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Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 253 records · Page 14Linked to original sources
PubMed1998

[Heerfordt's syndrome remitting without corticosteroid therapy].

A 25-year-old woman presented with low-grade fever, uveitis, and bilateral swelling of the parotid glands. Her older sister had a history of sarcoidosis. A chest X-ray film showed bilateral hilar lymphadenopathy. The low-grade fever persisted after admission. Ga scintigraphy showed abnormal uptake in the parotid glands and hilar lymph nodes bilaterally. Sarcoidosis was diagnosed histologically after epithelioid cell granulomas without caseous necrosis were found in a specimen obtained by transbronchial biopsy. Heerfordt's syndrome was the final diagnosis. Six days after admission, left facial and left trigeminal nerve paralysis developed. The symptoms remitted without steroid therapy and, as of eight months after discharge there had been no evidence of recurrence.

Adult↗
PubMed1998

[Stereotaxy during intravenous anesthesia with propofol].

A series of 30 patients, who underwent stereotactic surgery for movement disorder under intravenous propofol anesthesia between March, 1995 and December, 1997, was retrospectively reviewed. In 28 patients with Parkinson's disease including seven juvenile cases of parkinsonism, the postoperative motor and ADL scores on the Unified Parkinson's Disease Rating Scale significantly improved. In the other two patients, one of whom had severe posttraumatic tremor and the other had cerebral palsy, the stereotactic surgery produced considerable alleviation of their symptoms. We evaluated and discussed the usefulness of intravenous propofol anesthesia in stereotaxy. Except for one patient who had an allergic reaction against propofol, none of the patients complained of intraoperative pain postoperatively. Wake-up tests were performed to record neural noise levels in 26 cases. This recording was performed under propofol anesthesia in two cases with advanced Parkinson's disease and one with cerebral palsy. In these patients, neural noise levels were recorded and were useful for identifying the target. Although the tremor disappeared under propofol anesthesia in 17 patients presenting with moderate or severe tremor, it was presented again after discontinuation of propofol. Wake-up test, therefore, made a good evaluation of Vim thalamotomy for tremor. In juvenile parkinsonian patients, three presented with dopa-induced dyskinesia (DID) during propofol infusion. In two of them, the DID emerged immediately after posteroventral pallidotomy and continued 4 or 10 hours after stereotaxy. These findings suggest that propofol possibly has an anti-parkinsonian effect. Intravenous propofol anesthesia is a useful method to use with stereotactic surgery for movement disorders.

Adult↗
PubMed1997

Synergistic action of Flt3 and gp130 signalings in human hematopoiesis.

We recently showed that c-kit signal synergizes with glycoprotein (gp)130 signal mediated by a complex of interleukin (IL)-6 and soluble IL-6 receptor (IL-6/sIL-6R) to stimulate the expansion of human primitive hematopoietic progenitor cells and erythropoietin-independent erythropoiesis. In the present study, we examined the effect of a ligand for Flt3 (FL), whose receptor tyrosine kinase is closely related to c-kit, in combination with IL-6/sIL-6R on human hematopoiesis in vitro. In serum-containing methylcellulose clonal culture of cord blood CD34(+) cells, whereas FL alone stimulated only granulocyte-macrophage (GM) colony formation, erythroid bursts and mixed colonies in addition to GM colonies were induced by FL with IL-6/sIL-6R, but not IL-6/sIL-6R alone. In suspension culture, CD34(+) cells generated a small number of myeloid cells in the presence of FL or IL-6/sIL-6R alone. However, the addition of IL-6/sIL-6R to the culture with FL induced the generation of a significant number of erythroid cells and megakaryocytes in addition to myeloid cells. The combination of FL and IL-6/sIL-6R also induced a remarkable expansion of GM colony- and erythroid burst-forming cells and multipotential progenitors, although FL or IL-6/sIL-6R alone induced the generation of only a small number of progenitors for GM colonies. The synergistic effects of FL and IL-6/sIL-6R were confirmed in serum-free clonal and suspension cultures. In addition, the addition of anti-human gp130 monoclonal antibodies abrogated the synergistic action. These results indicate that Flt3 signal, as well as c-kit signal, synergizes with gp130 signal to stimulate human myelopoiesis, erythropoiesis and megakaryopoiesis, and the expansion of primitive multipotential hematopoietic progenitor cells.

Antibodies, Monoclonal↗
PubMed1997

Expression of telomerase RNA, telomerase activity, and telomere length in human gliomas.

To understand the mechanisms of telomere maintenance in human gliomas, telomerase activity, telomerase RNA expression and telomere length of surgically excised glioma samples were analyzed. Sixty-five percent of gliomas exhibited telomerase activity, the occurrence of which was not related to their histological malignancy scale. Not only the telomerase-positive gliomas, but also the telomerase-negative gliomas and normal brain expressed telomerase RNA, suggesting that the presence of telomerase RNA component does not indicate the presence of telomerase activity. Compared with telomerase-positive gliomas, telomerase-negative gliomas had long heterogeneous telomeric terminal restriction fragments. These data suggest that in addition to the telomerase-dependent mechanism, a telomerase-independent mechanism for telomere maintenance may be present in human gliomas.

Astrocytoma↗
PubMed1997

5,6-Cis-penems: broad-spectrum anti-methicillin-resistant Staphylococcus aureus beta-lactam antibiotics.

5,6-cis-Penem derivatives have been synthesized and evaluated as anti-MRSA antibiotics. The cis-penems 5 and 6 showed potent activities against not only MRSA but also a wide variety of bacteria including beta-lactamase-producing microorganisms. These compounds were designed to have high affinity to the penicillin-binding protein 2a of MRSA and to form stable acyl intermediates with beta-lactamases by blocking the deacylating water molecule.

Anti-Bacterial Agents↗
PubMed1997

Treatment of rat hemiparkinson model with xenogeneic neural transplantation: tolerance induction by anti-T-cell antibodies.

To obtain basic knowledge for the application of xenogeneic neural transplantation to patients with Parkinson's disease, the rejection process of xenogeneic neural grafts in rats was examined and a therapy to control it was developed. Tissues including the ventral mesencephalon were taken from mouse embryos and transplanted into the right lateral ventricle of mature male rats. Transplanted xenografts were usually rejected by day 15. To prevent the graft rejection, host rats were treated with anti-T-cell receptor alphabeta (anti-TCR alphabeta) or anti-CD2 monoclonal antibody (mAb) or by a combination of the two. Anti-TCR alphabeta (1 mg/kg) and anti-CD2 (7 mg/kg) mAb were administered for 3 consecutive days (day -2, -1, and 0 of transplantation). Although the administration of mAb against either CD2 or TCR alphabeta did not induce tolerance, the combination therapy with anti-CD2 and anti-TCR alphabeta mAb produced graft survival for more than 100 days. The tolerance induced by this combined antibody therapy is antigen specific because rats with long-term surviving neural xenograft accepted a second neural graft from the same donor strain C3H/He mouse, but not from a third-party strain BALB/c mouse, without additional treatment. In addition, T cells isolated from these rats did not respond to cultured C3H/He brain cells, but did respond vigorously to BALB/c brain cells in mixed lymphocyte reaction. More importantly, the finding that xenograft transplantation with the proper treatment reduced the rotation rate of 6-OHDA-lesioned rats confirmed that surviving grafts functioned properly. The results of the present study suggest that xenogeneic neural transplantation in combination with T-cell-targeted immunotherapy is an effective approach for treatment of Parkinson's disease.

Animals↗
PubMed1997

acrB mutation located at carboxyl-terminal region of gyrase B subunit reduces DNA binding of DNA gyrase.

Mutations that exhibit susceptibility to acriflavine have been isolated and classified as acr mutations in Escherichia coli. We cloned the acrB gene, which has been identified as a mutation of the gyrB gene, and found a double point mutation altering two consecutive amino acids (S759R/R760C) in the COOH-terminal region of the gyrase B subunit. The mutant B subunit was found to associate with the A subunit to make the quaternary structure, and the reconstituted gyrase showed an 80-fold reduction of specific activity in DNA supercoiling assay; the sensitivity to acriflavine was not different in the same unit of wild-type and mutant gyrases. The mutant enzyme retained intrinsic ATPase activity, but DNA-dependent stimulation was observed infrequently. A gel shift assay showed that acriflavine inhibited the DNA binding of gyrase. The acrB mutation also reduced significantly the DNA binding of gyrase but did not change the sensitivity to acriflavine. These results revealed that the acrB mutation is related to the inhibitory mechanism of acriflavine; and the acriflavine sensitivity of the mutant, at least in vitro, is caused mainly by reduction of the enzyme activity. Further, our findings suggest that the COOH-terminal region of the B subunit is essential for the initial binding of gyrase to the substrate DNA.

Amino Acid Sequence↗
PubMed1997

The presence of K-12 ras mutations in duodenal adenocarcinomas and the absence of ras mutations in other small bowel adenocarcinomas and carcinoid tumors.

BACKGROUND: Adenocarcinomas and carcinoid tumors are the most common malignant tumors of the small intestine. K-ras oncogene mutations at codon 12 are common in gastric, pancreatic, and colon carcinomas, with an incidence of 35-88%. K-ras mutations have not been extensively studied in either adenocarcinomas or carcinoid tumors of the small bowel. The purpose of this study was to determine whether ras mutations play an important role in the formation of these tumors. METHODS: Archival tissues from 28 adenocarcinomas and 22 carcinoid tumors of the small bowel were studied, along with archival tissues from 32 adenocarcinomas of the large bowel, which were used as controls. DNA from the small intestine tumors was analyzed for K-ras, H-ras, and N-ras oncogene mutations at codons 12, 13, and 61, using polymerase chain reaction and sequence specific oligonucleotide hybridization techniques. Large bowel adenocarcinomas were analyzed for K-ras mutations at codons 12 and 13. RESULTS: A point mutation of K-ras at codon 12 was detected in 4 of 28 (14.3%) of the small bowel adenocarcinomas, in 12 of 32 (37.5%) of the large bowel adenocarcinomas, and in 0 of 22 small intestine carcinoid tumors. No other K-ras, H-ras, or N-ras mutations were detected in any of the small bowel tumors. Each small intestine K-ras mutation was found in a duodenal adenocarcinoma (4 of 12 cases, 33%), whereas none occurred in 16 other jejunal or ileal adenocarcinomas. CONCLUSIONS: K-ras mutations appear to play a significant role in the pathogenesis of duodenal adenocarcinomas, but they do not appear to be important in the development of jejunal or ileal adenocarcinomas or of carcinoid tumors of the small intestine.

Adenocarcinoma↗
PubMed1997

Mutants of the phytopathogenic fungus magnaporthe grisea deficient in alternative, cyanide-resistant, respiration

The phytopathogenic fungus Magnaporthe grisea has a cyanide-resistant respiratory pathway. The fungicide SSF-126 ((E)-2-methoxyimino-N-methyl-2-(2-phenoxyphenyl) acetamide) blocks the cytochrome electron transport of M. grisea and induces the alternative respiratory pathway. Twelve mutants of M. grisea more susceptible to SSF-126 than wild type were identified after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. Five mutants retained a reduced alternative respiration activity, and seven mutants lacked alternative pathway activity. A monoclonal antibody against the maize alternative oxidase cross-reacted against a 40-kDa mitochondrial protein of M. grisea, indicating that the 40-kDa protein is an alternative oxidase. Immunoblot analysis indicated that the seven completely deficient mutants grouped into two classes: four mutants produced the 40-kDa proteins while the other three mutants failed to produce the functional protein. Copyright 1997 Academic Press. Copyright 1997 Academic Press

Journal Article↗
PubMed1997

Primary leptomeningeal meningiomatosis with widespread whorl formation.

We report a 10-year-old girl with a primary leptomeningeal tumor. She presented with a 5-week history of increased intracranial pressure, progressive cranial nerve deficits, and spinal compression signs. She had previously had a granulosa cell tumor, a benign estrogen-producing ovarian tumor, which was resected 6 months before the initial neurological symptoms developed. At autopsy, the brain and spinal cord showed diffuse neoplastic involvement of the leptomeninges. The tumor was composed of small cells with a high nucleus/cytoplasm ratio, which were immunoreactive for vimentin but not for epithelial membrane antigen or cytokeratin. In addition, the tumor contained many small cellular whorls with desmosome-like junctional complexes between the cells, suggesting that the tumor was a meningioma, basically of the meningothelial type. The term "meningeal meningiomatosis" has been used synonymously with "primary meningeal sarcomatosis." The present tumor was considered to be a rare example of "meningeal meningiomatosis" of true meningothelial cell origin.

Arachnoid↗
PubMed1997

cDNA cloning and mRNA expression analysis of the human neuronatin. High level expression in human pituitary gland and pituitary adenomas.

The authors cloned the nearly complete cDNA of human neuronatin with the aid of an expressed sequence tag (EST) database, and analyzed its expression in various human tissues by Northern blot analysis. The nucleotide and deduced amino acid sequences of the human neuronatin showed a high similarity to those of rodents. The Northern blot analysis revealed that the human neuronatin message was expressed predominantly in the fetal brain in the brain-specific manner, but only faintly in the adult brain. Among the various adult human tissues examined, the anterior pituitary gland was shown to be the only place where the neuronatin mRNA was strongly expressed. Intense neuronatin expression was also observed in several human pituitary adenomas, including ACTH-producing, GH-producing, and nonfunctioning adenomas, but hardly detected in other brain tumors.

Adenoma↗
PubMed1997

Solitary plasmacytomas of the occipital bone: a report of two cases.

The radiological appearances of two cases of solitary plasmacytoma in the occipital bone are described. One arose in the lateral part and the other in the squama. They showed characteristic radiological features on CT, MRI and angiography. Bone scintigraphy and gallium scintigraphy were also available. Solitary plasmacytoma of the skull is a rare condition and usually occurs in the calvarium. The skull base is an extremely rare site and only four cases have been reported. The literature of solitary plasmacytoma of the skull is reviewed.

Aged↗
PubMed1997

An unusual meningioma variant with glial fibrillary acidic protein expression.

We studied a recurrent meningioma located in the right frontal lobe. The tumor showed high cellularity and the cells had plump, hyalinous cytoplasm. Immunohistochemically, almost all the tumor cells were positive for epithelial membrane antigen and vimentin, and unexpectedly, glial fibrillary acidic protein (GFAP). Ultrastructural investigation revealed abundant 8- to 10-nm filaments in the cytoplasm. Conspicuous interdigitations with numerous desmosomes were present. Frequently, intracellular and intercellular lumina lined by microvilli were also found. We considered the present case to be an unusual variant of meningioma with GFAP expression. A few cases of meningioma with triple expression of GFAP, vimentin and cytokeratin have been reported previously. However, the present case showed obvious pathological differences from these, and had no immunoreactivity for cytokeratin.

Frontal Lobe↗
PubMed1997

Anastomosis of the superficial temporal artery to the middle cerebral artery with the interposed occipital artery graft in moyamoya disease: case report.

BACKGROUND: Although there have been various interposed bypass grafts used for cerebral revascularization, the occipital artery has never been used as a graft. Interposed occipital artery bypass graft in an adult case with moyamoya disease after failed indirect revascularization is presented. CASE DESCRIPTION: This 34-year-old woman with moyamoya disease, who had suffered from cerebral ischemic symptoms since the age of 6 years, was admitted to our hospital because of an intracerebral hemorrhage on the left side. She had undergone superficial temporal-to-middle cerebral artery anastomosis, encephalo-galeo-synangiosis on the right side, and encephalo-duro-arterio-synangiosis on the left side at age 29 years. Four months after the intracerebral hemorrhage, she still had cerebral ischemic symptoms in the left hemisphere where cerebral revascularization was poor. Since neither the superficial temporal nor occipital artery could be used for direct anastomosis because of spontaneous transdural anastomoses of the superficial temporal artery and the short length of the occipital artery, anastomosis between the left superficial temporal artery and left posterior parietal artery was performed using a left occipital artery graft 6 months after the hemorrhage. Postoperative external carotid angiograms showed good patency of the graft. CONCLUSION: In cases in which direct anastomosis is infeasible for cerebral revascularization, the occipital artery could successfully be used as a bypass graft.

Adult↗
PubMed1997

Intra-aneurysmal pressure changes during angiography in coil embolization.

BACKGROUND: Although elevation of blood pressure in aneurysms induced by injection of contrast medium has been postulated as a major cause of rerupture of ruptured cerebral aneurysms during angiography, no study has proved the elevation of intra-aneurysmal pressure because of difficulty in measuring the intra-aneurysmal pressure during angiography. The present study demonstrated intra-aneurysmal pressure to be raised by injection of contrast medium, using a microcatheter introduced into aneurysms. METHODS: To confirm the accuracy of pressure measurement through a microcatheter, we measured intra-aneurysmal pressure in a plastic model of an artery and an aneurysm during and after injection of contrast medium through a microcatheter and a needle inserted into the aneurysm. In a clinical study, intra-aneurysmal pressures were measured through the microcatheter in nine cerebral aneurysms of seven patients. RESULTS: In the model experiment, changes in the pressure measured through the microcatheter correlated well with those observed through the needle. In the clinical study, intra-aneurysmal systolic pressures increased by 5-23 mm Hg immediately after injection of contrast medium for 1-3 s in four basilar tip, three internal carotid-ophthalmic, and one middle cerebral artery aneurysm, whereas no pressure change was observed in a posterior cerebral artery aneurysm. Systemic blood pressure during angiography remained unchanged in all cases. CONCLUSIONS: This abruptly elevated intra-aneurysmal pressure by injection of contrast medium might cause rerupture of an aneurysm soon after rupture of the aneurysm, especially when the rupture site is fragile.

Adult↗
PubMed1997

Suppression by gangliosides of polymerization of glial cytoskeletons prepared from rat astrocytes: a role of sialic acid moiety.

This study investigated in vitro the effects of gangliosides on polymerization of either the depolymerized microfilament preparation (MF) or depolymerized glia filament preparation (GF) extracted separately from the crude cytoskeletal fraction of rat astrocytes. Gangliosides GM1, GM2 and GM3 markedly suppressed polymerization of both MF and GF. The concentration of GM1, GM2 or GM3 required to induce 50% inhibition of the polymerization of 7.5 micrograms MF protein/200 microliters (IC50 of GM1, GM2, or GM3) was 3.2, 2.8 or 5.6 micrograms/200 microliters, respectively. The IC50 of each ganglioside for the polymerization of 7.5 micrograms/200 microliters of GF, furthermore, was 3.3, 3.5 or 7.4 micrograms/200 microliters, respectively, suggesting that the inhibitory activities of GM1 and GM2 on polymerization of both MF and GF were greater than those of GM3. GM1, GM2 and GM3 also suppressed dose-dependently the polymerization of both actin and vimentin. The inhibitory activities of GM1 and GM2 on the polymerization of actin or vimentin were greater than GM3, as in the case of polymerization of MF or GF. The IC50S of GD1a and GT1b for MF polymerization at the same concentration were 2.2 and 1.2 micrograms/200 microliters, respectively, and those for GF polymerization were 2.7 and 1.7 micrograms/200 microliters, respectively. The IC50 of GD3 for MF polymerization was 3.9 micrograms/200 microliters, and that for GF polymerization 4.0 micrograms/200 microliters, implying that the inhibitory activities of GD3 on polymerization of both MF and GF were greater than those of GM3. The findings suggested that the inhibitory activities of gangliosides on MF or GF polymerization became greater with increasing number of sialic acid residues. AsialoGM1 suppressed neither MF nor GF polymerization, and inhibited dose-dependently the ability of GM1 to suppress MF polymerization.

Actin Cytoskeleton↗
PubMed1997

Structure-activity relationships of penem antibiotics: crystallographic structures and implications for their antimicrobial activities.

Twelve closely related crystal structures of the penem derivatives revealed a characteristic short contact of the oxygen atom in the C2 side-chains with the S1 atom. The side-chain conformations of the crystal structures showed a good correlation with the antimicrobial activity. In particular, the penems which show high antimicrobial activity have similar torsion angles for S1-C2-C1'-C2', suggesting that the disposition of the C2' atom would be important for binding to penicillin-interacting enzymes. Two conformations of the C6 hydroxyethyl group were observed in the crystal structures. Of those two, the conformation with a larger torsion angle (delta = 179.2 degrees) is deduced to be the enzyme-bound conformation in the Michaelis complex.

Anti-Bacterial Agents↗