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Biomedical subjects

Y Tada

Publications and source records attributed to Y Tada.

At least 163 records · Page 9Linked to original sources
PubMed1998

Inwardly rectifying K+ channel in retinal Müller cells: comparison with the KAB-2/Kir4.1 channel expressed in HEK293T cells.

Inwardly rectifying K+ (Kir) channels are considered to play the major role in the spatial buffering of glial cells. We have examined the electrophysiological properties of Kir channels in isolated rabbit Müller cells (retinal glial cells). Although a previous study reported that three kinds of Kir channels with different conductance and rectification properties were expressed in distinct regions of rabbit Müller cell membrane, we could record only a single population of Kir channels from the distal end to the endfoot in 205 successful cell-attached patches. The identified Müller cell Kir channel had a unitary conductance of 25 pS in the inward direction with symmetrical 153 mM K+ condition. The conductance and gating properties of the Müller cell Kir channels were identical to those of the KAB-2/Kir4.1 heterologously expressed in a mammalian cultured cell line, HEK293T cells. Thus KAB-2/Kir4.1 was the predominant glial Kir channel not only in the brain, but also in the retina. Because its rectification is intermediate, this Kir channel may contribute to both the intrusion and the extrusion of K+ ions across glial cell membrane and may be the major pathway for redistribution of extracellular K+ ions in the central nervous system.

Animals↗
PubMed1998

[A case of thymic carcinoma producing granulocyte colony-stimulating factor].

A 73-year-old man was admitted complaining of chest pain and weight loss. A chest X-ray film and chest CT scan showed a tumorous mass in the anterior mediastinum with moderate pleural effusion. Percutaneous needle biopsy specimens from the mass resulted in a diagnosis of poorly differentiated squamous cell carcinoma of the thymus. Laboratory findings on admission showed marked leukocytosis with no evidence of infection or bone marrow metastasis. The level of serum granulocyte colony-stimulating factor (G-CSF) was abnormally high (79.2 pg/ml, normal < 30). Carcinoma cells in the specimen showed positive staining with anti G-CSF monoclonal antibody, thus indicating that they produced G-CSF. Because multiple metastatic lesions on the chest wall and liver were detected, we performed combination chemotherapy with cisplatin, vindesine and mitomycin C. After 2 courses of chemotherapy, a decrease in tumor size was verified by CT scan. As the tumor size decreased, the patients white blood cell count and serum G-CSF concentration fell to normal levels.

Aged↗
PubMed1998

[Toremifene sensitized the effect of adriamycin on human breast cancer cell lines].

A experimental study was reported here to clarify the chemosensitizing effect of Toremifene (Tor) on human breast cancer cell lines. MCF7, estrogen dependent adriamycin (ADM) resistant cell, and MDA-MB231, estrogen independent cell, were preincubated for 8 hours with Tor 0, 4 or 10 microM, then with ADM 0-10 micrograms/ml for one hour. After that, cells were cultured for 24 hours, and their cell cycle and growth were analyzed with flow-cytometry and MTT assay, respectively. Furthermore, the ADM concentrations of these cells were measured by high-performance liquid chromatographic assay (HPLC). Although flowcytometric analysis showed the enhancement of Gz block only in MCF7 at the ADM concentration with 5 micrograms/ml, the sensitizing effect was revealed by MTT assay, and the elevation of ADM concentration was found in HPLC assay in both cells. The chemosensitizing effect of Toremifene was observed in estrogen dependent and independent cell lines.

Antibiotics, Antineoplastic↗
PubMed1998

[Analysis for predicting the prognostic factors of gastrointestinal tract leiomyosarcoma using MIB-1 and DNA flow cytometry].

PURPOSE: The present study was undertaken to investigate the possibility of determining a prognosis for gastrointestinal tract leiomyosarcoma with the use of DNA analysis and MIB-1 staining. SUBJECTS AND METHODS: Malignant tumors originating in smooth muscle of the gastrointestinal tract, surgically excised from 23 lesions in 17 patients (stomach; 8 cases, 12 lesions; small intestine: 6 cases, 8 lesions; colon: 3 cases, 3 lesions) and embedded in paraffin, were examined. DNA was analyzed using flow cytometry to produce a DNA histogram, and aneuploidy and diploidy were found. MIB-1 staining was done in conformity with the ABC method. RESULTS: 1. An investigation of prognoses using the Kaplan-Meier method revealed a tendency for more favorable prognoses in patients determined to be aneuploid through DNA analysis. However, this was not significantly better than those exhibiting diploidy. 2. All patients who died had a MIB-1 staining positivity rate of over 10%, while all patients who had no recurrence within one year or survived had a MIB-1 staining positivity of less than 10%. 3. No consistent trends were observed between MIB-1 positivity rate and DNA analysis, MIB-1 positivity rate and size of tumor, or DNA analysis and size of tumor. 4. The MIB-1 positivity rate of patients with remote metastases was significantly greater than that of patients with no remote metastases. CONCLUSION: From the fact that patients with MIB-1 positivity rates of greater than 10% had a poor prognosis, while those with rates of less than 10% had a favorable prognosis, we conclude that a MIB-1 positivity rate of 10% is an important value in determining the prognosis of patients with gastrointestinal tract leiomyosarcomas.

Adult↗
PubMed1998

[A preventable case who died of miliary tuberculosis after receiving contact examination].

A 30-year-old-man was admitted to our hospital because of headache and fever. His consciousness on admission was clouding. Sputum examination was positive for acid fast bacilli which later identified as Mycobacterium tuberculosis. Chest-X-ray and computed tomogram on admission showed multiple cavitary lesions on bilateral upper lung fields and bilateral diffuse nodular shadow. He was diagnosed as miliary tuberculosis with tuberculous meningitis. His mother admitted because of pulmonary tuberculosis four months ago, and her sputum examination was smear positive for acid fast bacilli, Gaffky 4, and she complained of cough for 6 months before admission. Because of this situation, he rapidly underwent the contact examination with chest X-ray, but not examined by tuberculin skin test because he was 30-year-old. As then chest X-ray was normal, he was not indicated of chemoprophylaxis, and he died of miliary tuberculosis and tuberculous meningitis 4 months after the contact examination.

Adult↗
PubMed1998

[Fenestration of diaphragm for management of persistent postoperative pleural effusion: clinical experience and experiment in rabbits].

UNLABELLED: The management of persistent postoperative pleural effusion is still considered difficult. We report here our experience with such a case, successfully managed with fenestration of the diaphragm-the first of it's kind. Clinical Experience: A two-year-old boy with double outlet right ventricle, underwent right heart bypass procedure. Due to low output and high venous pressure, he was on ventilator until the 26th postoperative day. The pericardial and right pleural effusion persisted till the 60th postoperative day. Right phrenic nerve palsy and atelectasis of right lower lobe were suspected to contribute to it. We performed a plication of the right diaphragm and fenestration of the pericardium and right diaphragm. A T-shaped incision was made on the right diaphragm and the edges were trimmed and strengthened with non-absorbable suture into a circular shaped defect of 1.5 cm diameter. The defect was closed with a Dacron mesh allowing passage of fluid across. Pleural effusion decreased immediately and he was discharged a month after the procedure. Experimental Study: The above procedure was experimented in rabbits in whom a contrast medium injected into the pleural cavity could easily drain into the peritoneum through the fenestation, proved by fluoroscopy. CONCLUSION: Fenestration of the diaphragm is an effective procedure to manage persistent pleural effusion.

Animals↗
PubMed1998

[A case of miliary tuberculosis with multiple cerebral tuberculoma and spinal tuberculosis owing to total delay].

We reported a case of miliary tuberculosis with multiple cerebral tuberculoma and spinal tuberculosis. The case was a 37 year old man. In the last sixteen months to the first visit to a hospital, he has been suffering from low grade fever, cough, and back pain, but he bared his symptoms without any therapy. At a hospital he first visited, he was told that he might have a malignant disease, which prevented him to visit the hospital because of a fear for his disease. Six months later, he was admitted to other hospital because of severe back pain. At last, he was diagnosed as tuberculosis and referred to our hospital. By the examinations on admission he was diagnosed as multiple cerebral tuberculoma and spinal tuberculosis, and anti-tuberculous therapy was started. It is thought that his severe disease status on admission is caused by the total delay, namely the delay in visiting a doctor and the doctor's delay in making diagnosis.

Adult↗
PubMed1998

[A case of cutaneous tuberculosis associated with steroid therapy for mixed connective tissue disease].

Patients receiving immunosuppressive therapy, such as adrenocorticosteroids, are high risk groups of tuberculosis. We report a case of cutaneous tuberculosis associated with steroid therapy for mixed connective tissue disease. A 63-year-old female was hospitalized after 6 months' treatment with prednisolone for connective tissue disease and bilateral abnormal shadows were revealed on her chest X-ray films. As her sputum smear was positive for acid-fast bacilli, the patient was transferred to our hospital for isolation and treatment. After three months' treatment with INH, RFP and EB, she complained the swelling of her left palm, left arm, and right leg, and skin puncture was performed. As smears of fluid aspirated from the swelling showed acid-fast bacilli, and fluid PCR tests showed positive for M. tuberculosis, she was diagnosed as cutaneous tuberculosis (scrofuloderma). In spite of administration of antituberculous agents, the swelling showed little improvement. Therefore, the dose of prednisolone was reduced and cutaneous lesions were resected by surgery. High risk of tuberculosis should be considered when a patient administered immunosuppressive drugs, such as adrenocorticosteroids.

Anti-Inflammatory Agents↗
PubMed1998

[Motor association cortex activity in Parkinson's disease--a functional MRI study].

The purpose of this study was to examine the activation of motor association cortex using functional magnetic resonance imaging (fMRI) in patients with Parkinson's disease (PD) and control subjects during performed hand movements. There were 26 patients with PD (12 patients with Hoehn and Yahr stage I-II, 14 patients with stage III) and 8 control subjects. Functional imaging was performed using a 1.5 tesla MRI system equipped with a single-shot, echo-planar pulse sequence. The significant signal changes were observed within the primary sensorimotor area, the supplementary motor area (SMA), and the parietal association area in both PD and control subjects. In PD subjects, the SMA was less activated than in control subjects; there were significant differences in the number of pixels activated in SMA between control and Yahr III group (p < 0.01), and between Yahr I-II and Yahr III group (p < 0.01). Our results demonstrated that movement related cerebral activity in the SMA is reduced in PD subjects, consistent with previously published data using other methods. It is well known from anatomical studies that one of the major cortical outputs of the basal ganglia is the SMA. This may explain the hypoactivation of the SMA in PD. Studies using fMRI provide a promising method not only for localizing cortical activation related to voluntary movements but also for investigating pathophysiology of movement disorders.

Aged↗
PubMed1997

Hemotoxicity of chlorpropham (CIPC) in F344 rats.

Chlorpropham[Isopropyl-N-(3-chlorophenyl)carbamate; CIPC] is a widely used sprout suppressant. Groups of ten male and ten female F344 rats were given 0, 7500, 15,000 or 30,000 ppm of CIPC in the diet for 13 weeks. Body weight gain of male and female rats in the 30,000 ppm-group was depressed. Spleen and liver weights of male and female rats in the treated groups were dose-dependently increased. Red blood cell count, hemoglobin concentration, hematocrit, mean corpuscular hemoglobin concentration and platelet count were decreased in male and female rats of the treated groups. Methemoglobin level, mean corpuscular volume and mean corpuscular hemoglobin were increased in male and female rats of the treated groups. Those hematological changes were dose-dependent and were marked in the 15,000 and 30,000 ppm-groups. White blood cell count of male and female rats in the 30,000 ppm-group were significantly higher than those of the control group. Congestion, increased hemosiderin deposition, increased extramedullary hemopoiesis, lymphoid atrophy and fibrosis were seen in spleen of male and female rats of all treated groups in a dose-dependent manner. Hemopoietic cell hyperplasia was marked in bone marrow of male and female rats in all treated groups. The results suggested that the erythrocyte is one of the primary targets of CIPC toxicity in rats.

Animals↗
PubMed1997

Expression and clustered distribution of an inwardly rectifying potassium channel, KAB-2/Kir4.1, on mammalian retinal Müller cell membrane: their regulation by insulin and laminin signals.

Inwardly rectifying potassium (K+) channels (Kir) in Müller cells, the dominant glial cells in the retina, are supposed to be responsible for the spatial buffering action of K+ ions. The molecular properties and subcellular localization of Müller cell Kir channels in rat and rabbit retinas were examined by using electrophysiological, molecular biological, and immunostaining techniques. Only a single population of Kir channel activity, the properties of which were identical to those of KAB-2/Kir4.1 expressed in HEK293T cells, could be recorded from endfoot to the distal portion of Müller cells. Consistently, Northern blot, in situ hybridization, and RT-PCR analyses indicated expression of Kir4. 1 in Müller cells per se. The Kir4.1 immunoreactivity was distributed in clusters throughout Müller cell membrane. The Kir4.1 expression in Müller cells disappeared promptly after culturing. When the dissociated Müller cells were cultured on laminin-coated dishes in the presence of insulin, Kir4.1 immunoreactivity was detected in a clustered manner on the cell membrane. Because insulin and laminin exist in the surrounding of Müller cells in the retina, these substances possibly may be physiological regulators of expression and distribution of Kir4.1 in Müller cells in vivo.

Animals↗
PubMed1997

Clustering and enhanced activity of an inwardly rectifying potassium channel, Kir4.1, by an anchoring protein, PSD-95/SAP90.

An inwardly rectifying potassium channel predominantly expressed in glial cells, Kir4.1/KAB-2, has a sequence of Ser-Asn-Val in its carboxyl-terminal end, suggesting a possible interaction with an anchoring protein of the PSD-95 family. We examined the effects of PSD-95 on the distribution and function of Kir4.1 in a mammalian cell line. When Kir4.1 was expressed alone, the channel immunoreactivity was distributed homogeneously. In contrast, when co-expressed with PSD-95, prominent clustering of Kir4.1 in the cell membrane occurred. Kir4.1 was co-immunoprecipitated with PSD-95 in the co-expressed cells. Glutathione S-transferase-fusion protein of COOH terminus of Kir4.1 bound to PSD-95. These interactions disappeared when the Ser-Asn-Val motif was deleted. The magnitude of whole-cell Kir4.1 current was increased by 2-fold in cells co-expressing Kir4.1 and PSD-95 compared with cells expressing Kir4. 1 alone. SAP97, another member of the PSD-95 family, showed similar effects on Kir4.1. Furthermore, we found that Kir4.1 as well as SAP97 distributed not diffusely but clustered in retinal glial cells. Therefore, PSD-95 family proteins may be a physiological regulator of the distribution and function of Kir4.1 in glial cells.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Phosphorylation-independent inhibition by intracellular cyclic nucleotides of brain inwardly rectifying K+ current expressed in Xenopus oocytes.

An inwardly rectifying K+ current, which was heterologously expressed in Xenopus oocytes, was inhibited by isoproterenol, a fadrenergic agonist. Poly(A)+ mRNA isolated from guinea-pig brain was injected into oocytes 2-3 days before experiments. Isoproterenol inhibition of the K+ current was time-and voltage-dependent: the inhibition became faster and more pronounced as the command voltage steps were applied to more negative potentials. This inhibition was prevented by propranolol. Dibutylyl cyclic (dB-c) AMP could mimic the effect of isoproterenol, while injection of the catalytic subunit of cAMP-dependent protein kinase into the oocytes did not affect the K+ current. Inhibitors of the protein kinases, WIPTIDE and H-8, did not prevent the inhibition by dB-cAMP. Furthermore, dB-cGMP also inhibited the K+ current in a similar time- and voltage-dependent manner. We propose that the phosphorylation-independent action of cyclic nucleotides mediates beta-adrenergic inhibition of brain inwardly rectifying K+ channels expressed in Xenopus oocytes.

Adrenergic beta-Agonists↗
PubMed1997

Reduced incidence and severity of antigen-induced autoimmune diseases in mice lacking interferon regulatory factor-1.

Interferon regulatory factor-1 (IRF-1) is a transcription factor that regulates interferon-induced genes and type I interferons. Recently, studies of IRF-l-deficient mice have revealed that IRF-I regulates the induction of molecules that play important roles in inflammation, such as inducible nitric oxide synthase (iNOS) and interleukin-l beta-converting enzyme (ICE). To study the role of IRF-1 in autoimmunity, we investigated type II collagen-induced arthritis (CIA), and experimental allergic encephalomyelitis (EAE), in mice lacking IRF-1. The incidence and severity of CIA were significantly decreased in IRF-1-/- mice compared with IRF-l +/- mice, as was the production of interferon (IFN)-gamma in lymph node cells. Both IRF-l+/- and IRF-1-/- mice exhibited mild and transient disease after adoptive transfer of a type II collagen (CII)-specific T cell line together with sera from arthritic mice, but the IRF-1-/- mice were less severely affected than the IRF-1+/- mice. In addition, the incidence of EAE in IRF-1-/- mice was decreased as compared with IRF-1 +/- mice. Reverse transcription polymerase chain reaction showed that IRF-1 mRNA was constitutively expressed in the spinal cords of IRF-1+/- mice, and was upregulated in mice with clinical EAE. Expression of iNOS was also detected in inflamed spinal cords. These results suggest that IRF-I plays a key role in promoting inflammation and autoimmunity in CIA and EAE animal models.

Animals↗
PubMed1997

Length of transplanted small bowel required for adequate weight gain in rats.

Progress has been made toward developing a clinically successful small-bowel transplant procedure, but there has been little research concerning the functional aspects of the transplanted small bowel. Using a rat model, our study examined the length of transplanted small bowel required to provide adequate weight gain. The rats were divided into six groups; groups 1 and 2 were considered controls. Group 1 (n = 6) underwent a gastrostomy. Group 2 (n = 3) underwent a jejunoile-ectomy followed by re-establishment of intestinal continuity and anastomosis of the native proximal small bowel to an abdominal stoma and the distal portion to the ascending colon. Groups 3 (n = 5), 4 (n = 4), 5 (n = 5), and 6 (n = 4) underwent small-bowel transplantation, receiving 100%, 50%, 25%, and 15% transplants, respectively. The donor small-bowel anastomoses were the same as the native small-bowel anastomoses in group 2. All of the rats began to produce stool within 4 days of becoming dependent upon the transplanted small bowel. By the end of postoperative week 4, there was no significant difference between the percentages of preoperative body weight in groups 1-4 (range 125.7%-130.0%). Although the weight gain in group 5 was significantly less than that in groups 1-4 (P < 0.05), it was adequate (111.8%); group 6 animals lost weight (94.7%). It is concluded that a 50% or more small-bowel transplant with or without an ileocecal valve provides ample weight gain; minimally adequate weight gain is achieved by a 25% transplant without an ileocecal valve; and the graft begins to function soon after transplantation.

Animals↗
PubMed1997

Delayed manifestation of aortic stenosis after blunt abdominal trauma: report of a case.

Delayed manifestation of aortic stenosis caused by abdominal blunt trauma is rare. We report herein the case of a 67-year-old man who was taken to a nearby hospital after being crushed between a heavy truck and a wall. An emergency laparotomy was performed, revealing only a mesenteric tear which was repaired. He was discharged after an uneventful postoperative course; however, 1 month later he began to experience intermittent claudication, and presented to our hospital in December 1994, 1 year after the first operation. Angiography and enhanced computed tomography (CT) demonstrated infrarenal abdominal aortic dilatation with distal stenosis. Both the dilated and stenotic lesions were resected and bypass surgery ws performed. Pathologic examination demonstrated that the intima had been lacerated circumferentially and everted distally, causing the aortic stenosis. To our knowledge, this is the first case of the delayed manifestation of traumatic aortic stenosis to be documented in Japan. The etiology of this rare complication of blunt trauma is described in this report.

Abdominal Injuries↗
PubMed1997

Detection of Trypanosoma congolense and T. brucei subspecies in cattle in Zambia by polymerase chain reaction from blood collected on a filter paper.

To facilitate epidemiology studies of African trypanosomiasis in cattle in Zambia, we adapted a polymerase chain reaction (PCR) method using blood spotted on filter papers. For easy preparation of template DNA from the dried blood, we adapted a simple DNA extraction method using Chelex-100, an anion-exchange resin. Using primers directed for repetitive nuclear DNA sequences, species-specific DNA amplifications were detected from the blood of rats infected with Zambian isolates of T. congolense and T. brucei subspecies. The method was sensitive enough to detect a single trypanosome for both species. In the Eastern Province of Zambia, 240 cattle were examined for motile flagellates in the buffy coat by the microhematocrit method, and 100 of them were positive for the test. These 100 animals were further examined by thin blood smears and PCR for species identification. The thin blood smear revealed 62 and 14 animals with T. congolense and T. brucei subspecies infection, respectively, whereas the PCR detected 73 of the former and 38 of the latter species. These results indicate that dried blood spots on filter papers are a useful source of DNA for detection of African trypanosomes by PCR.

Animals↗