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Biomedical subjects

K Takeda

Publications and source records attributed to K Takeda.

At least 991 records · Page 55Linked to original sources
PubMed1989

Suppression of TNF-stimulated proliferation of diploid fibroblasts and TNF-induced cytotoxicity against transformed fibroblasts by TGF-beta.

Human transforming growth factor-beta (TGF-beta) dose-dependently inhibited proliferation of WI-38 cells, normal human diploid fibroblasts, stimulated by tumor necrosis factor (TNF). Inhibition occurred at 1 ng/ml concentration of TGF-beta. Also, TGF-beta dose-dependently suppressed cytotoxicity of TNF against L-929 cells, murine transformed fibroblasts. The concentration of TNF required for 50% cytolysis of L-929 cells was changed from 30 ng/ml to 350 ng/ml by 10 ng/ml TGF-beta. This suppression was abolished when L-929 cells were treated with actinomycin D or cycloheximide, suggesting that TGF-beta might inhibit the action of TNF via de novo protein synthesis. This response was not due to down regulation of TNF receptors nor to alteration of the affinity of TNF for its receptor.

Animals↗
PubMed1989

A cytokine, lymphocyte blastogenesis inhibitory factor (LBIF), arrests mitogen-stimulated T lymphocytes at early G1 phase with no influence on interleukin 2 production and interleukin 2 receptor light chain expression.

The function of a human cytokine, lymphocyte blastogenesis inhibitory factor (LBIF), was characterized. To this end, LBIF was purified from crude supernatant of U-937 cells, a human macrophage-like cell line, by using fast protein liquid chromatography (FPLC). We demonstrated here that (a) the LBIF preparation completely inhibited phytohemagglutinin (PHA)-stimulated T cell proliferation; (b) however, in PHA-stimulated T lymphocytes LBIF inhibited neither interleukin (IL)2 production nor the expression of IL2 receptor (IL2R) light chain (CD25) which play a critical role for T cell proliferation; (c) LBIF arrested PHA-stimulated T lymphocytes at the G1 phase of cell cycle and inhibited entry into S phase, thus inhibiting lymphocyte proliferation. Wright-Giemsa's staining of the cells showed that PHA/LBIF-stimulated cells were arrested in early G1. In agreement with this result, LBIF strongly inhibited PHA-induced RNA synthesis. Further, LBIF inhibited the induction of the transferrin receptor which is normally expressed at the late G1 phase of the cell cycle. The inhibitory activity of LBIF was reversible. Thus, this study elucidated that LBIF arrests PHA-stimulated T lymphocytes at a point between the stages of IL2 production or IL2R light chain expression (in early G1) and transferrin receptor expression (in late G1). Taken together, these results suggest that there might be a control system of T cell proliferation distinct from the previously reported mechanisms, such as the inhibition of IL2 production or the inhibition of IL2R light chain (CD25) expression, and that LBIF might be an important molecule in the regulation of normal lymphocyte proliferation.

Biological Factors↗
PubMed1989

Circular dichroic study of conformational changes in ovalbumin.

By simulation of the circular dichroic spectra (Greenfield and Fasman (1969] and using reference spectra of Chen et al. (1974), native ovalbumin was estimated to contain 33% alpha-helix, 5% beta-structure, and 62% random coil. Ovalbumin resisted conformational changes in solutions of urea and of SDS. However, guanidine induced transition, starting at about 2 M and completing at about 4.5 M. At concentrations exceeding 4.5 M guanidine, ovalbumin existed as 6-7% alpha-helical, 12-13% beta-structure, and 80-81% random coil. Ovalbumin after denaturation in 6 M guanidine or in 8 M urea (incubated at 4 degrees C for 24 hr) did not recover the native conformation but acquired a new conformation in each case, with a somewhat destabilized helical structure.

Circular Dichroism↗
PubMed1989

Circular dichroic study of conformational changes in ovalbumin induced by modification of sulfhydryl groups and disulfide reduction.

Sulfhydryl groups of ovalbumin were chemically modified under denaturing conditions in the absence and presence of dithiothreitol, and effects on the secondary structure of the protein were investigated by circular dichroic (CD) measurements. The contents of alpha-helix, beta-structure, and "random coil" (unordered, nonrepetitive structure) were estimated by simulation of the CD spectra and using the parameters established by Chen et al. The principal findings were these: (1) Modification of the four free sulfhydryl groups [with 5,5'-dithiobis(2-nitrobenzoic acid), iodoacetate, or iodoacetamide] caused ovalbumin molecule to unfold partially and to undergo primarily helix-to-beta structure transition. (2) Cleavage of the disulfide bond did not lead to a further conformational change in the sulfhydryl-modified ovalbumin. (3) The remaining helical structure existed in a destabilized state with increased chain flexibility, as the modified protein was very susceptible to denaturation by guanidine and urea. (4) Further evidence for increased chain flexibility was provided by the finding that sodium dodecyl sulfate (SDS) induced helix formation in the sulfhydryl-modified, but not native, ovalbumin. And (5), since both nonreduced and reduced proteins, with their sulfhydryl groups blocked, displayed similar transitions in solutions of guanidine, urea, and SDS suggested that the single disulfide bond did not physically constrain the ovalbumin molecule.

Circular Dichroism↗
PubMed1989

Conformational change of bovine serum albumin by heat treatment.

The thermal denaturation of bovine serum albumin (BSA) was studied at pH 2.8 and 7.0 in the range of 2-65 degrees C. The relative proportions of alpha-helix, beta-structure, and disordered structure in the protein conformation were determined as a function of temperature, by the curve-fitting method of circular dichroism spectra. With the rise of temperature at pH 7.0, the proportion of alpha-helix decreased above 30 degrees C and those of beta-structure and disordered structure increased in the same temperature range. The structural change was reversible in the temperature range below 45 degrees C. However, the structural change was partially reversible upon cooling to room temperature subsequent to heating at 65 degrees C. On the other hand, the structural change of BSA at pH 2.8 was completely reversible in the temperature range of 2-65 degrees C, probably because the interactions between domains and between subdomains might disappear due to the acid expansion. The secondary structure of disulfide bridges-cleaved BSA remained unchanged during the heat treatment up to 65 degrees C at pH 2.8 and 7.0.

Animals↗
PubMed1989

Secondary structural changes in the intact and the disulfide bridges cleaved beta-lactoglobulin A and B in solutions of urea, guanidine hydrochloride, and sodium dodecyl sulfate.

The relative proportions of alpha-helix, beta-sheet, and unordered form in beta-lactoglobulin A and B were examined in solutions of urea, guanidine, and sodium dodecyl sulfate (SDS). In the curve-fitting method of circular dichroism (CD) spectra, the reference spectra of the corresponding structures determined by Chen et al. (1974) were modified essentially according to the secondary structure of beta-lactoglobulin B predicted by Creamer et al. (1983), i.e., that the protein has 17% alpha-helix and 41% beta-sheet. The two variants showed no appreciable difference in structural changes. The reduction of disulfide bridges in the proteins increased beta-sheet up to 48% but did not affect the alpha-helical proportion. The alpha-helical proportions of nonreduced beta-lactoglobulin A and B were not affected below 2 M guanidine or below 3 M urea, but those of the reduced proteins began to decrease in much lower concentrations of these denaturants. By contrast, the alpha-helical proportions of the nonreduced and reduced proteins increased to 40-44% in SDS. The beta-sheet proportions of both nonreduced and reduced proteins which remained unaffected even in 6 M guanidine and 9 M urea, decreased to 24-25% in SDS.

Circular Dichroism↗
PubMed1989

Circular dichroic study of the conformational stability of sulfhydryl-blocked bovine serum albumin.

1. The blockage of the single sulfhydryl-group of bovine serum albumin does not alter the secondary structure, although the alpha-helical structure is destabilized since lower concentrations of guanidine and of urea unfold the protein. 2. What happens to the previously helical structure depends upon the reagent used to block the sulfhydryl-group. Bovine serum albumin derivatized with 5,5'-dithiobis-(2-nitrobenzoic acid) and iodoacetate preferentially acquire the beta-structure in high concentrations of guanidine and urea, whereas iodoacetamide-derivatized bovine serum albumin acquires primarily the random coil structure. 3. Part of the helical structure is also lost in 5-6 mM sodium dodecyl sulfate; thionitrobenzoate-bovine serum albumin shows an increase in the random coil, whereas the two alkylated proteins display the increase both in beta-structure and random coil. 4. Carboxymethylation or carboxamidomethylation of fully reduced bovine serum albumin results in a drastic change in the secondary structure of the protein with a substantial decrease in alpha-helix and a corresponding increase in both beta-structure and random coil. These extensively alkylated proteins also display differences in denaturation profiles in solutions of guanidine and urea.

Alkylation↗
PubMed1989

Adenylate kinase of Mycobacterium marinum. Amino acid composition, secondary structure and other aspects.

1. Adenylate kinase purified from Mycobacterium marinum shares homology with the enzyme from mammalian muscle and from other bacteria with respect to amino acid composition, total residues and Mr. 2. However, it differs from others in not containing a free sulfhydryl or disulfide group. 3. It is much more sensitive to inhibition by adenosine (5')pentaphospho(5')adenosine than is the enzyme from other sources. 4. The enzyme contains 24% alpha-helix, 30% beta-structure and 46% random coil.

Adenylate Kinase↗
PubMed1989

A new device for monitoring concentrations of intracellular Ca2+ in CNS preparations and its application to the frog's spinal cord.

For monitoring the changes in intracellular concentrations of Ca2+ in vertebrate CNS neurones in situ, we devised an assembly of two quartz-made optic fibres enclosed in a glass capillary. Esterified fluorescent Ca2+ indicator (quin2/AM) was injected into the motoneuronal pool of the frog's spinal cord, and about 60 min later, the assembly was inserted directly into the same region. Ultraviolet light for exciting the indicator was transmitted through one optic fibre, while the fluorescence emitted from the cells was guided to a photoelectric converter through the other fibre. Administration of Ringer's solution containing some stimulant (KCl, excitatory amino acids) through arterial perfusion, evoked both an increase of fluorescence intensity under excitation light of 340 nm wavelength and a decrease under 380 nm light. Electrical stimulation delivered to a dorsal root provoked equivalent responses in fluorescence; this response is known to be an indicator of an elevation in intracellular concentrations of Ca2+.

Aminoquinolines↗
PubMed1989

Lethal toxicity and adjuvant activities of synthetic TDM and its related compounds in mice.

Trehalose-6,6'-dimycolate (TDM) and its monosaccharide-type analogues were synthesized, and their lethal and adjuvant activities were examined in mice. All the monosaccharide-type analogues with a glucose or N-acetylglucosamine moiety were devoid of lethal toxicity to mice; in particular, D-GlcNAcM(1-deoxy) and D-GlcNM did not cause any loss of body weight at an early stage after intravenous administration as a 9% oil-in-water emulsion. Intraperitoneal administration of D-GlcNAcM(1-deoxy) in aqueous suspension, as well as TDM, could activate macrophages to become tumoricidal against tumour cells, whereas D-GlcNAcM(1-deoxy) in oil emulsion, unlike TDM, caused no granulomatous formation in the lung after intravenous injection. Squalane-treated D-GlcNAcM(1-deoxy) showed significant inhibition of spontaneous lung metastases by B16-BL6 melanoma cells when it was administered twice intratumorally. The non-toxic monosaccharide-type analogue of TDM [D-GlcNAcM(1-deoxy)] was a beneficial adjuvant for the activation of macrophages and the prevention of cancer metastasis.

Adjuvants, Immunologic↗
PubMed1989

Metallothionein-I accumulation in the rat lung following a single paraquat administration.

The ability of paraquat (PQ), a free radical inducible chemical, to increase metallothionein-I (MT-I) content in the tissues was determined using radioimmunoassay. A single dose of PQ into the rat caused a sevenfold increase in pulmonary MT-I concentration on day 1 and its concentration returned to the control level by day 5. Paraquat-induced increase in MT-I was not observed in the kidney, but was seen in the liver. The data show the difference in accumulation of MT-I in liver, kidney and lung after intraperitoneal injection of a high dose of PQ.

Animals↗
PubMed1989

Generalized resistance to thyroid hormone associated with a mutation in the ligand-binding domain of the human thyroid hormone receptor beta.

The syndrome of generalized resistance to thyroid hormone is characterized by elevated circulating levels of thyroid hormone in the presence of an overall eumetabolic state and failure to respond normally to triiodothyronine. We have evaluated a family with inherited generalized resistance to thyroid hormone for abnormalities in the thyroid hormone nuclear receptors. A single guanine----cytosine replacement in the codon for amino acid 340 resulted in a glycine----arginine substitution in the hormone-binding domain of one of two alleles of the patient's thyroid hormone nuclear receptor beta gene. In vitro translation products of this mutant human thyroid hormone nuclear receptor beta gene did not bind triiodothyronine. Thus, generalized resistance to thyroid hormone can result from expression of an abnormal thyroid hormone nuclear receptor molecule.

Alleles↗
PubMed1989

Paraventricular nucleus lesions attenuate the development of hypertension in DOCA/salt-treated rats.

To determine whether paraventricular nucleus (PVN) can play a role in the hypertension in DOCA/salt-treated rats, DOCA/salt hypertension was produced in PVN lesions and sham-operated rats. In lesioned rats, the development of hypertension was significantly attenuated (day 7: 132 +/- 3 v 157 +/- 5 mm Hg, P less than 0.01; day 14: 132 +/- 3 v 157 +/- 5 mm Hg, P less than 0.01; day 21: 189 +/- 2 v 224 +2- 6 mm Hg, P less than 0.01). Lesions lowered systolic blood pressure in even control rats. Mean blood pressure (mBP) from awake free moving rats was also significantly lower in lesioned DOCA/salt-treated rats than those of sham-operated DOCA/salt-treated rats (155 +/- 14 mm Hg v 193 +/- 13, P less than 0.01), while mBP was not different between lesioned and sham-operated control rats. The reduction of mBP by hexamethonium injections was significantly larger in sham-operated DOCA/salt-treated rats than those of lesioned DOCA/salt rats. (-53 +/- 3% v -45 +/- 2, P less than 0.05). Plasma norepinephrine and epinephrine were significantly elevated in DOCA/salt-treated rats, however, PVN lesions inhibited significantly those elevations. 1-Deaminopenicillamine, 4-valine, 8-D-arginine Vasopressin (dPVDAVP) injections did not affect BP and heart rate in all rats. Body weight, water intake, urine volume, urine Na, K, and vasopressin excretion, and urine osmorality were not altered by lesions. These findings suggest that PVN contributes to development of hypertension in DOCA/salt-treated rats with sympathetic nervous activations.

Animals↗
PubMed1989

Transection of aortic depressor nerve fails to raise blood pressure in spontaneously hypertensive rats.

Although central resetting via the aortic depressor nerve (ADN) has been known to occur in spontaneously hypertensive rats, the function of the ADN is not yet clear in these animals. To determine whether a baroreflex via the ADN can act to regulate blood pressure during hypertension, blood pressures were measured following ADN transection in spontaneously hypertensive and normotensive rats, and the reflex changes of heart rate and the sympathetic nerve activity were recorded during the pressor response to phenylephrine infusions. Blood pressures were significantly raised 1 day after ADN transections in normotensive rats and continued so for 7 d. Blood pressures were not changed in sham operated rats. In spontaneously hypertensive rats, ADN transections did not alter blood pressures in comparison with sham operated controls. On the seventh day after transections, all rats were anaesthetised with urethane and pressor responses to phenylephrine were examined. Bradycardic and sympathoinhibitory responses to the elevation of blood pressure caused by phenylephrine infusions were significantly smaller in ADN transectioned normotensive rats than in sham operated controls. In spontaneously hypertensive rats, the bradycardic and sympatho-inhibitory responses were not reduced by ADN transections. These findings suggest that the impaired baroreflex via the ADN can contribute to the development of hypertension in the spontaneously hypertensive rat.

Animals↗