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1.
Pediatr Clin North Am ; 69(4): 645-656, 2022 08.
Article in English | MEDLINE | ID: mdl-35934491

ABSTRACT

The rising prevalence of autism spectrum disorder (ASD) calls for clear referral and treatment guidelines for children with ASD and their caregivers. Caregiver involvement in intervention is a standard practice of care and research suggests that teaching intervention strategies to caregivers can improve child outcomes and increase caregiver efficacy. Caregiver-mediated interventions that are naturalistic, developmental, and behavioral are effective in improving social and communication skills for children with ASD. Caregiver training models that use behavioral strategies are effective in reducing challenging behaviors. Finally, reducing caregiver barriers to treatment implementation, including stress and strain, are becoming critical components for improving the well-being and care of children with ASD and their families.


Subject(s)
Autism Spectrum Disorder , Autism Spectrum Disorder/therapy , Caregivers , Child , Family , Humans , Parents
2.
Psychiatr Serv ; 70(11): 1034-1039, 2019 11 01.
Article in English | MEDLINE | ID: mdl-31378192

ABSTRACT

OBJECTIVE: This study investigated equity in enrollment in a Medicaid waiver program for early intensive behavioral intervention for children with autism spectrum disorder (ASD). METHODS: State administrative, Medicaid, and U.S. Census data for children enrolled in the waiver program between 2007 and 2015 (N=2,111) were integrated. Multivariate and bivariate analyses were used to compare enrollees' neighborhood demographic characteristics with those of the state's general population, with controls for enrollees' age, sex, and race-ethnicity. RESULTS: Findings indicate that in general, enrollment was equitable. During the years in which there were inequities, children who lived in neighborhoods of privilege were favored. These neighborhoods had higher median incomes, lower poverty levels, and fewer female-headed households and were located in urban areas. CONCLUSIONS: As states work to provide equitable treatment to children with ASD and their families, it is important to track potential inequities between children who do and do not enroll in services and to use this information to inform outreach efforts. States may turn to South Carolina for insight on how to ensure equity.


Subject(s)
Autism Spectrum Disorder/economics , Autism Spectrum Disorder/therapy , Child Health Services/trends , Healthcare Disparities/statistics & numerical data , Medicaid/trends , Residence Characteristics , State Health Plans/trends , Child , Child, Preschool , Female , Health Services Accessibility , Humans , Male , Multivariate Analysis , Regression Analysis , Socioeconomic Factors , South Carolina , United States
3.
J Autism Dev Disord ; 49(5): 2173-2183, 2019 May.
Article in English | MEDLINE | ID: mdl-30701434

ABSTRACT

Health coverage of early intensive behavioral intervention (EIBI) for children with autism spectrum disorder is expanding. Yet there is no longitudinal research on patterns of or inequities in utilization of EIBI. We integrated state administrative records with Medicaid and Census data for children enrolled in an EIBI Medicaid waiver (N = 730) to identify and describe the type and prevalence of treatment utilization trajectories, and to examine the association between trajectory types and (a) child race-ethnicity and (b) neighborhood racial composition, poverty, affluence, and urbanicity. We identified four utilization trajectories (Low, Low-Moderate, Moderate, and High users). Race-ethnicity and neighborhood affluence were associated with trajectory membership. As coverage expands, policy makers should consider strategies to improve overall treatment utilization and enhance equity.


Subject(s)
Autism Spectrum Disorder/therapy , Ethnicity/statistics & numerical data , Facilities and Services Utilization , Healthcare Disparities , Racial Groups/statistics & numerical data , Residence Characteristics/statistics & numerical data , Adolescent , Autism Spectrum Disorder/rehabilitation , Behavior Therapy/statistics & numerical data , Child , Child, Preschool , Early Intervention, Educational/statistics & numerical data , Female , Humans , Male , Socioeconomic Factors , United States
4.
J Autism Dev Disord ; 48(2): 561-571, 2018 02.
Article in English | MEDLINE | ID: mdl-29080927

ABSTRACT

Health coverage of early intensive behavioral intervention (EIBI) for children with autism spectrum disorder (ASD) is rapidly expanding across the United States. Yet we know little about the time-lag between diagnosis and treatment onset. We integrated administrative, Medicaid claims, and Census data for children in an EIBI Medicaid waiver (n = 473) to examine the relationship between time-lag and (a) child race-ethnicity and (b) neighborhood racial composition, poverty, affluence, and urbanicity. We explored whether the relationship between child race-ethnicity and time-lag varies by neighborhood characteristics. Average time-lag between diagnosis and treatment onset was nearly 3 years. Child race-ethnicity and neighborhood characteristics did not predict time-lag. Reducing time-lag is critical to ensuring that children with ASD receive treatment as early as possible.


Subject(s)
Autism Spectrum Disorder/diagnosis , Autism Spectrum Disorder/therapy , Behavior Therapy , Healthcare Disparities , Autism Spectrum Disorder/ethnology , Child , Child, Preschool , Ethnicity , Female , Humans , Male , Medicaid , Racial Groups , Socioeconomic Factors , Time-to-Treatment , United States
5.
Int J Dev Disabil ; 64(4-5): 271-281, 2017 Aug 02.
Article in English | MEDLINE | ID: mdl-34141315

ABSTRACT

Background: In recent years, the delivery of early intensive behavioral intervention (EIBI) for children with autism spectrum disorder (ASD) in the United States has significantly changed. More children with ASD than ever before are eligible to use publicly funded EIBI. Yet, the challenges to large-scale implementation of EIBI remain unclear. Specific Aims: We examined parent perceived challenges to treatment utilization, predictors of increased challenges to treatment utilization, and parent recommendations for increasing utilization in a statewide EIBI program. Method: Using a cross-sectional design, we surveyed parents of children with ASD receiving EIBI through South Carolina's Pervasive Developmental Disorder Program (N = 145). To examine the contributions of parent demographic characteristics, parent social support, and child challenging behaviors to perceived challenges to utilization, we used multiple linear regression. Parent recommendations were collected using a single open-ended question. Findings: The most frequently endorsed challenges included the child's school schedule (62.1%) and the child being overburdened with other treatment demands (65.2%). Greater child challenging behaviors were associated with a greater degree of perceived challenges, and social support was associated with a lesser degree of perceived challenges. Discussion: Parents perceived various challenges to utilization, and child and family characteristics may increase the risk for experiencing challenges to utilization. As the delivery of EIBI continues to evolve in the United States and elsewhere, these findings have implications for policy, programming, and future research.

6.
J Rural Health ; 32(1): 92-101, 2016.
Article in English | MEDLINE | ID: mdl-26184098

ABSTRACT

PURPOSE: Little qualitative research has examined factors associated with care in substance abuse treatment agencies in Southeastern rural communities. This study explored client- and agency stakeholder-perceived barriers and facilitators to substance use treatment delivery in southeastern rural communities. METHODS: Group and individual interviews were conducted with 40 key stakeholders and 40 clients at 9 substance abuse agencies serving rural communities in a southeastern state. Qualitative thematic analysis was used to identify perceived barriers and facilitators to substance abuse services in rural communities. FINDINGS: Four primary themes emerged from the client and stakeholder interviews as both barriers and facilitators: availability of services for individuals with substance use disorders; access to the current technology for client services and agency functioning; cost of services; and stigma. CONCLUSIONS: This study identifies novel barriers and facilitators to substance use care in the rural South and highlights essential areas for consideration when developing and implementing substance use care in this geographic region. These findings can be used as guidelines to provide better care to individuals with substance use disorders living in rural communities.


Subject(s)
Health Services Accessibility/statistics & numerical data , Patient Acceptance of Health Care/statistics & numerical data , Rural Health Services/organization & administration , Rural Population/statistics & numerical data , Substance-Related Disorders/rehabilitation , Humans , Patient Acceptance of Health Care/psychology , Qualitative Research , Southeastern United States , Substance Abuse Treatment Centers/organization & administration , Substance-Related Disorders/psychology , Surveys and Questionnaires
7.
Disabil Health J ; 8(3): 407-13, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25595296

ABSTRACT

BACKGROUND: Children with Autism Spectrum Disorder (ASD) participate in a variety of treatments, including medication, behavioral, alternative and developmental treatments. Parent adherence to these treatments is crucial for positive child outcomes. OBJECTIVE: The current study: 1) Explored patterns of parent adherence across the full range of treatments that are prescribed to children with ASD and, 2) Examined whether parent demographics, parent treatment attitudes, and child ASD severity contribute to parents' adherence across ASD treatments. METHOD: Questionnaires were distributed to parents of children with ASD in a southeastern state. Parents (N = 274) were included if they were parenting a child with ASD who was receiving treatment for ASD symptoms. Paired t-tests and multiple linear regression were used to assess the study aims. RESULTS: Adherence to medication treatment was significantly greater than adherence to behavioral, developmental, or alternative treatments (adjusted p-values 0.0006, 0.0030, 0.0006 respectively). Perceived family burden of a treatment was associated with lower adherence to medication, developmental, and alternative treatments. Finally, greater ASD severity was associated with lower adherence to alternative treatments. CONCLUSION: Overall, the independent variables accounted for more variance in adherence to medication and alternative treatments than in behavioral and developmental treatments. Parents' adherence to ASD treatment differs significantly by treatment type and is influenced by parental perceptions of the burden of treatment on the family. These findings highlight the importance of understanding and addressing the impact of ASD treatment regimens on family life.


Subject(s)
Autism Spectrum Disorder/therapy , Autistic Disorder/therapy , Disabled Persons , Parenting , Parents , Patient Compliance , Adolescent , Adult , Autism Spectrum Disorder/drug therapy , Autistic Disorder/drug therapy , Child , Child, Preschool , Female , Humans , Infant , Male , Surveys and Questionnaires
8.
Disabil Health J ; 5(4): 298-304, 2012 Oct.
Article in English | MEDLINE | ID: mdl-23021742

ABSTRACT

BACKGROUND: Health professionals incorporate parent reports into the diagnosis and treatment of children with an autism spectrum disorder (ASD). Yet little is known about the contextual forces that may shape parents' perceptions of their child. OBJECTIVES: The current study seeks to: 1) compare the social ecological contexts of parents of children with ASD and parents of non-autistic children, and 2) explore the social ecological influences on parents' perception of their child's ASD severity. METHODS: This study employed a cross-sectional analysis of data from the 2007-2008 National Survey of Children's Health (NSCH) in the United States. Social ecological factors of interest included variables depicting family physical environment, family social environment, and individual parent characteristics. RESULTS: Results indicate that parents of children with ASD had increased odds of reporting poor neighborhood social capital, greater aggravation, more difficulty coping, and lower levels of relationship satisfaction and mental health. Parents' perceptions of their child's ASD severity were associated with several factors of their social ecological context. More severe parent-reported ASD was associated with aspects of the physical environment (rundown housing and garbage on the street), the social environment (parent relationship satisfaction) and individual parent characteristics (parent aggravation and mental health). CONCLUSIONS: Results suggest ways that professionals can contextualize parent reports to aid in the diagnosis and treatment of children with ASD. Findings also highlight a need for longitudinal research using well-characterized measures to determine the nature and direction of relationships between contextual factors and parents' perceptions.


Subject(s)
Autistic Disorder , Child Development Disorders, Pervasive , Environment , Parents , Perception , Severity of Illness Index , Social Environment , Adaptation, Psychological , Adolescent , Adult , Child , Child, Preschool , Cross-Sectional Studies , Female , Health Surveys , Housing , Humans , Interpersonal Relations , Male , Mental Health , Parents/psychology , Reference Values , Residence Characteristics , Stress, Psychological , United States
9.
Soc Psychiatry Psychiatr Epidemiol ; 47(11): 1807-14, 2012 Nov.
Article in English | MEDLINE | ID: mdl-22322982

ABSTRACT

PURPOSE: To characterize the rate of comorbid psychiatric conditions (CPC) among children with autism spectrum disorders (ASD), to examine their treatment utilization, and to investigate treatment delay or non-delivery. METHODS: Lifetime ASD and CPC in children, aged 2-17, were investigated using data from the 2007-2008 National Survey of Children's Health (NSCH). The NSCH surveyed parents and guardians regarding the health and well being, including treatment, of their child(ren) under age 18 (n = 91,642). Children with health conditions were defined by parent report that a doctor or other health professional had ever said their child had that condition. Factors related to overall health, treatment utilization, and barriers to access variables were investigated among this group. RESULTS: Children with ASD/CPC had poorer overall health outcomes than children with ASD alone. They more often were dissatisfied with their between-provider communication and less often had insurance cover needed services. Nonetheless, they did tend to use care coordination and mental health services to a greater degree. Families were more likely to report the delay or non-receipt of needed services when they perceived a lack of communication and partnership with providers, when they lacked insurance coverage, and when they felt that health care costs were unreasonable. CONCLUSIONS: The presence of a CPC seems to shape the treatment utilization and health outcomes of children with ASD. Because of this, health professionals working with children with autism should give special attention to treatment of those with comorbid diagnoses.


Subject(s)
Child Development Disorders, Pervasive/epidemiology , Child Development Disorders, Pervasive/therapy , Child Health Services/statistics & numerical data , Health Services Accessibility/statistics & numerical data , Mental Disorders/epidemiology , Mental Disorders/therapy , Adolescent , Child , Child Development Disorders, Pervasive/diagnosis , Child, Preschool , Comorbidity , Female , Health Surveys , Humans , Insurance Coverage , Insurance, Health , Male , Mental Disorders/diagnosis , Mental Health Services/statistics & numerical data , Parents , Patient Satisfaction/statistics & numerical data , Socioeconomic Factors
10.
Nucleic Acids Res ; 39(16): 7124-33, 2011 Sep 01.
Article in English | MEDLINE | ID: mdl-21596776

ABSTRACT

Binding of proteins to DNA is usually considered 1D with one protein bound to one DNA molecule. In principle, proteins with multiple DNA binding domains could also bind to and thereby cross-link different DNA molecules. We have investigated this possibility using high-mobility group A1 (HMGA1) proteins, which are architectural elements of chromatin and are involved in the regulation of multiple DNA-dependent processes. Using direct stochastic optical reconstruction microscopy (dSTORM), we could show that overexpression of HMGA1a-eGFP in Cos-7 cells leads to chromatin aggregation. To investigate if HMGA1a is directly responsible for this chromatin compaction we developed a DNA cross-linking assay. We were able to show for the first time that HMGA1a can cross-link DNA directly. Detailed analysis using point mutated proteins revealed a novel DNA cross-linking domain. Electron microscopy indicates that HMGA1 proteins are able to create DNA loops and supercoils in linearized DNA confirming the cross-linking ability of HMGA1a. This capacity has profound implications for the spatial organization of DNA in the cell nucleus and suggests cross-linking activities for additional nuclear proteins.


Subject(s)
DNA/chemistry , HMGA1a Protein/chemistry , AT-Hook Motifs , Amino Acid Sequence , Amino Acids, Basic/chemistry , Animals , COS Cells , Chlorocebus aethiops , Chromatin/chemistry , DNA/ultrastructure , HMGA1a Protein/analysis , HMGA1a Protein/genetics , Molecular Sequence Data , Mutation
11.
BMC Cell Biol ; 11: 64, 2010 Aug 11.
Article in English | MEDLINE | ID: mdl-20701767

ABSTRACT

BACKGROUND: High mobility group A (HMGA) proteins regulate gene transcription through architectural modulation of chromatin and the formation of multi-protein complexes on promoter/enhancer regions. Differential expression of HMGA variants has been found to be important for distinct differentiation processes and deregulated expression was linked to several disorders. Here we used mouse C2C12 myoblasts and C2C12 cells stably over-expressing HMGA1a-eGFP to study the impact of deregulated HMGA1 expression levels on cellular differentiation. RESULTS: We found that induction of the myogenic or osteogenic program of C2C12 cells caused an immediate down-regulation of HMGA1. In contrast to wild type C2C12 cells, an engineered cell line with stable over-expression of HMGA1a-eGFP failed to differentiate into myotubes. Immunolocalization studies demonstrated that sustained HMGA1a-eGFP expression prevented myotube formation and chromatin reorganization that normally accompanies differentiation. Western Blot analyses showed that elevated HMGA1a-eGFP levels affected chromatin composition through either down-regulation of histone H1 or premature expression of MeCP2. RT-PCR analyses further revealed that sustained HMGA1a expression also affected myogenic gene expression and caused either down-regulation of genes such as MyoD, myogenin, Igf1, Igf2, Igfbp1-3 or up-regulation of the transcriptional repressor Msx1. Interestingly, siRNA experiments demonstrated that knock-down of HMGA1a was required and sufficient to reactivate the myogenic program in induced HMGA1a over-expressing cells. CONCLUSIONS: Our data demonstrate that HMGA1 down-regulation after induction is required to initiate the myogenic program in C2C12 cells. Sustained HMGA1a expression after induction prevents expression of key myogenic factors. This may be due to specific gene regulation and/or global effects on chromatin. Our data further corroborate that altered HMGA1 levels influence the expression of other chromatin proteins. Thus, HMGA1 is able to establish a specific chromatin composition. This work contributes to the understanding of how differential HMGA1 expression is involved in chromatin organization during cellular differentiation processes and it may help to comprehend effects of HMGA1 over-expression occurring in malign or benign tumours.


Subject(s)
HMGA1a Protein/metabolism , Muscle Development , Muscle Fibers, Skeletal/metabolism , Myoblasts, Skeletal/metabolism , Recombinant Fusion Proteins/metabolism , Animals , Cell Line , Chromatin Assembly and Disassembly/genetics , Cloning, Molecular , DNA-Binding Proteins/metabolism , Gene Expression Regulation , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , HMGA1a Protein/genetics , Histone Deacetylases/metabolism , Histones/metabolism , Mice , Muscle Development/genetics , Muscle Fibers, Skeletal/pathology , Myoblasts, Skeletal/pathology , Recombinant Fusion Proteins/genetics
12.
Biochim Biophys Acta ; 1799(1-2): 15-27, 2010.
Article in English | MEDLINE | ID: mdl-20123065

ABSTRACT

Members of the superfamily of high mobility group (HMG) proteins are considered as architectural elements of chromatin. It is now clear that they belong to a network of dynamic chromatin proteins that constantly move around the chromatin fiber thereby dynamically modulating DNA-dependent processes. In this review we discuss how HMGs fused to fluorescent proteins and live cell imaging advanced our understanding in HMG dynamics and function. By presenting the regulation of the dynamic properties of each HMG family in comparison to one another we wish to highlight common themes among the three families, as well as stimulate new ideas from one HMG family in relation to the others and more generally in the dynamic world of chromatin.


Subject(s)
Chromatin/metabolism , High Mobility Group Proteins/metabolism , Imaging, Three-Dimensional , Animals , Cell Survival , Humans , Protein Binding , Protein Processing, Post-Translational
14.
Biochem Cell Biol ; 87(1): 127-37, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19234529

ABSTRACT

The dynamic interaction between nuclear proteins and chromatin leads to the functional plasticity necessary to mount adequate responses to regulatory signals. Here, we review the factors regulating the chromatin interactions of the high mobility group proteins (HMGs), an abundant and ubiquitous superfamily of chromatin-binding proteins in living cells. HMGs are highly mobile and interact with the chromatin fiber in a highly dynamic fashion, as part of a protein network. The major factors that affect the binding of HMGs to chromatin are operative at the level of the single nucleosome. These factors include structural features of the HMGs, competition with other chromatin-binding proteins for nucleosome binding sites, complex formation with protein partners, and post-translational modifications in the protein or in the chromatin-binding sites. The versatile modulation of the interaction between HMG proteins and chromatin plays a role in processes that establish the cellular phenotype.


Subject(s)
Chromatin/metabolism , High Mobility Group Proteins/metabolism , Animals , Cell Survival , High Mobility Group Proteins/chemistry , Humans , Protein Binding
15.
Proc Natl Acad Sci U S A ; 105(5): 1692-7, 2008 Feb 05.
Article in English | MEDLINE | ID: mdl-18234858

ABSTRACT

In all eukaryotic cells, origins of DNA replication are characterized by the binding of the origin recognition complex (ORC). How ORC is positioned to sites where replication initiates is unknown, because metazoan ORC binds DNA without apparent sequence specificity. Thus, additional factors might be involved in ORC positioning. Our experiments indicate that a family member of the high-mobility group proteins, HMGA1a, can specifically target ORC to DNA. Coimmunoprecipitations and imaging studies demonstrate that HMGA1a interacts with different ORC subunits in vitro and in vivo. This interaction occurs mainly in AT-rich heterochromatic regions to which HMGA1a localizes. Fusion proteins of HMGA1a and the DNA-binding domain of the viral factor EBNA1 or the prokaryotic tetracycline repressor, TetR, can recruit ORC to cognate operator sites forming functional origins of DNA replication. When HMGA1a is targeted to plasmid DNA, the prereplicative complex is assembled during G(1) and the amount of ORC correlates with the local concentration of HMGA1a. Nascent-strand abundance assays demonstrate that DNA replication initiates at or near HMGA1a-rich sites. Our experiments indicate that chromatin proteins can target ORC to DNA, suggesting they might specify origins of DNA replication in metazoan cells.


Subject(s)
DNA Replication , HMGA1a Protein/metabolism , Origin Recognition Complex/metabolism , Replication Origin , Binding Sites , Cell Line , Epstein-Barr Virus Nuclear Antigens/genetics , Epstein-Barr Virus Nuclear Antigens/metabolism , HMGA1a Protein/analysis , HMGA1a Protein/genetics , Humans , Immunoprecipitation , Origin Recognition Complex/analysis , Plasmids/chemistry , Plasmids/genetics , Protein Structure, Tertiary , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism
16.
Mol Biol Cell ; 19(5): 1816-24, 2008 May.
Article in English | MEDLINE | ID: mdl-18287527

ABSTRACT

Throughout the cell cycle, the histones remain associated with DNA, but the repertoire of proteins associated with the chromatin fiber continuously changes. The chromatin interaction of HMGNs, a family of nucleosome binding proteins that modulates the structure and activity of chromatin, during the cell cycle is controversial. Immunofluorescence studies demonstrated that HMGNs are not associated with chromatin, whereas live cell imaging indicated that they are present in mitotic chromosomes. To resolve this controversy, we examined the organization of wild-type and mutated HMGN1 and HMGN2 proteins in the cell nucleus by using immunofluorescence studies, live cell imaging, gel mobility shift assays, and bimolecular fluorescence complementation (BiFC). We find that during interphase, HMGNs bind specifically to nucleosomes and form homodimeric complexes that yield distinct BiFC signals. In metaphase, the nucleosomal binding domain of the protein is inactivated, and the proteins associate with chromatin with low affinity as monomers, and they do not form specific complexes. Our studies demonstrate that the mode of binding of HMGNs to chromatin is cell cycle dependent.


Subject(s)
Cell Cycle , Chromatin/metabolism , HMGN1 Protein/metabolism , HMGN2 Protein/metabolism , Animals , Cell Survival , Chromosomes, Human/metabolism , Fluorescence , Genetic Complementation Test , HMGN1 Protein/chemistry , HMGN2 Protein/chemistry , HeLa Cells , Humans , Interphase , Mice , Mitosis , Models, Biological , Phosphorylation , Protein Binding , Protein Structure, Tertiary , Rats
17.
Chromosoma ; 117(2): 147-57, 2008 Apr.
Article in English | MEDLINE | ID: mdl-17999076

ABSTRACT

Extensive epidemiological data indicate that inorganic arsenic is associated with several types of human cancer. Nevertheless, the underlying mechanisms are poorly understood. Among its mode of action are the alterations on DNA methylation, which provoke aberrant gene expression. However, beyond DNA methylation, little is known about arsenic's effects on chromatin. In this study, we investigated the effects of sodium arsenite (NaAsO(2)) on global histone modifications and nucleosome-associated proteins. Our findings revealed that NaAsO(2) exposure significantly increases global histone acetylation. This effect was related to the inhibition of histone deacetylase (HDAC) activity because NaAsO(2) was able to inhibit HDACs comparable to the well-known HDAC inhibitor trichostatin A (TSA). Furthermore, analyses of the dynamic properties of the nucleosome-associated high mobility group N proteins demonstrate that NaAsO(2) elevates their mobility. Thus, our data suggest that NaAsO(2) induces chromatin opening by histone hyperacetylation due to HDAC inhibition and increase of the mobility of nucleosome-associated proteins. As the chromatin compaction is crucial for the regulation of gene expression as well as for genome stability, we propose that chromatin opening by NaAsO(2) may play a significant role to impart its genotoxic effects.


Subject(s)
Arsenites/pharmacology , HMGN Proteins/metabolism , Histone Deacetylases/metabolism , Histones/metabolism , Sodium Compounds/pharmacology , Arsenites/metabolism , Cell Death , Cell Line , Cell Line, Tumor , Chromatin/metabolism , DNA Methylation , Humans , Hydroxamic Acids/pharmacology , Microscopy, Fluorescence , Models, Biological , Nucleosomes/metabolism , Protein Synthesis Inhibitors/pharmacology , Sodium Compounds/metabolism
18.
Mutat Res ; 637(1-2): 152-60, 2008 Jan 01.
Article in English | MEDLINE | ID: mdl-17888458

ABSTRACT

Aneuploidy represents a serious problem for human health. Toxicological data have shown that aneuploidy can be caused by exposure to chemical agents known as mitotic spindle poisons, since they arrest cell cycle in mitosis through their interaction with tubulin. Among these agents is arsenic. In previous reports, we demonstrated that the aneugenic events induced by sodium arsenite can be abolished by the exogenous addition of S-adenosyl-l-methionine (SAM). Nevertheless, the mechanisms involved are still unknown. The aim of the present work was to study the influence of SAM on the mitotic disturbances caused by sodium arsenite. To achieve this goal, we analyzed microtubule (MT) polymerization by immunolocalization and live cell microscopy of mitotic cells. Our findings indicate that sodium arsenite alters the dynamics of MT polymerization, induces centrosome amplification and delays mitosis. Furthermore, SAM reduces the alterations on MT dynamics, as well as centrosome amplification, and therefore diminishes the formation of multipolar spindles in treated HeLa cells. In addition, SAM decreases the progression time through mitosis. Taking these data together, we consider that the mechanism by which SAM reduces the frequency of aneuploid cells must be related to the modulation of the dynamics and organization of MT, suggesting a role of SAM on chromosome segregation, which should be further investigated in primary cells.


Subject(s)
Arsenites/antagonists & inhibitors , Cytostatic Agents/antagonists & inhibitors , Mitosis/drug effects , S-Adenosylmethionine/pharmacology , Sodium Compounds/antagonists & inhibitors , Cell Cycle/drug effects , Centrosome/drug effects , HeLa Cells , Humans , Spindle Apparatus/chemistry , Spindle Apparatus/drug effects , Spindle Apparatus/metabolism
19.
Mutat Res ; 617(1-2): 16-22, 2007 Apr 01.
Article in English | MEDLINE | ID: mdl-17241646

ABSTRACT

Alterations in methyl group's metabolism affect availability of S-adenosyl-L-methionine (SAM); these modifications can be originated by enzyme polymorphisms, nutritional deficiencies, and exposure to chemical agents. There are several types of chemicals that interfere with methyl groups, among them is arsenic. It deserves special attention because it modifies a number of cell functions that influence the development of diseases such as cancer. Since part of arsenic's toxicity is influenced by changes on SAM availability, in a previous study we investigated whether exogenous addition of SAM to cells treated with sodium arsenite (NaAsO(2)) has an effect on its genotoxicity. Results demonstrated that SAM reduces the frequency of cells presenting micronuclei (MN) and tubulin-cytoskeleton defects after treatment with NaAsO(2). MN are fragments of the cell nucleus that may contain whole chromosomes or chromosome fragments depending on whether they derive either from the aneugenic or from the clastogenic action of chemicals. Therefore one question generated by these results was whether SAM reduced only the frequency MN resulting from aneugenic damage. To answer this question, in the present work we used an all-centromere DNA probe to distinguish the type of MN reduced by SAM after treatment with NaAsO(2) and vinblastine. In addition, the capacity of SAM to reduce clastogenicity was also evaluated. Results show that SAM decreases the frequency of cells with MN containing whole chromosomes in cultures treated either with NaAsO(2) or with vinblastine; however, induction of double-strand breaks by NaAsO(2) was not prevented by SAM.


Subject(s)
Aneuploidy , Arsenites/toxicity , DNA Damage , Enzyme Inhibitors/toxicity , Fibroblasts/drug effects , Micronuclei, Chromosome-Defective/drug effects , S-Adenosylmethionine/pharmacology , Sodium Compounds/toxicity , Ataxia Telangiectasia Mutated Proteins , Carcinoma, Hepatocellular/metabolism , Carcinoma, Hepatocellular/pathology , Cell Cycle Proteins/metabolism , Cells, Cultured , Centromere , Chromosome Aberrations , DNA Probes , DNA-Binding Proteins/metabolism , Fibroblasts/metabolism , Histones/metabolism , Humans , In Situ Hybridization, Fluorescence , Infant , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , Micronucleus Tests , Protein Serine-Threonine Kinases/metabolism , Skin/cytology , Tumor Suppressor Proteins/metabolism
20.
Trends Cell Biol ; 17(2): 72-9, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17169561

ABSTRACT

The high mobility group (HMG) proteins are a superfamily of abundant and ubiquitous nuclear proteins that bind to DNA and nucleosomes and induce structural changes in the chromatin fiber. They are important in chromatin dynamics and influence DNA processing in the context of chromatin. Results emerging from studies of human disease, genetically modified mice and cells with altered HMG expression indicate that the expression of the HMG proteins is developmentally regulated and that changes in HMG protein levels alter the cellular phenotype and can lead to developmental abnormalities and disease. Here, we focus on the biological function of HMG proteins and highlight their possible roles in cellular differentiation and in the etiology of various diseases.


Subject(s)
Cell Differentiation/physiology , Chromatin/metabolism , High Mobility Group Proteins/physiology , Animals , Cell Differentiation/genetics , Chromatin/ultrastructure , DNA/metabolism , Epigenesis, Genetic , Gene Expression Regulation, Developmental , HMGA Proteins/genetics , HMGA Proteins/physiology , HMGB Proteins/genetics , HMGB Proteins/physiology , HMGN Proteins/genetics , HMGN Proteins/physiology , High Mobility Group Proteins/genetics , Humans , Mice , Mice, Knockout , Organ Specificity , Phenotype , Xenopus laevis
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