Wataru Matsumoto

Analysis Of Htlv-I Proviral Load In 202 Ham/Tsp Patients And 243 Asymptomatic Htlv-I Carriers: High Proviral Load Strongly Predisposes To Ham/Tsp

In order to examine the effect of HTLV-I proviral load on the pathogenesis of HAM/TSP, we measured the HTLV-I proviral load in peripheral blood mononuclear cells (PBMC) from a large number of HAM/TSP patients and asymptomatic HTLV-I carriers. To measure the proviral load, we used an accurate and reproducible quantitative PCR method using a dual-labeled fluorogenic probe (ABI PRISM 7700 Sequence Detection System). The mean + standard error of mean (s.e.m.) HTLV-I proviral copy number per 1 × 104 PBMC was 798 ±51 (median 544) in 202 HAM/TSP patients; 120 ± 17 (median 34) in 200 non HAM-related (general) asymptomatic HTLV-I carriers (RC); and 496 ± 82 (median 321) in 43 asymptomatic HTLV-I carriers genetically related to HAM/TSP patients (FA). The prevalence of HAM/TSP rises exponentially with log (proviral load) once the proviral load exceeds 1% PBMC. The HTLV-I proviral load of female patients with HAM/TSP was significantly higher than that of male patients, however there was no significant difference in p...

Circuit topology for synchronizing neurons in spontaneously active networks

Spike synchronization underlies information processing and storage in the brain. But how can neurons synchronize in a noisy network? By exploiting a high-speed (500–2,000 fps) multineuron imaging technique and a large-scale synapse mapping method, we directly compared spontaneous activity patterns and anatomical connectivity in hippocampal CA3 networks ex vivo. As compared to unconnected pairs, synaptically coupled neurons shared more common presynaptic neurons, received more correlated excitatory synaptic inputs, and emitted synchronized spikes with approximately 107 times higher probability. Importantly, common presynaptic parents per se synchronized more than unshared upstream neurons. Consistent with this, dynamic-clamp stimulation revealed that common inputs alone could not account for the realistic degree of synchronization unless presynaptic spikes synchronized among common parents. On a macroscopic scale, network activity was coordinated by a power-law scaling of synchronization, which engaged varying sets of densely interwired (thus highly synchronized) neuron groups. Thus, locally coherent activity converges on specific cell assemblies, thereby yielding complex ensemble dynamics. These segmentally synchronized pulse packets may serve as information modules that flow in associatively parallel network channels.

Different Cytokine Production in Tax-Expressing Cells between Patients with Human T Cell Lymphotropic Virus Type I (HTLV-I)–Associated Myelopathy/Tropical Spastic Paraparesis and Asymptomatic HTLV-I Carriers

Human T cell lymphotropic virus type I (HTLV-I) provirus load has been reported to be generally higher in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) than in asymptomatic HTLV-I carriers (ACs). However, some ACs have a high HTLV-I provirus load comparable with that in patients with HAM/TSP. To examine whether other factors influence the outcome of HTLV-I infection in patients with HAM/TSP and ACs, we analyzed spontaneous Tax expression and cytokine production in peripheral blood mononuclear cells using flow cytometry. The Tax expression in HTLV-I-infected cells (percentage of Tax expressing cells/HTLV-I provirus load when assumed 1 copy/cell) and the intensity of Tax expression did not differ between these 2 groups. However, the production of interferon-gamma and tumor necrosis factor-alpha in Tax-expressing cells was significantly lower in ACs with high HTLV-I provirus load than in patients with HAM/TSP. This result suggests that the production of inflammatory cytokines in Tax-expressing cells is one of the factors that contribute to the development of HAM/TSP.

Active hippocampal networks undergo spontaneous synaptic modification.

The brain is self-writable; as the brain voluntarily adapts itself to a changing environment, the neural circuitry rearranges its functional connectivity by referring to its own activity. How the internal activity modifies synaptic weights is largely unknown, however. Here we report that spontaneous activity causes complex reorganization of synaptic connectivity without any external (or artificial) stimuli. Under physiologically relevant ionic conditions, CA3 pyramidal cells in hippocampal slices displayed spontaneous spikes with bistable slow oscillations of membrane potential, alternating between the so-called UP and DOWN states. The generation of slow oscillations did not require fast synaptic transmission, but their patterns were coordinated by local circuit activity. In the course of generating spontaneous activity, individual neurons acquired bidirectional long-lasting synaptic modification. The spontaneous synaptic plasticity depended on a rise in intracellular calcium concentrations of postsynaptic cells, but not on NMDA receptor activity. The direction and amount of the plasticity varied depending on slow oscillation patterns and synapse locations, and thus, they were diverse in a network. Once this global synaptic refinement occurred, the same neurons now displayed different patterns of spontaneous activity, which in turn exhibited different levels of synaptic plasticity. Thus, active networks continuously update their internal states through ongoing synaptic plasticity. With computational simulations, we suggest that with this slow oscillation-induced plasticity, a recurrent network converges on a more specific state, compared to that with spike timing-dependent plasticity alone.

Longer dinucleotide repeat polymorphism in matrix metalloproteinase-9 (MMP-9) gene promoter which correlates with higher HTLV-I Tax mediated transcriptional activity influences the risk of HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Matrix metalloproteinase-9 (MMP-9) has been reported to be expressed in various inflammatory disorders including human T cell lymphotropic virus type I (HTLV-I) associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-I-infected T-cells expressed high levels of MMP-9 via viral transactivator Tax mediated activation of the MMP-9 promoter. To investigate whether the d(CA) repeat polymorphism in MMP-9 promoter affects the risk of developing HAM/TSP, we compared the allele frequencies between 200 HAM/TSP patients and 200 HTLV-I seropositive asymptomatic carriers (HCs). The longer d(CA) repeat alleles of MMP-9 promoter, which was associated with higher Tax-mediated transcriptional activity, was more frequently observed in HAM/TSP patients than HCs (p<0.01 by Mann-Whitney U-test). The length alteration of this d(CA) repeat in the MMP-9 promoter may cause phenotypic differences among HTLV-I infected infiltrating cells and may thereby be in part responsible for the development of HAM/TSP.

ApaI polymorphism of vitamin D receptor gene is associated with susceptibility to HTLV-1-associated myelopathy/tropical spastic paraparesis in HTLV-1 infected individuals

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is one outcome of human T-cell lymphotropic virus type-1 (HTLV-1) infection. It remains unknown why the majority of infected people remain healthy, whereas only approximately 2-3% of infected individuals develop the disease. The active form of vitamin D has immunomodulatory effects, and allelic variants of the vitamin D receptor (VDR) appear to be associated with differential susceptibility to several infectious diseases. To investigate whether VDR single nucleotide polymorphisms (SNPs) are associated with the development of HAM/TSP, we studied four VDR SNPs in a group of 207 HAM/TSP patients and 224 asymptomatic HTLV-1 seropositive carriers (HCs) in Kagoshima, Japan, by using PCR-RFLP analysis. We found that ApaI polymorphism of VDR is associated with the risk of HAM/TSP, although this polymorphism did not affect the provirus load of HTLV-1 in either HAM/TSP patients or HCs.

Mucolipidosis III (pseudo-Hurler polydystrophy); clinical studies in aged patients in one family

Three adult patients (38-year-old male, 86-year-old female, and 61-year-old male) in a family with mucolipidosis III (ML-III) were described. They had characteristic features of ML-III and they survived a long time. N-acetylglucosaminyl 1-phosphotransferase activity was low in fibroblasts of a patient, but its residual activity remained at a relatively high level (24.5-35.3% of controls), which may explain the benign clinical course. Odontoid dysplasia and atlanto-axial dislocation was found in one patient, and surgical treatment improved his physical disability. Bilateral carpal tunnel syndrome as well as claw hand deformities were common in all of the patients. The clinical manifestations were important for the diagnosis and the management of the patients.

Statistical Significance of Precisely Repeated Intracellular Synaptic Patterns

Can neuronal networks produce patterns of activity with millisecond accuracy? It may seem unlikely, considering the probabilistic nature of synaptic transmission. However, some theories of brain function predict that such precision is feasible and can emerge from the non-linearity of the action potential generation in circuits of connected neurons. Several studies have presented evidence for and against this hypothesis. Our earlier work supported the precision hypothesis, based on results demonstrating that precise patterns of synaptic inputs could be found in intracellular recordings from neurons in brain slices and in vivo. To test this hypothesis, we devised a method for finding precise repeats of activity and compared repeats found in the data to those found in surrogate datasets made by shuffling the original data. Because more repeats were found in the original data than in the surrogate data sets, we argued that repeats were not due to chance occurrence. Mokeichev et al. (2007) challenged these conclusions, arguing that the generation of surrogate data was insufficiently rigorous. We have now reanalyzed our previous data with the methods introduced from Mokeichev et al. (2007). Our reanalysis reveals that repeats are statistically significant, thus supporting our earlier conclusions, while also supporting many conclusions that Mokeichev et al. (2007) drew from their recent in vivo recordings. Moreover, we also show that the conditions under which the membrane potential is recorded contributes significantly to the ability to detect repeats and may explain conflicting results. In conclusion, our reevaluation resolves the methodological contradictions between Ikegaya et al. (2004) and Mokeichev et al. (2007), but demonstrates the validity of our previous conclusion that spontaneous network activity is non-randomly organized.

Protease activity appeared after trypsin treatment of the purified vitellogenin from eel Anguilla japonica.

Density gradient ultracentrifugation and anion-exchange chromatography combination were effective for the purification of the eel vitellogenin from the plasma of estradiol-treated eels. The vitellogenin was very high density glycolipoprotein (P = 1.27 g/ml) and its apolipoprotein was M(r) 196 k in both reduced and non-reduced conditions by SDS-PAGE. The major lipid component was phospholipid. The N-terminal amino-acid sequence of the vitellogenin was as follows: (Ac)Thr-Pro-Ala-Leu/Ala-Asp-Tyr. Amino-acid composition of the eel vitellogenin was similar to those of other teleosts. The protease activity appeared in the trypsinized vitellogenin, but was not detected in the purified vitellogenin. The protease was separated from the used trypsin and the other cleaved vitellogenin by a dextran sulfate cellulose column. The molecular weight of the protease was determined by zymogram using SDS-polyacrylamide gel containing casein and was 50 k. It was concluded that the eel vitellogenin possesses the protease activity as a latent form.

A C77G point mutation in CD45 exon 4, which is associated with the development of multiple sclerosis and increased susceptibility to HIV-1 infection, is undetectable in Japanese population

HTLV‐1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) is one outcome of Human T‐cell lymphotropic virus type 1 (HTLV‐1) infection. It remains unknown why the majority of infected people remain healthy whereas only approximately 2–3% develop disease. Recently, heterozygous state of CD45 exon 4 mutation (C77C wild type and C77G mutant) was reported to be associated with development of multiple sclerosis in German patients and increased susceptibility to HIV‐1 infection in the United Kingdom. To investigate whether this mutation is associated with the development of HAM/TSP, we studied a group of 164 HAM/TSP patients and 108 asymptomatic HTLV‐1 carriers in Kagoshima (HTLV‐1 endemic area in Southern Japan) by using PCR‐RFLP and subsequent direct sequencing analysis. All 272 subjects showed homozygosity in the CD45 exon 4, suggesting that this mutation is absent or very rare in Japanese population.