Humberto Santo Neto

University of Campinas, Conceição de Campinas, São Paulo, Brazil

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Publications (61)109.3 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Introduction: The purpose of this study was to better understand the beneficial effects of doxycycline on the dystrophic muscles of the mdx mouse. Methods: Doxycycline (DOX) was administered for 36 days, starting on postnatal day 0, via drinking water. Untreated mdx mice received plain water for the same period and served as a control group. Results: DOX decreased the levels of metalloproteinase-9 and tumor necrosis factor alpha in the biceps brachii and diaphragm of the mdx mice. It also reduced the total amount of calcium in the muscles studied, concomitant with an increase in the levels of calsequestrin 1. Discussion: These results show that DOX can affect factors that are important in the dystrophic pathogenesis and highlight its potential to be a readily accessible therapy for clinical trials for treatment of Duchenne muscular dystrophy. © 2014 Wiley Periodicals, Inc.
    Muscle & Nerve 01/2014; · 2.31 Impact Factor
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    ABSTRACT: In dystrophic mdx mice and in Duchenne muscular dystrophy, inflammation contributes to myonecrosis. Previously, we demonstrated that eicosapentaenoic acid (EPA) decreased inflammation and necrosis in dystrophic muscle. In the present study, we examined the effects of EPA and the corticoid deflazacort (DFZ) as modulators of M1 (iNOS-expressing cells) and M2 (CD206-expressing cells) macrophages. Mdx mice (14days old) received EPA or DFZ for 16days. The diaphragm, biceps brachii and quadriceps muscles were studied. Immunofluorescence, immunoblotting and ELISA assays showed that EPA increased interleucin-10, reduced interferon-γ and was more effective than DFZ in promoting a shift from M1 to M2.
    Journal of neuroimmunology 09/2013; · 2.84 Impact Factor
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    ABSTRACT: Introduction: To evaluate the effects of suramin, an antifibrotic agent, on the cardiac function and remodeling in the mdx mice. Methods: mdx mice (8 months old) received intraperitoneal injections of suramin twice a week for 3 months. Control mdx mice (8 months old) were injected with saline. Results: Suramin improved the electrocardiography profile with main corrections seen in S/R wave ratio, PR interval, Q amplitude with a significant decrease in the cardiomyopathy index. Suramin decreased myocardial fibrosis, inflammation, and myonecrosis. Discussion - These findings suggest that the antifibrotic drug suramin may be a potential new adjunctive therapy to help improve cardiomyopathy in DMD. © 2013 Wiley Periodicals, Inc.
    Muscle & Nerve 03/2013; · 2.31 Impact Factor
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    ABSTRACT: BACKGROUND & AIMS: In Duchenne muscular dystrophy (DMD) and in the mdx mouse model of DMD, the lack of dystrophin leads to muscle degeneration and inflammation contributes to progression of the disease. In this study, we evaluated the effects of commercially available fish oil containing EPA and docosahexaenoic acid (DHA) on mdx. METHODS: Mdx mice (14 days old) were treated with fish oil (FDC Vitamins; 0.002 g EPA and 0.001 g DHA) for 16 days by gavage. Control mdx mice received mineral oil (Nujol). Grip strength measurement was used for functional evaluation. The sternomastoid, diaphragm and biceps brachii muscles were removed and processed for histopathology and Western blot analysis. RESULTS: Fish oil decreased creatine kinase and myonecrosis. In all muscles studied, the inflammatory area was significantly reduced after treatment (18.0 ± 3.0% inflammatory area in untreated mdx mice versus 4.0 ± 1% in treated mdx mice). Fish oil protected against the loss of muscle strength. Fish oil significantly reduced the levels of TNF-α and the levels of 4-HNE-protein adducts (30-34% reduction for both) in all muscles studied. CONCLUSIONS: Commercially available fish oil may be potentially useful to ameliorate dystrophic progression of skeletal muscles, deserving further clinical trials in DMD patients.
    Clinical nutrition (Edinburgh, Scotland) 11/2012; · 3.27 Impact Factor
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    ABSTRACT: Introduction: In Duchenne muscular dystrophy and in the mdx mouse, muscle fiber degeneration and subsequent fibrosis lead to cardiorespiratory failure. Previously, we demonstrated that the anti-fibrotic agent suramin was effective in decreasing fibrosis in mdx muscles. In this study, we were interested to see whether suramin could affect metalloproteinases (MMP) and improve the functional activity of the mdx diaphragm muscle. Methods: Zymography was performed to evaluate MMP-2 and MMP-9 activity. Western blotting was used to analyze the levels of beta-dystroglycan. Muscle function was assessed in hemidiaphragm in vitro preparations. Results: We found that suramin affects metalloproteinase-9 activity and increases beta-dystroglycan. Furthermore, suramin also protects against diaphragm muscle fatigue over time. Conclusions: These results show the potential benefits of suramin in maintaining the structure of the dystrophin-glycoprotein complex. Muscle Nerve, 46:810-813, 2012.
    Muscle & Nerve 11/2012; 46(5):810-3. · 2.31 Impact Factor
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    ABSTRACT: We examined whether doxycycline, an antibiotic member of the tetracycline family, improves the histopathology and muscle function in mdx mice, the experimental model of DMD. Doxycycline was administered for 36 days (starting on postnatal day 0) and for 9 months (starting at 8 months of age) in drinking water. Histopathological, biochemical (creatine kinase), and functional (forelimb muscle grip strength) parameters were evaluated in limb, diaphragm, and cardiac muscle. Doxycycline significantly minimized the dystrophic phenotype of skeletal and cardiac muscles and improved forelimb muscle strength. The drug protected muscle fibers against myonecrosis and reduced inflammation. Furthermore, it slowed the progression of myocardial fibrosis. This study provides evidence that doxycycline may be a potential therapeutic agent for DMD.
    Muscle & Nerve 09/2012; 46(3):400-6. · 2.31 Impact Factor
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    ABSTRACT: BACKGROUND & AIMS: Duchenne muscular dystrophy (DMD) is a genetic muscle disease caused by the absence of dystrophin. An established animal model of DMD is the mdx mouse, which is unable to express dystrophin. Inflammation, particularly the proinflammatory cytokine tumor necrosis factor alpha (TNF-α), strongly contributes to necrosis in the dystrophin-deficient fibers of the mdx mice and in DMD. In this study we investigated whether the antioxidant N-acetylcysteine (NAC) decreases TNF-α levels and protects the diaphragm muscle of mdx mice against necrosis. METHODS: Mdx mice (14 days old) received daily intraperitoneal injections of NAC for 14 days, followed by removal of the diaphragm muscle. Control mdx mice were injected with saline. RESULTS: NAC reduced TNF-α and 4-HNE-protein adducts levels, inflammation, creatine kinase levels, and myonecrosis in diaphragm muscle. CONCLUSIONS: NAC may be used as a complementary treatment for dystrophinopathies. However, clinical trials are needed to determine the appropriate dose for patients with Duchenne muscular dystrophy.
    Clinical nutrition (Edinburgh, Scotland) 06/2012; · 3.27 Impact Factor
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    ABSTRACT: Oxidative stress contributes to myonecrosis in the dystrophin-deficient fibers of mdx mice and in Duchenne's muscular dystrophy. We examined the effects of ascorbic acid (AA), an antioxidant and free radical scavenger, on the dystrophic diaphragm muscle. Mdx mice (14 d old) received AA for 14 d. Control mdx mice received saline. The muscle damage was visualized by the penetration of Evans blue dye into myofibers and the extent of inflammation was assessed by histologic analysis. Creatine kinase levels were measured for the biochemical evaluation of muscle fiber degeneration. The levels of tumor necrosis factor-α (a proinflammatory cytokine) and 4-hydroxynonenal (a marker of lipid peroxidation) were analyzed by immunoblotting. Ascorbic acid decreased creatine kinase levels, myonecrosis, inflammation, and the levels of tumor necrosis factor-α and 4-hydroxynonenal. The present results suggest that AA plays a protective role in dystrophic muscle degeneration, possibly by decreasing reactive oxygen species, and support further investigations of AA as a potential therapy for dystrophinopathies.
    Nutrition 12/2011; 28(6):686-90. · 2.86 Impact Factor
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    ABSTRACT: In this study we investigate whether dystrophic intrinsic laryngeal muscles (ILM) from aged mdx mice show alterations in dystrophin-glycoprotein complex (DGC) components.Immunofluorescence and immunoblotting analyses of beta-sarcoglycan, beta-dystroglycan, and utrophin showed that aged ILM had a similar pattern of changes in aged affected muscles (diaphragm and limb), suggesting that aging leads to changes in utrophin and DGC proteins in dystrophic ILM that cannot be correlated with their protection from dystrophic change.
    Muscle & Nerve 12/2011; 44(6):978-80. · 2.31 Impact Factor
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    ABSTRACT: In Duchenne muscular dystrophy (DMD) and in the mdx mouse model of DMD, the lack of dystrophin is related to enhanced calcium influx and muscle degeneration. Stretch-activated channels (SACs) might be directly involved in the pathology of DMD, and transient receptor potential cation channels have been proposed as likely candidates of SACs. We investigated the levels of transient receptor potential canonical channel 1 (TRPC1) and the effects of streptomycin, a SAC blocker, in muscles showing different degrees of the dystrophic phenotype. Mdx mice (18 days old, n = 16) received daily intraperitoneal injections of streptomycin (182 mg/kg body wt) for 18 days, followed by removal of the diaphragm, sternomastoid (STN), biceps brachii, and tibialis anterior muscles. Control mdx mice (n = 37) were injected with saline. Western blot analysis showed higher levels of TRPC1 in diaphragm muscle compared with STN and limb muscles. Streptomycin reduced creatine kinase and prevented exercise-induced increases of total calcium and Evans blue dye uptake in diaphragm and in STN muscles. It is suggested that different levels of the stretch-activated calcium channel protein TRPC1 may contribute to the different degrees of the dystrophic phenotype seen in mdx mice. Early treatment designed to regulate the activity of these channels may ameliorate the progression of dystrophy in the most affected muscle, the diaphragm.
    AJP Cell Physiology 09/2011; 301(6):C1344-50. · 3.71 Impact Factor
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    ABSTRACT: The anatomy of the Guyon canal is crucial for open and endoscopic surgeries for ulnar canal syndrome at the wrist level. It is also of interest for surgical treatment of carpal canal syndromes. Whereas the Guyon canal is largely described in adults, no studies exist in children. In the present study, the authors examined the Guyon canal in children. Sectional anatomy was used. Thirty-two formalin-fixed cadavers (64 sides) were examined (age range 2-11 years). The hands were transversely cut into 2-3-mm-thick slices. Slices were placed in embedding medium, and transverse sections (10 μm thick) were stained with histological methods and photographed under a light microscope. The roof of the Guyon canal was attached to the flexor retinaculum laterally to the hamulus of the hamate bone. Thus, the radial boundary of the Guyon canal was lateral to the hamulus, which became part of the floor of the Guyon canal. An ulnar neurovascular bundle was found directly volar to the hamulus in 93.8% of the cases and slightly medial to the hamulus (to the ulnar side) in 6.2% of the cases. Proximally, the ulnar artery and nerve were sustained by the flexor retinaculum in direct apposition to the carpal canal. In children, the Guyon canal displays an anatomical particularity regarding the topography of the ulnar artery and nerve that may be of relevance for intraoperative orientation and endoscopic navigation to avoid lesions to the ulnar nerve and artery in carpal and Guyon canal syndromes.
    Journal of Neurosurgery Pediatrics 03/2011; 7(3):286-9. · 1.63 Impact Factor
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    Renato Ferretti, Humberto Santo Neto, Maria Julia Marques
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    ABSTRACT: In mdx mice, intrinsic laryngeal muscles are spared and sternomastoid muscles are affected, showing cycles of muscle regeneration. We observed that utrophin and acetylcholine receptors are fragmented only in affected muscles, providing further evidence that changes in the overall distribution of molecules at dystrophic neuromuscular junctions may be correlated with muscle regeneration.
    The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 02/2011; 294(2):283-6. · 1.34 Impact Factor
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    ABSTRACT: Fibrosis is a pathological feature observed in patients with Duchenne muscular dystrophy (DMD) and in mdx mice, the experimental model of DMD. We evaluated the effect of suramin, a transforming growth factor-beta 1 (TGF-β1) blocker, on fibrosis in mdx mice. mdx mice (6 months old) received suramin for 7 weeks. Suramin- and saline-treated (control) mdx mice performed exercise on a treadmill to worsen disease progression. Immunoblotting showed an increase of TGF-β1 in mdx diaphragm, limb, and cardiac muscles. Suramin decreased creatine kinase in mdx mice and attenuated fibrosis in all muscles studied, except for cardiac muscle. Suramin protected limb muscles against damage and reduced the exercise-induced loss of strength over time. These findings support a role for TGF-β1 in fibrinogenesis and myonecrosis during the later stages of disease in mdx mice. Suramin might be a useful therapeutic alternative for the treatment of dystrophinopathies.
    Muscle & Nerve 01/2011; 43(1):82-7. · 2.31 Impact Factor
  • Neuromuscular Disorders - NEUROMUSCULAR DISORD. 01/2011; 21(9):710-710.
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    ABSTRACT: In dystrophin-deficient fibers of mdx mice and in Duchenne muscular dystrophy, inflammation and increased production of tumor necrosis factor alpha (TNF-α) contribute to myonecrosis. We examined the effects of eicosapentaenoic acid (EPA) on dystrophic muscle degeneration. Mdx mice (14 days old) received EPA for 16 days. The sternomastoid, diaphragm and biceps brachii muscles were removed. Control mdx mice received vehicle. EPA decreased creatine kinase and myonecrosis and reduced the levels of TNF-α. These results suggest that EPA plays a protective role in dystrophic muscle degeneration, possibly by reducing TNF-α, and support further investigations of EPA as a potential therapy for dystrophinopathies.
    Journal of neuroimmunology 12/2010; 232(1-2):145-50. · 2.84 Impact Factor
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    ABSTRACT: The muscle fiber phenotype is mainly determined by motoneuron innervation and changes in neuromuscular interaction alter the muscle fiber type. In dystrophin-deficient mdx mice, changes in the molecular assembly of the neuromuscular junction and in nerve terminal sprouting occur in the sternomastoid (STN) muscle during early stages of the disease. In this study, we were interested to see whether early changes in neuromuscular assembly are correlated with alterations in fiber type in dystrophic STN at 2 months of age. A predominance of hybrid fast myofibers (about 52% type IIDB) was observed in control (C57Bl/10) STN. In mdx muscle, the lack of dystrophin did not change this profile (about 54% hybrid type IIDB). Pure fast type IID fibers predominated in normal and dystrophic diaphragm (DIA; about 39% in control and 30% in mdx muscle) and a population of slow Type I fibers was also present (about 10% in control and 13% in mdx muscle). In conclusion, early changes in neuromuscular assembly do not affect the fiber type composition of dystrophic STN. In contrast to the pure fast fibers of the more affected DIA, the hybrid phenotype of the STN may permit dynamic adaptations during progression of the disease.
    The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 10/2010; 293(10):1722-8. · 1.34 Impact Factor
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    ABSTRACT: Cardiac failure secondary to myocardial fibrosis (MF) significantly contributes to death in Duchenne muscular dystrophy (DMD), a fatal form of muscle disease. In aging, the mdx mice, an animal model of DMD, MF is similar to that observed in humans. Nitric oxide-based therapy has been proposed to retard MF in DMD and a candidate is L-arginine (L-arg). In this study we evaluated the effects of long-term therapy with L-arg in the MF of mdx mice. mdx mice (6 months old) were treated with L-arg in drinking water. Control mdx mice received water only. After 15 months of treatment, hearts were stained with Masson's trichrome for analysis of MF and with hematoxilyn and eosin for analysis of inflammation and cardiomyocyte damage. We observed that MF was not affected (29.5 +/- 2.5% of MF area for control vs 31.4 +/- 2% for L-arginine-treated animals; P > 0.05). The density of inflammatory cells was reduced (169 +/- 12 cells/mm 2 in control vs 102 +/- 9 cells/mm 2 in L-arg-treated; P < 0.05). The present study shows that long-term administration of L-arg is not effective in retarding MF in mdx dystrophinopathy.
    Acta Biologica Hungarica 06/2010; 61(2):168-74. · 0.50 Impact Factor
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    ABSTRACT: Duchenne muscular dystrophy is one of the most common hereditary diseases. Abnormal ion handling renders dystrophic muscle fibers more susceptible to necrosis and a rise in intracellular calcium is an important initiating event in dystrophic muscle pathogenesis. In the mdx mice, muscles are affected with different intensities and some muscles are spared. We investigated the levels of the calcium-binding proteins calsequestrin and calmodulin in the non-spared axial (sternomastoid and diaphragm), limb (tibialis anterior and soleus), cardiac and in the spared extraocular muscles (EOM) of control and mdx mice. Immunoblotting analysis showed a significant increase of the proteins in the spared mdx EOM and a significant decrease in the most affected diaphragm. Both proteins were comparable to the cardiac muscle controls. In limb and sternomastoid muscles, calmodulin and calsequestrin were affected differently. These results suggest that differential levels of the calcium-handling proteins may be involved in the pathogenesis of myonecrosis in mdx muscles. Understanding the signaling mechanisms involving Ca(2+)-calmodulin activation and calsequestrin expression may be a valuable way to develop new therapeutic approaches to the dystrophinopaties.
    International Journal of Experimental Pathology 12/2009; 91(1):63-71. · 2.04 Impact Factor
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    ABSTRACT: We evaluated the effects of long-term administration of deflazacort (DFZ) on the progression of myocardial fibrosis in mdx mice. Mdx mice (6 months old) were treated with DFZ for 15 months. Myocardial fibrosis (MF) was evaluated by histomorphometric methods, and treated and untreated mdx mice of the same age (21 months) were compared. DFZ significantly decreased MF. We conclude that long-term therapy with DFZ is effective in slowing down the progression of fibrosis in the dystrophin-deficient heart.
    Muscle & Nerve 08/2009; 40(3):466-8. · 2.31 Impact Factor
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    ABSTRACT: We evaluated the effects of deflazacort (DFZ) on muscle regeneration following Bothrops jararacussu envenoming. Tibialis anterior muscle from adult mice was injected with 80 microg of venom. Animals received DFZ during 6days. Seven and 60 days after envenoming, DFZ lead to a decrease in the total number of muscle fibers and an increase in interstitial fibrosis. We conclude that DFZ treatment may aggravate the loss of muscle mass after B. jararacussu envenoming.
    Toxicon 05/2009; 54(3):361-3. · 2.92 Impact Factor

Publication Stats

432 Citations
109.30 Total Impact Points

Institutions

  • 1997–2014
    • University of Campinas
      • • Departamento de Biologia Estrutural e Funcional
      • • Departamento de Anatomia Patologica
      • • Instituto de Biologia (IB)
      Conceição de Campinas, São Paulo, Brazil
  • 1998
    • São Paulo State University
      • Departamento de Anatomia
      São José do Rio Preto, Estado de Sao Paulo, Brazil