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Background/Aims: Although serum assays for pro-gastrin-releasing peptide (ProGRP) assays have been commercially available in Japan for several years, the stability of ProGRP in serum and plasma has not been well documented. We investigated the stability of ProGRP in serum and plasma with fresh and stored (frozen) specimens, as well as the cause of the observed instability in serum. Methods/Results: ProGRP concentrations in fresh serum were decreased by 6–28% after room temperature storage for 2 h and by 8–32% after 2–8°C storage for 24 h. The average change in ProGRP concentrations in fresh plasma was within ±10% of baseline for more than 4 h at room temperature and for more than 24 h at 2–8°C. The incubation of a serine protease, thrombin (activated blood coagulation factor II), in a buffer solution containing ProGRP caused decreases in ProGRP concentrations. Following the addition of phenylmethylsulfonyl fluoride, a serine protease inhibitor, to serum, the serum stability for ProGRP was similar to that in plasma. ProGRP is significantly more stable in plasma than in serum. We speculate that thrombin in serum is one of the factors that inactivate ProGRP in serum by proteolysis of the ProGRP antigen. Conclusion: The use of plasma samples for ProGRP may improve the clinical reliability of this marker by minimizing preanalytical changes in ProGRP concentrations.

Neuropathic pain induced by sciatic nerve injury not only causes peripheral dysfunctions but also affects the cortical and subcortical regions of the brain. It is still unknown whether neuropathic pain could relate to behavioral and neurochemical alterations in the central nervous system. This paper deals with the effect of peripheral neuropathic pain on mechanical allodynia, neuropeptide levels, neuropeptide-degrading enzyme activities, and microglial cells in the brain regions of rats by applying chronic constriction injury, a partial sciatic nerve injury. We examined the possible protection effect on the allodynia and changes in levels of neuropeptides and microglial activation in chronic constriction injury of the rat brain by memantine. On 4 days after chronic constriction injury, the induction of mechanical allodynia was suppressed by memantine treatment. Reductions in the substance P in the hypothalamus and somatostatin in the periaqueductal gray of chronic constriction injury rat brain were reversed by memantine. This suggests the role of these neuropeptides in pain information processing in the brain. Immunohistochemical experiments revealed that the expression of CD11b, a marker protein of microglia, was increased in the hypothalamus and periaqueductal gray in the chronic constriction injury rat brain as compared with the controls, and memantine treatment could suppress the activation of microglia, suggesting the involvement of microglia in pain mechanism. The present behavioral, biochemical, and immunohistochemical studies demonstrated that peripheral neuropathic pain affects the neuropeptide levels and microglial activation in the brain regions, and these events described above may play an important role in neuropathic pain pathogenesis.

A new immunochromatographic rapid test, Determine HIV-1/2, for the detection of antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2 in human whole blood, serum, and plasma was evaluated. Determine HIV-1/2 is a sandwich immunoassay and uses a nitrocellulose strip with a capture site for the patient’s results and a procedural control site to confirm the validity of the assay. The results can be read visually, and a positive result is indicated by the formation of a red line within 15 min after sample application. The test showed 100% sensitivity for HIV-1 with 102 whole-blood, 152 serum, and 144 plasma samples obtained from Ramathibodi Hospital, Bangkok, Thailand. The sensitivity of the test for HIV-2 was 100% with 100 serum or plasma samples obtained from Ivory Coast. The sensitivity of the test with 4 anti-HIV-1 seroconversion panels from Boston Biomedica Inc. was equivalent to or better than those of another agglutination assay with serum or plasma and the enzyme immunoassay licensed by the U.S. Food and Drug Administration. The specificity was 100% with 367 sets of whole-blood, serum, and plasma samples from Ramathibodi Hospital. This method had an analytical sensitivity for the detection of HIV-1 equivalent to or better than that of another agglutination assay with serum or plasma. This test had an analytical sensitivity for the detection of HIV-1 better than that of another immunochromatographic test with whole blood. This evaluation demonstrated the excellent performance of this immunochromatographic test with EDTA-anticoagulated whole-blood, serum, and plasma samples. We conclude that this test is suitable for use in emerging countries and is an excellent alternative to HIV antibody testing at remote sites, as well as in traditional laboratories.

Axonal transport of peptidylglycine alpha-amidating monooxygenase (PAM) activity was studied in rat sciatic nerves from 12 to 120 h after double ligations. The anterograde axonal transport increased and reached a plateau between 48 and 72 h and then decreased. The flow rate was 100 mm/day, and the molecular mass of the active entity was 70 kDa, which was determined by gel filtration. In contrast, there was no evidence for significant retrograde axonal transport. Anterograde axonal transport of immunoreactive cholecystokinin, a carboxy-terminal-amidated putative neuropeptide, was also found. These results suggest that PAM is transported by a rapid axonal flow and may play a role as a processing enzyme during transport or in the terminals of rat sciatic nerves.