Recombinant Mouse PAP Has pH-Dependent Ectonucleotidase Activity and Acts through A1-Adenosine Receptors to Mediate Antinociception

Prostatic acid phosphatase (PAP) is expressed in nociceptive neurons and functions as an ectonucleotidase. When injected intraspinally, the secretory isoforms of human and bovine PAP protein have potent and long-lasting antinociceptive effects that are dependent on A1-adenosine receptor (A1R) activation. In this study, we purified the secretory isoform of mouse (m)PAP using the baculovirus expression system to determine if recombinant mPAP also had antinociceptive properties. We found that mPAP dephosphorylated AMP, and to a much lesser extent, ADP at neutral pH (pH 7.0). In contrast, mPAP dephosphorylated all purine nucleotides (AMP, ADP, ATP) at an acidic pH (pH 5.6). The transmembrane isoform of mPAP had similar pH-dependent ectonucleotidase activity. A single intraspinal injection of mPAP protein had long-lasting (three day) antinociceptive properties, including antihyperalgesic and antiallodynic effects in the Complete Freund's Adjuvant (CFA) inflammatory pain model. These antinociceptive effects were transiently blocked by the A1R antagonist 8-cyclopentyl-1, 3-dipropylxanthine (CPX), suggesting mPAP dephosphorylates nucleotides to adenosine to mediate antinociception just like human and bovine PAP. Our studies indicate that PAP has species-conserved antinociceptive effects and has pH-dependent ectonucleotidase activity. The ability to metabolize nucleotides in a pH-dependent manner could be relevant to conditions like inflammation where tissue acidosis and nucleotide release occur. Lastly, our studies demonstrate that recombinant PAP protein can be used to treat chronic pain in animal models

Congruence between nurses' and patients' assessment of postoperative pain: a literature review

Postoperative pain remains poorly managed for many patients. Effective pain management begins with accurate pain assessment, with patient self-reporting considered the most accurate measure of pain. This literature review aimed to identify how congruent nurses' assessments of pain were with patients' self-reporting. A search identified six observational studies and one quasi-experimental study that met the inclusion criteria. The findings from these studies were summarised under two themes: nurses' underestimation of patients' pain and nurses' knowledge and understanding of pain assessment. Some nurses' pain management knowledge was deemed inadequate, with evidence of negative attitudes towards managing pain in certain groups of patients. Educational interventions have so far had limited impact on correcting the ethical and professional problem of inadequate pain relief in many patients postoperatively. Randomised controlled trials are required to identify effective education interventions that can contribute to ending this avoidable suffering