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Background The Questionnaire on Pain caused by Spasticity (QPS) is a modular patient- and observer-reported outcome measure of spasticity-related pain (SRP) in children with cerebral palsy (CP). Originally developed for an English-speaking population, we conducted a psychometric validation of a recently developed Chinese language version of the QPS. Methods This was a prospective, observational study involving 137 children/adolescents with CP and upper and/or lower limb spasticity and their parents at three sites in China. Six QPS modules were used, three each for upper and lower limb SRP assessment: a patient self-report module; an interviewer-administered module used by site staff based on the cognitive, communicative, and motor abilities of a patient; and a parent/caregiver module administered for all children as an observer-reported outcome to complement the patient-reported outcome. If no assessment by the patient was possible because of age or cognitive impairments, only the parent/caregiver module was completed. Two visits with a 3-week interval provided data to evaluate and establish administrative ease of use, scoring of the QPS (factor analyses, Rasch analyses), reliability (Cronbach’s α, intraclass correlation coefficient), validity (correlations with quality of life [PedsQL™], motor impairment [Gross Motor Function Classification System, Gross Motor Function Measure-66, Manual Ability Classification System], and spasticity [Ashworth Scale, Modified Tardieu Scale]). Results For most children, clinic staff reported no difficulties associated with general QPS use or deciding which module to use. Children (and parents) who reported more demanding activities also reported higher levels of associated SRP (or observed SRP behavior). Activity-related SRP items were combined for a total QPS score. Cronbach’s α was low for child self-report, but was acceptable for interviewer-administered and parent reports on SRP. Test–retest reliability was high for all modules. Moderate–strong associations were frequently seen between QPS and quality of life, and were particularly strong in the child self-report group. Relatively weak associations were observed between QPS and motor impairment and spasticity. Conclusions This first study was successful in providing initial evidence for the psychometric properties. Clinic staff were able to administer the QPS modules easily, and both children and parents were able to complete the designated QPS appropriately. Electronic supplementary material The online version of this article (10.1186/s12955-017-0804-8) contains supplementary material, which is available to authorized users.

The recently cloned ecto-ATPase and ecto-apyrase (ecto-ATP diphosphohydrolase) are plasma-membrane-bound enzymes responsible for the extracellular degradation of nucleoside 5'-triphosphates and nucleoside 5'-diphosphates. We expressed the rat-derived enzymes in CHO cells to compare their molecular and functional properties. Sequence-specific polyclonal antibodies differentiate between the two proteins and reveal identical molecular masses of 70-80 kDa. Both enzymes are stimulated by either Ca2+ or Mg2+ and reveal a broad substrate specificity towards purine and pyrimidine nucleotides. Whereas ecto-apyrase hydrolyzes nucleoside 5'-diphosphates at a rate approximately 20-30% lower than nucleoside-5'-triphosphates, ecto-ATPase hydrolyzes nucleoside-5'-diphosphates only to a marginal extent. The sensitivity of the two enzymes to the inhibitors of P2 receptors suramin, PPADS and reactive blue differs. Hydrolysis of ATP by ecto-ATPase leads to the accumulation in the medium of extracellular ADP as an intermediate product, whereas ecto-apyrase dephosphorylates ATP directly to AMP. Our results suggest that previous data describing extracellular hydrolysis of ATP by a variety of intact cellular systems with unidentified ecto-nucleotidases may be explained by the coexpression of ecto-ATPase and ecto-apyrase.

ATP, an important signalling substance in the central nervous system, is hydrolysed to adenosine via a surface-located enzyme cascade. The final hydrolysis step from AMP to adenosine is catalysed by 5'-nucleotidase, a GPI-anchored surface protein. 5'-Nucleotidase is transiently expressed on developing neurones. An antisense oligonucleotide that suppresses the synthesis of 5'-nucleotidase inhibits NGF-induced neurite formation and survival in PC12 cells and cultures of cerebellar granule cells. The inhibitory effect of the antisense oligonucleotide can be completely or partially relieved by addition of soluble 5'-nucleotidase or of nucleosides to the medium. Our results suggest that 5'-nucleotidase is essential for the differentiation and survival of neural cells and represents an important and critical step in the hydrolysis cascade of extracellular nucleotides.

Ecto-5′-nucleotidase catalyses the hydrolysis of AMP at the surface of a variety of cells whereas it is absent from others. In addition to its catalytic activity, a function in neural development and also its interaction with extracellular matrix proteins has been reported. In order to further elucidate the biological function of ecto-5′-nucleotidase we have investigated the effect of 5′-nucleotidase on nerve growth factor-induced differentiation of PC12 cells. Furthermore, we compared the effect of an inhibitory versus a non-inhibitory monospecific antibody against the enzyme on neuritic differentiation and survival of PC12 cells that constitutively express the enzyme. When coverslips are coated with the soluble form of ecto-5′-nucleotidase in addition to collagen, there is a considerable increase in nerve growth factor-induced neurite length during the first 24 h of culture. Addition of an antibody to a culture medium that inhibits 5′-nucleotidase activity to 33% of control values dramatically reduces the number of neurites per cell within 3 days of culture. The cells round up, cluster and eventually die. On the contrary, another antibody that had no significant effect on enzyme activity affected neither nerve growth factor-induced neurite formation nor survival of PC12 cells. Addition of adenosine (200 nM, 10 or 20 μM) to the culture medium did not influence PC12 cell differentiation. The effects induced by the inhibitory antibody could be only partially prevented by simultaneous application of adenosine. Our results suggest that 5′-nucleotidase is essential for nerve growth factor-induced neurite outgrowth and survival of PC12 cells. The results obtained cannot be simply explained on the basis of the availability and extracellular production of adenosine.

5′-Nucleotidase hydrolyzes 5′-mononucleotides to their nucleosides but is also thought to have a function in neuronal differentiation and synapse formation. The distribution of the enzyme, a glycosyl-phosphatidylinositol-anchored sialoglycoprotein, was investigated in PC12 cells using immunofluorescence microscopy. 5′-Nucleotidase was located both in intracellular compartments and at the cell surface. There was no principal difference in the cellular distribution between undifferentiated cells and after neuritogenic differentiation by nerve growth factor. Intracellularly, 5′-nucleotidase often revealed a sickle-shaped perinuclear distribution and a dotted pattern throughout the cytoplasm, including that of neurites and growth cones. The intracellular distribution was clearly different from that of the synaptic vesicle protein synaptophysin. However, the dotted fluorescence resembled that obtained after uptake of the endosomal marker acridine orange. 5′-Nucleotidase was present on the entire cell surface including all neurites formed after differentiation. There was no increase in 5′-nucleotidase fluorescence at synapse-like contacts between the tips of neurites and other PC12 cells. Surfacelocated 5′-nucleotidase could no longer be detected after the application of glycosyl-phosphatidylinositol-specific phospholipase C to cultured cells. This treatment did not affect PC12 cell differentiation. Our results thus reveal 5′-nucleotidase both at the surface and within organelles and suggest that PC12 cells may be used as a model system for the study of the physiological function of 5′-nucleotidase in neural cells.