Enzyme replacement therapy in the mouse model of Pompe disease

Deficiency of acid alpha-glucosidase (GAA) results in widespread cellular deposition of lysosomal glycogen manifesting as myopathy and cardiomyopathy. When GAA-/- mice were treated with rhGAA (20 mg/kg/week for up to 5 months), skeletal muscle cells took up little enzyme compared to liver and heart. Glycogen reduction was less than 50%, and some fibers showed little or no glycogen clearance. A dose of 100 mg/kg/week resulted in approximately 75% glycogen clearance in skeletal muscle. The enzyme reduced cardiac glycogen to undetectable levels at either dose. Skeletal muscle fibers with residual glycogen showed immunoreactivity for LAMP-1/LAMP-2, indicating that undigested glycogen remained in proliferating lysosomes. Glycogen clearance was more pronounced in type 1 fibers, and histochemical analysis suggested an increased mannose-6-phosphate receptor immunoreactivity in these fibers. Differential transport of enzyme into lysosomes may explain the strikingly uneven pattern of glycogen removal. Autophagic vacuoles, a feature of both the mouse model and the human disease, persisted despite glycogen clearance. In some groups a modest glycogen reduction was accompanied by improved muscle strength. These studies suggest that enzyme replacement therapy, although at much higher doses than in other lysosomal diseases, has the potential to reverse cardiac pathology and to reduce the glycogen level in skeletal muscle.     

Opposing effects on immune function and skin barrier regulation by the proteasome inhibitor bortezomib in an allergen‐induced eczema model

Proteasome inhibition (PI) has been reported to interfere with antibody‐driven autoimmune diseases. The impact of PI on the allergic immune response and on skin diseases like atopic dermatitis (AD) has not been thoroughly explored, however. Here, we examined whether the PI bortezomib interferes with the allergic immune response and the severity of AD by using an established mouse model of allergen‐driven dermatitis, to which bortezomib was applied after the establishment of systemic sensitization to ovalbumin. The treatment indeed resulted in a remarkable decrease in total and allergen‐specific plasma cells/antibody‐secreting cells, as evidenced by flow cytometry and ELISpot, respectively. This was accompanied by rapid reductions in serum antibody titres, including a prominent reduction of the IgE isotype. CD4+ and CD8+ cells were greatly diminished in lesional skin on immunohistological staining. The impressive effects at the level of immune modulation did not result in any improvement in the eczema, however. Following up on this unexpected result, we found that the skin itself was susceptible to bortezomib, by which it was instructed to lower the expression of critical skin barrier genes, especially transglutaminase‐1 and filaggrin. Together, bortezomib eliminates plasma cells and decreases immunoglobulin responses, including allergenic IgE. Although anti‐inflammatory effects are detectable in the skin, counter‐regulatory effects from PI on resident skin cells likely undermine improvement in the eczema. These results caution against the therapeutic use of bortezomib for inflammatory skin disorders, which are characterized by inherently impaired barrier function, especially AD.     

Abiotrophia Endocarditis in Children with No Underlying Heart Disease: A Rare but a Virulent Organism

Infective endocarditis is extremely rare in children with structurally normal hearts. The most common etiological agents are staphylococcal and streptococcal species. Nutritionally variant streptococci also classified as Abiotrophia species are a group of fastidious organisms that account for only 5% to 6% of all cases of culture‐negative infective endocarditis. Only seven cases of Abiotrophia infective endocarditis have been previously reported in children with no underlying structural heart disease. We report two cases of Abiotrophia infective endocarditis in children without any predisposing factors. Both patients presented with nonspecific symptoms leading to delay in diagnosis. While bacteriological clearance was achieved in both cases, both had a complicated course including development of brain mycotic aneurysms, splenic infarction, renal failure, and irreversible damage to the mitral valve. Both patients required surgical removal of the native mitral valve and replacement. We also present review of seven cases with similar diagnosis published previously in literature and highlight important differences. Our cases highlight special challenges in management of Abiotrophia endocarditis in pediatric patients. As the organism may not be isolated in routine culture media, may present with atypical clinical symptoms and may have a complicated course even without antibiotic failure, a high index of suspicion should be maintained in children with subacute symptoms even with no underlying structural cardiac disease.     

Functional roles of the phosphatidylinositol 3-kinases (PI3Ks) signaling in the mammalian ovary

The proinflammatory status of adipose tissue has been linked to the metabolic and cardiovascular consequences of obesity. Human adipose cells express the calcium sensing receptor (CaSR), and its expression is elevated in inflammatory states, such as that associated with obesity. Given the CaSR's association with inflammation in other tissues, we evaluated its role elevating the adipose expression of inflammatory factors. The CaSR activation by the calcimimatic cinacalcet (5μM) in adipose tissue and in vitro cultured LS14 adipose cells elicited an elevation in the expression of the proinflammatory cytokines IL6, IL1β, TNFα, and the chemoattractant CCL2. This was in part reverted by SN50, an inhibitor of the inflammatory mediator nuclear factor kappa B (NFκB). Our observations suggest that CaSR activation elevates cytokine and chemokine production, partially mediated by NFκB. These findings support the relevance of the CaSR in the pathophysiology of obesity-induced adipose tissue dysfunction, with an interesting potential for pharmacological manipulation.     

Purification and properties of hyaluronidase from Hippasa partita (funnel web spider) venom gland extract.

Spider venom is a complex mixture of protein and peptide toxins. Hyaluronidase a 'spreading factor' has not been studied extensively in spider venom. In this paper, we describe the purification and characterization of a hyaluronidase from Hippasa partita venom gland extract. Hyaluronidase (HPHyal) has been purified by the successive chromatography on a Sephadex G-100 and on CM-Sephadex C-25 columns. HPHyal has been purified to an extent of about approximately 20-folds. The molecular mass was found to be 42.26 kDa by matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry. HPHyal was optimally active at pH 5.8 at 37 degrees C and in the presence of 300 mM NaCl in the reaction mixture. HPHyal showed absolute specificity for hyaluronan and belongs to neutral active group of enzymes. HPHyal revealed single-precipitin line, while venom gland extract revealed multiple bands in Western blotting with the antiserum prepared against venom gland extract. HPHyal indirectly potentiates the myotoxicity of VRV-PL-VIII myotoxin and also the hemorrhagic potency of hemorrhagic complex-I. Cations, Na(+) and K(+) enhanced the activity and chloride ions do not have any effect while, divalent cations, inhibited the enzyme activity.     

Nicotine gum-induced atrial fibrillation

A 39-year-old man with no prior history of atrial fibrillation was hospitalized with atrial fibrillation and a rapid ventricular rate. For the 7 months before presentation, he had been chewing nicotine polacrilex gum on his own. The week he first developed palpitations, he was chewing more than 1 piece of nicotine Polacrilex gum per hour during work. His diagnostic work-up during hospitalization found no cause for atrial fibrillation. He was cardioverted to sinus rhythm. At 6-month follow-up, he had not renewed chewing nicotine polacrilex gum, was in sinus rhythm, and had no history of palpitations. The temporal relation between more frequent gum usage and the excessive consumption of nicotine polacrilex chewing gum with a probable high serum nicotine level at the time the patient developed his first episode of atrial fibrillation suggests a causal relationship.