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Biomedical subjects

K Fujimura

Publications and source records attributed to K Fujimura.

At least 37 records · Page 2Linked to original sources
PubMed1990

Rapid purification and characterization of human platelet glycoprotein V: the amino acid sequence contains leucine-rich repetitive modules as in glycoprotein Ib.

Glycoprotein V (GPV) is a membrane-associated, 82 Kd platelet glycoprotein that is hydrolyzed during thrombin activation to yield 69 Kd fragment. We have developed a rapid and simple method for isolation of the protein from platelet extracts using a combination of gel permeation, anion-exchange, and lectin affinity chromatography. The partial amino acid sequence was determined by analysis of peptides generated by digestion of the S-carboxyamido-methylated protein with Achromobacter protease I or cyanogen bromide. The sequence shows a remarkable periodicity of leucine residues, which is homologous to the consensus sequence of a highly diversified protein super-family with a common repetitive module. Thrombin cleavage site was determined to be located at the C-terminal region of GPV by analysis of the products separated by sizing and reversed-phase high performance liquid chromatography. By lectin blot analysis, the existence of mucin-type carbohydrate chains was indicated, as well as the existence of asparagine-linked carbohydrate chains shown by the amino acid sequence analysis. From these data, we report a structural model of GPV that is analogous to glycoprotein Ib.

Amino Acid Sequence↗
PubMed1990

Blastic transformation in essential thrombocythemia. In vitro differentiation of blast cells into granulocytic, erythroid, and megakaryocytic lineages.

A 57-year-old man with essential thrombocythemia (ET) developed myelofibrosis, that progressed to a blastic transformation state. The characteristics of the blastic cells were serially studied both morphologically and phenotypically as well as in cell culture. The blastic cells that were first detected in peripheral blood had features of myeloid stem cells with slight differentiation toward megakaryocytic lineage. However, later in the course, most of the blastic cells were immature. During culture in the presence of human plasma-derived serum (PDS), some blastic cells obtained at the initial stage differentiated, mainly to both granulocytes and macrophages morphologically, but later tended to differentiate into both megakaryocytes and macrophages. Finally the blasts appeared to have lost their ability to differentiate morphologically. However, the blasts formed mixed colonies consisting of erythroblasts, granulocytes, macrophages, and immature blasts when cultured in methylcellulose with PHA-leukocyte conditioned medium. In addition, the blastic cells in suspension culture strongly expressed phenotypic features which are characteristic of erythroblasts, in the presence of both PDS and 12-0-tetradecanoylphorbol 13-acetate (TPA), whereas they expressed features of megakaryoblasts in the presence of PDS alone. These results suggest that essential thrombocythemia is of myeloid stem cell origin. This is the first case in the literature in which a clonal evolution in ET has been followed closely, essential events were identified serially, and the blastic cells, which appeared as a result of the progression of ET, were found to have the capability to differentiate toward the three myeloid lineages.

Blast Crisis↗
PubMed1990

Analysis of platelet cytoskeleton assembly during platelet activation in Hermansky-Pudlak syndrome and thrombasthenia.

Time course change of the platelet cytoskeletal protein component in the Triton X-100 insoluble fraction after stimulation was analyzed in Hermansky-Pudlak syndrome and thrombasthenia. In Hermansky-Pudlak syndrome (HPS), a 31 kDa protein, myosin, actin, and a 100 kDa protein assembled as in the normal platelets at the shape change and release reaction phases after ADP or collagen stimulation, suggesting that, the deficient dense granule content do not lead to an abnormal platelet cytoskeletal protein assembly. In thrombasthenia (Type I), myosin increased at the shape change and release reaction phases as it does in normal platelets, but actin and the 100 kDa protein increased only at the initial activation phase, and then subsequently decreased to the level of the resting phase. The actin-binding protein (ABP) and the 31 kDa protein increased a little following stimulation. Similar cytoskeletal protein change after stimulation were found in normal platelets which were prevented from the aggregation process by chelating the external Ca2+ or by using synthetic decapeptide of fibrinogen gamma-chain of carboxyl terminus. The decreased platelet cytoskeletal protein assembly in thrombasthenia or in platelets stimulated without aggregation, was derived from a loss of the platelet aggregation process due to the defect of GP IIb-IIIa complex or an interaction failure between GP IIb-IIIa complex and fibrinogen. The interaction between platelets and either fibrinogen or fibrin can induce a more stable platelet cytoskeletal protein assembly, however, agonistic stimulation without these interactions cannot do it directly.

Actins↗
PubMed1990

Activities of new acridone alkaloid derivatives against Plasmodium yoelii in vitro.

Forty-seven new acridone alkaloid derivatives (SA compounds) were tested for antimalarial activity in vitro. At a concentration of 1.0 microgram/ml, six of these inhibited 50% or more of the incorporation of [3H]hypoxanthine into Plasmodium yoelii in vitro. The four most potent compounds, SA 3757, SA 3548, SA 3761 and SA 3499, showed 50% inhibitory concentration (IC50) values of 0.023 microgram/ml, 0.03 microgram/ml, 0.053 microgram/ml and 0.15 microgram/ml, respectively. The chemotherapeutic indexes of these four acridones, based on the ratio of the 50% lethal concentration (LC50) values for cell growth of L1210 cells to the IC50 for inhibition of uptake of [3H]hypoxanthine into P. yoelii, were calculated to be equal to or more higher (greater than 870, 263, 189 and greater than 133, respectively) than chloroquine diphosphate (315) or pyrimethamine (87).

Acridines↗
PubMed1989

Autogenous oscillatory potentials in neurons of the guinea pig substantia nigra pars compacta in vitro.

In spontaneously firing neurons of the guinea pig substantia nigra pars compacta (SNC) maintained in slices, blockade of the fast spikes by tetrodotoxin (TTX) revealed a slow oscillatory potential change, which was depressed by Cd2+, a Ca2+-channel blocker. The spontaneous firing was suppressed by the application of Ca2+-free saline, Cd2+ or Co2+, but not by nifedipine. These findings lend support to the view that the spontaneous firing of SNC neurons is produced by an intrinsic, Ca2+-dependent pacemaking process affected by Cd2+ but not by nifedipine.

Action Potentials↗
PubMed1989

Abnormal Ca2+ homeostasis in platelets of patients with myeloproliferative disorders: low levels of Ca2+ influx and efflux across the plasma membrane and increased Ca2+ accumulation into the dense tubular system.

Ca2+ influx and efflux in unstimulated platelets and Ca2+ uptake by simultaneously isolated two membrane fractions of platelets from patients with myeloproliferative disorders (MPD) have been investigated. In MPD, Ca2+ influx and efflux across the plasma membrane in unstimulated platelets were in equilibrium at significantly lower levels than in normals. Ca2+ uptake by external membrane fraction isolated from MPD platelets was lower, whereas, uptake by internal membrane fraction enriched with dense tubular system (DTS) from MPD platelets was significantly higher than that from normal platelets. This corresponded with the membrane associated Ca2+-activated ATPase activity. These abnormalities of calcium ion movement in plasma membrane and dense tubular system illustrates one of the mechanisms of qualitative abnormalities of MPD platelets.

Adenosine Triphosphatases↗
PubMed1989

Occurrence of platelet-activating factor (PAF) in normal rat stomach and alteration of PAF level by water immersion stress.

We detected platelet-activating substance in gastrointestinal areas, which was confirmed to be platelet-activating factor (PAF) on the basis of the following findings: 1) it comigrated with authentic PAF on thin-layer chromatography; 2) it did not aggregate PAF-desensitized platelets; and 3) its activity was completely antagonized by the receptor antagonists CV3988 and L-652,731. The level of PAF was determined with a bioassay method based on the release of [3H]serotonin from washed rabbit platelets. In the normal rat stomach, the level of PAF was high in the antrum (940 +/- 200 nmol PAF/mol phosphorus of original phospholipids), especially in the antral mucosa (1801 +/- 426 nmol/mol phosphorus of original phospholipids). The stomach PAF level was significantly altered by water immersion stress. Stress for a period of 1 h was associated with a decrease in the antral PAF level to 39 +/- 7% of that of untreated controls. This low PAF level persisted during stress. On the other hand, in the corpus, stress for periods of 1 and 3 h was associated with decreases in the PAF content, and further stress (7 h) resulted in restoration of the PAF level to normal. Furthermore, 7 h of stress was associated with distinct hemorrhagic lesions, which were prevented by CV3988 infused i.v. before the stress. This is the first report of an association between a decrease of the endogenous PAF level in animal tissues and tissue damage.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1989

Serum platelet-activating factor acetylhydrolase activity in rats with gastric ulcers induced by water-immersion stress.

Platelet-activating factor (PAF) acetylhydrolase is an enzyme which hydrolyzes PAF to yield inactive lysoPAF. This study focused on the influence of water-immersion stress on serum PAF acetylhydrolase activity. The enzyme activity was determined by measurement of [3H]acetate produced from 1-O-alkyl-2-[3H]acetyl-sn-glycero-3-phosphocholine upon precipitation of the complex of the radioactive substrate and albumin with trichloroacetic acid. The onset of water-immersion stress caused the development of gastric lesions associated with a significant increase in serum PAF acetylhydrolase activity. Serum PAF acetylhydrolase may leak into the blood from some tissues in rats with gastric injury induced by water-immersion stress and might control the action of PAF.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1989

[Arthrographic investigation for the disk configuration with closed lock of the temporomandibular joint].

The authors examined arthrotomographies of 89 patients (96 joints) with closed lock of the temporomandibular joint to clarify the frequency of disk deformity correlated with disk perforation, bone change and patients' age. The disk configurations were divided into 3 types, those were type-1-elongated and preserved shape of the disk, 39 joints, type 2-folded disk, 11 joints, and type 3-massed disk, 46 joints. The frequency of disk deformity was 66.7% (64 joints). The numbers of disk perforation, (and bone change) in each type were type 1-2 (5) joints, type 2-1 (1) joint, and type 3-11 (13) joints. The average ages of each type were type 1-28.1 years, type-2-27.2 years, and type 3-40.1 years. These results indicate that high percentage of disk deformations exist in the closed lock patients with degenerative changes of the soft and hard parts of the temporomandibular joint.

Adult↗
PubMed1989

[Correlation of the disk configuration with duration of illness and opening distance in patients with closed lock of the temporomandibular joint].

Classification of disk configuration for 96 joints (89 patients) of internal derangement with closed lock of the temporomandibular joint was performed by means of double-spacing contrast arthrotomography. The results of the classification were presented in the first report of this series. The disk shape was divided into 3 types; the first type-prolonged shape maintaining the main parts of the disk, the second type-folded disk, and the third type-massed disk. In this article, the authors tried to clarify the correlation of disk configuration with the duration of illness and with the interincisal opening distance at the first presentation. In the results, the average duration of clicking and locking was statistically longer in the joints of the third type. The interincisal opening distance was statistically smaller in the joints of the first type. These results indicate that the severity of the disk deformation is closely related to the duration of illness and to the joint function.

Cartilage, Articular↗
PubMed1989

[A case of refractory multiple myeloma demonstrating a relationship between the progression of the disease and in vitro myeloma cells activity].

In vitro proliferation (3H-TdR-uptake) and M-protein secretion rate by highly purified myeloma cells from bone marrow aspirates were examined serially to evaluate the progression of multiple myeloma in a patient who was refractory to conventional alkylating agents. Following the administration of IFN-alpha, serum M-protein decreased significantly, with the reduced in vitro spontaneous M-protein secretion rate from the separated myeloma cells. Similarly, when IFN-alpha as low as 10 u/ml was added in vitro, it also suppressed M-protein secretion from myeloma cells of this patient, suggesting that, the observed decrease of serum M-protein was due to diminished M-protein secretion by the myeloma cells themselves, as well as the reduction of the tumor cell burden. On the other hand the in vitro 3H-TdR uptake by the myeloma cells increased markedly with the decrease in the M-protein secretion rate. Five months after the initiation of IFN-alpha treatment, tumor formation at the lumbar vertebrae occurred when serum M-protein level was still low, followed by a bone marrow relapse. These results suggest that serial assessments of proliferation and M-protein secretion potential of myeloma cells in vitro can be helpful in predicting the progression of multiple myeloma.

Cell Division↗
PubMed1989

Acidified glycerol lysis test (AGLT) studies in Japan.

We investigated the usefulness of the acidified glycerol lysis test (AGLT) as a diagnostic tool for anemic patients in Japan. The results of the AGLT were found to be useful indicators of autoimmune processes and red cell membrane defects. When glycerol permeability was low and AGLT50 could not be determined, the reduction in optical density could be measured accurately by calculating the value during the first two minutes.

Anemia↗
PubMed1989

[Thrombotic thrombocytopenic purpura which was effectively treated by plasma exchange therapy--involvement of vWF and endothelial cell injury].

A 49-year-old man with a one-week history of general fatigue and several other symptoms, including hematuria, numbness of the mouth, anemia and thrombocytopenia, was admitted because of an episode of convulsions and unconsciousness after blood transfusion. A diagnosis of thrombotic thrombocytopenic purpura (TTP) was then made, and treatment with steroids, anti-platelet agents, transfusion of fresh frozen plasma was started. However, since no improvement was seen, on the third day of admission, treatment with plasma exchange was instituted (total plasma exchange volume was 18.1 iota), and his clinical and hematological conditions improved markedly. Since then, he has been in a remission state for about three years. Laboratory examinations during the acute phase showed increase of vWf: Ag, decrease of RCof/vWf: Ag, increase of vWf large multimers and a high endothelial cell injury activity by the patient's serum. In the next day following the plasma exchange therapy, RCof/vWf: Ag improved, but not to the normal range. One and a half years later, while in the remission phase, the vWf multimers and endothelial cell injury activity normalized. Thus, these findings show further evidence on the involvement of endothelial cell injury and vWf in the pathogenesis of TTP.

Endothelium, Vascular↗
PubMed1989

Abnormalities of calcium ion movement in platelets of patients with myeloproliferative disorders.

We investigated abnormalities in calcium ion influx in platelets of patients with myeloproliferative disorders (MPD). 45Ca2+ influx into the cytosol of MPD platelets was lower than that of normal controls. To determine whether the low Ca2+ influx is caused by a functional abnormality of membrane glycoprotein (GP) IIb-IIIa complex for Ca2+ channel or not, we investigated the Ca2+ influx through GP IIb-IIIa complex, which was reconstituted into liposomes. The purified GP IIb-IIIa complex from platelets of 5 patients was reconstituted into phospholipid liposomes. Ca2+ influx into the liposomes measured by fluorescence of intravesicular Fura-2 was lower in 2 of these patients. These findings corresponded with the results of intracellular calcium concentration after stimulation in these platelets. We concluded that functional abnormalities of GP IIb-IIIa is involved in the mechanism of impaired Ca2+ influx in MPD platelets.

Blood Platelets↗
PubMed1989

Progression activity for platelet-derived growth factor in plasma of patients with idiopathic thrombocytopenic purpura and aplastic anemia.

Progression activity for competence induced by platelet-derived growth factor (PDGF) was measured in plasma of patients with idiopathic thrombocytopenic purpura (ITP) and aplastic anemia (AA), in order to clarify the mechanism operating to maintain the wound healing system of these chronically thrombocytopenic patients. Progression activity in both ITP and AA patients was significantly higher than in normal subjects. There was a positive correlation between the activity and the duration of thrombocytopenia in AA patients who had thrombocytopenia for less than 100 months. The level of insulin like growth factor-I (IGF-I), which is a progression factor for PDGF, was lower in patients, than in normal controls. These results suggest that some plasma progression factor(s) for PDGF, other than IGF-I, plays an important role in maintaining the wound healing system of blood vessels in chronically thrombocytopenic patients.

Adolescent↗
PubMed1989

Low intracellular calcium concentration in the platelets after stimulation in patients with myeloproliferative disorders.

Intracellular calcium levels in the platelets of patients with myeloproliferative disorders (MPD) were measured by the Aequorin method. In the patients with MPD, the maximum intracellular calcium level [Ca2+]i was significantly lower and the time required to reach the peak calcium level was significantly longer than in normal controls after thrombin (0.5 U/ml) and collagen (2.5 micrograms/ml) stimulation. The rate of increase in intracellular calcium levels after thrombin (0.5 U/ml) stimulation in the presence of various concentrations of extracellular calcium was lower than in the normal controls, which suggests that the low level of intracellular [Ca2+]i after stimulation is caused mainly by a low Ca2+ influx. These results suggest the relationship between abnormalities of membrane glycoprotein and the impaired calcium influx of MPD platelets.

Blood Platelets↗
PubMed1989

[Multiple myeloma following chronic neutrophilia terminated with acute monocytic leukemia (AML, M 5 b)].

A case of a 70 years old female who developed multiple myeloma during a course of neutrophilia, and later on terminated with acute monocytic leukemia (AML, M 5 b) following Melphalan therapy for five years is reported. This patient was first found to have neutrophilia in 1966, After six years, she developed monoclonal gammopathy, (IgG1 kappa type) which coexisted with the neutrophilia. She was put on Melphalan regimen for 5 years which was discontinued due to anemia, leukocytopenia and the reduction of serum IgG. By routine bone marrow examination, she was diagnosed as AMoL (AML, M 5 b) in July 1984. Thereafter, a combination chemotherapy of BH-AC, 6-MP and prednisolone was started and complete remission for the AMoL was achieved after 2 months. Sixteen months later, she relapsed and a similar combination chemotherapy for reinduction regimen was administered. However, the AMoL was resistant and after 7 months, she died of pneumonia and multiple organ failure. The association of neutrophilia with multiple myeloma, the occurrence of AMoL after prolonged Melphalan therapy for the multiple myeloma and the strategy of therapy for secondary leukemia is discussed.

Aged↗