Thrombopoietic activity of recombinant human interleukin-11 in nonhuman primates with ACNU-induced thrombocytopenia

The effect of recombinant human interleukin-11 (rHuIL-11) on myelosuppressive nimustine (ACNU)-induced thrombocytopenia was assessed in nonhuman primates. A single intravenous (i.v.) injection of ACNU (15 mg/kg) was administered to cynomolgus monkeys on day 0. rHuIL-11 (100 microg/kg/day) or the vehicle was given subcutaneously (s.c.) from day 1 to day 21. In monkeys receiving ACNU, the circulating platelet count decreased to a low of 42 +/- 6 x 10(9)/L by day 21 but returned to pretreatment levels (375 +/- 48 x 10(9)/L) on day 30. Administration of rHuIL-11 prevented severe thrombocytopenia; the platelet count fell only to 138 +/- 23 x 10(9)/L on day 18, and platelet recovery was faster (458 +/- 91 x 10(9)/L by day 27) compared with that of the control animals. The size of bone marrow megakaryocytes from rHuIL-11-treated animals was larger than that of the controls, indicating that rHuIL-11 stimulated megakaryopoiesis in a myelosuppressive condition. Treatment with ACNU also caused leukopenia and moderate anemia. rHuIL-11 transiently and slightly decreased the white blood cell (WBC) and red blood cell (RBC) counts. Conversely, rHuIL-11 accelerated recovery of RBC count in the late administration period. These results support the assertion that rHuIL-11 may be an important therapeutic agent for reducing the severity and duration of thrombocytopenia following cancer chemotherapy.

Differentiation of hepatitis B virus genotypes D and E by ELISA using monoclonal antibodies to epitopes on the preS2-region product

An enzyme-linked immunosorbent assay (ELISA) has been described for serological determination of hepatitis B virus genotypes, using monoclonal antibodies (mAb) against seven distinct epitopes (b, m, k, s, u, f and g) on the preS2-region products of hepatitis B surface antigen (HBsAg). The usefulness of this method for serological detection of genotype E, however, was theoretical, because no HBsAg samples of this genotype were included in the original test panel. Moreover, the predicted serotype of genotype E (bksufg) closely resembled that of genotype D (bksu, bksuf or bksug). Four HBsAg samples of genotype E were tested by the original described ELISA. The epitope g, predicted to be present in these samples by amino acid sequences, was not detected when HBsAg of genotype E was captured on a solid phase by mAb to the common determinant 'a' of HBsAg and then reacted with mAb to g (5156) labeled with horseradish peroxidase. However, the four examples of HBsAg of genotype E were captured by mAb 5156 to g on a solid phase; they were then detected by labeled mAb to the common determinant 'a'. Since epitopes f and g co-occurred on HBsAg of genotype E, HBsAg samples of this genotype were also detected, by 'sandwiching' them between immobilized mAb to g and labeled mAb to f. By contrast, HBsAg of genotype D in 90 sera was not reactive when sandwiched between mAb to f and g. Thus, this modified ELISA enables the serological determination of all six genotypes of HBsAg and, by inference, of hepatitis B virus.

Properties of a YAP powder scintillator as alpha-ray detector

A YAP scintillator (YAlO3: Ce crystal) for alpha counting has been produced in powder form and this paper describes its performance characteristics. By measuring pulse-height and rise-time distributions, it was found that the YAP powder, as a fast detector for alpha rays, could clearly distinguish alpha events from beta and gamma events. In addition, the YAP powder was used in a phoswich detector combined with a YAG (Y3Al5O12: Ce) crystal for beta and gamma detection.

Full-genome sequence analyses of hepatitis B virus (HBV) strains recovered from chimpanzees infected in the wild: implications for an origin of HBV

Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus of the family Hepadnaviridae. Having been found in various animals (duck, heron, woodchuck, ground squirrel, and primates), hepadnaviruses must have undergone a long history of evolution and may comprise more members than currently recognized. Chimpanzees may also have their own hepadnavirus, even if it might be very close to HBV. We analyzed HBV-like sequences from three chimpanzees (Pan troglodytes) that were most likely infected during their life in Africa in the wild. Two chimpanzees (Ch256 and Ch258) possessed a viral genome of 3182 nt in length with a 33-nt deletion in the preS1 region, which could not be classified into any of the six genotypes (A-F) of human HBV but was very homologous to a previously reported isolate from a London Zoo chimpanzee. Phylogenetically distinct from the HBV-like sequences from gibbons, orangutans, and a gorilla so far reported, the Ch256 and Ch258 isolates would represent an indigenous chimpanzee HBV (tentatively ChHBV). A third chimpanzee (Ch195) had a 3212-nt genome, classifiable into the genotype E of HBV. Because HBV-E has been found mostly in Africans, Ch195 may have been infected from a human source in Africa. However, an inverse scenario is also possible: a spread of HBV-E might have occurred from chimpanzees to humans a long time ago in Africa. Analysis of the arginine-rich C-terminal region of the core protein, which is well conserved among mammalian hepadnaviruses, indicated that HBV-E/F and nonhuman primate hepadnaviruses are much closer than HBV-A/B/C/D to the hepadnaviruses of woodchuck and ground squirrel. Our results support an "ex-nonhuman primate" hypothesis for the origin of HBV.

Mutation and transcription analyses of the p63 gene in cervical carcinoma

Genetic mutation of p53, which monitors DNA damage and operates cellular checkpoints, is a major factor in the development of human malignancies. A novel gene p63/p73L/p51, encoding a protein with significant homology to p53 and p73, was recently identified at 3q27-9. To investigate the penetration of p63 in cervical carcinogenesis, mutation and transcription analyses of p63 were performed in cervical carcinoma. A certain isotype of p63 called TAp63gamma encodes the acidic N-terminus and possesses a short C-terminus. Using reverse transcriptase-polymerase chain reaction-single strand conformation polymorphism (RT-PCR-SSCP) analysis for TAp63gamma, one mutation was found in the cervical carcinoma cell line SKG-I. However, no mutations causing amino acid substitutions or frameshifts were found in 54 cases examined for TAp63gamma, which is thought to be a tumor suppressor gene. While cervical carcinomas tended to yield a positive signal in the RT-PCR reaction designed to amplify transcripts encoding the acidic N-terminus, normal cervix and cervical intraepithelial neoplasia (CIN) did not express this transcript. These data suggest that the p63 gene does not play an essential role as a tumor suppressor gene, but expression of TAp63gamma may be speculatively associated with tumor growth in cervical carcinogenesis.

Development and evaluation of a new canine myocardial infarction model using a closed-chest injection of thrombogenic material

A new canine myocardial infarction model using thrombi induced by closed-chest injection of thrombin and autogenous blood with fibrinogen into coronary arteries was developed. Occlusive thrombi were formed in all treated animals. Occluded vessels did not spontaneously reperfuse 1 day after occlusion, but did so within 3 days. Infarction was confirmed by increased levels of creatine kinase-MB, glutamate-oxaloacetate transaminase and a-hydroxybutyrate dehydrogenase. Additionally, the left ventricular ejection fraction (LVEF) decreased within 0.5 h after occlusion and had not improved 4 weeks later. After 1 week, extensive transmural anteroinferior myocardial infarction was observed and heart mass had increased. By 4 weeks after occlusion, pulmonary capillary wedge pressure and central venous pressure were increased, and oxygen pressure was decreased. Dropout of nuclei in cardiomyocytes and increased amount of collagen fiber were observed in myocardial infarct regions of hearts excised 4 weeks after occlusion. This canine model may be useful and convenient in evaluating treatment efficacy and the long-term outcome of acute myocardial infarction.

Serological detection of hepatitis B virus genotypes by ELISA with monoclonal antibodies to type-specific epitopes in the preS2-region product

An ELISA was developed for serological determination of the six genotypes of hepatitis B virus (HBV) designated A, B, C, D, E, and F. Monoclonal antibodies were raised against genotype-specific epitopes in the preS2-region product, and labeled with horseradish peroxidase. Hepatitis B surface antigen (HBsAg) in sera was captured by immobilized antibodies against the common determinant, and evaluated for reactivity with genotype-specific monoclonal antibodies labeled with the enzyme. Serological genotyping was in complete accord with genotypes determined by S-gene sequences in a panel of 68 sera containing HBV/HBsAg of different genotypes. Of 514 sera with HBsAg from Japan, 507 (98.6%) were genotyped serologically: genotype A was identified in 24 (4.7%); B in 196 (38.1%); C in 282 (54.9%); D in 2 (0.4%); and F in 3 (0.6%). There were no sera containing HBV of genotype E. Likewise, 425 of 446 (95.3%) sera with HBsAg from Brazil, China, India, Indonesia, Kenya, Korea, Nepal, Papua New Guinea, the Philippines, and Thailand were classified into A (25.6%), B (24.2%), C (33.9%), and D (11.7%) genotypes; there were no sera with HBsAg of genotype E or F among them. Some sera unclassifiable by ELISA revealed mixed infection with HBV of distinct genotypes, or contained HBsAg deprived of genotype-specific epitopes by point mutations. The ELISA would be useful for large-scale surveys, because it allows serological detection of HBV genotypes without sequencing nucleotides.

Antibodies against type II phospholipase A2 prevent renal injury due to ischemia and reperfusion in rats

This study was performed to determine the involvement of type II phospholipase A2 (PLA2-II) in renal injury caused by ischemia and reperfusion. Ischemia and reperfusion significantly elevated levels of blood urea nitrogen and serum creatinine in rats. These increases were significantly reduced by i.v. administration of rabbit IgG F(ab')2 fragments against rat PLA2-II. Increased levels of acid-stable PLA2 activity in the kidney were caused by ischemia and reperfusion, and were suppressed by administration of anti-PLA2-II F(ab')2. Increased levels of myeloperoxidase activity, a marker of neutrophil infiltration, in the kidney were also reduced after anti-PLA2-II F(ab')2 treatment. These results suggest that PLA2-II plays a pivotal role in pathogenesis of ischemia and reperfusion injury through induction of neutrophil infiltration.

An enzyme-linked immunosorbent assay with monoclonal antibodies for the determination of phosphorylated hepatitis B core protein (p21c) in serum

An enzyme-linked immunosorbent assay (ELISA) was developed for the determination of hepatitis B virus (HBV) core protein (p21c) using monoclonal antibody (mAb) directed to a phosphorylated C-terminal amino acid sequence that is not present in hepatitis B e antigen (HBeAg). HBV virions in the test serum were precipitated with horse polyclonal antibody to hepatitis B surface antigen (HBsAg), dissolved with Tween 20 and NaOH, and then neutralized. HBV core protein (p21c), released from HBV cores by this procedure, was sandwiched between immobilized mAb C33 directed to amino acids (aa) 133-140 of the core protein, fixed on a solid support and labeled mAb T2212 that recognizes aa 165-175, only when they are phosphorylated. The method was applied for the detection of phosphorylated p21c in sera from symptom-free carriers and patients with chronic hepatitis. The results indicated a higher extent of phosphorylation in p21c of HBV cores from symptom-free carriers than hepatitis patients.

YM866, a novel modified tissue-type plasminogen activator, affects left ventricular function and myocardial infarct development in dogs with coronary artery thrombi

YM866 is a novel modified tissue-type plasminogen activator (t-PA). Its effects on left ventricular function and myocardial infarct development in dogs with copper coil-induced coronary artery thrombosis were compared with those of a native t-PA, alteplase. YM866 (bolus injection) and alteplase (bolus plus infusion) were administered 15 min after coronary artery occlusion. YM866 and alteplase produced reperfusion in all animals, with a median time to reperfusion of 10 min. In contrast, no reperfusion occurred in the vehicle control group. Left ventricular ejection fraction (LVEF) significantly decreased 15 min after coronary occlusion. YM866 and alteplase improved LVEF 3 hr and 4 hr after administration, respectively, while LVEF did not improve in the vehicle control group. Only slight myocardial infarct areas were observed in both YM866- and alteplase-administered groups, while the area in the vehicle control group accounted for 18.2% of left ventricular myocardial area. In conclusion, although both YM866 and alteplase reperfused occluded coronary arteries, inhibited myocardial infarct development and improved LVEF in dogs with coronary artery thrombi, only a single bolus injection of YM866 was necessary to achieve these improvements. Therefore, YM866 shows promise as an improved clinical agent in treating acute myocardial infarction.

An enzyme-linked immunosorbent assay with monoclonal antibodies for the determination of phosphorylated hepatitis B core protein (p21c) in serum

An enzyme-linked immunosorbent assay (ELISA) was developed for the determination of hepatitis B virus (HBV) core protein (p21c) using monoclonal antibody (mAb) directed to a phosphorylated C-terminal amino acid sequence that is not present in hepatitis B e antigen (HBeAg). HBV virions in the test serum were precipitated with horse polyclonal antibody to hepatitis B surface antigen (HBsAg), dissolved with Tween 20 and NaOH, and then neutralized. HBV core protein (p21c), released from HBV cores by this procedure, was sandwiched between immobilized mAb C33 directed to amino acids (aa) 133-140 of the core protein, fixed on a solid support and labeled mAb T2212 that recognizes aa 165-175, only when they are phosphorylated. The method was applied for the detection of phosphorylated p21c in sera from symptom-free carriers and patients with chronic hepatitis. The results indicated a higher extent of phosphorylation in p21c of HBV cores from symptom-free carriers than hepatitis patients.

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 1: Hemodynamic effects in normal dogs and dogs with acute heart failure

Cardiovascular effects of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine), a calcium channel blocker, were investigated in anesthetized normal dogs and dogs with acute heart failure (AHF), and compared with those of nitroglycerin (NTG). In open-chest anesthetized dogs, NIC (0.1-10 micrograms/kg/min i.v.) dose-dependently increased cardiac output (CO) and coronary blood flow as well as decreased mean blood pressure (MBP). NIC had no effect on heart rate (HR) or maximum rate of rise of left ventricular pressure (max. dp/dt). In contrast (0.1-10 micrograms/kg/min i.v.) decreased MBP, but did not change the other cardiovascular parameters. NIC and NTG did not prolong PQ, QRS or QTc intervals. In addition, NIC was effective in the presence of dobutamine. In the anesthetized dog model of ischemic AHF induced by coronary ligation, and ischemia/angiotensin II-induced AHF, NIC (1 and 3 micrograms/kg/min i.v.) increased CO and stroke volume, and reduced total peripheral resistance without decreasing HR or cardiac contractility. Furthermore, in the ischemia/angiotension II-induced AHF model, NIC decreased left ventricular end-diastolic pressure (LVEDP). In contrast, NTG (1-10 micrograms/kg/min i.v.) decreased LVEDP in both AHF models; but did not increase CO. These results suggest that NIC improves hemodynamics in dogs with AHF mainly by reducing afterload without adversely affecting the cardiac contractility or conduction system, while NTG exerts its effect on AHF by reducing preload. NIC injection would thus appear to be beneficial in the treatment of AHF.

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 2: Effect on myocardial metabolism

The effect of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine) on myocardial metabolism was investigated in an experimental model of ischemic acute heart failure (AHF) induced by coronary ligation in anesthetized dogs. The left anterior descending and/or circumflex coronary ligation decreased coronary sinus blood flow (CBF), maximum rate of rise of left ventricular pressure (max. dp/dt), cardiac output (CO) and stroke volume (SV), and increased left ventricular end-diastolic pressure, indicating the development of AHF. In this ischemic AHF model, NIC (3 micrograms/kg/min i.v. infusion for 15 min) increased CBF, CO and SV, and reduced systemic and coronary artery resistances, resulting in the improvement of AHF. During the effective period, NIC decreased myocardial oxygen consumption and the coronary arterio-venous difference of oxygen content, carbon dioxide pressure and pH. At the same time, NIC did not decrease the lactate extraction. These results suggest that NIC improves hemodynamics and the balance of myocardium oxygen supply and demand in dogs with AHF by means of reducing afterload and dilating coronary artery.

Effects of YM175, a new-generation bisphosphonate, on hypercalcemia induced by tumor-derived bone resorbing factors in rats

YM175 (disodium cycloheptylaminomethylenediphosphonate monohydrate) is a new-generation bisphosphonate with stronger inhibitory activity on bone resorption than first-generation bisphosphonates. In the present study, the effect of YM175 on hypercalcemia induced in rats by single administration of either parathyroid hormone-related protein (PTHrP) or concomitant administration of PTHrP and interleukin 1beta (IL-1beta) was investigated. YM175 (0.01-1 mg/kg, i.v.) inhibited the increase in serum free calcium concentration induced by continuous administration of PTHrP alone (3 microg/rat/day, s.c., 7 days) dose-dependently. The inhibitory effect of YM175 appeared the day after administration and remained 3 days after administration. The effect of YM175 reached a maximum 2 days after administration, at which time the ED50 value of YM175 was calculated to be 0.041 mg/kg, i.v., revealing a potency approximately 50- and 10-fold stronger than those of either pamidronate or alendronate, respectively. In contrast, elcatonin (1-10 units/kg, s.c.) only transiently inhibited PTHrP-induced free calcium increase. YM175 (0.1-3 mg/kg, i.v.) also inhibited the increase in the serum free calcium concentration induced by continuous concomitant administration of both PTHrP and IL-1beta in a dose-dependent manner. These results indicated that YM175 is expected to be a useful drug for hypercalcemia associated with malignant tumors due to its efficacy and range of effect.

A monoclonal antibody against a hepatitis B e antigen epitope borne by six amino acids encoded by the precore region

Hepatitis B e antigen (HBeAg) polypeptide in the circulation (p17e) is composed of ten amino acids (aa) coded for by the precore region and 149 aa by the core gene of hepatitis B virus. A monoclonal antibody (Y0583A) was raised against the N-terminal ten amino acids (SKLCLGWLWG) encoded by the precore region. The binding of Y0583A with a panel of 203 decapeptides on multipins, which covered the precursor of HBeAg polypeptide made of 212 aa shifting by one aa, recognized an epitope sequenced LGWLWG representing the C-terminal six aa coded for by the precore region. This HBeAg epitope was not readily accessible on HBeAg in serum, but it became exposed and bound with Y0583A by treatment with 0.2 N NaOH. Using Y0583A, an enzyme-linked immunosorbent assay was developed for specific determination of HBeAg. The test sample was incubated with the monoclonal antibody to an HBeAg determinant encoded by the core gene (904) that had been immobilized on a solid support. Captured HBeAg was treated with 0.2 N NaOH, neutralized and released into the fluid phase. The reactant was then tested for a sandwich between monoclonal antibody (C33) to the C-terminus of the HBeAg polypeptide immobilized on a solid support and Y0583A labeled with horseradish peroxidase.

[Caregiver burden and subjective health level in primary caregivers of stroke patients]

The purpose of this study was to provide information on the burden and subjective health level experienced by caregivers of stroke patients. We assessed 32 patient/caregiver units attending a day care center, and investigated the characteristics and burden of caregivers. Subjective health level of caregivers was assessed using the Todai Health Index (THI). The functional level of patients was measured according to the Functional Independence Measure (FIM). Of the caregivers, 40.6% expressed a perception of being burdened. The burden of caregivers was associated with economic status, concern for future ability to provide care, and functional levels (ability of toileting, transfer, locomotion) of patients. Mean scale scores of THI did not differ significantly from scores for community women, and was not related to the perception of burden of caregivers. The situation of care for the subjects in this study can be considered to be relatively good. However, for the general caregiver of stroke patients, perception of burden and subjective health level may be affected to a greater extent than seen in this study.

Dopamine D3 and D4 receptor antagonists: synthesis and structure--activity relationships of (S)-(+)-N-(1-Benzyl-3-pyrrolidinyl)-5-chloro-4- [(cyclopropylcarbonyl) amino]-2-methoxybenzamide (YM-43611) and related compounds

In this study, we synthesized a series of (S)-N-(3-pyrrolidinyl)benzamide derivatives, 1, 2a-d, 5a-1, and 7, and their enantiomers, (R)-1 and (R)-5c-e, and evaluated their binding affinity for cloned dopamine D2, D3, and D4 receptors and their inhibitory activity against apomorphine-induced climbing behavior in mice. The results indicate that D2, D3, and D4 receptors have different bulk tolerance (D4 > D3 > D2) for the substituent of the 4-amino group (R1) on the benzamide nuclei and that cyclopropyl-, cyclobutyl-, and cyclopentylcarbonyl groups likely possess adequate bulkiness with respect to D3 and D4 affinity and selectivity over D2 receptors in this series. The results also suggested that the N-substituent (R2) on the pyrrolidin-3-yl group performs an important role in expressing affinity for D2, D3, and D4 receptors and selectivity among the respective subtypes. One of the compounds, (S)-(+)-N-(1-benzyl-3-pyrrolidinyl)-5-chloro-4-[(cyclopropylcarbonyl+ ++) amino]-2-methoxybenzamide (5c) (YM-43611), showed high affinity for D3 and D4 receptors (Ki values of 21 and 2.1 nM, respectively) with 110-fold D4 selectivity and 10-fold D3 preference over D2 receptors and weak or negligible affinity for representative neurotransmitter receptors. Compound 5c displayed potent antipsychotic activity in inhibiting apomorphine-induced climbing behavior in mice (ED50 value, 0.32 mg/kg sc).

In vitro pharmacological profile of YM-43611, a novel D2-like receptor antagonist with high affinity and selectivity for dopamine D3 and D4 receptors

1. We investigated some neurochemical properties of a novel benzamide, YM-43611, [(S)-N-(1-benzyl-3-pyrrolidinyl)-5-chloro-4-cyclopropylcarbonylamino+ ++-2- methoxybenzamide] in comparison with putative D2-like receptor antagonists using both rat and human cloned dopamine D2-like receptors in vitro. 2. Receptor binding studies revealed that YM-43611 had appropriately potent affinities for both rat and human D2-like receptors, with moderate selectivity for D3 receptors and high selectivity for D4 receptors over D2 receptors (Ki values (nM) for rat receptors: D2, 165; D3, 35.5; D4, 1.85, and for human receptors: D2, 42.9; D3, 11.2; D4, 2.10). 3. YM-43611 displayed weak or negligible affinity for other neurotransmitter receptors, namely D1, D5, alpha(1), alpha(2), beta, 5-HT1A, 5-HT2A, 5-HT3, H1, M1 and M2 receptors. 4. Dopamine stimulated low-Km GTPase activity on membranes from Chinese hamster ovary (CHO) cells expressing the human D2-like receptor subtype. This response to dopamine of low-Km GTPase activity was inhibited by use of putative D2-like receptor antagonists. YM-43611 showed a moderate selectivity for D3 receptors (Ki = 45.5 nM) and a high selectivity for D4 receptors (Ki = 3.28 nM) over D2 receptors (Ki = 70.6 nM). 5. Dopamine inhibited forskolin-stimulated adenylate cyclase in intact CHO cells expressing the human D2-like receptor subtype. YM-43611 shifted the inhibition curve of dopamine on respective D2-like receptor subtype-mediated cyclic AMP formation to the right in a parallel fashion, showing a pA2 value of 7.42 (38.1 nM) for D2 receptors, a pKB value of 8.06 (8.68 nM) for D3 receptors, and a pA2 value of 8.42 (3.77 nM) for D4 receptors. 6. YM-43611 but not the other D2-like receptor antagonists exhibited good selectivity with respect to dual antagonism for D3 and D4 receptors in both receptor binding and functional assays. 7. These results indicate that YM-43611 is a novel D2-like receptor antagonist with high potency and selectivity for both D3 and D4 receptors. YM-43611 is therefore expected to be valuable in exploration of the physiological role of D3 and D4 receptors.

YM90K: pharmacological characterization as a selective and potent alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptor antagonist

We investigated the pharmacological properties and neuroprotective actions of a novel alpha-amino-3-hydroxy-5-methylisoxazole-y-propionate (AMPA)/kainate receptor antagonist, [6-(1H-imidazol-1-yl)-7-nitro-2,3-(1H,4H)-quinoxalinedione hydrochloride (YM90K); formerly YM900], in comparison with those of 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (NBQX). YM90K selectively displaced [3H]-AMPA binding (Ki = 0.084 microM) and was less potent in inhibiting [3H]-kainate (Ki = 2.2 microM), [3H]-L-glutamate (N-methyl-D-aspartate-sensitive site; Ki > 100 microM) and [3H]-glycine (strychnine-insensitive site; Ki = 37 microM) binding to rat brain membranes. YM90K co-injected with AMPA or kainate into the rat striatum protected cholinergic neurons against AMPA- or kainate-induced neurotoxicity. YM90K showed potent suppressive activity against audiogenic seizure in DBA/2 mice; ED50 values of YM90K and NBQX against tonic seizure were 2.54 and 7.17 mg/kg (i.p.), respectively. The duration of the anticonvulsant effects of YM90K and NBQX was 30 min, indicating that both compounds possess short action. In a global ischemia model, YM90K (15 mg/kg i.p. x 3), NBQX (30 mg/kg i.p. x 3) and CNQX (60 mg/kg i.p. x 3) significantly prevented the delayed neuronal death in the hippocampal CA1 region in Mongolian gerbils when administered 1 h after 5-min ischemia. In addition, the therapeutic time window for the neuroprotective effect of YM90K (30 mg/kg i.p. x 3) was 6 h. In a focal ischemia model, YM90K (30 mg/kg i.v. bolus+10 mg/kg/h for 4 h) reduced the volume of ischemic damage in the cerebral cortex in F344 rats. Thus, YM90K was shown to be a potent and selective antagonist for AMPA/kainate receptors in vitro and in vivo. This compound may provide a therapeutic effect in various neurodegenerative disorders such as ischemic stroke in which glutamate neurotoxicity is thought to play a critical role in neuronal damage.