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Duchenne Muscular Dystrophy (DMD) is a fatal X-linked genetic disorder. In DMD, the absence of the dystrophin protein causes decreased sarcolemmal integrity resulting in progressive replacement of muscle with fibrofatty tissue. The effects of lacking dystrophin on muscle and systemic metabolism are still unclear. Therefore, to determine the impact of the absence of dystrophin on metabolism, we investigated the metabolic and lipid profile at two different, well-defined stages of muscle damage and stabilization in mdx mice. We measured NMR-detectable metabolite and lipid profiles in the serum and muscles of mdx mice at 6 and 24 weeks of age. Metabolites were determined in muscle in vivo using 1 H MRI/MRS, in isolated muscles using 1 H-HR-MAS NMR, and in serum using high resolution 1 H/13 C NMR. Dystrophic mice were found to have a unique lipid saturation profile compared with control mice, revealing an age-related metabolic change. In the 6-week-old mdx mice, serum lipids were increased and the degree of lipid saturation changed between 6 and 24 weeks. The serum taurine-creatine ratio increased over the life span of mdx, but not in control mice. Furthermore, the saturation index of lipids increased in the serum but decreased in the tissue over time. Finally, we demonstrated associations between MRI-T2 , a strong indicator of inflammation/edema, with tissue and serum lipid profiles. These results indicate the complex temporal changes of metabolites in the tissue and serum during repetitive bouts of muscle damage and regeneration that occur in dystrophic muscle.
Assuntos
Envelhecimento/metabolismo , Lipídeos/química , Metaboloma , Metabolômica , Distrofia Muscular Animal/metabolismo , Animais , Glicemia/análise , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Lipídeos/sangue , Imageamento por Ressonância Magnética , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos mdx , Análise Multivariada , Músculo Esquelético/metabolismo , Distrofia Muscular Animal/sangue , Análise de Componente PrincipalRESUMO
Assessment of muscle pathology is a key outcome measure to measure the success of clinical trials studying muscular dystrophies; however, few robust minimally invasive measures exist. Indocyanine green (ICG)-enhanced near-infrared (NIR) optical imaging offers an objective, minimally invasive, and longitudinal modality that can quantify pathology within muscle by imaging uptake of ICG into the damaged muscles. Dystrophic mice lacking dystrophin (mdx) or gamma-sarcoglycan (Sgcg-/-) were compared to control mice by NIR optical imaging and magnetic resonance imaging (MRI). We determined that optical imaging could be used to differentiate control and dystrophic mice, visualize eccentric muscle induced by downhill treadmill running, and restore the membrane integrity in Sgcg-/- mice following adeno-associated virus (AAV) delivery of recombinant human SGCG (desAAV8hSGCG). We conclude that NIR optical imaging is comparable to MRI and can be used to detect muscle damage in dystrophic muscle as compared to unaffected controls, monitor worsening of muscle pathology in muscular dystrophy, and assess regression of pathology following therapeutic intervention in muscular dystrophies.
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Imageamento por Ressonância Magnética/métodos , Distrofias Musculares/diagnóstico por imagem , Imagem Óptica/métodos , Sarcoglicanas/genética , Animais , Meios de Contraste , Modelos Animais de Doenças , Distrofina/genética , Terapia Genética , Vetores Genéticos/administração & dosagem , Humanos , Camundongos , Camundongos Endogâmicos mdx , Músculo Esquelético/diagnóstico por imagem , Distrofias Musculares/genética , Distrofias Musculares/terapia , Sarcoglicanas/administração & dosagemRESUMO
Muscle damage is currently assessed through methods such as muscle biopsy, serum biomarkers, functional testing, and imaging procedures, each with its own inherent limitations, and a pressing need for a safe, repeatable, inexpensive, and noninvasive modality to assess the state of muscle health remains. Our aim was to develop and assess near-infrared (NIR) optical imaging as a novel noninvasive method of detecting and quantifying muscle damage. An immobilization-reambulation model was used for inducing muscle damage and recovery in the lower hindlimbs in mice. Confirmation of muscle damage was obtained using in vivo indocyanine green-enhanced NIR optical imaging, magnetic resonance imaging, and ex vivo tissue analysis. The soleus of the immobilized-reambulated hindlimb was found to have a greater amount of muscle damage compared to that in the contralateral nonimmobilized limb, confirmed by in vivo indocyanine green-enhanced NIR optical imaging (3.86-fold increase in radiant efficiency), magnetic resonance imaging (1.41-fold increase in T2), and an ex vivo spectrophotometric assay of indocyanine green uptake (1.87-fold increase in normalized absorbance). Contrast-enhanced NIR optical imaging provides a sensitive, rapid, and noninvasive screening method that can be used for imaging and quantifying muscle damage and recovery in vivo.
Assuntos
Corantes , Verde de Indocianina , Músculo Esquelético/diagnóstico por imagem , Imagem Óptica/métodos , Animais , Imageamento por Ressonância Magnética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/lesões , Músculo Esquelético/patologia , Sensibilidade e Especificidade , Espectroscopia de Luz Próxima ao Infravermelho , Fatores de TempoRESUMO
The emergence of gene editing technologies offers a unique opportunity to develop mutation-specific treatments for pediatric neurological disorders. Gene editing systems can potentially alter disease trajectory by correcting dysfunctional mutations or therapeutically altering gene expression. Clustered regularly interspaced short palindromic repeats (CRISPR)-based approaches are attractive gene therapy platforms to personalize treatments because of their specificity, ease of design, versatility, and cost. However, many such approaches remain in the early stages of development, with ongoing efforts to optimize editing efficiency, minimize unintended off-target effects, and mitigate pathologic immune responses. Given the rapid evolution of CRISPR-based therapies, it is prudent for the clinically based child neurologist to have a conceptual understanding of what such therapies may entail, including both benefits and risks and how such therapies may be clinically applied. In this review, we describe the fundamentals of CRISPR-based therapies, discuss the opportunities and challenges that have arisen, and highlight preclinical work in several pediatric neurological diseases.
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Distrofia Muscular de Duchenne , Doenças do Sistema Nervoso , Humanos , Criança , Edição de Genes/métodos , Sistemas CRISPR-Cas/genética , Terapia Genética , Doenças do Sistema Nervoso/genética , Doenças do Sistema Nervoso/terapiaRESUMO
BACKGROUND: Sensitive, objective, and longitudinal outcome measures applicable to both pre-clinical and clinical interventions are needed to assess muscle health in Duchenne muscular dystrophy (DMD). Electrical impedance myography (EIM) has the potential to non-invasively measure disease progression in mice and boys with DMD. OBJECTIVE: We sought to evaluate how electrical impedance values (i.e., phase, reactance, and resistance) correlate to established measures of disease in both D2-mdx and wild type (WT) mice and boys with and without DMD. METHODS: Histological, functional, and EIM data collected from previous studies of WT and D2-mdx mice at 6, 13, 21 and 43 weeks of age were reanalyzed. In parallel, previously collected functional outcome measures and EIM values were reanalyzed from boys with and without DMD at four different age groups from 2 to 14 years old. RESULTS: In mice, disease progression as detected by histological, functional, and EIM measures, was appreciable over this time period and grip strength best correlated to longitudinal phase and reactance impedance values. In boys, disease progression quantified through commonly utilized functional outcome measures was significant and longitudinal phase demonstrated the strongest correlation with functional outcome measures. CONCLUSION: Similar changes in EIM values, specifically in longitudinal reactance and phase, were found to show significant correlations to functional measures in both mice and boys. Thus, EIM demonstrates applicability in both pre-clinical and clinical settings and can be used as a safe, non-invasive, and longitudinal proxy biomarker to assess muscle health in DMD.
Assuntos
Distrofia Muscular de Duchenne , Camundongos , Animais , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/patologia , Camundongos Endogâmicos mdx , Músculo Esquelético/patologia , Impedância Elétrica , Progressão da Doença , MiografiaRESUMO
In this study, we compared multiple quantitative ultrasound metrics for the purpose of differentiating muscle in 20 healthy, 10 dystrophic and 10 obese mice. High-frequency ultrasound scans were acquired on dystrophic (D2-mdx), obese (db/db) and control mouse hindlimbs. A total of 248 image features were extracted from each scan, using brightness-mode statistics, Canny edge detection metrics, Haralick features, envelope statistics and radiofrequency statistics. Naïve Bayes and other classifiers were trained on single and pairs of features. The a parameter from the Homodyned K distribution at 40 MHz achieved the best univariate classification (accuracy = 85.3%). Maximum classification accuracy of 97.7% was achieved using a logistic regression classifier on the feature pair of a2 (K distribution) at 30 MHz and brightness-mode variance at 40MHz. Dystrophic and obese mice have muscle with distinct acoustic properties and can be classified to a high level of accuracy using a combination of multiple features.
Assuntos
Distrofia Muscular de Duchenne , Animais , Teorema de Bayes , Camundongos , Camundongos Endogâmicos mdx , Músculo Esquelético/diagnóstico por imagem , Obesidade/diagnóstico por imagemRESUMO
As the drug development pipeline for Duchenne muscular dystrophy (DMD) rapidly advances, clinical trial outcomes need to be optimized. Effective assessment of disease burden, natural history progression, and response to therapy in clinical trials for Duchenne muscular dystrophy are critical factors for clinical trial success. By choosing optimal biomarkers to better assess therapeutic efficacy, study costs and sample size requirements can be reduced. Currently, functional measures continue to serve as the primary outcome for the majority of DMD clinical trials. Quantitative measures of muscle health, including magnetic resonance imaging and spectroscopy, electrical impedance myography, and ultrasound, sensitively identify diseased muscle, disease progression, and response to a therapeutic intervention. Furthermore, such non-invasive techniques have the potential to identify disease pathology prior to onset of clinical symptoms. Despite robust supportive evidence, non-invasive quantitative techniques are still not frequently utilized in clinical trials for Duchenne muscular dystrophy. Non-invasive quantitative techniques have demonstrated the ability to quantify disease progression and potential response to therapeutic intervention, and should be used as a supplement to current standard functional measures. Such methods have the potential to significantly accelerate the development and approval of therapies for DMD.
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Imageamento por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Distrofia Muscular de Duchenne/diagnóstico , Biomarcadores , Ensaios Clínicos como Assunto , Progressão da Doença , Humanos , Masculino , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiopatologia , Distrofia Muscular de Duchenne/fisiopatologiaRESUMO
This case demonstrates the importance of considering septic pulmonary embolism (SPE) on the differential for chest pain in the pediatric population, especially in patients with a history of skin and soft tissue infection. The adolescent patient in this report, with a history of axillary hidradenitis suppurativa complicated by methicillin-resistant Staphylococcus aureus (MRSA) superinfection and recent completion of a 3-month course of doxycycline, presented with isolated focal chest pain in the absence of other infectious or respiratory signs or symptoms. Initial pulmonary imaging revealed multiple bilateral wedge-shaped nodules. Three specialty teams were consulted in the patient's evaluation, resulting in biopsy of a suspicious lesion that confirmed the diagnosis of MRSA SPE. Following a course of targeted antibiotic therapy, the patient's chest pain resolved and imaging findings improved. Insights gleaned from the workup of this patient are useful in formulating a framework for recognition of SPE in children presenting with chest pain, and also highlight the importance of considering insidious SPE presentation in the setting of antibiotic pretreatment.
RESUMO
Skeletal muscle wasting is a devastating consequence of cancer that contributes to increased complications and poor survival, but is not well understood at the molecular level. Herein, we investigated the role of Myocilin (Myoc), a skeletal muscle hypertrophy-promoting protein that we showed is downregulated in multiple mouse models of cancer cachexia. Loss of Myoc alone was sufficient to induce phenotypes identified in mouse models of cancer cachexia, including muscle fiber atrophy, sarcolemmal fragility, and impaired muscle regeneration. By 18 months of age, mice deficient in Myoc showed significant skeletal muscle remodeling, characterized by increased fat and collagen deposition compared with wild-type mice, thus also supporting Myoc as a regulator of muscle quality. In cancer cachexia models, maintaining skeletal muscle expression of Myoc significantly attenuated muscle loss, while mice lacking Myoc showed enhanced muscle wasting. Furthermore, we identified the myocyte enhancer factor 2 C (MEF2C) transcription factor as a key upstream activator of Myoc whose gain of function significantly deterred cancer-induced muscle wasting and dysfunction in a preclinical model of pancreatic ductal adenocarcinoma (PDAC). Finally, compared with noncancer control patients, MYOC was significantly reduced in skeletal muscle of patients with PDAC defined as cachectic and correlated with MEF2c. These data therefore identify disruptions in MEF2c-dependent transcription of Myoc as a novel mechanism of cancer-associated muscle wasting that is similarly disrupted in muscle of patients with cachectic cancer. SIGNIFICANCE: This work identifies a novel transcriptional mechanism that mediates skeletal muscle wasting in murine models of cancer cachexia that is disrupted in skeletal muscle of patients with cancer exhibiting cachexia.
Assuntos
Caquexia/complicações , Proteínas do Citoesqueleto/metabolismo , Proteínas do Olho/metabolismo , Glicoproteínas/metabolismo , Músculo Esquelético/metabolismo , Doenças Musculares/metabolismo , Síndrome de Emaciação/etiologia , Animais , Composição Corporal , Caquexia/metabolismo , Carcinoma Ductal Pancreático/complicações , Carcinoma Ductal Pancreático/metabolismo , Proteínas do Citoesqueleto/deficiência , Proteínas do Citoesqueleto/genética , Diafragma/fisiologia , Modelos Animais de Doenças , Regulação para Baixo , Proteínas do Olho/genética , Feminino , Glicoproteínas/deficiência , Glicoproteínas/genética , Xenoenxertos , Humanos , Fatores de Transcrição MEF2/metabolismo , Masculino , Camundongos , Músculo Esquelético/patologia , Atrofia Muscular , Doenças Musculares/etiologia , Proteínas de Neoplasias/metabolismo , Neoplasias Pancreáticas/complicações , Neoplasias Pancreáticas/metabolismo , RNA Mensageiro/metabolismo , Regeneração , Corrida , Sarcolema , Síndrome de Emaciação/metabolismo , Síndrome de Emaciação/prevenção & controleRESUMO
Data suggests significantly higher attrition rates of graduate students compared to other health professional programs. Several key differences exist between the training paradigm of Ph.D. programs and other health professional fields, such as the dynamics of group training, differences and frequency of mentor and mentee feedback, and awareness of mental health resources. Many reasons contribute to graduate school attrition, including inadequate mentorship, a paucity of mental health resources, and increasing expenses to attend graduate school. Conversely, failing to adequately train graduate students is a failure to trainees, universities, and the broader public in terms of finances, invested time, and intellectual commitments. Diverse approaches to ensure mentor accountability, supporting emotional health, and increasing financial resources may help raise the graduate rates among graduate students.
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OBJECTIVE: To achieve ultrasound-controlled drug delivery using echogenic liposomes (ELIPs), we assessed ultrasound-triggered release of hydrophilic and lipophilic agents in vitro using color Doppler ultrasound delivered with a clinical 6-MHz compact linear array transducer. METHODS: Calcein, a hydrophilic agent, and papaverine, a lipophilic agent, were each separately loaded into ELIPs. Calcein-loaded ELIP (C-ELIP) and papaverine-loaded ELIP (P-ELIP) solutions were circulated in a flow model and treated with 6-MHz color Doppler ultrasound or Triton X-100. Treatment with Triton X-100 was used to release the encapsulated calcein or papaverine content completely. The free calcein concentration in the solution was measured directly by spectrofluorimetry. The free papaverine in the solution was separated from liposome-bound papaverine by spin column filtration, and the resulting papaverine concentration was measured directly by absorbance spectrophotometry. Dynamic changes in echogenicity were assessed with low-output B-mode ultrasound (mechanical index, 0.04) as mean digital intensity. RESULTS: Color Doppler ultrasound caused calcein release from C-ELIPs compared with flow alone (P < .05) but did not induce papaverine release from P-ELIPs compared with flow alone (P > .05). Triton X-100 completely released liposome-associated calcein and papaverine. Initial echogenicity was higher for C-ELIPs than P-ELIPs. Color Doppler ultrasound and Triton X-100 treatments reduced echogenicity for both C-ELIPs and P-ELIPs (P < .05). CONCLUSIONS: The differential efficiency of ultrasound-mediated pharmaceutical release from ELIPs for water- and lipid-soluble compounds suggests that water-soluble drugs are better candidates for the design and development of ELIP-based ultrasound-controlled drug delivery systems.
Assuntos
Sistemas de Liberação de Medicamentos/métodos , Fluoresceínas/química , Lipossomos/química , Lipossomos/efeitos da radiação , Papaverina/química , Sonicação , Difusão , Fluoresceínas/administração & dosagem , Interações Hidrofóbicas e Hidrofílicas , Papaverina/administração & dosagem , Inibidores de Fosfodiesterase/administração & dosagem , Inibidores de Fosfodiesterase/químicaRESUMO
Streptococcus anginosus is a clinically important pathogen that is emerging globally but remains poorly investigated. Here, we report the first case of acute glomerulonephritis resulting from infection with S. anginosus Glomerulonephritis is typically caused by S. pyogenes and reports secondary to other strains including S. zooepidemicus and S. constellatus exist. Infection with S. anginosus in this patient was associated with acute nephritis (haematuria, oedema and hypertension), nephrotic syndrome and progressive azotemia. There was activation of the complement system. The presence of low C1q and elevated anti-C1q binding complexes points to a potential pathogenic role. Testing for streptococcal antigens was strongly positive. Emerging nephritogenic strains of S. anginosus present a significant health concern for both developed and developing countries.
Assuntos
Dor Abdominal/diagnóstico , Complemento C1q/metabolismo , Complemento C3/metabolismo , Fasciite Necrosante/metabolismo , Glomerulonefrite/microbiologia , Nefropatias/microbiologia , Infecções Estreptocócicas/complicações , Streptococcus anginosus/isolamento & purificação , Dor Abdominal/diagnóstico por imagem , Dor Abdominal/etiologia , Parede Abdominal/patologia , Doença Aguda , Assistência ao Convalescente , Antibacterianos/uso terapêutico , Azotemia/sangue , Fasciite Necrosante/patologia , Fasciite Necrosante/cirurgia , Feminino , Glomerulonefrite/tratamento farmacológico , Glomerulonefrite/patologia , Humanos , Nefropatias/patologia , Pessoa de Meia-Idade , Nefrite/complicações , Nefrite/diagnóstico , Síndrome Nefrótica/complicações , Síndrome Nefrótica/diagnóstico , Proteinúria/diagnóstico , Proteinúria/urina , Infecções Estreptocócicas/tratamento farmacológico , Infecções Estreptocócicas/patologia , Resultado do TratamentoRESUMO
Recently, the first magnetic resonance microscopy (MRM) images at the cellular level in isolated mammalian brain tissues were obtained using microsurface coils. These methods can elucidate the cellular origins of MR signals and describe how these signals change over the course of disease progression and therapy. In this work, we explore the capability of these microimaging techniques to visualize mouse muscle fibers and their nuclei. Isolated myofibers expressing lacZ were imaged with and without a stain for ß-galactosidase activity (S-Gal + ferric ammonium citrate) that produces both optical and MR contrast. We found that MRM can be used to image single myofibers with 6-µm resolution. The ability to image single myofibers will serve as a valuable tool to study MR properties attributed to healthy and myopathic cells. The ability to image nuclei tagged with MR/Optical gene markers may also find wide use in cell lineage MRI studies.
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Imageamento por Ressonância Magnética/métodos , Microscopia/métodos , Fibras Musculares Esqueléticas/citologia , Animais , Genes Reporter , Imageamento Tridimensional , Camundongos Endogâmicos C57BL , Microscopia de Interferência , Fibras Musculares Esqueléticas/metabolismoRESUMO
BACKGROUND: Duchenne muscular dystrophy (DMD) causes progressive pathologic changes to muscle secondary to a cascade of inflammation, lipid deposition, and fibrosis. Clinically, this manifests as progressive weakness, functional loss, and premature mortality. Though insult to whole muscle groups is well established, less is known about the relationship between intramuscular pathology and function. OBJECTIVE: Differences of intramuscular heterogeneity across muscle length were assessed using an ordinal MRI grading scale in lower leg muscles of boys with DMD and correlated to patient's functional status. METHODS: Cross sectional T1 weighted MRI images with fat suppression were obtained from ambulatory boys with DMD. Six muscles (tibialis anterior, extensor digitorum longus, peroneus, soleus, medial and lateral gastrocnemii) were graded using an ordinal grading scale over 5 slice sections along the lower leg length. The scores from each slice were combined and results were compared to global motor function and age. RESULTS: Statistically greater differences of involvement were observed at the proximal ends of muscle compared to the midbellies. Multi-slice assessment correlated significantly to age and the Vignos functional scale, whereas single-slice assessment correlated to the Vignos functional scale only. Lastly, differential disease involvement of whole muscle groups and intramuscular heterogeneity were observed amongst similar age subjects. CONCLUSION: A multi-slice ordinal MRI grading scale revealed that muscles are not uniformly affected, with more advanced disease visible near the tendons in a primarily ambulatory population with DMD. A geographically comprehensive evaluation of the heterogeneously affected muscle in boys with DMD may more accurately assess disease involvement.
Assuntos
Imageamento por Ressonância Magnética/métodos , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiopatologia , Distrofia Muscular de Duchenne/diagnóstico por imagem , Distrofia Muscular de Duchenne/fisiopatologia , Subida de Escada , Tecido Adiposo/diagnóstico por imagem , Fatores Etários , Estudos de Casos e Controles , Criança , Fibrose , Humanos , Perna (Membro) , Masculino , Tendões/diagnóstico por imagemRESUMO
AIMS: Under pressure overload, initial adaptive hypertrophy of the heart is followed by cardiomyocyte elongation, reduced contractile force, and failure. The mechanisms governing the transition to failure are not fully understood. Pressure overload reduced cardiac myosin light chain kinase (cMLCK) by â¼80% within 1 week and persists. Knockdown of cMLCK in cardiomyocytes resulted in reduced cardiac contractility and sarcomere disorganization. Thus, we hypothesized that acute reduction of cMLCK may be causative for reduced contractility and cardiomyocyte remodelling during the transition from compensated to decompensated cardiac hypertrophy. METHODS AND RESULTS: To mimic acute cMLCK reduction in adult hearts, the floxed-Mylk3 gene that encodes cMLCK was inducibly ablated in Mylk3(flox/flox)/merCremer mice (Mylk3-KO), and compared with two control mice (Mylk3(flox/flox) and Mylk3(+/+)/merCremer) following tamoxifen injection (50 mg/kg/day, 2 consecutive days). In Mylk3-KO mice, reduction of cMLCK protein was evident by 4 days, with a decline to below the level of detection by 6 days. By 7 days, these mice exhibited heart failure, with reduction of fractional shortening compared with those in two control groups (19.8 vs. 28.0% and 27.7%). Severely convoluted cardiomyocytes with sarcomeric disorganization, wavy fibres, and cell death were demonstrated in Mylk3-KO mice. The cardiomyocytes were also unable to thicken adaptively to pressure overload. CONCLUSION: Our results, using a new mouse model mimicking an acute reduction of cMLCK, suggest that cMLCK plays a pivotal role in the transition from compensated to decompensated hypertrophy via sarcomeric disorganization.
Assuntos
Cardiomegalia/enzimologia , Insuficiência Cardíaca/enzimologia , Miócitos Cardíacos/enzimologia , Quinase de Cadeia Leve de Miosina/deficiência , Função Ventricular Esquerda , Remodelação Ventricular , Doença Aguda , Adaptação Fisiológica , Animais , Atrofia , Sinalização do Cálcio , Miosinas Cardíacas/metabolismo , Cardiomegalia/genética , Cardiomegalia/patologia , Cardiomegalia/fisiopatologia , Modelos Animais de Doenças , Progressão da Doença , Predisposição Genética para Doença , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Contração Miocárdica , Miócitos Cardíacos/patologia , Cadeias Leves de Miosina/metabolismo , Quinase de Cadeia Leve de Miosina/genética , Fenótipo , Fosforilação , Sarcômeros/enzimologia , Sarcômeros/patologia , Fatores de TempoRESUMO
Caloric restriction has consistently been shown to extend life span and ameliorate aging-related diseases. These effects may be due to diet-induced reactive oxygen species acting to up-regulate sirtuins and related protective pathways, which research suggests may be partially inhibited by dietary anti-oxidant supplementation. Because caloric restriction is not sustainable long term for most humans, we investigated an alternative dietary approach, intermittent fasting (IF), which is proposed to act on similar biological pathways. We hypothesized that a modified IF diet, where participants maintain overall energy balance by alternating between days of fasting (25% of normal caloric intake) and feasting (175% of normal), would increase expression of genes associated with aging and reduce oxidative stress and that these effects would be suppressed by anti-oxidant supplementation. To assess the tolerability of the diet and to explore effects on biological mechanisms related to aging and metabolism, we recruited a cohort of 24 healthy individuals in a double-crossover, double-blinded, randomized clinical trial. Study participants underwent two 3-week treatment periods-IF and IF with anti-oxidant (vitamins C and E) supplementation. We found strict adherence to study-provided diets and that participants found the diet tolerable, with no adverse clinical findings or weight change. We detected a marginal increase (2.7%) in SIRT3 expression due to the IF diet, but no change in expression of other genes or oxidative stress markers analyzed. We also found that IF decreased plasma insulin levels (1.01 µU/mL). Although our study suggests that the IF dieting paradigm is acceptable in healthy individuals, additional research is needed to further assess the potential benefits and risks.