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Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 127 records · Page 7Linked to original sources
PubMed2000

Thalamic potentials evoked by motor point stimulation.

We studied thalamic potentials elicited by stimulation of the extensor digitorum communis muscle motor point during stereotactic surgery for movement disorders. In 6 patients with Parkinson's disease and 1 with cerebral palsy, muscle afferent-evoked thalamic potentials (METPs) were recorded in the ventral intermediate (Vim) nucleus. METPs consisted of three peaks with an average latency of 11.02 +/- 0.80 ms for initial positive peak (PI), 13.04 +/- 0.58 ms for negative (N), and 14.30 +/- 0.87 ms for later positive peak (PII). These METPs were different from those evoked by median nerve stimulation. No peaks corresponding to the N20 component of the somatosensory evoked potential were recorded from C3 or C4 scalp electrodes. The METP amplitudes in the ventrolateral (VL) nucleus were markedly lower than those in the Vim nucleus. These findings suggest that METPs in the Vim nucleus are responses that occur via the fast conducting group Ia afferent fibers rather than somatosensory afferent fibers.

Aged↗
PubMed2000

Cyclosporine A-associated fatal central nervous system angiopathy in a bone marrow transplant recipient: an autopsy case.

We report here the case of a 32-year-old woman who suffered from a unique angiopathy in the central nervous system (CNS). She died of multiple infarcts in the brain stem and cerebellum during treatment with cyclosporine A after bone marrow transplantation for refractory anemia with excess of blasts. The autopsy findings showed segmental narrowing of the basilar artery, in which circumferential dissection of the internal elastic lamina had occurred. The distal portion of the basilar artery was obstructed by upward dislocation of the dissected intima. Similar angiopathy was also observed at multiple sites along the basilar artery branches. These findings suggest endothelial damage, including vasoconstriction and dissection of the CNS arteries.

Adult↗
PubMed2000

The influence of vascular pressure and angiographic characteristics on haemorrhage from arteriovenous malformations.

BACKGROUND: The present study was designed to determine whether there is a physiological explanation for the predisposition of patients with certain angiographic characteristics to haemorrhage from cerebral arteriovenous malformations (AVMs). METHODS: Intra-operative measurement of feeding artery pressure (FAP) and intravascular pressures in the draining venous system [draining vein pressure (DVP) and cranial sinus pressure (SP)] were performed for 30 AVM cases using direct puncture of the vessels. The correlation between pressures and previously described angiographic characteristics predisposing to haemorrhage were evaluated. FINDINGS: Small nidus size and only one draining vein increased the risk of haemorrhage. FAP and DVP are both inversely related to the number of draining veins and the size of the AVMs. DVP was significantly higher in AVMs with haemorrhage (23.1+/-8.7 mmHg) than in those without (13.5+/-4.4), as was FAP (58.6+/-12.8 as opposed to 38.7+/-4. 7) (p<0.05). Moreover, the difference between systemic blood pressure and the FAP with haemorrhagic AVMs (17.0+/-9.5 mmHg) was significantly lower than that in nonhaemorrhagic cases (33.7+/-5.5) (p<0.05). The pressure difference between the feeding artery and draining vein was not significant between the haemorrhagic and nonhaemorrhagic groups. There was no significant difference of SP between haemorrhagic and nonhaemorrhagic patients. INTERPRETATION: The present study suggests that a high DVP probably induced by high resistance in the venous drainage system, as well as a high FAP, may contribute to the development of haemorrhage from AVMs, and physiologically supports previous reports that small AVMs and AVMs with only one draining vein are susceptible to haemorrhage.

Cerebral Angiography↗
PubMed2000

Growth of incidental meningiomas.

The aim of this study was to assess the growth of incidental meningiomas, to establish a strategy for dealing with these tumours. The cases of 37 patients with a meningioma revealed incidentally by computerized tomography or magnetic resonance imaging, who were followed at least once by an additional imaging study, were reviewed. The tumour volume was calculated, to estimate the annual growth rate of the incidental meningiomas. Nine of the 37 patients (24.3%) showed a considerable increase (the annual growth rate > 1 cu cm/year) in their tumour volume (tumour growth). There was no significant difference in the follow-up period, age, or the volume of tumour between the patients with and without tumour growth. However, a multivariate analysis revealed that the likelihood of tumour growth independently and significantly increased according to a decrease in the age of the patients (Odds ratio 0.18 for one-standard-deviation change (ISD) 12.6 years, p = 0.042) and according to an increase in the volume of the tumour (Odds ratio 3.64 for ISD 4.46 cu cm, p = 0.042). The majority of patients with incidental meningioma can be apparently observed without any surgical intervention, because their annual growth rates are generally less than 1 cu cm/year. However, clinical and radiological observations would be advisable for these patients (especially young patients and patients with a large tumour), in view of the presence of rapidly growing tumours in some of the patients.

Adult↗
PubMed2000

Evidence for the presence of 1,2-cyclic acetal type sn-glycero-3-phosphoethanolamines in the sea anemone, Actiniogeton sp.

Five 1,2-cyclic acetal-type sn-glycero-3-phosphoethanolamines (CGPE) were isolated in a pure state from the sea anemone, Actiniogeton sp. (Coelenterata). Their structures, including the absolute configurations, have been determined on the basis of chemical and spectral data to be so-called Feulgen's acetalphosphatides, which have been regarded as artifacts derived from original plasmalogens. We examined whether these CGPE are intact constituents in the animal tissues and obtained reliable confirmation that CGPE are normally present in the sea anemone.

Animals↗
PubMed2000

Potential antitumor-promoting diterpenoids from the stem bark of Picea glehni.

A novel rearranged labdane-type diterpenoid, 19(4-->3)abeo-8alpha, 13(S)-epoxylabda-4(18),14-diene (1), and two new abietane-type diterpenoids, 19-nor-abieta-4(18),8,11,13-tetraen-7-one (2) and 12-hydroxydehydroabietic acid (3) were isolated from the stem bark of Picea glehni, together with seven known diterpenoids-13-epimanoyl oxide (4), dehydroabietic acid (5), (11E)-14, 15-bisnor-8alpha-hydroxy-11-labden-13-one (6), abieta-8,11, 13-trien-7-one (7), 9alpha,13alpha-epidioxyabiet-8(14)-en-18-oic acid (8), 9,10alpha-epoxy-9,10-seco-abieta-8,11,13-trien-18-oic acid (9), and methyl 15-hydroxy-7-oxo-dehydroabietate (10). Compounds 5-8 and 10 showed potent inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate.

Antineoplastic Agents↗
PubMed2000

Labdane-type diterpenes and a nordrimane-type sesquiterpene from the stem bark of Thuja standishii.

Two new labdane-type diterpene aldehydes, 15-oxolabda-8(17),11(Z), 13(E)-trien-19-oic acid (1) and 15-oxolabda-8(17),11(Z), 13(Z)-trien-19-oic acid (2), and a new nordrimane-type sesquiterpene, 12-oxo-11-nordrim-8-en-14-oic acid (3), along with a known diterpene, 15-nor-14-oxolabda-8(17),12(E)-dien-19-oic acid (4), were isolated from the stem bark of Thuja standishii. The structures of 1-3 were established by spectroscopic methods.

Cycadopsida↗
PubMed2000

Four new trisnorlanostene-type triterpenoids from the stem bark of Pinus luchuensis.

Four new 25,26,27-trisnorlanostene-type triterpenoids were isolated from the stem bark of Pinus luchuensis, together with five known compounds. These new compounds were characterized as 25,26, 27-trisnor-3 alpha-hydroxy-lanost-9(11)-en-24-oic acid (1), 25,26, 27-trisnor-3 alpha-methoxy-lanost-9(11)-en-24-oic acid (2), 25,26, 27-trisnor-3 beta-methoxy-lanost-9(11)-en-24-oic acid (3), and 25,26, 27-trisnor-3-oxo-lanost-9(11)-en-24-oic acid (4) on the basis of MS and NMR evidence.

Chromatography, Gel↗
PubMed2000

Bioactive steroids from the whole herb of Euphorbia chamaesyce.

Three new ergostane-type steroids, 3beta-hydroxy-4alpha, 14alpha-dimethyl-5alpha-ergosta-8,24(28)-dien-11 -one (1); 3beta, 11alpha-dihydroxy-4alpha,14alpha-dimethyl-5alpha -ergosta-8, 24(28)-dien-7-one (2); and 3beta,7alpha-dihydroxy-4alpha, 14alpha-dimethyl-5alpha-ergosta-8,24(28)-dien-11 -one (3), were isolated, together with two known triterpenoids, wrightial and lup-20(30)-ene-3beta,29-diol from the whole herb of Euphorbia chamaesyce. Compound 3 showed a potent inhibitory effect on Epstein-Barr virus early antigen activation induced by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA).

Antigens, Viral↗
PubMed2000

Demonstration of hydroxyindole-O-methyltransferase (HIOMT) mRNA expression in pineal parenchymal tumors: histochemical in situ hybridization.

The expression of hydroxyindole-O-methyltransferase (HIOMT), an enzyme catalyzing the final step of melatonin biosynthesis, was examined in three pineoblastomas and five pineocytomas by in situ hybridization analysis. Distinct hybridization signals for HIOMT mRNA, though weaker than in normal pineal gland pinealocytes, were detected in two of the three pineoblastoma and three of the five pineocytoma cases. Of the pineoblastomas, hybridization signals were observed in most tumor cells of one case, while in another, signals were detected in occasional cells clustered or scattered throughout the neoplastic field. Of the pineocytomas, signals were detected in most tumor cells of two cases, while in one case, signals were detected only in occasional cells. Among these specimens, one pineoblastoma and one pineocytoma were also analyzed using northern blot and reverse transcription polymerase chain reaction (RT-PCR) analyses. In the northern blot analysis, an apparently single band corresponding to the size of HIOMT mRNA was detected in both pineoblastoma and pineocytoma RNA blots. In the RT-PCR analysis, three species of HIOMT mRNA generated via alternative splicing were detected in both tumors. These results suggest that the neoplastic cells of pineoblastomas and pineocytomas often retain the ability to express HIOMT mRNA, as in normal pinealocytes, and that HIOMT is a useful tumor marker for the diagnosis of pineal parenchymal tumors.

Acetylserotonin O-Methyltransferase↗
PubMed2000

Improvement in bronchiolitis obliterans organizing pneumonia in a child after allogeneic bone marrow transplantation by a combination of oral prednisolone and low dose erythromycin.

We report a 13-year-old boy who developed dyspnea at rest 1 year after the occurrence of cGVHD following an allogeneic bone marrow transplant (BMT). Pulmonary function data, imaging studies, lung biopsy, and bronchoalveolar lavage were consistent with the diagnosis of bronchiolitis obliterans organizing pneumonia (BOOP). Although reports suggest that oral methylprednisolone or methylprednisolone pulse therapies improve BOOP after BMT, we treated our patient with a combination of oral prednisolone (1 mg/kg) and low dose erythromycin (10 mg/kg) to avoid the side-effects of high-dose steroids. With this therapy, our patient showed clinical and radiological improvements within 1 week. The steroids were tapered off 12 months later and erythromycin was given for 14 months. We conclude that therapy consisting of a combination of oral prednisolone and low-dose erythromycin for BOOP after BMT may minimize the dose and duration of steroid use.

Administration, Oral↗
PubMed2000

Natural killer cell depletion by anti-asialo GM1 antiserum treatment enhances human hematopoietic stem cell engraftment in NOD/Shi-scid mice.

The scid mutation was backcrossed on to the NOD/Shi mouse background, resulting in the development of NOD/Shi-scid mice, which showed lack of mature lymphocytes, macrophage dysfunction and absence of circulating complement, but were not as impaired in natural killer (NK) cell activity as NOD/LtSz-scid mice. We then examined the effect of recipient NK cell depletion by anti-asialo GM1 antiserum on the repopulation of human cord blood (CB) hematopoietic stem cells (HSC) in NOD/Shi-scid mice to clarify the role of recipient NK cells in human HSC engraftment. The anti-asialo GM1 antiserum treatment significantly enhanced the engraftment of CB CD34+ cells, but did not affect the differentiation of the engrafted HSC into each hematopoietic lineage. The NK cell depletion was effective at early stages of the engraftment, but not 3 weeks after the transplantation. The anti-asialo GM1 antiserum treatment did not improve the engraftment by human HSC in scid mice which lack mature lymphocytes, but show neither macrophage dysfunction nor a reduction in circulating complement, indicating that macrophages and/or complement also have roles in HSC graft rejection. The present study indicates that the preconditioning targeting of recipient NK cells in addition to T cell suppression and myeloablation might prevent HSC graft failure, and that NOD/Shi-scid mice treated with anti-asialo GM1 antiserum could provide a useful tool for evaluating the repopulating ability of transplantable human HSC.

Animals↗
PubMed2000

The amino terminus targets the mixed lineage leukemia (MLL) protein to the nucleolus, nuclear matrix and mitotic chromosomal scaffolds.

The mixed-lineage leukemia gene (MLL) is associated with more than 25 chromosomal translocations involving band 11q23 in diverse subtypes of human acute leukemia. Conditional expression of a 50 kDa amino terminal fragment spanning the AT hook motifs of MLL (MLL3AT) causes cell cycle arrest, upregulation of p21Cip1 and p27KiP1 and partial monocytic differentiation of the monoblastic U937 cell line, suggesting a major role for MLL3AT in MLL-AF9-induced myelomonocytic differentiation. In this study, we analyzed the subcellular localization of conditionally expressed MLL3AT in both U937 and HeLa cell lines. Immunofluorescence staining, confocal laser scanning microscopy and immunoelectron microscopy indicated that MLL3AT, like endogenous MLL, localized in the nucleoplasm in a punctate pattern of distribution, including regions attached to the nuclear envelope and the periphery of the nucleolus. We found that MLL3AT and endogenous MLL were present in interphase nuclear matrices and colocalized with topoisomerase II to mitotic chromosomal scaffolds. Nucleoplasm and nucleolar localization was observed even for MLL-AF9 and MLL-AF4 conditionally expressed chimeric proteins, suggesting a common target conferred by the amino terminus of MLL to many if not all the chimeric MLL proteins. The nuclear matrix/scaffold association suggests a role for the amino terminus of MLL in the modulation of chromatin structure, leading to epigenetic effects on the maintenance of gene expression.

Active Transport, Cell Nucleus↗
PubMed2000

Exclusive expression of G-CSF receptor on myeloid progenitors in bone marrow CD34+ cells.

Although granulocyte colony-stimulating factor (G-CSF) has been reported to act on cells of neutrophilic lineage, the administration of G-CSF to induce the mobilization of various haematopoietic progenitors into the circulation. We analysed the expression of receptors for G-CSF (G-CSFR) on human bone marrow and G-CSF-mobilized peripheral blood CD34+ cells, and examined the proliferation and differentiation capabilities of sorted CD34+G-CSFR+ and CD34+G-CSFR- cells using methylcellulose clonal culture. Flow cytometric analysis showed that G-CSFR was expressed on 14.9 +/- 4.9% of bone marrow CD34+ cells, most of which were included in CD34+CD33+ and CD34+CD38+ cell fractions. In clonal cultures, CD34+G-CSFR+ cells produced only myeloid colonies, whereas CD34+G-CSFR- cells produced erythroid bursts, megakaryocyte and multilineage colonies. When incubated with the cytokine cocktail for 5 d, CD34+G-CSFR- cells generated CD34+G-CSFR+ myeloid progenitors. In G-CSF-mobilized peripheral blood, CD34+ cells contained 10.8 +/- 5.8% of G-CSFR+ cells, most of which were also myeloid progenitors, although CD34+G-CSFR- cells contained a substantial number of myeloid progenitors. These results indicated that the expression of G-CSFR on CD34+ cells is restricted to myeloid progenitors, suggesting that the specific activity of G-CSF on myelopoiesis depends on the exclusive expression of its receptor on myeloid progenitors, and that the mobilization of various haematopoietic progenitors is not a direct effect of G-CSF in humans.

Adult↗
PubMed2000

Cytokine requirement for the development of T-lymphoid lineage potential in clonal lymphohaematopoietic progenitors in vitro.

The early process of T-cell development prior to thymic colonization has been poorly investigated because of the lack of a sensitive assay. We have developed a two-step in vitro culture system by combining a clonal culture with a fetal thymus organ culture (FTOC) and analysed the early development of T cells from lymphohaematopoietic progenitors. Cells of immature colonies derived from bone marrow cells of 5-fluorouracil (5FU)-treated mice using various combinations of early acting cytokines were transferred into a FTOC. All the combinations of stem cell factor (SCF), interleukin (IL)-3 and IL-6 capable of inducing colony formation supported T-cell generation. IL-11 and the Flt3 ligand possessed T-lineage promotional effects similar to IL-6 and SCF respectively. However, there were some quantitative differences in the final T-cell yield among cytokine combinations. Thus, the commitment towards T lineage in lymphohaematopoietic progenitors may be an event determined intrinsically rather than induced by specific stimuli, but there may be a hierarchy between the activity of cytokines in further development. Furthermore, we examined the T-lineage potential of individual colonies derived from Lin(-)c-Kit(+)Sca-1(+) cells clone-sorted from post-5FU marrow cells. No colonies that contained only myelocytic progenitors showed T-lineage potential, but 23.3% of colonies with a haematopoietic multipotentiality did. Therefore, the divergence of the T lineage from other lineages such as myeloid potential may occur at an early stage of the hierarchy of haematopoiesis. The proposed method should prove valuable for exploring the molecular and cellular changes that occur during early T-cell development before thymic colonization.

Animals↗
PubMed2000

Bacterial cell death induced by human pro-apoptotic Bax is blocked by an RNase E mutant that functions in an anti-oxidant pathway.

BACKGROUND: Bax is a member of the Bcl-2 family and induces apoptosis of mammalian cells. We have shown that a trace amount of human Bax induces the cell death of Escherichia coli, accompanied by damage to DNA, and that the region of Bax which is lethal to E. coli is also responsible for apoptosis-inducing activity in the mammalian cells. RESULTS: We isolated a Bax-resistant mutant from E. coli cells that survive in the presence of paraquat, a generator of superoxide, by screening a library constructed from the random insertion of a transposon. Psb1 (paraquat-resistant, suppressor of Bax-1) mutant had a Tn 10 transposon inserted in the rne gene of E. coli, splitting the RNase E gene (rne) into N- and C-terminal halves. The introduction of the truncated 5' end of rne specifically enhanced resistance to paraquat, prevented cell death induced by Bax and decreased the intracellular H2O2 concentration. The region responsible for the paraquat- and Bax-resistance was not the catalytic site for the endoribonuclease activity of RNase E. CONCLUSIONS: The N-terminal region of the RNase E protein inhibits bacterial death induced by human Bax as well as paraquat through a unique mechanism that is distinct from RNA digestion. This study implies that the protection of bacterial death induced by Bax is associated with an anti-oxidant pathway and that a mutant RNase E has a novel function as an anti-oxidant.

Apoptosis↗
PubMed2000

Intronic U50 small-nucleolar-RNA (snoRNA) host gene of no protein-coding potential is mapped at the chromosome breakpoint t(3;6)(q27;q15) of human B-cell lymphoma.

BACKGROUND: In eukaryotic cells, nucleolar processing of preribosomal RNAs (prerRNAs) is assisted by a large number of small nucleolar RNAs (snoRNAs) that function in the 2'-O-methylation or the pseudouridylation of rRNAs. Most snoRNAs so far characterized are encoded and processed from introns of premRNAs. RESULTS: We found a novel intronic snoRNA gene, named U50HG, located on chromosome 6q15, at the breakpoint of chromosomal translocation t(3;6)(q27;q15). The U50HG gene is composed of six exons, whose spliced transcripts have little potential for coding a protein, and its introns produce both U50 and U50-like (U50') snoRNAs that are localized in nucleoli. It possesses an oligopyrimidine tract that is characteristic of the 5'-terminal oligopyrimidine (5'TOP) class of genes which have been shown to be coordinately regulated in response to cell growth. CONCLUSIONS: U50HG is a member of the nonprotein-coding multiple snoRNA host gene family, as well as of the 5'TOP gene family similar to UHG (U22 host gene), U17HG (U17 host gene), U19HG (U19 host gene) and gas5 (growth arrest-specific transcript 5 gene). It is novel to find that the snoRNA gene is located at the breakpoint of chromosomal translocation t(3;6)(q27;q15) involved in human B-cell lymphoma.

Alternative Splicing↗