RESUMEN

Limb girdle muscular dystrophy type 2D (LGMD2D) is characterized by progressive weakening of muscles in the hip and shoulder girdles. It is caused by a mutation in the α-sarcoglycan gene and results in absence of α-sarcoglycan in the dystrophin-glycoprotein complex. The activin type IIB receptor is involved in the activin/myostatin pathway, with myostatin being a negative regulator of muscle growth. In this study, we investigated the effects of sequestering myostatin by a soluble activin type IIB receptor (sActRIIB) on muscle growth in Sgca-null mice, modelling LGMD2D. Treatment was initiated at 3 weeks of age, prior to the disease onset, or at 9 weeks of age when already in an advanced stage of the disease. We found that early sActRIIB treatment resulted in increased muscle size. However, this led to more rapid decline of muscle function than in saline-treated Sgca-null mice. Furthermore, no histopathological improvements were seen after sActRIIB treatment. When initiated at 9 weeks of age, sActRIIB treatment resulted in increased muscle mass too, but to a lesser extent. No effect of the treatment was observed on muscle function or histopathology. These data show that sActRIIB treatment as a stand-alone therapy does not improve muscle function or histopathology in Sgca-null mice.

Asunto(s)

Miostatina , Sarcoglicanopatías , Receptores de Activinas/metabolismo , Activinas/metabolismo , Animales , Modelos Animales de Enfermedad , Ratones , Músculo Esquelético/patología , Miostatina/genética , Sarcoglicanopatías/metabolismo , Sarcoglicanos/genética , Sarcoglicanos/metabolismo

RESUMEN

Duchenne muscular dystrophy is an X-linked, recessive muscular dystrophy in which the absence of the dystrophin protein leads to fibrosis, inflammation and oxidative stress, resulting in loss of muscle tissue. Drug repurposing, i.e. using drugs already approved for other disorders, is attractive as it decreases development time. Recent studies suggested that simvastatin, a cholesterol lowering drug used for cardiovascular diseases, has beneficial effects on several parameters in mdx mice. To validate properly the effectiveness of simvastatin, two independent labs tested the effects of 12-week simvastatin treatment in either young (starting at 4 weeks of age) or adult (starting at 12 weeks of age) mdx mice. In neither study were benefits of simvastatin treatment observed on muscle function, histology or expression of genes involved in fibrosis, regeneration, oxidative stress and autophagy. Unexpectedly, although the treatment protocol was similar, simvastatin plasma levels were found to be much lower than observed in a previous study. In conclusion, in two laboratories, simvastatin did not ameliorate disease pathology in mdx mice, which could either be due to the ineffectiveness of simvastatin itself or due to the low simvastatin plasma levels following oral administration via the food.

Asunto(s)

Distrofia Muscular Animal/fisiopatología , Distrofia Muscular de Duchenne/fisiopatología , Simvastatina/farmacología , Animales , Modelos Animales de Enfermedad , Fibrosis/fisiopatología , Ratones , Ratones Endogámicos mdx , Músculo Esquelético/efectos de los fármacos

RESUMEN

Duchenne muscular dystrophy (DMD) results, beside muscle degeneration in cognitive defects. As neuronal function is supported by astrocytes, which express dystrophin, we hypothesized that loss of dystrophin from DMD astrocytes might contribute to these cognitive defects. We generated cortical neuronal and astrocytic progeny from induced pluripotent stem cells (PSC) from six DMD subjects carrying different mutations and several unaffected PSC lines. DMD astrocytes displayed cytoskeletal abnormalities, defects in Ca+2 homeostasis and nitric oxide signaling. In addition, defects in glutamate clearance were identified in DMD PSC-derived astrocytes; these deficits were related to a decreased neurite outgrowth and hyperexcitability of neurons derived from healthy PSC. Read-through molecule restored dystrophin expression in DMD PSC-derived astrocytes harboring a premature stop codon mutation, corrected the defective astrocyte glutamate clearance and prevented associated neurotoxicity. We propose a role for dystrophin deficiency in defective astroglial glutamate homeostasis which initiates defects in neuronal development.

Asunto(s)

Astrocitos/metabolismo , Distrofina/metabolismo , Ácido Glutámico/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Neuronas/metabolismo , Astrocitos/citología , Calcio/metabolismo , Citoesqueleto/metabolismo , Distrofina/genética , Humanos , Células Madre Pluripotentes Inducidas/citología , Masculino , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/metabolismo , Proyección Neuronal/fisiología , Neuronas/citología , Óxido Nítrico/metabolismo

RESUMEN

Limb girdle muscular dystrophy (LGMD) types 2D and 2F are caused by mutations in the genes encoding for α- and δ-sarcoglycan, respectively, leading to progressive muscle weakness. Mouse models exist for LGMD2D (Sgca-/-) and 2F (Sgcd-/-). In a previous natural history study, we described the pathology in these mice at 34 weeks of age. However, the development of muscle pathology at younger ages has not been fully characterised yet. We therefore performed a study into age-related changes in muscle function and pathology by examining mice at different ages. From 4 weeks of age onwards, male mice were subjected to functional tests and sacrificed at respectively 8, 16 or 24 weeks of age. Muscle histopathology and expression of genes involved in muscle pathology were analysed for several skeletal muscles, while miRNA levels were assessed in serum. In addition, for Sgcd-/- mice heart pathology was assessed. Muscle function showed a gradual decline in both Sgca-/- and Sgcd-/- mice. Respiratory function was also impaired at all examined timepoints. Already at 8 weeks of age, muscle pathology was prominent, and fibrotic, inflammatory and regenerative markers were elevated, which remained relatively constant with age. In addition, Sgcd-/- mice showed signs of cardiomyopathy from 16 weeks of age onwards. These results indicate that Sgca-/- and Sgcd-/- are relevant disease models for LGMD2D and 2F.

Asunto(s)

Músculo Esquelético/patología , Sarcoglicanopatías/patología , Envejecimiento , Animales , Modelos Animales de Enfermedad , Eliminación de Gen , Regulación de la Expresión Génica , Masculino , Ratones , Ratones Endogámicos C57BL , MicroARNs/genética , Músculo Esquelético/metabolismo , Sarcoglicanopatías/genética , Sarcoglicanos/genética

RESUMEN

Hypertension is a major health concern throughout the United States and is a major cause of cardiovascular disease. The purpose of this study was to compare the responses of Tai Chi and walking on measures of central and peripheral cardiac mechanisms when controlling for exercise intensity. Fifteen hypertensive subjects (2 males, 13 females; age = 20.7 ± 3.77 years; body fat = 24.26 ± 10.27%) participated in Tai Chi (TC) and walking (WK) for 30 minutes on non-consecutive days. Central systolic (CSBP) and diastolic blood pressure (CDBP), augmentation index (Alx), pulse pressure (PP), heart rate (HR), and brachial systolic (BSBP) and diastolic blood pressure (BDBP) were measured prior to exercise and following exercise every 10 minutes for a total of 60 minutes in a seated position. There were no significant differences between the two exercise forms. CSBP decreased 10 minutes after exercise in both exercise types (TC = 6.63 ± 3.258 mmHG; WK = 7 ± 4.144 mmHG p < 0.05), and 40 minutes after exercise in both exercise types (TC = 6.07 ± 3.33 mmHG; WK = 8.2 ± 3.15 mmHG, p < 0.05) compared to the initial measurement. BSBP also decreased in both exercise forms following 10 min of rest (TC = 6.99 ± 3.776 mmHG; WK = 8.8 ± 3.20 mmHG p = 0.05), and 40 min (TC = 8.46 ± 3.07 mmHG; WK = 8.87 ± 3.87 mmHG, p < 0.05) when compared to the initial resting measurement. Central aortic pressure exhibits a post exercise hypotensive (PEH) effect similar to that of peripheral blood pressure. Both Tai Chi and walking elicited similar PEH effects on systolic blood pressure in hypertensive individuals.

RESUMEN

Duchenne muscular dystrophy is a severe, progressive muscle-wasting disease that is caused by mutations that abolish the production of functional dystrophin protein. The exon skipping approach aims to restore the disrupted dystrophin reading frame, to allow the production of partially functional dystrophins, such as found in the less severe Becker muscular dystrophy. Exon skipping is achieved by antisense oligonucleotides (AONs). Several chemical modifications have been tested in nonclinical and clinical trials. The morpholino phosphorodiamidate oligomer eteplirsen has been approved by the Food and Drug Administration, whereas clinical development with the 2'-O-methyl phosphorothioate (2OMePS) AON drisapersen was recently stopped. In this study, we aimed to study various aspects of 2OMePS AONs in nonclinical animal studies. We show that while efficiency of exon skipping restoration is comparable in young and older C57BL/10ScSn-Dmdmdx/J (mdx/BL10) mice, functional improvement was only observed for younger treated mice. Muscle quality did not affect exon skipping efficiency as exon skip and dystrophin levels were similar between mdx/BL10 and more severely affected, age-matched D2-mdx mice. We further report that treadmill running increases AON uptake and dystrophin levels in mdx/BL10 mice. Finally, we show that even low levels of exon skipping and dystrophin restoration are sufficient to significantly increase the survival of mdx-utrn-/- mice from 70 to 97 days.

Asunto(s)

Distrofina/genética , Distrofia Muscular de Duchenne/genética , Oligonucleótidos Antisentido/farmacología , Utrofina/genética , Animales , Ensayos Clínicos como Asunto , Distrofina/antagonistas & inhibidores , Exones/efectos de los fármacos , Exones/genética , Terapia Genética , Humanos , Ratones , Ratones Endogámicos mdx , Morfolinos/genética , Morfolinos/farmacología , Atrofia Muscular Espinal , Distrofia Muscular de Duchenne/terapia , Oligonucleótidos/farmacología , Oligonucleótidos Antisentido/genética , Compuestos Organotiofosforados/farmacología

RESUMEN

Duchenne muscular dystrophy is a severe muscle wasting disease, characterized by a severely reduced lifespan in which cardiomyopathy is one of the leading causes of death. Multiple therapies aiming at dystrophin restoration have been approved. It is anticipated that these therapies will maintain muscle function for longer and extend the ambulatory period, which in turn will increase the cardiac workload which could be detrimental for cardiac function. We investigated the effects of voluntary running exercise in combination with low dystrophin levels on function and pathology of skeletal muscle and heart. We divided 15.5-month old female mdx (no dystrophin), mdx-XistΔhs (varying low dystrophin levels) and wild type mice (BL10-WT and XistΔhs-WT) to either a sedentary or voluntary wheel running regime and assessed muscle function at 17.5 months of age. Thereafter, a cardiac MRI was obtained, and muscle and heart histopathology were assessed. We show that voluntary exercise is beneficial to skeletal muscle and heart function in dystrophic mice while not affecting muscle pathology. Low amounts of dystrophin further improve skeletal muscle and cardiac function. These findings suggest that voluntary exercise may be beneficial for skeletal muscle and heart in DMD patients, especially in conjunction with low amounts of dystrophin.

Asunto(s)

Corazón/fisiología , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiología , Distrofia Muscular Animal/fisiopatología , Distrofia Muscular de Duchenne/fisiopatología , Miocardio/metabolismo , Condicionamiento Físico Animal/fisiología , Animales , Western Blotting , Femenino , Masculino , Actividad Motora/fisiología , Distrofia Muscular Animal/metabolismo , Distrofia Muscular de Duchenne/metabolismo

RESUMEN

PURPOSE: Cardiac rehabilitation (CR) attendance has been associated with higher smoking cessation (SC) rates. However, for unclear reasons, smokers are consistently less likely to enroll in CR than nonsmokers, and it is uncertain what might encourage them to attend. METHODS: We surveyed patients eligible for CR who were cigarette smokers at the time of hospital admission. We assessed patient intention to quit smoking, start exercising, and enroll in CR. We also measured anxiety and depression levels. RESULTS: Of the 105 patients approached, 81 (77%) completed the survey (69% males, aged 57 ± 10 y, 72% white). Most patients reported interest in SC (80%) and attending CR (78%). Many felt that SC medications (41%), stress management programs (35%), and an exercise program with SC counseling (30%) would increase their likelihood to attend CR; however, 30% stated that they would be less likely to enroll in CR if they continued smoking following discharge. Many patients indicated high levels of anxiety (51%) and depression (27%); many desired to reduce stress following discharge (73%), with 35% stating that stress management programs would increase their likelihood to attend CR. CONCLUSIONS: Hospitalized smokers eligible for CR report significant interest in SC, attending CR, and beginning an exercise program. These patients show high levels of anxiety and depression and indicate a strong interest in stress management programs. These results suggest that messages emphasizing the role of CR in the treatment of depression, anxiety, and stress are likely to resonate with smokers, increase their enrollment in CR, and support long-term SC.

Asunto(s)

Rehabilitación Cardiaca , Ejercicio Físico , Cardiopatías/psicología , Cardiopatías/rehabilitación , Aceptación de la Atención de Salud/psicología , Fumar/psicología , Enfermedad Aguda , Anciano , Ansiedad/psicología , Consejo , Depresión/psicología , Femenino , Humanos , Pacientes Internos/psicología , Intención , Masculino , Persona de Mediana Edad , Cese del Hábito de Fumar , Estrés Psicológico/prevención & control

RESUMEN

Duchenne muscular dystrophy (DMD) is a severe, progressive muscle wasting disorder caused by reading frame disrupting mutations in the DMD gene. Exon skipping is a therapeutic approach for DMD. It employs antisense oligonucleotides (AONs) to restore the disrupted open reading frame, allowing the production of shorter, but partly functional dystrophin protein as seen in less severely affected Becker muscular dystrophy patients. To be effective, AONs need to be delivered and effectively taken up by the target cells, which can be accomplished by the conjugation of tissue-homing peptides. We performed phage display screens using a cyclic peptide library combined with next generation sequencing analyses to identify candidate muscle-homing peptides. Conjugation of the lead peptide to 2'-O-methyl phosphorothioate AONs enabled a significant, 2-fold increase in delivery and exon skipping in all analyzed skeletal and cardiac muscle of mdx mice and appeared well tolerated. While selected as a muscle-homing peptide, uptake was increased in liver and kidney as well. The homing capacity of the peptide may have been overruled by the natural biodistribution of the AON. Nonetheless, our results suggest that the identified peptide has the potential to facilitate delivery of AONs and perhaps other compounds to skeletal and cardiac muscle.

Asunto(s)

Empalme Alternativo , Técnicas de Transferencia de Gen , Terapia Genética , Distrofia Muscular de Duchenne/genética , Oligonucleótidos Antisentido/genética , Péptidos Cíclicos , Secuencia de Aminoácidos , Animales , Modelos Animales de Enfermedad , Distrofina/genética , Exones , Humanos , Ratones , Ratones Endogámicos mdx , Distrofia Muscular de Duchenne/terapia , Oligonucleótidos Antisentido/administración & dosificación , Oligonucleótidos Antisentido/química , Biblioteca de Péptidos , Péptidos Cíclicos/química

RESUMEN

This study was designed to assess the effectiveness of mental imagery supplemented with video-modeling on self-efficacy and front squat strength (three repetition maximum; 3RM). Subjects (13 male, 7 female) who had at least 6 months of front squat experience were assigned to either an experimental (n = 10) or a control (n = 10) group. Subjects' 3RM and self-efficacy for the 3RM were measured at baseline. Following this, subjects in the experimental group followed a structured imagery protocol, incorporating video recordings of both their own 3RM performance and a model lifter with excellent technique, twice a day for three days. Subjects in the control group spent the same amount of time viewing a placebo video. Following three days with no physical training, measurements of front squat 3RM and self-efficacy for the 3RM were repeated. Subjects in the experimental group increased in self-efficacy following the intervention, and showed greater 3RM improvement than those in the control group. Self-efficacy was found to significantly mediate the relationship between imagery and front squat 3RM. These findings point to the importance of mental skills training for the enhancement of self-efficacy and front squat performance.

RESUMEN

Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder typically caused by frame-shifting mutations in the DMD gene. Restoration of the reading frame would allow the production of a shorter but partly functional dystrophin protein as seen in Becker muscular dystrophy patients. This can be achieved with antisense oligonucleotides (AONs) that induce skipping of specific exons during pre-mRNA splicing. Different chemical modifications have been developed to improve AON properties. The 2'-deoxy-2'-fluoro (2F) RNA modification is attractive for exon skipping due to its ability to recruit ILF2/3 proteins to the 2F/pre-mRNA duplex, which resulted in enhanced exon skipping in spinal muscular atrophy models. In this study, we examined the effect of two different 2'-substituted AONs (2'-F phosphorothioate (2FPS) and 2'-O-Me phosphorothioate (2OMePS)) on exon skipping in DMD cell and animal models. In human cell cultures, 2FPS AONs showed higher exon skipping levels than their isosequential 2OMePS counterparts. Interestingly, in the mdx mouse model, 2FPS was less efficient than 2OMePS and suggested safety issues as evidenced by increased spleen size and weight loss. Our results do not support a clinical application for 2FPS AON.

RESUMEN

The purpose of the study was to examine the bilateral and unilateral force production difference in powerlifters (bilateral) and field jumpers (unilateral) to determine the existence of leg dominance. Nineteen powerlifters (PL; n = 11) and field jumpers (J; n = 8) were included in the study. Five different no arm swing countermovement jumps were randomized for testing: (a) double-leg jump; (b) dominant leg-specified double-leg jump; (c) nondominant leg-specified double-leg jump; (d) dominant leg-specified single-leg jump; and (e) nondominant leg-specified single-leg jump. The force, velocity, and power were measured via a forceplate. The Limb Symmetry Index (LSI% = (1 - ND limb/D limb) × 100%) was calculated for force imbalance between the dominant (N) and nondominant (ND) limb between PL and J. Based on the analysis, PL (mean = 2.75 ± 2.45%) had a lower LSI (p < 0.05) than J (mean = 6.81 ± 5.16%). The single-leg jumps show a (p < 0.05) significantly higher force and power and a significantly lower velocity than double-leg jump for both D and ND leg than double-leg jump. Finally, the ratio between bilateral and unilateral exercise for PL and J is 2.36:1.36 and 2.38:1, respectively. In summary, sport-specific demands between PL and J may contribute to the occurrence of the imbalance force production between limbs. This phenomenon is important for the strength coach to acknowledge, to perform an appropriate strength balance test during the off-season, and to implement a training program to reduce the force disparity between limbs. Neglecting the development of force imbalance between limbs may predispose healthy players to injury.

Asunto(s)

Lateralidad Funcional , Movimiento/fisiología , Fuerza Muscular/fisiología , Atletismo/fisiología , Levantamiento de Peso/fisiología , Adolescente , Adulto , Prueba de Esfuerzo , Humanos , Pierna/fisiología , Masculino , Músculo Esquelético/fisiología , Distribución Aleatoria , Adulto Joven

RESUMEN

Antisense oligonucleotide (AON)-mediated exon skipping is a promising therapeutic approach for Duchenne muscular dystrophy that is currently being tested in various clinical trials. This approach is based on restoring the open reading frame of dystrophin transcripts resulting in shorter but partially functional dystrophin proteins as found in patients with Becker muscular dystrophy. After systemic administration, a large proportion of AONs ends up in the liver and kidneys. Therefore, enhancing AON uptake by skeletal and cardiac muscle would improve the AONs' therapeutic effect. For phosphorodiamidate morpholino oligomer, AONs use nonspecific positively charged cell penetrating peptides to enhance efficacy. However, this is challenging for negatively charged 2'-O-methyl phosphorothioate oligomer. Therefore, we screened a 7-mer phage display peptide library to identify muscle and heart homing peptides in vivo in the mdx mouse model and found a promising candidate peptide capable of binding muscle cells in vitro and in vivo. Upon systemic administration in dystrophic mdx mice, conjugation of a 2'-O-methyl phosphorothioate AON to this peptide indeed improved uptake in skeletal and cardiac muscle, and resulted in higher exon skipping levels with a significant difference in heart and diaphragm. Based on these results, peptide conjugation represents an interesting strategy to enhance the therapeutic effect of exon skipping with 2'-O-methyl phosphorothioate AONs for Duchenne muscular dystrophy.

Asunto(s)

Oligonucleótidos Antisentido/química , Oligonucleótidos Antisentido/uso terapéutico , Oligonucleótidos Fosforotioatos/química , Oligonucleótidos Fosforotioatos/uso terapéutico , Animales , Distrofina/genética , Exones , Humanos , Masculino , Ratones , Ratones Endogámicos mdx , Músculo Esquelético/metabolismo , Distrofia Muscular Animal/genética , Distrofia Muscular Animal/metabolismo , Distrofia Muscular Animal/terapia , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/terapia , Mutación , Miocardio/metabolismo , Oligonucleótidos Antisentido/genética , Biblioteca de Péptidos , Ácidos Nucleicos de Péptidos/química , Ácidos Nucleicos de Péptidos/genética , Ácidos Nucleicos de Péptidos/uso terapéutico , Oligonucleótidos Fosforotioatos/genética , Reparación del Gen Blanco/métodos

RESUMEN

Antisense-mediated exon skipping is a promising therapeutic approach for Duchenne muscular dystrophy. It aims to restore the dystrophin open reading frame by skipping exons with antisense oligonucleotides (AONs) to allow production of partly functional proteins. The approach is currently tested in phase 3 clinical trials, but dosing and maintenance regimens have not yet been well studied. This study compared pharmacokinetic and pharmacodynamic effects of different 2'-O-methyl phosphorothioate RNA AON dosing and maintenance regimens in the preclinical mdx mouse model. When comparing different dosing regimens over a period of 8 weeks, higher levels of AON, exon skipping, and protein were observed in muscle after low daily doses compared with large weekly doses. Secondly, after receiving a high loading dose (1,250 mg/kg) in the first week, mice treated with maintenance injections twice weekly for 8 weeks showed higher preservation of therapeutic effects than mice receiving less or no maintenance injections. In both cases, the regimen resulting in the highest AON and exon skipping levels in muscle also resulted in high AON levels in liver and kidneys. These studies underline the importance of balancing optimal AON efficacy and tolerable levels in non-target organs, which may be fine-tuned by further optimization of AON treatment regimens.

Asunto(s)

Distrofina/genética , Músculo Esquelético/efectos de los fármacos , Distrofia Muscular de Duchenne/terapia , Oligonucleótidos Antisentido/farmacología , Oligonucleótidos Fosforotioatos/farmacología , Animales , Creatina Quinasa/sangre , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Vías de Administración de Medicamentos , Esquema de Medicación , Cálculo de Dosificación de Drogas , Distrofina/agonistas , Distrofina/metabolismo , Exones , Terapia Genética , Humanos , Riñón/efectos de los fármacos , Hígado/efectos de los fármacos , Ratones , Ratones Endogámicos mdx , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/patología , Oligonucleótidos Antisentido/síntesis química , Oligonucleótidos Antisentido/farmacocinética , Oligonucleótidos Fosforotioatos/síntesis química , Oligonucleótidos Fosforotioatos/farmacocinética

RESUMEN

Antisense-mediated exon skipping for Duchenne muscular dystrophy (DMD) is currently tested in phase 3 clinical trials. The aim of this approach is to modulate splicing by skipping a specific exon to reframe disrupted dystrophin transcripts, allowing the synthesis of a partly functional dystrophin protein. Studies in animal models allow detailed analysis of the pharmacokinetic and pharmacodynamic profile of antisense oligonucleotides (AONs). Here, we tested the safety and efficacy of subcutaneously administered 2'-O-methyl phosphorothioate AON at 200 mg/kg/week for up to 6 months in mouse models with varying levels of disease severity: mdx mice (mild phenotype) and mdx mice with one utrophin allele (mdx/utrn(+/-); more severe phenotype). Long-term treatment was well tolerated and exon skipping and dystrophin restoration confirmed for all animals. Notably, in the more severely affected mdx/utrn(+/-) mice the therapeutic effect was larger: creatine kinase (CK) levels were more decreased and rotarod running time was more increased. This suggests that the mdx/utrn(+/-) model may be a more suitable model to test potential therapies than the regular mdx mouse. Our results also indicate that long-term subcutaneous treatment in dystrophic mouse models with these AONs is safe and beneficial.Molecular Therapy-Nucleic Acids (2012) 1, e44; doi:10.1038/mtna.2012.38; published online 4 September 2012.

RESUMEN

UNLABELLED: Ankle stabilizers can reduce ankle sprain incidence and severity by limiting range of motion. Still whether using them affects performance remains unclear. The authors compared effects of 3 ankle stabilizers, tape, lace-up (Swede-O Ankle Lok), and semirigid (Air-Cast Air-Stirrup) braces, and a nonsupport control on vertical jump (Sargent Jump Test), agility (Right-Boomerang Run test), and dynamic balance (Modified Bass Test) in 10 volunteers (4 males, 6 females; 25.6 ± 2.8 years, 167.8 ± 13.7 cm, 61.4 ± 10.7 kg) using repeated-measures ANOVAs. Participants had similar vertical jump (P = .27; control = 41.40 ± 11.89 cm, tape = 37.90 ± 7.92 cm, Swede-O = 41.40 ± 11.89 cm, Air-Cast = 39.29 ± 10.85 cm) and dynamic balance (P = .08; control = 92.50 ± 2.46, tape = 91.55 ± 3.53, Swede-O = 97.00 ± 5.32, Air-Cast = 89.40 ± 6.08) but differing agility scores (P = .03; control = 13.55 ± 1.35 seconds, tape = 14.03 ± 1.5 seconds, Swede-O = 14.10 ± 1.36 seconds, Air-Cast = 14.14 ± 1.41 seconds). Post hoc tests revealed a significant difference (P = .03) between control and Air-Cast but not between Swede-O (P = .06) or tape (P = .07). Effect size (d) analyses indicated that compared with control, all stabilizers trended to increase agility run times (tape, d = 0.33; Swede-O, d = 0.40; Air-Cast, d = 0.43). Since participants primarily required sagittal plane motion when jumping vertically and had relatively slow directional changes in the dynamic balance test, wearing ankle stabilizers did not hamper jump or balance. However, ankle stabilizers hindered participants' ability to perform quick directional changes required in the agility test, with the most rigid stabilizer (Air-Cast) affecting agility the most. Clinicians should be aware that ankle stabilizers may affect some performance measures (agility) but not others (jumping, balance) and continue examinations in larger cohorts. LEVEL OF EVIDENCE: Therapeutic, Level II.

Asunto(s)

Articulación del Tobillo/fisiología , Cinta Atlética , Tirantes , Movimiento/fisiología , Equilibrio Postural/fisiología , Adulto , Análisis de Varianza , Traumatismos del Tobillo/prevención & control , Diseño de Equipo , Femenino , Humanos , Masculino , Carrera/fisiología , Esguinces y Distensiones/prevención & control

RESUMEN

Antisense oligonucleotides (AONs) are being developed as RNA therapeutic molecules for Duchenne muscular dystrophy. For oligonucleotides with the 2'-O-methyl-phosphorothioate (2OMePS) RNA chemistry, proof of concept has been obtained in patient-specific muscle cell cultures, the mouse and dog disease models, and recently by local administration in Duchenne patients. To further explore the pharmacokinetic (PK)/pharmacodynamic (PD) properties of this chemical class of oligonucleotides, we performed a series of preclinical studies in mice. The results demonstrate that the levels of oligonucleotides in dystrophin-deficient muscle fibers are much higher than in healthy fibers, leading to higher exon-skipping levels. Oligonucleotide levels and half-life differed for specific muscle groups, with heart muscle showing the lowest levels but longest half-life (approximately 46 days). Intravenous (i.v.), subcutaneous (s.c.), and intraperitoneal (i.p.) delivery methods were directly compared. For each method, exon-skipping and novel dystrophin expression were observed in all muscles, including arrector pili smooth muscle in skin biopsies. After i.v. administration, the oligonucleotide peak levels in plasma, liver, and kidney were higher than after s.c. or i.p. injections. However, as the bioavailability was similar, and the levels of oligonucleotide, exon-skipping, and dystrophin steadily accumulated overtime after s.c. administration, we selected this patient-convenient delivery method for future clinical study protocols.

Asunto(s)

Oligonucleótidos Fosforotioatos/farmacología , ARN sin Sentido/farmacología , Animales , Western Blotting , Modelos Animales de Enfermedad , Distrofina/administración & dosificación , Técnica del Anticuerpo Fluorescente , Ratones , Ratones Endogámicos mdx , Oligonucleótidos Fosforotioatos/farmacocinética , ARN sin Sentido/farmacocinética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa

RESUMEN

To assess the effect of potential therapeutic agents in dystrophic mice it is useful to have a functional test regime that does not affect the natural disease progression of mdx mice with dystrophinopathy. We determined the effect of a 12 week test regime consisting of fore limb grip strength, rotarod analysis and two and four limb hanging wire tests on the disease progression of 4-week-old mdx mice. Mice performed the different functional tests on consecutive days on a weekly basis. No difference was found in serum creatine kinase levels between functionally active and sedentary mice. The percentage of fibrotic/necrotic areas assessed in a semi-automated way with colour deconvolution of skeletal muscles, heart and diaphragm did not vary within muscles or between groups, nor did the gene expression levels of disease-related genes. We conclude that this test regime may be suitable for short-term functional evaluation of therapeutic approaches in the mdx mouse.

Asunto(s)

Evaluación de la Discapacidad , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/fisiopatología , Evaluación de Resultado en la Atención de Salud/métodos , Índice de Severidad de la Enfermedad , Factores de Edad , Animales , Creatina Quinasa/análisis , Creatina Quinasa/sangre , Modelos Animales de Enfermedad , Fibrosis/tratamiento farmacológico , Fibrosis/metabolismo , Fibrosis/fisiopatología , Regulación de la Expresión Génica/genética , Corazón/efectos de los fármacos , Corazón/fisiopatología , Procesamiento de Imagen Asistido por Computador , Masculino , Ratones , Ratones Endogámicos mdx , Actividad Motora/efectos de los fármacos , Actividad Motora/genética , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patología , Proteínas Musculares/genética , Fuerza Muscular/efectos de los fármacos , Fuerza Muscular/genética , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiopatología , Distrofia Muscular de Duchenne/tratamiento farmacológico , Miocardio/metabolismo , Examen Neurológico/métodos , Valor Predictivo de las Pruebas , Recuperación de la Función/efectos de los fármacos , Recuperación de la Función/genética , Factores de Tiempo

RESUMEN

Duchenne muscular dystrophy (DMD) is caused by the lack of functional dystrophin protein, most commonly as a result of a range of out-of-frame mutations in the DMD gene. Modulation of pre-mRNA splicing with antisense oligonucleotides (AOs) to restore the reading frame has been demonstrated in vitro and in vivo, such that truncated but functional dystrophin is expressed. AO-induced skipping of exon 51 of the DMD gene, which could treat 13% of DMD patients, has now progressed to clinical trials. We describe here the methodical, cooperative comparison, in vitro (in DMD cells) and in vivo (in a transgenic mouse expressing human dystrophin), of 24 AOs of the phosphorodiamidate morpholino oligomer (PMO) chemistry designed to target exon 53 of the DMD gene, skipping of which could be potentially applicable to 8% of patients. A number of the PMOs tested should be considered worthy of development for clinical trial.

Asunto(s)

Distrofina/efectos de los fármacos , Exones/efectos de los fármacos , Marcación de Gen/métodos , Terapia Genética/métodos , Distrofia Muscular de Duchenne/tratamiento farmacológico , Oligonucleótidos Antisentido/farmacología , Animales , Secuencia de Bases/efectos de los fármacos , Secuencia de Bases/genética , Células Cultivadas , Modelos Animales de Enfermedad , Distrofina/química , Distrofina/genética , Exones/genética , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Humanos , Masculino , Ratones , Ratones Transgénicos , Morfolinas/química , Morfolinas/farmacología , Morfolinas/uso terapéutico , Morfolinos , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/metabolismo , Mutación/genética , Oligonucleótidos Antisentido/química , Oligonucleótidos Antisentido/uso terapéutico , Transcripción Genética/efectos de los fármacos , Transcripción Genética/genética

RESUMEN

Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disease caused by frame shifting and nonsense mutations in the dystrophin gene. Through skipping of an (additional) exon from the pre-mRNA, the reading frame can be restored. This can be achieved with antisense oligonucleotides (AONs), which induce exon skipping by binding to splice sites or splice enhancer sites. The resulting protein will be shorter but at least partially functional. So far, exon skipping has been very successful in cell cultures, in mouse and dog models, and even in a first exploratory study in patients. Current research mainly focuses on optimization of systemic AON delivery. Here we give an overview of the available mouse models. To obtain the most informative results for future clinical application, research may have to move from the currently preferred mdx mouse to mouse models more comparable to patients, such as the utrophin/dystrophin-negative mouse and the hDMD mouse models. Further, we briefly discuss two AON backbone chemistries that are currently in clinical trials for DMD exon skipping. We propose that different chemistries should be further developed in parallel in order to hasten the transfer of the exon skipping therapy to the clinic.

Asunto(s)

Exones/genética , Distrofia Muscular de Duchenne/terapia , Oligonucleótidos Antisentido/administración & dosificación , Oligonucleótidos Antisentido/química , Oligonucleótidos Fosforotioatos/administración & dosificación , Oligonucleótidos Fosforotioatos/química , Animales , Modelos Animales de Enfermedad , Perros , Humanos , Ratones , Ratones Endogámicos mdx , Distrofia Muscular de Duchenne/genética , Oligonucleótidos Antisentido/genética , Oligonucleótidos Fosforotioatos/genética