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Biomedical subjects

Hiroaki Takeuchi

Publications and source records attributed to Hiroaki Takeuchi.

69 records · Page 4Linked to original sources
PubMed2002

Inhibition of human immunodeficiency virus type 1 replication by P-stereodefined oligo(nucleoside phosphorothioate)s in a long-term infection model.

Oligo(nucleoside phosphorothioate)s (S-ODNs), if prepared by conventional methods, consist of a mixture of diastereomers by virtue of the asymmetry of the phosphorus atom involved in the internucleotide linkages. This may affect the stability of the complexes formed between S-ODNs and complementary oligoribonucleotides, which is commonly accepted as the most important factor in determining the efficacy of an antisense approach. Using HIV-1-infected MOLT-4 cells via a long-term culture approach, we studied the influence of the P-chirality sense of stereodefined 28mer oligo(nucleoside phosphorothioate)s, [All-Rp]-S-ODN-gag-28-AUG and [All-Sp]-S-ODN-gag-28-AUG, complementary to the sequence starting at the AUG initiation codon of the gag mRNA of HIV-1, upon the anti-HIV-1 activity. The [All-Sp]-S-ODN-gag-28-AUG at a low concentration of 0.5 microM can completely suppress HIV-1(gag) p24 antigen expression in HIV-1-infected MOLT-4 clone 8 cells for 32 days. Cells treated with [All-Rp]-S-ODN-gag-28-AUG (0.5 microM) showed a high level of the antigen expression at day 16. Furthermore, satisfactory suppression could not be achieved from a random [Mix]-S-ODN-gag-28-AUG, consisting of a diastereomeric mixture of the oligonucleotides. Our results suggest that chemotherapy based upon the use of stereodefined antisense [All-Sp] S-ODN may be a more effective method for reducing the viral burden in HIV-1-infected individuals.

Anti-HIV Agents↗
PubMed2002

Characterization of expression of a functionally conserved Helicobacter pylori methyltransferase-encoding gene within inflamed mucosa and during in vitro growth.

Methylation of bacterial DNA can regulate microbial growth and virulence. Expression of hpyIM, a conserved methyltransferase of the gastric pathogen Helicobacter pylori, was quantitated in gastric biopsy specimens from 41 H. pylori-infected patients and during growth in vitro, by quantitative reverse transcriptase-polymerase chain reaction and/or RNA slot-blot analysis, to determine whether levels of transcription were associated with pathologic outcome, as based on both severity of gastritis and inflammatory cytokine levels, or were regulated by bacterial growth phase. The effects that hpyIM inactivation has on bacterial morphology were determined by electron microscopy. Expression of hpyIM varied dramatically within colonized gastric tissue, and levels were not related to either colonization density, severity of inflammation, mucosal IL-8 concentrations, or clinical disease. In vitro, hpyIM expression was higher during log-phase growth and was required for normal bacterial morphology, suggesting that hpyIM expression may be growth-phase regulated within the gastric niche.

Gastric Mucosa↗
PubMed2002

Abnormalities of rate-corrected QT intervals in Parkinson's disease-a comparison with multiple system atrophy and progressive supranuclear palsy.

A number of patients with Parkinson's disease (PD) and multiple system atrophy (MSA), in whom sudden death does occur occasionally, have QT or rate-corrected QT (QTc) interval prolongation on electrocardiogram (ECG). Although these QT or QTc interval abnormalities are likely related to autonomic dysfunction, the pathophysiology remains unknown. The aim of this study was to compare the degree of QTc interval prolongation among akinetic-rigid syndromes, namely PD and related disorders, and to evaluate the relationship between QTc prolongation and severity of autonomic dysfunction. Thirty-four patients with PD, 22 with MSA, 11 with progressive supranuclear palsy (PSP) and 30 healthy controls underwent standard autonomic function tests, and electrocardiography variables (RR, QT and QTc intervals) were measured by an ECG recorder with an automated analyzer. The relationship between QTc interval and cardiovascular reflex tests were also analyzed. Orthostatic hypotension and decreased heart rate in response to respiratory stimuli were prominent in MSA, while these were relatively mild in PD. Unlike the RR and QT intervals, the QTc interval significantly differed among all groups (p<0.01). The QTc interval was significantly prolonged in PD (409+/-17 ms; p<0.001) and MSA (404+/-14 ms; p<0.05) compared with healthy controls (394+/-19 ms). Neither autonomic dysfunction nor QTc interval prolongation was evident in PSP. QTc intervals and cardiovascular reflexes did not correlate, except for Valsalva ratio. The QTc interval was obviously prolonged in PD patients to an extent that could not be accounted for simply by autonomic dysfunction levels. MSA patients showed slightly prolonged QTc intervals in spite of marked cardiovascular autonomic dysfunction. Abnormalities of the QTc may reflect the degeneration of cardioselective sympathetic and parasympathetic neurons that cannot be fully captured by cardiovascular autonomic function tests.

Adult↗
PubMed2002

Prognostic effect of lymph node micrometastasis in patients with histologically node-negative gastric cancer.

BACKGROUND: There is no consensus as to the impact of lymph node micrometastasis on survival of patients with gastric cancer. The aim of this study was to clarify the prognostic significance of lymph node micrometastasis in patients with histologically node-negative gastric cancer. METHODS: Lymph nodes (n = 2039) from 64 patients with histologically node-negative gastric cancer (T2, T3) were evaluated for micrometastasis. Three serial 5- micro m sections of the resected lymph nodes were prepared for immunohistochemical staining with the anti-cytokeratin antibody CAM 5.2. RESULTS: Micrometastasis was found in 73 of 2039 nodes (4%) and 20 of 64 patients (32%). The 5-year survival rate was significantly lower for patients with lymph node micrometastasis than for those without lymph node micrometastasis (66% vs. 95%, P <.01). The 5-year survival rate was significantly lower when there were four or more positive micrometastatic nodes (94% vs. 29%, P <.01) and when there were extragastric micrometastatic nodes (89% vs. 53%, P <.01). CONCLUSIONS: Lymph node micrometastasis was associated with poor outcome in patients with histologically node-negative gastric cancer. The number and the level of lymph node micrometastases are useful prognostic markers for deciding treatment strategies for additional therapy and follow-up.

Adenocarcinoma↗
PubMed2002

Survey of dental hygienists and healthcare workers for microorganisms in the oral cavity.

Over 350 bacterial species are known to form communities on tooth surfaces in the oral cavity, and opportunistic pathogens are frequently isolated from samples taken from the oral cavities of immunocompromised hosts, as well as elderly people with poor oral hygiene. To confirm the correlation between the prevalence of opportunistic pathogens in the oral cavity and oral hygiene, dental plaque and saliva samples from 15 dental hygienists and 15 healthcare workers were investigated. No opportunistic pathogens were found in the samples from dental hygienists, however, they were isolated from 10 of the 15 healthcare workers (66.7%). The total amounts of Streptococcus sp. and Lactobacillus sp. were also significantly higher in the healthcare workers. The amount of Streptococcus mutans was also higher, although the difference was not significant. From our results, we concluded that the prevalence of opportunistic pathogens and cariogenic bacteria in the oral cavity may be reduced by proper oral hygiene measures.

Adult↗
PubMed2002

A case of severe respiratory depression due to cibenzoline overdosage induced by a transient renal dysfunction.

A 69-year-old man was transferred to our hospital because of severe general fatigue and progressive systemic muscle weakness. He had taken 300 mg/day of cibenzoline for his sustained ventricular tachycardia (VT) for years. At the end of June 2001 he began to feel general fatigue, which slowly progressed to systemic muscle weakness and walking disturbance. On 2nd July 2001, he finally could not stand up by himself. He also felt dyspnea. He was transferred to our emergency room, where he developed severe respiratory depression. Acute myocardial infarction was ruled out based on his ECG and blood chemistry data. Serum BUN and creatinine were elevated to 32 and 2.2 mg/dl, respectively, which returned to normal range 2 weeks later. What we did in our ICU were basically a replacement of cibenzoline with mexiletine and mechanical support of ventilation. As his renal function gradually improved, his spontaneous respiration and muscle power were slowly restored. He was discharged on foot after 1 month of hospitalization. His blood cibenzoline content taken 2 days after the cessation of cibenzoline was 959.6 mg/ml that was abnormally elevated. Considering metabolism and excretion for the 2 days between the cibenzoline cessation and the blood sample drawing, his cibenzoline level on the day of admission must have been extraordinary high. We should be aware of the possibility of abrupt overdosage of cibenzoline even in patients with normal kidney function in the event of a transient or an acute renal dysfunction.

Aged↗
PubMed2002

Epithelial differentiation and proliferative potential in spinal ependymomas.

The aim of this investigation was recognition of the epithelial differentiation and proliferative activity of ependymomas in the spinal cord compared with astrocytomas in the spinal cord and ependymoma in the brain. We investigated histopathological and immunohistochemical examination in thirty-five cases, including eleven ependymomas, thirteen astrocytomas in the spinal region and eleven ependymomas in the intracranial region. An anti-epithelial membrane antigen antibody (EMA), and two types of anti-cytokeratin antibodies, CAM 5.2 (45 and 52 kDa) and keratin (56 and 64 kDa) were applied as epithelial markers. The proliferative potential of the tumors was investigated using the Ki-67 labeling index (LI, %). Histologically, perivascular pseudorosettes were seen in all of the spinal and intracranial ependymomas. There were few ependymal structures in the spinal ependymomas except in the myxopapillary type. Immunohistochemical study demonstrated that nine (82%) were immunoreactive for EMA, eight (73%) were immunoreactive for CAM 5.2 and three (27%) were immunoreactive for keratin in the spinal ependymomas. In the spinal astrocytomas, no tumors were immunoreactive for EMA or CAM 5.2. One of thirteen cases was immunoreactive for keratin. The Ki-67 LI of the spinal ependymomas was lower than that of the intracranial ependymoma (p < 0.01). Epithelial differentiation was found in the ependymomas which may reflect the differences in histological and biological features between ependymomas and astrocytomas in the spinal cord. Regional differences in ependymomas may influence not only clinical features but also histo-pathological characteristics.

Adolescent↗
PubMed2002

Development of HIV-1 dependent gene expression vector with the Cre/loxP (ON) system.

We used the HIV-1 5'LTR and the Cre/loxP system to develop an anti-gene expression system. The LTR promoter of HIV-1 has a specific activity that includes the intermediary region of gag, as shown in a previous report. We constructed the U5-region of HIV-1 as the target of the ribozyme expression vector (pCre/loxP-Rz), with the Cre/loxP system under the control of this LTR promoter. The function of this vector is to induce the HIV-1 dependent ribozyme-mediated inhibition in a dose-responsive manner. Furthermore, ribozyme mRNA expression was detected in the presence of pNL4-3 in HeLa-CD4+ cells. These studies are expected to yield novel applications of antiviral strategies for HIV-1.

Gene Expression↗
PubMed2002

RNA cleavage by a mammalian tRNA 3'processing endoribonuclease (3'tRNase) reduces HIV-1 expression.

We examined the suppression of HIV-1 expression by cleavage of the HIV-1 RNA gene, using a mammalian tRNA 3'processing endoribonuclease (3'tRNase) as an External Guide Sequence oligozyme (EGS) in vivo. The enzyme can also recognize and cleave a target RNA that forms a pre-tRNA like complex with a substrate RNA. We designed an EGS to specifically recognize the packaging signal region (p.s.) and the upstream portion of the gag region (g.s.) of HIV-1 mRNA, and constructed EGS expression vectors that used the tRNA(met) promoter as an expression cassette for the EGS. Their cleavage activities were assessed in cell culture, using a transient assay system. The EGS efficiencies were determined by co-transfection of the EGS expression vectors and the HIV-1 gene plasmid vector (pNL-luc) into COS cells. The assay results showed a significant inhibition of the HIV-1 gag p24 antigen expression. In addition, we constructed MLV-based VSV-G pseudotyped retrovirus vectors that express the EGS. They were co-infected into MT-4 cells with the HIV-1 virus (NL4-3). These EGS expression retrovirus vectors exhibited a similar inhibitory effect.

Animals↗
PubMed2002

Measurement of the vascularity and vascular leakage of gliomas by double-echo dynamic magnetic resonance imaging: a preliminary study.

RATIONALE AND OBJECTIVE: To evaluate the vascularity and vascular leakage of well-enhanced gliomas by double-echo dynamic magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eight patients with glioblastoma multiforme (GBM) and two patients with juvenile pilocytic astrocytoma (JPA) were studied. Double-echo dynamic MR imaging was utilized to separate the T2* shortening effect and the T1 shortening effect. The former was represented by the vascularity index, and the latter was represented by the leakage index. These indexes were compared with histopathologic data. RESULTS: The mean vascularity index of the GBM was higher than that of the JPA (mean +/- SD, 3.48 +/- 1.57 [GBM] versus 0.51 +/- 0.29 [JPA]), and the mean leakage index of the JPA was higher than that of the GBM (1.35 +/- 0.87 [JPA] versus 0.27 +/- 0.15 [GBM]). Abundant vascularity was noted in the tight interstitial space in the pathologic specimen of GBM. Conversely, sparse vasculature was observed in the wide interstitial space in the pathologic specimen of JPA. CONCLUSION: This method may enable better characterization of grade in well-enhanced glioma by providing the information on the vascularity and leakage indexes.

Adult↗
PubMed2002

Inhibition of human immunodeficiency virus type 1 activity in vitro by a new self-stabilized oligonucleotide with guanosine-thymidine quadruplex motifs.

An oligonucleotide with a dimeric hairpin guanosine quadruplex (basket type structure) (dG3T4G3-s), containing phosphorothioate groups, was able to inhibit human immunodeficiency virus type 1 (HIV-1)-induced syncytium formation and virus production (as measured by p24 core antigen expression) in peripheral blood mononuclear cells. This oligonucleotide lacks primary sequence homology with the complementary (antisense) sequences to the HIV-1 genome. Furthermore, this oligonucleotide may have increased nuclease resistance. The activity of this oligonucleotide was increased when the phosphodiester backbone was replaced with a phosphorothioate backbone. In vivo results showed that dG3T4G3-s was capable of blocking the interaction between gp120 and CD4. We also found that dG3T4G3-s specifically inhibits the entry of T-cell line-tropic HIV-1 into cells. This compound is a viable candidate for evaluation as a therapeutic agent against HIV-1 in humans.

Giant Cells↗
PubMed2002

Inhibition of HIV-1 replication by an HIV-1 dependent ribozyme expression vector with the Cre/loxP (ON/OFF) system.

Antiviral strategies to inhibit HIV-1 replication have included the generation of gene products that provide the intracellular inhibition of an essential viral protein or RNA. When used in conjunction with the HIV-1 long terminal repeat (LTR), an inducible promoter dependent on the virus-encoded trans-activator (tat), relatively high background activity is still observed in the absence of tat (Caruso & Klatzmann, 1992; Dinges et al., 1995). In order to circumvent this problem, we used the Cre/loxP (ON/OFF) recombination system as a tool for our investigation. In the present study, we constructed a loxP-cassette vector with the ribozyme (Rz) expression portion under the control of the tRNAi(Met) promoter between two loxP sequences (plox-Rz-U5). We also constructed an HIV-1 LTR promoter-driven Cre recombinase gene (pLTR-Cre). These vectors were triple-transfected into HeLa CD4 cells with the HIV-1 pseudotype viral expression vector. Basal activity was not detectable before HIV-1 infection. The LTR-dependent Cre protein product in HIV-1 infected HeLa CD4 cells expressed the ribozyme by inducing loxP homologous recombination, which strongly inhibited the HIV-1 gene expression. These results demonstrate the potential of an anti-ribozyme with the Cre/loxP system for controlling HIV-1 infection via gene therapy.

Attachment Sites, Microbiological↗
PubMed2002

[Functional MRI activation in area V4 alpha during a hue arrangement test].

BACKGROUND: Recent studies of cerebral information processing have shown that area V4 alpha, the area anterior to area V4, which is known as the human color center, is also associated with color. However, our clinical study has shown that lesions associated with hue arrangement test failures are more anterior than those associated with pseudoisochromatic plate test failure. PURPOSE AND METHODS: We studied area V4 alpha, and planned two functional magnetic resonance experiments for V4 alpha activity during the hue arrangement test. The task in the first experiment was virtual simulation of the hue arrangement test. The second experiment involved a task more specific to color information processing. RESULTS: We found significant activity in area V4 alpha in healthy subjects. CONCLUSIONS: We have reported that one of our patients with a more anterior lesion excluding area V4 had dyschromatopsia, as revealed by a panel D-15 test. Our experimental data and the clinical findings suggest that area V4 alpha plays an important role in processing during the hue arrangement test.

Cerebral Cortex↗