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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 181 records · Page 10Linked to original sources
PubMed2000

Asymptomatic cyst passers of Entamoeba histolytica but not Entamoeba dispar in institutions for the mentally retarded in Japan.

Entamoeba histolytica/Entamoeba dispar was isolated from 50 asymptomatic amebic cyst passers in three institutions for the mentally retarded in Kanagawa Prefecture, Japan. To distinguish between E. histolytica and E. dispar, the isolates were analyzed by PCR, reactivity to monoclonal antibodies, and zymodemes. All isolates were identified as E. histolytica. The results lead us to conceive that, in Japan, E. histolytica is predominant even in asymptomatic cyst passers.

Animals↗
PubMed2000

Adult onset Still's disease with hemophagocytic syndrome and severe liver dysfunction.

We report the case of a 55-year-old Japanese woman with adult onset Still's disease in whom hemophagocytic syndrome and severe liver dysfunction developed. High serum levels of ferritin, macrophage colony stimulating factor and interferon-gamma, which imply the presence of hemophagocytic syndrome, were detected. It is known that hemophagocytic syndrome is associated with adult onset Still's disease. In our case, many markedly swollen Kupffer cells with phagocytized red blood cells were found in the liver, as well as macrophages in the bone marrow and spleen. Accordingly, we believe that severe liver dysfunction in this case may have been related to hypercytokinemia due to hemophagocytic syndrome.

Journal Article↗
PubMed2000

Sleep onset REM period appearance rate is affected by REM propensity in circadian rhythm in normal nocturnal sleep.

OBJECTIVE: REM latency is usually 60-120 min, but under certain conditions, its latency may be less than 25 min, in which it is known as sleep onset REM period (SOREMP). In order to identify the factors responsible for the appearance of SOREMP, we used the nocturnal sleep interruption method to investigate whether REM propensity in normal nocturnal sleep, (i.e. circadian variations in REM sleep related to body temperature rhythm), could affect the rate of SOREMP appearance (SOREMP%). MATERIALS AND METHODS: After two adaptation and one baseline nights, we interrupted the nocturnal sleep, either in the second or the fourth cycle (early and late conditions, respectively) of 16 subjects and compared SOREMP% at the second sleep onset between these conditions by chi(2) test. Rectal temperature was measured. RESULTS: SOREMP% was found to be 58.1% in the early condition and 87.5% in the late condition - a significant difference. Body temperature dropped at the second sleep onset in both conditions but the drops did not differ significantly. CONCLUSION: We concluded that SOREMP% was affected by circadian variations in REM propensity but SOREMP% and body temperature drop did not show a linear relationship. Further studies to discriminate the influence of circadian rhythm factors and slow wave sleep on SOREMP% are called for.

Adolescent↗
PubMed2000

Application of a method incorporating differential centrifugation for selective isolation of motile actinomycetes in soil and plant litter.

The present paper describes a simple enrichment technique which enables rapid and selective isolation of diverse zoosporic actinomycete genera directly from soil and plant litter. This technique, designated the rehydration and centrifugation (RC) method, consists of immersing the air-dried source material in 10 mM phosphate buffer containing 10% soil extract, letting the preparation stand at 30 degrees C for 90 min, followed by centrifugation of the fluid at 1,500 x g for 20 min. Portions of the supernatant containing actinomycete zoospores are plated on the humic acid-vitamin agar which is supplemented with nalidixic acid and trimethoprim as the selective inhibitors for Gram-negative bacteria and bacilli. The phosphate buffer-soil extract solution significantly promoted liberation of motile zoospores from the source material. The centrifugation stage greatly eliminated streptomycetes and other non-motile actinomycetes from the liquid phase, thereby facilitating selective growth of rare, motile actinomycetes on the isolation plates subsequent to inoculation. Ten different soil and leaf-litter samples, taken from fields, forests, and stream banks, were examined. The RC method consistently achieved preferential isolation of motile actinomycetes in all samples, which accounted for 37-86% of the total microbial population recovered. The most frequently isolated motile actinomycetes were Actinoplanes and Dactylosporangium. Strains of Actinokineospora, Catenuloplanes and Kineosporia were also recovered, depending on the nature of the samples examined. Other motile actinomycetes that were occasionally isolated in small numbers included Actinosynnema, Geodermatophilus and Sporichthya.

Actinomycetales↗
PubMed2000

A possible mechanism for feedback regulation of the mouse tyrosinase gene by its 3' non-coding RNA fragments.

The 5' upstream regulatory region of the mouse tyrosinase gene contains a long (GA)n sequence, that may be capable of adopting a triple-helical conformation (triplex). We analyzed protein-DNA interactions in a part of the 5' upstream region containing the (GA)n sequence by gel retardation analysis and found evidence for a cell type-specific protein(s) that bound to this region. We also found a (TC)10 sequence about 100 bp downstream from a polyadenylation site of the gene. Examination of tyrosinase cDNAs and Northern analysis indicated that this sequence is transcribed and removed during 3' end-processing of the mRNA. Based on the hypothesis that the (TC)10 sequence binds to the (GA)n sequence and forms an intermolecular triplex, we performed the same gel retardation assay in the presence of the 3' non-coding RNA fragments containing the (UC)10 sequence. The probe DNA failed to interact with the cell type-specific protein(s). These results suggest a novel hypothesis for the regulation of the mouse tyrosinase gene, i.e. that the 3' non-coding RNA fragments of mouse tyrosinase transcripts suppress its own expression at the transcriptional level. This might occur by preventing cell type-specific protein factor(s) from binding to the regulatory cis-elements in the 5' upstream region of the gene, possibly through a triplex formation, although this hypothesis remains to be proven.

3' Untranslated Regions↗
PubMed2000

Involvement of cyclic AMP - PKA pathway in VIP-induced, charybdotoxin-sensitive relaxation of longitudinal muscle of the distal colon of Wistar-ST rats.

The intracellular mechanism of vasoactive intestinal peptide (VIP)-induced, charybdotoxin (ChTx)-sensitive relaxation of longitudinal muscle of the distal colon of Wistar-ST rats was studied. A single pulse or 100 pulses at 10 Hz of electrical field stimulation (EFS) induced rapid transient relaxation or that with a subsequent contraction of the longitudinal muscle in the presence of atropine and guanethidine, respectively. Rp-8 bromo cAMPS, an inhibitor of cyclic AMP dependent protein kinase (PKA), at 30 microM inhibited the relaxations induced by EFS with a single or 100 pulses maximally by about 80 or 60%, respectively. It also inhibited VIP (300 nM)-induced relaxation by 82%. VIP (100 nM - 1 microM) increased the cyclic AMP content of longitudinal muscle myenteric plexus preparations obtained from the distal colon. ChTx at 100 nM almost completely inhibited 8 bromo cyclic AMP-induced relaxation of the distal segments. EFS with two or three pulses at 10 Hz induced inhibitory junction potentials consisting of two phases, rapid and subsequent slow hyperpolarization in the membrane potential of longitudinal smooth muscle cells. Rp-cAMPS, another inhibitor of PKA, inhibited the delayed slow hyperpolarization. It also inhibited the exogenously added VIP-induced hyperpolarization of the cell membrane. Thus, the present study suggests that activation of PKA via activation of VIP receptors is associated with activation of ChTx-sensitive K(+) channels in relaxation of longitudinal muscle of the distal colon of Wistar-ST rats. British Journal of Pharmacology (2000) 129, 140 - 146

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2000

Increase in participation of vasoactive intestinal peptide in relaxation of the distal colon of Wistar rats with age.

Changes in participation of vasoactive intestinal peptide (VIP) in nonadrenergic noncholinergic (NANC) relaxation of longitudinal muscle of the distal colon with age were studied in 2- to 50-week-old Wistar rats in vitro. The extent of the VIP-mediated component of the relaxation induced by electrical field stimulation (EFS) was determined by the effect of VIP(10 - 28), a VIP receptor antagonist. In 2-week-old rats, the extent of the VIP-mediated component of the relaxation was scarce, about 10%, whereas the component gradually increase with age and reached the maximum extent 66% at 50-week-old. Since our previous results suggest that VIP induces NANC relaxation via activation of charybdotoxin (ChTx, a blocker of large conductance Ca(2+)-activated K(+) channel)-sensitive K(+) channels with concomitant slow hyperpolarization in the muscle cells, we next studied whether ChTx-sensitive component and slow hyperpolarization changes with age. Extent of ChTx-sensitive component of the relaxation increased with age, showing a very similar pattern to VIP-mediated one. EFS induced monophasic inhibitory junction potentials (i.j.ps) in longitudinal muscle cells of the distal colon of 2- and 4-week-old. EFS also induced biphasic i.j.ps in many longitudinal muscle cells of 8- and 50-week-old: rapid and subsequent slow hyperpolarization. A VIP receptor antagonist selectively inhibited the slow hyperpolarization. Exogenously added VIP induced no appreciable change in the membrane potential of longitudinal muscle cells of 2-week-old, whereas it induced slight slow hyperpolarization of the cell membrane in 4-week-old and magnitude of the hyperpolarization increased with age. On the other hand, relaxant response of the longitudinal muscle to exogenously added VIP was high in younger rats. The present results suggest that the role of VIP in mediating NANC relaxation of longitudinal muscle of the Wistar rat distal colon is very little at neonatal stage, but it increases with age.

Age Factors↗
PubMed2000

Glioma/glioblastoma-specific adenoviral gene expression using the nestin gene regulator.

For glioma- and glioblastoma-specific gene expression, we utilized a nestin regulatory element whose activity was evaluated by the reporter gene lacZ. Nestin is a 38-kDa intermediate filament protein, and is expressed specifically in the neuroepithelial stem cells. Nestin is detected in gliomas and glioblastomas, but not in normal brain tissue. We constructed a nestin gene regulator by placing nestin's second intron before the 5' upstream region (2iNP). To obtain enhanced expression of this tissue-specific regulator, we utilized the adenovirus double-infection method with a Cre-loxP on/off switching system. We constructed a 'regulator' vector, Ax2iNPNCre, which expresses Cre recombinase under the control of the nestin regulatory element, 2iNP. A 'reporter' vector, AxCALNLNZK, expresses lacZ under the control of a strong CAG promoter when the stuffer sequence has been removed by Cre recombinase at a pair of loxP sites. We used seven human glioma/glioblastoma cell lines: U251, KG-1C, NGM5, U87 MG, LN-Z308, NP-2 and T98G. Of these, nestin was expressed highly in U251 and KG-1C, less in NGM5, and undetectably in the other four lines. With the use of the two adenovirus vectors, we found X-gal staining and high nestin regulator-promoted beta-galactosidase activities in four of the seven glioma/glioblastoma cell lines. Staining was strong in U251, KG-1C and NGM5, and less in U87 MG. LacZ expression was nearly undetectable in the non-glioma cell line, HeLa, but a little in COS-7. The adenovirus double-infection method, which uses a nestin regulator, is applicable for glioma/glioblastoma-specific expression.

Adenoviridae↗
PubMed2000

Indirect amperometric detection of underivatized amino acids in microcolumn liquid chromatography with carbon film based ring-disk electrodes.

An indirect amperometric detection of underivatized amino acids has been developed using a carbon film based ring-disk electrode (CFBRDE) in microcolumn liquid chromatography (LC). Bromide present in the mobile phase could be efficiently oxidized to bromine at the upstream (disk) electrode, and was subsequently detected at the downstream (ring) electrode. Most of the underivatized amino acids that are electroinactive under conventional amperometric conditions react rapidly with the electrogenerated bromine, the concentration of amino acids can therefore be indirectly determined by continuously monitoring the reduction current of bromine. The signal monitored at the downstream electrode was largely dependent on the bromide concentration in the mobile phase. Under optimized conditions, the response linearly increased with the concentration for most of the amino acids over a concentration range of 1-100 microM, with a correlation coefficient of 0.990-0.993. The detection limits for most of the amino acids were below 1 microM (0.2 pmol). It was demonstrated that detection with a ring-disk electrode offers the advantages of achieving a much higher collection efficiency caused by a decrease in flow rate in the microcolumn LC.

Amino Acids↗
PubMed2000

Recognition of sleep paralysis among normal adults in Canada and in Japan.

There were no differences between Canada and Japan in the prevalence and symptoms of sleep paralysis (SP), but many more Canadians considered SP to be a dream. The difference was considered to be derived from the fact that there is a common expression for SP in Japan but there is not one in Canada. Then, we investigated why there are individuals who consider SP to be a dream and others who do not, and found that many Japanese who regarded it as a dream did not report the symptom of 'unable to move', while in Canada, self-evaluation of spirituality was different between the two groups.

Adult↗
PubMed2000

Expression of T-cadherin (CDH13, H-Cadherin) in human brain and its characteristics as a negative growth regulator of epidermal growth factor in neuroblastoma cells.

In the present study, we first examined the expression of T-cadherin in human CNS by northern blot analysis, immunohistochemical staining, and in situ hybridization. Northern blot analysis demonstrated expression of T-cadherin in human adult cerebral cortex, medulla, thalamus, and midbrain. Immunohistochemical staining with a newly generated monoclonal antibody, designated MA-511, revealed strong expression of T-cadherin in neural cell surface membrane and neurites in adult cerebral cortex, medulla oblongata, and nucleus olivaris. Little or no expression of T-cadherin was found in spinal cord. We further examined T-cadherin expression in various developing nervous systems, and found that T-cadherin expression was lower in developing brain than in adult brain. In situ hybridization revealed that neural cells in medulla oblongata and nucleus olivaris, but not in spinal cord, possessed T-cadherin molecules. We transfected T-cadherin-negative TGW and NH-12 neuroblastoma cells with a T-cadherin cDNA-containing expression vector. T-cadherin-expressing neuroblastoma cells lost mitogenic proliferative response to epidermal growth factor. Epidermal growth factor is known to be required for proliferation of neural stem cells. This finding, together with those of the present study, suggests that T-cadherin functions as a negative regulator of neural cell growth.

Adult↗
PubMed2000

The role of anti-epithelial cell antibodies in the pathogenesis of bilateral radiation pneumonitis caused by unilateral thoracic irradiation.

Two cases of bilateral radiation pneumonitis associated with unilateral thoracic irradiation against lung cancer are described. Both patients died of respiratory failure and autopsy was performed. Histologically, bilateral diffuse alveolar damage was demonstrated in both cases, associated with marked organization of hyaline membrane in one case (case 1). In addition, numerous hyperplastic type II pneumocytes which strongly expressed cytokeratins 8, 18 and 19 were observed. In both patients' sera, antibodies against cytokeratin 8, 18 and 19 were demonstrated by a Western immunoblot. The possible association between autoantibodies to cytokeratins and diffuse alveolar damage observed in patients with bilateral radiation pneumonitis are discussed.

Adenocarcinoma↗
PubMed2000

Alternative sources of gametes: reality or science fiction?

Although great progress has been made in both the investigation and treatment of infertility, a considerable number of patients still fail to conceive. Spermatogenic failure and/or oocyte ageing appear to be responsible for a large proportion of cases. The use of donor gametes may bring legal, ethical and even social problems of acceptance that can discourage infertile couples from the donor route. Fortunately, emerging reproductive technologies and preliminary results from animal experiments provide some hope for alternative sources of gametes through which these infertile patients can finally conceive their own genetic child. In conjunction with intracytoplasmic sperm injection (ICSI), fertilization of human oocytes with immature sperm precursors, e.g. spermatids and even secondary spermatocytes, has resulted in healthy babies. Pregnancies have also resulted from the use of spermatids derived from in-vitro spermatogenesis. In the mouse, even primary spermatocytes appear able to participate in normal embryogenesis. In view of the possibility for transplantation and even xenotransplantation of spermatogonia to a host testis in animals, a similar use of human male stem cells might provide an attractive source for the treatment of males with arrested spermatogenesis, as well as male cancer patients. Transplantation of somatic cell nuclei and their haploidization within oocytes may prove to be a practical way of eradicating age-related aneuploidy and so constitute an innovative source of healthy oocytes. Most importantly, however, the safety of the procedures described here needs to be proven before their application to the human arena. Finally, we discuss the implications of cytoplasmic quality and of genetic imprinting in the context of these manipulations.

Animals↗
PubMed2000

Multiple elements for negative regulation of the rat catalase gene expression in dedifferentiated hepatoma cells.

Like such hepatic genes as those for albumin and aldolase B, the rat catalase gene shows markedly reduced expression in carcinogenesis of hepatocytes. Strong silencer activity has been widely observed in the 5'-flanking region of the gene, downstream from the G-rich sequence identified in a previous study. In this study, we identified and characterized multiple elements involved in negative regulation of catalase gene expression by reporter assay and gel shift assay. One of the silencer elements is located 3 kb upstream of the gene and has GATATCCCGATATC as core sequence. The observation that protein binding to the element is abundantly expressed in dedifferentiated hepatoma cell lines, but scarcely in well-differentiated cell lines suggests that this element is involved in negative regulation of the catalase gene expression in hepatocarcinogenesis. This element was targeted by a novel 20-kDa nuclear protein, which is designated HNRF (hepatocarcinogenesis-related negative regulatory factor).

Animals↗
PubMed2000

The application of the atomic force microscope to studies of medically important protozoan parasites.

Both living and fixed specimens of the medically-important parasitic protozoa, Trypanosoma cruzi, Toxoplasma gondii, Giardia lamblia, Entamoeba histolytica, and Acanthamoeba spp. were studied by atomic force microscopy (AFM). The preparation of fixed specimens was similar to methods used for either scanning or transmission electron microscopy. AFM scanning was performed using both contact and tapping modes. A classical fixation procedure utilizing glutaraldehyde followed by ethanol dehydration was not suitable for all parasite species. AFM images could not be obtained from fixed samples of T. cruzi, T. gondii or E. histolytica. However, excellent topographic images could be obtained from specimens of G. lamblia and Acanthamoeba under identical conditions. Critical point drying permitted AFM imaging of both trypomastigote and epimastigote stages of T. cruzi. Phase imaging of T. cruzi elucidated unique surface details at a level of resolution not visible using any other imaging modalities. AFM elasticity map imaging of T. cruzi-infected and T. gondii-infected cells demonstrated that both parasites were markedly firmer than the surrounding host cell cytoplasm. The parasitophorous vacuole surrounding replicating T. gondii tachyzoites was also visualized by elasticity map imaging. These data suggest that although much remains to be learned about preparing parasitic protozoa for AFM imaging, the technique has the potential of providing unique and important insights into these disease causing organisms.

Amoebida↗
PubMed2000

[Studies on current trend of imported malaria in Japan--pediatric cases in recent 20 years].

Imported malaria has been increasing according to the recent globalization of Japan. There are about 120 clinical cases of malaria which include a few pediatric cases (approximately 1%) every year. Generally, pediatric cases often have an atypical onset and course compared to adult cases, and also develop serious and fatal effects in a short time. In this study, we examined imported malaria cases in subjects under 15 years old from 1980 to 1999 conducted by Research group on clinical evaluation against orphan drugs in the treatment of imported tropical diseases and parasitic diseases. During the 20 years we found 44 clinical cases in children. Of these 70% were foreign cases. Among the species of parasites, there were 21 cases of Vivax malaria and 17 cases of Falciparum malaria and a few cases of Malariae and Ovale malaria were also found, which is rare even in adults. Concerning the drugs chosen in Japan for chemotherapy to treat malaria, chloroquine and primaquine seemed to be employed most frequently before 1990, however mefloquine or artesunate seemed to be more common after 1990. Also, most pediatric cases were former residents or refugees from tropical countries, however some cases were in Japanese children who had recently visited those areas with their families. There have been no fatalities in pediatric cases of malaria, however tropical diseases, including malaria, must be rule out, when examining pyretic children, considering the number of travelers going abroad has been increasing.

Adolescent↗
PubMed2000

Changes in plasma adenosine concentrations during normal pregnancy.

The aim of this study was to measure changes in plasma adenosine concentration [ADO] during a normal pregnancy and to evaluate the possible role of platelets and red blood cells (RBC) as causes of changes in plasma [ADO]. We measured the plasma [ADO] in normal pregnant women (n = 11) during the first, second and third trimesters. The mean plasma [ADO] in the third trimester was 0.41 +/- 0.08 microM (means +/- SEM), significantly higher than in the first and second trimesters (p < 0.05). In pregnant women, platelet and RBC counts, hematocrit and hemoglobin concentration decreased slightly throughout the pregnancy. The elevation in the plasma [ADO] correlated inversely with the platelet count (r = -0.43, p < 0.05). These results suggest that an increase in the plasma [ADO] in the third trimester may be attributed to the enhanced adenosine release from activated platelets.

Adenosine↗