Dysregulation of extracellular matrix and Lysyl Oxidase in Ehlers-Danlos syndrome type IV skin fibroblasts.

Background: Ehlers-Danlos syndrome Type IV (aka Vascular Ehlers Danlos, or vEDS) is a dominantly inherited mutation in the Collagen 3A1 gene (COL3A1). The disease is characterized by tissue friability and age-related susceptibility to arterial aneurysm, dissection and rupture as well as uterine and bowl tears. These clinical manifestations result in major surgical intervention and decreased life expectancy.

Quantitative bioanalysis of strontium in human serum by inductively coupled plasma-mass spectrometry.

Aim: A bioanalytical method using inductively-coupled plasma-mass spectrometry to measure endogenous levels of strontium in human serum was developed and validated.

Results & Methodology: This article details the experimental procedures used for the method development and validation thus demonstrating the application of the inductively-coupled plasma-mass spectrometry method for quantification of strontium in human serum samples. The assay was validated for specificity, linearity, accuracy, precision, recovery and stability.

Biomarker analysis of Morquio syndrome: identification of disease state and drug responsive markers.

Background: This study was conducted to identify potential biomarkers that could be used to evaluate disease progression and monitor responses to enzyme replacement therapy (ERT) in patients with mucopolysaccharidosis (MPS) IVA.

Methods: Levels of 88 candidate biomarkers were compared in plasma samples from 50 healthy controls and 78 MPSIVA patients not receiving ERT to test for significant correlations to the presence of MPSIVA. MPSIVA samples were also tested for correlations between candidate biomarkers and age, endurance, or urinary keratin sulfate (KS) levels.

Validation of an LC-MS/MS assay for detecting relevant disaccharides from keratan sulfate as a biomarker for Morquio A syndrome.

Background: Mucopolysaccharidosis IVA (MPS IVA, Morquio A syndrome) is an inherited lysosomal storage disease caused by deficiency of N-acetylgalactosamine-6-sulfatase (GALNS), an enzyme required for stepwise degradation of keratan sulfate (KS). We have developed a selective, sensitive, accurate and precise LC-MS/MS assay for the KS-derived disaccharides Galβ1-4GlcNAc(6S) and Gal(6S)β1-4GlcNAc(6S) in human urine and plasma using keratanase II digestion.

Results: Mean accuracy was 96-106% in urine and 97-108% in plasma.

Relative bioavailability of sapropterin from intact and dissolved sapropterin dihydrochloride tablets and the effects of food: a randomized, open-label, crossover study in healthy adults.

Background: Phenylketonuria (PKU) is an autosomal recessive metabolic disorder characterized by hyperphenylalaninemia in association with neurocognitive and neuromotor impairment. Sapropterin dihydrochloride (hereafter referred to as sapropterin) administered orally as dissolved tablets is approved by the US Food and Drug Administration for hyperphenylalaninemia in patients with tetrahydrobiopterin responsive PKU.

Objectives: This study compared the relative oral bioavailability of sapropterin when administered as intact and dissolved tablets.

Detection of tetrahydrobiopterin by LC-MS/MS in plasma from multiple species.

Background: Tetrahydrobiopterin (BH4) is a naturally occurring pteridine and cofactor for a variety of enzymes, including phenylalanine-4-hydroxylase, nitric oxide synthetase and glyceryl ether monooxygenase. BH4 is readily oxidized to dihydrobiopterin and biopterin (B), however only BH4 can provide proper cofactor functions. BH4 is the active ingredient in Kuvan™ for the treatment of phenylketonuria.

Pharmacokinetics of sapropterin in patients with phenylketonuria.

Background And Objective: Untreated phenylketonuria is characterized by neurocognitive and neuromotor impairment, which result from elevated blood phenylalanine concentrations. To date, the recommended management of phenylketonuria has been the use of a protein-restricted diet and the inclusion of phenylalanine-free protein supplements; however, this approach is often associated with poor compliance and a suboptimal clinical outcome. Sapropterin dihydrochloride, herein referred to as sapropterin, a synthetic formulation of 6R-tetrahydrobiopterin (6R-BH4), has been shown to be effective in reducing blood phenylalanine concentrations in patients with phenylketonuria.

Comparison of neutralizing antibody assays for receptor binding and enzyme activity of the enzyme replacement therapeutic Naglazyme (galsulfase).

Most patients receiving Naglazyme (galsulfase, rhASB) enzyme replacement therapy for mucopolysaccharidosis type VI develop an antibody response. To evaluate the impact of this response, two in vitro neutralizing antibody (NAb) assays were developed based on the two steps of the mechanism of action. Neutralization of enzyme activity was detected by inhibition of rhASB cleavage of a fluorogenic substrate.

Development, validation, and clinical implementation of an assay to measure total antibody response to naglazyme (galsulfase).

Naglazyme (galsulfase, rhASB) was developed as enzyme replacement therapy for mucopolysaccharidosis type VI. Naglazyme generated an IgG antibody response in most patients. To better characterize Naglazyme immunogenicity, a solution phase bridged immunoassay was developed to measure total antibody response regardless of isotype.

NF-kappaB/Rel regulates inhibitory and excitatory neuronal function and synaptic plasticity.

Changes in synaptic plasticity required for memory formation are dynamically regulated through opposing excitatory and inhibitory neurotransmissions. To explore the potential contribution of NF-kappaB/Rel to these processes, we generated transgenic mice conditionally expressing a potent NF-kappaB/Rel inhibitor termed IkappaBalpha superrepressor (IkappaBalpha-SR). Using the prion promoter-enhancer, IkappaBalpha-SR is robustly expressed in inhibitory GABAergic interneurons and, at lower levels, in excitatory neurons but not in glia.

Targeting of the receptor protein tyrosine phosphatase beta with a monoclonal antibody delays tumor growth in a glioblastoma model.

The receptor protein tyrosine phosphatase beta (RPTPbeta) is a functional biomarker for several solid tumor types. RPTPbeta expression is largely restricted to the central nervous system and overexpressed primarily in astrocytic tumors. RPTPbeta is known to facilitate tumor cell adhesion and migration through interactions with extracellular matrix components and the growth factor pleiotrophin.

Discoidin domain receptor-1a (DDR1a) promotes glioma cell invasion and adhesion in association with matrix metalloproteinase-2.

Invasion of glioma cells involves the attachment of invading tumor cells to extracellular matrix (ECM), disruption of ECM components, and subsequent cell penetration into adjacent brain structures. Discoidin domain receptor 1 (DDR1) tyrosine kinases constitute a novel family of receptors characterized by a unique structure in the ectodomain (discoidin-I domain). These cell surface receptors bind to several collagens and facilitate cell adhesion.

FAS associated phosphatase (FAP-1) blocks apoptosis of astrocytomas through dephosphorylation of FAS.

Astrocytomas are the most common primary tumor of the adult human central nervous system. Despite efforts to develop more effective clinical treatment strategies, median survival time for patients with the most severe form of astrocytoma, glioblastoma multiforme (GBM), remains about one year. Astrocytomas are resistant to cytotoxic therapy in general and radiation therapy in particular, greatly limiting treatment options.

Functional comparison of long and short splice forms of RPTPbeta: implications for glioblastoma treatment.

The receptor protein tyrosine phosphatase beta (RPTPbeta/PTPzeta) is overexpressed in glioblastoma tumors and plays a functional role in tumor cell migration and adhesion. Glioblastomas express at least three splice variants of RPTPbeta, including long and short receptor forms and a secreted chondroitin sulfate proteoglycan called phosphacan. Here we explore the differences in the expression pattern and function of long RPTPbeta and short RPTPbeta.

GPR56 is a GPCR that is overexpressed in gliomas and functions in tumor cell adhesion.

GPR56 (also known as TM7XN1) is a newly discovered orphan G-protein-coupled receptor (GPCR) of the secretin family that has a role in the development of neural progenitor cells and has been linked to developmental malformations of the human brain. GPR56 diverges from other secretin-like family members in that it has an extremely large N-terminal extracellular region (381 amino acids) and contains a novel feature among this new subclass, consisting of four cysteine residues that define a GPCR proteolytic site (GPS motif) located just before the first transmembrane spanning domain. The rest of the amino-terminal domain contains a large number of possible N- and O-linked glycosylation sites similar to mucin-like proteins.