RESUMEN
Alternative polyadenylation (APA) creates distinct transcripts from the same gene by cleaving the pre-mRNA at poly(A) sites that can lie within the 3' untranslated region (3'UTR), introns, or exons. Most studies focus on APA within the 3'UTR; however, here, we show that CPSF6 insufficiency alters protein levels and causes a developmental syndrome by deregulating APA throughout the transcript. In neonatal humans and zebrafish larvae, CPSF6 insufficiency shifts poly(A) site usage between the 3'UTR and internal sites in a pathway-specific manner. Genes associated with neuronal function undergo mostly intronic APA, reducing their expression, while genes associated with heart and skeletal function mostly undergo 3'UTR APA and are up-regulated. This suggests that, under healthy conditions, cells toggle between internal and 3'UTR APA to modulate protein expression.
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Poliadenilación , Pez Cebra , Animales , Humanos , Recién Nacido , Regiones no Traducidas 3' , Exones , Intrones/genética , Pez Cebra/genética , Embrión no MamíferoRESUMEN
Background: Optimal management of androgen excess in 21-hydroxylase deficiency (21OHD) remains challenging. 11-oxygenated-C19 steroids (11-oxyandrogens) have emerged as promising biomarkers of disease control, but data regarding their response to treatment are lacking. Objective: To compare the dynamic response of a broad set of steroids to both conventional oral glucocorticoids (OG) and circadian cortisol replacement via continuous subcutaneous hydrocortisone infusion (CSHI) in patients with 21OHD based on 24-hour serial sampling. Participants and Methods: We studied 8 adults (5 women), ages 19-43 years, with poorly controlled classic 21OHD who participated in a single-center open-label phase I-II study comparing OG with CSHI. We used mass spectrometry to measure 15 steroids (including 11-oxyandrogens and Δ5 steroid sulfates) in serum samples obtained every 2 h for 24 h after 3 months of stable OG, and 6 months into ongoing CSHI. Results: In response to OG therapy, androstenedione, testosterone (T), and their four 11-oxyandrogen metabolites:11ß-hydroxyandrostenedione, 11-ketoandrostenedione, 11ß-hydroxytestosterone and 11-ketotestosterone (11KT) demonstrated a delayed decline in serum concentrations, and they achieved a nadir between 0100-0300. Unlike DHEAS, which had little diurnal variation, pregnenolone sulfate (PregS) and 17-hydoxypregnenolone sulfate peaked in early morning and declined progressively throughout the day. CSHI dampened the early ACTH and androgen rise, allowing the ACTH-driven adrenal steroids to return closer to baseline before mid-day. 11KT concentrations displayed the most consistent difference between OG and CSHI across all time segments. While T was lowered by CSHI as compared with OG in women, T increased in men, suggesting an improvement of the testicular function in parallel with 21OHD control in men. Conclusion: 11-oxyandrogens and PregS could serve as biomarkers of disease control in 21OHD. The development of normative data for these promising novel biomarkers must consider their diurnal variability.
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Hiperplasia Suprarrenal Congénita/sangre , Glucocorticoides/sangre , Esteroides/sangre , Hiperplasia Suprarrenal Congénita/tratamiento farmacológico , Adulto , Biomarcadores , Ritmo Circadiano/efectos de los fármacos , Femenino , Glucocorticoides/uso terapéutico , Humanos , Hidrocortisona/uso terapéutico , Masculino , Sulfatos/sangre , Adulto JovenRESUMEN
OBJECTIVE: Puberty-induced insulin resistance is considered critical in the pathogenesis of type 2 diabetes (T2D) in youth. The development of T2D before puberty suggests distinct risk factors and pathophysiology but, because of its rarity, this has not been well studied. We aimed to describe the clinical characteristics of children with T2D diagnosed before the onset of puberty. RESEARCH DESIGN AND METHODS: We retrospectively studied all children with autoantibody-negative T2D and available pubertal development assessment seen at our center between July 2016 and July 2019, and compared characteristics of those at Tanner stage I (prepubertal, n = 35) versus those at Tanner II-V of pubertal development (n = 341). RESULTS: At T2D diagnosis, prepubertal children compared with those at Tanner II-V had higher body mass index z-score (p = 0.003) and higher C-peptide (p = 0.003) (while glucose levels were not significantly different), with differences retaining significance after adjustment for glucose, race/ethnicity and sex. Dyslipidemia occurred in 100% of prepubertal children versus 89.7% of those diagnosed later (p = 0.036). Of the prepubertal children diagnosed under age 10 (n = 13), 69.2% were female, 100% racial/ethnic minority, 100% had obesity with history of dyslipidemia and none with diabetic ketoacidosis. CONCLUSIONS: T2D, although rarely, can develop before puberty. Children with T2D diagnosed in the prepubertal period have more severe obesity, greater insulin resistance, and more frequent dyslipidemia than older youth. These findings suggest that children with prepubertal T2D are at increased risk for associated morbidity compared with older youth and underscore the significance of interventions to prevent and treat obesity in early childhood.
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Diabetes Mellitus Tipo 2/epidemiología , Resistencia a la Insulina/fisiología , Pubertad/fisiología , Adolescente , Autoanticuerpos/sangre , Índice de Masa Corporal , Niño , Diabetes Mellitus Tipo 2/inmunología , Diabetes Mellitus Tipo 2/fisiopatología , Dislipidemias/epidemiología , Minorías Étnicas y Raciales/estadística & datos numéricos , Femenino , Humanos , Islotes Pancreáticos/inmunología , Masculino , Obesidad Infantil/epidemiología , Obesidad Infantil/genética , Estudios Retrospectivos , Factores de RiesgoRESUMEN
BACKGROUND: In a phase 2 short-term (6 months) study of patients with congenital adrenal hyperplasia (CAH), continuous subcutaneous hydrocortisone infusion (CSHI) was found to be a safe, effective and well-tolerated method of replacing cortisol with improved disease and patient-related outcomes. OBJECTIVE: To evaluate the safety and efficacy of long-term CSHI. DESIGN: Single-centre, open-label, phase 2 extension study. PATIENTS: Five adults with classic CAH. MEASUREMENTS: Biomarkers of disease control, metabolic indices and health-related quality-of-life (HRQoL) estimates. RESULTS: Six of eight patients chose to continue on long-term CSHI therapy. Compared to baseline, eighteen months of CSHI resulted in decreased (P = 0.043) 0700-hour ACTH, 17-hydroxyprogesterone, androstenedione and progesterone; increased whole-body lean mass (P = 0.024); and improved HRQoL, especially symptoms of adrenal insufficiency (P = 0.003). Findings at six and eighteen months did not differ, and improvements achieved in androgen control, lean body mass and HRQoL after 6 months of CSHI were maintained at eighteen months. The hydrocortisone dose appeared to decrease with time [6 vs 18 months: 38.3 ± 8.8 vs 33.6 ± 12.2 mg/day (P = 0.062)], especially in women receiving oral contraceptives. Reduction of testicular adrenal rest and adrenal size observed at 6 months remained stable. In one patient, an adrenal adenoma continually decreased over time. Subjective improvement in hirsutism was reported. CONCLUSIONS: Long-term use of CSHI is a safe and well-tolerated treatment option in a select set of adults with classic CAH. Improvements observed short term in disease control and subjective health status continued long term.
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Hiperplasia Suprarrenal Congénita/tratamiento farmacológico , Hidrocortisona/administración & dosificación , Hidrocortisona/uso terapéutico , Hiperplasia Suprarrenal Congénita/sangre , Adulto , Biomarcadores/sangre , Índice de Masa Corporal , Densidad Ósea/efectos de los fármacos , Femenino , Humanos , Hidrocortisona/efectos adversos , Hidrocortisona/sangre , Masculino , Espectroscopía de Protones por Resonancia Magnética , Calidad de VidaRESUMEN
Management of adult patients with classic congenital adrenal hyperplasia (CAH) is challenging and often complicated by obesity, metabolic syndrome, and adverse cardiovascular risk. Alterations in weight can influence cortisol kinetics. A 19-year-old woman with classic CAH and morbid obesity experienced persistent elevations of androgen levels while receiving oral glucocorticoid therapy. Control of adrenal androgens was improved with continuous subcutaneous hydrocortisone infusion therapy, but obesity-related comorbidities persisted. After undergoing sleeve gastrectomy, the patient experienced dramatic weight loss, with improvement in insulin sensitivity and fatty liver in the postbariatric period. Cortisol clearance studies performed to evaluate changes in hydrocortisone dose requirements showed marked alternations in cortisol pharmacokinetics with decreases in volume of distribution and cortisol clearance, along with an increase in area under the curve for cortisol. Hydrocortisone dose was subsequently decreased 34% by 15 months after surgery. Effective control of androgen excess on this lower hydrocortisone dose was achieved and continues 27 months after surgery. This case highlights obesity-related complications of glucocorticoid replacement therapy in the management of CAH. Individual patient factors, such as fatty liver disease and insulin resistance, can have a clinically important effect on cortisol metabolism. Bariatric surgery was a safe and effective treatment of obesity in this patient with CAH and should be considered for patients with CAH and multiple obesity-related comorbidities.
RESUMEN
OBJECTIVE: Brown adipose tissue (BAT) has been proposed as a potential therapeutic target against obesity and its related metabolic conditions. Data from studies in rodents support a cross talk between BAT and other distal tissues. The relation between BAT and peptide hormones secreted from the gastrointestinal system (GI) and involved in appetite regulation is not known in humans. DESIGN: We studied 18 men during thermoneutral conditions and mild non-shivering cold exposure (CE). METHODS: 2-Deoxy-2-(18F)fluoro-d-glucose positron emission tomography-computed tomography scans were conducted after mild cold to measure BAT volume. Fasting serum concentration of GI-secreted peptides and peptides involved in appetite regulation were measured during thermoneutral conditions and mild CE. RESULTS: During thermoneutral conditions, BAT volume was associated with lower serum concentration of leptin (P = 0.006), gastric inhibitory polypeptide (P = 0.016) and glucagon (P = 0.048) after adjusting for age and body fat percent. CE significantly decreased serum leptin (P = 0.004) and glucagon concentration (P = 0.020), while cold-induced BAT activation was significantly associated with lower serum ghrelin concentration (P = 0.029). CONCLUSIONS: BAT is associated with systemic concentrations of GI-secreted peptides and peptides involved in appetite regulation, suggesting a potential cross talk between BAT and the enteropancreatic axis. Further studies are needed to elucidate the potential link of BAT with the postprandial levels of appetite-regulating peptides and the putative role of BAT in appetite regulation in humans.
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Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Pardo/fisiología , Regulación del Apetito/fisiología , Tracto Gastrointestinal/metabolismo , Tracto Gastrointestinal/fisiología , Neuropéptidos/metabolismo , Neuropéptidos/fisiología , Tejido Adiposo Pardo/diagnóstico por imagen , Adiposidad , Adulto , Anciano , Envejecimiento/metabolismo , Composición Corporal , Frío , Fluorodesoxiglucosa F18 , Polipéptido Inhibidor Gástrico/sangre , Polipéptido Inhibidor Gástrico/metabolismo , Ghrelina/sangre , Glucagón/sangre , Glucagón/metabolismo , Humanos , Leptina/sangre , Leptina/metabolismo , Masculino , Persona de Mediana Edad , Tomografía de Emisión de Positrones , RadiofármacosRESUMEN
CONTEXT: Classic congenital adrenal hyperplasia (CAH) management remains challenging, given that supraphysiologic glucocorticoid doses are often needed to optimally suppress the ACTH-driven adrenal androgen overproduction. OBJECTIVE: This study sought to approximate physiologic cortisol secretion via continuous subcutaneous hydrocortisone infusion (CSHI) and evaluate the safety and efficacy of CSHI in patients with difficult-to-treat CAH. DESIGN: Eight adult patients with classic CAH participated in a single-center open-label phase I-II study comparing CSHI to conventional oral glucocorticoid treatment. All patients had elevated adrenal steroids and one or more comorbidities at study entry. Assessment while receiving conventional therapy at baseline and 6 months following CSHI included: 24-hour hormonal sampling, metabolic and radiologic evaluation, health-related quality-of-life (HRQoL), and fatigue questionnaires. MAIN OUTCOME MEASURES: The ability of CSHI to approximate physiologic cortisol secretion and the percent of patients with 0700-hour 17-hydroxyprogesterone (17-OHP) ≤1200 ng/dL was measured. RESULTS: CSHI approximated physiologic cortisol secretion. Compared with baseline, 6 months of CSHI resulted in decreased 0700-hour and 24-hour area under the curve 17-OHP, androstenedione, ACTH, and progesterone, increased osteocalcin, c-telopeptide and lean mass, and improved HRQoL (and SF-36 Vitality Score), and fatigue. One of three amenorrheic women resumed menses. One man had reduction of testicular adrenal rest tissue. CONCLUSIONS: CSHI is a safe and well-tolerated modality of cortisol replacement that effectively approximates physiologic cortisol secretion in patients with classic CAH poorly controlled on conventional therapy. Improved adrenal steroid control and positive effects on HRQoL suggest that CSHI should be considered a treatment option for classic CAH. The long-term effect on established comorbidities requires further study.
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Hiperplasia Suprarrenal Congénita/sangre , Hiperplasia Suprarrenal Congénita/tratamiento farmacológico , Glucocorticoides/administración & dosificación , Glucocorticoides/farmacocinética , Terapia de Reemplazo de Hormonas/métodos , Hidrocortisona/administración & dosificación , Hidrocortisona/farmacocinética , Evaluación de Resultado en la Atención de Salud , Adulto , Biomarcadores/sangre , Femenino , Glucocorticoides/efectos adversos , Terapia de Reemplazo de Hormonas/efectos adversos , Humanos , Hidrocortisona/efectos adversos , Infusiones Subcutáneas , Masculino , Adulto JovenRESUMEN
UNLABELLED: X-linked nephrogenic diabetes insipidus (NDI, OMIM#304800) is caused by mutations in the arginine vasopressin (AVP, OMIM*192340) receptor type 2 (AVPR2, OMIM*300538) gene. A 20-month-old boy and his 8-year-old brother presented with polyuria, polydipsia, and failure to thrive. Both boys demonstrated partial DDAVP (1-desamino-8-D AVP or desmopressin) responses; thus, NDI diagnosis was delayed. While routine sequencing of AVPR2 showed a potential splice site variant, it was not until exome sequencing confirmed the AVPR2 splice site variant and did not reveal any more likely candidates that the patients' diagnosis was made and proper treatment was instituted. Both patients were hemizygous for two AVPR2 variants predicted in silico to affect AVPR2 messenger RNA (mRNA) splicing. A minigene assay revealed that the novel AVPR2 c.276A>G mutation creates a novel splice acceptor site leading to 5' truncation of AVPR2 exon 2 in HEK293 human kidney cells. Both patients have been treated with high-dose DDAVP with a remarkable improvement of their symptoms and accelerated linear growth and weight gain. CONCLUSION: We present here a unique case of partial X-linked NDI due to an AVPR2 splice site mutation; patients with diabetes insipidus of unknown etiology may harbor splice site mutations that are initially underestimated in their pathogenicity on sequence analysis. WHAT IS KNOWN: ⢠X-linked nephrogenic diabetes insipidus is caused by AVPR2 mutations, and disease severity can vary depending on the functional effect of the mutation. What is New: ⢠We demonstrate here that a splice site mutation in AVPR2 leads to partial X-linked NDI in two brothers. ⢠Treatment with high-dose DDAVP led to improvement of polyuria and polydipsia, weight gain, and growth.
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Diabetes Insípida Nefrogénica/genética , Mutación , Sitios de Empalme de ARN/genética , Receptores de Vasopresinas/genética , Hermanos , Niño , Análisis Mutacional de ADN , Diabetes Insípida Nefrogénica/metabolismo , Humanos , Lactante , Masculino , Linaje , Receptores de Vasopresinas/metabolismoRESUMEN
OBJECTIVES: The treatment goal in congenital adrenal hyperplasia (CAH) is to replace glucocorticoids while avoiding androgen excess and iatrogenic Cushing's syndrome. However, there is no consensus on how to monitor disease control. Our main objectives were to evaluate hormonal circadian rhythms and use these profiles to identify optimal monitoring times and novel disease biomarkers in CAH adults on intermediate- and long-acting glucocorticoids. DESIGN: This was an observational, cross-sectional study at the National Institutes of Health Clinical Center in 16 patients with classic CAH. METHODS: Twenty-four-hour serum sampling for ACTH, 17-hydroxyprogesterone (17OHP), androstenedione (A4), androsterone, DHEA, testosterone, progesterone and 24-h urinary pdiol and 5ß-pdiol was carried out. Bayesian spectral analysis and cosinor analysis were performed to detect circadian rhythmicity. The number of hours to minimal (TminAC) and maximal (TmaxAC) adrenocortical hormone levels after dose administration was calculated. RESULTS: A significant rhythm was confirmed for ACTH (r(2), 0.95; P<0.001), 17OHP (r(2), 0.70; P=0.003), androstenedione (r(2), 0.47; P=0.043), androsterone (r(2), 0.80; P<0.001), testosterone (r(2), 0.47; P=0.042) and progesterone (r(2), 0.64; P=0.006). The mean (s.d.) TminAC and TmaxAC for 17OHP and A4 were: morning prednisone (4.3 (2.3) and 9.7 (3.5) h), evening prednisone (4.5 (2.0) and 10.3 (2.4) h), and daily dexamethasone (9.2 (3.5) and 16.4 (7.2) h). AUC0-24 h progesterone, androsterone and 24-h urine pdiol were significantly related to 17OHP. CONCLUSION: In CAH patients, adrenal androgens exhibit circadian rhythms influenced by glucocorticoid replacement. Measurement of adrenocortical hormones and interpretation of results should take into account the type of glucocorticoid and time of dose administration. Progesterone and backdoor metabolites may provide alternative disease biomarkers.
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Hiperplasia Suprarrenal Congénita/metabolismo , Ritmo Circadiano , Hormonas/metabolismo , 17-alfa-Hidroxiprogesterona/sangre , 5-alfa-Dihidroprogesterona/orina , Hiperplasia Suprarrenal Congénita/tratamiento farmacológico , Hormona Adrenocorticotrópica/sangre , Adulto , Androstenodiona/sangre , Androsterona/sangre , Biomarcadores/metabolismo , Estudios Transversales , Deshidroepiandrosterona/sangre , Dexametasona/uso terapéutico , Femenino , Glucocorticoides/uso terapéutico , Humanos , Masculino , Prednisona/uso terapéutico , Pregnanodionas/orina , Progesterona/sangre , Testosterona/sangre , Adulto JovenRESUMEN
Body growth is rapid in infancy but subsequently slows and eventually ceases due to a progressive decline in cell proliferation that occurs simultaneously in multiple organs. We previously showed that this decline in proliferation is driven in part by postnatal down-regulation of a large set of growth-promoting genes in multiple organs. We hypothesized that this growth-limiting genetic program is orchestrated by microRNAs (miRNAs). Bioinformatic analysis identified target sequences of the miR-29 family of miRNAs to be overrepresented in age-down-regulated genes. Concomitantly, expression microarray analysis in mouse kidney and lung showed that all members of the miR-29 family, miR-29a, -b, and -c, were strongly up-regulated from 1 to 6 weeks of age. Real-time PCR confirmed that miR-29a, -b, and -c were up-regulated with age in liver, kidney, lung, and heart, and their expression levels were higher in hepatocytes isolated from 5-week-old mice than in hepatocytes from embryonic mouse liver at embryonic day 16.5. We next focused on 3 predicted miR-29 target genes (Igf1, Imp1, and Mest), all of which are growth-promoting. A 3'-untranslated region containing the predicted target sequences from each gene was placed individually in a luciferase reporter construct. Transfection of miR-29 mimics suppressed luciferase gene activity for all 3 genes, and this suppression was diminished by mutating the target sequences, suggesting that these genes are indeed regulated by miR-29. Taken together, the findings suggest that up-regulation of miR-29 during juvenile life drives the down-regulation of multiple growth-promoting genes, thus contributing to physiological slowing and eventual cessation of body growth.
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Crecimiento y Desarrollo/genética , MicroARNs/genética , Regulación hacia Arriba/genética , Regiones no Traducidas 3'/genética , Envejecimiento/genética , Animales , Animales Recién Nacidos , Secuencia de Bases , Regulación hacia Abajo/genética , Regulación del Desarrollo de la Expresión Génica , Células HEK293 , Humanos , Riñón/metabolismo , Pulmón/metabolismo , Masculino , Ratones Endogámicos C57BL , MicroARNs/metabolismo , Datos de Secuencia Molecular , Miocardio/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Especificidad de Órganos/genética , ARN Mensajero/genética , ARN Mensajero/metabolismoRESUMEN
OBJECTIVE: Premature menarche is an uncommon, benign condition characterized by isolated or recurrent menstrual bleeding in the absence of secondary sexual characteristics. METHODS: We performed an observational retrospective study to further characterize the clinical, biochemical and imaging features of benign prepubertal vaginal bleeding (BPVB). Out of 1037 girls evaluated for precocious puberty over a 5-year period, 24 girls with BPVB were identified based on ≥1 episodes of vaginal bleeding, Tanner I or non-progressive Tanner II breast development, and lack of physical findings suggesting genital infection, trauma or foreign body. RESULTS: Age at presentation ranged from 3 years 2 months to 9 years 11 months. Ten patients (42%) had one episode of vaginal bleeding, six (25%) had two episodes and eight patients (33%) had three or more. First bleeding episode lasted 3 days (range; 1-30 days). Six girls had intermittent spotting for up to 1 year. No breast development was noted in 19 (79%) patients. Minimal breast was present in five girls; early pubic hair was present in 2. LH and FSH were prepubertal; estradiol was >20 pg/mL in two girls. Pelvic ultrasound, performed in 11 patients, showed pre-pubertal uterus and ovaries without adnexal masses. CONCLUSION: Isolated prepubertal vaginal bleeding is typically benign and self-limited, in the absence of sexual precocity signs or other vaginal pathology. Laboratory and imaging studies are generally unrevealing.
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Menarquia/fisiología , Pubertad Precoz/diagnóstico , Hemorragia Uterina/diagnóstico , Densidad Ósea/fisiología , Niño , Preescolar , Femenino , Humanos , Pubertad Precoz/diagnóstico por imagen , Radiografía , Estudios Retrospectivos , Hemorragia Uterina/diagnóstico por imagen , Muñeca/diagnóstico por imagenRESUMEN
Peripheral arterial disease (PAD), a manifestation of systemic atherosclerosis that produces blockages in arteries supplying the legs, affects an estimated 27 million people in Europe and North America. Increased production of reactive oxygen species by dysfunctional mitochondria in leg muscles of PAD patients is viewed as a key mechanism of initiation and progression of the disease. Previous studies demonstrated increased oxidative damage in homogenates of biopsy specimens from PAD gastrocnemius compared to controls, but did not address myofiber-specific damage. In this study, we investigated oxidative damage to myofibers as a possible cause of the myopathy of PAD. To achieve this, we developed and validated fluorescence microscopy procedures for quantitative analysis of carbonyl groups and 4-hydroxy-2-nonenal (HNE) adducts in myofibers of biopsy specimens from human gastrocnemius. PAD and control specimens were evaluated for differences in 1) myofiber content of these two forms of oxidative damage and 2) myofiber cross-sectional area. Furthermore, oxidative damage to PAD myofibers was tested for associations with clinical stage of disease, degree of ischemia in the affected leg, and myofiber cross-sectional area. Carbonyl groups and HNE adducts were increased 30% (p < 0.0001) and 40% (p < 0.0001), respectively, in the myofibers of PAD (N = 34) compared to control (N = 21) patients. Mean cross-sectional area of PAD myofibers was reduced 29.3% compared to controls (p < 0.0003). Both forms of oxidative damage increased with clinical stage of disease, blood flow limitation in the ischemic leg, and reduced myofiber cross-sectional area. The data establish oxidative damage to myofibers as a possible cause of PAD myopathy.
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Fibras Musculares Esqueléticas/patología , Estrés Oxidativo , Enfermedad Arterial Periférica/patología , Aldehídos/metabolismo , Índice Tobillo Braquial , Estudios de Casos y Controles , Demografía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedad Arterial Periférica/metabolismo , Carbonilación ProteicaRESUMEN
A myopathy characterized by mitochondrial pathology and oxidative stress is present in patients with peripheral arterial disease (PAD). Patients with PAD differ in disease severity, mode of presentation, and presence of comorbid conditions. In this study, we used a mouse model of hindlimb ischemia to isolate and directly investigate the effects of chronic inflow arterial occlusion on skeletal muscle microanatomy, mitochondrial function and expression, and oxidative stress. Hindlimb ischemia was induced by staged ligation/division of the common femoral and iliac arteries in C57BL/6 mice, and muscles were harvested 12 wk later. Muscle microanatomy was examined by bright-field microscopy, and mitochondrial content was determined as citrate synthase activity in muscle homogenates and ATP synthase expression by fluorescence microscopy. Electron transport chain (ETC) complexes I through IV were analyzed individually by respirometry. Oxidative stress was assessed as total protein carbonyls and 4-hydroxy-2-nonenal (HNE) adducts and altered expression and activity of manganese superoxide dismutase (MnSOD). Ischemic muscle exhibited histological features of myopathy and increased mitochondrial content compared with control muscle. Complex-dependent respiration was significantly reduced for ETC complexes I, III, and IV in ischemic muscle. Protein carbonyls, HNE adducts, and MnSOD expression were significantly increased in ischemic muscle. MnSOD activity was not significantly changed, suggesting MnSOD inactivation. Using a mouse model, we have demonstrated for the first time that inflow arterial occlusion alone, i.e., in the absence of other comorbid conditions, causes myopathy with mitochondrial dysfunction and increased oxidative stress, recapitulating the muscle pathology of PAD patients.
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Isquemia/complicaciones , Mitocondrias Musculares/metabolismo , Músculo Esquelético/patología , Enfermedades Musculares/complicaciones , Estrés Oxidativo/fisiología , Complejos de ATP Sintetasa/metabolismo , Aldehídos/metabolismo , Animales , Enfermedad Crónica , Citrato (si)-Sintasa/metabolismo , Femenino , Regulación de la Expresión Génica , Miembro Posterior/irrigación sanguínea , Humanos , Ratones , Ratones Endogámicos C57BL , Mitocondrias Musculares/enzimología , Superóxido Dismutasa/metabolismoRESUMEN
In recent years, an increasing number of studies have demonstrated that a myopathy is present, contributes, and, to a certain extent, determines the pathogenesis of peripheral arterial occlusive disease. These works provide evidence that a state of repetitive cycles of exercise-induced ischemia followed by reperfusion at rest operates in patients with peripheral arterial occlusive disease and mediates a large number of structural and metabolic changes in the muscle, resulting in reduced strength and function. The key players in this process appear to be defective mitochondria that, through multilevel failure in their roles as energy, oxygen radical species, and apoptosis regulators, produce and sustain a progressive decline in muscle performance. In this 2-part review, the currently available evidence that characterizes the nature and mechanisms responsible for this myopathy is highlighted. In part 1, the functional and histomorphological characteristics of the myopathy were reviewed, and the main focus was on the biochemistry and bioenergetics of its mitochondriopathy. In part 2, accumulating evidence that oxidative stress related to ischemia reperfusion is probably the major operating mechanism of peripheral arterial occlusive disease myopathy is reviewed. Important new findings of a possible neuropathy and a shift in muscle fiber type are also reviewed. Learning more about these mechanisms will enhance our understanding of the degree to which they are preventable and treatable.
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Arteriopatías Oclusivas/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , Enfermedades Musculares/metabolismo , Estrés Oxidativo , Enfermedades Vasculares Periféricas/metabolismo , Animales , Arteriopatías Oclusivas/patología , Arteriopatías Oclusivas/fisiopatología , Sistema Nervioso Autónomo/fisiopatología , Metabolismo Energético , Ejercicio Físico , Humanos , Mitocondrias Musculares/metabolismo , Fibras Musculares Esqueléticas/patología , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/inervación , Músculo Esquelético/patología , Enfermedades Musculares/patología , Enfermedades Musculares/fisiopatología , Enfermedades Vasculares Periféricas/patología , Enfermedades Vasculares Periféricas/fisiopatología , Daño por Reperfusión/metabolismoRESUMEN
The signs and symptoms of peripheral arterial occlusive disease (PAD), including claudication, rest pain, and tissue loss, are consequences of compromised bioenergetics and oxidative tissue injury within the affected lower extremities. Compromised bioenergetics is the result of a combination of low blood flow through diseased arteries and diminished adenosine triphosphate production by dysfunctional mitochondria. The tissue injury appears to be secondary to increased production of reactive oxygen species by dysfunctional mitochondria and by inflammation, in association with ischemia and ischemia/reperfusion. In this review, we present the current histomorphologic, physiologic, and biochemical evidence defining the nature of this mitochondriopathy and discuss its contribution to the pathogenesis and clinical manifestations of PAD.
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Arteriopatías Oclusivas/etiología , Miopatías Mitocondriales/complicaciones , Enfermedades Vasculares Periféricas/etiología , ADN Mitocondrial/genética , Transporte de Electrón/fisiología , Humanos , Extremidad Inferior , Mitocondrias Musculares/fisiología , Miopatías Mitocondriales/genética , Miopatías Mitocondriales/fisiopatología , Músculo Esquelético/fisiopatología , Estrés OxidativoRESUMEN
In recent years, an increasing number of studies have demonstrated that a myopathy is present, contributes, and, to a certain extent, determines the pathogenesis of peripheral arterial occlusive disease (PAD). These works provide evidence that a state of repetitive cycles of exercise-induced ischemia followed by reperfusion at rest operates in PAD patients and mediates a large number of structural and metabolic changes in the muscle, resulting in reduced strength and function. The key players in this process appear to be defective mitochondria that, through multilevel failure in their roles as energy, oxygen radical species, and apoptosis regulators, produce and sustain a progressive decline in muscle performance. In this 2-part review, we highlight the currently available evidence that characterizes the nature and mechanisms responsible for this myopathy. In part 1, the authors review the functional and histomorphological characteristics of the myopathy and focus on the biochemistry and bioenergetics of its mitochondriopathy. In part 2, they then review accumulating evidence that oxidative stress related to ischemia reperfusion is probably the major operating mechanism of PAD myopathy. Important new findings of a possible neuropathy and a shift in muscle fiber type are also reviewed. Learning more about these mechanisms will enhance our understanding of the degree to which they are preventable and treatable.