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1.
J Virol ; 93(2)2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30381489

RESUMO

Epstein-Barr virus (EBV) is implicated in the pathogenesis of human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OSCC). EBV-associated cancers harbor a latent EBV infection characterized by a lack of viral replication and the expression of viral oncogenes. Cellular changes promoted by HPV are comparable to those shown to facilitate EBV latency, though whether HPV-positive cells support a latent EBV infection has not been demonstrated. Using a model of direct EBV infection into HPV16-immortalized tonsillar cells grown in organotypic raft culture, we showed robust EBV replication in HPV-negative rafts but little to no replication in HPV-immortalized rafts. The reduced EBV replication was independent of immortalization, as human telomerase-immortalized normal oral keratinocytes supported robust EBV replication. Furthermore, we observed reduced EBV lytic gene expression and increased expression of EBER1, a noncoding RNA highly expressed in latently infected cells, in the presence of HPV. The use of human foreskin keratinocyte rafts expressing the HPV16 E6 and/or E7 oncogene(s) (HPV E6 and E7 rafts) showed that E7 was sufficient to reduce EBV replication. EBV replication is dependent upon epithelial differentiation and the differentiation-dependent expression of the transcription factors KLF4 and PRDM1. While KLF4 and PRDM1 levels were unaltered, the expression levels of KLF4 transcriptional targets, including late differentiation markers, were reduced in HPV E6 and E7 rafts compared to their levels in parental rafts. However, the HPV E7-mediated block in EBV replication correlated with delayed expression of early differentiation markers. Overall, this study reveals an HPV16-mediated block in EBV replication, through E7, that may facilitate EBV latency and long-term persistence in the tumor context.IMPORTANCE Using a model examining the establishment of EBV infection in HPV-immortalized tissues, we showed an HPV-induced interruption of the normal EBV life cycle reminiscent of a latent EBV infection. Our data support the notion that a persistent EBV epithelial infection depends upon preexisting cellular alterations and suggest the ability of HPV to promote such changes. More importantly, these findings introduce a model for how EBV coinfection may influence HPV-positive (HPV-pos) OSCC pathogenesis. Latently EBV-infected epithelial cells, as well as other EBV-associated head-and-neck carcinomas, exhibit oncogenic phenotypes commonly seen in HPV-pos OSCC. Therefore, an HPV-induced shift in the EBV life cycle toward latency would not only facilitate EBV persistence but also provide additional viral oncogene expression, which can contribute to the rapid progression of HPV-pos OSCC. These findings provide a step toward defining a role for EBV as a cofactor in HPV-positive oropharyngeal tumors.


Assuntos
Células Epiteliais/virologia , Herpesvirus Humano 4/fisiologia , Papillomavirus Humano 16/metabolismo , Queratinócitos/citologia , Proteínas Oncogênicas Virais/metabolismo , Proteínas E7 de Papillomavirus/metabolismo , Proteínas Repressoras/metabolismo , Animais , Diferenciação Celular , Células Cultivadas , Técnicas de Cocultura , Células Epiteliais/citologia , Prepúcio do Pênis/citologia , Papillomavirus Humano 16/fisiologia , Humanos , Queratinócitos/virologia , Fator 4 Semelhante a Kruppel , Masculino , Camundongos , Células NIH 3T3 , Tonsila Palatina/citologia , Tonsila Palatina/virologia , Latência Viral , Replicação Viral
2.
Oral Dis ; 24(4): 497-508, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-28190296

RESUMO

Epstein-Barr virus (EBV) is a ubiquitous gamma-herpesvirus that establishes a lifelong persistent infection in the oral cavity and is intermittently shed in the saliva. EBV exhibits a biphasic life cycle, supported by its dual tropism for B lymphocytes and epithelial cells, which allows the virus to be transmitted within oral lymphoid tissues. While infection is often benign, EBV is associated with a number of lymphomas and carcinomas that arise in the oral cavity and at other anatomical sites. Incomplete association of EBV in cancer has questioned if EBV is merely a passenger or a driver of the tumorigenic process. However, the ability of EBV to immortalize B cells and its prevalence in a subset of cancers has implicated EBV as a carcinogenic cofactor in cellular contexts where the viral life cycle is altered. In many cases, EBV likely acts as an agent of tumor progression rather than tumor initiation, conferring malignant phenotypes observed in EBV-positive cancers. Given that the oral cavity serves as the main site of EBV residence and transmission, here we review the prevalence of EBV in oral malignancies and the mechanisms by which EBV acts as an agent of tumor progression.


Assuntos
Carcinoma de Células Escamosas/virologia , Infecções por Vírus Epstein-Barr/complicações , Herpesvirus Humano 4 , Estágios do Ciclo de Vida , Linfoma/virologia , Neoplasias Bucais/virologia , Herpesvirus Humano 4/crescimento & desenvolvimento , Humanos , Leucoplasia Pilosa/virologia , Neoplasias das Glândulas Salivares/virologia
3.
Eur J Paediatr Dent ; 18(4): 313-318, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29380618

RESUMO

AIM: The purpose of this chart review study was to investigate the common factors that exist in paediatric patients requiring a repeat dental treatment under general anaesthesia (GA2) within four years after the initial dental treatment under general anaesthesia (GA1). MATERIALS AND METHODS: The Electronic Health Records of one to 12 year-old children who received dental treatment under general anaesthesia (GA) between April 2004 and October 2009 were identified and analysed by a single examiner. Children who had GA2, within a four year period following GA1 were categorised as cases. Children who had only one dental treatment under GA were considered the control pool. Each case was matched to three controls based on sex and age range at GA1 of ± 6 months. Other recorded variables included: date of birth, date of GAs (GA1 and GA2 for cases; GA1 for controls), type of payment, dmfs before GA1, dental treatments provided under GA, return of 1-week post-GA1 follow-up, frequency of recare/recall visits following one-year post-GA1 visit and the type and frequency of post GA1 emergency visits. RESULTS: Out of 581 subjects, 29 (4.99%) cases were matched to 87 controls. Medically compromised patients had four times the risk of GA2. At GA1, cases received statistically significant less sealants (p=0.026), less extractions (p<0.0001), and more composite restorations (p=0.0002) compared to controls. CONCLUSION: Medically compromised children and children treated with more composites and fewer sealants and extractions at their initial dental treatment under general anaesthesia were more likely to have a repeat dental treatment under general anaesthesia within 4 years.


Assuntos
Anestesia Geral , Assistência Odontológica para Crianças/estatística & dados numéricos , Retratamento/estatística & dados numéricos , Estudos de Casos e Controles , Criança , Pré-Escolar , Registros Odontológicos , Feminino , Humanos , Lactente , Masculino , Estudos Retrospectivos
4.
PLoS One ; 17(6): e0269404, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35771867

RESUMO

Micropeptides, encoded from small open reading frames of 300 nucleotides or less, are hidden throughout mammalian genomes, though few functional studies of micropeptides in the brain are published. Here, we describe a micropeptide known as the Plasticity-Associated Neural Transcript Short (Pants), located in the 22q11.2 region of the human genome, the microdeletion of which conveys a high risk for schizophrenia. Our data show that Pants is upregulated in early adulthood in the mossy fiber circuit of the hippocampus, where it exerts a powerful negative effect on long-term potentiation (LTP). Further, we find that Pants is secreted from neurons, where it associates with synapses but is rapidly degraded with stimulation. Pants dynamically interacts with Rtn4/Nogo-A, a well-studied regulator of adult plasticity. Pants interaction with Nogo-A augments its influence over postsynaptic AMPA receptor clustering, thus gating plasticity at adult synapses. This work shows that neural micropeptides can act as architectural modules that increase the functional diversity of the known proteome.


Assuntos
Potenciação de Longa Duração , Plasticidade Neuronal , Adulto , Hipocampo/metabolismo , Humanos , Potenciação de Longa Duração/fisiologia , Plasticidade Neuronal/fisiologia , Proteínas Nogo/genética , Proteínas Nogo/metabolismo , Peptídeos/metabolismo , Sinapses/metabolismo
5.
Pain Res Manag ; 2020: 3284623, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33014213

RESUMO

Introduction: Pain is a universal human experience tied to an individual's health but difficult to understand. It is especially important in health emergencies. We performed a two-step quality improvement project to assess pain management by the SAMU ambulance service in Kigali, Rwanda, examining how pain is assessed and treated by ambulance staff to facilitate development of standardized guidelines of pain management in the prehospital setting, which did not exist at the time of the study. Materials and Methods: Deidentified ambulance service records from December 2012 to May 2016 were analyzed descriptively for patient demographics, emergency conditions, pain assessment, and medications given. Then, anonymized, semistructured interviews of ambulance staff were conducted until thematic saturation was achieved. Data were analyzed using a grounded theory approach. Results: SAMU managed 11,161 patients over the study period, of which 6,168 (55%) were documented as reporting pain and 5,010 (45%) received pain medications. Men had greater odds of receiving pain medications compared to women (OR = 3.8, 95% CI (3.5, 4.1), p < 0.01). Twenty interviews were conducted with SAMU staff. They indicated that patients communicate pain in different ways. They reported using informal ways to measure pain or a standardized granular numeric scale. The SAMU team reviewed these results and developed plans to modify practices. Conclusions: We reviewed the existing quality of pain management in the prehospital setting in Kigali, Rwanda, assessed the SAMU staff's perceptions of pain, and facilitated standardization of prehospital pain management through context-specific guidelines.


Assuntos
Serviços Médicos de Emergência/normas , Manejo da Dor/normas , Medição da Dor/normas , Dor/epidemiologia , Melhoria de Qualidade/normas , Adulto , Ambulâncias/normas , Estudos Transversais , Serviços Médicos de Emergência/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dor/diagnóstico , Manejo da Dor/métodos , Medição da Dor/métodos , Ruanda/epidemiologia
6.
Virology ; 537: 149-156, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31493653

RESUMO

Screening for human papillomavirus (HPV) integration into host cell chromosomes typically requires large amounts of time and reagents. We developed a rapid and sensitive assay based on exonuclease V (ExoV) and quantitative polymerase chain reaction (qPCR) to determine HPV genome configurations in cell lines and tissues. We established the assay using genomic DNA from cell lines known to harbor integrated or episomal HPV16. DNA was incubated with ExoV, which is specific for linear DNA, and the DNA fraction resistant to digestion was measured by qPCR. The percent of DNA resistant to ExoV digestion was calculated relative to undigested DNA for determination of episomal or integrated HPV16. The ExoV assay was accurate, capable of distinguishing episomal from integrated HPV16 in cell lines and tissues. Future applications of the ExoV assay may include screening of HPV genome configurations in the progression of HPV-associated cancers.


Assuntos
DNA Viral/análise , Exodesoxirribonuclease V/metabolismo , Papillomavirus Humano 16/genética , Plasmídeos , Provírus/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos , Integração Viral , Células Cultivadas , DNA Viral/genética , Papillomavirus Humano 16/crescimento & desenvolvimento , Humanos
7.
mBio ; 10(4)2019 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-31431547

RESUMO

Epstein-Barr virus (EBV) is a human herpesvirus that is associated with lymphomas as well as nasopharyngeal and gastric carcinomas. Although carcinomas account for almost 90% of EBV-associated cancers, progress in examining EBV's role in their pathogenesis has been limited by difficulty in establishing latent infection in nontransformed epithelial cells. Recently, EBV infection of human telomerase reverse transcriptase (hTERT)-immortalized normal oral keratinocytes (NOKs) has emerged as a model that recapitulates aspects of EBV infection in vivo, such as differentiation-associated viral replication. Using uninfected NOKs and NOKs infected with the Akata strain of EBV (NOKs-Akata), we examined changes in gene expression due to EBV infection and differentiation. Latent EBV infection produced very few significant gene expression changes in undifferentiated NOKs but significantly reduced the extent of differentiation-induced gene expression changes. Gene set enrichment analysis revealed that differentiation-induced downregulation of the cell cycle and metabolism pathways was markedly attenuated in NOKs-Akata relative to that in uninfected NOKs. We also observed that pathways induced by differentiation were less upregulated in NOKs-Akata. We observed decreased differentiation markers and increased suprabasal MCM7 expression in NOKs-Akata versus NOKs when both were grown in raft cultures, consistent with our transcriptome sequencing (RNA-seq) results. These effects were also observed in NOKs infected with a replication-defective EBV mutant (AkataΔRZ), implicating mechanisms other than lytic-gene-induced host shutoff. Our results help to define the mechanisms by which EBV infection alters keratinocyte differentiation and provide a basis for understanding the role of EBV in epithelial cancers.IMPORTANCE Latent infection by Epstein-Barr virus (EBV) is an early event in the development of EBV-associated carcinomas. In oral epithelial tissues, EBV establishes a lytic infection of differentiated epithelial cells to facilitate the spread of the virus to new hosts. Because of limitations in existing model systems, the effects of latent EBV infection on undifferentiated and differentiating epithelial cells are poorly understood. Here, we characterize latent infection of an hTERT-immortalized oral epithelial cell line (NOKs). We find that although EBV expresses a latency pattern similar to that seen in EBV-associated carcinomas, infection of undifferentiated NOKs results in differential expression of a small number of host genes. In differentiating NOKs, however, EBV has a more substantial effect, reducing the extent of differentiation and delaying the exit from the cell cycle. This effect may synergize with preexisting cellular abnormalities to prevent exit from the cell cycle, representing a critical step in the development of cancer.


Assuntos
Ciclo Celular/fisiologia , Diferenciação Celular , Células Epiteliais/metabolismo , Células Epiteliais/virologia , Infecções por Vírus Epstein-Barr/metabolismo , Herpesvirus Humano 4/genética , Divisão Celular , Linhagem Celular , Proliferação de Células , Células Epiteliais/patologia , Regulação Neoplásica da Expressão Gênica , Regulação Viral da Expressão Gênica , Genes Virais/genética , Herpesvirus Humano 4/patogenicidade , Humanos , Queratinócitos/metabolismo , Queratinócitos/patologia , Queratinócitos/virologia , Componente 7 do Complexo de Manutenção de Minicromossomo/metabolismo , Neoplasias Gástricas , Telomerase/metabolismo , Transcriptoma , Ativação Viral , Latência Viral
8.
Virus Res ; 231: 139-147, 2017 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-27826043

RESUMO

The etiological role of human papillomavirus (HPV) in anogenital tract and head and neck cancers is well established. However, only a low percentage of HPV-positive women develop cancer, indicating that HPV is necessary but not sufficient in carcinogenesis. Several biological and environmental cofactors have been implicated in the development of HPV-associated carcinoma that include immune status, hormonal changes, parity, dietary habits, tobacco usage, and co-infection with other sexually transmissible agents. Such cofactors likely contribute to HPV persistent infection through diverse mechanisms related to immune control, efficiency of HPV infection, and influences on tumor initiation and progression. Conversely, HPV co-infection with other factors may also harbor anti-tumor effects. Here, we review epidemiological and experimental studies investigating human immunodeficiency virus (HIV), herpes simplex virus (HSV) 1 and 2, human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), BK virus (BKV), JC virus (JCV), and adeno-associated virus (AAV) as viral cofactors in or therapeutic factors against the development of genital and oral HPV-associated carcinomas.


Assuntos
Neoplasias do Ânus/virologia , Neoplasias dos Genitais Femininos/virologia , Neoplasias de Cabeça e Pescoço/virologia , Papillomaviridae/patogenicidade , Infecções por Papillomavirus/virologia , Neoplasias do Ânus/genética , Neoplasias do Ânus/imunologia , Neoplasias do Ânus/patologia , Vírus BK/genética , Vírus BK/crescimento & desenvolvimento , Vírus BK/patogenicidade , Carcinogênese/genética , Carcinogênese/imunologia , Carcinogênese/patologia , Coinfecção , Citomegalovirus/genética , Citomegalovirus/crescimento & desenvolvimento , Citomegalovirus/patogenicidade , Dependovirus/genética , Dependovirus/crescimento & desenvolvimento , Dependovirus/patogenicidade , Feminino , Neoplasias dos Genitais Femininos/genética , Neoplasias dos Genitais Femininos/imunologia , Neoplasias dos Genitais Femininos/patologia , HIV/genética , HIV/crescimento & desenvolvimento , HIV/patogenicidade , Neoplasias de Cabeça e Pescoço/genética , Neoplasias de Cabeça e Pescoço/imunologia , Neoplasias de Cabeça e Pescoço/patologia , Herpesvirus Humano 1/genética , Herpesvirus Humano 1/crescimento & desenvolvimento , Herpesvirus Humano 1/patogenicidade , Herpesvirus Humano 2/genética , Herpesvirus Humano 2/crescimento & desenvolvimento , Herpesvirus Humano 2/patogenicidade , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/crescimento & desenvolvimento , Herpesvirus Humano 4/patogenicidade , Humanos , Vírus JC/genética , Vírus JC/crescimento & desenvolvimento , Vírus JC/patogenicidade , Papillomaviridae/genética , Papillomaviridae/crescimento & desenvolvimento , Infecções por Papillomavirus/genética , Infecções por Papillomavirus/imunologia , Infecções por Papillomavirus/patologia , Fatores de Proteção , Fatores de Risco
9.
Nucleic Acids Res ; 29(10): 2163-70, 2001 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-11353086

RESUMO

In this study, we characterize the thermodynamics of hybridization, binding kinetics and conformations of four ribose-modified (2'-fluoro, 2'-O-propyl, 2'-O-methoxyethyl and 2'-O-aminopropyl) decameric mixed-sequence oligonucleotides. Hybridization to the complementary non-modified DNA or RNA decamer was probed by fluorescence and circular-dichroism spectroscopy and compared to the same duplex formed between two non-modified strands. The thermal melting points of DNA-DNA duplexes were increased by 1.8, 2.2, 0.3 and 1.3 degrees C for each propyl, methoxyethyl, aminopropyl and fluoro modification, respectively. In the case of DNA-RNA duplexes, the melting points were increased by 3.1, 4.1 and 1.0 degrees C for each propyl, methoxyethyl and aminopropyl modification, respectively. The high stability of the duplexes formed with propyl-, methoxyethyl- and fluoro-modified oligonucleotides correlated with high preorganization in these single-strands. Despite higher thermodynamic duplex stability, hybridization kinetics to complementary DNA or RNA was slower for propyl- and methoxyethyl-modified oligonucleotides than for the non-modified control. In contrast, the positively-charged aminopropyl-modified oligonucleotide showed rapid binding to the complementary DNA or RNA.


Assuntos
Pareamento de Bases , Oligonucleotídeos/química , Oligonucleotídeos/metabolismo , Ribose/metabolismo , Sequência de Bases , Dicroísmo Circular , DNA/química , DNA/genética , DNA/metabolismo , Terapia Genética , Cinética , Desnaturação de Ácido Nucleico , Hibridização de Ácido Nucleico , Oligonucleotídeos/genética , RNA/química , RNA/genética , RNA/metabolismo , Ribose/química , Espectrometria de Fluorescência , Eletricidade Estática , Temperatura , Termodinâmica
10.
Biochim Biophys Acta ; 1479(1-2): 214-24, 2000 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-10862971

RESUMO

Flavodoxins are proteins with an alpha/beta doubly wound topology that mediate electron transfer through a non-covalently bound flavin mononucleotide (FMN). The FMN moiety binds strongly to folded flavodoxin (K(D)=0.1 nM, oxidized FMN). To study the effect of this organic cofactor on the conformational stability, we have characterized apo and holo forms of Desulfovibrio desulfuricans flavodoxin by GuHCl-induced denaturation. The unfolding reactions for both holo- and apo-flavodoxin are reversible. However, the unfolding curves monitored by far-UV circular dichroism and fluorescence spectroscopy do not coincide. For both apo- and holo-flavodoxin, a native-like intermediate (with altered tryptophan fluorescence but secondary structure as the folded form) is present at low GuHCl concentrations. There is no effect on the flavodoxin stability imposed by the presence of the FMN cofactor (DeltaG=20(+/-2) and 19(+/-1) kJ/mol for holo- and apo-flavodoxin, respectively). A thermodynamic cycle, connecting FMN binding to folded and unfolded flavodoxin with the unfolding free energies for apo- and holo-flavodoxin, suggests that the binding strength of FMN to unfolded flavodoxin must be very high (K(D)=0.2 nM). In agreement, we discovered that the FMN remains coordinated to the polypeptide upon unfolding.


Assuntos
Desulfovibrio/química , Flavodoxina/química , Dicroísmo Circular , Mononucleotídeo de Flavina/metabolismo , Flavodoxina/metabolismo , Modelos Moleculares , Conformação Proteica , Desnaturação Proteica , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta
11.
J Mol Biol ; 301(4): 769-73, 2000 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-10966783

RESUMO

Cytochrome c(553) (cyt c(553)) from Desulfovibrio vulgaris is a small helical heme protein that displays apparent two-state equilibrium-unfolding behavior. The covalently attached heme is low-spin, ligated by Met and His residues, in the native state but becomes high-spin upon unfolding at pH 7. Here, we show that in contrast to other c-type heme proteins, where misligations in the unfolded states are prominent, cyt c(553) refolding kinetics at pH 7 proceeds rapidly without detectable intermediates. The extrapolated folding rate constant in water for oxidized cyt c(553) matches exactly that predicted from the cyt c(553) native-state topology: 5300 s(-1 )(experimental) versus 5020 s(-1) (predicted). We therefore conclude that the presence of the oxidized cofactor does not affect the intrinsic formation speed of the cyt c(553 )structural motif.


Assuntos
Grupo dos Citocromos c/química , Grupo dos Citocromos c/metabolismo , Desulfovibrio vulgaris/química , Dobramento de Proteína , Guanidina/farmacologia , Histidina/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Metionina/metabolismo , Modelos Moleculares , Oxirredução , Desnaturação Proteica/efeitos dos fármacos , Renaturação Proteica/efeitos dos fármacos , Termodinâmica , Água/metabolismo
12.
Arch Intern Med ; 147(10): 1821, 1987 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3116961

RESUMO

Phenytoin, administered by suspension into a feeding tube through which continuous enteral feedings are being given, is very poorly absorbed. There appears to be very little information regarding this potentially serious problem in the general medical literature. Commonly used doses of phenytoin (300 to 500 mg/d) may result in almost undetectable serum levels. Therapeutic phenytoin levels may be obtained if a very large dose of the drug is given. Our patient required 1800 mg daily in two divided doses to get a serum phenytoin level of 9 micrograms/mL. Commonly used enteral feedings were being delivered by way of a continuous infusion pump. We found one enteral feeding product that did not severely impair the absorption of phenytoin. The mechanism by which enteral feedings impair phenytoin absorption is unknown.


Assuntos
Nutrição Enteral/efeitos adversos , Fenitoína/administração & dosagem , Hemorragia Cerebral/tratamento farmacológico , Feminino , Humanos , Absorção Intestinal , Pessoa de Meia-Idade , Fenitoína/farmacocinética , Suspensões
13.
Protein Sci ; 9(11): 2109-17, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11152122

RESUMO

Chaperonins cpn60/cpn10 (GroEL/GroES in Escherichia coli) assist folding of nonnative polypeptides. Folding of the chaperonins themselves is distinct in that it entails assembly of a sevenfold symmetrical structure. We have characterized denaturation and renaturation of the recombinant human chaperonin 10 (cpn10), which forms a heptamer. Denaturation induced by chemical denaturants urea and guanidine hydrochloride (GuHCl) as well as by heat was monitored by tyrosine fluorescence, far-ultraviolet circular dichroism, and cross-linking; all denaturation reactions were reversible. GuHCl-induced denaturation was found to be cpn10 concentration dependent, in accord with a native heptamer to denatured monomer transition. In contrast, urea-induced denaturation was not cpn10 concentration dependent, suggesting that under these conditions cpn10 heptamers denature without dissociation. There were no indications of equilibrium intermediates, such as folded monomers, in either denaturant. The different cpn10 denatured states observed in high [GuHCl] and high [urea] were supported by cross-linking experiments. Thermal denaturation revealed that monomer and heptamer reactions display the same enthalpy change (per monomer), whereas the entropy-increase is significantly larger for the heptamer. A thermodynamic cycle for oligomeric cpn10, combining chemical denaturation with the dissociation constant in absence of denaturant, shows that dissociated monomers are only marginally stable (3 kJ/mol). The thermodynamics for co-chaperonin stability appears conserved; therefore, instability of the monomer could be necessary to specify the native heptameric structure.


Assuntos
Chaperonina 10/química , Desnaturação Proteica , Chaperonina 10/metabolismo , Dicroísmo Circular , Citrato (si)-Sintase/metabolismo , Reagentes de Ligações Cruzadas/farmacologia , Relação Dose-Resposta a Droga , Escherichia coli/metabolismo , Guanidina/farmacologia , Temperatura Alta , Humanos , Mitocôndrias/química , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Termodinâmica , Tirosina/metabolismo , Raios Ultravioleta , Ureia/farmacologia
14.
Protein Sci ; 10(8): 1539-48, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11468351

RESUMO

The ferredoxin from the thermophilic archaeon Acidianus ambivalens is a small monomeric seven-iron protein with a thermal midpoint (T(m)) of 122 degrees C (pH 7). To gain insight into the basis of its thermostability, we have characterized unfolding reactions induced chemically and thermally at various pHs. Thermal unfolding of this ferredoxin, in the presence of various guanidine hydrochloride (GuHCl) concentrations, yields a linear correlation between unfolding enthalpies (DeltaH[T(m)]) and T(m) from which an upper limit for the heat capacity of unfolding (DeltaC(P)) was determined to be 3.15 +/- 0.1 kJ/(mole * K). Only by the use of the stronger denaturant guanidine thiocyanate (GuSCN) is unfolding of A. ambivalens ferredoxin at pH 7 (20 degrees C) observed ([GuSCN](1/2) = 3.1 M; DeltaG(U)[H(2)O] = 79 +/- 8 kJ/mole). The protein is, however, less stable at low pH: At pH 2.5, T(m) is 64 +/- 1 degrees C, and GuHCl-induced unfolding shows a midpoint at 2.3 M (DeltaG(U)[H(2)O] = 20 +/- 1 kJ/mole). These results support that electrostatic interactions contribute significantly to the stability. Analysis of the three-dimensional molecular model of the protein shows that there are several possible ion pairs on the surface. In addition, ferredoxin incorporates two iron-sulfur clusters and a zinc ion that all coordinate deprotonated side chains. The zinc remains bound in the unfolded state whereas the iron-sulfur clusters transiently form linear three-iron species (in pH range 2.5 to 10), which are associated with the unfolded polypeptide, before their complete degradation.


Assuntos
Proteínas Arqueais/química , Ferredoxinas/química , Sulfolobaceae/química , Dicroísmo Circular , Desinfetantes/química , Guanidina/química , Guanidinas/química , Concentração de Íons de Hidrogênio , Ferro/química , Modelos Moleculares , Desnaturação Proteica , Dobramento de Proteína , Eletricidade Estática , Enxofre/química , Temperatura , Termodinâmica , Tiocianatos/química , Zinco/química
15.
FEBS Lett ; 470(2): 203-6, 2000 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-10734234

RESUMO

Native myoglobin (Mb) consists of two populations which differ in the orientation of the heme by 180 degrees rotation (as verified by nuclear magnetic resonance) but have identical absorption spectra and equilibrium-thermodynamic stability. Here, we report that these two fractions of native oxidized Mb (from horse) both unfold and refold (chemical denaturant, pH 7, 20 degrees C) in two parallel kinetic reactions with rate constants differing 10-fold. In accord, the oxidized heme remains coordinated to unfolded horse Mb in up to 4 M guanidine hydrochloride (pH 7, 20 degrees C).


Assuntos
Heme/metabolismo , Metamioglobina/química , Metamioglobina/metabolismo , Dobramento de Proteína , Renaturação Proteica , Animais , Apoproteínas/química , Apoproteínas/metabolismo , Dicroísmo Circular , Relação Dose-Resposta a Droga , Fluorescência , Guanidina/farmacologia , Cavalos , Cinética , Mioglobina/química , Mioglobina/metabolismo , Desnaturação Proteica/efeitos dos fármacos , Rotação , Termodinâmica , Triptofano/metabolismo , Baleias
16.
Obstet Gynecol ; 96(5 Pt 2): 804-6, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11094212

RESUMO

BACKGROUND: Heparin resistance is the need for more than 35,000 units of heparin per 24 hours to achieve therapeutic activated partial thromboplastin time (APTT) values. Elevated factor VIII can cause apparent heparin resistance by suppressing the APTT result without inhibiting the antithrombotic effect of heparin. CASE: A 41-year-old gravida 2 para 0 presented at 25 weeks of a twin gestation with a deep venous thrombosis that required unusually high doses of heparin, resulting in hematuria. Apparent heparin resistance caused by elevated factor VIII was diagnosed, and the heparin dose was appropriately decreased with anti-Xa heparin monitoring. The deep venous thrombosis and hematuria resolved. CONCLUSION: Factor VIII rises significantly during pregnancy, and can cause apparent heparin resistance. When this occurs, anti-Xa heparin levels are superior to APTT for monitoring heparin therapy.


Assuntos
Anticoagulantes/administração & dosagem , Fator VIII/análise , Heparina/administração & dosagem , Complicações Cardiovasculares na Gravidez/tratamento farmacológico , Trombose Venosa/tratamento farmacológico , Adulto , Feminino , Hematúria/etiologia , Humanos , Tempo de Tromboplastina Parcial , Gravidez , Complicações Cardiovasculares na Gravidez/sangue , Gêmeos
17.
Vet Immunol Immunopathol ; 1(4): 329-41, 1980 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15615051

RESUMO

Bovine IgG1, IgG2, IgA, and IgM were measured in the serum and lacteal secretions of six cows from 10 days prepartum to 240 days of lactation. Immunoglobulins in lacteal secretions were expressed in units of concentration (mg/ml) as well as in total daily output. All isotypes were selectively accumulated during colostrum formation. The rate of IgG1 accumulation decreased rapidly after calving; this decrease corresponded to a return to normal serum levels of this immunoglobulin. Selective accumulation of IgA > IgM > IgG1 was maintained throughout lactation, but IgG2 showed no selective accumulation beyond 5 days postpartum. In serum, IgA and IgM levels were elevated at parturition and showed a significant decrease postpartum. Increases in serum IgA levels 60 days postpartum corresponded to a rise in lacteal concentration. The concentration of all immunoglobulins increased during late lactation, coincident with a major reduction in milk yield. Six strains of mastitis-causing organisms were cultured during the period of the experiment; however, none resulted in clinical mastitis or showed an effect on immunoglobulin secretion.


Assuntos
Bovinos/imunologia , Imunoglobulinas/sangue , Lactação/imunologia , Leite/imunologia , Animais , Feminino , Albumina Sérica/imunologia
18.
Crit Care Clin ; 7(3): 533-54, 1991 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1863882

RESUMO

Anticoagulation is being used increasingly in the critical care areas. Thrombolytic therapy is now commonly used in emergency departments and coronary care units for treatment of AMI. Heparin therapy for unstable angina and for a 48 to 72 hour period following thrombolytic therapy for AMI is becoming commonplace. Beginning warfarin therapy concomitantly with heparin to decrease the total duration of heparin and the duration of hospital stay for DVT therapy is encouraged. The use of low-dose warfarin to prevent DVT in hip surgery, improve catheter patency, and prevent catheter-related subclavian thrombosis is increasing. Along with the increased use of anticoagulation must come a greater appreciation of the complications associated with the agents used, and of how to prevent or treat the hemorrhagic or thrombotic morbidity that may arise. Acute hemorrhage with thrombolytic agents must be recognized and the immediate implementation of conservative and aggressive measures begun. Heparin-induced thrombocytopenia with thrombosis is an often-unrecognized problem that may occur in 1% to 2% of heparin recipients and result in limb amputations. A delayed onset (6-10 days) requires frequent platelet counts for early diagnosis and treatment. The resurgence of warfarin use for prevention of cardiovascular and cerebrovascular disorders demands observation for skin necrosis from protein C and S inhibition. Early recognition of symptoms and syndromes associated with organ system hemorrhage in patients receiving chronic anticoagulation is imperative. The use of antagonists, such as protamine sulfate for heparin, vitamin K1 for warfarin, and antifibrinolytic drugs for thrombolytic agents, may be necessary in treating hemorrhagic events. However, their use may worsen the thromboembolic event initially treated.


Assuntos
Anticoagulantes/efeitos adversos , Cuidados Críticos , Fibrinolíticos/efeitos adversos , Terapia Trombolítica/efeitos adversos , Anticoagulantes/uso terapêutico , Contraindicações , Feminino , Fibrinolíticos/farmacologia , Heparina/efeitos adversos , Heparina/uso terapêutico , Humanos , Unidades de Terapia Intensiva , Gravidez , Varfarina/efeitos adversos , Varfarina/farmacocinética , Varfarina/uso terapêutico
19.
Med Hypotheses ; 52(1): 69-75, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10342674

RESUMO

Lack of complete concordance for schizophrenia in monozygotic twins has been interpreted as indicative of non-genetic cofactors in transmission of the illness. We present an alternative hypothesis that can parsimoniously explain, using known genetic mechanisms, the heredity pattern, the phenotypic spectrum and the biological abnormalities found in schizophrenia. The inheritance of a single recessive mutated allele of a gene crucial in brain development if followed by a somatic mutation in the normal allele during critical periods of brain development could result in developmental abnormalities that are expressed behaviorally as schizophrenic illness. Acquisition of this somatic mutation is likely enhanced during periods of intense cell division; therefore, the window of opportunity would be restricted to key periods in neurodevelopment. The somatic mutation may not always occur, thus explaining the variability of expression seen in the clinical population. Because the single allele mutation is still transmissible, the equal incidence of schizophrenia in the offspring of monozygotic twins discordant for the disease could also be explained. This possibility has implications for the development of genetic models and the source of genetic material for studies isolating the gene(s) of schizophrenia.


Assuntos
Modelos Genéticos , Esquizofrenia/genética , Encéfalo/anormalidades , Encéfalo/crescimento & desenvolvimento , Doenças em Gêmeos/genética , Genes Recessivos , Genes Supressores de Tumor , Humanos , Modelos Biológicos , Mutação , Proto-Oncogenes , Gêmeos Monozigóticos
20.
Am J Ment Retard ; 93(6): 657-68, 1989 May.
Artigo em Inglês | MEDLINE | ID: mdl-2719848

RESUMO

Concerns involved with prescription of psychotropic medication to persons with developmental disabilities to ameliorate maladaptive behavior were described. Responses to a national survey of state agencies regarding statutes, regulations, and operating procedures for initiating and monitoring psychotropic drug regimens were examined. The survey showed that most states had more rules and regulations for persons in institutions than in community settings. It also showed that some states have initiated rules similar to court-ordered guidelines for assessing tardive dyskinesia, restricting the use of antiparkinson drugs and polypharmacy, and implementing periodic drug interruptions. Recommendations were made based on these findings.


Assuntos
Política de Saúde , Deficiência Intelectual/tratamento farmacológico , Psicotrópicos/administração & dosagem , Quimioterapia Combinada , Discinesia Induzida por Medicamentos/diagnóstico , Humanos , Consentimento Livre e Esclarecido/legislação & jurisprudência , Legislação de Medicamentos , Comitê de Profissionais , Estados Unidos
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