Partial Purification of Histaminase from Guinea-Pig Liver by Gel-Filtration at High Temperature

Histaminase was partially purified by Sephadex G-200 gel filtration at high temperature. Guinea pig liver histaminase was extracted with heparin. The extract was fractionated by Sephadex G-200 gel filtration at 4°C. In the fractions containing histaminase, 7 dense and 2 faint protein bands were detected on SDS-gel electrophoresis. Further, fractionation of this sample by Sephadex G-200 gel filtration at 55°C markedly decreased the number of bands, i.e. only 1 dense and 2 faint bands were observed in the fractions in which histaminase activity was detected, and the enzyme activity was increased by approximately ten times. The results suggest that gel filtration at high temperature may be useful for partial purification of histaminase.This work was supported by Scientific Research Grant from the Japanese Ministry of Education (B, No. 58480264)

Activation of cytosolic phospholipase A2 in dorsal root ganglion neurons by Ca2+/calmodulin-dependent protein kinase II after peripheral nerve injury

<p>Abstract</p> <p>Background</p> <p>Peripheral nerve injury leads to a persistent neuropathic pain state in which innocuous stimulation elicits pain behavior (tactile allodynia), but the underlying mechanisms have remained largely unknown. We have previously shown that spinal nerve injury induces the activation of cytosolic phospholipase A₂(cPLA₂) in injured dorsal root ganglion (DRG) neurons that contribute to tactile allodynia. However, little is known about the signaling pathway that activates cPLA₂after nerve injury. In the present study, we sought to determine the mechanisms underlying cPLA₂activation in injured DRG neurons in an animal model of neuropathic pain, focusing on mitogen-activated protein kinases (MAPKs) and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII).</p> <p>Results</p> <p>Pharmacological inhibition of either p38 or extracellular signal-regulated kinase (ERK) in the injured DRG, which led to suppression of the development of tactile allodynia, did not affect cPLA₂phosphorylation and translocation after nerve injury. By contrast, a CaMKII inhibitor prevented the development and expression of nerve injury-induced tactile allodynia and reduced both the level of cPLA₂phosphorylation and the number of DRG neurons showing translocated cPLA₂in response to nerve injury. Applying ATP to cultured DRG neurons increased the level of both phosphorylated cPLA₂and CaMKII in the vicinity of the plasma membrane and caused physical association of these two proteins. In addition, ATP-stimulated cPLA₂and CaMKII phosphorylation were inhibited by both a selective P2X₃R/P2X₂₊₃R antagonist and a nonselective voltage-dependent Ca²⁺channel (VDCC) blocker.</p> <p>Conclusion</p> <p>These results suggest that CaMKII, but not MAPKs, has an important role in cPLA₂activation following peripheral nerve injury, probably through P2X₃R/P2X₂₊₃R and VDCCs in primary afferent neurons.</p

A case of pancreatic acinar cell carcinoma metastatic to skin

We report a rare case of pancreatic acinar cell carcinoma with widespread metastases in a 68-year-old woman who presented with subcutaneous nodules as the initial symptom. Computed tomography showed a pancreatic mass with hepatic tumors and enlarged lymph nodes besides ring-enhanced subcutaneous nodules. Magnetic resonance diffusionweighted imaging detected the presence of lesions in other organs. Histological analysis of a colonic polypoid lesion revealed carcinoma with endocrine and acinar differentiation compatible with pancreatic origin. Regrettably, she died of a cerebral infarction without any treatment, and autopsy findings confirmed our diagnosis

Role of PAF Receptor in Proinflammatory Cytokine Expression in the Dorsal Root Ganglion and Tactile Allodynia in a Rodent Model of Neuropathic Pain

BACKGROUND: Neuropathic pain is a highly debilitating chronic pain following damage to peripheral sensory neurons and is often resistant to all treatments currently available, including opioids. We have previously shown that peripheral nerve injury induces activation of cytosolic phospholipase A(2) (cPLA(2)) in injured dorsal root ganglion (DRG) neurons that contribute to tactile allodynia, a hallmark of neuropathic pain. However, lipid mediators downstream of cPLA(2) activation to produce tactile allodynia remain to be determined. PRINCIPAL FINDINGS: Here we provide evidence that platelet-activating factor (PAF) is a potential candidate. Pharmacological blockade of PAF receptors (PAFRs) reduced the development and expression of tactile allodynia following nerve injury. The expression of PAFR mRNA was increased in the DRG ipsilateral to nerve injury, which was seen mainly in macrophages. Furthermore, mice lacking PAFRs showed a reduction of nerve injury-induced tactile allodynia and, interestingly, a marked suppression of upregulation of tumor necrosis factor alpha (TNFalpha) and interleukin-1beta (IL-1beta) expression in the injured DRG, crucial proinflammatory cytokines involved in pain hypersensitivity. Conversely, a single injection of PAF near the DRG of naïve rats caused a decrease in the paw withdrawal threshold to mechanical stimulation in a dose-dependent manner and an increase in the expression of mRNAs for TNFalpha and IL-1beta, both of which were inhibited by pretreatment with a PAFR antagonist. CONCLUSIONS: Our results indicate that the PAF/PAFR system has an important role in production of TNFalpha and IL-1beta in the DRG and tactile allodynia following peripheral nerve injury and suggest that blocking PAFRs may be a viable therapeutic strategy for treating neuropathic pain