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1.
J Am Acad Psychiatry Law ; 51(2): 255-262, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37257906

RESUMO

There are approximately 500,000 children in the foster care system in the United States of America. With exposure to chronic and cumulative trauma, they constitute a population with an increased risk of developing mental health concerns and adverse outcomes in later life, including contact with the forensic system. Legislative frameworks that have been developed to facilitate improved outcomes are outlined, although these vary between states, and the focus is often on the parental relationship. Several studies have emphasized the importance of sibling relationships and that placing siblings in the same foster home is associated with higher rates of placement stability, reunification, adoption and guardianship, and fostering positive sibling relations. The multifaceted role of the clinician in promoting recovery from trauma, enhancing resiliency, and thoughtfully prescribing and advocating for familial relationships is discussed.


Assuntos
Maus-Tratos Infantis , Relações entre Irmãos , Criança , Humanos , Estados Unidos , Irmãos , Cuidados no Lar de Adoção , Proteção da Criança
2.
Curr Atheroscler Rep ; 24(4): 253-264, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35320835

RESUMO

PURPOSE OF REVIEW: The goal of this article is to characterize the myriad of ways that children with mental health conditions can be at risk for premature cardiovascular disease (CVD) and various modalities to ameliorate this risk in childhood in order to improve the life course of these children. REVIEW FINDINGS: Child and adolescent mental health conditions are a common yet underrecognized risk factor for premature CVD. The American Heart Association has recently included psychiatric conditions as a CVD risk factor (CVDRF) and the evidence linking childhood adversity to cardiometabolic disease. There are bidirectional and additive effects from the intrinsic emotional dysregulation and inflammatory changes from the mental health condition, the associations with risky health behaviors, and in some cases, metabolic side effects from pharmacotherapy. These pathways can be potentiated by toxic stress, a physiologic response to stressors from childhood adversity. Toxic stress is also associated with development of mental health conditions with epigenetic effects that can result in transgenerational inheritance of cardiometabolic risk. Exposure to toxic stress and mental health conditions in isolation sometimes compounded by pharmacotherapies used in treatment increase the risk of cardiometabolic diseases in childhood. The multiple pathways, which adversely influence cardiometabolic outcomes, encourage clinicians to consider strategies to mitigate these factors and justify the importance of early screening and treatment for CVDRFs. Mental health, health behaviors, and environmental factors co-occur and intersect in complex pathways that can increase CVD risk over the lifespan. Early detection and response can mitigate the risks associated with premature development of CVD.


Assuntos
Doenças Cardiovasculares , Adolescente , American Heart Association , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/etiologia , Doenças Cardiovasculares/prevenção & controle , Criança , Fatores de Risco de Doenças Cardíacas , Humanos , Saúde Mental , Fatores de Risco
3.
Arch Sex Behav ; 50(1): 83-103, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33231828

RESUMO

Despite the fact that HIV can be controlled with medication to undetectable levels where it cannot be passed on, stigmatization of women living with HIV persists. Such stigmatization pivots on stereotypes around sex and sexism and has force in women's lives. Our aim was to create an inspirational resource for women living with HIV regarding sex, relationships, and sexuality: www.lifeandlovewithhiv.ca (launched in July 2018). This paper describes the development and mixed-method evaluation of our first year and a half activities. We situated our work within a participatory arts-based knowledge translation planning framework and used multiple data sources (Google Analytics, stories and comments on the website, team reflections over multiple meetings) to report on interim outcomes and impacts. In our first 1.5 years, we recruited and mentored 12 women living with HIV from around the world (Canada, Australia, New Zealand, Kenya, South Africa, Spain, Nigeria, and the U.S.) to write their own stories, with the support of a mentor/editor, as a way of regaining control of HIV narratives and asserting their right to have pleasurable, fulfilling, and safer sexual lives. Writers published 43 stories about pleasure, orgasm, bodies, identities, trauma, resilience, dating, disclosure, self-love, and motherhood. Our social media community grew to 1600, and our website received approximately 300 visits per month, most by women (70%) and people aged 25-44 years (65%), from more than 50 cities globally, with shifts in use and demographics over time. Qualitative data indicated the power of feminist digital storytelling for opportunity, access, validation, and healing, though not without risks. We offer recommendations to others interested in using arts-based digital methods to advance social equity in sexual health.


Assuntos
Infecções por HIV/epidemiologia , Terapia Narrativa/métodos , Prazer/fisiologia , Comportamento Sexual/psicologia , Feminino , Humanos
4.
J Cyst Fibros ; 15(1): 74-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26104996

RESUMO

BACKGROUND: Poor nebuliser hygiene can result in bacterial contamination and risk of infections. The aim of this study was to assess the prevalence of fungal contamination of nebulisers used by adults with cystic fibrosis. METHODS: A total of 170 nebulisers from 149 subjects were screened by wetting a sterile cotton swab with sterile water and swabbing each drug chamber. The swab was then plated out on Sabouraud and on Scel+agar and incubated at 27 °C for up to 2 weeks. RESULTS: Fungal cultures were positive in 86 (57.7%) patient's devices. In 28/149 (18.8%), 39/149 (26.2%), 47/149 (31.5%) and 20/149 (13.4%) of subjects Aspergillus species, yeasts, moulds and both yeasts and moulds were isolated respectively. There was no difference in contamination rates between different devices. CONCLUSION: Nebuliser devices are frequently contaminated by moulds and yeasts and emphasis should be placed on ensuring adequate nebuliser hygiene.


Assuntos
Antibacterianos/administração & dosagem , Fibrose Cística/tratamento farmacológico , Contaminação de Equipamentos/prevenção & controle , Expectorantes/administração & dosagem , Fungos/isolamento & purificação , Nebulizadores e Vaporizadores/microbiologia , Adulto , Aerossóis , Feminino , Humanos , Masculino , Educação de Pacientes como Assunto , Melhoria de Qualidade
5.
J Mol Biol ; 423(1): 63-78, 2012 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-22750730

RESUMO

The core shell of hepatitis B virus is a potent immune stimulator, giving a strong neutralizing immune response to foreign epitopes inserted at the immunodominant region, located at the tips of spikes on the exterior of the shell. Here, we analyze structures of core shells with a model epitope inserted at two alternative positions in the immunodominant region. Recombinantly expressed core protein assembles into T=3 and T=4 icosahedral shells, and atomic coordinates are available for the T=4 shell. Since the modified protein assembles predominantly into T=3 shells, a quasi-atomic model of the native T=3 shell was made. The spikes in this T=3 structure resemble those in T=4 shells crystallized from expressed protein. However, the spikes in the modified shells exhibit an altered conformation, similar to the DNA containing shells in virions. Both constructs allow full access of antibodies to the foreign epitope, DPAFR from the preS1 region of hepatitis B virus surface antigen. However, one induces a 10-fold weaker immune response when injected into mice. In this construct, the epitope is less constrained by the flanking linker regions and is positioned so that the symmetry of the shell causes pairs of epitopes to come close enough to interfere with one another. In the other construct, the epitope mimics the native epitope conformation and position. The interaction of native core shells with an antibody specific to the immunodominant epitope is compared to the constructs with an antibody against the foreign epitope. Our findings have implications for the design of vaccines based on virus-like particles.


Assuntos
Complexo Antígeno-Anticorpo/imunologia , Epitopos/imunologia , Anticorpos Anti-Hepatite B/imunologia , Antígenos do Núcleo do Vírus da Hepatite B/imunologia , Vírus da Hepatite B/imunologia , Sequência de Aminoácidos , Animais , Complexo Antígeno-Anticorpo/química , Epitopos/química , Anticorpos Anti-Hepatite B/química , Antígenos do Núcleo do Vírus da Hepatite B/química , Antígenos de Superfície da Hepatite B/química , Antígenos de Superfície da Hepatite B/imunologia , Vírus da Hepatite B/química , Camundongos , Dados de Sequência Molecular , Conformação Proteica
6.
Psychiatr Serv ; 62(5): 525-31, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21532079

RESUMO

OBJECTIVES: Data are limited on how clinicians contribute to outcome differences between black patients and white patients. Because the clinician-patient relationship is the foundation of mental health services, understanding clinicians' role in outcome differences may help identify evidence-based interventions that decrease disparities and capitalize on positive differences. Symptoms and functioning in a sample of black and white adults receiving outpatient services were examined to determine the effects of their primary clinician on those patterns. METHODS: The study included 551 patients (25% black) with serious mental illness and 62 mental health professionals (21% black) identified as the patients' primary clinician. Treatment outcomes were measured at baseline and two follow-ups (two and four months) with the Behavior and Symptom Identification Scale, a measure of symptoms and functioning. Data were analyzed with hierarchical linear modeling. Clinicians' levels of multicultural competence, burnout, and education were analyzed. RESULTS: Clinicians moderated the relationship between patient race and outcome differences. There was significant variability among clinicians: approximately 20% had black patients whose outcomes were worse than those of their white patients, and 40% had black patients with better outcomes than their white patients. The only clinician factor predicting these differences was clinician's general experiences and relationships with people from racial-ethnic and cultural groups other than their own. CONCLUSIONS: The occurrence of outcome differences varied across clinicians, with some clinicians magnifying outcome differences between black and white patients and others minimizing them. Factors other than clinicians' race, multicultural competence, education, and burnout may contribute to outcome differences between black and white patients.


Assuntos
Negro ou Afro-Americano , Centros Comunitários de Saúde Mental , Transtornos Mentais , Avaliação de Resultados em Cuidados de Saúde , População Branca , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Relações Profissional-Paciente , Inquéritos e Questionários , Estados Unidos
7.
Psychiatr Serv ; 62(11): 1255-7, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22211202

RESUMO

Between 2009 and 2011, states implemented significant budget cuts to community mental health agencies (CMHAs), which are frequently the sole provider of specialized behavioral health services in rural communities. Starting in 2010, federal policy changes created by health care reform and mental health parity are likely to increase the number of individuals who can afford to seek services for a mental illness. CMHAs under financial stress have begun to eliminate services and reduce staff. These trends could result in a growing gap between available behavioral health services and the number of people who can afford to seek treatment for a mental illness.


Assuntos
Orçamentos , Serviços Comunitários de Saúde Mental/métodos , Reforma dos Serviços de Saúde , Necessidades e Demandas de Serviços de Saúde , Serviços de Saúde Rural/provisão & distribuição , Adulto , Criança , Serviços Comunitários de Saúde Mental/economia , Serviços Comunitários de Saúde Mental/provisão & distribuição , Redução de Custos/tendências , Humanos , Estados Unidos
8.
J Adolesc Health ; 38(5): 621-3, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16635780

RESUMO

This study hypothesized that gender-role nonconformity is associated with suicidality, and bullying mediates this relationship. Gay males retrospectively answered questions pertaining to elementary, middle, and high school. Support for the hypotheses was found. Results can help screen gay youth for suicidality and support the need for policies prohibiting harassment based on sexual orientation.


Assuntos
Comportamento do Adolescente , Identidade de Gênero , Homossexualidade Masculina/psicologia , Assédio Sexual , Tentativa de Suicídio/psicologia , Adolescente , Adulto , Agressão , Vítimas de Crime/psicologia , Humanos , Relações Interpessoais , Masculino , Apoio Social
9.
Soc Work ; 51(1): 49-58, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16512510

RESUMO

This study examined the help-seeking behaviors of depressed, African American adolescents. Qualitative interviews were conducted with 18 urban, African American boys, ages 14 to 18, who were recruited from community-based mental health centers and after-school programs for youths. Interviews covered sociodemographic information, questions regarding depressive symptomotology, and open-ended questions derived from the Network-Episode Model--including knowledge, attitudes and behaviors related to problem recognition, help seeking, and perceptions of mental health services. Most often adolescents discussed their problems with their family and often received divergent messages about problem resolution; absent informal network resolution of their problems, professional help would be sought, and those receiving treatment were more likely to get support from friends but were less likely to tell friends that they were actually receiving care. Implications for social work research and practice are discussed.


Assuntos
Negro ou Afro-Americano , Depressão , Aceitação pelo Paciente de Cuidados de Saúde , Adolescente , Humanos , Entrevistas como Assunto , Masculino , Estados Unidos
10.
Int J Law Psychiatry ; 28(3): 290-9, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15935476

RESUMO

At times in psychiatric treatment practice in the United States, the notion of individualism or independence (an American ideal) is confused with autonomy (a rights goal). Client autonomy is defined as the ability of clients to make their own choices. When the societal ideal of independence overrides individual autonomy, inclusion and client well-being may be jeopardized. A case will be presented to illustrate these points. We make recommendations for professional education to protect client rights through understanding the distinction between autonomy and independence.


Assuntos
Atividades Cotidianas/psicologia , Transtornos Mentais/reabilitação , Autonomia Pessoal , Conflito Psicológico , Pessoas com Deficiência , Humanos , Masculino , Pessoa de Meia-Idade , Psicoterapia , Resultado do Tratamento , Estados Unidos
11.
Health Soc Work ; 29(4): 297-305, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15575457

RESUMO

The authors surveyed a random sample of 1,200 NASW members in post-master's practice in mental health to identify their attitudes toward practice with people with severe mental illness. Contrary to the literature that claims social workers have abandoned vulnerable populations or have negative attitudes toward this population, the authors found that the majority practice with this clientele and find their practice rewarding. Most of the respondents' frustration and obstacles in practice were related to systemic problems, not client-related problems. Respondents' recommendations for education of future practitioners are presented.


Assuntos
Atitude do Pessoal de Saúde , Serviços Comunitários de Saúde Mental , Satisfação no Emprego , Transtornos Mentais/classificação , Serviço Social em Psiquiatria , Adulto , Idoso , Feminino , Humanos , Masculino , Transtornos Mentais/terapia , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Inquéritos e Questionários
12.
Med Biol Eng Comput ; 42(1): 37-43, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14977221

RESUMO

A stereo-photogrammetric method for three-dimensional reconstruction of points in low-dose digital X-ray images obtained using a scanner with similar imaging geometry to that of computed tomography scan projection radiography, was analysed. A calibration frame containing 25 radio-opaque markers with known three-dimensional locations was scanned, and the accuracy of reconstruction of the marker positions under varying control point configurations and separation angles was assessed. Errors of less than 1 mm were obtained when nine test points were reconstructed, with 16, 11 and 7 control points at a 90 degrees separation angle, and with 16 and 11 control points at 75 degrees and 60 degrees separation angles. The optimum reconstruction, with a resultant error of 0.68 mm, was found to occur at a separation angle of 90 degrees, with the largest number of control points (16) used to calculate the parameters of the transformation. Extrapolation in the scanning direction beyond the space defined by the control points gave errors of less than 2 mm. This method should be suitable for three-dimensional point reconstruction in applications such as cephalometry, brachytherapy planning and assessment of spinal shape.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Fotogrametria/métodos , Tomografia Computadorizada por Raios X/métodos , Humanos
13.
J Behav Health Serv Res ; 30(4): 418-32, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14593665

RESUMO

HIV infection among people with severe mental illness (SMI) is a growing concern, and interventions have been designed to address HIV prevention among these individuals. However, little is known about the preparedness of mental health providers to support these interventions. This study concentrated on mental health case management as a locus for HIV-prevention services. Focus groups of case managers were conducted to learn participants' motivation to adopt HIV-prevention services and barriers/facilitators to such adoption. Participants reported they would be motivated to offer HIV prevention if services were to be presented in the context of existing client relationships and case-management tasks. Barriers and facilitators were discussed at client, provider, and community levels, and recommendations for training were offered. Findings have implications for diffusion of HIV-prevention services in case management, and the line of questioning in focus groups provides a basis for learning about other behavioral health service contexts as loci for disease prevention.


Assuntos
Administração de Caso , Infecções por HIV/prevenção & controle , Serviços de Saúde Mental/organização & administração , Pessoas Mentalmente Doentes/psicologia , Prevenção Primária/organização & administração , Adulto , Prestação Integrada de Cuidados de Saúde , Feminino , Grupos Focais , Infecções por HIV/epidemiologia , Infecções por HIV/psicologia , Humanos , Masculino , Pessoas Mentalmente Doentes/estatística & dados numéricos , Modelos Organizacionais , Assistência Centrada no Paciente , Pennsylvania/epidemiologia , Avaliação de Programas e Projetos de Saúde
14.
Qual Life Res ; 12 Suppl 1: 17-23, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-12803307

RESUMO

It has been our experience that it is easier to measure quality of life among persons with serious mental illness than it is to intervene to improve it. This article presents background and historical context of service delivery to persons with severe mental illness. We then examine approaches to assessing outcomes of services, especially quality of life. We conclude with an illustration and discussion of dilemmas in measuring quality of life in this vulnerable population.


Assuntos
Transtornos Mentais/psicologia , Serviços de Saúde Mental/normas , Pessoas Mentalmente Doentes , Avaliação de Resultados em Cuidados de Saúde , Qualidade de Vida , Atividades Cotidianas , Pesquisa sobre Serviços de Saúde/métodos , Nível de Saúde , Humanos , Determinação da Personalidade , Índice de Gravidade de Doença , Estados Unidos
15.
J Am Acad Child Adolesc Psychiatry ; 39(5): 619-26, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-10802980

RESUMO

OBJECTIVE: While Adderall has been available for the treatment of attention-deficit/hyperactivity disorder (ADHD) for several years, there are few controlled studies comparing it to methylphenidate. METHOD: Fifty-eight children with ADHD (mean age 8.1 +/- 1.4 years) were randomly assigned to receive placebo, methylphenidate, or Adderall in a double-blind, parallel-group design for 3 weeks. Dosage was adjusted at the end of weeks 1 and 2 via an algorithm based on teacher and parent ratings. Final doses were 12.5 +/- 4.1 mg/day for Adderall and 25.2 +/- 13.1 mg/day for methylphenidate. Teacher and parent ratings, as well as the psychiatrist's Clinical Global Impression (CGI), were the final outcome measures at the end of week 3. RESULTS: Both medications were superior to placebo at reducing inattentive and oppositional symptoms in the classroom and on the CGI. Adderall produced significantly more improvements on teacher ratings and the CGI than methylphenidate, although the algorithm may have limited dosing in the methylphenidate group. Seventy percent of children in the Adderall group were given medication once a day, compared with 15% of the subjects receiving methylphenidate. CONCLUSIONS: Adderall compared favorably to methylphenidate, and the behavioral effects of Adderall appear to persist longer than those of methylphenidate after individual doses.


Assuntos
Algoritmos , Transtorno do Deficit de Atenção com Hiperatividade/tratamento farmacológico , Estimulantes do Sistema Nervoso Central/uso terapêutico , Metilfenidato/uso terapêutico , Criança , Método Duplo-Cego , Feminino , Humanos , Masculino , Resultado do Tratamento
16.
J Periodontol ; 71(1): 1-7, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10695932

RESUMO

BACKGROUND: The levels of glycosaminoglycans in gingival crevicular fluid (GCF) are good indicators of underlying tissue turnover. We hypothesize that connective tissue elements in GCF may be used as indicators of tissue maturation underneath barrier membranes. Therefore, we investigated the levels of sulfated glycosaminoglycans in GCF at sites before and after guided tissue regeneration (GTR). METHODS: Six patients were selected on the basis of having at least one Class II buccal furcation involvement on a molar tooth. Each molar furcation was treated with the standard GTR surgical protocol using a non-resorbable expanded polytetrafluoroethylene membrane. Gingival crevicular fluid samples were taken at baseline (immediately prior to insertion of the membrane) and at 1, 2, 3, 4, 5, and 6 weeks (immediately prior to removal of the membrane). Glycosaminoglycan levels were determined using an Alcian blue dye detection system. RESULTS: The mean levels of chondroitin sulfate and total sulfated glycosaminoglycans in GCF significantly decreased during the first 4 weeks after GTR surgery. By week 5, the levels began to rise, and by week 6 the levels had returned to baseline levels. CONCLUSIONS: Sulfated glycosaminoglycans can be monitored in GCF at healing GTR sites. It is proposed that this is a useful means of monitoring the status of the regenerating tissues. However, further longitudinal studies are required to assess if the sulfated glycosaminoglycans can be used as indicators of tissue maturation under guided tissue membranes used to treat periodontal defects.


Assuntos
Defeitos da Furca/metabolismo , Líquido do Sulco Gengival/química , Glicosaminoglicanos/análise , Regeneração Tecidual Guiada Periodontal , Adulto , Azul Alciano , Análise de Variância , Biomarcadores/análise , Sulfatos de Condroitina/análise , Corantes , Tecido Conjuntivo/metabolismo , Seguimentos , Defeitos da Furca/classificação , Defeitos da Furca/cirurgia , Humanos , Ácido Hialurônico/análise , Masculino , Membranas Artificiais , Pessoa de Meia-Idade , Dente Molar , Projetos Piloto , Politetrafluoretileno , Regeneração
17.
Mol Cell ; 3(6): 771-80, 1999 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10394365

RESUMO

Hepatitis B is a small enveloped DNA virus that poses a major hazard to human health. The crystal structure of the T = 4 capsid has been solved at 3.3 A resolution, revealing a largely helical protein fold that is unusual for icosahedral viruses. The monomer fold is stabilized by a hydrophobic core that is highly conserved among human viral variants. Association of two amphipathic alpha-helical hairpins results in formation of a dimer with a four-helix bundle as the major central feature. The capsid is assembled from dimers via interactions involving a highly conserved region near the C terminus of the truncated protein used for crystallization. The major immunodominant region lies at the tips of the alpha-helical hairpins that form spikes on the capsid surface.


Assuntos
Capsídeo/química , Vírus da Hepatite B/química , Sequência de Aminoácidos , Sítios de Ligação , Capsídeo/genética , Capsídeo/metabolismo , Sequência Conservada , Cristalização , Cristalografia por Raios X , Cisteína/metabolismo , Dimerização , Dissulfetos/metabolismo , Elétrons , Epitopos/química , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Dobramento de Proteína , Estrutura Secundária de Proteína , Deleção de Sequência
18.
Acta Crystallogr D Biol Crystallogr ; 55(Pt 2): 557-60, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10089378

RESUMO

Hepatitis B virus causes liver cirrhosis and hepatocellular cancer and is a major cause of death, particularly in Asia and sub-Saharan Africa. The virus consists of an inner core or nucleocapsid, which encloses the viral nucleic acid, with an outer lipid envelope containing surface-antigen proteins. The core protein, when expressed in E. coli, assembles into spherical shells containing 180 or 240 subunits, arranged with T = 3 or T = 4 icosahedral symmetry. The C-terminal region of the protein is involved in nucleic acid binding, and deletion of this region does not prevent capsid formation. C-terminally deleted hepatitis B core shells containing 240 subunits have been crystallized and data has been collected to 3. 6 A resolution from frozen crystals, using butanediol as a cryoprotectant. The crystals have C2 symmetry, with unit-cell parameters a = 538.0, b = 353.0, c = 369.6 A, beta = 132.3 degrees.


Assuntos
Antígenos do Núcleo do Vírus da Hepatite B/química , Temperatura Baixa , Cristalização , Cristalografia por Raios X , Antígenos do Núcleo do Vírus da Hepatite B/isolamento & purificação , Conformação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação
19.
Nature ; 386(6620): 88-91, 1997 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-9052786

RESUMO

Hepatitis B virus, a major human pathogen with an estimated 300 million carriers worldwide, can lead to cirrhosis and liver cancer in cases of chronic infection. The virus consists of an inner nucleocapsid or core, surrounded by a lipid envelope containing virally encoded surface proteins. The core protein, when expressed in bacteria, assembles into core shell particles, closely resembling the native core of the virus. Here we use electron cryomicroscopy to solve the structure of the core protein to 7.4 A resolution. Images of about 6,400 individual particles from 34 micrographs at different levels of defocus were combined, imposing icosahedral symmetry. The three-dimensional map reveals the complete fold of the polypeptide chain, which is quite unlike previously solved viral capsid proteins and is largely alpha-helical. The dimer clustering of subunits produces spikes on the surface of the shell, which consist of radial bundles of four long alpha-helices. Our model implies that the sequence corresponding to the immunodominant region of the core protein lies at the tip of the spike and also explains other properties of the core protein.


Assuntos
Antígenos do Núcleo do Vírus da Hepatite B/ultraestrutura , Microscopia Eletrônica/métodos , Conformação Proteica , Dobramento de Proteína , Capsídeo/química , Capsídeo/ultraestrutura , Linhagem Celular , Dimerização , Congelamento , Antígenos do Núcleo do Vírus da Hepatite B/química , Processamento de Imagem Assistida por Computador , Modelos Moleculares , Proteínas Recombinantes/química , Proteínas Recombinantes/ultraestrutura
20.
Biochem J ; 317 ( Pt 1): 235-45, 1996 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-8694770

RESUMO

The gene encoding the tetrameric malate dehydrogenase (MDH) in a thermophilic Bacillus species (BI) has been cloned in an Escherichia coli plasmid. The nucleotide sequence of the gene, the first to be elucidated for a tetrameric MDH, shows the MDH subunit to contain 312 amino acids and have a molecular mass of 33648 Da, which confirms the experimentally determined value of about 35 kDa. Like the genomic DNA of BI, the MDH gene is relatively AT-rich; this contrasts with the generally GC-rich nature of the DNA of thermophilic Bacillus species. Comparison of amino acid sequences reveals that BI MDH bears greater structural similarity to lactate dehydrogenases (LDHs) than to other (dimeric) MDHs. MDHs and LDHs resemble each other in catalytic mechanism and several other respects. However, whereas MDHs in the majority of organisms are dimers, the tetrameric structure is favoured among LDHs. The stronger structural resemblance that BI MDH has to LDHs than to the dimeric MDHs provides some explanation as to why Bacillus MDH, unlike most other MDHs, is tetrameric. A 1 kb fragment containing the BI MDH gene, produced in a PCR, has been cloned into a high-expression E. coli plasmid vector. BI MDH synthesized from this clone constitutes about 47% of the total protein in cell extracts of the E. coli strain carrying the clone. MDH purified from BI and that purified from the E. coli strain carrying the MDH gene clone appear to be identical proteins by several criteria. A number of characteristics of the MDH have been elucidated, including the molecular masses of the native enzyme and the subunit, N-terminal amino acid sequence, isoelectric point, pH optimum for activity, thermostability, stability to pH, urea and guanidinium chloride and several kinetic parameters. Whereas the MDH is a stable tetramer in the pH range 5-7, it appears to be converted into a stable dimer at pH 3.5. This suggests that the dimer is a stable intermediate in the dissociation of the tetramer to monomers at low pH.


Assuntos
Bacillus/genética , Genes Bacterianos , Malato Desidrogenase/química , Malato Desidrogenase/genética , Sequência de Aminoácidos , Bacillus/enzimologia , Sequência de Bases , Clonagem Molecular , Estabilidade Enzimática , Escherichia coli/genética , Código Genético , Temperatura Alta , L-Lactato Desidrogenase/genética , Malato Desidrogenase/biossíntese , Dados de Sequência Molecular , Conformação Proteica , Desnaturação Proteica , Proteínas Recombinantes/biossíntese , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos
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