extremely small (e.g., 0.01% over a year for low-risk individuals engaging in weekly sexual activity and 0.1% for higher-risk individuals). In addition, the attributable risk (the percentage of MIs due to sexual activity) is <1%. Thus, any individual's risk of MI during sexual activity is low. Nonetheless, factors that may decrease the risk of MI after sexual activity are important to explore, and include regular exercise and perhaps medication use, such as aspirin and beta blockers. Although there may be a long-term cardiovascular and mortality benefit to regular sexual activity, current data supporting this theory are limited. This article describes the relation between sexual activity and acute MI with respect to the complex interplay among relative, attributable, and absolute risk. Limitations of studies examining the potential long-term benefits of regular sexual activity are also discussed.

Adult↗

Effect of luminal and extravesicular Ca2+ on NAADP binding and release properties.

Nicotinic acid adenine dinucleotide phosphate (NAADP) has been shown to be a powerful Ca2+ release agent in numerous systems, including echinoderms, plants, and mammalian cells. NAADP has been shown to release Ca2+ via a separate mechanism to IP3 and ryanodine receptors, and specific binding sites have recently been characterised. However, functional studies have shown that there is a functional interplay between the NAADP-sensitive mechanism and the other two. In particular, it appears that activation of the NAADP receptor might act as a trigger to facilitate responses from IP3 and ryanodine receptors. To further characterise this interplay, we have investigated the effects of luminal and cytosolic Ca2+ on the NAADP receptor in sea urchin egg homogenates. We report that neither cytosolic nor luminal Ca2+ appears to influence NAADP binding. Conversely, emptying of stores significantly amplifies NAADP-induced fractional Ca2+-release, providing a mechanism of self-adjustment independent of store loading.

Animals↗

Effects of phorbol ester and dexamethasone treatment on histidine decarboxylase and ornithine decarboxylase in basophilic cells.

Both histamine and polyamines are important for maintaining basophilic cell function and viability. The synthesis of these biogenic amines is regulated by histidine decarboxylase and ornithine decarboxylase, respectively. In other mammalian tissues, an interplay between histamine and polyamine metabolisms has been suspected. In this report, the interplay between histamine and ornithine-derived polyamines was studied in a non-transformed mouse mast cell line (C57.1) treated with phorbol ester and dexamethasone, a treatment previously used to increase histidine decarboxylase expression in mastocytoma and basophilic leukemia. Treatment with phorbol ester and dexamethasone increased histidine decarboxylase expression and intracellular histamine levels in C57.1 mast cells to a greater extent than those found for other transformed basophilic models. The treatment also induced a reduction in ornithine decarboxylase expression, intracellular polyamine contents, and cell proliferation. These results indicate that the treatment induces a co-ordinate response of polyamine metabolism and proliferation in mast cells and other immune-related cells. The decrease in the proliferative capacity of mast cells caused by phorbol ester and dexamethasone was simultaneous to an increase in histamine production. Our results, together with those reported by other groups working with polyamine-treated mast cells, indicate an antagonism between histamine and polyamines in basophilic cells.

Animals↗

The role of sex hormones in psychopathology: focus on schizophrenia.

The example of schizophrenia is used to illustrate how sex hormones affect the presentation of illness and its treatment. Organization and activation effects of hormones are explained, and behavior is shown to result from a complex interplay of hormones, brain mechanisms, and social pressures. Sex differences in schizophrenia (in onset age, symptoms, antipsychotic, and other treatment) are consequences of this interplay and impact on the clinician's ability to diagnose, treat, prognosticate, and prevent the disability and distress of schizophrenia.

Antipsychotic Agents↗

Conserved cAMP responsive element and core promoter complex are critical for specificity of the distal T-cell receptor beta chain enhancer for its native promoter.

The Vbeta 8.1 promoter is regulated by T-cell-specific and ubiquitous transcription factors, which bind immediately upstream of and inside the core promoter region. The various Vbeta promoters contain two conserved elements, a cAMP responsive element (CRE) located upstream of the core promoter and a basal initiator flanked by two regulatory motifs. Here we have studied the interplay between the distal enhancer and its native promoter. We show that the remote enhancer acts specifically through its native promoter. Specific enhancer-promoter interplay is mediated through the conserved regions of the Vbeta promoters. Importantly, the conserved CRE serves as a functional recognition element for the enhancer whereas it barely contributes to promoter activity. The other conserved regions surrounding the initiation site are critical for activators that bind at and function through the core promoter region and thereby regulate both promoter and enhancer activity. The enhancer is highly sensitive to E1A-12S, which represses both general and specific enhancer activities. Enhancer activity and promoter-enhancer specificity is, at least in part, mediated by the coactivators CBP/p300.

Adenovirus E1A Proteins↗

The two by two diagram: a graphical truth table.

The two by two table is widely used in statistics, and in particular in the medical literature, to present the results of experimental and clinical studies in which two different operators (such as a reference standard and a new diagnostic test) sort a sample into two groups. The four cells of the table reflect the four possible categories of results. Despite the simplicity of the table, the interplay of its contents is surprisingly complex, and description of this interplay can be confusing if rendered with the conventional descriptive terms alone, such as sensitivity and predictive value. We present a graphical transformation of the table, comprised of a rectangular box in a special coordinate system. This diagram is offered as a flexible and subtle conceptual tool to help physicians, authors, and students to understand, plan, and present clinical research studies.

Data Display↗

Mesoderm-determining transcription in Drosophila is alleviated by mutations in TAF(II)60 and TAF(II)110.

In Drosophila, a coordinate interplay between the Rel transcription factor Dorsal and the basic Helix-Loop-Helix transcription factor Twist initiates mesoderm formation by activating the zygotic expression of mesoderm-determining genes. Here, we show that TBP-associated-factors (TAF(II)s) within the basal transcription factor TFIID mediate transcriptional activation by Dorsal and Twist. Dorsal interacts with TAF(II)110 and TAF(II)60, while Twist contacts TAF(II)110. The TAF(II):activator interactions mediate simple and synergistic transactivation by Dorsal and Twist in vitro. Mutations in TAF(II)60 or TAF(II)110 alleviate the transcription of Dorsal and Twist target genes. Gene dosage assays imply that an interplay of Dorsal and Twist with TAF(II)110 is critically required for the activation of mesoderm-determining gene expression in the Drosophila embryo. The results provide evidence that TAF(II)-subunits within the TFIID complex play an important role during the molecular events leading to initiation of mesoderm formation in Drosophila.

Animals↗

Cell-cell adhesion and signalling.

Signalling pathways activated by Rho small GTPases have recently been identified that coordinate junction assembly, stability and function, as well as interactions of adhesive complexes with the underlying cortical cytoskeleton. Particularly exciting is the interplay between adherens junctions, activation of Rho proteins and the dynamics of microtubule, actin and intermediate filaments. This interplay has important implications for functional regulation of cell-cell adhesion, and points to a more integrated view of signalling processes.

Actins↗

You Wnt some, you lose some: oncogenes in the Wnt signaling pathway.

The highly regulated Wnt signaling cascade plays a decisive role during embryonic patterning and cell-fate determination. The inappropriate expression of Wnt target genes, resulting from deregulation of this pathway, is also implicated in tumorigenesis. Thus, regulation of this pathway is of paramount importance. The Wnt signals are extracellularly regulated by a diverse group of antagonists, cofactors and coreceptors. In the cytoplasm, beta-catenin, a key effector of the Wnt signaling cascade, is highly regulated by a large and fascinating complex of proteins. In the nucleus, activation of target genes is regulated by a complex interplay of activators, repressors and other proteins. Recently, new factors in this pathway have been identified and the interplay and mechanisms of action of key players have been better characterized. Collectively, this represents an important step forward in our understanding of the role of Wnt signaling in development and oncogenesis.

Animals↗

STAT3 is required for Flt3L-dependent dendritic cell differentiation.

The signals that control decisions of progenitor commitment involve the interplay of both cytokines and transcription factors. Flt3L has emerged as a potential regulator of dendritic cell (DC) development, but regulation of HSC commitment to the DC lineage remains poorly understood. Our central finding is the identification of STAT3 activation as a checkpoint of Flt3L-regulated DC development. Deletion of STAT3 caused profound deficiency in the DC compartment and abrogated Flt3L effects on DC development. DC derivation by Flt3L revealed a normal HSC pool, a 2- to 3-fold accumulation of CLP/CMP, but absence of common DC precursors as well as their DC progeny in STAT3-deficient mice. The formation of CMP and CLP represents the first decisive lineage commitment step, and in this regard we provide evidence that commitments of CLP/CMP to the DC lineage strictly depend on the interplay of both Flt3L and STAT3 activation.

Animals↗

Theory on the evolutionary history of lamprey metamorphosis: role of reproductive and thyroid axes.

Metamorphosis is a developmental strategy used by only a small number of extant fishes and little is known about its phylogenetic development during the evolution history of this large group of vertebrates. The present report provides a putative evolutionary history of metamorphosis in the lamprey, an extant agnathan with direct descendancy from some of the oldest known vertebrates. The study reviews recent data on the role of the thyroid gland and its hormones in metamorphosis, summarizes some recent views on the evolution of the endostyle/follicular thyroid in lampreys, and provides new data on the content of two gonadotropin-releasing hormones (GnRH-I and -III) in brain during goitrogen-stimulated, precocious metamorphosis. These new data support an earlier viewpoint of a relationship between thyroid and reproductive axes during metamorphosis. It is proposed that the earliest lampreys were paedomorphic larvae and they lived in a marine environment; as such, they resembled in many ways the larvae from which the ancient protochordates, Larvacea, are derived. The iodide-concentrating efficiency of the endostyle was a critical factor in the evolution of metamorphosis and this gland was replaced by a follicular thyroid, for postmetamorphic animals needed to store iodine following their invasion of freshwater. Larval growth and postmetamorphic reproduction in freshwater became fixtures in the lamprey life cycle; a non-parasitic adult life-history type appeared later. The presence among extant lampreys of two different adult life-history types, and examples of the lability of the timing of sexual maturation in some species, imply that there has been a complex interplay between the thyroid and reproductive axes during the evolution of metamorphosis in lampreys. This proposal is consistent with what we know of interplay of these axes in extant adult lampreys and with the long-held viewpoint that thyroid function and sexual maturation are an association with an ancient history.

Animals↗

A dynamic structural model for estrogen receptor-alpha activation by ligands, emphasizing the role of interactions between distant A and E domains.

The functional interplay between different domains of estrogen receptor-alpha (ERalpha, NR3A1) is responsible for the overall properties of the full-length protein. We previously identified an interaction between the N-terminal A and C-terminal domains, which we demonstrate here to repress ligand-independent transactivation and transrepression abilities of ERalpha. Using targeted mutations based on ERalpha structural models, we determine the basis for this interaction that defines a regulatory interplay between ERalpha A domain, corepressors, and ERalpha Helix 12 for binding to the same C-terminal surface. We propose a dynamic model where binding of different ligands influences the A/D-F domain interaction and results in specific functional outcomes. This model gives insights into the dynamic properties of full-length ERalpha and into the structure of unliganded ERalpha.

Amino Acid Sequence↗

All I need is the air that I breath: outdoor air quality and asthma.

In recent years, developing insight into the pathophysiology of asthma and advances in asthma management have been substantial. Despite these advancements, asthma remains a significant health problem in the paediatric population. In the USA, the prevalence of asthma in children under 18 years of age is estimated at 7% [US Environmental Health Protection Agency. Publication # EPA-100-r-018. Washington, DC, 2000]. Prevalence rates in various subpopulations, particularly African and Hispanic Americans, are much higher. Certain inner-city census tracts have estimated prevalence rates of 20 to 25% [ Crain EF Weiss KP, Stein REK. Pediatric 1994; 94: 356-362]. Many of these subpopulations experience alarmingly disparate and apparently increasing morbidity and mortality associated with asthma. Similar trends in prevalence and morbidity have been observed in urban populations outside the USA as well [Sears MR. Lancet 1997; 350: 1015-1020]. There is considerable controversy as to the scientific basis for these observed trends. While the identification of a single factor or even a closely related group of factors appears unlikely, there is considerable speculation about the role of environmental factors, particularly outdoor air quality. In the USA, the National Ambient Air Quality Standards (NAAQs) offer specific standards for air quality. These standards are applied to certain criteria pollutants, including ozone, particulate matter (both PM(10) and PM(2.5)), sulfur dioxide, nitrogen dioxide, lead and carbon monoxide [ Committee on Environmental Health, AAP. In: Handbook of Pediatric Environmental Health. Elk Grove Village, IL, 1999; 181-191]. The NAAQs were recently revised for both ozone and particulate matter based on data that suggested health risks existed at levels below those set forth in the previous standards. Monitoring data reveals that urban populations are more likely to be exposed to elevated levels of these pollutants [Dickey JH. Disease Monitor 2000; 46(9): 566-589]. Children are uniquely predisposed to the potential harmful effects of these pollutants. This predisposition is related to unique physiologic, anatomic and behavioural characteristics of the infant, child and adolescent. There is compelling evidence that an interplay of genetic predisposition and environmental exposure to a number of chemical and infectious agents may be operative in both the inception and persistence of the clinical asthma phenotype. The relative role of the criteria air pollutants in this interplay is the subject of considerable study. The potential value of intervention by regulatory agencies or by behavioural modification among individuals or communities should be explored. At the very least, the current data offers implications for situational strategies of asthma management based on local monitoring data.

Air Pollutants↗

The Social, Genetic and Developmental Psychiatry Centre: its origins, conception and initial accomplishments.

BACKGROUND: The Social, Genetic and Developmental Psychiatry Centre was established by the Medical Research Council, in partnership with the Institute of Psychiatry, King's College London, in 1994. METHOD AND RESULTS: The paper describes the origins of the Centre; the reasons why a new initiative was needed in the early 1990s; the thinking that led to the proposal for a major interdisciplinary research centre that integrated social, genetic and developmental research perspectives; the approach to international recruitment of world leaders; and the initial research accomplishments with respect to the basic goal of understanding nature-nurture interplay. CONCLUSIONS: The structure and interdisciplinary approach of the Centre have proved a success and the initial accomplishments have begun to meet the objectives of showing how nature-nurture interplay is involved in the development of psychiatric disorders.

Child Psychiatry↗

Complex genetic and environmental relationships between psychological distress, fatigue and immune functioning: a twin study.

BACKGROUND: Although there is considerable support for adverse relationships between states of psychological and somatic distress and immune response, there is little evidence in humans of the relative contribution of genetic and environmental factors. METHODS: This study utilized a twin methodology to examine the interplay between psychological distress, fatigue and immune function. We recorded a number of measures of distress, including conventional depression and anxiety as well as the somatic symptom of prolonged fatigue, and immune responsiveness (by delayed-type hypersensitivity skin response) in 124 normal adult twin pairs (79 monozygotic, 45 dizygotic). RESULTS: While there were strong genetic influences on the psychological distress and fatigue factors (only some of which are common to both), familial aggregation of immune responsiveness arose mainly from environmental factors shared by both members of a twin pair. Phenotypic correlations between psychological and immune measures were negligible, but multivariate genetic modelling revealed that these masked larger genetic and environmental correlations of opposite sign. Negative environmental effects of psychological distress and fatigue on immune responsiveness were countered by a positive genetic relationship between psychological distress and immune function. CONCLUSIONS: Our study suggests that current psychoneuroimmunological hypotheses in humans need to be modified to place increasing importance on the individual's genotype. In this cohort immune responsiveness varied in response to a complex interplay of genetic and environmental factors. Additionally, although psychological distress and fatigue had some shared genetic determinants, independent genetic and environmental risk factors for fatigue were also identified.

Adult↗

Effect of oxidation rate on cross-linking of mussel adhesive proteins.

The cross-linking behavior of mussel adhesive protein Mefp-1 was studied by measuring the rate of aggregation of the protein by photon correlation spectroscopy. To be able to calculate the aggregation numbers, the hydrodynamic radius of monomer Mefp-1 (10 nm) was determined under reducing conditions. The aggregation is controlled by the redox potential of the solution, and the aggregation number varied, independent of pH, over a factor 2 within the experimentally accessible redox potential window. A kinetic model for cross-linking, based on the intricate interplay of the oxidation and auto-oxidation of the hydroquinones of Mefp-1, is proposed. The oxidation rate strongly depends on redox potential. The cross-linking rate is taken to be proportional to the rate of auto-oxidation. The model correctly predicts the experimentally observed phenomena. When the oxidation rate is slower than the auto-oxidation rate, cross-linking is efficient and controlled by the oxidation rate. When the rate of auto-oxidation rate is slower than the oxidation rate, the cross-linking is inefficient due to the quick exhaustion of the hydroquinones. The experimentally determined rate constant for cross-linking is found to be much smaller than those found for auto-oxidation of hydroquinones because of the excluded volume interactions imposed by the protein backbone. Tuning the interplay between oxidation and auto-oxidation presents the potential of controlling cross-linking density independent of the density of reactive groups.

Animals↗