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Biomedical subjects

M Hanada

Publications and source records attributed to M Hanada.

At least 19 recordsLinked to original sources
PubMed1995

Structure-function analysis of Bcl-2 protein. Identification of conserved domains important for homodimerization with Bcl-2 and heterodimerization with Bax.

The Bcl-2 protein is a suppressor of programmed cell death that homodimerizes with itself and forms heterodimers with a homologous protein Bax, a promoter of cell death. Expression of Bax in Saccharomyces cerevisiae as a membrane-bound fusion protein results in a lethal phenotype that is suppressible by co-expression of Bcl-2. Functional analysis of deletion mutants of human Bcl-2 in yeast demonstrated the presence of at least three conserved domains that are required to suppress Bax-mediated cytotoxicity, termed domains A (amino acids 11-33), B (amino acids 138-154), and C (amino acids 188-196). In vitro binding experiments using GST-Bcl-2 fusion proteins demonstrated that Bcl-2(delta B) and Bcl-2(delta C) deletion mutants had a markedly impaired ability to heterodimerize with Bax but retained the ability to homodimerize with wild-type Bcl-2. In contrast, Bcl-2(delta A) and an NH2-terminal deletion mutant Bcl-2(delta 1-82) retained Bax binding activity in vitro but failed to suppress Bax-mediated cytotoxicity in yeast. Sequences downstream of domain C in the region 197-218 also were shown to be required for Bax-binding in vitro and anti-death function in yeast. Analysis of Bcl-2/Bcl-2 homodimerization using both in vitro binding assays as well as a yeast two-hybrid method provided evidence in support of a head-to-tail model for Bcl-2/Bcl-2 homodimerization and revealed that sequences within the NH2-terminal A domain interact with a structure that requires the presence of both the carboxyl B and C domains in combination. In addition to further delineating structural features within Bcl-2 that are required for homo-dimerization, the findings reported here support the hypothesis that Bcl-2 promotes cell survival by binding directly to Bax but suggest that ability to bind Bax can be insufficient for anti-cell death function.

Amino Acid Sequence↗
PubMed1995

Vitamin K prodrugs: 1. Synthesis of amino acid esters of menahydroquinone-4 and enzymatic reconversion to an active form.

The efficacy and toxicity of vitamin K depends on the pathway and the extent of enzymatic reductive activation to vitamin K hydroquinone, which is an essential cofactor for the synthesis of clotting factors. Parenteral use of vitamin K is impaired by its water insolubility. With the aim to improve delivery problems associated with menahydroquinone-4 (MKH, 2), an active form of menaquinone-4, N,N-dimethylglycine esters of 2 (1-mono, 4-mono, and 1,4-bis) were synthesized and assessed as potential water-soluble prodrugs for parenteral use. The esters can deliver the hydroquinone to its active site without a quinone reductive activation step. The hydrochloride salts of the esters were found to be quite soluble in water. The hydrolysis of the esters in 20% rat liver homogenate 9000 x g supernatant, rat plasma and phosphate buffer, pH 7.4, at 37 degrees C was kinetically studied in the presence and absence of an esterase inhibitor. The hydrolysis was catalyzed by esterases located in the rat liver and rat plasma and quantitatively yielded 2. These results suggest that esterification of 2 with N,N-dimethylglycine is a promising way for obtaining water-soluble prodrug forms of 2. Based on the high susceptibility to liver esterase, the esters are potential prodrugs for achieving the site-specific delivery of 2.

Animals↗
PubMed1995

Synchronous fluctuation of interleukin-6 and platelet count in cyclic thrombocytopenia and thrombocytosis.

We describe a case of cyclic thrombocytopenia and thrombocytosis, whose cytokine levels, granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-6 (IL-6) in plasma, fluctuated in synchrony with platelet count. The levels of the two cytokines correlated significantly with the platelet count for 11 observations over an 8-month period (r = 0.79, p < 0.01 for GM-CSF and r = 0.87, p < 0.001 for IL-6). No inverse relationship between platelet-associated immunoglobulin G (PAIgG) and platelet count was observed (r = 0.39, p > 0.20). These findings suggest that the fluctuation of platelet count in this case may result from an aberration of the cytokine network regulating megakaryopoiesis and platelet formation.

Adult↗
PubMed1995

[A case of pituitary abscess caused by infection of Rathke's cleft cyst].

Pituitary abscess is relatively rare. Only about 80 cases have been reported. Preexisting lesions in pituitary fossa, such as pituitary adenoma, craniopharyngioma and Rathke's cleft cyst, are inclined to be complicated by infection more than the normal pituitary glands are. We reported a case of pituitary abscess caused by infection of Rathke's cleft cyst. A 67-year-old male had general fatigue and loss of appetite 4 months before admission. On admission he was found to have diabetes mellitus, diabetes insipidus, and hypernatremia. These defects were controlled by medication but he gradually became comatose and febrile. CT and MRI revealed an intrasellar lesion with ring enhancement. Lumbar puncture demonstrated an increase of mononuclear cells and protein. Blood chemistry revealed a marked increase of CRP. He was operated on via the transsphenoidal approach, which revealed sphenoid sinusitis and abscess formation in the pituitary gland. Histological examination of the surgical specimen revealed infection of Rathke's cleft cyst but the fluid in the cyst was sterile. By the drainage of the cyst and the use of antibiotics the patient became alert and signs of infection disappeared. He was discharged with a slight hypopituitarism and returned to normal life. Mortality rate of pituitary abscess is decreasing but is still high because of hypopituitarism and severe infection. Accurate diagnosis and operation are necessary. Transsphenoidal surgery is preferable for postoperative drainage of the abscess.

Abscess↗
PubMed1995

[A case of intracranial malignant meningioma with extraneural metastases].

A case of intracranial malignant meningioma with remote metastases to the bones is reported. A 66-year-old man with regrowth of right sphenoid ridge meningioma, whose meningioma had partially been removed 15 years before, was admitted to our clinic. The tumor was large enough to protrude into the lateral and third ventricles, and involved the right internal carotid, middle cerebral, anterior cerebral artery and optic nerve. The tumor had irregular contour, and was heterogeneously enhanced by Gd-DTPA on MRI. An operation was performed, but a part of the tumor around these main arteries could not be removed. Histopathological examination revealed anaplastic meningioma, resulting from malignant change. Radiotherapy was performed postoperatively and the patient was discharged. Seven months after the operation he complained of posterior nuchal, back, and lumbar pain. Radiological examination revealed multiple punched-out lesions in the ribs and vertebrae, which were histologically demonstrated to be metastases of intracranial anaplastic meningioma. Radiotherapy was carried out for the cervical vertebrae, but his symptoms persisted. He died of pneumonia 10 months after the operation.

Aged↗
PubMed1995

[TSH-secreting fibrous pituitary adenoma showing calcification: a case report].

TSH-secreting pituitary adenoma with calcification and proliferation of the collagen fibers was presented. A 42-year-old man had shown general fatigue and thyroid hypertrophy caused by hyperthyroidism for 3 years. CT and MRI revealed pituitary adenoma with calcification extending into the cavernous sinus and sphenoid sinus. The patient was operated on using the transsphenoidal route twice, but the tumor was not able to be removed totally, partly due to the hardness of the tumor. The tumor in- and around the left cavernous sinus as well as the hardest part of the tumor itself due to the calcification could not be removed. Histopathological examination revealed chromophobe adenoma with proliferation of the collagen fibers. Immunohistological and electronmicroscopic examination demonstrated TSH-secreting adenoma. Postoperatively, thyroid function improved and the patient's symptoms due to hyperthyroidism disappeared.

Adenoma, Chromophobe↗
PubMed1995

Immunohistochemical analysis of the Bcl-2 oncoprotein in human neuroblastomas. Comparisons with tumor cell differentiation and N-Myc protein.

BACKGROUND: The bcl-2 gene encodes a 26-kilodalton integral membrane oncoprotein that is noteworthy for its function as a blocker of programmed cell death, and ability to render cells resistant to killing by chemotherapeutic drugs and x-irradiation. EXPERIMENTAL DESIGN: To determine the in vivo patterns of bcl-2 expression in neuroblastomas (NBs), tumor specimens derived from 17 children with NB or ganglioneuromas were immunohistochemically evaluated using formalin-fixed, paraffin-embedded material and antibodies specific for the Bcl-2 and N-Myc proteins, or various markers typically used to assess the differentiation status of these tumors, including neuron-specific enolase, S-100 protein, beta 2-microglobulin (beta 2M) and the intermediate filament proteins, vimentin, and neurofilament light- and medium-chains. RESULTS: Using two-color immunohistochemical methods, Bcl-2 protein was found exclusively in tumor cells that did not contain N-Myc, an oncoprotein previously associated with poor prognosis in NB. Levels of Bcl-2 immunostaining were heterogeneous in the undifferentiated small, round cells typically seen in tumors with aggressive histology, and ranged from essentially undetectable, to strong in intensity. Somewhat higher levels of Bcl-2 immunostaining were found in the slightly larger, more differentiated neuroblastic cells that had more generous cytoplasm in these neoplasms. In contrast to the heterogeneous levels of Bcl-2 seen in undifferentiated NBs, Bcl-2 immunoreactivity was uniformly present at high levels in tumor cells that were more differentiated and judged to be similar to immature ganglion cells at an intermediate stage of neuronal differentiation, based on morphologic characteristics and immunophenotyping with antibodies specific for various differentiation markers. The still more differentiated ganglionic cells seen in ganglioneuroblastomas and ganglioneuromas exhibited much less intense immunoreactivity with anti-Bcl-2 antibodies, suggesting down-regulation of bcl-2 during final terminal differentiation. In contrast to cells with neuronal features, the stromal Schwann cells were uniformly negative for Bcl-2 protein in all histologic grades of tumors. Thus, bcl-2 expression in NBs was limited to cells of the neuronal lineage and tended to be highest in tumor cells with the characteristics of ganglionic cell precursors. The expression of bcl-2 in the normal fetal and postnatal adrenal medulla and sympathetic ganglia paralleled that seen in NBs, consistent with previous suggestions that NB reflects a block in the normal differentiation process. CONCLUSIONS: Taken together, these findings indicate that the levels of the Bcl-2 protein are developmentally regulated in normal and neoplastic cells of the sympathetic branch of the autonomic nervous system, and suggest that this oncoprotein may be useful as a differentiation marker for subclassification of NBs for prognostic purposes and for investigations of normal neuronal maturation. Furthermore, strong Bcl-2 immunoreactivity was detected in islets of residual tumor cells in 6 of 7 specimens obtained from 5 patients after therapy, suggesting that this oncoprotein may be cytoprotective for NB cells in vivo.

Adolescent↗
PubMed1994

Interactions among members of the Bcl-2 protein family analyzed with a yeast two-hybrid system.

Interactions of the Bcl-2 protein with itself and other members of the Bcl-2 family, including Bcl-X-L, Bcl-X-S, Mcl-1, and Bax, were explored with a yeast two-hybrid system. Fusion proteins were created by linking Bcl-2 family proteins to a LexA DNA-binding domain or a B42 trans-activation domain. Protein-protein interactions were examined by expression of these fusion proteins in Saccharomyces cerevisiae having a lacZ (beta-galactosidase) gene under control of a LexA-dependent operator. This approach gave evidence for Bcl-2 protein homodimerization. Bcl-2 also interacted with Bcl-X-L and Mcl-1 and with the dominant inhibitors Bax and Bcl-X-S. Bcl-X-L displayed the same pattern of combinatorial interactions with Bcl-2 family proteins as Bcl-2. Use of deletion mutants of Bcl-2 suggested that Bcl-2 homodimerization involves interactions between two distinct regions within the Bcl-2 protein, since a LexA protein containing Bcl-2 amino acids 83-218 mediated functional interactions with a B42 fusion protein containing Bcl-2 amino acids 1-81 but did not complement a B42 fusion protein containing Bcl-2 amino acids 83-218. In contrast to LexA/Bcl-2 fusion proteins, expression of a LexA/Bax protein was lethal to yeast. This cytotoxicity could be abrogated by B42 fusion proteins containing Bcl-2, Bcl-X-L, or Mcl-1 but not those containing Bcl-X-S (an alternatively spliced form of Bcl-X that lacks a well-conserved 63-amino acid region). The findings suggest a model whereby Bax and Bcl-X-S differentially regulate Bcl-2 function, and indicate that requirements for Bcl-2/Bax heterodimerization may be different from those for Bcl-2/Bcl-2 homodimerization.

Bacterial Proteins↗
PubMed1994

Reconstitution of an efficient protein translocation machinery comprising SecA and the three membrane proteins, SecY, SecE, and SecG (p12).

A cytoplasmic membrane protein, p12, of Escherichia coli was discovered as a new factor that stimulates the protein translocation activity reconstituted with SecA, SecY, and SecE (Nishiyama, K., Mizushima, S., and Tokuda, H. (1993) EMBO J. 12, 3409-3415). Direct involvement of p12 in protein translocation was subsequently demonstrated in vivo by genetic studies, and the name SecG has been proposed for p12 (Nishiyama, K., Hanada, M., and Tokuda, H. (1994) EMBO J. 13, 3272-3277). To elucidate the role of SecG in protein translocation and to characterize the translocation apparatus comprising these four Sec proteins, the activity of reconstituted proteoliposomes was examined in detail as a function of the amount of each component. SecG markedly stimulated the translocation activity over wide ranges of amounts of the other three Sec proteins, indicating that none of the other three Sec proteins substitutes for the SecG function. Detailed kinetic analyses indicated that the activity of proteoliposomes was dependent on the amount of the SecY-SecE complex when SecG was absent and the amount of the SecY.SecE.SecG complex when the proteoliposomes contained SecG. The translocation activity of the latter complex was significantly higher than that of the former one. Binding of SecA to liposomes appreciably increased when they contained both SecY and SecE, whereas the further presence of SecG did not enhance the binding. On the other hand, the ATPase activity of SecA, which was dependent on proOmpA and SecY.SecE-containing proteoliposomes, was significantly enhanced when the proteoliposomes contained SecG. Taken together, these results indicate that SecG enhances the translocation activity of the apparatus after the step of SecA targeting to SecY.SecE.

Adenosine Triphosphatases↗
PubMed1994

Disruption of the gene encoding p12 (SecG) reveals the direct involvement and important function of SecG in the protein translocation of Escherichia coli at low temperature.

The Escherichia coli cytoplasmic membrane protein, p12, stimulates the protein translocation activity reconstituted with SecY, SecE and SecA. The gene encoding p12, which is located at 69 min on the E. coli chromosome, was deleted to examine the role of p12 in protein translocation in vivo. The deletion strain exhibited cold-sensitive growth. Pulse-chase experiments revealed that precursors of outer membrane protein A, maltose binding protein and beta-lactamase accumulated at 20 degrees C but not at 37 degrees C. The deletion strain harboring a plasmid which carries the gene encoding p12 under the control of the araBAD promoter was able to grow in the cold when p12 was expressed with the addition of arabinose. Furthermore, the accumulated precursors were rapidly processed to the mature forms upon the expression of p12. Immunoblot analysis revealed the steady-state accumulation of precursor proteins at 20 degrees C, whereas the accumulation was only marginal at 37 degrees C, indicating that the function of p12 is more critical at 20 degrees C than at 37 degrees C. Finally, proteoliposomes were reconstituted with or without p12 to demonstrate that the stimulation of the activity by p12 increases with a decrease in temperature. From these results, we concluded that p12 is directly involved in protein translocation in E. coli and plays a critical role in the cold. We propose the more systematic name, SecG, for p12.

ATP-Binding Cassette Transporters↗
PubMed1994

Identification of a p53-dependent negative response element in the bcl-2 gene.

Recently, we have shown that the p53 tumor suppressor gene product can inhibit expression of the bcl-2 gene. In this report, we explored the molecular basis for p53-mediated down-regulation of bcl-2 gene expression using a cotransfection approach involving p53 expression plasmids and chloramphenicol acetyltransferase (CAT) reporter gene constructs containing regions from the bcl-2 gene. When transfected into a p53-deficient human lung cancer cell line H358, reporter gene constructs containing only the promoter region of bcl-2 and upstream sequences were not suppressed by p53. Inclusion of bcl-2 gene sequences corresponding to the 5' untranslated region in bcl-2/CAT constructs, however, resulted in p53-dependent down-regulation. A 195-base pair segment from the bcl-2 gene 5' untranslated region was found to be capable of conferring p53-dependent repression on a heterologous expression plasmid containing CAT under the control of an SV40 immediate early-region promoter. This p53-negative response element functioned in an orientation-independent manner when placed either upstream or downstream of the SV40-CAT transcription unit. The results demonstrate the existence of a negative response element in the bcl-2 gene through which p53 may either directly or indirectly transcriptionally down-regulate expression of this gene involved in the regulation of programmed cell death.

Base Sequence↗
PubMed1994

[Results of surgical treatment of aortic dissections].

From January 1989 to September 1993, 59 consecutive patients (35 males and 24 females, mean age 59.6 years old) underwent surgical repair of aortic dissection on the cardiovascular surgical unit at Takeda Hospital. The type of aortic dissection were classified according to Stanford University criteria. Twenty-two patients had acute type A (Ac-A), 10 had chronic type A (Ch-A), 4 had acute type B (Ac-B), and 23 had chronic type B (Ch-B) dissection. Seventeen dissections (29%) in the entire group of 59 cases had ruptured (including cardiac tamponade, pleural effusion and hemoptysis etc.). Ischemia of lower extremity occurred in 7 patients and ischemia of visceral organs in 3 patients. Type A dissection were approached via a median sternotomy and cardiopulmonary bypass with systemic hypothermia. Type B dissections were approached through a left postrolateral thoracotomy. Left heart bypass (left atrial-femoral in 8 cases) and partial cardiopulmonary bypass (femoral-femoral in 12 cases) generally were utilized. Resection of intimal tear and replacement of aorta with vascular grafts (including aortic arch in 19 cases) were performed in most patients and primary closure of the intimal tear was performed in 9 cases using GRF. The over-all operative mortality rate was 36% (8/22) for Ac-A, 20% (2/10) for Ch-A, 25% (1/4) for Ac-B, 22% (5/23) for Ch-B. Main causes of operative death was perioperative brain damage. It is necessary to improve the operative mortality for Ac-A dissections (especially in replacement of aortic arch and arch vessels). Further researches are needed regarding optimal methods of the cerebral protection during reconstruction of aortic arch.

Adult↗
PubMed1993

bcl-2 gene hypomethylation and high-level expression in B-cell chronic lymphocytic leukemia.

The bcl-2 gene becomes transcriptionally deregulated in the majority of low-grade non-Hodgkin lymphomas as a result of t(14;18) translocations that place the bcl-2 gene at 18q21 into juxtaposition with the Ig heavy-chain locus at 14q32. This chromosomal translocation or similar bcl-2 gene rearrangements involving the Ig light-chain genes have been reported to occur in some cases of B-cell chronic lymphocytic leukemia (B-CLL). We analyzed the structure, methylation, and expression of the bcl-2 gene in 20 cases of B-CLL or closely related variants of this lymphoproliferative disorder, including at least 16 typical examples of CD5+ B-CLL. None of the 20 specimens had evidence of bcl-2 gene rearrangements, based on Southern blot analysis using three different bcl-2 probes. However, immunoblot analysis using antibodies specific for the Bcl-2 protein showed that 14 of 20 cases (70%) contained levels of p26-Bcl-2 that were equal to or greater than those found in a t(14;18)-bearing lymphoma cell line. Furthermore, in 19 of 20 cases (95%), the Bcl-2 protein was present at levels that were 1.7- to 25-fold higher than in normal peripheral blood lymphocytes. These differences in the relative levels of Bcl-2 protein among cases of B-CLL appeared to be functionally significant, in that a preliminary analysis of 3 representative cases showed that CLL cells with higher levels of Bcl-2 protein survived longer in culture and were delayed in their onset of DNA degradation relative to CLL cells with lower Bcl-2 protein levels. Evaluation of the methylation status of the bcl-2 gene using the isoschizomers Msp I and Hpa II, and a probe corresponding to the first major exon of the gene showed complete demethylation of both copies of the bcl-2 gene in a region corresponding to a 2.4-kb Msp I fragment in all 20 cases of B-CLL. In contrast, analysis of 6 of 6 B-cell lines that harbor a t(14;18) was consistent with hypomethylation of only one of the two bcl-2 alleles. Neither copy of the bcl-2 gene was demethylated in this region in 5 of 5 lymphoid cell lines that lack this translocation. However, hypomethylation of the bcl-2 gene did not necessarily correlate with the relative levels of Bcl-2 protein present in the B-CLL cells, suggesting that additional mechanisms for regulating bcl-2 expression are involved.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomarkers, Tumor↗
PubMed1993

[Immunoblastic lymphadenopathy (IBL)-like T cell lymphoma associated with granulocytopenia and autoimmune hemolytic anemia].

A 65 year-old woman was admitted in May 1990, because of fever, generalized lymphadenopathy and eruption. Laboratory examination showed granulocytopenia, polyclonal hypergammaglobulinemia, positive Coombs' test, positive cold antibody and positive anti-E erythrocyte antibody. 7 days after admission autoimmune hemolytic anemia developed. The appearance of the anti neutrophil leukocyte antibody was suspected because of the absence of the segmented neutrophils in marrow specimen. Histological findings of the biopsied lymph node and the marker study of the tumor cell disclosed IBL-like T cell lymphoma. The patient was treated with G-CSF and VEPA chemotherapy. Granulocytes increased and she showed marked symptomatic improvement with complete remission. Our case showed various clinical pictures with hemolytic anemia and granulocytopenia, which could be based on the autoimmune mechanisms.

Aged↗
PubMed1992

Cellular immunosuppression in children with acute lymphoblastic leukemia: effect of consolidation chemotherapy.

The present study was designed to evaluate the chemotherapy-induced cellular immunosuppression in 20 children with acute lymphoblastic leukemia (ALL) in remission and receiving maintenance chemotherapy. Peripheral blood was serially obtained from leukemic children during vincristine/cyclophosphamide/6-mercaptopurine/prednisone combined consolidation chemotherapy. The mean absolute number of peripheral blood lymphocytes as well as the mean absolute numbers of lymphocyte subsets (T cells, T cell subsets, B cells, and natural killer cells) from leukemic children before consolidation chemotherapy were all significantly lower than in control subjects; however, the percentages of lymphocyte subsets were similar in both groups. After consolidation chemotherapy, the percentages of CD4+ T lymphocytes and natural killer (NK) cells were significantly decreased and the percentages of monocytes and CD8+ T lymphocytes were significantly increased. Phytohemagglutinin- and 12-O-tetradecanoylphorbol-13-acetate-induced production of interleukin-2 (IL-2) and NK-cell-mediated cytotoxic activity by peripheral blood mononuclear cells (PBMC) were also substantially decreased in the post-therapy groups. NK activity correlated with the percentage of NK cells in PBMC. In contrast, OK432-induced production of tumor necrosis factor alpha (TNF alpha) and killer activity against NK-resistant target cells were significantly increased after therapy as compared with the pre-therapy and control groups. TNF alpha production correlated with the percentage of monocytes in PBMC. These results demonstrate that substantial quantitative and qualitative chemotherapy-induced abnormalities of the cellular immune system are present in the majority of patients treated with ALL. It is also suggested that the increased TNF alpha production by monocytes and the appearance of potent killing activity against NK-resistant targets might compensate for the defects of IL-2 production and NK activity during intensive consolidation chemotherapy.

Animals↗
PubMed1992

Epoxomicin, a new antitumor agent of microbial origin.

An actinomycete strain No. Q996-17 produced a novel compound, epoxomicin, which exhibited in vivo antitumor activity against B16 melanoma. Structural studies indicated that it is a new member of the epoxy-beta-aminoketone group, and is closely related to eponemycin.

Actinomycetales↗