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Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 667 records · Page 37Linked to original sources
PubMed1994

Plasma lipoprotein (a) levels and fibrinolytic activity in acute myocardial infarction.

To evaluate the effects of lipoprotein (a) [Lp (a)] on the fibrinolytic system in patients with acute myocardial infarction (AMI) who underwent thrombolytic therapy with recombinant tissue-type plasminogen activator, we examined serial changes in plasma levels of Lp (a), plasminogen activator inhibitor (PAI) activity, alpha 2-plasmin inhibitor-plasmin complex (PIC) and thrombin antithrombin III complex (TAT) in venous plasma samples from 25 patients with AMI for 3 weeks. Plasma Lp (a) levels were significantly increased 5, 7, and 14 days after admission and tended to decrease by the 21st day. On the other hand, the ratio of PIC/TAT was significantly increased on the 7th day and remained high for 3 weeks (p < 0.01), while plasma PAI activity was significantly decreased on the 5th day after admission (p < 0.01). Thus, plasma fibrinolytic function is impaired in the early phase after AMI, and gradually improves over the course of 3 weeks. The increase in plasma Lp (a) levels is, therefore, not accompanied by a significant decrease in plasma fibrinolytic function in patients with AMI.

Aged↗
PubMed1994

Purification, characterization, and production of two pectic transeliminases with protopectinase activity from Bacillus subtilis.

We found two enzymes that solubilize pectin from protopectin, tentatively named protopectinase-N (PPase-N) and protopectinase-R (PPase-R), in a culture filtrate of Bacillus subtilis IFO 3134. These enzymes were purified to homogeneity by hydrophobic, cation exchange and size exclusion chromatographies. The molecular weights of PPase-N and PPase-R were estimated to be 43,000 and 35,000, respectively, by SDS-PAGE. Their pIs were 9.4 and 8.2, respectively. These enzymes were stable in a wide range of pH and temperature. PPase-N and -R released water-soluble pectin by transeliminative cleavage of protopectin. According to their substrate specificities and modes of action, PPase-N and PPase-R could be classified as endo-pectate transeliminase (pectate lyase; EC 4.2.2.2) and endo-pectin transeliminase (pectin lyase; EC 4.2.2.10), respectively. Both enzymes were produced in a simple medium containing defatted soybean flour and phosphates. Production of PPase-N was repressed by addition of glucose while that of PPase-R was enhanced by phosphate.

Amino Acid Sequence↗
PubMed1994

Adhesive interaction between lymphocytes and sinusoidal liver cells.

Since sinusoidal liver cells directly interact with circulating hemopoietic cells and lymphocytes, Kupffer cells may have the capacity to trap and activate these cells in the liver microcirculation. In order to investigate the adhesion mechanism of Kupffer cells to other lymphoid cells, mouse sinusoidal liver cells were isolated by a collagenase perfusion followed by differential centrifugations. By in vitro adhesion assay of lymphocytes to sinusoidal liver cells and staining of adhered lymphocytes with FITC/peroxidase labeled peanut agglutinin (PNA), the following observations were made: 1) Lymphocytes from various lymphoid organs including the liver itself adhered to Kupffer cells. 2) After an incubation period, DNA synthesis of the adhered lymphocytes increased. 3) A high percentage of the adhered lymphocytes were PNA+ cells. 4) D-Galactose, a PNA specific carbohydrate, inhibited the lymphocyte binding and the total DNA synthesis of the adhered lymphocytes decreased proportionally with their decrease in number. Our results suggest that sinusoidal liver cells may have the ability to trap and to activate PNA+ cells.

Animals↗
PubMed1994

Infectivity of three species of Fasciola to Wistar rats.

The infectivity of Fasciola spp. to Wistar rats was evaluated with the recovery rate and development of flukes. The recovery rate from the liver parenchyma and bile duct was 20.0-30.0% in F. hepatica, 36.6-47.5% in Japanese Fasciola sp. and 0-5.0% in F. gigantica. Mature flukes were first recovered at week 8 in F. hepatica and week 12 in Japanese Fasciola sp., however, F. gigantica did not mature in the rats examined until 12 weeks after infection. These results suggest that F. hepatica and Japanese Fasciola sp. are high in infectivity to Wistar rats, whereas F. gigantica is low.

Animals↗
PubMed1994

Localized pleural mesothelioma with elevation of high molecular weight insulin-like growth factor II and hypoglycemia.

Recurrent hypoglycemia occurred in a 48-year-old woman with a localized pleural mesothelioma. During hypoglycemia, serum high molecular weight insulin-like growth factor II (IGF-II) was elevated. The tumor also contained a high level of high molecular weight IGF-II. We propose that the primary cause of the hypoglycemia in this patient was the high molecular weight IGF-II produced by the tumor.

Female↗
PubMed1994

Combination of ascorbic acid and methylprednisolone pulse therapy in the treatment of idiopathic thrombocytopenic purpura.

Ascorbic acid, reported in 1988 to be effective for idiopathic thrombocytopenic purpura (ITP), is an attractive drug because of its lack of toxicity. Further studies are necessary in order to improve its effectiveness without increasing secondary effects. We present a chronic ITP patient treated with a combination of ascorbic acid and methylprednisolone pulse (MP) therapy who was previously treated with MP therapy alone. The effect of this combination therapy seems to be better than MP therapy alone. This therapy is worth further examination as another therapeutic choice due to its fewer secondary effects than the usual regimen of corticosteroids, splenectomy, and other immunosuppressive drugs.

Aged↗
PubMed1994

Fatal respiratory failure due to polymyositis.

A patient presenting as severe respiratory failure due to alveolar hypoventilation resulting from respiratory muscle weakness is described. Diagnosis of polymyositis was established by electromyography and muscle biopsy. Steroid therapy was initiated and it ameliorated respiratory failure remarkably. Selective respiratory muscle involvement due to polymyositis has been suggested in this patient. Although fatal respiratory failure is a very rare complication in polymyositis, polymyositis should be considered as one of underlying diseases causing severe respiratory failure.

Fatal Outcome↗
PubMed1994

Pigmentary retinopathy with nephrotic syndrome, Ménétrier's disease, and diabetes mellitus.

A patient with pigmentary retinopathy, nephrotic syndrome, Ménétrier's disease, and diabetes mellitus is presented. Other complications were congestive heart failure, hypothyroidism, hypertension, and hypertriglyceridemia. Hypogenitalism was also suspected. Pigmentary retinopathy is known to associate with many systemic diseases, which are classified into several syndromes. This case superficially resembles Alström's disease due to the common characteristics of pigmentary retinopathy, diabetes mellitus, renal disease, and hypogenitalism. But clinically and histologically, there are distinct differences. To our knowledge, this association has never been reported.

Consanguinity↗
PubMed1994

Pituitary adenoma invading the skull base--a strategy for skull base surgery.

A strategy for surgical management, including the approach and preoperative evaluation, of pituitary adenoma invading the skull base is described. Preoperative evaluation requires a balloon occlusion test of the internal carotid artery (ICA) to determine tolerance to occlusion. Failure to tolerate occlusion indicates administration of brain protective agents and/or a bypass procedure before tumor removal. The transsphenoidal, pterional, orbitofrontomalar, and infratemporal fossa approaches are all suitable for various tumor locations. A combined orbitofrontomalar and extended frontal approach allows removal of tumor with extensive invasion and is suitable for bypass procedures. Preoperative evaluation of ICA occlusion can prevent development of hemodynamic stroke. We treated five patients with pituitary adenoma invading the skull base, including two primary and three recurrent cases. All symptoms improved, but temporary oculomotor nerve disturbance occurred in three patients and anosmia in one. Reoperations for recurrent pituitary adenomas were effective in reversing the symptoms. No hemodynamic stroke was seen postoperatively. These tumors, except for drug-responsive cases, are indicated for skull base surgery.

Adenoma↗
PubMed1994

Accurate contiguous sections without breath-holding on chest CT: value of respiratory gating and ultrafast CT.

OBJECTIVE: To image truly contiguous CT sections without breath-holding, we developed a respiratory-gating device combined with ultrafast CT. The purpose of this study was to evaluate the utility of this system, especially focusing on the contiguity of the images. SUBJECTS AND METHODS: In 37 patients, we obtained respiratory-gated scans and breath-hold scans with 6-mm collimation and 6-mm incrementation (19 patients) and with 3-mm collimation and 3-mm incrementation (18 patients). We compared these two sets of images with respect to quality and contiguity. In nine patients who could not hold their breath because of dyspnea or infancy, we obtained only respiratory-gated scans with 3-mm collimation and 3-mm incrementation. Our respiratory-gating device was composed of a commercial ECG and respiratory monitor, a triggering device, an original amplifier, and an original switching unit. It was designed to control the scan timing of an ultrafast CT scanner at a user-selected level of the respiratory curve obtained with transthoracic impedance plethysmography. RESULTS: The respiratory-gated images were equal in quality to the breath-hold images in 31 of the 37 patients who had both sets of images. In 15 of 19 patients who had 6-mm-thick sections and in 11 of 18 patients who had 3-mm-thick sections, satisfactory contiguous images of bronchi and pulmonary vessels were obtained. Additionally, in seven of the nine patients who could not hold their breath, satisfactory contiguous sections were obtained. CONCLUSION: The respiratory gating system combined with ultrafast CT can provide contiguous CT scans without breath-holding or patients' cooperation. The procedure could improve the diagnostic accuracy of CT, especially in severely ill patients, infants, and senile patients.

Female↗
PubMed1994

Clinical evaluation of severe ischemic limbs by tissue reflection spectrophotometry.

The clinical usefulness of tissue reflection spectrophotometry in the prognosis of ischemic limbs was evaluated. The diseased group (n = 12) consisted of 7 cases of femoral artery thrombosis, 4 cases of chronic obstructive arteriosclerosis and 1 case of femoral vein thrombosis. The normal control group consisted of 14 limbs in 7 normal subjects (n = 14). Index of tissue hemoglobin concentration (IHb) was 37.3 +/- 4.5 (n = 14) in the normal control group and 38.5 +/- 16.9 (n = 12) in the diseased group, which was not significantly different. In a subgroup of patients who required amputation or developed necrosis (severe subgroup), the value was 54.2 +/- 1.7 (n = 6). This was significantly higher than the value of 22.8 +/- 8.5 (n = 6) obtained in a subgroup of patients who received the conservative treatment of thrombectomy (mild subgroup) (p < 0.05). Index of tissue oxygen saturation (ISO2) was 28.0 +/- 4.9 (n = 14) in the normal control group, and 9.1 +/- 2.7 (n = 12) in the diseased group (p < 0.05). ISO2 was 7.0 +/- 1.6 (n = 6) in the severe subgroup which was significantly lower than 11.2 +/- 1.9 (n = 6) in the mild subgroup (p < 0.05). Tissue reflection spectrophotometry therefore appears to provide clinically useful information for the prognosis of ischemic limbs.

Adult↗
PubMed1994

Collagen gel contraction induced by retinal pigment epithelial cells and choroidal fibroblasts involves the protein kinase C pathway.

Contraction of intraocular fibrous membranes is an important feature in the pathogenesis of retinal detachment in proliferative vitreoretinopathy (PVR). Collagen gel contraction is a useful in vitro model of membrane contraction in PVR. We studied the role of protein kinase C (PKC) in collagen gel contraction induced by bovine choroidal fibroblasts and retinal pigment epithelial (RPE) cells. Collagen gels embedded with the cells were formed in culture dishes and gel contraction was evaluated. The PKC stimulator, phorbol 12-myristate 13-acetate (PMA), and the protein phosphatase 1 and 2A inhibitor, okadaic acid (OA), were used to evaluate the role of the PKC-mediated phosphorylation system in this gel contraction. Fifteen min incubation with PMA stimulated gel contraction, but 180 min incubation had no effect. Choroidal fibroblast- but not RPE cell-induced gel contraction was stimulated by OA. These effects were inhibited by the broad spectrum protein kinase inhibitor staurosporine and the specific PKC antagonist calphostin C. Transforming growth factor-beta (TGF-beta)1 and TGF-beta 2, which are known to be present in eyes with PVR, were evaluated to determine their effect on gel contraction. Both TGF-beta 1 and 2 had a stimulatory effect on contraction of gels seeded with choroidal fibroblasts and RPE cells, but staurosporine and calphostin C inhibited this TGF-beta-induced gel contraction. These results indicate that activation of PKC/protein phosphorylation is an important factor in gel contraction caused by choroidal fibroblasts and RPE cells, and that TGF-beta-induced gel contraction is mediated at least in part via the PKC pathway.

Animals↗
PubMed1994

Lack of renal dopamine production during acute volume expansion in Dahl salt-sensitive rats.

Endogenous kidney dopamine (DA) is reported to contribute to the natriuretic response to acute volume expansion (VE). Several studies suggest that a defect in renal DA-ergic system may play a role in genetic hypertension in humans and rats. The present study was performed to determine the role of renal DA and tubular DA-1 receptors in the natriuretic response to VE in age-matched inbred Dahl salt sensitive (SS/Jr) and salt resistant (SR/Jr) rats of 9-11 weeks of age. In pentobarbital anesthetized rats, VE was carried out by intravenous infusion of isotonic sodium chloride (5% body weight) over a period of 60 min. This maneuver evoked marked increases in urine output and urinary sodium excretion in both SR/Jr and SS/Jr species. However, the natriuretic and diuretic response to VE was significantly reduced in SS/Jr as compared to SR/Jr rats. It was also observed that the urinary excretion of DA was significantly increased during VE only in SR/Jr, but not in SS/Jr rats. In separate group of animals, infusion of DA (1 microgram/kg/min) produced similar increases in urine output and urinary sodium excretion without causing any alterations in blood pressure or heart rate in either SS/Jr or SR/Jr rats. These results suggest that SS/Jr rats are not able to eliminate an acute increase in sodium load as efficiently as SR/Jr, which may be partly due to an impaired endogenous kidney DA production.

Animals↗
PubMed1994

Redistribution of alpha-granule membrane glycoprotein IIb/IIIa (integrin alpha IIb beta 3) to the surface membrane of human platelets during the release reaction.

Treatment of human washed platelets with 5 mM EDTA at 37 degrees for 60 min irreversibly dissociated glycoprotein (GP) IIb/IIIa complex (alpha IIb beta 3 integrin) on the surface membrane, since transmission immunoelectron microscopy studies demonstrated that these EDTA-pretreated platelets in the presence of added Ca2+ ion could not bind P2, an anti-GPIIb/IIIa complex-specific monoclonal antibody, to their surface membrane. The treatment, however, had no effect on the GPIIb/IIIa complex on the alpha-granule membrane. At 30 sec after the EDTA-pretreated platelets were activated with 0.1 U/ml of thrombin, alpha-granules fused with each other or with the surface-connected canalicular system (SCCS) to form swollen SCCS, the membrane of which was found to have the intact GPIIb/IIIa complex detectable by P2. In addition, at this time the intact GPIIb/IIIa complex reappeared on the surface membrane. At 5 min, the intact GPIIb/IIIa complex increased on the surface membrane with a reciprocal decrease or disappearance on the membrane of the swollen SCCS. The observation under scanning immunoelectron microscopy also confirmed the same translocation of the intact GPIIb/IIIa complex. These results indicate that alpha-granule membrane GPIIb/IIIa is redistributed to the surface membrane via the membrane of SCCS during the release reaction.

Blood Platelets↗