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1.
Phys Rev Lett ; 129(27): 275001, 2022 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-36638294

RESUMO

We present measurements of ice-ablator mix at stagnation of inertially confined, cryogenically layered capsule implosions. An ice layer thickness scan with layers significantly thinner than used in ignition experiments enables us to investigate mix near the inner ablator interface. Our experiments reveal for the first time that the majority of atomically mixed ablator material is "dark" mix. It is seeded by the ice-ablator interface instability and located in the relatively cooler, denser region of the fuel assembly surrounding the fusion hot spot. The amount of dark mix is an important quantity as it is thought to affect both fusion fuel compression and burn propagation when it turns into hot mix as the burn wave propagates through the initially colder fuel region surrounding an igniting hot spot. We demonstrate a significant reduction in ice-ablator mix in the hot-spot boundary region when we increase the initial ice layer thickness.

2.
Phys Rev Lett ; 126(2): 025001, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33512226

RESUMO

Inertial confinement fusion seeks to create burning plasma conditions in a spherical capsule implosion, which requires efficiently absorbing the driver energy in the capsule, transferring that energy into kinetic energy of the imploding DT fuel and then into internal energy of the fuel at stagnation. We report new implosions conducted on the National Ignition Facility (NIF) with several improvements on recent work [Phys. Rev. Lett. 120, 245003 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.245003; Phys. Rev. E 102, 023210 (2020)PRESCM2470-004510.1103/PhysRevE.102.023210]: larger capsules, thicker fuel layers to mitigate fuel-ablator mix, and new symmetry control via cross-beam energy transfer; at modest velocities, these experiments achieve record values for the implosion energetics figures of merit as well as fusion yield for a NIF experiment.

3.
Phys Rev Lett ; 126(2): 025002, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33512229

RESUMO

Inertial confinement fusion implosions must achieve high in-flight shell velocity, sufficient energy coupling between the hot spot and imploding shell, and high areal density (ρR=∫ρdr) at stagnation. Asymmetries in ρR degrade the coupling of shell kinetic energy to the hot spot and reduce the confinement of that energy. We present the first evidence that nonuniformity in the ablator shell thickness (∼0.5% of the total thickness) in high-density carbon experiments is a significant cause for observed 3D ρR asymmetries at the National Ignition Facility. These shell-thickness nonuniformities have significantly impacted some recent experiments leading to ρR asymmetries on the order of ∼25% of the average ρR and hot spot velocities of ∼100 km/s. This work reveals the origin of a significant implosion performance degradation in ignition experiments and places stringent new requirements on capsule thickness metrology and symmetry.

4.
Phys Rev Lett ; 120(24): 245003, 2018 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-29956968

RESUMO

A series of cryogenic, layered deuterium-tritium (DT) implosions have produced, for the first time, fusion energy output twice the peak kinetic energy of the imploding shell. These experiments at the National Ignition Facility utilized high density carbon ablators with a three-shock laser pulse (1.5 MJ in 7.5 ns) to irradiate low gas-filled (0.3 mg/cc of helium) bare depleted uranium hohlraums, resulting in a peak hohlraum radiative temperature ∼290 eV. The imploding shell, composed of the nonablated high density carbon and the DT cryogenic layer, is, thus, driven to velocity on the order of 380 km/s resulting in a peak kinetic energy of ∼21 kJ, which once stagnated produced a total DT neutron yield of 1.9×10^{16} (shot N170827) corresponding to an output fusion energy of 54 kJ. Time dependent low mode asymmetries that limited further progress of implosions have now been controlled, leading to an increased compression of the hot spot. It resulted in hot spot areal density (ρr∼0.3 g/cm^{2}) and stagnation pressure (∼360 Gbar) never before achieved in a laboratory experiment.

5.
Ir Med J ; 111(2): 688, 2018 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-29952437

RESUMO

Parenteral Nutrition (PN) is a life-saving treatment used for patients with Intestinal Failure (IF). PN is complex and demands highly specialised care to avoid serious complications in the home setting. All tertiary centres in the Republic of Ireland (ROI) were contacted to assess the prevalence of IF requiring PN and complications, over a one year period. Sixty-seven patients were treated across 15 centres: a period prevalence of 14.6 and 9.6 patients per million for long-term PN and home PN respectively. Three-quarters of patients experienced at least one major complication with 18% mortality rate over the study period. There were 2.86 admissions per HPN patient, each lasting mean 13.4 days. One-third experienced catheter-related infections. There was a reduced length of stay during emergency re-admissions in high volume centres (mean 31 v 43 days, p=0.17). The establishment of a National Centre for IF/HPN in ROI is integral to reducing PN-associated complications.


Assuntos
Enteropatias/epidemiologia , Enteropatias/terapia , Intestinos , Nutrição Parenteral no Domicílio/estatística & dados numéricos , Adulto , Infecções Relacionadas a Cateter/epidemiologia , Humanos , Irlanda/epidemiologia , Nutrição Parenteral no Domicílio/efeitos adversos , Nutrição Parenteral no Domicílio/mortalidade , Prevalência , Estudos Retrospectivos , Centros de Atenção Terciária/estatística & dados numéricos
6.
Ir Med J ; 109(6): 422, 2016 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-27814439

RESUMO

A recent systematic review and meta-analysis shows that appropriate use of oral nutrition supplements (ONS) in community patients is associated with a significant reduction in hospitalisations. Given higher use of acute care resource by malnourished versus normally nourished patients, this paper examines the potential to reduce bed utilisation by applying these results to Irish inpatient and malnutrition prevalence data. In 2013, adults admitted to hospital with medium or high malnutrition risk scores used an estimated 36% of adult acute inpatient bed days. Targeted use of ONS in community patients might reduce hospitalisation by 168,438 adult bed days per year, equivalent to 460 beds per day. This is particularly important, given high bed occupancy rates and twelve month daily averages of 254 patients on trolleys. Relevant stakeholders should consider strategies to ensure effective ONS use with a view to improving outcomes and reducing pressure on the acute care system.


Assuntos
Ocupação de Leitos/estatística & dados numéricos , Desnutrição/diagnóstico , Suplementos Nutricionais/estatística & dados numéricos , Hospitalização/estatística & dados numéricos , Hospitais , Humanos , Irlanda/epidemiologia , Desnutrição/epidemiologia , Desnutrição/terapia , Estado Nutricional , Prevalência
7.
Clin Med (Lond) ; 11(1): 11-6, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21404775

RESUMO

Transient loss of consciousness (T-LOC), or blackout, is common in acute medicine. Clinical skills are not done well, with at least 74,000 patients misdiagnosed and mistreated for epilepsy in England alone. The aim of this study was to provide a rapid, structured assessment and an electrocardiogram (ECG) for patients with blackouts, aiming to identify high risk, reduce misdiagnoses, reduce hospital admission rates for low-risk patients, diagnose and treat where appropriate, and also provide onward specialist referral. The majority of patients had syncope, and very few had epilepsy. A high proportion had an abnormal ECG. A specialist-nurse-led rapid access blackouts triage clinic (RABTC) provided rapid effective triage for risk, a comprehensive assessment format, direct treatment for many patients, and otherwise a prompt appropriate onward referral. Rapid assessment through a RABTC reduced re-admissions with blackouts. Widespread use of the web-based blackouts tool could provide the NHS with a performance map. The U.K. has low rates of pacing compared to Western Europe, which RABTCs might help correct. The RABTC sits between first responders and specialist referral, providing clinical assessment and ECG in all cases, and referral where appropriate.


Assuntos
Instituições de Assistência Ambulatorial/organização & administração , Epilepsia/diagnóstico , Síncope/diagnóstico , Triagem/métodos , Inconsciência/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Erros de Diagnóstico , Epilepsia/complicações , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Encaminhamento e Consulta , Medição de Risco , Síncope/complicações , Inconsciência/etiologia , Adulto Jovem
8.
CBE Life Sci Educ ; 19(3): ar30, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32644001

RESUMO

As we strive to make science education more inclusive, more research is needed to fully understand gender gaps in academic performance and in-class participation in the life sciences. Studies suggest that male voices dominate introductory biology courses, but no studies have been done on upper-level courses. Results on achievement gender gaps in biology vary and often conflict, and no studies have been done on the correlation between participation and academic performance gaps. We observed 34 life sciences courses at all levels at a large private university. Overall, males were more likely to participate than their female peers, but these gender gaps varied from class to class. Females participated more in classes in which the instructor called on most hands that were raised or in classes with more females in attendance. Performance gender gaps also varied by classroom, but female final course grades were as much as 0.2 SD higher in classes with a female instructor and/or a female student majority. Gender gaps in participation and final course grades were positively correlated, but this could be solely because female students are more likely to both participate more and earn higher grades in classes with many females in attendance.


Assuntos
Disciplinas das Ciências Biológicas , Avaliação Educacional , Desempenho Acadêmico , Logro , Feminino , Humanos , Masculino , Grupo Associado , Fatores Sexuais , Estudantes , Universidades
9.
Diabetologia ; 52(10): 2117-21, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19662379

RESUMO

AIMS/HYPOTHESIS: Circulating beta-carotene levels are inversely associated with risk of type 2 diabetes, but the causal direction of this association is not certain. In this study we used a Mendelian randomisation approach to provide evidence for or against the causal role of the antioxidant vitamin beta-carotene in type 2 diabetes. METHODS: We used a common polymorphism (rs6564851) near the BCMO1 gene, which is strongly associated with circulating beta-carotene levels (p = 2 x 10(-24)), with each G allele associated with a 0.27 standard deviation increase in levels. We used data from the InCHIANTI and Uppsala Longitudinal Study of Adult Men (ULSAM) studies to estimate the association between beta-carotene levels and type 2 diabetes. We next used a triangulation approach to estimate the expected effect of rs6564851 on type 2 diabetes risk and compared this with the observed effect using data from 4549 type 2 diabetes patients and 5579 controls from the Diabetes Genetics Replication And Meta-analysis (DIAGRAM) Consortium. RESULTS: A 0.27 standard deviation increase in beta-carotene levels was associated with an OR of 0.90 (95% CI 0.86-0.95) for type 2 diabetes in the InCHIANTI study. This association was similar to that of the ULSAM study (OR 0.90 [0.84-0.97]). In contrast, there was no association between rs6564851 and type 2 diabetes (OR 0.98 [0.93-1.04], p = 0.58); this effect size was also smaller than that expected, given the known associations between rs6564851 and beta-carotene levels, and the associations between beta-carotene levels and type 2 diabetes. CONCLUSIONS/INTERPRETATION: Our findings in this Mendelian randomisation study are in keeping with randomised controlled trials suggesting that beta-carotene is not causally protective against type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/genética , beta Caroteno/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Polimorfismo de Nucleotídeo Único/genética , beta-Caroteno 15,15'-Mono-Oxigenase/genética
10.
Science ; 231(4738): 589-94, 1986 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-3003905

RESUMO

Comparison of HTLV-III, the putative AIDS virus, with other related viruses, may help to reveal more about the origin of AIDS in humans. In this study, the nucleotide sequence of the gag and pol genes of an equine infectious anemia virus (EIAV) proviral DNA clone was determined. The sequence was compared with that of HTLV-III and of visna, a pathogenic lentivirus of sheep. The results show that these viruses constitute a family clearly distinct from that of the type C viruses or the BLV-HTLV-I and -II group. Within the family, EIAV, HTLV-III, and visna appear to be equally divergent from a common evolutionary ancestor.


Assuntos
Deltaretrovirus/genética , Genes Virais , Vírus da Anemia Infecciosa Equina/genética , Vírus Visna-Maedi/genética , Animais , Sequência de Bases , Códon , DNA Viral/genética , Cavalos , Humanos , Camundongos
11.
Science ; 204(4395): 841-2, 1979 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-87013

RESUMO

A type C retrovirus was isolated from a continuous cell line established from a spontaneous esophageal carcinoma of a rhesus monkey (Macaca mulata) by prolonged cocultivation with canine cells. A DNA transcript of the viral RNA hybridized to a high level and kinetic analysis indicated the presence of multiple copies of the viral genome in rhesus monkey DNA, showing that the virus is endogenous in this species. The rhesus monkey virus closely resembles, in several respects, an endogenous type C virus previously isolated from stumptailed macques (Macaca arctoides), aa species closely related to rhesus monkeys.


Assuntos
Macaca mulatta/microbiologia , Macaca/microbiologia , Retroviridae/isolamento & purificação , Animais , Haplorrinos , Hibridização de Ácido Nucleico , RNA Viral/análise , DNA Polimerase Dirigida por RNA/metabolismo , Retroviridae/enzimologia , Retroviridae/ultraestrutura , Proteínas Virais/análise , Proteínas Virais/imunologia
12.
J Med Entomol ; 45(2): 314-25, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18402148

RESUMO

The spatial heterogeneity of questing Ixodes ricinus (L.) (Acari: Ixodidae) within endemic areas in Great Britain is well established. Their presence is acutely responsive to blood host availability and their ability to maintain water balance, which are in turn governed by a variety of ecological and environmental factors. This article details the findings of a 3-yr study on the Gower peninsula, south Wales, which investigated the contribution of such factors (both ground- and geographic information systems [GIS] -derived) for predicting the presence of questing I. ricinus (Q(P)), at a local scale. Statistically significant univariate associations were found between Q(P) and calcareous/ neutral grassland and heathland habitats, particularly those grazed by livestock, and various factors that intuitively promote tick survival. For example, topographical features, such as certain aspects, that reduce exposure to cold northerly winds and the hot midday sun, favored Q(P). Similarly, positive associations were found with substrata composed of less permeable soil types and less permeable superficial/bedrock geologies that promote a moist microhabitat and reduce the likelihood of desiccation. Q(P) was also higher in areas of high soil moisture. This study highlighted a number of GIS-derived data sets that could be applied in the development of local and national predictive maps for I. ricinus in Great Britain. An understanding of the influence of these factors on questing I. ricinus can aid targeted tick control programs and help to educate the public, and those occupationally exposed, in understanding likely I. ricinus prolific areas within an I. ricinus endemic region.


Assuntos
Ecossistema , Ixodes , Animais , Feminino , Geografia , Masculino , Densidade Demográfica , Estatísticas não Paramétricas , País de Gales
13.
CBE Life Sci Educ ; 17(2): ar23, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29749838

RESUMO

Providing students with one-on-one interaction with instructors is a big challenge in large courses. One solution is to have students interact with their peers during class. Reciprocal peer tutoring (RPT) is a more involved interaction that requires peers to alternate the roles of "teacher" and "student." Theoretically, advantages for peer tutoring include the verbalization and questioning of information and the scaffolded exploration of material through social and cognitive interaction. Studies on RPT vary in their execution, but most require elaborate planning and take up valuable class time. We tested the effectiveness of a "teach and question" (TQ) assignment that required student pairs to engage in RPT regularly outside class. A quasi-experimental design was implemented: one section of a general biology course completed TQ assignments, while another section completed a substitute assignment requiring individuals to review course material. The TQ section outperformed the other section by ∼6% on exams. Session recordings were coded to investigate correlation between TQ quality and student performance. Asking more questions was the characteristic that best predicted exam performance, and this was more predictive than most aspects of the course. We propose the TQ as an easy assignment to implement with large performance gains.


Assuntos
Biologia/educação , Avaliação Educacional , Aprendizagem , Grupo Associado , Ensino , Atitude , Currículo , Humanos , Reprodutibilidade dos Testes , Estudantes
14.
Mol Cell Biol ; 17(5): 2475-84, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9111316

RESUMO

NFAT proteins constitute a family of transcription factors involved in mediating signal transduction. Using a panel of specific antisera in immunoprecipitation assays, we found that NFATp (135 kDa) is constitutively expressed in normal human T cells, while synthesis of NFATc (predominant form of 86 kDa) is induced by ionomycin treatment. NFAT4/x was very weakly expressed in unstimulated cells, and its level did not increase upon treatment with activating agents. NFAT3 protein was not observed under any conditions. Higher-molecular-weight species of NFATc (of 110 and 140 kDa) were also detected. In addition, translation of NFATc mRNA apparently initiates at two different AUG codons, giving rise to proteins that differ in size by 36 amino acids. Additional size heterogeneity of both NFATc and NFATp results from phosphorylation. In contrast to ionomycin treatment, exposure of cells to phorbol myristate acetate (PMA) plus anti-CD28 did not induce NFATc, indicating that under these conditions, interleukin-2 synthesis by these cells is apparently independent of NFATc. In DNA binding assays, both PMA plus anti-CD28 and PMA plus ionomycin resulted in nuclear NFAT. Surprisingly, the PMA-ionomycin-induced synthesis of NFATc that was detected by immunoprecipitation was not mirrored in the DNA binding assays: nearly all of the activity was due to NFATp. This is the first study of expression of all family members at the protein level in normal human T cells.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Ativação Linfocitária , Proteínas Nucleares/metabolismo , Fosfoproteínas/metabolismo , Linfócitos T/metabolismo , Fatores de Transcrição/metabolismo , Antígenos CD28/imunologia , DNA/metabolismo , Eletroforese em Gel de Poliacrilamida , Humanos , Soros Imunes , Células Jurkat , Peso Molecular , Fatores de Transcrição NFATC , Acetato de Tetradecanoilforbol/farmacologia
15.
Mol Cell Biol ; 15(2): 872-82, 1995 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-7823953

RESUMO

In most cells, proteins belonging to the Rel/NF-kappa B family of transcription factors are held in inactive form in the cytoplasm by an inhibitor protein, I kappa B alpha. Stimulation of the cells leads to degradation of the inhibitor and transit of active DNA-binding Rel/NF-kappa B dimers to the nucleus. I kappa B alpha is also able to inhibit DNA binding by Rel/NF-kappa B dimers in vitro, suggesting that it may perform the same function in cells when the activating signal is no longer present. Structurally, the human I kappa B alpha molecule can be divided into three sections: a 70-amino-acid N terminus with no known function, a 205-residue midsection composed of six ankyrin-like repeats, and a very acidic 42-amino-acid C terminus that resembles a PEST sequence. In this study we examined how the structural elements of the I kappa B alpha protein correlate with its functional capabilities both in vitro and in vivo. Using a battery of I kappa B alpha mutants, we show that (i) a dimer binds a single I kappa B alpha molecule, (ii) the acidic C-terminal region of I kappa B alpha is not required for protein-protein binding and does not mask the nuclear localization signal of the dimer, (iii) the same C-terminal region is required for inhibition of DNA binding, and (iv) this inhibition may be accomplished by direct interaction between the PEST-like region and the DNA-binding region of one of the subunits of the dimer.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas I-kappa B , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Sequência Consenso , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/isolamento & purificação , Humanos , Substâncias Macromoleculares , Camundongos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Inibidor de NF-kappaB alfa , NF-kappa B/antagonistas & inibidores , Oligodesoxirribonucleotídeos , Proteínas Proto-Oncogênicas c-rel , Fator de Transcrição RelA , Fatores de Transcrição/metabolismo , Transfecção
16.
Mol Cell Biol ; 18(5): 2640-9, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9566883

RESUMO

Members of the Rel/NF-kappaB family of transcription factors are related to each other over a region of about 300 amino acids called the Rel Homology Domain (RHD), which governs DNA binding, dimerization, and binding to inhibitor. At the C-terminal end of the RHD, each protein has a nuclear localization signal (NLS). The crystal structures of the p50 and RelA family members show that the RHD consists of two regions: an N-terminal section which contains some of the DNA contacts and a C-terminal section which contains the remaining DNA contacts and controls dimerization. In unstimulated cells, the homo- or heterodimeric Rel/NF-kappaB proteins are cytoplasmic by virtue of binding to an inhibitor protein (IkappaB) which somehow masks the NLS of each member of the dimer. The IkappaB proteins consist of an ankyrin-repeat-containing domain that is required for binding to dimers and N- and C-terminal domains that are dispensable for binding to most dimers. In this study, we examined the interaction between IkappaB alpha and Rel family homodimers by mutational analysis. We show that (i) the dimerization regions of p50, RelA, and c-Rel are sufficient for binding to IkappaB alpha, (ii) the NLSs of RelA and c-Rel are not required for binding to IkappaB alpha but do stabilize the interaction, (iii) the NLS of p50 is required for binding to IkappaB alpha, (iv) only certain residues within the p50 NLS are required for binding, and (v) in a p50-IkappaB alpha complex or a c-Rel-IkappaB alpha complex, the N terminus of IkappaB alpha either directly or indirectly masks one or both of the dimer NLSs.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas I-kappa B , NF-kappa B/metabolismo , Sinais de Localização Nuclear , Proteínas Proto-Oncogênicas/metabolismo , Sítios de Ligação , Compartimento Celular , Citoplasma/metabolismo , Dimerização , Humanos , Mutação , Inibidor de NF-kappaB alfa , NF-kappa B/genética , Subunidade p50 de NF-kappa B , Ligação Proteica , Proteínas Proto-Oncogênicas c-rel
17.
Mol Cell Biol ; 5(10): 2826-31, 1985 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3016517

RESUMO

We isolated and sequenced a human genomic-DNA segment that is homologous to a portion of v-rel, the transforming gene of reticuloendotheliosis virus (strain T). We also localized the human rel sequences to human chromosome 2 by screening a panel of rodent X human somatic-cell hybrids with the newly described human rel segment.


Assuntos
Cromossomos Humanos 1-3 , Proteínas Proto-Oncogênicas/genética , Sequência de Bases , Mapeamento Cromossômico , Humanos , Vírus da Reticuloendoteliose/genética
18.
Mol Cell Biol ; 15(10): 5339-45, 1995 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-7565683

RESUMO

The proteolytic degradation of the inhibitory protein MAD3/I kappa B alpha in response to extracellular stimulation is a prerequisite step in the activation of the transcription factor NF-kappa B. Analysis of the expression of human I kappa B alpha protein in stable transfectants of mouse 70Z/3 cells shows that, as for the endogenous murine protein, exogenous I kappa B alpha is degraded in response to inducers of NF-kappa B activity, such as phorbol myristate acetate or lipopolysaccharide. In addition, pretreatment of the cells with the proteasome inhibitor N-Ac-Leu-Leu-norleucinal inhibits this ligand-induced degradation and, in agreement with previous studies, stabilizes a hyperphosphorylated form of the human I kappa B alpha protein. By expressing mutant forms of the human protein in this cell line, we have been able to delineate the sequences responsible for both the ligand-induced phosphorylation and the degradation of I kappa B alpha. Our results show that deletion of the C terminus of the I kappa B alpha molecule up to amino acid 279 abolishes constitutive but not ligand-inducible phosphorylation and inhibits ligand-inducible degradation. Further analysis reveals that the inducible phosphorylation of I kappa B alpha maps to two serines in the N terminus of the protein (residues 32 and 36) and that the mutation of either residue is sufficient to abolish ligand-induced degradation, whereas both residues must be mutated to abolish inducible phosphorylation of the protein. We propose that treatment of 70Z/3 cells with either phorbol myristate acetate or lipopolysaccharide induces a kinase activity which phosphorylates serines 32 and that these phosphorylations target the protein for rapid proteolytic degradation, possibly by the ubiquitin-26S proteasome pathway, thus allowing NF-kappa B to translocate to the nucleus and to activate gene expression.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas I-kappa B , NF-kappa B/metabolismo , Sequência de Aminoácidos , Animais , Linfócitos B/efeitos dos fármacos , Linhagem Celular , Inibidores de Cisteína Proteinase/farmacologia , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Humanos , Leupeptinas/farmacologia , Lipopolissacarídeos/farmacologia , Camundongos , Dados de Sequência Molecular , Mutação , Inibidor de NF-kappaB alfa , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Deleção de Sequência , Serina/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Transfecção
19.
Mol Cell Biol ; 7(3): 1304-9, 1987 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2436042

RESUMO

A portion of the human cellular homolog of v-rel, the transforming gene of the leukemogenic retrovirus reticuloendotheliosis virus, strain T, was used to survey RNAs from several mouse tissues, selected lymphocyte populations, and hematopoietic cell lines for c-rel expression. Relatively high levels of a high-molecular-weight transcript were observed in peripheral B and T cells, whereas lower levels were detectable in functionally immature thymocytes. These results suggested that, unlike c-myb and c-ets, the c-rel proto-oncogene plays a role in later stages of lymphocyte differentiation.


Assuntos
Sistema Hematopoético/metabolismo , Linfócitos/metabolismo , Proto-Oncogenes , Animais , Linhagem Celular , DNA/genética , Hematopoese , Humanos , Camundongos , Proto-Oncogene Mas , RNA/genética , Transcrição Gênica
20.
Mol Cell Biol ; 16(5): 2341-9, 1996 May.
Artigo em Inglês | MEDLINE | ID: mdl-8628301

RESUMO

The ubiquitous transcription factor NF-kappaB is an essential component in signal transduction pathways, in inflammation, and in the immune response. NF-kappaB is maintained in an inactive state in the cytoplasm by protein-protein interaction with IkappaBalpha. Upon stimulation, rapid degradation of IkappaBalpha allows nuclear translocation of NF-kappaB. To study the importance of IkappaBalpha in signal transduction, IkappaBalpha-deficient mice were derived by gene targeting. Cultured fibroblasts derived from IkappaBalpha-deficient embryos exhibit levels of NF-kappaB1, NF-kappaB2, RelA, c-Rel, and IkappaBbeta similar to those of wild-type fibroblasts. A failure to increase nuclear levels of NF-kappaB indicates that cytoplasmic retention of NF-kappaB may be compensated for by other IkappaB proteins. Treatment of wild-type cells with tumor necrosis factor alpha (TNF-alpha) resulted in rapid, transient nuclear localization of NF-kappaB. IkappaBalpha-deficient fibroblasts are also TNF-alpha responsive, but nuclear localization of NF-kappaB is prolonged, thus demonstrating that a major irreplaceable function Of IkappaBalpha is termination of the NF-kappaB response. Consistent with these observations, and with IkappaBalpha and NF-kappaB's role in regulating inflammatory and immune responses, is the normal development Of IkappaBalpha-deficient mice. However, growth ceases 3 days after birth and death usually occurs at 7 to 10 days of age. An increased percentage of monocytes/macrophages was detected in spleen cells taken from 5-, 7-, and 9-day-old pups. Death is accompanied by severe widespread dermatitis and increased levels of TNF-alpha mRNA in the skin.


Assuntos
Proteínas de Ligação a DNA/genética , Dermatite/genética , Proteínas I-kappa B , NF-kappa B/metabolismo , Células 3T3 , Animais , Western Blotting , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Clonagem Molecular , Cicloeximida/farmacologia , Proteínas de Ligação a DNA/biossíntese , Dermatite/patologia , Dermatite/fisiopatologia , Embrião de Mamíferos , Expressão Gênica , Triagem de Portadores Genéticos , Genótipo , Homozigoto , Rim/metabolismo , Rim/patologia , Fígado/metabolismo , Fígado/patologia , Camundongos , Camundongos Knockout , Inibidor de NF-kappaB alfa , NF-kappa B/antagonistas & inibidores , Proteínas Nucleares/biossíntese , Proteínas Proto-Oncogênicas/biossíntese , Proteínas Proto-Oncogênicas c-rel , RNA Mensageiro/análise , Deleção de Sequência , Pele/metabolismo , Pele/patologia , Baço/metabolismo , Baço/patologia , Fator de Necrose Tumoral alfa/biossíntese , Fator de Necrose Tumoral alfa/farmacologia
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