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1.
Phys Rev Lett ; 131(18): 185101, 2023 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-37977609

RESUMO

High-performance fusion plasmas, requiring high pressure ß, are not well understood in stellarator-type experiments. Here, the effect of ß on ion-temperature-gradient-driven (ITG) turbulence is studied in Wendelstein 7-X (W7-X), showing that subdominant kinetic ballooning modes (KBMs) are unstable well below the ideal MHD threshold and get strongly excited in the turbulence. By zonal-flow erosion, these subthreshold KBMs (stKBMs) affect ITG saturation and enable higher heat fluxes. Controlling stKBMs will be essential to allow W7-X and future stellarators to achieve maximum performance.

2.
Neurobiol Learn Mem ; 144: 136-146, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28720405

RESUMO

While thepsychoactive inhalant toluene causes behavioral effects similarto those produced by other drugs of abuse, the persistent behavioral and anatomical abnormalities induced by toluene exposure are not well known. To mimic human "binge-like" inhalant intoxication, adolescent, male Sprague-Dawley rats were exposed to toluene vapor (5700ppm) twice daily for five consecutive days. These rats remained in their home cages until adulthood (P60), when they were trained in operant boxes to respond to a palatable food reward and then challenged with several different cognitive tasks. Rats that experienced chronic exposure to toluene plus abstinence ("CTA") showed enhanced performance in a strategy set-shifting task using a between-session, but not a within-session test design. CTA also blunted operant and classical conditioning without affecting responding during a progressive ratio task. While CTA rats displayed normal latent inhibition, previous exposure to a non-reinforced cue enhanced extinction of classically conditioned approach behavior of these animals compared to air controls. To determine whether CTA alters the structural plasticity of brain areas involved in set-shifting and appetitive behaviors, we quantified basal dendritic spine morphology in DiI-labeled pyramidal neurons in layer 5 of the medial prefrontal cortex (mPFC) and medium spiny neurons in the nucleus accumbens (NAc). There were no changes in dendritic spine density or subtype in the mPFC of CTA rats while NAc spine density was significantly increased due to an enhanced prevalence of long-thin spines. Together, these findings suggest that the persistent effects of CTA on cognition are related to learning and memory consolidation/recall, but not mPFC-dependent behavioral flexibility.


Assuntos
Cognição/efeitos dos fármacos , Aprendizagem/efeitos dos fármacos , Núcleo Accumbens/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Tolueno/administração & dosagem , Animais , Condicionamento Clássico/efeitos dos fármacos , Condicionamento Operante/efeitos dos fármacos , Espinhas Dendríticas/efeitos dos fármacos , Espinhas Dendríticas/patologia , Extinção Psicológica/efeitos dos fármacos , Masculino , Núcleo Accumbens/patologia , Córtex Pré-Frontal/patologia , Ratos Sprague-Dawley
5.
Clin Oncol (R Coll Radiol) ; 28(10): 622-626, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27169593

RESUMO

The median survival in glioblastoma is just over a year, with no standard second-line therapy. Ipilimumab is an immune checkpoint inhibitor that activates the anti-tumour immune response by cytotoxic T-lymphocyte antigen-4 blockade. There is significant evidence supporting its role in the treatment of malignant melanoma, including in patients with brain metastases. The addition of the anti-angiogenesis agent, bevacizumab, seems to offer additional benefit and limit the immune-related side-effects of ipilimumab in melanoma. To date there have been no clinical trials investigating this combination in glioblastoma. In this single practice case series, 20 patients with glioblastoma were consented for and treated with ipilimumab and bevacizumab in combination. Safety, tolerability and the response to treatment were reviewed for all patients. Three patients were treated after palliative first-line radiotherapy, one patient after first-line chemoradiation and 16 patients were treated with recurrent disease. Sixty-five per cent of patients completed four cycles of 3 weekly ipilimumab therapy, administered with 2 weekly bevacizumab. Radiographic responses for patients with recurrent disease were evaluated by Response Assessment in Neuro-oncology (RANO) criteria; 31% of patients showed a partial response, 31% had stable disease and 38% had disease progression. The treatment combination was well tolerated, with treatment terminated before completion due to adverse events in two patients. Autoimmune toxicity was manageable with systemic corticosteroid therapy. Ipilimumab and bevacizumab in combination show promising activity with a predictable and manageable toxicity profile, warranting further clinical studies.


Assuntos
Inibidores da Angiogênese/uso terapêutico , Anticorpos Monoclonais Humanizados/uso terapêutico , Anticorpos Monoclonais/uso terapêutico , Bevacizumab/uso terapêutico , Neoplasias Encefálicas/tratamento farmacológico , Glioblastoma/tratamento farmacológico , Adulto , Idoso , Inibidores da Angiogênese/efeitos adversos , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais Humanizados/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica , Bevacizumab/efeitos adversos , Neoplasias Encefálicas/patologia , Terapia Combinada , Feminino , Humanos , Ipilimumab , Masculino , Melanoma , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/patologia , Neoplasias Cutâneas , Resultado do Tratamento , Adulto Jovem , Melanoma Maligno Cutâneo
6.
Br J Cancer ; 109(4): 827-35, 2013 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-23887607

RESUMO

Next-generation sequencing (NGS) of cancer genomes promises to revolutionise oncology, with the ability to design and use targeted drugs, to predict outcome and response, and to classify tumours. It is continually becoming cheaper, faster and more reliable, with the capability to identify rare yet clinically important somatic mutations. Technical challenges include sequencing samples of low quality and/or quantity, reliable identification of structural and copy number variation, and assessment of intratumour heterogeneity. Once these problems are overcome, the use of the data to guide clinical decision making is not straightforward, and there is a risk of premature use of molecular changes to guide patient management in the absence of supporting evidence. Paradoxically, NGS may simply move the bottleneck of personalised medicine from data acquisition to the identification of reliable biomarkers. Standardised cancer NGS data collection on an international scale would be a significant step towards optimising patient care.


Assuntos
Neoplasias/genética , Genoma , Humanos , Técnicas de Diagnóstico Molecular , Mutação , Neoplasias/diagnóstico , Medicina de Precisão , Análise de Sequência de DNA
7.
Oncogenesis ; 2: e41, 2013 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-23545860

RESUMO

Despite an improved understanding of the molecular aberrations that occur in glioblastoma, the use of molecularly targeted therapies have so far been disappointing. We present a patient with three different brain tumours: astrocytoma, glioblastoma and gliosarcoma. Genetic analysis showed that the three different brain tumours were derived from a common origin but had each developed unique genetic aberrations. Included in these, the glioblastoma had PDGFRA amplification, whereas the gliosarcoma had MYC amplification. We propose that genetic heterogeneity contributes to treatment failure and requires comprehensive assessment in the era of personalised medicine.

8.
OA Alcohol ; 1(1): 2, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-24432188

RESUMO

Alcohol use disorders (AUDs) are a major public health issue and have an enormous social and economic burden in developed, developing, and third-world countries. Current pharmacotherapies for treating AUDs suffer from deleterious side effects and are only effective in preventing relapse in a subset of individuals. This signifies an essential need for improved medications to reduce heavy episodic drinking and alcohol-related problems. Growing literature has provided support for the use of anticonvulsants in suppressing symptoms induced by alcohol withdrawal. Emerging clinical and preclinical evidence suggests that a number of well-tolerated anticonvulsants may also decrease alcohol drinking. This review will focus on recent evidence supporting the efficacy of novel anticonvulsants in reducing voluntary alcohol consumption in rodent models. The data demonstrate that anticonvulsants reduce drinking in standard home cage two-bottle choice paradigms, self-administration of alcohol in operant chambers, and cue- and stress-induced reinstatement of alcohol seeking behaviors in rats and mice. This review also highlights evidence that some anticonvulsants were only moderately effective in reducing drinking in select strains of rodents or models. This suggests that genetics, possible neuroadaptations, or the pharmacological target affect the ability of anticonvulsants to attenuate alcohol consumption. Nonetheless, anticonvulsants are relatively safe, have little abuse potential, and can work in combination with other drugs. The results from these preclinical and clinical studies provide compelling evidence that anticonvulsants are a promising class of medication for the treatment of AUDs.

9.
Neuroscience ; 165(2): 525-34, 2010 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-19837138

RESUMO

Excess glutamate release and stimulation of post-synaptic glutamatergic receptors have been implicated in the pathophysiology of many neurological diseases. The hippocampus, and the pyramidal cell layer of the cornu ammonus 1 (CA1) region in particular, has been noted for its selective sensitivity to excitotoxic insults. The current studies examined the role of N-methyl-D-aspartate (NMDA) receptor subunit composition and sensitivity to stimulatory effects of the polyamine spermidine, an allosteric modulator of NMDA NR2 subunit activity, in hippocampal CA1 region sensitivity to excitotoxic insult. Organotypic hippocampal slice cultures of 8 day-old neonatal rat were obtained and maintained in vitro for 5 days. At this time, immunohistochemical analysis of mature neuron density (NeuN); microtubule associated protein-2(a,b) density (MAP-2); and NMDA receptor NR1 and NR2B subunit density in the primary cell layers of the dentate gyrus (DG), CA3, and CA1 regions, was conducted. Further, autoradiographic analysis of NMDA receptor distribution and density (i.e. [(125)I]MK-801 binding) and spermidine (100 microM)-potentiated [(125)I]MK-801 binding in the primary cell layers of these regions was examined. A final series of studies examined effects of prolonged exposure to NMDA (0.1-10 microM) on neurodegeneration in the primary cell layers of the DG, CA3, and CA1 regions, in the absence and presence of spermidine (100 microM) or ifenprodil (100 microM), an allosteric inhibitor of NR2B polypeptide subunit activity. The pyramidal cell layer of the CA1 region demonstrated significantly greater density of mature neurons, MAP-2, NR1 and NR2B subunits, and [(125)I]MK-801 binding than the CA3 region or DG. Twenty-four hour NMDA (10 microM) exposure produced marked neurodegeneration (approximately 350% of control cultures) in the CA1 pyramidal cell region that was significantly reduced by co-exposure to ifenprodil or DL-2-Amino-5-phosphonopentanoic acid (APV). The addition of spermidine significantly potentiated [(125)I]MK-801 binding and neurodegeneration induced by exposure to a non-toxic concentration of NMDA, exclusively in the CA1 region. This neurodegeneration was markedly reduced with co-exposure to ifenprodil. These data suggest that selective sensitivity of the CA1 region to excitotoxic stimuli may be attributable to the density of mature neurons expressing polyamine-sensitive NR2B polypeptide subunits.


Assuntos
Hipocampo/efeitos dos fármacos , Neurotoxinas/toxicidade , Células Piramidais/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/metabolismo , Espermidina/toxicidade , Animais , Região CA1 Hipocampal/efeitos dos fármacos , Região CA1 Hipocampal/metabolismo , Região CA3 Hipocampal/efeitos dos fármacos , Região CA3 Hipocampal/metabolismo , Giro Denteado/efeitos dos fármacos , Giro Denteado/metabolismo , Maleato de Dizocilpina/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Feminino , Hipocampo/metabolismo , Técnicas In Vitro , Masculino , N-Metilaspartato/metabolismo , Degeneração Neural/induzido quimicamente , Degeneração Neural/tratamento farmacológico , Degeneração Neural/metabolismo , Fármacos Neuroprotetores/farmacologia , Piperidinas/farmacologia , Células Piramidais/metabolismo , Ratos , Ratos Sprague-Dawley , Valina/análogos & derivados , Valina/farmacologia
10.
Neuroscience ; 165(1): 130-7, 2010 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-19850106

RESUMO

Activation of glutamate receptors is known to modulate K(+) channel surface trafficking, phosphorylation, and function, and increasing evidence has implicated K(+) channels in plastic changes in glutamatergic synapses. Kv4.2 channels control the amplitude of back-propagating action potentials and shape postsynaptic responses in hippocampus, and synaptic glutamate receptor activation leads to increased phosphorylation of Kv4.2 channels that is associated with enhanced synaptic plasticity. Thus, we investigated the possibility that activation of extrasynaptic NMDA-type glutamate receptors couples to Kv4.2 channel dephosphorylation. In hippocampal neurons, we found that selective activation of extrasynaptic NMDA receptors dephosphorylates Kv4.2 channels, and driving synaptic activity increases phosphorylation of Kv4.2. We also observed that Ca(2+) entry through NMDA receptors is necessary for dephosphorylation of Kv4.2 channels. Consistent with a synaptic and extrasynaptic localization at hippocampal synapses, a fraction of Kv4.2 channel clusters was found to localize outside of pre- and postsynaptic markers. Excitatory amino acid transporters (EAATs) regulate ambient extracellular glutamate levels that active extrasynaptic NMDA receptors, and inhibition of glutamate uptake by blocking EAATs with the non-selective transporter inhibitor dl-threo-beta-benzyloxyaspartic acid (TBOA) or the EAAT1/3 selective inhibitor l-serine O-sulfate (SOS) dephosphorylates Kv4.2 channels. These findings in conjunction with previous reports support the interesting possibility that synaptic and extrasynaptic NMDA receptors bi-directionally regulate phosphorylation levels of Kv4.2 channels in hippocampus. Moreover, we observed that EAAT activity controls extrasynaptic NMDA receptor modulation of Kv4.2 channel dephosphorylation.


Assuntos
Sistema X-AG de Transporte de Aminoácidos/antagonistas & inibidores , Hipocampo/metabolismo , Receptores de N-Metil-D-Aspartato/agonistas , Canais de Potássio Shal/metabolismo , Animais , Animais Recém-Nascidos , Cálcio/metabolismo , Análise por Conglomerados , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos C3H , Pentilenotetrazol , Fosforilação , Transporte Proteico , Ratos , Ratos Sprague-Dawley , Convulsões/induzido quimicamente , Convulsões/metabolismo
11.
Ecology ; 89(12): 3515-27, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19137956

RESUMO

Allochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of 15N as nitrate in six streams differing in riparian-stream interaction and metabolic character. Nitrate removal was quantified using a nutrient spiraling approach based on measurements of downstream decline in 15N flux. Respiration (R) and gross primary production (GPP) were measured with whole-stream diel oxygen budgets. Uptake and metabolism metrics were addressed as z scores relative to site means to assess temporal variation. In open-canopied streams, areal uptake (U; microg N x m(-2) x s(-1)) was closely related to GPP, metabolic rates increased with temperature, and R was accurately predicted by metabolic scaling relationships. In forested streams, N spiraling was not related to GPP; instead, uptake velocity (v(f); mm/s) was closely related to R. In contrast to open-canopied streams, N uptake and metabolic activity were negatively correlated to temperature and poorly described by scaling laws. We contend that streams differ along a gradient of exogenous and endogenous control that relates to the relative influences of resource subsidies and in-stream energetics as determinants of seasonal patterns of metabolism and N cycling. Our research suggests that temporal variation in the propagation of ecological influence between adjacent systems generates phases when ecosystems are alternatively characterized as endogenously and exogenously controlled.


Assuntos
Ecossistema , Monitoramento Ambiental/métodos , Água Doce/química , Nitrogênio/análise , Nitrogênio/metabolismo , Carbono/análise , Carbono/metabolismo , Isótopos de Nitrogênio , Rios , Estações do Ano
13.
Neuroscience ; 151(2): 419-27, 2008 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-18055129

RESUMO

NMDA receptors bidirectionally modulate extracellular signal-regulated kinase (ERK) through the coupling of synaptic NMDA receptors to an ERK activation pathway that is opposed by a dominant ERK shutoff pathway thought to be coupled to extrasynaptic NMDA receptors. In the present study, synaptic NMDA receptor activation of ERK in rat cortical cultures was partially inhibited by the highly selective NR2B antagonist Ro25-6981 (Ro) and the less selective NR2A antagonist NVP-AAM077 (NVP). When Ro and NVP were added together, inhibition appeared additive and equal to that observed with the NMDA open-channel blocker MK-801. Consistent with a selective coupling of extrasynaptic NMDA receptors to the dominant ERK shutoff pathway, pre-block of synaptic NMDA receptors with MK-801 did not alter the inhibitory effect of bath-applied NMDA on ERK activity. Lastly, in contrast to a complete block of synaptic NMDA receptor activation of ERK by extrasynaptic NMDA receptors, activation of extrasynaptic NMDA receptors had no effect upon ERK activation by brain-derived neurotrophic factor. These results suggest that the synaptic NMDA receptor ERK activation pathway is coupled to both NR2A and NR2B containing receptors, and that the extrasynaptic NMDA receptor ERK inhibitory pathway is not a non-selective global ERK shutoff.


Assuntos
Fator Neurotrófico Derivado do Encéfalo/fisiologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Receptores de N-Metil-D-Aspartato/fisiologia , Transdução de Sinais/efeitos dos fármacos , Animais , Western Blotting , Fator Neurotrófico Derivado do Encéfalo/efeitos dos fármacos , Células Cultivadas , Córtex Cerebral/citologia , Córtex Cerebral/efeitos dos fármacos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/biossíntese , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Maleato de Dizocilpina , Ativação Enzimática/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/metabolismo , N-Metilaspartato , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Técnicas de Patch-Clamp , Fenóis/farmacologia , Piperidinas/farmacologia , Quinoxalinas/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores
14.
Palliat Med ; 21(4): 313-22, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17656408

RESUMO

BACKGROUND: There is consensus in the literature that the end of life care for patients with chronic illness is suboptimal, but research on the specific needs of this population is limited. AIM: This study aimed to use a mixed methodology and case study approach to explore the palliative care needs of patients with a non-cancer diagnosis from the perspectives of the patient, their significant other and the clinical team responsible for their care. Patients (n = 18) had a diagnosis of either end-stage heart failure, renal failure or respiratory disease. METHODS: The Short Form 36 and Hospital and Anxiety and Depression Questionnaire were completed by all patients. Unstructured interviews were (n = 35) were conducted separately with each patient and then their significant other. These were followed by a focus group discussion (n = 18) with the multiprofessional clinical team. Quantitative data were analysed using simple descriptive statistics and simple descriptive statistics. All qualitative data were taped, transcribed and analysed using Colaizzi's approach to qualitative analysis. FINDINGS: Deteriorating health status was the central theme derived from this analysis. It led to decreased independence, social isolation and family burden. These problems were mitigated by the limited resources at the individual's disposal and the availability of support from hospital and community services. Generally resources and support were perceived as lacking. All participants in this study expressed concerns regarding the patients' future and some patients described feelings of depression or acceptance of the inevitability of imminent death. CONCLUSION: Patients dying from chronic illness in this study had many concerns and unmet clinical needs. Care teams were frustrated by the lack of resources available to them and admitted they were ill-equipped to provide for the individual's holistic needs. Some clinicians described difficulty in talking openly with the patient and family regarding the palliative nature of their treatment. An earlier and more effective implementation of the palliative care approach is necessary if the needs of patients in the final stages of chronic illness are to be adequately addressed.


Assuntos
Avaliação das Necessidades , Cuidados Paliativos/métodos , Assistência Terminal/métodos , Doente Terminal/psicologia , Idoso , Idoso de 80 Anos ou mais , Atitude do Pessoal de Saúde , Atitude Frente a Morte , Cuidadores/psicologia , Doença Crônica , Feminino , Grupos Focais , Nível de Saúde , Humanos , Falência Renal Crônica/psicologia , Pneumopatias/psicologia , Masculino , Pessoa de Meia-Idade , Planejamento de Assistência ao Paciente , Escalas de Graduação Psiquiátrica , Pesquisa Qualitativa , Insuficiência Renal/psicologia
15.
Neuroscience ; 136(1): 259-67, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16182452

RESUMO

Many patients display elevated levels of serum cortisol following acute ischemic stroke. Given that glucocorticoids may potentiate some forms of insult, these studies examined the effects of corticosterone or dexamethasone exposure on cytotoxicity following oxygen-glucose deprivation in the cerebellum, a brain region susceptible to stroke. In organotypic cerebellar slice cultures prepared from neonatal rat pups, 90-min of oxygen-glucose deprivation at 15 days in vitro resulted in significant cytotoxicity at 24-, 48-, and 72-h post-oxygen-glucose deprivation, as measured by uptake of propidium iodide. Exposure of cultures following oxygen-glucose deprivation to the antioxidant trolox (500 microM), but not to the glucocorticoid receptor antagonist RU486 (10 microM), completely blocked oxygen-glucose deprivation-induced cytotoxicity. Corticosterone (1 microM) or dexamethasone (10 microM) exposure alone did not significantly increase propidium iodide uptake above levels observed in control cultures. However, corticosterone or dexamethasone exposure after oxygen-glucose deprivation potentiated oxygen-glucose deprivation-mediated propidium iodide uptake at each time point. Trolox, as well as RU486, co-exposure of cultures to corticosterone or dexamethasone after oxygen-glucose deprivation abolished all cytotoxicity. In conclusion, these data demonstrated that glucocorticoid exposure modulated oxygen-glucose deprivation-mediated propidium iodide uptake, which likely involved glucocorticoid receptor activation and pro-oxidant effects.


Assuntos
Cerebelo/efeitos dos fármacos , Cerebelo/fisiopatologia , Corticosterona/farmacologia , Dexametasona/farmacologia , Glucose/deficiência , Hipóxia/fisiopatologia , Animais , Antioxidantes/farmacologia , Morte Celular/efeitos dos fármacos , Cerebelo/metabolismo , Cromanos/farmacologia , Sinergismo Farmacológico , Feminino , Técnicas In Vitro , Masculino , Mifepristona/farmacologia , Propídio/farmacocinética , Ratos , Ratos Sprague-Dawley
16.
Neuroscience ; 135(4): 1129-39, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16165302

RESUMO

Nutritional deficiencies associated with long-term ethanol consumption may cause neuronal damage in ethanol-dependent individuals. Thiamine deficiency, in particular, is thought to contribute to ethanol-associated cerebellar degeneration, although damage may occur in adequately nourished alcoholics. Thus, the present study examined the effects of thiamine depletion and ethanol exposure on cytotoxicity in rat cerebellum. Organotypic cerebellar slice cultures were treated starting at 25 days in vitro with 100 mM ethanol for 11 days or 10 days followed by a 24-h withdrawal period. This exposure paradigm has previously been shown in hippocampal slice cultures to result in spontaneous cytotoxicity upon ethanol withdrawal. Additional cerebellar cultures were exposed to the thiamine depleting agent pyrithiamine (10-500 microM) for 10 or 11 days, some in the presence of ethanol exposure or withdrawal. Other cultures were co-exposed to thiamine (1-100 microM), 500 microM pyrithiamine, and ethanol for 10 or 11 days. The results demonstrated that neither 11-day ethanol treatment nor withdrawal from 10-day exposure significantly increased cerebellar cytotoxicity, as measured by propidium iodide fluorescence. The 11-day treatment with 100 or 500 microM pyrithiamine significantly increased propidium iodide fluorescence approximately 21% above levels observed in control tissue. Cultures treated with both ethanol (11 days or 10 days plus withdrawal) and 500 microM pyrithiamine displayed a marked increase in cytotoxicity approximately 60-90% above levels observed in control cultures. Pyrithiamine and ethanol-induced cytotoxicity was prevented in cultures co-exposed to thiamine (10-100 microM) for the duration of pyrithiamine treatment. Findings from this report suggest that the cerebellum may be more sensitive to the toxic effects of thiamine deficiency, as compared with alcohol withdrawal, associated with alcohol dependence.


Assuntos
Depressores do Sistema Nervoso Central/toxicidade , Cerebelo/efeitos dos fármacos , Cerebelo/patologia , Etanol/toxicidade , Deficiência de Tiamina/fisiopatologia , Animais , Feminino , Masculino , Técnicas de Cultura de Órgãos , Piritiamina/farmacologia , Ratos , Ratos Sprague-Dawley , Síndrome de Abstinência a Substâncias/fisiopatologia , Deficiência de Tiamina/induzido quimicamente
17.
Neuroscience ; 125(3): 671-82, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15099681

RESUMO

Hypercortisolemia, long-term exposure of the brain to high concentrations of stress hormones (i.e. cortisol), may occur in patients suffering from depression, alcoholism, and other disorders. This has been suggested to produce neuropathological effects, in part, via increased function or sensitivity of N-methyl-d-aspartate (NMDA)-type glutamate receptors. Given that cigarette smoking is highly prevalent in some of these patient groups and nicotine has been shown to reduce toxic consequences of NMDA receptor function, it may be suggested that nicotine intake may attenuate the neurotoxic effects of hypercortisolemia. To investigate this possibility, organotypic hippocampal slice cultures derived from rat were pre-treated with corticosterone (0.001-1 microM) alone or in combination with selective glucocorticoid receptor antagonists for 72-h prior to a brief (1-h) NMDA exposure (5 microM). Pre-treatment with corticosterone (0.001-1 microM) alone did not cause hippocampal damage, while NMDA exposure produced significant cellular damage in the cornu ammonis (CA)1 subregion. No significant damage was observed in the dentate gyrus or CA3 regions following NMDA exposure. Pre-treatment of cultures with corticosterone (0.1-1 microM) markedly exacerbated NMDA-induced CA1 and dentate gyrus region damage. This effect in the CA1 region was prevented by co-administration of the glucocorticoid receptor antagonist RU486 (>or=1 microM), but not spironolactone (1-10 microM), a mineralocorticoid receptor antagonist. In a second series of studies, both acute and pre-exposure of cultures to (-)-nicotine (1-10 microM) significantly reduced NMDA toxicity in the CA1 region. Co-administration of cultures to (-)-nicotine (1-10 microM) with 100 nM corticosterone prevented corticosterone's exacerbation of subsequent CA1 insult. This protective effect of (-)-nicotine was not altered by co-exposure of cultures to 10 microM dihydro-beta-erythroidine but was blocked by co-exposure to 100 nM methyllycaconitine, suggesting the involvement of nicotinic acetylcholine receptors possessing the alpha7* subunit. The present studies suggest a role for hypercortisolemia in sensitizing the hippocampal NMDA receptor system to pathological activation and indicate that prolonged nicotine exposure attenuates this sensitization. Thus, it is possible that one consequence of heavy smoking in those suffering from hypercortisolemia may be a reduction of neuronal injury and sparing of cellular function.


Assuntos
Aconitina/análogos & derivados , Corticosterona/antagonistas & inibidores , Hipocampo/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Nicotina/farmacologia , Receptores de N-Metil-D-Aspartato/metabolismo , Aconitina/farmacologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Corticosterona/farmacologia , Modelos Animais de Doenças , Interações Medicamentosas/fisiologia , Hipocampo/metabolismo , Hipocampo/patologia , Técnicas In Vitro , Masculino , Mifepristona/farmacologia , N-Metilaspartato/toxicidade , Neurônios/metabolismo , Neurônios/patologia , Fármacos Neuroprotetores/farmacologia , Neurotoxinas/toxicidade , Antagonistas Nicotínicos/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores de Glucocorticoides/antagonistas & inibidores , Receptores de Glucocorticoides/metabolismo , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Receptores Nicotínicos/efeitos dos fármacos , Receptores Nicotínicos/metabolismo , Receptor Nicotínico de Acetilcolina alfa7
18.
J Clin Oncol ; 21(21): 4009-15, 2003 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-14581424

RESUMO

PURPOSE: Squamous cell carcinoma of the esophagus remains an aggressive disease with a poor prognosis, even after curative-intent surgery. This article analyzes the impact of preoperative chemotherapy with mitomycin, ifosfamide, and cisplatin (MIC) on a cohort of 68 patients. PATIENTS AND METHODS: From 1988 to 1994, 68 patients with potentially operable squamous cell carcinoma of the esophagus were entered onto two phase II trials of neoadjuvant chemotherapy with mitomycin 6 mg/m2, ifosfamide 3 g/m2, and cisplatin 50 mg/m2 and received between two and four cycles of treatment at 3-weekly intervals. Two patients were removed from the analysis when they were found to have malignancy other than squamous cell carcinoma of the esophagus. RESULTS: Forty (61%) of 66 patients had a radiologic response to chemotherapy (18 complete responses and 22 partial responses), and 52 (79%) of 66 patients went on to have the primary tumor resected. There were nine pathologic complete responders, seven of whom remain fit and well after at least 60 months of follow-up. The overall median survival was 12.4 months (95% confidence interval, 9.6 to 18.8 months). The complete response and node-negative patients survived significantly longer than those in other categories (log-rank chi2 = 18.8; P <.001): on average 13 months longer than the node-positive or nonresected category (22.0 v 9.4 months). The toxicity of the regimen was low. CONCLUSION: MIC is an easily administered, well-tolerated, and efficacious regimen as neoadjuvant therapy for patients with squamous cell carcinoma of the esophagus. These results warrant further investigation.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/cirurgia , Neoplasias Esofágicas/tratamento farmacológico , Neoplasias Esofágicas/cirurgia , Terapia Neoadjuvante , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Carcinoma de Células Escamosas/diagnóstico por imagem , Carcinoma de Células Escamosas/mortalidade , Carcinoma de Células Escamosas/patologia , Cisplatino/administração & dosagem , Estudos de Coortes , Terapia Combinada , Esquema de Medicação , Neoplasias Esofágicas/diagnóstico por imagem , Neoplasias Esofágicas/mortalidade , Neoplasias Esofágicas/patologia , Esofagectomia , Feminino , Humanos , Ifosfamida/administração & dosagem , Masculino , Pessoa de Meia-Idade , Mitomicina/administração & dosagem , Recidiva Local de Neoplasia/diagnóstico por imagem , Recidiva Local de Neoplasia/mortalidade , Recidiva Local de Neoplasia/patologia , Irlanda do Norte , Radiografia , Análise de Sobrevida , Resultado do Tratamento
19.
Microb Ecol ; 43(1): 55-66, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11984629

RESUMO

The absolute amount of microbial biomass and relative contribution of fungi and bacteria are expected to vary among types of organic matter (OM) within a stream and will vary among streams because of differences in organic matter quality and quantity. Common types of benthic detritus [leaves, small wood, and fine benthic organic matter (FBOM)] were sampled in 9 small (1st-3rd order) streams selected to represent a range of important controlling factors such as surrounding vegetation, detritus standing stocks, and water chemistry. Direct counts of bacteria and measurements of ergosterol (a fungal sterol) were used to describe variation in bacterial and fungal biomass. There were significant differences in bacterial abundance among types of organic matter with higher densities per unit mass of organic matter on fine particles relative to either leaves or wood surfaces. In contrast, ergosterol concentrations were significantly greater on leaves and wood, confirming the predominance of fungal biomass in these larger size classes. In general, bacterial abundance per unit organic matter was less variable than fungal biomass, suggesting bacteria will be a more predictable component of stream microbial communities. For 7 of the 9 streams, the standing stock of fine benthic organic matter was large enough that habitat-weighted reach-scale bacterial biomass was equal to or greater than fungal biomass. The quantities of leaves and small wood varied among streams such that the relative contribution of reach-scale fungal biomass ranged from 10% to as much as 90% of microbial biomass. Ergosterol concentrations were positively associated with substrate C:N ratio while bacterial abundance was negatively correlated with C:N. Both these relationships are confounded by particle size, i.e., leaves and wood had higher C:N than fine benthic organic matter. There was a weak positive relationship between bacterial abundance and streamwater soluble reactive phosphorus concentration, but no apparent pattern between either bacteria or fungi and streamwater dissolved inorganic nitrogen. The variation in microbial biomass per unit organic matter and the relative abundance of different types of organic matter contributed equally to driving differences in total microbial biomass at the reach scale.


Assuntos
Bactérias , Ecossistema , Fungos , Microbiologia da Água , Biodegradação Ambiental , Biomassa , Carbono/metabolismo , Nitrogênio/metabolismo , Compostos Orgânicos , Tamanho da Partícula , Fósforo/metabolismo , Folhas de Planta/metabolismo , Movimentos da Água , Madeira
20.
Clin Oncol (R Coll Radiol) ; 13(3): 164-9, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11527288

RESUMO

Adenocarcinoma of the oesophagus is a systemic disease at presentation in the majority of patients. This article analyses the impact of preoperative chemotherapy on a cohort of 68 patients. From 1990 to 1996, 68 patients with potentially operable adenocarcinoma of the oesophagus were entered into three sequential Phase II trials of neoadjuvant chemotherapy with cisplatin/mitomycin C/ifosfamide, cisplatin/5-fluorouracil (5-FU) and mitomycin C/cisplatin/5-FU. Twenty-four (35%) patients had a radiological (4 complete; 20 partial) response to chemotherapy, and 52 (76%) went on to have the primary tumour resected. There was only one pathological complete responder. The overall median survival was 13 months (95% confidence interval (CI) 9-16). Survival for the 28 N(0) patients was 34 months (95% CI 14-60). The pattern of failure for resected patients was predominantly systemic (16/17). These results indicate that neoadjuvant chemotherapy followed by surgery for adenocarcinoma of the oesophagus achieves excellent local control. The dominance, however, of distant recurrence after surgery underlines the fact that, in the majority of patients, the only hope of improving results in the future is to develop better systemic therapies.


Assuntos
Adenocarcinoma/tratamento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Esofágicas/tratamento farmacológico , Terapia Neoadjuvante , Recidiva Local de Neoplasia , Adenocarcinoma/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Cisplatino/administração & dosagem , Neoplasias Esofágicas/cirurgia , Feminino , Fluoruracila/administração & dosagem , Seguimentos , Humanos , Ifosfamida/administração & dosagem , Masculino , Pessoa de Meia-Idade , Mitomicina/administração & dosagem , Análise de Sobrevida , Resultado do Tratamento
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