Spatiotemporal Characteristics Determining the Multifaceted Nature of Reactive Oxygen, Nitrogen, and Sulfur Species in Relation to Proton Homeostasis.

Significance: Reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) act as signaling molecules, regulating gene expression, enzyme activity, and physiological responses. However, excessive amounts of these molecular species can lead to deleterious effects, causing cellular damage and death. This dual nature of ROS, RNS, and RSS presents an intriguing conundrum that calls for a new paradigm. Recent Advances: Recent advancements in the study of photosynthesis have offered significant insights at the molecular level and with high temporal resolution into how the photosystem II oxygen-evolving complex manages to prevent harmful ROS production during the water-splitting process. These findings suggest that a dynamic spatiotemporal arrangement of redox reactions, coupled with strict regulation of proton transfer, is crucial for minimizing unnecessary ROS formation. Critical Issues: To better understand the multifaceted nature of these reactive molecular species in biology, it is worth considering a more holistic view that combines ecological and evolutionary perspectives on ROS, RNS, and RSS. By integrating spatiotemporal perspectives into global, cellular, and biochemical events, we discuss local pH or proton availability as a critical determinant associated with the generation and action of ROS, RNS, and RSS in biological systems. Future Directions: The concept of localized proton availability will not only help explain the multifaceted nature of these ubiquitous simple molecules in diverse systems but also provide a basis for new therapeutic strategies to manage and manipulate these reactive species in neural disorders, pathogenic diseases, and antiaging efforts.

Histone H3.3 variant plays a critical role on zygote-to-oocyst development in malaria parasites.

The Plasmodium life cycle involves differentiation into multiple morphologically distinct forms, a process regulated by developmental stage-specific gene expression. Histone proteins are involved in epigenetic regulation in eukaryotes, and the histone variant H3.3 plays a key role in the regulation of gene expression and maintenance of genomic integrity during embryonic development in mice. However, the function of H3.3 through multiple developmental stages in Plasmodium remains unknown. To examine the function of H3.3, h3.3-deficient mutants (Δh3.3) were generated in P. berghei. The deletion of h3.3 was not lethal in blood stage parasites, although it had a minor effect of the growth rate in blood stage; however, the in vitro ookinete conversion rate was significantly reduced, and the production of the degenerated form was increased. Regarding the mosquito stage development of Δh3.3, oocysts number was significantly reduced, and no sporozoite production was observed. The h3.3 gene complemented mutant have normal development in mosquito stage producing mature oocysts and salivary glands contained sporozoites, and interestingly, the majority of H3.3 protein was detected in female gametocytes. However, Δh3.3 male and female gametocyte production levels were comparable to the wild-type levels. Transcriptome analysis of Δh3.3 male and female gametocytes revealed the upregulation of several male-specific genes in female gametocytes, suggesting that H3.3 functions as a transcription repressor of male-specific genes to maintain sexual identity in female gametocytes. This study provides new insights into the molecular biology of histone variants H3.3 which plays a critical role on zygote-to-oocyst development in primitive unicellular eukaryotes.

Admp regulates tail bending by controlling ventral epidermal cell polarity via phosphorylated myosin localization in Ciona.

Ventral tail bending, which is transient but pronounced, is found in many chordate embryos and constitutes an interesting model of how tissue interactions control embryo shape. Here, we identify one key upstream regulator of ventral tail bending in embryos of the ascidian Ciona. We show that during the early tailbud stages, ventral epidermal cells exhibit a boat-shaped morphology (boat cell) with a narrow apical surface where phosphorylated myosin light chain (pMLC) accumulates. We further show that interfering with the function of the BMP ligand Admp led to pMLC localizing to the basal instead of the apical side of ventral epidermal cells and a reduced number of boat cells. Finally, we show that cutting ventral epidermal midline cells at their apex using an ultraviolet laser relaxed ventral tail bending. Based on these results, we propose a previously unreported function for Admp in localizing pMLC to the apical side of ventral epidermal cells, which causes the tail to bend ventrally by resisting antero-posterior notochord extension at the ventral side of the tail.

Impact of tumor growth rate during preceding treatment on tumor response to nivolumab or irinotecan in advanced gastric cancer.

BACKGROUND: Nivolumab (NIVO) and irinotecan (IRI) are standard treatments for refractory advanced gastric cancer (AGC); however, it is unclear which drug should be administered first or in which cases. The tumor growth rate (TGR) during preceding treatment is reported to be associated with tumor response in metastatic colorectal cancer patients treated with regorafenib or trifluridine/tipiracil, suggesting that TGR may be useful for drug selection. Therefore, we evaluated the association between TGR during preceding treatment and the tumor response to NIVO or IRI. PATIENTS AND METHODS: We retrospectively evaluated consecutive AGC patients treated with NIVO or IRI and divided them into slow-growing (Slow) and rapid-growing (Rapid) groups according to TGR and the presence or absence of new lesions (NL+/NL-, respectively) during preceding treatment (Slow group: NL- with low TGR <0.30%/day; Rapid group: NL+ or high TGR ≥0.30%/day). RESULTS: A total of 117 patients (Rapid/Slow groups, 72/45; NIVO/IRI groups, 32/85) were eligible. All baseline characteristics except peritoneal metastases were similar between patients treated with NIVO and IRI in the Rapid and Slow groups. The response rate was significantly higher in patients treated with NIVO compared with IRI [31%/3%; odds ratio (OR), 13.8; P = 0.01; adjusted OR, 52; P = 0.002] in the Slow group, but there was no difference between patients treated with NIVO and IRI (5%/8%; OR, 0.68; P = 0.73; adjusted OR, 0.94; P = 0.96) in the Rapid group. Disease control rate, progression-free survival, and overall survival were consistent with these results. CONCLUSIONS: Our findings suggest that NIVO treatment is a more favorable option for patients with slow-growing tumors, and NIVO and IRI are similarly recommended for patients with rapid-growing tumors in refractory AGC. TGR and NL emergence during preceding treatment may be helpful for drug selection and warrant further investigation.

Molecular epidemiology of coxsackievirus A6 circulating in Hong Kong reveals common neurological manifestations and emergence of novel recombinant groups.

BACKGROUND: Coxsackievirus A6 (CV-A6) represents the predominant enterovirus serotype in Hong Kong, but its epidemiology in our population was unknown. OBJECTIVES: To examine the clinical and molecular epidemiology of CV-A6 and detect emerging recombinant strains in Hong Kong. STUDY DESIGN: Nasopharyngeal aspirates (NPAs) from patients with febrile or respiratory illness were subject to RT-PCR for CV-A6 and sequencing of 5'-NCR and VP1. CV-A6-positive samples were further subject to 2C and 3D gene sequencing. Complete genome sequencing was performed on potential recombinant strains. RESULTS: Thirty-six (0.35%) NPAs were positive for CV-A6 by 5'-NCR RT-PCR and sequencing, 28 of which confirmed by partial VP1 gene sequencing. Among the 28 patients (mainly young children) with CV-A6 infection, hand-foot-and-mouth disease (HFMD) (43%), herpangina (18%) and tonsillitis (11%) were the most common diagnoses. Seven (25%) patients had neurological manifestations, including febrile seizures, encephalitis and meningitis. VP1 gene analysis showed that 24 CV-A6 strains circulating in Hong Kong belonged to genotype D5, while 4 strains belonged to D4. Further 2C and 3D gene analysis revealed eight potential recombinant strains. Genome sequencing of five selected strains confirmed four recombinant strains: HK459455/2013 belonging to recombination group RJ arisen from CV-A6/CV-A4, HK458288/2015 and HK446377/2015 representing novel group RL arisen from CV-A6/CV-A4, and HK462069/2015 representing novel group RM arisen from CV-A6/EV-A71. Recombination breakpoints located at 3D were identified in the latter three recombinant strains, with HK462069/2015 (from a child with encephalitis) having acquired 3D region from EV-A71. CONCLUSIONS: We identified novel recombinant CV-A6 strains in Hong Kong, with 3D being a common recombination site.

S-1 and irinotecan plus bevacizumab versus mFOLFOX6 or CapeOX plus bevacizumab as first-line treatment in patients with metastatic colorectal cancer (TRICOLORE): a randomized, open-label, phase III, noninferiority trial.

Background: Combination therapy with oral fluoropyrimidine and irinotecan has not yet been established as first-line treatment of metastatic colorectal cancer (mCRC). We carried out a randomized, open-label, phase III trial to determine whether S-1 and irinotecan plus bevacizumab is noninferior to mFOLFOX6 or CapeOX plus bevacizumab in terms of progression-free survival (PFS). Patients and methods: Patients from 53 institutions who had previously untreated mCRC were randomly assigned (1 : 1) to receive either mFOLFOX6 or CapeOX plus bevacizumab (control group) or S-1 and irinotecan plus bevacizumab (experimental group; a 3-week regimen: intravenous infusions of irinotecan 150 mg/m2 and bevacizumab 7.5 mg/kg on day 1, oral S-1 80 mg/m2 twice daily for 2 weeks, followed by a 1-week rest; or a 4-week regimen: irinotecan 100 mg/m2 and bevacizumab 5 mg/kg on days 1 and 15, S-1 80 mg/m2 twice daily for 2 weeks, followed by a 2-week rest). The primary end point was PFS. The noninferiority margin was 1.25; noninferiority would be established if the upper limit of the 95% confidence interval (CI) for the hazard ratio (HR) of the control group versus the experimental group was less than this margin. Result: Between June 2012 and September 2014, 487 patients underwent randomization. Two hundred and forty-three patients assigned to the control group and 241 assigned to the experimental group were included in the primary analysis. Median PFS was 10.8 months (95% CI 9.6-11.6) in the control group and 14.0 months (95% CI 12.4-15.5) in the experimental group (HR 0.84, 95% CI 0.70-1.02; P < 0.0001 for noninferiority, P = 0.0815 for superiority). One hundred and fifty-seven patients (64.9%) in the control group and 140 (58.6%) in the experimental group had adverse events of grade 3 or higher. Conclusion: S-1 and irinotecan plus bevacizumab is noninferior to mFOLFOX6 or CapeOX plus bevacizumab with respect to PFS as first-line treatment of mCRC and could be a new standard treatment. Clinical trials number: UMIN000007834.

Randomised phase II study comparing dose-escalated weekly paclitaxel vs standard-dose weekly paclitaxel for patients with previously treated advanced gastric cancer.

BACKGROUND: This randomised phase II trial compared dose-escalated weekly paclitaxel (wPTX) vs standard-dose wPTX for patients with previously treated advanced gastric cancer (AGC). METHODS: Ninety patients were randomised to a standard dose of wPTX (80 mg m(-2)) or an escalated dose of wPTX (80-120 mg m(-2)) to assess the superiority of overall survival (OS) with a one-sided alpha error of 0.3 and a power of 0.8. RESULTS: The median OS showed a trend towards longer survival in the dose-escalated arm (11.8 vs 9.6 months; hazard ratio (HR), 0.75; one-sided P=0.12), although it was statistically not significant. The median progression-free survival (PFS) was significantly longer in the dose-escalated arm (4.3 vs 2.5 months, HR, 0.55; P=0.017). Objective response rate was 30.3% with dose escalation and 17.1% with standard dose (P=0.2). The frequency of all grades of neutropenia was significantly higher with dose escalation (88.7% vs 60.0%, P=0.002); however, no significant difference was observed in the proportion of patients experiencing grade 3 or more (40.9% vs 31.1%, P=0.34). CONCLUSION: Dose-escalated wPTX in patients with pretreated AGC met our predefined threshold of primary end point, OS (P<0.3); however, it did not show a significantly longer OS. Progression-free survival was significantly better with dose escalation.

Caspase activation is involved in early megakaryocyte differentiation but not in platelet production from megakaryocytes.

To elucidate whether caspase activation is involved in megakaryopoiesis, we characterized megakaryocytes (MKs) in vav-bcl-2 transgenic (Tg) mice, in which Bcl-2 is overexpressed in hematopoietic cells. To exclude the effect of splenomegaly in Tg mice on megakaryopoiesis, splenectomy was performed. After splenectomy, basal platelet counts in peripheral blood were not significantly different between Tg and wild-type (WT) mice. However, when experimental thrombocytopenia was induced by injecting 5-fluorouracil into splenectomized mice, overshoot of platelet counts during the recovery phase was hardly observed in Tg mice. Analyses of MK ploidy during the recovery phase showed that MKs less than 16 N ploidy were significantly decreased in Tg mice, suggesting that MK supply from progenitors is impaired. Supporting this, differentiation of CD34-/c-kit+/Sca-1+/Lineage- stem cells into MKs was significantly hampered in Tg mice, whereas megakaryocyte-erythroid progenitors (MEPs) normally differentiated into MKs. It suggests that differentiation into MKs is impaired in Tg mice before the stage of MEP. Furthermore, MK colony formation in WT cells was dose-dependently inhibited in the presence of a caspase inhibitor. Contrary, Bcl-2-overexpressing MKs showed normal ability for in vitro platelet production. We thus believe that caspase activation is involved in the differentiation of progenitors into megakaryocytic lineage but not in platelet production.

Development of case-based medication alerting and recommender system: a new approach to prevention for medication error.

The purpose of this study was to develop a new alerting and recommender system for preventing medication errors. In recent years, alerting systems have been widely implemented, but because these systems apply a same static threshold for all patients in all cases, they produce excessive alerts and subject physicians to "alert fatigue". We believe that the most commonly-written prescription for a patient's status is the safest one. From this standpoint, we developed a real-time case-based medication alerting and recommender system linked to a database of past prescriptions. When a physician issues his or her prescription, our system dynamically compares it with past ones for similar patients in the database. An analysis of the 10 most frequently-used drugs in the University of Tokyo Hospital revealed that our system reduced the number of false alerts compared to the traditional static alert method. Our system contributes to the creation of alerts that are appropriate for patients' clinical conditions and based on physicians' empirical discretion.

Continuous expression of Bcl-xL protein during megakaryopoiesis is post-translationally regulated by thrombopoietin-mediated Akt activation, which prevents the cleavage of Bcl-xL.

BACKGROUND: One of the important biological activities of thrombopoietin (TPO) is to prevent the apoptosis of megakaryocytes. As the antiapoptotic protein Bcl-xL, which has been proven to be indispensable for erythroid differentiation, is also abundantly expressed in megakaryocytes, it is assumed that Bcl-xL plays an important role in megakaryopoiesis. OBJECTIVES: We investigated the expression of Bcl-xL during megakaryopoiesis and the underlying regulatory mechanism. METHODS AND RESULTS: In stem cell-derived megakaryocytes, expression of Bcl-xL increased in the early and mid-stages of the differentiation. Both in vitro in cell culture and in vivo in an animal model, expression of Bcl-xL protein was maintained until the platelet-producing stage. TPO depletion caused significant decrease in Bcl-xL protein level without affecting its mRNA in both megakaryocytes and TPO-dependent megakaryocytic UT-7/TPO cells, suggesting that Bcl-xL protein level in TPO-dependent cells is post-translationally regulated. In agreement with this finding, we recognized the appearance of a 12-kD fragment of Bcl-xL upon TPO depletion. This cleavage of Bcl-xL was inhibited by a caspase-3-specific inhibitor. Furthermore, pretreatment of UT-7/TPO with a phosphatidylinositol 3-kinase (PI3 K) inhibitor resulted in the cleavage of Bcl-xL even in the presence of TPO. We thus hypothesized that PI3 K inhibits the activation of caspase-3 and consequent cleavage of Bcl-xL. To prove this, we prepared UT-7/TPO cells transfected with constitutively active Akt-1. When TPO was depleted, the transfectant was significantly less liable to caspase-3 activation and Bcl-xL cleavage. CONCLUSIONS: Bcl-xL protein is expressed throughout megakaryopoiesis until platelets are produced, and its expression level is at least in part post-translationally regulated through TPO-mediated Akt activation.

Treatment of a Gilbert's syndrome patient with irinotecan, leucovorin and 5-fluorouracil.

The patient was an elderly male who had radical surgery for sigmoid cancer in 2001. Owing to metastasis of his cancer to the left supraclavicular lymph nodes in 2002, the patient was admitted to our hospital for systemic chemotherapy. We started treatment with irinotecan, leucovorin, 5-fluorouracil (IFL). After administering 100 mg/m2 of irinotecan, 250 mg/m2 leucovorin and 600 mg/m2 5-fluorouracil to the patient on day 1, grade 3 leukopenia developed rapidly and grade 4 thrombocytopenia was observed on day 5. We excluded irinotecan from the medication and continued the administration of 5-fluorouracil and leucovorin, but his tumors had not been reduced sufficiently. Based on some examination results, we assumed that the patient had Gilbert's syndrome and that the severe side effects that occurred were due to prolongation of SN38 metabolism. We again administered irinotecan but at reduced dose (25 mg/m2). Four courses of this modified IFL were administered safely and the response was favorable.

Delayed neuronal death prevented by inhibition of increased hydroxyl radical formation in a transient cerebral ischemia.

The salicylate-trapping method was used to detect hydroxyl radicals by measurement of stable adduct dihydroxybenzoic acid (DHBA). Ten minutes of forebrain ischemia followed by reperfusion induced the increase in DHBA in rat hippocampal perfusates. Postischemic treatment with a free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186), significantly reduced the increase in DHBA and suppressed delayed neuronal death in the hippocampal CA1 region.

Effects of a novel free radical scavenger, MCl-186, on ischemic brain damage in the rat distal middle cerebral artery occlusion model.

We investigated the effects of a free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (MCl-186), on infarct areas, neurological deficits and regional cerebral blood flow (rCBF), with use of a rat thrombotic distal middle cerebral artery (dMCA) occlusion model to elucidate its possible therapeutic effects on focal cerebral ischemia. In addition, we have attempted to measure 2-oxo-3-(phenylhydrazono)-butanoic acid (OPB), which is the major oxidation product of MCl-186, in the penumbral cortex of a thrombotic dMCA occlusion model. Postischemic treatment with MCl-186 (3 mg/kg) significantly (P < .05) decreased the size of the cerebral infarcts 1 day after dMCA occlusion. MCl-186 (3 mg/kg) significantly (P < .05) improved the neurological deficits 1 day after dMCA occlusion. On the contrary, MCl-186 had no effect on rCBF 1 day after dMCA occlusion. MCl-186 mainly reacted into OPB by peroxidation in rat brain homogenates. Furthermore, the increase in OPB content in the ischemic penumbral cortex tissue was confirmed after 90 min of MCl-186 perfusion. These results suggest that MCI-186 has a protective effect on brain ischemia by reacting with oxygen radicals and that oxygen radicals are closely related to postischemic brain injury.

The changes of LCGU and rCBF in the MCA occlusion-recirculation model in rats and the ameliorating effect of MCI-186, a novel free radical scavenger.

We examined the change of regional cerebral blood flow (rCBF) and local cerebral glucose utilization (LCGU) in the middle cerebral artery (MCA) occlusion or recirculation model of rats, and tested anti-ischemic effects of a free radical scavenger, 3-methyl-1-phenyl-pyrazolon-5-one (MCI-186). A remarkable increase in LCGU was observed in the cortex supplied by the anterior cerebral artery after recirculation. This hypermetabolism of glucose was at least partly caused by the postischemic oxidative injury, since MCI-186 ameliorated the high LCGU in this area. These results suggested the usefulness of this type of free radical scavenger for inhibiting the postischemic injury.

Effects of a thrombin inhibitor, argatroban, on ischemic brain damage in the rat distal middle cerebral artery occlusion model.

To elucidate the role of thrombin in brain damage during focal cerebral ischemia, we investigated the effects of a selective thrombin inhibitor, argatroban, on microthrombi formation, regional cerebral blood flow (rCBF), infarct areas and neurological deficits using a rat thrombotic distal middle cerebral artery (dMCA) occlusion model. The rat dMCA was occluded by a platelet-rich thrombus formed after photochemical reaction between rose bengal and green light. One day after dMCA occlusion, the number of microthrombi were counted. In the separate animals, rCBF was measured by using the iodoantipyrine method 1 day after dMCA occlusion. Three days after dMCA occlusion, behavioral tests were performed and the size of the cerebral infarction was determined. In the present study, argatroban was administered i.p. by continuous infusion after dMCA occlusion. Argatroban (0.3 mg/h/rat) significantly (P < .05) decreased the number of microthrombi 1 day after dMCA occlusion. Argatroban (0.1 and 0.3 mg/h/rat) significantly (P < .01) reversed a decrease in rCBF 1 day after dMCA occlusion. Argatroban (0.3 mg/h/rat) also significantly (P < .01) reduced the size of the cerebral infarction. Administration of argatroban (0.1 and 0.3 mg/h/rat) resulted in a significant improvement in neurological deficits 3 days after dMCA occlusion (P < .01 and P < .05, respectively). Argatroban decreased the size of the cerebral infarction and improved neurological deficits in the rat thrombotic dMCA occlusion model. These effects were thought to be due to the improvement of rCBF and to the reduction in secondary thrombus formation after dMCA occlusion.

Synthesis and antipancreatitis activities of novel N-(2-sulfonylamino-5-trifluoromethyl-3-pyridyl)carboxamide derivatives as phospholipase A2 inhibitors.

Novel N-(2-sulfonylamino-5-trifluoromethyl-3-pyridyl)carboxamide derivatives have been prepared and evaluated as phospholipase A2 (PLA2) inhibitors. Among these compounds, IS-741 (sodium salt of 1j), which showed the highest and the most stable therapeutic effect on acute hemorrhagic pancreatitis induced by the closed duodenal loop method in rats, was selected as a candidate for further development.

Protective effects of MCI-186 on cerebral ischemia: possible involvement of free radical scavenging and antioxidant actions.

The anti-ischemic effects and a possible mechanism of a new antistroke agent, 3-methyl-1-phenyl-pyrazolin-5-one (MCI-186), were studied. Preischemic treatment with MCI-186 (3 mg/kg i.v.) facilitated the recovery of electrocorticographic activity and prolonged survival time in global complete ischemia of rats; MCI-186 (1 and 3 mg/kg i.v.) also mitigated dysfunction of the blood-brain barrier and energy failure in hemispheric embolization of rats. Postischemic treatment with MCI-186 (3 mg/kg i.v.) decreased cortical infarction in focal embolization of rats. MCI-186 (0.6-2.4 mM) inhibited the OH.-induced hydroxylation of salicylate (maximal inhibition, 40.2%), but at 100 microM it did not influence O2- generation. MCI-186 inhibited the formation of linoleic acid-conjugated dienes caused by OH. (IC50 = 32.0 microM). Also, concurrent administration of MCI-186 (3-100 mg/kg i.v.) ameliorated hyperglycemia, hyperlipopeoxidemia and degranulation of beta-cells in alloxan (40 mg/kg i.v.)-treated rats. In addition, MCI-186 inhibited iron-dependent peroxidation in rat brain homogenates and mitochondrial homogenates (IC50 = 15.0 and 2.3 microM, respectively) and prevented iron-dependent peroxidative disintegration of mitochondrial membranes (IC50 = 39.0 microM). These findings suggest that MCI-186 has potent anti-ischemic actions and that its mechanism may be closely associated with beneficial antioxidant activities.

Vinconate prevents ischemic neuronal damage in the rat hippocampus.

The neuroprotective effect of vinconate, a novel vinca alkaloid derivative, was examined in a rat model of forebrain ischemia induced by 4-vessel occlusion. Hippocampal cell loss was quantified histologically 3 days after 10 or 15 min of ischemia. Intraperitoneal application of vinconate (25 and 50 mg/kg) 10 min before and immediately after 10 min of ischemia significantly reduced the neuronal cell loss in the CA1 sector of the hippocampus. Protective effect of vinconate against 15 min of ischemia was reduced, but there was still significant protection at the higher dose. Autoradiography using 14C-vinconate showed that the drug easily penetrates the blood-brain barrier and distributes in the hippocampus. The result suggests that vinconate prevents ischemic neuronal damage by direct action on the hippocampal CA1 neurons.

Effect of MCI-186 on brain edema in rats.

We induced brain edema in 72 rats by injecting 5 microliters of 3.0% wt:vol polyvinyl acetate into the left internal carotid artery, producing permanent embolization in the left cerebral hemisphere, which developed ipsilateral brain edema reproducibly. Edema was assessed 24 hours after embolization by determining the brain water content and the sodium and potassium concentrations. In this model, the free radical scavenger MCI-186 at 1.0 and 3.0 mg/kg i.v. prevented brain edema in a dose-dependent manner. At 3.0 mg/kg i.v., MCI-186 significantly reduced water content by 1.5% and improved the sodium-potassium balance to within the normal range in the embolized left hemisphere. Dexamethasone at 1.0 mg/kg i.v. did but at 3.0 mg/kg i.v. did not significantly inhibit the development of brain edema. Indomethacin at 4.0 mg/kg i.p. had no effect on brain edema. We suggest that the cyclooxygenase metabolites of arachidonic acid liberated from neuronal cell membrane phospholipids are not likely to be involved in the pathogenesis of permanent brain edema induced by polyvinyl acetate. Our results suggest that MCI-186 attenuates brain edema by suppressing the production of lipoxygenase metabolites, including free radicals or lipid peroxides, and that it may prove valuable for the treatment of brain edema associated with cerebral ischemia.

Strong attenuation of ischemic and postischemic brain edema in rats by a novel free radical scavenger.

Regional changes in the amount of free fatty acids, polyphosphoinositides, and water content in the cerebral cortex were examined using a middle cerebral artery occlusion model of rats. The amount of various free fatty acids increased as polyphosphoinositides decreased during 3 and 6 hours of ischemia in the occluded middle cerebral artery territory. After 3 hours of reperfusion following 3 hours of ischemia, free fatty acids partially recovered while polyphosphoinositides did not. Water content increased significantly after 3 and 6 hours of ischemia, and a further increase was found after 3 hours of reperfusion following 3 hours of ischemia. The change of polyenoic fatty acids in this occluded middle cerebral artery territory was much smaller than that in the case of decapitation ischemia, although the amounts of polyphosphoinositides and monoenoic and saturated fatty acids showed almost identical changes in both cases, probably because polyenoic fatty acids may be washed out and/or peroxidatively consumed in the middle cerebral artery occlusion model due to its residual blood flow. Changes in the area surrounding the occluded middle cerebral artery territory were similar to the above results, although less dramatic. However, there was no change in free fatty acids, polyphosphoinositides, and water content in the contralateral cortex. A novel free radical scavenger (MCI-186), which prevents both nonenzymatic peroxidation and lipoxygenase activity in vitro, markedly attenuated the ischemic and postischemic brain swelling. These results suggest that free radical mechanisms may be involved in ischemic and postischemic brain edema.