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Biomedical subjects

A Miwa

Publications and source records attributed to A Miwa.

At least 37 records · Page 2Linked to original sources
PubMed2000

Akt/protein kinase B prevents injury-induced motoneuron death and accelerates axonal regeneration.

Motoneurons require neurotrophic factors for their survival and axonal projection during development, as well as nerve regeneration. By using the axotomy-induced neuronal death paradigm and adenovirus-mediated gene transfer, we attempted to gain insight into the functional significances of major growth factor receptor downstream cascades, Ras-extracellular signal-regulated kinase (Ras-ERK) pathway and phosphatidylinositol-3 kinase-Akt (PI3K-Akt) pathway. After neonatal hypoglossal nerve transection, the constitutively active Akt-overexpressing neurons could survive as well as those overexpressing Bcl-2, whereas the constitutively active ERK kinase (MEK)-overexpressing ones failed to survive. A dominant negative Akt experiment demonstrated that inhibition of Akt pathway hastened axotomy-induced neuronal death in the neonate. In addition, the dominant active Akt-overexpressing adult hypoglossal neurons showed accelerated axonal regeneration after axotomy. These results suggest that Akt plays dual roles in motoneuronal survival and nerve regeneration in vivo and that PI3K-Akt pathway is probably more vital in neuronal survival after injury than Ras-ERK pathway.

Animals↗
PubMed2000

Prediction of suitable amount of water addition for wet granulation.

The purpose of this study was to predict the amounts of water addition suitable for pharmaceutical formulations in wet granulation, using a high-speed mixer or a fluidized bed granulator, before granulation trials. In order to determine the suitable amount of water addition, each excipient was first subjected to kneading with water in a mortar and a refractive near-infrared moisture sensor (IR sensor) measured the amount of water at the powder surface. Further by analysis the plot (output value of the IR sensor vs. amount of added water) for each excipient, the amount of water addition for granulation was determined for it. As a second step, two model formulations were designed and suitable amounts of water for granulation were predicted by summation of the obtained excipient values. The predicted value was compared with the experimental value for high-speed mixer granulation. The predicted and experimental amounts of water addition corresponded for the two model formulations, suggesting that the above method is useful for estimating suitable amounts of addition of water for formulations before granulation trials.

Chemistry, Pharmaceutical↗
PubMed2000

High serum lactate dehydrogenase level predicts short survival after vincristine-doxorubicin-dexamethasone (VAD) salvage for refractory multiple myeloma.

We evaluated possible prognostic factors just before salvage therapy with vincristine, doxorubicin, and dexamethasone (VAD) for 36 patients with refractory multiple myeloma. The median duration from diagnosis to the first VAD salvage was 14 months (range 2-76 months). Among parameters that have been shown to be associated with poor survival, a high serum lactate dehydrogenase (LDH) level was the sole significant predictor of survival. The median survival of patients with high LDH levels was 4 months, whereas that of patients with low LDH levels was 20 months. A multivariate analysis identified high LDH and high age as independent prognostic factors. More aggressive therapies might be indicated for high-LDH patients with refractory myeloma.

Adult↗
PubMed2000

Structure and biological activities of eumenine mastoparan-AF (EMP-AF), a new mast cell degranulating peptide in the venom of the solitary wasp (Anterhynchium flavomarginatum micado).

A new mast cell degranulating peptide, eumenine mastoparan-AF (EMP-AF), was isolated from the venom of the solitary wasp Anterhynchium flavomarginatum micado, the most common eumenine wasp found in Japan. The structure was analyzed by FAB-MS/MS together with Edman degradation, which was corroborated by solid-phase synthesis. The sequence of EMP-AF, Ile-Asn-Leu-Leu-Lys-Ile-Ala-Lys-Gly-Ile-Ile-Lys-Ser-Leu-NH(2), was similar to that of mastoparan, a mast cell degranulating peptide from a hornet venom; tetradecapeptide with C-terminus amidated and rich in hydrophobic and basic amino acids. In fact, EMP-AF exhibited similar activity to mastoparan in stimulating degranulation from rat peritoneal mast cells and RBL-2H3 cells. It also showed significant hemolytic activity in human erythrocytes. Therefore, this is the first example that a mast cell degranulating peptide is found in the solitary wasp venom. Besides the degranulation and hemolytic activity, EMP-AF also affects on neuromuscular transmission in the lobster walking leg preparation. Three analogs EMP-AF-1 approximately 3 were snythesized and biologically tested together with EMP-AF, resulting in the importance of the C-terminal amide structure for biological activities.

Amino Acid Sequence↗
PubMed2000

Facilitation of neurotransmitter release at the spiny lobster neuromuscular junction.

Stimulation-induced facilitation of transmitter release was examined at spiny lobster (Palinurus japonicus) neuromuscular junctions by measuring excitatory junctional potentials (EJPs). We found three components of facilitation with the decay time constants about 16, 200 and 1000 ms, respectively. The decay time constants of the nerve terminal free Ca(2+) concentration after stimulation agreed well with the two slower time constants of facilitation. The relationship among the three components of facilitation and a yet slower component, S, was investigated on the basis of several models. The models that have a multiplicative relationship between any two components of facilitation, and the additive model between all components could not account for the results of experiments. Only the 'unified power model', which assumes that facilitation and S are described by the 3-4th power of the sum of underlying components, could account for both the growth process of EJPs during stimulation and the effects of Ca(2+)-chelators. Loading Ca(2+)-chelators, BAPTA and EGTA, into the presynaptic terminals resulted in reduction, but not elimination, of any component of the facilitation. These results suggest that in the spiny lobster neuromuscular junction, the 'unified power model' can describe the relationship between three components of facilitation and S, and that residual free Ca(2+) enhances all three components of facilitation, although it may not be essential for them.

Animals↗
PubMed2000

Myopericarditis caused by cyclophosphamide used to mobilize peripheral blood stem cells in a myeloma patient with renal failure.

Cyclophosphamide (CPA) is widely used for peripheral blood stem cell mobilization, and a dose adjustment of CPA in the presence of renal failure has not been suggested. However, we describe a myeloma patient with renal failure (serum creatinine 4.2 mg/dl, creatinine clearance 11.2 ml/min) receiving CPA 2 g/m2 for 2 days, who developed unexpectedly severe toxicity, including myopericarditis and prolonged myelosuppression. The serial serum concentrations of CPA metabolites were persistently much higher than those in a myeloma patient with normal renal function. We consider, therefore, that the dose of CPA should be reduced in the presence of severe renal failure when used as high-dose therapy or to mobilize peripheral blood stem cells.

Adult↗
PubMed2000

A new class of neurotoxin from wasp venom slows inactivation of sodium current.

The effects of alpha-pompilidotoxin (alpha-PMTX), a new neurotoxin isolated from the venom of a solitary wasp, were studied on the neuromuscular synapses in lobster walking leg and the rat trigeminal ganglion (TG) neurons. Paired intracellular recordings from the presynaptic axon terminals and the innervating lobster leg muscles revealed that alpha-PMTX induced long bursts of action potentials in the presynaptic axon, which resulted in facilitated excitatory and inhibitory synaptic transmission. The action of alpha-PMTX was distinct from that of other known facilitatory presynaptic toxins, including sea anemone toxins and alpha-scorpion toxins, which modify the fast inactivation of Na+ current. We further characterized the action of alpha-PMTX on Na+ channels by whole-cell recordings from rat trigeminal neurons. We found that alpha-PMTX slowed the Na+ channels inactivation process without changing the peak current-voltage relationship or the activation time course of tetrodotoxin (TTX)-sensitive Na+ currents, and that alpha-PMTX had voltage-dependent effects on the rate of recovery from Na+ current inactivation and deactivating tail currents. The results suggest that alpha-PMTX slows or blocks conformational changes required for fast inactivation of the Na+ channels on the extracellular surface. The simple structure of alpha-PMTX, consisting of 13 amino acids, would be advantageous for understanding the functional architecture of Na+ channel protein.

4-Aminopyridine↗
PubMed2000

Spontaneous remission in acute type adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is a neoplastic disorder of T lymphocytes associated with human T lymphotropic virus type I (HTLV-I). The prognosis of ATL is generally poor. We present here a 79-year-old woman with spontaneous remission of acute type ATL. Spontaneous remission was preceded by surgical biopsy and pneumonia and lasted for two years until she died with pancreas cancer. Monoclonal integration of HTLV-I provirus DNA became undetectable after remission.

Adult↗
PubMed2000

Prognostic significance of serum soluble interleukin-2 receptor level in non-Hodgkin's lymphoma: a single center study in Japan.

Interleukin 2 receptor is expressed not only on the surface of activated T or B lymphocytes, but also on certain lymphoid malignancies. The receptor is released from the cell membrane as soluble form (sIL-2R). Serum sIL-2R level is a sensitive and quantitative marker of circulating peripheral blood mononuclear cell activation or specific tumor cell growth including non-Hodgkin's lymphoma (NHL). However, the relevance of serum sIL-2R levels relating to clinical outcome in adult patients with NHL remains uncertain. Therefore, we investigated the serial serum sIL-2R levels in 28 untreated patients with NHL to evaluate its correlation with clinical characteristics. High serum sIL-2R level (>1000 U/ml) at diagnosis was associated with a high incidence of treatment failure (p=0.03) and poor overall survival (p=0.057). The serum sIL-2R levels decreased significantly after achieving complete remission (p=0.003). Further larger studies are required to evaluate whether serum sIL-2R level is an independent prognostic factor or not. However, adding this parameter to those already employed in the International Prognostic Index would perhaps provide a better prognostic index for adult patients with NHL.

Adult↗
PubMed2000

Treatment of deep vein thrombosis using temporary vena caval filters after allogeneic bone marrow transplantation.

Bone marrow transplant (BMT) recipients have risk factors for deep vein thrombosis (DVT) including venous stasis caused by immobilization in the sterile unit, vessel wall damage caused by preparative regimen or indwelling catheters, and hypercoagulability caused by decreased natural anticoagulants. We successfully treated a patient who developed massive DVT in the superior vena cava after BMT with anticoagulation and the use of temporary vena caval filters. Considering the delayed complications, permanent filter is not appropriate for BMT recipients, because the risk factors for DVT associated with BMT are transient. We considered that temporary vena caval filter is a safe and useful device to prevent pulmonary embolism after DVT in BMT recipients.

Anticoagulants↗
PubMed2000

Pyogenic granuloma of the tongue early after allogeneic bone marrow transplantation for multiple myeloma.

Oral complications occur frequently after bone marrow transplantation (BMT). Some of them are caused by regimen-related toxicity of the preparative regimen, and others by infections. In addition, oral tissues are targets of graft-versus-host disease (GVHD). Oral granulomatous lesions are not a common complication after BMT, and are especially rare on the tongue. Such rare lesions reported in the literature, developed late after BMT with oral chronic GVHD. We present here a patient who developed pyogenic granuloma of the tongue early after allogeneic BMT done for multiple myeloma. Regimen-related mucositis, oral acute GVHD, the administration of cyclosporine A, and the preexisting macroglossia might be responsible for the formation of granuloma.

Bone Marrow Transplantation↗
PubMed2000

[A case of primary macroglobulinemia with acute pulmonary edema].

A 54-year-old man with acute respiratory failure underwent emergency admission to our hospital. Acute pulmonary edema combined with severe pneumonia was strongly suspected, and treatment with diuretics, antibiotics, and corticosteroids was effective. The diagnosis, primary macroglobulinemia, was made from the following findings: a high level of the lgM 1 type monoclonal protein, and an elevated serum viscosity with characteristic "linked sausage effects" seen in the retinal veins. Lymphoplasmacytoid cells, plasma cells, and small lymphocytes were seen in the bone marrow and lymphoplasmacytoid cells were also seen in the smear of the patient's peripheral blood. The types of malignant cells found in his bone marrow were also seen in both infiltrative lesions in the lung parenchyma and the pleural effusion. We concluded that this was a case of primary macroglobulinemia with acute pulmonary edema, which was caused partly by the hyperviscosity syndrome. The antitumor effect of the corticosteroid might have some effect on the recovery from acute respiratory failure and primary macroglobulinemia. He was transferred to the Department of Hematology to receive suitable chemotherapy.

Acute Disease↗
PubMed1999

Alternative splicing of the C-terminal domain regulates cell surface expression of the NMDA receptor NR1 subunit.

Subcellular localization of the NMDA receptor NR1 splice forms was studied by expressing individual splice variants and their epitope-tagged derivatives in mouse fibroblasts and in hippocampal neurons. When NR1 splice variants were expressed in fibroblasts, the amount of NR1 molecules expressed on the cell surface varied among forms with different C-terminal cytoplasmic domains. The splice forms with the longest C-terminal cytoplasmic tail (NR1-1a and NR1-1b) showed the lowest amount of cell surface expression, and the splice forms with the shortest C-terminal cytoplasmic tail (NR1-4a and NR1-4b) showed the highest cell surface expression. Cell surface expression of NR1 was enhanced by the coexpression of the NR2 subunit. We measured the glutamate-induced increase of calcium concentration in fibroblasts expressing one of the NR1 splice forms and the NR2B subunit. The increase of calcium concentration after glutamate application had a positive correlation with the amount of NR1 splice forms expressed on the cell surface. When epitope-tagged NR1 splice variants were expressed in primary hippocampal neurons using recombinant adenoviruses, we also observed the differential expression on the cell surface between splice variants. These results suggest that the splicing of the C-terminal domain of the NR1 subunit regulates the cell surface expression of the functional NMDA receptors.

3T3 Cells↗
PubMed1999

Expression of recombinant NMDA receptors in hippocampal neurons by adenoviral-mediated gene transfer.

N-methyl-d-aspartate (NMDA) receptors have attracted a great deal of attention because they are intimately involved in brain development, synaptic plasticity and a variety of neurological disorders. The ability to artificially alter the properties of NMDA receptors in central nervous system (CNS) neurons would be useful for elucidating the physiological roles of these receptors. It would also raise the possibility of gene therapy of neurological diseases caused by malfunction of NMDA receptors. In this study, we constructed three recombinant adenoviruses encoding rat NMDA receptor subunit cDNAs, NMDAR1 (NR1), NMDAR2B (NR2B) and mutant NR1(N598R) in which the asparagine (N) site of the wild-type NR1 was replaced with arginine (R) by site-directed mutagenesis. PC12 cells co-infected with recombinant adenoviruses bearing NR1 and NR2B cDNAs expressed conventional NMDA receptors that were permeable to Ca2+ and sensitive to Mg2+, whereas those with viruses bearing NR1(N598R) and NR2B cDNAs expressed Ca2+-impermeable and Mg2+-insensitive receptors. When rat hippocampal neurons in culture were infected with NR1(N598R) and NR2B viruses, both Ca2+ permeability and Mg2+ sensitivity of NMDA receptors were markedly reduced in the infected neurons. Excitatory postsynaptic currents (EPSCs) mediated by NMDA receptors also became much less sensitive to Mg2+. Thus, the NR1(N598R)/NR2B receptors were more dominant than the native NMDA receptors in the infected neurons, and the former receptors introduced by the adenoviral vectors functioned as postsynaptic receptors. These results indicate that the functional properties of postsynaptic NMDA receptors can be manipulated by gene transfer technology using adenoviral vectors.

Adenoviridae↗
PubMed1999

Postsynaptic expression of Ca2+-permeable AMPA-type glutamate receptor channels by viral-mediated gene transfer.

The ability to artificially express a particular receptor protein in the postsynaptic sites of neurons in the central nervous system (CNS) would be useful for the study of synaptic function of cloned receptor genes as well as for gene therapy of neurological disorders caused by dysfunction of postsynaptic receptors. In this study, we aimed to express the cDNA of unedited GluR2 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptor that forms inwardly rectifying and Ca2+-permeable channel in CNS neurons by using adenoviral-mediated gene transfer. For this purpose, we have constructed a recombinant adenovirus bearing an expression-switching unit, where the unedited GluR2 cDNA can be activated by the Cre recombinase-mediated excisional deletion of a stuffer DNA interposed between the promotor and the coding region. When PC12 cells were infected with this recombinant adenovirus together with an adenovirus expressing Cre recombinase, the inwardly rectifying and Ca2+-permeable AMPA receptor channels were expressed in nearly 100% of infected cells. Two days after co-infection of cultured rat hippocampal neurons with these adenoviruses, fast excitatory neurotransmission in the glutamatergic synapse was mediated predominantly by the inwardly rectifying and Ca2+-permeable AMPA receptor channels. This indicates that the native AMPA receptors in the postsynaptic sites of the glutamatergic synapse are replaced rapidly with recombinant receptors newly produced by the viral-mediated gene transfer.

2-Amino-5-phosphonovalerate↗
PubMed1999

Intussusception of a mucocele of the appendix secondary to an obstruction by endometriosis: report of a case.

We treated a patient with a complete invagination of the cecum which contained a mucocele of the appendix secondary to an obstruction by endometriosis. Preoperatively, a barium enema showed a crab's claw-like area without filling in the oral side of the transverse colon. An emergency laparotomy was performed and revealed a mucocele of the appendix to have induced appendicecal invagination; however, no colonic invagination was observed. An appendicecal resection was thus done. Pathologically, the resected specimen was a mucosal hyperplasia with mucin-secreting lesions of the appendix. The theories regarding the pathogenesis of appendicecal mucocele are reviewed and discussed.

Adult↗