Search PubMed⌕ Search

Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

At least 883 records · Page 49Linked to original sources
PubMed1985

High-frequency oscillatory ventilation and pulmonary extravascular water.

The lungs of anesthetized rabbits were embolized by intravenous injection of 75 mg/kg of starch particles in divided doses. One group received high-frequency oscillatory ventilation (HFOV) at a rate of 15 Hz. Both groups were ventilated with an FIO2 of 1.0. After 3 hr of ventilation, the animals were sacrificed, and the extravascular lung water (EVLW) was determined gravimetrically. With conventional mechanical ventilation (CMV), the EVLW/body weight ratio was 4.1 +/- 1.4 g/kg (mean +/- SD) and was significantly higher than the ratio of 2.8 +/- 0.6 in animals given HFOV (P less than 0.05). In a second series of animals, 20 muCi of 125I-labeled bovine albumin was injected intravenously prior to embolization and followed by the same two types of ventilation. After the rabbits were sacrificed, the lungs were lavaged with 0.9 N saline, and the radioactivity of the fluid was measured to determine the protein leak. After CMV, 2.76 +/- 2.05% of the injected radioactivity was recovered from the fluid, significantly higher (P less than 0.01) than the amount of radioactivity recovered after HFOV, 0.3 +/- 0.28%. There also was significantly more labeled protein in the lung tissue that had been on CMV. We conclude that in this model of pulmonary edema, HFOV significantly reduces both the amount of fluid and protein leaking into the lung.

Animals↗
PubMed1985

[Fusiform aneurysm of the anterior cerebral artery (A1 segment)--a case report].

A very rare case of fusiform aneurysm of A1 segment of the anterior cerebral artery is reported. A 54-year-old man was admitted with dull headache and speech disturbance for 6 days before admission. CT scan revealed hypertensive subcortical small hemorrhage in the left temporal lobe. Angiography showed no vascular lesion concerning to the subcortical hemorrhage in the left temporal lobe, but showed a spherical aneurysmal dilatation in the left A1 segment of the anterior cerebral artery. At operation a fusiform aneurysm of the left A1 segment was confirmed. The aneurysm was obliterated, and new parent artery was reconstructed using a curved and a straight Yasargil aneurysm clips. The postoperative course was uneventful. Surgical treatment should be directed toward exclusion of large fusiform aneurysm and arteriosclerotic saccular aneurysm from cerebral circulation.

Carotid Arteries↗
PubMed1984

Induction of human gamma interferon by Sarcophaga peregrina humoral lectin.

Humoral lectin isolated from the hemolymph of injured Sarcophaga peregrina (flesh-fly) larvae was found to activate human peripheral blood cells to produce interferon activity. This interferon was inactivated by dialysis against a solution of pH 2.0 and by heat treatment at 56 degrees C for 30 min, indicating that it was a gamma interferon. The role of this lectin in the defence mechanism is discussed from the viewpoint of comparative immunology.

Animals↗
PubMed1984

Chemical modification of islet-activating protein, pertussis toxin. Essential role of free amino groups in its lymphocytosis-promoting activity.

Chemical modification of amino groups in the molecule of islet-activating protein (IAP), pertussis toxin, resulted in differential modification of biological activities of the toxin estimated in vivo with rats. Acetamidination of epsilon-amino groups of 50% (or more) of lysine residues in the IAP molecule totally abolished the lymphocytosis-promoting activity, but exerted no effects on the epinephrine-hyperglycemia inhibitory activity, of the toxin. Both activities were abolished by acylation of 50% or more of the amino groups probably due to the destruction of the toxin's quarternary structure. In contrast, the subunit assembly of IAP was maintained after exhaustive acetamidination of its lysine residues. The ADP-ribosyltransferase (or NAD-glycohydrolase) activity of the A-promoter (the biggest subunit) of IAP, which is responsible for the principal action of the toxin, enhancing insulin secretory responses and thereby inhibiting epinephrine hyperglycemia, was not affected by acetamindination of lysine residues. Thus, the A-protomer moiety of IAP is not directly involved in, but the amino groups of lysine residues in other subunits are selectively essential for, the development of the toxin-induced lymphocytosis.

Acylation↗
PubMed1984

Dual mechanisms involved in development of diverse biological activities of islet-activating protein, pertussis toxin, as revealed by chemical modification of lysine residues in the toxin molecule.

Islet-activating protein (IAP), pertussis toxin, is an oligomeric protein composed of an A-protomer and a B-oligomer. There seem to be at least two molecular mechanisms by which IAP exerts its various effects in vivo and in vitro. On the one hand, some of the effects were not significantly affected by acetamidination of the epsilon-amino groups of the lysine residues in the molecule. These include the activities in vitro (1) catalyzing ADP-ribosylation of one of the membrane proteins directly, (2) enhancing membrane adenylate cyclase activity in C6 cells, (3) reversing receptor-mediated inhibition of insulin or glycerol release from pancreatic islets or adipocytes, respectively, and the activities in vivo (4) inhibiting epinephrine-induced hyperglycemia, (5) potentiating glucose-induced hyperinsulinemia, (6) reducing hypertension and increasing the heart rate in genetically hypertensive rats. These activities are concluded to develop as a result of ADP-ribosylation catalyzed by the A-protomer which is rendered accessible to its intramembrane substrate thanks to the associated B-oligomer moiety. Thus, neither the enzymic activity of the A-protomer nor the transporting activity of the B-oligomer needs free amino groups of the lysine residues in the IAP molecule. On the other hand, additional effects of IAP, such as (1) mitogenic, (2) lymphocytosis-promoting, (3) histamine-sensitizing, (4) adjuvant and (5) vascular permeability increasing, were markedly suppressed by acetamidination of the intrapeptide lysine residues. The free epsilon-amino group of lysine would play an indispensable role in the firm (or divalent) attachment of the B-oligomer of IAP to the cell surface that is responsible for development of these activities.

Adenosine Diphosphate Ribose↗
PubMed1984

Clinical pathology of malignant meningiomas.

Nineteen cases of malignant meningiomas-seven haemangiopericytic, two papillary and ten of the anaplastic type-were examined clinicopathologically. These were ten male and nine female patients and eleven of these received reoperation for recurrence. Tumours of the hemangiopericytic type had similar angiographic and macrooscopic features and malignant characteristics were found microscopically in some tumours. There were intratumoral cysts in both cases of the papillary type and these tumours had a high cellularity, an increased number of mitosis, haemorrhage and partially haemangiopericytic patterns. Six cases of the anaplastic type had changed from a benign type at recurrence and those tumours had variable features radiographically and macroscopically. Lack of typical arrangement, a large number of mitoses, increased cellularity, focal necrosis, brain infiltration, pleomorphism and anaplasia were found histologically. Four cases of the anaplastic type were diagnosed at the first operation and these tumours had apparently similar angiographic and macroscopic features, but with variable organoid structures and malignant forms, microscopically. Electron microscopic features are also described. In malignant meningiomas, the recurrence rate was high even in cases of total removal. The outcome for these patients was good in the papillary type, relatively good in the haemangiopericytic type and poor in the anaplastic type. From these results therapeutic indications are also suggested.

Adult↗
PubMed1984

Attenuation values of chronic subdural haematoma and subdural effusion in CT scans.

When peripheral blood is serially diluted with saline solution, the bloody colour is determined by the derivative of haemoglobin. Solutions over 10(5)/mm3 red cells or 0.5 g/dl haemoglobin are represented as being sanguineous. This is the lower limit for a subdural haematoma, because the name itself requires at least a bloody appearance of its contents. Diluted blood solutions less 0.5 X 10(4) red cells or 15 mg/dl haemoglobin are macroscopically translucent or watery clear. Solutions between bloody and translucent are xanthochromic. If the contents of a subdural collection is watery clear or xanthochromic, it must be called an effusion or hygroma. The haemoglobin in haematomas is the most important factor determining the attenuation values in the CT scan. Protein, iron or calcium ions have only minimal concentration in haematomas and are negligible for attenuation values of haematomas in the CT scan. The lightest sanguineous solution, that is a haematoma, corresponds to 15 Hounsfield's units measured by the CT scan.

Chronic Disease↗
PubMed1984

Topographic analysis of the redox state of rat brain by NADH fluorescence photography of cross sections.

Two-dimensional changes of the redox level of NADH were measured by fluorescence photography with the aid of computer-processing in cross sections of rat brain that had been frozen in situ in liquid nitrogen. Structure-related heterogeneity was noted in the distribution of the redox level in normal brain of conscious rats. Using 2-deoxy-[14C]glucose autoradiography, the area showing relatively high NADH fluorescence was found to be the area of high glucose utilization. Quantitatively, however, the fluorescence intensity did not parallel the rate of glucose uptake. Increase of NADH fluorescence was observed specifically in the nucleus caudatus putamen and the thalamus when the rats were anesthetized with pentobarbital. Chemical determination of the NADH content was also performed simultaneously, and the results were consistent with those obtained by fluorescence photography.

Animals↗
PubMed1984

The effect of K+ concentration on the energy metabolism in perfused rat heart.

From experiments at various perfusion pressures in hemoglobin-free perfused rat hearts, oxygen consumption and redox shift of pyridine nucleotide were found to vary linearly with cardiac work. This relation was used for analysis of the energy metabolism associated with ion pumps. Mechanical activities such as left ventricular pressure and heart rate varied with the extracellular K+ concentration. Ion-pump dependent changes in oxygen consumption and redox state of pyridine nucleotide, estimated as the difference of the values at normal (4.7 mM) and various other extracellular K+ concentrations with corrections for the change due to mechanical work, were found to vary linearly with the K+ concentration. The slope for oxygen consumption was about 0.1 mumol/min/g X wet wt per mM K+. Lactate release changed markedly but transiently, about 1 min after changing the extracellular K+ concentration, and its amount varied linearly with the K+ concentration. In the steady state, however, lactate release was almost independent of the extracellular K+ concentration, although oxidized pyridine nucleotide increased with increasing K+ concentration. Coronary flow increased with the extracellular K+ concentration. Heart rate changed little between 1 and 12 mM K+, but decreased sharply above 12 mM K+. At 20 mM K+, heart beat was arrested and approximately 40% of myoglobin was deoxygenated. The intracellular oxygen concentration was estimated to be about 10 microM even during aerobic perfusion. Similarly, Ca2+-free arrested heart was found to be in a hypoxic state. The results showed that oxygen entry into cardiac tissue is facilitated by the cardiac cycle.

Animals↗
PubMed1984

Amino acid sequence of NADH-cytochrome b5 reductase of human erythrocytes.

The amino acid sequence of soluble NADH-cytochrome b5 reductase purified from normal human erythrocytes was determined as one approach to understand the hereditary disease of a deficiency of this enzyme. The protein is hydrophilic as a whole, but two regions, from Phe-36 to Ile-71 and from Met-231 to Phe-275, were found to be highly hydrophobic. The sequence of the latter region is particularly unique, and rich in proline (20%). The sequence of the amino-terminal region was very similar to the partial sequences of the corresponding regions of the enzymes from pig and steer liver microsomes.

Amino Acid Sequence↗
PubMed1984

Malignant lymphoma, small non-cleaved, non-Burkitt's type.

An autopsy case of "Malignant lymphoma, small non-cleaved, non-Burkitt's type" with hypercalcemia is presented. A 57-year-old Japanese man suffering from epigastralgia and "retroperitoneal tumor" for nine months was found at autopsy to have two large tumor masses in the retroperitoneum and pelvic cavity. Tumor cell infiltration into the liver, spleen, both kidneys, and both adrenal glands was observed on microscopic examination. The tumor cells were lymphoid cells with the characteristics of "Malignant lymphoma, small non-cleaved, non-Burkitt's type". The importance of recognizing non-Burkitt's type is pointed out. The cause of the presence of hypercalcemia is also discussed.

Autopsy↗