[A case of local relapsed rectal cancer responding to low-dose S-1].

We report a case of local recurrent colorectal cancer that has been treated successfully with low-dose oral chemotherapeutic agent. An 80-year-old man underwent a low anterior resection for rectal cancer. Two years and nine months later, a recurrent tumor was revealed in the vicinity of the anastomotic region by colonoscopy. Additional examination by enhanced CT elucidated the tumor infiltrated the sacrum. For this reason, we planned an abdominoperineal resection of rectum with sacrum excision for treatment. However, we considered that he could not overcome the burden of operation for his complication. As a result of informed consent with the patient and his family, we decided a conservative treatment, and started chemotherapy using S-1. The tumor has been diminished slowly on enhanced CT and colonoscopy. The chemotherapy using S-1 has been continued with good quality of life for over five years. S-1 is expected to be an effective choice for the patient of colorectal cancer who cannot be taken the standard treatment for various reasons.

Immunotargeting of apolipoprotein E in amyloid: an initial trial in mice.

Apolipoprotein E is commonly present in systemic amyloid deposits. To investigate the possibility of using apolipoprotein E immunotargeting in the diagnosis and treatment of amyloidosis, we examined whether anti-apolipoprotein E monoclonal antibody was bound to murine amyloid deposits in vivo and whether it influenced amyloidogenesis. This study utilized a radiolabeled monoclonal antibody specific to human apolipoprotein E fragments and human apolipoprotein E-knock-in mice, in which AA amyloidosis was induced. Accumulation of the injected radiolabeled antibody was significantly higher in the organs of amyloidotic mice than in those of non-amyloidotic mice. Plasma clearance of the antibody did not differ between the amyloidotic and non-amyloidotic mice. The antibody was given to mice during amyloid induction but failed to prevent amyloidogenesis. The results of this initial study are encouraging, but considerable improvement is necessary, particularly in regard to development of a high affinity antibody.

A 1 GHz integrated circuit with carbon nanotube interconnects and silicon transistors.

Due to their excellent electrical properties, metallic carbon nanotubes are promising materials for interconnect wires in future integrated circuits. Simulations have shown that the use of metallic carbon nanotube interconnects could yield more energy efficient and faster integrated circuits. The next step is to build an experimental prototype integrated circuit using carbon nanotube interconnects operating at high speed. Here, we report the fabrication of the first stand-alone integrated circuit combining silicon transistors and individual carbon nanotube interconnect wires on the same chip operating above 1 GHz. In addition to setting a milestone by operating above 1 GHz, this prototype is also a tool to investigate carbon nanotubes on a silicon-based platform at high frequencies, paving the way for future multi-GHz nanoelectronics.

Tau phosphorylation in the mouse brain during aversive conditioning.

Stress response is intimately involved in memory formation. Stress has been shown to cause reversible Alzheimer-like tau phosphorylation in the brain of experimental animals, but it is not known whether tau phoshorylation takes place during memory acquisition. As an initial investigation we chose contextual fear conditioning paradigm involving electric shocks, and studied tau phosphorylation in the hippocampus and a neighboring limbic region of the mouse brain. Quantitative immunoblot analyses of tissue extracts rapidly prepared from animals undergoing the conditioning showed statistically significant increases in the phosphorylation level at Thr231/Ser235 of tau in both tissues. The reaction reached statistical significance after 10 but not 3 shocks of 0.8mA. Ten shocks of 0.2mA were ineffective. Concurrent increases in phosphorylation of protein kinase TPKI/GSK3beta at Ser9 and of CaMKIIalpha at Thr286 were observed. These results suggest involvement of tau and TPKI/GSK3beta phosphorylation in an early phase of memory formation in the hippocampus and amygdala, raising a possibility that a dysregulation of tau phosphorylation may underlie memory impairment in incipient Alzheimer's disease.

Novel action of apolipoprotein E (ApoE): ApoE isoform specifically inhibits lipid-particle-mediated cholesterol release from neurons.

BACKGROUND: Since the majority of apolipoprotein E (apoE) existing in the cerebrospinal fluid is associated with high-density lipoprotein (HDL), one should focus on the role of the apoE-HDL complex rather than on that of free apoE in cholesterol metabolism in the central nervous system. However, the apoE-isoform-specific effect of apoE-HDL on cholesterol transport remains unclarified. RESULTS: Here we show that apoE3-HDL induced a marked cholesterol release from neurons, while apoE4-HDL induced little. To elucidate the mechanism underlying this phenomenon, we used a complex of lipid emulsion (EM) with recombinant apoE3 or apoE4 (apoE-EM) at various apoE concentrations. When a small number of apoE molecules were associated with EM, apoE3- and apoE4-EM, induced a marked cholesterol release to a level similar to that induced by EM alone. However, when apoE at given concentrations was incubated with EM, apoE3-EM induced a marked cholesterol release, while apoE4-EM induced little. Under these conditions, a greater number of apoE4 molecules were associated with EM than apoE3 molecules. When an increasing number of apoE molecules were associated with EM, both apoE3-EM and apoE4-EM induced little cholesterol release. Preincubation with beta-mercaptoethanol increased the number of apoE3 molecules associated with EM similar to that of apoE4 molecules, indicating that the presence (apoE3) or absence (apoE4) of intermolecular disulfide bond formation is responsible for the association of a greater number of apoE4 molecules to EM than apoE3 molecules. CONCLUSION: These results suggest that although apoE and a lipid particle are lipid acceptors, when apoE and a lipid particle form a complex, apoE on the particle surface inhibits the lipid particle-mediated cholesterol release from cells in an apoE-concentration-dependent manner.

Effects of human apolipoprotein E isoforms on the amyloid beta-protein concentration and lipid composition in brain low-density membrane domains.

Apolipoprotein E4 (apoE4) encoded by epsilon 4 allele is a strong genetic risk factor for Alzheimer's disease (AD). ApoE4 carriers have accelerated amyloid beta-protein (A beta) deposition in their brains, which may account for their unusual susceptibility to AD. We hypothesized that the accelerated A beta deposition in the brain of apoE4 carriers is mediated through cholesterol-enriched low-density membrane (LDM) domains. Thus, the concentrations of A beta and various lipids in LDM domains were quantified in the brains of homozygous apoE3 and apoE4 knock-in (KI) mice, and in the brains of those mice bred with beta-amyloid precursor protein (APP) transgenic mice (Tg2576). The A beta 40 and A beta 42 concentrations and the A beta 42 proportions in LDM domains did not differ between apoE3 and apoE4 KI mice up to 18 months of age. The A beta 40 concentration in the LDM domains was slightly, but significantly higher in apoE3/APP mice than in apoE4/APP mice. The lipid composition of LDM domains was modulated in an apoE isoform-specific manner, but its significance for A beta deposition remains unknown. These data show that the apoE isoform-specific effects on the A beta concentration in LDM domains do not occur in KI mouse models.

Ether stress-induced Alzheimer-like tau phosphorylation in the normal mouse brain.

Tau is reversibly hyperphosphorylated in the mouse brain by starvation or cold water swimming. Here, we report tau phosphorylation in the hippocampus of normal mouse after ether anesthesia, known to trigger typical stress reactions. Robust phosphorylation of tau was observed immediately and 10min after ether vapor exposure at Ser202/Thr205 and Thr231/Ser235, sites typically phosphorylated in Alzheimer brains. The phosphorylation levels returned to baseline by 1h. The most conspicuous and consistent change in the protein kinases studied was the inactivating phosphorylation of Ser9 of TPKI/GSK3beta in close correspondence with tau phosphorylation. These findings show that tau phosphorylation is a rapid physiological process integral to stress response system, and suggest involvement therein of TPKI/GSK3beta.

Producing cluster states in charge qubits and flux qubits.

We propose a method to efficiently generate cluster states in charge qubits, both semiconducting and superconducting, as well as flux qubits. We show that highly entangled cluster states can be realized by a "one-touch" entanglement operation by tuning gate bias voltages for charge qubits. We also investigate the robustness of these cluster states for nonuniform qubits, which are unavoidable in solid-state systems. We find that quantum computation based on cluster states is a promising approach for solid-state qubits.

Molecular control of spinal accessory motor neuron/axon development in the mouse spinal cord.

Within the developing vertebrate spinal cord, motor neuron subtypes are distinguished by the settling positions of their cell bodies, patterns of gene expression, and the paths their axons follow to exit the CNS. The inclusive set of cues required to guide a given motor axon subtype from cell body to target has yet to be identified, in any species. This is attributable, in part, to the unavailability of markers that demarcate the complete trajectory followed by a specific class of spinal motor axons. Most spinal motor neurons extend axons out of the CNS through ventral exit points. In contrast, spinal accessory motor neurons (SACMNs) project dorsally directed axons through lateral exit points (LEPs), and these axons assemble into the spinal accessory nerve (SAN). Here we show that an antibody against BEN/ALCAM/SC1/DM-GRASP/MuSC selectively labels mouse SACMNs and can be used to trace the pathfinding of SACMN axons. We use this marker, together with a battery of transcription factor-deficient or guidance cue/receptor-deficient mice to identify molecules required for distinct stages of SACMN development. Specifically, we find that Gli2 is required for the initial extension of axons from SACMN cell bodies, and that netrin-1 and its receptor Dcc are required for the proper dorsal migration of these cells and the dorsally directed extension of SACMN axons toward the LEPs. Furthermore, in the absence of the transcription factor Nkx2.9, SACMN axons fail to exit the CNS. Together, these findings suggest molecular mechanisms that are likely to regulate key steps in SACMN development.

Age-dependent enhancement of hippocampal long-term potentiation in knock-in mice expressing human apolipoprotein E4 instead of mouse apolipoprotein E.

Human apolipoprotein E (apoE) comprises three isoforms, apoE2, apoE3 and apoE4, and apoE4 has been reported as a risk factor of Alzheimer's disease (AD). One of the clinical symptoms of AD is disorder of memory that has been suggested to be related with synaptic plasticity such as long-term potentiation (LTP). Here, we show the enhancement of hippocampal LTP at younger age in knock-in mice lacking mouse apoE, but instead expressing human apoE4. The enhancement of LTP in apoE4 knock-in mice is age-dependent, and it disappears in adult apoE4 knock-in mice. In apoE3 knock-in mice LTP is unaltered, thus human apoE4, but not apoE3, specifically modulates synaptic plasticity at younger age. Since basal synaptic transmission and distribution of glutamate receptors, as well as presynaptic functions, are intact in apoE4 knock-in mice, postsynaptic functional modification of LTP through lipid homeostasis is suggested. ApoE4 knock-in mice would be a useful animal model of human apoE4 carriers, and our finding that LTP is enhanced in younger apoE4 knock-in mice is in accord with the previous report showing higher intelligence in young human apoE4 carriers.

Phosphorylated alpha-synuclein in normal mouse brain.

alpha-Synuclein phosphorylated at Ser129 is the main component of Lewy bodies of Parkinson's and closely related diseases. We studied, by quantitative immunoblotting, changes in the phosphorylation level of alpha-synuclein in the mouse brains subjected to cold water stress. Relative basal level of alpha-synuclein phosphorylation at Ser129 was 40% higher in the striatum compared with the hippocampus. The phosphorylation level decreased to 57% in the striatum 20 min after 5 min of cold water stress, and also in the hippocampus and cortex to lesser degrees. Recovery to basal levels took place over several hours. The stress-induced temporary dephosphorylation was of smaller magnitude in the striatum of aged (18 months) mice. These results show that alpha-synuclein phosphorylation level at Ser129 in vivo responds to physiological stimuli. Relative prominence and age sensitivity of this phenomenon in the striatum may be relevant to the pathogenesis of Parkinson's disease.

Accelerated Abeta aggregation in the presence of GM1-ganglioside-accumulated synaptosomes of aged apoE4-knock-in mouse brain.

Aging and apolipoprotein E4 (apoE4) expression are strong risk factors for the development of Alzheimer's disease (AD); however, their pathological roles remain to be clarified. In the process of AD development, the conversion of the nontoxic amyloid beta-protein (Abeta) monomer to its toxic aggregates is a fundamental process. We previously hypothesized that Abeta aggregation is accelerated through the generation of GM1 ganglioside (GM1)-bound Abeta which acts as a seed for Abeta fibril formation. Here we report that GM1 level in detergent-resistant membrane microdomains (DRMs) of synaptosomes increased with age and that this increase was significantly pronounced in the apoE4- than the apoE3-knock-in mouse brain. Furthermore, we show that Abeta aggregation is markedly accelerated in the presence of the synaptosomes of the aged apoE4-knock-in mouse brain. These observations suggest that aging and apoE4 expression cooperatively accelerate Abeta aggregation in the brain through an increase in the level of GM1 in neuronal membranes.

Independent effects of APOE on cholesterol metabolism and brain Abeta levels in an Alzheimer disease mouse model.

The APOE epsilon4 allele is the most significant genetic risk factor associated with Alzheimer's disease to date. Epidemiological studies have demonstrated that inheritance of one or more epsilon4 alleles affects both the age of onset and the severity of pathology development. Dosage of APOE epsilon2 and epsilon3 alleles, however, appear to be protective against the effects of epsilon4. Although much of the biology of APOE in peripheral cholesterol metabolism is understood, its role in brain cholesterol metabolism and its impact on AD development is less defined. Several APOE transgenic models have been generated to study the effects of APOE alleles on APP processing and Abeta pathology. However, these models have potential limitations that confound our understanding of the effects of apolipoprotein E (APOE) levels and cholesterol metabolism on disease development. To circumvent these limitations, we have taken a genomic-based approach to better understand the relationship between APOE alleles, cholesterol and Abeta metabolism. We have characterized APOE knock-in mice, which express each human allele under the endogenous regulatory elements, on a defined C57BL6/J background. These mice have significantly different serum cholesterol levels and steady-state brain APOE levels, and yet have equivalent brain cholesterol levels. However, the presence of human APOE significantly increases brain Abeta levels in a genomic-based model of AD, irrespective of genotype. These data indicate an independent role for APOE in cholesterol metabolism in the periphery relative to the CNS, and that the altered levels of cholesterol and APOE in these mice are insufficient to influence Abeta metabolism in a mouse model of Alzheimer's disease.

Augmented delayed infarct expansion and reactive astrocytosis after permanent focal ischemia in apolipoprotein E4 knock-in mice.

Using homozygous human apolipoprotein E2 (apoE2) (2/2)-, apoE3 (3/3)-, or apoE4 (4/4)-knock-in (KI) mice, we aimed to examine whether an apoE isoform-specific exacerbation of delayed infarct expansion occurs after permanent middle cerebral artery occlusion (pMCAO). Compared with 2/2- or 3/3-KI mice, 4/4-KI mice exhibited significantly larger infarct volumes and worse neurologic deficits after pMCAO, with no significant differences between the latter two groups. Infarct volume in 4/4-KI mice was significantly increased from 1 to 5 days after pMCAO, whereas that in 2/2- or 3/3-KI mice was not significantly altered. DNA fragmentation in the peri-infarct area as detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphatenick end-labeling was increased to a similar degree in all of the KI mice by 5 days after pMCAO, with no significant differences among the mouse groups. At every time-point examined, human apoE was most markedly expressed in the peri-infarct area, with similar immunoreactivity among the three lines of KI mice. The glial fibrillary acidic protein immunoreactive burden in the peri-infarct area was progressively increased through 7 days in 4/4-KI mice, but not in 2/2- or 3/3-KI mice. Taken together, these data show that the apoE4 isoform acts to aggravate delayed infarct expansion and peri-infarct reactive astrocytosis during the subacute phase of pMCAO in genetically engineered apoE-KI mice.

MuSC is involved in regulating axonal fasciculation of mouse primary vestibular afferents.

Regulation of axonal fasciculation plays an important role in the precise patterning of neural circuits. Selective fasciculation contributes to the sorting of different types of axons and prevents the misrouting of axons. However, axons must defasciculate once they reach the target area. To study the regulation of fasciculation, we focused on the primary vestibulo-cerebellar afferents (PVAs), which show a dramatic change from fasciculated axon bundles to defasciculated individual axons at their target region, the cerebellar primordium. To understand how fasciculation and defasciculation are regulated in this system, we investigated the roles of murine SC1-related protein (MuSC), a molecule belonging to the immunoglobulin superfamily. We show: (i) by comparing 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil) labelling and anti-MuSC immunohistochemistry, that downregulation of MuSC in PVAs during development is concomitant with the defasciculation of PVA axons; (ii) in a binding assay with cells expressing MuSC, that MuSC has cell-adhesive activity via a homophilic binding mechanism, and this activity is increased by multimerization; and (iii) that MuSC also displays neurite outgrowth-promoting activity in vestibular ganglion cultures. These findings suggest that MuSC is involved in axonal fasciculation and its downregulation may help to initiate the defasciculation of PVAs.

A ferredoxin Arg-Glu pair important for efficient electron transfer between ferredoxin and ferredoxin-NADP(+) reductase.

In order to elucidate the importance of a ferredoxin (Fd) Arg-Glu pair involved in dynamic exchange from intra- to intermolecular salt bridges upon complex formation with ferredoxin-NADP(+) oxidoreductase (FNR), Equisetum arvense FdI and FdII were investigated as normal and the pair-lacking Fd, respectively. The FdI mutant lacking this pair was unstable and rapidly lost the [2Fe-2S] cluster. The catalytic constant (k(cat)) of the electron transfer for FdI is 5.5 times that for FdII and the introduction of this pair into FdII resulted in the increase of k(cat) to a level comparable to that for FdI, demonstrating directly that the Arg-Glu pair is important for efficient electron transfer between Fd and FNR.

Phosphorylation state of tau in the hippocampus of apolipoprotein E4 and E3 knock-in mice.

The apolipoprotein E (apoE) epsilon 4 allele is associated with an increased risk of sporadic as well as late-onset familial Alzheimer's disease (AD). To accurately determine the isoform-specific effects of human apoE on AD-like phosphorylation of tau, hippocampi from human apoE knock-in (KI) mice were studied by quantitative immunoblotting. There was no significant difference in phosphorylation levels of tau at nine of the 13 epitopes, for six of eight tau kinases, or in protein levels of three tau phosphatases, between apoE3-KI and apoE4-KI mouse hippocampi. However, in apoE4-KI mice, phosphorylation of tau at Ser235 was increased to approximately 150%, that at Ser413 to approximately 140%, while that at Ser202/Thr205 and Thr205 were decreased to approximately 70%, and the protein level of tau protein kinase I/glycogen synthase kinase 3beta (TPKI/GSK3beta) was increased to approximately 120%, that of extracellular signal-regulated kinase 2 (ERK2) was increased to approximately 130%, compared with apoE3-KI mice.

Increased vulnerability to focal ischemic brain injury in human apolipoprotein E4 knock-in mice.

Accumulating evidence suggests that among the 3 human apolipoprotein E (apoE) isoforms encoded by the human APOE gene, the e4 allele may act to exacerbate brain damage in humans and animals. This study aimed to compare the isoform-specific vulnerability conferred by human apoE to ischemic brain damage, using mice expressing human apoE isoforms (apoE2, apoE3, or apoE4) in place of mouse apoE, produced by the gene-targeting technique in embryonic stem cells (knock-in, KI). Homozygous human apoE2 (2/2), apoE3 (3/3), or apoE4 (4/4) KI mice were subjected to permanent focal cerebral ischemia by a modified intraluminal suture method. Twenty-four h thereafter, brain damage, (as estimated by infarct volume and neurologic deficit) was significantly worse in 4/4 KI mice versus 2/2 or 3/3 KI mice (p < 0.001 for each comparison), with no significant differences between 2/2 and 3/3 KI mice. Immunohistochemistry for human apoE expression revealed similar apoE distribution with no significant difference in the immunostaining intensity among the 3 lines of KI mice. Notably. increased expression of human apoE was detected in neurons and astrocytes in the peri-infarct area, and a punctate expression pattern was evident in the border between the infarct and peri-infarct areas in all KI mice subjected to ischemia. Taken together, our results show that apoE affects the outcome of acute brain damage in an isoform-specific fashion (apoE4 > apoE3 = apoE2) in genetically engineered mice.

Stress-induced hyperphosphorylation of tau in the mouse brain.

We previously showed that starvation causes reversible hyperphosphorylation of tau in the mouse brain. To explore possible involvement of stress in tau hyperphosphorylation quantitative analysis of phosphorylated tau in four brain regions of mice subjected to cold water stress (CWS) was made by immunoblot analyses using phosphorylation-dependent antibodies directed to eight sites on tau known to be hyperphosphorylated in the brain of Alzheimer's disease (AD) patients. Ser199, Ser202/Thr205, Thr231/Ser235 were hyperphosphorylated 20 and 40 min after CWS. The response was pronounced in the hippocampus and cerebral hemisphere, but weak in the cerebellum in parallel with the regional vulnerability in AD. Among the regulatory phosphorylation of protein kinases studied, a transient phosphorylation of tau protein kinase I/glycogen synthase kinase 3beta at Ser9 was most conspicuous.