RESUMO
BACKGROUND: Primary endocrine therapy may be an alternative treatment for less fit women with oestrogen receptor (ER)-positive breast cancer. This study compared quality-of-life (QoL) outcomes in older women treated with surgery or primary endocrine therapy. METHODS: This was a multicentre, prospective, observational cohort study of surgery or primary endocrine therapy in women aged over 70 years with operable breast cancer. QoL was assessed using European Organisation for Research and Treatment of cancer QoL questionnaires QLQ-C30, -BR23, and -ELD14, and the EuroQol Five Dimensions 5L score at baseline, 6 weeks, and 6, 12, 18, and 24 months. Propensity score matching was used to adjust for baseline variation in health, fitness, and tumour stage. RESULTS: The study recruited 3416 women (median age 77 (range 69-102) years) from 56 breast units. Of these, 2979 (87.2 per cent) had ER-positive breast cancer; 2354 women had surgery and 500 received primary endocrine therapy (125 were excluded from analysis due to inadequate data or non-standard therapy). Median follow-up was 52 months. The primary endocrine therapy group was older and less fit. Baseline QoL differed between the groups; the mean(s.d.) QLQ-C30 global health status score was 66.2(21.1) in patients who received primary endocrine therapy versus 77.1(17.8) among those who had surgery plus endocrine therapy. In the unmatched analysis, changes in QoL between 6 weeks and baseline were noted in several domains, but by 24 months most scores had returned to baseline levels. In the matched analysis, major surgery (mastectomy or axillary clearance) had a more pronounced adverse impact than primary endocrine therapy in several domains. CONCLUSION: Adverse effects on QoL are seen in the first few months after surgery, but by 24 months these have largely resolved. Women considering surgery should be informed of these effects.
Assuntos
Antineoplásicos Hormonais/uso terapêutico , Neoplasias da Mama/terapia , Qualidade de Vida , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/psicologia , Feminino , Humanos , Estudos Longitudinais , Mastectomia , Estudos Prospectivos , Receptores de Estrogênio/metabolismoRESUMO
Soil carbon sequestration (SCS) has the potential to attenuate increasing atmospheric CO2 and mitigate greenhouse warming. Understanding of this potential can be assisted by the use of simulation models. We evaluated the ability of the EPIC model to simulate corn (Zea mays L.) yields and soil organic carbon (SOC) at Arlington, WI, during 1958-1991. Corn was grown continuously on a Typic Argiudoll with three N levels: LTN1 (control), LTN2 (medium), and LTN3 (high). The LTN2 N rate started at 56 kg ha(-1) (1958), increased to 92 kg ha(-1) (1963), and reached 140 kg ha(-1) (1973). The LTN3 N rate was maintained at twice the LTN2 level. In 1984, each plot was divided into four subplots receiving N at 0, 84, 168, and 252 kg ha(-1). Five treatments were used for model evaluation. Percent errors of mean yield predictions during 1958-1983 decreased as N rate increased (LTN1 = -5.0%, LTN2 = 3.5%, and LTN3 = 1.0%). Percent errors of mean yield predictions during 1985-1991 were larger than during the first period. Simulated and observed mean yields during 1958-1991 were highly correlated (R2 = 0.961, p < 0.01). Simulated SOC agreed well with observed values with percent errors from -5.8 to 0.5% in 1984 and from -5.1 to 0.7% in 1990. EPIC captured the dynamics of SOC, SCS, and microbial biomass. Simulated net N mineralization rates were lower than those from laboratory incubations. Improvements in EPIC's ability to predict annual variability of crop yields may lead to improved estimates of SCS.
Assuntos
Carbono/análise , Fertilizantes , Nitrogênio/metabolismo , Solo/análise , Zea mays/crescimento & desenvolvimento , Biomassa , Carbono/metabolismo , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Ecossistema , Monitoramento Ambiental , Previsões , Efeito Estufa , Fatores de TempoRESUMO
GPR50 is an orphan G protein-coupled receptor (GPCR) located on Xq28, a region previously implicated in multiple genetic studies of bipolar affective disorder (BPAD). Allele frequencies of three polymorphisms in GPR50 were compared in case-control studies between subjects with BPAD (264), major depressive disorder (MDD) (226), or schizophrenia (SCZ) (263) and ethnically matched controls (562). Significant associations were found between an insertion/deletion polymorphism in exon 2 and both BPAD (P=0.0070), and MDD (P=0.011) with increased risk associated with the deletion variant (GPR50(Delta502-505)). When the analysis was restricted to female subjects, the associations with BPAD and MDD increased in significance (P=0.00023 and P=0.0064, respectively). Two other single-nucleotide polymorphisms (SNPs) tested within this gene showed associations between: the female MDD group and an SNP in exon 2 (P=0.0096); and female SCZ and an intronic SNP (P=0.0014). No association was detected in males with either MDD, BPAD or SCZ. These results suggest that GPR50(Delta502-505), or a variant in tight linkage disequilibrium with this polymorphism, is a sex-specific risk factor for susceptibility to bipolar disorder, and that other variants in the gene may be sex-specific risk factors in the development of schizophrenia.
Assuntos
Transtorno Bipolar/genética , Cromossomos Humanos X , Transtorno Depressivo Maior/genética , Proteínas do Tecido Nervoso/genética , Receptores Acoplados a Proteínas G/genética , Esquizofrenia/genética , Adulto , Estudos de Casos e Controles , Feminino , Frequência do Gene , Humanos , Desequilíbrio de Ligação/genética , Masculino , Polimorfismo de Nucleotídeo Único/genética , Caracteres Sexuais , Estatísticas não ParamétricasRESUMO
To determine whether autaptic inhibition plays a functional role in the adult hippocampus, the action potential afterhyperpolarisations (spike AHPs) of CA1 interneurones were investigated in 25 basket, three bistratified and eight axo-axonic cells. The spike AHPs showed two minima in all regular-spiking (5), burst-firing (3) and in many fast-spiking cells (17:28). The fast component had a time-to-peak (TTP) of 1.2 +/- 0.5 ms, the slower TTP was very variable (range of 3.3-103 ms). The AHP width at half-amplitude (HW) was 12.5 +/- 5.7 ms in fast-spiking, 29.3 +/- 18 ms in regular-spiking and 99.7 +/- 42 ms in burst-firing cells. Axo-axonic cells never establish autapses, and the fast-spiking variety showed narrow (HW: 3.9 +/- 0.7 ms) spike AHPs with only one AHP minimum (TTP: 0.9 +/- 0.1 ms). When challenged with GABA(A) receptor modulators, spike AHPs in basket and bistratified cells were enhanced by zolpidem (HW by 18.4 +/- 6.2 % in 10:15 cells tested), diazepam (45.2 +/- 0.5 %, 6:7), etomidate (43.9 +/- 36 %, 6:8) and pentobarbitone sodium (41 %, 1:1), and were depressed by bicuculline (-41 +/- 5.7 %, 5:8) and picrotoxin (-54 %, 1:1), and the enhancement produced by zolpidem was reduced by flumazenil (-31 +/- 13 %, relative to the AHP HW during exposure to zolpidem, 3:4). Neuronal excitability was modulated in parallel. The spike AHPs of three axo-axonic cells tested showed no sensitivity to etomidate, pentobarbitone or diazepam. Interneurone-to-interneurone inhibitory postsynaptic potentials (IPSPs), studied with dual intracellular recordings, had time courses resembling those of the spike AHPs. The IPSP HW was 13.4 +/- 2.8 ms in fast-spiking (n = 16) and 28.7 +/- 5.8 ms in regular-spiking/burst-firing cells (n = 6), and the benzodiazepine1-selective modulator zolpidem strongly enhanced these IPSPs (45 +/- 28 %, n = 5). Interneurones with spike AHPs affected by the GABA(A) receptor ligands exhibited 3.8 +/- 1.9 close autaptic appositions. In three basket cells studied at the ultrastructural level 6 of 6, 1 of 2 and 1 of 2 close appositions were confirmed as autapses. Therefore, in the hippocampus autaptic connections contribute to spike AHPs in many interneurones. These autapses influence neuronal firing and responses to GABA(A) receptor ligands.
Assuntos
Hipocampo/fisiologia , Interneurônios/fisiologia , Inibição Neural/fisiologia , Receptores de GABA-A/metabolismo , Sinapses/fisiologia , Potenciais de Ação/fisiologia , Animais , Eletrofisiologia , Agonistas GABAérgicos/farmacologia , Hipocampo/citologia , Hipocampo/ultraestrutura , Interneurônios/ultraestrutura , Ligantes , Masculino , Neurônios/fisiologia , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Tempo de Reação , Sinapses/ultraestrutura , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia , ZolpidemRESUMO
OBJECTIVE: to explore, describe and understand the expectations during pregnancy and subsequent experiences of childbirth in primiparae. DESIGN: a qualitative study using a phenomenological approach. Data were collected using unstructured, tape-recorded interviews in late pregnancy and at two weeks post birth. SETTING: the north of England. PARTICIPANTS: eight pregnant women, expecting their first baby. FINDINGS: the women all wanted to take an active part in their labour and the feeling of being 'in control' was the main finding and the 'essence' of this study. This was achieved through support from partners, the positive attitudes of the midwives caring for them during pregnancy and labour, information giving during pregnancy and labour and being able to make and be included in decision making during labour. IMPLICATIONS FOR PRACTICE: if women are to be empowered by making choices for childbirth and feeling 'in control', then it is important for midwives to explore and discover the wishes and feelings of women in their care so that realistic expectations can be promoted and then hopefully fulfilled.
Assuntos
Atitude Frente a Saúde , Tomada de Decisões , Parto Obstétrico/psicologia , Tocologia/normas , Mães/psicologia , Adulto , Parto Obstétrico/métodos , Parto Obstétrico/enfermagem , Inglaterra , Feminino , Humanos , Relações Enfermeiro-Paciente , Pesquisa Metodológica em Enfermagem , Gravidez , Apoio Social , Inquéritos e QuestionáriosRESUMO
GSH-dependent prostaglandin D(2) synthase (PGDS) enzymes represent the only vertebrate members of class Sigma glutathione S-transferases (GSTs) identified to date. Complementary DNA clones encoding the orthologous human and rat GSH-dependent PGDS (hPGDS and rPGDS, respectively) have been expressed in Escherichia coli, and the recombinant proteins isolated by affinity chromatography. The purified enzymes were both shown to catalyse specifically the isomerization of prostaglandin (PG) H(2) to PGD(2). Each transferase also exhibited GSH-conjugating and GSH-peroxidase activities. The ability of hPGDS to catalyse the conjugation of aryl halides and isothiocyanates with GSH was found to be less than that of the rat enzyme. Whilst there is no difference between the enzymes with respect to their K(m) values for 1-chloro-2,4-dinitrobenzene, marked differences were found to exist with respect to their K(m) for GSH (8 mM versus 0.3 mM for hPGDS and rPGDS, respectively). Using molecular modelling techniques, amino acid substitutions have been identified in the N-terminal domain of these enzymes that lie outside the proposed GSH-binding site, which may explain these catalytic differences. The tissue-specific expression of PGDS also varies significantly between human and rat; amongst the tissues examined, variation in expression between the two species was most apparent in spleen and bone marrow. Differences in catalytic properties and tissue-specific expression of hPGDS and rPGDS appears to reflect distinct physiological roles for class Sigma GST between species. The evolution of divergent functions for the hPGDS and rPGDS is discussed in the context of the orthologous enzyme from chicken.
Assuntos
Glutationa Transferase/metabolismo , Oxirredutases Intramoleculares/metabolismo , Sequência de Aminoácidos , Animais , Catálise , Glutationa Transferase/classificação , Glutationa Transferase/genética , Humanos , Oxirredutases Intramoleculares/química , Oxirredutases Intramoleculares/genética , Isoenzimas/metabolismo , Lipocalinas , Modelos Moleculares , Dados de Sequência Molecular , Especificidade de Órgãos , Conformação Proteica , Estrutura Terciária de Proteína , Ratos , Ratos Wistar , Proteínas Recombinantes/metabolismo , Alinhamento de SequênciaRESUMO
The exchange of information is an everyday part of orthodontic treatment. However, the amount of information that is understood and retained, by patients and their parents, is not known. There has been very little research in the area of information retention in dentistry. This has implications with the demands for improved provision of information for patients. This questionnaire-based study, compared the effectiveness of written, verbal, and visual methods of providing orthodontic information. It assessed the retention of this information, by patients and parents, in both the short- and long-term. Twenty-eight patients and their parents, were allocated alternately into one of three groups, receiving written, verbal, or visual information. Short-term retention of knowledge was assessed 10-15 minutes after receiving the information and long-term retention rated by a second questionnaire mailed 8 weeks later. Overall, little difference was found between the three methods. The findings suggested that verbal information should not be given to patients unless supplemented by written and/or visual information, and that parents were more attentive to verbal instructions than their children.
Assuntos
Ortodontia/educação , Educação de Pacientes como Assunto/métodos , Retenção Psicológica , Adolescente , Recursos Audiovisuais , Distribuição de Qui-Quadrado , Criança , Comunicação , Feminino , Humanos , Masculino , Pais/educação , Estatísticas não Paramétricas , Inquéritos e Questionários , Aprendizagem Verbal , RedaçãoRESUMO
The epidermal growth factor receptor (EGF-R) plays an important role in the growth and progression of estrogen receptor-negative human breast cancers. EGF binds with high affinity to the EGF-R and activates a variety of second messenger pathways that affect cellular proliferation. However, the underlying mechanisms involved in the regulation of EGF-R expression in breast cancer cells are yet to be described. Here we show that the EGF-induced upregulation of EGF-R mRNA in two human breast cancer cell lines that overexpress EGF-R (MDA-MB-468 and BT-20) is accompanied by stabilization (>2-fold) of EGF-R mRNA. Transient transfections using a luciferase reporter identified a novel EGF-regulated approximately 260-nucleotide (nt) cis-acting element in the 3' untranslated region (3'-UTR) of EGF-R mRNA. This cis element contains two distinct AU-rich sequences (~75 nt), EGF-R1A with two AUUUA pentamers and EGF-R2A with two AUUUUUA extended pentamers. Each independently regulated the mRNA stability of the heterologous reporter. Analysis of mutants of the EGF-R2A AU-rich sequence demonstrated a role for the 3' extended pentamer in regulating basal turnover. RNA gel shift analysis identified cytoplasmic proteins (~55 to 80 kDa) from breast cancer cells that bound specifically to the EGF-R1A and EGF-R2A cis-acting elements and whose binding activity was rapidly downregulated by EGF and phorbol esters. RNA gel shift analysis of EGF-R2A mutants identified a role for the 3' extended AU pentamer, but not the 5' extended pentamer, in binding proteins. These EGF-R mRNA-binding proteins were present in multiple human breast and prostate cancer cell lines. In summary, these data demonstrate a central role for mRNA stabilization in the control of EGF-R gene expression in breast cancer cells. EGF-R mRNA contains a novel complex AU-rich 260-nt cis-acting destabilizing element in the 3'-UTR that is bound by specific and EGF-regulated trans-acting factors. Furthermore, the 3' extended AU pentamer of EGF-R2A plays a central role in regulating EGF-R mRNA stability and the binding of specific RNA-binding proteins. These findings suggest that regulated RNA-protein interactions involving this novel cis-acting element will be a major determinant of EGF-R mRNA stability.
Assuntos
Regiões 3' não Traduzidas , Receptores ErbB/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo , Sequências Reguladoras de Ácido Nucleico , Sequência de Bases , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Citoplasma/metabolismo , Análise Mutacional de DNA , Fator de Crescimento Epidérmico/metabolismo , Fator de Crescimento Epidérmico/farmacologia , Receptores ErbB/metabolismo , Humanos , Dados de Sequência Molecular , Estabilidade de RNA , RNA Mensageiro/efeitos dos fármacos , Proteínas de Ligação a RNA/genética , Acetato de Tetradecanoilforbol/farmacologia , Transfecção , Células Tumorais CultivadasRESUMO
In this paper evidence-based care is defined. The evidence to support the provision of care by midwives is presented, as is the evidence to support home birth for those women at low obstetric risk. In conclusion midwives are challenged to be political and use this evidence to support changes to improve the quality of care provided to women and their families.
Assuntos
Medicina Baseada em Evidências , Tocologia/organização & administração , Enfermeiros Obstétricos/organização & administração , Pesquisa em Enfermagem/organização & administração , Feminino , Parto Domiciliar/enfermagem , Humanos , Modelos de Enfermagem , GravidezRESUMO
Inhibitory hippocampal and neocortical interneurones comprise a physiologically, morphologically and neurochemically heterogenous cell population. To identify the roles each class of interneurone plays within a given circuit it is necessary to correlate the electrophysiological properties of individual cells with their neurochemistry and morphology at both the light and electron microscopic level. However, the optimal conditions required for any one part of the protocol typically compromise the results from another. We have developed a protocol which allows the neurochemical content, gross morphology and ultrastructure details of biocytin-filled neurones to be recovered following long, dual intracellular recordings in thick mature slices maintained in an interface recording chamber, helping define sub-populations which could not otherwise be determined. Dual immunofluorescence is performed by incubating the tissue in monoclonal and polyclonal antibodies simultaneously, prior to visualization of biocytin-labelling with precipitation of a peroxidase reaction product. By using a biotinylated anti-avidin D antibody (Vector Laboratories), the intensity of this precipitation can be enhanced further where necessary. It is envisaged that this protocol can not only help determine the neurochemical content of cells recorded in similar in vivo studies, but that the ability to amplify peroxidase labelling in poorly filled cells is also of interest.
Assuntos
Eletrofisiologia/métodos , Imunofluorescência/métodos , Técnicas Imunoenzimáticas/métodos , Interneurônios/metabolismo , Lisina/análogos & derivados , Animais , Avidina/imunologia , Avidina/farmacologia , Tamanho Celular/fisiologia , Técnicas de Cultura , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Corantes Fluorescentes , Hipocampo/metabolismo , Hipocampo/ultraestrutura , Interneurônios/classificação , Interneurônios/ultraestrutura , Microeletrodos/normas , Neocórtex/metabolismo , Neocórtex/ultraestrutura , Inibição Neural/efeitos dos fármacos , Inibição Neural/fisiologia , Ratos , XantenosRESUMO
Intracellular iron homeostasis is regulated, in part, by interactions between iron-regulatory proteins (IRP1 and IRP2) and iron-responsive elements (IREs) in ferritin and transferrin receptor mRNAs. In addition to iron, cellular oxidative stress induced by H(2)O(2), nitric oxide, and hypoxia, and hormonal activation by thyroid hormone and erythropoeitin have each been shown to regulate IRP binding to IREs. Hormonal signals, in particular mediated through protein kinase C (PKC), play a central role in the modulation of IRP/IRE interactions since phorbol esters were shown to activate IRP binding (Eisenstein, R. S., Tuazon, P. T., Schalinske, K. L., Anderson, S. A., and Traugh, J. A. (1993) J. Biol. Chem. 268, 27363-27370). In pituitary thyrotrophs (TtT97), we found that thyrotropin releasing hormone (TRH) and epidermal growth factor (EGF) increased IRP binding to a ferritin IRE, dependent on PKC and mitogen-activated protein kinase (MAPK) activity. In contrast, TRH and EGF decreased IRP binding in pituitary lactotrophs (GH3), despite activation of PKC and MAPK. IRP1 and IRP2 levels remained constant and IRP2 binding was predominant throughout. TRH and EGF markedly decreased IRP binding in MAPK kinase inhibitor-treated GH3 cells, whereas, they increased IRP binding in phosphatase inhibitor-treated GH3 cells. IRE-dependent CAT reporter translational expression closely reflected IRP binding to the ferritin IRE in both GH3 and TtT97 cells. Interestingly, ferritin protein levels were regulated similarly by TRH in both cell lines. These data link two different cell receptor systems to common signaling pathways that regulate IRP binding and ferritin expression. Remarkably, for TRH and EGF, these effects may be PKC-dependent or -independent determined by the cell type.
Assuntos
Fator de Crescimento Epidérmico/farmacologia , Proteínas Ferro-Enxofre/metabolismo , Hipófise/efeitos dos fármacos , Proteína Quinase C/metabolismo , Proteínas de Ligação a RNA/metabolismo , Transdução de Sinais/efeitos dos fármacos , Hormônio Liberador de Tireotropina/farmacologia , Animais , Ferritinas/genética , Genes Reporter , Homeostase/efeitos dos fármacos , Ferro/metabolismo , Proteína 1 Reguladora do Ferro , Proteína 2 Reguladora do Ferro , Proteínas Reguladoras de Ferro , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosfoproteínas Fosfatases/antagonistas & inibidores , Fosfoproteínas Fosfatases/metabolismo , Hipófise/citologia , Hipófise/enzimologia , Hipófise/metabolismo , Ligação Proteica/efeitos dos fármacos , Proteína Quinase C/antagonistas & inibidores , RNA/genética , RNA/metabolismo , Ratos , Elementos de Resposta/genética , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genéticaRESUMO
Regulating gene expression from DNA to protein is a complex multistage process with multiple control mechanisms. Transcriptional regulation has been considered the major control point of protein production in eukaryotic cells; however, there is growing evidence of pivotal posttranscriptional regulation for many genes. This has prompted extensive investigations to elucidate the mechanisms controlling RNA processing, mRNA nuclear export and localization, mRNA stability and turnover, in addition to translational rates and posttranslational events. The regulation of mRNA stability has emerged as a critical control step in determining the cellular mRNA level, with individual mRNAs displaying a wide range of stability that has been linked to discrete sequence elements and specific RNA-protein interactions. This review will focus on current knowledge of the determinants of mRNA stability and RNA-protein interactions in the pituitary. This field is rapidly expanding with the identification of regulated cis-acting stability-modifying elements within many mRNAs, and the cloning and characterization of trans-acting proteins that specifically bind to their cognate cis elements. We will present evidence for regulation of multiple pituitary genes at the level of mRNA stability and some examples of the emerging data characterizing RNA-protein interactions.
Assuntos
Hipófise/metabolismo , Proteínas/metabolismo , RNA Mensageiro/metabolismo , Animais , Sequência de Bases , Proteínas de Transporte/metabolismo , Citoplasma/metabolismo , Exorribonucleases/metabolismo , Regulação da Expressão Gênica , Humanos , Modelos Biológicos , Hormônios Hipofisários/metabolismo , Poli A/metabolismo , Proteínas de Ligação a Poli(A) , Proteínas/genética , Processamento Pós-Transcricional do RNA , Estabilidade de RNA , RNA Mensageiro/química , RNA Mensageiro/genética , Proteínas de Ligação a RNA/metabolismoRESUMO
During the 1950s to 70s most of the mechanisms that control transmitter release from presynaptic nerve terminals were described at the neuromuscular junction. It was not, however, until the 1990s that the multiplicity of protein-protein interactions that govern this process began to be identified. The sheer numbers of proteins and the complexity of their interactions at first appears excessive, even redundant. However, studies of identified central synapses indicate that this molecular diversity may underlie a important functional diversity. The task of the neuromuscular junction is to relay faithfully the rate and pattern code generated by the motoneurone. To demonstrate phenomena such as facilitation and augmentation that are apparent only when the probability of release is low, experimental manipulation is required. In the cortex, however, low probability synapses displaying facilitation can be recorded in parallel with high probability synapses displaying depression. The mechanisms are largely the same as those displayed by the neuromuscular junction, but some are differentially expressed and controlled. Central synapses demonstrate exquisitely fine tuned information transfer, each of the many types displaying its own repertoire of pattern- and frequency-dependent properties. These appear tuned to match both the discharge pattern in the presynaptic neurone and the integrative requirements of the postsynaptic cell. The molecular identification of these differentially expressed frequency filters is now just coming into sight. This review attempts to correlate these two aspects of synaptic physiology and to identify the components of the release process that are responsible for the diversity of function.
Assuntos
Proteínas do Tecido Nervoso/fisiologia , Neurônios/fisiologia , Terminações Pré-Sinápticas/fisiologia , Transmissão Sináptica/fisiologia , AnimaisRESUMO
Release probability (P) appears to be a major factor that influences the pattern of transmitter release. At cortical pyramidal axon inputs onto different classes of target cells, very different release patterns are observed, patterns that correlate with release probability. Simplistically, 'low P' synapses display facilitation and augmentation, whereas 'high P' synapses supplied by the same axon exhibit paired-pulse and frequency-dependent depression. Different combinations of factors probably contribute to release probability at different terminals, during development and under different experimental conditions. The recent advances made by molecular biological studies of the release machinery do, however, provide candidate proteins and protein-protein interactions whose differential distributions might be important factors in determining the patterns of transmitter release.
Assuntos
Cálcio/metabolismo , Neurotransmissores/metabolismo , Terminações Pré-Sinápticas/metabolismo , Transmissão Sináptica/fisiologia , Vesículas Sinápticas/metabolismo , Animais , HumanosRESUMO
Hippocampal pyramidal cells express several alpha-subunits, which determine the affinity of GABAA (gamma-aminobutyric acid) receptors for benzodiazepine site ligands. This study asked whether inhibitory postsynaptic potentials (IPSPs) elicited by specific interneuronal subclasses were differentially sensitive to the alpha1-preferring agonist Zolpidem, i.e. whether different receptors mediate different inhibitory connections. Paired intracellular recordings in which the presynaptic cell was an interneuron and the postsynaptic cell a CA1 pyramid were performed in slices of adult rat hippocampus. Resultant IPSPs were challenged with Zolpidem, cells filled with biocytin and identified morphologically. IPSPs elicited by fast spiking (FS) basket cells (n = 9) were enhanced more than IPSPs elicited by regular spiking (RS) basket cells (n = 10). At FS basket cell synapses the efficacy of Zolpidem was equivalent to that of Diazepam, while RS basket cell IPSPs are enhanced 50% less by Zolpidem than by Diazepam. Thus, while alpha1 subunits may dominate at synapses supplied by FS basket cells, RS basket cell synapses also involve alpha2/3 subunits. Two bistratified cell IPSPs tested with Zolpidem did not increase in amplitude, despite powerful enhancements of bistratified cell IPSPs by Diazepam, consistent with previous indications that these synapses utilize alpha5-containing receptors. Enhancements of basket cell IPSPs by Zolpidem and Diazepam were bi- or triphasic with steep amplitude increases separated by plateaux, occurring 10-15, 25-30 and 45-55 min after adding the drug to the bath. The entire enhancement was, however, blocked by the antagonist Flumazenil (n = 7). Flumazenil, either alone (n = 3), or after Zolpidem, reduced IPSP amplitude to approximately 90% of control, suggesting that alpha4-containing receptors were not involved.
Assuntos
Potenciais Evocados/efeitos dos fármacos , Agonistas GABAérgicos/farmacologia , Hipocampo/efeitos dos fármacos , Interneurônios/efeitos dos fármacos , Piridinas/farmacologia , Receptores de GABA-A/efeitos dos fármacos , Animais , Diazepam/farmacologia , Flumazenil/farmacologia , Moduladores GABAérgicos/farmacologia , Hipocampo/fisiologia , Interneurônios/fisiologia , Masculino , Terminações Pré-Sinápticas/efeitos dos fármacos , Terminações Pré-Sinápticas/fisiologia , Células Piramidais/fisiologia , Ratos , Ratos Sprague-Dawley , ZolpidemRESUMO
Recent studies have described the coupling between pairs of neocortical interneurons involving both electrical and chemical transmission; these new results may have important implications for the mechanisms underlying neuronal synchrony and rhythmic activity in the brain.
Assuntos
Interneurônios/fisiologia , Neocórtex/fisiologia , Transmissão Sináptica , Animais , Eletrofisiologia , Neocórtex/citologiaRESUMO
In this paper evidence-based care is defined. The evidence to support the provision of care by midwives is presented, as is the evidence to support home birth for those women at low obstetric risk. In conclusion midwives are challenged to be political and use this evidence to support changes to improve the quality of care provided to women and their families.
Assuntos
Medicina Baseada em Evidências , Parto Domiciliar , Tocologia/normas , Segurança , Parto Obstétrico/métodos , Feminino , Custos de Cuidados de Saúde , Parto Domiciliar/economia , Humanos , Mortalidade Infantil , Recém-Nascido , Gravidez , Reino Unido/epidemiologiaRESUMO
Iron plays a central role in the metabolism of all cells. This is evident by its major contribution to many diverse functions, such as DNA replication, bacterial pathogenicity, photosynthesis, oxidative stress control and cell proliferation. In mammalian systems, control of intracellular iron homeostasis is largely due to posttranscriptional regulation of binding by iron-regulatory RNA-binding proteins (IRPs) to iron-responsive elements (IREs) within ferritin and transferrin receptor (TfR) mRNAs. the TfR transports iron into cells and the iron is subsequently stored within ferritin. IRP binding is under tight control so that it responds to changes in intracellular iron requirements in a coordinate manner by differentially regulating ferritin mRNA translational efficiency and TfR mRNA stability. Several different stimuli, as well as intracellular iron levels and oxidative stress, are capable of regulating these RNA-protein interactions. In this mini-review, we shall concentrate on the mechanisms underlying modulation of the interaction of IRPs and the ferritin IRE and its role in regulating ferritin gene expression.
Assuntos
Ferritinas/genética , Proteínas Ferro-Enxofre/metabolismo , Biossíntese de Proteínas , RNA Mensageiro , Proteínas de Ligação a RNA/metabolismo , Elementos de Resposta , Animais , Humanos , Proteínas Reguladoras de Ferro , Isoformas de Proteínas/metabolismoRESUMO
Considerable interest has recently focused on defining the mechanisms involved in the regulation of gene expression at the level of mRNA stability and translational efficiency. However, the assays used to directly investigate interactions between RNA and cytoplasmic proteins have been difficult to establish, and methods are not widely available. Here, we describe a robust method for RNA electrophoretic mobility shift and UV cross-linking assays that allows rapid detection of cytoplasmic RNA-protein interactions. For added convenience to new investigators, these assays use mini-gels with an electrophoresis time of 15-20 min, enabling a high throughput of samples. The method works successfully with many different probes and cytoplasmic extracts from a variety of cell lines. Furthermore, we provide a system to optimize characterization of the RNA-protein complex and troubleshoot most assay difficulties.
Assuntos
Eletroforese em Gel de Poliacrilamida/métodos , RNA Mensageiro/análise , Proteínas de Ligação a RNA/análise , Animais , Neoplasias da Mama , Reagentes de Ligações Cruzadas , Receptores ErbB/genética , Ferritinas/genética , Regulação Neoplásica da Expressão Gênica , Heparina/metabolismo , Humanos , Ribonuclease T1/metabolismo , Tireotropina/genética , Células Tumorais Cultivadas , Raios UltravioletaRESUMO
Simultaneous intracellular recordings from presynaptic Stratum pyramidale interneurons and postsynaptic pyramidal cells in adult rat hippocampal slices were performed to investigate the strength of the modulation of single-axon inhibitory postsynaptic potentials (IPSPs) by the GABAA receptor modulators pentobarbitone, diazepam and zinc. The processing of biocytin-filled interneurons for light microscopy revealed that these single-axon IPSPs were generated by basket cells (n = 33), bistratified cells (n = 18) and axo-axonic cells (n = 2). The IPSPs generated by these three groups of interneurons had amplitudes and widths at half amplitude with similar ranges, but when bistratified cell IPSPs were compared with basket cell IPSPs with similar half widths their rise times were slower. Pentobarbitone sodium (250 microM) powerfully enhanced 13 tested IPSPs generated by all three cell types. Amplitudes were enhanced by 82 +/- 56%, 10-90% rise times by 150 +/- 101% and the widths at half amplitude by 71 +/- 29%. Diazepam (1-2 microM) also increased all IPSPs tested, although the changes were more moderate in basket cell IPSPs (amplitudes increased by 19 +/- 11%, n = 8) than in bistratified cell IPSPs (amplitudes increased by 66 +/- 48%, n = 5). Basket cell IPSP 10-90% rise times and widths at half amplitude were not significantly increased. Bistratified cell IPSP 10-90% rise times were increased by 44 +/- 24% and the widths at half amplitude by 32 +/- 35%. The one tested IPSP generated by an axo-axonic cell was also diazepam-sensitive. Zinc, 250 microM, decreased four out of 10 IPSPs generated by basket cells and four out of five IPSPs generated by bistratified cells. The one tested axo-axonic cell IPSP was zinc-insensitive. These data suggest that IPSPs generated in CA1 pyramidal cells by basket and bistratified cells display different pharmacologies and may be mediated by different receptors or receptor combinations.