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Biomedical subjects

T Ohtsuka

Publications and source records attributed to T Ohtsuka.

At least 181 records · Page 10Linked to original sources

G protein specificity of the muscarine-induced increase in an inward rectifier potassium current in AtT-20 cells.

Muscarine and somatostatin enhance an inward rectifier K+ conductance in the AtT-20 pituitary cell line. Both effects are abolished by pertussis toxin (PTX). To determine which PTX-sensitive G protein mediates these agonist effects, we made cDNAs encoding mutant PTX-insensitive Gi alpha subtypes, in which the cysteine residue fourth from the C terminus was replaced with serine. The mutated cDNA was transfected into AtT-20 cells, resulting in stable cell lines overexpressing a Gi alpha subtype. As controls, wild-type Gi alpha cDNA was transfected into AtT-20 cells. The agonist-induced increase of the inward rectifier K+ conductance in the transfectants was examined with the whole-cell clamp method. Only in the cell lines into which the mutated (PTX-insensitive) Gi2 alpha cDNA was transfected, did the muscarine response become PTX-insensitive, suggesting that Gi2 couples to the muscarinic receptor and enhances the activity of the inward rectifier K+ channel. However, PTX-insensitive somatostatin responses were not obtained in any of the cell lines transfected with a mutated Gi alpha cDNA, suggesting either that none of the Gi subtypes is a transducer for the somatostatin effect or that the mutation prevents the coupling of the Gi alpha to the somatostatin receptor.

Animals↗

Primary B-cell lymphoma of the breast in patient with smoldering type adult T-cell lymphoma.

We report a patient with primary B-cell lymphoma of the breast complicated by smoldering type adult T-cell leukaemia (ATL). A 52-year-old Japanese woman complained of a rapidly enlarging lump in her right breast. She had been diagnosed to have smoldering type ATL since the age of 49. Aspiration cytology and subsequent excisional biopsy revealed B-cell type lymphoma of the breast. A gallium-scintigram showed abnormal accumulation in the bilateral breasts. Radiology was adopted because the lesion was localized only in the breasts and associated with smoldering type ATL. The lesions disappeared after the treatment.

Breast Neoplasms↗

Pathogenic role of thromboxane A2 in immediate food hypersensitivity reactions in children.

BACKGROUND: Food hypersensitivity, from the standpoint of pathogenesis as well as clinical management, remains controversial. During the food allergen-induced immediate hypersensitivity reaction, various chemical mediators are released. OBJECTIVE: The purpose of our study was to determine whether thromboxane A2 participates in food antigen-induced responses in children with food hypersensitivity. METHODS: Nine open food challenges were performed in nine patients with suspected food hypersensitivity. Plasma thromboxane B2 and histamine levels were measured during a 24-hour period following the challenge. RESULTS: All the patients demonstrated immediate reactions after food challenge. The mean plasma thromboxane B2 level (a marker of thromboxane A2 activity) rose significantly at two hours and three hours after the challenge. Simultaneously, the mean plasma histamine level rose significantly at two hours and three hours after the challenge. CONCLUSIONS: The results suggest that thromboxane A2 may play a pathogenic role in part in the immediate reaction after food challenge and that thromboxane A2 is probably released from a common cellular source (eg, mast cell) with histamine and/or by a common mechanism (eg, IgE-dependent platelet activation).

Child↗

Mid-term result of one and one half ventricular repair in a patient with pulmonary atresia and intact ventricular septum.

A 10-year-old girl was referred to us with a diagnosis of pulmonary atresia and intact ventricular septum with a severely hypoplastic right ventricle and atrial septal defect. Her tricuspid valve diameter (TVD) was 48.5% of normal, with a TVD Z-score of -6.7, while right ventricular end-diastolic volume was 53.4% of normal. As a definitive procedure, one and one half ventricular repair using a bidirectional cavopulmonary shunt (BCPS) was performed instead of a Fontan procedure. The postoperative course was uneventful without episodes of low cardiac output or elevated right atrial pressure. She has been doing well during a follow-up period of 3 years.

Cardiac Surgical Procedures↗

[Video-assisted thoracic surgical (VATS) biopsy as a technique for differential diagnosis of indeterminate small pulmonary nodules].

The authors experienced two cases of multiple pulmonary tuberculomas, which were suspected of metastatic lung tumors. First patient was a 63-years-old male, who was found to have multiple pulmonary nodular shadows on his check up chest X-ray film, suspected of pulmonary metastases of rectal cancer. VATS biopsy, performed for one of nodules revealed that it was caseating granuloma, suggestive of pulmonary tuberculosis. Second patient was a 55-years-old female with rheumatoid arthritis and a chest X-ray film showed multiple pulmonary nodules, which were thought to be metastatic lung tumor from unknown origin. VATS biopsy for a subpleural nodule showed epitheloid granuloma with caseous necrosis of lung, indicating pulmonary tuberculosis. VATS biopsy is, therefore, an useful technique for differential diagnosis of small pulmonary nodules of unknown origin.

Biopsy↗

[Small-cell lung cancer and subacute sensory neuropathy in a patient positive for the anti-Hu antigen].

We encountered a case of small-cell lung cancer in a patient with subacute sensory neuropathy that began 5 months before the cancer was diagnosed. A 60-year-old man complained of abnormalities in the functioning of his peripheral sensory systems (senses of pain, touch, position, and vibration). A chest X-ray film obtained on admission showed an anterior mediastinal tumor. The anti-Hu antibody was found in his serum. The diagnosis was small-cell lung cancer. Combination chemotherapy (cisplatin and irinotecan, CPT-11) was begun and the response was a complete remission. The symptoms of neuropathy continued. The anti-Hu antibody was useful in the diagnosis in the case of small-cell lung cancer combined with subacute sensory neuropathy.

Acute Disease↗

[Hemodynamic and pathological changes in the normal rabbit brain after linac stereotactic irradiation].

A number of clinical reports on stereotactic radiosurgery using a linear accelerator have been published. So far, however, basic studies using the experimental animals have been comparatively few in number. Changes of cerebral hemodynamics and pathohistology in the animal brain after stereotactic, large dose irradiation was studied in this experiment. Fourteen pure imbred Japanese white rabbits, weighing approximately 5 kg, were used. As the landmark for irradiation targeting, a small silicone ball, 2 mm in diameter, was implanted aseptically in the right frontal bone. A month after placing the landmark, stereotactic irradiation was given in a single dose of 100 Gys by a linear accelerator with a 10 mm collimator. In all animals, dynamic CT was carried out before and immediately after irradiation, and thereafter, it was repeated at various intervals. Time density curve which has two parameters of peak-time (PT) and peak-height (PH), was drawn with the help of Sprine function. The ratios of PT, PH, and CBF were calculated for their values in the irradiated area/values in the contralateral corresponding area. Two animals were sacrificed immediately, 1, 3, 7, 21, 90 and 180 days respectively after irradiation, and one animal was killed 1 year after radiation followed by another animal killed 2 years after irradiation. Brains were removed and formalin-paraffin sections were made. All sections were stained with hematoxylin-eosin and GFAP (glial fibrillary acidic protein). In the brain of day 3, cerebral hemorrhage and an increase of astrocyte were demonstrated in the irradiated area. The increase of astrocyte had persisted for approximately 3 weeks. On the other hand, neurons and vessels appeared intact, even i the brain of day 90. In the brain of day 180, brain necrosis had developed in the irradiated area and necrosis had become wider and more prominent in the brains of 1 and 2 years after irradiation. Fibrinoid degeneration of capillaries was evident in the irradiated area and its adjacent areas. Regional cerebral blood flow (r-CBF) in the irradiated area decreased for 3 days and continued to remain at a lower level for a week. However, r-CBF increased thereafter again at 3 weeks. Then it gradually continued to decrease and finally it became unmeasurable at one or 2 years after irradiation. To interpret the fact that there is a biphasic time course for r-CBF, the early decrease was attributed to local edema, and the later decrease was attributed to changes in the wall of vessels.

Animals↗

Purification of a Ras-dependent mitogen-activated protein kinase kinase kinase from bovine brain cytosol and its identification as a complex of B-Raf and 14-3-3 proteins.

We previously purified a protein factor, named REKS (Ras-dependent Extracellular Signal-regulated Kinase (ERK)/mitogen-activated protein kinase Kinase (MEK) Stimulator), from Xenopus eggs by use of a cell-free assay system in which recombinant GTP gamma S (guanosine 5'-(3-O-thio)triphosphate)-Ki-Ras activates recombinant MEK. By use of this assay system, we purified here bovine REKS to near homogeneity from the cytosol fraction of bovine brain by successive chromatographies of Mono S, Mono Q, GTP gamma S-glutathione S-transferase-Ha-Ras-coupled glutathione-agarose, and Mono Q columns. It was composed of three proteins with masses of about 95, 32, and 30 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The 95-, 32-, and 30-kDa proteins were identified by immunoblot analysis to be B-Raf protein kinase, 14-3-3 protein, and 14-3-3 protein, respectively. Moreover, the REKS activity was specifically immunoprecipitated by an anti-B-Raf antibody. Bovine REKS was activated by lipid-modified GTP gamma S-Ki-Ras far more effectively than by a lipid-unmodified one. Lipid-modified GDP-Ki-Ras was inactive. Exogenous addition of 14-3-3 proteins stimulated further the REKS activity both in the presence and absence of GTP gamma S-Ki-Ras. These results indicate that at least one of the direct targets of Ras is B-Raf complexed with 14-3-3 proteins in bovine brain.

14-3-3 Proteins↗

Doc2: a novel brain protein having two repeated C2-like domains.

Two repeated C2-like domains interacting with Ca2+ and phospholipid are found in synaptotagmin and Rabphilin-3A which are implicated in neurotransmitter release. Here we have isolated a cDNA encoding a novel protein having two repeated C2-like domains from a human brain cDNA library. The isolated cDNA encodes a protein with 400 amino acids and a M(r) of 44,071. The purified recombinant protein indeed interacts with Ca2+ and phospholipid. We have named this protein Doc2 (Double C2). Doc2 is exclusively expressed in brain and is highly concentrated in the synaptic vesicle fraction. These results suggest that Doc2 is a novel brain protein and serves as a Ca2+ sensor in neurotransmitter release.

Adaptor Proteins, Signal Transducing↗

Relation between gestational sac diameter, crown-rump length, and maternal serum estradiol, progesterone, and prolactin levels in early pregnancy.

In 152 patients with an early pregnancy which was subsequently normal, we measured the maternal serum levels of estradiol (E2), progesterone (P4) and prolactin (PRL) as well as the diameter of gestational sac (GS) and the crown-rump length (CRL) of the embryo by transvaginal ultrasonography. The maternal serum level of E2 had the closest statistically significant correlation with both the GS diameter (r = 0.769, P < 0.01) and the CRL (r = 0.736, P < 0.001). P4 and PRL concentrations showed less correlation with embryo development.

Crown-Rump Length↗

Application of a new tactile sensor to thoracoscopic surgery: experimental and clinical study.

BACKGROUND: We developed a new tactile sensor that could quantify the hardness of objects as changes in the resonance frequency of the sensor (delta f). We have applied it to thoracoscopic operations for the localization of small invisible nodules in the lung. METHODS: When the sensor probe was moved over the lung surface, a delta f curve was depicted on the computer screen. When the sensor tip reached a point directly above a hard object, a sudden upward jump of the delta f curve was evoked. After experimental studies using pigs, the sensor was applied in 8 patients. More recently we produced a needle sensor to distinguish small nodules from bronchi that may evoke similar upward jumps of the delta f curve. Eight nodules and four bronchi in resected human lungs were probed directly using this sensor. RESULTS: In all of the patients, the hardness of various thoracic structures could be quantified. A total of 10 nodules were found using the sensor and resected thoracoscopically. The needle sensor distinguished nodules from bronchi, as the mean delta f of the bronchial walls (-64 +/- 45.9 Hz) was significantly higher than that of nodules (-526 +/- 168 Hz, p < 0.001). CONCLUSIONS: Thoracoscopic detection of small and invisible pulmonary nodules using our new tactile sensor is feasible.

Adenocarcinoma↗

Central nervous system disease in a child with primary Sjögren syndrome.

A 9-year-old girl had hemiparesis, and a diagnosis of primary Sjögren syndrome was made. The neurologic dysfunction was multifocal, involving both the brain and spinal cord, and was recurrent; the findings mimicked multiple sclerosis. Corticosteroid treatment during episodes of acute neurologic dysfunction appeared to be beneficial.

Brain↗

Image analysis of nailfold capillaries in patients with undifferentiated connective tissue syndromes.

Several studies have reported patients that show nailfold capillary abnormality without fulfilling any of the criteria for rheumatic diseases. Our objective was to define how many patients with undifferentiated connective tissue syndrome (UCTS) have nailfold capillary abnormalities and to determine the correlation between capillary abnormality and clinical findings. We analyzed videograph images of nailfold capillaries in 75 patients with UCTS, comparing them with 22 normal controls (NL) and 55 patients with systemic sclerosis (SS), using standardized canonical discriminant analysis. Sixty patients with UCTS showed the SS type pattern and 15, the NL type pattern. The SS type pattern in patients with UCTS significantly correlated with Raynaud's phenomenon, telangiectasia, and anti-nuclear antibody. The UCTS patients with nailfold capillary abnormalities correlated with symptoms of SS have a possibility of progressing to SS. The follow up study of these patients will show whether progression to SS occurs.

Adolescent↗

Effects of isoproterenol on the cardiovascular system of fetal sheep exposed to long-term high-altitude hypoxemia.

We exposed fetuses to high-altitude (3,820 m) hypoxemia from 30 to 130 days gestation, when we measured fetal heart rate, right and left ventricular outputs with electromagnetic flow probes, and arterial blood pressure during an isoproterenol dose-response infusion. We also measured the distribution of cardiac output with radiolabeled microspheres during the maximal isoproterenol dose. Baseline fetal arterial blood pressure was higher in long-term hypoxemic fetuses (50.1 +/- 1.3 vs. 43.4 +/- 1.0 mmHg) but fell during the isoproterenol infusion to 41.3 +/- 1.4 and 37.5 +/- 1.4 mmHg, respectively, at the highest dose. Heart rate was the same in both groups and did not differ during isoproterenol infusion. Baseline fetal cardiac output was lower in the hypoxemic group (339 +/- 18 vs. 436 +/- 19 ml.min-1.kg-1) due mainly to a reduction in right ventricular output. During the isoproterenol infusion, right ventricular output increased to the same extent in both hypoxemic and normoxic fetuses (approximately 35%); however, left ventricular output increased only approximately 15% in the hypoxemic group compared with approximately 40% in the normoxic group. The percent change in individual organ blood flows during isoproterenol infusion in the hypoxemic groups was not significantly different from the normoxic group. All of the mechanisms that might be responsible for the differential response of the fetal left and right ventricles to long-term hypoxia are not understood and need further exploration.

Altitude↗

Cardiac enzyme activities in fetal and adult pregnant and nonpregnant sheep exposed to high-altitude hypoxemia.

We measured pyruvate kinase (PK), citrate synthase (CS), and lactate dehydrogenase (LDH) activities in the right and left ventricles of fetal, maternal, and nonpregnant adult sheep exposed to high altitude (3,820 m) for 112 days and compared them with control groups of animals kept at sea level. Enzymes were assayed by the spectrophotometric appearance of reaction products specific to each enzyme, and activity was expressed as micromoles per minute per gram of wet weight of tissue. In control sheep, CS activity was significantly higher in both ventricles of the pregnant and nonpregnant adult compared with the fetus. However, LDH and PK activities were only higher in the left ventricle of the nonpregnant adult compared with the fetus. Long-term hypoxemia significantly increased LDH activities in fetal (57 and 53%), pregnant adult (29 and 27%), and non-pregnant adult (25 and 24%) right and left ventricles, respectively. CS activities also increased in fetal (90 and 97%), pregnant adult (43 and 39%), and nonpregnant adult (46 and 48%) right and left ventricles, respectively. However, PK activity was not affected by altitude in any group of animals. In the fetal heart, which uses lactate as its primary metabolic fuel, these enzyme changes may help enhance aerobic energy production during hypoxemia. In the adult heart, which relies on free fatty acids as well as glucose for energy production, the significance of these enzyme changes is less clear.

Altitude↗