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Biomedical subjects

T Kuwaki

Publications and source records attributed to T Kuwaki.

At least 73 records · Page 4Linked to original sources
PubMed1990

Structural analysis of the receptors for granulocyte colony-stimulating factor on neutrophils.

We investigated granulocyte colony-stimulating factor (G-CSF) receptors on neutrophils from three patients with chronic myelogenous leukemia (CML) in the chronic phase, in comparison with four normal volunteers. Because we experienced some difficulties in radioiodinating intact recombinant human G-CSF, we developed a new derivative of human G-CSF termed YPY-G-CSF. It was easy to iodinate this protein using the lactoperoxidase method because of two additional tyrosine residues, and its radioactivity was higher than that previously reported. The biological activity of YPY-G-CSF as G-CSF was fully retained. Scatchard analysis demonstrated that CML neutrophils had a single class of binding sites (1400 +/- 685/cell) with a dissociation constant (Kd) of 245 +/- 66 pM. The number of sites and Kd value of CML neutrophils were not significantly different from those of normal neutrophils (p greater than 0.9). Cross-linking studies revealed two specifically labeled bands of [125I]YPY-G-CSF-receptor complexes with apparent molecular masses of 160 and 110 kd on both normal and CML neutrophils. This is the first report describing two receptor proteins on neutrophils. According to the analyses of the proteolytic process of these cross-linked complexes and proteolytic mapping, we assume that alternative splicing or processing from a single gene may generate two distinct receptor proteins that bind specifically to G-CSF but have different fates in intracellular metabolism.

Adult↗
PubMed1989

Characterization of human interleukin-3 receptors on a multi-factor-dependent cell line.

Recombinant human interleukin-3 (hIL-3) was radioiodinated by Bolton-Hunter method with maintenance of biological activity. Using 125I-hIL-3, hIL-3 receptors were characterized on a multi-factor-dependent cell line TF-1. Equilibrium binding studies revealed the existence of a single class of binding sites (667 +/- 306 sites/cell) with a Kd of 173 +/- 25 pM. Affinity labeling of TF-1 cells with 125I-IL-3 yielded two bands of 150 kDa and 85 kDa, implying molecular weights of 135 kDa and 70 kDa for the hIL-3 receptors.

Cell Line↗
PubMed1989

Establishment and characterization of a unique human cell line that proliferates dependently on GM-CSF, IL-3, or erythropoietin.

We have established a novel cell line, designated as TF-1, from a patient with erythroleukemia, which showed complete growth dependency on granulocyte-macrophage colony-stimulating factor (GM-CSF) or on interleukin-3 (IL-3) and carried a homogeneous chromosomal abnormality (54X). Erythropoietin (EPO) also sustained the short-term growth of TF-1, but did not induce erythroid differentiation. These three hematopoietic growth factors acted on TF-1 synergistically. Transforming growth factor-beta and interferons inhibited the factor-dependent growth of TF-1 cells in a dose-dependent fashion, and monocyte-colony stimulating factor and interkeukin-1 enhanced the GM-CSF-dependent growth of TF-1. Ultrastructural studies revealed some very immature features in this cell line. Although TF-1 cells do not express glycophorin A or carbonyl anhydrase I, the morphological and cytochemical features, and the constitutive expression of globin genes, indicate the commitment of TF-1 to erythroid lineage. When induced to differentiate, TF-1 entered two different pathways. Specifically, hemin and delta-aminolevulinic acid induced hemoglobin synthesis, whereas TPA induced dramatic differentiation of TF-1 into macrophage-like cells. In summary, TF-1 is a cell line of immature erythroid origin that requires GM-CSF, IL-3, or EPO for its growth and that has the ability to undergo differentiation into either more mature erythroid cells or into macrophage-like cells. TF-1 is a useful tool for analyzing the human receptors for IL-3, GM-CSF, and EPO or the signal transduction of these hemopoietic growth factors.

Adult↗
PubMed1989

Nilvadipine attenuates ischemic degradation of gerbil brain cytoskeletal proteins.

We have previously demonstrated that transient cerebral ischemia induces marked decreases in concentrations of cytoskeletal proteins and have suggested putative involvement of calpain in the decrease of microtubule-associated protein 2 (MAP2) content. We examine the effect of nilvadipine, a new calcium channel blocker, on protein degradation in gerbil brains after 5 minutes of bilateral carotid artery occlusion and compare this effect with those of nimodipine and nicardipine. By densitometric quantification of the electrophoretically separated soluble proteins, mean +/- SEM MAP2 content in the hippocampus (14.4 +/- 1.8 micrograms/mg protein) was depleted (5.4 +/- 0.5 micrograms/mg, p less than 0.01) 4 days after ischemia; this depletion was significantly inhibited by 1 or 10 mg nilvadipine/kg/day. MAP2 content was also depleted in vitro when normal nonischemic brain extract was incubated with calcium, but this degradation was not inhibited by the calcium channel blockers. Our results suggest that calcium channel blockers do not act directly on calpain but act at the calcium channels of neurons and may suppress activation of the enzyme and attenuate ischemic degradation of cytoskeletal protein. We found nilvadipine to be the most potent drug among those studied, and we believe it could be useful for the treatment of cerebral ischemia.

Animals↗
PubMed1989

Identification and analysis of human erythropoietin receptors on a factor-dependent cell line, TF-1.

We have recently established a novel cell line, TF-1, from bone marrow cells of a patient with erythroleukemia, that showed an absolute growth dependency on each of three hematopoietic growth factors: erythropoietin (EPO) granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin 3 (IL-3). EPO stimulated the proliferation of TF-1 cells even at the physiologic concentration (0.03 U/mL). We performed binding experiments on TF-1 cells using radioiodinated EPO. The binding of radioiodinated EPO to TF-1 was specific, time- and temperature-dependent, and saturable. Scatchard analysis of the saturation binding data suggested the existence of a single class of binding sites (kd = 0.40 nmol/L; number of binding sites = 1,630 per cell). TF-1 cells were usually maintained in RPMI 1640 containing 10% fetal bovine serum and 5 ng/mL GM-CSF. The kd and the number of the EPO receptors were not changed by incubating the cells with IL-3, although culturing the cells in the presence of EPO resulted in down-modulation of EPO receptors. The chemical cross-linking study demonstrated that two molecules with apparent molecular weights of 105 kilodalton (Kd) and 90 Kd were the binding components of EPO. Present data suggest that human EPO receptors are very similar to the previously reported murine EPO receptors.

Cell Division↗
PubMed1989

[Acetylcholinesterase activity in CSF in senile dementia of Alzheimer type, vascular dementia, and Parkinson's disease].

Acetylcholinesterase (AChE) activity was measured in cerebrospinal fluid (CSF) from 25 patients with senile dementia of Alzheimer type (SDAT), 11 patients with vascular dementia (VD), 26 patients with Parkinson's disease (PD), and 30 normal controls. AChE activity also was measured in 46 normal subjects whose ages ranged from 15 to 85 to evaluate the effect of age on AChE activity. CSF AChE activity for the SDAT, VD and PD groups showed no significant difference compared with the value for the control group. However, there were significant decreases in CSF AChE activity in the VD and PD groups with the development of ventricular enlargement. There was no significant correlation between CSF AChE activity decrease and ventricular enlargement in the SDAT group. AChE activity increased significantly over the age range of 15 to 85. These results suggest that, although CSF AChE activity is not a useful parameter in the diagnosis of dementia, it may be a marker indicating abnormalities of the intracerebral cholinergic system during the process of cerebral atrophy.

Acetylcholinesterase↗
PubMed1988

Effects of acetyl-L-carnitine on the brain lipofuscin content and emotional behavior in aged rats.

The effects of long-term dosing with acetyl-L-carnitine (ALC) were examined in aged rats, and they were compared with those in young rats. ALC significantly reduced the lipofuscin deposition in the brain of aged rats. Emotional parameters such as locomotor activity and rearing behavior are lower in aged rats than in young rats, and these behaviors decreased in both age groups during the experiments. ALC diminished the decrease of these emotional behaviors, especially in rearing behavior in the aged rats. Furthermore, ALC had no effect on body weight gain. These results might reflect one of the main beneficial pharmacological mechanisms of ALC in clinical use.

Acetylcarnitine↗
PubMed1987

Comparative study of tiapride and neuroleptics with anti-dopamine activity on convulsive seizure in mice.

The effects of tiapride on the convulsive seizures induced by pentylenetetrazole, strychnine, picrotoxin and bemegride, and on electric seizure are reported and compared with those of sulpiride, chlorpromazine, haloperidol and reserpine. The number of deaths and intensity of convulsion increased dose-dependently and also with the increase in amplitude of electric shock. Tiapride and a similar compound, sulpiride, did not affect these seizures, whereas chlorpromazine potentiated strychnine-induced and electric seizure. Haloperidol and reserpine potentiated electric seizure, and chlorpromazine and reserpine tended to potentiate bemegride-induced seizure. Reserpine also tended to potentiate pentylenetetrazole-induced seizure. These results suggest that tiapride would be clinically safer than other drugs with anti-dopamine activity, except for sulpiride.

Animals↗
PubMed1987

Effect of long-term dosing with tiapride on brain dopamine receptors and metabolism in rats. Comparative study with sulpiride and haloperidol.

The effects of long-term dosing with tiapride for 21 days on barin dopamine receptors and dopamine turnover were compared with those of sulpiride and haloperidol. Haloperidol caused an increase in both antagonist (3H-spiperone) labeled receptors and agonist (3H-N,n-propylnorapomorphine) labeled ones, whereas tiapride acted on the agonist binding sites and sulpiride acted on the antagonist binding sites. The increases induced by sulpiride were only observed in the striatum, while those induced by tiapride and haloperidol were observed in both the striatum and limbic area. Dopamine and dopamine metabolites in the brain tissues were measured at 2 hr and 3 days after long-term dosing with the drugs as an indicator of dopamine turnover. They were higher at 2 hr and lower at 3 days than those of the saline treated controls; however, the increase at 2 hr was much less than that after single acute dosing with drugs. This suggested that all drugs induced tolerance with regard to dopamine turnover. In these studies, tiapride and sulpiride were less active than haloperidol in the effects on brain dopamine receptors and dopamine turnover. This generally weaker activity of sulpiride and tiapride suggest that the benzamide drugs have fewer side effects such as a tardive dyskinesia, than does haloperidol, even after long-term dosing. Furthermore, a slight difference between the effects of tiapride and sulpiride on the dopamine receptor subtypes in the brain subdivision was suggested.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1981

A new regulatory protein that affects the state of actin polymerization.

A new protein factor that regulates the state of actin polymerization was purified from porcine brain by DNase I-agarose chromatography. The purified protein factor consisted of a 1 : 1 complex of 88,000 dalton polypeptide and actin. When actin was polymerized by salt in the presence of the factor, the steady-state viscosity and the sedimentability were greatly reduced. The extent of the reductions was found to be greater in the presence of Ca2+ than in its absence.

Actins↗
PubMed1981

Phosphorylation of microtubule-associated proteins (MAPs) and pH of the medium control interaction between MAPs and actin filaments.

Interaction of microtubule-associated proteins (MAPs) with actin filaments at neutral pH is inhibited by phosphorylation of MAPs. Phosphorylated MAPs are less potent than unphosphorylated ones in increasing the low-shear viscosity of actin filaments in the neutral pH range. The ability of unphosphorylated MAPs to crosslink actin filaments falls off sharply above pH 7.5. Upon phosphorylation, the crosslinking ability of the MAPs peaks sharply between pH 6.2 and 6.3. Thus, the MAPs-actin interaction can be regulated by phosphorylation of MAPs and small changes in the physiological range of pH.

Actins↗