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Biomedical subjects

A Miwa

Publications and source records attributed to A Miwa.

At least 55 records · Page 3Linked to original sources
PubMed1999

Cooperative Ca2+ removal from presynaptic terminals of the spiny lobster neuromuscular junction.

Stimulation-induced changes in presynaptic free calcium concentration ([Ca2+]i) were examined by fluorescent imaging at the spiny lobster excitor motor nerve terminals. The Ca2+ removal process in the terminal was analyzed based on a single compartment model, under the assumption that the Ca2+ removal rate from the terminal cytoplasm is proportional to nth power of [Ca2+]i. During 100 nerve stimuli at 10-100 Hz, [Ca2+]i reached a plateau that increased in a less-than-linear way with stimulation frequency, and the power index, n, was about 2. In the decay time course after stimulation, n changed with the number of stimuli from about 1.4 after 10 stimuli to about 2 after 100 stimuli. With the change of n from 1.4 to 2, the rate became larger at high [Ca2+]i (>1.5 microM), but was smaller at low [Ca2+]i (<1 microM). These results suggest that a cooperative Ca2+ removal mechanism of n = 2, such as mitochondria, may play an important role in the terminal. This view is supported by the gradual increase in the [Ca2+]i plateau during long-term stimulation at 20-50 Hz for 60 s and by the existence of a very slow [Ca2+]i recovery process after this stimulation, both of which may be due to accumulation of Ca2+ in the organelle.

Animals↗
PubMed1999

Continual remodeling of postsynaptic density and its regulation by synaptic activity.

A postsynaptic density (PSD) protein, PSD-95, was tagged with green fluorescent protein (GFP-PSD-95) and expressed in cultured hippocampal neurons using recombinant adenoviruses. GFP-PSD-95 was selectively localized to excitatory postsynaptic sites. Time-lapse fluorescence imaging of hippocampal neurons revealed that >20% of GFP-PSD-95 clusters turned over within 24 hours. The appearance rate of clusters was higher than the disappearance rate, and this difference accounted for the gradual increase of the cluster density observed in culture. Dynamics of PSD-95 clusters were also inhibited by blockers of excitatory synaptic transmission. Continual PSD turnover and its regulation by synaptic activity may be important in activity-dependent remodeling of neuronal connections.

2-Amino-5-phosphonovalerate↗
PubMed1999

Smooth muscle tumors of the esophagus: clinicopathological findings in six patients.

Preoperatively, it is difficult to discriminate leiomyoma and leiomyosarcoma of the esophagus, which are rare smooth muscle tumors. The objective of this study was to evaluate the clinicopathological findings of this unusual lesion. A search of the surgery archives of the Toyama Prefectural Central Hospital of Pathology revealed six cases of esophageal smooth muscle tumors. Clinicopathological findings were reviewed retrospectively. Only three patients (50%) presented with dysphagia, and the remaining three patients were asymptomatic. These patients underwent surgical excision. Histologically four of the six tumors were leiomyomas, and the other two tumors were leiomyosarcomas. Two tumors were in the upper to middle esophagus, and the remaining four were in the distal esophagus. On endoscopic examination, all tumors were noted to be polypoid. The two leiomyosarcomas measured over 5 cm and the four leiomyomas less than 4 cm. Neither ulceration nor necrosis proved to be of use in discriminating leiomyoma and leiomyosarcoma. The two patients with leiomyosarcoma died of liver metastasis 10 and 22 months after the treatment. Patients with leiomyosarcoma presented with distant metastasis and/or recurrence, with hematogeneous metastasis being the predominant type of recurrence.

Adult↗
PubMed1999

Number of lymph node metastases influences survival in patients with thoracic esophageal carcinoma: therapeutic value of radiation treatment for recurrence.

We retrospectively investigated whether the number of involved lymph nodes and the radiation therapy for recurrence affect survival in patients with thoracic esophageal carcinoma. Eighty-nine patients underwent surgical resection and reconstruction for thoracic esophageal squamous cell carcinoma beyond the mucosal layer. Patients were classified into three groups: group 1 comprised 40 patients without lymph node involvement; group 2 comprised 34 patients with 1-3 positive nodes; and group 3 comprised 15 patients with > or = 4 involved lymph nodes. The 3-year and 5-year survival rates were 77.5% and 73.2% respectively in group 1, 64.8% and 55.8% respectively in group 2, and 28.1% and 0% respectively in group 3. The mean survival time (MST) mean +/- SD of the patients in group 3 (772.1 +/- 146.2 days) was significantly shorter than that of patients in group 1 (3728.5 +/- 320.7 days, p < 0.0001) and group 2 (2330.4 +/- 344.3 days, p = 0.0130). The MST of the patients in group 2 was also significantly shorter than that of patients in group 1 (p = 0.0366). Patients with recurrent lymph nodes that were localized were treated effectively with radiation therapy. We conclude that the number of lymph node metastases influences survival in thoracic esophageal cancer. Early detection as well as radiation therapy for recurrent lymph node metastases is effective in improving long-term survival.

Adult↗
PubMed1999

Highly aggressive behavior and poor prognosis of small-cell carcinoma in the alimentary tract: flow-cytometric analysis and immunohistochemical staining for the p53 protein and proliferating cell nuclear antigen.

The purpose of this study was to determine the clinical course, and effects of the histopathologic characteristics of specific tumors, including DNA contents and immunohistochemical aspects, in patients with small-cell carcinoma of the alimentary tract. Medical records of 14 patients who presented with small-cell carcinoma of the alimentary tract were retrospectively reviewed. Primary tumors were studied by immunohistochemical and flow cytometric analyses. Of these 14 small-cell carcinomas, 4 were esophageal, 8 gastric, and 2 colonic tumors. DNA aneuploidy was observed in 8 tumors. Staining for the p53 product was positive in 57.1% of all the tumors. The average proliferating cell nuclear antigen (PCNA) labeling rate (LR) was 72.4 +/- 11.6%. The average PCNA LR was significantly higher for the p53-positive group (p < 0.05). The estimated median survival was 253 days for all patients. Noncurative resection was associated with a significantly less favorable prognosis (p < 0.01). Distant metastases were observed in 13 of 14 patients. A higher PCNA LR of small-cell carcinoma may be an unfavorable characteristic of biological behavior. The patients with disseminated disease should undergo a symptomatically palliative operation combined with chemotherapy.

Adult↗
PubMed1999

Esophageal sarcomas: report of three cases.

BACKGROUND/AIMS: Sarcomas of the esophagus, including carcinosarcoma, are rare neoplasms. METHODS: The clinical and pathologic characteristics of 3 patients with esophageal sarcomas are presented, including the only recorded esophageal carcinosarcoma and 2 patients with leiomyosarcoma. RESULTS: All 3 patients were males who presented with dysphagia or an abnormal shadow of the mediastinum on a plain chest X-ray. Two tumors were in the middle esophagus, and the remaining one was in the distal esophagus. On endoscopic examination, all three tumors were noted to be polypoid. These patients underwent surgical excision. One patient died 7 days following the operation, and the remaining 2 patients died of liver metastasis 10 and 22 months following the treatment. CONCLUSION: Esophagectomy or esophagogastrectomy is a surgical choice. Even if metastases are present, a palliative resection can still be performed.

Aged↗
PubMed1999

Cervical epidural rhabdomyosarcoma with a leukemia-like presentation in an aged patient--case report.

A 77-year-old female presented with rhabdomyosarcoma manifesting as leukemia-like indications. Neuroimagings detected cervical and paravertebral masses. Immunohistochemical study of the surgically excised mass lesion from the cervical spine established the correct diagnosis. This leukemia-like presentation of rhabdomyosarcoma requires a multidisciplinary approach to establish the correct diagnosis and treatment.

Acute Disease↗
PubMed1999

Serial serum thrombopoietin levels in a pregnant woman with essential thrombocythaemia.

Thrombopoietin (TPO) is a ligand for c-mpl, which regulates the differentiation and maturation of megakaryocytes. Essential thrombocythaemia (ET) is a clonal myeloproliferative disorder. It has been reported that the platelet count declines during pregnancy in ET patients. We examined serial changes in the serum TPO level during the course of pregnancy in a patient with ET. The serum TPO level showed significant negative correlation with the platelet count. Although it mimicked the normal feed back system, the TPO levels were consistently higher than the normal upper limit. Accumulation of these data will be helpful in revealing the pathogenesis of ET and the decline in the platelet count during pregnancy.

Adult↗
PubMed1999

[Tricuspid valve replacement in a patient with idiopathic tricuspid regurgitation].

Tricuspid regurgitation is often seen but is rarely categorized as "idiopathic". A 66-year-old man suspected of idiopathic tricuspid regurgitation underwent tricuspid valve replacement. With right heart failure over twenty years, his CTR increased to eighty six (86) per cent. During operation, no abnormal findings were observed except for the dilated tricuspid valve ring. Then a stented porcine xenograft (Carpentier-Edwards 33 mm) was inserted in the tricuspid valve annulus. Seven years after replacement, he died. Autopsy demonstrated myocardial hypertrophy of the right ventricle and dilatation of the right heart, supporting the diagnosis of idiopathic tricuspid regurgitation.

Aged↗
PubMed1998

Ambiguus nucleus neurons innervating the abdominal esophagus are malpositioned in the reeler mouse.

To examine whether the migration of ambiguus nucleus (NA) neurons is affected in the reeler mouse, recombinant replication-deficient adenoviral vector carrying E. coli-galactosidase gene (lacZ) was injected into the abdominal esophagus of the reeler mouse and normal control at two months of age prior to 5 days of sacrifice of the animals. In the normal control, lacZ-positive neurons were found in the compact formation of the NA, whereas, in the reeler, they were scattered from the base of the fourth ventricle to the ventro-lateral margin of the medulla. The present study confirmed that NA neurons are malpositioned in the reeler mouse, suggesting that the migration of NA neurons is guided by the reelin-related protein (Reelin).

Abdomen↗
PubMed1998

Isolation and structure of pompilidotoxins, novel peptide neurotoxins in solitary wasp venoms.

Novel peptide neurotoxins, alpha- and beta-pompilidotoxins (alpha- and beta-PMTXs), were purified from the venoms of the solitary wasps Anoplius samariensis and Batozonellus maculifrons. Their structures were analyzed mostly by MALDI-TOF-MS, which were corroborated by solid-phase synthesis. alpha-PMTX, with 13 amino acid residues and the sequence of Arg-Ile-Lys-Ile-Gly-Leu-Phe-Gln-Asp-Leu-Ser-Lys-Leu-NH2, greatly potentiates synaptic transmission of lobster leg muscle by the presynaptic mechanisms. beta-PMTX, in which the lysine residue at 12 position of alpha-PMTX was replaced with arginine, was more potent than alpha-PMTX.

Animals↗
PubMed1998

Elevated plasma nitrate in patients with crush syndrome caused by the Kobe earthquake.

We investigated the nitric oxide profile in the plasma of ten healthy controls and 29 patients hurt by the Kobe Earthquake. The levels of nitrite (NO2-) and nitrate (NO3-) were measured simultaneously by high-performance liquid chromatography (HPLC) with UV detection using the Griess reaction after the reduction of nitrate to nitrite. Arginine consumed in food or diet-derived nitrite had no effect on the plasma nitrite and nitrate contents of the healthy volunteers. Plasma nitrate was elevated in the crush syndrome patients; whereas neither nitrite nor nitrate was increased in patients with normal renal function. This finding suggests increased nitric oxide synthesis, decreased excretion of nitric oxide in the crush syndrome or both.

Adult↗
PubMed1998

Primary small cell carcinoma of the esophagus: flow cytometric analysis and immunohistochemical staining for the p53 protein and proliferating cell nuclear antigen.

BACKGROUND AND OBJECTIVES: The purpose of this study was to determine the clinical course and effects of histopathologic characteristics of specific tumors including DNA contents and immunohistochemical aspects in patients with small cell carcinoma of the esophagus. METHODS: Medical records of 4 patients who presented with small cell carcinoma of the esophagus were retrospectively reviewed. RESULTS: DNA aneuploidy was observed in 2 cases. Staining for the p53 product was positive in all cases. The average proliferating cell nuclear antigen (PCNA) labeling rate (LR) was 77.6% (64.0-90.8%). The estimated median survival was 42 days for all patients. Distant metastases were observed in 2 of the 4 patients. CONCLUSIONS: Higher PCNA LR of small cell carcinoma may be an unfavorable characteristic of biological behavior. Patients with disseminated disease should have symptomatically palliative operation combined with chemotherapy.

Aged↗