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Biomedical subjects

E Abe

Publications and source records attributed to E Abe.

At least 163 records · Page 9Linked to original sources
PubMed1983

1 alpha,25-dihydroxyvitamin D3 promotes fusion of mouse alveolar macrophages both by a direct mechanism and by a spleen cell-mediated indirect mechanism.

Extensive fusion was induced in mouse alveolar macrophages by treatment with conditioned media obtained from spleen cell cultures treated with 15 micrograms of phytohemagglutinin or concanavalin A per ml or with 12 nM 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3]. The fusion rate was 80-90% on day 3. In addition, 1 alpha,25(OH)2D3 added directly to alveolar macrophages induced fusion of about 35% of the cells on day 3, whereas direct addition of phytohemagglutinin and concanavalin A did not enhance fusion at all. When conditioned media from spleen cell or T cell cultures treated with 12 nM 1 alpha,25(OH)2D3 were applied to a Sephadex G-100 column, a fusion factor (Mr 37,000-70,000) could be separated from 1 alpha,25(OH)2D3. 1 alpha,25(OH)2D3 induced fusion at 0.012-120 nM in a dose-dependent manner both by direct action and by spleen cell-mediated indirect action, but the fusion rate was always much greater in the latter than in the former at each concentration of the vitamin. Of the vitamin D3 derivatives tested, 1 alpha,25(OH)2D3 was the most potent, followed successively by 1 alpha,24R,25-trihydroxyvitamin D3, 1 alpha-hydroxyvitamin D3, 25-hydroxyvitamin D3, and 24R,25-dihydroxyvitamin D3. These results clearly indicate that 1 alpha,25(OH)2D3 induces fusion of mouse alveolar macrophages by both a direct and an indirect mechanism, the latter mediated by spleen cells, probably by T cells.

Animals↗
PubMed1983

Regulation of terminal differentiation of cultured mouse epidermal cells by 1 alpha,25-dihydroxyvitamin D3.

Terminal differentiation of mouse epidermal cells in primary culture was found to be regulated by 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3), the hormonal form of vitamin D3 produced by sequential hydroxylations in the liver and kidney. Epidermal differentiation was stimulated dose dependently by 1 alpha,25(OH)2D3 at concentrations of 0.12 nM or more. In the presence of the vitamin, stratified foci increased in number and size and contiguous foci coalesced. Basal cells in the treated cultures decreased sharply and underwent differentiation into squamous and enucleated cells which sloughed off into the medium during cultivation. The size and density of the cells became larger and lighter during the course of differentiation. 1 alpha,25(OH)2D3 markedly stimulated formation of a cornified envelope, a structure with chemically stable cross-links formed beneath the plasma membrane. Of several derivatives of vitamin D3 examined, 1 alpha,25(OH)2D3 was the most potent in inducing epidermal differentiation. Stimulation of epidermal differentiation was also observed in low calcium medium. DNA synthesis was inhibited dose dependently by 1 alpha,25(OH)2D3. A specific receptor for 1 alpha,25(OH)2D3 was found in the cytosol fraction of the epidermal cells. Scatchard plot analysis revealed that the receptor has an apparent dissociation constant (Kd value) of 54 pM and maximum binding value (Nmax) of 43 fmol/mg protein. The specificity of the receptor was demonstrated by analog competition in the following order: 1 alpha,25(OH)2D3 much greater than 25-hydroxyvitamin D3 greater than 1 alpha-hydroxyvitamin D3 greater than 24R,25-dihydroxyvitamin D3.

Animals↗
PubMed1983

Functional defect of variant clones of a human myeloid leukemia cell line (HL-60) resistant to 1 alpha,25-dihydroxyvitamin D3.

Two variant clones of a human myeloid leukemia cell line (HL-60) resistant to the active metabolite of vitamin D3, 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3], were isolated from a 1 alpha,25(OH)2D3-sensitive parent clone, and the mechanism of the resistance was examined. When the parent clone was incubated with 120 nM 1 alpha,25(OH)2D3, cell growth was suppressed to half of the control and about half of the cells exhibited phagocytic activity and C3 rosette formation on day 3. The variant clones, however, were resistant to 120 nM 1 alpha,25(OH)2D3. One of the variant clones was also insensitive to other potential inducers such as 12-O-tetradecanoyl-phorbol-13-acetate, actinomycin D, and dimethyl sulfoxide. When the variant clones were incubated with 1 alpha,25(OH)2[3H]D3, they took up much less radioactivity than the parent clone into the whole cells, and into the cytosol protein-bound and chromatin-bound fractions. The variant clones were found to possess reduced amounts of the cytosol receptor protein to which 1 alpha,25(OH)2D3 was specifically bound; but the hormone-receptor complex could be transferred to the chromatin acceptor sites similarly both in the wild type clone and its variant clones, indicating that one of the major defects in the 1 alpha,25(OH)2D3-resistant clones is the reduced amounts of the specific cytosol receptor. These results support the concept that 1 alpha,25(OH)2D3 induces differentiation of human myeloid leukemia cells by a receptor-mediated mechanism.

Calcitriol↗
PubMed1983

1 alpha,25-Dihydroxyvitamin D3 markedly enhances chemically-induced transformation in BALB 3T3 cells.

1 alpha,25-Dihydroxyvitamin D3, a hormonally active form of vitamin D3, enhanced methylcholanthrene-induced transformation in BALB 3T3 cells to a much greater extent than 12-O-tetradecanoylphorbol-13-acetate. This enhancement was probably mediated by a cytosol receptor for 1 alpha,25-dihydroxyvitamin D3 which has an equilibrium constant of 28.4pM and a maximum binding of 32.6 fmol/mg protein.

Animals↗
PubMed1982

1 alpha,25-Dihydroxycholecalciferol and a human myeloid leukaemia cell line (HL-60).

Human promyelocytic leukaemia cells (HL-60) can be induced to differentiate into mature granulocytes in vitro by 1 alpha,25-dihydroxycholecalciferol [1 alpha,25(OH)2D3], the active form of cholecalciferol. The differentiation-associated properties, such as phagocytosis and C3 rosette formation, were induced by as little as 0.12 nM-1 alpha,25(OH)2D3, and, at 12 nM, about half of the cells exhibited differentiation on day 3 of incubation. Concomitantly the viable cell number was decreased to less than half of the control. Among various derivatives of cholecalciferol examined, 1 alpha,25(OH)2D3 and 1 alpha,24R-dihydroxycholecalciferol were the most potent in inducing differentiation, followed successively by 1 alpha,24S-dihydroxycholecalciferol, 1 alpha-hydroxycholecalciferol, 25-hydroxycholecalciferol and 24R,25-dihydroxycholecalciferol. A cytosol protein specifically bound to 1 alpha,25 (OH)2D3 was found in HL-60 cells. Its physical properties closely resembled those found in such target tissues as intestine and parathyroid glands. 1 alpha,25(OH)2D3 bound to the cytosol receptor was transferred quantitatively to the chromatin fraction. The specificity of various derivatives of cholecalciferol in inducing differentiation was well correlated with that of their association with the cytosol receptor. These results are compatible with the hypothesis that the active form of cholecalciferol induces differentiation of human myeloid leukaemia cells by a mechanism similar to that proposed for the classical concept of steroid hormone action.

Binding Sites↗
PubMed1982

Disorders of cholecalciferol metabolism in old egg-laying hens.

It has been reported that the rate of cracked or soft-shelled eggs markedly increases in old laying hens. We investigated the effect of age on cholecalciferol metabolism in different age groups of laying hens. The egg production rate in hens more than 500 days old was maintained within a range of about 70% of that in young hens (230-320 days old), whereas the rate of cracked or soft-shelled eggs increased markedly with age. When kidney homogenates from the different age groups were incubated with [3H]-25-hydroxyvitamin D-3, renal 25-hydroxyvitamin D-3-1 alpha-hydroxylase activity was found to decrease markedly with age. When birds were given intravenously either [3H]-25-hydroxyvitamin D-3 or [3H]-1 alpha,25-dihydroxyvitamin D-3, the accumulation of [3H]-1 alpha,25-dihydroxyvitamin D-3 in plasma and target tissue also decreased with age. Forced molting performed in old hens restored eggshell quality. The treatment also restored, though partially, the in vivo accumulation of [3H]-l alpha,25-dihydroxyvitamin D-3 in the target tissues. These results suggest that the increased rate of cracked or soft-shelled eggs seen in older birds is associated with disorders of vitamin D-3 metabolism.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1981

Vitamin D metabolism and its possible role in the developing chick embryo.

The relationship between bone formation and vitamin D metabolism was investigated in the developing chick embryo. Fertilized White Leghorn eggs were incubated at 38 degrees C in an incubator for 21 days. The fresh weight and calcium content of embryonic tibiae began to increase at day 12 and attained maximal values at day 19. Bone alkaline phosphatase and citrate decarboxylation activities, both of which represent osteoblastic activity, also began to increase at days 10-12, reached maximal values at day 19 and sharply declined thereafter. Both bone enzyme activities were highly correlated with CA2+-binding activity in the chorioallantoic membrane measured by the Chelex 100 assay. When mesonephric and metanephric homogenates were incubated with 25-hydroxy[3H]cholecalciferol, a marked and concomitant increase occurred in the metanephric 1 alpha- and 24-hydroxylase activity after day 14. The production of 1 alpha, 25-dihydroxycholecalciferol attained a maximal value at day 19 and decreased thereafter, whereas that of 24,25-dihydroxycholecalciferol continued to increase until hatching. The production rate of 1 alpha, 25-dihydroxycholecalciferol by the metanephros coincided with the changes in Ca2+-binding activity in the chorioallantoic membrane and osteoblastic activity. Since both intestinal calcium absorption and bone mineral mobilization do not occur in embryonic life, these results support the idea that 1 alpha, 25-dihydroxycholecalciferol may be involved directly in bone formation or induction of a calcium-binding protein in the chorioallantoic membrane.

Allantois↗
PubMed1981

Differentiation of mouse myeloid leukemia cells induced by 1 alpha,25-dihydroxyvitamin D3.

Mouse myeloid leukemia cells can be induced to differentiate into macrophages in vitro by 1 alpha,25-dihydroxyvitamin D3, the active form of vitamin D3. The minimal concentration of 1 alpha,25-dihydroxyvitamin D3 to induce the cell differentiation was 0.12 nM. The degree of cell differentiation in various markers induced by 12 nM 1 alpha,25-dihydroxyvitamin D3 was nearly equivalent to that induced by 1 microM dexamethasone, the most potent known stimulator. Among several markers of the differentiation by 1 alpha,25-dihydroxyvitamin D3, phagocytic activity was induced within 24 hr, and this was followed by induction of lysozyme and locomotive activities. Similar changes were also induced by 0.01-1 microM 1 alpha-hydroxyvitamin D3. 25-Hydroxyvitamin D3 and 24R,25-dihydroxyvitamin D3 showed only weak inducing activity. These results suggest the possibility that, in addition to its wellknown biological activities in enhancing intestinal calcium transport and bone mineral mobilization, 1 alpha, 25-dihydroxyvitamin D3 is involved in the differentiation of bone marrow cells.

Animals↗
PubMed1981

Effect of DL-alpha-tocopherol (vitamin E) on the differentiation of mouse myeloid leukemia cell.

The effect of DL-alpha-tocopherol on the differentiation of the mouse myeloid leukemia cell line (M1) was investigated using fluorometry. The reliability of the fluorometric determination was verified by the mutual overlapping of the curves of disappearance of the radioactivity recovered as alpha-tocopherol and the loss of its fluorescence. alpha-Tocopherol solubilized into the culture medium was relatively stable (t1/2 = 147-168 hr). In corporation of alpha-tocopherol into M1 cells was time- and dose-dependent. Proliferation of M1 cells was never inhibited, but was slightly enhanced by treatment with alpha-tocopherol. alpha-Tocopherol caused a twofold increase in acid-phosphatase activity and slightly inhibited both the spontaneous- and dexamethasone-induced differentiation with respect to adhesion on glass and cell surface-rosette formation. alpha-Tocopherol also induced morphological change, making the shape of M1 cells rounder.

Animals↗
PubMed1981

[Intramuscular pressure and muscle blood flow during and after contraction (author's transl)].

In order to investigate the effects of intramuscular pressure on muscle blood flow changes during and after isometric contraction, experiments were conducted in anesthetized rabbits. Simultaneous measurements of muscle blood flow with a heated thermocouple technique and intramuscular pressure with a 'multi-hole wick catheter' connected to a transducer were done in the quadriceps muscle. The muscle contraction was caused by stimulating the femoral nerve using supramaximal square voltage pulses (7-9V, 0.1 msec). Intramuscular pressure increased linearly in response to various levels of stimulation frequency. At the low levels of frequency in stimuli (1-17 Hz), muscle blood flow during contraction increased continuously and intramuscular pressure was lower than the level of arterial blood pressure. But at the levels of frequency above 25 Hz, intramuscular pressure reached to or exceeded the level of systolic arterial blood pressure and muscle blood flow during contraction decreased continuously. It was suggested that increased intramuscular pressure disturbed muscle blood flow by collapsing the vessels within the muscle. Postcontraction peak flow appeared immediately after contraction caused by high frequent stimuli. This peak flow was not related to the duration of the contraction. Postcontraction hyperemia persisting long after contraction increased proportional to the intensity and duration of the contraction. These findings suggested the postcontraction peak flow was related to mechanical factor, whereas postcontraction hyperemia was to the other mechanism, such as metabolic products.

Animals↗
PubMed1980

A high-affinity cytosol binding protein for 1 alpha,25-dihydroxycholecalciferol in the uterus of Japanese quail.

Cytosol fractions prepared from the uterine mucosa of egg-laying Japanese Quail were analysed for binding of the metabolites of cholecalciferol. When the uterus was incubated at 37 degrees C with various radioactive metabolites of cholecalciferol, the nuclear fraction incorporated only 1 alpha,25-dihydroxy[3H]cholecalciferol. When the uterus was incubated at 0 degree C with 1 alpha,25-dihydroxy[3H]cholecalciferol, most of the radioactivity was found in the cytosol. Translocation of 1 alpha,25-dihydroxy[3H]cholecalciferol from the cytosol to the nucleus was temperature-dependent. The addition of 100-fold excess amounts of unlabelled 1 alpha-25-dihydroxycholecalciferol significantly diminished the nuclear binding of 1 alpha,25-dihydroxy[3H]cholecalciferol. The cytosol fraction contained a 3.5 S macromolecule that specifically binds 1 alpha,25-dihydroxy[3H]cholecalciferol. The dissociation constant was 0.39 nM and the maximal binding was 55 fmol/mg of protein. These results strongly suggest that the uterus in egg-laying birds is a target organ or 1 alpha,25-dihydroxycholecalciferol.

Animals↗