Cyclic Peptides to Improve Delivery and Exon Skipping of Antisense Oligonucleotides in a Mouse Model for Duchenne Muscular Dystrophy.

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.

Use of carotid compression in a patient with arteriovenous malformation.

We report a case of a patient with a high flow arteriovenous malformation (AVM)i n the orbit, who developed a severe compartment syndrome, and was successfully treated with manual carotid compressions. The patient suffered a progressive proptosis, restriction of ocular motility and decreased of the visual acuity of the right eye. Embolization had a high risk of serious complications due to fistula location, so an alternative treatment consisting in carotid compressions was prescribed. Manual carotid compression is a non-invasive alternative technique to treat AVMs in patients with high risk of embolization episodes.

Phage display screening without repetitious selection rounds.

Phage display screenings are frequently employed to identify high-affinity peptides or antibodies. Although successful, phage display is a laborious technology and is notorious for identification of false positive hits. To accelerate and improve the selection process, we have employed Illumina next generation sequencing to deeply characterize the Ph.D.-7 M13 peptide phage display library before and after several rounds of biopanning on KS483 osteoblast cells. Sequencing of the naive library after one round of amplification in bacteria identifies propagation advantage as an important source of false positive hits. Most important, our data show that deep sequencing of the phage pool after a first round of biopanning is already sufficient to identify positive phages. Whereas traditional sequencing of a limited number of clones after one or two rounds of selection is uninformative, the required additional rounds of biopanning are associated with the risk of losing promising clones propagating slower than nonbinding phages. Confocal and live cell imaging confirms that our screen successfully selected a peptide with very high binding and uptake in osteoblasts. We conclude that next generation sequencing can significantly empower phage display screenings by accelerating the finding of specific binders and restraining the number of false positive hits.

Acute Lung Toxicity After Intralesional Bleomycin Sclerotherapy.

Bleomycin has progressively been used to treat low-flow vascular malformations in children. No significant systemic side effects have been reported in large series after low doses, but some authors are still concerned about its use. We report a case of a severe acute lung toxicity after a low dose of a second bleomycin intralesional injection in a 5-year-old girl. She had no risk factors and presented a cervical low-flow venous malformation. Twenty-four hours after this second administration, she presented with fever and respiratory distress. A chest radiograph showed bilateral opacities and computerized tomography revealed extensive and diffuse lung ground-glass opacities. The patient started to receive intravenous methylprednisolone, but she experienced progressively increased dyspnea, and montelukast was added. She improved and was discharged from the hospital without oxygen support, with montelukast and prednisolone for tapering doses during months. Five months after onset, the patient is developing well, is active, and walks and talks without dyspnea. A new low-dose computed tomography shows improvement in radiologic findings. This is the second case of pulmonary toxicity observed in a child after bleomycin intralesional administration, and the first reported after the lowest dose of this drug to date (7 mg: 0.28 mg/kg; 10 U: 0.4 U/kg). A delay in the diagnosis and treatment of this complication can be fatal. Any physician who treats these patients must be alert and consider this complication in children with respiratory symptoms after bleomycin sclerotherapy. Early detection of pulmonary toxicity would allow prompt therapy and could avoid pulmonary damage.

Feasibility of SPECT-CT Imaging to Study the Pharmacokinetics of Antisense Oligonucleotides in a Mouse Model of Duchenne Muscular Dystrophy.

Antisense oligonucleotides (AONs) are promising candidates for treatment of Duchenne muscular dystrophy (DMD), a severe and progressive disease resulting in premature death. However, more knowledge on the pharmacokinetics of new AON drug candidates is desired for effective application in the clinic. We assessed the feasibility of using noninvasive single-photon emission computed tomography-computed tomography (SPECT-CT) imaging to determine AON pharmacokinetics in vivo. To this end, a 2'-O-methyl phosphorothioate AON was radiolabeled with 123I or 111In, and administered to mdx mice, a rodent model of DMD. SPECT-CT imaging was performed to determine AON tissue levels, and the results were compared to data obtained with invasive analysis methods (scintillation counting and a ligation-hybridization assay). We found that SPECT-CT data obtained with 123I-AON and 111In-AON were qualitatively comparable to data derived from invasive analytical methods, confirming the feasibility of using SPECT-CT analysis to study AON pharmacokinetics. Notably, also AON uptake in skeletal muscle, the target tissue in DMD, could be readily quantified using SPECT-CT imaging, which was considered a particular challenge in mice, due to their small size. In conclusion, our results demonstrate that SPECT-CT imaging allows for noninvasive characterization of biodistribution and pharmacokinetics of AONs, thereby enabling quantitative comparisons between different radiolabeled AON drug candidates and qualitative conclusions about the corresponding unmodified parent AONs. This technology may contribute to improved (pre)clinical drug development, leading to drug candidates with optimized characteristics in vivo.

Intracellular Distribution and Nuclear Activity of Antisense Oligonucleotides After Unassisted Uptake in Myoblasts and Differentiated Myotubes In Vitro.

Clinical efficacy of antisense oligonucleotides (AONs) for the treatment of neuromuscular disorders depends on efficient cellular uptake and proper intracellular routing to the target. Selection of AONs with highest in vitro efficiencies is usually based on chemical or physical methods for forced cellular delivery. Since these methods largely bypass existing natural mechanisms for membrane passage and intracellular trafficking, spontaneous uptake and distribution of AONs in cells are still poorly understood. Here, we report on the unassisted uptake of naked AONs, so-called gymnosis, in muscle cells in culture. We found that gymnosis works similarly well for proliferating myoblasts as for terminally differentiated myotubes. Cell biological analyses combined with microscopy imaging showed that a phosphorothioate backbone promotes efficient gymnosis, that uptake is clathrin mediated and mainly results in endosomal-lysosomal accumulation. Nuclear localization occurred at a low level, but the gymnotically delivered AONs effectively modulated the expression of their nuclear RNA targets. Chloroquine treatment after gymnotic delivery helped increase nuclear AON levels. In sum, we demonstrate that gymnosis is feasible in proliferating and non-proliferating muscle cells and we confirm the relevance of AON chemistry for uptake and intracellular trafficking with this method, which provides a useful means for bio-activity screening of AONs in vitro.

Confirmation of the D configuration of the 2-substituted arabinitol 1-phosphate residue in the capsular polysaccharide from Streptococcus pneumoniae Type 17F.

The absolute configuration of the 2-substituted arabinitol 1-phosphate residue present in the repeating unit of the capsular polysaccharide (CPS) from Streptococcus pneumoniae Type 17F is confirmed as D, based on a comparison of proton and carbon chemical shifts in a synthetic oligosaccharide and in an oligosaccharide derived from the CPS by degradation.

Peptide conjugation of 2'-O-methyl phosphorothioate antisense oligonucleotides enhances cardiac uptake and exon skipping in mdx mice.

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.

[Acute vertebral fracture and vertebral reinforcement techniques]. / Fractura vertebral aguda y técnicas de refuerzo vertebral.

The high incidence of fractures by fragility and, especially of the vertebral fractures in osteoporotic postmenopausal women, forces us to approach this subject once more. In this manuscript epidemiological data that indicates the magnitude of the problem will be updated. Treatment alternatives to decrease back pain produced by vertebral fracture are will be reviewed, and the prevention of the occurrence of new osteoporotic fractures of any type, through the administration of suitable antiresorptive and bone-forming pharmacological agents to increase bone mineral density will also be addressed. In some patients with painful vertebral compression fractures it is possible obtain an analgesic effect by percutaneous vertebroplasty or by kiphoplasty using polymethylmetacrilate cement or calcium- phosphate cement, injected into vertebral bodies.

Synthesis and antibody-binding studies of a series of parasite fuco-oligosaccharides.

Complex multifucosylated oligosaccharides are structural elements of glycoprotein and glycolipid subsets of larval, egg, and adult stages of Schistosoma, the parasitic worms that cause schistosomiasis, a serious disease affecting more than 200 million people in the tropics. The fucosylated structures are thought to play an important role in the immunology of schistosomiasis. Defined schistosomal oligosaccharides that enable immunological studies are difficult to obtain from natural sources. Therefore, we have chemically synthesized spacer-linked GlcNAc, Fucalpha1-3GlcNAc, Fucalpha1-2Fucalpha1-3GlcNAc, and Fucalpha1-2Fucalpha1-2Fucalpha1-3GlcNAc. This series of linear oligosaccharides was used to screen a library of anti-schistosome monoclonal antibodies by surface plasmon resonance spectroscopy. Interestingly, the reactive antibodies could be grouped according to their specificity for the different oligosaccharides tested, showing that these oligosaccharides form different immunological entities based on the number and linkage of the fucose residues. Subsequently, the thus defined monoclonal antibodies were used to visualize the expression of the corresponding oligosaccharide epitopes by adult Schistosoma mansoni worms.

Transglycosidase activity of chitotriosidase: improved enzymatic assay for the human macrophage chitinase.

Chitotriosidase is a chitinase that is massively expressed by lipid-laden tissue macrophages in man. Its enzymatic activity is markedly elevated in serum of patients suffering from lysosomal lipid storage disorders, sarcoidosis, thalassemia, and visceral Leishmaniasis. Monitoring of serum chitotriosidase activity in Gaucher disease patients during progression and therapeutic correction of their disease is useful to obtain insight in changes in body burden on pathological macrophages. However, accurate quantification of chitotriosidase levels by enzyme assay is complicated by apparent substrate inhibition, which prohibits the use of saturating substrate concentrations. We have therefore studied the catalytic features of chitotriosidase in more detail. It is demonstrated that the inhibition of enzyme activity at excess substrate concentration can be fully explained by transglycosylation of substrate molecules. The potential physiological consequences of the ability of chitotriosidase to hydrolyze as well as transglycosylate are discussed. The novel insight in transglycosidase activity of chitotriosidase has led to the design of a new substrate molecule, 4-methylumbelliferyl-(4-deoxy)chitobiose. With this substrate, which is no acceptor for transglycosylation, chitotriosidase shows normal Michaelis-Menten kinetics, resulting in major improvements in sensitivity and reproducibility of enzymatic activity measurements. The novel convenient chitotriosidase enzyme assay should facilitate the accurate monitoring of Gaucher disease patients receiving costly enzyme replacement therapy.

Fractura vertebral aguda y técnicas de refuerzo vertebral / Acute vertebral fracture and vertebral reinforcement techniques

La alta incidencia de las fracturas por fragilidad y especialmente de las fracturas vertebrales (FV) en mujeres con osteoporosis posmenopáusica obliga a abordar este tema una y otra vez. En este manuscrito se actualizan los datos epidemiológicos que indican la magnitud del problema y se revisan alternativas de tratamiento farmacológico, tanto para disminuir el dolor producido por la FV como para prevenir la presentación de nuevas fracturas osteoporóticas de cualquier tipo, indicando los agentes antirresortivos y osteoformadores disponibles actualmente. En los casos de FV por compresión, en las que el tratamiento farmacológico habitual no produce mejoría del dolor y siempre que no existan contraindicaciones, puede ser muy apropiado realizar vertebroplastia o cifoplastia (AU)

The high incidence of fractures by fragility and, especially of the vertebral fractures in osteoporotic postmenopausal women, forces us to approach this subject once more. In this manuscript epidemiological data that indicates the magnitude of the problem will be updated. Treatment alternatives to decrease back pain produced by vertebral fracture are will be reviewed, and the prevention of the occurrence of new osteoporotic fractures of any type, through the administration of suitable antiresorptive and bone-forming pharmacological agents to increase bone mineral density will also be addressed. In some patients with painful vertebral compression fractures it is possible obtain an analgesic effect by percutaneous vertebroplasty or by kiphoplasty using polymethylmetacrilate cement or calcium- phosphate cement, injected into vertebral bodies (AU)