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H Ohkubo

Publications and source records attributed to H Ohkubo.

At least 19 recordsLinked to original sources
PubMed2003

Reduction of propagation and bending losses of heterostructured photonic crystal waveguides by use of a high-delta structure.

We describe the fabrication and evaluation of a low-loss, high-delta optical waveguide consisting of heterostructured photonic crystals. The waveguide is composed of a multilayer stack of Ta2O5/SiO2 and is prepared by use of the autocloning technique. Light is guided in the waveguide by the difference in the effective refractive indices of the constituent photonic crystals. By improving the design of the core region so that is has a flat multilayer structure, we achieve delta = 3.09% for the in-plane direction and net propagation loss of 0.56 dB/mm at lambda = 1.6 microm. Experiments also suggest that the bending loss of the waveguide can be reduced to less than 0.1 dB if the curvature radius is larger than 700 microm.

Journal Article↗
PubMed2002

Alterations of quantitative EEG and mini-mental state examination in interferon-alpha-treated hepatitis C.

We have recently observed a diffuse slowing of brain waves using serial quantitative electroencephalographic (qEEG) examinations in interferon (IFN)-alpha-treated chronic hepatitis C patients. However, it remains unclear how this alteration could be assessed. We evaluated the correlation between the qEEG changes and three tests of mental status, including the Mini-Mental State Examination (MMSE), in such patients. This is the first study to undertake a clinical evaluation of the adverse effects on brain function due to IFN. We undertook blind, prospective and serial qEEG examinations on 56 chronic hepatitis C patients at three independent hospitals. IFN-alpha was administered intramuscularly at a dose of 9 x 10(6) IU daily for the first 4 weeks and then 3 times/week for the next 20 weeks. Serial EEGs were obtained before, at 2 and 4 weeks of treatment, and after the IFN-alpha treatment. The absolute power values of each frequency band in each patient at different stages of treatment were recorded by qEEG. Each patient was assessed by the MMSE, Hamilton Rating Scale for Depression (HSD), and Hamilton Rating Scale for Anxiety (HSA). We statistically evaluated the correlations between the changes in power values and alterations of scores on the mental status tests during IFN-alpha treatment. The decreased scores observed on the MMSE ranged from 2 to 5 points at both 2 and 4 weeks of IFN-alpha treatment. There were no significant differences in age distribution for each decreased score on the MMSE. As the alteration in MMSE score during IFN treatment increased, the alteration in absolute power values for the slow waves during IFN treatment increased significantly, while that for the alpha 2 and fast waves during treatment decreased significantly. However, the changes in the HDS and HSA revealed no significant correlations. The alteration of the qEEG was reversible after the treatment. MMSE scores represent one screening method for the clinical assessment of IFN-alpha-induced alterations of brain function.

Adult↗
PubMed2002

Waste management systems of dairy cattle farms in Japan.

Recently, the size of livestock farms in Japan has been expanding and the pollution from farm wastes has become a serious problem in rural areas. Therefore it is necessary to design treatment strategies and improve the recycling of livestock manure for sustainability of agriculture in Japan. The dairy cattle waste management systems were studied at dairy farms in Aomori prefecture and in Hokkaido, Japan. The four farms, typical for the respective regions in Japan, were investigated on the basis of the land and livestock size, housing, overall farm and waste management, type of machinery and a farm labour force. A statistical comparison was made for housing, milking and waste handling systems of dairy farms. One of the waste handling strategies was aerobic slurry treatment and land irrigation of the treated liquid fraction. Such methods began to solve some of waste management problems created since 1967 in grassland farming areas of Hokkaido. The irrigation system supplies water fertiliser and organic material to land as well as shortening the spreading times. It recycles livestock resources, increases the soil fertility and rationalizes the farm management.

Agriculture↗
PubMed2001

Identification and characterization of cell-specific enhancer elements for the mouse ETF/Tead2 gene.

We have identified and characterized by transient transfection assays the cell-specific 117-bp enhancer sequence in the first intron of the mouse ETF (Embryonic TEA domain-containing factor)/Tead2 gene required for transcriptional activation in ETF/Tead2 gene-expressing cells, such as P19 cells. The 117-bp enhancer contains one GC-rich sequence (5'-GGGGCGGGG-3'), termed the GC box, and two tandemly repeated GA-rich sequences (5'-GGGGGAGGGG-3'), termed the proximal and distal GA elements. Further analyses, including transfection studies and electrophoretic mobility shift assays using a series of deletion and mutation constructs, indicated that Sp1, a putative activator, may be required to predominate over its competition with another unknown putative repressor, termed the GA element-binding factor, for binding to both the GC box, which overlapped with the proximal GA element, and the distal GA element in the 117-bp sequence in order to achieve a full enhancer activity. We also discuss a possible mechanism underlying the cell-specific enhancer activity of the 117-bp sequence.

Animals↗
PubMed2001

Presence of multiple HIV type 1 subtypes among mothers and children in Japan.

We collected blood samples from 70 HIV-1-infected pregnant women and 76 babies born to HIV-1-infected women in Japan, from 1989 to 1999. To analyze the genetic diversity of HIV-1 among mothers and children, we sequenced the C2-V3 regions of HIV-1 gp120. Phylogenetic tree analysis of these regions revealed that multiple HIV-1 subtypes, A, B, D, E, and G, were circulating among mothers and children in Japan. Thus, the genetic heterogeneity of HIV-1 among mothers and children in Japan is steadily increasing, although the number of cases remains small. Perhaps the longest term survivor, an 11-year-old child with a vertical HIV-1 subtype G infection in Japan, is one of our subjects.

Amino Acid Sequence↗
PubMed2000

Structure of the mouse NDRF gene and its regulation during neuronal differentiation of P19 cells.

We have isolated and characterized the mouse gene for NDRF (neuroD-related factor), a basic helix-loop-helix transcription factor implicated in neural development and function. The gene consists of two exons and the entire protein-coding sequence is encoded by a single downstream exon. RNA blot hybridization analysis revealed that NDRF mRNA was detectable at day 4 and increased to a maximal level at day 6 during neuronal differentiation of P19 cells. To elucidate the regulatory mechanisms of the NDRF gene expression during this process, a construct containing the genomic DNA fragment of about 3 kbp upstream of the NDRF coding region fused to a luciferase reporter gene was transfected into P19 cells, and stable transformants were pooled for assay of luciferase activities. When the stable transformants were treated with RA and aggregated to induce neuronal differentiation, the luciferase activities were induced in a temporal expression pattern similar to that of the endogenous NDRF mRNA. Further experiments using a series of deletion and mutation constructs indicated that the 376-bp sequence in the 5'-flanking region of the NDRF gene is important, and that one of the E boxes in the sequence plays a critical role in the regulated expression. Transient transfection experiments also showed that the same E box is required for the transactivation of the NDRF promoter activity by neurogenin 1. These results suggest that the NDRF gene expression is regulated by an E box-binding factor during neuronal differentiation of P19 cells.

Animals↗
PubMed2000

A prospective study of interferon therapy modified by pre-treatment viral load in cirrhotic patients. Tokyo-Chiba Hepatitis Research Group.

BACKGROUND/AIMS: The relative role of hepatitis C virus (HCV) load and subtype as predictors of the efficacy of interferon therapy has been clarified in patients with chronic hepatitis C, but the effectiveness of interferon therapy in cirrhotic patients is still unclear. METHODS: To resolve this issue, we undertook a multicenter, randomized, and prospective study of 114 cirrhotic patients with hepatitis C virus infection. The patients were selected to undergo two different periods (6 or 12 months) of IFN therapy according to viral load. Patients with "low" viral load (< or = 10(5.8) copies/ml serum) were randomly divided into three groups, receiving 6 or 9 million units (MU) interferon three times a week for 6 months (total dose: 468 or 702 MU), or of a modified regimen using 6MU of IFN over 6 months (total dose 564 MU), while patients with "high" viral load (< or = 10(6.3) copies/ml serum) were also randomly divided into two groups of 6 or 9 MU of IFN three times a week for 12 months (total dose: 936 or 1,404 MU). RESULTS: HCV-RNA negativity rate at the completion of treatment with 6 or 9 MU IFN was 65% in patients with "low" viral load, in contrast to 14% in patients with "high" viral load. Sustained virological response was found in 40% of patients with "low" viral load irrespective of the three different regimens, in contrast to only 1 out of 35 patients (3%) with "high" viral load. Viral eradication was found in approximately 50% of patients having a low virus load (< or = 10(4.3) copies/ml) and with HCV subtype 2a. Univariate and multivariate analysis revealed that pretreatment viral load was a significant factor contributing to efficacy of IFN therapy. CONCLUSIONS: Sustained response was scarcely achieved in cirrhotic patients with high viral loads even after a 12-month course of intensive IFN therapy. This result indicates that there is a certain cut-off level of HCV RNA load which can not be eradicated.

Adult↗
PubMed1999

Interaction of PKN with a neuron-specific basic helix-loop-helix transcription factor, NDRF/NeuroD2.

By the yeast two-hybrid screening of a human brain cDNA library with the amino-terminal regulatory region of PKN as a bait, a clone encoding a neuron-specific basic Helix-Loop-Helix (bHLH) transcription factor, NDRF/NeuroD2 was isolated. NDRF/NeuroD2 was co-precipitated with PKN from the lysate of COS-7 cells transfected with both expression constructs for NDRF/NeuroD2 and PKN. In vitro binding studies using the deletion mutants of NDRF/NeuroD2 synthesized in a rabbit reticulocyte lysate indicated that the internal region containing the bHLH domain of NDRF/NeuroD2 was necessary and sufficient for the interaction with PKN. In addition, recombinant NDRF/NeuroD2 purified from Escherichia coli could bind PKN, suggesting the direct interaction between NDRF/NeuroD2 and PKN. Transient transfection assays using P19 cells revealed that expression of NDRF/NeuroD2 increased the transactivation of the rat insulin promoter element 3 (RIPE3) enhancer up to approximately 12-fold and that co-expression of catalytically active form of PKN, but not kinase-deficient derivative, resulted in a further threefold increase of NDRF/NeuroD2-mediated transcription. These findings suggest that PKN may contribute to transcriptional responses through the post-translational modification of the NDRF/NeuroD2-dependent transcriptional machinery.

Animals↗
PubMed1999

Predictive value of Ki-67, p53 protein, and DNA content in the diagnosis of gastric carcinoma.

BACKGROUND: The ability to make a precise preoperative diagnosis is a valuable and effective method in improving the prognosis of patients with gastric carcinoma. The authors examined retrospectively whether preoperative histopathologic analysis with p53 protein, Ki-67 labeling index, and DNA ploidy along with preoperative radiographic and endoscopic findings led to a precise preoperative diagnosis of patients with gastric carcinoma. METHODS: Histopathologic analysis of p53 protein, Ki-67 labeling index, and DNA content was performed on formalin fixed, paraffin embedded tissue. Tissue sections from endoscopic and surgically resected specimens were stained immunohistochemically for p53 protein and Ki-67 labeling index, and the cell nuclear DNA content of the surgically resected primary lesion was measured using a microspectrophotometer. These analyses were performed on 16 patients with early gastric carcinoma (EGC) who were diagnosed with advanced gastric carcinoma (AGC) based on the preoperative imaging findings and on 15 patients with AGC who were diagnosed preoperatively with EGC. RESULTS: Overexpression of p53 in the AGC group was significantly more frequent compared with that in the EGC group (P = 0.0386). With regard to the correlation between lymph node metastases and p53 overexpression, there was no apparent relation in either the AGC group (P = 0.648) or the EGC group (P = 0.726). The AGC group had significantly higher Ki-67 labeling indices compared with the EGC group (P = 0.0195). There was complete concordance between endoscopic and surgically resected specimens with regard to the p53 and Ki-67 labeling index findings. DNA ploidy in the primary tumor did not differ between the AGC and EGC groups. The survival rates for the EGC group were significantly superior to those for the AGC group (P = 0.0312). CONCLUSIONS: The findings of the current study suggest that in routine clinical practice, the combination of preoperative imaging findings in addition to Ki-67 labeling indexes, and p53 protein analyses may be useful for the accurate diagnosis of EGC; however, DNA ploidy did not appear to reflect the growth potential of gastric carcinoma.

Aged↗
PubMed1999

Cloning from insulinoma cells of synapsin I associated with insulin secretory granules.

Synapsin I is a synaptic vesicle-associated protein involved in neurotransmitter release. The functions of this protein are apparently regulated by Ca2+/calmodulin-dependent protein kinase II (CaM kinase II). We reported evidence for CaM kinase II and a synapsin I-like protein present in mouse insulinoma MIN6 cells (Matsumoto, K., Fukunaga, K., Miyazaki, J., Shichiri, M., and Miyamoto, E. (1995) Endocrinology 136, 3784-3793). Phosphorylation of the synapsin I-like protein in these cells correlated with the activation of CaM kinase II and insulin secretion. In the present study, we screened the MIN6 cDNA library with the full-length cDNA probe of rat brain synapsin Ia and obtained seven positive clones; the largest one was then sequenced. The largest open reading frame deduced from the cDNA sequence of 3695 base pairs encoded a polypeptide of 670 amino acids, which exhibited significant sequence similarity to rat synapsin Ib. The cDNA contained the same sequence as the first exon of the mouse synapsin I gene. These results indicate that synapsin Ib is present in MIN6 cells. Synapsin I was expressed in normal rat islets, as determined by reverse transcriptase-polymerase chain reaction analysis. Immunoblot analysis after subcellular fractionation of MIN6 cells demonstrated that synapsin Ib and delta subunit of CaM kinase II co-localized with insulin secretory granules. By analogy concerning regulation of neurotransmitter release, our results suggest that phosphorylation of synapsin I by CaM kinase II may induce the release of insulin from islet cells.

Amino Acid Sequence↗
PubMed1999

Transcriptional regulation of mouse type 1 inositol 1,4,5-trisphosphate receptor gene by NeuroD-related factor.

The type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) is a Ca2+ channel protein that is expressed abundantly in the CNS, such as in the cerebellar Purkinje cells and hippocampus. We previously demonstrated that the box-I element, which is located -334 relative to the transcription initiation site of the mouse IP3R1 gene and includes an E-box consensus sequence, is involved in the up-regulation of such IP3R1 gene expression. Furthermore, the previous study also indicated that some CNS-related basic helix-loop-helix (bHLH) factors bind to the box-I and activate IP3R1 gene expression. In this study, we demonstrated that one of the CNS-related bHLH factors, neuronal differentiation factor (NeuroD)-related factor (NDRF), specifically bound to the box-I sequence with a ubiquitously expressed bHLH protein, E47, and activated IP3R1 gene expression. In situ hybridization of adult mouse brain revealed that IP3R1 and NDRF mRNA were co-expressed in many subsets of neurons, highly in Purkinje cells and hippocampus and moderately in cerebral cortex, olfactory bulb, and caudate putamen. Furthermore, the spatiotemporal expression patterns of these two genes resembled one another throughout postnatal development of the mouse CNS. From these results, we suggest that NDRF is involved in the tissue-specific regulation of IP3R1 gene expression in the CNS.

Animals↗
PubMed1999

A newly identified patient with clinical xeroderma pigmentosum phenotype has a non-sense mutation in the DDB2 gene and incomplete repair in (6-4) photoproducts.

We report here a patient (Ops1) with clinical photosensitivity, including pigmented or depigmented macules and patches, and multiple skin neoplasias (malignant melanomas, basal cell carcinomas, and squamous cell carcinomas in situ) in sun-exposed areas. These clinical features are reminiscent of xeroderma pigmentosum. As cells from Ops1 showed normal levels in DNA repair synthesis in vivo (unscheduled DNA synthesis and recovery of RNA synthesis after ultraviolet irradiation), we performed a postreplication repair assay and recovery of replicative DNA synthesis after ultraviolet irradiation to investigate if Ops1 cells belonged to a xeroderma pigmentosum variant pattern. Ops1 cells were normal, but there was an incomplete pattern repair in (6-4) photoproducts in contrast to a normal pattern repair in cis-syn cyclobutane pyrimidine dimers by repair kinetics using the enzyme-linked immunosorbent assay. Moreover, Ops1 cells were defective in a damage-specific DNA binding protein and carried a non-sense mutation in the DDB2 gene. These results suggest that (i) the DDB2 gene is somewhat related to skin carcinogenesis, photoaging skin, and the removal of (6-4) photoproducts; (ii) although it is believed that cyclobutane pyrimidine dimers are the principal mutagenic lesion and (6-4) photoproducts are less likely to contribute to ultraviolet-induced mutations in mammals, Ops1 is one of the ultraviolet-induced mutagenic models induced by (6-4) photoproducts.

Caffeine↗
PubMed1999

Prediction of the development of hepato-cellular-carcinoma in patients with liver cirrhosis by the serial determinations of serum alpha-L-fucosidase activity.

OBJECTIVE: Evaluation of the usefulness of the serial determinations of serum alpha-L-fucosidase (AFU) activity for prediction of the development of hepatocellular carcinoma (HCC) was performed. METHODS AND PATIENTS: Serum AFU activity was determined monthly for 42 months in 73 patients with liver cirrhosis (LC). RESULTS: HCC was diagnosed in 27 patients by means of ultrasonography during this observation period. In 23 (85%) of the 27 patients, serum AFU activity was found to exceed 700 nmole/ml/h during the LC stage. HCC developed within a few years in 23 (82%) of 28 LC patients with AFU activity exceeding 700 nmole/ml/h, in contrast, it developed in only 4 (9%) of 45 LC patients with AFU activity below 700 nmole/ml/h. AFU activity was already elevated in 23 (85%) of 27 patients at least 6 months before the detection of HCC by ultrasonography. CONCLUSION: It is conceivable that the development of HCC can be predicted by means of serial determinations of serum AFU activity in patients with LC.

Carcinoma, Hepatocellular↗
PubMed1999

Association of polymorphism in the NeuroD/BETA2 gene with type 1 diabetes in the Japanese.

NeuroD/BETA2, a transcription factor of the insulin gene, also plays an important role in the development of pancreatic beta-cells. Recently, the NeuroD/BETA2 gene has been mapped to the long arm of human chromosome 2 (2q32) where the IDDM7 gene has previously been mapped, implying its involvement in diabetes. To identify mutations in the NeuroD/BETA2 gene that may predispose patients to develop diabetes, we studied the gene in 50 Japanese subjects with diabetes (4 with type 1 and 46 with type 2) by the polymerase chain reaction (PCR) followed by single-strand conformation polymorphism and sequencing analyses. Further analysis was performed in 392 Japanese subjects (60 with type 1 and 158 with type 2 diabetes and 174 healthy control subjects) by mismatch PCR restriction fragment length polymorphism. We found a DNA polymorphism of the NeuroD/BETA2 gene. A nucleotide G-to-A transition results in the substitution of alanine to threonine at codon 45 (Ala45Thr). The frequencies of heterozygotes for the Ala45Thr variant were 9.8% in the control subjects, 9.5% in the patients with type 2 diabetes, and 25.0% in the patients with type 1 diabetes, a significant difference (P = 0.006). Because the variant of the NeuroD/BETA2 gene (Ala45Thr) is associated with type 1 but not type 2 diabetes, it may be implicated in the loss of pancreatic beta-cells in type 1 diabetes.

Adult↗
PubMed1998

A 3 T superconducting magnet for long-run magnetic Compton-scattering experiments.

A 3 T superconducting magnet has been designed and constructed for magnetic Compton-profile (MCP) measurements with the new capabilities that the magnetic field direction can be altered quickly (within 5 s) and liquid-He refill is not required for more than one week. For the latter capability, two refrigerators have been directly attached to the cryostat to maintain the low temperature of the radiation shields and for the recondensation of liquid He. The system has been satisfactorily operated for over one week.

Journal Article↗
PubMed1998

Regulated expression of neurogenic basic helix-loop-helix transcription factors during differentiation of the immortalized neuronal progenitor cell line HC2S2 into neurons.

Expression of nine neurogenic basic helix-loop-helix (bHLH) transcription factors was examined in an immortalized neuronal progenitor cell line HC2S2, which differentiates into neurons after suppression of the v-myc expression with tetracycline. Expression of MASH-1, NeuroD, NeuroD-related factor (NDRF) and HES-1 was demonstrated in HC2S2 cells by Northern blot analysis using total RNA. Expression of MASH-1 mRNA was downregulated upon differentiation of HC2S2 cells into mature neurons. In contrast, NeuroD and NDRF mRNA expression was maintained all through the differentiation. The expression of HES-1, a negative regulator of the neuronal differentiation, was upregulated temporarily in accordance with the suppression of the v-myc expression and was downregulated upon the differentiation of HC2S2 cells into neurons. The reduced expression of HES-1 mRNA in undifferentiated HC2S2 cells may be explained by the transcriptional suppression of HES-1 by the myc oncoprotein. The above data imply that both HES-1 and MASH-1 need to be downregulated at the time of accomplishment of the terminal differentiation into mature neurons and that NeuroD and NDRF participate in the regulatory process of the terminal differentiation in combination.

Animals↗
PubMed1997

Improved mortality rate of gastric carcinoma patients with peritoneal carcinomatosis treated with intraperitoneal hyperthermic chemoperfusion combined with surgery.

BACKGROUND: Peritoneal carcinomatosis from gastric carcinoma has a very poor prognosis. The purpose of this study was to evaluate the efficacy of intraperitoneal hyperthermic chemoperfusion (IHCP) in advanced gastric carcinoma patients with peritoneal carcinomatosis. METHODS: IHCP combined with aggressive surgery was performed in 48 gastric carcinoma patients with peritoneal carcinomatosis; 18 gastric carcinoma patients with peritoneal carcinomatosis serving as controls were treated with surgery alone. RESULTS: The survival period was extended for the 48 patients who underwent surgery plus IHCP compared with the control patients (P = 0.00167). Of the 29 patients with peritoneal carcinomatosis in the upper abdominal cavity, the 21 patients treated with IHCP and surgery had survival periods superior to those of the 8 patients treated by surgery alone (P = 0.000817). The 5-year survival rate of the 18 IHCP patients with countable metastases in the entire cavity was 41.6%, whereas the 50% survival duration of the control group was 110 days. Nineteen patients with numerous metastases in the entire cavity died within 673 days, regardless of whether or not IHCP was used. CONCLUSIONS: Peritoneal carcinomatosis is not a disease beyond treatment. IHCP treatment combined with extensive surgery provides an effective and practical method of treating this disease entity.

Carcinoma↗