Activation of insular cortex and subcortical regions related to feedback stimuli in a time estimation task: an fMRI study

We used functional magnetic resonance imaging to investigate brain activity related to motivational function of informative feedback stimuli in a time estimation task. In that task, subjects pressed a button as a response 3 s after a cue stimulus; a visual feedback stimulus was presented 2 s after the response. In a true feedback condition, subjects received true information (informative feedback) about their time-estimation performance. In the false feedback condition, the same visual signs were used, but they were presented randomly. Therefore, they were not related to actual performance. In the 20 subjects examined, higher hemodynamic responses were identified in the insular cortex, the thalamus, and the striatum by comparing the true feedback condition to the false feedback condition. The time estimation performance and subjective score on motivation were also markedly higher in the true feedback condition. The anterior insular cortex and striatal regions are known to be involved in motivational and reward processing. Therefore, the hemodynamic responses observed in this study suggest that the motivational function of the feedback information is a crucial factor for behavioral learning; it is considered that the informative feedback might serve as an implicit reward for humans.     

Mutation spectrum in UVB-exposed skin epidermis of a mildly-affected Xpg-deficient mouse

A C-terminal 183 amino acid-truncated mutation of the mouse Xpg gene (XpgDeltaex15) gives rise to a partial deficiency in nucleotide excision repair in homozygously affected cells. We studied the effect of this mutation on UVB-induced mutagenesis in mouse skin, using transgenic mice harboring lambda-phage-based bacterial lacZ genes as a mutational reporter. UVB increased the lacZ mutant frequency in the epidermis moderately in the homozygous mutant mice, but significantly higher than in the wild-type or the heterozygous mice, whereas background mutant frequencies were not appreciably different among the three mouse genotypes. Ninety-eight lacZ mutant sequences isolated from the UVB-exposed epidermis of the XpgDeltaex15-homozygous mice were analyzed and compared with mutant sequences from the wild-type mice. The spectra of the mutations in the two mouse genotypes were not significantly different, and they were highly UV-specific. There were frequent C --> T transitions at dipyrimidine sites and several CC --> TT tandem mutations, although the UV-specific mutations occurred more frequently at CpG sites in the mutant mice. The distribution of the mutations observed in the lacZ transgene and the preferred sequence context of the UV-specific C --> T mutations (5'-TC-3' > 5'-CC-3' > 5'-CT-3') in the Xpg-mutant mice were similar to those found in the wild-type mice. Despite these similarities, we detected a previously unrecognized type of the UV-induced mutation only in the Xpg mutant (6/98 in the mutation spectrum of the mutant vs. 0/76 in the wild-type; P = 0.035), which is characterized by multiple base substitutions or frameshifts within a three-nucleotide sequence containing a dipyrimidine. We propose that this putative new class of mutation, which we refer to as a "triplet mutation", is characteristic of UV-induced mutation in an excision-repair-deficient background.     

A phase I study of oral uracil-tegafur prior to weekly intravenous gemcitabine in patients with advanced pancreatic cancer

BACKGROUND: Gemcitabine is widely accepted as the first-line agent for advanced pancreatic cancer. The antitumor cell activity of gemcitabine is higher when administered after 5-fluorouracil (5-FU) rather than before 5-FU in an in vitro study. The present study was conducted to define the maximum tolerated dose and dose-limiting toxicity associated with an oral fluoropyrimidine prodrug that combines uracil and tegafur (UFT), given prior to weekly intravenous gemcitabine in patients with advanced pancreatic cancer. METHODS: Over a 21-day cycle, gemcitabine was given intravenously over 30 min on days 8 and 15, while UFT was given orally from days 1 to 14. The dose of UFT used was 400 mg per day, given as two doses. The dose of gemcitabine was escalated in a stepwise fashion from 800 (level 1, n = 3) to 900 mg/m2 (level 2, n = 6) and then to 1,000 mg/m2 (level 3, n = 3), such that totally 12 patients received the combination chemotherapy. RESULTS: During the first cycle, grade 3 leukopenia was observed in 2 patients at dose level 1. Only 1 patient treated at dose level 2 experienced dose-limiting toxicity (grade 3 elevated transaminase), including additional patients treated at this dose level. No grade 3/4 toxicities occurred in patients treated at dose level 3. A significant response was observed in 1 out of 12 patients (8.3%). Seven patients (58.3%) had stable disease, while 4 patients (33.3%) showed disease progression. CONCLUSIONS: The combination chemotherapy of oral UFT and gemcitabine was convenient, well tolerated and may benefit patients with advanced pancreatic cancer. Doses recommended for further study of this schedule are gemcitabine 1,000 mg/m2 and UFT 400 mg/day.     

Endothelial progenitor thrombospondin-1 mediates diabetes-induced delay in reendothelialization following arterial injury

Delayed reendothelialization contributes to restenosis after angioplasty and stenting in diabetes. Prior data have shown that bone marrow (BM)-derived endothelial progenitor cells (EPCs) contribute to endothelial recovery after arterial injury. We investigated the hypothesis that the EPC contribution to reendothelialization may be impaired in diabetes, resulting in delayed reendothelialization. Reendothelialization was significantly reduced in diabetic mice compared with nondiabetic mice in a wire-induced carotid denudation model. The EPC contribution to neoendothelium was significantly reduced in Tie2/LacZ BM-transplanted diabetic versus nondiabetic mice. BM from diabetic and nondiabetic mice was transplanted into nondiabetic mice, revealing that reendothelialization was impaired in the recipients of diabetic BM. To examine the relative roles of denuded artery versus EPCs in diabetes, we injected diabetic and nondiabetic EPCs intravenously after arterial injury in diabetic and nondiabetic mice. Diabetic EPCs recruitment to the neoendothelium was significantly reduced, regardless of the diabetic status of the recipient mice. In vitro, diabetic EPCs exhibited decreased migration and adhesion activities. Vascular endothelial growth factor and endothelial NO synthase expressions were also significantly reduced in diabetic EPCs. Notably, thrombospondin-1 mRNA expression was significantly upregulated in diabetic EPCs, associating with the decreased EPC adhesion activity in vitro and in vivo. Reendothelialization is impaired by malfunctioning EPCs in diabetes. Diabetic EPCs have phenotypic differences involving thrombospondin-1 expression compared with nondiabetic EPCs, revealing potential novel mechanistic insights and therapeutic targets to improve reendothelialization and reduce restenosis in diabetes.     

Effect of repetitive transcranial magnetic stimulation applied over the premotor cortex on somatosensory-evoked potentials and regional cerebral blood flow

Somatosensory-evoked potentials (SEPs) are attenuated by movement. This phenomenon of 'gating' reflects sensorimotor integration for motor control. The frontal N30 component after median nerve stimulation was shown to be reduced in amplitude prior to hand movement. To investigate the mechanism of this sensory gating, we recorded median SEPs immediately before and after application of monophasic very low-frequency (0.2 Hz) repetitive transcranial magnetic stimulation (rTMS) of 250 stimuli over motor cortex (MC), premotor cortex (PMC), or supplementary motor area (SMA) in 9 healthy volunteers. The stimulus intensity for MC or PMC was set 85% of the resting motor threshold for the hand muscle, and that for SMA was at the active motor threshold for the leg muscle. SEPs showed significant increases in amplitudes of the frontal N30 component after PMC stimulation, but not after SMA or MC stimulation. Low-frequency (1 Hz) biphasic stimulation over PMC showed no significant N30 changes in 6 out of 9 subjects tested, indicating the effect being specific for 0.2 Hz monophasic stimulation. To examine the functional anatomy of the N30 change, single photon emission computed tomography was performed immediately before and after monophasic 0.2 Hz rTMS over PMC in all the 9 subjects. Regional cerebral blood flow showed significant increases mainly in PMC and prefrontal cortex, indicating the involvement of these cortical areas in sensory input gating for motor control.     

An association study of asthma and related phenotypes with polymorphisms in negative regulator molecules of the TLR signaling pathway

Although associations between endotoxin exposure or respiratory infection and asthma have been recognized, the genetic effects in these conditions are unclear. Toll-like receptors (TLRs) play an essential role in innate host defense and in the control of adaptive immune responses. IL-1R-associated kinase-M (IRAK-M) and single immunoglobulin IL-1R-related molecule (SIGIRR) negatively regulate TLR-signaling pathways. To investigate whether polymorphisms in these genes were associated with asthma or asthma-related phenotypes, we screened these genes for polymorphisms by direct sequencing of 24 asthmatics and identified 19 variants in IRAK-M and 12 variants in SIGIRR. We next conducted linkage disequilibrium mapping of the genes, and examined the association of polymorphisms and haplotypes using 391 child patients with asthma, 462 adult patients with asthma, and 639 controls. None of the alleles or haplotypes of IRAK-M and SIGIRR were associated with asthma susceptibility or asthma-related phenotype. Our results indicate that polymorphisms in IRAK-M and SIGIRR are not likely to be associated with the development of asthma in the Japanese population.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Association of VKORC1 and CYP2C9 polymorphisms with warfarin dose requirements in Japanese patients

Warfarin is the most commonly used oral anticoagulant for treatment of thromboembolism, but adjustment of the dose appropriate to each patient is not so easy because of the large inter-individual variation in dose requirement. We analyzed single nucleotide polymorphism (SNP) genotypes of the VKORC1 and CYP2C9 genes using DNA from 828 Japanese patients treated with warfarin, and investigated association between SNP genotype and warfarin-maintenance dose. Five SNPs in VKORC1, 5 flanking–1413A>G, intron 1–136T>C, intron 2+124C>G, intron 2+837T>C and exon 3 343G>A, were in absolute linkage disequilibrium, and showed a significant association with daily warfarin dose of these patients. The median warfarin dose of patients with homozygosity for the minor allele was 4.0 mg/day, which is significantly higher than those heterozygous for the minor allele (3.5 mg/day) or those homozygous for the major allele (2.5 mg/day; P=5.1×10^–11 in the case of intron 1–136T>C SNP). We then genotyped the CYP2C9 gene for the Japanese common genetic variant, CYP2C9*3 and, based on the genotype of these two genes, classified patients into three categories, which we call warfarin-responsive index. The median warfarin daily dose varied significantly in this classification according to the warfarin-responsive index (2.0 mg/day for index 0 group, 2.5 mg/day for index 1 group, and 3.5 mg/day for index 2 group; P=4.4×10^–13). Thus, analysis of the combination of VKORC1 and CYP2C9 genotypes should identify warfarin-sensitive patients who require a lower dose of drug, allowing personalized warfarin treatment.