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Biomedical subjects

N Katayama

Publications and source records attributed to N Katayama.

341 records · Page 19Linked to original sources

Dynamics of a hybrid system of a brain neural network and an artificial nonlinear oscillator.

In the brain, many functional modules interact with each other to execute complex information processing. Understanding the nature of these interactions is necessary for understanding how the brain functions. In this study, to mimic interacting modules in the brain, we constructed a hybrid system mutually coupling a hippocampal CA3 network as an actual brain module and a radial isochron clock (RIC) simulated by a personal computer as an artificial module. Return map analysis of the CA3-RIC system's dynamics showed the mutual entrainment and complex dynamics dependent on the coupling modes. The phase response curve of CA3 was modeled regarding the CA3 as a nonlinear oscillator. Using the phase response curves of CA3 and RIC, we reconstructed return maps of the hybrid system's dynamics. Although the reconstructed return maps almost agreed with the experimental data, there were deviations dependent on the coupling mode. In particular, we noted that the deviation was smaller under the bidirectional coupling conditions than during the one-way coupling from RIC to CA3. These results suggest that brain modules may flexibly change their dynamical properties through interaction with other modules.

Hippocampus↗

Binding of a non-beta-lactam antibiotic to penicillin-binding proteins.

In the search for new beta-lactam antibiotics of natural origin, the discoveries of cephamycins and sulfazecins (monobactams) were important turning points in that they accelerated many screening efforts aimed at other new compounds. In our target-directed screening for beta-lactam antibiotics using beta-lactam hypersensitive mutants, we have examined Gram-negative bacteria isolated from natural habitats and have recently reported several types of beta-lactam antibiotics such as cephabacins and formadicins. Here we report a novel antibiotic, lactivicin, found using this system. Although lactivicin has various biological activities commonly observed in beta-lactam antibiotics, it does not possess a beta-lactam ring in its molecule, but has the unique structure of a dicyclic dipeptide.

Anti-Bacterial Agents↗

Isolated factor VII deficiency diagnosed after a life-threatening brain haemorrhage.

A 65-year-old man was admitted to another hospital with a life-threatening brain haemorrhage, and laboratory examinations on admission revealed prolonged prothrombin time with normal activated partial thromboplastin time. To establish the cause of his abnormal coagulation, he was referred to our clinic. Neither the patient nor his family had any previous history of bleeding symptoms. His liver function was within normal limits but coagulation tests showed increased plasma activities of factors II, VIII, IX, X, with reduced activities of factors V and VII. The activity of factor VII was less than 2% but no inhibitor of factor VII was detected in the plasma. We concluded that the patient had a rare congenital isolated factor VII deficiency although he had not shown earlier bleeding problems, presumably because of compensation for the factor VII deficiency by enhanced activities of components of the extrinsic coagulation pathway, factors II, VIII, IX and X.

Aged↗

The CAG regimen (low-dose cytarabine, aclarubicin hydrochloride and granulocyte colony-stimulating factor) for the treatment of elderly acute myelomonocytic leukaemia: a case study.

Elderly patients with acute myelomonocytic leukaemia (AMMoL) frequently have a poor quality of life after induction of remission using high-intensity treatment; we seek a more appropriate regimen for such patients. An 86-year-old man was hospitalized with a diagnosis of AMMoL (FAB classification M4), of abnormal karyotype, and complications of diabetes mellitus and complete right bundle branch block. He was treated with CAG therapy (cytarabine 10 mg/m2 subcutaneously every 12 h for 14 consecutive days; aclarubicin hydrochloride 10 mg/m2 per day, bolus intravenously for 4 consecutive days; granulocyte colony-stimulating factor 100 microg/day, subcutaneous injection for 14 consecutive days) every 3 months. White blood cell counts were at their lowest (around 600 - 800/microl) 12 days after the end of therapy, but returned to about 2000 - 2300/microl 30 days after stopping therapy. No symptoms of drug-related toxicity, except slight nausea, were found. Complete remission with a good quality of life was induced and lasted over 2 years suggesting that CAG therapy might prove effective in elderly patients with AMMoL.

Aclarubicin↗

Treatment of acute myeloblastic leukaemia in a patient with Bombay blood type: a case report.

A 62-year-old female was admitted to our hospital with suspected acute leukaemia and after investigation we diagnosed acute myeloblastic leukaemia (AML-M1). The patient's blood type was found to be the very rare Bombay type and surveillance of her relatives showed the same blood type in her male cousin on her mother's side. Alongside chemotherapy the patient received 4000 ml of frozen Bombay-type red cells, 1400 ml of concentrated red cells in manitol adenine phosphate solutions and 360 units of type O concentrated platelets without marked effects. The anti-H antibody was initially at 128 dilution but for unknown reasons increased to 2048 dilution after remission of AML-M1. About 3 months after hospitalization the patient died of Cryptococcus neoformans pneumonia despite strict precautions against infection. Although AML-M1 is a common adult leukaemia and is chemosensitive to anti-leukaemic drugs, neither AML-M1 in a patient with Bombay-type red cells nor its treatment with chemotherapy and transfusion with type Oh frozen red cells have previously been reported.

Antineoplastic Agents↗

A therapeutic strategy for isolated plasmacytoma of bone.

Two cases of solitary plasmacytoma of bone (SPB) were diagnosed. The first case was a 41-year-old woman, complaining of fatigue from her lumbar region to her legs. The second case was a 56-year-old man complaining of poor gait and severe lumbago with numbness in the toes of both feet. Magnetic resonance imaging showed the osteolytic lesion in the 12th thoracic bone in the first patient and around the 2nd, 3rd and 4th lumbar bones in the second patient. In both patients serum analysis revealed the monoclonal component of immunoglobulin G (IgG) protein with kappa-light chain, and considering this and other findings SPB was diagnosed. Both patients were first treated with irradiation around the involved bone and then with a course of chemotherapy. In the first patient the tumour region of the bone was surgically removed and replaced with a ceramic spacer. The symptoms of both patients were ameliorated, and the patients remained in good condition for around 3 years without conversion to multiple myeloma. In view of the overall effectiveness of treatments for SPB, our therapeutic strategy deserves careful evaluation.

Adult↗

Purpura due to aspirin-induced platelet dysfunction aggravated by drinking alcohol.

We report a rare case of prominent purpura induced by aspirin and enhanced by alcohol. A 44-year-old woman presented with a history of generalized purpura. She drank alcohol once or twice a week and regularly took an analgesic preparation, containing aspirin and acetaminophen, for alleviation of headaches. When purpura was evident the patient's liver function was within normal limits and her coagulation time was normal but her bleeding time was prolonged. Red blood cell, white blood cell and platelet counts were normal but a poor response to platelet agonists demonstrated platelet dysfunction. After stopping the analgesic and abstaining from alcohol for 5 days, platelet aggregation, in response to the agonists, returned to normal and purpura disappeared. When the patient took further doses of the analgesic preparation for 3 days for headache relief, but did not drink alcohol, platelet aggregation was again abnormal but purpura was only slight.

Adult↗

Autologous peripheral stem-cell transplantation after intensive chemotherapy in a case of CD30 (Ki-1)-positive anaplastic large-cell lymphoma.

Simultaneous treatment with peripheral blood stem-cell (PBSC) transplantation and intensive chemotherapy was evaluated in a case of non-Hodgkin's lymphoma (NHL) with poor prognosis. A 59-year-old male diagnosed with a high-grade, anaplastic large-cell (Ki-1) NHL, involving fractures in the left hip, underwent computed tomography and gallium scintigram surveillance. The patient received chemotherapy with epirubicin hydrochloride, cyclophosphamide, vincristine and prednisolone, and the fractured hip bone was repaired following the first course of chemotherapy. After the second and third courses of chemotherapy, PBSCs were harvested and cryopreserved. The patient then received a further course of chemotherapy and PBSC transplantation was conducted using infused cells consisting of 9.63 x 10(6)/kg CD34 cells and 2.24 x 10(5)/kg granulocyte macrophage colony-forming units. Recovery of platelet and white blood cell counts occurred 10 and 8 days, respectively, after PBSC infusion and the patient remains well.

Antineoplastic Combined Chemotherapy Protocols↗

Malignant lymphoma of the lung: report of an autopsy case and review of literature.

A 74-year-old man complained of a cough and left chest pain. Chest X-ray showed marked pleural effusion and a large mass in the left lower lobe, and air bronchograms within the mass were observed by tomography and computed tomography (CT). About 3 months later, the patient died of left atelectasis and pneumonia. Autopsy revealed a localized tumor in the lower lobe of the left lung. Histologically, proliferation of lymphoma cells was noted. Immunoglobulin staining showed B cell-type monoclonality. No metastasis was evident except for a very small nodular area in the left renal cortex.

Aged↗

An adult case of acute lymphoblastic leukemia with necrotizing leukoencephalopathy.

A 19-year-old man with common acute lymphoblastic leukemia (ALL) developed necrotizing leukoencephalopathy (NL) after extensive chemotherapy and irradiation. Clinicians should exercise care in the treatment of leukemia, since chemotherapy has shown a trend of becoming more intensive, and the survival time of patients with leukemia is being extended.

Adult↗

Local recurrence of breast cancer demonstrated on 99mTc-MIBI scintigraphy.

We present a postmastectomy patient in whom a mass was palpated in the chest wall. It appeared to be difficult to determine whether the chest wall mass was local recurrence of breast cancer or granulation induced by mastectomy on computed tomography (CT). The mass was successfully demonstrated on 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) scintigraphy as an area of increased accumulation, and was considered to be a recurrent tumor. Surgical resection was performed, and the mass was histopathologically proven to be recurrence. 99mTc-MIBI scintigraphy may contribute to the detection of local recurrence or distant metastasis in addition to the diagnosis of primary breast cancer and axillary metastasis.

Breast Neoplasms↗

A case of jugular foramen chordoma with extension to the neck: CT and MR findings.

We describe a case of jugular foramen chordoma with extracranial extension into the carotid, parapharyngeal, and perivertebral spaces through the jugular foramen. Although this type of extension is unusual, the differential diagnosis of head and neck tumors includes unusual extension of chordoma as well as extension of meningioma and neurinoma from the posterior skull base.

Aged↗