RESUMO
Health practitioners often insert and maintain central venous access devices (CVADs) as part of cancer care. One in four CVADs prematurely fail, which is associated with increased mortality, morbidity and a negative impact on quality of life. To support implementation of updated guidelines, eviQ Education developed a comprehensive, peer-reviewed, evidence-based CVADs eLearning package. An evaluation indicated that the eLearning supported clinicians' practice and increased knowledge and clinical competency in CVAD insertion and management.
Assuntos
Instrução por Computador , Neoplasias , Humanos , Qualidade de Vida , Competência Clínica , Escolaridade , Avaliação de Resultados da Assistência ao Paciente , Neoplasias/terapiaRESUMO
Effective eLearning design takes into account the learning needs and styles of users. eviQ Education, a program of the Cancer Institute NSW, considered evidence from user data to develop a range of clinical education resources in formats informed by user preferences, including mini-modules, videos and webinars. Through the website and mobile app, content is available on-demand, supporting health professionals to learn anytime, anywhere, on any device.
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Educação a Distância , Aprendizagem , Oncologia , Escolaridade , Academias e InstitutosRESUMO
Oncology clinicians must participate in continuing professional development (CPD) to stay up to date with best practice. The Cancer Institute NSW eviQ Education program produces evidence-based, peer-reviewed eLearning resources for oncology professionals. In response to user feedback, eviQ Education trialled a mobile app, EdApp, to improve accessibility of self-directed CPD materials. Following a pilot, users indicated that the EdApp improved CPD accessibility and user experience. EdApp will continue to be used to support evidence-based practice.
Assuntos
Aplicativos Móveis , Humanos , Escolaridade , Oncologia , Academias e Institutos , Pessoal de SaúdeRESUMO
BACKGROUND: Restraint is widely practised within inpatient mental health services and is considered a higher-risk procedure for patients and staff. There is a sparsity of evidence in respect of the efficacy of personal protective equipment (PPE) used during restraint for reducing risk of infection. METHODS: A series of choreographed restraint episodes were used to simulate contact contamination in research participants playing the roles of staff members and a patient. For comparison, one episode of simulated recording of physical observations was taken. Ultraviolet (UV) fluorescent material was used to track the simulated contact contamination, with analysis undertaken using established image registration techniques of UV photographs. This was repeated for three separate sets of PPE. RESULTS: All three PPE sets showed similar performance in protecting against contamination transfer. For teams not utilising coveralls, this was dependent upon effective cleansing as part of doffing. There were similar patterns of contamination for restraint team members assigned to specific roles, with hands and upper torso appearing to be higher-risk areas. The restraint-related contamination was 23 times higher than that observed for physical observations. DISCUSSION: A second layer of clothing that can be removed showed efficacy in reducing contact contamination. PPE fit to individual is important. Post-restraint cleansing procedures are currently inadequate, with new procedures for face and neck cleansing required. These findings leave scope for staff to potentially improve their appearance when donning PPE and engaging with distressed patients.
Assuntos
COVID-19/transmissão , Pessoal de Saúde/educação , Controle de Infecções/métodos , Transmissão de Doença Infecciosa do Paciente para o Profissional/prevenção & controle , Equipamento de Proteção Individual/normas , Restrição Física , Treinamento por Simulação , Controle Comportamental , Humanos , Pacientes Internados , SARS-CoV-2 , Reino Unido/epidemiologiaRESUMO
While compassion-focused therapy (CFT) holds significant promise as an intervention for survivors of sexual abuse, a history of abuse can uniquely impact an individual's capacity to cultivate compassion and may generate a fear of compassion. Understanding the specific perspectives of sexual abuse survivors may inform the application of CFT-based interventions with this client group. Two separate focus groups were established for this purpose, one with adult female survivors of sexual abuse (n = 7) and another with sexual abuse counselors (n = 7). Transcripts were analyzed according to a consensual qualitative research design. Analysis of the survivor focus group identified two core domains, Barriers to Compassion, including poor relational templates, negative perception of self, low coping self-efficacy, and fears, resistance, and misperceptions regarding self-compassion, and Factors Supporting Compassion, including support from others, compassion for others, high coping self-efficacy, motivation and hope for change, and timing and readiness for change. Analysis of the counselor focus group revealed three domains, Therapeutic Factors to Support Compassion, including counselor authenticity and modeling, gradual introduction with consideration to individual needs, acknowledgment of suffering and offering an alternative perspective; Factors Affecting Client Readiness and Capacity, including shame, self-blame, and negative sense of self, response from others, and difficulty in changing self-critical habits; and Anticipated Outcomes, including providing a hope and recovery focus, offering an alternative perspective and coping strategy, and restoring trust. Findings are discussed in relation to clinical implications and relevance to a CFT model of intervention.
Assuntos
Conselheiros , Delitos Sexuais , Adulto , Empatia , Feminino , Humanos , Vergonha , SobreviventesRESUMO
Naturopathy is the general practice of natural therapies. It emphasizes prevention, treatment, and promotion of optimal health through therapeutic modalities which encourage the self-healing process of the body. Formalized in the 19th century by the hydrotherapy and nature cure movement in Austria and Germany, naturopathy was introduced to Australia at the turn of the 20th century. It became popular since the 1970s due to social and cultural change characterized by the post-modern philosophy, as well as government policies highlighting individual responsibility and freedom of choice. Naturopathy is one of the most popular forms of complementary medicine in Australia today with naturopaths received 4.9 million consultations annually. Naturopathic consultations are sought for a variety of conditions and, in some areas, as a form of primary care, especially by middle-aged women who have a higher education level and a higher annual income. The number of Australian naturopaths was estimated to be over 4000 in 2017 and expects to grow to over 4600 by 2022, although this number is likely to be an underestimation. Australian naturopaths, as a predominantly female profession, work mainly in private clinical practice with nutritional medicine, herbal medicine, homeopathy, as well as massage therapies being the most common modalities used. There are also signs of greater integration with community pharmacies and integrative medicine clinics in major cities. The Bachelor's degree programs in Naturopathy has just become the only accredited entry-level qualification since late 2015. Currently, there are only 5 private colleges offering naturopathic education, a far cry from the 40 over in mid-2000. The profession continues to be self-regulated. There is no barrier of entry to practice and unqualified practitioners of naturopathy can potentially do harm to the public. The registration of naturopaths remains unresolved due to fragmented representation under many professional associations, disunity among the profession, and objections by certain health care lobbyists. There is a dearth of research demonstrating efficacy of the whole practice of naturopathy in Australia, which has directed the government's decision to withdraw it from private health insurance coverage from 2019. Moving forward, the whole system research of naturopathy in Australia will be in focus with the recent establishment of a practice-based research network and an international research consortium. With increasing scrutiny from evidence-based medicine, the present and future challenge to Australian naturopaths is centered on the integration of both scientific and traditional evidence to form the foundation of a person-centered, evidence-informed practice.
Assuntos
Terapias Complementares , Naturologia , Austrália , Terapias Complementares/educação , Terapias Complementares/organização & administração , Terapias Complementares/estatística & dados numéricos , HumanosRESUMO
INTRODUCTION: Irregular breathing motion exacerbates uncertainties throughout a course of radiation therapy. Breathing guidance has demonstrated to improve breathing motion consistency. This was the first clinical implementation of audiovisual biofeedback (AVB) breathing guidance over a course of liver stereotactic body radiotherapy (SBRT) investigating interfraction reproducibility. METHODS: Five liver cancer patients underwent a screening procedure prior to CT sim during which patients underwent breathing conditions (i) AVB, or (ii) free breathing (FB). Whichever breathing condition was more regular was utilised for the patient's subsequent course of SBRT. Respiratory motion was obtained from the Varian respiratory position monitoring (RPM) system (Varian Medical Systems). Breathing motion reproducibility was assessed by the variance of displacement across 10 phase-based respiratory bins over each patient's course of SBRT. RESULTS: The screening procedure yielded the decision to utilise AVB for three patients and FB for two patients. Over the course of SBRT, AVB significantly improved the relative interfraction motion by 32%, from 22% displacement difference for FB patients to 15% difference for AVB patients. Further to this, AVB facilitated sub-millimetre interfraction reproducibility for two AVB patients. CONCLUSION: There was significantly less interfraction motion with AVB than FB. These findings demonstrate that AVB is potentially a valuable tool in ensuring reproducible interfraction motion.
Assuntos
Biorretroalimentação Psicológica , Neoplasias Hepáticas/radioterapia , Radiocirurgia/métodos , Técnicas de Imagem de Sincronização Respiratória/métodos , Feminino , Humanos , Masculino , Movimento , Reprodutibilidade dos TestesRESUMO
Child sexual abuse can have long-term negative impacts across psychological, physical, and interpersonal domains. Some of the common issues for survivors of sexual abuse include shame and self-blame, attachment-based difficulties, avoidant coping strategies, and reduced capacity for self-compassion. Compassion-focused therapy is a transdiagnostic intervention that specifically responds to these concerns. Compassion-focused therapy was originally developed for clients who experience high levels of shame and self-criticism and aims to strengthen the soothing and affiliative system through the cultivation of compassion. This article will highlight the theoretical alignment between some of the common issues and impacts associated with experiences of sexual abuse, with the core underlying principles of compassion-focused therapy. This includes (a) the capacity of the therapy's evolutionary framework to reduce perceptions of self-blame, (b) the cultivation of compassion to respond to feelings of shame, (c) acknowledgment of the role of early attachment experiences and facilitation of corrective affiliative experiences, (d) regulation of the threat-based system following trauma, and (e) provision of an alternative to avoidant-based coping by responding to distress with compassion. It is proposed that the theoretical framework and core focus and aims of compassion-focused therapy are highly applicable for survivors of sexual abuse and therefore holds significant promise as a treatment option for this client group.
Assuntos
Sobreviventes Adultos de Maus-Tratos Infantis/psicologia , Abuso Sexual na Infância/terapia , Empatia , Psicoterapia/métodos , Vergonha , Adulto , Criança , Abuso Sexual na Infância/psicologia , Emoções , Feminino , Humanos , AutoimagemRESUMO
This case report details a clinical trial's first recruited liver cancer patient who underwent a course of stereotactic body radiation therapy treatment utilising audiovisual biofeedback breathing guidance. Breathing motion results for both abdominal wall motion and tumour motion are included. Patient 1 demonstrated improved breathing motion regularity with audiovisual biofeedback. A training effect was also observed.
Assuntos
Suspensão da Respiração , Imobilização/métodos , Neoplasias Hepáticas/cirurgia , Posicionamento do Paciente/métodos , Radiocirurgia/métodos , Idoso , Recursos Audiovisuais , Biorretroalimentação Psicológica , Humanos , Masculino , Movimento (Física) , Projetos Piloto , Resultado do TratamentoRESUMO
Dyslipidemia has been identified as an important pathogenic risk factor for diabetic neuropathy, but current animal models do not adequately reproduce the lipid profile observed in human diabetics (increased triglycerides with an elevated LDL-cholesterol and reduced HDL-cholesterol). High fat feeding of mice produces hyperlipidemia, but mice are resistant to increases in the LDL to HDL ratio, reducing the potential for peripheral lipid deposits to impact neuropathy, as is postulated to occur in human subjects. Genetic manipulations provide an alternative approach to reproducing a neuropathic plasma lipid profile. Based on findings from the atherosclerosis literature, we began with knockout of ApoE. Since knockout of ApoE alone only partially mimics the human diabetic lipid profile, we examined the impact of its combination with a well-characterized model of type 2 diabetes exhibiting neuropathy, the db/db mouse. We added further gene manipulations to increase hyperlipidemia by using mice with both ApoE and ApoB48 knockout on the ob/+ (leptin mutation) mice. In all of these models, we found that either the db/db or ob/ob genotypes had increased body weight, hyperlipidemia, hyperglycemia, and evidence of neuropathy compared with the control groups (db/+ or ob/+, respectively). We found that ApoE knockout combined with leptin receptor knockout produced a lipid profile most closely modeling human dyslipidemia that promotes neuropathy. ApoE knockout combined with additional ApoB48 and leptin knockout produced similar changes of smaller magnitude, but, notably, an increase in HDL-cholesterol. Our data suggest that the overall effects of ApoE knockout, either directly upon nerve structure and function or indirectly on lipid metabolism, are insufficient to significantly alter the course of diabetic neuropathy. Although these models ultimately do not deliver optimal lipid profiles for translational diabetic neuropathy research, they do present glycemic and lipid profile properties of value for future therapeutic investigations.
Assuntos
Apolipoproteínas E/genética , Apolipoproteínas E/fisiologia , Dislipidemias/genética , Dislipidemias/patologia , Doenças do Sistema Nervoso Periférico/genética , Doenças do Sistema Nervoso Periférico/patologia , Animais , Comportamento Animal/fisiologia , Glicemia/metabolismo , Peso Corporal/fisiologia , Colesterol/sangue , Interpretação Estatística de Dados , Modelos Animais de Doenças , Dislipidemias/complicações , Fenômenos Eletrofisiológicos , Leptina/genética , Lipídeos/sangue , Lipoproteínas/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Medição da Dor , Doenças do Sistema Nervoso Periférico/etiologia , Triglicerídeos/sangueRESUMO
Diabetic neuropathy (DN) is the most common complication of diabetes and is characterized by distal-to-proximal loss of peripheral nerve axons. The idea of tissue-specific pathological alterations in energy metabolism in diabetic complications-prone tissues is emerging. Altered nerve metabolism in type 1 diabetes models is observed; however, therapeutic strategies based on these models offer limited efficacy to type 2 diabetic patients with DN. Therefore, understanding how peripheral nerves metabolically adapt to the unique type 2 diabetic environment is critical to develop disease-modifying treatments. In the current study, we utilized targeted liquid chromatography-tandem mass spectrometry (LC/MS/MS) to characterize the glycolytic and tricarboxylic acid (TCA) cycle metabolomes in sural nerve, sciatic nerve, and dorsal root ganglia (DRG) from male type 2 diabetic mice (BKS.Cg-m+/+Lepr(db); db/db) and controls (db/+). We report depletion of glycolytic intermediates in diabetic sural nerve and sciatic nerve (glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-bisphosphate (sural nerve only), 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate, and lactate), with no significant changes in DRG. Citrate and isocitrate TCA cycle intermediates were decreased in sural nerve, sciatic nerve, and DRG from diabetic mice. Utilizing LC/electrospray ionization/MS/MS and HPLC methods, we also observed increased protein and lipid oxidation (nitrotyrosine; hydroxyoctadecadienoic acids) in db/db tissue, with a proximal-to-distal increase in oxidative stress, with associated decreased aconitase enzyme activity. We propose a preliminary model, whereby the greater change in metabolomic profile, increase in oxidative stress, and decrease in TCA cycle enzyme activity may cause distal peripheral nerves to rely on truncated TCA cycle metabolism in the type 2 diabetes environment.
Assuntos
Ciclo do Ácido Cítrico , Diabetes Mellitus Tipo 2/metabolismo , Neuropatias Diabéticas/metabolismo , Modelos Animais de Doenças , Glicólise , Estresse Oxidativo , Sistema Nervoso Periférico/metabolismo , Aconitato Hidratase/metabolismo , Animais , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/enzimologia , Neuropatias Diabéticas/enzimologia , Regulação para Baixo , Gânglios Espinais/enzimologia , Gânglios Espinais/metabolismo , Peroxidação de Lipídeos , Masculino , Camundongos , Camundongos Mutantes , Neurônios/enzimologia , Neurônios/metabolismo , Sistema Nervoso Periférico/enzimologia , Receptores para Leptina/genética , Receptores para Leptina/metabolismo , Nervo Isquiático/enzimologia , Nervo Isquiático/metabolismo , Nervo Sural/enzimologia , Nervo Sural/metabolismo , Tirosina/análogos & derivados , Tirosina/metabolismoRESUMO
Insulin resistance (IR) is the major feature of metabolic syndrome, including type 2 diabetes. IR studies are mainly focused on peripheral tissues, such as muscle and liver. There is, however, little knowledge about IR in neurons. In this study, we examined whether neurons develop IR in response to hyperinsulinemia. We first examined insulin signaling using adult dorsal root ganglion neurons as a model system. Acute insulin treatment resulted in time- and concentration-dependent activation of the signaling cascade, including phosphorylation of the insulin receptor, Akt, p70S6K, and glycogen synthase kinase-3ß. To mimic hyperinsulinemia, cells were pretreated with 20 nM insulin for 24 h and then stimulated with 20 nM insulin for 15 min. Chronic insulin treatment resulted in increased basal Akt phosphorylation. More importantly, acute insulin stimulation after chronic insulin treatment resulted in blunted phosphorylation of Akt, p70S6K, and glycogen synthase kinase-3ß. Interestingly, when the cells were treated with phosphatidylinositol 3-kinase pathway inhibitor, but not MAPK pathway inhibitor, chronic insulin treatment did not block acute insulin treatment-induced Akt phosphorylation. Insulin-induced Akt phosphorylation was lower in dorsal root ganglion neurons from BKS-db/db compared with control BKS-db+ mice. This effect was age dependent. Our results suggest that hyperinsulinemia cause IR by disrupting the Akt-mediated pathway. We also demonstrate that hyperinsulinemia increases the mitochondrial fission protein dynamin-related protein 1. Our results suggest a new theory for the etiology of diabetic neuropathy, i.e. that, similar to insulin dependent tissues, neurons develop IR and, in turn, cannot respond to the neurotrophic properties of insulin, resulting in neuronal injury and the development of neuropathy.
Assuntos
Gânglios Espinais/metabolismo , Hiperinsulinismo/metabolismo , Resistência à Insulina , Animais , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
Mitochondrial-mediated oxidative stress in response to high glucose is proposed as a primary cause of dorsal root ganglia (DRG) neuron injury in the pathogenesis of diabetic neuropathy. In the present study, we report a greater number of mitochondria in both myelinated and unmyelinated dorsal root axons in a well-established model of murine diabetic neuropathy. No similar changes were seen in younger diabetic animals without neuropathy or in the ventral motor roots of any diabetic animals. These findings led us to examine mitochondrial biogenesis and fission in response to hyperglycemia in the neurites of cultured DRG neurons. We demonstrate overall mitochondrial biogenesis via increases in mitochondrial transcription factors and increases in mitochondrial DNA in both DRG neurons and axons. However, this process occurs over a longer time period than a rapidly observed increase in the number of mitochondria in DRG neurites that appears to result, at least in part, from mitochondrial fission. We conclude that during acute hyperglycemia, mitochondrial fission is a prominent response, and excessive mitochondrial fission may result in dysregulation of energy production, activation of caspase 3, and subsequent DRG neuron injury. During more prolonged hyperglycemia, there is evidence of compensatory mitochondrial biogenesis in axons. Our data suggest that an imbalance between mitochondrial biogenesis and fission may play a role in the pathogenesis of diabetic neuropathy.
Assuntos
Axônios/ultraestrutura , Neuropatias Diabéticas/patologia , Mitocôndrias/fisiologia , Neurônios/patologia , Biogênese de Organelas , Fatores Etários , Animais , Axônios/patologia , Glicemia/fisiologia , Células Cultivadas , Neuropatias Diabéticas/genética , Modelos Animais de Doenças , Gânglios Espinais/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Glucose/farmacologia , Hiperglicemia/metabolismo , Hiperglicemia/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Transmissão/métodos , Proteínas Mitocondriais/metabolismo , Neuritos/efeitos dos fármacos , Neuritos/metabolismo , Neuritos/patologia , Neurônios/metabolismo , Estresse Oxidativo/fisiologia , Fenantridinas , Fatores de Tempo , Fatores de Transcrição/metabolismo , Canais de Ânion Dependentes de Voltagem/metabolismoRESUMO
Mitochondria are key regulators of cellular energy and are the focus of a large number of studies examining the regulation of mitochondrial dynamics and biogenesis in healthy and diseased conditions. One approach to monitoring mitochondrial biogenesis is to measure the rate of mitochondrial DNA (mtDNA) replication. We developed a sensitive technique to visualize newly synthesized mtDNA in individual cells to study mtDNA replication within subcellular compartments of neurons. The technique combines the incorporation of 5-bromo-2-deoxyuridine (BrdU) and/or 5-ethynyl-2'-deoxyuridine (EdU) into mtDNA, together with a tyramide signal amplification protocol. Employing this technique, we visualized and measured mtDNA biogenesis in individual cells. The labeling procedure for EdU allows for more comprehensive results by allowing the comparison of its incorporation with other intracellular markers, because it does not require the harsh acid or enzyme digests necessary to recover the BrdU epitope. In addition, the utilization of both BrdU and EdU permits sequential pulse-chase experiments to follow the intracellular localization of mtDNA replication. The ability to quantify mitochondrial biogenesis provides an essential tool for investigating the alterations in mitochondrial dynamics involved in the pathogenesis of multiple cellular disorders, including neuropathies and neurodegenerative diseases.
Assuntos
Bromodesoxiuridina/metabolismo , DNA Mitocondrial/biossíntese , DNA Mitocondrial/metabolismo , Desoxiuridina/análogos & derivados , Imagem Molecular/métodos , Coloração e Rotulagem/métodos , Animais , Linhagem Celular Tumoral , Desoxiuridina/metabolismo , Humanos , Camundongos , Neurônios/citologiaRESUMO
OBJECTIVE: Neuropathy is a frequent and severe complication of diabetes. Multiple metabolic defects in type 2 diabetic patients result in oxidative injury of dorsal root ganglia (DRG) neurons. Our previous work focused on hyperglycemia clearly demonstrates induction of mitochondrial oxidative stress and acute injury in DRG neurons; however, this mechanism is not the only factor that produces neuropathy in vivo. Dyslipidemia also correlates with the development of neuropathy, even in pre-diabetic patients. This study was designed to explore the contribution of dyslipidemia in neuropathy. RESEARCH DESIGN AND METHODS: Mice (n = 10) were fed a control (10% kcal %fat) or high-fat (45% kcal %fat) diet to explore the impact of plasma lipids on the development of neuropathy. We also examined oxidized lipid-mediated injury in cultured DRG neurons from adult rat using oxidized LDLs (oxLDLs). RESULTS: Mice on a high-fat diet have increased oxLDLs and systemic and nerve oxidative stress. They develop nerve conduction velocity (NCV) and sensory deficits prior to impaired glucose tolerance. In vitro, oxLDLs lead to severe DRG neuron oxidative stress via interaction with the receptor lectin-like oxLDL receptor (LOX)-1 and subsequent NAD(P)H oxidase activity. Oxidative stress resulting from oxLDLs and high glucose is additive. CONCLUSIONS: Multiple metabolic defects in type 2 diabetes directly injure DRG neurons through different mechanisms that all result in oxidative stress. Dyslipidemia leads to high levels of oxLDLs that may injure DRG neurons via LOX-1 and contribute to the development of diabetic neuropathy.
Assuntos
Neuropatias Diabéticas/etiologia , Neuropatias Diabéticas/fisiopatologia , Dislipidemias/complicações , Lipoproteínas LDL/metabolismo , Receptores Depuradores Classe E/metabolismo , Animais , Glicemia/metabolismo , Fragmentação do DNA , Diabetes Mellitus Tipo 2/complicações , Neuropatias Diabéticas/sangue , Gorduras na Dieta/efeitos adversos , Feminino , Gânglios Espinais/citologia , Gânglios Espinais/fisiopatologia , Teste de Tolerância a Glucose , Membro Posterior/fisiopatologia , Insulina/sangue , Lipídeos/sangue , Lipoproteínas LDL/efeitos adversos , Camundongos , Camundongos Endogâmicos C57BL , Fibras Nervosas/patologia , Condução Nervosa/fisiologia , Neurônios/citologia , Neurônios/fisiologia , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismoRESUMO
Elevated blood glucose is a key initiator of mechanisms leading to diabetic neuropathy. Increases in glucose induce acute mitochondrial oxidative stress in dorsal root ganglion (DRG) neurons, the sensory neurons normally affected in diabetic neuropathy, whereas Schwann cells are largely unaffected. We propose that activation of an antioxidant response in DRG neurons would prevent glucose-induced injury. In this study, mild oxidative stress (1 microM H2O2) leads to the activation of the transcription factor Nrf2 and expression of antioxidant (phase II) enzymes. DRG neurons are thus protected from subsequent hyperglycemia-induced injury, as determined by activation of caspase 3 and the TUNEL assay. Schwann cells display high basal antioxidant enzyme expression and respond to hyperglycemia and mild oxidative stress via further increases in these enzymes. The botanical compounds resveratrol and sulforaphane activate the antioxidant response in DRG neurons. Other drugs that protect DRG neurons and block mitochondrial superoxide, identified in a compound screen, have differential ability to activate the antioxidant response. Multiple cellular targets exist for the prevention of hyperglycemic oxidative stress in DRG neurons, and these form the basis for new therapeutic strategies against diabetic neuropathy.
Assuntos
Antioxidantes/metabolismo , Estresse Oxidativo , Células de Schwann/metabolismo , Células Receptoras Sensoriais/metabolismo , Animais , Western Blotting , Caspase 3/metabolismo , Ativação Enzimática , Hiperglicemia/metabolismo , Imuno-Histoquímica , Fator 2 Relacionado a NF-E2/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
Hyperglycemia-induced oxidative stress is an inciting event in the development of diabetic complications including diabetic neuropathy. Our observations of significant oxidative stress and morphological abnormalities in mitochondria led us to examine manganese superoxide dismutase (SOD2), the enzyme responsible for mitochondrial detoxification of oxygen radicals. We demonstrate that overexpression of SOD2 decreases superoxide (O(2)(-)) in cultured primary dorsal root ganglion (DRG) neurons and subsequently blocks caspase-3 activation and cellular injury. Underexpression of SOD2 in dissociated DRG cultures from adult SOD2(+/-) mice results in increased levels of O2-, activation of caspase-3 cleavage and decreased neurite outgrowth under basal conditions that are exacerbated by hyperglycemia. These profound changes in sensory neurons led us to explore the effects of decreased SOD2 on the development of diabetic neuropathy (DN) in mice. DN was assessed in SOD2(+/-) C57BL/6J mice and their SOD2(+/+) littermates following streptozotocin (STZ) treatment. These animals, while hyperglycemic, do not display any signs of DN. DN was observed in the C57BL/6Jdb/db mouse, and decreased expression of SOD2 in these animals increased DN. Our data suggest that SOD2 activity is an important cellular modifier of neuronal oxidative defense against hyperglycemic injury.
Assuntos
Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Fármacos Neuroprotetores/metabolismo , Superóxido Dismutase/metabolismo , Animais , Caspase 3/metabolismo , Células Cultivadas , Diabetes Mellitus/genética , Diabetes Mellitus Experimental , Neuropatias Diabéticas/metabolismo , Neuropatias Diabéticas/prevenção & controle , Ativação Enzimática , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Potenciais da Membrana , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Membranas Mitocondriais , Condução Nervosa , Neurônios Aferentes/metabolismo , Neurônios Aferentes/patologia , Estresse Oxidativo , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/deficiência , TransfecçãoRESUMO
The concept that oxidative stress is a key mediator of nerve injury in diabetes has led us to design therapies that target oxidative stress mechanisms. Using an in vitro model of glucose-treated dorsal root ganglion (DRG) neurons in culture, we can examine both free radical generation, using fluorimetric probes for reactive oxygen species, and cell death via the TUNEL assay. The cell culture system is scaled down to a 96-well plate format, and so is well suited to high-throughput screening. In the present study, we test the ability of three drugs, nicotinamide, allopurinol, and alpha-lipoic acid, alone and in combination to prevent DRG neuron oxidative stress and cell death. This combination of drugs is currently in clinical trial in type 1 diabetic patients. We demonstrate independent effects on oxidative stress and neuronal survival for the three drugs, and neuronal protection using the three drugs in combination. The data strengthen the rationale for the current clinical trial. In addition, we describe an effective tool for rapid preclinical testing of novel therapies against diabetic neuropathy.
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Hiperglicemia/metabolismo , Hiperglicemia/patologia , Estresse Oxidativo/efeitos dos fármacos , Animais , Antioxidantes/farmacologia , Técnicas de Cultura de Células , Morte Celular , Células Cultivadas , Gânglios Espinais/citologia , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/lesões , Glucose/farmacologia , Peróxido de Hidrogênio/farmacologia , Hiperglicemia/prevenção & controle , Peroxidação de Lipídeos , Modelos Biológicos , Neurônios/citologia , Neurônios/efeitos dos fármacos , Niacinamida/farmacologia , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Ácido Tióctico/farmacologiaRESUMO
Dorsal root ganglia neurons in culture die through programmed cell death when exposed to elevated glucose, providing an in vitro model system for the investigation of the mechanisms leading to diabetic neuropathy. This study examines the time course of programmed cell death induction, regulation of cellular antioxidant capacity, and the protective effects of antioxidants in neurons exposed to hyperglycemia. We demonstrate that the first 2 h of hyperglycemia are sufficient to induce oxidative stress and programmed cell death. Using fluorimetric analysis of reactive oxygen species (ROS) production, in vitro assays of antioxidant enzymes, and immunocytochemical assays of cell death, we demonstrate superoxide formation, inhibition of aconitase, and lipid peroxidation within 1 h of hyperglycemia. These are followed by caspase-3 activation and DNA fragmentation. Antioxidant potential increases by 3-6 h but is insufficient to protect these neurons. Application of the antioxidant alpha-lipoic acid potently prevents glucose-induced oxidative stress and cell death. This study identifies cellular therapeutic targets to prevent diabetic neuropathy. Since oxidative stress is a common feature of the micro- and macrovascular complications of diabetes, the present findings have broad application to the treatment of diabetic patients.
Assuntos
Apoptose , Hiperglicemia/patologia , Hiperglicemia/fisiopatologia , Neurônios/patologia , Neurônios/fisiologia , Estresse Oxidativo , Aconitato Hidratase/antagonistas & inibidores , Animais , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Caspase 3 , Caspases/metabolismo , Catalase/metabolismo , Células Cultivadas , Fragmentação do DNA , Ativação Enzimática , Gânglios Espinais , Glucose/farmacologia , Glutationa/análise , Peroxidação de Lipídeos , Complexos Multienzimáticos/metabolismo , NADH NADPH Oxirredutases/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/metabolismo , Superóxidos/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Ácido Tióctico/farmacologia , Fatores de TempoRESUMO
A previous study from our laboratory suggested that prostate cancer metastasis to bone may be mediated, in part, by preferential adhesion to human bone marrow endothelial (HBME) cells. Tumor cell adhesion to endothelial cells may be modulated by the effect of cytokines on cell adhesion molecules (CAMs). Tumor necrosis factor-alpha (TNF-alpha) regulates VCAM expression on the endothelium and this effect is enhanced by dihydrotestosterone (DHT). Transforming growth factor-beta (TGF-beta) stimulates the expression of alpha2beta1 integrin on PC-3 cells. The current study investigated the effects of the above cytokines and DHT (singularly and in various combinations) upon HBME and prostate cancer cell expression of VCAM, alpha2 integrin subunit, and beta1 integrin subunit by flow cytometry. We also monitored the effects of the above treatments on PC-3 cell adhesion to HBME monolayers. The data demonstrate that none of the treatments significantly altered the expression of selected CAMs on HBME cell and neoplastic prostate cell lines. The treatment of HBME monolayers with various combinations of cytokines and DHT prior to performing adhesion assays with PC-3 demonstrates that treatments containing TGF-beta reduced PC-3 cell adhesion to HBME monolayers by 32% or greater (P < 0.05). The reduction in PC-3 cell adhesion to TGF-beta-treated HBME monolayers was dose dependent. Interestingly, LNCaP cells but not PC-3 cells treated with TGF-beta had a reduced ability to adhere to untreated HBME monolayers. These results suggest that TGF-beta may reduce tumor cell adhesion to bone marrow microvascular endothelium, in vivo. The biological significance of this observation is discussed.