Elevated concentrations of sphingosylphosphorylcholine in cerebrospinal fluid after subarachnoid hemorrhage: a possible role as a spasmogen.

This study investigates the role of sphingosylphosphorylcholine (SPC) in the mechanisms underlying cerebral vasospasm after subarachnoid hemorrhage (SAH). The levels of SPC were measured in cerebrospinal fluid (CSF) of patients with SAH and also in an experimental canine model. CSF samples were collected from 11 patients with SAH, and from dogs that had received an injection of SPC into the cisterna magna to examine SPC kinetics in the CSF. SPC was assayed using solid-phase extraction and triple quadrupole mass spectrometry. The SPC concentrations in SAH patients on days 3, 8, and 14 after the onset of SAH were significantly higher than those in normal CSF. In the canine model, rapid dilution of SPC in CSF was observed. In combination with data from previous studies, these results suggest that SPC is involved in the development of cerebral vasospasm. Rapid dilution of SPC in CSF suggests that SPC is released into CSF at higher concentrations than those measured in the present study.

[No association between moyamoya disease and polymorphism of IGF2R].

Moyamoya disease is a cerebrovascular disorder of unknown etiology. Its high incidence in East Asia and accumulation in family members suggest a genetic background. A high incidence of maternal inheritance implicates genomic imprinting in this disorder. Based on this hypothesis, we studied the association between moyamoya disease and IGF2R gene on chromosome 6, but found no evidence for such association between them. On the other hand, heterogeneous expressions of IGF2R were confirmed in the lymphocytes. Some individuals showed monoallelic expression and others showed biallelic expression.

[Molecular screening for moyamoya disease by use of expressed sequence tag on chromosome 3p].

Moyamoya disease is a well-known cerebrovascular disorder of unknown pathogenesis affecting terminal portion of internal carotid arteries and causing ischemic attacks. Its familial occurrence suggests genetic background. We hypothesized that paternally imprinted gene might be associated with this disorder. To identify the expressed sequence tags (ESTs) with monoallelic expressions on chromosome 3, we used mouse A9 hybrid cells having human chromosome 3. Two ESTs showed only maternal expression in mouse A9 hybrid cells, and four showed non-expression in the lymphocytes derived from moyamoya patients. Although these ESTs are clustered on the same 150 kb region, we finally failed to identify cDNA in this region.

Sphingosylphosphorylcholine is a novel messenger for Rho-kinase-mediated Ca2+ sensitization in the bovine cerebral artery: unimportant role for protein kinase C.

Although recent investigations have suggested that a Rho-kinase-mediated Ca2+ sensitization of vascular smooth muscle contraction plays a critical role in the pathogenesis of cerebral and coronary vasospasm, the upstream of this signal transduction has not been elucidated. In addition, the involvement of protein kinase C (PKC) may also be related to cerebral vasospasm. We recently reported that sphingosylphosphorylcholine (SPC), a sphingolipid, induces Rho-kinase-mediated Ca2+ sensitization in pig coronary arteries. The purpose of this present study was to examine the possible mediation of SPC in Ca2+ sensitization of the bovine middle cerebral artery (MCA) and the relation to signal transduction pathways mediated by Rho-kinase and PKC. In intact MCA, SPC induced a concentration-dependent (EC50=3.0 micromol/L) contraction, without [Ca2+]i elevation. In membrane-permeabilized MCA, SPC induced Ca2+ sensitization even in the absence of added GTP, which is required for activation of G-proteins coupled to membrane receptors. The SPC-induced Ca2+ sensitization was blocked by a Rho-kinase inhibitor (Y-27632) and a dominant-negative Rho-kinase, but not by a pseudosubstrate peptide for conventional PKC, which abolished the Ca2+-independent contraction induced by phorbol ester. In contrast, phorbol ester-induced Ca2+ sensitization was resistant to a Rho-kinase inhibitor and a dominant-negative Rho-kinase. In primary cultured vascular smooth muscle cells, SPC induced the translocation of cytosolic Rho-kinase to the cell membrane. We propose that SPC is a novel messenger for Rho-kinase-mediated Ca2+ sensitization of cerebral arterial smooth muscle and, therefore, may play a pivotal role in the pathogenesis of abnormal contraction of the cerebral artery such as vasospasm. The SPC/Rho-kinase pathway functions independently of the PKC pathway.

Electrophoretic studies on the phosphorylation of stathmin and mitogen-activated protein kinases in neuronal cell death induced by oxidized very-low-density lipoprotein with apolipoprotein E.

In the central nervous system, stressful conditions can easily cause the oxidation of lipoprotein particles, followed by the oxidative modification of apolipoproteins such as apolipoprotein E (apoE) and the production of free radicals and aldehydes. We have confirmed that oxidized very-low-density lipoprotein (VLDL) inhibits the proliferation, viability and differentiation of neuronal PC12 cells leading to cell death. The cells internalized intact apoE, but did not internalize oxidized apoE. The phosphorylation of stathmin and various mitogen-activated protein (MAP) kinases including extracellular signal-regulated protein kinase (ERK), p38, and c-Jun N-terminal kinase (JNK) was examined in PC12 cells exposed to native and oxidized VLDL, H(2)O(2) (which generates free radicals), and 4-hydroxy-2-nonenal (HNE) (an aldehyde). Oxidized VLDL and H(2)O(2) reduced stathmin phosphorylation while HNE increased it, suggesting that oxidized VLDL and H(2)O(2) stimulated similar signal transduction pathways. Based on the results, free radicals, but not aldehydes may play a major role in the neuronal cell death induced by lipoprotein oxidation. Furthermore, the phosphorylation status of MAP kinases indicated that the activation of the JNK cascade might be required for neuronal cell death.

Evaluation of cerebral perfusion parameters measured by perfusion CT in chronic cerebral ischemia: comparison with xenon CT.

PURPOSE: The purpose of this work was to evaluate the usefulness of perfusion CT in the evaluation of patients with chronic cerebral ischemia by comparing it with xenon CT (Xe-CT). METHOD: Cerebral blood flow (CBF) of perfusion CT (CBFper) and time to peak (TTP) were compared with the CBF of Xe-CT (CBFxe) in 18 patients. Cerebral blood volume (CBV) was compared with cerebral vascular reserve (CVR) in 10 of 18 patients who underwent pre- and postacetazolamide Xe-CT. RESULTS: CBFper and TTP demonstrated a high correlation with CBFxe in relative values by side-to-side comparisons (r = 0.743, p < 0.0001 and r = -0.760, p < 0.0001, respectively). There was a negative correlation between relative CBV and relative CVR (r = -0.637, p = 0.0025). Visually, territories with delayed TTP corresponded well to those of decreased CBFxe, but these territories tended to be larger in TTP maps. CONCLUSION: Perfusion CT is a useful tool to evaluate chronic hemodynamic disturbance and can be an alternative method for those using acetazolamide challenge.