RESUMEN
Background: The process of developing patient management plans requires a series of clinical decision-making skills that can take years in practice to develop. For the inexperienced practitioner, providing a logical, systematic patient management framework may assist in clinical scenarios and accelerate their decision-making skill development. The purpose of this study was to assess whether a novel clinical management decision aid would improve the management decision-making of chiropractic students. Methods: A prospective before and after study tracked chiropractic master degree students in their final year of study across a 10-week period from February-May, 2017. Case-based assessments were performed at baseline, after initial exposure to the decision aid, and after repeated exposure over the course of the semester. Outcome measures included the results from the 3 assessments, scored out of 20 by two markers using a standardised marking rubric, then averaged and converted to percentages; and 2 feedback questionnaires, given after initial exposure and at 10 weeks. Results: A total of 75 students (44 males; 31 females) participated in the study. The mean score at baseline was 8.34/20 (41.7%) (95% CI: 7.98, 8.70; SD: 1.56) and after initial exposure was 9.52/20 (47.6%) (95% CI: 9.06, 9.98; SD: 2.02). The mean score after repeated exposure was 15.04/20 (75.2%) (95% CI: 14.46, 15.62; SD: 2.54). From baseline to initial exposure, there was a statistically significant absolute increase in mean score of 1.18/20 (5.9%) (95% CI: 0.6, 1.76; p < 0.0001), or a 2.82/20 (14.1%) relative improvement. From baseline to repeated exposure, there was a statistically significant absolute increase in mean score of 6.7/20 (33.5%) (95% CI: 6.02, 7.38; p < 0.0001), or a 16.06/20 (80.3%) relative improvement. The questionnaire results were also favourable. 56/75 (75%) participants agreed that the decision aid was easy to use and 46/75 (61%) of participants agreed that the decision aid improved their ability to integrate various management techniques. Conclusion: Implementing a clinical management decision aid into the teaching curriculum helped to facilitate the ability of chiropractic students to develop patient management plans.
Asunto(s)
Quiropráctica/educación , Toma de Decisiones Clínicas , Estudiantes de Medicina/psicología , Adulto , Técnicas de Apoyo para la Decisión , Femenino , Humanos , Masculino , Persona de Mediana Edad , Gestión de la Práctica Profesional , Estudios Prospectivos , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Chronic exposure of skeletal muscle to saturated fatty acids, such as palmitate (C16:0), enhances proinflammatory IKK-NFκB signaling by a mechanism involving the MAP kinase (Raf-MEK-ERK) pathway. Raf activation can be induced by its dissociation from the Raf-kinase inhibitor protein (RKIP) by diacylglycerol (DAG)-sensitive protein kinase C (PKC). However, whether these molecules mediate the proinflammatory action of palmitate, an important precursor for DAG synthesis, is currently unknown. Here, involvement of DAG-sensitive PKCs, RKIP, and the structurally related monounsaturated fatty acid palmitoleate (C16:1) on proinflammatory signaling are investigated. Palmitate, but not palmitoleate, induced phosphorylation/activation of the MEK-ERK-IKK axis and proinflammatory cytokine (IL-6, CINC-1) expression. Palmitate increased intramyocellular DAG and invoked PKC-dependent RKIP(Ser153) phosphorylation, resulting in RKIP-Raf1 dissociation and MEK-ERK signaling. These responses were mimicked by PMA, a DAG mimetic and PKC activator. However, while pharmacological inhibition of PKC suppressed PMA-induced activation of MEK-ERK-IKK signaling, activation by palmitate was upheld, suggesting that DAG-sensitive PKC and RKIP were dispensable for palmitate's proinflammatory action. Strikingly, the proinflammatory effect of palmitate was potently repressed by palmitoleate. This repression was not due to reduced palmitate uptake but linked to increased neutral lipid storage and enhanced cellular oxidative capacity brought about by palmitoleate's ability to restrain palmitate-induced mitochondrial dysfunction.
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Diglicéridos/metabolismo , Ácidos Grasos Monoinsaturados/farmacología , Mitocondrias/metabolismo , Palmitatos/farmacología , Transducción de Señal/efectos de los fármacos , Animales , Transporte Biológico/efectos de los fármacos , Línea Celular , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Quinasa I-kappa B/metabolismo , Inflamación/metabolismo , Inflamación/patología , Oxígeno/metabolismo , Proteínas de Unión a Fosfatidiletanolamina/metabolismo , Fosforilación/efectos de los fármacos , Proteína Quinasa C/metabolismo , Proteínas Proto-Oncogénicas c-raf/metabolismo , RatasRESUMEN
The relationship between glucose and lipid metabolism has been of significant interest in understanding the pathogenesis of obesity-induced insulin resistance. To gain insight into this metabolic paradigm, we explored the potential interplay between cellular glucose flux and lipid-induced metabolic dysfunction within skeletal muscle. Here, we show that palmitate (PA)-induced insulin resistance and proinflammation in muscle cells, which is associated with reduced mitochondrial integrity and oxidative capacity, can be attenuated under conditions of glucose withdrawal or glycolytic inhibition using 2-deoxyglucose (2DG). Importantly, these glucopenic-driven improvements coincide with the preservation of mitochondrial function and are dependent on PA oxidation, which becomes markedly enhanced in the absence of glucose. Intriguingly, despite its ability to upregulate mitochondrial PA oxidation, glucose withdrawal did not attenuate PA-induced increases in total intramyocellular diacylglycerol and ceramide. Furthermore, consistent with our findings in cultured muscle cells, we also report enhanced insulin sensitivity and reduced proinflammatory tone in soleus muscle from obese Zucker rats fed a 2DG-supplemented diet. Notably, this improved metabolic status after 2DG dietary intervention is associated with markedly reduced plasma free fatty acids. Collectively, our data highlight the key role that mitochondrial substrate availability plays in lipid-induced metabolic dysregulation both in vitro and in vivo.
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Antimetabolitos/farmacología , Desoxiglucosa/farmacología , Inflamación/metabolismo , Resistencia a la Insulina , Metabolismo de los Lípidos , Mitocondrias/metabolismo , Músculo Esquelético/metabolismo , Obesidad/metabolismo , Palmitatos/metabolismo , Transducción de Señal , Animales , Ácidos Grasos no Esterificados/metabolismo , Glucólisis/efectos de los fármacos , Immunoblotting , Inflamación/etiología , Masculino , Obesidad/complicaciones , Oxidación-Reducción , Estrés Oxidativo , Palmitatos/administración & dosificación , Ratas , Ratas Zucker , Regulación hacia ArribaRESUMEN
In recent decades, the antihyperglycemic biguanide metformin has been used extensively in the treatment of type 2 diabetes, despite continuing uncertainty over its direct target. In this article, using two independent approaches, we demonstrate that cellular actions of metformin are disrupted by interference with its metal-binding properties, which have been known for over a century but little studied by biologists. We demonstrate that copper sequestration opposes known actions of metformin not only on AMP-activated protein kinase (AMPK)-dependent signaling, but also on S6 protein phosphorylation. Biguanide/metal interactions are stabilized by extensive π-electron delocalization and by investigating analogs of metformin; we provide evidence that this intrinsic property enables biguanides to regulate AMPK, glucose production, gluconeogenic gene expression, mitochondrial respiration, and mitochondrial copper binding. In contrast, regulation of S6 phosphorylation is prevented only by direct modification of the metal-liganding groups of the biguanide structure, supporting recent data that AMPK and S6 phosphorylation are regulated independently by biguanides. Additional studies with pioglitazone suggest that mitochondrial copper is targeted by both of these clinically important drugs. Together, these results suggest that cellular effects of biguanides depend on their metal-binding properties. This link may illuminate a better understanding of the molecular mechanisms enabling antihyperglycemic drug action.
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Cobre/metabolismo , Hepatocitos/efectos de los fármacos , Hipoglucemiantes/farmacología , Metformina/farmacología , Adenilato Quinasa/metabolismo , Animales , Línea Celular , Células Cultivadas , Quelantes/farmacología , Glucosa/biosíntesis , Hepatocitos/metabolismo , Consumo de Oxígeno/efectos de los fármacos , Fosforilación/efectos de los fármacos , Ratas , Proteínas Quinasas S6 Ribosómicas/metabolismo , Transducción de Señal/efectos de los fármacos , Trientina/farmacologíaRESUMEN
BACKGROUND: Sustained exposure of pancreatic ß cells to an increase in saturated fatty acids induces pleiotropic effects on ß-cell function, including a reduction in stimulus-induced insulin secretion. The objective of this study was to investigate the effects of chronic over supply of palmitate upon glucose- and amino acid-stimulated insulin secretion (GSIS and AASIS, respectively) and autocrine-dependent insulin signalling with particular focus on the importance of ceramide, ERK and CaMKII signalling. PRINCIPAL FINDINGS: GSIS and AASIS were both stimulated by >7-fold resulting in autocrine-dependent activation of protein kinase B (PKB, also known as Akt). Insulin release was dependent upon nutrient-induced activation of calcium/calmodulin-dependent protein kinase II (CaMKII) and extracellular signal-regulated kinase (ERK) as their pharmacological inhibition suppressed GSIS/AASIS significantly. Chronic (48 h, 0.4 mM) palmitate treatment blunted glucose/AA-induced activation of CaMKII and ERK and caused a concomitant reduction (~75%) in GSIS/AASIS and autocrine-dependent activation of PKB. This inhibition could not be attributed to enhanced mitochondrial fatty acid uptake/oxidation or ceramide synthesis, which were unaffected by palmitate. In contrast, diacylglycerol synthesis was elevated suggesting increased palmitate esterification rather than oxidation may contribute to impaired stimulus-secretion coupling. Consistent with this, 2-bromopalmitate, a non-oxidisable palmitate analogue, inhibited GSIS as effectively as palmitate. CONCLUSIONS: Our results exclude changes in ceramide content or mitochondrial fatty acid handling as factors initiating palmitate-induced defects in insulin release from MIN6 ß cells, but suggest that reduced CaMKII and ERK activation associated with palmitate overload may contribute to impaired stimulus-induced insulin secretion.
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Aminoácidos/farmacología , Comunicación Autocrina/efectos de los fármacos , Glucosa/farmacología , Células Secretoras de Insulina/citología , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Palmitatos/farmacología , Animales , Apoptosis/efectos de los fármacos , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Línea Celular , Activación Enzimática/efectos de los fármacos , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Transducción de Señal/efectos de los fármacos , Factores de TiempoRESUMEN
Sustained over-supply of saturated non-esterified 'free' fatty acids has been shown to promote skeletal muscle insulin resistance, which may be driven, in part, by an increase in inflammatory signalling within this tissue. In the present manuscript we show that exposure of L6 myotubes to palmitate, a saturated fatty acid, induces activation of the NF-κB (nuclear factor κB) pathway {based on increased IKK [IκB (inhibitory κB) kinase] phosphorylation, IκBα loss and elevated interleukin-6 mRNA expression} and that this was associated with enhanced phosphorylation/activation of p38 MAPK (mitogen-activated protein kinase), JNK (c-Jun N-terminal kinase) and ERK (extracellular-signal-regulated kinase) as well as impaired insulin-dependent activation of PKB (protein kinase B)/Akt and glucose transport. NF-κB activation by palmitate was unaffected by pharmacological inhibition of p38 MAPK or JNK, but was suppressed significantly by inhibition of MEK (MAPK/ERK kinase)/ERK signalling. The importance of ERK with respect to downstream NF-κB signalling was underscored by the finding that PMA, a potent ERK activator, enhanced IKK phosphorylation. Strikingly, both palmitate- and PMA-induced activation of IKK/NF-κB were antagonized by AMPK (AMP-activated protein kinase) activators because of reduced ERK signalling. Although palmitate-induced activation of NF-κB was repressed by AMPK activation and by cellular overexpression of a mutated IκBα (S32A/S36A) super-repressor, this did not ameliorate the loss in insulin-stimulated PKB activation or glucose transport. Our results from the present study indicate that ERK plays a pivotal role in palmitate-induced activation of the IKK/NF-κB signalling axis and that AMPK can restrain the activity of this pro-inflammatory pathway. The finding that insulin resistance persists in myotubes in which NF-κB signalling has been repressed implies that palmitate and/or its lipid derivatives retain the capacity to impair insulin-regulated events independently of the increase in inflammatory signalling.